Field demonstration of CO2 leakage detection and potential impacts on groundwater quality at Brackenridge Field Laboratory

NASA Astrophysics Data System (ADS)

Zou, Y.; Yang, C.; Guzman, N.; Delgado, J.; Mickler, P. J.; Horvoka, S.; Trevino, R.

2015-12-01

One concern related to GCS is possible risk of unintended CO2 leakage from the storage formations into overlying potable aquifers on underground sources of drinking water (USDW). Here we present a series of field tests conducted in an alluvial aquifer which is on a river terrace at The University of Texas Brackenridge Field Laboratory. Several shallow groundwater wells were completed to the limestone bedrock at a depth of 6 m and screened in the lower 3 m. Core sediments recovered from the shallow aquifer show that the sediments vary in grain size from clay-rich layers to coarse sandy gravels. Two main types of field tests were conducted at the BFL: single- (or double-) well push-pull test and pulse-like CO2 release test. A single- (or double-) well push-pull test includes three phases: the injection phase, the resting phase and pulling phase. During the injection phase, groundwater pumped from the shallow aquifer was stored in a tank, equilibrated with CO2 gasand then injected into the shallow aquifer to mimic CO2 leakage. During the resting phase, the groundwater charged with CO2 reacted with minerals in the aquifer sediments. During the pulling phase, groundwater was pumped from the injection well and groundwater samples were collected continuously for groundwater chemistry analysis. In such tests, large volume of groundwater which was charged with CO2 can be injected into the shallow aquifer and thus maximize contact of groundwater charged with CO2. Different than a single- (or double-) well push-pull test, a pulse-like CO2 release test for validating chemical sensors for CO2 leakage detection involves a CO2 release phase that CO2 gas was directly bubbled into the testing well and a post monitoring phase that groundwater chemistry was continuously monitored through sensors and/or grounder sampling. Results of the single- (or double-) well push-pull tests conducted in the shallow aquifer shows that the unintended CO2 leakage could lead to dissolution of carbonates and some silicates and mobilization of heavy metals from the aquifer sediments to groundwater, however, such mobilization posed no risks on groundwater quality at this site. The pulse-like tests have demonstrated it is plausible to use chemical sensors for CO2 leakage detection in groundwater.

Numerical modeling of experimental observations on gas formation and multi-phase flow of carbon dioxide in subsurface formations

NASA Astrophysics Data System (ADS)

Pawar, R.; Dash, Z.; Sakaki, T.; Plampin, M. R.; Lassen, R. N.; Illangasekare, T. H.; Zyvoloski, G.

2011-12-01

One of the concerns related to geologic CO2 sequestration is potential leakage of CO2 and its subsequent migration to shallow groundwater resources leading to geochemical impacts. Developing approaches to monitor CO2 migration in shallow aquifer and mitigate leakage impacts will require improving our understanding of gas phase formation and multi-phase flow subsequent to CO2 leakage in shallow aquifers. We are utilizing an integrated approach combining laboratory experiments and numerical simulations to characterize the multi-phase flow of CO2 in shallow aquifers. The laboratory experiments involve a series of highly controlled experiments in which CO2 dissolved water is injected in homogeneous and heterogeneous soil columns and tanks. The experimental results are used to study the effects of soil properties, temperature, pressure gradients and heterogeneities on gas formation and migration. We utilize the Finite Element Heat and Mass (FEHM) simulator (Zyvoloski et al, 2010) to numerically model the experimental results. The numerical models capture the physics of CO2 exsolution, multi-phase fluid flow as well as sand heterogeneity. Experimental observations of pressure, temperature and gas saturations are used to develop and constrain conceptual models for CO2 gas-phase formation and multi-phase CO2 flow in porous media. This talk will provide details of development of conceptual models based on experimental observation, development of numerical models for laboratory experiments and modelling results.

Numerical studies of CO2 and brine leakage into a shallow aquifer through an open wellbore

NASA Astrophysics Data System (ADS)

Wang, Jingrui; Hu, Litang; Pan, Lehua; Zhang, Keni

2018-03-01

Industrial-scale geological storage of CO2 in saline aquifers may cause CO2 and brine leakage from abandoned wells into shallow fresh aquifers. This leakage problem involves the flow dynamics in both the wellbore and the storage reservoir. T2Well/ECO2N, a coupled wellbore-reservoir flow simulator, was used to analyze CO2 and brine leakage under different conditions with a hypothetical simulation model in water-CO2-brine systems. Parametric studies on CO2 and brine leakage, including the salinity, excess pore pressure (EPP) and initially dissolved CO2 mass fraction, are conducted to understand the mechanism of CO2 migration. The results show that brine leakage rates increase proportionally with EPP and inversely with the salinity when EPP varies from 0.5 to 1.5 MPa; however, there is no CO2 leakage into the shallow freshwater aquifer if EPP is less than 0.5 MPa. The dissolved CO2 mass fraction shows an important influence on the CO2 plume, as part of the dissolved CO2 becomes a free phase. Scenario simulation shows that the gas lifting effect will significantly increase the brine leakage rate into the shallow freshwater aquifer under the scenario of 3.89% dissolved CO2 mass fraction. The equivalent porous media (EPM) approach used to model the wellbore flow has been evaluated and results show that the EPM approach could either under- or over-estimate brine leakage rates under most scenarios. The discrepancies become more significant if a free CO2 phase evolves. Therefore, a model that can correctly describe the complex flow dynamics in the wellbore is necessary for investigating the leakage problems.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dobler, Jeremy; Zaccheo, T. Scott; Blume, Nathan

This report describes the development and testing of a novel system, the Greenhouse gas Laser Imaging Tomography Experiment (GreenLITE), for Monitoring, Reporting and Verification (MRV) of CO 2 at Geological Carbon Storage (GCS) sites. The system consists of a pair of laser based transceivers, a number of retroreflectors, and a set of cloud based data processing, storage and dissemination tools, which enable 2-D mapping of the CO 2 in near real time. A system was built, tested locally in New Haven, Indiana, and then deployed to the Zero Emissions Research and Technology (ZERT) facility in Bozeman, MT. Testing at ZERTmore » demonstrated the ability of the GreenLITE system to identify and map small underground leaks, in the presence of other biological sources and with widely varying background concentrations. The system was then ruggedized and tested at the Harris test site in New Haven, IN, during winter time while exposed to temperatures as low as -15 °CºC. Additional testing was conducted using simulated concentration enhancements to validate the 2-D retrieval accuracy. This test resulted in a high confidence in the reconstruction ability to identify sources to tens of meters resolution in this configuration. Finally, the system was deployed for a period of approximately 6 months to an active industrial site, Illinois Basin – Decatur Project (IBDP), where >1M metric tons of CO 2 had been injected into an underground sandstone basin. The main objective of this final deployment was to demonstrate autonomous operation over a wide range of environmental conditions with very little human interaction, and to demonstrate the feasibility of the system for long term deployment in a GCS environment.« less

Development of a 1 x N Fiber Optic Sensor Array for Carbon Sequestration Site Monitoring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Repasky, Kevin

2014-02-01

A fiber sensor array for sub-surface CO 2 concentrations measurements was developed for monitoring geologic carbon sequestration sites. The fiber sensor array uses a single temperature tunable distributed feedback (DFB) laser operating with a nominal wavelength of 2.004 μm. Light from this DFB laser is direct to one of the 4 probes via an in-line 1 x 4 fiber optic switch. Each of the 4 probes are buried and allow the sub-surface CO 2 to enter the probe through Millipore filters that allow the soil gas to enter the probe but keeps out the soil and water. Light from themore » DFB laser interacts with the CO 2 before it is directed back through the in-line fiber optic switch. The DFB laser is tuned across two CO 2 absorption features where a transmission measurement is made allowing the CO 2 concentration to be retrieved. The fiber optic switch then directs the light to the next probe where this process is repeated allowing sub-surface CO 2 concentration measurements at each of the probes to be made as a function of time. The fiber sensor array was deployed for fifty-eight days beginning June 19, 2012 at the Zero Emission Research Technology (ZERT) field site where sub-surface CO 2 concentrations were monitored. Background measurements indicate the fiber sensor array can monitor background levels as low as 1,000 parts per million (ppm). A thirty four day sub-surface release of 0.15 tones CO 2/day began on July 10, 2012. The elevated subsurface CO 2 concentration was easily detected by each of the four probes with values ranging to over 60,000 ppm, a factor of greater than 6 higher than background measurements. The fiber sensor array was also deploy at the Big Sky Carbon Sequestration Partnership (BSCSP) site in north-central Montana between July 9th and August 7th, 2013 where background measurements were made in a remote sequestration site with minimal infrastructure. The project provided opportunities for two graduate students to participate in research directly related to geologic carbon sequestration. Furthermore, commercialization of the technology developed is being pursued with five different companies via the Department of energy SBIR/STTR program« less

Rapid Surface Detection of CO2 Leaks from Geologic Sequestration Sites

NASA Astrophysics Data System (ADS)

Moriarty, D. M.; Krevor, S. C.; Benson, S. M.

2013-12-01

Carbon sequestration is becoming a viable option for global CO2 mitigation but effective monitoring methods are needed assure the carbon dioxide stays underground. Above surface monitoring using a mobile gas analyzer is one such method (e.g. Krevor et al., 2010). The Picarro gas analyzer uses wavelength-scanned cavity ring down spectroscopy to accurately identify concentrations of various atmospheric gases including their isotopic composition. These measurements can then be used for anomaly (leak) detection and source attribution. Leaks are detected by anomalous absolute concentration of CO2 and anomalous δ13C values. Source attribution is determined by the isotopic concentrations of the identified leaking gas. To distinguish between noise from ambient signals and leaks, a method based on mixing ratios has been developed. A newly acquired data set presented here has been collected from a 3.7km2 area with naturally occurring CO2 springs near Green River, Utah. All of the areas of known leakage were readily detected using this method along with several other areas that showed significant signs of leakage. In addition, testing on the Stanford campus has shown that this method is sensitive enough to distinguish between open fields and roadways. Another data set is being collected at Montana State University at the ZERT monitoring test site where an artificial leak has been created for the purpose of testing leak detection and quantification methods. Data collected from this site are being used for (1) assessing of detection levels and how they depend on environmental parameters such as wind speed, and acquisition variables such as sample rate and traverse speed, (2) optimizing acquisition parameters to increase detection levels and increase confidence in leak detection, (3) evaluating the potential for quantifying the magnitude of the leak and (4) spatial data analysis to identify the most probable leak locations.

Increasing shallow groundwater CO2 and limestone weathering, Konza Prairie, USA

USGS Publications Warehouse

Macpherson, G.L.; Roberts, J.A.; Blair, J.M.; Townsend, M.A.; Fowle, D.A.; Beisner, K.R.

2008-01-01

In a mid-continental North American grassland, solute concentrations in shallow, limestone-hosted groundwater and adjacent surface water cycle annually and have increased steadily over the 15-year study period, 1991-2005, inclusive. Modeled groundwater CO2, verified by measurements of recent samples, increased from 10-2.05 atm to 10-1.94 atm, about a 20% increase, from 1991 to 2005. The measured groundwater alkalinity and alkaline-earth element concentrations also increased over that time period. We propose that carbonate minerals dissolve in response to lowered pH that occurs during an annual carbonate-mineral saturation cycle. The cycle starts with low saturation during late summer and autumn when dissolved CO2 is high. As dissolved CO2 decreases in the spring and early summer, carbonates become oversaturated, but oversaturation does not exceed the threshold for precipitation. We propose that groundwater is a CO2 sink through weathering of limestone: soil-generated CO2 is transformed to alkalinity through dissolution of calcite or dolomite. The annual cycle and long-term increase in shallow groundwater CO2 is similar to, but greater than, atmospheric CO2. ?? 2008 Elsevier Ltd. All rights reserved.

Crustal migration of CO2-rich magmatic fluids recorded by tree-ring radiocarbon and seismicity at Mammoth Mountain, CA, USA

USGS Publications Warehouse

Lewicki, Jennifer L.; Hilley, George E.; Shelly, David R.; King, John C.; McGeehin, John P.; Mangan, Margaret T.; Evans, William C.

2014-01-01

Unrest at Mammoth Mountain over the past several decades, manifest by seismicity, ground deformation, diffuse CO2 emissions, and elevated 3He/4He ratios in fumarolic gases has been driven by the release of CO2-rich fluids from basaltic intrusions in the middle to lower crust. Recent unrest included the occurrence of three lower-crustal (32–19 km depth) seismic swarms beneath Mammoth Mountain in 2006, 2008 and 2009 that were consistently followed by peaks in the occurrence rate of shallow (≤10 km depth) earthquakes. We measured 14C in the growth rings (1998–2012) of a tree growing in the largest (∼0.3 km2) area of diffuse CO2 emissions on Mammoth Mountain (the Horseshoe Lake tree kill; HLTK) and applied atmospheric CO2 concentration source area modeling to confirm that the tree was a reliable integrator of magmatic CO2 emissions over most of this area. The tree-ring 14C record implied that magmatic CO2 emissions from the HLTK were relatively stable from 1998 to 2009, nearly doubled from 2009 to 2011, and then declined by the 2012 growing season. The initial increase in CO2 emissions was detected during the growing season that immediately followed the largest (February 2010) peak in the occurrence rate of shallow earthquakes. Migration of CO2-rich magmatic fluids may have driven observed patterns of elevated deep, then shallow seismicity, while the relationship between pore fluid pressures within a shallow (upper 3 km of crust) fluid reservoir and permeability structure of the reservoir cap rock may have controlled the temporal pattern of surface CO2 emissions.

Monitoring a pilot CO2 injection experiment in a shallow aquifer using 3D cross-well electrical resistance tomography

NASA Astrophysics Data System (ADS)

Yang, X.; Lassen, R. N.; Looms, M. C.; Jensen, K. H.

2014-12-01

Three dimensional electrical resistance tomography (ERT) was used to monitor a pilot CO2 injection experiment at Vrøgum, Denmark. The purpose was to evaluate the effectiveness of the ERT method for monitoring the two opposing effects from gas-phase and dissolved CO2 in a shallow unconfined siliciclastic aquifer. Dissolved CO2 increases water electrical conductivity (EC) while gas phase CO2 reduce EC. We injected 45kg of CO2 into a shallow aquifer for 48 hours. ERT data were collected for 50 hours following CO2 injection. Four ERT monitoring boreholes were installed on a 5m by 5m square grid and each borehole had 24 electrodes at 0.5 m electrode spacing at depths from 1.5 m to 13 m. ERT data were inverted using a difference inversion algorithm for bulk EC. 3D ERT successfully detected the CO2 plume distribution and growth in the shallow aquifer. We found that the changes of bulk EC were dominantly positive following CO2 injection, indicating that the effect of dissolved CO2 overwhelmed that of gas phase CO2. The pre-injection baseline resistivity model clearly showed a three-layer structure of the site. The electrically more conductive glacial sand layer in the northeast region are likely more permeable than the overburden and underburden and CO2 plumes were actually confined in this layer. Temporal bulk EC increase from ERT agreed well with water EC and cross-borehole ground penetrating radar data. ERT monitoring offers a competitive advantage over water sampling and GPR methods because it provides 3D high-resolution temporal tomographic images of CO2 distribution and it can also be automated for unattended operation. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC. LLNL IM release#: LLNL-PROC-657944.

Enhanced CO2 uptake at a shallow Arctic Ocean seep field overwhelms the positive warming potential of emitted methane.

PubMed

Pohlman, John W; Greinert, Jens; Ruppel, Carolyn; Silyakova, Anna; Vielstädte, Lisa; Casso, Michael; Mienert, Jürgen; Bünz, Stefan

2017-05-23

Continued warming of the Arctic Ocean in coming decades is projected to trigger the release of teragrams (1 Tg = 10 6 tons) of methane from thawing subsea permafrost on shallow continental shelves and dissociation of methane hydrate on upper continental slopes. On the shallow shelves (<100 m water depth), methane released from the seafloor may reach the atmosphere and potentially amplify global warming. On the other hand, biological uptake of carbon dioxide (CO 2 ) has the potential to offset the positive warming potential of emitted methane, a process that has not received detailed consideration for these settings. Continuous sea-air gas flux data collected over a shallow ebullitive methane seep field on the Svalbard margin reveal atmospheric CO 2 uptake rates (-33,300 ± 7,900 μmol m -2 ⋅d -1 ) twice that of surrounding waters and ∼1,900 times greater than the diffusive sea-air methane efflux (17.3 ± 4.8 μmol m -2 ⋅d -1 ). The negative radiative forcing expected from this CO 2 uptake is up to 231 times greater than the positive radiative forcing from the methane emissions. Surface water characteristics (e.g., high dissolved oxygen, high pH, and enrichment of 13 C in CO 2 ) indicate that upwelling of cold, nutrient-rich water from near the seafloor accompanies methane emissions and stimulates CO 2 consumption by photosynthesizing phytoplankton. These findings challenge the widely held perception that areas characterized by shallow-water methane seeps and/or strongly elevated sea-air methane flux always increase the global atmospheric greenhouse gas burden.

Enhanced CO2 uptake at a shallow Arctic Ocean seep field overwhelms the positive warming potential of emitted methane

PubMed Central

Greinert, Jens; Silyakova, Anna; Vielstädte, Lisa; Casso, Michael; Mienert, Jürgen; Bünz, Stefan

2017-01-01

Continued warming of the Arctic Ocean in coming decades is projected to trigger the release of teragrams (1 Tg = 106 tons) of methane from thawing subsea permafrost on shallow continental shelves and dissociation of methane hydrate on upper continental slopes. On the shallow shelves (<100 m water depth), methane released from the seafloor may reach the atmosphere and potentially amplify global warming. On the other hand, biological uptake of carbon dioxide (CO2) has the potential to offset the positive warming potential of emitted methane, a process that has not received detailed consideration for these settings. Continuous sea−air gas flux data collected over a shallow ebullitive methane seep field on the Svalbard margin reveal atmospheric CO2 uptake rates (−33,300 ± 7,900 μmol m−2⋅d−1) twice that of surrounding waters and ∼1,900 times greater than the diffusive sea−air methane efflux (17.3 ± 4.8 μmol m−2⋅d−1). The negative radiative forcing expected from this CO2 uptake is up to 231 times greater than the positive radiative forcing from the methane emissions. Surface water characteristics (e.g., high dissolved oxygen, high pH, and enrichment of 13C in CO2) indicate that upwelling of cold, nutrient-rich water from near the seafloor accompanies methane emissions and stimulates CO2 consumption by photosynthesizing phytoplankton. These findings challenge the widely held perception that areas characterized by shallow-water methane seeps and/or strongly elevated sea−air methane flux always increase the global atmospheric greenhouse gas burden. PMID:28484018

CO2 dynamics in the Amargosa Desert: Fluxes and isotopic speciation in a deep unsaturated zone

USGS Publications Warehouse

Walvoord, Michelle Ann; Striegl, Robert G.; Prudic, David E.; Stonestrom, David A.

2005-01-01

Natural unsaturated-zone gas profiles at the U.S. Geological Survey's Amargosa Desert Research Site, near Beatty, Nevada, reveal the presence of two physically and isotopically distinct CO2 sources, one shallow and one deep. The shallow source derives from seasonally variable autotrophic and heterotrophic respiration in the root zone. Scanning electron micrograph results indicate that at least part of the deep CO2 source is associated with calcite precipitation at the 110-m-deep water table. We use a geochemical gas-diffusion model to explore processes of CO2 production and behavior in the unsaturated zone. The individual isotopic species 12CO2, 13CO2, and 14CO2 are treated as separate chemical components that diffuse and react independently. Steady state model solutions, constrained by the measured δ13C (in CO2), and δ14C (in CO2) profiles, indicate that the shallow CO2 source from root and microbial respiration composes ∼97% of the annual average total CO2 production at this arid site. Despite the small contribution from deep CO2 production amounting to ∼0.1 mol m−2 yr−1, upward diffusion from depth strongly influences the distribution of CO2 and carbon isotopes in the deep unsaturated zone. In addition to diffusion from deep CO2 production, 14C exchange with a sorbed CO2 phase is indicated by the modeled δ14C profiles, confirming previous work. The new model of carbon-isotopic profiles provides a quantitative approach for evaluating fluxes of carbon under natural conditions in deep unsaturated zones.

Impacts of CO2 Leakage on a Shallow Aquifer System: Laboratory Column Experiments and Reactive Transport Modeling

NASA Astrophysics Data System (ADS)

Ha, Jong Heon; Jeen, Sung-Wook

2017-04-01

Groundwater quality change due to the leakage of CO2 in a shallow aquifer system is an important aspect of environmental impact assessment in a carbon dioxide capture and storage (CCS) site. This study evaluated geochemical changes in a shallow aquifer system resulting from leakage of CO2 through laboratory column experiments and reactive transport modeling. In the column experiments, two columns were set up and filled with the sediment from the Environmental Impact Test (EIT) facility of the Korea CO2 Storage Environmental Management (K-COSEM) Research Center. Groundwater, also collected form the EIT site, was purged with CO2 or Ar gases, and was pumped into the columns with the pumping rates of 200-1000 mL day-1 (0.124-0.62 m day-1). Profile and time-series effluent samplings were conducted to evaluate the spatial and temporal geochemical changes in the aquifer materials upon contact with CO2. The experimental results showed that after injecting CO2-purged groundwater, the pH was decreased, and alkalinity, electrical conductivity (EC) and concentrations of major cations were increased. The spatial and temporal geochemical changes from the column experiments indicate that dissolution of aquifer materials in contact with dissolved CO2 is the major contributor to the changes in groundwater geochemistry. The reactive transport modeling has been conducted to reproduce these geochemical changes in the aquifer system by incorporating dissolution of the dominant aluminosilicate minerals in the aquifer such as microcline, anorthite, albite, and biotite. This study suggests that pH, alkalinity, EC and concentrations of major cations are important monitoring parameters for detecting CO2 leakage in a shallow groundwater aquifer system.

CGILS Phase 2 LES intercomparison of response of subtropical marine low cloud regimes to CO 2 quadrupling and a CMIP3 composite forcing change: Large eddy simulation of cloud feedbacks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blossey, Peter N.; Bretherton, Christopher S.; Cheng, Anning

We extended Phase 1 of the CGILS large-eddy simulation (LES) intercomparison in order to understand if subtropical marine boundary-layer clouds respond to idealized climate perturbations consistently in six LES models. Here the responses to quadrupled carbon dioxide (“fast adjustment”) and to a composite climate perturbation representative of CMIP3 multimodel mean 2×CO 2 near-equilibrium conditions are analyzed. As in Phase 1, the LES is run to equilibrium using specified steady summertime forcings representative of three locations in the Northeast Pacific Ocean in shallow well-mixed stratocumulus, decoupled stratocumulus, and shallow cumulus cloud regimes. Our results are generally consistent with a single-LES studymore » of Bretherton et al. (2013) on which this intercomparison was based. Both quadrupled CO 2 and the composite climate perturbation result in less cloud and a shallower boundary layer for all models in well-mixed stratocumulus and for all but a single LES in decoupled stratocumulus and shallow cumulus, corroborating similar findings from global climate models (GCMs). For both perturbations, the amount of cloud reduction varies across the models, but there is less intermodel scatter than in GCMs. Furthermore, the cloud radiative effect changes are much larger in the stratocumulus-capped regimes than in the shallow cumulus regime, for which precipitation buffering may damp the cloud response. In the decoupled stratocumulus and cumulus regimes, both the CO 2 increase and CMIP3 perturbations reduce boundary-layer decoupling, due to the shallowing of inversion height.« less

CGILS Phase 2 LES intercomparison of response of subtropical marine low cloud regimes to CO 2 quadrupling and a CMIP3 composite forcing change: Large eddy simulation of cloud feedbacks

DOE PAGES

Blossey, Peter N.; Bretherton, Christopher S.; Cheng, Anning; ...

2016-10-27

We extended Phase 1 of the CGILS large-eddy simulation (LES) intercomparison in order to understand if subtropical marine boundary-layer clouds respond to idealized climate perturbations consistently in six LES models. Here the responses to quadrupled carbon dioxide (“fast adjustment”) and to a composite climate perturbation representative of CMIP3 multimodel mean 2×CO 2 near-equilibrium conditions are analyzed. As in Phase 1, the LES is run to equilibrium using specified steady summertime forcings representative of three locations in the Northeast Pacific Ocean in shallow well-mixed stratocumulus, decoupled stratocumulus, and shallow cumulus cloud regimes. Our results are generally consistent with a single-LES studymore » of Bretherton et al. (2013) on which this intercomparison was based. Both quadrupled CO 2 and the composite climate perturbation result in less cloud and a shallower boundary layer for all models in well-mixed stratocumulus and for all but a single LES in decoupled stratocumulus and shallow cumulus, corroborating similar findings from global climate models (GCMs). For both perturbations, the amount of cloud reduction varies across the models, but there is less intermodel scatter than in GCMs. Furthermore, the cloud radiative effect changes are much larger in the stratocumulus-capped regimes than in the shallow cumulus regime, for which precipitation buffering may damp the cloud response. In the decoupled stratocumulus and cumulus regimes, both the CO 2 increase and CMIP3 perturbations reduce boundary-layer decoupling, due to the shallowing of inversion height.« less

Viability of modelling gas transport in shallow injection-monitoring experiment field at Maguelone, France

NASA Astrophysics Data System (ADS)

Basirat, Farzad; Perroud, Hervé; Lofi, Johanna; Denchik, Nataliya; Lods, Gérard; Fagerlund, Fritjof; Sharma, Prabhakar; Pezard, Philippe; Niemi, Auli

2015-04-01

In this study, TOUGH2/EOS7CA model is used to simulate the shallow injection-monitoring experiment carried out at Maguelone, France, during 2012 and 2013. The possibility of CO2 leakage from storage reservoir to upper layers is one of the issues that need to be addressed in CCS projects. Developing reliable monitoring techniques to detect and characterize CO2 leakage is necessary for the safety of CO2 storage in reservoir formations. To test and cross-validate different monitoring techniques, a series of shallow gas injection-monitoring experiments (SIMEx) has been carried out at the Maguelone. The experimental site is documented in Lofi et al [2013]. At the site, a series of nitrogen and one CO2 injection experiment have been carried out during 2012-2013 and different monitoring techniques have been applied. The purpose of modelling is to acquire understanding of the system performance as well as to further develop and validate modelling approaches for gas transport in the shallow subsurface, against the well-controlled data sets. The preliminary simulation of the experiment including the simulation for the Nitrogen injection test in 2012 was presented in Basirat et al [2013]. In this work, the simulations represent the gaseous CO2 distribution and dissolved CO2 within range obtained by monitoring approaches. The Multiphase modelling in combination with geophysical monitoring can be used for process understanding of gas phase migration- and mass transfer processes resulting from gaseous CO2 injection. Basirat, F., A. Niemi, H. Perroud, J. Lofi, N. Denchik, G. Lods, P. Pezard, P. Sharma, and F. Fagerlund (2013), Modeling Gas Transport in the Shallow Subsurface in Maguelone Field Experiment, Energy Procedia, 40, 337-345. Lofi, J., P. Pezard, F. Bouchette, O. Raynal, P. Sabatier, N. Denchik, A. Levannier, L. Dezileau, and R. Certain (2013), Integrated Onshore-Offshore Investigation of a Mediterranean Layered Coastal Aquifer, Groundwater, 51(4), 550-561.

Sleipner vest CO{sub 2} disposal, CO{sub 2} injection into a shallow underground aquifer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baklid, A.; Korbol, R.; Owren, G.

1996-12-31

This paper describes the problem of disposing large amounts of CO{sub 2} into a shallow underground aquifer from an offshore location in the North Sea. The solutions presented is an alternative for CO{sub 2} emitting industries in addressing the growing concern for the environmental impact from such activities. The topside injection facilities, the well and reservoir aspects are discussed as well as the considerations made during establishing the design basis and the solutions chosen. The CO{sub 2} injection issues in this project differs from industry practice in that the CO{sub 2} is wet and contaminated with methane, and further, becausemore » of the shallow depth, the total pressure resistance in the system is not sufficient for the CO{sub 2} to naturally stay in the dense phase region. To allow for safe and cost effective handling of the CO{sub 2}, it was necessary to develop an injection system that gave a constant back pressure from the well corresponding to the output pressure from the compressor, and being independent of the injection rate. This is accomplished by selecting a high injectivity sand formation, completing the well with a large bore, and regulating the dense phase CO{sub 2} temperature and thus the density of the fluid in order to account for the variations in back pressure from the well.« less

Impact of naturally leaking carbon dioxide on soil properties and ecosystems in the Qinghai-Tibet plateau.

PubMed

Zhao, Xiaohong; Deng, Hongzhang; Wang, Wenke; Han, Feng; Li, Chunrong; Zhang, Hui; Dai, Zhenxue

2017-06-07

One of the major concerns for CO 2 capture and storage (CCS) is the potential risk of CO 2 leakage from storage reservoirs on the shallow soil property and vegetation. This study utilizes a naturally occurring CO 2 leaking site in the Qinghai-Tibet Plateau to analog a "leaking CCS site". Our observations from this site indicates that long-term CO 2 invasion in the vadose zone results in variations of soil properties, such as pH fluctuation, slight drop of total organic carbon, reduction of nitrogen and phosphorus, and concentration changes of soluble ions. Simultaneously, XRD patterns of the soil suggest that crystallization of soil is enhanced and mineral contents of calcite and anorthite in soil are increased substantially. Parts of the whole ecosystem such as natural wild plants, soil dwelling animals and microorganisms in shallow soil are affected as well. Under a moderate CO 2 concentration (less than 110000 ppm), wild plant growth and development are improved, while an intensive CO 2 flux over 112000 ppm causes adverse effects on the plant growth, physiological and biochemical system of plants, and crop quality of wheat. Results of this study provide valuable insight for understanding the possible environmental impacts associated with potential CO 2 leakage into shallow sediments at carbon sequestration sites.

Multiple isotopes (O, C, Li, Sr) as tracers of CO2 and brine leakage from CO2-enhanced oil recovery activities in Permian Basin, Texas, USA

NASA Astrophysics Data System (ADS)

Phan, T. T.; Sharma, S.; Gardiner, J. B.; Thomas, R. B.; Stuckman, M.; Spaulding, R.; Lopano, C. L.; Hakala, A.

2017-12-01

Potential CO2 and brine migration or leakage into shallow groundwater is a critical issue associated with CO2 injection at both enhanced oil recovery (EOR) and carbon sequestration sites. The effectiveness of multiple isotope systems (δ18OH2O, δ13C, δ7Li, 87Sr/86Sr) in monitoring CO2 and brine leakage at a CO2-EOR site located within the Permian basin (Seminole, Texas, USA) was studied. Water samples collected from an oil producing formation (San Andres), a deep groundwater formation (Santa Rosa), and a shallow groundwater aquifer (Ogallala) over a four-year period were analyzed for elemental and isotopic compositions. The absence of any change in δ18OH2O or δ13CDIC values of water in the overlying Ogallala aquifer after CO2 injection indicates that injected CO2 did not leak into this aquifer. The range of Ogallala water δ7Li (13-17‰) overlaps the San Andres water δ7Li (13-15‰) whereas 87Sr/86Sr of Ogallala (0.70792±0.00005) significantly differs from San Andres water (0.70865±0.00003). This observation demonstrates that Sr isotopes are much more sensitive than Li isotopes in tracking brine leakage into shallow groundwater at the studied site. In contrast, deep groundwater δ7Li (21-25‰) is isotopically distinct from San Andres produced water; thus, monitoring this intermitted formation water can provide an early indication of CO2 injection-induced brine migration from the underlying oil producing formation. During water alternating with gas (WAG) operations, a significant shift towards more positive δ13CDIC values was observed in the produced water from several of the San Andres formation wells. The carbon isotope trend suggests that the 13C enriched injected CO2 and formation carbonates became the primary sources of dissolved inorganic carbon in the area surrounding the injection wells. Moreover, one-way ANOVA statistical analysis shows that the differences in δ7Li (F(1,16) = 2.09, p = 0.17) and 87Sr/86Sr (F(1,18) = 4.47, p = 0.05) values of shallow groundwater collected before and during the WAG period are not statistically significant. The results to date suggest that the water chemistry of shallow groundwater has not been influenced by the CO2 injection activities. The efficacy of each isotope system as a monitoring tool will be evaluated and discussed using a Bayesian mixing model.

The Role of Optimality in Characterizing CO2 Seepage from Geological Carbon Sequestration Sites

NASA Astrophysics Data System (ADS)

Cortis, A.; Oldenburg, C. M.; Benson, S. M.

2007-12-01

Storage of large amounts of carbon dioxide (CO2) in deep geological formations for greenhouse-gas mitigation is gaining momentum and moving from its conceptual and testing stages towards widespread application. In this talk we explore various optimization strategies for characterizing surface leakage (seepage) using near-surface measurement approaches such as accumulation chambers and eddy covariance towers. Seepage characterization objectives and limitations need to be defined carefully from the outset especially in light of large natural background variations that can mask seepage. The cost and sensitivity of seepage detection are related to four critical length scales pertaining to the size of the: (1) region that needs to be monitored; (2) footprint of the measurement approach; (3) main seepage zone; and (4) region in which concentrations or fluxes are influenced by seepage. Seepage characterization objectives may include one or all of the tasks of detecting, locating, and quantifying seepage. Each of these tasks has its own optimal strategy. Detecting and locating seepage in a region in which there is no expected or preferred location for seepage nor existing evidence for seepage requires monitoring on a fixed grid, e.g., using eddy covariance towers. The fixed-grid approaches needed to detect seepage are expected to require large numbers of eddy covariance towers for large-scale geologic CO2 storage. Once seepage has been detected and roughly located, seepage zones and features can be optimally pinpointed through a dynamic search strategy, e.g., employing accumulation chambers and/or soil-gas sampling. Quantification of seepage rates can be done through measurements on a localized fixed grid once the seepage is pinpointed. Background measurements are essential for seepage detection in natural ecosystems. Artificial neural networks are considered as regression models useful for distinguishing natural system behavior from anomalous behavior suggestive of CO2 seepage without need for detailed understanding of natural system processes. Because of the local extrema in CO2 fluxes and concentrations in natural systems, simple steepest-descent algorithms are not effective and evolutionary computation algorithms are proposed as a paradigm for dynamic monitoring networks to pinpoint CO2 seepage areas. This work was carried out within the ZERT project, funded by the Assistant Secretary for Fossil Energy, Office of Sequestration, Hydrogen, and Clean Coal Fuels, National Energy Technology Laboratory, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

Hydrogeochemical alteration of groundwater due to a CO2 injection test into a shallow aquifer in Northeast Germany

NASA Astrophysics Data System (ADS)

Dethlefsen, Frank; Peter, Anita; Hornbruch, Götz; Lamert, Hendrik; Garbe-Schönberg, Dieter; Beyer, Matthias; Dietrich, Peter; Dahmke, Andreas

2014-05-01

The accidental release of CO2 into potable aquifers, for instance as a consequence of a leakage out of a CO2 store site, can endanger drinking water resources due to the induced geochemical processes. A 10-day CO2 injection experiment into a shallow aquifer was carried out in Wittstock (Northeast Germany) in order to investigate the geochemical impact of a CO2 influx into such an aquifer and to test different monitoring methods. Information regarding the site investigation, the injection procedure monitoring setup, and first geochemical monitoring results are described in [1]. Apart from the utilization of the test results to evaluate monitoring approaches [2], further findings are presented on the evaluation of the geophysical monitoring [3], and the monitoring of stable carbon isotopes [4]. This part of the study focuses of the hydrogeochemical alteration of groundwater due to the CO2 injection test. As a consequence of the CO2 injection, major cations were released, i.e. concentrations increased, whereas major anion concentrations - beside bicarbonate - decreased, probably due to increased anion sorption capacity at variably charged exchange sites of minerals. Trace element concentrations increased as well significantly, whereas the relative concentration increase was far larger than the relative concentration increase of major cations. Furthermore, geochemical reactions show significant spatial heterogeneity, i.e. some elements such as Cr, Cu, Pb either increased in concentration or remained at stable concentrations with increasing TIC at different wells. Statistical analyses of regression coefficients confirm the different spatial reaction patterns at different wells. Concentration time series at single wells give evidence, that the trace element release is pH dependent, i.e. trace elements such as Zn, Ni, Co are released at pH of around 6.2-6.6, whereas other trace elements like As, Cd, Cu are released at pH of 5.6-6.4. [1] Peter, A., et al., Investigation of the geochemical impact of CO2; on shallow groundwater: design and implementation of a CO2; injection test in Northeast Germany. Environmental Earth Sciences, 2012. 67(2): p. 335-349. [2] Dethlefsen, F., et al., Monitoring approaches for detecting and evaluating CO2 and formation water leakages into near-surface aquifers. Energy Procedia, 2013. 37(0): p. 4886-4893. [3] Lamert, H., et al., Feasibility of geoelectrical monitoring and multiphase modeling for process understanding of gaseous CO2; injection into a shallow aquifer. Environmental Earth Sciences, 2012. 67(2): p. 447-462. [4] Schulz, A., et al., Monitoring of a simulated CO2 leakage in a shallow aquifer using stable carbon isotopes. Environmental Science & Technology, 2012. 46(20): p. 11243-11250.

CO 2 Storage in Shallow Underground and Surface Coal Mines: Challenges and Opportunities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Romanov, Vyacheslav N.; Ackman, Terry E.; Soong, Yee

2009-02-01

For coal to be a viable energy source, its excessive CO 2 emissions must be curtailed. Sequestration of CO 2 and other greenhouse gases is a possibility, but success therein is preceded by a significant number of challenges. Perhaps the most onerous is the tradeoff between using deep mines that would better trap CO 2 against using shallower options that are more economical to access. In confronting this issue, a group of U.S. Department of Energy researchers argue that recent advances in the understanding of materials afforded by nanoscale mechanistic models point in a promising direction to develop better sequestrationmore » technologies.« less

Impact of naturally leaking carbon dioxide on soil properties and ecosystems in the Qinghai-Tibet plateau

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Xiaohong; Deng, Hongzhang; Wang, Wenke

One of the major concerns for CO 2 capture and storage (CCS) is the potential risk of CO 2 leakage from storage reservoirs on the shallow soil property and vegetation. This study utilizes a naturally occurring CO 2 leaking site in the Qinghai-Tibet Plateau to analog a “leaking CCS site”. Our observations from this site indicates that long-term CO 2 invasion in the vadose zone results in variations of soil properties, such as pH fluctuation, slight drop of total organic carbon, reduction of nitrogen and phosphorus, and concentration changes of soluble ions. Simultaneously, XRD patterns of the soil suggest thatmore » crystallization of soil is enhanced and mineral contents of calcite and anorthite in soil are increased substantially. Parts of the whole ecosystem such as natural wild plants, soil dwelling animals and microorganisms in shallow soil are affected as well. Under a moderate CO 2 concentration (less than 110000 ppm), wild plant growth and development are improved, while an intensive CO2 flux over 112000 ppm causes adverse effects on the plant growth, physiological and biochemical system of plants, and crop quality of wheat. Results of this study provide valuable insight for understanding the possible environmental impacts associated with potential CO 2 leakage into shallow sediments at carbon sequestration sites.« less

Impact of naturally leaking carbon dioxide on soil properties and ecosystems in the Qinghai-Tibet plateau

DOE PAGES

Zhao, Xiaohong; Deng, Hongzhang; Wang, Wenke; ...

2017-06-07

One of the major concerns for CO 2 capture and storage (CCS) is the potential risk of CO 2 leakage from storage reservoirs on the shallow soil property and vegetation. This study utilizes a naturally occurring CO 2 leaking site in the Qinghai-Tibet Plateau to analog a “leaking CCS site”. Our observations from this site indicates that long-term CO 2 invasion in the vadose zone results in variations of soil properties, such as pH fluctuation, slight drop of total organic carbon, reduction of nitrogen and phosphorus, and concentration changes of soluble ions. Simultaneously, XRD patterns of the soil suggest thatmore » crystallization of soil is enhanced and mineral contents of calcite and anorthite in soil are increased substantially. Parts of the whole ecosystem such as natural wild plants, soil dwelling animals and microorganisms in shallow soil are affected as well. Under a moderate CO 2 concentration (less than 110000 ppm), wild plant growth and development are improved, while an intensive CO2 flux over 112000 ppm causes adverse effects on the plant growth, physiological and biochemical system of plants, and crop quality of wheat. Results of this study provide valuable insight for understanding the possible environmental impacts associated with potential CO 2 leakage into shallow sediments at carbon sequestration sites.« less

Regional-scale advective, diffusive, and eruptive dynamics of CO2 and brine leakage through faults and wellbores

NASA Astrophysics Data System (ADS)

Jung, Na-Hyun; Han, Weon Shik; Han, Kyungdoe; Park, Eungyu

2015-05-01

Regional-scale advective, diffusive, and eruptive transport dynamics of CO2 and brine within a natural analogue in the northern Paradox Basin, Utah, were explored by integrating numerical simulations with soil CO2 flux measurements. Deeply sourced CO2 migrates through steeply dipping fault zones to the shallow aquifers predominantly as an aqueous phase. Dense CO2-rich brine mixes with regional groundwater, enhancing CO2 dissolution. Linear stability analysis reveals that CO2 could be dissolved completely within only 500 years. Assigning lower permeability to the fault zones induces fault-parallel movement, feeds up-gradient aquifers with more CO2, and impedes down-gradient fluid flow, developing anticlinal CO2 traps at shallow depths (<300 m). The regional fault permeability that best reproduces field spatial CO2 flux variation is estimated 1 × 10-17 ≤ kh < 1 × 10-16 m2 and 5 × 10-16 ≤ kv < 1 × 10-15 m2. The anticlinal trap serves as an essential fluid source for eruption at Crystal Geyser. Geyser-like discharge sensitively responds to varying well permeability, radius, and CO2 recharge rate. The cyclic behavior of wellbore CO2 leakage decreases with time.

A shallow subsurface controlled release facility in Bozeman, Montana, USA, for testing near surface CO2 detection techniques and transport models

USGS Publications Warehouse

Spangler, L.H.; Dobeck, L.M.; Repasky, K.S.; Nehrir, A.R.; Humphries, S.D.; Keith, C.J.; Shaw, J.A.; Rouse, J.H.; Cunningham, A.B.; Benson, S.M.; Oldenburg, C.M.; Lewicki, J.L.; Wells, A.W.; Diehl, J.R.; Strazisar, B.R.; Fessenden, J.E.; Rahn, T.A.; Amonette, J.E.; Barr, J.L.; Pickles, W.L.; Jacobson, J.D.; Silver, E.A.; Male, E.J.; Rauch, H.W.; Gullickson, K.S.; Trautz, R.; Kharaka, Y.; Birkholzer, J.; Wielopolski, L.

2010-01-01

A controlled field pilot has been developed in Bozeman, Montana, USA, to study near surface CO2 transport and detection technologies. A slotted horizontal well divided into six zones was installed in the shallow subsurface. The scale and CO2 release rates were chosen to be relevant to developing monitoring strategies for geological carbon storage. The field site was characterized before injection, and CO2 transport and concentrations in saturated soil and the vadose zone were modeled. Controlled releases of CO2 from the horizontal well were performed in the summers of 2007 and 2008, and collaborators from six national labs, three universities, and the U.S. Geological Survey investigated movement of CO2 through the soil, water, plants, and air with a wide range of near surface detection techniques. An overview of these results will be presented. ?? 2009 The Author(s).

Return of the coral reef hypothesis - Basin to shelf partitioning of CaCO3 and its effect on atmospheric CO2

NASA Technical Reports Server (NTRS)

Opdyke, Bradley N.; Walker, James C. G.

1992-01-01

CaCO3 deposition rates in shallow water are assumed to vary in a sawtoothed manner about a long-term average deposition rate of 8 x 10 exp 12 mol/yr. It is proposed that rising sea level serves as the driving mechanism for changing the locus of CaCO3 deposition from deep sea to shallow shelf. Deposition on the shelves occurs when sea level is rising, while shelf carbonates dissolve when sea level is falling. It is shown that this mechanism alone can account for variations of atmospheric CO2 and can contribute to the pelagic carbonate dissolution cycles observed in the equatorial Pacific.

Intermediate-Scale Experimental Study to Improve Fundamental Understanding of Attenuation Capacity for Leaking CO2 in Heterogeneous Shallow Aquifers

NASA Astrophysics Data System (ADS)

Plampin, Michael R.; Porter, Mark L.; Pawar, Rajesh J.; Illangasekare, Tissa H.

2017-12-01

To assess the risks of Geologic Carbon Sequestration (GCS), it is crucial to understand the fundamental physicochemical processes that may occur if and when stored CO2 leaks upward from a deep storage reservoir into the shallow subsurface. Intermediate-scale experiments allow for improved understanding of the multiphase evolution processes that control CO2 migration behavior in the subsurface, because the boundary conditions, initial conditions, and porous media parameters can be better controlled and monitored in the laboratory than in field settings. For this study, a large experimental test bed was designed to mimic a cross section of a shallow aquifer with layered geologic heterogeneity. As water with aqueous CO2 was injected into the system to mimic a CO2-charged water leakage scenario, the spatiotemporal evolution of the multiphase CO2 plume was monitored. Similar experiments were performed with two different sand combinations to assess the relative effects of different types of geologic facies transitions on the CO2 evolution processes. Significant CO2 attenuation was observed in both scenarios, but by fundamentally different mechanisms. When the porous media layers had very different permeabilities, attenuation was caused by local accumulation (structural trapping) and slow redissolution of gas phase CO2. When the permeability difference between the layers was relatively small, on the other hand, gas phase continually evolved over widespread areas near the leading edge of the aqueous plume, which also attenuated CO2 migration. This improved process understanding will aid in the development of models that could be used for effective risk assessment and monitoring programs for GCS projects.

CO2 Leakage-Induced Shallow Aquifer Contaminations and Associated Health Risk Assessment.

NASA Astrophysics Data System (ADS)

Kim, C. Y.; Han, W. S.; Park, E.; Choung, S.; Piao, J.; Han, G.; Tianfu, X.

2016-12-01

Leakage of stored CO2 from designated deep formation could degrade portable groundwater quality in overlaying shallow aquifers. Dissolution of leaked CO2 causes to reduction of pH and alters dominant geochemical reactions, which ultimately enhances mobility of toxic heavy metals in shallow aquifer. In this study, among various toxic heavy metals, mobilization of As and U were focused because these metals are considered to be cancer potency factor when human being continuously exposes for long period. For this reason, it is critical to evaluate relationship between the amount of leaked CO2 into shallow aquifer and a degree of mobility in As and U. In the end, cancer risk to human body were quantified with probabilistic approach after accounting for shallow groundwater velocity, pumping rate from residential well, geologic heterogeneity. For this study, two-dimensional reactive transport models were developed. Geologic heterogeneity was accounted with three interbedded rock types, which consisted of sandstone, As and U bearing shale, and carbonate rocks, respectively. Within these three-rock types, variability includes changes in permeability, porosity, a type of minerals, and its volume fraction, accounting for both physical and chemical heterogeneities Finally, human health risk is calculated through multiplying cancer potency factor by average daily dose, which is obtained after acquiring for both As and U concentrations profile at residential well through reactive transport modeling. As per variability, a series of human health risks were calculated. Quantification of risk in conjunction with sensitivity analysis aids to evaluate a list of geologic parameters enhancing human health risk.

Heterogeneity-enhanced gas phase formation in shallow aquifers during leakage of CO2-saturated water from geologic sequestration sites

NASA Astrophysics Data System (ADS)

Plampin, Michael R.; Lassen, Rune N.; Sakaki, Toshihiro; Porter, Mark L.; Pawar, Rajesh J.; Jensen, Karsten H.; Illangasekare, Tissa H.

2014-12-01

A primary concern for geologic carbon storage is the potential for leakage of stored carbon dioxide (CO2) into the shallow subsurface where it could degrade the quality of groundwater and surface water. In order to predict and mitigate the potentially negative impacts of CO2 leakage, it is important to understand the physical processes that CO2 will undergo as it moves through naturally heterogeneous porous media formations. Previous studies have shown that heterogeneity can enhance the evolution of gas phase CO2 in some cases, but the conditions under which this occurs have not yet been quantitatively defined, nor tested through laboratory experiments. This study quantitatively investigates the effects of geologic heterogeneity on the process of gas phase CO2 evolution in shallow aquifers through an extensive set of experiments conducted in a column that was packed with layers of various test sands. Soil moisture sensors were utilized to observe the formation of gas phase near the porous media interfaces. Results indicate that the conditions under which heterogeneity controls gas phase evolution can be successfully predicted through analysis of simple parameters, including the dissolved CO2 concentration in the flowing water, the distance between the heterogeneity and the leakage location, and some fundamental properties of the porous media. Results also show that interfaces where a less permeable material overlies a more permeable material affect gas phase evolution more significantly than interfaces with the opposite layering.

Crustal CO2 liberation during the 2006 eruption and earthquake events at Merapi volcano, Indonesia

NASA Astrophysics Data System (ADS)

Troll, Valentin R.; Hilton, David R.; Jolis, Ester M.; Chadwick, Jane P.; Blythe, Lara S.; Deegan, Frances M.; Schwarzkopf, Lothar M.; Zimmer, Martin

2012-06-01

High-temperature volcanic gas is widely considered to originate from ascending, mantle-derived magma. In volcanic arc systems, crustal inputs to magmatic gases mainly occur via subducted sediments in the mantle source region. Our data from Merapi volcano, Indonesia imply, however, that during the April-October 2006 eruption significant quantities of CO2 were added from shallow crustal sources. We show that prior to the 2006 events, summit fumarole gas δ13C(CO2) is virtually constant (δ13C1994-2005 = -4.1 ± 0.3‰), but during the 2006 eruption and after the shallow Yogyakarta earthquake of late May, 2006 (M6.4; hypocentres at 10-15 km depth), carbon isotope ratios increased to -2.4 ± 0.2‰. This rise in δ13C is consistent with considerable addition of crustal CO2 and coincided with an increase in eruptive intensity by a factor of ˜3 to 5. We postulate that this shallow crustal volatile input supplemented the mantle-derived volatile flux at Merapi, intensifying and sustaining the 2006 eruption. Late-stage volatile additions from crustal contamination may thus provide a trigger for explosive eruptions independently of conventional magmatic processes.

An estimate of gas emissions and magmatic gas content from Kilauea volcano

USGS Publications Warehouse

Greenland, L.P.; Rose, William I.; Stokes, J.B.

1985-01-01

Emission rates of CO2 have been measured at Kilauea volcano, Hawaii, in the east-rift eruptive plume and CO2 and SO2 have been measured in the plume from the noneruptive fumaroles in the summit caldera. These data yield an estimate of the loading of Kilauean eruptive gases to the atmosphere and suggest that such estimates may be inferred directly from measured lava volumes. These data, combined with other chemical and geologic data, suggest that magma arrives at the shallow summit reservoir containing (wt.%) 0.32% H2O, 0.32% CO2 and 0.09% S. Magma is rapidly degassed of most of its CO2 in the shallow reservoir before transport to the eruption site. Because this summit degassing yields a magma saturated and in equilibrium with volatile species and because transport of the magma to the eruption site occurs in a zone no shallower than the summit reservoir, we suggest that eruptive gases from Kilauea characteristically should be one of two types: a 'primary' gas from fresh magma derived directly from the mantle and a carbon-depleted gas from magma stored in the summit reservoir. ?? 1995.

Potential impacts of leakage from deep CO2 geosequestration on overlying freshwater aquifers.

PubMed

Little, Mark G; Jackson, Robert B

2010-12-01

Carbon Capture and Storage may use deep saline aquifers for CO(2) sequestration, but small CO(2) leakage could pose a risk to overlying fresh groundwater. We performed laboratory incubations of CO(2) infiltration under oxidizing conditions for >300 days on samples from four freshwater aquifers to 1) understand how CO(2) leakage affects freshwater quality; 2) develop selection criteria for deep sequestration sites based on inorganic metal contamination caused by CO(2) leaks to shallow aquifers; and 3) identify geochemical signatures for early detection criteria. After exposure to CO(2), water pH declines of 1-2 units were apparent in all aquifer samples. CO(2) caused concentrations of the alkali and alkaline earths and manganese, cobalt, nickel, and iron to increase by more than 2 orders of magnitude. Potentially dangerous uranium and barium increased throughout the entire experiment in some samples. Solid-phase metal mobility, carbonate buffering capacity, and redox state in the shallow overlying aquifers influence the impact of CO(2) leakage and should be considered when selecting deep geosequestration sites. Manganese, iron, calcium, and pH could be used as geochemical markers of a CO(2) leak, as their concentrations increase within 2 weeks of exposure to CO(2).

Controlled CO2 injection into a shallow aquifer and leakage detection monitoring practices at the K-COSEM site, Korea

NASA Astrophysics Data System (ADS)

Lee, S. S.; Joun, W.; Ju, Y. J.; Ha, S. W.; Jun, S. C.; Lee, K. K.

2017-12-01

Artificial carbon dioxide injection into a shallow aquifer system was performed with two injection types imitating short- and long-term CO2 leakage events into a shallow aquifer. One is pulse type leakage of CO2 (6 hours) under a natural hydraulic gradient (0.02) and the other is long-term continuous injection (30 days) under a forced hydraulic gradient (0.2). Injection and monitoring tests were performed at the K-COSEM site in Eumseong, Korea where a specially designed well field had been installed for artificial CO2 release tests. CO2-infused and tracer gases dissolved groundwater was injected through a well below groundwater table and monitoring were conducted in both saturated and unsaturated zones. Real-time monitoring data on CO2 concentration and hydrochemical parameters, and periodical measurements of several gas tracers (He, Ar, Kr, SF6) were obtained. The pulse type short-term injection test was carried out prior to the long-term injection test. Results of the short-term injection test, under natural hydraulic gradient, showed that CO2 plume migrated along the preferential pathway identified through hydraulic interference tests. On the other hand, results of the long-term injection test indicated the CO2 plume migration path was aligned to the forced hydraulic gradient. Compared to the short-term test, the long-term injection formed detectable CO2 concentration change in unsaturated wellbores. Recovery data of tracer gases made breakthrough curves compatible to numerical simulation results. The monitoring results indicated that detection of CO2 leakage into groundwater was more effectively performed by using a pumping and monitoring method in order to capture by-passing plume. With this concept, an effective real-time monitoring method was proposed. Acknowledgement: Financial support was provided by the "R&D Project on Environmental Management of Geologic CO2storage" from the KEITI (Project number : 2014001810003)

Scoping Alternatives for Negative Emission Technologies. FRACCC - Possible Routes to Biomass-Derived Carbon Injection in Shallow Aquifers?

NASA Astrophysics Data System (ADS)

Correa Silva, R.; Larter, S.

2016-12-01

Atmospheric CO2 capture into biomass is one of the capture options for negative emission technologies, although proposed sequestration systems such as the permanent burial of total fresh biomass, algal lipids or soil amendment with biochar are yet to be successfully demonstrated as effective at scale. In the context of carbon sequestration, shallow geological reservoirs have not been exhaustively explored, even though they pose, away from groundwater protection zones, potentially low implementation cost, and geographically abundant potential carbon storage reservoirs. Typical carbon storage vectors considered, such as CO2 and biochar, are not suitable for shallow aquifer disposal, due either to cap rock containment requirements, or shallow aquifer CO2 densities, or issues related to formation damage from solid particles. Thus, a cost-effective technology, aimed at converting biomass into a large-scale carbon vector fit-for-disposal in shallow formations could be significant, linking promising carbon capture and containment strategies. In this work, we discuss the development of unconventional carbon vectors for subsurface storage in the form of Functionalized, Refractory and Aqueous Compatible Carbon Compounds (FRACCC), as a potential alternative negative emission technology (Larter et al., 2010). The concept is based on CO2 capture into microbial and algal biomass, followed by the modification of biomass constituents through facile chemical reactions aimed at rendering the biomass efficiently into a stable, biologically refractory but water soluble form, similar in some regards, to dissolved organic matter in the oceans, then sequestering the material in geological settings. As the injected material is not buoyant, containment specifications are more modest than for CO2 injection and potentially, more reservoirs could be accessible! This work analyses the technological, economic and societal implications of such potential FRACCC technologies, and make an assessment of whether such routes are likely to be technically, economically and politically viable.

Characterizing near-surface CO2 conditions before injection - Perspectives from a CCS project in the Illinois Basin, USA

USGS Publications Warehouse

Locke, R.A.; Krapac, I.G.; Lewicki, J.L.; Curtis-Robinson, E.

2011-01-01

The Midwest Geological Sequestration Consortium is conducting a large-scale carbon capture and storage (CCS) project in Decatur, Illinois, USA to demonstrate the ability of a deep saline formation to store one million tonnes of carbon dioxide (CO2) from an ethanol facility. Beginning in early 2011, CO2 will be injected at a rate of 1,000 tonnes/day for three years into the Mount Simon Sandstone at a depth of approximately 2,100 meters. An extensive Monitoring, Verification, and Accounting (MVA) program has been undertaken for the Illinois Basin Decatur Project (IBDP) and is focused on the 0.65 km2 project site. Goals include establishing baseline conditions to evaluate potential impacts from CO2 injection, demonstrating that project activities are protective of human health and the environment, and providing an accurate accounting of stored CO2. MVA efforts are being conducted pre-, during, and post- CO2 injection. Soil and net CO2 flux monitoring has been conducted for more than one year to characterize near-surface CO2 conditions. More than 2,200 soil CO2 flux measurements have been manually collected from a network of 118 soil rings since June 2009. Three ring types have been evaluated to determine which type may be the most effective in detecting potential CO 2 leakage. Bare soil, shallow-depth rings were driven 8 cm into the ground and were prepared to minimize surface vegetation in and near the rings. Bare soil, deep-depth rings were prepared similarly, but were driven 46 cm. Natural-vegetation, shallow-depth rings were driven 8 cm and are most representative of typical vegetation conditions. Bare-soil, shallow-depth rings had the smallest observed mean flux (1.78 ??mol m-2 s-1) versus natural-vegetation, shallow-depth rings (3.38 ??mol m-2 s-1). Current data suggest bare ring types would be more sensitive to small CO2 leak signatures than natural ring types because of higher signal to noise ratios. An eddy covariance (EC) system has been in use since June 2009. Baseline data from EC monitoring is being used to characterize pre-injection conditions, and may then be used to detect changes in net exchange CO2 fluxes (Fc) that could be the result of CO2 leakage into the near-surface environment during or following injection. When injection at IBDP begins, soil and net CO2 monitoring efforts will have established a baseline of near-surface conditions that will be important to help demonstrate the effectiveness of storage activities. ?? 2011 Published by Elsevier Ltd.

Extreme diel dissolved oxygen and carbon cycles in shallow vegetated lakes.

PubMed

Andersen, Mikkel R; Kragh, Theis; Sand-Jensen, Kaj

2017-09-13

A common perception in limnology is that shallow lakes are homogeneously mixed owing to their small water volume. However, this perception is largely gained by downscaling knowledge from large lakes to their smaller counterparts. Here we show that shallow vegetated lakes (less than 0.6 m), in fact, undergo recurring daytime stratification and nocturnal mixing accompanied by extreme chemical variations during summer. Dense submerged vegetation effectively attenuates light and turbulence generating separation between warm surface waters and much colder bottom waters. Photosynthesis in surface waters produces oxygen accumulation and CO 2 depletion, whereas respiration in dark bottom waters causes anoxia and CO 2 accumulation. High daytime pH in surface waters promotes precipitation of CaCO 3 which is re-dissolved in bottom waters. Nocturnal convective mixing re-introduces oxygen into bottom waters for aerobic respiration and regenerated inorganic carbon into surface waters, which supports intense photosynthesis. Our results reconfigure the basic understanding of local environmental gradients in shallow lakes, one of the most abundant freshwater habitats globally. © 2017 The Author(s).

Modulating the band structure and sub-bandgap absorption of Co-hyperdoped silicon by co-doping with shallow-level elements

NASA Astrophysics Data System (ADS)

Dong, Xiao; Fang, Xiuxiu; Wang, Yongyong; Song, Xiaohui; Lu, Zhansheng

2018-06-01

Hyperdoped group-III elements can lower the Fermi energy in the band structures of Co-hyperdoped silicon. When the Co-to-X (X = B, Al, Ga) ratio is 2:1, the intermediate band (IB) in the bandgap includes the Fermi energy and is partially filled by electrons, which is in accordance with the requirement of an IB material. The hyperdoped X atoms can cause the blueshift of the sub-bandgap absorption of the compound compared with the material with no shallow-level elements, which is due to the enlargement of the electronic excitation energy of the Co,X-co-doped silicon.

Global Sampling for Integrating Physics-Specific Subsystems and Quantifying Uncertainties of CO 2 Geological Sequestration

DOE PAGES

Sun, Y.; Tong, C.; Trainor-Guitten, W. J.; ...

2012-12-20

The risk of CO 2 leakage from a deep storage reservoir into a shallow aquifer through a fault is assessed and studied using physics-specific computer models. The hypothetical CO 2 geological sequestration system is composed of three subsystems: a deep storage reservoir, a fault in caprock, and a shallow aquifer, which are modeled respectively by considering sub-domain-specific physics. Supercritical CO 2 is injected into the reservoir subsystem with uncertain permeabilities of reservoir, caprock, and aquifer, uncertain fault location, and injection rate (as a decision variable). The simulated pressure and CO 2/brine saturation are connected to the fault-leakage model as amore » boundary condition. CO 2 and brine fluxes from the fault-leakage model at the fault outlet are then imposed in the aquifer model as a source term. Moreover, uncertainties are propagated from the deep reservoir model, to the fault-leakage model, and eventually to the geochemical model in the shallow aquifer, thus contributing to risk profiles. To quantify the uncertainties and assess leakage-relevant risk, we propose a global sampling-based method to allocate sub-dimensions of uncertain parameters to sub-models. The risk profiles are defined and related to CO 2 plume development for pH value and total dissolved solids (TDS) below the EPA's Maximum Contaminant Levels (MCL) for drinking water quality. A global sensitivity analysis is conducted to select the most sensitive parameters to the risk profiles. The resulting uncertainty of pH- and TDS-defined aquifer volume, which is impacted by CO 2 and brine leakage, mainly results from the uncertainty of fault permeability. Subsequently, high-resolution, reduced-order models of risk profiles are developed as functions of all the decision variables and uncertain parameters in all three subsystems.« less

Developing a Robust Geochemical and Reactive Transport Model to Evaluate Possible Sources of Arsenic at the CO2 Sequestration Natural Analog Site in Chimayo, New Mexico

EPA Science Inventory

Migration of carbon dioxide (CO₂) from deep storage formations into shallow drinking water aquifers is a possible system failure related to geologic CO₂ sequestration. A CO₂ leak may cause mineral precipitation/dissolution reactions, changes in a...

Continuous CO2 gas monitoring to clarify natural pattern and artificial leakage signals

NASA Astrophysics Data System (ADS)

Joun, W.; Ha, S. W.; Joo, Y. J.; Lee, S. S.; Lee, K. K.

2017-12-01

Continuous CO2 gas monitoring at shallow aquifer is significant for early detection and immediate handling of an aquifer impacted by leaking CO2 gas from the sequestration reservoir. However, it is difficult to decide the origin of CO2 gas because detected CO2 includes not only leaked CO2 but also naturally emitted CO2. We performed CO2 injection and monitoring tests in a shallow aquifer. Before the injection of CO2 infused water, we have conducted continuous monitoring of multi-level soil CO2 gas concentration and physical parameters such as temperature, humidity, pressure, wind speed and direction, and precipitation. The monitoring data represented that CO2 gas concentrations in unsaturated soil zone borehole showed differences at depths and daily variation (360 to 6980 ppm volume). Based on the observed data at 5 m and 8 m depths, vertical flux of gas was calculated as 0.471 L/min (LPM) for inflow from 5 m to 8 m and 9.42E-2 LPM for outflow from 8 m to 5 m. The numerical and analytical models were used to calculate the vertical flux of gas and to compare with observations. The results showed that pressure-based modeling could not explain the rapid change of CO2 gas concentration in borehole. Acknowledgement Financial support was provided by the "R&D Project on Environmental Management of Geologic CO2 Storage" from the KEITI (Project Number: 2014001810003)

Brine Flow Up a Borehole Caused by Pressure Perturbation From CO2 Storage: Static and Dynamic Evaluations

EPA Science Inventory

Industrial-scale storage of CO2 in saline sedimentary basins will cause zones of elevated pressure, larger than the CO2 plume itself. If permeable conduits (e.g., leaking wells) exist between the injection reservoir and overlying shallow aquifers, brine could be pushed upwards al...

DIAGNOSTIC MONITORING OF BIOGEOCHEMICAL INTERACTIONS OF A SHALLOW AQUIFER IN RESPONSE TO A CO2 LEAK

EPA Science Inventory

Results from these coupled laboratory and field experiments will greatly improve our understanding of the geochemical and microbiological reactions under low pH - high CO2 stress. We anticipate that this research will: (1) provide criteria for site selection for geological CO2...

Modeling of Near-Surface Leakage and Seepage of CO2 for Risk Characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oldenburg, Curtis M.; Unger, Andre A.J.

2004-02-18

The injection of carbon dioxide (CO2) into deep geologic carbon sequestration sites entails risk that CO2 will leak away from the primary storage formation and migrate upwards to the unsaturated zone from which it can seep out of the ground. We have developed a coupled modeling framework called T2CA for simulating CO2 leakage and seepage in the subsurface and in the atmospheric surface layer. The results of model simulations can be used to calculate the two key health, safety, and environmental (HSE) risk drivers, namely CO2 seepage flux and nearsurface CO2 concentrations. Sensitivity studies for a subsurface system with amore » thick unsaturated zone show limited leakage attenuation resulting in correspondingly large CO2 concentrations in the shallow subsurface. Large CO2 concentrations in the shallow subsurface present a risk to plant and tree roots, and to humans and other animals in subsurface structures such as basements or utility vaults. Whereas CO2 concentrations in the subsurface can be high, surfacelayer winds reduce CO2 concentrations to low levels for the fluxes investigated. We recommend more verification and case studies be carried out with T2CA, along with the development of extensions to handle additional scenarios such as calm conditions, topographic effects, and catastrophic surface-layer discharge events.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Y.; Tong, C.; Trainor-Guitten, W. J.

The risk of CO 2 leakage from a deep storage reservoir into a shallow aquifer through a fault is assessed and studied using physics-specific computer models. The hypothetical CO 2 geological sequestration system is composed of three subsystems: a deep storage reservoir, a fault in caprock, and a shallow aquifer, which are modeled respectively by considering sub-domain-specific physics. Supercritical CO 2 is injected into the reservoir subsystem with uncertain permeabilities of reservoir, caprock, and aquifer, uncertain fault location, and injection rate (as a decision variable). The simulated pressure and CO 2/brine saturation are connected to the fault-leakage model as amore » boundary condition. CO 2 and brine fluxes from the fault-leakage model at the fault outlet are then imposed in the aquifer model as a source term. Moreover, uncertainties are propagated from the deep reservoir model, to the fault-leakage model, and eventually to the geochemical model in the shallow aquifer, thus contributing to risk profiles. To quantify the uncertainties and assess leakage-relevant risk, we propose a global sampling-based method to allocate sub-dimensions of uncertain parameters to sub-models. The risk profiles are defined and related to CO 2 plume development for pH value and total dissolved solids (TDS) below the EPA's Maximum Contaminant Levels (MCL) for drinking water quality. A global sensitivity analysis is conducted to select the most sensitive parameters to the risk profiles. The resulting uncertainty of pH- and TDS-defined aquifer volume, which is impacted by CO 2 and brine leakage, mainly results from the uncertainty of fault permeability. Subsequently, high-resolution, reduced-order models of risk profiles are developed as functions of all the decision variables and uncertain parameters in all three subsystems.« less

Modelled interglacial carbon cycle dynamics during the Holocene, the Eemian and Marine Isotope Stage (MIS) 11

NASA Astrophysics Data System (ADS)

Kleinen, Thomas; Brovkin, Victor; Munhoven, Guy

2016-11-01

Trends in the atmospheric concentration of CO2 during three recent interglacials - the Holocene, the Eemian and Marine Isotope Stage (MIS) 11 - are investigated using an earth system model of intermediate complexity, which we extended with process-based modules to consider two slow carbon cycle processes - peat accumulation and shallow-water CaCO3 sedimentation (coral reef formation). For all three interglacials, model simulations considering peat accumulation and shallow-water CaCO3 sedimentation substantially improve the agreement between model results and ice core CO2 reconstructions in comparison to a carbon cycle set-up neglecting these processes. This enables us to model the trends in atmospheric CO2, with modelled trends similar to the ice core data, forcing the model only with orbital and sea level changes. During the Holocene, anthropogenic CO2 emissions are required to match the observed rise in atmospheric CO2 after 3 ka BP but are not relevant before this time. Our model experiments show a considerable improvement in the modelled CO2 trends by the inclusion of the slow carbon cycle processes, allowing us to explain the CO2 evolution during the Holocene and two recent interglacials consistently using an identical model set-up.

Rapid detection and characterization of surface CO2 leakage through the real-time measurement of δ13C signatures in CO2 flux from the ground

NASA Astrophysics Data System (ADS)

Krevor, S.; Perrin, J.; Esposito, A.; Rella, C.; Benson, S. M.

2009-12-01

A portable stable carbon isotope ratio analyzer for carbon dioxide, based on wavelength scanned cavity ringdown spectroscopy, has been used to detect and characterize an intentional leakage of CO2 from an underground pipeline at the ZERT experimental facility in Bozeman, Montana. Rapid (~1 hour) walking surveys of the entire 100m x 100m site were collected using this mobile, real-time instrument. The resulting concentration and 13C isotopic abundance maps were processed using simple yet powerful analysis techniques, permitting not only the identification of specific leakage locations, but providing the ability to distinguish petrogenic sources of CO2 from biogenic sources. At the site an approximately 100-meter horizontal well has been drilled below an alfalfa field at a depth between 1-3 meters below the surface. The well has perforations along the central 70 meters of the well. The overlying strata are highly permeable sand, silt, and topsoil. The flora consists generally of long grasses and was cut to a height of less than 6 inches before the start of the experiment. For 30 days starting July 15, 2009, CO2 was injected at a rate of 0.2 tonnes per day. The injection rate is designed to simulate leakage from a mature storage reservoir at an annual rate of between .001 and .01%. The isotopic composition of the gas from the tank is at δ13C signature of approximately -52‰, far more negative than either atmospheric (approx. -8‰) or CO2 from soil respiration (approx. -26‰) at the site. The CO2 isotopic and concentration measurements were taken with a Picarro WS-CRDS analyzer with 1/8” tubing connected to a sampling inlet. Simultaneous with CO2 concentrations (including 13C), position data was logged using a GPS receiver. Datapoints are taken around every second. The analyzer was powered using batteries and housed in a conventional garden cart. The surveys consisted of traverses of the site along the length of the pipeline and extending out 100 meters on either side of the pipeline with the end of the gas inlet tube approximate 9 cm above the ground at a walking speed of 1-2m/sec. This simulates the type of survey that could be easily performed if the actual or potential site of a leak was known to within an area on the order of 100 square kilometers or less, the scale of expected industrial CO2 sequestration operations. The surveys were performed both during the day and during the evening when CO2 flux due to respiration from the soil is markedly different. Keeling plots were used to characterize the spatially varying 13C composition of ground source CO2 across the site. A map constructed from this data shows that CO2 flux from sources of leakage was characterized by a δ 13C of -40‰ or less whereas locations away from the leakage spots had much higher δ 13C signatures, -25‰ or higher. The distinct isotopic signature allows for a clear discernment between leakage of petrogenic CO2 and that of natural CO2 fluxes from soil respiration. This is particularly valuable in the circumstance where the leak is slow enough that it could not be identified from CO2 concentration or flux changes above the natural background signal alone.

Comparative carbon cycle dynamics of the present and last interglacial

NASA Astrophysics Data System (ADS)

Brovkin, Victor; Brücher, Tim; Kleinen, Thomas; Zaehle, Sönke; Joos, Fortunat; Roth, Raphael; Spahni, Renato; Schmitt, Jochen; Fischer, Hubertus; Leuenberger, Markus; Stone, Emma J.; Ridgwell, Andy; Chappellaz, Jérôme; Kehrwald, Natalie; Barbante, Carlo; Blunier, Thomas; Dahl Jensen, Dorthe

2016-04-01

Changes in temperature and carbon dioxide during glacial cycles recorded in Antarctic ice cores are tightly coupled. However, this relationship does not hold for interglacials. While climate cooled towards the end of both the last (Eemian) and present (Holocene) interglacials, CO2 remained stable during the Eemian while rising in the Holocene. We identify and review twelve biogeochemical mechanisms of terrestrial (vegetation dynamics and CO2 fertilization, land use, wildfire, accumulation of peat, changes in permafrost carbon, subaerial volcanic outgassing) and marine origin (changes in sea surface temperature, carbonate compensation to deglaciation and terrestrial biosphere regrowth, shallow-water carbonate sedimentation, changes in the soft tissue pump, and methane hydrates), which potentially may have contributed to the CO2 dynamics during interglacials but which remain not well quantified. We use three Earth System Models (ESMs) of intermediate complexity to compare effects of selected mechanisms on the interglacial CO2 and δ13CO2 changes, focusing on those with substantial potential impacts: namely carbonate sedimentation in shallow waters, peat growth, and (in the case of the Holocene) human land use. A set of specified carbon cycle forcings could qualitatively explain atmospheric CO2 dynamics from 8 ka BP to the pre-industrial. However, when applied to Eemian boundary conditions from 126 to 115 ka BP, the same set of forcings led to disagreement with the observed direction of CO2 changes after 122 ka BP. This failure to simulate late-Eemian CO2 dynamics could be a result of the imposed forcings such as prescribed CaCO3 accumulation and/or an incorrect response of simulated terrestrial carbon to the surface cooling at the end of the interglacial. These experiments also reveal that key natural processes of interglacial CO2 dynamics - shallow water CaCO3 accumulation, peat and permafrost carbon dynamics - are not well represented in the current ESMs. Global-scale modeling of these long-term carbon cycle components started only in the last decade, and uncertainty in parameterization of these mechanisms is a main limitation in the successful modeling of interglacial CO2 dynamics.

Integrated Framework for Assessing Impacts of CO₂ Leakage on Groundwater Quality and Monitoring-Network Efficiency: Case Study at a CO₂ Enhanced Oil Recovery Site.

PubMed

Yang, Changbing; Hovorka, Susan D; Treviño, Ramón H; Delgado-Alonso, Jesus

2015-07-21

This study presents a combined use of site characterization, laboratory experiments, single-well push-pull tests (PPTs), and reactive transport modeling to assess potential impacts of CO2 leakage on groundwater quality and leakage-detection ability of a groundwater monitoring network (GMN) in a potable aquifer at a CO2 enhanced oil recovery (CO2 EOR) site. Site characterization indicates that failures of plugged and abandoned wells are possible CO2 leakage pathways. Groundwater chemistry in the shallow aquifer is dominated mainly by silicate mineral weathering, and no CO2 leakage signals have been detected in the shallow aquifer. Results of the laboratory experiments and the field test show no obvious damage to groundwater chemistry should CO2 leakage occur and further were confirmed with a regional-scale reactive transport model (RSRTM) that was built upon the batch experiments and validated with the single-well PPT. Results of the RSRTM indicate that dissolved CO2 as an indicator for CO2 leakage detection works better than dissolved inorganic carbon, pH, and alkalinity at the CO2 EOR site. The detection ability of a GMN was assessed with monitoring efficiency, depending on various factors, including the natural hydraulic gradient, the leakage rate, the number of monitoring wells, the aquifer heterogeneity, and the time for a CO2 plume traveling to the monitoring well.

Fundamental Study on the Dynamics of Heterogeneity-Enhanced CO2 Gas Evolution in the Shallow Subsurface During Possible Leakage from Deep Geologic Storage Sites

NASA Astrophysics Data System (ADS)

Plampin, M. R.; Lassen, R. N.; Sakaki, T.; Pawar, R.; Jensen, K.; Illangasekare, T. H.

2013-12-01

A concern for geologic carbon sequestration is the potential for CO2 stored in deep geologic formations to leak upward into shallow freshwater aquifers where it can have potentially detrimental impacts to the environment and human health. Understanding the mechanisms of CO2 exsolution, migration and accumulation (collectively referred to as 'gas evolution') in the shallow subsurface is critical to predict and mitigate the environmental impacts. During leakage, CO2 can move either as free-phase or as a dissolved component of formation brine. CO2 dissolved in brine may travel upward into shallow freshwater systems, and the gas may be released from solution. In the shallow aquifer, the exsolved gas may accumulate near interfaces between soil types, and/or create flow paths that allow the gas to escape through the vadose zone to the atmosphere. The process of gas evolution in the shallow subsurface is controlled by various factors, including temperature, dissolved CO2 concentration, water pressure, background water flow rate, and geologic heterogeneity. However, the conditions under which heterogeneity controls gas phase evolution have not yet been precisely defined and can therefore not yet be incorporated into models used for environmental risk assessment. The primary goal of this study is to conduct controlled laboratory experiments to help fill this knowledge gap. With this as a goal, a series of intermediate-scale laboratory experiments were conducted to observe CO2 gas evolution in porous media at multiple scales. Deionized water was saturated with dissolved CO2 gas under a specified pressure (the saturation pressure) before being injected at a constant volumetric flow rate into the bottom of a 1.7 meter-tall by 5.7 centimeter-diameter column or a 2.4 meter-tall by 40 centimeter-wide column that were both filled with sand in various heterogeneous packing configurations. Both test systems were initially saturated with fresh water and instrumented with soil moisture sensors to monitor the evolution of gas phase through time by measuring the average water content in small sampling volumes of soil. Tensiometers allowed for observation of water pressure through space and time in the test systems, and a computer-interfaced electronic scale continuously monitored the outflow of water from the top of the two test columns. Several packing configurations with five different types of sands were used in order to test the effects of various pore size contrasts and interface shapes on the evolution of the gas phase near soil texture transitions in the heterogeneous packings. Results indicate that: (1) heterogeneity affects gas phase evolution patterns within a predictable range of conditions quantified by the newly introduced term 'oversaturation,' (2) soil transition interfaces where less permeable material overlies more permeable material have a much more pronounced effect on gas evolution than interfaces with opposite orientations, and (3) anticlines (or stratigraphic traps) cause significantly greater gas accumulation than horizontal interfaces. Further work is underway to apply these findings to more realistic, two-dimensional scenarios, and to assess how well existing numerical models can capture these processes.

Propagation of vent CO2 in a subtropical shallow-water ecosystem assessed by stable carbon isotopes

NASA Astrophysics Data System (ADS)

Cheng, Y. F.; Chen, C. T. A.; Liao, Y. M.; Lin, Y. S.

2016-02-01

Carbon cycle of the ocean plays an important role in the global change associated with the emission of CO2. Anthropogenic CO2 dissolves in seawater, changes carbon chemistry of the ocean, and affects marine life in different and complicated ways. In this study, we investigated stable carbon isotope systematics of a shallow-water hydrothermal field near the Kueishantao Islet off NE Taiwan, which has vent gas composition dominated by CO2 and world record breaking low pH hydrothermal fluids. By studying this natural laboratory of ocean acidification, we aim at clarifying to which extent the high dosage of CO2 propagates in the subtropical shallow-water ecosystem, and how it affects the carbon cycle. Samples of seawater and suspended particles were collected from stations of two nearshore-offshore transects, one with hydrothermal vents at the nearshore end (Transect M, 1230 m long) and the other serving as the baseline (Transect B, 1560 m long). Surface seawater of Transect M showed increasing pH in the offshore direction, from 5.8 at the vent mouths to 7.6 at the most distant station. In contrast, pH of surface water decreased seaward from 8.0 to 7.8 in Transect B. The δ13C values of the vent CO2 averaged -6.4‰, consistent with the range attributed to mantle CO2. Seawater DIC δ13C values of Transect M were 13C-depleted (as negative as -2.5‰) at the vent mouths, and became increasingly 13C-enriched till 0.7‰ at the most distant station. This pattern is in clear contrast to that of Transect B, the DIC δ13C values of which decreased from 0.7 to 0.6 ‰ in the offshore direction. We concluded that the vent CO2 has propagated in the surface ocean at least >700 m away from the hydrothermal field. Our next step is to explore how the vent CO2 affects the stable carbon isotopes of particulate organic matter, and to assess the effect of vent CO2 using quantitative approaches.

Exploring for geothermal resource in a dormant volcanic system: The Haleakala Southwest Rift Zone, Maui, Hawai'i

NASA Astrophysics Data System (ADS)

Martini, B. A.; Lewicki, J. L.; Kennedy, B. M.; Lide, C.; Oppliger, G.; Drakos, P. S.

2011-12-01

Suites of new geophysical and geochemical surveys provide compelling evidence for geothermal resource at the Haleakala Southwest Rift Zone (HSWRZ) on Maui Island, Hawai'i. Ground-based gravity (~400 stations) coupled with heli-borne magnetics (~1500 line kilometers) define both deep and shallow fractures/faults while also delineating potentially widespread subsurface hydrothermal alteration on the lower flanks (below approximately 1800 feet a.s.l.). Multi-level, upward continuation calculations and 2-D gravity and magnetic modeling provide information on source depths, but lack of lithologic information leaves ambiguity in the estimates. Lithology and physical property data from future drilling will improve these interpretations. Additionally, several well-defined gravity lows (possibly vent zones) lie coincident with magnetic highs suggesting the presence of dike intrusions at depth; a potentially young source of heat for a modern geothermal system. Soil CO2 fluxes were measured along transects across geophysically-defined faults and fractures as well as young cinder cones along the HSWRZ; a weak anomalous flux signal was observed at one young cinder cone location. Dissolved inorganic carbon concentrations and δ13C compositions and 3He/4He values measured in several shallow groundwater samples indicate addition of magmatic CO2 and He to the groundwater system. The general lack of observed magmatic surface CO2 signals on the HSWRZ is therefore likely due to a combination of groundwater 'scrubbing' of CO2 and relatively high biogenic surface CO2 fluxes that mask magmatic CO2. Similar surveys at the Puna geothermal field on the Kilauea Lower East Rift Zone (KLERZ) also showed a lack of surface CO2 flux signals attributed to a magmatic source, while aqueous geochemistry indicated contribution of magmatic CO2 and He to shallow groundwaters at both Maui and Puna. As magma has been intercepted in geothermal drilling at the Puna field, the lack of measured surface CO2 flux associated with upflow of magmatic fluids here is likely due to the aforementioned 'scrubbing' from extensive groundwater flow, as well as high background biogenic CO2 flux. Deep, temperature gradient core holes have been sited based on these geophysical and geochemical datasets.

CO 2 leakage impacts on shallow groundwater. Field-scale reactive-transport simulations informed by observations at a natural analog site

DOE PAGES

Keating, Elizabeth H.; Hakala, J. Alexandra; Viswanathan, Hari; ...

2013-03-01

It is challenging to predict the degree to which shallow groundwater might be affected by leaks from a CO 2 sequestration reservoir, particularly over long time scales and large spatial scales. In this study observations at a CO 2 enriched shallow aquifer natural analog were used to develop a predictive model which is then used to simulate leakage scenarios. This natural analog provides the opportunity to make direct field observations of groundwater chemistry in the presence of elevated CO 2, to collect aquifer samples and expose them to CO 2 under controlled conditions in the laboratory, and to test themore » ability of multiphase reactive transport models to reproduce measured geochemical trends at the field-scale. The field observations suggest that brackish water entrained with the upwelling CO 2 are a more significant source of trace metals than in situ mobilization of metals due to exposure to CO 2. The study focuses on a single trace metal of concern at this site: U. Experimental results indicate that cation exchange/adsorption and dissolution/precipitation of calcite containing trace amounts of U are important reactions controlling U in groundwater at this site, and that the amount of U associated with calcite is fairly well constrained. Simulations incorporating these results into a 3-D multi-phase reactive transport model are able to reproduce the measured ranges and trends between pH, pCO 2, Ca, total C, U and Cl -at the field site. Although the true fluxes at the natural analog site are unknown, the cumulative CO 2 flux inferred from these simulations are approximately equivalent to 37.8E-3 MT, approximately corresponding to a .001% leak rate for injection at a large (750 MW) power plant. The leakage scenario simulations suggest that if the leak only persists for a short time the volume of aquifer contaminated by CO 2-induced mobilization of U will be relatively small, yet persistent over 100 a.« less

Earth's partial pressure of CO2 over the past 100-500 Ma; evidence from Ce anomalies in mostly shallow seas (less than 200 m) as recorded in carbonate sediments, 2

NASA Technical Reports Server (NTRS)

Liu, Y.-G.; Reinhardt, J. W.; Schmitt, R. A.

1993-01-01

We reported the direct relationship of Ce anomalies recorded in 0.2-119 Ma CaCO3 sediments (Ce(sup A*)) to the Ce anomalies in the parental Pacific deep seawater (Ce(sup A)) and their relationship to atmospheric P(CO2) relative to present P(CO2). We have analyzed continental CaCO3 samples that were deposited in ancient oceans and shallow sea platforms less than 200 m over central USA, central Europe, China, and Saudi-Arabia/Oman. We have plotted Ce(sup A*) over the 75-470 Ma interval. For P(CO2) calculations, we assumed as a reference standard the less than 200 m mixed Pacific Ocean with a Ce(sup A) geometric mean of 0.22 and a range of 0.10-0.43. Because P(CO2) values obtained from reliable deep Pacific Ocean carbonates in the 67-119 Ma interval were similar to the present P(CO2) values, we have drawn a 1.0 ratio for that interval. Although there is considerable scatter among the approximately 150 Ma carbonates, the average Ce(sup A*) value suggests that P(CO2) increased during the early Cretaceous, from 1.0X at approximately 120 Ma to about 1.4X at approximately 150 Ma. At approximately 250 Ma, the average Ce(sup A*) in 13 shallow sea China carbonates agrees well with the single and more reliable approximately 250 Ma China carbonate deposited in deeper open platform. We suggest that P(CO2) ranged from 1.4-1.7X over the Jurassic and Triassic periods. At approximately 280 Ma, three China carbonates deposited in deeper open platforms and therefore considered more reliable are consistent with a European carbonate, which indicate Ce(sup A) and P(CO2) values similar to the present. The minimum at this time corresponds to the great Permo-Carboniferous glaciation. From 280 Ma to 470 Ma, the trend favors increasing Ce(sup A*) and corresponding P(CO2) values between 1.9-2.7X, with a more reliable value closer to 2.7X at 430 Ma because of the unknown higher temperature in the less than 100 m seawater over continental USA which was located just south of the equator at approximately 430 Ma.

3D ultra-high resolution seismic imaging of shallow Solfatara crater in Campi Flegrei (Italy): New insights on deep hydrothermal fluid circulation processes.

PubMed

De Landro, Grazia; Serlenga, Vincenzo; Russo, Guido; Amoroso, Ortensia; Festa, Gaetano; Bruno, Pier Paolo; Gresse, Marceau; Vandemeulebrouck, Jean; Zollo, Aldo

2017-06-13

Seismic tomography can be used to image the spatial variation of rock properties within complex geological media such as volcanoes. Solfatara is a volcano located within the Campi Flegrei, a still active caldera, so it is of major importance to characterize its level of activity and potential danger. In this light, a 3D tomographic high-resolution P-wave velocity image of the shallow central part of Solfatara crater is obtained using first arrival times and a multiscale approach. The retrieved images, integrated with the resistivity section and temperature and the CO 2 flux measurements, define the following characteristics: 1. A depth-dependent P-wave velocity layer down to 14 m, with V p  < 700 m/s typical of poorly-consolidated tephra and affected by CO 2 degassing; 2. An intermediate layer, deepening towards the mineralized liquid-saturated area (Fangaia), interpreted as permeable deposits saturated with condensed water; 3. A deep, confined high velocity anomaly associated with a CO 2 reservoir. These features are expression of an area located between the Fangaia, water saturated and replenished from deep aquifers, and the main fumaroles, superficial relief of the deep rising CO 2 flux. Therefore, the changes in the outgassing rate greatly affect the shallow hydrothermal system, which can be used as a "mirror" of fluid migration processes occurring at depth.

CO 2 Leakage Into Shallow Aquifers: Modeling CO 2 Gas Evolution and Accumulation at Interfaces of Heterogeneity

DOE PAGES

Porter, Mark L.; Plampin, Michael; Pawar, Rajesh; ...

2014-12-31

The physicochemical processes associated with CO 2 leakage into shallow aquifer systems are complex and span multiple spatial and time scales. Continuum-scale numerical models that faithfully represent the underlying pore-scale physics are required to predict the long-term behavior and aid in risk analysis regarding regulatory and management decisions. This study focuses on benchmarking the numerical simulator, FEHM, with intermediate-scale column experiments of CO 2 gas evolution in homogeneous and heterogeneous sand configurations. Inverse modeling was conducted to calibrate model parameters and determine model sensitivity to the observed steady-state saturation profiles. It is shown that FEHM is a powerful tool thatmore » is capable of capturing the experimentally observed out ow rates and saturation profiles. Moreover, FEHM captures the transition from single- to multi-phase flow and CO 2 gas accumulation at interfaces separating sands. We also derive a simple expression, based on Darcy's law, for the pressure at which CO 2 free phase gas is observed and show that it reliably predicts the location at which single-phase flow transitions to multi-phase flow.« less

Geochemical Analyses of Surface and Shallow Gas Flux and Composition Over a Proposed Carbon Sequestration Site in Eastern Kentucky

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas Parris; Michael Solis; Kathryn Takacs

2009-12-31

Using soil gas chemistry to detect leakage from underground reservoirs (i.e. microseepage) requires that the natural range of soil gas flux and chemistry be fully characterized. To meet this need, soil gas flux (CO{sub 2}, CH{sub 4}) and the bulk (CO{sub 2}, CH{sub 4}) and isotopic chemistry ({delta}{sup 13}C-CO2) of shallow soil gases (<1 m, 3.3 ft) were measured at 25 locations distributed among two active oil and gas fields, an active strip mine, and a relatively undisturbed research forest in eastern Kentucky. The measurements apportion the biologic, atmospheric, and geologic influences on soil gas composition under varying degrees ofmore » human surface disturbance. The measurements also highlight potential challenges in using soil gas chemistry as a monitoring tool where the surface cover consists of reclaimed mine land or is underlain by shallow coals. For example, enrichment of ({delta}{sup 13}C-CO2) and high CH{sub 4} concentrations in soils have been historically used as indicators of microseepage, but in the reclaimed mine lands similar soil chemistry characteristics likely result from dissolution of carbonate cement in siliciclastic clasts having {delta}{sup 13}C values close to 0{per_thousand} and degassing of coal fragments. The gases accumulate in the reclaimed mine land soils because intense compaction reduces soil permeability, thereby impeding equilibration with the atmosphere. Consequently, the reclaimed mine lands provide a false microseepage anomaly. Further potential challenges arise from low permeability zones associated with compacted soils in reclaimed mine lands and shallow coals in undisturbed areas that might impede upward gas migration. To investigate the effect of these materials on gas migration and composition, four 10 m (33 ft) deep monitoring wells were drilled in reclaimed mine material and in undisturbed soils with and without coals. The wells, configured with sampling zones at discrete intervals, show the persistence of some of the aforementioned anomalies at depth. Moreover, high CO{sub 2} concentrations associated with coals in the vadose zone suggest a strong affinity for adsorbing CO{sub 2}. Overall, the low permeability of reclaimed mine lands and coals and CO2 adsorption by the latter is likely to reduce the ability of surface geochemistry tools to detect a microseepage signal.« less

Use of carbon monoxide and hydrogen by a bacteria-animal symbiosis from seagrass sediments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kleiner, Manuel; Wentrup, Cecilia; Holler, Thomas

The gutless marine worm Olavius algarvensis lives in symbiosis with chemosynthetic bacteria that provide nutrition by fixing carbon dioxide (CO 2) into biomass using reduced sulfur compounds as energy sources. A recent metaproteomic analysis of the O. algarvensis symbiosis indicated that carbon monoxide (CO) and hydrogen (H 2) might also be used as energy sources. We provide direct evidence that the O. algarvensis symbiosis consumes CO and H 2. Single cell imaging using nanoscale secondary ion mass spectrometry revealed that one of the symbionts, the γ3-symbiont, uses the energy from CO oxidation to fix CO 2. Pore water analysis revealedmore » considerable in-situ concentrations of CO and H 2 in the O. algarvensis environment, Mediterranean seagrass sediments. Pore water H 2 concentrations (89-2147 nM) were up to two orders of magnitude higher than in seawater, and up to 36-fold higher than previously known from shallow-water marine sediments. Pore water CO concentrations (17-51 nM) were twice as high as in the overlying seawater (no literature data from other shallow-water sediments are available for comparison). Ex-situ incubation experiments showed that dead seagrass rhizomes produced large amounts of CO. Lastly, CO production from decaying plant material could thus be a significant energy source for microbial primary production in seagrass sediments.« less

Use of carbon monoxide and hydrogen by a bacteria-animal symbiosis from seagrass sediments

DOE PAGES

Kleiner, Manuel; Wentrup, Cecilia; Holler, Thomas; ...

2015-05-27

The gutless marine worm Olavius algarvensis lives in symbiosis with chemosynthetic bacteria that provide nutrition by fixing carbon dioxide (CO 2) into biomass using reduced sulfur compounds as energy sources. A recent metaproteomic analysis of the O. algarvensis symbiosis indicated that carbon monoxide (CO) and hydrogen (H 2) might also be used as energy sources. We provide direct evidence that the O. algarvensis symbiosis consumes CO and H 2. Single cell imaging using nanoscale secondary ion mass spectrometry revealed that one of the symbionts, the γ3-symbiont, uses the energy from CO oxidation to fix CO 2. Pore water analysis revealedmore » considerable in-situ concentrations of CO and H 2 in the O. algarvensis environment, Mediterranean seagrass sediments. Pore water H 2 concentrations (89-2147 nM) were up to two orders of magnitude higher than in seawater, and up to 36-fold higher than previously known from shallow-water marine sediments. Pore water CO concentrations (17-51 nM) were twice as high as in the overlying seawater (no literature data from other shallow-water sediments are available for comparison). Ex-situ incubation experiments showed that dead seagrass rhizomes produced large amounts of CO. Lastly, CO production from decaying plant material could thus be a significant energy source for microbial primary production in seagrass sediments.« less

Degradation mechanism of over-charged LiCoO 2/mesocarbon microbeads battery during shallow depth of discharge cycling

DOE PAGES

Zhang, Lingling; Ma, Yulin; Cheng, Xinqun; ...

2016-08-26

LiCoO 2/mesocarbon microbeads (MCMB) batteries are over-charged to different voltage (4.4 V, 4.5 V, 4.6 V, and 4.7 V, respectively) for ten times, and then are cycled 1000 times for shallow depth of discharge. The morphology, structure, and electrochemical performance of the electrode materials were studied in detail in order to identify the capacity fading mechanism of over-charged battery after long-term cycling. The cycling performances of LiCoO 2/MCMB batteries are gradually aggravated with the increase of over-charging voltage and the degradation mechanism is diverse upon the degree of over-charging. Furthermore, the capacity fading after long-term cycling of battery over-charged tomore » 4.6 V or 4.7 V is mainly attributed to the cathodes. Soft X-ray absorption spectroscopy (XAS) demonstrates that the lower valence state of cobalt exists on the surface of the LiCoO 2 after serious over-charging (4.6 V or 4.7 V), and cobalt is dissolved then deposited on the anode according to the result of energy dispersive spectrometry (EDS). But, after shallow over-charging (4.4 V or 4.5 V), the capacity deterioration is proposed as the loss of active lithium, presented by the generation of the SEI film on the anode, which is verified by water washed tests.« less

Cyclic degassing of Erebus volcano, Antarctica

NASA Astrophysics Data System (ADS)

Ilanko, Tehnuka; Oppenheimer, Clive; Burgisser, Alain; Kyle, Philip

2015-06-01

Field observations have previously identified rapid cyclic changes in the behaviour of the lava lake of Erebus volcano. In order to understand more fully the nature and origins of these cycles, we present here a wavelet-based frequency analysis of time series measurements of gas emissions from the lava lake, obtained by open-path Fourier transform infrared spectroscopy. This reveals (i) a cyclic change in total gas column amount, a likely proxy for gas flux, with a period of about 10 min, and (ii) a similarly phased cyclic change in proportions of volcanic gases, which can be explained in terms of chemical equilibria and pressure-dependent solubilities. Notably, the wavelet analysis shows a persistent periodicity in the CO2/CO ratio and strong periodicity in H2O and SO2 degassing. The `peaks' of the cycles, defined by maxima in H2O and SO2 column amounts, coincide with high CO2/CO ratios and proportionally smaller increases in column amounts of CO2, CO, and OCS. We interpret the cycles to arise from recharge of the lake by intermittent pulses of magma from shallow depths, which degas H2O at low pressure, combined with a background gas flux that is decoupled from this very shallow magma degassing.

Exploring the MIS M2 glaciation occurring during a warm and high atmospheric CO2 Pliocene background climate

NASA Astrophysics Data System (ADS)

Tan, Ning; Ramstein, Gilles; Dumas, Christophe; Contoux, Camille; Ladant, Jean-Baptiste; Sepulchre, Pierre; Zhang, Zhongshi; De Schepper, Stijn

2017-08-01

Prior to the Northern Hemisphere glaciation around ∼2.7 Ma, a large global glaciation corresponding to a 20 to 60 m sea-level drop occurred during Marine Isotope Stage (MIS) M2 (3.312-3.264 Ma), interrupted the period of global warmth and high CO2 concentration (350-450 ppmv) of the mid Piacenzian. Unlike the late Quaternary glaciations, the M2 glaciation only lasted 50 kyrs and occurred under uncertain CO2 concentration (220-390 ppmv). The mechanisms causing the onset and termination of the M2 glaciation remain enigmatic, but a recent geological hypothesis suggests that the re-opening and closing of the shallow Central American Seaway (CAS) might have played a key role. In this article, thanks to a series of climate simulations carried out using a fully coupled Atmosphere Ocean General Circulation Model (GCM) and a dynamic ice sheet model, we show that re-opening of the shallow CAS helps precondition the low-latitude oceanic circulation and affects the related northward energy transport, but cannot alone explain the onset of the M2 glaciation. The presence of a shallow open CAS, together with favourable orbital parameters, 220 ppmv of CO2 concentration, and the related vegetation and ice sheet feedback, led to a global ice sheet build-up producing a global sea-level drop in the lowest range of proxy-derived estimates. More importantly, our results show that the simulated closure of the CAS has a negligible impact on the NH ice sheet melt and cannot explain the MIS M2 termination.

Potential for iron oxides to control metal releases in CO2 sequestration scenarios

USGS Publications Warehouse

Berger, P.M.; Roy, W.R.

2011-01-01

The potential for the release of metals into groundwater following the injection of carbon dioxide (CO2) into the subsurface during carbon sequestration projects remains an open research question. Changing the chemical composition of even the relatively deep formation brines during CO2 injection and storage may be of concern because of the recognized risks associated with the limited potential for leakage of CO2-impacted brine to the surface. Geochemical modeling allows for proactive evaluation of site geochemistry before CO2 injection takes place to predict whether the release of metals from iron oxides may occur in the reservoir. Geochemical modeling can also help evaluate potential changes in shallow aquifers were CO2 leakage to occur near the surface. In this study, we created three batch-reaction models that simulate chemical changes in groundwater resulting from the introduction of CO2 at two carbon sequestration sites operated by the Midwest Geological Sequestration Consortium (MGSC). In each of these models, we input the chemical composition of groundwater samples into React??, and equilibrated them with selected mineral phases and CO 2 at reservoir pressure and temperature. The model then simulated the kinetic reactions with other mineral phases over a period of up to 100 years. For two of the simulations, the water was also at equilibrium with iron oxide surface complexes. The first model simulated a recently completed enhanced oil recovery (EOR) project in south-central Illinois in which the MGSC injected into, and then produced CO2, from a sandstone oil reservoir. The MGSC afterwards periodically measured the brine chemistry from several wells in the reservoir for approximately two years. The sandstone contains a relatively small amount of iron oxide, and the batch simulation for the injection process showed detectable changes in several aqueous species that were attributable to changes in surface complexation sites. After using the batch reaction configuration to match measured geochemical changes due to CO2 injection, we modeled potential changes in groundwater chemistry at the Illinois Basin - Decatur Project (IBDP) site in Decatur, Illinois, USA. At the IBDP, the MGSC will inject 1 million tonnes of CO2 over the course of three years at a depth of about 2 km below the surface into the Mt. Simon Formation. Sections of the Mt. Simon Formation contain up to 10 percent iron oxide, and therefore surface complexes on iron oxides should play a major role in controlling brine chemistry. The batch simulation of this system showed a significant decrease in pH after the injection of CO2 with corresponding changes in brine chemistry resulting from both mineral precipitation/dissolution reactions and changes in the chemistry on iron oxide surfaces. To ensure the safety of shallow drinking water sources, there are several shallow monitoring wells at the IBDP that the MGSC samples regularly to determine baseline chemical concentrations. Knowing what geochemical parameters are most sensitive to CO2 disturbances allows us to focus monitoring efforts. Modeling a major influx of CO2 into the shallow groundwater allowed us to determine that were an introduction of CO2 to occur, the only immediate effect will be dolomite dissolution and calcite precipitation. ?? 2011 Published by Elsevier Ltd.

MUFITS Code for Modeling Geological Storage of Carbon Dioxide at Sub- and Supercritical Conditions

NASA Astrophysics Data System (ADS)

Afanasyev, A.

2012-12-01

Two-phase models are widely used for simulation of CO2 storage in saline aquifers. These models support gaseous phase mainly saturated with CO2 and liquid phase mainly saturated with H2O (e.g. TOUGH2 code). The models can be applied to analysis of CO2 storage only in relatively deeply-buried reservoirs where pressure exceeds CO2 critical pressure. At these supercritical reservoir conditions only one supercritical CO2-rich phase appears in aquifer due to CO2 injection. In shallow aquifers where reservoir pressure is less than the critical pressure CO2 can split in two different liquid-like and gas-like phases (e.g. Spycher et al., 2003). Thus a region of three-phase flow of water, liquid and gaseous CO2 can appear near the CO2 injection point. Today there is no widely used and generally accepted numerical model capable of the three-phase flows with two CO2-rich phases. In this work we propose a new hydrodynamic simulator MUFITS (Multiphase Filtration Transport Simulator) for multiphase compositional modeling of CO2-H2O mixture flows in porous media at conditions of interest for carbon sequestration. The simulator is effective both for supercritical flows in a wide range of pressure and temperature and for subcritical three-phase flows of water, liquid CO2 and gaseous CO2 in shallow reservoirs. The distinctive feature of the proposed code lies in the methodology for mixture properties determination. Transport equations and Darcy correlation are solved together with calculation of the entropy maximum that is reached in thermodynamic equilibrium and determines the mixture composition. To define and solve the problem only one function - mixture thermodynamic potential - is required. The potential is determined using a three-parametric generalization of Peng-Robinson equation of state fitted to experimental data (Todheide, Takenouchi, Altunin etc.). We apply MUFITS to simple 1D and 2D test problems of CO2 injection in shallow reservoirs subjected to phase changes between liquid and gaseous CO2. We consider CO2 injection into highly heterogeneous the 10th SPE reservoir. We provide analysis of physical phenomena that have control temperature distribution in the reservoir. The distribution is non-monotonic with regions of high and low temperature. The main phenomena responsible for considerable temperature decline around CO2 injection point is the liquid CO2 evaporation process. We also apply the code to real-scale 3D simulations of CO2 geological storage at supercritical conditions in Sleipner field and Johansen formation (Fig). The work is supported financially by the Russian Foundation for Basic Research (12-01-31117) and grant for leading scientific schools (NSh 1303.2012.1). CO2 phase saturation in Johansen formation after 50 years of injection and 1000 years of rest period

The potential of near-surface geophysical methods in a hierarchical monitoring approach for the detection of shallow CO2 seeps at geological storage sites

NASA Astrophysics Data System (ADS)

Sauer, U.; Schuetze, C.; Dietrich, P.

2013-12-01

The MONACO project (Monitoring approach for geological CO2 storage sites using a hierarchic observation concept) aims to find reliable monitoring tools that work on different spatial and temporal scales at geological CO2 storage sites. This integrative hierarchical monitoring approach based on different levels of coverage and resolutions is proposed as a means of reliably detecting CO2 degassing areas at ground surface level and for identifying CO2 leakages from storage formations into the shallow subsurface, as well as CO2 releases into the atmosphere. As part of this integrative hierarchical monitoring concept, several methods and technologies from ground-based remote sensing (Open-path Fourier-transform infrared (OP-FTIR) spectroscopy), regional measurements (near-surface geophysics, chamber-based soil CO2 flux measurement) and local in-situ measurements (using shallow boreholes) will either be combined or used complementary to one another. The proposed combination is a suitable concept for investigating CO2 release sites. This also presents the possibility of adopting a modular monitoring concept whereby our monitoring approach can be expanded to incorporate other methods in various coverage scales at any temporal resolution. The link between information obtained from large-scale surveys and local in-situ monitoring can be realized by sufficient geophysical techniques for meso-scale monitoring, such as geoelectrical and self-potential (SP) surveys. These methods are useful for characterizing fluid flow and transport processes in permeable near-surface sedimentary layers and can yield important information concerning CO2-affected subsurface structures. Results of measurements carried out a natural analogue site in the Czech Republic indicate that the hierarchical monitoring approach represents a successful multidisciplinary modular concept that can be used to monitor both physical and chemical processes taking place during CO2 migration and seepage. The application of FTIR spectroscopy in combination with soil gas surveys and geophysical investigations results in a comprehensive site characterization, including atmospheric and near-surface CO2 distribution, as well as subsurface structural features. We observed a correlation of higher CO2 concentration and flux rates at the meso-scale that coincides with distinct geophysical anomalies. Here, we found prominent SP anomalies and zones of lower resistivity in the geoelectrical images compared to undisturbed regions nearby. This presentation will discuss the results we obtained and illustrate the influence of CO2 on electrical parameters measured under field conditions in relation to environmental parameters.

Changes in Eocene-Miocene shallow marine carbonate factories along the tropical SE Circum-Caribbean responded to major regional and global environmental and tectonic events

NASA Astrophysics Data System (ADS)

Silva-Tamayo, Juan Carlos

2015-04-01

Changes in the factory of Cenozoic tropical marine carbonates have been for long attributed to major variations on climatic and environmental conditions. Although important changes on the factories of Cenozoic Caribbean carbonates seem to have followed global climatic and environmental changes, the regional impact of such changes on the factories of shallow marine carbonate along the Caribbean is not well established. Moreover, the influence of transpressional tectonics on the occurrence, distribution and stratigraphy of shallow marine carbonate factories along this area is far from being well understood. Here we report detailed stratigraphic, petrographic and Sr-isotope chemostratigraphic information of several Eocene-Miocene carbonate successions deposited along the equatorial/tropical SE Circum-Caribbean (Colombia and Panama) from which we further assess the influence of changing environmental conditions, transtentional tectonics and sea level change on the development of the shallow marine carbonate factories. Our results suggest that during the Eocene-early Oligocene interval, a period of predominant high atmospheric pCO2, coralline algae constitute the principal carbonate builders of shallow marine carbonate successions along the SE Circum-Caribbean. Detailed stratigraphic and paragenetic analyses suggest the developed of laterally continuous red algae calcareous build-ups along outer-rimmed carbonate platforms. The predominance of coralline red algae over corals on the shallow marine carbonate factories was likely related to high sea surface temperatures and high turbidity. The occurrence of such build-ups was likely controlled by pronounce changes in the basin paleotopography, i.e. the occurrence of basement highs and lows, resulting from local transpressional tectonics. The occurrence of these calcareous red algae dominated factories was also controlled by diachronic opening of different sedimentary basins along the SE Circum Caribbean resulting from transpressional tectonics. Calcareous algae persisted as the main constituents of the shallow marine carbonate factories until the middle Oligocene; a period when atmospheric pCO2 dropped significantly. The drop in atmospheric pCO2 allowed the onset of global icehouse conditions, which likely resulted in a decrease in sea surface temperatures along the Caribbean. This drop allowed the appearance of corals as the main constituents of the shallow marine carbonate factories along the SE Circum-Caribbean by late Oligocene times.

Effective detection of CO 2 leakage: a comparison of groundwater sampling and pressure monitoring

DOE PAGES

Keating, Elizabeth; Dai, Zhenxue; Dempsey, David; ...

2014-12-31

Shallow aquifer monitoring is likely to be a required aspect to any geologic CO 2 sequestration operation. Collecting groundwater samples and analyzing for geochemical parameters such as pH, alkalinity, total dissolved carbon, and trace metals has been suggested by a number of authors as a possible strategy to detect CO 2 leakage. The effectiveness of this approach, however, will depend on the hydrodynamics of the leak-induced CO 2 plume and the spatial distribution of the monitoring wells relative to the origin of the leak. To our knowledge, the expected effectiveness of groundwater sampling to detect CO 2 leakage has notmore » yet been quantitatively assessed. In this study we query hundreds of simulations developed for the National Risk Assessment Project (US DOE) to estimate risks to drinking water resources associated with CO 2 leaks. The ensemble of simulations represent transient, 3-D multi-phase reactive transport of CO 2 and brine leaked from a sequestration reservoir, via a leaky wellbore, into an unconfined aquifer. Key characteristics of the aquifer, including thickness, mean permeability, background hydraulic gradient, and geostatistical measures of aquifer heterogeneity, were all considered uncertain parameters. Complex temporally-varying CO 2 and brine leak rate scenarios were simulated using a heuristic scheme with ten uncertain parameters. The simulations collectively predict the spatial and temporal evolution of CO 2 and brine plumes over 200 years in a shallow aquifer under a wide range of leakage scenarios and aquifer characteristics. Using spatial data from an existing network of shallow drinking water wells in the Edwards Aquifer, TX, as one illustrative example, we calculated the likelihood of leakage detection by groundwater sampling. In this monitoring example, there are 128 wells available for sampling, with a density of about 2.6 wells per square kilometer. If the location of the leak is unknown a priori, a reasonable assumption in many cases, we found that the leak would be detected in at least one of the monitoring wells in less than 10% of the scenarios considered. This is because plume sizes are relatively small, and so the probability of detection decreases rapidly with distance from the leakage point. For example, 400m away from the leakage point there is less than 20% chance of detection. We then compared the effectiveness of groundwater quality sampling to shallow aquifer and/or reservoir pressure monitoring. For the Edwards Aquifer example, pressure monitoring in the same monitoring well network was found to be even less effective that groundwater quality monitoring. This is presumably due to the unconfined conditions and relatively high permeability, so pressure perturbations quickly dissipate. Although specific results may differ from site to site, this type of analysis should be useful to site operators and regulators when selecting leak detection strategies. Given the spatial characteristics of a proposed monitoring well network, probabilities of leakage detection can be rapidly calculated using this methodology. Although conditions such as these may not be favorable for leakage detection in shallow aquifers, leakage detection could be much more successful in the injection reservoir. We demonstrate proof-of-concept for this hypothesis, presenting a simulation where there is measurable pressure change at the injection well due to overpressurization, fault rupture, and consequent leakage up the fault into intermediate and shallow aquifers. The size of the detectible pressure change footprint is much larger in the reservoir than in either of the overlying aquifers. Further exploration of the range of conditions for which this technique would be successful is the topic of current study.« less

High net CO2 and CH4 release at a eutrophic shallow lake on a formerly drained fen

NASA Astrophysics Data System (ADS)

Franz, Daniela; Koebsch, Franziska; Larmanou, Eric; Augustin, Jürgen; Sachs, Torsten

2016-05-01

Drained peatlands often act as carbon dioxide (CO2) hotspots. Raising the groundwater table is expected to reduce their CO2 contribution to the atmosphere and revitalise their function as carbon (C) sink in the long term. Without strict water management rewetting often results in partial flooding and the formation of spatially heterogeneous, nutrient-rich shallow lakes. Uncertainties remain as to when the intended effect of rewetting is achieved, as this specific ecosystem type has hardly been investigated in terms of greenhouse gas (GHG) exchange. In most cases of rewetting, methane (CH4) emissions increase under anoxic conditions due to a higher water table and in terms of global warming potential (GWP) outperform the shift towards CO2 uptake, at least in the short term.Based on eddy covariance measurements we studied the ecosystem-atmosphere exchange of CH4 and CO2 at a shallow lake situated on a former fen grassland in northeastern Germany. The lake evolved shortly after flooding, 9 years previous to our investigation period. The ecosystem consists of two main surface types: open water (inhabited by submerged and floating vegetation) and emergent vegetation (particularly including the eulittoral zone of the lake, dominated by Typha latifolia). To determine the individual contribution of the two main surface types to the net CO2 and CH4 exchange of the whole lake ecosystem, we combined footprint analysis with CH4 modelling and net ecosystem exchange partitioning.The CH4 and CO2 dynamics were strikingly different between open water and emergent vegetation. Net CH4 emissions from the open water area were around 4-fold higher than from emergent vegetation stands, accounting for 53 and 13 g CH4 m-2 a-1 respectively. In addition, both surface types were net CO2 sources with 158 and 750 g CO2 m-2 a-1 respectively. Unusual meteorological conditions in terms of a warm and dry summer and a mild winter might have facilitated high respiration rates. In sum, even after 9 years of rewetting the lake ecosystem exhibited a considerable C loss and global warming impact, the latter mainly driven by high CH4 emissions. We assume the eutrophic conditions in combination with permanent high inundation as major reasons for the unfavourable GHG balance.

Quantifying the Movement and Dissolution of Fugitive Methane in Shallow Aquifers: Visualization Experiments

NASA Astrophysics Data System (ADS)

Van De Ven, C. J. C.; Mumford, K. G.

2016-12-01

The environmental impact and potential human health implications, specifically from the contamination of groundwater sources, has sparked controversy around shale gas extraction in North America. It is clear that understanding the effects of hydraulic fracturing on shallow fresh water aquifers is of great importance, including the threat of stray gas (also referred to as fugitive methane) on groundwater quality. Faulty wells provide a preferential pathway for free gas phase (mostly methane) to migrate from deeper gas-bearing formations of natural gas to shallow aquifers, followed by its dissolution into the surrounding groundwater. An increased understanding of the fate of fugitive methane in shallow aquifers is required to assess the potential risks associated with current and future operations, as well as to better link gas migration, dissolution and the deterioration of groundwater quality. In this study, a series of laboratory experiments were performed using carbon dioxide (CO2) gas as a surrogate for methane to improve our understanding of gas dissolution in groundwater systems. Using CO2, a novel laboratory technique was developed that allows the measurement of dissolved CO2 concentrations using image analysis alongside visualization of free gas mobilization. The technique is based on the acidification of water during CO2 dissolution, which causes a colour change in an indicator dye. The colour change is recorded using a visual light transmission technique, in which digital images are used to track dissolved concentrations at high spatial (1 mm) and temporal (5 s) resolutions in a two-dimensional (25 × 25 × 1 cm3) flow cell. The experiments were completed in both homogeneous sand packs and sand packs containing layered heterogeneities to investigate the dissolution of both gas fingers and gas pools. The results demonstrate the potential of this novel technique for investigating gas dissolution, and showed significant tailing of dissolved CO2 and persistence of other gas phase components. This technique will aid in the development of conceptual models to link fugitive methane to groundwater contamination and provide detailed data required for the validation of numerical models that account for gas-water mass transfer; both of which are required for the development of sound monitoring techniques.

Blind Geothermal System Exploration in Active Volcanic Environments; Multi-phase Geophysical and Geochemical Surveys in Overt and Subtle Volcanic Systems, Hawai’i and Maui

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fercho, Steven; Owens, Lara; Walsh, Patrick

2015-08-01

Suites of new geophysical and geochemical exploration surveys were conducted to provide evidence for geothermal resource at the Haleakala Southwest Rift Zone (HSWRZ) on Maui Island, Hawai’i. Ground-based gravity (~400 stations) coupled with heli-bourne magnetics (~1500 line kilometers) define both deep and shallow fractures/faults, while also delineating potentially widespread subsurface hydrothermal alteration on the lower flanks (below approximately 1800 feet a.s.l.). Multi-level, upward continuation calculations and 2-D gravity and magnetic modeling provide information on source depths, but lack of lithologic information leaves ambiguity in the estimates. Additionally, several well-defined gravity lows (possibly vent zones) lie coincident with magnetic highs suggestingmore » the presence of dike intrusions at depth which may represent a potentially young source of heat. Soil CO2 fluxes were measured along transects across geophysically-defined faults and fractures as well as young cinder cones along the HSWRZ. This survey generally did not detect CO2 levels above background, with the exception of a weak anomalous flux signal over one young cinder cone. The general lack of observed CO2 flux signals on the HSWRZ is likely due to a combination of lower magmatic CO2 fluxes and relatively high biogenic surface CO2 fluxes which mix with the magmatic signal. Similar surveys at the Puna geothermal field on the Kilauea Lower East Rift Zone (KLERZ) also showed a lack of surface CO2 flux signals, however aqueous geochemistry indicated contribution of magmatic CO2 and He to shallow groundwater here. As magma has been intercepted in geothermal drilling at the Puna field, the lack of measured surface CO2 flux indicative of upflow of magmatic fluids here is likely due to effective “scrubbing” by high groundwater and a mature hydrothermal system. Dissolved inorganic carbon (DIC) concentrations, δ13C compositions and 3He/4He values were sampled at Maui from several shallow groundwater samples indicating only minor additions of magmatic CO2 and He to the groundwater system, although much less than observed near Puna. The much reduced DIC and He abundances at Maui, along with a lack of hotsprings and hydrothermal alteration, as observed near Puna, does not strongly support a deeper hydrothermal system within the HSWRZ.« less

Uncertainty Quantification and Risk Mitigation of CO2 Leakage in Groundwater Aquifers

NASA Astrophysics Data System (ADS)

Sun, Y.; Tong, C.; Mansoor, K.; Carroll, S.

2013-12-01

The risk of CO2 leakage into shallow aquifers through various pathways such as faults and abandoned wells is a concern of CO2 geological sequestration. If a leak is detected in an aquifer system, a contingency plan is required to manage the CO2 storage and to protect the groundwater source. Among many remediation and mitigation strategies, the simplest is to stop CO2 leakage at a wellbore. Therefore, it is necessary to address whether and when the CO2 leaks should be sealed, and how much risk can be mitigated. In the presence of various uncertainties, including geological-structure uncertainty and parametric uncertainty, the risk of CO2 leakage into an aquifer needs to be assessed with probabilistic distributions of uncertain parameters. In this study, we developed an integrated model to simulate multiphase flow of CO2 and brine in a deep storage reservoir, through a leaky well at an uncertain location, and subsequently multicomponent reactive transport in a shallow aquifer. Each sub-model covers its domain-specific physics. Uncertainties of geological structure and parameters are considered together with decision variables (CO2 injection rate and mitigation time) for risk assessment of leakage-impacted aquifer volume. High-resolution and less-expensive reduced-order models (ROMs) of risk profiles are approximated as polynomial functions of decision variables and all uncertain parameters. These reduced-order models are then used in the place of computationally-expensive numerical models for future decision-making on if and when the leaky well is sealed. The tradeoff between CO2 storage capacity in the reservoir and the leakage-induced risk in the aquifer is evaluated. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

Intermediate-Scale Experimental Study to Improve Fundamental Understanding of Attenuation Capacity for Leaking CO 2 in Heterogeneous Shallow Aquifers

DOE PAGES

Plampin, Michael R.; Porter, Mark L.; Pawar, Rajesh J.; ...

2017-11-15

In order to assess the risks of Geologic Carbon Sequestration (GCS), it is crucial to understand the fundamental physicochemical processes that may occur if and when stored CO 2 leaks upward from a deep storage reservoir into the shallow subsurface. Intermediate-scale experiments allow for improved understanding of the multiphase evolution processes that control CO 2 migration behaviour in the subsurface, because the boundary conditions, initial conditions, and porous media parameters can be better controlled and monitored in the laboratory than in field settings. For this study, a large experimental test bed was designed to mimic a cross-section of a shallowmore » aquifer with layered geologic heterogeneity. As water with aqueous CO 2 was injected into the system to mimic a CO 2-charged water leakage scenario, the spatiotemporal evolution of the multiphase CO 2 plume was monitored. Similar experiments were performed with two different sand combinations to assess the relative effects of different types of geologic facies transitions on the CO 2 evolution processes. Significant CO 2 attenuation was observed in both scenarios, but by fundamentally different mechanisms. When the porous media layers had very different permeabilities, attenuation was caused by local accumulation (structural trapping) and slow re-dissolution of gas phase CO 2. When the permeability difference between the layers was relatively small, on the other hand, gas phase continually evolved over widespread areas near the leading edge of the aqueous plume, which also attenuated CO 2 migration. In conclusion, this improved process understanding will aid in the development of models that could be used for effective risk assessment and monitoring programs for GCS projects.« less

Intermediate-Scale Experimental Study to Improve Fundamental Understanding of Attenuation Capacity for Leaking CO 2 in Heterogeneous Shallow Aquifers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Plampin, Michael R.; Porter, Mark L.; Pawar, Rajesh J.

In order to assess the risks of Geologic Carbon Sequestration (GCS), it is crucial to understand the fundamental physicochemical processes that may occur if and when stored CO 2 leaks upward from a deep storage reservoir into the shallow subsurface. Intermediate-scale experiments allow for improved understanding of the multiphase evolution processes that control CO 2 migration behaviour in the subsurface, because the boundary conditions, initial conditions, and porous media parameters can be better controlled and monitored in the laboratory than in field settings. For this study, a large experimental test bed was designed to mimic a cross-section of a shallowmore » aquifer with layered geologic heterogeneity. As water with aqueous CO 2 was injected into the system to mimic a CO 2-charged water leakage scenario, the spatiotemporal evolution of the multiphase CO 2 plume was monitored. Similar experiments were performed with two different sand combinations to assess the relative effects of different types of geologic facies transitions on the CO 2 evolution processes. Significant CO 2 attenuation was observed in both scenarios, but by fundamentally different mechanisms. When the porous media layers had very different permeabilities, attenuation was caused by local accumulation (structural trapping) and slow re-dissolution of gas phase CO 2. When the permeability difference between the layers was relatively small, on the other hand, gas phase continually evolved over widespread areas near the leading edge of the aqueous plume, which also attenuated CO 2 migration. In conclusion, this improved process understanding will aid in the development of models that could be used for effective risk assessment and monitoring programs for GCS projects.« less

Eutrophication effects on greenhouse gas fluxes from shallow-lake mesocosms override those of climate warming.

PubMed

Davidson, Thomas A; Audet, Joachim; Svenning, Jens-Christian; Lauridsen, Torben L; Søndergaard, Martin; Landkildehus, Frank; Larsen, Søren E; Jeppesen, Erik

2015-12-01

Fresh waters make a disproportionately large contribution to greenhouse gas (GHG) emissions, with shallow lakes being particular hot spots. Given their global prevalence, how GHG fluxes from shallow lakes are altered by climate change may have profound implications for the global carbon cycle. Empirical evidence for the temperature dependence of the processes controlling GHG production in natural systems is largely based on the correlation between seasonal temperature variation and seasonal change in GHG fluxes. However, ecosystem-level GHG fluxes could be influenced by factors, which while varying seasonally with temperature are actually either indirectly related (e.g. primary producer biomass) or largely unrelated to temperature, for instance nutrient loading. Here, we present results from the longest running shallow-lake mesocosm experiment which demonstrate that nutrient concentrations override temperature as a control of both the total and individual GHG flux. Furthermore, testing for temperature treatment effects at low and high nutrient levels separately showed only one, rather weak, positive effect of temperature (CH4 flux at high nutrients). In contrast, at low nutrients, the CO2 efflux was lower in the elevated temperature treatments, with no significant effect on CH4 or N2 O fluxes. Further analysis identified possible indirect effects of temperature treatment. For example, at low nutrient levels, increased macrophyte abundance was associated with significantly reduced fluxes of both CH4 and CO2 for both total annual flux and monthly observation data. As macrophyte abundance was positively related to temperature treatment, this suggests the possibility of indirect temperature effects, via macrophyte abundance, on CH4 and CO2 flux. These findings indicate that fluxes of GHGs from shallow lakes may be controlled more by factors indirectly related to temperature, in this case nutrient concentration and the abundance of primary producers. Thus, at ecosystem scale, response to climate change may not follow predictions based on the temperature dependence of metabolic processes. © 2015 John Wiley & Sons Ltd.

Chemistry of unsaturated zone gases sampled in open boreholes at the crest of Yucca Mountain, Nevada: Data and basic concepts of chemical and physical processes in the mountain

USGS Publications Warehouse

Thorstenson, Donald C.; Weeks, Edwin P.; Haas, Herbert; Busenberg, Eurybiades; Plummer, Niel; Peters, Charles A.

1998-01-01

Boreholes open to the unsaturated zone at the crest of Yucca Mountain, Nevada, were variously sampled for CO2 (including 13C and 14C), CH4, N2, O2, Ar, CFC-11, CFC-12, and CFC-113 from 1986 to 1993. Air enters the mountain in outcrops, principally on the eastern slope, is enriched in CO2by mixing with soil gas, and is advected to the mountain crest, where it returns to the atmosphere. The CFC data indicate that travel times of the advecting gas in the shallow Tiva Canyon hydrogeologic unit are ≤5 years. The 14C activities are postbomb to depths of 100 m, indicating little retardation of 14CO2 in the shallow flow systems. The 14C activities from 168 to 404 m in the Topopah Spring hydrogeologic unit are 85–90 pMC at borehole USW-UZ6. The CFC data show that the drilling of USW-UZ6 in 1984 has altered the natural system by providing a conduit through the Paintbrush Nonwelded unit, allowing flow from Topopah Spring outcrops in Solitario Canyon on the west to USW-UZ6, upward in the borehole through the Paintbrush, to the shallow Tiva Canyon flow systems, and out of the mountain.

The pH and pCO2 dependence of sulfate reduction in shallow-sea hydrothermal CO2 – venting sediments (Milos Island, Greece)

PubMed Central

Bayraktarov, Elisa; Price, Roy E.; Ferdelman, Timothy G.; Finster, Kai

2013-01-01

Microbial sulfate reduction (SR) is a dominant process of organic matter mineralization in sulfate-rich anoxic environments at neutral pH. Recent studies have demonstrated SR in low pH environments, but investigations on the microbial activity at variable pH and CO2 partial pressure are still lacking. In this study, the effect of pH and pCO2 on microbial activity was investigated by incubation experiments with radioactive 35S targeting SR in sediments from the shallow-sea hydrothermal vent system of Milos, Greece, where pH is naturally decreased by CO2 release. Sediments differed in their physicochemical characteristics with distance from the main site of fluid discharge. Adjacent to the vent site (T ~40–75°C, pH ~5), maximal sulfate reduction rates (SRR) were observed between pH 5 and 6. SR in hydrothermally influenced sediments decreased at neutral pH. Sediments unaffected by hydrothermal venting (T ~26°C, pH ~8) expressed the highest SRR between pH 6 and 7. Further experiments investigating the effect of pCO2 on SR revealed a steep decrease in activity when the partial pressure increased from 2 to 3 bar. Findings suggest that sulfate reducing microbial communities associated with hydrothermal vent system are adapted to low pH and high CO2, while communities at control sites required a higher pH for optimal activity. PMID:23658555

The pH and pCO2 dependence of sulfate reduction in shallow-sea hydrothermal CO2 - venting sediments (Milos Island, Greece).

PubMed

Bayraktarov, Elisa; Price, Roy E; Ferdelman, Timothy G; Finster, Kai

2013-01-01

Microbial sulfate reduction (SR) is a dominant process of organic matter mineralization in sulfate-rich anoxic environments at neutral pH. Recent studies have demonstrated SR in low pH environments, but investigations on the microbial activity at variable pH and CO2 partial pressure are still lacking. In this study, the effect of pH and pCO2 on microbial activity was investigated by incubation experiments with radioactive (35)S targeting SR in sediments from the shallow-sea hydrothermal vent system of Milos, Greece, where pH is naturally decreased by CO2 release. Sediments differed in their physicochemical characteristics with distance from the main site of fluid discharge. Adjacent to the vent site (T ~40-75°C, pH ~5), maximal sulfate reduction rates (SRR) were observed between pH 5 and 6. SR in hydrothermally influenced sediments decreased at neutral pH. Sediments unaffected by hydrothermal venting (T ~26°C, pH ~8) expressed the highest SRR between pH 6 and 7. Further experiments investigating the effect of pCO2 on SR revealed a steep decrease in activity when the partial pressure increased from 2 to 3 bar. Findings suggest that sulfate reducing microbial communities associated with hydrothermal vent system are adapted to low pH and high CO2, while communities at control sites required a higher pH for optimal activity.

Probabilistic evaluation of shallow groundwater resources at a hypothetical carbon sequestration site

DOE PAGES

Dai, Zhenxue; Keating, Elizabeth; Bacon, Diana H.; ...

2014-03-07

Carbon sequestration in geologic reservoirs is an important approach for mitigating greenhouse gases emissions to the atmosphere. This study first develops an integrated Monte Carlo method for simulating CO 2 and brine leakage from carbon sequestration and subsequent geochemical interactions in shallow aquifers. Then, we estimate probability distributions of five risk proxies related to the likelihood and volume of changes in pH, total dissolved solids, and trace concentrations of lead, arsenic, and cadmium for two possible consequence thresholds. The results indicate that shallow groundwater resources may degrade locally around leakage points by reduced pH and increased total dissolved solids (TDS).more » The volumes of pH and TDS plumes are most sensitive to aquifer porosity, permeability, and CO 2 and brine leakage rates. The estimated plume size of pH change is the largest, while that of cadmium is the smallest among the risk proxies. Plume volume distributions of arsenic and lead are similar to those of TDS. The scientific results from this study provide substantial insight for understanding risks of deep fluids leaking into shallow aquifers, determining the area of review, and designing monitoring networks at carbon sequestration sites.« less

Volatile Emissions from Hot Spring Basin, Yellowstone National Park, USA

NASA Astrophysics Data System (ADS)

Werner, C.; Hurwitz, S.; Bergfeld, D.; Evans, W. C.; Lowenstern, J. B.; Jaworowski, C.; Heasler, H.

2007-12-01

The flux and composition of magmatic volatiles were characterized for Hot Spring Basin (HSB), Yellowstone National Park, in August 2006. Diffuse fluxes of CO2 (228 sites) from thermal soil were elevated, with a population distribution similar to that of other acid-sulfate areas in Yellowstone. Thus the estimated diffuse emission rate at HSB is proportionately larger than other areas due to its large area, and could be as high as 1000 td-1 CO2. The diffuse flux of H2S was only above detection limits at 20 of the 31 sites measured. The estimated diffuse H2S emission rate was ~ 4 td-1. Good correlation exists between the log of CO2 flux and shallow soil temperatures, indicating linked steam and gas upflow in the subsurface. The correlation between CO2 and H2S fluxes is weak, and the CO2 / H2S diffuse flux ratio was higher than in fumarolic ratios of CO2 to H2S. This suggests that various reactions, e.g., native sulfur deposition, act to remove H2S from the original gas stream in the diffuse low- temperature environment. Dissolved sulfate flux through Shallow Creek, which drains part of HSB, was ~ 4 td-1. Comparing dissolved sulfate flux to estimates of primary emission of H2S based on fumarolic gas geochemistry gives first order estimates of the sulfur consumed in surficial or subsurface mineral deposition. Total C and S outputs from HSB are comparable to other active volcanic systems.

Forest-killing diffuse CO2 emission at Mammoth Mountain as a sign of magmatic unrest

NASA Astrophysics Data System (ADS)

Farrar, C. D.; Sorey, M. L.; Evans, W. C.; Howle, J. F.; Kerr, B. D.; Kennedy, B. M.; King, C.-Y.; Southon, J. R.

1995-08-01

MAMMOTH Mountain, in the western United States, is a large dacitic volcano with a long history of vo lean ism that began 200 kyr ago1 and produced phreatic eruptions as recently as 500 +/- 200 yr BP (ref. 2). Seismicity, ground deformation and changes in fumarole gas composition suggested an episode of shallow dyke intrusion in 1989-90 (refs 3, 4). Areas of dying forest and incidents of near asphyxia in confined spaces, first reported in 1990, prompted us to search for diffuse flank emissions of magmatic CO2, as have been described at Mount Etna5 and Vulcano6. Here we report the results of a soil-gas survey, begun in 1994, that revealed CO2 concentrations of 30-96% in a 30-hectare region of killed trees, from which we estimate a total CO2 flux of >=1,200 tonnes per day. The forest die-off is the most conspicuous surface manifestation of magmatic processes at Mammoth Mountain, which hosts only weak fumarolic vents and no summit activity. Although the onset of tree kill coincided with the episode of shallow dyke intrusion, the magnitude and duration of the CO2 flux indicates that a larger, deeper magma source and/or a large reservoir of high-pressure gas is being tapped.

Forest-killing diffuse CO2 emission at Mammoth Mountain as a sign of magmatic unrest

USGS Publications Warehouse

Farrar, C.D.; Sorey, M.L.; Evans, William C.; Howle, J.F.; Kerr, B.D.; Kennedy, B.M.; King, C.-Y.; Southon, J.R.

1995-01-01

MAMMOTH Mountain, in the western United States, is a large dacitic volcano with a long history of volcamsm that began 200 kyr ago1 and produced phreatic eruptions as recently as 500 ?? 200 yr BP (ref. 2). Seismicity, ground deformation and changes in fumarole gas composition suggested an episode of shallow dyke intrusion in 1989-90 (refs 3, 4). Areas of dying forest and incidents of near asphyxia in confined spaces, first reported in 1990, prompted us to search for diffuse flank emissions of magmatic CO2, as have been described at Mount Etna5 and Vulcano6. Here we report the results of a soil-gas survey, begun in 1994, that revealed CO2 concentrations of 30-96% in a 30-hectare region of killed trees, from which we estimate a total CO2 flux of ???1,200 tonnes per day. The forest die-off is the most conspicuous surface manifestation of magmatic processes at Mammoth Mountam, which hosts only weak fumarolic vents and no summit activity. Although the onset of tree kill coincided with the episode of shallow dyke intrusion, the magnitude and duration of the CO2 flux indicates that a larger, deeper magma source and/or a large reservoir of high-pressure gas is being tapped.

Geochemical variations during the 2012 Emilia seismic sequence

NASA Astrophysics Data System (ADS)

Sciarra, Alessandra; Cantucci, Barbara; Galli, Gianfranco; Cinti, Daniele; Pizzino, Luca

2015-04-01

Several geochemical surveys (soil gas and shallow water) were performed in the Modena province (Massa Finalese, Finale Emilia, Medolla and S. Felice sul Panaro), during 2006-2014 period. In May-June 2012, a seismic sequence (main shocks of ML 5.9 and 5.8) was occurred closely to the investigated area. In this area 300 CO2 and CH4 fluxes measurements, 150 soil gas concentrations (He, H2, CO2, CH4 and C2H6), 30 shallow waters and their isotopic analyses (δ13C- CH4, δD- CH4 and δ13C- CO2) were performed in April-May 2006, October and December 2008, repeated in May and September 2012, June 2013 and July 2014 afterwards the 2012 Emilia seismic sequences. Chemical composition of soil gas are dominated by CH4 in the southern part by CO2 in the northern part. Very anomalous fluxes and concentrations are recorded in spot areas; elsewhere CO2 and CH4 values are very low, within the typical range of vegetative and of organic exhalation of the cultivated soil. After the seismic sequence the CH4 and CO2 fluxes are increased of one order of magnitude in the spotty areas, whereas in the surrounding area the values are within the background. On the contrary, CH4 concentration decrease (40%v/v in the 2012 surveys) and CO2 concentration increase until to 12.7%v/v (2013 survey). Isotopic gas analysis were carried out only on samples with anomalous values. Pre-seismic data hint a thermogenic origin of CH4 probably linked to leakage from a deep source in the Medolla area. Conversely, 2012/2013 isotopic data indicate a typical biogenic origin (i.e. microbial hydrocarbon production) of the CH4, as recognized elsewhere in the Po Plain and surroundings. The δ13C-CO2 value suggests a prevalent shallow origin of CO2 (i.e. organic and/or soil-derived) probably related to anaerobic oxidation of heavy hydrocarbons. Water samples, collected from domestic, industrial and hydrocarbons exploration wells, allowed us to recognize different families of waters. Waters are meteoric in origin and, apart one sample, are not thermally anomalous. Stable isotopes of H and O point out the absence of mixing with connate waters, prolonged interaction with the host-rock at high temperature and/or heavy gas-water exchange at depth. Isotopic carbon composition emphasizes its organic (i.e. shallow) origin; only "La Canonica" site, the deepest well sampled in this study, shows a probable deep(er) provenance of dissolved carbon. Waters trend away from the atmospheric end-member composition, dissolving CO2 or CH4 depending on their redox state. Dissolved radon activity is very low, likely due to the particular hydrogeological setting of the study area (i.e. the presence of waters with long residence times in the considered aquifers). Obtained results highlight a different behavior before and after the seismic events, proved also by the different carbon isotopic signature of CH4. These variations could be produced by increasing of bacterial (e.g. peat strata) and methanogenic fermentation processes in the first meters of the soil.

Modelling gas transport in the shallow subsurface in the Maguelone field experiment

NASA Astrophysics Data System (ADS)

Basirat, Farzad; Niemi, Auli; Perroud, Hervé; Lofi, Johanna; Denchik, Nataliya; Lods, Gérard; Pezard, Philippe; Sharma, Prabhakar; Fagerlund, Fritjof

2013-04-01

Developing reliable monitoring techniques to detect and characterize CO2 leakage in shallow subsurface is necessary for the safety of any GCS project. To test different monitoring techniques, shallow injection-monitoring experiment have and are being carried out at the Maguelone, along the Mediterranean lido of the Gulf of Lions, near Montpellier, France. This experimental site was developed in the context of EU FP7 project MUSTANG and is documented in Lofi et al. (2012). Gas injection experiments are being carried out and three techniques of pressure, electrical resistivity and seismic monitoring have been used to detect the nitrogen and CO2 release in the near surface environment. In the present work we use the multiphase and multicomponent TOUGH2/EOS7CA model to simulate the gaseous nitrogen and CO2 transport of the experiments carried out so far. The objective is both to gain understanding of the system performance based on the model analysis as well as to further develop and validate modelling approaches for gas transport in the shallow subsurface, against the well-controlled data sets. Numerical simulation can also be used for the prediction of experimental setup limitations. We expect the simulations to represent the breakthrough time for the different tested injection rates. Based on the hydrogeological formation data beneath the lido, we also expect the vertical heterogeneities in grain size distribution create an effective capillary barrier against upward gas transport in numerical simulations. Lofi J., Pezard P.A., Bouchette F., Raynal O., Sabatier P., Denchik N., Levannier A., Dezileau L., and Certain R. Integrated onshore-offshore geophysical investigation of a layered coastal aquifer, NW Mediterranean. Ground Water, (2012).

Water Footprint and Water Consumption for the Main Crops and Biofuels Produced in Brazil

NASA Astrophysics Data System (ADS)

Sun, Y.; Tong, C.; Mansoor, K.; Carroll, S.

2011-12-01

The risk of CO2 leakage into shallow aquifers through various pathways such as faults and abandoned wells is a concern of CO2 geological sequestration. If a leak is detected in an aquifer system, a contingency plan is required to manage the CO2 storage and to protect the groundwater source. Among many remediation and mitigation strategies, the simplest is to stop CO2 leakage at a wellbore. Therefore, it is necessary to address whether and when the CO2 leaks should be sealed, and how much risk can be mitigated. In the presence of various uncertainties, including geological-structure uncertainty and parametric uncertainty, the risk of CO2 leakage into an aquifer needs to be assessed with probabilistic distributions of uncertain parameters. In this study, we developed an integrated model to simulate multiphase flow of CO2 and brine in a deep storage reservoir, through a leaky well at an uncertain location, and subsequently multicomponent reactive transport in a shallow aquifer. Each sub-model covers its domain-specific physics. Uncertainties of geological structure and parameters are considered together with decision variables (CO2 injection rate and mitigation time) for risk assessment of leakage-impacted aquifer volume. High-resolution and less-expensive reduced-order models (ROMs) of risk profiles are approximated as polynomial functions of decision variables and all uncertain parameters. These reduced-order models are then used in the place of computationally-expensive numerical models for future decision-making on if and when the leaky well is sealed. The tradeoff between CO2 storage capacity in the reservoir and the leakage-induced risk in the aquifer is evaluated. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

The influence of biopreparations on the reduction of energy consumption and CO2 emissions in shallow and deep soil tillage.

PubMed

Naujokienė, Vilma; Šarauskis, Egidijus; Lekavičienė, Kristina; Adamavičienė, Aida; Buragienė, Sidona; Kriaučiūnienė, Zita

2018-06-01

The application of innovation in agriculture technologies is very important for increasing the efficiency of agricultural production, ensuring the high productivity of plants, production quality, farm profitability, the positive balance of used energy, and the requirements of environmental protection. Therefore, it is a scientific problem that solid and soil surfaces covered with plant residue have a negative impact on the work, traction resistance, energy consumption, and environmental pollution of tillage machines. The objective of this work was to determine the dependence of the reduction of energy consumption and CO 2 gas emissions on different biopreparations. Experimental research was carried out in a control (SC1) and seven different biopreparations using scenarios (SC2-SC8) using bacterial and non-bacterial biopreparations in different consistencies (with essential and mineral oils, extracts of various grasses and sea algae, phosphorus, potassium, humic and gibberellic acids, copper, zinc, manganese, iron, and calcium), estimating discing and plowing as the energy consumption parameters of shallow and deep soil tillage machines, respectively. CO 2 emissions were determined by evaluating soil characteristics (such as hardness, total porosity and density). Meteorological conditions such average daily temperatures (2015-20.3 °C; 2016-16.90 °C) and precipitations (2015-6.9 mm; 2016-114.9 mm) during the month strongly influenced different results in 2015 and 2016. Substantial differences between the averages of energy consumption identified in approximately 62% of biological preparation combinations created usage scenarios. Experimental research established that crop field treatments with biological preparations at the beginning of vegetation could reduce the energy consumption of shallow tillage machines by up to approximately 23%, whereas the energy consumption of deep tillage could be reduced by up to approximately 19.2% compared with the control treatment. The experimental research results reveal the reduction of CO 2 emissions in shallow tillage to approximately 20.14% (and that in deep tillage to approximately 19.16%) when works were performed by different biological preparation usage scenarios. This experimental research demonstrates the efficient use of the special adaptation of a new biotechnological method for the reduction of the energy consumption and CO 2 gas emissions of agricultural machinery. Copyright © 2018 Elsevier B.V. All rights reserved.

Effects of dissolved CO2 on Shallow Freshwater Microbial Communities simulating a CO2 Leakage Scenario

NASA Astrophysics Data System (ADS)

Gulliver, D. M.; Lowry, G. V.; Gregory, K.

2013-12-01

Geological carbon sequestration is likely to be part of a comprehensive strategy to minimize the atmospheric release of greenhouse gasses, establishing a concern of sequestered CO2 leakage into overlying potable aquifers. Leaking CO2 may affect existing biogeochemical processes and therefore water quality. There is a critical need to understand the evolution of CO2 exposed microbial communities that influence the biogeochemistry in these freshwater aquifers. The evolution of microbial ecology for different CO2 exposure concentrations was investigated using fluid-slurry samples obtained from a shallow freshwater aquifer (55 m depth, 0.5 MPa, 22 °C, Escatawpa, MS). The microbial community of well samples upstream and downstream of CO2 injection was characterized. In addition, batch vessel experiments were conducted with the upstream aquifer samples exposed to varying pCO2 from 0% to 100% under reservoir temperature and pressure for up to 56 days. The microbial community of the in situ experiment and the batch reactor experiment were analyzed with 16S rRNA clone libraries and qPCR. In both the in situ experiment and the batch reactor experiment, DNA concentration did not correlate with CO2 exposure. Both the in situ experiment and the batch reactors displayed a changing microbial community with increased CO2 exposure. The well water isolate, Curvibacter, appeared to be the most tolerant genus to high CO2 concentrations in the in situ experiments and to mid-CO2 concentrations in the batch reactors. In batch reactors with pCO2 concentrations higher than experienced in situ (pCO2 = 0.5 MPa), Pseudomonas appeared to be the most tolerant genus. Findings provide insight into a dynamic biogeochemical system that will alter with CO2 exposure. Adapted microbial populations will eventually give rise to the community that will impact the metal mobility and water quality. Knowledge of the surviving microbial populations will enable improved models for predicting the fate of CO2 following leakage and lead to better strategies for ensuring the quality of potable aquifer water.

Geochemical evidence for a magmatic CO2 degassing event at Mammoth Mountain, California, September-December 1997

USGS Publications Warehouse

McGee, K.A.; Gerlach, T.M.; Kessler, R.; Doukas, M.P.

2000-01-01

Recent time series soil CO2 concentration data from monitoring stations in the vicinity of Mammoth Mountain, California, reveal strong evidence for a magmatic degassing event during the fall of 1997 lasting more than 2 months. Two sensors at Horseshoe Lake first recorded the episode on September 23, 1997, followed 10 days later by a sensor on the north flank of Mammoth Mountain. Direct degassing from shallow intruding magma seems an implausible cause of the degassing event, since the gas released at Horseshoe Lake continued to be cold and barren of other magmatic gases, except for He. We suggest that an increase in compressional strain on the area south of Mammoth Mountain driven by movement of major fault blocks in Long Valley caldera may have triggered an episode of increased degassing by squeezing additional accumulated CO2 from a shallow gas reservoir to the surface along faults and other structures where it could be detected by the CO2 monitoring network. Recharge of the gas reservoir by CO2 emanating from the deep intrusions that probably triggered deep long-period earthquakes may also have contributed to the degassing event. The nature of CO2 discharge at the soil-air interface is influenced by the porous character of High Sierra soils and by meteorological processes. Solar insolation is the primary source of energy for the Earth atmosphere and plays a significant role in most diurnal processes at the Earth surface. Data from this study suggest that external forcing due largely to local orographic winds influences the fine structure of the recorded CO2 signals.

Monitoring CO2 Intrusion in shallow aquifer using complex electrical methods and a novel CO2 sensitive Lidar-based sensor

NASA Astrophysics Data System (ADS)

Leger, E.; Dafflon, B.; Thorpe, M.; Kreitinger, A.; Laura, D.; Haivala, J.; Peterson, J.; Spangler, L.; Hubbard, S. S.

2016-12-01

While subsurface storage of CO2 in geological formations offers significant potential to mitigate atmospheric greenhouse gasses, approaches are needed to monitor the efficacy of the strategy as well as possible negative consequences, such as leakage of CO2 or brine into groundwater or release of fugitive gaseous CO2. Groundwater leakages can cause subsequent reactions that may also be deleterious. For example, a release of dissolved CO2 into shallow groundwatersystems can decrease groundwater pH which can potentiallymobilize naturally occurring trace metals and ions. In this perspective, detecting and assessing potential leak requires development of novel monitoring techniques.We present the results of using surface electrical resistivity tomography (ERT) and a novel CO2 sensitive Lidar-based sensor to monitor a controlled CO2 release at the ZeroEmission Research and Technology Center (Bozeman, Montana). Soil temperature and moisture sensors, wellbore water quality measurements as well as chamber-based CO2 flux measurements were used in addition to the ERT and a novel Lidar-based sensor to detect and assess potential leakage into groundwater, vadose zone and atmosphere. The three-week release wascarried out in the vadose and the saturated zones. Well sampling of pH and conductivity and surface CO2 fluxes and concentrations measurements were acquired during the release and are compared with complex electricalresistivity time-lapse measurements. The novel Lidar-based image of the CO2 plume were compared to chamber-based CO2 flux and concentration measurements. While a continuous increase in subsurface ERT and above ground CO2 was documented, joint analysis of the above and below ground data revealed distinct transport behavior in the vadose and saturated zones. Two type of transport were observed, one in the vadoze zone, monitored by CO2 flux chamber and ERT, and the other one in the saturated zone, were ERT and wellsampling were carried. The experiment suggests how a range of geophysical, remote sensing, hydrological and geochemical measurement approaches can be optimally configured to detect the distribution and explore behavior of possible CO2 leakages in distinct compartments, including groundwater, vadose zone, and atmosphere.

The system Na2CO3-CaCO3 at 3 GPa

NASA Astrophysics Data System (ADS)

Podborodnikov, Ivan V.; Shatskiy, Anton; Arefiev, Anton V.; Rashchenko, Sergey V.; Chanyshev, Artem D.; Litasov, Konstantin D.

2018-04-01

It was suggested that alkali-alkaline earth carbonates may have a substantial role in petrological processes relevant to metasomatism and melting of the Earth's mantle. Because natrite, Na2CO3, Na-Ca carbonate (shortite and/or nyerereite), and calcite, CaCO3, have been recently reported from xenoliths of shallow mantle (110-115 km) origin, we performed experiments on phase relations in the system Na2CO3-CaCO3 at 3 GPa and 800-1300 °C. We found that the system has one intermediate compound, Na2Ca3(CO3)4, at 800 °C, and two intermediate compounds, Na2Ca(CO3)2 and Na2Ca3(CO3)4, at 850 °C. CaCO3 crystals recovered from experiments at 950 and 1000 °C are aragonite and calcite, respectively. Maximum solid solution of CaCO3 in Na2CO3 is 20 mol% at 850 °C. The Na-carbonate-Na2Ca(CO3)2 eutectic locates near 860 °C and 56 mol% Na2CO3. Na2Ca(CO3)2 melts incongruently near 880 °C to produce Na2Ca3(CO3)4 and a liquid containing about 51 mol% Na2CO3. Na2Ca3(CO3)4 disappears above 1000 °C via incongruent melting to calcite and a liquid containing about 43 mol% Na2CO3. At 1050 °C, the liquid, coexisting with Na-carbonate, contains 87 mol% Na2CO3. Na-carbonate remains solid up to 1150 °C and melts at 1200 °C. The Na2CO3 content in the liquid coexisting with calcite decreases to 15 mol% as temperature increases to 1300 °C. Considering the present and previous data, a range of the intermediate compounds on the liquidus of the Na2CO3-CaCO3 join changes as pressure increases in the following sequence: Na2Ca(CO3)2 (0.1 GPa) → Na2Ca(CO3)2, Na2Ca3(CO3)4 (3 GPa) → Na4Ca(CO3)3, Na2Ca3(CO3)4 (6 GPa). Thus, the Na2Ca(CO3)2 nyerereite stability field extends to the shallow mantle pressures. Consequently, findings of nyerereite among daughter phases in the melt inclusions in olivine from the sheared garnet peridotites are consistent with their mantle origin.

Effect of subalpine canopy removal on snowpack, soil solution, and nutrient export, Fraser Experimental Forest, CO

USGS Publications Warehouse

Stottlemyer, R.; Troendle, C.A.

1999-01-01

Research on the effects of vegetation manipulation on snowpack, soil water, and streamwater chemistry and flux has been underway at the Fraser Experimental Forest (FEF), CO, since 1982. Greater than 95% of FEF snowmelt passes through watersheds as subsurface flow where soil processes significantly alter meltwater chemistry. To better understand the mechanisms accounting for annual variation in watershed streamwater ion concentration and flux with snowmelt, we studied subsurface water flow, its ion concentration, and flux in conterminous forested and clear cut plots. Repetitive patterns in subsurface flow and chemistry were apparent. Control plot subsurface flow chemistry had the highest ion concentrations in late winter and fall. When shallow subsurface flow occurred, its Ca2+, SO42-, and HCO3- concentrations were lower and K+ higher than deep flow. The percentage of Ca2+, NO3-, SO42-, and HCO3- flux in shallow depths was less and K+ slightly greater than the percentage of total flow. Canopy removal increased precipitation reaching the forest floor by about 40%, increased peak snowpack water equivalent (SWE) > 35%, increased the average snowpack Ca2+, NO3-, and NH4+ content, reduced the snowpack K+ content, and increased the runoff four-fold. Clear cutting doubled the percentage of subsurface flow at shallow depths, and increased K+ concentration in shallow subsurface flow and NO3- concentrations in both shallow and deep flow. The percentage change in total Ca2+, SO42-, and HCO3- flux in shallow depths was less than the change in water flux, while that of K+ and NO3- flux was greater. Relative to the control, in the clear cut the percentage of total Ca2+ flux at shallow depths increased from 5 to 12%, SO42- 5.4 to 12%, HCO3- from 5.6 to 8.7%, K+ from 6 to 35%, and NO3- from 2.7 to 17%. The increases in Ca2+ and SO42- flux were proportional to the increase in water flux, the flux of HCO3- increased proportionally less than water flux, and NO3- and K+ were proportionally greater than water flux. Increased subsurface flow accounted for most of the increase in non-limiting nutrient loss. For limiting nutrients, loss of plant uptake and increased shallow subsurface flow accounted for the greater loss. Seasonal ion concentration patterns in streamwater and subsurface flow were similar.Research on the effects of vegetation manipulation on snowpack, soil water, and streamwater chemistry and flux has been underway at the Fraser Experimental Forest (FEF), CO, since 1982. Greater than 95% of FEF snowmelt passes through watersheds as subsurface flow where soil processes significantly alter meltwater chemistry. To better understand the mechanisms accounting for annual variation in watershed streamwater ion concentration and flux with snowmelt, we studied subsurface water flow, its ion concentration, and flux in conterminous forested and clear cut plots. Repetitive patterns in subsurface flow and chemistry were apparent. Control plot subsurface flow chemistry had the highest ion concentrations in late winter and fall. When shallow subsurface flow occurred, its Ca2+, SO42-, and HCO3- concentrations were lower and K+ higher than deep flow. The percentage of Ca2+, NO3-, SO42-, and HCO3- flux in shallow depths was less and K+ slightly greater than the percentage of total flow. Canopy removal increased precipitation reaching the forest floor by about 40%, increased peak snowpack water equivalent (SWE) > 35%, increased the average snowpack Ca2+, NO3-, and NH4+ content, reduced the snowpack K+ content, and increased the runoff four-fold. Clear cutting doubled the percentage of subsurface flow at shallow depths, and increased K+ concentration in shallow subsurface flow and NO3- concentrations in both shallow and deep flow. The percentage change in total Ca2+, SO42-, and HCO3- flux in shallow depths was less than the change in water flux, while that of K+ and NO3- flux was greater. Relative to the control, in the clear cut the percentage of total Ca

Comparison of CO 2 Detection Methods Tested in Shallow Groundwater Monitoring Wells at a Geological Sequestration Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edenborn, Harry M.; Jain, Jinesh N.

The geological storage of anthropogenic carbon dioxide (CO 2) is one method of reducing the amount of CO 2 released into the atmosphere. Monitoring programs typically determine baseline conditions in surface and near-surface environments before, during, and after CO 2 injection to evaluate if impacts related to injection have occurred. Because CO 2 concentrations in groundwater fluctuate naturally due to complex geochemical and geomicrobiologicalinteractions, a clear understanding of the baseline behavior of CO 2 in groundwater near injection sites is important. Numerous ways of measuring aqueous CO 2 in the field and lab are currently used, but most methods havemore » significant shortcomings (e.g., are tedious, lengthy, have interferences, or have significant lag time before a result is determined). In this study, we examined the effectiveness of two novel CO 2 detection methods and their ability to rapidly detect CO2in shallow groundwater monitoring wells associated with the Illinois Basin –Decatur Project geological sequestration site. The CarboQC beverage carbonation meter was used to measure the concentration of CO 2 in water by monitoring temperature and pressure changes and calculating the PCO 2 from the ideal gas law. Additionally, a non-dispersive infrared (NDIR) CO< sub>2sensor enclosed in a gas-permeable, water-impermeable membrane measured CO2by determining an equilibrium concentration. Results showed that the CarboQC method provided rapid (< 3 min) and repeatable results under field conditions within a measured concentration range of 15 –125 mg/L CO 2. The NDIR sensor results correlated well (r 2= 0.93) with the CarboQC data, but CO 2 equilibration required at least 15 minutes, making the method somewhat less desirable under field conditions. In contrast, NDIR-based sensors have a greater potential for long-term deployment. Both systems are adaptable to in-line groundwater sampling methods. Other specific advantages and disadvantages associated with the two approaches, and anomalies associated with specific samples, are discussed in greater detail in this poster.« less

Greenhouse gas fluxes of a shallow lake in south-central North Dakota, USA

USGS Publications Warehouse

Tangen, Brian; Finocchiaro, Raymond; Gleason, Robert A.; Dahl, Charles F.

2016-01-01

Greenhouse gas (GHG) fluxes of aquatic ecosystems in the northern Great Plains of the U.S. represent a significant data gap. Consequently, a 3-year study was conducted in south-central North Dakota, USA, to provide an initial estimate of GHG fluxes from a large, shallow lake. Mean GHG fluxes were 0.02 g carbon dioxide (CO2) m−2 h−1, 0.0009 g methane (CH4) m−2 h−1, and 0.0005 mg nitrous oxide (N2O) m−2 h−1. Fluxes of CO2 and CH4 displayed temporal and spatial variability which is characteristic of aquatic ecosystems, while fluxes of N2O were consistently low throughout the study. Comparisons between results of this study and published values suggest that mean daily fluxes of CO2, CH4, and N2O fromLong Lakewere low, particularly when compared to the well-studied prairie pothole wetlands of the region. Similarly, cumulative seasonal CH4 fluxes, which ranged from 2.68–7.58 g CH4 m−2, were relatively low compared to other wetland systems of North America. The observed variability among aquatic ecosystems underscores the need for further research.

Epitaxial CoSi2 on MOS devices

DOEpatents

Lim, Chong Wee; Shin, Chan Soo; Petrov, Ivan Georgiev; Greene, Joseph E.

2005-01-25

An Si.sub.x N.sub.y or SiO.sub.x N.sub.y liner is formed on a MOS device. Cobalt is then deposited and reacts to form an epitaxial CoSi.sub.2 layer underneath the liner. The CoSi.sub.2 layer may be formed through a solid phase epitaxy or reactive deposition epitaxy salicide process. In addition to high quality epitaxial CoSi.sub.2 layers, the liner formed during the invention can protect device portions during etching processes used to form device contacts. The liner can act as an etch stop layer to prevent excessive removal of the shallow trench isolation, and protect against excessive loss of the CoSi.sub.2 layer.

Utilization of Integrated Assessment Modeling for determining geologic CO2 storage security

NASA Astrophysics Data System (ADS)

Pawar, R.

2017-12-01

Geologic storage of carbon dioxide (CO2) has been extensively studied as a potential technology to mitigate atmospheric concentration of CO2. Multiple international research & development efforts, large-scale demonstration and commercial projects are helping advance the technology. One of the critical areas of active investigation is prediction of long-term CO2 storage security and risks. A quantitative methodology for predicting a storage site's long-term performance is critical for making key decisions necessary for successful deployment of commercial scale projects where projects will require quantitative assessments of potential long-term liabilities. These predictions are challenging given that they require simulating CO2 and in-situ fluid movements as well as interactions through the primary storage reservoir, potential leakage pathways (such as wellbores, faults, etc.) and shallow resources such as groundwater aquifers. They need to take into account the inherent variability and uncertainties at geologic sites. This talk will provide an overview of an approach based on integrated assessment modeling (IAM) to predict long-term performance of a geologic storage site including, storage reservoir, potential leakage pathways and shallow groundwater aquifers. The approach utilizes reduced order models (ROMs) to capture the complex physical/chemical interactions resulting due to CO2 movement and interactions but are computationally extremely efficient. Applicability of the approach will be demonstrated through examples that are focused on key storage security questions such as what is the probability of leakage of CO2 from a storage reservoir? how does storage security vary for different geologic environments and operational conditions? how site parameter variability and uncertainties affect storage security, etc.

Spatial and temporal variability of greenhouse gas emissions from a small and shallow temperate lake

NASA Astrophysics Data System (ADS)

Praetzel, Leandra; Schmiedeskamp, Marcel; Broder, Tanja; Hüttemann, Caroline; Jansen, Laura; Metzelder, Ulrike; Wallis, Ronya; Knorr, Klaus-Holger; Blodau, Christian

2017-04-01

Small inland waters (< 1 km2) have recently been discovered as significant sources and sinks in the global carbon cycle because they cover larger areas than previously assumed and exhibit a higher metabolic activity than larger lakes. They are further expected to be susceptible to changing climate conditions. So far, little is known about the spatial and temporal variability of carbon dioxide (CO2) and methane (CH4) emissions and in-lake dynamics of CH4 production and oxidation in small, epilimnetic lakes in the temperate zone. Of particular interest is the potential occurrence of "hot spots" and "hot moments" that could contribute significantly to total emissions. To address this knowledge gap, we determined CO2 and CH4 emissions and dynamics to identify their controlling environmental factors in a polymictic small (1.4 ha) and shallow (max. depth approx. 1.5 m) crater lake ("Windsborn") in the Eifel uplands in south-west Germany. As Lake Windsborn has a small catchment area (8 ha) and no surficial inflows, it serves well as a model system for the identification of factors and processes controlling emissions. In 2015, 2016 and 2017 we measured CO2 and CH4 gas fluxes with different techniques across the sediment/water and water/atmosphere interface. Atmospheric exchange was measured using mini-chambers equipped with CO2 sensors and with an infra-red greenhouse gas analyzer for high temporal resolution flux measurements. Ebullition of CH4 was quantified with funnel traps. Sediment properties were examined using pore-water peepers. All measurements were carried out along a transect covering both littoral and central parts of the lake. Moreover, a weather station on a floating platform in the center of the lake recorded meteorological data as well as CO2 concentration in different depths of the water column. So far, Lake Windsborn seems to be a source for both CO2 and CH4 on an annual scale. CO2 emissions generally increased from spring to summer. Even though CO2 uptake could be observed during some periods in spring and fall, CO2 emissions in the summer exceeded the uptake. CO2 and CH4 emissions also appeared to be spatially variable between littoral areas and the inner lake. Shallow areas turned out to be "hot spots" of CO2 emissions whereas CH4 emissions were - against our expectations - highest in the center of the lake. Moreover, CH4 ebullition contributed substantially to total CH4 emissions. Our results show the importance of spatially and temporally highly resolved long-term measurements of greenhouse gas emissions and of potential controlling factors to address diurnal, seasonal and inter-annual variability as well as possible feedbacks to climate change.

Regional-scale brine migration along vertical pathways due to CO2 injection - Part 2: A simulated case study in the North German Basin

NASA Astrophysics Data System (ADS)

Kissinger, Alexander; Noack, Vera; Knopf, Stefan; Konrad, Wilfried; Scheer, Dirk; Class, Holger

2017-06-01

Saltwater intrusion into potential drinking water aquifers due to the injection of CO2 into deep saline aquifers is one of the hazards associated with the geological storage of CO2. Thus, in a site-specific risk assessment, models for predicting the fate of the displaced brine are required. Practical simulation of brine displacement involves decisions regarding the complexity of the model. The choice of an appropriate level of model complexity depends on multiple criteria: the target variable of interest, the relevant physical processes, the computational demand, the availability of data, and the data uncertainty. In this study, we set up a regional-scale geological model for a realistic (but not real) onshore site in the North German Basin with characteristic geological features for that region. A major aim of this work is to identify the relevant parameters controlling saltwater intrusion in a complex structural setting and to test the applicability of different model simplifications. The model that is used to identify relevant parameters fully couples flow in shallow freshwater aquifers and deep saline aquifers. This model also includes variable-density transport of salt and realistically incorporates surface boundary conditions with groundwater recharge. The complexity of this model is then reduced in several steps, by neglecting physical processes (two-phase flow near the injection well, variable-density flow) and by simplifying the complex geometry of the geological model. The results indicate that the initial salt distribution prior to the injection of CO2 is one of the key parameters controlling shallow aquifer salinization. However, determining the initial salt distribution involves large uncertainties in the regional-scale hydrogeological parameterization and requires complex and computationally demanding models (regional-scale variable-density salt transport). In order to evaluate strategies for minimizing leakage into shallow aquifers, other target variables can be considered, such as the volumetric leakage rate into shallow aquifers or the pressure buildup in the injection horizon. Our results show that simplified models, which neglect variable-density salt transport, can reach an acceptable agreement with more complex models.

Strangelove Ocean and Deposition of Unusual Shallow-Water Carbonates After the End-Permian Mass Extinction

NASA Technical Reports Server (NTRS)

Rampino, Michael R.; Caldeira, Ken

2003-01-01

The severe mass extinction of marine and terrestrial organisms at the end of the Permian Period (approx. 251 Ma) was accompanied by a rapid negative excursion of approx. 3 to 4 per mil in the carbon-isotope ratio of the global surface oceans and atmosphere that persisted for some 500,000 into the Early Triassic. Simulations with an ocean-atmosphere/carbon-cycle model suggest that the isotope excursion can be explained by collapse of ocean primary productivity (a Strangelove Ocean) and changes in the delivery and cycling of carbon in the ocean and on land. Model results also suggest that perturbations of the global carbon cycle resulting from the extinctions led to short-term fluctuations in atmospheric pCO2 and ocean carbonate deposition, and to a long-term (>1 Ma) decrease in sedimentary burial of organic carbon in the Triassic. Deposition of calcium carbonate is a major sink of river-derived ocean alkalinity and for CO2 from the ocean/atmosphere system. The end of the Permian was marked by extinction of most calcium carbonate secreting organisms. Therefore, the reduction of carbonate accumulation made the oceans vulnerable to a build-up of alkalinity and related fluctuations in atmospheric CO2. Our model results suggest that an increase in ocean carbonate-ion concentration should cause increased carbonate accumulation rates in shallow-water settings. After the end-Permian extinctions, early Triassic shallow-water sediments show an abundance of abiogenic and microbial carbonates that removed CaCO3 from the ocean and may have prevented a full 'ocean-alkalinity crisis' from developing.

Experimental determination of CO2 content at graphite saturation along a natural basalt-peridotite melt join: Implications for the fate of carbon in terrestrial magma oceans

NASA Astrophysics Data System (ADS)

Duncan, Megan S.; Dasgupta, Rajdeep; Tsuno, Kyusei

2017-05-01

Knowledge of the carbon carrying capacity of peridotite melt at reducing conditions is critical to constrain the mantle budget and planet-scale distribution of carbon set at early stage of differentiation. Yet, neither measurements of CO2 content in reduced peridotite melt nor a reliable model to extrapolate the known solubility of CO2 in basaltic (mafic) melt to solubility in peridotitic (ultramafic) melt exist. There are several reasons for this gap; one reason is due to the unknown relative contributions of individual network modifying cations, such as Ca2+ versus Mg2+, on carbonate dissolution particularly at reducing conditions. Here we conducted high pressure, temperature experiments to estimate the CO2 contents in silicate melts at graphite saturation over a compositional range from natural basalts toward peridotite at a fixed pressure (P) of 1.0 GPa, temperature (T) of 1600 °C, and oxygen fugacity (log ⁡ fO2 ∼ IW + 1.6). We also conducted experiments to determine the relative effects of variable Ca and Mg contents in mafic compositions on the dissolution of carbonate. Carbon in quenched glasses was measured and characterized using Fourier transform infrared spectroscopy (FTIR) and Raman Spectroscopy and was found to be dissolved as carbonate (CO32-). The FTIR spectra showed CO32- doublets that shifted systematically with the MgO and CaO content of silicate melts. Using our data and previous work we constructed a new composition-based model to determine the CO2 content of ultramafic (peridotitic) melt representative of an early Earth, magma ocean composition at graphite saturation. Our data and model suggest that the dissolved CO2 content of reduced, peridotite melt is significantly higher than that of basaltic melt at shallow magma ocean conditions; however, the difference in C content between the basaltic and peridotitic melts may diminish with depth as the more depolymerized peridotite melt is more compressible. Using our model of CO2 content at graphite saturation as a function of P-T-fO2-melt composition, we predict that a superliquidus shallow magma ocean should degas CO2. Whereas if the increase of fO2 with depth is weak, a magma ocean may ingas a modest amount of carbon during crystallization. Further, using the carbon content of peridotite melt at log ⁡ fO2 of IW and the knowledge of C content of Fe-rich alloy melt, we also consider the core-mantle partitioning of carbon, showing that DCmetal/peridotite of a shallow magma ocean is generally higher than previously estimated.

Multiple source components in gas manifestations from north-central Italy

USGS Publications Warehouse

Minissale, A.; Evans, William C.; Magro, G.; Vaselli, O.

1997-01-01

Gas manifestations in north-central Italy consist of CO2-rich gases with minor N2-rich emissions and discharge either along with thermal springs or into cold and stagnant waters. 'Cold' gases are prevalently CO2-dominated (> 90%) while gases related to the thermal waters have variable composition: from CO2 > 99.5% to N2 > 90%. The variable composition of 'thermal' gases is caused by differences in the thermal regime and lithology of the ascent paths, where there is mixing of gases from multiple sources, such as N2-rich atmospheric and deep CO2-rich metamorphic end-members. Elevated concentrations of CH4 and H2 in these gases are generally related to the presence of active geothermal systems at shallow depth, such as the Larderello-Travale field in Tuscany. The ??13C values between coexisting CH4 and CO2 in all samples analyzed suggest that CH4 originates abiogenically in 200-400??C hydrothermal systems. Far from geothermal areas, where the thermal gradient is lower or the water/gas ratio is high because of large inflow of meteoric waters, H2 and CH4 are usually lower. In some cases, they can be scrubbed or oxidized (especially H2), while the residual rising gas becomes indirectly enriched in N2 and CO2. Carbon dioxide is also enriched in some discharged gases because it is produced at shallow depth in lower temperature conditions (< 150??C). Heavy ??15N values for N2 to near +7.0??? suggest that, for some gas samples that contain excess nitrogen (e.g. where N2/Ar ??? 83), this component probably derives from ammonia-rich feldspars and micas within the Palaeozoic schist basement rocks. However, other samples show evidence of a shallow component of CH4 and N2 from Neogene basin sediments. The areal distribution of the 3He/4He ratio points to a general prevalence of atmospheric and crustal 4He in the gas discharges in central Italy. A significant component of mantle 3He is only found in the geothermal areas of Larderello where the large regional thermal anomaly suggests the presence of a deep magmatic body. ?? 1997 Elsevier Science B.V.

Laboratory investigation of the potential influence of CO2 migration on trace element release from natural aquifer sediments

NASA Astrophysics Data System (ADS)

Lebel, J.; Hakala, A.; Keating, E. H.; Allen, D. E.

2010-12-01

Successful geologic CO2 sequestration requires that risk management practices include efforts to ensure the protection of groundwater resources. In order to determine the level of detail necessary for predictive reactive transport inputs, we focused on CO2-water-rock reactions at a particular natural analog site for CO2 release (Chimayo, NM, USA) that currently is the focus of a broader reactive transport modeling study. At the Chimayo natural analog site, fluids with elevated total dissolved solids (TDS) and CO2 are being released into a shallow aquifer along a series of faults. Although many areas of the shallow aquifer contain elevated TDS and CO2, some areas remain unaffected. The purpose of our study is to investigate whether laboratory-based reactions between CO2, synthetic groundwater (both high and low TDS), and Chimayo aquifer sediments can be used to interpret the geochemical processes that are responsible for elevated metal concentrations in the high-TDS, high-CO2 Chimayo groundwaters. Sediment samples were collected from an outcrop from the Chimayo aquifer (Tesuque Formation, Santa Fe Group). The samples were ground and size fractionated to <60 mesh. Two synthetic groundwater solutions were created based on the major ion chemistries from previous studies of well samples: synthetic Na-HCO3 “background” water and synthetic Na-Ca-Cl “saline” water. Four reactor vessels were constructed to examine CO2-water-rock reactions for two natural sediment samples; for each sample, one reaction contained the background water, and the other contained the saline water. The reactors were continuously sparged with CO2 at a pressure of 1 atm for 14 days, and the reactor vessels were sampled at 6 different time intervals. As expected, the reactors sparged with CO2 showed a pH decrease (ranging from 5.66-6.06); in control reactions without CO2 the pH stayed relatively high and similar to field-measured pH values of low-CO2 Chimayo waters (7.25-8.65). The refractive index (RI) of the reacted fluids, used as a proxy for salinity changes during the reaction, showed no significant change over the course of the experiment indicating that CO2-water-rock reaction alone will not significantly increase groundwater TDS values at Chimayo. Preliminary analysis for similar CO2-water-rock reactions with Chimayo sediments show that, within 16 hours, Mg, Ca, K, Ba, Zn, Mn, P, Sr and U are preferentially released into solution when CO2 reacts with Chimayo sediments in the presence of low-TDS groundwater. All of these elements are associated with the carbonate mineral fraction, as determined through prior sequential extraction work. Our results show that rapid pH changes can be expected when CO2 is introduced into a shallow clay and sand-rich aquifer system, and that a variety of elements associated with the carbonate mineral fraction can be important to consider in the context of groundwater quality (e.g., Ba, U). Future risk assessment efforts will require an understanding of the trace element content of the CO2-reactive mineral fraction in groundwater aquifers adjacent to potential geologic sequestration sites.

Arsenic mobilization in shallow aquifers due to CO 2 intrusion from storage reservoirs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, Ting; Dai, Zhenxue; Viswanathan, Hari S.

We developed an integrated framework of combined batch experiments and reactive transport simulations to quantify water-rock-CO 2 interactions and arsenic (As) mobilization responses to CO 2 and/or saline water leakage into USDWs. Experimental and simulation results suggest that when CO 2 is introduced, pH drops immediately that initiates release of As from clay minerals. Calcite dissolution can increase pH slightly and cause As re-adsorption. Thus, the mineralogy of the USDW is ultimately a determining factor of arsenic fate and transport. Salient results suggest that: (1) As desorption/adsorption from/onto clay minerals is the major reaction controlling its mobilization, and clay mineralsmore » could mitigate As mobilization with surface complexation reactions; (2) dissolution of available calcite plays a critical role in buffering pH; (3) high salinity in general hinders As release from minerals; and (4) the magnitude and quantitative uncertainty of As mobilization are predicated on the values of reaction rates and surface area of calcite, adsorption surface areas and equilibrium constants of clay minerals, and cation exchange capacity. Results of this study are intended to improve ability to quantify risks associated with potential leakage of reservoir fluids into shallow aquifers, in particular the possible environmental impacts of As mobilization at carbon sequestration sites.« less

Arsenic mobilization in shallow aquifers due to CO 2 intrusion from storage reservoirs

DOE PAGES

Xiao, Ting; Dai, Zhenxue; Viswanathan, Hari S.; ...

2017-06-05

We developed an integrated framework of combined batch experiments and reactive transport simulations to quantify water-rock-CO 2 interactions and arsenic (As) mobilization responses to CO 2 and/or saline water leakage into USDWs. Experimental and simulation results suggest that when CO 2 is introduced, pH drops immediately that initiates release of As from clay minerals. Calcite dissolution can increase pH slightly and cause As re-adsorption. Thus, the mineralogy of the USDW is ultimately a determining factor of arsenic fate and transport. Salient results suggest that: (1) As desorption/adsorption from/onto clay minerals is the major reaction controlling its mobilization, and clay mineralsmore » could mitigate As mobilization with surface complexation reactions; (2) dissolution of available calcite plays a critical role in buffering pH; (3) high salinity in general hinders As release from minerals; and (4) the magnitude and quantitative uncertainty of As mobilization are predicated on the values of reaction rates and surface area of calcite, adsorption surface areas and equilibrium constants of clay minerals, and cation exchange capacity. Results of this study are intended to improve ability to quantify risks associated with potential leakage of reservoir fluids into shallow aquifers, in particular the possible environmental impacts of As mobilization at carbon sequestration sites.« less

The Plumbing System of a Highly Explosive Basaltic Volcano: Sunset Crater, AZ

NASA Astrophysics Data System (ADS)

Allison, C. M.; Roggensack, K.; Clarke, A. B.

2015-12-01

We seek to better understand highly explosive basaltic eruptions with specific focus on magmatic volatile solubility in alkali basalts and the magma plumbing system. Sunset Crater, an alkali basalt (~3.7 wt.% alkalis) scoria cone volcano, erupted explosively in 1085 AD. We analyzed 125 primary melt inclusions (MIs) from Sunset Crater tephra deposited by 2 subplinian phases and 1 Strombolian explosion to compare magma volatiles and storage conditions. We picked rapidly quenched free olivine crystals and selected large volume MIs (50-180 μm) located toward crystal cores. MIs are faceted and exhibit little major element composition variability with minor post entrapment crystallization (2-10%). MIs are relatively dry but CO2-rich. Water content varies from 0.4 wt.% to 1.5 wt.% while carbon dioxide abundance ranges between 1,150 ppm and 3,250 ppm. Most MIs contain >1 wt.% H2O and >2,150 ppm CO2. All observed MIs contain a vapor bubble, so we are evaluating MI vapor bubbles with Raman spectroscopy and re-homogenization experiments to determine the full volatile budget. Because knowledge of volatile solubility is critical to accurately interpret results from MI analyses, we measured H2O-CO2 solubility in the Sunset Crater bulk composition. Fluid-saturated experiments at 4 and 6 kbar indicate shallower entrapment pressures for these MIs than values calculated for this composition using existing models. Assuming fluid saturation, MIs record depths from 6 km to 14 km, including groupings suggesting two pauses for longer-term storage at ~6 km and ~10.5 km. We do not observe any significant differences in MIs from phases exhibiting different eruptive styles, suggesting that while a high CO2 content may drive rapid magma ascent and be partly responsible for highly explosive eruptions, shallower processes may govern the final eruptive character. To track shallow processes during magma ascent from depth of MI-entrapment up to the surface, we are examining MI re-entrants.

The role of CO2 variability and exposure time for biological impacts of ocean acidification

NASA Astrophysics Data System (ADS)

Shaw, Emily C.; Munday, Philip L.; McNeil, Ben I.

2013-09-01

impacts of ocean acidification have mostly been studied using future levels of CO2 without consideration of natural variability or how this modulates both duration and magnitude of CO2 exposure. Here we combine results from laboratory studies on coral reef fish with diurnal in situ CO2 data from a shallow coral reef, to demonstrate how natural variability alters exposure times for marine organisms under increasingly high-CO2 conditions. Large in situ CO2 variability already results in exposure of coral reef fish to short-term CO2 levels higher than laboratory-derived critical CO2 levels (~600 µatm). However, we suggest that the in situ exposure time is presently insufficient to induce negative effects observed in laboratory studies. Our results suggest that both exposure time and the magnitude of CO2 levels will be important in determining the response of organisms to future ocean acidification, where both will increase markedly with future increases in CO2.

Evaluating sensitivity of complex electrical methods for monitoring CO2 intrusion into a shallow groundwater system and associated geochemical transformations

NASA Astrophysics Data System (ADS)

Dafflon, B.; Wu, Y.; Hubbard, S. S.; Birkholzer, J. T.; Daley, T. M.; Pugh, J. D.; Peterson, J.; Trautz, R. C.

2011-12-01

A risk factor of CO2 storage in deep geological formations includes its potential to leak into shallow formations and impact groundwater geochemistry and quality. In particular, CO2 decreases groundwater pH, which can potentially mobilize naturally occurring trace metals and ions commonly absorbed to or contained in sediments. Here, geophysical studies (primarily complex electrical method) are being carried out at both laboratory and field scales to evaluate the sensitivity of geophysical methods for monitoring dissolved CO2 distribution and geochemical transformations that may impact water quality. Our research is performed in association with a field test that is exploring the effects of dissolved CO2 intrusion on groundwater geochemistry. Laboratory experiments using site sediments (silica sand and some fraction of clay minerals) and groundwater were initially conducted under field relevant CO2 partial pressures (pCO2). A significant pH drop was observed with inline sensors with concurrent changes in fluid conductivity caused by CO2 dissolution. Electrical resistivity and electrical phase responses correlated well with the CO2 dissolution process at various pCO2. Specifically, resistivity decreased initially at low pCO2 condition resulting from CO2 dissolution followed by a slight rebound because of the transition of bicarbonate into non-dissociated carbonic acid at lower pH slightly reducing the total concentration of dissociated species. Continuous electrical phase decreases were also observed, which are interpreted to be driven by the decrease of surface charge density (due to the decrease of pH, which approaches the PZC of the sediments). In general, laboratory experiments revealed the sensitivity of electrical signals to CO2 intrusion into groundwater formations and can be used to guide field data interpretation. Cross well complex electrical data are currently being collected periodically throughout a field experiment involving the controlled release of dissolved CO2 into groundwater. The objective of the geophysical cross well monitoring effort is to evaluate the sensitivity of complex electrical methods to dissolved CO2 at the field scale. Here, we report on the ability to translate laboratory-based petrophysical information from lab to field scales, and on the potential of field complex electrical methods for remotely monitoring CO2-induced geochemical transformations.

Cholera toxin expression by El Tor Vibrio cholerae in shallow culture growth conditions.

PubMed

Cobaxin, Mayra; Martínez, Haydee; Ayala, Guadalupe; Holmgren, Jan; Sjöling, Asa; Sánchez, Joaquín

2014-01-01

Vibrio cholerae O1 classical, El Tor and O139 are the primary biotypes that cause epidemic cholera, and they also express cholera toxin (CT). Although classical V. cholerae produces CT in various settings, the El Tor and O139 strains require specific growth conditions for CT induction, such as the so-called AKI conditions, which consist of growth in static conditions followed by growth under aerobic shaking conditions. However, our group has demonstrated that CT production may also take place in shallow static cultures. How these type of cultures induce CT production has been unclear, but we now report that in shallow culture growth conditions, there is virtual depletion of dissolved oxygen after 2.5 h of growth. Concurrently, during the first three to 4 h, endogenous CO2 accumulates in the media and the pH decreases. These findings may explain CT expression at the molecular level because CT production relies on a regulatory cascade, in which the key regulator AphB may be activated by anaerobiosis and by low pH. AphB activation stimulates TcpP synthesis, which induces ToxT production, and ToxT directly stimulates ctxAB expression, which encodes CT. Importantly, ToxT activity is enhanced by bicarbonate. Therefore, we suggest that in shallow cultures, AphB is activated by initial decreases in oxygen and pH, and subsequently, ToxT is activated by intracellular bicarbonate that has been generated from endogenous CO2. This working model would explain CT production in shallow cultures and, possibly, also in other growth conditions. Copyright © 2013 Elsevier Ltd. All rights reserved.

A controlled field pilot for testing near surface CO2 detection techniques and transport models

USGS Publications Warehouse

Spangler, L.H.; Dobeck, L.M.; Repasky, K.; Nehrir, A.; Humphries, S.; Keith, C.; Shaw, J.; Rouse, J.; Cunningham, A.; Benson, S.; Oldenburg, C.M.; Lewicki, J.L.; Wells, A.; Diehl, R.; Strazisar, B.; Fessenden, J.; Rahn, Thomas; Amonette, J.; Barr, J.; Pickles, W.; Jacobson, J.; Silver, E.; Male, E.; Rauch, H.; Gullickson, K.; Trautz, R.; Kharaka, Y.; Birkholzer, J.; Wielopolski, L.

2009-01-01

A field facility has been developed to allow controlled studies of near surface CO2 transport and detection technologies. The key component of the facility is a shallow, slotted horizontal well divided into six zones. The scale and fluxes were designed to address large scale CO2 storage projects and desired retention rates for those projects. A wide variety of detection techniques were deployed by collaborators from 6 national labs, 2 universities, EPRI, and the USGS. Additionally, modeling of CO2 transport and concentrations in the saturated soil and in the vadose zone was conducted. An overview of these results will be presented. ?? 2009 Elsevier Ltd. All rights reserved.

Predicting long-term performance of engineered geologic carbon dioxide storage systems to inform decisions amidst uncertainty

NASA Astrophysics Data System (ADS)

Pawar, R.

2016-12-01

Risk assessment and risk management of engineered geologic CO2 storage systems is an area of active investigation. The potential geologic CO2 storage systems currently under consideration are inherently heterogeneous and have limited to no characterization data. Effective risk management decisions to ensure safe, long-term CO2 storage requires assessing and quantifying risks while taking into account the uncertainties in a storage site's characteristics. The key decisions are typically related to definition of area of review, effective monitoring strategy and monitoring duration, potential of leakage and associated impacts, etc. A quantitative methodology for predicting a sequestration site's long-term performance is critical for making key decisions necessary for successful deployment of commercial scale geologic storage projects where projects will require quantitative assessments of potential long-term liabilities. An integrated assessment modeling (IAM) paradigm which treats a geologic CO2 storage site as a system made up of various linked subsystems can be used to predict long-term performance. The subsystems include storage reservoir, seals, potential leakage pathways (such as wellbores, natural fractures/faults) and receptors (such as shallow groundwater aquifers). CO2 movement within each of the subsystems and resulting interactions are captured through reduced order models (ROMs). The ROMs capture the complex physical/chemical interactions resulting due to CO2 movement and interactions but are computationally extremely efficient. The computational efficiency allows for performing Monte Carlo simulations necessary for quantitative probabilistic risk assessment. We have used the IAM to predict long-term performance of geologic CO2 sequestration systems and to answer questions related to probability of leakage of CO2 through wellbores, impact of CO2/brine leakage into shallow aquifer, etc. Answers to such questions are critical in making key risk management decisions. A systematic uncertainty quantification approach can been used to understand how uncertain parameters associated with different subsystems (e.g., reservoir permeability, wellbore cement permeability, wellbore density, etc.) impact the overall site performance predictions.

Global change and modern coral reefs: New opportunities to understand shallow-water carbonate depositional processes

NASA Astrophysics Data System (ADS)

Hallock, Pamela

2005-04-01

Human activities are impacting coral reefs physically, biologically, and chemically. Nutrification, sedimentation, chemical pollution, and overfishing are significant local threats that are occurring worldwide. Ozone depletion and global warming are triggering mass coral-bleaching events; corals under temperature stress lose the ability to synthesize protective sunscreens and become more sensitive to sunlight. Photo-oxidative stress also reduces fitness, rendering reef-building organisms more susceptible to emerging diseases. Increasing concentration of atmospheric CO 2 has already reduced CaCO 3 saturation in surface waters by more than 10%. Doubling of atmospheric CO 2 concentration over pre-industrial concentration in the 21st century may reduce carbonate production in tropical shallow marine environments by as much as 80%. As shallow-water reefs decline worldwide, opportunities abound for researchers to expand understanding of carbonate depositional systems. Coordinated studies of carbonate geochemistry with photozoan physiology and calcification, particularly in cool subtropical-transition zones between photozoan-reef and heterotrophic carbonate-ramp communities, will contribute to understanding of carbonate sedimentation under environmental change, both in the future and in the geologic record. Cyanobacteria are becoming increasingly prominent on declining reefs, as these microbes can tolerate strong solar radiation, higher temperatures, and abundant nutrients. The responses of reef-dwelling cyanobacteria to environmental parameters associated with global change are prime topics for further research, with both ecological and geological implications.

Lower Respiration in the Littoral Zone of a Subtropical Shallow Lake

PubMed Central

They, Ng Haig; da Motta Marques, David; Souza, Rafael Siqueira

2013-01-01

Macrophytes are important sources of dissolved organic carbon (DOC) to littoral zones of lakes, but this DOC is believed to be mostly refractory to bacteria, leading to the hypothesis that bacterial metabolism is different in littoral and pelagic zones of a large subtropical shallow lake. We tested this hypothesis by three approaches: (I) dissolved inorganic carbon (DIC) accumulation in littoral and pelagic water; (II) O2 consumption estimate for a cloud of points (n = 47) covering the entire lake; (III) measurement of O2 consumption and CO2 accumulation in dark bottles, pCO2 in the water, lake-atmosphere fluxes of CO2 (fCO2) and a large set of limnological variables at 19 sampling points (littoral and pelagic zones) during seven extensive campaigns. For the first two approaches, DIC and O2 consumption were consistently lower in the littoral zone, and O2 consumption increased marginally with the distance to the nearest shore. For the third approach, we found in the littoral zone consistently lower DOC, total phosphorus (TP), and chlorophyll a, and a higher proportion of low-molecular-weight substances. Regression trees confirmed that high respiration (O2 consumption and CO2 production) was associated to lower concentration of low-molecular-weight substances, while pCO2 was associated to DOC and TP, confirming that CO2 supersaturation occurs in an attempt to balance phosphorus deficiency of macrophyte substrates. Littoral zone fCO2 showed a tendency to be a CO2 sink, whereas the pelagic zone showed a tendency to act as CO2 source to the atmosphere. The high proportion of low-molecular-weight, unreactive substances, together with lower DOC and TP may impose lower rates of respiration in littoral zones. This effect of perennial stands of macrophytes may therefore have important, but not yet quantified implications for the global carbon metabolism of these lakes, but other issues still need to be carefully addressed before rejecting the general belief that macrophytes are always beneficial to bacteria. PMID:23293635

4-D High-Resolution Seismic Reflection Monitoring of Miscible CO2 Injected into a Carbonate Reservoir

DOE Office of Scientific and Technical Information (OSTI.GOV)

Richard D. Miller; Abdelmoneam E. Raef; Alan P. Byrnes

2007-06-30

The objective of this research project was to acquire, process, and interpret multiple high-resolution 3-D compressional wave and 2-D, 2-C shear wave seismic data in the hopes of observing changes in fluid characteristics in an oil field before, during, and after the miscible carbon dioxide (CO{sub 2}) flood that began around December 1, 2003, as part of the DOE-sponsored Class Revisit Project (DOE No.DE-AC26-00BC15124). Unique and key to this imaging activity is the high-resolution nature of the seismic data, minimal deployment design, and the temporal sampling throughout the flood. The 900-m-deep test reservoir is located in central Kansas oomoldic limestonesmore » of the Lansing-Kansas City Group, deposited on a shallow marine shelf in Pennsylvanian time. After 30 months of seismic monitoring, one baseline and eight monitor surveys clearly detected changes that appear consistent with movement of CO{sub 2} as modeled with fluid simulators and observed in production data. Attribute analysis was a very useful tool in enhancing changes in seismic character present, but difficult to interpret on time amplitude slices. Lessons learned from and tools/techniques developed during this project will allow high-resolution seismic imaging to be routinely applied to many CO{sub 2} injection programs in a large percentage of shallow carbonate oil fields in the midcontinent.« less

Massive CO2 Ice Deposits Sequestered in the South Polar Layered Deposits of Mars

USGS Publications Warehouse

Phillips, Roger J.; Davis, Brian J.; Tanaka, Kenneth L.; Byrne, Shane; Mellon, Michael T.; Putzig, Nathaniel E.; Haberle, Robert M.; Kahre, Melinda A.; Campbell, Bruce A.; Carter, Lynn M.; Smith, Isaac B.; Holt, John W.; Smrekar, Suzanne E.; Nunes, Daniel C.; Plaut, Jeffrey J.; Egan, Anthony F.; Titus, Timothy N.; Seu, Roberto

2011-01-01

Shallow Radar soundings from the Mars Reconnaissance Orbiter reveal a buried deposit of carbon dioxide (CO2) ice within the south polar layered deposits of Mars with a volume of 9500 to 12,500 cubic kilometers, about 30 times that previously estimated for the south pole residual cap. The deposit occurs within a stratigraphic unit that is uniquely marked by collapse features and other evidence of interior CO2 volatile release. If released into the atmosphere at times of high obliquity, the CO2 reservoir would increase the atmospheric mass by up to 80%, leading to more frequent and intense dust storms and to more regions where liquid water could persist without boiling.

Soil organic carbon and nitrogen pools drive soil C-CO2 emissions from selected soils in Maritime Antarctica.

PubMed

Pires, C V; Schaefer, C E R G; Hashigushi, A K; Thomazini, A; Filho, E I F; Mendonça, E S

2017-10-15

The ongoing trend of increasing air temperatures will potentially affect soil organic matter (SOM) turnover and soil C-CO 2 emissions in terrestrial ecosystems of Maritime Antarctica. The effects of SOM quality on this process remain little explored. We evaluated (i) the quantity and quality of soil organic matter and (ii) the potential of C release through CO 2 emissions in lab conditions in different soil types from Maritime Antarctica. Soil samples (0-10 and 10-20cm) were collected in Keller Peninsula and the vicinity of Arctowski station, to determine the quantity and quality of organic matter and the potential to emit CO 2 under different temperature scenarios (2, 5, 8 and 11°C) in lab. Soil organic matter mineralization is low, especially in soils with low organic C and N contents. Recalcitrant C form is predominant, especially in the passive pool, which is correlated with humic substances. Ornithogenic soils had greater C and N contents (reaching to 43.15gkg -1 and 5.22gkg -1 for total organic carbon and nitrogen, respectively). C and N were more present in the humic acid fraction. Lowest C mineralization was recorded from shallow soils on basaltic/andesites. C mineralization rates at 2°C were significant lower than at higher temperatures. Ornithogenic soils presented the lowest values of C-CO 2 mineralized by g of C. On the other hand, shallow soils on basaltic/andesites were the most sensitive sites to emit C-CO 2 by g of C. With permafrost degradation, soils on basaltic/andesites and sulfates are expected to release more C-CO 2 than ornithogenic soils. With greater clay contents, more protection was afforded to soil organic matter, with lower microbial activity and mineralization. The trend of soil temperature increases will favor C-CO 2 emissions, especially in the reduced pool of C stored and protected on permafrost, or in occasional Histosols. Copyright © 2016 Elsevier B.V. All rights reserved.

Toward explaining the Holocene carbon dioxide and carbon isotope records: Results from transient ocean carbon cycle-climate simulations

NASA Astrophysics Data System (ADS)

Menviel, L.; Joos, F.

2012-03-01

The Bern3D model was applied to quantify the mechanisms of carbon cycle changes during the Holocene (last 11,000 years). We rely on scenarios from the literature to prescribe the evolution of shallow water carbonate deposition and of land carbon inventory changes over the glacial termination (18,000 to 11,000 years ago) and the Holocene and modify these scenarios within uncertainties. Model results are consistent with Holocene records of atmospheric CO2 and δ13C as well as the spatiotemporal evolution of δ13C and carbonate ion concentration in the deep sea. Deposition of shallow water carbonate, carbonate compensation of land uptake during the glacial termination, land carbon uptake and release during the Holocene, and the response of the ocean-sediment system to marine changes during the termination contribute roughly equally to the reconstructed late Holocene pCO2 rise of 20 ppmv. The 5 ppmv early Holocene pCO2 decrease reflects terrestrial uptake largely compensated by carbonate deposition and ocean sediment responses. Additional small contributions arise from Holocene changes in sea surface temperature, ocean circulation, and export productivity. The Holocene pCO2 variations result from the subtle balance of forcings and processes acting on different timescales and partly in opposite direction as well as from memory effects associated with changes occurring during the termination. Different interglacial periods with different forcing histories are thus expected to yield different pCO2 evolutions as documented by ice cores.

Hydro-ecological controls on dissolved carbon dynamics in groundwater and export to streams in a temperate pine forest

NASA Astrophysics Data System (ADS)

Deirmendjian, Loris; Loustau, Denis; Augusto, Laurent; Lafont, Sébastien; Chipeaux, Christophe; Poirier, Dominique; Abril, Gwenaël

2018-02-01

We studied the export of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) from forested shallow groundwater to first-order streams, based on groundwater and surface water sampling and hydrological data. The selected watershed was particularly convenient for such study, with a very low slope, with pine forest growing on sandy permeable podzol and with hydrology occurring exclusively through drainage of shallow groundwater (no surface runoff). A forest plot was instrumented for continuous eddy covariance measurements of precipitation, evapotranspiration, and net ecosystem exchanges of sensible and latent heat fluxes as well as CO2 fluxes. Shallow groundwater was sampled with three piezometers located in different plots, and surface waters were sampled in six first-order streams; river discharge and drainage were modeled based on four gauging stations. On a monthly basis and on the plot scale, we found a good consistency between precipitation on the one hand and the sum of evapotranspiration, shallow groundwater storage and drainage on the other hand. DOC and DIC stocks in groundwater and exports to first-order streams varied drastically during the hydrological cycle, in relation with water table depth and amplitude. In the groundwater, DOC concentrations were maximal in winter when the water table reached the superficial organic-rich layer of the soil. In contrast, DIC (in majority excess CO2) in groundwater showed maximum concentrations at low water table during late summer, concomitant with heterotrophic conditions of the forest plot. Our data also suggest that a large part of the DOC mobilized at high water table was mineralized to DIC during the following months within the groundwater itself. In first-order streams, DOC and DIC followed an opposed seasonal trend similar to groundwater but with lower concentrations. On an annual basis, leaching of carbon to streams occurred as DIC and DOC in similar proportion, but DOC export occurred in majority during short periods of the highest water table, whereas DIC export was more constant throughout the year. Leaching of forest carbon to first-order streams represented a small portion (approximately 2 %) of the net land CO2 sink at the plot. In addition, approximately 75 % of the DIC exported from groundwater was not found in streams, as it returned very fast to the atmosphere through CO2 degassing.

Microbial Stimulation and Succession following a Test Well Injection Simulating CO₂ Leakage into a Shallow Newark Basin Aquifer

PubMed Central

O’Mullan, Gregory; Dueker, M. Elias; Clauson, Kale; Yang, Qiang; Umemoto, Kelsey; Zakharova, Natalia; Matter, Juerg; Stute, Martin; Takahashi, Taro; Goldberg, David

2015-01-01

In addition to efforts aimed at reducing anthropogenic production of greenhouse gases, geological storage of CO2 is being explored as a strategy to reduce atmospheric greenhouse gas emission and mitigate climate change. Previous studies of the deep subsurface in North America have not fully considered the potential negative effects of CO2 leakage into shallow drinking water aquifers, especially from a microbiological perspective. A test well in the Newark Rift Basin was utilized in two field experiments to investigate patterns of microbial succession following injection of CO2-saturated water into an isolated aquifer interval, simulating a CO2 leakage scenario. A decrease in pH following injection of CO2 saturated aquifer water was accompanied by mobilization of trace elements (e.g. Fe and Mn), and increased bacterial cell concentrations in the recovered water. 16S ribosomal RNA gene sequence libraries from samples collected before and after the test well injection were compared to link variability in geochemistry to changes in aquifer microbiology. Significant changes in microbial composition, compared to background conditions, were found following the test well injections, including a decrease in Proteobacteria, and an increased presence of Firmicutes, Verrucomicrobia and microbial taxa often noted to be associated with iron and sulfate reduction. The concurrence of increased microbial cell concentrations and rapid microbial community succession indicate significant changes in aquifer microbial communities immediately following the experimental CO2 leakage event. Samples collected one year post-injection were similar in cell number to the original background condition and community composition, although not identical, began to revert toward the pre-injection condition, indicating microbial resilience following a leakage disturbance. This study provides a first glimpse into the in situ successional response of microbial communities to CO2 leakage after subsurface injection in the Newark Basin and the potential microbiological impact of CO2 leakage on drinking water resources. PMID:25635675

Potential impacts on groundwater resources of deep CO2 storage: natural analogues for assessing potential chemical effects

NASA Astrophysics Data System (ADS)

Lions, J.; Gale, I.; May, F.; Nygaard, E.; Ruetters, H.; Beaubien, S.; Sohrabi, M.; Hatzignatiou, D. G.; CO2GeoNet Members involved in the present study Team

2011-12-01

Carbon dioxide Capture and Storage (CCS) is considered as one of the promising options for reducing atmospheric emissions of CO2 related to human activities. One of the main concerns associated with the geological storage of CO2 is that the CO2 may leak from the intended storage formation, migrate to the near-surface environment and, eventually, escape from the ground. This is a concern because such leakage may affect aquifers overlying the storage site and containing freshwater that may be used for drinking, industry and agriculture. The IEA Greenhouse Gas R&D Programme (IEAGHG) recently commissioned the CO2GeoNet Association to undertake a review of published and unpublished literature on this topic with the aim of summarizing 'state of the art' knowledge and identifying knowledge gaps and research priorities in this field. Work carried out by various CO2GeoNet members was also used in this study. This study identifies possible areas of conflict by combining available datasets to map the global and regional superposition of deep saline formations (DSF) suitable for CO2 storage and overlying fresh groundwater resources. A scenario classification is developed for the various geological settings where conflict could occur. The study proposes two approaches to address the potential impact mechanisms of CO2 storage projects on the hydrodynamics and chemistry of shallow groundwater. The first classifies and synthesizes changes of water quality observed in natural/industrial analogues and in laboratory experiments. The second reviews hydrodynamic and geochemical models, including coupled multiphase flow and reactive transport. Various models are discussed in terms of their advantages and limitations, with conclusions on possible impacts on groundwater resources. Possible mitigation options to stop or control CO2 leakage are assessed. The effect of CO2 pressure in the host DSF and the potential effects on shallow aquifers are also examined. The study provides a review of CO2 storage-specific regulations in the main countries undertaking CCS evaluation and research. It aims to identify the constraints imposed by existing regulations on the protection of groundwater resources and highlight the inconsistencies and gaps between CCS regulations and Water Protection regulations. The present paper focuses specifically on potential risks on groundwater quality caused by CO2 storage in DSF assessed via natural CO2 analogues from both the literature and detailed European case studies.

Heat-Wave Effects on Oxygen, Nutrients, and Phytoplankton Can Alter Global Warming Potential of Gases Emitted from a Small Shallow Lake.

PubMed

Bartosiewicz, Maciej; Laurion, Isabelle; Clayer, François; Maranger, Roxane

2016-06-21

Increasing air temperatures may result in stronger lake stratification, potentially altering nutrient and biogenic gas cycling. We assessed the impact of climate forcing by comparing the influence of stratification on oxygen, nutrients, and global-warming potential (GWP) of greenhouse gases (the sum of CH4, CO2, and N2O in CO2 equivalents) emitted from a shallow productive lake during an average versus a heat-wave year. Strong stratification during the heat wave was accompanied by an algal bloom and chemically enhanced carbon uptake. Solar energy trapped at the surface created a colder, isolated hypolimnion, resulting in lower ebullition and overall lower GWP during the hotter-than-average year. Furthermore, the dominant CH4 emission pathway shifted from ebullition to diffusion, with CH4 being produced at surprisingly high rates from sediments (1.2-4.1 mmol m(-2) d(-1)). Accumulated gases trapped in the hypolimnion during the heat wave resulted in a peak efflux to the atmosphere during fall overturn when 70% of total emissions were released, with littoral zones acting as a hot spot. The impact of climate warming on the GWP of shallow lakes is a more complex interplay of phytoplankton dynamics, emission pathways, thermal structure, and chemical conditions, as well as seasonal and spatial variability, than previously reported.

How organic carbon derived from multiple sources contributes to carbon sequestration processes in a shallow coastal system?

PubMed Central

Watanabe, Kenta; Kuwae, Tomohiro

2015-01-01

Carbon captured by marine organisms helps sequester atmospheric CO2, especially in shallow coastal ecosystems, where rates of primary production and burial of organic carbon (OC) from multiple sources are high. However, linkages between the dynamics of OC derived from multiple sources and carbon sequestration are poorly understood. We investigated the origin (terrestrial, phytobenthos derived, and phytoplankton derived) of particulate OC (POC) and dissolved OC (DOC) in the water column and sedimentary OC using elemental, isotopic, and optical signatures in Furen Lagoon, Japan. Based on these data analysis, we explored how OC from multiple sources contributes to sequestration via storage in sediments, water column sequestration, and air–sea CO2 exchanges, and analyzed how the contributions vary with salinity in a shallow seagrass meadow as well. The relative contribution of terrestrial POC in the water column decreased with increasing salinity, whereas autochthonous POC increased in the salinity range 10–30. Phytoplankton-derived POC dominated the water column POC (65–95%) within this salinity range; however, it was minor in the sediments (3–29%). In contrast, terrestrial and phytobenthos-derived POC were relatively minor contributors in the water column but were major contributors in the sediments (49–78% and 19–36%, respectively), indicating that terrestrial and phytobenthos-derived POC were selectively stored in the sediments. Autochthonous DOC, part of which can contribute to long-term carbon sequestration in the water column, accounted for >25% of the total water column DOC pool in the salinity range 15–30. Autochthonous OC production decreased the concentration of dissolved inorganic carbon in the water column and thereby contributed to atmospheric CO2 uptake, except in the low-salinity zone. Our results indicate that shallow coastal ecosystems function not only as transition zones between land and ocean but also as carbon sequestration filters. They function at different timescales, depending on the salinity, and OC sources. PMID:25880367

Preliminary Geophysical Characterization of a CO2-Driven Geyser in the Rio Grande Rift, New Mexico

NASA Astrophysics Data System (ADS)

Feucht, D. W.; Jensen, K. J.; Kelly, C.; Ryan, J. C.; Ferriz, H.; Kanjorski, N.; Ferguson, J. F.; McPhee, D. K.; Pellerin, L.

2009-12-01

As part of the Summer of Applied Geophysical Experience (SAGE) a preliminary geophysical investigation was conducted in the vicinity of a cold CO2-driven geyser located at Chimayó, NM, along the eastern margin of the Rio Grand Rift. This geyser is of interest as a possible analog for CO2 leakage from deep saline-aquifer carbon sequestration projects. Observed water chemistry variations can be explained by mixing of a CO2-rich, high salinity brine rising into, and mixing with a shallow freshwater aquifer. Several large, basin bounding faults and numerous smaller normal faults cut the area of the well and may constitute the necessary conduit for the deep water. Geophysical methods were used to characterize the subsurface properties at the Chimayó geyser as well as regional structures that may influence groundwater flow in the area. Shallow transient electromagnetic (TEM) data and capactively-coupled resistivity (CCR) data were acquired in close proximity to the geyser. The CCR shows a near-surface resistive feature, possibly hematite-cemented Tesuque formation sediment, in close proximity to the geyser. A shallow, highly conductive layer delineated through modeling of the TEM data is postulated to be a fluid consistent with high levels of Total Dissolved Solid (TDS) content. The well is located almost directly on the Roberts fault, which is antithetic to the basin bounding Chimayó fault 1.5 km to the east. Previously published hydrogeochemical studies associate this fault with high CO2 and TDS water along its strike. Deeper sounding TEM and audiomagnetotelluric (AMT) data were acquired along the Alamo Arroyo, 3 km to the southwest of the well. The Kelley Federal #1 Well located in this arroyo provides deep stratigraphic control to Pennsylvanian carbonate basement at 740 m. Tesuque formation conglomeritic alluvial fan deposits occur between 230 and 708 m and are overlain by finer grained basin floor deposits. The deep, coarse grained unit is thought to be a good, freshwater aquifer. A 2-D model of the AMT data indicates a resistive layer at about 200 m depth, which may correspond to the aquifer. High conductivity observed in the TEM and AMT data likely reflects saline fluids. Gravity data were collected at approximately 500 m station spacing along transects in Arroyo Alamo and Arroyo Seco 2 km to the south, and throughout the Chimayó Valley. The new data, combined with previously collected data, were used to create regional complete Bouguer anomaly and depth to basement maps. Two-dimensional forward models were constructed to provide a geohydrologic framework consistent with migration of CO2 rich brine up the Chimayó fault to mix with freshwater in the conglomeritic aquifer. The shallow, mixed groundwater emerges at the surface along the Roberts fault and drives the geyser at the Roberts well.

Impact production of CO2 by the Cretaceous/Tertiary extinction bolide and the resultant heating of the earth

NASA Technical Reports Server (NTRS)

O'Keefe, John D.; Ahrens, Thomas J.

1989-01-01

Various observations and data demonstrate that sea level at the end of the Cretaceous was 150-200 m higher than at present, suggesting the possibility that the extinction bolide struck a shallow marine carbonate-rich sedimentary section. It is shown here that the impact of such a bolide (about 5 km in radius) onto a carbonate-rich terrane would increase the CO2 content of the atmosphere by a factor of two to ten. Additional dissolution of CO2 from the ocean's photic zone could release much larger quantities of CO2. The impact-induced release of CO2, by itself, would enhance atmospheric greenhouse heating and give rise to a worldwide increase in temperature from 2 K to 10 K for periods of 10,000 to 100,000 years.

Hydro-geochemical impact of CO2 leakage from geological storage on shallow potable aquifers: A field scale pilot experiment.

NASA Astrophysics Data System (ADS)

Cahill, A.; Jakobsen, R.

2012-04-01

In order to assess the environmental implications of leakage of CO2 from a geological sequestration site into overlying shallow potable aquifers, a 3 month field release experiment is planned to commence in spring 2012 at Vrøgum plantation, Western Denmark. To test the injection and sampling methodologies and as a study of short term effects, a pilot experiment was conducted at the field site: 45 kg of food grade CO2 was injected at 10 m depth over 48 hours into an unconfined, aeolian/glacial sand aquifer and the effects on water chemistry studied. The CO2 was injected through an inclined well installed with a 1 m length of porous polyethylene well screen (20 µm pore size) initially at a rate of 5 litres per minute increasing to 10 litres per minute after 24 hours. Water samples were taken from a network of multi-level sample points (8, 4 and 2.4m depth) before, during and after the injection and measured for physico-chemical parameters and major/trace element composition. Although the site possesses a relatively high hydraulic conductivity (12-16 m/day), due to the small hydraulic gradient (0.0039) 6 days elapsed before effects of CO2 on the ground water were detected in the first sampling point located 0.5 m down flow from the injection well. The dissolved plume of CO2 was observed only in the 8 m depth sample points and moved with flow (approximately 0.10 - 0.12 m/day). The plume spread laterally to 2m width as little as 1 m from the injection screen after 26 days, indicating that CO2 bubbles change the hydraulics of the medium. Dissolved CO2 was not detected in sample points at 4 or 2.4 m depth at any time during the experiment, suggesting gas could not move into the slightly finer grained upper sand. Effects of CO2 dissolution at 8 m depth were manifest as a clear and stable increase in electrical conductivity (approximately 160 to 300 µS/cm), a relatively small increase in total dissolved ions (approximately 30 to 50 mg/l) and an unstable depression of pH (approximately 5.8 to 4.73). The dissolved CO2 plume evolved with a distinct maximal front observed to pass through sample points followed by a slowly dissipating tail. After 56 days the CO2 plume reached the end of the monitoring network and was at its greatest extent (5 m length by 1 m width) however still appeared to be increasing in size suggesting residual gas phase CO2 trapped within the pore space continuously dissolving. Water quality did not significantly deteriorate and only small increases in major and trace elements were observed. Overall, groundwater chemistry results indicate that for an aquifer composed primarily of slowly reacting silicate sediments, such as Vrøgum, the risks to water resources from a short term leak from CCS into shallow overlying aquifers are minimal. However, a potential accumulation effect within the plume front as it moves through the formation was observed inferring a large scale leak may develop a CO2 charged plume exceeding guideline values for major and trace elements.

Direct Experiments on the Ocean Disposal of Fossil Fuel CO2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barry, James, P.

2010-05-26

Funding from DoE grant # FG0204-ER63721, Direct Experiments on the Ocean Disposal of Fossil Fuel CO2, supposed several postdoctoral fellows and research activities at MBARI related to ocean CO2 disposal and the biological consequences of high ocean CO2 levels on marine organisms. Postdocs supported on the project included Brad Seibel, now an associate professor at the University of Rhode Island, Jeff Drazen, now an associate professor at the University of Hawaii, and Eric Pane, who continues as a research associate at MBARI. Thus, the project contributed significantly to the professional development of young scientists. In addition, we made significant progressmore » in several research areas. We continued several deep-sea CO2 release experiments using support from DoE and MBARI, along with several collaborators. These CO2 release studies had the goal of broadening our understanding of the effects of high ocean CO2 levels on deep sea animals in the vicinity of potential release sites for direct deep-ocean carbon dioxide sequestration. Using MBARI ships and ROVs, we performed these experiments at depths of 3000 to 3600 m, where liquid CO2 is heavier than seawater. CO2 was released into small pools (sections of PVC pipe) on the seabed, where it dissolved and drifted downstream, bathing any caged animals and sediments in a CO2-rich, low-pH plume. We assessed the survival of organisms nearby. Several publications arose from these studies (Barry et al. 2004, 2005; Carman et al. 2004; Thistle et al. 2005, 2006, 2007; Fleeger et al. 2006, 2010; Barry and Drazen 2007; Bernhard et al. 2009; Sedlacek et al. 2009; Ricketts et al. in press; Barry et al, in revision) concerning the sensitivity of animals to low pH waters. Using funds from DoE and MBARI, we designed and fabricated a hyperbaric trap-respirometer to study metabolic rates of deep-sea fishes under high CO2 conditions (Drazen et al, 2005), as well as a gas-control aquarium system to support laboratory studies of the effects of high CO2 waters on marine animals (Barry et al. 2008). This system is capable of controlling oxygen, pH, and temperature of seawater for use in studies of the physiological responses of animals under acidified conditions. We have investigated the tolerance of deep- and shallow-living crabs to high CO2 levels (Pane and Barry 2007; Pane et al. 2008), and are now working on brachiopods (Barry et al. in prep.) and a comparison of deep and shallow living sea urchins. This research program, supported in part by DoE has contributed to a number of other publications authored or co-authored by Barry (Caldeira et al. 2005; Brewer and Barry 2008; Barry et al. 2006, 2010a,b,c; National Research Council, in press; Hoffman et al. in press) as well as over 40 invited talks since 2004, including Congressional briefings and testimony at U.S. Senate Hearings on Ocean Acidification. Through the grant period, the research emphasis shifted from studies of the effects of direct deep-sea carbon dioxide sequestration on deep-sea animals, to a broader conceptual framework of the effects of ocean acidification (whether purposeful or passive) on the physiology and survival of deep and shallow living marine animals. We feel that this has been a very productive program and are grateful to DoE for its support.« less

Coalbed methane accumulation and dissipation patterns: A Case study of the Junggar Basin, NW China

NASA Astrophysics Data System (ADS)

Li, Xin; Fu, Xuehai; Yang, Xuesong; Ge, Yanyan; Quan, Fangkai

2018-07-01

The Junggar Basin is a potential replacement area of coalbed methane (CBM) development in China. To improve the efficiency of CBM exploration, we investigated CBM accumulation and dissipation patterns of coal profiles located in the northwestern, southern, eastern, and central Junggar Basin based on the following criteria: burial depth, hydrogeological zone, CBM origin, CBM phase, and CBM migration type. We identified four types of CBM accumulation patterns: (1) a self-sourcing CBM pattern containing adsorbed gas of biogenic origin from shallow-depth coal within a weak runoff zone; (2) an endogenic migration pattern containing adsorbed gas of thermogenic origin from the medium and deep coals within a stagnant zone; (3) an exogenic migration pattern containing adsorbed gas of thermogenic origin from deep coal within a stagnant zone; and (4) an exogenic migration pattern containing adsorbed and free gas of thermogenic origin from ultra-deep coal within a stagnant zone. We also identified two types of CBM dissipation patterns: (1) shallow-depth coal within a runoff zone with mixed origin CBM; and (2) shallow and medium-deep coal seams with mixed origin CBM. CBM migration in low-rank coals was more substantial than that adsorbed in high-rank coal. CBM in shallow coal could easily escape, in the absence of closed structures or hydrogeological seals. CBM reservoirs occurred in deep coal where oversaturated gas may accumulate. Future exploration should focus on gas-water sealing structures in shallow coalbeds. CBM that occurred in adsorbed and free phases and other unconventional natural gas dominated by free gas in the coal stratum should be co-explored and co-developed.

Variability of the carbonate chemistry in a shallow, seagrass-dominated ecosystem: implications for ocean acidification experiments

USGS Publications Warehouse

Challener, Roberta; Robbins, Lisa L.; Mcclintock, James B.

2016-01-01

Open ocean observations have shown that increasing levels of anthropogenically derived atmospheric CO2 are causing acidification of the world's oceans. Yet little is known about coastal acidification and studies are just beginning to characterise the carbonate chemistry of shallow, nearshore zones where many ecologically and economically important organisms occur. We characterised the carbonate chemistry of seawater within an area dominated by seagrass beds (Saint Joseph Bay, Florida) to determine the extent of variation in pH and pCO2 over monthly and daily timescales. Distinct diel and seasonal fluctuations were observed at daily and monthly timescales respectively, indicating the influence of photosynthetic and respiratory processes on the local carbonate chemistry. Over the course of a year, the range in monthly values of pH (7.36-8.28), aragonite saturation state (0.65-5.63), and calculated pCO2 (195-2537 μatm) were significant. When sampled on a daily basis the range in pH (7.70-8.06), aragonite saturation state (1.86-3.85), and calculated pCO2 (379-1019 μatm) also exhibited significant range and indicated variation between timescales. The results of this study have significant implications for the design of ocean acidification experiments where nearshore species are utilised and indicate that coastal species are experiencing far greater fluctuations in carbonate chemistry than previously thought.

Identifying Attributes of CO2 Leakage Zones in Shallow Aquifers Using a Parametric Level Set Method

NASA Astrophysics Data System (ADS)

Sun, A. Y.; Islam, A.; Wheeler, M.

2016-12-01

Leakage through abandoned wells and geologic faults poses the greatest risk to CO2 storage permanence. For shallow aquifers, secondary CO2 plumes emanating from the leak zones may go undetected for a sustained period of time and has the greatest potential to cause large-scale and long-term environmental impacts. Identification of the attributes of leak zones, including their shape, location, and strength, is required for proper environmental risk assessment. This study applies a parametric level set (PaLS) method to characterize the leakage zone. Level set methods are appealing for tracking topological changes and recovering unknown shapes of objects. However, level set evolution using the conventional level set methods is challenging. In PaLS, the level set function is approximated using a weighted sum of basis functions and the level set evolution problem is replaced by an optimization problem. The efficacy of PaLS is demonstrated through recovering the source zone created by CO2 leakage into a carbonate aquifer. Our results show that PaLS is a robust source identification method that can recover the approximate source locations in the presence of measurement errors, model parameter uncertainty, and inaccurate initial guesses of source flux strengths. The PaLS inversion framework introduced in this work is generic and can be adapted for any reactive transport model by switching the pre- and post-processing routines.

Sensitivity of mesquite shrubland CO2 exchange to precipitation in contrasting landscape settings.

PubMed

Potts, Daniel L; Scott, Russell L; Cable, Jessica M; Huxman, Travis E; Williams, David G

2008-10-01

In semiarid ecosystems, physiography (landscape setting) may interact with woody-plant and soil microbe communities to constrain seasonal exchanges of material and energy at the ecosystem scale. In an upland and riparian shrubland, we examined the seasonally dynamic linkage between ecosystem CO2 exchange, woody-plant water status and photosynthesis, and soil respiration responses to summer rainfall. At each site, we compared tower-based measurements of net ecosystem CO2 exchange (NEE) with ecophysiological measurements among velvet mesquite (Prosopis velutina Woot.) in three size classes and soil respiration in sub-canopy and inter-canopy micro-sites. Monsoonal rainfall influenced a greater shift in the magnitude of ecosystem CO2 assimilation in the upland shrubland than in the riparian shrubland. Mesquite water status and photosynthetic gas exchange were closely linked to the onset of the North American monsoon in the upland shrubland. In contrast, the presence of shallow alluvial groundwater in the riparian shrubland caused larger size classes of mesquite to be physiologically insensitive to monsoonal rains. In both shrublands, soil respiration was greatest beneath mesquite canopies and was coupled to shallow soil moisture abundance. Physiography, through its constraint on the physiological sensitivity of deeply rooted woody plants, may interact with plant-mediated rates of soil respiration to affect the sensitivity of semiarid-ecosystem carbon exchange in response to episodic rainfall.

Processes of multibathyal aragonite undersaturation in the Arctic Ocean

USGS Publications Warehouse

Wynn, J.G.; Robbins, L.L.; Anderson, L.G.

2016-01-01

During 3 years of study (2010–2012), the western Arctic Ocean was found to have unique aragonite saturation profiles with up to three distinct aragonite undersaturation zones. This complexity is produced as inflow of Atlantic-derived and Pacific-derived water masses mix with Arctic-derived waters, which are further modified by physiochemical and biological processes. The shallowest aragonite undersaturation zone, from the surface to ∼30 m depth is characterized by relatively low alkalinity and other dissolved ions. Besides local influence of biological processes on aragonite undersaturation of shallow coastal waters, the nature of this zone is consistent with dilution by sea-ice melt and invasion of anthropogenic CO2 from the atmosphere. A second undersaturated zone at ∼90–220 m depth (salinity ∼31.8–35.4) occurs within the Arctic Halocline and is characterized by elevated pCO2 and nutrients. The nature of this horizon is consistent with remineralization of organic matter on shallow continental shelves bordering the Canada Basin and the input of the nutrients and CO2 entrained by currents from the Pacific Inlet. Finally, the deepest aragonite undersaturation zone is at greater than 2000 m depth and is controlled by similar processes as deep aragonite saturation horizons in the Atlantic and Pacific Oceans. The comparatively shallow depth of this deepest aragonite saturation horizon in the Arctic is maintained by relatively low temperatures, and stable chemical composition. Understanding the mechanisms controlling the distribution of these aragonite undersaturation zones, and the time scales over which they operate will be crucial to refine predictive models.

A fundamental study of gas formation and migration during leakage of stored carbon dioxide in subsurface formations

NASA Astrophysics Data System (ADS)

Sakaki, T.; Plampin, M. R.; Lassen, R. N.; Pawar, R. J.; Komatsu, M.; Jensen, K. H.; Illangasekare, T. H.

2011-12-01

Geologic sequestration of CO2 has received significant attention as a potential method for reducing the release of greenhouse gases into the atmosphere. Potential risk of leakage of the stored CO2 to the shallow zones of the subsurface is one of the critical issues that is needed to be addressed to design effective field storage systems. If a leak occurs, gaseous CO2 reaching shallow zones of the subsurface can potentially impact the surface and groundwater sources and vegetation. With a goal of developing models that can predict these impacts, a research study is underway to improve our understanding of the fundamental processes of gas-phase formation and multi-phase flow dynamics during CO2 migration in shallow porous media. The approach involves conducting a series of highly controlled experiments in soil columns and tanks to study the effects of soil properties, temperature, pressure gradients and heterogeneities on gas formation and migration. This paper presents the results from a set of column studies. A 3.6m long column was instrumented with 16 soil moisture sensors, 15 of which were capable of measuring electrical conductivity (EC) and temperature, eight water pressure, and two gas pressure sensors. The column was filled with test sands with known hydraulic and retention characteristics with predetermined packing configurations. Deionized water saturated with CO2 under ~0.3 kPa (roughly the same as the hydrostatic pressure at the bottom of the column) was injected at the bottom of the column using a peristaltic pump. Water and gas outflow at the top of the column were monitored continuously. The results, in general, showed that 1) gas phase formation can be triggered by multiple factors such as water pressure drop, temperature rise, and heterogeneity, 2) transition to gas phase tends to occur rather within a short period of time, 3) gas phase fraction was as high as ~40% so that gas flow was not via individual bubble movement but two-phase flow, 4) water outflow that was initially equal to the inflow rate increased when gas-phase started to form (i.e., water gets displaced), and 5) gas starts to flow upward after gas phase fraction stabilizes (i.e., buoyant force overcomes). These results suggest that the generation and migration processes of gas phase CO2 can be modelled as a traditional two-phase flow with source (when CO2 gas exsolved due to complex factors) as well as sink (when gas dissolved) terms. The experimental data will be used to develop and test the conceptual models that will guide the development of numerical simulators for applications involving CO2 storage and leakage.

[Effects of sand burial on fluxes of greenhouse gases from the soil covered by biocrust in an arid desert region.

PubMed

Teng, Jia Ling; Jia, Rong Liang; Hu, Yi Gang; Xu, Bing Xin; Chen, Meng Chen; Zhao, Yun

2016-03-01

Based on the measurements of the fluxes of CO 2 , CH 4 and N 2 O from the soil covered by two types of biocrusts dominated separately by moss and algae-lichen, followed by 0 (control), 1 (shallow) and 10 (deep) mm depths of sand burial treatments, we studied the effects of sand burial on greenhouse gases fluxes and their relationships with soil temperature and moisture at Shapotou, southeastern edge of the Tengger Desert. The results showed that sand burial had significantly positive effects on CO 2 emission fluxes and CH 4 uptake fluxes of the soil covered by the two types of biocrusts, but imposed differential effects on N 2 O fluxes depending on the type of biocrust and the depth of burial. Deep burial (10 mm) dramatically increased the N 2 O uptake fluxes of the soil co-vered by the two types of biocrusts, while shallow burial (1 mm) decreased the N 2 O uptake flux of the soil co-vered by moss crust only and had no significant effects on N 2 O uptake flux of the soil covered by algae-lichen crust. In addition, CO 2 fluxes of the two biocrusts were closely related to the soil temperature and soil moisture, thereby increasing with the raised soil surface temperature and soil moisture caused by sand burial. However, the relationships of burial-induced changes of soil temperature and moisture with the changes in the other two greenhouse gases fluxes were not evident, indicating that the variations of soil temperature and moisture caused by sand burial were not the key factors affecting the fluxes of CH 4 and N 2 O of the soil covered by the two types of biocrusts.

The Effect of CO 2 on the Measurement of 220Rn and 222Rn with Instruments Utilising Electrostatic Precipitation

DOE PAGES

Lane-Smith, Derek; Sims, Kenneth

2013-06-09

In some volcanic systems, thoron and radon activity and CO 2 flux, in soil and fumaroles, show a relationship between ( 220Rn/ 222Rn) and CO 2 efflux. It is theorized that deep, magmatic sources of gas are characterized by high 222Rn activity and high CO 2 efflux, whereas shallow sources are indicated by high 220Rn activity and relatively low CO 2 efflux. In this paper we evaluate whether the observed inverse relationship is a true geochemical signal, or potentially an analytical artifact of high CO 2 concentrations. We report results from a laboratory experiment using the RAD7 radon detector, knownmore » 222Rn (radon) and 220Rn (thorn), and a controllable percentage of CO 2 in the carrier gas. Our results show that for every percentage of CO 2, the 220Rn reading should be multiplied by 1.019, the 222Rn radon should be multiplied by 1.003 and the 220Rn/ 222Rn ratio should be multiplied by 1.016 to correct for the presence of the CO 2.« less

The Effect of CO 2 on the Measurement of 220Rn and 222Rn with Instruments Utilising Electrostatic Precipitation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lane-Smith, Derek; Sims, Kenneth

In some volcanic systems, thoron and radon activity and CO 2 flux, in soil and fumaroles, show a relationship between ( 220Rn/ 222Rn) and CO 2 efflux. It is theorized that deep, magmatic sources of gas are characterized by high 222Rn activity and high CO 2 efflux, whereas shallow sources are indicated by high 220Rn activity and relatively low CO 2 efflux. In this paper we evaluate whether the observed inverse relationship is a true geochemical signal, or potentially an analytical artifact of high CO 2 concentrations. We report results from a laboratory experiment using the RAD7 radon detector, knownmore » 222Rn (radon) and 220Rn (thorn), and a controllable percentage of CO 2 in the carrier gas. Our results show that for every percentage of CO 2, the 220Rn reading should be multiplied by 1.019, the 222Rn radon should be multiplied by 1.003 and the 220Rn/ 222Rn ratio should be multiplied by 1.016 to correct for the presence of the CO 2.« less

Tolerance of allogromiid Foraminifera to severely elevated carbon dioxide concentrations: Implications to future ecosystem functioning and paleoceanographic interpretations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernhard, Joan M.; Mollo-Christensen, Elizabeth; Eisenkolb, Nadine

2009-02-01

Increases in the partial pressure of carbon dioxide (pCO2) in the atmosphere will significantly affect a wide variety of terrestrial fauna and flora. Because of tight atmospheric oceanic coupling, shallow-water marine species are also expected to be affected by increases in atmospheric carbon dioxide concentrations. One proposed way to slow increases in atmospheric pCO2 is to sequester CO2 in the deep sea. Thus, over the next few centuries marine species will be exposed to changing seawater chemistry caused by ocean atmospheric exchange and/or deep-ocean sequestration. This initial case study on one allogromiid foraminiferal species (Allogromia laticollaris) was conducted to beginmore » to ascertain the effect of elevated pCO2 on benthic Foraminifera, which are a major meiofaunal constituent of shallow- and deep-water marine communities. Cultures of this thecate foraminiferan protist were used for 10-14-day experiments. Experimental treatments were executed in an incubator that controlled CO2 (15000; 30 000; 60 000; 90 000; 200 000 ppm), temperature and humidity; atmospheric controls (i.e., ~375 ppm CO2) were executed simultaneously. Although the experimental elevated pCO2 values are far above foreseeable surface water pCO2, they were selected to represent the spectrum of conditions expected for the benthos if deep-sea CO2 sequestration becomes a reality. Survival was assessed in two independent ways: pseudopodial presence/absence and measurement of adenosine triphosphate (ATP), which is an indicator of cellular energy. Substantial proportions of A. laticollaris populations survived 200 000 ppm CO2 although the mean of the median [ATP] of survivors was statistically lower for this treatment than for that of atmospheric control specimens. After individuals that had been incubated in 200 000 ppm CO2 for 12 days were transferred to atmospheric conditions for ~24 h, the [ATP] of live specimens (survivors) approximated those of the comparable atmospheric control treatment. Incubation in 200 000 ppm CO2 also resulted in reproduction by some individuals. Results suggest that certain Foraminifera are able to tolerate deep-sea CO2 sequestration and perhaps thrive as a result of elevated pCO2 that is predicted for the next few centuries, in a high-pCO2 world. Thus, allogromiid foraminiferal blooms may result from climate change. Furthermore, because allogromiids consume a variety of prey, it is likely that they will be major players in ecosystem dynamics of future coastal sedimentary environments.« less

Tolerance of allogromiid Foraminifera to severely elevated carbon dioxide concentrations: Implications to future ecosystem functioning and paleoceanographic interpretations

NASA Astrophysics Data System (ADS)

Bernhard, Joan M.; Mollo-Christensen, Elizabeth; Eisenkolb, Nadine; Starczak, Victoria R.

2009-02-01

Increases in the partial pressure of carbon dioxide (pCO 2) in the atmosphere will significantly affect a wide variety of terrestrial fauna and flora. Because of tight atmospheric-oceanic coupling, shallow-water marine species are also expected to be affected by increases in atmospheric carbon dioxide concentrations. One proposed way to slow increases in atmospheric pCO 2 is to sequester CO 2 in the deep sea. Thus, over the next few centuries marine species will be exposed to changing seawater chemistry caused by ocean-atmospheric exchange and/or deep-ocean sequestration. This initial case study on one allogromiid foraminiferal species ( Allogromia laticollaris) was conducted to begin to ascertain the effect of elevated pCO 2 on benthic Foraminifera, which are a major meiofaunal constituent of shallow- and deep-water marine communities. Cultures of this thecate foraminiferan protist were used for 10-14-day experiments. Experimental treatments were executed in an incubator that controlled CO 2 (15 000; 30 000; 60 000; 90 000; 200 000 ppm), temperature and humidity; atmospheric controls (i.e., ~ 375 ppm CO 2) were executed simultaneously. Although the experimental elevated pCO 2 values are far above foreseeable surface water pCO 2, they were selected to represent the spectrum of conditions expected for the benthos if deep-sea CO 2 sequestration becomes a reality. Survival was assessed in two independent ways: pseudopodial presence/absence and measurement of adenosine triphosphate (ATP), which is an indicator of cellular energy. Substantial proportions of A. laticollaris populations survived 200 000 ppm CO 2 although the mean of the median [ATP] of survivors was statistically lower for this treatment than for that of atmospheric control specimens. After individuals that had been incubated in 200 000 ppm CO 2 for 12 days were transferred to atmospheric conditions for ~ 24 h, the [ATP] of live specimens (survivors) approximated those of the comparable atmospheric control treatment. Incubation in 200 000 ppm CO 2 also resulted in reproduction by some individuals. Results suggest that certain Foraminifera are able to tolerate deep-sea CO 2 sequestration and perhaps thrive as a result of elevated pCO 2 that is predicted for the next few centuries, in a high-pCO 2 world. Thus, allogromiid foraminiferal "blooms" may result from climate change. Furthermore, because allogromiids consume a variety of prey, it is likely that they will be major players in ecosystem dynamics of future coastal sedimentary environments.

CO2 Storage related Groundwater Impacts and Protection

NASA Astrophysics Data System (ADS)

Fischer, Sebastian; Knopf, Stefan; May, Franz; Rebscher, Dorothee

2016-03-01

Injection of CO2 into the deep subsurface will affect physical and chemical conditions in the storage environment. Hence, geological CO2 storage can have potential impacts on groundwater resources. Shallow freshwater can only be affected if leakage pathways facilitate the ascent of CO2 or saline formation water. Leakage associated with CO2 storage cannot be excluded, but potential environmental impacts could be reduced by selecting suitable storage locations. In the framework of risk assessment, testing of models and scenarios against operational data has to be performed repeatedly in order to predict the long-term fate of CO2. Monitoring of a storage site should reveal any deviations from expected storage performance, so that corrective measures can be taken. Comprehensive R & D activities and experience from several storage projects will enhance the state of knowledge on geological CO2 storage, thus enabling safe storage operations at well-characterised and carefully selected storage sites while meeting the requirements of groundwater protection.

Spatial variability in degassing at Erebus volcano, Antarctica

NASA Astrophysics Data System (ADS)

Ilanko, Tehnuka; Oppenheimer, Clive; Kyle, Philip; Burgisser, Alain

2015-04-01

Erebus volcano on Ross Island, Antarctica, hosts an active phonolitic lava lake, along with a number of persistently degassing vents in its summit crater. Flank degassing also occurs through ice caves and towers. The longevity of the lake, and its stable convection, have been the subject of numerous studies, including Fourier transform infrared (FTIR) spectroscopy of the lava lake. Two distinct gas compositions were previously identified in the main lava lake plume (Oppenheimer et al., 2009; 2011): a persistent 'conduit' gas with a more oxidised signature, ascribed to degassing through a permeable magma conduit; and a H2O- and SO2- enriched 'lake' composition that increases and decreases cyclically due to shallow degassing of incoming magma batches. During the past decade of annual field seasons on Erebus, gas compositions have been measured through FTIR spectroscopy at multiple sites around Erebus volcano, including flank degassing through an ice cave (Warren Cave). We present measurements from four such vents, and compare their compositions to those emitted from the main lava lake. Summit degassing involves variable proportions of H2O, CO2, CO, SO2, HF, HCl, OCS. Cyclicity is evident in some summit vents, but with signatures indicative of shallower magmatic degassing than that of the lava lake. By contrast, flank degassing at Warren Cave is dominated by H2O, CO2, and CH4. The spatial variability in gas compositions within the summit crater suggests an alternative origin for 'conduit' and 'lake' degassing to previous models that assume permeability in the main conduit. Rather, the two compositions observed in main lake degassing may be a result of decoupled 'conduit' gas and pulses of magma rising through discrete fractures before combining in the lake floor or the main plume. Smaller vents around the crater thus emit isolated 'lake' or 'conduit' compositions while their combined signature is observed in the lava lake. We suggest that this separation between gas sources is enabled by a complex shallow fracture network, collapses of which also promote frequent changes to crater morphology. Flank degassing results from decoupling and ascent of CO2-rich gas through deeper fractures, and re-equilibration to lower temperatures and pressures.

Textural and geochemical characteristics of marine sediments in the SW Gulf of Mexico: implications for source and seasonal change.

PubMed

Rosales-Hoz, Leticia; Carranza-Edwards, Arturo; Martinez-Serrano, Raymundo G; Alatorre, Miguel Angel; Armstrong-Altrin, John S

2015-04-01

Two oceanographic cruises were taken during the winter (SAV I, November and December 2007) and summer (SAV II, July and August 2008) across the mouth of the Papaloapan River in the Gulf of Mexico. Surficial sediment samples were collected from shallow (16-30 m), intermediate (30 to 80 m), and deeper areas (≥300 m). Shallow water sediments are coarser, better-sorted, and primarily composed of sands during the winter, while those found in the summer are finer. At depths greater than 30 m, sediments are primarily fine-grained no matter the season. Major element analysis from shallow areas indicates higher SiO2 concentrations during the windy season with negative correlation against Al2O3 during both seasons, following the respective abundances of sand and muds. High organic carbon content was observed in shallow areas during the summer. Trace metals V, Ni, Cu, Zn, Pb, Li, Cr, Co, and Ba were evaluated. The first six metals showed higher average concentration in the deeper areas, although the highest values at some individual sampling sites for Cr, Co, Cu, and Ba were observed in the coastal area. Factor and cluster analysis were used to explain the sediment distribution pattern and the factors that determine the sediment characteristics within the study area. In shallow areas, four clusters were observed during the winter and five during the summer. The geochemical characteristics of the samples in each cluster suggest association with fluvial sediment input, textural characteristics, heavy minerals, and Cu and Ba concentration. To evaluate the variations in heavy metal concentration, metal enrichment factors (EFs) were calculated. Enrichment in V, Cr, Co, Zn, Ba, and Pb was detected at certain sites, whereas Cu behaved differently. The distribution of Cu enrichment suggests that it may be of natural origin, associated with the lithology of the volcanic continental area. The minor enrichment observed for other elements may be associated with river discharge. According to sediment quality guidelines, trace metal concentrations of Cu, Pb, and Zn present occasional risks to aquatic organisms.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Birkholzer, Jens; Apps, John; Zheng, Liange

One promising approach to reduce greenhouse gas emissions is injecting CO{sub 2} into suitable geologic formations, typically depleted oil/gas reservoirs or saline formations at depth larger than 800 m. Proper site selection and management of CO{sub 2} storage projects will ensure that the risks to human health and the environment are low. However, a risk remains that CO{sub 2} could migrate from a deep storage formation, e.g. via local high-permeability pathways such as permeable faults or degraded wells, and arrive in shallow groundwater resources. The ingress of CO{sub 2} is by itself not typically a concern to the water qualitymore » of an underground source of drinking water (USDW), but it will change the geochemical conditions in the aquifer and will cause secondary effects mainly induced by changes in pH, in particular the mobilization of hazardous inorganic constituents present in the aquifer minerals. Identification and assessment of these potential effects is necessary to analyze risks associated with geologic sequestration of CO{sub 2}. This report describes a systematic evaluation of the possible water quality changes in response to CO{sub 2} intrusion into aquifers currently used as sources of potable water in the United States. Our goal was to develop a general understanding of the potential vulnerability of United States potable groundwater resources in the event of CO{sub 2} leakage. This goal was achieved in two main tasks, the first to develop a comprehensive geochemical model representing typical conditions in many freshwater aquifers (Section 3), the second to conduct a systematic reactive-transport modeling study to quantify the effect of CO{sub 2} intrusion into shallow aquifers (Section 4). Via reactive-transport modeling, the amount of hazardous constituents potentially mobilized by the ingress of CO{sub 2} was determined, the fate and migration of these constituents in the groundwater was predicted, and the likelihood that drinking water standards might be exceeded was evaluated. A variety of scenarios and aquifer conditions was considered in a sensitivity evaluation. The scenarios and conditions simulated in Section 4, in particular those describing the geochemistry and mineralogy of potable aquifers, were selected based on the comprehensive geochemical model developed in Section 3.« less

Hydrological controls on riverine carbon export in a seasonally wet tropical catchment

NASA Astrophysics Data System (ADS)

Duvert, C.; Hutley, L. B.; Bossa, M.; Bird, M. I.; Munksgaard, N.; Wynn, J. G.; Setterfield, S. A.; Northwood, M.

2017-12-01

Understanding the movement of carbon (C) through the landscape is critical for accurate C accounting. Failure to account for the transport of terrestrially-derived C to aquifers and streams can result in a considerable over-estimation of the C sequestration by the biosphere. Here we report on the magnitude of C export via shallow groundwater and adjacent streams in a savanna-covered seasonally wet tropical catchment of northern Australia. Riverine fluxes of carbon dioxide (CO2), dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) were measured at a high resolution over a full year to gain insight into the drivers of C export in this system. Water and C stable isotopes were also measured in order to elucidate water sources and dominant flow pathways. Our results suggest that CO2 evasion was the major process contributing to riverine C loss in the catchment (111 kg C ha-1 yr-1). The downstream export of C was dominated by DOC (78 kg C ha-1 yr-1), while DIC accounted for 39 kg C ha-1 yr-1 of the annual export. The bulk of annual DOC export was flushed out during the very first high-flow events, with export decreasing throughout the wet season to pre-flood levels. In contrast, the DIC flux was more important during flow recession, upon activation of deeper flowpaths carrying geologically-derived C. Shallow groundwater measured in boreholes was supersaturated with CO2 (15,000 < pCO2 < 55,000 ppm), whereas in-stream concentrations were an order of magnitude lower, suggesting substantial outgassing of CO2. Our findings outline the key role of point-source groundwater discharge in riverine CO2 evasion, with C largely sourced from seasonally productive savanna vegetation. Given the complexity of this pathway and the magnitude of this flux, new methods are needed to more precisely quantify CO2 evasion.

Trace gas emissions from tropical biomass fires: Yucatan Peninsula, Mexico

NASA Astrophysics Data System (ADS)

Cofer, Wesley R.; Levine, Joel S.; Winstead, Edward L.; Stocks, Brian J.; Cahoon, Donald R.; Pinto, Joseph P.

Mixing ratios for carbon dioxide (CO 2), carbon monoxide (CO), hydrogen (H 2), methane (CH 4) and total non-methane hydrocarbons (TNMHC) were determined from the smoke plumes of two small (˜0.25 ha) prescribed biomass fires conducted on the Yucatan Peninsula in Mexico. In the region of these fires the combination of climate and shallow soils produces a scrubby and stunted forest with species composition similar to the Brazilian rain forest, but at a noticeably reduced size. Aircraft collections of smoke from these fires were analysed and used to determine CO 2-normalized emission ratios ( ΔX/ ΔCO 2; v/v; where Δ = in-plume specie concentration less background concentration) for CO, H 2, CH 4 and TNMHC produced and released into the atmosphere from these fires. Suprisingly, high mean emission ratios for TNMHCs (˜1.7% of CO 2 release) and H 2 (˜2.5% of CO 2) were determined. Emission ratios for CO (˜7%) and CH 4 (˜0.7%), however, were found to fall within expected bounds.

Annual cycle of magmatic CO2 in a tree-kill soil at Mammoth Mountain, California: implications for soil acidification

USGS Publications Warehouse

McGee, K.A.; Gerlach, T.M.

1998-01-01

Time-series sensor data reveal significant short-term and seasonal variations of magmatic CO2 in soil over a 12 month period in 1995-1996 at the largest tree-kill site on Mammoth Mountain, central-eastern California. Short-term variations leading to ground-level soil CO2 concentrations hazardous and lethal to humans were triggered by shallow faulting in the absence of increased seismicity or intrusion, consistent with tapping a reservoir of accumulated CO2, rather than direct magma degassing. Hydrologic processes closely modulated seasonal variations in CO2 concentrations, which rose to 65%-100% in soil gas under winter snowpack and plunged more than 25% in just days as the CO2 dissolved in spring snowmelt. The high efflux of CO2 through the tree-kill soils acts as an open-system CO2 buffer causing infiltration of waters with pH values commonly of < 4.2, acid loading of up to 7 keqH+.ha-1.yr-1, mobilization of toxic Al3+, and long-term decline of soil fertility.

CO2 geosequestration at the laboratory scale: Combined geophysical and hydromechanical assessment of weakly-cemented shallow Sleipner-like reservoirs

NASA Astrophysics Data System (ADS)

Falcon-Suarez, I.; North, L. J.; Best, A. I.

2017-12-01

To date, the most promising mitigation strategy for reducing global carbon emissions is Carbon Capture and Storage (CCS). The storage technology (i.e., CO2 geosequestration, CGS) consists of injecting CO2 into deep geological formations, specifically selected for such massive-scale storage. To guarantee the mechanical stability of the reservoir during and after injection, it is crucial to improve existing monitoring techniques for controlling CGS activities. We developed a comprehensive experimental program to investigate the integrity of the Sleipner CO2 storage site in the North Sea - the first commercial CCS project in history where 1 Mtn/y of CO2 has been injected since 1996. We assessed hydro-mechanical effects and the related geophysical signatures of three synthetic sandstones and samples from the Utsira Sand formation (main reservoir at Sleipner), at realistic pressure-temperature (PT) conditions and fluid compositions. Our experimental approach consists of brine-CO2 flow-through tests simulating variable inflation/depletion scenarios, performed in the CGS-rig (Fig. 1; Falcon-Suarez et al., 2017) at the National Oceanography Centre (NOC) in Southampton. The rig is designed for simultaneous monitoring of ultrasonic P- and S-wave velocities and attenuations, electrical resistivity, axial and radial strains, pore pressure and flow, during the co-injection of up to two fluids under controlled PT conditions. Our results show velocity-resistivity and seismic-geomechanical relations of practical importance for the distinction between pore pressure and pore fluid distribution during CGS activities. By combining geophysical and thermo-hydro-mechano-chemical coupled information, we can provide laboratory datasets that complement in situ seismic, geomechanical and electrical survey information, useful for the CO2 plume monitoring in Sleipner site and other shallow weakly-cemented sand CCS reservoirs. Falcon-Suarez, I., Marín-Moreno, H., Browning, F., Lichtschlag, A., Robert, K., North, L.J., Best, A.I., 2017. Experimental assessment of pore fluid distribution and geomechanical changes in saline sandstone reservoirs during and after CO2 injection. International Journal of Greenhouse Gas Control 63, 356-369.

Reduced ventilation and enhanced magnitude of the deep Pacific carbon pool during the last glacial period

NASA Astrophysics Data System (ADS)

Skinner, L.; McCave, I. N.; Carter, L.; Fallon, S.; Scrivner, A. E.; Primeau, F.

2015-02-01

It has been proposed that the ventilation of the deep Pacific carbon pool was not significantly reduced during the last glacial period, posing a problem for canonical theories of glacial-interglacial CO2 change. However, using radiocarbon dates of marine tephra deposited off New Zealand, we show that deep- (> 2000 m) and shallow sub-surface ocean-atmosphere 14C age offsets (i.e. "reservoir-" or "ventilation" ages) in the southwest Pacific increased by ˜1089 and 337 yrs respectively, reaching ˜2689 and ˜1037 yrs during the late glacial. A comparison with other radiocarbon data from the southern high-latitudes suggests that broadly similar changes were experienced right across the Southern Ocean. If, like today, the Southern Ocean was the main source of water to the glacial ocean interior, these observations would imply a significant change in the global radiocarbon inventory during the last glacial period, possibly equivalent to an increase in the average radiocarbon age > 2 km of ˜ 700 yrs. Simple mass balance arguments and numerical model sensitivity tests suggest that such a change in the ocean's mean radiocarbon age would have had a major impact on the marine carbon inventory and atmospheric CO2, possibly accounting for nearly half of the glacial-interglacial CO2 change. If confirmed, these findings would underline the special role of high latitude shallow sub-surface mixing and air-sea gas exchange in regulating atmospheric CO2 during the late Pleistocene.

Initial Results from the Deep Drilling of Lake Junin, Perú

NASA Astrophysics Data System (ADS)

Rodbell, D. T.; Abbott, M. B.; Weidhaas, N.; Hatfield, R. G.; Woods, A.; Hillman, A. L.; Tapia, P. M.; Chen, C. Y.; McGee, D.; Stoner, J. S.

2016-12-01

Lake Junín (11.0°S, 76.2°W, 4085 masl) is an intermontane, high-elevation lake in the inner-tropics of the Southern Hemisphere that spans 300 km2. With a maximum water depth of 12m, Lake Junin is dammed at its northern and southern ends by alluvial fans that emanate from glacial valleys in both cordillera. These fans can be traced to moraines that are >250 ka, indicating that the lake is at least this old. During the maximum extent of late Cenozoic glaciation, glaciers reached the lake edge but at no time over the last 1 million years, or more, has Lake Junín been overridden by ice. Lake Junín is thus one of the few lakes in the tropical Andes that predates the maximum extent of glaciation and is in a geomorphic position to record the waxing and waning of alpine glaciers in nearby cordillera. Sediment cores obtained between 1980 and 1996 reveal that sediment deposited during the last glacial cycle ( 30-16 ka) is dominated by glacial flour whereas sediment deposited during the last 16 ka consists predominantly of authigenic calcite (marl) with ostracod carapaces punctuated with intervals of gyttja and peat. In July and August of 2015, piston cores were obtained from three sites in Lake Junin. Multiple overlapping cores from the deepest water site (Site 1) extend to 100 m below lake floor (mblf), and those from two shallow water, paleoglacier-proximal sites (Sites 2 and 3) extend 23 and 51 mblf, respectively. Samples acquired at 8-cm resolution from Site 1 were analyzed for total organic carbon (TOC) and total inorganic carbon [as Ca(Mg)CO3; TIC] by coulometry. Total carbon (TC) was analyzed by combusting 10 mg samples at 1000°C and quantifying the resultant CO2 by coulometry whereas TIC was analyzed by reacting 10 mg samples in 6N H3PO4 and quantifying the resultant CO2 by coulometry; TOC was determined from TOC=TC-TIC. Over the last glacial postglacial cycle (last 30 ka), mean CaCO3 and TOC concentrations in Site 1 cores are higher ( 33% and 7.4%, respectively) than those in shallow water settings ( 9.5% and 4%). Similarly, mean magnetic susceptibility (MS) is lower in Site 1 cores (6.9 SI) than in the most paleoglacier-proximal shallow water site (Site 2, 9.4 SI). Site 1 records 7 glacial and interglacial cycles whereas shallow water locations appear to be dominated by sediment deposited during the last glacial-interglacial cycle.

Field demonstration of CO2 leakage detection in potable aquifers with a pulselike CO2-release test.

PubMed

Yang, Changbing; Hovorka, Susan D; Delgado-Alonso, Jesus; Mickler, Patrick J; Treviño, Ramón H; Phillips, Straun

2014-12-02

This study presents two field pulselike CO2-release tests to demonstrate CO2 leakage detection in a shallow aquifer by monitoring groundwater pH, alkalinity, and dissolved inorganic carbon (DIC) using the periodic groundwater sampling method and a fiber-optic CO2 sensor for real-time in situ monitoring of dissolved CO2 in groundwater. Measurements of groundwater pH, alkalinity, DIC, and dissolved CO2 clearly deviated from their background values, showing responses to CO2 leakage. Dissolved CO2 observed in the tests was highly sensitive in comparison to groundwater pH, DIC, and alkalinity. Comparison of the pulselike CO2-release tests to other field tests suggests that pulselike CO2-release tests can provide reliable assessment of geochemical parameters indicative of CO2 leakage. Measurements by the fiber-optic CO2 sensor, showing obvious leakage signals, demonstrated the potential of real-time in situ monitoring of dissolved CO2 for leakage detection at a geologic carbon sequestration (GCS) site. Results of a two-dimensional reactive transport model reproduced the geochemical measurements and confirmed that the decrease in groundwater pH and the increases in DIC and dissolved CO2 observed in the pulselike CO2-release tests were caused by dissolution of CO2 whereas alkalinity was likely affected by carbonate dissolution.

Effects of High Carbon Dioxide Soil-Gas Concentrations and Emission Rates From Mammoth Mountain, California, USA

NASA Astrophysics Data System (ADS)

Farrar, C. D.; Evans, W. C.

2006-12-01

High concentrations (90 vol %) of carbon dioxide (CO2) are present in shallow soils, and CO2 is emitted to the atmosphere at high rates (1,000 g/d/m2), in several locations around Mammoth Mountain. The CO2 emissions have been diffuse and at ambient temperature. CO2 in the soil has killed most of the coniferous forest in five areas totaling 35 ha around the north, west, and south sides of the mountain at altitudes between 2,600 and 3,000 m. Part of the CO2 has dissolved in ground water, causing acidic conditions and severely corroding steel casings in several wells. The high CO2 emission rates are implicated in the deaths of four people in the past eight years. During winter, a large quantity of CO2 is sequestered in the snow pack on parts of the mountain, posing potential dangers for winter recreation. One U.S. Forest Service campground has been closed and safety plans have been implemented by the local ski resort. Mammoth Mountain is a dormant Quaternary volcanic center, but overlies an area that has been affected by periods of magmatic unrest during the past two decades. Hypocenters of long-period earthquakes indicate that basaltic intrusions reach depths as shallow as 20 to 15 km, from which CO2 has exsolved during decompression and (or) crystallization of these intrusions. CO2 moves to the land surface along fracture zones associated with faults and possibly geologic contacts. The magmatic source of CO2 is confirmed by ¦Ä13C = -3 to -5 PDB, a lack of 14C, and 3He/4He = 4 to 5 R/RA. The present-day high CO2 soil-gas concentrations and emission rates were first documented in 1994; however, anecdotal information and low 14C in post-1989 tree rings suggest that an abrupt increase in both concentrations and emission rates probably began in 1990, following a 6-month period of seismic swarm activity beneath the mountain. Emissions in an area on the south flank of the mountain have been the focus of CO2 monitoring and have shown no indications of abatement between 1994 and 2005, during which estimates of the total CO2 efflux ranged from 90 to 150 MT/d. The variations can be partly attributed to the precision of the techniques and to minor differences in measurement protocols between researchers; variations in soil- moisture and atmospheric conditions alone can cause fluctuations in efflux of ± 10% over periods of hours to days.

Uncertainty analyses of CO2 plume expansion subsequent to wellbore CO2 leakage into aquifers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hou, Zhangshuan; Bacon, Diana H.; Engel, David W.

2014-08-01

In this study, we apply an uncertainty quantification (UQ) framework to CO2 sequestration problems. In one scenario, we look at the risk of wellbore leakage of CO2 into a shallow unconfined aquifer in an urban area; in another scenario, we study the effects of reservoir heterogeneity on CO2 migration. We combine various sampling approaches (quasi-Monte Carlo, probabilistic collocation, and adaptive sampling) in order to reduce the number of forward calculations while trying to fully explore the input parameter space and quantify the input uncertainty. The CO2 migration is simulated using the PNNL-developed simulator STOMP-CO2e (the water-salt-CO2 module). For computationally demandingmore » simulations with 3D heterogeneity fields, we combined the framework with a scalable version module, eSTOMP, as the forward modeling simulator. We built response curves and response surfaces of model outputs with respect to input parameters, to look at the individual and combined effects, and identify and rank the significance of the input parameters.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hornibrook, E.R.C.; Longstaffe, F.J.; Fyfe, W.S.

The identity and distribution of substrates that support CH{sub 4} production in wetlands is poorly known at present. Organic compounds are the primary methanogenic precursor at all depths within anoxic wetland soils; however, the distribution of microbial processes by which these compounds are ultimately converted to CH{sub 4} is uncertain. Based on stable isotope measurements of CH{sub 4} and {Sigma}CO{sub 2} extracted from soil porewaters in two temperate zone wetlands, we present evidence that a systematic spatial distribution of microbial methanogenic pathways can exist in certain anoxic, organic-rich soils. CH{sub 4} production by the acetate fermentation pathway is favored inmore » the shallow subsurface. while methanogenesis from the reduction of CO{sub 2} with H{sub 2} becomes more predominant in older, less reactive peat at depth. This distribution can account for many of the reported CH{sub 4} emission characteristics of wetlands, in particular, their sensitivity to changes in primary productivity, temperature, and hydrology. These factors play an important role in controlling the short-term supply of labile substrates to fermentive methanogens in the shallow subsurface where the most intense CH{sub 4} production occurs. Predominance of the CO{sub 2}-reduction pathway at depth may help to explain reports of CH{sub 4} with a semifossil age in lower peat layers. 60 refs., 7 figs., 1 tab.« less

Likelihood of Brine and CO 2 Leak Detection using Magnetotellurics and Electrical Resistivity Tomography Methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, X.; Buscheck, T. A.; Mansoor, K.

The US DOE National Risk Assessment Partnership (NRAP), funded through the Office of Fossil Energy and NETL, is developing methods to evaluate the effectiveness of monitoring techniques to detect brine and CO 2 leakage from legacy wells into underground sources of drinking water (USDW) overlying a CO 2 storage reservoir. As part of the NRAP Strategic Monitoring group, we have generated 140 simulations of aquifer impact data based on the Kimberlina site in California’s southern San Joaquin Basin, Kimberlina Rev. 1.1. CO 2 buoyancy allows some of the stored CO 2 to reach shallower permeable zones and is detectable withmore » surface geophysical sensors. We are using this simulated data set to evaluate effectiveness of electrical resistivity tomography (ERT) and magnetotellurics (MT) for leak detection. The evaluation of additional monitoring methods such as pressure, seismic and gravity is underway through a multi-lab collaboration.« less

Geochemical and hydrological characterization of shallow aquifer water following a nearby deep CO2 injection in Wellington, Kansas

NASA Astrophysics Data System (ADS)

Datta, S.; Andree, I.; Johannesson, K. H.; Kempton, P. D.; Barker, R.; Birdie, T. R.; Watney, W. L.

2017-12-01

Salinization or CO2 leakage from local Enhanced Oil Recovery (EOR) projects has become a possible source for contamination and water quality degradation for local irrigation or potable well users in Wellington, Kansas. Shallow domestic and monitoring wells, as well as surface water samples collected from the site, were analyzed for a wide array of geochemical proxies including major and trace ions, rare earth elements (REE), stable isotopes, dissolved organic carbon and dissolved hydrocarbons; these analytes were employed as geotracers to understand the extent of hydrologic continuity throughout the Paleozoic stratigraphic section. Previous research by Barker et al. (2012) laid the foundation through a mineralogical and geochemical investigation of the Arbuckle injection zone and assessment of overlying caprock integrity, which led to the conclusion that the 4,910-5,050' interval will safely sequester CO2 with high confidence of a low leakage potential. EOR operations using CO2 as the injectant into the Mississippian 3,677-3,706' interval was initiated in Jan 2016. Two groundwater sampling events were conducted to investigate any temporal changes in the surface and subsurface waters. Dissolved (Ca+Mg)/Na and Na/Cl mass ratio values of two domestic wells and one monitoring well ranged from 0.67 to 2.01 and 0.19 to 0.39, respectively, whereas a nearby Mississippian oil well had values of 0.20 and 0.62, respectively . δ18O and δ2H ranged from -4.74 to -5.41 ‰VSMOW and -31.4 to -34.3 ‰VSMOW, respectively, among the domestic wells and shallowest monitoring well. Conservative ion relationships in drill-stem-test waters from Arbuckle and Mississippian injection zones displayed significant variability, indicating limited vertical hydrologic communication. Total aquifer connectivity is inconclusive based on the provided data; however, a paleoterrace and incised valley within the study site are thought to be connected through a Mississippian salt plume migration passing through the major domestic wells and a well at 200 ft depth. REE patterns of the shallow monitoring wells indicate a different water source than the domestic wells in the study area.

Diel CO2 cycles reduce severity of behavioural abnormalities in coral reef fish under ocean acidification.

PubMed

Jarrold, Michael D; Humphrey, Craig; McCormick, Mark I; Munday, Philip L

2017-08-31

Elevated CO 2 levels associated with ocean acidification (OA) have been shown to alter behavioural responses in coral reef fishes. However, all studies to date have used stable pCO 2 treatments, not considering the substantial diel pCO 2 variation that occurs in shallow reef habitats. Here, we reared juvenile damselfish, Acanthochromis polyacanthus, and clownfish, Amphiprion percula, at stable and diel cycling pCO 2 treatments in two experiments. As expected, absolute lateralization of A. polyacanthus and response to predator cue of Am. percula were negatively affected in fish reared at stable, elevated pCO 2 in both experiments. However, diel pCO 2 fluctuations reduced the negative effects of OA on behaviour. Importantly, in experiment two, behavioural abnormalities that were present in fish reared at stable 750 µatm CO 2 were largely absent in fish reared at 750 ± 300 µatm CO 2 . Overall, we show that diel pCO 2 cycles can substantially reduce the severity of behavioural abnormalities caused by elevated CO 2 . Thus, past studies may have over-estimated the impacts of OA on the behavioural performance of coral reef fishes. Furthermore, our results suggest that diel pCO 2 cycles will delay the onset of behavioural abnormalities in natural populations.

Downhole monitoring of biogenic gas production at the Maguelone shallow injection experimental site (Languedoc coastline, France).

NASA Astrophysics Data System (ADS)

Abdelghafour, H.; Brondolo, F.; Denchik, N.; Pezard, P. A.

2014-12-01

The controllability of CO2 geological storage can ensure the integrity of storage operations, requiring a precise monitoring of reservoir fluids and properties during injection and over time. In this context, deep saline aquifers offer a large capacity of storing CO2, but the accessibility to long term behavior studies remains limited until now. The Maguelone shallow experimental site located near Montpellier (Languedoc, France) provides such an opportunity for the understanding and accuracy of hydrogeophysical monitoring methods. The geology, petrophysic and hydrology of this site have been studied in details in previous studies, revealing the presence of a thin saline aquifer at 13-16 m depth surrounded by clay-rich materials. The site as a whole provides a natural laboratory to study CO2 injection at field scale, shallow depth, hence reasonable costs. The monitoring setup is composed of a series of hydrogeophysical and geochemical methods offering measurements of fluid pore pressure, electrical resistivity, acoustic velocities as well as pH and fluid properties and chemistry. To assess the response of the reservoir during CO2 injection, all measurements need to be compared to a representative baseline. Long after a series of gas injection experiments at Maguelone, fluctuations overtime of reservoir fluids and properties (such as pore fluid pH) were discovered at steady state, demonstrating the natural variability of the site in terms of biogenic gas (H2S, CH4, CO2) production and transfer. For this, a new resistivity baseline had to be constructed for all observatories. From this, the downhole gas saturation was determined versus depth and time from time-lapse resistivity logs analysed on the basis of other logs and laboratory measurements. The Waxman and Smits model (1968) for electrical properties of sand-clay formations was modified to estimate the gas saturation in 4D, to account for surface conductivity and pore connectivity. High frequency logging and monitoring of electrical properties both, with several measurements per hour and a dm-scale resolution, provide and insight into subsurface dynamics in terms of gas flow and storage, with biogenic gas saturations ranging from 0.1 to 5.0 %. This natural contribution has to be taken into account for upcoming experiments.

Tropical CO2 seeps reveal the impact of ocean acidification on coral reef invertebrate recruitment.

PubMed

Allen, Ro; Foggo, Andrew; Fabricius, Katharina; Balistreri, Annalisa; Hall-Spencer, Jason M

2017-11-30

Rising atmospheric CO 2 concentrations are causing ocean acidification by reducing seawater pH and carbonate saturation levels. Laboratory studies have demonstrated that many larval and juvenile marine invertebrates are vulnerable to these changes in surface ocean chemistry, but challenges remain in predicting effects at community and ecosystem levels. We investigated the effect of ocean acidification on invertebrate recruitment at two coral reef CO 2 seeps in Papua New Guinea. Invertebrate communities differed significantly between 'reference' (median pH7.97, 8.00), 'high CO 2 ' (median pH7.77, 7.79), and 'extreme CO 2 ' (median pH7.32, 7.68) conditions at each reef. There were also significant reductions in calcifying taxa, copepods and amphipods as CO 2 levels increased. The observed shifts in recruitment were comparable to those previously described in the Mediterranean, revealing an ecological mechanism by which shallow coastal systems are affected by near-future levels of ocean acidification. Copyright © 2016 Elsevier Ltd. All rights reserved.

Increasing CO2 flux at Pisciarelli, Campi Flegrei, Italy

NASA Astrophysics Data System (ADS)

Queißer, Manuel; Granieri, Domenico; Burton, Mike; Arzilli, Fabio; Avino, Rosario; Carandente, Antonio

2017-09-01

The Campi Flegrei caldera is located in the metropolitan area of Naples (Italy) and has been undergoing different stages of unrest since 1950, evidenced by episodes of significant ground uplift followed by minor subsidence, increasing and fluctuating emission strengths of water vapor and CO2 from fumaroles, and periodic seismic crises. We deployed a scanning laser remote-sensing spectrometer (LARSS) that measured path-integrated CO2 concentrations in the Pisciarelli area in May 2017. The resulting mean CO2 flux is 578 ± 246 t d-1. Our data suggest a significant increase in CO2 flux at this site since 2015. Together with recent geophysical observations, this suggests a greater contribution of the magmatic source to the degassing and/or an increase in permeability at shallow levels. Thanks to the integrated path soundings, LARSS may help to give representative measurements from large regions containing different CO2 sources, including fumaroles, low-temperature vents, and degassing soils, helping to constrain the contribution of deep gases and their migration mechanisms towards the surface.

Volcanic carbon dioxide vents show ecosystem effects of ocean acidification.

PubMed

Hall-Spencer, Jason M; Rodolfo-Metalpa, Riccardo; Martin, Sophie; Ransome, Emma; Fine, Maoz; Turner, Suzanne M; Rowley, Sonia J; Tedesco, Dario; Buia, Maria-Cristina

2008-07-03

The atmospheric partial pressure of carbon dioxide (p(CO(2))) will almost certainly be double that of pre-industrial levels by 2100 and will be considerably higher than at any time during the past few million years. The oceans are a principal sink for anthropogenic CO(2) where it is estimated to have caused a 30% increase in the concentration of H(+) in ocean surface waters since the early 1900s and may lead to a drop in seawater pH of up to 0.5 units by 2100 (refs 2, 3). Our understanding of how increased ocean acidity may affect marine ecosystems is at present very limited as almost all studies have been in vitro, short-term, rapid perturbation experiments on isolated elements of the ecosystem. Here we show the effects of acidification on benthic ecosystems at shallow coastal sites where volcanic CO(2) vents lower the pH of the water column. Along gradients of normal pH (8.1-8.2) to lowered pH (mean 7.8-7.9, minimum 7.4-7.5), typical rocky shore communities with abundant calcareous organisms shifted to communities lacking scleractinian corals with significant reductions in sea urchin and coralline algal abundance. To our knowledge, this is the first ecosystem-scale validation of predictions that these important groups of organisms are susceptible to elevated amounts of p(CO(2)). Sea-grass production was highest in an area at mean pH 7.6 (1,827 (mu)atm p(CO(2))) where coralline algal biomass was significantly reduced and gastropod shells were dissolving due to periods of carbonate sub-saturation. The species populating the vent sites comprise a suite of organisms that are resilient to naturally high concentrations of p(CO(2)) and indicate that ocean acidification may benefit highly invasive non-native algal species. Our results provide the first in situ insights into how shallow water marine communities might change when susceptible organisms are removed owing to ocean acidification.

U-tube based near-surface environmental monitoring in the Shenhua carbon dioxide capture and storage (CCS) project.

PubMed

Li, Qi; Song, Ranran; Shi, Hui; Ma, Jianli; Liu, Xuehao; Li, Xiaochun

2018-04-01

The CO 2 injected into deep formations during implementation of carbon dioxide (CO 2 ) capture and storage (CCS) technology may leak and migrate into shallow aquifers or ground surfaces through a variety of pathways over a long period. The leaked CO 2 can threaten shallow environments as well as human health. Therefore, almost all monitoring programs for CCS projects around the world contain near-surface monitoring. This paper presents a U-tube based near-surface monitoring technology focusing on its first application in the Shenhua CCS demonstration project, located in the Ordos Basin, Inner Mongolia, China. First, background information on the site monitoring program of the Shenhua CCS demonstration project was provided. Then, the principle of fluid sampling and the monitoring methods were summarized for the U-tube sampler system, and the monitoring data were analyzed in detail. The U-tube based monitoring results showed that the U-tube sampler system is accurate, flexible, and representative of the subsurface fluid sampling process. The monitoring indicators for the subsurface water and soil gas at the Shenhua CCS site indicate good stratification characteristics. The concentration level of each monitoring indicator decreases with increasing depth. Finally, the significance of this near-surface environmental monitoring technology for CO 2 leakage assessments was preliminarily confirmed at the Shenhua CCS site. The application potential of the U-tube based monitoring technology was also demonstrated during the subsurface environmental monitoring of other CCS projects.

Mantle to surface degassing of alkalic magmas at Erebus volcano, Antarctica

USGS Publications Warehouse

Oppenheimer, C.; Moretti, R.; Kyle, P.R.; Eschenbacher, A.; Lowenstern, J. B.; Hervig, R.L.; Dunbar, N.W.

2011-01-01

Continental intraplate volcanoes, such as Erebus volcano, Antarctica, are associated with extensional tectonics, mantle upwelling and high heat flow. Typically, erupted magmas are alkaline and rich in volatiles (especially CO2), inherited from low degrees of partial melting of mantle sources. We examine the degassing of the magmatic system at Erebus volcano using melt inclusion data and high temporal resolution open-path Fourier transform infrared (FTIR) spectroscopic measurements of gas emissions from the active lava lake. Remarkably different gas signatures are associated with passive and explosive gas emissions, representative of volatile contents and redox conditions that reveal contrasting shallow and deep degassing sources. We show that this unexpected degassing signature provides a unique probe for magma differentiation and transfer of CO2-rich oxidised fluids from the mantle to the surface, and evaluate how these processes operate in time and space. Extensive crystallisation driven by CO2 fluxing is responsible for isobaric fractionation of parental basanite magmas close to their source depth. Magma deeper than 4kbar equilibrates under vapour-buffered conditions. At shallower depths, CO2-rich fluids accumulate and are then released either via convection-driven, open-system gas loss or as closed-system slugs that ascend and result in Strombolian eruptions in the lava lake. The open-system gases have a reduced state (below the QFM buffer) whereas the closed-system gases preserve their deep oxidised signatures (close to the NNO buffer). ?? 2011 Elsevier B.V.

Microbial succession and stimulation following a test well injection simulating CO2 leakage into shallow Newark Basin aquifers

NASA Astrophysics Data System (ADS)

Dueker, M.; Clauson, K.; Yang, Q.; Umemoto, K.; Seltzer, A. M.; Zakharova, N. V.; Matter, J. M.; Stute, M.; Takahashi, T.; Goldberg, D.; O'Mullan, G. D.

2012-12-01

Despite growing appreciation for the importance of microbes in altering geochemical reactions in the subsurface, the microbial response to geological carbon sequestration injections and the role of microbes in altering metal mobilization following leakage scenarios in shallow aquifers remain poorly constrained. A Newark Basin test well was utilized in field experiments to investigate patterns of microbial succession following injection of CO2 saturated water into isolated aquifer intervals. Additionally, laboratory mesocosm experiments, including microbially-active and inactive (autoclave sterilized) treatments, were used to constrain the microbial role in mineral dissolution, trace metal release, and gas production (e.g. hydrogen and methane). Hydrogen production was detected in both sterilized and unsterilized laboratory mesocosm treatments, indicating abiotic hydrogen production may occur following CO2 leakage, and methane production was detected in unsterilized, microbially active mesocosms. In field experiments, a decrease in pH following injection of CO2 saturated aquifer water was accompanied by mobilization of trace elements (e.g. Fe and Mn), the production of hydrogen gas, and increased bacterial cell concentrations. 16S ribosomal RNA clone libraries, from samples collected before and after the test well injection, were compared in an attempt to link variability in geochemistry to changes in aquifer microbiology. Significant changes in microbial composition, compared to background conditions, were found following the test well injection, including a decrease in Proteobacteria, and an increased presence of Firmicutes, Verrucomicrobia, Acidobacteria and other microbes associated with iron reducing and syntrophic metabolism. The concurrence of increased microbial cell concentration, and rapid microbial community succession, with increased concentrations of hydrogen gas suggests that abiotically produced hydrogen may serve as an ecologically-relevant energy source stimulating changes in aquifer microbial communities immediately following CO2 leakage.

Elevated carbon dioxide flux at the Dixie Valley geothermal field, Nevada; relations between surface phenomena and the geothermal reservoir

USGS Publications Warehouse

Bergfeld, D.; Goff, F.; Janik, C.J.

2001-01-01

In the later part of the 1990s, a large die-off of desert shrubs occurred over an approximately 1 km2 area in the northwestern section of the Dixie Valley (DV) geothermal field. This paper reports results from accumulation-chamber measurements of soil CO2 flux from locations in the dead zone and stable isotope and chemical data on fluids from fumaroles, shallow wells, and geothermal production wells within and adjacent to the dead zone. A cumulative probability plot shows three types of flux sites within the dead zone: Locations with a normal background CO2 flux (7 g m-2 day-1); moderate flux sites displaying "excess" geothermal flux; and high flux sites near young vents and fumaroles. A maximum CO2 flux of 570 g m-2 day-1 was measured at a location adjacent to a fumarole. Using statistical methods appropriate for lognormally distributed populations of data, estimates of the geothermal flux range from 7.5 t day-1 from a 0.14-km2 site near the Stillwater Fault to 0.1 t day-1 from a 0.01 -km2 location of steaming ground on the valley floor. Anomalous CO2 flux is positively correlated with shallow temperature anomalies. The anomalous flux associated with the entire dead zone area declined about 35% over a 6-month period. The decline was most notable at a hot zone located on an alluvial fan and in the SG located on the valley floor. Gas geochemistry indicates that older established fumaroles along the Stillwater Fault and a 2-year-old vent in the lower section of the dead zone discharge a mixture of geothermal gases and air or gases from air-saturated meteoric water (ASMW). Stable isotope data indicate that steam from the smaller fumaroles is produced by ??? 100??C boiling of these mixed fluids and reservoir fluid. Steam from the Senator fumarole (SF) and from shallow wells penetrating the dead zone are probably derived by 140??C to 160??C boiling of reservoir fluid. Carbon-13 isotope data suggest that the reservoir CO2 is produced mainly by thermal decarbonation of hydrothermal calcite in veins that cut reservoir rocks. Formation of the dead zone is linked to the reservoir pressure decline caused by continuous reservoir drawdown from 1986 to present. These reservoir changes have restricted flow and induced boiling in a subsurface hydrothermal outflow plume extending from the Stillwater Fault southeast toward the DV floor. We estimate that maximum CO2 flux in the upflow zone along the Stillwater Fault in 1998 was roughly seven to eight times greater than the pre-production flux in 1986. The eventual decline in CO2 flux reflects the drying out of the outflow plume. Published by Elsevier Science B.V.

Seaweed fails to prevent ocean acidification impact on foraminifera along a shallow-water CO2 gradient.

PubMed

Pettit, Laura R; Smart, Christopher W; Hart, Malcolm B; Milazzo, Marco; Hall-Spencer, Jason M

2015-05-01

Ocean acidification causes biodiversity loss, alters ecosystems, and may impact food security, as shells of small organisms dissolve easily in corrosive waters. There is a suggestion that photosynthetic organisms could mitigate ocean acidification on a local scale, through seagrass protection or seaweed cultivation, as net ecosystem organic production raises the saturation state of calcium carbonate making seawater less corrosive. Here, we used a natural gradient in calcium carbonate saturation, caused by shallow-water CO2 seeps in the Mediterranean Sea, to assess whether seaweed that is resistant to acidification (Padina pavonica) could prevent adverse effects of acidification on epiphytic foraminifera. We found a reduction in the number of species of foraminifera as calcium carbonate saturation state fell and that the assemblage shifted from one dominated by calcareous species at reference sites (pH ∼8.19) to one dominated by agglutinated foraminifera at elevated levels of CO2 (pH ∼7.71). It is expected that ocean acidification will result in changes in foraminiferal assemblage composition and agglutinated forms may become more prevalent. Although Padina did not prevent adverse effects of ocean acidification, high biomass stands of seagrass or seaweed farms might be more successful in protecting epiphytic foraminifera.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Lingling; Ma, Yulin; Cheng, Xinqun

LiCoO 2/mesocarbon microbeads (MCMB) batteries are over-charged to different voltage (4.4 V, 4.5 V, 4.6 V, and 4.7 V, respectively) for ten times, and then are cycled 1000 times for shallow depth of discharge. The morphology, structure, and electrochemical performance of the electrode materials were studied in detail in order to identify the capacity fading mechanism of over-charged battery after long-term cycling. The cycling performances of LiCoO 2/MCMB batteries are gradually aggravated with the increase of over-charging voltage and the degradation mechanism is diverse upon the degree of over-charging. Furthermore, the capacity fading after long-term cycling of battery over-charged tomore » 4.6 V or 4.7 V is mainly attributed to the cathodes. Soft X-ray absorption spectroscopy (XAS) demonstrates that the lower valence state of cobalt exists on the surface of the LiCoO 2 after serious over-charging (4.6 V or 4.7 V), and cobalt is dissolved then deposited on the anode according to the result of energy dispersive spectrometry (EDS). But, after shallow over-charging (4.4 V or 4.5 V), the capacity deterioration is proposed as the loss of active lithium, presented by the generation of the SEI film on the anode, which is verified by water washed tests.« less

Seaweed fails to prevent ocean acidification impact on foraminifera along a shallow-water CO2 gradient

PubMed Central

Pettit, Laura R; Smart, Christopher W; Hart, Malcolm B; Milazzo, Marco; Hall-Spencer, Jason M

2015-01-01

Ocean acidification causes biodiversity loss, alters ecosystems, and may impact food security, as shells of small organisms dissolve easily in corrosive waters. There is a suggestion that photosynthetic organisms could mitigate ocean acidification on a local scale, through seagrass protection or seaweed cultivation, as net ecosystem organic production raises the saturation state of calcium carbonate making seawater less corrosive. Here, we used a natural gradient in calcium carbonate saturation, caused by shallow-water CO2 seeps in the Mediterranean Sea, to assess whether seaweed that is resistant to acidification (Padina pavonica) could prevent adverse effects of acidification on epiphytic foraminifera. We found a reduction in the number of species of foraminifera as calcium carbonate saturation state fell and that the assemblage shifted from one dominated by calcareous species at reference sites (pH ∼8.19) to one dominated by agglutinated foraminifera at elevated levels of CO2 (pH ∼7.71). It is expected that ocean acidification will result in changes in foraminiferal assemblage composition and agglutinated forms may become more prevalent. Although Padina did not prevent adverse effects of ocean acidification, high biomass stands of seagrass or seaweed farms might be more successful in protecting epiphytic foraminifera. PMID:26140195

Carbon dioxide emissions from the flat bottom and shallow Nam Theun 2 Reservoir: drawdown area as a neglected pathway to the atmosphere

NASA Astrophysics Data System (ADS)

Deshmukh, Chandrashekhar; Guérin, Frédéric; Vongkhamsao, Axay; Pighini, Sylvie; Oudone, Phetdala; Sopraseuth, Saysoulinthone; Godon, Arnaud; Rode, Wanidaporn; Guédant, Pierre; Oliva, Priscia; Audry, Stéphane; Zouiten, Cyril; Galy-Lacaux, Corinne; Robain, Henri; Ribolzi, Olivier; Kansal, Arun; Chanudet, Vincent; Descloux, Stéphane; Serça, Dominique

2018-03-01

Freshwater reservoirs are a significant source of CO2 to the atmosphere. CO2 is known to be emitted at the reservoir surface by diffusion at the air-water interface and downstream of dams or powerhouses by degassing and along the river course. In this study, we quantified total CO2 emissions from the Nam Theun 2 Reservoir (Lao PDR) in the Mekong River watershed. The study started in May 2009, less than a year after flooding and just a few months after the maximum level was first reached and lasted until the end of 2013. We tested the hypothesis that soils from the drawdown area would be a significant contributor to the total CO2 emissions.Total inorganic carbon, dissolved and particulate organic carbon and CO2 concentrations were measured in 4 pristine rivers of the Nam Theun watershed, at 9 stations in the reservoir (vertical profiles) and at 16 stations downstream of the monomictic reservoir on a weekly to monthly basis. CO2 bubbling was estimated during five field campaigns between 2009 and 2011 and on a weekly monitoring, covering water depths ranging from 0.4 to 16 m and various types of flooded ecosystems in 2012 and 2013. Three field campaigns in 2010, 2011 and 2013 were dedicated to the soils description in 21 plots and the quantification of soil CO2 emissions from the drawdown area. On this basis, we calculated total CO2 emissions from the reservoir and carbon inputs from the tributaries. We confirm the importance of the flooded stock of organic matter as a source of carbon (C) fuelling emissions. We show that the drawdown area contributes, depending on the year, from 40 to 75 % of total annual gross emissions in this flat and shallow reservoir. Since the CO2 emissions from the drawdown zone are almost constant throughout the years, the large interannual variations result from the significant decrease in diffusive fluxes and downstream emissions between 2010 and 2013. This overlooked pathway in terms of gross emissions would require an in-depth evaluation for the soil organic matter and vegetation dynamics to evaluate the actual contribution of this area in terms of net modification of gas exchange in the footprint of the reservoir, and how it could evolve in the future.

Geochemistry of carbon and sulfur in the 2.7 Ga stromatolitic carbonate and shale (ABDP#10 core) from Meentheena, Western Australia

NASA Astrophysics Data System (ADS)

Tomiuka, T.; Yamaguchi, K. E.

2014-12-01

Earth's surface environments about 2.7 Ga ago likely experienced drastic changes such as rapid continental growth, negative excursion of organic carbon isotopes, and positive excursion of mass-independently fractionated sulfur isotopes. Discovery of biomarkers indicating cyanobacteria, although questionable, was also claimed. The coeval shallow ocean could have contained appreciable amount of molecular O2 produced by cyanobacteria, but it has been unknown whether deep sea was oxygenated by ocean circulation. In order to unravel the shallow water environment, we obtained modern-weathering-free 2.7 Ga drilcore samples of stromatolitic carbonate and shale by Archean Biosphere Drilling Project (ABDP#10 core) in Meentheena, NE Western Australia. The purpose of this study is to extract information regarding the surface ocean chemistry by abundance (of various species) and corresponding stable isotope compositions of carbon and sulfur. Based on mass balance calculation, we obtained a much reduced fraction of organic carbon to total carbon (forg) to be 0.11 (c.f., Phanerozoic average is 0.2), suggesting that aerobic and/or anaerobic decomposition of organic matter was vigorous. The very low δ13Corg values suggest carbon recycling involving methanogenesis by methanogen (e.g., 2CH2O → CH4 + CO2) accompanied by large isotope fractionation. Generated CH4 was oxidized by methylotroph to CO2, which was reused to form organic matter by biochemical processes such as photosynthesis. Either O2 or SO42- was required to facilitate CH4 oxidation, suggesting availability of oxidized species in the 2.7 Ga shallow sea environment. Abundance of Spy with near zero δ34Spy values suggest syndepositional and/or diagenetic formation of bacteriogenic pyrite utilizing sulfate formed by oxidation of mantle-derived sulfur (δ34S ≈ 0‰). A plot of Spy vs. Corg abundance shows a trend falling between a Phanerozoic normal marine trend (Spy/Corg = 0.36) and a freshwater trend (Spy << Corg), suggesting formation of Spy in environments fluctuating between near normal marine and fresh water conditions with low SO42- concentration. We suggest that the 2.7 Ga shallow water near Meentheena was slightly oxic in lacustrine setting.

Sensitivity of climate and atmospheric CO2 to deep-ocean and shallow-ocean carbonate burial

NASA Technical Reports Server (NTRS)

Volk, Tyler

1989-01-01

A model of the carbonate-silicate geochemical cycle is presented that distinguishes carbonate masses produced by shallow-ocean and deep-ocean carbonate burial and shows that reasonable increases in deep-ocean burial could produce substantial warmings over a few hundred million years. The model includes exchanges between crust and mantle; transients from burial shifts are found to be sensitive to the fraction of nondegassed carbonates subducted into the mantle. Without the habitation of the open ocean by plankton such as foraminifera and coccolithophores, today's climate would be substantially colder.

CO2 Exsolution from CO2 Saturated Water: Core-Scale Experiments and Focus on Impacts of Pressure Variations.

PubMed

Xu, Ruina; Li, Rong; Ma, Jin; Jiang, Peixue

2015-12-15

For CO2 sequestration and utilization in the shallow reservoirs, reservoir pressure changes are due to the injection rate changing, a leakage event, and brine withdrawal for reservoir pressure balance. The amounts of exsolved CO2 which are influenced by the pressure reduction and the subsequent secondary imbibition process have a significant effect on the stability and capacity of CO2 sequestration and utilization. In this study, exsolution behavior of the CO2 has been studied experimentally using a core flooding system in combination with NMR/MRI equipment. Three series of pressure variation profiles, including depletion followed by imbibitions without or with repressurization and repetitive depletion and repressurization/imbibition cycles, were designed to investigate the exsolution responses for these complex pressure variation profiles. We found that the exsolved CO2 phase preferentially occupies the larger pores and exhibits a uniform spatial distribution. The mobility of CO2 is low during the imbibition process, and the residual trapping ratio is extraordinarily high. During the cyclic pressure variation process, the first cycle has the largest contribution to the amount of exsolved CO2. The low CO2 mobility implies a certain degree of self-sealing during a possible reservoir depletion.

Endogenous gas hazard at Pizzillo (Stromboli Island, Italy)

NASA Astrophysics Data System (ADS)

Tarchini, L.; Carapezza, M. L.; Ranaldi, M.; Ricci, T.

2009-04-01

In open-conduit volcanoes like Stromboli or Etna, the major degassing is associated to the plume emission from the craters. However the presence of faults and fractures acts as preferential pathway for gas escaping to the surface, thus there is also a relevant CO2 diffuse degassing from the soil from most of the edifice. In the inhabited areas on these volcanoes, natural gases can accumulate in houses generating potential hazards. Pizzillo is one of the anomalous degassing zone located near the sea shore, in the inhabited area of Stromboli. It is well known to local people for the presence of a mofette lethal to small animals and of a shallow thermal aquifer (T= 35-42 °C). It has a high dissolved CO2 content and is mostly fed by sea water and heated by gas rising from depth. High CO2 concentration has been found in the soil (17 % and 40 %, at 50 and 100 cm depth). Chemical and isotopic data of soil gas indicate a deep magmatic provenance. Interesting anomalies of CO2 and other dissolved gases, including C and He isotopes, have been recorded in this thermal shallow aquifer before the 2002 eruption onset and the 5 April 2003 paroxysm, suggesting an increasing input of gas released from an uprising magma body. The presence in this coastal zone of NE-SW trending fractures is confirmed also by the results of a shallow electromagnetic survey carried out in 2004 using a multifrequency (625 to 19,925 Hz) GEM 300 with investigation depth of 30 to 50 m depending on ground resistivity. Most of the CO2 emission of Pizzillo occurs along a N64E° trending fracture extending uphill toward Rina Grande, and along which a series of flank collapses occurred. The CO2 soil flux map, carried out over 3200 m2, delineates two anomalies oriented NE-SW on both sides of an house, that is severely exposed to gas hazard. This house, where people mostly live during summer, is located just in the middle of the most CO2 soil emissive zone. It has a window very near to the rock cut from where most CO2 is emitted. As such a location is severely exposed to gas hazard, indoor CO2 air concentration was repeatedly measured within a ground room where the gas, denser than air, could accumulate up to reach dangerous levels. An automatic Dräger X-am 7000 devise, which records CO2 concentration every minute, was used; it was placed at 10 cm from the ground. The first measures, carried out from 29 July to 2 August 2006, gave very dangerous concentration values up to 8 vol.% that were always recorded in periods of no or very low wind. A longer survey was carried out from 7 March to 15 May 2007, during and after the last Stromboli eruption, with some interruptions due to power cuts. Results confirm the high gas hazard of this house, as immediately lethal CO2 air concentration (10 %) is often reached or exceeded. In order to ascertain from where the gas was coming, a second Dräger was placed on the windowsill at 2 m from the ground. Results clearly show that CO2 was mostly entering the room from this window, as very high concentrations were found with peaks shortly preceding those recorded near the ground. This prevented to recommend room aeration, which is the most elementary precautionary measure in these cases. We suggested the owner to wall up that window and impermeabilise the floor. During five days of measurements, carried out in January 2008 after the completion of these works, [CO2] was mostly at its normal air value.

Single hole multi-parameter downhole monitoring of shallow CO2 injection at Maguelone experimental site (Languedoc, France)

NASA Astrophysics Data System (ADS)

Denchik, N.; Pezard, P. A.; Abdoulghafour, H.; Lofi, J.; Neyens, D.; Perroud, H.; Henry, G.; Rolland, B.

2015-12-01

The Maguelone experimental site for shallow subsurface hydrogeophysical monitoring, located along the Mediterranean Lido near Montpellier (Languedoc, France) has proven over the years to provide a unique setup to test gas storage monitoring methods at shallow depth. The presence of two small reservoirs (R1: 13-16 m and R2: 8-9 m) with impermeable boundaries provides an opportunity to study a saline formation for geological storage both in the field and in a laboratory context. This integrated monitoring concept was first applied at Maguelone for characterization of the reservoir state before and during N2 and CO2 injections as part of the MUSTANG FP7 project. Multimethod monitoring was shown to be sensitive to gas storage within a saline reservoir with clear data changes immediately after the beginning of injection. Pressure remains the first indicator of gas storage at ~8-9 m depth in a small permeable unit (gravels/shells) under the Holocene lagoonal sediments. A good correlation is also obtained between the resistivity response and geochemical parameters from pore fluid sampling (pH, minor and major cation concentrations) at this depth. On the basis of previous gas injection experiments, new holes were drilled as part of PANACEA (EC project) in 2014, including an injection hole targeted for injection at 8-9 m depth in the R2 reservoir in order to have gas injection and gas storage at the same depth, a single hole multi-parameter observatory, and a seismic source hole. A total volume of ~48 m3 of CO2 was injected over ~2 hours on December 4, 2014. The injection rate varied from 24 to 30 m3/h, with a well head pressure of 1.8 bars. All downhole monitoring technologies (resistivity, temperature, pressure, SP and seismic measurements) were combined in the single hole observatory. Such device allows monitoring the downhole system before and after injection and the gas migration from the injection hole, helping to characterize the transport mechanism. Decreasing the number of monitoring-measurements and verification (MMV) holes enables a significant decrease of gas leakage risk. This specific monitoring approach is expected to give information about the safety and reliability of CO2 storage operation that guarantees public acceptance.

Effects of 12-crown-4 ether on the electrochemical performance of CoO2 and TiS2 cathodes in Li polymer electrolyte cells

NASA Technical Reports Server (NTRS)

Nagasubramanian, G.; Attia, Alan I.; Halpert, G.

1992-01-01

The effect of adding 12-crown-4 ether (12Cr4) to the polyethylene oxide (PEO) electrolyte on the electrochemical properties of cells with Li(x)CoO2 or TiS2 as the cathode was investigated. The polymer electrolyte films were: (1) PEO, LiBF4; (2) PEO, LiBF4 with 12Cr4; (3) Li(x)CoO2, PEO, and LiBF4; and (4) Li(x)CoO2, PEO, LiBF4, and 12Cr4. It was found that, although 12Cr4 improved the cell performance over cells without 12Cr4 in the shallow c/d cycles (cyclic voltammetric behavior), it did not seem to prolong the active life of the cell. The cells with CoO2 as the cathode failed after a few c/d cycles, while similar cells with TiS2 did not fail even after 12 c/d cycles. The probable cause of failure in the case of CoO2 is ascribed to the instability of the CoO2 cathode.

Thermodynamic and hydrochemical controls on CH4 in a coal seam gas and overlying alluvial aquifer: new insights into CH4 origins

PubMed Central

Owen, D. Des. R.; Shouakar-Stash, O.; Morgenstern, U.; Aravena, R.

2016-01-01

Using a comprehensive data set (dissolved CH4, δ13C-CH4, δ2H-CH4, δ13C-DIC, δ37Cl, δ2H-H2O, δ18O-H2O, Na, K, Ca, Mg, HCO3, Cl, Br, SO4, NO3 and DO), in combination with a novel application of isometric log ratios, this study describes hydrochemical and thermodynamic controls on dissolved CH4 from a coal seam gas reservoir and an alluvial aquifer in the Condamine catchment, eastern Surat/north-western Clarence-Moreton basins, Australia. δ13C-CH4 data in the gas reservoir (−58‰ to −49‰) and shallow coal measures underlying the alluvium (−80‰ to −65‰) are distinct. CO2 reduction is the dominant methanogenic pathway in all aquifers, and it is controlled by SO4 concentrations and competition for reactants such as H2. At isolated, brackish sites in the shallow coal measures and alluvium, highly depleted δ2H-CH4 (<310‰) indicate acetoclastic methanogenesis where SO4 concentrations inhibit CO2 reduction. Evidence of CH4 migration from the deep gas reservoir (200–500 m) to the shallow coal measures (<200 m) or the alluvium was not observed. The study demonstrates the importance of understanding CH4 at different depth profiles within and between aquifers. Further research, including culturing studies of microbial consortia, will improve our understanding of the occurrence of CH4 within and between aquifers in these basins. PMID:27578542

Growth history of Kilauea inferred from volatile concentrations in submarine-collected basalts

NASA Astrophysics Data System (ADS)

Coombs, Michelle L.; Sisson, Thomas W.; Lipman, Peter W.

2006-03-01

Major-element and volatile (H 2O, CO 2, S) compositions of glasses from the submarine flanks of Kilauea Volcano record its growth from pre-shield into tholeiite shield-stage. Pillow lavas of mildly alkalic basalt at 2600-1900 mbsl on the upper slope of the south flank are an intermediate link between deeper alkalic volcaniclastics and the modern tholeiite shield. Lava clast glasses from the west flank of Papau Seamount are subaerial Mauna Loa-like tholeiite and mark the contact between the two volcanoes. H 2O and CO 2 in sandstone and breccia glasses from the Hilina bench, and in alkalic to tholeiitic pillow glasses above and to the east, were measured by FTIR. Volatile saturation pressures equal sampling depths (10 MPa = 1000 m water) for south flank and Puna Ridge pillow lavas, suggesting recovery near eruption depths and/or vapor re-equilibration during down-slope flow. South flank glasses are divisible into low-pressure (CO 2 < 40 ppm, H 2O < 0.5 wt.%, S < 500 ppm), moderate-pressure (CO 2 < 40 ppm, H 2O > 0.5 wt.%, S 1000-1700 ppm), and high-pressure groups (CO 2 > 40 ppm, S > ˜1000 ppm), corresponding to eruption ≥ sea level, at moderate water depths (300-1000 m) or shallower but in disequilibrium, and in deep water (> 1000 m). Saturation pressures range widely in early alkalic to strongly alkalic breccia clast and sandstone glasses, establishing that early Kīlauea's vents spanned much of Mauna Loa's submarine flank, with some vents exceeding sea level. Later south flank alkalic pillow lavas expose a sizeable submarine edifice that grew concurrent with nearby subaerial alkalic eruptions. The onset of the tholeiitic shield stage is marked by extension of eruptions eastward and into deeper water (to 5500 m) during growth of the Puna Ridge. Subaerial and shallow water eruptions from earliest Kilauea show that it is underlain shallowly by Mauna Loa, implying that Mauna Loa is larger, and Kilauea smaller, than previously recognized.

Annealing in tellurium-nitrogen co-doped ZnO films: The roles of intrinsic zinc defects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Kun, E-mail: ktang@nju.edu.cn; Gu, Ran; Gu, Shulin, E-mail: slgu@nju.edu.cn

2015-04-07

In this article, the authors have conducted an extensive investigation on the roles of intrinsic zinc defects by annealing of a batch of Te-N co-doped ZnO films. The formation and annihilation of Zn interstitial (Zn{sub i}) clusters have been found in samples with different annealing temperatures. Electrical and Raman measurements have shown that the Zn{sub i} clusters are a significant compensation source to holes, and the Te co-doping has a notable effect on suppressing the Zn{sub i} clusters. Meanwhile, shallow acceptors have been identified in photoluminescence spectra. The N{sub O}-Zn-Te complex, zinc vacancy (V{sub Zn})-N{sub O} complex, and V{sub Zn}more » clusters are thought to be the candidates as the shallow acceptors. The evolution of shallow acceptors upon annealing temperature have been also studied. The clustering of V{sub Zn} at high annealing temperature is proposed to be a possible candidate as a stable acceptor in ZnO.« less

Assessment of brine migration risks along vertical pathways due to CO2 injection

NASA Astrophysics Data System (ADS)

Kissinger, Alexander; Class, Holger

2015-04-01

Global climate change, shortage of resources and the growing usage of renewable energy sources has lead to a growing demand for the utilization of subsurface systems. Among these competing uses are Carbon Capture and Storage (CCS), geothermal energy, nuclear waste disposal, 'renewable' methane or hydrogen storage as well as the ongoing production of fossil resources like oil, gas and coal. Additionally, these technologies may also create conflicts with essential public interests such as water supply. For example, the injection of CO2 into the subsurface causes an increase in pressure reaching far beyond the actual radius of influence of the CO2 plume, potentially leading to large amounts of displaced salt water. In this work we focus on the large scale impacts of CO2 storage on brine migration but the methodology and the obtained results may also apply to other fields like waste water disposal, where large amounts of fluid are injected into the subsurface. In contrast to modeling on the reservoir scale the spatial scale required for this work is much larger in both vertical and lateral direction, as the regional hydrogeology has to be considered. Structures such as fault zones, hydrogeological windows in the Rupelian clay or salt domes are considered as potential pathways for displaced fluids into shallow systems and their influence has to be taken into account. We put the focus of our investigations on the latter type of scenario, since there is still a poor understanding of the role that salt diapirs would play in CO2 storage projects. As there is hardly any field data available on this scale, we compare different levels of model complexity in order to identify the relevant processes for brine displacement and simplify the modeling process wherever possible, for example brine injection vs. CO2 injection, simplified geometries vs. the complex formation geometry and the role of salt induced density differences on flow. Further we investigate the impact of the displaced brine due to CO2 injection and compare it to the natural fluid exchange between shallow and deep aquifers in order to asses possible damage.

Acceleration of modern acidification in the South China Sea driven by anthropogenic CO2

PubMed Central

Liu, Yi; Peng, Zicheng; Zhou, Renjun; Song, Shaohua; Liu, Weiguo; You, Chen-Feng; Lin, Yen-Po; Yu, Kefu; Wu, Chung-Che; Wei, Gangjian; Xie, Luhua; Burr, George S.; Shen, Chuan-Chou

2014-01-01

Modern acidification by the uptake of anthropogenic CO2 can profoundly affect the physiology of marine organisms and the structure of ocean ecosystems. Centennial-scale global and regional influences of anthropogenic CO2 remain largely unknown due to limited instrumental pH records. Here we present coral boron isotope-inferred pH records for two periods from the South China Sea: AD 1048–1079 and AD 1838–2001. There are no significant pH differences between the first period at the Medieval Warm Period and AD 1830–1870. However, we find anomalous and unprecedented acidification during the 20th century, pacing the observed increase in atmospheric CO2. Moreover, pH value also varies in phase with inter-decadal changes in Asian Winter Monsoon intensity. As the level of atmospheric CO2 keeps rising, the coupling global warming via weakening the winter monsoon intensity could exacerbate acidification of the South China Sea and threaten this expansive shallow water marine ecosystem. PMID:24888785

Acceleration of modern acidification in the South China Sea driven by anthropogenic CO2

NASA Astrophysics Data System (ADS)

Liu, Yi; Peng, Zicheng; Zhou, Renjun; Song, Shaohua; Liu, Weiguo; You, Chen-Feng; Lin, Yen-Po; Yu, Kefu; Wu, Chung-Che; Wei, Gangjian; Xie, Luhua; Burr, George S.; Shen, Chuan-Chou

2014-06-01

Modern acidification by the uptake of anthropogenic CO2 can profoundly affect the physiology of marine organisms and the structure of ocean ecosystems. Centennial-scale global and regional influences of anthropogenic CO2 remain largely unknown due to limited instrumental pH records. Here we present coral boron isotope-inferred pH records for two periods from the South China Sea: AD 1048-1079 and AD 1838-2001. There are no significant pH differences between the first period at the Medieval Warm Period and AD 1830-1870. However, we find anomalous and unprecedented acidification during the 20th century, pacing the observed increase in atmospheric CO2. Moreover, pH value also varies in phase with inter-decadal changes in Asian Winter Monsoon intensity. As the level of atmospheric CO2 keeps rising, the coupling global warming via weakening the winter monsoon intensity could exacerbate acidification of the South China Sea and threaten this expansive shallow water marine ecosystem.

The Value of Information: Assessing the Ability of Electrical Resistivity to Detect CO2 Leakage in a Shallow Aquifer

NASA Astrophysics Data System (ADS)

Trainor Guitton, W. J.; Yang, X.; Mansoor, K.; Ramirez, A. L.; Sun, Y.; Carroll, S.

2012-12-01

This study demonstrates a methodology for evaluating the value of electrical resistivity data to detect CO2 leakage in a shallow groundwater aquifer. This methodology adopts the value of information (VOI) metric from the field of decision analysis. We consider a stakeholder's decision of whether or not to remediate the aquifer, given that they are uncertain whether or not a CO2 leak has occurred from a deep storage source through a well-bore into the shallow aquifer and what the impact of that leak would be. Two themes of uncertainty are needed for VOI studies. The first is related to the uncertain state of the subsurface, which is directly related to the outcome of the decision. In our example, it is uncertain whether or not the shallow groundwater has been impacted by CO2 leakage. The impact may be determined by the existence of depressed pH or elevated TDS (total dissolved solids) plume. We utilize results from a previous work that investigated uncertainty quantification of spatial heterogeneity and leakage rates (Mansoor et al, 2011). Therefore, we have a comprehensive suite of 713 simulations that represent our uncertainty regarding the existence and extent of a CO2 plume. Given certain TDS and pH thresholds, the simulations are categorized into two groups: impacted (a plume exists) or not impacted (no plume) at time=50 years. The second theme is related to the information's accuracy to inform us about the existence of a plume (e.g. the state of the subsurface directly relevant to the decision). The uncertainty of the information is measured by the data likelihood and is used to determine the value of imperfect information. For this demonstration, we consider how electrical resistivity data can detect the existence of pH plumes (due to the dissolution of CO2) and TDS (due to the accompanying brine leakage). The pH and TDS output from the 713 simulations are used to determine the electrical resistivity at time = 0 and time=50 years. An empirical method is used to compare the time=0 and time=50 resistivities: the geometric log mean ratio (GLMR) of the 2 data sets is calculated (Daily et al, 2004). This requires only the forward response be calculated at the 2 different times. The GLMR is used as a sensitivity measure, representing how much the electrical resistivity would change given the conditions of the aquifer. The likelihood of electrical resistivity to detect the presence of a plume is estimated by comparing the GLMR and the category (plume or no plume) for all the 713 simulations. Electrical resistivity forward models were calculated for two acquisition configurations: surface electrodes only and surface-to-borehole. For the surface acquisition, a GLMR >0.05 exclusively identifies impacted simulations. Whereas GLMR <0.05 give a more ambiguous message: both simulations that are impacted and not have GMLR<0.05. The degree of this ambiguity changes with different definitions of the plume (i.e. pH and TDS thresholds). Surface-to-borehole forward models were performed for a borehole located 200m from the leaky well. Results show that surface-to-borehole resistivity data is more reliable at distinguishing between impacted and non-impacted simulations, and therefore the VOI is higher than for surface electrodes alone. Prepared by LLNL under Contract No. DE-AC52-07NA27344.

Physiological advantages of dwarfing in surviving extinctions in high-CO2 oceans

NASA Astrophysics Data System (ADS)

Garilli, Vittorio; Rodolfo-Metalpa, Riccardo; Scuderi, Danilo; Brusca, Lorenzo; Parrinello, Daniela; Rastrick, Samuel P. S.; Foggo, Andy; Twitchett, Richard J.; Hall-Spencer, Jason M.; Milazzo, Marco

2015-07-01

Excessive CO2 in the present-day ocean-atmosphere system is causing ocean acidification, and is likely to cause a severe biodiversity decline in the future, mirroring effects in many past mass extinctions. Fossil records demonstrate that organisms surviving such events were often smaller than those before, a phenomenon called the Lilliput effect. Here, we show that two gastropod species adapted to acidified seawater at shallow-water CO2 seeps were smaller than those found in normal pH conditions and had higher mass-specific energy consumption but significantly lower whole-animal metabolic energy demand. These physiological changes allowed the animals to maintain calcification and to partially repair shell dissolution. These observations of the long-term chronic effects of increased CO2 levels forewarn of changes we can expect in marine ecosystems as CO2 emissions continue to rise unchecked, and support the hypothesis that ocean acidification contributed to past extinction events. The ability to adapt through dwarfing can confer physiological advantages as the rate of CO2 emissions continues to increase.

Tree-ring 14C links seismic swarm to CO2 spike at Yellowstone, USA

USGS Publications Warehouse

Evans, William C.; Bergfeld, D.; McGeehin, J.P.; King, J.C.; Heasler, H.

2010-01-01

Mechanisms to explain swarms of shallow seismicity and inflation-deflation cycles at Yellowstone caldera (western United States) commonly invoke episodic escape of magma-derived brines or gases from the ductile zone, but no correlative changes in the surface efflux of magmatic constituents have ever been documented. Our analysis of individual growth rings in a tree core from the Mud Volcano thermal area within the caldera links a sharp ~25% drop in 14C to a local seismic swarm in 1978. The implied fivefold increase in CO2 emissions clearly associates swarm seismicity with upflow of magma-derived fluid and shows that pulses of magmatic CO2 can rapidly traverse the 5-kmthick brittle zone, even through Yellowstone's enormous hydrothermal reservoir. The 1978 event predates annual deformation surveys, but recognized connections between subsequent seismic swarms and changes in deformation suggest that CO2 might drive both processes. ?? 2010 Geological Society of America.

Detecting potential impacts of deep subsurface CO2 injection on shallow drinking water

NASA Astrophysics Data System (ADS)

Smyth, R. C.; Yang, C.; Romanak, K.; Mickler, P. J.; Lu, J.; Hovorka, S. D.

2012-12-01

Presented here are results from one aspect of collective research conducted at Gulf Coast Carbon Center, BEG, Jackson School at UT Austin. The biggest hurdle to public acceptance of CCS is to show that drinking water resources will not be impacted. Since late 1990s our group has been supported by US DOE NETL and private industry to research how best to detect potential impacts to shallow (0 to ~0.25 km) subsurface drinking water from deep (~1 to 3.5 km) injection of CO2. Work has and continues to include (1) field sampling and testing, (2) laboratory batch experiments, (3) geochemical modeling. The objective has been to identify the most sensitive geochemical indicators using data from research-level investigations, which can be economically applied on an industrial-scale. The worst-case scenario would be introduction of CO2 directly into drinking water from a leaking wellbore at a brownfield site. This is unlikely for a properly screened and/or maintained site, but needs to be considered. Our results show aquifer matrix (carbonate vs. clastic) to be critical to interpretation of pH and carbonate (DIC, Alkalinity, and δ13C of DIC) parameters because of the influence of water-rock reaction (buffering vs. non-buffering) on aqueous geochemistry. Field groundwater sampling sites to date are Cranfield, MS and SACROC, TX CO2-EOR oilfields. Two major aquifer types are represented, one dominated by silicate (Cranfield) and the other by carbonate (SACROC) water-rock reactions. We tested sensitivity of geochemical indicators (pH, DIC, Alkalinity, and δ13C of DIC) by modeling the effects of increasing pCO2 on aqueous geochemistry, and laboratory batch experiments, both with partial pressure of CO2 gas (pCO2) at 1x105 Pa (1 atm). Aquifer matrix and groundwater data provided constraints for the geochemical models. We used results from modeling and batch experiments to rank geochemical parameter sensitivity to increased pCO2 into weakly, mildly and strongly sensitive categories for both aquifer systems. DIC concentration is strongly sensitive to increased pCO2 for both aquifers; however, CO2 outgassing during sampling complicates direct field measurement of DIC. Interpretation of data from in-situ push-pull aquifer tests is ongoing and will be used to augment results summarized here. We are currently designing groundwater monitoring plans for two additional industrial-scale sites where we will further test the sensitivity and utility of our sampling approach.

Sedum-dominated green-roofs in a semi-arid region increase CO2 concentrations during the dry season.

PubMed

Agra, Har'el; Klein, Tamir; Vasl, Amiel; Shalom, Hadar; Kadas, Gyongyver; Blaustein, Leon

2017-04-15

Green roofs are expected to absorb and store carbon in plants and soils and thereby reduce the high CO 2 concentration levels in big cities. Sedum species, which are succulent perennials, are commonly used in extensive green roofs due to their shallow root system and ability to withstand long water deficiencies. Here we examined CO 2 fixation and emission rates for Mediterranean Sedum sediforme on green-roof experimental plots. During late winter to early spring, we monitored CO 2 concentrations inside transparent tents placed over 1m 2 plots and followed gas exchange at the leaf level using a portable gas-exchange system. We found high rates of CO 2 emission at daytime, which is when CO 2 concentration in the city is the highest. Both plot- and leaf-scale measurements showed that these CO 2 emissions were not fully compensated by the nighttime uptake. We conclude that although carbon sequestration may only be a secondary benefit of green roofs, for improving this ecosystem service, other plant species than Sedum should also be considered for use in green roofs, especially in Mediterranean and other semi-arid climates. Copyright © 2017 Elsevier B.V. All rights reserved.

Extremely Fast Numerical Integration of Ocean Surface Wave Dynamics: Building Blocks for a Higher Order Method

DTIC Science & Technology

2006-09-30

equation known as the Kadomtsev - Petviashvili (KP) equation ): (ηt + coηx +αηηx + βη )x +γηyy = 0 (4) where γ = co / 2 . The KdV equation ...using the spectral formulation of the Kadomtsev - Petviashvili equation , a standard equation for nonlinear, shallow water wave dynamics that is a... Petviashvili and nonlinear Schroedinger equations and higher order corrections have been developed as prerequisites to coding the Boussinesq and Euler

Viability and metal reduction of Shewanella oneidensis MR-1 under CO2 stress: implications for ecological effects of CO2 leakage from geologic CO2 sequestration.

PubMed

Wu, Bing; Shao, Hongbo; Wang, Zhipeng; Hu, Yandi; Tang, Yinjie J; Jun, Young-Shin

2010-12-01

To study potential ecological impacts of CO(2) leakage to shallow groundwater and soil/sediments from geologic CO(2) sequestration (GCS) sites, this work investigated the viability and metal reduction of Shewanella oneidensis MR-1 under CO(2) stress. While MR-1 could grow under high-pressure nitrogen gas (500 psi), the mix of 1% CO(2) with N(2) at total pressures of 15 or 150 psi significantly suppressed the growth of MR-1, compared to the N(2) control. When CO(2) partial pressures were over 15 psi, the growth of MR-1 stopped. The reduced bacterial viability was consistent with the pH decrease and cellular membrane damage under high pressure CO(2). After exposure to 150 psi CO(2) for 5 h, no viable cells survived, the cellular contents were released, and microscopy images confirmed significant cell structure deformation. However, after a relatively short exposure (25 min) to 150 psi CO(2), MR-1 could fully recover their growth within 24 h after the stress was removed, and the reduction of MnO(2) by MR-1 was observed right after the stress was removed. Furthermore, MR-1 survived better if the cells were aggregated rather than suspended, or if pH buffering minerals, such as calcite, were present. To predict the cell viability under different CO(2) pressures and exposure times, a two-parameter mathematical model was developed.

A compact plasma pre-ionized TEA-CO2 laser pulse clipper for material processing

NASA Astrophysics Data System (ADS)

Gasmi, Taieb

2017-08-01

An extra-laser cavity CO2-TEA laser pulse clipper using gas breakdown techniques for high spatial resolution material processing and shallow material engraving and drilling processes is presented. Complete extinction of the nitrogen tail, that extends the pulse width, is obtained at pressures from 375 up to 1500 torr for nitrogen and argon gases. Excellent energy stability and pulse repeatability were further enhanced using high voltage assisted preionized plasma gas technique. Experimental data illustrates the direct correlation between laser pulse width and depth of engraving in aluminum and alumina materials.

Experimental investigation of biofilm formation within a glass porous medium in the presence of carbon dioxide

NASA Astrophysics Data System (ADS)

Sygouni, Varvara; Manariotis, Ioannis D.; Chrysikopoulos, Constantinos V.

2013-04-01

Capturing CO2 emissions and storing them in properly selected deep geologic formations is considered a promising solution for the reduction of CO2 in the atmosphere. However, if CO2 leakage occurs from geologic storage formations due to permeability increases caused by rock-brine-supercritical CO2 geochemical reactions or reactivation of existing fractures, the impact to groundwater quality could be significant. Dissolved CO2 in groundwater can decrease the pH, which in turn can solubilize undesired heavy metals from the solid matrix with profound and severe implications to public health. Consequently, it is essential to fully understand the potential impact of CO2 to shallow groundwater systems. In this study, a series of visualization experiments in a glass-etched micromodel were performed in order to estimate the effect of CO2 on biofilm formation. All biofilms were developed using Pseudomonas (P.) Putida. Synthetic water saturated with CO2 was injected through the micromodel through an inlet port, and CO2 was measured at the outlet port. The transient growth of the biofilm was monitored by taking high-resolution digital photographs at various times, and the effect of CO2 on biofilm growth was estimated. Furthermore, transient changes of effective permeability and porosity were measured and the effect of solution chemistry (e.g. pH, ionic strength, redox potential) on the rate of biofilm growth was evaluated.

Effect of different management systems on soil CO2 emission and plant growth in a maize field

NASA Astrophysics Data System (ADS)

Dencso, Marton; Gelybó, Györgyi; Kása, Ilona; Pokovai, Klára; Potyó, Imre; Horel, Ágota; Birkás, Márta; Takács, Tünde; Tóth, Eszter

2017-04-01

In this study soil CO2 emission was examined in a long-term tillage experiment along with observations of plant morphological parameters, arbuscular mycorrhizal fungal (AMF) root colonization, soil properties and soil hydrothermal regime on loamy clay soil (Józsefmajor, Hungary) sown with maize. The tillage experiment was set up in 2002 and we focused on measurements performed in 2016. Based on soil disturbance depths, we selected three different tillage types such as ploughing (26-32 cm), shallow cultivation (12-16 cm), and no tillage (0 cm) for the present study. We examined CO2 emissions in rows compared to between rows within the same treatment in order to estimate the CO2 emission pattern in case of the different treatments. The measurements were carried out using the static chamber method in seven spatial replicates per treatment. For investigating plant morphological parameters of the maize we measured height of plants, leaf number and area, girth area of stem...etc. The CO2 data showed that the difference between ploughing and no tillage treatments was higher in the vegetation period of 2016 than during the dormant season. There were higher CO2 emissions in case of chambers inserted in rows than between rows on average, moreover there were significant differences between certain chambers installed in rows and between rows according to statistical data. This phenomenom can be explained by the enhanced root repiration in the rows. Based on plant morphology measurements we observed that plant developement was slower in no tillage treatment than in ploughing. Depending on sampling date, height of plants data showed 1.1 to 1.5 higher values, while leaf area data showed 1.2 to 2.5 times higher areas in case of ploughing compared to no tillage treatment. This can be due to the different soil conditions and textures of the treatments. The AMF root colonization data showed minor differences between ploughing and no tillage treatments, the highest colonization rates were found in case of shallow cultivation.

Inertia-gravity wave radiation from the merging of two co-rotating vortices in the f-plane shallow water system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sugimoto, Norihiko, E-mail: nori@phys-h.keio.ac.jp

Inertia-gravity wave radiation from the merging of two co-rotating vortices is investigated numerically in a rotating shallow water system in order to focus on cyclone–anticyclone asymmetry at different values of the Rossby number (Ro). A numerical study is conducted on a model using a spectral method in an unbounded domain to estimate the gravity wave flux with high accuracy. Continuous gravity wave radiation is observed in three stages of vortical flows: co-rotating of the vortices, merging of the vortices, and unsteady motion of the merged vortex. A cyclone–anticyclone asymmetry appears at all stages at smaller Ro (≤20). Gravity waves frommore » anticyclones are always larger than those from cyclones and have a local maximum at smaller Ro (∼2) compared with that for an idealized case of a co-rotating vortex pair with a constant rotation rate. The source originating in the Coriolis acceleration has a key role in cyclone–anticyclone asymmetry in gravity waves. An additional important factor is that at later stages, the merged axisymmetric anticyclone rotates faster than the elliptical cyclone due to the effect of the Rossby deformation radius, since a rotation rate higher than the inertial cutoff frequency is required to radiate gravity waves.« less

On the possibilty of clathrate hydrates on the Moon

NASA Technical Reports Server (NTRS)

Duxbury, N.; Nealson, K.; Romanovsky, V.

2000-01-01

One of the most important inferences of the Lunar Prospector mission data was the existence of subsurface water ice in the permanently shadowed craters near both lunar poles [Feldman et al., 1998]. We propose and substantiate an alternative explanation that hydrogen can exist in the shallow lunar subsurface in the form of clathrate hydrates: CH4 . 6H(2)o and/or CO2 . 6H(2)o.

Net uptake of atmospheric CO2 by coastal submerged aquatic vegetation

PubMed Central

Tokoro, Tatsuki; Hosokawa, Shinya; Miyoshi, Eiichi; Tada, Kazufumi; Watanabe, Kenta; Montani, Shigeru; Kayanne, Hajime; Kuwae, Tomohiro

2014-01-01

‘Blue Carbon’, which is carbon captured by marine living organisms, has recently been highlighted as a new option for climate change mitigation initiatives. In particular, coastal ecosystems have been recognized as significant carbon stocks because of their high burial rates and long-term sequestration of carbon. However, the direct contribution of Blue Carbon to the uptake of atmospheric CO2 through air-sea gas exchange remains unclear. We performed in situ measurements of carbon flows, including air-sea CO2 fluxes, dissolved inorganic carbon changes, net ecosystem production, and carbon burial rates in the boreal (Furen), temperate (Kurihama), and subtropical (Fukido) seagrass meadows of Japan from 2010 to 2013. In particular, the air-sea CO2 flux was measured using three methods: the bulk formula method, the floating chamber method, and the eddy covariance method. Our empirical results show that submerged autotrophic vegetation in shallow coastal waters can be functionally a sink for atmospheric CO2. This finding is contrary to the conventional perception that most near-shore ecosystems are sources of atmospheric CO2. The key factor determining whether or not coastal ecosystems directly decrease the concentration of atmospheric CO2 may be net ecosystem production. This study thus identifies a new ecosystem function of coastal vegetated systems; they are direct sinks of atmospheric CO2. PMID:24623530

Gas emissions from failed and actual eruptions from Cook Inlet Volcanoes, Alaska, 1989-2006

USGS Publications Warehouse

Werner, C.A.; Doukas, M.P.; Kelly, P.J.

2011-01-01

Cook Inlet volcanoes that experienced an eruption between 1989 and 2006 had mean gas emission rates that were roughly an order of magnitude higher than at volcanoes where unrest stalled. For the six events studied, mean emission rates for eruptions were ~13,000 t/d CO2 and 5200 t/d SO2, but only ~1200 t/d CO2 and 500 t/d SO2 for non-eruptive events (‘failed eruptions’). Statistical analysis suggests degassing thresholds for eruption on the order of 1500 and 1000 t/d for CO2 and SO2, respectively. Emission rates greater than 4000 and 2000 t/d for CO2 and SO2, respectively, almost exclusively resulted during eruptive events (the only exception being two measurements at Fourpeaked). While this analysis could suggest that unerupted magmas have lower pre-eruptive volatile contents, we favor the explanations that either the amount of magma feeding actual eruptions is larger than that driving failed eruptions, or that magmas from failed eruptions experience less decompression such that the majority of H2O remains dissolved and thus insufficient permeability is produced to release the trapped volatile phase (or both). In the majority of unrest and eruption sequences, increases in CO2 emission relative to SO2 emission were observed early in the sequence. With time, all events converged to a common molar value of C/S between 0.5 and 2. These geochemical trends argue for roughly similar decompression histories until shallow levels are reached beneath the edifice (i.e., from 20–35 to ~4–6 km) and perhaps roughly similar initial volatile contents in all cases. Early elevated CO2 levels that we find at these high-latitude, andesitic arc volcanoes have also been observed at mid-latitude, relatively snow-free, basaltic volcanoes such as Stromboli and Etna. Typically such patterns are attributed to injection and decompression of deep (CO2-rich) magma into a shallower chamber and open system degassing prior to eruption. Here we argue that the C/S trends probably represent tapping of vapor-saturated regions with high C/S, and then gradual degassing of remaining dissolved volatiles as the magma progresses toward the surface. At these volcanoes, however, C/S is often accentuated due to early preferential scrubbing of sulfur gases. The range of equilibrium degassing is consistent with the bulk degassing of a magma with initial CO2 and S of 0.6 and 0.2 wt.%, respectively, similar to what has been suggested for primitive Redoubt magmas.

Refining the Magnitude of the Shallow Slip Deficit

NASA Astrophysics Data System (ADS)

Xu, X.; Tong, X.; Sandwell, D. T.; Milliner, C. W. D.

2014-12-01

Geodetic inversions for slip versus depth for several major (Mw > 7) strike-slip earthquakes (e.g. 1992 Landers, 1999 Hector Mine, 2010 El_Mayor-Cucapah) show a 10% to 40% reduction in slip near surface (depth < 2 km) compared to the slip at deeper depths (5 to 8 km). This has been called the shallow slip deficit (SSD). The large magnitude of this deficit has been an enigma since it cannot be explained by shallow creep during the interseismic period or by triggered slip from nearby earthquakes. One potential explanation for the SSD is that the previous geodetic inversions used incomplete data that do not go close to fault so the shallow portions of the slip models were poorly resolved and generally underestimated. In this study we improve the geodetic inversion, especially at shallow depth by: 1) refining the InSAR processing with non-boxcar phase filtering, model-dependent range corrections, more complete phase unwrapping by SNAPHU using a correlation mask and allowing a phase discontinuity along the rupture; 2) including near-fault offset data from optical imagery and SAR azimuth offsets; 3) using more detailed fault geometry; 4) and using additional campaign GPS data. With these improved observations, the slip inversion has significantly increased resolution at shallow depth. For the Landers rupture the SSD is reduced from 45% to 16%. Similarly for the Hector Mine rupture the SSD is reduced from 15% to 5%. We are assembling all the relevant co-seismic data for the El Major-Cucapah earthquake and will report the inversion result with its SSD at the meeting.

Carbon dioxide emissions from vegetation-kill zones around the resurgent dome of Long Valley caldera, eastern California, USA

NASA Astrophysics Data System (ADS)

Bergfeld, Deborah; Evans, William C.; Howle, James F.; Farrar, Christopher D.

2006-04-01

A survey of diffuse CO 2 efflux, soil temperature and soil-gas chemistry over areas of localized vegetation-kill on and around the resurgent dome of Long Valley caldera California was performed to evaluate the premise that gaseous and thermal anomalies are related to renewed intrusion of magma. Some kill sites are long-lived features and others have developed in the past few years. Total anomalous CO 2 emissions from the thirteen areas average around 8.7 t per day; but the majority of the emissions come from four sites west of the Casa Diablo geothermal power plant. Geochemical analyses of the soil-gases from locations west and east of the plant revealed the presence of isobutane related to plant operations. The δ13C values of diffuse CO 2 range from - 5.7‰ to - 3.4‰, similar to values previously reported for CO 2 from hot springs and thermal wells around Long Valley. At many of the vegetation-kill sites soil temperatures reach boiling at depths ≤ 20 cm. Soil temperature/depth profiles at two of the high-emissions areas indicate that the conductive thermal gradient in the center of the areas is around 320 °C m - 1 . We estimate total heat loss from the two areas to be about 6.1 and 2.3 MW. Given current thinking on the rate of hydrothermal fluid flow across the caldera and using the CO 2 concentration in the thermal fluids, the heat and CO 2 loss from the kill areas is easily provided by the shallow hydrothermal system, which is sourced to the west of the resurgent dome. We find no evidence that the development of new areas of vegetation kill across the resurgent dome are related to new input of magma or magmatic fluids from beneath the resurgent dome. Our findings indicate that the areas have developed as a response to changes in the shallow hydrologic system. Some of the changes are likely related to fluid production at the power plant, but at distal sites the changes are more likely related to seismicity and uplift of the dome.

Development and Deployment of a Compact Eye-Safe Scanning Differential absorption Lidar (DIAL) for Spatial Mapping of Carbon Dioxide for Monitoring/Verification/Accounting at Geologic Sequestration Sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Repasky, Kevin

2014-03-31

A scanning differential absorption lidar (DIAL) instrument for monitoring carbon dioxide has been developed. The laser transmitter uses two tunable discrete mode laser diodes (DMLD) operating in the continuous wave (cw) mode with one locked to the online absorption wavelength and the other operating at the offline wavelength. Two in-line fiber optic switches are used to switch between online and offline operation. After the fiber optic switch, an acousto- optic modulator (AOM) is used to generate a pulse train used to injection seed an erbium doped fiber amplifier (EDFA) to produce eye-safe laser pulses with maximum pulse energies of 66more » {micro}J, a pulse repetition frequency of 15 kHz, and an operating wavelength of 1.571 {micro}m. The DIAL receiver uses a 28 cm diameter Schmidt-Cassegrain telescope to collect that backscattered light, which is then monitored using a photo-multiplier tube (PMT) module operating in the photon counting mode. The DIAL instrument has been operated from a laboratory environment on the campus of Montana State University, at the Zero Emission Research Technology (ZERT) field site located in the agricultural research area on the western end of the Montana State University campus, and at the Big Sky Carbon Sequestration Partnership site located in north-central Montana. DIAL data has been collected and profiles have been validated using a co-located Licor LI-820 Gas Analyzer point sensor.« less

Geochemical Sources of Energy for Chemolithoautotrophic Metabolisms in Global Hydrothermal Ecosystems

NASA Astrophysics Data System (ADS)

Lu, G. S.; Amend, J.; LaRowe, D.

2017-12-01

Chemolithoautotrophic microorganisms are important primary producers in hydrothermal environments. The potential catabolic energy sources that thermophilic chemolithoautotrophs can take advantage of can be quantified by combining analytical geochemical data and thermodynamic calculations. This approach explicitly considers how microbial communities are shaped by environmental conditions such as temperature, pressure, pH and the concentrations of electron donors and acceptors. In this study, we have calculated the Gibbs free energy available from 730 redox reactions in 30 terrestrial, shallow-sea, and deep-sea hydrothermal venting systems around the world (326 geochemical data sets) to better determine the relationship between microbial physiology and environment. The reactions with NO2-, O2, MnO2 and NO3- as terminal electron acceptors yield 5-20 kJ/mol e- more energy in terrestrial and shallow-sea hydrothermal systems than in deep-sea hydrothermal settings. However, reactions in which As5+, S0, FeS2 and SO42- as electron acceptors are more favorable by 5-30 kJ/mol e- in deep-sea hydrothermal systems than in the other two types of hydrothermal systems. The most exergonic reactions were predominantly NO2-, O2, MnO2 and NO3- reduction or Fe2+, pyrite, CO and CH4 oxidation. In contrast, reduction of N2, CO, and CO2 or oxidation of N2, Mn2+, and NO2-, though still often exergonic, yielded significantly less energy. Our results provide a comprehensive view of the distribution of energy supplies from redox reactions in high-temperature ecosystems on a global scale. Furthermore, the bioenergetic modeling carried out in this study can be used to test physiological predictions made from metagenomic and proteomic data sets, explore in situ biogeochemical interactions, predict possible but yet-to-be observed metabolisms and guide cultivation efforts.

Comparative Study of Effects of CO 2 Concentration and pH on Microbial Communities from a Saline Aquifer, a Depleted Oil Reservoir, and a Freshwater Aquifer

DOE PAGES

Gulliver, Djuna M.; Lowry, Gregory V.; Gregory, Kelvin B.

2016-08-09

Injected CO 2 from geologic carbon storage is expected to impact the microbial communities of proposed storage sites, such as depleted oil reservoirs and deep saline aquifers, as well as overlying freshwater aquifers at risk of receiving leaking CO 2. Microbial community change in these subsurface sites may affect injectivity of CO 2, permanence of stored CO 2, and shallow subsurface water quality. The effect of CO 2 concentration on the microbial communities in fluid collected from a depleted oil reservoir and a freshwater aquifer was examined at subsurface pressures and temperatures. The community was exposed to 0%, 1%, 10%,more » and 100% pCO 2 for 56 days. Bacterial community structure was analyzed through 16S rRNA gene clone libraries, and total bacterial abundance was estimated through quantitative polymerase chain reaction. Changes in the microbial community observed in the depleted oil reservoir samples and freshwater samples were compared to previous results from CO 2-exposed deep saline aquifer fluids. Overall, results suggest that CO 2 exposure to microbial communities will result in pH-dependent population change, and the CO 2-selected microbial communities will vary among sites. In conclusion, this is the first study to compare the response of multiple subsurface microbial communities at conditions expected during geologic carbon storage, increasing the understanding of environmental drivers for microbial community changes in CO 2-exposed environments.« less

Comparative Study of Effects of CO 2 Concentration and pH on Microbial Communities from a Saline Aquifer, a Depleted Oil Reservoir, and a Freshwater Aquifer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gulliver, Djuna M.; Lowry, Gregory V.; Gregory, Kelvin B.

Injected CO 2 from geologic carbon storage is expected to impact the microbial communities of proposed storage sites, such as depleted oil reservoirs and deep saline aquifers, as well as overlying freshwater aquifers at risk of receiving leaking CO 2. Microbial community change in these subsurface sites may affect injectivity of CO 2, permanence of stored CO 2, and shallow subsurface water quality. The effect of CO 2 concentration on the microbial communities in fluid collected from a depleted oil reservoir and a freshwater aquifer was examined at subsurface pressures and temperatures. The community was exposed to 0%, 1%, 10%,more » and 100% pCO 2 for 56 days. Bacterial community structure was analyzed through 16S rRNA gene clone libraries, and total bacterial abundance was estimated through quantitative polymerase chain reaction. Changes in the microbial community observed in the depleted oil reservoir samples and freshwater samples were compared to previous results from CO 2-exposed deep saline aquifer fluids. Overall, results suggest that CO 2 exposure to microbial communities will result in pH-dependent population change, and the CO 2-selected microbial communities will vary among sites. In conclusion, this is the first study to compare the response of multiple subsurface microbial communities at conditions expected during geologic carbon storage, increasing the understanding of environmental drivers for microbial community changes in CO 2-exposed environments.« less

Shallow soil CO2 flow along the San Andreas and Calaveras Faults, California

USGS Publications Warehouse

Lewicki, J.L.; Evans, William C.; Hilley, G.E.; Sorey, M.L.; Rogie, J.D.; Brantley, S.L.

2003-01-01

We evaluate a comprehensive soil CO2 survey along the San Andreas fault (SAF) in Parkfield, and the Calaveras fault (CF) in Hollister, California, in the context of spatial and temporal variability, origin, and transport of CO2 in fractured terrain. CO2 efflux was measured within grids with portable instrumentation and continously with meteorological parameters at a fixed station, in both faulted and unfaulted areas. Spatial and temporal variability of surface CO2 effluxes was observed to be higher at faulted SAF and CF sites, relative to comparable background areas. However, ??13C (-23.3 to - 16.4???) and ??14C (75.5 to 94.4???) values of soil CO2 in both faulted and unfaulted areas are indicative of biogenic CO2, even though CO2 effluxes in faulted areas reached values as high as 428 g m-2 d-1. Profiles of soil CO2 concentration as a function of depth were measured at multiple sites within SAF and CF grids and repeatedly at two locations at the SAF grid. Many of these profiles suggest a surprisingly high component of advective CO2 flow. Spectral and correlation analysis of SAF CO2 efflux and meteorological parameter time series indicates that effects of wind speed variations on atmospheric air flow though fractures modulate surface efflux of biogenic CO2. The resulting areal patterns in CO2 effluxes could be erroneously attributed to a deep gas source in the absence of isotopic data, a problem that must be addressed in fault zone soil gas studies.

Magma surge from the mantle: the Father's Day Eruption, Kīlauea Volcano, Hawai'i

NASA Astrophysics Data System (ADS)

Salem, L. C.; Edmonds, M.; Maclennan, J.; Houghton, B. F.; Poland, M. P.

2015-12-01

The geometry of the shallow plumbing system of Kīlauea Volcano, Hawai'i, is constrained by both geophysical and petrologic studies, yet the loci of lower crustal magma storage and timescales of magma ascent are almost entirely unknown. The petrography and texture of erupted magmas are largely overprinted by processes in the shallow reservoir and conduit. Direct petrological evidence for lower crustal storage and transport is enigmatic but exists in the form of fine-scale crystal zoning in the cores of olivine phenocrysts, in the geochemical heterogeneity of melt inclusions and in fluid inclusion density. The 2007 Father's Day intrusion and eruption occurred at the culmination of a surge in magma supply to the summit reservoir and during a period of heightened CO2 outgassing flux. The erupted lavas provide an opportunity to analyze atypically primitive melts, with > 8.5 wt% MgO in the whole rock, which have undergone relatively little shallow crustal processing. We characterise melt inclusions and their host olivine crystals through a detailed study of olivine morphology, diffusion modelling, and melt and fluid inclusion geochemistry. We show that the melt inclusions preserve primitive geochemical heterogeneity, which we use to reconstruct fractionation, mixing and degassing processes through the crust. We infer timescales and pressures of magma ascent, storage, and CO2 degassing through the crustal plumbing system. These observations are interpreted in the context of the exceptionally detailed set of volcano monitoring data at Kīlauea Volcano.

Volatile emissions and gas geochemistry of Hot Spring Basin, Yellowstone National Park, USA

USGS Publications Warehouse

Werner, C.; Hurwitz, S.; Evans, William C.; Lowenstern, J. B.; Bergfeld, D.; Heasler, H.; Jaworowski, C.; Hunt, A.

2008-01-01

We characterize and quantify volatile emissions at Hot Spring Basin (HSB), a large acid-sulfate region that lies just outside the northeastern edge of the 640??ka Yellowstone Caldera. Relative to other thermal areas in Yellowstone, HSB gases are rich in He and H2, and mildly enriched in CH4 and H2S. Gas compositions are consistent with boiling directly off a deep geothermal liquid at depth as it migrates toward the surface. This fluid, and the gases evolved from it, carries geochemical signatures of magmatic volatiles and water-rock reactions with multiple crustal sources, including limestones or quartz-rich sediments with low K/U (or 40*Ar/4*He). Variations in gas chemistry across the region reflect reservoir heterogeneity and variable degrees of boiling. Gas-geothermometer temperatures approach 300????C and suggest that the reservoir feeding HSB is one of the hottest at Yellowstone. Diffuse CO2 flux in the western basin of HSB, as measured by accumulation-chamber methods, is similar in magnitude to other acid-sulfate areas of Yellowstone and is well correlated to shallow soil temperatures. The extrapolation of diffuse CO2 fluxes across all the thermal/altered area suggests that 410 ?? 140??t d- 1 CO2 are emitted at HSB (vent emissions not included). Diffuse fluxes of H2S were measured in Yellowstone for the first time and likely exceed 2.4??t d- 1 at HSB. Comparing estimates of the total estimated diffuse H2S emission to the amount of sulfur as SO42- in streams indicates ~ 50% of the original H2S in the gas emission is lost into shallow groundwater, precipitated as native sulfur, or vented through fumaroles. We estimate the heat output of HSB as ~ 140-370??MW using CO2 as a tracer for steam condensate, but not including the contribution from fumaroles and hydrothermal vents. Overall, the diffuse heat and volatile fluxes of HSB are as great as some active volcanoes, but they are a small fraction (1-3% for CO2, 2-8% for heat) of that estimated for the entire Yellowstone system.

Geochemistry and volatile content of magmas feeding explosive eruptions at Telica volcano (Nicaragua)

NASA Astrophysics Data System (ADS)

Robidoux, P.; Rotolo, S. G.; Aiuppa, A.; Lanzo, G.; Hauri, E. H.

2017-07-01

Telica volcano, in north-west Nicaragua, is a young stratovolcano of intermediate magma composition producing frequent Vulcanian to phreatic explosive eruptions. The Telica stratigraphic record also includes examples of (pre)historic sub-Plinian activity. To refine our knowledge of this very active volcano, we analyzed major element composition and volatile content of melt inclusions from some stratigraphically significant Telica tephra deposits. These include: (1) the Scoria Telica Superior (STS) deposit (2000 to 200 years Before Present; Volcanic Explosive Index, VEI, of 2-3) and (2) pyroclasts from the post-1970s eruptive cycle (1982; 2011). Based on measurements with nanoscale secondary ion mass spectrometry, olivine-hosted (forsterite [Fo] > 80) glass inclusions fall into 2 distinct clusters: a group of H2O-rich (1.8-5.2 wt%) inclusions, similar to those of nearby Cerro Negro volcano, and a second group of CO2-rich (360-1700 μg/g CO2) inclusions (Nejapa, Granada). Model calculations show that CO2 dominates the equilibrium magmatic vapor phase in the majority of the primitive inclusions (XCO2 > 0.62-0.95). CO2, sulfur (generally < 2000 μg/g) and H2O are lost to the vapor phase during deep decompression (P > 400 MPa) and early crystallization of magmas. Chlorine exhibits a wide concentration range (400-2300 μg/g) in primitive olivine-entrapped melts (likely suggesting variable source heterogeneity) and is typically enriched in the most differentiated melts (1000-3000 μg/g). Primitive, volatile-rich olivine-hosted melt inclusions (entrapment pressures, 5-15 km depth) are exclusively found in the largest-scale Telica eruptions (exemplified by STS in our study). These eruptions are thus tentatively explained as due to injection of deep CO2-rich mafic magma into the shallow crustal plumbing system. More recent (post-1970), milder (VEI 1-2) eruptions, instead, do only exhibit evidence for low-pressure (P < 50-60 MPa), volatile-poor (H2O < 0.3-1.7 wt%; CO2 < 23-308 μg/g) magmatic conditions. These are manifested as andesitic magmas, recording multiple magma mixing events, in pyroxene inclusions. We propose that post-1970s eruptions are possibly related to the high viscosity of resident magma in shallow plumbing system (< 2.4 km), due to crystallization and degassing.

Multi-property modeling of ocean basin carbon fluxes

NASA Technical Reports Server (NTRS)

Volk, Tyler

1988-01-01

The objectives of this project were to elucidate the causal mechanisms in some of the most important features of the global ocean/atomsphere carbon system. These included the interaction of physical and biological processes in the seasonal cycle of surface water pCo2, and links between productivity, surface chlorophyll, and the carbon cycle that would aid global modeling efforts. In addition, several other areas of critical scientific interest involving links between the marine biosphere and the global carbon cycle were successfully pursued; specifically, a possible relation between phytoplankton emitted DMS and climate, and a relation between the location of calcium carbonate burial in the ocean and metamorphic source fluxes of CO2 to the atmosphere. Six published papers covering the following topics are summarized: (1) Mass extinctions, atmospheric sulphur and climatic warming at the K/T boundary; (2) Sensitivity of climate and atmospheric CO2 to deep-ocean and shallow-ocean carbonate burial; (3) Controls on CO2 sources and sinks in the earthscale surface ocean; (4) pre-anthropogenic, earthscale patterns of delta pCO2 between ocean and atmosphere; (5) Effect on atmospheric CO2 from seasonal variations in the high latitude ocean; and (6) Limitations or relating ocean surface chlorophyll to productivity.

Seismic rupture and ground accelerations induced by CO 2 injection in the shallow crust

DOE PAGES

Cappa, Frédéric; Rutqvist, Jonny

2012-09-01

We present that because of the critically stressed nature of the upper crust, the injection of large volumes of carbon dioxide (CO 2) into shallow geological reservoirs can trigger seismicity and induce ground deformations when the injection increases the fluid pressure in the vicinity of potentially seismic faults. The increased fluid pressure reduces the strength against fault slip, allowing the stored elastic energy to be released in seismic events that can produce felt ground accelerations. Here, we seek to explore the likelihood ground motions induced by a CO 2 injection using hydromechanical modelling with multiphase fluid flow and dynamic rupture,more » including fault-frictional weakening. We extend the previous work of Cappa and Rutqvist, in which activation of a normal fault at critical stress may be possible for fast rupture nucleating by localized increase in fluid pressure and large decrease in fault friction. In this paper, we include seismic wave propagation generated by the rupture. For our assumed system and injection rate, simulations show that after a few days of injection, a dynamic fault rupture of few centimetres nucleates at the base of the CO 2 reservoir and grows bilaterally, both toward the top of the reservoir and outside. The rupture is asymmetric and affects a larger zone below the reservoir where the rupture is self-propagating (without any further pressure increase) as a result of fault-strength weakening. The acceleration and deceleration of the rupture generate waves and result in ground accelerations (~0.1–0.6 g) consistent with observed ground motion records. Finally, the maximum ground acceleration is obtained near the fault, and horizontal accelerations are generally markedly higher than vertical accelerations.« less

Multi-Spectral imaging of vegetation for detecting CO2 leaking from underground

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rouse, J.H.; Shaw, J.A.; Lawrence, R.L.

2010-06-01

Practical geologic CO{sub 2} sequestration will require long-term monitoring for detection of possible leakage back into the atmosphere. One potential monitoring method is multi-spectral imaging of vegetation reflectance to detect leakage through CO{sub 2}-induced plant stress. A multi-spectral imaging system was used to simultaneously record green, red, and near-infrared (NIR) images with a real-time reflectance calibration from a 3-m tall platform, viewing vegetation near shallow subsurface CO{sub 2} releases during summers 2007 and 2008 at the Zero Emissions Research and Technology field site in Bozeman, Montana. Regression analysis of the band reflectances and the Normalized Difference Vegetation Index with timemore » shows significant correlation with distance from the CO{sub 2} well, indicating the viability of this method to monitor for CO{sub 2} leakage. The 2007 data show rapid plant vigor degradation at high CO{sub 2} levels next to the well and slight nourishment at lower, but above-background CO{sub 2} concentrations. Results from the second year also show that the stress response of vegetation is strongly linked to the CO{sub 2} sink-source relationship and vegetation density. The data also show short-term effects of rain and hail. The real-time calibrated imaging system successfully obtained data in an autonomous mode during all sky and daytime illumination conditions.« less

Seasonal patterns in carbon dioxide in 15 mid-continent (USA) reservoirs

USGS Publications Warehouse

Jones, John R.; Obrecht, Daniel V.; Graham, Jennifer L.; Balmer, Michelle B.; Filstrup, Christopher T.; Downing, John A.

2016-01-01

Evidence suggests that lakes are important sites for atmospheric CO2 exchange and so play a substantial role in the global carbon budget. Previous research has 2 weaknesses: (1) most data have been collected only during the open-water or summer seasons, and (2) data are concentrated principally on natural lakes in northern latitudes. Here, we report on the full annual cycle of atmospheric CO2 exchanges of 15 oligotrophic to eutrophic reservoirs in the Glacial Till Plains of the United States. With one exception, these reservoirs showed an overall loss of CO2 during the year, with most values within the lower range reported for temperate lakes. There was a strong cross-system seasonal pattern: an average of 70% of total annual CO2 efflux occurred by the end of spring mixis; some 20% of annual flux was reabsorbed during summer stratification; and the remaining 50% of efflux was lost during autumnal mixing. Net annual flux was negatively correlated with depth and positively correlated with both water residence time and DOC, with the smallest annual CO2 efflux measured in shallow fertile impoundments. Strong correlations yield relationships allowing regional up-scaling of CO2 evasion. Understanding lacustrine CO2 uptake and evasion requires seasonal analyses across the full range of lake trophic states and morphometric attributes.

Simple dielectric mixing model in the monitoring of CO2 leakage from geological storage aquifer

NASA Astrophysics Data System (ADS)

Abidoye, L. K.; Bello, A. A.

2017-03-01

The principle of the dielectric mixing for multiphase systems in porous media has been employed to investigate CO2-water-porous media system and monitor the leakage of CO2, in analogy to scenarios that can be encountered in geological carbon sequestration. A dielectric mixing model was used to relate the relative permittivity for different subsurface materials connected with the geological carbon sequestration. The model was used to assess CO2 leakage and its upward migration, under the influences of the depth-dependent characteristics of the subsurface media as well as the fault-connected aquifers. The results showed that for the upward migration of CO2 in the subsurface, the change in the bulk relative permittivity (εb) of the CO2-water-porous media system clearly depicts the leakage and movement of CO2, especially at depth shallower than 800 m. At higher depth, with higher pressure and temperature, the relative permittivity of CO2 increases with pressure, while that of water decreases with temperature. These characteristics of water and supercritical CO2, combine to limit the change in the εb, at higher depth. Furthermore, it was noted that if the pore water was not displaced by the migrating CO2, the presence of CO2 in the system increases the εb. But, with the displacement of pore water by the migrating CO2, it was shown how the εb profile decreases with time. Owing to its relative simplicity, composite dielectric behaviour of multiphase materials can be effectively deployed for monitoring and enhancement of control of CO2 movement in the geological carbon sequestration.

Multi-Sensor Mapping of Diffuse Degassing of C-O-H Compounds in Terrestrial Hydrothermal Systems

NASA Astrophysics Data System (ADS)

Schwandner, F. M.; Shock, E. L.

2004-12-01

In-situ single-sensor detection and mapping of diffuse degassing phenomena in hydrothermal and volcanic areas can be used to elucidate subsurface tectonic structures, assess emission rates, and to monitor emission variability (Williams 1985; Chiodini et al. 1996, Werner et al., 2003). More than one technique has been deployed to measure several gas species simultaneously (e.g., Crenshaw et al. 1982), and correlations of one gas species (usually CO2) with physical parameters like heat flux (Brombach et al., 2001), or with one other gas species (Rn, He) have been demonstrated (Barberi & Carapezza 1994; Williams-Jones et al., 2000). Recently, correlations of multiple gas species with one another were reported (Schwandner et al., 2004), leading to the possibility of quantitative mapping of subsurface hydrothermal chemical processes by simultaneous measurement of reaction partners and products that continuously and diffusely degas. In the present study, we joined a fully-quantitative multi-sensor instrument (Draeger Multiwarn II) to a modified accumulation-chamber sensing method (Chiodini et al., 1996) and measured diffuse degassing of CH4, H2, CO2, CO, and H2S. In this approach, each batch of gas that is recirculated through the detector is simultaneously analyzed by all sensors. To test this approach we chose two magmatically influenced, hydrothermally active areas at Yellowstone National Park (USA): Sylvan Springs and the Greater Obsidian Pool Area. The area near Obsidian Pool was previously studied during a diffuse CO2 degassing campaign (Werner & Brantley, 2004). Preliminary results show that elevated reduced gas emissions appear to be most prominent near hydrothermal pools, whereas CO2-dominated degassing anomalies highlight subsurface tectonic structures. This multimodal distribution allows us to distinguish deep degassing sources (CO2 anomalies) from shallow localized hydrothermal processes (reduced gas anomalies). The results permit us to positively identify and partially map a previously-inferred active lineament in the Obsidian Pool area. In addition, reduced gas data are yielding areal ratio distributions of CO/CO2, H2/CH4, and CO/CH4, that may be indicative of reactions such as the catalytic hydrogenation of CO2 (Sabatier-Process) and of CO (Fischer-Tropsch-Process) within the shallow hydrothermal system. Barberi & Carapezza (1994). Bull. Volcanol. 56(5): 335-342. Brombach, et al. (2001). Geophys. Res. Lett. 28(1): 69-72. Crenshaw et al. (1982). Nature 300: 345-346. Chiodini et al. (1996). Bull. Volcanol. 58(1): 41-50. Schwandner et al. (2004). JGR D 109: D04301, doi:10.1029/2003JD003890. Werner & Brantley (2004) JGR B 105: 10,831-10,846. Werner et al. (2003). Earth Planet. Sci. Lett. 210: 561-577. Williams (1985). Science 229(4713): 551-553. Williams-Jones et al. (2000). Bull. Volcanol. 62: 130-142.

Turmoil at Turrialba Volcano (Costa Rica): Degassing and eruptive processes inferred from high-frequency gas monitoring.

PubMed

de Moor, J Maarten; Aiuppa, A; Avard, G; Wehrmann, H; Dunbar, N; Muller, C; Tamburello, G; Giudice, G; Liuzzo, M; Moretti, R; Conde, V; Galle, B

2016-08-01

Eruptive activity at Turrialba Volcano (Costa Rica) has escalated significantly since 2014, causing airport and school closures in the capital city of San José. Whether or not new magma is involved in the current unrest seems probable but remains a matter of debate as ash deposits are dominated by hydrothermal material. Here we use high-frequency gas monitoring to track the behavior of the volcano between 2014 and 2015 and to decipher magmatic versus hydrothermal contributions to the eruptions. Pulses of deeply derived CO 2 -rich gas (CO 2 /S total  > 4.5) precede explosive activity, providing a clear precursor to eruptive periods that occurs up to 2 weeks before eruptions, which are accompanied by shallowly derived sulfur-rich magmatic gas emissions. Degassing modeling suggests that the deep magmatic reservoir is ~8-10 km deep, whereas the shallow magmatic gas source is at ~3-5 km. Two cycles of degassing and eruption are observed, each attributed to pulses of magma ascending through the deep reservoir to shallow crustal levels. The magmatic degassing signals were overprinted by a fluid contribution from the shallow hydrothermal system, modifying the gas compositions, contributing volatiles to the emissions, and reflecting complex processes of scrubbing, displacement, and volatilization. H 2 S/SO 2 varies over 2 orders of magnitude through the monitoring period and demonstrates that the first eruptive episode involved hydrothermal gases, whereas the second did not. Massive degassing (>3000 T/d SO 2 and H 2 S/SO 2  > 1) followed, suggesting boiling off of the hydrothermal system. The gas emissions show a remarkable shift to purely magmatic composition (H 2 S/SO 2  < 0.05) during the second eruptive period, reflecting the depletion of the hydrothermal system or the establishment of high-temperature conduits bypassing remnant hydrothermal reservoirs, and the transition from phreatic to phreatomagmatic eruptive activity.

Turmoil at Turrialba Volcano (Costa Rica): Degassing and eruptive processes inferred from high‐frequency gas monitoring

PubMed Central

Aiuppa, A.; Avard, G.; Wehrmann, H.; Dunbar, N.; Muller, C.; Tamburello, G.; Giudice, G.; Liuzzo, M.; Moretti, R.; Conde, V.; Galle, B.

2016-01-01

Abstract Eruptive activity at Turrialba Volcano (Costa Rica) has escalated significantly since 2014, causing airport and school closures in the capital city of San José. Whether or not new magma is involved in the current unrest seems probable but remains a matter of debate as ash deposits are dominated by hydrothermal material. Here we use high‐frequency gas monitoring to track the behavior of the volcano between 2014 and 2015 and to decipher magmatic versus hydrothermal contributions to the eruptions. Pulses of deeply derived CO2‐rich gas (CO2/Stotal > 4.5) precede explosive activity, providing a clear precursor to eruptive periods that occurs up to 2 weeks before eruptions, which are accompanied by shallowly derived sulfur‐rich magmatic gas emissions. Degassing modeling suggests that the deep magmatic reservoir is ~8–10 km deep, whereas the shallow magmatic gas source is at ~3–5 km. Two cycles of degassing and eruption are observed, each attributed to pulses of magma ascending through the deep reservoir to shallow crustal levels. The magmatic degassing signals were overprinted by a fluid contribution from the shallow hydrothermal system, modifying the gas compositions, contributing volatiles to the emissions, and reflecting complex processes of scrubbing, displacement, and volatilization. H2S/SO2 varies over 2 orders of magnitude through the monitoring period and demonstrates that the first eruptive episode involved hydrothermal gases, whereas the second did not. Massive degassing (>3000 T/d SO2 and H2S/SO2 > 1) followed, suggesting boiling off of the hydrothermal system. The gas emissions show a remarkable shift to purely magmatic composition (H2S/SO2 < 0.05) during the second eruptive period, reflecting the depletion of the hydrothermal system or the establishment of high‐temperature conduits bypassing remnant hydrothermal reservoirs, and the transition from phreatic to phreatomagmatic eruptive activity. PMID:27774371

Turmoil at Turrialba Volcano (Costa Rica): Degassing and eruptive processes inferred from high-frequency gas monitoring

NASA Astrophysics Data System (ADS)

de Moor, J. Maarten; Aiuppa, A.; Avard, G.; Wehrmann, H.; Dunbar, N.; Muller, C.; Tamburello, G.; Giudice, G.; Liuzzo, M.; Moretti, R.; Conde, V.; Galle, B.

2016-08-01

Eruptive activity at Turrialba Volcano (Costa Rica) has escalated significantly since 2014, causing airport and school closures in the capital city of San José. Whether or not new magma is involved in the current unrest seems probable but remains a matter of debate as ash deposits are dominated by hydrothermal material. Here we use high-frequency gas monitoring to track the behavior of the volcano between 2014 and 2015 and to decipher magmatic versus hydrothermal contributions to the eruptions. Pulses of deeply derived CO2-rich gas (CO2/Stotal > 4.5) precede explosive activity, providing a clear precursor to eruptive periods that occurs up to 2 weeks before eruptions, which are accompanied by shallowly derived sulfur-rich magmatic gas emissions. Degassing modeling suggests that the deep magmatic reservoir is 8-10 km deep, whereas the shallow magmatic gas source is at 3-5 km. Two cycles of degassing and eruption are observed, each attributed to pulses of magma ascending through the deep reservoir to shallow crustal levels. The magmatic degassing signals were overprinted by a fluid contribution from the shallow hydrothermal system, modifying the gas compositions, contributing volatiles to the emissions, and reflecting complex processes of scrubbing, displacement, and volatilization. H2S/SO2 varies over 2 orders of magnitude through the monitoring period and demonstrates that the first eruptive episode involved hydrothermal gases, whereas the second did not. Massive degassing (>3000 T/d SO2 and H2S/SO2 > 1) followed, suggesting boiling off of the hydrothermal system. The gas emissions show a remarkable shift to purely magmatic composition (H2S/SO2 < 0.05) during the second eruptive period, reflecting the depletion of the hydrothermal system or the establishment of high-temperature conduits bypassing remnant hydrothermal reservoirs, and the transition from phreatic to phreatomagmatic eruptive activity.

Syn-eruptive CO2 Degassing of Submarine Lavas Flows: Constraints on Eruption Dynamics

NASA Astrophysics Data System (ADS)

Soule, S. A.; Boulahanis, B.; Fundis, A.; Clague, D. A.; Chadwick, B.

2013-12-01

At fast- and intermediate-spreading rate mid-ocean ridges, quenched lava samples are commonly supersaturated in CO2 with concentrations similar to the pressure/depth of shallow crustal melt lenses. This supersaturation is attributed to rapid ascent and decompression rates that exceed the kinetic rates of bubble nucleation and growth. During emplacement, CO2 supersaturated lavas experience nearly isothermal and isobaric conditions over a period of hours. A recent study has demonstrated systematic decreases in CO2 with increasing transport distance (i.e. time) along a single flow pathway within the 2005-06 eruption at the East Pacific Rise (~2500 m.b.s.l.). Based on analysis of vesicle population characteristics and complementary noble gas measurements, it is proposed that diffusion of CO2 into bubbles can be used as a basis to model the gas loss from the melt and thus place constraints on the dynamics of the eruption. We suggest that submarine lava flows represent a natural experiment in degassing that isolates conditions of low to moderate supersaturation and highlights timescales of diffusion and vesiculation processes that are relevant to shallow crustal and conduit processes in subaerial basaltic volcanic systems. Here we report a new suite of volatile concentration analyses and vesicle size distributions from the 2011 eruption of Axial Volcano along the Juan de Fuca Ridge (~1500 m.b.s.l.). The lava flows from this eruption are mapped by differencing of repeat high-resolution bathymetric surveys, so that the geologic context of the samples is known. In addition, in-situ instrument records record the onset of the eruption and place constraints on timing that can be used to verify estimates of eruption dynamics derived from degassing. This sample suite provides a comprehensive view of the variability in volatile concentrations within a submarine eruption and new constraints for evaluating models of degassing and vesiculation. Initial results show systematic variability in CO2 supersaturation along eruptive fissures as well as with increasing distance along flows pathways providing constraints on threshold decompression rates required to nucleate and grow bubbles in a basaltic melt, timescales of degassing in natural systems, and the properties of consequent vesicle populations.

Depth-dependence and monthly variability of charophyte biomass production: consequences for the precipitation of calcium carbonate in a shallow Chara-lake.

PubMed

Pukacz, Andrzej; Pełechaty, Mariusz; Frankowski, Marcin

2016-11-01

The month-to-month variability of biomass and CaCO 3 precipitation by dense charophyte beds was studied in a shallow Chara-lake at two depths, 1 and 3 m. Charophyte dry weights (d.w.), the percentage contribution of calcium carbonate to the dry weight and the precipitation of CaCO 3 per 1 m 2 were analysed from May to October 2011. Physical-chemical parameters of water were also measured for the same sample locations. The mean dry weight and calcium carbonate precipitation were significantly higher at 1 m than at 3 m. The highest measured charophyte dry weight (exceeding 2000 g m -2 ) was noted at 1 m depth in September, and the highest CaCO 3 content in the d.w. (exceeding 80 % of d.w.) was observed at 3 m depth in August. The highest CaCO 3 precipitation per 1 m 2 exceeded 1695 g at 1 m depth in August. Significant differences in photosynthetically active radiation (PAR) were found between 1 and 3 m depths; there were no significant differences between depths for other water properties. At both sampling depths, there were distinct correlations between the d.w., CaCO 3 content and precipitation and water properties. In addition to PAR, the water temperature and magnesium and calcium ion concentrations were among the most significant determinants of CaCO 3 content and d.w. The results show that light availability seems to be the major factor in determining charophyte biomass in a typical, undisturbed Chara-lake. The study results are discussed in light of the role of charophyte vegetation in whole ecosystem functioning, with a particular focus on sedimentary processes and the biogeochemical cycle within the littoral zone.

Dynamics of carbon dioxide emission at Mammoth Mountain, California

USGS Publications Warehouse

Rogie, J.D.; Kerrick, Derrill M.; Sorey, M.L.; Chiodini, G.; Galloway, D.L.

2001-01-01

Mammoth Mountain, a dormant volcano in the eastern Sierra Nevada, California, has been passively degassing large quantities of cold magmatic CO2 since 1990 following a 6-month-long earthquake swarm associated with a shallow magmatic intrussion in 1989. A search for any link between gas discharge and volcanic hazard at this popular recreation area led us to initiate a detailed study of the degassing process in 1997. Our continuous monitoring results elucidate some of the physical controls that influence dynamics in flank CO2 degassing at this volcano. High coherence between variations in CO2 efflux and variations in atmospheric pressure and wind speed imply that meteorological parameters account for much, if not all of the variability in CO2 efflux rates. Our results help explain differences among previously published estimates of CO2 efflux at Mammoth Mountain and indicate that the long-term (annual) CO2 degassing rate has in fact remained constant since ~ 1997. Discounting the possibility of large meteorologically driven temporal variations in gas efflux at other volcanoes may result in spurious interpretations of transients do not reflect actual geologic processes. ?? 2001 Elsevier Science B.V. All rights reserved.

SwiftLase: a new technology for char-free ablation in rectal surgery

NASA Astrophysics Data System (ADS)

Arnold, David A.

1995-05-01

We describe layer-by-layer char-free ablation of hemorrhoids and other rectal lesions at very low CO2 laser power levels with a miniature `SwiftLaser' optomechanical flashscanner. Increased speed with excellent control, very shallow thermal damage, and less postoperative pain are the main advantages of the flashscan technology in rectal surgery.

Ecophysiological Significance of CO2-Recycling via Crassulacean Acid Metabolism in Talinum calycinum Engelm. (Portulacaceae) 1

PubMed Central

Martin, Craig E.; Higley, Michael; Wang, Wei-Zhong

1988-01-01

High levels of variability in gas exchange characteristics and degree of CAM-cycling were found in the same and different individuals of Talinum calycinum Engelm. collected from rock outcrops in Missouri. Differences in CO2 assimilation were mostly correlated with differences in shoot conductance to CO2 not shoot internal CO2 concentration. As found previously, CAM acid fluctuations were evident in well-watered plants exhibiting C3 gas exchange patterns (CAM-cycling) and also in drought-stressed plants with stomata closed, or nearly so, day and night (CAM-idling). Drought stress also resulted in rapid stomatal closure, conserving water during droughts. Maximal CO2 uptake rates occurred below 35°C; higher temperatures induced decreases in CO2 assimilation and conductance while shoot internal CO2 concentrations remained similar. Plant water-use-efficiency was severely curtailed at temperatures above 30°C. Tissue acid fluctuations were the result of changes in malic acid concentrations. Calculations of the amount of water potentially conserved by CAM-cycling yielded values of approximately 5 to 44% of daytime water loss. Thus, CAM-cycling may be an important adaptation minimizing water loss by perennial succulents growing in shallow soil on rock outcrops. PMID:16665946

CO2 snow depth and subsurface water-ice abundance in the northern hemisphere of Mars.

PubMed

Mitrofanov, I G; Zuber, M T; Litvak, M L; Boynton, W V; Smith, D E; Drake, D; Hamara, D; Kozyrev, A S; Sanin, A B; Shinohara, C; Saunders, R S; Tretyakov, V

2003-06-27

Observations of seasonal variations of neutron flux from the high-energy neutron detector (HEND) on Mars Odyssey combined with direct measurements of the thickness of condensed carbon dioxide by the Mars Orbiter Laser Altimeter (MOLA) on Mars Global Surveyor show a latitudinal dependence of northern winter deposition of carbon dioxide. The observations are also consistent with a shallow substrate consisting of a layer with water ice overlain by a layer of drier soil. The lower ice-rich layer contains between 50 and 75 weight % water, indicating that the shallow subsurface at northern polar latitudes on Mars is even more water rich than that in the south.

Growth history of Kilauea inferred from volatile concentrations in submarine-collected basalts

USGS Publications Warehouse

Coombs, Michelle L.; Sisson, Thomas W.; Lipman, Peter W.

2006-01-01

Major-element and volatile (H2O, CO2, S) compositions of glasses from the submarine flanks of Kilauea Volcano record its growth from pre-shield into tholeiite shield-stage. Pillow lavas of mildly alkalic basalt at 2600–1900 mbsl on the upper slope of the south flank are an intermediate link between deeper alkalic volcaniclastics and the modern tholeiite shield. Lava clast glasses from the west flank of Papau Seamount are subaerial Mauna Loa-like tholeiite and mark the contact between the two volcanoes. H2O and CO2 in sandstone and breccia glasses from the Hilina bench, and in alkalic to tholeiitic pillow glasses above and to the east, were measured by FTIR. Volatile saturation pressures equal sampling depths (10 MPa = 1000 m water) for south flank and Puna Ridge pillow lavas, suggesting recovery near eruption depths and/or vapor re-equilibration during down-slope flow. South flank glasses are divisible into low-pressure (CO2 <40 ppm, H2O < 0.5 wt.%, S <500 ppm), moderate-pressure (CO2 <40 ppm, H2O >0.5 wt.%, S 1000–1700 ppm), and high-pressure groups (CO2 >40 ppm, S  ∼1000 ppm), corresponding to eruption ≥ sea level, at moderate water depths (300–1000 m) or shallower but in disequilibrium, and in deep water (>1000 m). Saturation pressures range widely in early alkalic to strongly alkalic breccia clast and sandstone glasses, establishing that early Kīlauea's vents spanned much of Mauna Loa's submarine flank, with some vents exceeding sea level. Later south flank alkalic pillow lavas expose a sizeable submarine edifice that grew concurrent with nearby subaerial alkalic eruptions. The onset of the tholeiitic shield stage is marked by extension of eruptions eastward and into deeper water (to 5500 m) during growth of the Puna Ridge. Subaerial and shallow water eruptions from earliest Kilauea show that it is underlain shallowly by Mauna Loa, implying that Mauna Loa is larger, and Kilauea smaller, than previously recognized.Keywords

Carbonate-derived CO 2 purging magma at depth: Influence on the eruptive activity of Somma-Vesuvius, Italy

NASA Astrophysics Data System (ADS)

Dallai, Luigi; Cioni, Raffaello; Boschi, Chiara; D'Oriano, Claudia

2011-10-01

Mafic phenocrysts from selected products of the last 4 ka volcanic activity at Mt. Vesuvius were investigated for their chemical and O-isotope composition, as a proxy for primary magmas feeding the system. 18O/ 16O ratios of studied Mg-rich olivines suggest that near-primary shoshonitic to tephritic melts experienced a flux of sedimentary carbonate-derived CO 2, representing the early process of magma contamination in the roots of the volcanic structure. Bulk carbonate assimilation (physical digestion) mainly occurred in the shallow crust, strongly influencing magma chamber evolution. On a petrological and geochemical basis the effects of bulk sedimentary carbonate digestion on the chemical composition of the near-primary melts are resolved from those of carbonate-released CO 2 fluxed into magma. An important outcome of this process lies in the effect of external CO 2 in changing the overall volatile solubility of the magma, enhancing the ability of Vesuvius mafic magmas to rapidly rise and explosively erupt at the surface.

Risk Assessment of Carbon Sequestration into A Naturally Fractured Reservoir at Kevin Dome, Montana

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Minh; Onishi, Tsubasa; Carey, James William

In this report, we describe risk assessment work done using the National Risk Assessment Partnership (NRAP) applied to CO 2 storage at Kevin Dome, Montana. Geologic CO 2 sequestration in saline aquifers poses certain risks including CO 2/brine leakage through wells or non-sealing faults into groundwater or to the land surface. These risks are difficult to quantify due to data availability and uncertainty. One solution is to explore the consequences of these limitations by running large numbers of numerical simulations on the primary CO2 injection reservoir, shallow reservoirs/aquifers, faults, and wells to assess leakage risks and uncertainties. However, a largemore » number of full-physics simulations is usually too computationally expensive. The NRAP integrated assessment model (NRAP-IAM) uses reduced order models (ROMs) developed from full-physics simulations to address this issue. A powerful stochastic framework allows NRAPIAM to explore complex interactions among many uncertain variables and evaluate the likely performance of potential sequestration sites.« less

New insights into hydrothermal vent processes in the unique shallow-submarine arc-volcano, Kolumbo (Santorini), Greece

PubMed Central

Kilias, Stephanos P.; Nomikou, Paraskevi; Papanikolaou, Dimitrios; Polymenakou, Paraskevi N.; Godelitsas, Athanasios; Argyraki, Ariadne; Carey, Steven; Gamaletsos, Platon; Mertzimekis, Theo J.; Stathopoulou, Eleni; Goettlicher, Joerg; Steininger, Ralph; Betzelou, Konstantina; Livanos, Isidoros; Christakis, Christos; Bell, Katherine Croff; Scoullos, Michael

2013-01-01

We report on integrated geomorphological, mineralogical, geochemical and biological investigations of the hydrothermal vent field located on the floor of the density-stratified acidic (pH ~ 5) crater of the Kolumbo shallow-submarine arc-volcano, near Santorini. Kolumbo features rare geodynamic setting at convergent boundaries, where arc-volcanism and seafloor hydrothermal activity are occurring in thinned continental crust. Special focus is given to unique enrichments of polymetallic spires in Sb and Tl (±Hg, As, Au, Ag, Zn) indicating a new hybrid seafloor analogue of epithermal-to-volcanic-hosted-massive-sulphide deposits. Iron microbial-mat analyses reveal dominating ferrihydrite-type phases, and high-proportion of microbial sequences akin to "Nitrosopumilus maritimus", a mesophilic Thaumarchaeota strain capable of chemoautotrophic growth on hydrothermal ammonia and CO2. Our findings highlight that acidic shallow-submarine hydrothermal vents nourish marine ecosystems in which nitrifying Archaea are important and suggest ferrihydrite-type Fe3+-(hydrated)-oxyhydroxides in associated low-temperature iron mats are formed by anaerobic Fe2+-oxidation, dependent on microbially produced nitrate. PMID:23939372

Carbon isotope exchange between CO2 and CH4 in hydrothermal fluids from the Tuscan-Roman and Campanian degassing systems (central-southern Italy)

NASA Astrophysics Data System (ADS)

Tassi, F.; Fiebig, J.; Nocentini, M.; Vaselli, O.

2010-12-01

The carbon isotope composition in CO2 and CH4 are commonly used as exploration tools and diagnostic indicators to investigate the origin of endogenous gases. At temperature <200 °C both proportions and isotope ratios of these two gases are considered to be largely controlled by processes (i.e. bacterial activity, thermal hydrolysis, and cracking of organic matter) that are mainly dictated by kinetics. Recent investigations on abiogenic generation of CH4 suggest that at temperatures as low as 100 °C, CH4 production from CO2 has halftimes in the order of 1 year. The present work is based on the d13C-CO2 and d13C-CH4 values of more than 83 gas discharges from the Tuscan-Roman and Campanian degassing systems (central-southern Italy). The main aims are to i) investigate the processes regulating the chemical and isotopic compositions of CO2 and CH4 and ii) verify the use of the CO2-CH4 carbon isotopic equilibrium for evaluating the temperature of deep hydrothermal reservoirs. Our results show that the d13C-CH4 values, with few exceptions related to local production of biogenic CH4 at shallow depth, are > -40 ‰ V-PDB. The most intriguing feature of the measured d13C-CH4 values is that they progressively decrease from the peri-Tyrrhenian area, where productive geothermal systems and active volcanoes are located, to East, i.e. approaching the CH4-rich reservoirs that mark the Adriatic side of the Italian peninsula. The d13C-CO2 values are substantially spanning from a thermometamorphic to a mantle degassing CO2 and do not show any preferential spatial distribution. Secondary carbon isotope fractionation caused by interaction with relatively shallow aquifers may contribute to the scatter of d13C-CO2 values, considering the high solubility of CO2 in liquid water. However, the CO2-CH4 isotopic compositions of fluids from the high temperature geothermal systems characterizing the Tyrrhenian coast of central-southern Italy, i.e. Larderello, Mt. Amiata, Manziana and Phlegrean Fields, provide apparent equilibrium temperatures in the range of those directly measured in production wells and/or estimated on the basis of the CH4-CO2 chemical geothermometer. These results are consistent with the fact that the carbon isotopic equilibrium in the CO2-CH4 system has to be preceded by that of the chemical exchange because the latter has a kinetic rate 400 times faster than the isotopic partitioning. The observed agreement between measured and/or inferred aquifer temperatures with apparent carbon isotopic equilibration supports recent findings that CO2 and CH4 can attain carbon isotopic equilibrium in high-enthalpy hydrothermal systems. The d13C-CH4 values of gas discharges located eastward, toward the Appennine sedimentary chain, are likely produced by mixing of high temperature fluids from the geothermal areas and a relatively cold deep aquifer characterized by biogenic CH4: The higher distance from the geothermal-volcanic systems, the higher fraction of low temperature fluids.

Ecosystem CO2 and CH4 exchange in a mixed tundra and a fen within a hydrologically diverse Arctic landscape: 1. Modeling versus measurements

NASA Astrophysics Data System (ADS)

Grant, R. F.; Humphreys, E. R.; Lafleur, P. M.

2015-07-01

CO2 and CH4 exchange are strongly affected by hydrology in landscapes underlain by permafrost. Hypotheses for these effects in the model ecosys were tested by comparing modeled CO2 and CH4 exchange with CO2 fluxes measured by eddy covariance from 2006 to 2009, and with CH4 fluxes measured with surface chambers in 2008, along a topographic gradient at Daring Lake, NWT. In an upland tundra, rises in net CO2 uptake in warmer years were constrained by declines in CO2 influxes when vapor pressure deficits (D) exceeded 1.5 kPa and by rises in CO2 effluxes with greater active layer depth. Consequently, net CO2 uptake rose little with warming. In a lowland fen, CO2 influxes declined less with D and CO2 effluxes rose less with warming, so that rises in net CO2 uptake were greater than those in the tundra. Greater declines in CO2 influxes with warming in the tundra were modeled from greater soil-plant-atmosphere water potential gradients that developed under higher D in drained upland soil, and smaller rises in CO2 effluxes with warming in the fen were modeled from O2 constraints to heterotrophic and belowground autotrophic respiration from a shallow water table in poorly drained lowland soil. CH4 exchange modeled during July and August indicated very small influxes in the tundra and larger effluxes characterized by afternoon emission events caused by degassing of warming soil in the fen. Emissions of CH4 modeled from degassing during soil freezing in October-November contributed about one third of the annual total.

Monthly CO2 at A4HDYD station in a productive shallow marginal sea (Yellow Sea) with a seasonal thermocline: Controlling processes

NASA Astrophysics Data System (ADS)

Xu, Xuemei; Zang, Kunpeng; Zhao, Huade; Zheng, Nan; Huo, Cheng; Wang, Juying

2016-07-01

Based upon 21 field surveys conducted from March 2011 to November 2013, monthly variation of carbon dioxide partial pressure (pCO2) and other carbon system parameters were investigated for the first time (to our knowledge) at A4HDYD station (38°40‧N, 122°10‧E) located in the North Yellow Sea, a region with a seasonal thermocline. Surface pCO2 was undersaturated from March to May and nearly in equilibrium with the atmosphere from June to August. During September and November, pCO2 declined to a lower level than that from June to August, but reached the highest level in December. In contrast, pCO2 declined to atmospheric CO2 levels in February. Overall, the study area was a net CO2 sink at a rate of 0.85 ± 0.59 mol C m- 2 yr- 1. The underlying processes governing the variation of pCO2 were also examined. In general, temperature had an important influence on the monthly variation of pCO2, but its effect was counterbalanced by biological production in spring and vertical mixing in early winter. Our study indicated that dynamic mechanism studies based on high temporal resolution observations are urgently needed to understand the complexity of the carbon cycle and detect biogeochemical changes or ecosystem responses to climate change on continental margins.

CO2 leakage monitoring and analysis to understand the variation of CO2 concentration in vadose zone by natural effects

NASA Astrophysics Data System (ADS)

Joun, Won-Tak; Ha, Seung-Wook; Kim, Hyun Jung; Ju, YeoJin; Lee, Sung-Sun; Lee, Kang-Kun

2017-04-01

Controlled ex-situ experiments and continuous CO2 monitoring in the field are significant implications for detecting and monitoring potential leakage from CO2 sequestration reservoir. However, it is difficult to understand the observed parameters because the natural disturbance will fluctuate the signal of detections in given local system. To identify the original source leaking from sequestration reservoir and to distinguish the camouflaged signal of CO2 concentration, the artificial leakage test was conducted in shallow groundwater environment and long-term monitoring have been performed. The monitoring system included several parameters such as pH, temperature, groundwater level, CO2 gas concentration, wind speed and direction, atmospheric pressure, borehole pressure, and rainfall event etc. Especially in this study, focused on understanding a relationship among the CO2 concentration, wind speed, rainfall and pressure difference. The results represent that changes of CO2 concentration in vadose zone could be influenced by physical parameters and this reason is helpful in identifying the camouflaged signal of CO2 concentrations. The 1-D column laboratory experiment also was conducted to understand the sparking-peak as shown in observed data plot. The results showed a similar peak plot and could consider two assumptions why the sparking-peak was shown. First, the trapped CO2 gas was escaped when the water table was changed. Second, the pressure equivalence between CO2 gas and water was broken when the water table was changed. These field data analysis and laboratory experiment need to advance due to comprehensively quantify local long-term dynamics of the artificial CO2 leaking aquifer. Acknowledgement Financial support was provided by the "R&D Project on Environmental Management of Geologic CO2 Storage" from the KEITI (Project Number: 2014001810003)

Potential for the Use of Wireless Sensor Networks for Monitoring of CO2 Leakage Risks

NASA Astrophysics Data System (ADS)

Pawar, R.; Illangasekare, T. H.; Han, Q.; Jayasumana, A.

2015-12-01

Storage of supercritical CO2 in deep saline geologic formation is under study as a means to mitigate potential global climate change from green house gas loading to the atmosphere. Leakage of CO2 from these formations poses risk to the storage permanence goal of 99% of injected CO2 remaining sequestered from the atmosphere,. Leaked CO2 that migrates into overlying groundwater aquifers may cause changes in groundwater quality that pose risks to environmental and human health. For these reasons, technologies for monitoring, measuring and accounting of injected CO2 are necessary for permitting of CO2 sequestration projects under EPA's class VI CO2 injection well regulations. While the probability of leakage related to CO2 injection is thought to be small at characterized and permitted sites, it is still very important to protect the groundwater resources and develop methods that can efficiently and accurately detect CO2 leakage. Methods that have been proposed for leakage detection include remote sensing, soil gas monitoring, geophysical techniques, pressure monitoring, vegetation stress and eddy covariance measurements. We have demonstrated the use of wireless sensor networks (WSN) for monitoring of subsurface contaminant plumes. The adaptability of this technology for leakage monitoring of CO2 through geochemical changes in the shallow subsurface is explored. For this technology to be viable, it is necessary to identify geochemical indicators such as pH or electrical conductivity that have high potential for significant change in groundwater in the event of CO2 leakage. This talk presents a conceptual approach to use WSNs for CO2 leakage monitoring. Based on our past work on the use of WSN for subsurface monitoring, some of the challenges that need to be over come for this technology to be viable for leakage detection will be discussed.

Early warning of freshwater salinization due to upward brine displacement by species transport simulations combined with a hydrochemical genesis model

NASA Astrophysics Data System (ADS)

Langer, Maria; Kühn, Michael

2016-04-01

Shallow groundwater resources could be possibly affected by intruding brines, which are displaced along hydraulically conductive faults as result of subsurface activities like CO2 injection. To avoid salinization of potable freshwater aquifers an early detection of intruding saline water is necessary, especially in regions where an initial geogenic salinization already exists. Our study is based on work of Tillner et al. [1] and Langer et al. [2] who investigated the influence of permeable fault systems on brine displacement for the prospective storage site Beeskow-Birkholz in the Northeast German Basin. With a 3D regional scale model considering the deep groundwater system, they demonstrated that the existence of hydraulically conductive faults is not necessarily an exclusion criterion for potential injection sites, because salinization of shallower aquifers strongly depends on the effective damage zone volume, the initial salinity distribution and overlying reservoirs [2], while permeability of fault zones does not influence salinization of shallower aquifers significantly [1]. Here we extracted a 2D cross section regarding the upper 220 m of the study area mainly represented by shallow freshwater aquifers, but also considering an initial geogenic salinization [3]. We took flow rates of the intruding brines from the previous studies [2] and implemented species transport simulations with the program code SHEMAT [4]. Results are investigated and interpreted with the hydrochemical genesis model GEBAH [5] which has been already applied as early warning of saltwater intrusions into freshwater aquifers and surface water [6]. GEBAH allows a categorization of groundwater by the ion ratios of the dissolved components and offers a first indicative determination for an existence and the intensity of saline water intrusion in shallow groundwater aquifer, independent of the concentration of the solution. With our model we investigated the migration of saline water through a fault or an erosional channel which both allows an exchange between the shallow freshwater and the deeper saline water complex. The salinization potential of a drinking water well in vicinity to the brine source was determined for different scenarios. [1] Tillner E., Kempka T., Nakaten B., Kühn M. (2013) Brine migration through fault zones: 3D numerical simulations for a prospective CO2 storage site in Northeast Germany. International Journal of Greenhouse Gas Control 19, 689-703. doi: 10.1016/ j.ijggc.2013.03.012 [2] Langer M., Tillner E., Kempka T., Kühn M. (2015) Effective damage zone volume of fault zones and initial salinity distribution determine intensity of shallow aquifer salinization in geological underground utilization. Hydrology and Earth System Sciences Discussion, 12, 5703-5748. doi: 10.5194/hessd-12-5703-2015 [3] Hotzan, G., and Voss, T. (2013): Complex hydrogeochemic-genetic mapping for evaluation of the endangerment of pleistocene and tertiary aquifers by saline waters in the region Storkow-Frankfurt (Oder)-Eisenhüttenstadt. Brandenburgische Geowissenschaftliche Beiträge, 20 (1/2), 62-82. (in German) [4] Clauser C. (2003) SHEMAT and Processing SHEMAT - Numerical simulation of reactive flow in hot aquifers, Springer Publishers, Heidelberg [5] Rechlin, B., Hoffknecht, A., Scholz, H., Helms, A. (2010): Genetic evaluation of analyses from the hydrosphere. Software GEBAH Vers. 1.1 LBGR/GCI, Cottbus, Königs Wusterhausen (in German) [6] Rechlin, B. (2008): A method for a concentration free early detection of saltwater intrusions into freshwater aquifers and surface water. Brandenburgische Geowissenschaftliche Beiträge, 15 (1/2), 57-68. (in German)

In situ trace metal analysis of Neoarchaean--Ordovician shallow-marine microbial-carbonate-hosted pyrites.

PubMed

Gallagher, M; Turner, E C; Kamber, B S

2015-07-01

Pre-Cambrian atmospheric and oceanic redox evolutions are expressed in the inventory of redox-sensitive trace metals in marine sedimentary rocks. Most of the currently available information was derived from deep-water sedimentary rocks (black shale/banded iron formation). Many of the studied trace metals (e.g. Mo, U, Ni and Co) are sensitive to the composition of the exposed land surface and prevailing weathering style, and their oceanic inventory ultimately depends on the terrestrial flux. The validity of claims for increased/decreased terrestrial fluxes has remained untested as far as the shallow-marine environment is concerned. Here, the first systematic study of trace metal inventories of the shallow-marine environment by analysis of microbial carbonate-hosted pyrite, from ca. 2.65-0.52 Ga, is presented. A petrographic survey revealed a first-order difference in preservation of early diagenetic pyrite. Microbial carbonates formed before the 2.4 Ga great oxygenation event (GOE) are much richer in pyrite and contain pyrite grains of greater morphological variability but lesser chemical substitution than samples deposited after the GOE. This disparity in pyrite abundance and morphology is mirrored by the qualitative degree of preservation of organic matter (largely as kerogen). Thus, it seems that in microbial carbonates, pyrite formation and preservation were related to presence and preservation of organic C. Several redox-sensitive trace metals show interpretable temporal trends supporting earlier proposals derived from deep-water sedimentary rocks. Most notably, the shallow-water pyrite confirms a rise in the oceanic Mo inventory across the pre-Cambrian-Cambrian boundary, implying the establishment of efficient deep-ocean ventilation. The carbonate-hosted pyrite also confirms the Neoarchaean and early Palaeoproterozoic ocean had higher Ni concentration, which can now more firmly be attributed to a greater proportion of magnesian volcanic rock on land rather than a stronger hydrothermal flux of Ni. Additionally, systematic trends are reported for Co, As, and Zn, relating to terrestrial flux and oceanic productivity. © 2015 John Wiley & Sons Ltd.

Microbial activity of trench leachates from shallow-land, low-level radioactive waste disposal sites.

PubMed Central

Francis, A J; Dobbs, S; Nine, B J

1980-01-01

Trench leachate samples collected anoxically from shallow-land, low-level radioactive waste disposal sites were analyzed for total aerobic and anaerobic populations, sulfate reducers, denitrifiers, and methanogens. Among the several aerobic and anaerobic bacteria isolated, only Bacillus sp., Pseudomonas sp., Citrobacter sp., and Clostridium sp. were identified. Mixed bacterial cultures isolated from the trench leachates were able to grow anaerobically in trench leachates, which indicates that the radionuclides and organic chemicals present were not toxic to these bacteria. Changes in concentrations of several of the organic constituents of the waste leachate samples were observed due to anaerobic microbial activity. Growth of a mixed culture of trench-water bacteria in media containing a mixture of radionuclides, 60Co, 85Sr, and 134,137Cs, was not affected at total activity concentrations of 2.6 X 10(2) and 2.7 X 10(3) pCi/ml. PMID:7406490

Magma mixing and high fountaining during the 1959 Kīlauea Iki eruption, Hawai‘i

USGS Publications Warehouse

Sides, I.; Edmonds, M.; Maclennan, J.; Houghton, Bruce F.; Swanson, Don; Steele-MacInnis, M.J.

2014-01-01

The 1959 Kīlauea Iki eruption provides a unique opportunity to investigate the process of shallow magma mixing, its impact on the magmatic volatile budget and its role in triggering and driving episodes of Hawaiian fountaining. Melt inclusions hosted by olivine record a continuous decrease in H2O concentration through the 17 episodes of the eruption, while CO2 concentrations correlate with the degree of post-entrapment crystallization of olivine on the inclusion walls. Geochemical data, when combined with the magma budget and with contemporaneous eruption observations, show complex mixing between episodes involving hot, geochemically heterogeneous melts from depth, likely carrying exsolved vapor, and melts which had erupted at the surface, degassed and drained-back into the vent. The drained-back melts acted as a coolant, inducing rapid cooling of the more primitive melts and their olivines at shallow depths and inducing crystallization and vesiculation and triggering renewed fountaining. A consequence of the mixing is that the melts became vapor-undersaturated, so equilibration pressures cannot be inferred from them using saturation models. After the melt inclusions were trapped, continued growth of vapor bubbles, caused by enhanced post-entrapment crystallization, sequestered a large fraction of CO2 from the melt within the inclusions. This study, while cautioning against accepting melt inclusion CO2 concentrations “as measured” in mixed magmas, also illustrates that careful analysis and interpretation of post-entrapment modifications can turn this apparent challenge into a way to yield novel useful insights into the geochemical controls on eruption intensity.

Soft tissue molding technique in cleft lip and palate patient using laser surgery in combination with orthodontic appliance: A case report.

PubMed

Theerasopon, Pornpat; Wangsrimongkol, Tasanee; Sattayut, Sajee

2017-03-31

Although surgical treatment protocols for cleft lip and palate patients have been established, many patients still have some soft tissue defects after complete healing from surgical interventions. These are excess soft tissue, high attached fraena and firmed tethering scares. These soft tissue defects resulted shallowing of vestibule, restricted tooth movement, compromised periodontal health and trended to limit the maxillary growth. The aim of this case report was to present a method of correcting soft tissue defects after conventional surgery in cleft lip and palate patient by using combined laser surgery and orthodontic appliance. A bilateral cleft lip and palate patient with a clinical problem of shallow upper anterior vestibule after alveolar bone graft received a vestibular extension by using CO 2 laser with ablation and vaporization techniques at 4 W and continuous wave. A customized orthodontic appliance, called a buccal shield, was placed immediately after surgery and retained for 1 month to 3 months until complete soft tissue healing. The procedures were performed 2 episodes. Both interventions used the same CO 2 laser procedure. The first treatment resulted in partial re-attachment of soft tissue at surgical area. The second laser operation with the proper design of buccal shield providing passive contact with more extended flange resulting in a favorable outcome from 1 year follow up. Then the corrective orthodontic treatment could be continued effectively. The CO 2 laser surgery was a proper treatment for correcting soft tissue defects and the design of buccal shield was a key for success in molding surgical soft tissue.

Reductive dissolution and reactive solute transport in a sewage-contaminated glacial outwash aquifer

USGS Publications Warehouse

Lee, R.W.; Bennett, P.C.

1998-01-01

Contamination of shallow ground water by sewage effluent typically contains reduced chemical species that consume dissolved oxygen, developing either a low oxygen geochemical environment or an anaerobic geochemical environment. Based on the load of reduced chemical species discharged to shallow ground water and the amounts of reactants in the aquifer matrix, it should be possible to determine chemical processes in the aquifer and compare observed results to predicted ones. At the Otis Air Base research site (Cape Cod, Massachusetts) where sewage effluent has infiltrated the shallow aquifer since 1936, bacterially mediated processes such as nitrification, denitrification, manganese reduction, and iron reduction have been observed in the contaminant plume. In specific areas of the plume, dissolved manganese and iron have increased significantly where local geochemical conditions are favorable for reduction and transport of these constituents from the aquifer matrix. Dissolved manganese and iron concentrations ranged from 0.02 to 7.3 mg/L, and 0.001 to 13.0 mg/L, respectively, for 21 samples collected from 1988 to 1989. Reduction of manganese and iron is linked to microbial oxidation of sewage carbon, producing bicarbonate and the dissolved metal ions as by-products. Calculated production and flux of CO2 through the unsaturated zone from manganese reduction in the aquifer was 0.035 g/m2/d (12% of measured CO2 flux during winter). Manganese is limited in the aquifer, however. A one-dimensional, reaction-coupled transport model developed for the mildly reducing conditions in the sewage plume nearest the source beds showed that reduction, transport, and removal of manganese from the aquifer sediments should result in iron reduction where manganese has been depleted.

A suture delta: the co-evolution of tectonics and sedimentology as a remnant ocean basin closes; the Indo Burman ranges, northeast India and Bangladesh

NASA Astrophysics Data System (ADS)

Sincavage, R.; Betka, P. M.; Seeber, L.; Steckler, M. S.; Zoramthara, C.

2017-12-01

The closure of an ocean basin involves the interplay of tectonics and sedimentology, whereby thick successions of fluvio-deltaic and shallow marine sediment accumulate in the closing gap between the subduction zone and passive margin. The transition from subduction to collision involves processes that are inherently time-transgressive and co-evolve to influence the nature of the developing tectonic wedge. The Indo-Burman Ranges (IBR) of eastern India present a unique opportunity to examine this scenario on a variety of spatial (10-2­­­-105 m2) and temporal (1 a-10 Ma) scales. Recent field mapping campaigns in the IBR have illuminated analogous depositional environments expressed in the Neogene outcrops of the IBR and the Holocene sediment archive of the Ganges-Brahmaputra-Meghna delta (GBMD). Six distinct lithofacies are present in shallow-marine to fluvial strata of the IBR, containing sedimentary structures that reflect depositional environments correlative with the modern delta. Cyclical alternations of fine sands and silts in packages on the order of 15-20 cm thick define part of the shallow-marine section (M2 facies) that we interpret to represent the foreset beds of the ancient subaqueous delta. The overall scale and sedimentary structures of M2 compare favorably with modern foreset deposits in the Bay of Bengal. Tan-orange medium-grained, well sorted fluvial sandstone that contain large scale (1-10 m) tabular and trough cross bedding represent large-river channel deposits (F2 facies) that overlie the shallow marine strata. F2 deposits bear a striking resemblance in scale and character to bar deposits along the modern Jamuna River. Preliminary grain size analyses on the F2 facies yield grain size distributions that are remarkably consistent with Brahmaputra-sourced mid-Holocene sediments from Sylhet basin within the GBMD. Current research on the GBMD has revealed quantifiable trends in bed thicknesses, downstream fining, and grain size within fluvial deposits. These data will be coupled with ongoing structural and geo- and thermochronology field studies of the IBR that aim to continue to reveal the structural and stratigraphic evolution of this geologically active and densely populated region.

Cibicidodes Pachyderma B/Ca as a Shalow Water Carbonate Saturation State Proxy

NASA Astrophysics Data System (ADS)

Wojcieszek, D. E.; Flower, B. P.; Moyer, R. P.; Byrne, R. H.

2012-12-01

Since the industrial revolution, the oceans have absorbed about 25% of anthropogenic CO2 emissions to the atmosphere, leading to a decrease in seawater pH (termed ocean acidification: OA) as well as many associated effects, including decreased saturation states. Assessment of the effects of OA on marine ecosystems is presently based on <50 years of observations. Reconstructions of past seawater chemistry and its impact on biota over much longer time scales can provide essential context for likely future consequences of OA. Reliable oceanic paleo-proxies for influential chemical variables such as pH and carbonate saturation state are crucial components for examining ancient environments affected by OA. Addition of CO2 to seawater leads to not only decreases in seawater pH and saturation state, but also the extent to which boron (B) is incorporated into CaCO3 during biotic calcification. Consequently, the abundance of B in calcite could reflect pH and/or saturation state of the water in which calcification occurred. Recent studies indicate a linear relationship between the ratio of boron to calcium (B/Ca) in benthic foraminifera shells ( Cibicidoides wuellerstorfi, C. mundulus) and the degree of carbonate saturation (Δ[CO32-]), defined as a difference between [CO32-]in situ and [CO32-]saturation. However, the observed relationship between B/Ca and Δ[CO32-] was only established for depths >1000m. Thus, since OA most immediately affects the upper 1000 m of the water column, a reliable shallow water (<1000 m) carbonate chemistry proxy is desirable. We are testing the utility of B/Ca in Cibicidoides pachyderma as a shallow water Δ[CO32-] proxy. C. pachyderma is an epibenthic species and therefore records the composition of bottom, rather than interstitial, waters. It usually inhabits depths between 200 and 1000 m, and is a common species in the Gulf of Mexico. The gently sloping West Florida Shelf (WFS) is an excellent setting for this kind of study as it provides a full range of depths habitable by C.pachyderma. Nine surface sediment samples were collected along a 150-1400 m depth transect across the WFS. Bottom water pH along the transect ranged between 7.82 and 8.12, corresponding to Δ[CO32-] values between 35 and 200 μmol/kg. Preliminary B/Ca data range between 109 and 174 μmol/mol and display high variability. Our results suggest that WFS bottom water chemistry may be intermittently affected by phenomena such as eutrophication-induced hypoxia or boundary layer differences between the lower water column and the sediment-water interface. Additional B/Ca and bottom water measurements are planned to characterize the relationship between C.pachyderma B/Ca and Δ[CO32-], and extend global benthic foraminifera B/Ca calibrations to depths shallower than 1000 m.

Arsenic, vanadium, iron, and manganese biogeochemistry in a deltaic wetland, southern Louisiana, USA

DOE PAGES

Telfeyan, Katherine; Breaux, Alexander; Kim, Jihyuk; ...

2017-04-05

Geochemical cycling of the redox-sensitive trace elements arsenic (As) and vanadium (V) was examined in shallow pore waters from a marsh in an interdistributary embayment of the lower Mississippi River Delta. In particular, we explore how redox changes with depth and distance from the Mississippi River affect As and V cycling in the marsh pore waters. Previous geophysical surveys and radon mass balance calculations suggested that Myrtle Grove Canal and bordering marsh receive fresh groundwater, derived in large part from seepage of the Mississippi River, which subsequently mixes with brackish waters of Barataria Bay. In addition, the redox geochemistry ofmore » pore waters in the wetlands is affected by Fe and S cycling in the shallow subsurface (0-20 cm). Sediments with high organic matter content undergo SO 4 2- reduction, a process ubiquitous in the shallow subsurface but largely absent at greater depths (~3 m). Instead, at depth, in the absence of organic-rich sediments, Fe concentrations are elevated, suggesting that reduction of Fe(III) oxides/oxyhydroxides buffers redox conditions. Arsenic and V cycling in the shallow subsurface are decoupled from their behavior at depth, where both V and As appear to be removed from solution by either diffusion or adsorption onto, or co-precipitation with, authigenic minerals within the deeper aquifer sediments. Pore water As concentrations are greatest in the shallow subsurface (e.g., up to 315 nmol kg -1 in the top ~20 cm of the sediment) but decrease with depth, reaching values <30 nmol kg -1 at depths between 3 and 4 m. Vanadium concentrations appear to be tightly coupled to Fe cycling in the shallow subsurface, but at depth, V may be adsorbed to clay or sedimentary organic matter (SOM). Diffusive fluxes are calculated to examine the export of trace elements from the shallow marsh pore waters to the overlying canal water that floods the marsh. The computed fluxes suggest that the shallow sediment serves as a source of Fe, Mn, and As to the surface waters, whereas the sediments act as a sink for V. Iron and Mn fluxes are substantial, ranging from 50 to 30,000 and 770 to 4,300 nmol cm -2 day -1, respectively, whereas As fluxes are much less, ranging from 2.1 to 17 nmol cm -2 day -1. Vanadium fluxes range from 3.0 nmol cm -2 day -1 directed into the sediment to 1.7 nmol cm -2 day -1 directed out of the sediment« less

Arsenic, vanadium, iron, and manganese biogeochemistry in a deltaic wetland, southern Louisiana, USA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Telfeyan, Katherine; Breaux, Alexander; Kim, Jihyuk

Geochemical cycling of the redox-sensitive trace elements arsenic (As) and vanadium (V) was examined in shallow pore waters from a marsh in an interdistributary embayment of the lower Mississippi River Delta. In particular, we explore how redox changes with depth and distance from the Mississippi River affect As and V cycling in the marsh pore waters. Previous geophysical surveys and radon mass balance calculations suggested that Myrtle Grove Canal and bordering marsh receive fresh groundwater, derived in large part from seepage of the Mississippi River, which subsequently mixes with brackish waters of Barataria Bay. In addition, the redox geochemistry ofmore » pore waters in the wetlands is affected by Fe and S cycling in the shallow subsurface (0-20 cm). Sediments with high organic matter content undergo SO 4 2- reduction, a process ubiquitous in the shallow subsurface but largely absent at greater depths (~3 m). Instead, at depth, in the absence of organic-rich sediments, Fe concentrations are elevated, suggesting that reduction of Fe(III) oxides/oxyhydroxides buffers redox conditions. Arsenic and V cycling in the shallow subsurface are decoupled from their behavior at depth, where both V and As appear to be removed from solution by either diffusion or adsorption onto, or co-precipitation with, authigenic minerals within the deeper aquifer sediments. Pore water As concentrations are greatest in the shallow subsurface (e.g., up to 315 nmol kg -1 in the top ~20 cm of the sediment) but decrease with depth, reaching values <30 nmol kg -1 at depths between 3 and 4 m. Vanadium concentrations appear to be tightly coupled to Fe cycling in the shallow subsurface, but at depth, V may be adsorbed to clay or sedimentary organic matter (SOM). Diffusive fluxes are calculated to examine the export of trace elements from the shallow marsh pore waters to the overlying canal water that floods the marsh. The computed fluxes suggest that the shallow sediment serves as a source of Fe, Mn, and As to the surface waters, whereas the sediments act as a sink for V. Iron and Mn fluxes are substantial, ranging from 50 to 30,000 and 770 to 4,300 nmol cm -2 day -1, respectively, whereas As fluxes are much less, ranging from 2.1 to 17 nmol cm -2 day -1. Vanadium fluxes range from 3.0 nmol cm -2 day -1 directed into the sediment to 1.7 nmol cm -2 day -1 directed out of the sediment« less

Temporal variability of air-sea CO2 exchange in a low-emission estuary

NASA Astrophysics Data System (ADS)

Mørk, Eva Thorborg; Sejr, Mikael Kristian; Stæhr, Peter Anton; Sørensen, Lise Lotte

2016-07-01

There is the need for further study of whether global estimates of air-sea CO2 exchange in estuarine systems capture the relevant temporal variability and, as such, the temporal variability of bulk parameterized and directly measured CO2 fluxes was investigated in the Danish estuary, Roskilde Fjord. The air-sea CO2 fluxes showed large temporal variability across seasons and between days and that more than 30% of the net CO2 emission in 2013 was a result of two large fall and winter storms. The diurnal variability of ΔpCO2 was up to 400 during summer changing the estuary from a source to a sink of CO2 within the day. Across seasons the system was suggested to change from a sink of atmospheric CO2 during spring to near neutral during summer and later to a source of atmospheric CO2 during fall. Results indicated that Roskilde Fjord was an annual low-emission estuary, with an estimated bulk parameterized release of 3.9 ± 8.7 mol CO2 m-2 y-1 during 2012-2013. It was suggested that the production-respiration balance leading to the low annual emission in Roskilde Fjord, was caused by the shallow depth, long residence time and high water quality in the estuary. In the data analysis the eddy covariance CO2 flux samples were filtered according to the H2Osbnd CO2 cross-sensitivity assessment suggested by Landwehr et al. (2014). This filtering reduced episodes of contradicting directions between measured and bulk parameterized air-sea CO2 exchanges and changed the net air-sea CO2 exchange from an uptake to a release. The CO2 gas transfer velocity was calculated from directly measured CO2 fluxes and ΔpCO2 and agreed to previous observations and parameterizations.

The Monitoring of Sallow CO2 Leakage From the CO2 Release Experiment in South Korea

NASA Astrophysics Data System (ADS)

Kim, H. J.; Han, S. H.; Kim, S.; Son, Y.

2017-12-01

This study was conducted to analyze the in-soil CO2 gas diffusion from the K-COSEM shallow CO2 release experiment. The study site consisting of five zones was built in Eumseong, South Korea, and approximately 1.8 t CO2 were injected from the perforated release well at Zones 1 to 4 from June 1 to 30, 2016. In-soil CO2 concentrations were measured once a day at 15 cm and 60 cm depths at 0 m, 2.5 m, 5.0 m, and 10.0 m away from the CO2 releasing well using a portable gas analyzer (GA5000) from May 11 to July 27, 2016. On June 4, CO2 leakage was simultaneously detected at 15 cm (8.8 %) and 60 cm (44.0 %) depths at 0 m from the well at Zone 3, and were increased up to about 30 % and 70 %, respectively. During the CO2 injection period, CO2 concentrations measured at 15 cm depth were significantly lower than those measured at 60 cm depth because of the atmospheric pressure effect. After stopping the CO2 injection, CO2 concentrations gradually decreased until July 27, but were still higher than the natural background concentration. This result suggested the possibility of long-term CO2 leakage. In addition, low levels of CO2 leakage were determined using CO2 regression analysis and CO2:O2 ratio. CO2 concentrations measured at 60 cm depth at 0 m from the well at Zones 1 to 4 consistently showed sigmoid increasing patterns with the injection time (R2=0.60-0.99). O2 concentrations at 15 cm and 60 cm depths from the CO2 release experiment were reached 0 % at about 76 % and 84 % of CO2 concentrations, respectively, whereas, those from biological reaction approached 0 % when CO2 increased to about 21 %. Therefore, deep underground monitoring would be able to detect CO2 leakage faster than near-surface monitoring, and CO2 regression and CO2:O2 ratio analyses seemed to be useful as clear indicators of CO2 leakage.

Reactive collisions of sulfur dioxide with molten carbonates

PubMed Central

Krebs, Thomas; Nathanson, Gilbert M.

2010-01-01

Molecular beam scattering experiments are used to investigate reactions of SO2 at the surface of a molten alkali carbonate eutectic at 683 K. We find that two-thirds of the SO2 molecules that thermalize at the surface of the melt are converted to gaseous CO2 via the reaction . The CO2 product is formed from SO2 in less than 10-6 s, implying that the reaction takes place in a shallow liquid region less than 100 Å deep. The reaction probability does not vary between 683 and 883 K, further implying a compensation between decreasing SO2 residence time in the near-interfacial region and increasing reactivity at higher temperatures. These results demonstrate the remarkable efficiency of SO2 → CO2 conversion by molten carbonates, which appear to be much more reactive than dry calcium carbonate or wet slurries commonly used for flue gas desulfurization in coal-burning power plants. PMID:20133648

Atmospheric fossil fuel CO2 traced by 14CO2 and air quality index pollutant observations in Beijing and Xiamen, China.

PubMed

Niu, Zhenchuan; Zhou, Weijian; Feng, Xue; Feng, Tian; Wu, Shugang; Cheng, Peng; Lu, Xuefeng; Du, Hua; Xiong, Xiaohu; Fu, Yunchong

2018-06-01

Radiocarbon ( 14 C) is the most accurate tracer available for quantifying atmospheric CO 2 derived from fossil fuel (CO 2ff ), but it is expensive and time-consuming to measure. Here, we used common hourly Air Quality Index (AQI) pollutants (AQI, PM 2.5 , PM 10 , and CO) to indirectly trace diurnal CO 2ff variations during certain days at the urban sites in Beijing and Xiamen, China, based on linear relationships between AQI pollutants and CO 2ff traced by 14 C ([Formula: see text]) for semimonthly samples obtained in 2014. We validated these indirectly traced CO 2ff (CO 2ff-in ) concentrations against [Formula: see text] concentrations traced by simultaneous diurnal 14 CO 2 observations. Significant (p < 0.05) strong correlations were observed between each of the separate AQI pollutants and [Formula: see text] for the semimonthly samples. Diurnal variations in CO 2ff traced by each of the AQI pollutants generally showed similar trends to those of [Formula: see text], with high agreement at the sampling site in Beijing and relatively poor agreement at the sampling site in Xiamen. AQI pollutant tracers showed high normalized root-mean-square (NRMS) errors for the summer diurnal samples due to low [Formula: see text] concentrations. After the removal of these summer samples, the NRMS errors for AQI pollutant tracers were in the range of 31.6-64.2%. CO generally showed a high agreement and low NRMS errors among these indirect tracers. Based on these linear relationships, monthly CO 2ff averages at the sampling sites in Beijing and Xiamen were traced using CO concentration as a tracer. The monthly CO 2ff averages at the Beijing site showed a shallow U-type variation. These results indicate that CO can be used to trace CO 2ff variations in Chinese cities with CO 2ff concentrations above 5 ppm.

Remaining gaps for "safe" CO2 storage: the INGV CO2GAPS vision of "learning by doing" monitoring geogas leakage, reservoirs contamination/mixing and induced/triggered seismicity

NASA Astrophysics Data System (ADS)

Quattrocchi, F.; Vinciguerra, S.; Chiarabba, C.; Boschi, E.; Anselmi, M.; Burrato, P.; Buttinelli, M.; Cantucci, B.; Cinti, D.; Galli, G.; Improta, L.; Nazzari, M.; Pischiutta, M.; Pizzino, L.; Procesi, M.; Rovelli, A.; Sciarra, A.; Voltattorni, N.

2012-12-01

The CO2GAPS project proposed by INGV is intended to build up an European Proposal for a new kind of research strategy in the field of the geogas storage. Aim of the project would be to fill such key GAPS concerning the main risks associated to CO2 storage and their implications on the entire Carbon Capture and Storage (CCS) process, which are: i) the geogas leakage both in soils and shallow aquifers, up to indoor seepage; ii) the reservoirs contamination/mixing by hydrocarbons and heavy metals; iii) induced or triggered seismicity and microseismicity, especially for seismogenic blind faults. In order to consider such risks and make the CCS public acceptance easier, a new kind of research approach should be performed by: i) a better multi-disciplinary and "site specific" risk assessment; ii) the development of more reliable multi-disciplinary monitoring protocols. In this view robust pre-injection base-lines (seismicity and degassing) as well as identification and discrimination criteria for potential anomalies are mandatory. CO2 injection dynamic modelling presently not consider reservoirs geomechanical properties during reactive mass-transport large scale simulations. Complex simulations of the contemporaneous physic-chemical processes involving CO2-rich plumes which move, react and help to crack the reservoir rocks are not totally performed. These activities should not be accomplished only by the oil-gas/electric companies, since the experienced know-how should be shared among the CCS industrial operators and research institutions, with the governments support and overview, also flanked by a transparent and "peer reviewed" scientific popularization process. In this context, a preliminary and reliable 3D modelling of the entire "storage complex" as defined by the European Directive 31/2009 is strictly necessary, taking into account the above mentioned geological, geochemical and geophysical risks. New scientific results could also highlighting such opportunities recently shown by strategic researches on the synergies between the use of underground space (e.g. CH4, CO2 storage and deep geothermics) for energetic supplying purposes. The CO2GAPS approach would merge together geomechanical and geochemical data with seismic velocity and anisotropy properties of the crust, induced seismicity data, gravimetry, EM techniques, and "early alarm" procedures for leakage/cracks detection in shallow geo-spheres (e.g. abandoned wells, naturally seismic and degassing zones). Moreover, a full merging of those data is necessary for a reliable 3D-Earth modelling and the subsequent reactive transport simulations. CO2GAPS vision would apply and verify these issues working on several European selected sites, taking also into account complex systems such as "inland" active faulted blocks close to potential off-shore CO2 storage sites, ECBM faulted prone-areas, "inland" injection test site and CO2 natural faulted analogues. The purpose of these activities focus on the study of long-term fate of stored CO2, leakage mechanisms through the cap-rock and/or abandoned wells, cement wells reactivity, as well as the effects of impurities in the CO2 streams, their removal costs, the use of tracers and the role of biota.

Constraining magma ascent and degassing paths with olivine- and clinopyroxene-hosted melt inclusions: Evidence for multiple depths of crystallization and boundary-layer entrapment

NASA Astrophysics Data System (ADS)

Lloyd, A. S.; Newcombe, M. E.; Plank, T. A.

2016-12-01

Although olivine-hosted melt inclusions (MIs) remain the gold standard for recovering volatile concentrations of primitive magmas, later-fractionating minerals may be more appropriate for assessing magma storage conditions immediately prior to eruption. We present volatile analyses of MIs entrapped in early (Mg# 81-83) olivine and later (Mg# 70-80) clinopyroxene (Cpx) from the 1977 eruption of Seguam volcano, to assess the ascent history prior to this violent strombolian eruption. The olivine-hosted MIs contain average volatile concentrations (n=16) of 3.79 wt% H2O, 167 ppm CO2, 592 ppm Cl, and 133 ppm F, consistent with an entrapment pressure of 200 to 300 MPa ( 10-13 km depth) if the CO2 contained in the bubble is taken into account (Moore et al., 2015). Cpx phenocrysts contain two distinct MI assemblages; the inner assemblage consists of randomly distributed, rounded MIs which never contain a vapor bubble. Average volatile concentrations of the inner assemblage MIs (n=11) are 0.96 wt% H2O, 98 ppm CO2, 798 ppm Cl, and 280 ppm F, consistent with an entrapment at much shallower depth, 2 km. The outer assemblage contains inclusions too small for routine volatile analysis. Inner assemblage Cpx-hosted MIs preserve average enrichments of 1.3x and 2x for Cl and F respectively, and are similarly enriched in incompatible minor and trace elements (up to a factor of 5x). Two potential scenarios can explain these observations. The enrichments may represent the entrapment of an unrelated highly-fractionated, shallow magma (which is unsupported by the whole rock record at Seguam). A second possibility is enrichment through boundary layer entrapment during a period of rapid crystal growth during ascent through the upper crust. Boundary layer entrapment during MI formation is further supported by a negative correlation between the degree of enrichment and the diffusivity of individual elements, which is consistent with growth rates 10-8 m/s. Although the olivine-hosted MIs record a volatile-rich storage region, the later-fractionating Cpx indicate a phase of rapid crystallization, likely driven by water loss from the melt at shallow depths. This work highlights the information added by analyzing multiple phases in order to reconstruct the degassing path of magma prior to eruption.

Multiple Origins of Pyroclastic Obsidian and Implications for Changes in the Dynamics of the 1300 BP eruption of Newberry Volcano, USA

NASA Astrophysics Data System (ADS)

Rust, A. C.; Cashman, K. V.

2005-12-01

Like many rhyolite tephras, the pyroclastic deposits of the 1300 B.P. eruption of Newberry Volcano, USA, contain minor amounts of obsidian. The H2O and CO2 contents and textures of these clasts vary considerably and provide information on eruption history and dynamics. Early in the eruption, obsidian probably derived from veins of vanguard magma or tuffisite that, together with wall rock fragments, were eroded and incorporated into the eruption column as the vent widened. Later, following a temporary cessation of activity, the proportion of obsidian to lithic fragments increased and new types of obsidian dominated, types that represent remnants of a shallow conduit plug and welded fallback material. Analysis of bubble geometries provide flow parameters and time scales operative for deformation within the shallow conduit. Furthermore, spatial variations in CO2 help constrain welding and wall rock assimilation time scales. Comparison of obsidian characteristics from the Newberry eruption with those of the well-studied Mono Craters eruption shows intriguing differences in obsidian formation that may relate to the nature of the conduit feeding the two events. From this comparison we conclude that obsidian is less likely to provide information on magmatic fragmentation than on time scales and mechanisms of pre-fragmentation magma ascent.

Seagrass beds as ocean acidification refuges for mussels? High resolution measurements of pCO2 and O2 in a Zostera marina and Mytilus edulis mosaic habitat

NASA Astrophysics Data System (ADS)

Saderne, V.; Fietzek, P.; Aßmann, S.; Körtzinger, A.; Hiebenthal, C.

2015-07-01

It has been speculated that macrophytes beds might act as a refuge for calcifiers from ocean acidification. In the shallow nearshores of the western Kiel Bay (Baltic Sea), mussel and seagrass beds are interlacing, forming a mosaic habitat. Naturally, the diverse physiological activities of seagrasses and mussels are affected by seawater carbonate chemistry and they locally modify it in return. Calcification by shellfishes is sensitive to seawater acidity; therefore the photosynthetic activity of seagrasses in confined shallow waters creates favorable chemical conditions to calcification at daytime but turn the habitat less favorable or even corrosive to shells at night. In contrast, mussel respiration releases CO2, turning the environment more favorable for photosynthesis by adjacent seagrasses. At the end of summer, these dynamics are altered by the invasion of high pCO2/low O2 coming from the deep water of the Bay. However, it is in summer that mussel spats settle on the leaves of seagrasses until migrating to the permanent habitat where they will grow adult. These early life phases (larvae/spats) are considered as most sensitive with regard to seawater acidity. So far, the dynamics of CO2 have never been continuously measured during this key period of the year, mostly due to the technological limitations. In this project we used a combination of state-of-the-art technologies and discrete sampling to obtain high-resolution time-series of pCO2 and O2 at the interface between a seagrass and a mussel patch in Kiel Bay in August and September 2013. From these, we derive the entire carbonate chemistry using statistical models. We found the monthly average pCO2 more than 50 % (approx. 640 μatm for August and September) above atmospheric equilibrium right above the mussel patch together with large diel variations of pCO2 within 24 h: 887 ± 331 μatm in August and 742 ± 281 μatm in September (mean ± SD). We observed important daily corrosiveness for calcium carbonates (Ωarag and Ωcalc < 1) centered on sunrise. On the positive side, the investigated habitat never suffered from hypoxia during the study period. We emphasize the need for more experiments on the impact of these acidic conditions on (juvenile) mussels with a focus on the distinct day-night variations observed.

Combined Effects of Ocean Acidification and Light or Nitrogen Availabilities on 13C Fractionation in Marine Dinoflagellates.

PubMed

Hoins, Mirja; Eberlein, Tim; Groβmann, Christian H; Brandenburg, Karen; Reichart, Gert-Jan; Rost, Björn; Sluijs, Appy; Van de Waal, Dedmer B

2016-01-01

Along with increasing oceanic CO2 concentrations, enhanced stratification constrains phytoplankton to shallower upper mixed layers with altered light regimes and nutrient concentrations. Here, we investigate the effects of elevated pCO2 in combination with light or nitrogen-limitation on 13C fractionation (εp) in four dinoflagellate species. We cultured Gonyaulax spinifera and Protoceratium reticulatum in dilute batches under low-light ('LL') and high-light ('HL') conditions, and grew Alexandrium fundyense and Scrippsiella trochoidea in nitrogen-limited continuous cultures ('LN') and nitrogen-replete batches ('HN'). The observed CO2-dependency of εp remained unaffected by the availability of light for both G. spinifera and P. reticulatum, though at HL εp was consistently lower by about 2.7‰ over the tested CO2 range for P. reticulatum. This may reflect increased uptake of (13C-enriched) bicarbonate fueled by increased ATP production under HL conditions. The observed CO2-dependency of εp disappeared under LN conditions in both A. fundyense and S. trochoidea. The generally higher εp under LN may be associated with lower organic carbon production rates and/or higher ATP:NADPH ratios. CO2-dependent εp under non-limiting conditions has been observed in several dinoflagellate species, showing potential for a new CO2-proxy. Our results however demonstrate that light- and nitrogen-limitation also affect εp, thereby illustrating the need to carefully consider prevailing environmental conditions.

Natural Carbonation of Peridotite and Applications for Carbon Storage

NASA Astrophysics Data System (ADS)

Streit, E.; Kelemen, P.; Matter, J.

2009-05-01

Natural carbonation of peridotite in the Samail Ophiolite of Oman is surprisingly rapid and could be further enhanced to provide a safe, permanent method of CO2 storage through in situ formation of carbonate minerals. Carbonate veins form by low-temperature reaction between peridotite and groundwater in a shallow weathering horizon. Reaction with peridotite drives up the pH of the water, and extensive travertine terraces form where this groundwater emerges at the surface in alkaline springs. The potential sink for CO2 in peridotite is enormous: adding 1wt% CO2 to the peridotite in Oman could consume 1/4 of all atmospheric carbon, and several peridotite bodies of comparable size exist throughout the world. Thus carbonation rate and cost, not reservoir size, are the limiting factors on the usefulness of in situ mineral carbonation of peridotite for carbon storage. The carbonate veins in Oman are much younger than previously believed, yielding average 14C ages of 28,000 years. Age data plus estimated volumes of carbonate veins and terraces suggest 10,000 to 100,000 tons per year of CO2 are consumed by these peridotite weathering reactions in Oman. This rate can be enhanced by drilling, hydraulic fracture, injecting CO2-rich fluid, and increasing reaction temperature. Drilling and hydraulic fracture can increase volume of peridotite available for reaction. Additional fracture may occur due to the solid volume increase of the carbonation reaction, and field observations suggest that such reaction-assisted fracture may be responsible for hierarchical carbonate vein networks in peridotite. Natural carbonation of peridotite in Oman occurs at low pCO2, resulting in partial carbonation of peridotite, forming magnesite and serpentine. Raising pCO2 increases carbonation efficiency, forming of magnesite + talc, or at complete carbonation, magnesite + quartz, allowing ˜30wt% CO2 to be added to the peridotite. Increasing the temperature to 185°C can improve the reaction rate by a factor of more than 100,000. Thermal modeling suggests that after an initial heating stage, CO2-rich fluids injected at relatively low temperature can be heated by exothermic carbonation reactions, offsetting diffusive heat loss to maintain optimal temperatures for rapid carbonation without additional energy input. With these enhancements, in situ carbonation could consume more than 1 billion tons of CO2 per cubic kilometer of peridotite per year. Costs associated with this method include drilling, hydraulic fracture, initial heating, CO2 capture and transport, fluid injection and monitoring. The techniques for drilling, fracture and injection are routinely used by oil companies. Compared with other carbon storage methods, in situ mineral carbonation has several advantages. It offers permanent storage that is safer and easier to monitor than storage of CO2-rich fluids in porous underground reservoirs or in the ocean. It may also be less costly than ex situ mineral carbonation, which requires quarrying and transportation of peridotite, grinding and heat treatment, reactions in pressure vessels at elevated temperature, production of catalysts, and disposal of carbonated material. An alternative method, carbonation by reaction of offshore peridotite with shallow seawater rather than CO2-rich fluids, would consume less CO2, but would avoid the costs of CO2 capture and transport inherent in other CCS methods. Drilling to depths where rocks are already close to the optimal carbonation temperature would avoid pre-heating costs and circulate water by thermal convection rather than pumping fluids.

Understanding dynamics of Martian winter polar vortex with “improved” moist-convective shallow water model

NASA Astrophysics Data System (ADS)

Rostami, M.; Zeitlin, V.

2017-12-01

We show how the properties of the Mars polar vortex can be understood in the framework of a simple shallow-water type model obtained by vertical averaging of the adiabatic “primitive” equations, and “improved” by inclusion of thermal relaxation and convective fluxes due to the phase transitions of CO 2, the major constituent of the Martian atmosphere. We perform stability analysis of the vortex, show that corresponding mean zonal flow is unstable, and simulate numerically non-linear saturation of the instability. We show in this way that, while non-linear adiabatic saturation of the instability tends to reorganize the vortex, the diabatic effects prevent this, and thus provide an explanation of the vortex form and longevity.

Ecological effects of ocean acidification and habitat complexity on reef-associated macroinvertebrate communities.

PubMed

Fabricius, K E; De'ath, G; Noonan, S; Uthicke, S

2014-01-22

The ecological effects of ocean acidification (OA) from rising atmospheric carbon dioxide (CO2) on benthic marine communities are largely unknown. We investigated in situ the consequences of long-term exposure to high CO2 on coral-reef-associated macroinvertebrate communities around three shallow volcanic CO2 seeps in Papua New Guinea. The densities of many groups and the number of taxa (classes and phyla) of macroinvertebrates were significantly reduced at elevated CO2 (425-1100 µatm) compared with control sites. However, sensitivities of some groups, including decapod crustaceans, ascidians and several echinoderms, contrasted with predictions of their physiological CO2 tolerances derived from laboratory experiments. High CO2 reduced the availability of structurally complex corals that are essential refugia for many reef-associated macroinvertebrates. This loss of habitat complexity was also associated with losses in many macroinvertebrate groups, especially predation-prone mobile taxa, including crustaceans and crinoids. The transition from living to dead coral as substratum and habitat further altered macroinvertebrate communities, with far more taxa losing than gaining in numbers. Our study shows that indirect ecological effects of OA (reduced habitat complexity) will complement its direct physiological effects and together with the loss of coral cover through climate change will severely affect macroinvertebrate communities in coral reefs.

Ecological effects of ocean acidification and habitat complexity on reef-associated macroinvertebrate communities

PubMed Central

Fabricius, K. E.; De'ath, G.; Noonan, S.; Uthicke, S.

2014-01-01

The ecological effects of ocean acidification (OA) from rising atmospheric carbon dioxide (CO2) on benthic marine communities are largely unknown. We investigated in situ the consequences of long-term exposure to high CO2 on coral-reef-associated macroinvertebrate communities around three shallow volcanic CO2 seeps in Papua New Guinea. The densities of many groups and the number of taxa (classes and phyla) of macroinvertebrates were significantly reduced at elevated CO2 (425–1100 µatm) compared with control sites. However, sensitivities of some groups, including decapod crustaceans, ascidians and several echinoderms, contrasted with predictions of their physiological CO2 tolerances derived from laboratory experiments. High CO2 reduced the availability of structurally complex corals that are essential refugia for many reef-associated macroinvertebrates. This loss of habitat complexity was also associated with losses in many macroinvertebrate groups, especially predation-prone mobile taxa, including crustaceans and crinoids. The transition from living to dead coral as substratum and habitat further altered macroinvertebrate communities, with far more taxa losing than gaining in numbers. Our study shows that indirect ecological effects of OA (reduced habitat complexity) will complement its direct physiological effects and together with the loss of coral cover through climate change will severely affect macroinvertebrate communities in coral reefs. PMID:24307670

Carbon dioxide emissions from vegetation-kill zones around the resurgent dome of Long Valley caldera, eastern California, USA

USGS Publications Warehouse

Bergfeld, Deborah; Evans, William C.; Howle, James F.; Farrar, Christopher D.

2006-01-01

A survey of diffuse CO2 efflux, soil temperature and soil-gas chemistry over areas of localized vegetation-kill on and around the resurgent dome of Long Valley caldera California was performed to evaluate the premise that gaseous and thermal anomalies are related to renewed intrusion of magma. Some kill sites are long-lived features and others have developed in the past few years. Total anomalous CO2 emissions from the thirteen areas average around 8.7 t per day; but the majority of the emissions come from four sites west of the Casa Diablo geothermal power plant. Geochemical analyses of the soil-gases from locations west and east of the plant revealed the presence of isobutane related to plant operations. The δ13C values of diffuse CO2 range from − 5.7‰ to − 3.4‰, similar to values previously reported for CO2 from hot springs and thermal wells around Long Valley.At many of the vegetation-kill sites soil temperatures reach boiling at depths ≤ 20 cm. Soil temperature/depth profiles at two of the high-emissions areas indicate that the conductive thermal gradient in the center of the areas is around 320 °C m− 1. We estimate total heat loss from the two areas to be about 6.1 and 2.3 MW. Given current thinking on the rate of hydrothermal fluid flow across the caldera and using the CO2 concentration in the thermal fluids, the heat and CO2 loss from the kill areas is easily provided by the shallow hydrothermal system, which is sourced to the west of the resurgent dome. We find no evidence that the development of new areas of vegetation kill across the resurgent dome are related to new input of magma or magmatic fluids from beneath the resurgent dome. Our findings indicate that the areas have developed as a response to changes in the shallow hydrologic system. Some of the changes are likely related to fluid production at the power plant, but at distal sites the changes are more likely related to seismicity and uplift of the dome.

Rapid detection and characterization of surface CO2 leakage through the real-time measurement of δ13C signatures in CO2 flux from the ground

NASA Astrophysics Data System (ADS)

Krevor, Samuel; Benson, Sally; Rella, Chris; Perrin, Jean-Christophe; Esposito, Ariel; Crosson, Eric

2010-05-01

The surface monitoring of CO2 over geologic sequestration sites will be an essential tool in the monitoring and verification of sequestration projects. Surface monitoring is the only tool that currently provides the opportunity to detect and quantify leakages on the order of 1000 tons/year CO2. Near-surface detection and quantification can be made complicated, however, due to large temporal and spatial variations in natural background CO2 fluxes from biological processes. In addition, current surface monitoring technologies, such as the use of IR spectroscopy in eddy covariance towers and aerial surveys, radioactive or noble gas isotopic tracers, and flux chamber gas measurements can generally accomplish one or two of the necessary tasks of leak detection, identification, and quantification, at both large spatial scales and high spatial resolution. It would be useful, however, to combine the utility of these technologies so that a much simplified surface monitoring program can be deployed. Carbon isotopes of CO2 provide an opportunity to distinguish between natural biogenic CO2 fluxes from the ground and CO2 leaking from a sequestration reservoir that has ultimate origins in a process giving it a distinct isotopic signature such as natural gas processing. Until recently, measuring isotopic compositions of gases was a time-consuming and expensive process utilizing mass-spectrometry, not practical for deployment in a high-resolution survey of a potential leakage site at the surface. Recent developments in commercially available instruments utilizing wavelength scanned cavity ringdown spectroscopy (WS-CRDS) and Fourier transform infrared spectroscopy (FT-IR) have made it possible to rapidly measure the isotopic composition of gases including the 13C and 12C isotopic composition of CO2 in a field setting. A portable stable carbon isotope ratio analyzer for carbon dioxide, based on wavelength scanned cavity ringdown spectroscopy, has been used to rapidly detect and characterize an intentional leakage of CO2 from an underground pipeline at the ZERT experimental facility in Bozeman, Montana. Rapid ( 1 hour) walking surveys of the entire 100m x 100m site were collected using this mobile, real-time instrument. The resulting concentration and 13C isotopic abundance maps were processed using simple yet powerful analysis techniques, permitting not only the identification of specific leakage locations, but providing the ability to distinguish petrogenic sources of CO2 from biogenic sources. At the site an approximately 100-meter horizontal well has been drilled below an alfalfa field at a depth between 1-3 meters below the surface. The well has perforations along the central 70 meters of the well. The overlying strata are highly permeable sand, silt, and topsoil. For 30 days starting July 15, 2009, CO2 was injected at a rate of 0.2 tonnes per day. The injection rate is designed to simulate leakage from a mature storage reservoir at an annual rate of between .001 and .01%. The isotopic composition of the gas from the tank is at δ13C signature of approximately -52 parts per thousand (per mil), far more negative than either atmospheric (approx. -8 per mil) or CO2 from soil respiration (approx. -26 per mil) at the site. The CO2 isotopic and concentration measurements were taken with a Picarro WS-CRDS analyzer with 1/8' tubing connected to a sampling inlet. Simultaneous with CO2 concentrations (including 13C), position data was logged using a GPS receiver. Datapoints are taken around every second. The analyzer was powered using batteries and housed in a mobile cart. The surveys consisted of traverses of the site along the length of the pipeline and extending out 100 meters on either side of the pipeline with the end of the gas inlet tube approximate 9 cm above the ground at a speed of 1-2m/sec. This simulates the type of survey that could be easily performed if the actual or potential site of a leak was known to within an area on the order of 100 square kilometers or less, the scale of expected industrial CO2 sequestration operations. The surveys were performed both during the day and during the evening when CO2 flux due to respiration from the soil is markedly different. Keeling plots were used to characterize the spatially varying 13C composition of ground source CO2 across the site. A map constructed from this data shows that CO2 flux from sources of leakage was characterized by a δ13C of -40 per mil or less whereas locations away from the leakage spots had much higher δ13C signatures, -25 per mil or higher. The distinct isotopic signature allows for a clear discernment between leakage of petrogenic CO2 and that of natural CO2 fluxes from soil respiration. This is particularly valuable in the circumstance where the leak is slow enough that it could not be identified from CO2 concentration or flux changes above the natural background signal alone. Moreover, this detection took place both rapidly and at high spatial resolution. Samples collected from a mobile platform moving at the rate and with the sampling frequency used in this study could provide a 1000 km of survey traverses over an area of 100 km2 within 2-3 weeks. This provides a powerful tool for surface monitoring, combining the utilities of leak detection, characterization, and source identification with rapid deployment across large spatial scales and high spatial resolutions.

Diffuse degassing at Longonot volcano, Kenya: Implications for CO2 flux in continental rifts

NASA Astrophysics Data System (ADS)

Robertson, Elspeth; Biggs, Juliet; Edmonds, Marie; Clor, Laura; Fischer, Tobias P.; Vye-Brown, Charlotte; Kianji, Gladys; Koros, Wesley; Kandie, Risper

2016-11-01

Magma movement, fault structures and hydrothermal systems influence volatile emissions at rift volcanoes. Longonot is a Quaternary caldera volcano located in the southern Kenyan Rift, where regional extension controls recent shallow magma ascent. Here we report the results of a soil carbon dioxide (CO2) survey in the vicinity of Longonot volcano, as well as fumarolic gas compositions and carbon isotope data. The total non-biogenic CO2 degassing is estimated at < 300 kg d- 1, and is largely controlled by crater faults and fractures close to the summit. Thus, recent volcanic structures, rather than regional tectonics, control fluid pathways and degassing. Fumarolic gases are characterised by a narrow range in carbon isotope ratios (δ13C), from - 4.7‰ to - 6.4‰ (vs. PDB) suggesting a magmatic origin with minor contributions from biogenic CO2. Comparison with other degassing measurements in the East African Rift shows that records of historical eruptions or unrest do not correspond directly to the magnitude of CO2 flux from volcanic centres, which may instead reflect the current size and characteristics of the subsurface magma reservoir. Interestingly, the integrated CO2 flux from faulted rift basins is reported to be an order of magnitude higher than that from any of the volcanic centres for which CO2 surveys have so far been reported.

Adaptation and acclimatization to ocean acidification in marine ectotherms: an in situ transplant experiment with polychaetes at a shallow CO2 vent system

PubMed Central

Calosi, Piero; Rastrick, Samuel P. S.; Lombardi, Chiara; de Guzman, Heidi J.; Davidson, Laura; Jahnke, Marlene; Giangrande, Adriana; Hardege, Jörg D.; Schulze, Anja; Spicer, John I.; Gambi, Maria-Cristina

2013-01-01

Metabolic rate determines the physiological and life-history performances of ectotherms. Thus, the extent to which such rates are sensitive and plastic to environmental perturbation is central to an organism's ability to function in a changing environment. Little is known of long-term metabolic plasticity and potential for metabolic adaptation in marine ectotherms exposed to elevated pCO2. Consequently, we carried out a series of in situ transplant experiments using a number of tolerant and sensitive polychaete species living around a natural CO2 vent system. Here, we show that a marine metazoan (i.e. Platynereis dumerilii) was able to adapt to chronic and elevated levels of pCO2. The vent population of P. dumerilii was physiologically and genetically different from nearby populations that experience low pCO2, as well as smaller in body size. By contrast, different populations of Amphiglena mediterranea showed marked physiological plasticity indicating that adaptation or acclimatization are both viable strategies for the successful colonization of elevated pCO2 environments. In addition, sensitive species showed either a reduced or increased metabolism when exposed acutely to elevated pCO2. Our findings may help explain, from a metabolic perspective, the occurrence of past mass extinction, as well as shed light on alternative pathways of resilience in species facing ongoing ocean acidification. PMID:23980245

Adaptation and acclimatization to ocean acidification in marine ectotherms: an in situ transplant experiment with polychaetes at a shallow CO2 vent system.

PubMed

Calosi, Piero; Rastrick, Samuel P S; Lombardi, Chiara; de Guzman, Heidi J; Davidson, Laura; Jahnke, Marlene; Giangrande, Adriana; Hardege, Jörg D; Schulze, Anja; Spicer, John I; Gambi, Maria-Cristina

2013-01-01

Metabolic rate determines the physiological and life-history performances of ectotherms. Thus, the extent to which such rates are sensitive and plastic to environmental perturbation is central to an organism's ability to function in a changing environment. Little is known of long-term metabolic plasticity and potential for metabolic adaptation in marine ectotherms exposed to elevated pCO2. Consequently, we carried out a series of in situ transplant experiments using a number of tolerant and sensitive polychaete species living around a natural CO2 vent system. Here, we show that a marine metazoan (i.e. Platynereis dumerilii) was able to adapt to chronic and elevated levels of pCO2. The vent population of P. dumerilii was physiologically and genetically different from nearby populations that experience low pCO2, as well as smaller in body size. By contrast, different populations of Amphiglena mediterranea showed marked physiological plasticity indicating that adaptation or acclimatization are both viable strategies for the successful colonization of elevated pCO2 environments. In addition, sensitive species showed either a reduced or increased metabolism when exposed acutely to elevated pCO2. Our findings may help explain, from a metabolic perspective, the occurrence of past mass extinction, as well as shed light on alternative pathways of resilience in species facing ongoing ocean acidification.

Capturing Postseismic Processes of the 2016 Mw 7.1 Kumamoto Earthquake, Japan, Using Dense, Continuous GPS and Short-repeat Time ALOS-2 InSAR Data: Implications for the Shallow Slip Deficit Problem

NASA Astrophysics Data System (ADS)

Milliner, C. W. D.; Burgmann, R.; Wang, T.; Inbal, A.; Bekaert, D. P.; Liang, C.; Fielding, E. J.

2017-12-01

Separating the contribution of shallow coseismic slip from rapidly decaying, postseismic afterslip in surface rupturing events has been difficult to resolve due to the typically sparse configuration of GPS networks and long-repeat time of InSAR acquisitions. Whether shallow fault motion along surface ruptures is a result of coseismic slip, or largely a product of rapid afterslip occurring within the first minutes to days, has significant implications for our understanding of the mechanics and frictional behavior of faulting in the shallow crust. To test this behavior in the case of a major surface rupturing event, we attempt to quantify the co- and postseismic slip of the 2016 Mw 7.1 Kumamoto earthquake sequence using a dense and continuous GPS network ( 10 km spacing), with short-repeat time, ALOS-2 InSAR data. Using the Network Inversion Filter method, we jointly invert the GPS and InSAR data to obtain a time history of afterslip in the first minutes to months following the mainshock. From our initial results, we find no clear evidence of significant shallow afterslip (i.e., no observable slip > 30 cm at depths of < 3 km, a minimum resolvable value), that could account for the 1 m of coseismic deficit of shallow slip inferred from our static finite-fault inversion. Our results show, aside from significant volumetric changes related to poroelastic processes, the majority of shallow fault slip was largely complete after rupture cessation. We also attempt to improve our coseismic slip model by implementing a method that inverts changes in seismicity rates for coseismic slip, helping constrain parts of the model space at depth where geodetic data loses resolving power. The use of geodetic data with the ability to resolve near-field, coseismic deformation and rapidly decaying postseismic processes will aid in our understanding of the frictional properties of shallow faulting, giving more reliable predictions for ground motion simulations and seismic hazard assessments.

Ocean acidification accelerates dissolution of experimental coral reef communities

NASA Astrophysics Data System (ADS)

Comeau, S.; Carpenter, R. C.; Lantz, C. A.; Edmunds, P. J.

2015-01-01

Ocean acidification (OA) poses a severe threat to tropical coral reefs, yet much of what is know about these effects comes from individual corals and algae incubated in isolation under high pCO2. Studies of similar effects on coral reef communities are scarce. To investigate the response of coral reef communities to OA, we used large outdoor flumes in which communities composed of calcified algae, corals, and sediment were combined to match the percentage cover of benthic communities in the shallow back reef of Moorea, French Polynesia. Reef communities in the flumes were exposed to ambient (~ 400 μatm) and high pCO2 (~ 1300 μatm) for 8 weeks, and calcification rates measured for the constructed communities including the sediments. Community calcification was reduced by 59% under high pCO2, with sediment dissolution explaining ~ 50% of this decrease; net calcification of corals and calcified algae remained positive but was reduced by 29% under elevated pCO2. These results show that, despite the capacity of coral reef calcifiers to maintain positive net accretion of calcium carbonate under OA conditions, reef communities might transition to net dissolution as pCO2 increases, particularly at night, due to enhanced sediment dissolution.

Ocean acidification accelerates dissolution of experimental coral reef communities

NASA Astrophysics Data System (ADS)

Comeau, S.; Carpenter, R. C.; Lantz, C. A.; Edmunds, P. J.

2014-08-01

Ocean acidification (OA) poses a severe threat to tropical coral reefs, yet much of what is know about these effects comes from individual corals and algae incubated in isolation under high pCO2. Studies of similar effects on coral reef communities are scarce. To investigate the response of coral reef communities to OA, we used large outdoor flumes in which communities composed of calcified algae, corals, and sediment were combined to match the percentage cover of benthic communities in the shallow back reef of Moorea, French Polynesia. Reef communities in the flumes were exposed to ambient (~400 μatm) and high pCO2 (~1300 μatm) for 8 weeks, and calcification rates measured for the constructed communities including the sediments. Community calcification was depressed 59% under high pCO2, with sediment dissolution explaining ~50% of this decrease; net calcification of corals and calcified algae remained positive, but was reduced 29% under elevated pCO2. These results show that despite the capacity of coral reef calcifiers to maintain positive net accretion of calcium carbonate under OA conditions, reef communities might switch to net dissolution as pCO2 increases, particularly at night, due to enhanced sediment dissolution.

Hydrogeochemical and mineralogical effects of sustained CO2 contamination in a shallow sandy aquifer: A field-scale controlled release experiment

NASA Astrophysics Data System (ADS)

Cahill, Aaron G.; Marker, Pernille; Jakobsen, Rasmus

2014-02-01

A shallow aquifer CO2 contamination experiment was performed to investigate evolution of water chemistry and sediment alteration following leakage from geological storage by physically simulating a leak from a hypothetical storage site. In a carbonate-free aquifer, in western Denmark, a total of 1600 kg of gas phase CO2 was injected at 5 and 10 m depth over 72 days through four inclined injection wells into aeolian and glacial sands. Water chemistry was monitored for pH, EC, and dissolved element evolution through an extensive network of multilevel sampling points over 305 days. Sediment cores were taken pre and postinjection and analyzed to search for effects on mineralogy and sediment properties. Results showed the simulated leak to evolve in two distinct phases; an advective elevated ion pulse followed by increasing persistent acidification. Spatial and temporal differences in evolution of phases suggest separate chemical mechanisms and geochemical signatures. Dissolved element concentrations developed exhibiting four behaviors: (1) advective pulse (Ca, Mg, Na, Si, Ba, and Sr), (2) pH sensitive abundance dependent (Al and Zn), (3) decreasing (Mn and Fe), and (4) unaffected (K). Concentration behaviors were characterized by: (1) a maximal front moving with advective flow, (2) continual increase in close proximity to the injection plane, (3) removal from solution, and (4) no significant change. Only Al was observed to exceed WHO guidelines, however significantly so (10-fold excess). The data indicate that pH is controlled by equilibrium with gibbsite which is again coupled to cation exchange processes. Pre and postinjection sediment analysis indicated alteration of sediment composition and properties including depletion of reactive mineral species.

Isotopic identification of the source of methane in subsurface sediments of an area surrounded by waste disposal facilities

USGS Publications Warehouse

Hackley, Keith C.; Liu, Chao-Li; Trainor, D.

1999-01-01

The major source of methane (CH4) in subsurface sediments on the property of a former hazardous waste treatment facility was determined using isotopic analyses measured on CH4 and associated groundwater. The site, located on an earthen pier built into a shallow wetland lake, has had a history of waste disposal practices and is surrounded by landfills and other waste management facilities. Concentrations of CH4 up to 70% were found in the headspace gases of several piezometers screened at 3 different depths (ranging from 8 to 17 m) in lacustrine and glacial till deposits. Possible sources of the CH4 included a nearby landfill, organic wastes from previous impoundments and microbial gas derived from natural organic matter in the sediments. Isotopic analyses included ??13C, ??D, 14C, and 3H on select CH4 samples and ??D and ??18O on groundwater samples. Methane from the deepest glacial till and intermediate lacustrine deposits had ??13C values from -79 to -82???, typical of natural 'drift gas' generated by microbial CO2-reduction. The CH4 from the shallow lacustrine deposits had ??13C values from -63 to -76???, interpreted as a mixture between CH4 generated by microbial fermentation and the CO2-reduction processes within the subsurface sediments. The ??D values of all the CH4 samples were quite negative ranging from -272 to -299???. Groundwater sampled from the deeper zones also showed quite negative ??D values that explained the light ??D observed for the CH4. Radiocarbon analyses of the CH4 showed decreasing 14C activity with depth, from a high of 58 pMC in the shallow sediments to 2 pMC in the deeper glacial till. The isotopic data indicated the majority of CH4 detected in the fill deposits of this site was microbial CH4 generated from naturally buried organic matter within the subsurface sediments. However, the isotopic data of CH4 from the shallow piezometers was more variable and the possibility of some mixing with oxidized landfill CH4 could not be completely ruled out.

Volatile emissions from the crater and flank of Oldoinyo Lengai volcano, Tanzania

USGS Publications Warehouse

Koepenick, K.W.; Brantley, S.L.; Thompson, J.M.; Rowe, G.L.; Nyblade, A.A.; Moshy, C.

1996-01-01

As a comparison to airborne infrared (IR) flux measurements, ground-based sampling of fumarole and soil gases was used to characterize the quiescent degassing of CO2 from Oldoinyo Lengai volcano. Aerial and ground-based measurements are in good agreement: ???75% of the aerially measured CO2 flux at Lengai (0.05-0.06 ?? 1012 mol yr-1 or 6000-7200 tonnes CO2 d-1) can be attributed to seven large crater vents. In contrast to Etna and Vulcano Island, where 15-50% of the total CO2 flux emanates diffusely through the volcanic flanks, diffuse emissions were measured only within 500 m of the crater rim at Lengai, contributing < 2% of the total flux. The lack of extensive flank emissions may reflect the dimensions of the magma chamber and/or the lack of a shallow fluid flow system. Thermodynamic restoration of fumarole analyses shows that gases are the most CO2-rich and H2O-poor reported for any volcano, containing 64-74% CO2, 24-34% H2O, 0.88-1.0% H2, 0.1-0.4% CO and < 0.1% H2S, HCl, HF, and CH4. Volatile emissions of S, Cl, and F at Oldoiyno Lengai are estimated as 4.5, 1.5, and 1.0 ?? 107 mol yr-1, respectively. Accuracy of the airborne technique was also assessed by measuring the C emission rate from a coal-burning power plant. CO2 fluxes were measured within ??10% near the plant; however, poor resolution at increased distances caused an underestimation of the flux by a factor of 2. The relatively large CO2 fluxes measured for alkaline volcanoes such as Oldoinyo Lengai or Etna may indicate that midplate volcanoes represent a large, yet relatively unknown, natural source of CO2.

Carbon dioxide dynamics in a lake and a reservoir on a tropical island (Bali, Indonesia).

PubMed

Macklin, Paul A; Suryaputra, I Gusti Ngurah Agung; Maher, Damien T; Santos, Isaac R

2018-01-01

Water-to-air carbon dioxide fluxes from tropical lakes and reservoirs (artificial lakes) may be an important but understudied component of global carbon fluxes. Here, we investigate the seasonal dissolved carbon dioxide (CO2) dynamics in a lake and a reservoir on a tropical volcanic island (Bali, Indonesia). Observations were performed over four seasonal surveys in Bali's largest natural lake (Lake Batur) and largest reservoir (Palasari Reservoir). Average CO2 partial pressures in the natural lake and reservoir were 263.7±12.2 μatm and 785.0±283.6 μatm respectively, with the highest area-weighted partial pressures in the wet season for both systems. The strong correlations between seasonal mean values of dissolved oxygen (DO) and pCO2 in the natural lake (r2 = 0.92) suggest that surface water metabolism was an important driver of CO2 dynamics in this deep system. Radon (222Rn, a natural groundwater discharge tracer) explained up to 77% of the variability in pCO2 in the shallow reservoir, suggesting that groundwater seepage was the major CO2 driver in the reservoir. Overall, the natural lake was a sink of atmospheric CO2 (average fluxes of -2.8 mmol m-2 d-1) while the reservoir was a source of CO2 to the atmosphere (average fluxes of 7.3 mmol m-2 d-1). Reservoirs are replacing river valleys and terrestrial ecosystems, particularly throughout developing tropical regions. While the net effect of this conversion on atmospheric CO2 fluxes remains to be resolved, we speculate that reservoir construction will partially offset the CO2 sink provided by deep, volcanic, natural lakes and terrestrial environments.

Study of CO2 bubble dynamics in seawater from QICS field Experiment

NASA Astrophysics Data System (ADS)

Chen, B.; Dewar, M.; Sellami, N.; Stahl, H.; Blackford, J.

2011-12-01

One of the concerns of employing CCS at engineering scale is the risk of leakage of storage CO2 on the environment and especially on the marine life. QICS, a scientific research project was launched with an aim to study the effects of a potential leak from a CCS system on the UK marine environment [1]. The project involves the injection of CO2 from a shore-based lab into shallow marine sediments. One of the main objectives of the project is to generate experimental data to be compared with the developed physical models. The results of the models are vital for the biogeochemical and ecological models in order to predict the impact of a CO2 leak in a variety of situations. For the evaluation of the fate of the CO2 bubbles into the surrounding seawater, the physical model requires two key parameters to be used as input which are: (i) a correlation of the drag coefficient as function of the CO2 bubble Reynolds number and (ii) the CO2 bubble size distribution. By precisely measuring the CO2 bubble size and rising speed, these two parameters can be established. For this purpose, the dynamical characteristics of the rising CO2 bubbles in Scottish seawater were investigated experimentally within the QICS project. Observations of the CO2 bubbles plume rising freely in the in seawater column were captured by video survey using a ruler positioned at the leakage pockmark as dimension reference. This observation made it possible, for the first time, to discuss the dynamics of the CO2 bubbles released in seawater. [1] QICS, QICS: Quantifying and Monitoring Potential Ecosystem Impacts of Geological Carbon Storage. (Accessed 15.07.13), http://www.bgs.ac.uk/qics/home.html

Study of CO2 bubble dynamics in seawater from QICS field Experiment

NASA Astrophysics Data System (ADS)

Chen, B.; Dewar, M.; Sellami, N.; Stahl, H.; Blackford, J.

2013-12-01

One of the concerns of employing CCS at engineering scale is the risk of leakage of storage CO2 on the environment and especially on the marine life. QICS, a scientific research project was launched with an aim to study the effects of a potential leak from a CCS system on the UK marine environment [1]. The project involves the injection of CO2 from a shore-based lab into shallow marine sediments. One of the main objectives of the project is to generate experimental data to be compared with the developed physical models. The results of the models are vital for the biogeochemical and ecological models in order to predict the impact of a CO2 leak in a variety of situations. For the evaluation of the fate of the CO2 bubbles into the surrounding seawater, the physical model requires two key parameters to be used as input which are: (i) a correlation of the drag coefficient as function of the CO2 bubble Reynolds number and (ii) the CO2 bubble size distribution. By precisely measuring the CO2 bubble size and rising speed, these two parameters can be established. For this purpose, the dynamical characteristics of the rising CO2 bubbles in Scottish seawater were investigated experimentally within the QICS project. Observations of the CO2 bubbles plume rising freely in the in seawater column were captured by video survey using a ruler positioned at the leakage pockmark as dimension reference. This observation made it possible, for the first time, to discuss the dynamics of the CO2 bubbles released in seawater. [1] QICS, QICS: Quantifying and Monitoring Potential Ecosystem Impacts of Geological Carbon Storage. (Accessed 15.07.13), http://www.bgs.ac.uk/qics/home.html

Monitoring CO 2 sequestration into deep saline aquifer and associated salt intrusion using coupled multiphase flow modeling and time lapse electrical resistivity tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chuan Lu; CHI Zhang; Hai Hanag

2014-04-01

Successful geological storage and sequestration of carbon dioxide (CO2) require efficient monitoring of the migration of CO2 plume during and after large-scale injection in order to verify the containment of the injected CO2 within the target formation and to evaluate potential leakage risk. Field studies have shown that surface and cross-borehole electrical resistivity tomography (ERT) can be a useful tool in imaging and characterizing solute transport in heterogeneous subsurface. In this synthetic study, we have coupled a 3-D multiphase flow model with a parallel 3-D time-lapse ERT inversion code to explore the feasibility of using time-lapse ERT for simultaneously monitoringmore » the migration of CO2 plume in deep saline formation and potential brine intrusion into shallow fresh water aquifer. Direct comparisons of the inverted CO2 plumes resulting from ERT with multiphase flow simulation results indicate the ERT could be used to delineate the migration of CO2 plume. Detailed comparisons on the locations, sizes and shapes of CO2 plume and intruded brine plumes suggest that ERT inversion tends to underestimate the area review of the CO2 plume, but overestimate the thickness and total volume of the CO2 plume. The total volume of intruded brine plumes is overestimated as well. However, all discrepancies remain within reasonable ranges. Our study suggests that time-lapse ERT is a useful monitoring tool in characterizing the movement of injected CO2 into deep saline aquifer and detecting potential brine intrusion under large-scale field injection conditions.« less

Carbon Dioxide Effects under Conditions of Raised Environmental Pressure

DTIC Science & Technology

1974-12-26

mechanics of respiration and in particular, the behavior of the respiratory gases. Carbon dioxide plays a major role in the physiology of the...of respiratory limitations and associated COg retention when divers are performing heavy, exhaustive work. In shallow habitat air diving using...combinations of air and normoxic nitrogen-oxygen breathing mixtures, evidence for the development of slight respiratory acidosis and CO2 retention has

Fingerprinting captured CO2 using natural tracers: Determining CO2 fate and proving ownership

NASA Astrophysics Data System (ADS)

Flude, Stephanie; Gilfillan, Stuart; Johnston, Gareth; Stuart, Finlay; Haszeldine, Stuart

2016-04-01

In the long term, captured CO2 will most likely be stored in large saline formations and it is highly likely that CO2 from multiple operators will be injected into a single saline formation. Understanding CO2 behavior within the reservoir is vital for making operational decisions and often uses geochemical techniques. Furthermore, in the event of a CO2 leak, being able to identify the owner of the CO2 is of vital importance in terms of liability and remediation. Addition of geochemical tracers to the CO2 stream is an effective way of tagging the CO2 from different power stations, but may become prohibitively expensive at large scale storage sites. Here we present results from a project assessing whether the natural isotopic composition (C, O and noble gas isotopes) of captured CO2 is sufficient to distinguish CO2 captured using different technologies and from different fuel sources, from likely baseline conditions. Results include analytical measurements of CO2 captured from a number of different CO2 capture plants and a comprehensive literature review of the known and hypothetical isotopic compositions of captured CO2 and baseline conditions. Key findings from the literature review suggest that the carbon isotope composition will be most strongly controlled by that of the feedstock, but significant fractionation is possible during the capture process; oxygen isotopes are likely to be controlled by the isotopic composition of any water used in either the industrial process or the capture technology; and noble gases concentrations will likely be controlled by the capture technique employed. Preliminary analytical results are in agreement with these predictions. Comparison with summaries of likely storage reservoir baseline and shallow or surface leakage reservoir baseline data suggests that C-isotopes are likely to be valuable tracers of CO2 in the storage reservoir, while noble gases may be particularly valuable as tracers of potential leakage.

Feasibility of Autonomous Monitoring of CO2 Leakage in Aquifers: Results From Controlled Laboratory Experiments

NASA Astrophysics Data System (ADS)

Versteeg, R.; Leger, E.; Dafflon, B.

2016-12-01

Geologic sequestration of CO2 is one of the primary proposed approaches for reducing total atmospheric CO2 concentrations. MVAA (Monitoring, Verification, Accounting and Assessment) of CO2 sequestration is an essential part of the geologic CO2 sequestration cycle. MVAA activities need to meet multiple operational, regulatory and environmental objectives, including ensuring the protection of underground sources of drinking water. Anticipated negative consequences of CO2 leakage into groundwater, besides possible brine contamination and release of gaseous CO2, include a significant increase of dissolved CO2 into shallow groundwater systems, which will decrease groundwater pH and can potentially mobilize naturally occurring trace metals and ions that are commonly absorbed to or contained in sediments. Autonomous electrical geophysical monitoring in aquifers has the potential of allowing for rapid and automated detection of CO2 leakage. However, while the feasibility of such monitoring has been demonstrated by a number of different field experiments, automated interpretation of complex electrical resistivity data requires the development of quantitative relationships between complex electrical resistivity signatures and dissolved CO2 in the aquifer resulting from leakage Under a DOE SBIR funded effort we performed multiple tank scale experiments in which we investigated complex electrical resistivity signatures associated with dissolved CO2 plumes in saturated sediments. We also investigated the feasibility of distinguishing CO2 leakage signatures from signatures associated with other processes such as salt water movement, temperature variations and other variations in chemical or physical conditions. In addition to these experiments we also numerically modeled the tank experiments. These experiments showed that (a) we can distinguish CO2 leakage signatures from other signatures, (b) CO2 leakage signatures have a consistent characteristic, (c) laboratory experiments are in agreement with field results, and (d) we can numerically simulate the main characteristics of CO2 leakage and associated electrical geophysical signatures.

Compositional data analysis and geochemical modeling of CO2-water-rock interactions in three provinces of Korea.

PubMed

Kim, Seong Hee; Choi, Byoung-Young; Lee, Gyemin; Yun, Seong-Taek; Kim, Soon-Oh

2017-12-20

The CO 2 -rich spring water (CSW) occurring naturally in three provinces, Kangwon (KW), Chungbuk (CB), and Gyeongbuk (GB) of South Korea was classified based on its hydrochemical properties using compositional data analysis. Additionally, the geochemical evolution pathways of various CSW were simulated via equilibrium phase modeling (EPM) incorporated in the PHREEQC code. Most of the CSW in the study areas grouped into the Ca-HCO 3 water type, but some samples from the KW area were classified as Na-HCO 3 water. Interaction with anorthite is likely to be more important than interaction with carbonate minerals for the hydrochemical properties of the CSW in the three areas, indicating that the CSW originated from interactions among magmatic CO 2 , deep groundwater, and bedrock-forming minerals. Based on the simulation results of PHREEQC EPM, the formation temperatures of the CSW within each area were estimated as 77.8 and 150 °C for the Ca-HCO 3 and Na-HCO 3 types of CSW, respectively, in the KW area; 138.9 °C for the CB CSW; and 93.0 °C for the GB CSW. Additionally, the mixing ratios between simulated carbonate water and shallow groundwater were adjusted to 1:9-9:1 for the CSW of the GB area and the Ca-HCO 3 -type CSW of the KW area, indicating that these CSWs were more affected by carbonate water than by shallow groundwater. On the other hand, mixing ratios of 1:9-5:5 and 1:9-3:7 were found for the Na-HCO 3 -type CSW of the KW area and for the CSW of the CB area, respectively, suggesting a relatively small contribution of carbonate water to these CSWs. This study proposes a systematic, but relatively simple, methodology to simulate the formation of carbonate water in deep environments and the geochemical evolution of CSW. Moreover, the proposed methodology could be applied to predict the behavior of CO 2 after its geological storage and to estimate the stability and security of geologically stored CO 2 .

On the assimilation of SWOT type data into 2D shallow-water models

NASA Astrophysics Data System (ADS)

Frédéric, Couderc; Denis, Dartus; Pierre-André, Garambois; Ronan, Madec; Jérôme, Monnier; Jean-Paul, Villa

2013-04-01

In river hydraulics, assimilation of water level measurements at gauging stations is well controlled, while assimilation of images is still delicate. In the present talk, we address the richness of satellite mapped information to constrain a 2D shallow-water model, but also related difficulties. 2D shallow models may be necessary for small scale modelling in particular for low-water and flood plain flows. Since in both cases, the dynamics of the wet-dry front is essential, one has to elaborate robust and accurate solvers. In this contribution we introduce robust second order, stable finite volume scheme [CoMaMoViDaLa]. Comparisons of real like tests cases with more classical solvers highlight the importance of an accurate flood plain modelling. A preliminary inverse study is presented in a flood plain flow case, [LaMo] [HoLaMoPu]. As a first step, a 0th order data processing model improves observation operator and produces more reliable water level derived from rough measurements [PuRa]. Then, both model and flow behaviours can be better understood thanks to variational sensitivities based on a gradient computation and adjoint equations. It can reveal several difficulties that a model designer has to tackle. Next, a 4D-Var data assimilation algorithm used with spatialized data leads to improved model calibration and potentially leads to identify river discharges. All the algorithms are implemented into DassFlow software (Fortran, MPI, adjoint) [Da]. All these results and experiments (accurate wet-dry front dynamics, sensitivities analysis, identification of discharges and calibration of model) are currently performed in view to use data from the future SWOT mission. [CoMaMoViDaLa] F. Couderc, R. Madec, J. Monnier, J.-P. Vila, D. Dartus, K. Larnier. "Sensitivity analysis and variational data assimilation for geophysical shallow water flows". Submitted. [Da] DassFlow - Data Assimilation for Free Surface Flows. Computational software http://www-gmm.insa-toulouse.fr/~monnier/DassFlow/ [HoLaMoPu] R. Hostache, X. Lai, J. Monnier, C. Puech. "Assimilation of spatial distributed water levels into a shallow-water flood model. Part II: using a remote sensing image of Mosel river". J. Hydrology (2010). [LaMo] X. Lai, J. Monnier. "Assimilation of spatial distributed water levels into a shallow-water flood model. Part I: mathematical method and test case". J. Hydrology (2009). [PuRa] C. Puech, D. Raclot. "Using geographic information systems and aerial photographs to determine water levels during floods". Hydrol. Process., 16, 1593 - 1602, (2002). [RoDa] H. Roux, D. Dartus. "Use of Parameter Optimization to Estimate a Flood Wave: Potential Applications to Remote Sensing of Rivers". J. Hydrology (2006).

Modulation of magmatic processes by carbon dioxide

NASA Astrophysics Data System (ADS)

Caricchi, L.; Sheldrake, T. E.; Blundy, J. D.

2017-12-01

Volatile solubility in magmas increases with pressure, although the solubility of CO2 is much lower than that of H2O. Consequently, magmas rising from depth release CO2-rich fluids, which inevitably interact with H2O-poor magmas in the upper crust (CO2-flushing). CO2-flushing triggers the exsolution of H2O-rich fluids, leading to an increase of volume and magma crystallisation. While the analyses of eruptive products demonstrates that this process operates in virtually all magmatic system, its impact on magmatic and volcanic processes has not been quantified. Here we show that depending on the initial magma crystallinity, and the depth of magma storage, CO2-flushing can lead to volcanic eruptions or promote conditions that favour the impulsive release of mineralising fluids. Our calculations show that the interaction between a few hundred ppm of carbonic fluids, and crystal-poor magmas stored at shallow depths, produces rapid pressurisation that can potentially lead to an eruption. Further addition of CO2 increases magma compressibility and crystallinity, reducing the potential for volcanic activity, promoting the formation of ore deposits. Increasing the depth of fluid-magma interaction dampens the impact of CO2-flushing on the pressurisation of a magma reservoir. CO2-flushing may result in surface inflation and increases in surface CO2 fluxes, which are commonly considered signs of an impending eruption, but may not necessarily result in eruption depending on the initial crystallnity and depth of the magmatic reservoir. We propose that CO2-flushing is a powerful agent modulating the pressurisation of magma reservoirs and the release of mineralising fluids from upper crustal magma reservoirs.

4-D High-Resolution Seismic Reflection Monitoring of Miscible CO2 Injected into a Carbonate Reservoir

DOE Office of Scientific and Technical Information (OSTI.GOV)

Richard D. Miller; Abdelmoneam E. Raef; Alan P. Byrnes

2005-09-01

The objective of this research project is to acquire, process, and interpret multiple high-resolution 3-D compressional wave and 2-D, 2-C shear wave seismic data to observe changes in fluid characteristics in an oil field before, during, and after the miscible carbon dioxide (CO{sub 2}) flood that began around December 1, 2003, as part of the DOE-sponsored Class Revisit Project (DOE DE-AC26-00BC15124). Unique and key to this imaging activity is the high-resolution nature of the seismic data, minimal deployment design, and the temporal sampling throughout the flood. The 900-m-deep test reservoir is located in central Kansas oomoldic limestones of the Lansing-Kansasmore » City Group, deposited on a shallow marine shelf in Pennsylvanian time. After 18 months of seismic monitoring, one baseline and six monitor surveys clearly imaged changes that appear consistent with movement of CO{sub 2} as modeled with fluid simulators.« less

Monitoring of environmental influences on seismic velocity at the geological storage site for CO2 in Ketzin (Germany) with ambient seismic noise

NASA Astrophysics Data System (ADS)

Gassenmeier, M.; Sens-Schönfelder, C.; Delatre, M.; Korn, M.

2015-01-01

Regarding the exploitation of natural resources, storage of waste or subsurface construction, there is an increasing need to obtain comprehensive knowledge about the subsurface and its temporal changes. We investigate the possibility of a passive monitoring using ambient seismic noise, which is cheap and continuous compared to active seismics. We work with data acquired with a seismic network in Ketzin (Germany) where 67 271 tons of CO2 were injected from 2008 June until 2013 August into a saline aquifer at a depth of about 650 m. Monitoring the expansion of the CO2 plume is essential for the characterization of the reservoir as well as the detection of potential leakage. By cross-correlating about 4 yr of passive seismic data in a frequency range of 0.05-4.5 Hz we found periodic velocity variations with a period of approximately 1 yr that cannot be caused by the CO2 injection. The prominent direction of the noise wavefield indicates a wind farm as the dominant source providing the temporally stable noise field. This spacial stability excludes variations of the noise source distribution as a cause of spurious velocity variations. Based on an amplitude decrease associated with time windows towards later parts of the coda, we show that the variations must be generated in the shallow subsurface. A comparison to groundwater level data reveals a direct correlation between depth of the groundwater level and the seismic velocity. The influence of ground frost on the seismic velocities is documented by a sharp increase of velocity when the maximum daily temperature stays below 0 °C. Although the observed periodic changes and the changes due to ground frost affect only the shallow subsurface, they mask potential signals of material changes from the reservoir depths.

Effective CO2 sequestration monitoring using joint inversion result of seismic and electromagnetic data

NASA Astrophysics Data System (ADS)

Noh, K.; Jeong, S.; Seol, S. J.; Byun, J.; Kwon, T.

2015-12-01

Man-made carbon dioxide (CO2) released into the atmosphere is a significant contributor to the greenhouse gas effect and related global warming. Sequestration of CO2 into saline aquifers has been proposed as one of the most practical options of all geological sequestration possibilities. During CO2 geological sequestration, monitoring is indispensable to delineate the change of CO2 saturation and migration of CO2 in the subsurface. Especially, monitoring of CO2 saturation in aquifers provides useful information for determining amount of injected CO2. Seismic inversion can provide the migration of CO2 plume with high resolution because velocity is reduced when CO2 replaces the pore fluid during CO2 injection. However, the estimation of CO2 saturation using the seismic method is difficult due to the lower sensitivity of the velocity to the saturation when the CO2 saturation up to 20%. On the other hand, marine controlled-source EM (mCSEM) inversion is sensitive to the resistivity changes resulting from variations in CO2 saturation, even though it has poor resolution than seismic method. In this study, we proposed an effective CO2 sequestration monitoring method using joint inversion of seismic and mCSEM data based on a cross-gradient constraint. The method was tested with realistic CO2 injection models in a deep brine aquifer beneath a shallow sea which is selected with consideration for the access convenience for the installation of source and receiver and an environmental safety. Resistivity images of CO2 plume by the proposed method for different CO2 injection stages have been significantly improved over those obtained from individual EM inversion. In addition, we could estimate a reliable CO2 saturation by rock physics model (RPM) using the P-wave velocity and the improved resistivity. The proposed method is a basis of three-dimensional estimation of reservoir parameters such as porosity and fluid saturation, and the method can be also applied for detecting a reservoir and calculating the accurate oil and gas reserves.

Factors mediating co-occurrence of an economically valuable introduced fish and its native frog prey.

PubMed

Hartman, Rosemary; Pope, Karen; Lawler, Sharon

2014-06-01

Habitat characteristics mediate predator-prey coexistence in many ecological systems but are seldom considered in species introductions. When economically important introduced predators are stocked despite known negative impacts on native species, understanding the role of refuges, landscape configurations, and community interactions can inform habitat management plans. We measured these factors in basins with introduced trout (Salmonidae) and the Cascades frog (Rana cascadae) to determine, which are responsible for observed patterns of co-occurrence of this economically important predator and its native prey. Large, vegetated shallows were strongly correlated to co-occurrence, and R. cascadae larvae occur in shallower water when fish are present, presumably to escape predation. The number of nearby breeding sites of R. cascadae was also correlated to co-occurrence, but only when the western toad (Anaxyrus boreas) was present. Because A. boreas larvae are unpalatable to fish and resemble R. cascadae, they may provide protection from trout via Batesian mimicry. Although rescue-effect dispersal from nearby populations may maintain co-occurrence, within-lake factors proved more important for predicting co-occurrence. Learning which factors allow co-occurrence between economically important introduced species and their native prey enables managers to make better-informed stocking decisions. © 2013 Society for Conservation Biology.

Simulation of cosmic irradiation conditions in thick target arrangements

NASA Technical Reports Server (NTRS)

Theis, S.; Englert, P.; Reedy, R. C.; Arnold, J. R.

1986-01-01

One approach to simulate 2-pi irradiation conditions of planetary surfaces which has been widely applied in the past are bombardments of so called thick targets. A very large thick target was exposed recently to 2.1 GeV protons at the Bevatron-Bevalac in Berkeley. In a 100x100x180 cm steel-surrounded granodiorite target radioactive medium and high energy spallation products of the incident primary and of secondary particles were analyzed along the beam axis down to depths of 140 g/cm(2) in targets such as Cu, Ni, Co, Fe, T, Si, SiO2 and Al. Activities of these nuclides were exclusively determined via instrumental gamma-ray spectroscopy. Relative yields of neutron capture and spallation products induced in Co and Cu targets during the thick target bombardment are shown as a function of depth. The majority of the medium energy products such as Co-58 from Co targets exhibit a maximum at shallow depths of 40-60 g/cm(2) and then decrease exponentially. In a comparable 600 MeV proton bombarded thick target such a slight maximum for medium energy products was not observed. Rather, Co-58 activities in Co decreased steadily with the highest activity at the surface. The activities of the n-capture product Co-60 increase steadily starting at the surface. This indicates the rapidly growing flux of low energy neutrons within the target.

Geologic Storage of CO2: Leakage Pathways and Environmental Risks

NASA Astrophysics Data System (ADS)

Celia, M. A.; Peters, C. A.; Bachu, S.

2002-05-01

Geologic storage of CO2 appears to be an attractive option for carbon mitigation because it offers sufficient capacity to solve the problem, and it can be implemented with existing technology. Among the list of options for storage sites, depleted hydrocarbon reservoirs and deep saline aquifers are two major categories. While injection into hydrocarbon reservoirs offers immediate possibilities, especially in the context of enhanced oil recovery, it appears that deep saline aquifers provide the extensive capacity necessary to solve the problem over the decade to century time scale. Capacity and technology argue favorably for this option, but remaining obstacles to implementation include capture technologies, overall economic considerations, and potential environmental consequences of the injection. Of these, the environmental questions may be most difficult to solve. Experience from CO2 floods for enhanced oil recovery and from CO2 and acid gas disposal operations indicates that geological storage of CO2 is safe over the short term for comparatively small amounts of CO2. However, there is no experience to date regarding the long-term fate and safety of the large volumes of CO2 that must be injected to significantly reduce atmospheric emissions. In order to make proper evaluation of environmental risks, the full range of possible environmental consequences must be considered. Most of these environmental concerns involve migration and leakage of CO2 into shallow portions of the subsurface and eventually into the atmosphere. In shallow subsurface zones, elevated levels of carbon dioxide can cause pH changes, leading to possible mobilization of ground-water contaminants including metals. In the unsaturated zone, vegetation can be adversely affected, as can other ecosystem components. At the land surface, elevated levels of CO2 can lead to asphyxiation in humans and other animals. And finally, in the atmosphere, CO2 that leaks from underground diminishes the effectiveness of the overall storage scheme and contributes to possible climate change. To characterize these environmental consequences, reliable models of leakage characteristics and rates are needed. While leakage through natural flowpaths in the subsurface may occur, a more likely pathway is leakage through abandoned wells. This may be especially troublesome in mature sedimentary basins, which are often "punctured" by a very large number of exploration and production wells. For example, in the Alberta Basin there are more than 100,000 abandoned wells, the oldest from 1883. The cement used in the completion and abandonment of these wells, historically of variable quality and quantity, most probably has degraded with age and under the effect of formation brines. The cement may degrade even more rapidly when contacted by CO2 and possibly other components in the injection mixture (such as H2S). Cement properties and their modification through time must be understood in order to provide reliable estimates of leakage rates. Those leakage rates must then be linked to models of environmental consequences, and ultimately the entire analysis must be embedded in a probabilistic framework. Such an approach will allow leakage to be addressed rationally in terms of safety and long-term environmental impacts.

Field Tests of Real-time In-situ Dissolved CO2 Monitoring for CO2 Leakage Detection in Groundwater

NASA Astrophysics Data System (ADS)

Yang, C.; Zou, Y.; Delgado, J.; Guzman, N.; Pinedo, J.

2016-12-01

Groundwater monitoring for detecting CO2 leakage relies on groundwater sampling from water wells drilled into aquifers. Usually groundwater samples are required be collected periodically in field and analyzed in the laboratory. Obviously groundwater sampling is labor and cost-intensive for long-term monitoring of large areas. Potential damage and contamination of water samples during the sampling process can degrade accuracy, and intermittent monitoring may miss changes in the geochemical parameters of groundwater, and therefore signs of CO2 leakage. Real-time in-situ monitoring of geochemical parameters with chemical sensors may play an important role for CO2 leakage detection in groundwater at a geological carbon sequestration site. This study presents field demonstration of a real-time in situ monitoring system capable of covering large areas for detection of low levels of dissolved CO2 in groundwater and reliably differentiating natural variations of dissolved CO2 concentration from small changes resulting from leakage. The sand-alone system includes fully distributed fiber optic sensors for carbon dioxide detection with a unique sensor technology developed by Intelligent Optical Systems. The systems were deployed to the two research sites: the Brackenridge Field Laboratory where the aquifer is shallow at depths of 10-20 ft below surface and the Devine site where the aquifer is much deeper at depths of 140 to 150 ft. Groundwater samples were periodically collected from the water wells which were installed with the chemical sensors and further compared to the measurements of the chemical sensors. Our study shows that geochemical monitoring of dissolved CO2 with fiber optic sensors could provide reliable CO2 leakage signal detection in groundwater as long as CO2 leakage signals are stronger than background noises at the monitoring locations.

Hydrogeological characterization of shallow-depth zone for CO2 injection and leak test at a CO2 environmental monitoring site in Korea

NASA Astrophysics Data System (ADS)

Lee, S. S.; Kim, T. W.; Kim, H. H.; Ha, S. W.; Jeon, W. T.; Lee, K. K.

2015-12-01

The main goal of the this study is to evaluate the importance of heterogeneities in controlling the field-scale transport of CO2 are originated from the CO2 injected at saturated zone below the water table for monitoring and prediction of CO2 leakage from a reservoir. Hydrogeological and geophysical data are collected to characterize the site, prior to conducting CO2 injection experiment at the CO2 environmental monitoring site at Eumseong, Korea. The geophysical data were acquired from borehole electromagnetic flowmeter tests, while the hydraulic data were obtained from pumping tests, slug tests, and falling head permeability tests. Total of 13 wells to perform hydraulic and geophysical test are established along groundwater flow direction in regular sequence, revealed by the results of borehole electromagnetic flowmeter test. The results of geophysical tests indicated that hydraulic gradient is not identical with the topographic gradient. Groundwater flows toward the uphill direction in the study area. Then, the hydraulic tests were conducted to identify the hydraulic properties of the study site. According to the results of pumping and slug tests at the study site, the hydraulic conductivity values show ranges between 4.75 x 10-5 cm/day and 9.74 x 10-5 cm/day. In addition, a portable multi-level sampling and monitoring packer device which remains inflated condition for a long period developed and used to isolate designated depths to identify vertical distribution of hydrogeological characteristics. Hydrogeological information obtained from this study will be used to decide the injection test interval of CO2-infused water and gaseous CO2. Acknowledgement: Financial support was provided by "R&D Project on Environmental Mangement of Geologic CO2 Storage" from the KEITI (Project Number: 2014001810003).

Gopherus agassizii (desert tortoise) and Crotalus ruber (red diamond rattlesnake). Burrow co-occupancy

USGS Publications Warehouse

Lovich, Jeffrey E.

2011-01-01

I observed an adult Desert Tortoise and an adult Red Diamond Rattlesnake (sexes unknown) in a shallow tortoise burrow on 6 January 1997 at a wind energy generation facility near Palm Springs, Riverside Co., California, USA (33.9599°N, 116.6613°W).

Impacts of Ocean Acidification on Sediment Processes in Shallow Waters of the Arctic Ocean

PubMed Central

Gazeau, Frédéric; van Rijswijk, Pieter; Pozzato, Lara; Middelburg, Jack J.

2014-01-01

Despite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO2 and usually have a lower buffering capacity than warmer waters, acidification rates in these areas are faster than those in sub-tropical regions. The present study investigates the effects of ocean acidification on sediment composition, processes and sediment-water fluxes in an Arctic coastal system. Undisturbed sediment cores, exempt of large dwelling organisms, were collected, incubated for a period of 14 days, and subject to a gradient of pCO2 covering the range of values projected for the end of the century. On five occasions during the experimental period, the sediment cores were isolated for flux measurements (oxygen, alkalinity, dissolved inorganic carbon, ammonium, nitrate, nitrite, phosphate and silicate). At the end of the experimental period, denitrification rates were measured and sediment samples were taken at several depth intervals for solid-phase analyses. Most of the parameters and processes (i.e. mineralization, denitrification) investigated showed no relationship with the overlying seawater pH, suggesting that ocean acidification will have limited impacts on the microbial activity and associated sediment-water fluxes on Arctic shelves, in the absence of active bio-irrigating organisms. Only following a pH decrease of 1 pH unit, not foreseen in the coming 300 years, significant enhancements of calcium carbonate dissolution and anammox rates were observed. Longer-term experiments on different sediment types are still required to confirm the limited impact of ocean acidification on shallow Arctic sediment processes as observed in this study. PMID:24718610

Sources of Nutrients to Nearshore Areas of a Eutrophic Estuary: Implications for Nutrient-Enhanced Acidification in Puget Sound

NASA Astrophysics Data System (ADS)

Pacella, S. R.

2016-02-01

Ocean acidification has recently been highlighted as a major stressor for coastal organisms. Further work is needed to assess the role of anthropogenic nutrient additions in eutrophied systems on local biological processes, and how this interacts with CO2 emission-driven acidification. This study sought to distinguish changes in pH caused by natural versus anthropogenically affected processes. We quantified the variability in water column pH attributable to primary production and respiration fueled by anthropogenically derived nitrogen in a shallow nearshore area. Two study sites were located in shallow subtidal areas of the Snohomish River estuary, a eutrophic system located in central Puget Sound, Washington. These sites were chosen due to the presence of heavy agricultural activity, urbanized areas with associated waste water treatment, as well as influence from deep, high CO2 marine waters transported through the Strait of Juan de Fuca and upwelled into the area during spring and summer. Data was collected from July-December 2015 utilizing continuous moorings and discrete water column sampling. Analysis of stable isotopes, δ15N, δ18O-NO3, δ15N-NH4, was used to estimate the relative contributions of anthropogenic versus upwelled marine nitrogen sources. Continuous monitoring of pH, dissolved oxygen, temperature, and salinity was conducted at both study sites to link changes in nutrient source and availability with changes in pH. We predicted that isotope data would indicate greater contributions of nitrogen from agriculture and wastewater rather than upwelling in the shallow, nearshore study sites. This study seeks to distinguish the relative magnitude of pH change stimulated by anthropogenic versus natural sources of nitrogen to inform public policy decisions in critically important nearshore ecosystems.

Impacts of ocean acidification on sediment processes in shallow waters of the Arctic Ocean.

PubMed

Gazeau, Frédéric; van Rijswijk, Pieter; Pozzato, Lara; Middelburg, Jack J

2014-01-01

Despite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO2 and usually have a lower buffering capacity than warmer waters, acidification rates in these areas are faster than those in sub-tropical regions. The present study investigates the effects of ocean acidification on sediment composition, processes and sediment-water fluxes in an Arctic coastal system. Undisturbed sediment cores, exempt of large dwelling organisms, were collected, incubated for a period of 14 days, and subject to a gradient of pCO2 covering the range of values projected for the end of the century. On five occasions during the experimental period, the sediment cores were isolated for flux measurements (oxygen, alkalinity, dissolved inorganic carbon, ammonium, nitrate, nitrite, phosphate and silicate). At the end of the experimental period, denitrification rates were measured and sediment samples were taken at several depth intervals for solid-phase analyses. Most of the parameters and processes (i.e. mineralization, denitrification) investigated showed no relationship with the overlying seawater pH, suggesting that ocean acidification will have limited impacts on the microbial activity and associated sediment-water fluxes on Arctic shelves, in the absence of active bio-irrigating organisms. Only following a pH decrease of 1 pH unit, not foreseen in the coming 300 years, significant enhancements of calcium carbonate dissolution and anammox rates were observed. Longer-term experiments on different sediment types are still required to confirm the limited impact of ocean acidification on shallow Arctic sediment processes as observed in this study.

Analysis of stress changes and fault stability related to CO2 injection at the Tomakomai offshore site

NASA Astrophysics Data System (ADS)

Kano, Y.; Funatsu, T.; Nakao, S.; Kusunose, K.; Ishido, T.; Lei, X.; Tosha, T.

2013-12-01

A carbon capture and storage demonstration project is planned at the Tomakomai offshore site, which is located in the southwestern part of Hokkaido, Japan. The project includes geological CO2 storage at a rate of 0.25 Mt/year for three and a half years and a coherent system of capture (from petroleum refineries) and transportation (Ministry of Economy, Trade and Industry, 2012). Two different reservoirs are candidates: one is the Moebetsu formation which is shallow, gently inclined and composed of relatively homogeneous sandstone, and another is the Takinoue T1 formation which is deep, sharply inclined, overpressured and composed of heterogeneous volcanic rocks. Effects of the CO2 injection are expected to be considerably different between these two reservoirs. As part of a safety assessment, Kano et al. (2013) investigated stress changes and corresponding fault stability in the deeper Takinoue T1 formation, based on an estimated initial stress field and numerically-simulated changes in fluid pressure caused by a planned CO2 injection. One of the important features was that the slip tendency becomes maximal near the top of the dipping Takinoue formation which is substantially shallower than the injection depth. This is thought to be due to a combination of the overpressure and heterogeneous structure. In this presentation we will report results of additional analysis and discuss different behaviours between the Takinoue and Moebetsu formations. Sensitivity to uncertain geomechanical properties such as the friction coefficient and the effects of poro-elastic stress development due to changes in fluid pressure and temperature are also discussed. This research was partly funded and supported by the Ministry of Economy, Trade and Industry. We would like to acknowledge Japan CCS Co., Ltd., for providing their survey and research data on the Tomakomai site. References: Ministry of Economy, Trade and Industry, 2012. CCS demonstration project at the Tomakomai site (in Japanese). http://www.meti.go.jp/information/downloadfiles/c120208a02j.pdf Kano, Y., Funatsu, T., Nakao, S., Kusunose, K., Ishido, T., Lei, X.-L., Tosha, T., 2013. Fault stability analysis related to CO2 injection at Tomakomai, Hokkaido, Japan. Proc. GHGT-11, Kyoto, Japan, 18-22 November. Energy Procedia 37, 4946-4953.

Highly conductive ultrathin Co films by high-power impulse magnetron sputtering

NASA Astrophysics Data System (ADS)

Jablonka, L.; Riekehr, L.; Zhang, Z.; Zhang, S.-L.; Kubart, T.

2018-01-01

Ultrathin Co films deposited on SiO2 with conductivities exceeding that of Cu are demonstrated. Ionized deposition implemented by high-power impulse magnetron sputtering (HiPIMS) is shown to result in smooth films with large grains and low resistivities, namely, 14 µΩ cm at a thickness of 40 nm, which is close to the bulk value of Co. Even at a thickness of only 6 nm, a resistivity of 35 µΩ cm is obtained. The improved film quality is attributed to a higher nucleation density in the Co-ion dominated plasma in HiPIMS. In particular, the pulsed nature of the Co flux as well as shallow ion implantation of Co into SiO2 can increase the nucleation density. Adatom diffusion is further enhanced in the ionized process, resulting in a dense microstructure. These results are in contrast to Co deposited by conventional direct current magnetron sputtering where the conductivity is reduced due to smaller grains, voids, rougher interfaces, and Ar incorporation. The resistivity of the HiPIMS films is shown to be in accordance with models by Mayadas-Shatzkes and Sondheimer which consider grain-boundary and surface-scattering.

Biology of Symbioses between Marine Invertebrates and Intracellular Bacteria

DTIC Science & Technology

1990-01-30

bisphosphate carboxylase We designed from published sequence information oligonucleotide primers which are complementary to conserved regions on RubisCO ...large and small subunit genes. These primers were used successfully to amplify using polymerase chain reaction (PCR) specific regions of RubisCO ...for the large subunit of ribulose bisphosphate carboxylase/oxygenase ( RubisCO ) to symbiont DNA shows that the symbionts from both deep-sea and shallow

Geochemical survey of Levante Bay, Vulcano Island (Italy), a natural laboratory for the study of ocean acidification.

PubMed

Boatta, F; D'Alessandro, W; Gagliano, A L; Liotta, M; Milazzo, M; Rodolfo-Metalpa, R; Hall-Spencer, J M; Parello, F

2013-08-30

Shallow submarine gas vents in Levante Bay, Vulcano Island (Italy), emit around 3.6t CO2 per day providing a natural laboratory for the study of biogeochemical processes related to seabed CO2 leaks and ocean acidification. The main physico-chemical parameters (T, pH and Eh) were measured at more than 70 stations with 40 seawater samples were collected for chemical analyses. The main gas vent area had high concentrations of dissolved hydrothermal gases, low pH and negative redox values all of which returned to normal seawater values at distances of about 400m from the main vents. Much of the bay around the vents is corrosive to calcium carbonate; the north shore has a gradient in seawater carbonate chemistry that is well suited to studies of the effects of long-term increases in CO2 levels. This shoreline lacks toxic compounds (such as H2S) and has a gradient in carbonate saturation states. Copyright © 2013 Elsevier Ltd. All rights reserved.

Seasonal Variability in Vadose zone biodegradation at a crude oil pipeline rupture site

USGS Publications Warehouse

Sihota, Natasha J.; Trost, Jared J.; Bekins, Barbara; Berg, Andrew M.; Delin, Geoffrey N.; Mason, Brent E.; Warren, Ean; Mayer, K. Ulrich

2016-01-01

Understanding seasonal changes in natural attenuation processes is critical for evaluating source-zone longevity and informing management decisions. The seasonal variations of natural attenuation were investigated through measurements of surficial CO2 effluxes, shallow soil CO2 radiocarbon contents, subsurface gas concentrations, soil temperature, and volumetric water contents during a 2-yr period. Surficial CO2 effluxes varied seasonally, with peak values of total soil respiration (TSR) occurring in the late spring and summer. Efflux and radiocarbon data indicated that the fractional contributions of natural soil respiration (NSR) and contaminant soil respiration (CSR) to TSR varied seasonally. The NSR dominated in the spring and summer, and CSR dominated in the fall and winter. Subsurface gas concentrations also varied seasonally, with peak values of CO2 and CH4 occurring in the fall and winter. Vadose zone temperatures and subsurface CO2 concentrations revealed a correlation between contaminant respiration and temperature. A time lag of 5 to 7 mo between peak subsurface CO2 concentrations and peak surface efflux is consistent with travel-time estimates for subsurface gas migration. Periods of frozen soils coincided with depressed surface CO2 effluxes and elevated CO2 concentrations, pointing to the temporary presence of an ice layer that inhibited gas transport. Quantitative reactive transport simulations demonstrated aspects of the conceptual model developed from field measurements. Overall, results indicated that source-zone natural attenuation (SZNA) rates and gas transport processes varied seasonally and that the average annual SZNA rate estimated from periodic surface efflux measurements is 60% lower than rates determined from measurements during the summer.

Marine Hydrokinetic (MHK) Systems: A Systems Engineering Approach to Select Locations for the Practical Harvest of Electricity from Shallow Water Tidal Currents

NASA Astrophysics Data System (ADS)

Domenech, John

Due to increasing atmospheric CO2 concentration and its effect on global climates, the United States Environmental Protection Agency (EPA) proposes a Clean Power Plan (CPP) mandating CO2 reductions which will likely force the early retirement of inefficient, aging power plants. Consequentially, removing these plants equates to a shortfall of approximately 66 GW of electricity. These factors add to the looming resource problems of choosing whether to build large replacement power plants or consider alternative energy sources as a means to help close the gap between electricity supply and demand in a given region. One energy source, shallow water tidal currents, represents opportunities to convert kinetic energy to mechanical forms and provide electricity to homes and businesses. Nearly 2,000 National Oceanic Atmospheric Administration (NOAA) tidal current data points from Maine to Texas are considered. This paper, based on systems engineering thinking, provides key attributes (e.g. turbine efficiency, array size, transmission losses) for consideration as decision makers seek to identify where to site Marine Hydrokinetic (MHK) systems and the number of homes powered by the practical harvest of electricity from tidal currents at those locations with given attributes. A systems engineering process model is proposed for consideration as is a regression based equation to estimate MHK machine parameters needed for power a given number of homes.

Shallow water marine sediment bacterial community shifts along a natural CO2 gradient in the Mediterranean Sea off Vulcano, Italy.

PubMed

Kerfahi, Dorsaf; Hall-Spencer, Jason M; Tripathi, Binu M; Milazzo, Marco; Lee, Junghoon; Adams, Jonathan M

2014-05-01

The effects of increasing atmospheric CO(2) on ocean ecosystems are a major environmental concern, as rapid shoaling of the carbonate saturation horizon is exposing vast areas of marine sediments to corrosive waters worldwide. Natural CO(2) gradients off Vulcano, Italy, have revealed profound ecosystem changes along rocky shore habitats as carbonate saturation levels decrease, but no investigations have yet been made of the sedimentary habitat. Here, we sampled the upper 2 cm of volcanic sand in three zones, ambient (median pCO(2) 419 μatm, minimum Ω(arag) 3.77), moderately CO(2)-enriched (median pCO(2) 592 μatm, minimum Ω(arag) 2.96), and highly CO(2)-enriched (median pCO(2) 1611 μatm, minimum Ω(arag) 0.35). We tested the hypothesis that increasing levels of seawater pCO(2) would cause significant shifts in sediment bacterial community composition, as shown recently in epilithic biofilms at the study site. In this study, 454 pyrosequencing of the V1 to V3 region of the 16S rRNA gene revealed a shift in community composition with increasing pCO(2). The relative abundances of most of the dominant genera were unaffected by the pCO(2) gradient, although there were significant differences for some 5 % of the genera present (viz. Georgenia, Lutibacter, Photobacterium, Acinetobacter, and Paenibacillus), and Shannon Diversity was greatest in sediments subject to long-term acidification (>100 years). Overall, this supports the view that globally increased ocean pCO(2) will be associated with changes in sediment bacterial community composition but that most of these organisms are resilient. However, further work is required to assess whether these results apply to other types of coastal sediments and whether the changes in relative abundance of bacterial taxa that we observed can significantly alter the biogeochemical functions of marine sediments.

Geochemical constraints on volatile sources and subsurface conditions at Mount Martin, Mount Mageik, and Trident Volcanoes, Katmai Volcanic Cluster, Alaska

NASA Astrophysics Data System (ADS)

Lopez, T.; Tassi, F.; Aiuppa, A.; Galle, B.; Rizzo, A. L.; Fiebig, J.; Capecchiacci, F.; Giudice, G.; Caliro, S.; Tamburello, G.

2017-11-01

We use the chemical and isotopic composition of volcanic gases and steam condensate, in situ measurements of plume composition and remote measurements of SO2 flux to constrain volatile sources and characterize subvolcanic conditions at three persistently degassing and seismically active volcanoes within the Katmai Volcanic Cluster (KVC), Alaska: Mount Martin, Mount Mageik and Trident. In situ plume measurements of gas composition were collected at all three volcanoes using MultiGAS instruments to calculate gas ratios (e.g. CO2/H2S, SO2/H2S and H2O/H2S), and remote measurements of SO2 column density were collected from Mount Martin and Mount Mageik by ultraviolet spectrometer systems to calculate SO2 fluxes. Fumaroles were directly sampled for chemical and isotopic composition from Mount Mageik and Trident. Mid Ocean Ridge Basalt (MORB)-like 3He/4He ratios ( 7.2-7.6 Rc/RA) within Mount Mageik and Trident's fumarole emissions and a moderate SO2 flux ( 75 t/d) from Mount Martin, combined with gas compositions dominated by H2O, CO2 and H2S from all three volcanoes, indicate magma degassing and active hydrothermal systems in the subsurface of these volcanoes. Mount Martin's gas emissions have the lowest CO2/H2S ratio ( 2-4) and highest SO2 flux compared to the other KVC volcanoes, indicative of shallow magma degassing. Geothermometry techniques applied to Mount Mageik and Trident's fumarolic gas compositions suggest that their hydrothermal reservoirs are located at depths of 0.2 and 4 km below the surface, respectively. Observations of an unusually reducing gas composition at Trident and organic material in the near-surface soils suggest that thermal decomposition of sediments may be influencing gas composition. When the measured gas compositions from Mount Mageik and Trident are compared with previous samples collected in the late 1990's, relatively stable magmatic-hydrothermal conditions are inferred for Mount Mageik, while gradual degassing of residual magma and contamination by shallow crustal fluids is inferred for Trident. The isotopic composition of volcanic gases emitted from Mount Mageik and Trident reflect mixing of subducted slab, mantle and crustal volatile sources, with organic sediment and carbonate being the predominant sources. Considering the close proximity of the target volcanoes in comparison with the depth to the subducted slab we speculate that Aleutian Arc volatiles are fed by a relatively homogeneous subducted fluid and that much of the apparent variability in volatile provenance can be explained by shallow crustal volatile sources and/or processes.

Conversion of a moderately rewetted fen to a shallow lake - implications for net CO2 exchange

NASA Astrophysics Data System (ADS)

Koebsch, Franziska; Glatzel, Stephan; Hofmann, Joachim; Forbrich, Inke; Jurasinski, Gerald

2013-04-01

Extensive rewetting projects to re-establish the natural carbon (C) sequestration function of degraded peatlands are currently taking place in Europe and North-America. Year-round flooding provides a robust measure to prevent periods of drought that are associated with ongoing peat mineralization and to initiate the accumulation of new organic matter. Here, we present measurements of net carbon dioxide (CO2) exchange during the gradual conversion of a moderately rewetted fen to a shallow lake. When we started our measurements in 2009, mean growing season water level (MWGL) was 0 cm. In 2010 the site was flooded throughout the year with MWGL of 36 cm. Extraordinary strong rainfalls in July 2011 resulted in a further increase of MWGL to 56 cm. Measurements of net ecosystem exchange (NEE) were conducted during growing seasons (May-October) using the Eddy Covariance method. Information about vegetation vitality was deduced from the enhanced vegetation index (EVI) based on MODIS data. Ecosystem respiration (Reco) and gross ecosystem production (GEP) were high during vegetation period 2009 (1273.4 and -1572.1 g CO2-C m-2), but decreased by 61 and 46% respectively when the fen was flooded throughout 2010. Under water-logged conditions, heterotrophic respiration declines and gas exchange is limited. Moreover, flooding is a severe stress factor for plants and decreases autotrophic respiration and photosynthesis. However, in comparison to 2010, rates of Reco and GEP doubled during the beginning of growing season 2011, indicating plastic response strategies of wetland plants to flooding. Presumably, plants were not able to cope with the further increase of water levels to up to 120 cm in June/July 2011, resulting in another drop of GEP and Reco. The effects of plant vitality on GEP were confirmed by the remote sensed vegetation index. Throughout all three growing seasons, the fen was a distinct net CO2 sink (2009: -333.3±12.3, 2010: -294.1±8.4, -352.4±5.1 g CO2-C m-2). However, flooding causes a short-term ecosystem shift with severe consequences for Reco and GEP. Our results indicate that after a relatively short period of time, the plant community can acclimatise to inundation with increasing rates of GEP and autotrophic respiration.

Comparing eruptions of varying intensity at Kilauea via melt inclusion analysis

NASA Astrophysics Data System (ADS)

Ferguson, D. J.; Plank, T. A.; Hauri, E. H.; Houghton, B. F.; Gonnermann, H. M.; Swanson, D. A.; Blaser, A. P.

2013-12-01

Over the past 500 years explosive summit eruptions from Kilauea volcano, Hawaii, have exhibited a range of eruption magnitudes, from large basaltic sub-plinian events to Hawaiian lava fountains of various intensity. Knowledge of the factors controlling such dramatic changes in explosivity and mass discharge rate is vital for understanding the dynamics of explosive basaltic magma systems, but these remain poorly constrained. At Kilauea this information also has important implications for hazard assessment, as future eruptions may be far larger than those observed historically. To investigate the processes associated with eruptions of varying magnitudes we have analyzed the composition and dissolved volatile contents (H2O-CO2-S-Cl-F) of olivine-hosted melt inclusions, sampled from tephra deposits associated with three eruptions of different sizes: a moderate lava-fountain (1959 Episode of Kilauea Iki); an exceptionally high lava-fountain (1500 CE Keanakāko'i reticulite) and a basaltic sub-plinian eruption (1650 CE Keanakāko'i layer 6 scoria). Over this time period (~500 years) we find no major shifts in the major element composition of primary melts feeding the Kilauea magmatic system, and melt inclusions from all eruptions record similar maximum water (~0.7 wt% H2O) and CO2 (~300 ppm) contents, regardless of eruption magnitude. Co-variations between other volatile species, such as CO2 and S, do not support a role for excess volatiles (i.e. CO2) in the larger eruptions via ';gas-fluxing'. Our data therefore suggests that major shifts in eruptive magnitude are unlikely to be linked to either changes in the primary volatile content of the melts or excess gas supplied by open-system degassing of deeper melts. Rather we find evidence for significant variations in the shallow degassing behavior of magmas associated with the larger Keanakāko'i eruptions (sub-plinian and strong lava-fountaining events) compared to that from less vigorous moderate Kilauea Iki lava-fountaining events. On plots of CO2 versus H2O, Kilauea Iki MI's record volatile contents consistent with equilibrium degassing of magma rising from a depth of ~3 km. In contrast, the volatile contents of melts from the more explosive eruptions appear to be strongly affected by degassing processes at shallow depths (< 300 m), indicating variations in the ascent and storage of melts over this time-period. These changes in storage conditions may be linked to variations in the depth of the summit caldera, which was significantly greater during the older more explosive eruptive phases.

Co-seismic deformation of the August 27, 2012 Mw 7.3 El Salvador and September 5, 2012 Mw 7.6 Costa Rica earthquakes

NASA Astrophysics Data System (ADS)

Geirsson, H.; La Femina, P. C.; DeMets, C.; Mattioli, G. S.; Hernández, D.

2013-05-01

We investigate the co-seismic deformation of two significant earthquakes that occurred along the Middle America trench in 2012. The August 27 Mw 7.3 El Salvador and September 5 Mw 7.6 Nicoya Peninsula, Costa Rica earthquakes, were examined using a combination of episodic and continuous Global Positioning System (GPS) data. USGS finite fault models based on seismic data predict fundamentally different characteristics for the two ruptures. The El Salvador event occurred in a historical seismic gap and on the shallow segment of the Middle America Trench main thrust, rupturing a large area, but with a low magnitude of slip. A small tsunami was observed along the coast in Nicaragua and El Salvador, additionally indicating near-trench rupture. Conversely, the Nicoya, Costa Rica earthquake was predicted to have an order of magnitude higher slip on a spatially smaller patch deeper on the main thrust. We present results from episodic and continuous geodetic GPS measurements made in conjunction with the two earthquakes, including data from newly installed COCONet (Continuously Operating Caribbean GPS Observational Network) sites. Episodic GPS measurements made in El Salvador, Honduras, and Nicaragua following the earthquakes, allow us to estimate the co-seismic deformation field from both earthquakes. Because of the small magnitude of the El Salvador earthquake and its shallow rupture the observed co-seismic deformation is small (<2 cm). Conversely, the Costa Rica earthquake occurred directly beneath a seismic and geodetic network specifically designed to capture such events. The observed displacements exceeded 0.5 m and there is a significant post-seismic transient following the earthquake. We use our estimated co-seismic offsets for both earthquakes to model the magnitude and spatial variability of slip for these two events.

Natural analogues for CO2 storage sites - analysis of a global dataset

NASA Astrophysics Data System (ADS)

Miocic, Johannes; Gilfillan, Stuart; McDermott, Christopher; Haszeldine, R. Stuart

2013-04-01

Carbon Capture and Storage is the only industrial scale technology currently available to reduce CO2 emissions from fossil-fuelled power plants and large industrial source to the atmosphere and thus mitigate climate change. CO2 is captured at the source and transported to subsurface storage sites, such as depleted oil and gas fields or saline aquifers. In order to have an effect on emissions and to be considered safe it is crucial that the amount of CO2 leaking from storage sites to shallow aquifers or the surface remains very low (<1% over 1000 years). Some process that influence the safety of a reservoir, such as CO2-rock-brine interactions, can be studied using experiments on both laboratory and field-scale. However, long-term processes such as the development of leakage pathways can only be understood by either predictive modelling or by studying natural CO2 reservoirs as analogues for long term CO2 storage sites. Natural CO2 reservoirs have similar geological trapping mechanisms as anticipated for CO2 storage sites and often have held CO2 for a geological period of time (millions of years) without any indication for leakage. Yet, migration of CO2 from reservoirs to the surface is also common and evidenced by gas seeps such as springs and soil degassing. We have compiled and analysed a dataset comprising of more than 50 natural CO2 reservoirs from different settings all around the globe to provide an overview of the factors that are important for the retention of CO2 in the subsurface and what processes lead to leakage of CO2 from the reservoir. Initial results indicate that if the reservoir is found to be leaking, CO2 migration is along faults and not through caprock layers. This indicates that faults act as fluid pathways and play an important role when characterizing a storage site. Additionally, it appears that overpressure of the overburden and the state of CO2 in the reservoir influence the likelihood of migration and hence the safety of a reservoir.

Effects of ocean acidification driven by elevated CO2 on larval shell growth and abnormal rates of the venerid clam, Mactra veneriformis

NASA Astrophysics Data System (ADS)

Kim, Jee-Hoon; Yu, Ok Hwan; Yang, Eun Jin; Kang, Sung-Ho; Kim, Won; Choy, Eun Jung

2016-11-01

The venerid clam ( Mactra veneriformis Reeve 1854) is one of the main cultured bivalve species in intertidal and shallow subtidal ecosystems along the west coast of Korea. To understand the effects of ocean acidification on the early life stages of Korean clams, we investigated shell growth and abnormality rates and types in the D-shaped, umbonate veliger, and pediveliger stages of the venerid clam M. veneriformis during exposure to elevated seawater pCO2. In particular, we examined abnormal types of larval shell morphology categorized as shell deformations, shell distortions, and shell fissures. Specimens were incubated in seawater equilibrated with bubbled CO2-enriched air at (400±25)×10-6 (ambient control), (800±25)×10-6 (high pCO2), or (1 200±28)×10-6 (extremely high pCO2), the atmospheric CO2 concentrations predicted for the years 2014, 2084, and 2154 (70-year intervals; two human generations), respectively, in the Representative Concentration Pathway (RCP) 8.5 scenario. The mean shell lengths of larvae were significantly decreased in the high and extremely high pCO2 groups compared with the ambient control groups. Furthermore, under high and extremely high pCO2 conditions, the cultures exhibited significantly increased abundances of abnormal larvae and increased severity of abnormalities compared with the ambient control. In the umbonate veliger stage of the experimental larvae, the most common abnormalities were shell deformations, distortions, and fissures; on the other hand, convex hinges and mantle protuberances were absent. These results suggest that elevated CO2 exerts an additional burden on the health of M. veneriformis larvae by impairing early development.

Monitoring CO2 sequestration into deep saline aquifer and associated salt intrusion using coupled multiphase flow modeling and time-lapse electrical resistivity tomography

NASA Astrophysics Data System (ADS)

Lu, C.; Zhang, C.; Huang, H.; Johnson, T.

2012-12-01

Geological sequestration of carbon dioxide (CO2) into the subsurface has been considered as one solution to reduce greenhouse emission to the atmosphere. Successful sequestration process requires efficient and adequate monitoring of injected fluids as they migrate into the aquifer to evaluate flow path, leakage, and geochemical interactions between CO2 and geologic media. In this synthetic field scale study, we have integrated 3D multiphase flow modeling code PFLOTRAN with 3D time-laps electrical resistivity tomography (ERT) to gain insight into the supercritical (SC) CO2 plumes movement in the deep saline aquifer and associated brine intrusion into shallower fresh water aquifer. A parallel ERT forward and inverse modeling package was introduced, and related algorithms are briefly described. The capabilities and limitations of ERT in monitoring CO2 migration are assessed by comparing the results from PFLOTRAN simulations with the ERT inversion results. In general, our study shows the ERT inversion results compare well with PFLOTRAN with reasonable discrepancies, indicating that the ERT can capture the actual CO2 plume dynamics and brine intrusion. Detailed comparisons on the location, size and volume of CO2 plume show the ERT method underestimated area review and overestimated total plume volume in the predictions of SC CO2 movements. These comparisons also show the ERT method constantly overestimate salt intrusion area and underestimated total solute amount in the predictions of brine filtration. Our study shows that together with other geochemical and geophysical methods, ERT is a potentially useful monitoring tool in detecting the SC CO2 and formation fluid migrations.

Ocean life breaking rules by building shells in acidic extremes.

PubMed

Doubleday, Zoë A; Nagelkerken, Ivan; Connell, Sean D

2017-10-23

Rising levels of carbon dioxide (CO 2 )from fossil fuel combustion is acidifying our oceans [1,2]. This acidification is expected to have negative effects on calcifying animals because it affects their ability to build shells [3,4]. However, the effects of ocean acidification in natural environments, subject to ecological and evolutionary processes (such as predation, competition, and adaptation), is uncertain [5,6]. These processes may buffer, or even reverse, the direct, short-term effects principally measured in laboratory experiments (for example, [6]). Here we describe the discovery of marine snails living at a shallow-water CO 2 vent in the southwest Pacific, an environment 30 times more acidic than normal seawater (Figure 1). By measuring the chemical fingerprints locked within the shell material, we show that these snails have a restricted range of movement, which suggests that they live under these conditions for their entire lives. The existence of these snails demonstrates that calcifying animals can build their shells under the acidic and corrosive conditions caused by extreme CO 2 enrichment. This unforeseen capacity, whether driven by ecological or adaptive processes, is key to understanding whether calcifying life may survive a high-CO 2 future. Copyright © 2017 Elsevier Ltd. All rights reserved.

Carbon-Isotopic Dynamics of Streams, Taylor Valley, Antarctica: Biological Effects

NASA Technical Reports Server (NTRS)

Neumann, K.; DesMarais, D. J.

1998-01-01

We have investigated the role of biological processes in the C-isotopic dynamics of the aquatic ecosystems in Taylor Valley, Antarctica. This cold desert ecosystem is characterized by the complete lack of vascular plants, and the presence of algal mats in ephemeral streams and perennially ice covered lakes. Streams having abundant algal mats and mosses have very low sigma CO2 concentrations, as well as the most depleted delta C-13 values (-4%). Previous work has shown that algal mats in these streams have delta C-13 values averaging -7.01%. These values are similar to those observed in the algal mats in shallow areas of the lakes in Taylor Valley, where CO2 is thought to be colimiting to growth. These low Sigma CO2 concentrations, and delta C(13) signatures heavier than the algal mats, suggest that CO2 may be colimiting in the streams, as well. Streams with little algal growth, especially the longer ones in Fryxell Basin, have higher Sigma CO2 concentrations and much more enriched isotopic signatures (as high as +8%). In these streams, the dissolution of isotopically enriched, cryogenic CaCO3 is probably the major source of dissolved carbonate. The delta C(13) geochemistry of Antarctic streams is radically different from the geochemistry of more temperate streams, as it is not affected by terrestrially produced, isotopically depleted Sigma CO2. These results have important implications for the understanding of "biogenic" carbonate that might have been produced from aquatic ecosystems in the past on Mars.

How secure is subsurface CO2 storage? Controls on leakage in natural CO2 reservoirs

NASA Astrophysics Data System (ADS)

Miocic, Johannes; Gilfillan, Stuart; McDermott, Christopher; Haszeldine, Stuart

2014-05-01

Carbon Capture and Storage (CCS) is the only industrial scale technology available to directly reduce carbon dioxide (CO2) emissions from fossil fuelled power plants and large industrial point sources to the atmosphere. The technology includes the capture of CO2 at the source and transport to subsurface storage sites, such as depleted hydrocarbon reservoirs or saline aquifers, where it is injected and stored for long periods of time. To have an impact on the greenhouse gas emissions it is crucial that there is no or only a very low amount of leakage of CO2 from the storage sites to shallow aquifers or the surface. CO2 occurs naturally in reservoirs in the subsurface and has often been stored for millions of years without any leakage incidents. However, in some cases CO2 migrates from the reservoir to the surface. Both leaking and non-leaking natural CO2 reservoirs offer insights into the long-term behaviour of CO2 in the subsurface and on the mechanisms that lead to either leakage or retention of CO2. Here we present the results of a study on leakage mechanisms of natural CO2 reservoirs worldwide. We compiled a global dataset of 49 well described natural CO2 reservoirs of which six are leaking CO2 to the surface, 40 retain CO2 in the subsurface and for three reservoirs the evidence is inconclusive. Likelihood of leakage of CO2 from a reservoir to the surface is governed by the state of CO2 (supercritical vs. gaseous) and the pressure in the reservoir and the direct overburden. Reservoirs with gaseous CO2 is more prone to leak CO2 than reservoirs with dense supercritical CO2. If the reservoir pressure is close to or higher than the least principal stress leakage is likely to occur while reservoirs with pressures close to hydrostatic pressure and below 1200 m depth do not leak. Additionally, a positive pressure gradient from the reservoir into the caprock averts leakage of CO2 into the caprock. Leakage of CO2 occurs in all cases along a fault zone, indicating that faults play a major role when it comes to fluid migration from a reservoir. However, nearly 50% of the non-leaking studied reservoirs are also fault bound, demonstrating that faults are not always necessarily leakage pathways.

Sn/Be Sequentially co-doped Hematite Photoanodes for Enhanced Photoelectrochemical Water Oxidation: Effect of Be2+ as co-dopant

PubMed Central

Annamalai, Alagappan; Lee, Hyun Hwi; Choi, Sun Hee; Lee, Su Yong; Gracia-Espino, Eduardo; Subramanian, Arunprabaharan; Park, Jaedeuk; Kong, Ki-jeong; Jang, Jum Suk

2016-01-01

For ex-situ co-doping methods, sintering at high temperatures enables rapid diffusion of Sn4+ and Be2+ dopants into hematite (α–Fe2O3) lattices, without altering the nanorod morphology or damaging their crystallinity. Sn/Be co-doping results in a remarkable enhancement in photocurrent (1.7 mA/cm2) compared to pristine α–Fe2O3 (0.7 mA/cm2), and Sn4+ mono-doped α-Fe2O3 photoanodes (1.0 mA/cm2). From first-principles calculations, we found that Sn4+ doping induced a shallow donor level below the conduction band minimum, which does not contribute to increase electrical conductivity and photocurrent because of its localized nature. Additionally, Sn4+-doping induce local micro-strain and a decreased Fe-O bond ordering. When Be2+ was co-doped with Sn4+-doped α–Fe2O3 photoanodes, the conduction band recovered its original state, without localized impurities peaks, also a reduction in micro-strain and increased Fe-O bond ordering is observed. Also the sequence in which the ex-situ co-doping is carried out is very crucial, as Be/Sn co-doping sequence induces many under-coordinated O atoms resulting in a higher micro-strain and lower charge separation efficiency resulting undesired electron recombination. Here, we perform a detailed systematic characterization using XRD, FESEM, XPS and comprehensive electrochemical and photoelectrochemical studies, along with sophisticated synchrotron diffraction studies and extended X-ray absorption fine structure. PMID:27005757

The combined effects of ocean warming and acidification on shallow-water meiofaunal assemblages.

PubMed

Lee, Matthew R; Torres, Rodrigo; Manríquez, Patricio H

2017-10-01

Climate change due to increased anthropogenic CO 2 in the atmosphere is causing an increase in seawater temperatures referred to as ocean warming and a decrease in seawater pH, referred to as ocean acidification. The meiofauna play an important role in the ecology of marine ecosystems and the functions they provide. Using microcosms, meiofaunal assemblages were exposed to two temperatures (15 and 19 °C) and two pHs (pCO 2 of 400 and 1000 ppm), both individually and in combination, for a period of 90 days. The hypothesis that increased temperature will increase meiofaunal abundance was not supported. The hypothesis that a reduced pH will reduce meiofaunal abundance and species richness was supported. The combination of future conditions of temperature and pH (19 °C and pCO 2 of 1000 ppm) did not affect overall abundance but the structure of the nematode assemblage changed becoming dominated by a few opportunistic species. Copyright © 2017 Elsevier Ltd. All rights reserved.

Puhimau thermal area: a window into the upper east rift zone of Kilauea Volcano, Hawaii?

USGS Publications Warehouse

McGee, K.A.; Sutton, A.J.; Elias, T.; Doukas, M.P.; Gerlach, T.M.

2006-01-01

We report the results of two soil CO2 efflux surveys by the closed chamber circulation method at the Puhimau thermal area in the upper East Rift Zone (ERZ) of Kilauea volcano, Hawaii. The surveys were undertaken in 1996 and 1998 to constrain how much CO2 might be reaching the ERZ after degassing beneath the summit caldera and whether the Puhimau thermal area might be a significant contributor to the overall CO2 budget of Kilauea. The area was revisited in 2001 to determine the effects of surface disturbance on efflux values by the collar emplacement technique utilized in the earlier surveys. Utilizing a cutoff value of 50 g m−2 d−1 for the surrounding forest background efflux, the CO2 emission rates for the anomaly at Puhimau thermal area were 27 t d−1 in 1996 and 17 t d−1 in 1998. Water vapor was removed before analysis in all cases in order to obtain CO2 values on a dry air basis and mitigate the effect of water vapor dilution on the measurements. It is clear that Puhimau thermal area is not a significant contributor to Kilauea's CO2 output and that most of Kilauea's CO2 (8500 t d−1) is degassed at the summit, leaving only magma with its remaining stored volatiles, such as SO2, for injection down the ERZ. Because of the low CO2 emission rate and the presence of a shallow water table in the upper ERZ that effectively scrubs SO2 and other acid gases, Puhimau thermal area currently does not appear to be generally well suited for observing temporal changes in degassing at Kilauea.

Dissolved gases in hydrothermal (phreatic) and geyser eruptions at Yellowstone National Park, USA

USGS Publications Warehouse

Hurwitz, Shaul; Clor, Laura; McCleskey, R. Blaine; Nordstrom, D. Kirk; Hunt, Andrew G.; Evans, William C.

2016-01-01

Multiphase and multicomponent fluid flow in the shallow continental crust plays a significant role in a variety of processes over a broad range of temperatures and pressures. The presence of dissolved gases in aqueous fluids reduces the liquid stability field toward lower temperatures and enhances the explosivity potential with respect to pure water. Therefore, in areas where magma is actively degassing into a hydrothermal system, gas-rich aqueous fluids can exert a major control on geothermal energy production, can be propellants in hazardous hydrothermal (phreatic) eruptions, and can modulate the dynamics of geyser eruptions. We collected pressurized samples of thermal water that preserved dissolved gases in conjunction with precise temperature measurements with depth in research well Y-7 (maximum depth of 70.1 m; casing to 31 m) and five thermal pools (maximum depth of 11.3 m) in the Upper Geyser Basin of Yellowstone National Park, USA. Based on the dissolved gas concentrations, we demonstrate that CO2 mainly derived from magma and N2 from air-saturated meteoric water reduce the near-surface saturation temperature, consistent with some previous observations in geyser conduits. Thermodynamic calculations suggest that the dissolved CO2 and N2 modulate the dynamics of geyser eruptions and are likely triggers of hydrothermal eruptions when recharged into shallow reservoirs at high concentrations. Therefore, monitoring changes in gas emission rate and composition in areas with neutral and alkaline chlorine thermal features could provide important information on the natural resources (geysers) and hazards (eruptions) in these areas.

Three-Dimensional Shallow Water Adaptive Hydraulics (ADH-SW3) Validation: Galveston Bay Hydrodynamics and Salinity Transport

DTIC Science & Technology

2015-04-01

model mesh with elements (vertical co-ordinate in meters). ....................... 5 Figure 3. Ocean tidal boundary (Hour 0 = 1 Jan 1990, 12:00 a.m...7 Figure 4. Ocean salt boundary (Hour 0 = 1 Jan 1990, 12:00 a.m...channel and the connections of Galveston Bay to the open ocean . Figures 1 and 2 illustrate the distribution of vertical layers and resolution in the

Optimizing and Quantifying CO 2 Storage Resource in Saline Formations and Hydrocarbon Reservoirs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bosshart, Nicholas W.; Ayash, Scott C.; Azzolina, Nicholas A.

In an effort to reduce carbon dioxide (CO 2) emissions from large stationary sources, carbon capture and storage (CCS) is being investigated as one approach. This work assesses CO 2 storage resource estimation methods for deep saline formations (DSFs) and hydrocarbon reservoirs undergoing CO 2 enhanced oil recovery (EOR). Project activities were conducted using geologic modeling and simulation to investigate CO 2 storage efficiency. CO 2 storage rates and efficiencies in DSFs classified by interpreted depositional environment were evaluated at the regional scale over a 100-year time frame. A focus was placed on developing results applicable to future widespread commercial-scalemore » CO 2 storage operations in which an array of injection wells may be used to optimize storage in saline formations. The results of this work suggest future investigations of prospective storage resource in closed or semiclosed formations need not have a detailed understanding of the depositional environment of the reservoir to generate meaningful estimates. However, the results of this work also illustrate the relative importance of depositional environment, formation depth, structural geometry, and boundary conditions on the rate of CO 2 storage in these types of systems. CO 2 EOR occupies an important place in the realm of geologic storage of CO 2, as it is likely to be the primary means of geologic CO 2 storage during the early stages of commercial implementation, given the lack of a national policy and the viability of the current business case. This work estimates CO 2 storage efficiency factors using a unique industry database of CO 2 EOR sites and 18 different reservoir simulation models capturing fluvial clastic and shallow shelf carbonate depositional environments for reservoir depths of 1219 and 2438 meters (4000 and 8000 feet) and 7.6-, 20-, and 64-meter (25-, 66,- and 209-foot) pay zones. The results of this work provide practical information that can be used to quantify CO 2 storage resource estimates in oil reservoirs during CO 2 EOR operations (as opposed to storage following depletion) and the uncertainty associated with those estimates.« less

Composition and origin of coalbed gases in the Lower Silesian basin, southwest Poland

USGS Publications Warehouse

Kotarba, M.J.; Rice, D.D.

2001-01-01

Coalbed gases in the Lower Silesian Coal Basin (LSCB) of Poland are highly variable in both their molecular and stable isotope compositions. Geochemical indices and stable isotope ratios vary within the following ranges: hydrocarbon (CHC) index CHC = CH4/(C2H6+C3H8) from 1.1 to 5825, wet gas (C2+) index C2+ = (C2H6+ C3H8+ C4H10+ C5H12) / (CH4+ C2H6+ C3H8+ C4H10+ C5H12) 100 (%) from 0.0 to 48.3%, CO2-CH4 (CDMI) index CDMI = CO2/ (CO2+ CH4) 100 (%) from 0.1 to 99.9%, ??13C(CH4) from -66.1 to -24.6%o, ??D(CH4) from -266 to -117%o, ??13C(C2H6) from -27.8 to -22.8%o, and ??13C(CO2) from -26.6 to 16.8%o. Isotopic studies reveal the presence of 3 genetic types of natural gases: thermogenic (CH4, higher gaseous hydrocarbons, and CO2), endogenic CO2, and microbial CH4 and CO2. Thermogenic gases resulted from coalification processes, which were probably completed by Late Carboniferous and Early Permian time. Endogenic CO2 migrated along the deep-seated faults from upper mantle and/or magma chambers. Minor volumes of microbial CH4 and CO2 occur at shallow depths close to the abandoned mine workings. "Late-stage" microbial processes have commenced in the Upper Cretaceous and are probably active at present. However, depth-related isotopic fractionation which has resulted from physical and physicochemical (e.g. diffusion and adsorption/desorption) processes during gas migration cannot be neglected. The strongest rock and gas outbursts occur only in those parts of coal deposits of the LSCB which are dominated by large amounts of endogenic CO2. ?? 2001 Elsevier Science Ltd.

Carbon dioxide budgets in cave air and carbon in speleothems; insights from a shallow cave in Ireland

NASA Astrophysics Data System (ADS)

McDermott, Frank; Phillips, Dominika

2017-04-01

The conventional view that hydrological inputs (e.g. drip-water degassing) comprise the dominant source of cave air CO2 has been challenged by recent studies that emphasise the importance of direct advection of gaseous CO2from above and beneath cave voids (e.g. 'soil air' and 'ground air'). A better understanding of CO2 gas budgets in caves is important, not only for the correct interpretation of δ13C values and 14C activity data in speleothems, but also for an understanding of the wider role of karst in the global carbon cycle as a source or sink of atmospheric CO2. This study presents new results from a combined air-temperature and CO2 monitoring programme at a small multi-chamber cave in SE Ireland (Ballynamintra cave, Co. Waterford), building on an earlier study at this cave (Baldini et al., 2006). Episodic, low-amplitude but temporally coherent diurnal-scale cave air temperature fluctuations detected almost simultaneously by a series of temperature loggers within the cave were used to detect air mass advection. The sequence and pattern of temperature fluctuations at different locations within the cave enabled the identification of discrete air-inflow and air-outflow events. These diurnal-scale events occur episodically throughout the year in the winter/ spring and summer/autumn temperature ventilation regimes of the cave. Importantly, changes in cave air pCO2 values recorded by an infra-red logger located in the inner chamber a few metres from the back of the cave occur contemporaneously with the air-mass displacement events, and are consistent with direct advection of CO2-rich soil air via fractures in the subjacent cave roof and walls. In the winter regime, episodic diurnal-scale air outflow events draw CO2-rich air over the logger, resulting in short-lived pulses of air, typically containing c. 0.7% CO2 (by volume), several times the ambient cave air CO2 values at this site. Similar events occur during the summer/autumn thermal regime, but these reach higher CO2values (1-1.2%), similar to those measured previously in the overlying soil. Overall, the data confirm an important role for soil and/or ground air sources at this cave and indicate that the episodic CO2 inputs are not controlled by drip-water inputs,. Some recent studies have additionally argued that advected 'ground-air' is not only an important constituent of cave air, but also an important source of carbon in speleothems. This claim is critically evaluated here using 14C activity measurements from actively growing zero-age soda-straw stalactites from the small inner chamber of the cave where the CO2 monitoring was carried out. Surprisingly, soda-straws collected from within a few metres of each other in this inner chamber exhibit quite different 14C activities (93-101 pMC), and are not identical as might be expected if complete carbon isotope exchange had occurred between the dissolved inorganic carbon and the cave atmosphere. The reasons for this will be discussed, drawing on the results of published kinetic models for degassing and isotope exchange. Overall, it is concluded that while the CO2 budget of the air in Ballynamintra cave is dominated by directly advected soil air, water transported dissolved inorganic carbon (DIC) likely remains an important carbon source for its speleothems. Baldini, J.U.L., Baldini, L.M., McDermott, F. and Clipson, N. (2006) Carbon dioxide sources, sinks, and spatial variability in shallow temperate zone caves: evidence from Ballynamintra Cave, Ireland. Journal of Cave and Karst Studies, 68, 4-11.

Soil gas geochemistry in relation to eruptive fissures on Timanfaya volcano, Lanzarote Island (Canary Islands, Spain)

NASA Astrophysics Data System (ADS)

Padrón, Eleazar; Padilla, Germán; Hernández, Pedro A.; Pérez, Nemesio M.; Calvo, David; Nolasco, Dácil; Barrancos, José; Melián, Gladys V.; Dionis, Samara; Rodríguez, Fátima

2013-01-01

We report herein the first results of an extensive soil gas survey performed on Timanfaya volcano on May 2011. Soil gas composition at Timanfaya volcano indicates a main atmospheric source, slightly enriched in CO2 and He. Soil CO2 concentration showed a very slight deep contribution of the Timanfaya volcanic system, with no clear relation to the main eruptive fissures of the studied area. The existence of soil helium enrichments in Timanfaya indicates a shallow degassing of crustal helium and other possible deeper sources probably form cooling magma bodies at depth. The main soil helium enrichments were observed in good agreement with the main eruptive fissures of the 1730-36 eruption, with the highest values located at those areas with a higher density of recent eruptive centers, indicating an important structural control for the leakage of helium at Timanfaya volcano. Atmospheric air slightly polluted by deep-seated helium emissions, CO2 degassed from a cooling magma body, and biogenic CO2, might be the most plausible explanation for the existence of soil gas. Helium is a deep-seated gas, exhibiting important emission rates along the main eruptive fissure of the 1730-36 eruption of Timanfaya volcano.

A geochemical approach for assessing the possible uses of the geothermal resource in the eastern sector of the Sabatini Volcanic District (Central Italy)

NASA Astrophysics Data System (ADS)

Cinti, Daniele; Tassi, Franco; Procesi, Monia; Brusca, Lorenzo; Cabassi, Jacopo; Capecchiacci, Francesco; Delgado Huertas, Antonio; Galli, Gianfranco; Grassa, Fausto; Vaselli, Orlando; Voltattorni, Nunzia

2017-04-01

The Sabatini Volcanic District (SVD) hosts a hydrothermal reservoir heated by the post-magmatic activity that affected the peri-Tyrrhenian sector of central Italy, giving rise to a number of thermal and mineral discharges. In this study, a complete geochemical and isotopic dataset based on the composition of 215 water and 9 bubbling gases, collected from the eastern sector of this huge hydrothermal system, is reported. The main aims are to (i) investigate the fluid sources and the main chemical-physical processes controlling the fluid chemistry and (ii) construct a conceptual fluid circulation model to provide insights into the possible use(s) of the geothermal resource. The fluid discharges are fed by two main aquifers, characterized by: (1) a Ca-HCO3 to Ca(Na)-HCO3 composition, typical of a shallow hydrological circuit within volcanic and sedimentary formations, and (2) a Ca-HCO3(SO4) to Na(Ca)-HCO3(Cl) composition, produced by the interaction of CO2-rich fluids with Mesozoic and Triassic carbonate-evaporite rocks. A thick sequence of low-permeability volcanic products represents a physical barrier between the two fluid reservoirs. As commonly occurring in central-southern Italy, CO2 is mainly produced by thermo-metamorphic decarbonation within the carbonate-evaporite reservoir, with minor contribution of mantle CO2. A dominant crustal source is also indicated by the relatively low R/Ra values (0.07-1.04). Methane and light hydrocarbons are mostly thermogenic, whereas H2S derives from thermogenic reduction of the Triassic anhydrites. Slightly positive 15N/14N values suggest minor N2 contribution from deep sedimentary sources. On the whole, a comparison of these geochemical features with those of the thermal fluids from the western portion of SVD highlights an eastward increasing influence of the shallow aquifer on the deep-originated fluids, likely caused by the proximity of the Apennine range from where the meteoric water, recharging the hydrothermal system, permeate. Accordingly, gas geothermometry in the CH4-CO2-H2 and H2S-CO2-H2 systems suggests equilibrium temperatures <200 °C, i.e. significantly lower than those measured in fluids from deep geothermal wells (300 °C). Although mitigated by the short distance from the Apennine range, the thermal anomaly recognized by fluid geochemistry in the eastern SVD makes this area suitable for direct exploitation of the geothermal resource.

Modelling of the dissolution and reprecipitation of uranium under oxidising conditions in the zone of shallow groundwater circulation.

PubMed

Dutova, Ekaterina M; Nikitenkov, Aleksei N; Pokrovskiy, Vitaly D; Banks, David; Frengstad, Bjørn S; Parnachev, Valerii P

2017-11-01

Generic hydrochemical modelling of a grantoid-groundwater system, using the Russian software "HydroGeo", has been carried out with an emphasis on simulating the accumulation of uranium in the aqueous phase. The baseline model run simulates shallow granitoid aquifers (U content 5 ppm) under conditions broadly representative of southern Norway and southwestern Siberia: i.e. temperature 10 °C, equilibrated with a soil gas partial CO 2 pressure (P CO2 , open system) of 10 -2.5 atm. and a mildly oxidising redox environment (Eh = +50 mV). Modelling indicates that aqueous uranium accumulates in parallel with total dissolved solids (or groundwater mineralisation M - regarded as an indicator of degree of hydrochemical evolution), accumulating most rapidly when M = 550-1000 mg L -1 . Accumulation slows at the onset of saturation and precipitation of secondary uranium minerals at M = c. 1000 mg L -1 (which, under baseline modelling conditions, also corresponds approximately to calcite saturation and transition to Na-HCO 3 hydrofacies). The secondary minerals are typically "black" uranium oxides of mixed oxidation state (e.g. U 3 O 7 and U 4 O 9 ). For rock U content of 5-50 ppm, it is possible to generate a wide variety of aqueous uranium concentrations, up to a maximum of just over 1 mg L -1 , but with typical concentrations of up to 10 μg L -1 for modest degrees of hydrochemical maturity (as indicated by M). These observations correspond extremely well with real groundwater analyses from the Altai-Sayan region of Russia and Norwegian crystalline bedrock aquifers. The timing (with respect to M) and degree of aqueous uranium accumulation are also sensitive to Eh (greater mobilisation at higher Eh), uranium content of rocks (aqueous concentration increases as rock content increases) and P CO2 (low P CO2 favours higher pH, rapid accumulation of aqueous U and earlier saturation with respect to uranium minerals). Copyright © 2017 Elsevier Ltd. All rights reserved.

Assessing Methane in Shallow Groundwater in Unconventional Oil and Gas Play Areas, Eastern Kentucky.

PubMed

Zhu, Junfeng; Parris, Thomas M; Taylor, Charles J; Webb, Steven E; Davidson, Bart; Smath, Richard; Richardson, Stephen D; Molofsky, Lisa J; Kromann, Jenna S; Smith, Ann P

2018-05-01

The expanding use of horizontal drilling and hydraulic fracturing technology to produce oil and gas from tight rock formations has increased public concern about potential impacts on the environment, especially on shallow drinking water aquifers. In eastern Kentucky, horizontal drilling and hydraulic fracturing have been used to develop the Berea Sandstone and the Rogersville Shale. To assess baseline groundwater chemistry and evaluate methane detected in groundwater overlying the Berea and Rogersville plays, we sampled 51 water wells and analyzed the samples for concentrations of major cations and anions, metals, dissolved methane, and other light hydrocarbon gases. In addition, the stable carbon and hydrogen isotopic composition of methane (δ 13 C-CH 4 and δ 2 H-CH 4 ) was analyzed for samples with methane concentration exceeding 1 mg/L. Our study indicates that methane is a relatively common constituent in shallow groundwater in eastern Kentucky, where methane was detected in 78% of the sampled wells (40 of 51 wells) with 51% of wells (26 of 51 wells) exhibiting methane concentrations above 1 mg/L. The δ 13 C-CH 4 and δ 2 H-CH 4 ranged from -84.0‰ to -58.3‰ and from -246.5‰ to -146.0‰, respectively. Isotopic analysis indicated that dissolved methane was primarily microbial in origin formed through CO 2 reduction pathway. Results from this study provide a first assessment of methane in the shallow aquifers in the Berea and Rogersville play areas and can be used as a reference to evaluate potential impacts of future horizontal drilling and hydraulic fracturing activities on groundwater quality in the region. © 2017, National Ground Water Association.

Environmental factors controlling transient and seasonal changes of trace gases within shallow vadose zone

NASA Astrophysics Data System (ADS)

Pla, Concepcion; Galiana-Merino, Juan Jose; Cuezva, Soledad; Fernandez-Cortes, Angel; Garcia-Anton, Elena; Cuevas, Jaime; Cañaveras, Juan Carlos; Sanchez-Moral, Sergio; Benavente, David

2014-05-01

Shallow vadose environments below soil, mainly caves, show significant seasonal and even daily variations in gas composition of ground air, which involves the exchange of large amounts of gases, e.g. greenhouse gases (GHGs) as CO2 or CH4, with the lower troposphere. To understand better the role of caves as a sink or depot of GHGs, geochemical tracing of air (atmosphere, soil and ground air) was performed at Rull cave (southeast Spain) by monitoring CH4, CO2 and the stable carbon isotopic delta13C[CO2] using cavity ring-down spectroscopy (CRDS). A comprehensive microclimatic monitoring of exterior and cave atmosphere was simultaneously conducted to GHGs-tracking, including factors as temperature, barometric pressure, relative humidity and concentration of CO2 and 222Rn. The analysis of the measured data allows understanding outgassing and isolation processes taking place in the karst cavity. Annual patterns of gases behaviour can be distinguished, depending on the prevailing relationship between outer atmosphere, indoor atmosphere and soil system. Cave air temperature fluctuates around 15.7 ºC and relative humidity remains higher than 96% the whole annual cycle. The mean concentration of 222Rn is 1584 Bq m-3 while CO2 remains 1921 ppm. When external temperature is higher of indoor temperature (April-October), the highest levels of both trace gases are reached, while levels drop to its lowest values in the coldest months. Preliminary results obtained show an annual variation in concentration of CO2 inside the cave between 3300 ppm and 900 ppm, whereas corresponding isotopic signal delta13CO2 varies between -24‰ and -21‰. The results have been studied by Keeling model that approximates the isotopic signal of the source contribution in a resulting air mix. The values registered inside the cave were represented joined to results for exterior air (average values round 410 ppm of CO2 and -9 ‰ for delta13C). Value obtained is -27‰ pointing to a high influence of the soil produced CO2 (with a characteristic signal of -27‰ for C3 plants) in the cave atmosphere. The lowest levels of CO2 coincide with the highest of delta13C pointing to an input of exterior air during the degassing stage. Regarding the CH4 concentration inside the cave, higher values (0.3 ppm average concentration) are observed during outgassing stage than the isolation period (CH4 mean value of 0 ppm), confirming a major connection with the exterior atmosphere (average value of methane 1.8 ppm) during outgassing stage. By introducing wavelet analysis on obtained time series filtered signal of raw data show strong dependencies between trace gases and studied parameters. For instance, values of coherence between relative humidity and CO2 or 222Rn concentration are higher than 0.9. Results show that gas patterns dependence on relative humidity, atmospheric pressure and temperatures (indoor and outdoor) prevails throughout a year, determining the outgassing and isolation periods identified by statistical analyses. The measured of delta13C and CH4 concentration became a useful tool to understand processes affecting cave air and driving parameters variations inside the cave. Moreover, combining wavelet analysis, statistics and resemblance techniques, seasonal and transient behaviour of gases exchange can be highlighted in subterranean sites as Rull Cave.

Chemistry and Environments of Dolomitization —A Reappraisal

NASA Astrophysics Data System (ADS)

Machel, Hans-G.; Mountjoy, Eric W.

1986-05-01

Dolomitization of calcium carbonate can best be expressed by mass transfer reactions that allow for volume gain, preservation, or loss during the replacement process. Experimental data, as well as textures and porosities of natural dolomites, indicate that these reactions must include CO 32- and/or HCO 3- supplied by the solution to the reaction site. Since dolomite formation is thermodynamically favoured in solutions of (a) low Ca 2+/Mg 2+ ratios, (b) low Ca 2+/CO 32- (or Ca 2+/HCO 3-) ratios, and (c) high temperatures, the thermodynamic stability for the system calcite-dolomite-water is best represented in a diagram with these three parameters as axes. Kinetic considerations favour dolomitization under the same conditions, and additionally at low as well as at high salinities. If thermodynamic and kinetic considerations are combined, the following conditions and environments are considered chemically conducive to dolomitization: (1) environments of any salinity above thermodynamic and kinetic saturation with respect to dolomite (i.e. freshwater/seawater mixing zones, normal saline to hypersaline subtidal environments, hypersaline supratidal environments, schizohaline environments); (2) alkaline environments (i.e. those under the influence of bacterial reduction and/or fermentation processes, or with high input of alkaline continental groundwaters); and (3) many environments with temperatures greater than about 50°C (subsurface and hydrothermal environments). Whether or not massive, replacive dolostones are formed in these environments depends on a sufficient supply of magnesium, and thus on hydrologic parameters. Most massive dolostones, particularly those consisting of shallowing-upward cycles and capped by regional unconformities, have been interpreted to be formed according to either the freshwater/seawater mixing model or the sabkha with reflux model. However, close examination of natural mixing zones and exposed evaporitic environments reveals that the amounts of dolomite formed are small and texturally different from the massive, replacive dolostones commonly inferred to have been formed in these environments. Many shallowing-upward sequences are devoid of dolomite. It is therefore suggested that massive, replacive dolomitization during exposure is rare, if not impossible. Rather, only small quantities of dolomite (cement or replacement) are formed which may act as nuclei for later subsurface dolomitization. Alternatively, large-scale dolomitization may take place in shallow subtidal environments of moderate to strong hypersalinity. The integration of stratigraphic, petrographic, geochemical, and hydrological parameters suggests that the only environments capable of forming massive, replacive dolostones on a large scale are shallow, hypersaline subtidal environments and certain subsurface environments.

Global Distribution of Shallow Water on Mars: Neutron Mapping of Summer-Time Surface by HEND/Odyssey

NASA Technical Reports Server (NTRS)

Mitrofanov, I. G.; Litvak, M. L.; Kozyrev, A. S.; Sanin, A. B.; Tretyakov, V. I.; Boynton, W.; Hamara, D.; Shinohara, C.; Saunders, R. S.; Drake, D.

2003-01-01

Orbital mapping of induced neutrons and gamma-rays by Odyssey has recently successfully proven the applicability of nuclear methods for studying of the elementary composition of Martian upper-most subsurface. In particular, the suite of Gamma-Ray Spectrometer (GRS) has discovered the presence of large water-ice rich regions southward and northward on Mars. The data of neutron mapping of summer-time surface are presented below from the Russian High Energy Neutron Spectrometer (HEND), which is a part of GRS suite. These maps represent the content of water in the soil for summer season at Southern and Northern hemispheres, when the winter deposit of CO2 is absent on the surface. The seasonal evolution of CO2 coverage on Mars is the subject of the complementary paper.

Thoracoscopic CO laser coagulation shrinkage of blebs in treatment of spontaneous pneumothorax

NASA Astrophysics Data System (ADS)

Sensaki, Koji; Arai, Tsunenori; Kikuchi, Keiichi; Takagi, Keigo; Tanaka, Susumu; Kikuchi, Makoto

1992-06-01

Spontaneous pneumothorax is a common disease in young people. Operative intervention has been done in most of the recurrent cases. Recently thoracoscopic treatment has been tested as a less invasive treatment modarity. We adopted carbon monoxide (CO) laser for thoracoscopic treatment of recurrent spontaneous pneumothorax. CO laser (wavelength; 5.4 micrometers ) could be delivered by chalcogenide glass (As - S) covered with a teflon sheath and ZnSe fiber tip. The sterilized flexible bronchoscope was inserted through the thoracoscopic outer sheath under local anesthesia. Shrinkage of blebs was obtained by non-contact method of CO laser irradiation. Laser power at the tip was 2.5 - 5 W and irradiation duration was 0.5 s each. Excellent shrinkage of bleb and bulla could be obtained by CO laser without perforation complication. Advantages of CO laser as a thoracoscopic treatment were: (1) capability of fiber delivery (flexible thoracoscopy was easy to operate and clear to visualize the blebs which were frequently found at the apical portion of the lung, and (2) shallow extinction length (good shrinkage of blebs, low risk of perforation, and thin layer of carbonization). In conclusion, our new technique of thoracoscopic CO laser irradiation was found to be a safe and effective treatment of spontaneous pneumothorax.

Improving the Ginkgo CO2 barometer: Implications for the early Cenozoic atmosphere

NASA Astrophysics Data System (ADS)

Barclay, Richard S.; Wing, Scott L.

2016-04-01

Stomatal properties of fossil Ginkgo have been used widely to infer the atmospheric concentration of CO2 in the geological past (paleo-pCO2). Many of these estimates of paleo-pCO2 have relied on the inverse correlation between pCO2 and stomatal index (SI - the proportion of epidermal cells that are stomata) observed in recent Ginkgo biloba, and therefore depend on the accuracy of this relationship. The SI - pCO2 relationship in G. biloba has not been well documented, however. Here we present new measurements of SI for leaves of G. biloba that grew under pCO2 from 290 to 430 ppm. We prepared and imaged all specimens using a consistent procedure and photo-documented each count. As in prior studies, we found a significant inverse relationship between SI and pCO2, however, the relationship is more linear, has a shallower slope, and a lower correlation coefficient than previously reported. We examined leaves of G. biloba grown under pCO2 of 1500 ppm, but found they had highly variable SI and a large proportion of malformed stomata. We also measured stomatal dimensions, stomatal density, and the carbon isotope composition of G. biloba leaves in order to test a mechanistic model for inferring pCO2. This model overestimated observed pCO2, performing less well than the SI method between 290 and 430 ppm. We used our revised SI-pCO2 response curve, and new observations of selected fossils, to estimate late Cretaceous and Cenozoic pCO2 from fossil Ginkgo adiantoides. All but one of the new estimates is below 800 ppm, and together they show little long-term change in pCO2 or relation to global temperature. The low Paleogene pCO2 levels indicated by the Ginkgo SI proxy are not consistent with the high pCO2 inferred by some climate and carbon cycle models. We cannot currently resolve the discrepancy, but greater agreement between proxy data and models may come from a better understanding of the stomatal response of G. biloba to elevated pCO2, better counts and measurements of fossil Ginkgo, or models that can simulate greenhouse climates at lower pCO2.

Limitations to CO2-induced growth enhancement in pot studies.

PubMed

McConnaughay, K D M; Berntson, G M; Bazzaz, F A

1993-07-01

Recently, it has been suggested that small pots may reduce or eliminate plant responses to enriched CO 2 atmospheres due to root restriction. While smaller pot volumes provide less physical space available for root growth, they also provide less nutrients. Reduced nutrient availability alone may reduce growth enhancement under elevated CO 2 . To investigate the relative importance of limited physical rooting space separate from and in conjunction with soil nutrients, we grew plants at ambient and double-ambient CO 2 levels in growth containers of varied volume, shape, nutrient concentration, and total nutrient content. Two species (Abutilon theophrasti, a C 3 dicot with a deep tap root andSetaria faberii, a C 4 monocot with a shallow diffuse root system) were selected for their contrasting physiology and root architecture. Shoot demography was determined weekly and biomass was determined after eight and ten weeks of growth. Increasing total nutrients, either by increasing nutrient concentration or by increasing pot size, increased plant growth. Further, increasing pot size while maintaining equal total nutrients per pot resulted in increased total biomass for both species. CO 2 -induced growth and reproductive yield enhancements were greatest in pots with high nutrient concentrations, regardless of total nutrient content or pot size, and were also mediated by the shape of the pot. CO 2 -induced growth and reproductive yield enhancements were unaffected by pot size (growth) or were greater in small pots (reproductive yield), regardless of total nutrient content, contrary to predictions based on earlier studies. These results suggest that several aspects of growth conditions within pots may influence the CO 2 responses of plants; pot size, pot shape, the concentration and total amount of nutrient additions to pots may lead to over-or underestimates of the CO 2 responses of real-world plants.

Liquid carbon dioxide of magmatic origin and its role in volcanic eruptions

USGS Publications Warehouse

Chivas, A.R.; Barnes, I.; Evans, William C.; Lupton, J.E.; Stone, J.O.

1987-01-01

Natural liquid carbon dioxide is produced commercially from a 2.5-km-deep well near the 4,500-yr-old maar volcano, Mount Gambier, South Australia. The carbon dioxide has accumulated in a dome that is located on the extension of a linear chain of volcanic activity. A magmatic origin for the fluid is suggested by the geological setting, ??13CPDB of -4.0???, for the CO2 (where PDB represents the carbon-isotope standard), and a relatively high 3He component of the contained helium and high 3He/C ratio (6.4 x 10-10). The 3He/ 4He and He/Ne ratios are 3.0 and > 1,370 times those of air, respectively. The CO2, as collected at the Earth's surface at 29.5 ??C and 75 bar, expands more than 300-fold to form a gas at 1 atm and 22 ??C. We suggest that liquid CO2 or high-density CO2 fluid (the critical point is 31.1 ??C, 73.9 bar) of volcanic origin that expands explosively from shallow levels in the Earth's crust may be a major contributor to 'phreatic' volcanic eruptions and maar formation. Less violent release of magmatic CO2 into crater lakes may cause gas bursts with equally disastrous consequences such as occurred at Lake Nyos, Cameroon, in August 1986. ?? 1987 Nature Publishing Group.

Advective, Diffusive and Eruptive Leakage of CO2 and Brine within Fault Zone

NASA Astrophysics Data System (ADS)

Jung, N. H.; Han, W. S.

2014-12-01

This study investigated a natural analogue for CO2 leakage near the Green River, Utah, aiming to understand the influence of various factors on CO2 leakage and to reliably predict underground CO2 behavior after injection for geologic CO2 sequestration. Advective, diffusive, and eruptive characteristics of CO2 leakage were assessed via a soil CO2 flux survey and numerical modeling. The field results show anomalous CO2 fluxes (> 10 g m-2 d-1) along the faults, particularly adjacent to CO2-driven cold springs and geysers (e.g., 36,259 g m-2 d-1 at Crystal Geyser), ancient travertines (e.g., 5,917 g m-2 d-1), joint zones in sandstone (e.g., 120 g m-2 d-1), and brine discharge zones (e.g., 5,515 g m-2 d-1). Combined to similar isotopic ratios of gas and progressive evolution of brine chemistry at springs and geysers, a gradual decrease of soil CO2 flux from the Little Grand Wash (LGW; ~36,259 g m-2 d-1) to Salt Wash (SW; ~1,428 g m-2 d-1) fault zones reveals the same CO2 origin and potential southward transport of CO2 over 10-20 km. The numerical simulations overtly exhibit lateral transport of free CO2 and CO2-rich brine from the LGW to SW fault zones through the regional aquifers (e.g., Entrada, Navajo, Kayenta, Wingate, White Rim). CO2 travels predominantly as an aqueous phase (Xco2=~0.045) as previously suggested, giving rise to the convective instability that further accelerates CO2 dissolution. While the buoyant free CO2 always tends to ascend, a fraction of dense CO2-rich brine flows laterally into the aquifer and mixes with the formation fluids during upward migration along the fault. The fault always enhances advective CO2 transport regardless of its permeability (k). However, only the low-k fault scenario engenders development of CO2 anticlinal trap within the shallow aquifers (Entrada and Navajo), concentrating high CO­­­2 fluxes (~1,273 g m-2 d-1) within the northern footwall of the LGW fault similar to the field. Moreover, eruptive CO2 leakage at a well (Crystal Geyser) solely appears under the presence of anticlinal trap. Thus, it can be concluded that the LGW fault is likely low-permeable, 0.01 md ≤ kh <0.1 md and 0.5 md ≤ kv < 1 md, which could be used as a good starting point for other studies and further improved.

Monitoring Conformance and Containment for Geological Carbon Storage: Can Technology Meet Policy and Public Requirements?

NASA Astrophysics Data System (ADS)

Lawton, D. C.; Osadetz, K.

2014-12-01

The Province of Alberta, Canada identified carbon capture and storage (CCS) as a key element of its 2008 Climate Change strategy. The target is a reduction in CO2 emissions of 139 Mt/year by 2050. To encourage uptake of CCS by industry, the province has provided partial funding to two demonstration scale projects, namely the Quest Project by Shell and partners (CCS), and the Alberta Carbon Trunk Line Project (pipeline and CO2-EOR). Important to commercial scale implementation of CCS will be the requirement to prove conformance and containment of the CO2 plume injected during the lifetime of the CCS project. This will be a challenge for monitoring programs. The Containment and Monitoring Institute (CaMI) is developing a Field Research Station (FRS) to calibrate various monitoring technologies for CO2 detection thresholds at relatively shallow depths. The objective being assessed with the FRS is sensitivity for early detection of loss of containment from a deeper CO2 storage project. In this project, two injection wells will be drilled to sandstone reservoir targets at depths of 300 m and 700 m. Up to four observation wells will be drilled with monitoring instruments installed. Time-lapse surface and borehole monitoring surveys will be undertaken to evaluate the movement and fate of the CO2 plume. These will include seismic, microseismic, cross well, electrical resistivity, electromagnetic, gravity, geodetic and geomechanical surveys. Initial baseline seismic data from the FRS will presented.

Southwestern Regional Partnership For Carbon Sequestration (Phase 2) Pump Canyon CO2- ECBM/Sequestration Demonstration, San Juan Basin, New Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Advanced Resources International

2010-01-31

Within the Southwest Regional Partnership on Carbon Sequestration (SWP), three demonstrations of geologic CO{sub 2} sequestration are being performed -- one in an oilfield (the SACROC Unit in the Permian basin of west Texas), one in a deep, unmineable coalbed (the Pump Canyon site in the San Juan basin of northern New Mexico), and one in a deep, saline reservoir (underlying the Aneth oilfield in the Paradox basin of southeast Utah). The Pump Canyon CO{sub 2}-enhanced coalbed methane (CO{sub 2}/ECBM) sequestration demonstration project plans to demonstrate the effectiveness of CO{sub 2} sequestration in deep, unmineable coal seams via a small-scalemore » geologic sequestration project. The site is located in San Juan County, northern New Mexico, just within the limits of the high-permeability fairway of prolific coalbed methane production. The study area for the SWP project consists of 31 coalbed methane production wells located in a nine section area. CO{sub 2} was injected continuously for a year and different monitoring, verification and accounting (MVA) techniques were implemented to track the CO{sub 2} movement inside and outside the reservoir. Some of the MVA methods include continuous measurement of injection volumes, pressures and temperatures within the injection well, coalbed methane production rates, pressures and gas compositions collected at the offset production wells, and tracers in the injected CO{sub 2}. In addition, time-lapse vertical seismic profiling (VSP), surface tiltmeter arrays, a series of shallow monitoring wells with a regular fluid sampling program, surface measurements of soil composition, CO{sub 2} fluxes, and tracers were used to help in tracking the injected CO{sub 2}. Finally, a detailed reservoir model was constructed to help reproduce and understand the behavior of the reservoir under production and injection operation. This report summarizes the different phases of the project, from permitting through site closure, and gives the results of the different MVA techniques.« less

Integrated geophysical and hydrothermal models of flank degassing and fluid flow at Masaya Volcano, Nicaragua

USGS Publications Warehouse

Sanford, Ward E.; Pearson, S.C.P.; Kiyosugi, K.; Lehto, H.L.; Saballos, J.A.; Connor, C.B.

2012-01-01

We investigate geologic controls on circulation in the shallow hydrothermal system of Masaya volcano, Nicaragua, and their relationship to surface diffuse degassing. On a local scale (~250 m), relatively impermeable normal faults dipping at ~60° control the flowpath of water vapor and other gases in the vadose zone. These shallow normal faults are identified by modeling of a NE-SW trending magnetic anomaly of up to 2300 nT that corresponds to a topographic offset. Elevated SP and CO2 to the NW of the faults and an absence of CO2 to the SE suggest that these faults are barriers to flow. TOUGH2 numerical models of fluid circulation show enhanced flow through the footwalls of the faults, and corresponding increased mass flow and temperature at the surface (diffuse degassing zones). On a larger scale, TOUGH2 modeling suggests that groundwater convection may be occurring in a 3-4 km radial fracture zone transecting the entire flank of the volcano. Hot water rising uniformly into the base of the model at 1 x 10-5 kg/m2s results in convection that focuses heat and fluid and can explain the three distinct diffuse degassing zones distributed along the fracture. Our data and models suggest that the unusually active surface degassing zones at Masaya volcano can result purely from uniform heat and fluid flux at depth that is complicated by groundwater convection and permeability variations in the upper few km. Therefore isolating the effects of subsurface geology is vital when trying to interpret diffuse degassing in light of volcanic activity.

Investigating controls on boron isotope ratios in shallow marine carbonates

NASA Astrophysics Data System (ADS)

Zhang, Shuang; Henehan, Michael J.; Hull, Pincelli M.; Reid, R. Pamela; Hardisty, Dalton S.; Hood, Ashleigh v. S.; Planavsky, Noah J.

2017-01-01

The boron isotope-pH proxy has been widely used to reconstruct past ocean pH values. In both planktic foraminifera and corals, species-specific calibrations are required in order to reconstruct absolute values of pH, due to the prevalence of so-called vital effects - physiological modification of the primary environmental signals by the calcifying organisms. Shallow marine abiotic carbonate (e.g. ooids and cements) could conceivably avoid any such calibration requirement, and therefore provide a potentially useful archive for reconstructions in deep (pre-Cenozoic) time. However, shallow marine abiotic carbonates could also be affected by local shifts in pH caused by microbial photosynthesis and respiration, something that has up to now not been fully tested. In this study, we present boron isotope measurements from shallow modern marine carbonates, from the Bahama Bank and Belize to investigate the potential of using shallow water carbonates as pH archives, and to explore the role of microbial processes in driving nominally 'abiogenic' carbonate deposition. For Bahama bank samples, our boron-based pH estimates derived from a range of carbonate types (i.e. ooids, peloids, hardground cements, carbonate mud, stromatolitic micrite and calcified filament micrite) are higher than the estimated modern mean-annual seawater pH values for this region. Furthermore, the majority (73%) of our marine carbonate-based pH estimates fall out of the range of the estimated pre-industrial seawater pH values for this region. In shallow sediment cores, we did not observe a correlation between measured pore water pH and boron-derived pH estimates, suggesting boron isotope variability is a depositional rather than early diagenetic signal. For Belize reef cements, conversely, the pH estimates are lower than likely in situ seawater pH at the time of cement formation. This study indicates the potential for complications when using shallow marine non-skeletal carbonates as marine pH archives. In addition, variability in δ11B based pH estimates provides additional support for the idea that photosynthetic CO2 uptake plays a significant role in driving carbonate precipitation in a wide range of shallow water carbonates.

Brucite microbialites in living coral skeletons: Indicators of extreme microenvironments in shallow-marine settings

USGS Publications Warehouse

Nothdurft, L.D.; Webb, G.E.; Buster, N.A.; Holmes, C.W.; Sorauf, J.E.; Kloprogge, J.T.

2005-01-01

Brucite [Mg(OH)2] microbialites occur in vacated interseptal spaces of living scleractinian coral colonies (Acropora, Pocillopora, Porites) from subtidal and intertidal settings in the Great Barrier Reef, Australia, and subtidal Montastraea from the Florida Keys, United States. Brucite encrusts microbial filaments of endobionts (i.e., fungi, green algae, cyanobacteria) growing under organic biofilms; the brucite distribution is patchy both within interseptal spaces and within coralla. Although brucite is undersaturated in seawater, its precipitation was apparently induced in the corals by lowered pCO 2 and increased pH within microenvironments protected by microbial biofilms. The occurrence of brucite in shallow-marine settings highlights the importance of microenvironments in the formation and early diagenesis of marine carbonates. Significantly, the brucite precipitates discovered in microenvironments in these corals show that early diagenetic products do not necessarily reflect ambient seawater chemistry. Errors in environmental interpretation may arise where unidentified precipitates occur in microenvironments in skeletal carbonates that are subsequently utilized as geochemical seawater proxies. ?? 2005 Geological Society of America.

High resolution shallow co-seismic and post-seismic slip from the 2016 central Italy earthquake sequence captured using terrestrial laser scanning, structure from motion and low-cost near-field GNSS

NASA Astrophysics Data System (ADS)

Wedmore, L. N. J.; Gregory, L. C.; McCaffrey, K. J. W.; Wilkinson, M.; Walters, R. J.

2017-12-01

Coseismic fault slip in the shallow crust is poorly constrained by many of the conventional tools used to record deformation during earthquakes. GNSS stations are often distributed too far from faults and radar images tend to decorrelate across earthquake surface ruptures. As a result, our understanding of near-field fault slip, shallow slip deficits, and off-fault deformation is limited. We present evidence from the 2016 central Italy earthquake sequence, during which we captured shallow coseismic and post-seismic slip using a combination of terrestrial laser scanning (TLS), structure-from-motion (SfM), and near-field low-cost GNSS recording at 1Hz. Three Mw>6 earthquakes on the 24th August, 26th and 30th October all involved slip on the Mt Vettore-Mt Bove fault system. We collected TLS and SfM point clouds across three separate segments of this system. Each segment experienced a different record of slip during the earthquake sequence; all three ruptured in the largest event (Mw 6.6. on October 30th) but two segments also ruptured during either the 24th August or the 26th October earthquakes. Following the Mw 6.6 earthquake, the faults were repeatedly surveyed using TLS, with the first scan collected c. 5 hours following the earthquake. This represents the first known instance where shallow co-seismic slip has been recorded by pre- and post-event terrestrial laser scanning. Displacement continuously measured across GNSS pairs at 1 Hz demonstrates that permanent near field displacement developed across the fault in the immediate seconds following the initiation of the rupture. However, a discrepancy between on-fault field measurements of surface displacement and the GNSS recorded displacement over 1km long baselines hints at a more complex rupture processes and the possibility of high slip gradients in the shallow subsurface. Displacement measured by differential TLS confirms the presence of these shallow slip deficits but suggests that shallow slip gradient may be controlled by the pattern and timing of slip in the preceding earthquakes. Postseismic afterslip captured by repeated TLS surveys hints at more complicated temporal evolution of nearfield afterslip than is currently predicted by logarithmic models for this process.

Attenuation of sinking particulate organic carbon flux through the mesopelagic ocean

PubMed Central

Marsay, Chris M.; Sanders, Richard J.; Henson, Stephanie A.; Pabortsava, Katsiaryna; Achterberg, Eric P.; Lampitt, Richard S.

2015-01-01

The biological carbon pump, which transports particulate organic carbon (POC) from the surface to the deep ocean, plays an important role in regulating atmospheric carbon dioxide (CO2) concentrations. We know very little about geographical variability in the remineralization depth of this sinking material and less about what controls such variability. Here we present previously unpublished profiles of mesopelagic POC flux derived from neutrally buoyant sediment traps deployed in the North Atlantic, from which we calculate the remineralization length scale for each site. Combining these results with corresponding data from the North Pacific, we show that the observed variability in attenuation of vertical POC flux can largely be explained by temperature, with shallower remineralization occurring in warmer waters. This is seemingly inconsistent with conclusions drawn from earlier analyses of deep-sea sediment trap and export flux data, which suggest lowest transfer efficiency at high latitudes. However, the two patterns can be reconciled by considering relatively intense remineralization of a labile fraction of material in warm waters, followed by efficient downward transfer of the remaining refractory fraction, while in cold environments, a larger labile fraction undergoes slower remineralization that continues over a longer length scale. Based on the observed relationship, future increases in ocean temperature will likely lead to shallower remineralization of POC and hence reduced storage of CO2 by the ocean. PMID:25561526

SiO2-Ag-SiO2 core/shell structure with a high density of Ag nanoparticles for CO oxidation catalysis.

PubMed

Feng, Xiaoqian; Li, Hongmo; Zhang, Qing; Zhang, Peng; Song, Xuefeng; Liu, Jing; Zhao, Liping; Gao, Lian

2016-11-11

SiO 2 -Ag-SiO 2 , a sandwiched core/shell structure with a layer of Ag nanoparticles (∼4 nm) encapsulated between a shallow SiO 2 surface layer and a SiO 2 submicrosphere substrate (∼200 nm), has been synthesized from [Formula: see text] and SiO 2 spheres by a facile one-pot hydrothermal method. The composite is proposed to result from the dynamic balance between the [Formula: see text] reduction and the dissolution-redeposition of SiO 2 in mild basic media. The synthetic mechanism and the roles of the reaction time, temperature, and the amount of ammonia in the formation of this unique structure are investigated and discussed. The composite structure shows superior catalytic performance in CO oxidation to the control Ag/SiO 2 structure prepared by impregnation. Pre-treatment by O 2 at 600 °C significantly improves the catalytic performance of the composite structure and preserves the nanocomposite structure well.

Results of a hydrogeological and hydrogeochemical study of a semi-arid karst aquifer in Tezbent plateau, Tebessa region, northeast of Algeria

NASA Astrophysics Data System (ADS)

Belfar, Dalila; Fehdi, Chemseddine; Baali, Fethi; Salameh, Elias

2017-06-01

The Hammamet Plain, situated in the northwest of the Tezbent mountain range, northeast of Algeria, drains carbonate aquifers through some important karst springs. The physical and chemical characteristics of spring and well water samples were studied for 2 years to assess the origin of groundwater and determine the factors driving the geochemical composition. The ionic speciation and mineral dissolution/precipitation was calculated. Water wells, characterizing groundwater circulation at shallow depths, are moderate to high mineralized waters of Na-HCO3 type. In contrast to the shallow environment, the CO2-rich, deeper waters are of the Ca-HCO3-SO4 type and undergo significant changes in the baseline chemistry along flow lines with increasing residence time. The main factors controlling the groundwater composition and its seasonal variations are the geology, because of the presence of carbonate formations, the elevation and the rate of karst development. In both groups, the carbonate chemistry is diagnostic of the effect of karst development. The supersaturation with respect to calcite indicates CO2 degassing, occurring either inside the aquifer in open conduits, or at the outlet in reservoirs. The undersaturation with respect to calcite shows the existence of fast flow and short residence time conditions inside the aquifer. Interaction between groundwater and surrounding host rocks is believed to be the main process responsible for the observed chemical characteristics of groundwater in the study area.

Kern River steam expansion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rintoul, B.

1970-09-15

The newest addition to Getty Oil Co.'s imposing array of steam equipment at Kern River is a 240-million-btu-per-hr boiler. This boiler is almost 5 times more powerful than the previous largest piece of steam-generating hardware in use in the field. The huge boiler went into operation in Aug. on the Canfield Fee property on Sec. 29, 28S-28E. It is being used to furnish steam for 60 wells in a displacement project. The components that have made Getty Oil Co. the leading steamer at Kern River and the field, in turn, the world capital for oil-field steam operations include shallow wells,more » steam generators, and--since last year--a computer. There are more than 4,500 oil wells in the Kern River field, including more than 2,600 on Getty Oil properties. Getty Oil's steam operations involve 2,469 producing wells and 151 injection wells, including 2,167 producing wells in stimulation projects and 302 producing wells in displacement projects. The Kern River drilling program for 1970 consists of 313 wells of which 179 are steam-injection wells for the expansion of displacement projects. Wells are shallow, drilled mainly to the Kern River Series sands at an average depth of 900 ft, with a few drilled to the China Grade zone at an average depth of 1,300 ft. To furnish steam for the massive Kern River program, Getty Oil has assembled a force of 96 steam generators.« less

Temperate and tropical brown macroalgae thrive, despite decalcification, along natural CO2 gradients.

PubMed

Johnson, Vivienne R; Russell, Bayden D; Fabricius, Katharina E; Brownlee, Colin; Hall-Spencer, Jason M

2012-09-01

Predicting the impacts of ocean acidification on coastal ecosystems requires an understanding of the effects on macroalgae and their grazers, as these underpin the ecology of rocky shores. Whilst calcified coralline algae (Rhodophyta) appear to be especially vulnerable to ocean acidification, there is a lack of information concerning calcified brown algae (Phaeophyta), which are not obligate calcifiers but are still important producers of calcium carbonate and organic matter in shallow coastal waters. Here, we compare ecological shifts in subtidal rocky shore systems along CO2 gradients created by volcanic seeps in the Mediterranean and Papua New Guinea, focussing on abundant macroalgae and grazing sea urchins. In both the temperate and tropical systems the abundances of grazing sea urchins declined dramatically along CO2 gradients. Temperate and tropical species of the calcifying macroalgal genus Padina (Dictyoaceae, Phaeophyta) showed reductions in CaCO3 content with CO2 enrichment. In contrast to other studies of calcified macroalgae, however, we observed an increase in the abundance of Padina spp. in acidified conditions. Reduced sea urchin grazing pressure and significant increases in photosynthetic rates may explain the unexpected success of decalcified Padina spp. at elevated levels of CO2 . This is the first study to provide a comparison of ecological changes along CO2 gradients between temperate and tropical rocky shores. The similarities we found in the responses of Padina spp. and sea urchin abundance at several vent systems increases confidence in predictions of the ecological impacts of ocean acidification over a large geographical range. © 2012 Blackwell Publishing Ltd.

Temporal change in shallow subsurface P- and S-wave velocities and S-wave anisotropy inferred from coda wave interferometry

NASA Astrophysics Data System (ADS)

Yamamoto, M.; Nishida, K.; Takeda, T.

2012-12-01

Recent progresses in theoretical and observational researches on seismic interferometry reveal the possibility to detect subtle change in subsurface seismic structure. This high sensitivity of seismic interferometry to the medium properties may thus one of the most important ways to directly observe the time-lapse behavior of shallow crustal structure. Here, using the coda wave interferometry, we show the co-seismic and post-seismic changes in P- and S-wave velocities and S-wave anisotropy associated with the 2011 off the Pacific coast of Tohoku earthquake (M9.0). In this study, we use the acceleration data recorded at KiK-net stations operated by NIED, Japan. Each KiK-net station has a borehole whose typical depth is about 100m, and two three-component accelerometers are installed at the top and bottom of the borehole. To estimate the shallow subsurface P- and S-wave velocities and S-wave anisotropy between two sensors and their temporal change, we select about 1000 earthquakes that occurred between 2004 and 2012, and extract body waves propagating between borehole sensors by computing the cross-correlation functions (CCFs) of 3 x 3 component pairs. We use frequency bands of 2-4, 4-8, 8-16 Hz in our analysis. Each averaged CCF shows clear wave packets traveling between borehole sensors, and their travel times are almost consistent with those of P- and S-waves calculated from the borehole log data. Until the occurrence of the 2011 Tohoku earthquake, the estimated travel time at each station is rather stable with time except for weak seasonal/annual variation. On the other hand, the 2011 Tohoku earthquake and its aftershocks cause sudden decrease in the S-wave velocity at most of the KiK-net stations in eastern Japan. The typical value of S-wave velocity changes, which are measured by the time-stretching method, is about 5-15%. After this co-seismic change, the S-wave velocity gradually recovers with time, and the recovery continues for over one year following the logarithm of the lapse time. At some stations, the estimated P-wave velocity also shows co-seismic velocity decrease and subsequent gradual recovery. However, the magnitude of estimated P-wave velocity change is much smaller than that of S-wave, and at the other stations, the magnitude of P-wave velocity change is smaller than the resolution of our analysis. Using the CCFs computed from horizontal components, we also determine the seismic anisotropy in subsurface structure, and examine its temporal change. The estimated strength of anisotropy strength shows co-seismic increase at most of stations where co-seismic velocity change is detected. Nevertheless, the direction of anisotropy after the 2011 Tohoku earthquake stays about the same as before. These results suggest that, in addition to the change in pore pressure and corresponding decrease in the rigidity, the change in the aspect ratio of pre-existing subsurface fractures/micro-crack may be another key mechanism causing the co-seismic velocity change in shallow subsurface structures.

Oxygen Fugacity Variation From Mantle Transition Zone To Ocean Ridges Recorded By In Situ Diamond-Bearing Peridotite Of Indus Ophiolite

NASA Astrophysics Data System (ADS)

Das, S.; Basu, A. R.

2017-12-01

Our recently discovered transition zone ( 410 - 660 Km) -derived peridotites in the Indus Ophiolite, Ladakh Himalaya [1] provide a unique opportunity to study changes in oxygen fugacity from shallow mantle beneath ocean ridges to mantle transition zone. We found in situ diamond, graphite pseudomorphs after diamond crystals, hydrocarbon (C - H) and hydrogen (H2) fluid inclusions in ultra-high pressure (UHP) peridotites that occur in the mantle - section of the Indus ophiolite and sourced from the mantle transition zone [2]. Diamond occurs as octahedral inclusion in orthoenstatite of one of these peridotites. The graphite pseudomorphs after diamond crystals and primary hydrocarbon (C-H), and hydrogen (H2) fluids are included in olivine of this rock. Hydrocarbon fluids are also present as inclusions in high pressure clinoenstatite (> 8 GPa). The association of primary hydrocarbon and hydrogen fluid inclusions in the UHP peridotites suggest that their source-environment was highly reduced at the base of the upper mantle. We suggest that during mantle upwelling beneath Neo Tethyan spreading center, the hydrocarbon fluid was oxidized and precipitated diamond. The smaller diamonds converted to graphite at shallower depth due to size, high temperature and elevated oxygen fugacity. This process explains how deep mantle upwelling can oxidize reduced fluid carried from the transition zone to produce H2O - CO2. The H2O - CO2 fluids induce deep melting in the source of the mid oceanic ridge basalts (MORB) that create the oceanic crust. References: [1] Das S, Mukherjee B K, Basu A R, Sen K, Geol Soc London, Sp 412, 271 - 286; 2015. [2] Das S, Basu A R, Mukherjee B K, Geology 45 (8), 755 - 758; 2017.

Potential for intrinsic bioremediation of a DNT-contaminated aquifer

USGS Publications Warehouse

Bradley, P.M.; Chapelle, F.H.; Landmeyer, J.E.; Schumacher, J.G.

1997-01-01

Microorganisms indigenous to a shallow aquifer, which underlies an explosives-contaminated site, mineralized 28% of [U-ring-14C] 2,4–dinitrotoluene to 14CO2 within 28 days under aerobic conditions. Approximately 20% of added 2,4–dinitrotoluene remained undegraded at the end of the incubation while approximately 22% and 6% were transformed to 4–amino-2–nitrotoluene and 2–amino-4–nitrotoluene, respectively. In aquifer microcosms containing 2,6–dinitrotoluene, approximately 67% of the substrate remained undegraded and approximately 14% was transformed to 2–amino-6–nitrotoluene. The radiolabeled study indicated that about 8% of the 2,6–dinotrotoluene was mineralized to CO2. The demonstrated degradation and subsequent mineralization of dinitrotoluene compounds by aquifer microorganisms are consistent with the decline in dissolved dinitrotoluene concentrations observed along the general ground-water flowpath at the site. The results indicate that intrinsic bioremediation may be a viable alternative for remediating contaminated ground water at this site.

Monitoring CO2 emissions in tree kill areas near the resurgent dome at Long Valley Caldera, California

USGS Publications Warehouse

Bergfeld, D.; Evans, William C.

2011-01-01

We report results of yearly measurements of the diffuse CO2 flux and shallow soil temperatures collected since 2006 across two sets of tree-kill areas at Long Valley Caldera, California. These data provide background information about CO2 discharge during a period with moderate seismicity, but little to no deformation. The tree kills are located at long-recognized areas of weak thermal fluid upflow, but have expanded in recent years, possibly in response to geothermal fluid production at Casa Diablo. The amount of CO2 discharged from the older kill area at Basalt Canyon is fairly constant and is around 3-5 tonnes of CO2 per day from an area of about 15,000 m2. The presence of isobutane in gas samples from sites in and around Basalt Canyon suggests that geothermal fluid production directly effects fluid upflow in the region close to the power plant. The average fluxes at Shady Rest are lower than average fluxes at Basalt Canyon, but the area affected by fluid upflow is larger. Total CO2 discharged from the central portion of the kill area at Shady Rest has been variable, ranging from 6 to11 tonnes per day across 61,000 m2. Gas collected at Shady Rest contains no detectable isobutane to link emissions chemically to geothermal fluid production, but two samples from 2009-10 have detectable H2S and suggest an increasing geothermal character of emitted gas. The appearance of this gas at the surface may signal increased drawdown of water levels near the geothermal productions wells.

2D and 3D high resolution seismic imaging of shallow Solfatara crater in Campi Flegrei (Italy): new insights on deep hydrothermal fluid circulation processes

NASA Astrophysics Data System (ADS)

De Landro, Grazia; Gammaldi, Sergio; Serlenga, Vincenzo; Amoroso, Ortensia; Russo, Guido; Festa, Gaetano; D'Auria, Luca; Bruno, Pier Paolo; Gresse, Marceau; Vandemeulebrouck, Jean; Zollo, Aldo

2017-04-01

Seismic tomography can be used to image the spatial variation of rock properties within complex geological media such as volcanoes. Solfatara is a volcano located within the Campi Flegrei still active caldera, characterized by periodic episodes of extended, low-rate ground subsidence and uplift called bradyseism accompanied by intense seismic and geochemical activities. In particular, Solfatara is characterized by an impressive magnitude diffuse degassing, which underlines the relevance of fluid and heat transport at the crater and prompted further research to improve the understanding of the hydrothermal system feeding the surface phenomenon. In this line, an active seismic experiment, Repeated Induced Earthquake and Noise (RICEN) (EU Project MEDSUV), was carried out between September 2013 and November 2014 to provide time-varying high-resolution images of the structure of Solfatara. In this study we used the datasets provided by two different acquisition geometries: a) A 2D array cover an area of 90 x 115 m ^ 2 sampled by a regular grid of 240 vertical sensors deployed at the crater surface; b) two 1D orthogonal seismic arrays deployed along NE-SW and NW-SE directions crossing the 400 m crater surface. The arrays are sampled with a regular line of 240 receiver and 116 shots. We present 2D and 3D tomographic high-resolution P-wave velocity images obtained using two different tomographic methods adopting a multiscale strategy. The 3D image of the shallow (30-35 m) central part of Solfatara crater is performed through the iterative, linearized, tomographic inversion of the P-wave first arrival times. 2D P-wave velocity sections (60-70 m) are obtained using a non-linear travel-time tomography method based on the evaluation of a posteriori probability density with a Bayesian approach. The 3D retrieved images integrated with resistivity section and temperature and CO2 flux measurements , define the following characteristics: 1. A depth dependent P-wave velocity layer down to 14 m, with Vp<700m/s typical of poorly-consolidated tephra and affected by CO2 degassing; 2. An intermediate layer, deepening towards the mineralized liquid-saturated area (Fangaia), interpreted as permeable deposits saturated with condensed water; 3. A deep, confined high velocity anomaly associated with a CO2 reservoir. With the 2D profiles we can image up to around 70 m depth: the first 30 m are characterized by features and velocities comparable to those of the 3D profiles, deeper, between 40-60 m depth, were found two low velocity anomalies, that probably indicate a preferential via for fluid degassing. These features are expression of an area located between the Fangaia, which is water saturated and replenished from deep aquifers, and the main fumaroles that are the superficial relief of deep rising CO2 flux. So, the changes in the outgassing rate greatly affects the shallow hydrothermal system, which can be used as a near-surface "mirror" of fluid migration processes occurring at greater depths.

Implementation of Free-Formulation-Based Flat Shell Elements into NASA Comet Code and Development of Nonlinear Shallow Shell Element

NASA Technical Reports Server (NTRS)

Barut, A.; Madenci, Erdogan; Tessler, A.

1997-01-01

This study presents a transient nonlinear finite element analysis within the realm of a multi-body dynamics formulation for determining the dynamic response of a moderately thick laminated shell undergoing a rapid and large rotational motion and nonlinear elastic deformations. Nonlinear strain measure and rotation, as well as 'the transverse shear deformation, are explicitly included in the formulation in order to capture the proper motion-induced stiffness of the laminate. The equations of motion are derived from the virtual work principle. The analysis utilizes a shear deformable shallow shell element along with the co-rotational form of the updated Lagrangian formulation. The shallow shell element formulation is based on the Reissner-Mindlin and Marguerre theory.

Oxygenation of the shallow ocean after the Great Oxidation Event: Geochemistry and Carbon isotopes of the Paleoproterozoic Hutuo Group in North China Craton

NASA Astrophysics Data System (ADS)

She, Z.; Yang, F.; Papineau, D.

2013-12-01

The Paleoproterozoic was known as a period of profound perturbations in marine environments and biogeochemical cycles due to the Great Oxidation Event (GOE), but the interconnections and consequences of these events remain poorly understood. We investigated the geochemistry and C isotopes of the 2.09-1.96 Ga Hutuo Group in the North China Craton (NCC) which provide evidence for the oxygenation of shallow oceans. The Hutuo Group is a >10-km-thick clastic and carbonate sequence with intercalated basalts and has undergone lower greenschist facies metamorphism. Diverse stromatolite morphotypes, ranging from small domical, conical, and columnar forms to bioherms with diameters up to 4 meters, as well as giant oncoids, are developed in the Hutuo carbonates. C isotopes of the Hutuo carbonates are characterized by a general decrease in δ13Ccarb values upsection. It consists of a lower part with δ13Ccarb ranging from 1.3 ‰ to 3.4 ‰, a middle part showing alternating positive and negative excursions of δ13Ccarb from -3.6 ‰ to 2.7 ‰, and a upper part of exclusively negative excursions with δ13Ccarb as light as -5.6 ‰. Most samples have δ18Ocarb greater than -10 ‰ and show no correlation between δ18Ocarb and δ13Ccarb. This, along with relatively low Mn/Sr ratios (mostly < 10), exclude significant diagenetic modification of the C isotopes. δ13Corg of acid-insoluble residues of stromatolitic carbonates range between -30.9 ‰ and -22.3 ‰, consistent with C-fixation with the cyanobacterial RuBisCO enzymes. Therefore, the positive excursions are probably related to burial of organic matter produced by primary producers, consistent with the ending of the 2.22-2.06 Ga Lomagundi-Jatuli event. Similar positive C isotope excursions have also been reported from contemporaneous successions elsewhere in the NCC, including the Songshan Group in Henan and Liaohe Group in Liaoning. The following negative excursions, which is consistent with the excursions reported from the 2.1-2.0 Ga Zaonega Fm in the Fennoscandian Shield, thus correspond to pulsed oxidation of biomass in an oxygenated shallow ocean. The geochemical signatures of the carbonates which show minimal contamination by terrigenous materials provides constrains on the chemistry of the Paleoproterozoic ocean. PAAS-normalized REE patterns are flat or slightly LREE-depleted with variable but slightly negative to positive shale-normalized Ce anomaly and evident Eu anomaly. The carbonates have low concentrations of U, Mo, Co and Ni, and show upsection decrease in Mo, Co and Ni abundances, consistent with increasing redox states. Metapelites from the Hutuo Group show slightly positive Eu anomaly and low Mo concentrations and U/Th ratios (0.33 - 0.10), consistent with deposition in an oxygenated environment. Collectively, the data document the fluctuations of ocean redox states and final oxygenation of the Hutuo Basin in the aftermath of the GOE. Blooms of stromatolite-building cyanobacteria caused by high nutrient availability following the GOE might have played key roles in the final oxygenation of the atmosphere and shallow oceans.

Quantifying Conditions for Fault Self-Sealing in Geologic Carbon Sequestration

NASA Astrophysics Data System (ADS)

McPherson, B. J. O. L.; Patil, V.; Moore, J.; Trujillo, E. M.

2015-12-01

Injecting anthropogenic CO2 into a subsurface reservoir for sequestration will impact the reservoir significantly, including its geochemistry, porosity and permeability. If a fault or fracture penetrates the reservoir, CO2-laden brine may migrate into that fault, eventually sealing it via precipitation or opening it up via dissolution. The goal of this study was to identify and quantify such conditions of fault self-sealing or self-enhancing. We found that the dimensionless Damköhler number (Da), the ratio of reaction rate to advection rate, provides a meaningful framework for characterizing the propensity of (fault) systems to seal or open up. We developed our own framework wherein Damköhler numbers evolve spatiotemporally as opposed to the traditional single Da value approach. Our approach enables us to use the Damköhler for characterization of complex multiphase and multimineral reactive transport problems. We applied this framework to 1D fault models with eight conditions derived from four geologic compositions and two reservoir conditions. The four­ geologic compositions were chosen such that three out of them were representative of distinct geologic end-members (sandstone, mudstone and dolomitic limestone) and one was a mixed composition based on an average of three end-member compositions. The two sets of P-T conditions chosen included one set corresponding to CO2 in a gaseous phase ("shallow conditions") and the other corresponding to supercritical phase CO2 ("deep conditions"). Simulation results suggest that fault sealing via carbonate precipitation was a possibility for shallow conditions within limestone and mixed composition settings. The concentration of cations in the water was found to be an important control on the carbonate precipitation. The deep conditions models did not forecast self-sealing via carbonates. Sealing via clay precipitation is a likely possibility, but the 1000 year time-frame may be short for such. Model results indicated a range of Da values within which substantial reductions of fault porosity (meaning self-sealing) could be expected. A key conclusion suggested by the results of this study is that carbonate precipitation in the near-surface (top ~50-100 m) depths of a fault is the most likely mechanism of "self-sealing" for most geological settings.

Carbon dioxide and energy fluxes over a large shallow lake in China

NASA Astrophysics Data System (ADS)

Zhao, Xiaosong

2017-04-01

The turbulent exchange of carbon dioxide and energy between water and atmosphere over lakes differ from those over vegetated surfaces due to high heat capacity of water and different water ecological environment. For a shallow lake, the underlying surface generally changes between water covered and land covered with water level fluctuation, which significantly influences carbon dioxide and energy fluxes. Continuous measurement of the carbon dioxide (CO2), latent (LE) and sensible (H) heat fluxes was made using the eddy covariance method over the Poyang Lake, the largest fresh lake in China, from August 2013 to December 2015. Results indicated that the surface energy budget has a strong seasonal pattern, with peaks in LE and H observed in early August and September. There was 10 days delay between the net radiation and the latent heat flux. More net radiation (Rn) was allocated to the LE rather than H through the year, with monthly mean LE/Rn of 0.65 and H/Rn of 0.11, which caused Bowen ratio was 0.15 in water-covered period, lower than that in land-covered period. The water heat storage experienced shifting from heat storage to heat release, with maximum heat storage in July and maximum heat release in September. The water heat advection was account for 4% to 10% of Rn and peaked in June. The annual evaporation is 875 mm, 893 mm and 1019 mm in 2013 (from August 2013 to July 2014), 2014 and 2015, which was account for approximately 57% of precipitation in the three years. The large lake acted as a CO2 source in inundating period and a CO2 sink in exposure period. The energy fluxes were controlled by environmental factors with timescale dependence. On daily scale, the LE and H were highly correlated with product of wind speed and vapor pressure deficit (UVPD) or wind speed (U) in the water-covered period, and with Rn in the land-covered period. Monthly LE, H and annual H were controlled by Rn, while annual LE was primarily dependent on water depth. Annual CO2 budget was regulated by duration of inundating period.

The geothermal system of Caviahue-Copahue Volcanic Complex (Chile-Argentina): New insights from self-potential, soil CO2 degassing, temperature measurements and helium isotopes, with structural and fluid circulation implications.

NASA Astrophysics Data System (ADS)

Roulleau, Emilie; Bravo, Francisco; Barde-Cabusson, Stephanie; Pizarro, Marcela; Muños, Carlos; Sanchez, Juan; Tardani, Daniele; Sano, Yuji; Takahata, Naoto; de Cal, Federico; Esteban, Carlos

2016-04-01

Geothermal systems represent natural heat transfer engines in a confined volume of rock which are strongly influenced by the regional volcano-tectonic setting controlling the formation of shallow magmatic reservoirs, and by the local faults/fracture network, that permits the development of hydrothermal circulation cells and promote the vertical migration of fluids and heat. In the Southern Volcanic Zone of Chile-Argentina, geothermal resources occur in close spatial relationship with active volcanism along the Cordillera which is primarily controlled by the 1000 km long, NNE Liquiñe-Ofqui Fault Zone (LOFZ), an intra-arc dextral strike-slip fault system, associated with second-order intra-arc anisotropy of overall NE-SW (extensional) and NW-SE orientation (compressional). However there is still a lack of information on how fault network (NE and WNW strinking faults) and lithology control the fluid circulation. In this study, we propose new data of dense self-potential (SP), soil CO2 emanation and temperature (T) measurements within the geothermal area from Caviahue-Copahue Volcanic Complex (CCVC), coupled with helium isotopes ratios measured in fumaroles and thermal springs. We observe that inside the geothermal system the NE-striking faults, characterized by a combination of SP-CO2 and T maxima with high 3He/4He ratios (7.86Ra), promote the formation of high vertical permeability pathways for fluid circulation. Whereas, the WNW-striking faults represent low permeability pathways for hydrothermal fluids ascent associated with moderate 3He/4He ratios (5.34Ra), promoting the infiltration of meteoric water at shallow depth. These active zones are interspersed by SP-CO2- T minima, which represent self-sealed zones (e.g. impermeable altered rocks) at depth, creating a barrier inhibiting fluids rise. The NE-striking faults seem to be associated with the upflow zones of the geothermal system, where the boiling process produces a high vapor-dominated zone close to the surface. The WNW-striking faults seems to limit to the south the Copahue geothermal area.

Numerical investigation for the impact of CO2 geologic sequestration on regional groundwater flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamamoto, H.; Zhang, K.; Karasaki, K.

Large-scale storage of carbon dioxide in saline aquifers may cause considerable pressure perturbation and brine migration in deep rock formations, which may have a significant influence on the regional groundwater system. With the help of parallel computing techniques, we conducted a comprehensive, large-scale numerical simulation of CO{sub 2} geologic storage that predicts not only CO{sub 2} migration, but also its impact on regional groundwater flow. As a case study, a hypothetical industrial-scale CO{sub 2} injection in Tokyo Bay, which is surrounded by the most heavily industrialized area in Japan, was considered, and the impact of CO{sub 2} injection on near-surfacemore » aquifers was investigated, assuming relatively high seal-layer permeability (higher than 10 microdarcy). A regional hydrogeological model with an area of about 60 km x 70 km around Tokyo Bay was discretized into about 10 million gridblocks. To solve the high-resolution model efficiently, we used a parallelized multiphase flow simulator TOUGH2-MP/ECO2N on a world-class high performance supercomputer in Japan, the Earth Simulator. In this simulation, CO{sub 2} was injected into a storage aquifer at about 1 km depth under Tokyo Bay from 10 wells, at a total rate of 10 million tons/year for 100 years. Through the model, we can examine regional groundwater pressure buildup and groundwater migration to the land surface. The results suggest that even if containment of CO{sub 2} plume is ensured, pressure buildup on the order of a few bars can occur in the shallow confined aquifers over extensive regions, including urban inlands.« less

Calcification rates and the effect of ocean acidification on Mediterranean cold-water corals

PubMed Central

Maier, C.; Watremez, P.; Taviani, M.; Weinbauer, M. G.; Gattuso, J. P.

2012-01-01

Global environmental changes, including ocean acidification, have been identified as a major threat to scleractinian corals. General predictions are that ocean acidification will be detrimental to reef growth and that 40 to more than 80 per cent of present-day reefs will decline during the next 50 years. Cold-water corals (CWCs) are thought to be strongly affected by changes in ocean acidification owing to their distribution in deep and/or cold waters, which naturally exhibit a CaCO3 saturation state lower than in shallow/warm waters. Calcification was measured in three species of Mediterranean cold-water scleractinian corals (Lophelia pertusa, Madrepora oculata and Desmophyllum dianthus) on-board research vessels and soon after collection. Incubations were performed in ambient sea water. The species M. oculata was additionally incubated in sea water reduced or enriched in CO2. At ambient conditions, calcification rates ranged between −0.01 and 0.23% d−1. Calcification rates of M. oculata under variable partial pressure of CO2 (pCO2) were the same for ambient and elevated pCO2 (404 and 867 µatm) with 0.06 ± 0.06% d−1, while calcification was 0.12 ± 0.06% d−1 when pCO2 was reduced to its pre-industrial level (285 µatm). This suggests that present-day CWC calcification in the Mediterranean Sea has already drastically declined (by 50%) as a consequence of anthropogenic-induced ocean acidification. PMID:22130603

Earth's Deep Carbon Cycle Constrained by Partial Melting of Mantle Peridotite and Eclogite

NASA Astrophysics Data System (ADS)

Dasgupta, R.; Hirschmann, M. M.; Withers, A. C.

2006-05-01

The mass of carbon in the mantle is thought to exceed that in all Earth's other reservoirs combined1 and large fluxes of carbon are cycled into and out of the mantle via subduction and volcanic emission. Devolatilization is known to release water in the mantle wedge, but release of carbon could be delayed if the relevant decarbonation reactions or solidi of oceanic crust are not encountered along P-T path of subduction. Outgassing of CO2 from the mantle also has a critical influence on Earth's climate for time scales of 108-109 yr1. The residence time for carbon in the mantle is thought to exceed the age of the Earth1,2, but it could be significantly shorter owing to pervasive deep melting beneath oceanic ridges. The dominant influx of carbon is via carbonate in altered ocean-floor basalts, which survives decarbonation during subduction. Our experiments demonstrate that solidi of carbonated eclogite remain hotter than average subduction geotherms at least as deep as transition zone3, and thus significant subducted C is delivered to the deep Earth, rather than liberated in the shallow mantle by melting. Flux of CO2 into the mantle, assuming average estimate of carbon in altered ocean crust of 0.21 wt. % CO24, can amount to 0.15 × 1015 g/yr. In upwelling mantle, however, partial melting of carbonated eclogite releases calcio-dolomitic carbonatite melt at depths near ~400 km and metasomatically implants carbonate to surrounding peridotite. Thus, volcanic release of CO2 to basalt source regions is likely controlled by the solidus of carbonated peridotite. Our recent experiments with nominally anhydrous, carbonate-bearing garnet lherzolite indicate that the solidus of peridotite with a trace amount of CO2 is ~500 °C lower than that of volatile-free peridotite at 10 GPa5. In upwelling mantle the solidus of carbonated lherzolite is ~100-200 km shallower than that of eclogite+CO2, but beneath oceanic ridges, initial melting occurs as deep as 300-330 km. For peridotite with ~100-1000 ppm CO2, this initial melting yields 0.03-0.3% carbonatite melt. Extraction of such melts from the mantle above 300 km implies residence times of 1 to 4 Gyr for carbon and other highly incompatible elements in the convecting mantle. Such short residence times suggest that large fractions of mantle carbon must be recycled rather than primordial. Implied CO2 fluxes are 0.12-3.4 × 1015 g/yr, which matches or exceeds direct estimates for CO2 fluxes at ridges (0.04-0.66 × 1015 g/yr) 1,6. However, not all of this deep extracted CO2 may reach ridges; some may instead be implanted into oceanic lithosphere, providing a widespread source for metasomatic fluids that are highly enriched in incompatible elements. 1Sleep, N. H. and Zahnle, K. 2001, JGR 106, 1373-1399. 2Zhang, Y. and Zindler, A. 1993, EPSL 117, 331-345. 3Dasgupta, R. et al. 2004, EPSL 227, 73-85. 4Alt, J. C. and Teagle, D. A. H. 1999, GCA, 1527-1535. 5Dasgupta, R. and Hirschmann, M. M. in press, Nature. 6Javoy, M. and Pineau, F. 1991, EPSL 107, 598-611.

A large CO2 sink enhanced by eutrophication in a tropical coastal embayment (Guanabara Bay, Rio de Janeiro, Brazil)

NASA Astrophysics Data System (ADS)

Cotovicz, L. C., Jr.; Knoppers, B. A.; Brandini, N.; Costa Santos, S. J.; Abril, G.

2015-03-01

In contrast to its small surface area, the coastal zone plays a disproportionate role in the global carbon cycle. Carbon production, transformation, emission and burial rates at the land-ocean interface are still poorly known, especially in tropical regions. Surface water pCO2 and ancillary parameters were monitored during nine field campaigns between April 2013 and April 2014 in Guanabara Bay, a tropical eutrophic to hypertrophic semi-enclosed estuarine embayment surrounded by the city of Rio de Janeiro, SE-Brazil. Water pCO2 varied between 22 and 3715 ppmv in the Bay showing spatial, diurnal and seasonal trends that mirrored those of dissolved oxygen (DO) and Chlorophyll a (Chl a). Marked pCO2 undersaturation was prevalent in the shallow, confined and thermally stratified waters of the upper bay, whereas pCO2 oversaturation was restricted to sites close to the small river mouths and small sewage channels, which covered only 10% of the bay's area. Substantial daily variations in pCO2 (up to 395 ppmv between dawn and dusk) were also registered and could be integrated temporally and spatially for the establishment of net diurnal, seasonal and annual CO2 fluxes. In contrast to other estuaries worldwide, Guanabara Bay behaved as a net sink of atmospheric CO2, a property enhanced by the concomitant effects of strong radiation intensity, thermal stratification, and high availability of nutrients, which promotes phytoplankton development and net autotrophy. In the inner part of the bay, the calculated annual CO2 sink (-19.6 mol C m2 yr-1) matched the organic carbon burial in the sediments reported in the literature. The carbon sink and autotrophy of Guanabara Bay was driven by planktonic primary production promoted by eutrophication, and by its typology of marine embayment lacking the classical extended estuarine mixing zone, in contrast to river-dominated estuarine systems, which are generally net heterotrophic and CO2 emitters. Our results show that global CO2 budgetary assertions still lack information on tropical estuarine embayments and lagoons, which are affected by thermal stratification and eutrophication and behave specifically with respect to atmospheric CO2.

Concentration-Discharge Relationships, Nested Reaction Fronts, and the Balance of Oxidative and Acid-Base Weathering Fluxes in an Alpine Catchment, East River, Colorado

NASA Astrophysics Data System (ADS)

Winnick, M.; Carroll, R. W. H.; Williams, K. H.; Maxwell, R. M.; Maher, K.

2016-12-01

Although important for solute production and transport, the varied interactions between biogeochemical processes and subsurface hydrology remain poorly characterized. We investigate these couplings in the headwaters of the East River, CO, a high-elevation shale-dominated catchment system in the Rocky Mountains, using concentration-discharge (C-Q) relationships for major cations, anions, and organic carbon. Dissolved organic carbon (DOC) displays a positive C-Q relationship with well-defined clockwise hysteresis, indicating the mobilization and depletion of DOC in the upper soil horizons and highlighting the importance of shallow flowpaths through the snowmelt period. Cation and anion concentrations demonstrate that carbonate weathering, which dominates solute fluxes, is promoted by both carbonic acid and sulfuric acid derived from oxidation of pyrite in the shale bedrock. Sulfuric acid weathering in the deep subsurface dominates during base flow conditions when waters have infiltrated below the hypothesized pyrite oxidation front, whereas carbonic acid weathering plays a dominant role during the snowmelt period as a result of shallow flowpaths. Differential C-Q relationships between solutes suggest that infiltrating waters approach calcite saturation before reaching the pyrite oxidation front, after which sulfuric acid reduces carbonate alkalinity. This increase in CO2(aq) at the expense of HCO3- results in outgassing of CO2 when waters equilibrate to surface conditions, and reduces the export of carbon and alkalinity from the East River by roughly 33% annually. Future changes in snowmelt dynamics that control the balance of carbonic and sulfuric acid weathering therefore have the capacity to substantially alter the cycling of carbon in the East River catchment. Ultimately, we demonstrate that differential C-Q relationships between major solutes can provide unique insights into the complex subsurface flow and biogeochemical dynamics that operate at catchment scales.

Mantle and Crustal Sources of Carbon, Nitrogen, and Noble gases in Cascade-Range and Aleutian-Arc Volcanic gases

USGS Publications Warehouse

Symonds, Robert B.; Poreda, Robert J.; Evans, William C.; Janik, Cathy J.; Ritchie, Beatrice E.

2003-01-01

Here we report anhydrous chemical (CO2, H2S, N2, H2, CH4, O2, Ar, He, Ne) and isotopic (3He/4He, 40Ar/36Ar, δ13C of CO2, δ13C of CH4, δ15N) compositions of virtually airfree gas samples collected between 1994 and 1998 from 12 quiescent but potentially restless volcanoes in the Cascade Range and Aleutian Arc (CRAA). Sample sites include ≤173°C fumaroles and springs at Mount Shasta, Mount Hood, Mount St. Helens, Mount Rainier, Mount Baker, Augustine Volcano, Mount Griggs, Trident, Mount Mageik, Aniakchak Crater, Akutan, and Makushin. The chemical and isotopic data generally point to magmatic (CO2, Ar, He), shallow crustal sedimentary (hereafter, SCS) (CO2, N2, CH4), crustal (He), and meteoric (N2, Ar) sources of volatiles. CH4 clearly comes from SCS rocks in the subvolcanic systems because CH4 cannot survive the higher temperatures of deeper potential sources. Further evidence for a SCS source for CH4 as well as for non-mantle CO2 and non-meteoric N2 comes from isotopic data that show wide variations between volcanoes that are spatially very close and similar isotopic signatures from volcanoes from very disparate areas. Our results are in direct opposition to many recent studies on other volcanic arcs (Kita and others, 1993; Sano and Marty, 1995; Fischer and others, 1998), in that they point to a dearth of subducted components of CO2 and N2 in the CRAA discharges. Either the CRAA volcanoes are fundamentally different from volcanoes in other arcs or we need to reevaluate the significance of subducted C and N recycling in convergent-plate volcanoes.

Reduced carbon uptake during the 2010 Northern Hemisphere summer from GOSAT

NASA Astrophysics Data System (ADS)

Guerlet, S.; Basu, S.; Butz, A.; Krol, M.; Hahne, P.; Houweling, S.; Hasekamp, O. P.; Aben, I.

2013-05-01

Column-averaged dry air mole fractions of carbon dioxide (XCO2) measured by the Greenhouse Gases Observing Satellite (GOSAT) reveal significant interannual variation (IAV) of CO2uptake during the Northern Hemisphere summer between 2009 and 2010. The XCO2drawdown in 2010 is shallower than in 2009 by 2.4 ppm and 3.0 ppm over North America and Eurasia, respectively. Reduced carbon uptake in the summer of 2010 is most likely due to the heat wave in Eurasia driving biospheric fluxes and fire emissions. A joint inversion of GOSAT and surface data estimates an integrated biospheric and fire emission anomaly in April-September of 0.89 ±0.20 PgC over Eurasia. In contrast, inversions of surface measurements alone fail to replicate the observed XCO2IAV and underestimate emission IAV over Eurasia. This shows the value of GOSAT XCO2in constraining the response of land-atmosphere exchange of CO2 to climate events.

Magnetotelluric Detection Thresholds as a Function of Leakage Plume Depth, TDS and Volume

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, X.; Buscheck, T. A.; Mansoor, K.

We conducted a synthetic magnetotelluric (MT) data analysis to establish a set of specific thresholds of plume depth, TDS concentration and volume for detection of brine and CO 2 leakage from legacy wells into shallow aquifers in support of Strategic Monitoring Subtask 4.1 of the US DOE National Risk Assessment Partnership (NRAP Phase II), which is to develop geophysical forward modeling tools. 900 synthetic MT data sets span 9 plume depths, 10 TDS concentrations and 10 plume volumes. The monitoring protocol consisted of 10 MT stations in a 2×5 grid laid out along the flow direction. We model the MTmore » response in the audio frequency range of 1 Hz to 10 kHz with a 50 Ωm baseline resistivity and the maximum depth up to 2000 m. Scatter plots show the MT detection thresholds for a trio of plume depth, TDS concentration and volume. Plumes with a large volume and high TDS located at a shallow depth produce a strong MT signal. We demonstrate that the MT method with surface based sensors can detect a brine and CO 2 plume so long as the plume depth, TDS concentration and volume are above the thresholds. However, it is unlikely to detect a plume at a depth larger than 1000 m with the change of TDS concentration smaller than 10%. Simulated aquifer impact data based on the Kimberlina site provides a more realistic view of the leakage plume distribution than rectangular synthetic plumes in this sensitivity study, and it will be used to estimate MT responses over simulated brine and CO 2 plumes and to evaluate the leakage detectability. Integration of the simulated aquifer impact data and the MT method into the NRAP DREAM tool may provide an optimized MT survey configuration for MT data collection. This study presents a viable approach for sensitivity study of geophysical monitoring methods for leakage detection. The results come in handy for rapid assessment of leakage detectability.« less

US Geological Survey Toxic Substances Hydrology Program: Proceedings of the technical meeting, Phoenix, Arizona, September 26-30, 1988

USGS Publications Warehouse

Mallard, Gail E.; Ragone, Stephen E.

1989-01-01

Crude oil floating at the surface of a shallow aquifer of glacial outwash, near Bemidji, Minnesota, is altered by geochemical processes. Hydrocarbons from the oil are attenuated by several reactions that include aerobic and anaerobic microbial degradation. These degradation reactions result in the development of geochemical facies in the shallow groundwater system. Groundwater most affected by the presence of organic compounds is anoxic, and concentrations of methane, dissolved organic carbon, and total inorganic are high--0.76 millimole/L, 2.9 millimole/L, and 12.3 millimole/L, respectively. The concentrations of chemical species and delta-(13)C isotope values indicate that the plume near the oil lens has become progressively more reducing. Over a 4-year period (1984 through 1987), the concentrations of methane and iron have increased by a factor of > 25. The data suggest that sequential degradation occurs, as predicted by thermo-dynamics: manganese is reduced before iron is reduced, which occurs before methanogenesis. These data provide field evidence that reduction of iron and manganese is an important mechanism of decomposition of organic matter in aquifers. The delta-(13)C values of inorganic carbon of the native groundwater range from -12 ppt to -15 ppt as a result of mixing of soil CO2 with CO2 from the dissolution of carbonates. Non methanogenic biodegradation of oil constituents adds isotopically light CO2 to the groundwater because the oil has a delta-(13)C value of 28 ppt. The delta-(13)C value of inorganic carbon in the reducing zone have become progressively heavier from 1985 through 1987. The maximum change occurs 15 m downgradient from the oil lens, where the delta-(13)C values increased from -21.6 ppt to -5.35 ppt. This change indicates that the plume has become more reducing and methanogenic over time. 

Landslides triggered by the January 12, 2010 Port-au-Prince, Haiti Mw 7.0 earthquake

NASA Astrophysics Data System (ADS)

Xu, Chong

2014-05-01

The January 12, 2010 Port-au-Prince, Haiti earthquake (Mw 7.0) triggered tens of thousands of landslides. The purpose of this study is to investigate correlations of the occurrence of landslides and its erosion thickness with topographic factors, seismic parameters, and distance from roads. A total of 30,828 landslides triggered by the earthquake cover a total area of 15.736 km2, and the volume of landslide accumulation materials is estimated to be about 30,000,000 m3, and throughout an area more than 3,000 km2. These landslides are of various types, mainly in shallow disrupted landslides and rock falls, and also including coherent deep-seated landslides, shallow disrupted landslides, rock falls, and rock slides. These landslides were delineated using pre- and post-earthquake high-resolutions satellite images. Spatial distribution maps and contour maps of landslide number density, landslide area percentage, and landslide erosion thickness were respectively constructed in order to more intuitive to discover the spatial distribution patterns of the co-seismic landslides. Statistics of size distribution and morphometric parameters of the co-seismic landslides were carried out and were compared with other earthquake events. Four proxies of co-seismic landslides abundances, including landslides centroid number density (LCND), landslide top number density (LTND), landslide area percentage (LAP), and landslide erosion thickness (LET) were used to correlate the co-seismic landslides with various landslide controlling parameters. These controlling parameters include elevation, slope angle, slope aspect, slope curvature, topographic position, distance from drainages, stratum/lithology, distance from the epicenter, distance from the Enriquillo-Plantain Garden fault, distance along the fault, and peak ground acceleration (PGA). Comparing of controls of impact parameters on co-seismic landslides show that slope angle is the strongest impact parameter on co-seismic landslides occurrence. In addition, it should be noted that the co-seismic landslides of our inventories is much more detailed than other inventories in several previous publications. Therefore, comparisons of inventories of landslides triggered by the Haiti earthquake with other published results were carried out and the reasons of such differences were presented. We suggest it should not be limited by past empirical functions between earthquake magnitude and co-seismic landslides or it is necessary to update the past empirical functions based on more and more latest and complete co-seismic landslide inventories. This research was supported by the National Science Foundation of China (41202235)

Geophysical delineation of Mg-rich ultramafic rocks for mineral carbon sequestration

USGS Publications Warehouse

McCafferty, Anne E.; Van Gosen, Bradley S.; Krevor, Sam C.; Graves, Chris R.

2009-01-01

This presentation covers three general topics: (1) description of a new geologic compilation of the United States that shows the location of magnesium-rich ultramafic rocks in the conterminous United States; (2) conceptual illustration of the potential ways that ultramafic rocks could be used to sequester carbon dioxide; and (3) description of ways to use geophysical data to refine and extend the geologic mapping of ultramafic rocks and to better characterize their mineralogy.The geophysical focus of this research is twofold. First, we illustrate how airborne magnetic data can be used to map the shallow subsurface geometry of ultramafic rocks for the purpose of estimating the volume of rock material available for mineral CO2 sequestration. Secondly, we explore, on a regional to outcrop scale, how magnetic mineralogy, as expressed in magnetic anomalies, may vary with magnesium minerals, which are the primary minerals of interest for CO2 sequestration. 

Contrasting fault fluids along high-angle faults: a case study from Southern Apennines (Italy)

NASA Astrophysics Data System (ADS)

Sinisi, Rosa; Petrullo, Angela Vita; Agosta, Fabrizio; Paternoster, Michele; Belviso, Claudia; Grassa, Fausto

2016-10-01

This work focuses on two fault-controlled deposits, the Atella and Rapolla travertines, which are associated with high-angle extensional faults of the Bradano Trough, southern Apennines (Italy). The Atella travertine is along a NW-SE striking, deep-seated extensional fault, already described in literature, which crosscuts both Apulian carbonates and the overlying foredeep basin infill. The Rapolla travertine is on top of a NE-SW striking, shallow-seated fault, here described for the first time, which is interpreted as a tear fault associated with a shallow thrust displacing only the foredeep basin infill. The results of structural, sedimentological, mineralogical, and C and O isotope analyses are here reported and discussed to assess the provenance of mineralizing fluids, and to evaluate the control exerted by the aforementioned extensional faults on deep, mantle-derived and shallow, meteoric fluids. Sedimentological analysis is consistent with five lithofacies in the studied travertines, which likely formed in a typical lacustrine depositional environment. Mineralogical analysis show that travertines mainly consist of calcite, and minor quartz, feldspar and clay minerals, indicative of a terrigenous supply during travertine precipitation. The isotope signature of the two studied travertines shows different provenance for the mineralizing fluids. At the Atella site, the δ13CPDB values range between + 5.2 and + 5.7‰ and the δ18OPDB values between - 9.0 and - 7.3‰, which are consistent with a mantle-derived CO2 component in the fluid. In contrast, at the Rapolla site the δ13CPDB values vary from - 2.7 to + 1.5‰ and the δ18OPDB values from - 6.8 to - 5.4‰, suggesting a mixed CO2 source with both biogenic-derived and mantle-derived fluids. The results of structural analyses conducted along the footwall damage zone of the fault exposed at the Rapolla site, show that the whole damage zone, in which fractures and joints likely channeled the mixed fluids, acted as a distributed conduit for both fault-parallel and cross-fault fluid migration.

Polygenetic Karsted Hardground Omission Surfaces in Lower Silurian Neritic Limestones: a Signature of Early Paleozoic Calcite Seas

NASA Astrophysics Data System (ADS)

James, Noel P.; Desrochers, André; Kyser, Kurt T.

2015-04-01

Exquisitely preserved and well-exposed rocky paleoshoreline omission surfaces in Lower Silurian Chicotte Formation limestones on Anticosti Island, Quebec, are interpreted to be the product of combined marine and meteoric diagenesis. The different omission features include; 1) planar erosional bedding tops, 2) scalloped erosional surfaces, 3) knobs, ridges, and swales at bedding contacts, and 4) paleoscarps. An interpretation is proposed that relates specific omission surface styles to different diagenetic-depositional processes that took place in separate terrestrial-peritidal-shallow neritic zones. Such processes were linked to fluctuations in relative sea level with specific zones of diagenesis such as; 1) karst corrosion, 2) peritidal erosion, 3) subtidal seawater flushing and cementation, and 4) shallow subtidal deposition. Most surfaces are interpreted to have been the result of initial extensive shallow-water synsedimentary lithification that were, as sea level fell, altered by exposure and subaerial corrosion, only to be buried by sediments as sea level rose again. This succession was repeated several times resulting in a suite of recurring polyphase omission surfaces through many meters of stratigraphic section. Synsedimentary cloudy marine cements are well preserved and are thus interpreted to have been calcitic originally. Aragonite components are rare and thought to have to have been dissolved just below the Silurian seafloor. Large molluscs that survived such seafloor removal were nonetheless leached and the resultant megamoulds were filled with synsedimentary calcite cement. These Silurian inner neritic-strandline omission surfaces are temporally unique. They are part of a suite of marine omission surfaces that are mostly found in early Paleozoic neritic carbonate sedimentary rocks. These karsted hardgrounds formed during a calcite-sea time of elevated marine carbonate saturation and extensive marine cement precipitation. The contemporaneous greenhouse atmosphere was supercharged with CO2 leading to profound surface karst under strongly acid rain. Younger peritidal omission surfaces, although potentially formed during aragonite or calcite sea times, would have been subject to very different terrestrial diagenetic process with lower atmospheric pCO2 values but increasingly complex biogenic soils producing dissimilar alteration features.

An overview of results from the CO2SINK 3D baseline seismic survey at Ketzin, Germany

NASA Astrophysics Data System (ADS)

Juhlin, C.; Giese, R.; Cosma, C.; Kazemeini, H.; Juhojuntti, N.; Lüth, S.; Norden, B.; Förster, A.; Yordkayhun, S.

2009-04-01

A 3D seismic survey was acquired at the CO2SINK project site over the Ketzin anticline in the fall of 2005. Main objectives of the survey were (1) to verify earlier geological interpretations of the structure based on vintage 2D seismic and borehole data, (2) to provide, if possible, an understanding of the structural geometry for flow pathways within the reservoir, (3) a baseline for later evaluation of the time evolution of rock properties as CO2 is injected into the reservoir, and (4) detailed sub-surface images near the injection borehole for planning of the drilling operations. Overlapping templates with 5 receiver lines containing 48 active channels in each template were used for the acquisition. In each template, 200 nominal source points were activated using an accelerated weight drop, giving a nominal fold of 25. Due to logistics, the number of actual source points in each template varied. In spite of the relatively low fold and the simple source used, data quality is generally good with the uppermost 1000 m being well imaged. Data processing results clearly show a fault system across the top of the Ketzin anticline that is termed the Central Graben Fault Zone (CGFZ). The fault zone consists of west-southwest-east-northeast- to east-west-trending normal faults bounding a 600-800 m wide graben. Within the Jurassic section, discrete faults are well developed, and the main graben-bounding faults have throws of up to 30 m. At shallower levels, the fault system appears to disappear in the Tertiary Rupelian clay. The main bounding faults of the CGFZ can be traced downwards to the top of the Weser Formation and possibly to the Stuttgart level, the target formation for CO2 injection. No faults were imaged near the injection site on the southern limb of the anticline. Remnant gas, cushion and residual gas from a previous natural gas storage facility at the site, is present near the top of the anticline in the depth interval of about 250-400 m and has a clear seismic signature. In addition to the standard processing and interpretation applied, attribute analysis, detailed shallow reflection seismic processing, tomographic inversion of first arrival times, and initial seismic modeling of the CO2 response have been performed. Attribute analysis of the target horizon using the continuous wavelet transform indicates that the injection site penetrates the target reservoir near the edge of a north-northwest-south-southeast striking channel.

Methane and carbon dioxide emission from two pig finishing barns.

PubMed

Ni, Ji-Qin; Heber, Albert J; Lim, Teng Teeh; Tao, Pei Chun; Schmidt, Amy M

2008-01-01

Agricultural activities are an important source of greenhouse gases. However, comprehensive, long-term, and high-quality measurement data of these gases are lacking. This article presents a field study of CH(4) and CO(2) emission from two 1100-head mechanically ventilated pig (Sus scrofa) finishing barns (B1 and B2) with shallow manure flushing systems and propane space heaters from August 2002 to July 2003 in northern Missouri. Barn 2 was treated with soybean oil sprinkling, misting essential oils, and misting essential oils with water to reduce air pollutant emissions. Only days with CDFB (complete-data-full-barn), defined as >80% of valid data during a day with >80% pigs in the barns, were used. The CH(4) average daily mean (ADM) emission rates were 36.2 +/- 2.0 g/d AU (ADM +/- 95% confidence interval; animal unit = 500 kg live mass) from B1 (CDFB days = 134) and 28.8 +/- 1.8 g/d AU from B2 (CDFB days = 131). The CO(2) ADM emission rates were 17.5 +/- 0.8 kg/d AU from B1 (CDFB days = 146) and 14.2 +/- 0.6 kg/d AU from B2 (CDFB days = 137). The treated barn reduced CH(4) emission by 20% (P < 0.01) and CO(2) emission by 19% (P < 0.01). The CH(4) and CO(2) released from the flushing lagoon effluent were equivalent to 9.8 and 4.1% of the CDFB CH(4) and CO(2) emissions, respectively. The emission data were compared with the literature, and the characteristics of CH(4) and CO(2) concentrations and emissions were discussed.

Lithospheric magma dynamics beneath the El Hierro Volcano, Canary Islands: insights from fluid inclusions

NASA Astrophysics Data System (ADS)

Oglialoro, E.; Frezzotti, M. L.; Ferrando, S.; Tiraboschi, C.; Principe, C.; Groppelli, G.; Villa, I. M.

2017-10-01

At active volcanoes, petrological studies have been proven to be a reliable approach in defining the depth conditions of magma transport and storage in both the mantle and the crust. Based on fluid inclusion and mineral geothermobarometry in mantle xenoliths, we propose a model for the magma plumbing system of the Island of El Hierro (Canary Islands). The peridotites studied here were entrained in a lava flow exposed in the El Yulan Valley. These lavas are part of the rift volcanism that occurred on El Hierro at approximately 40-30 ka. The peridotites are spinel lherzolites, harzburgites, and dunites which equilibrated in the shallow mantle at pressures between 1.5 and 2 GPa and at temperatures between 800 and 950 °C (low-temperature peridotites; LT), as well as at higher equilibration temperatures of 900 to 1100 °C (high-temperature peridotites; HT). Microthermometry and Raman analyses of fluid inclusions reveal trapping of two distinct fluid phases: early type I metasomatic CO2-N2 fluids ( X N2 = 0.01-0.18; fluid density (d) = 1.19 g/cm3), coexisting with silicate-carbonate melts in LT peridotites, and late type II pure CO2 fluids in both LT (d = 1.11-1.00 and 0.75-0.65 g/cm3) and HT ( d = 1.04-1.11 and 0.75-0.65 g/cm3) peridotites. While type I fluids represent metasomatic phases in the deep oceanic lithosphere (at depths of 60-65 km) before the onset of magmatic activity, type II CO2 fluids testify to two fluid trapping episodes during the ascent of xenoliths in their host mafic magmas. Identification of magma accumulation zones through interpretation of type II CO2 fluid inclusions and mineral geothermobarometry indicate the presence of a vertically stacked system of interconnected small magma reservoirs in the shallow lithospheric mantle between a depth of 22 and 36 km (or 0.67 to 1 GPa). This magma accumulation region fed a short-lived magma storage region located in the lower oceanic crust at a depth of 10-12 km (or 0.26-0.34 GPa). Following our model, the 40-30-ka-old volcanic activity of El Hierro is related to this mantle-based magma system, a system that we propose fed the recent 2011-2012 eruption.

Geochemical effects of CO2 injection on produced water chemistry at an enhanced oil recovery site in the Permian Basin of northwest Texas, USA: Preliminary geochemical and Li isotope results

NASA Astrophysics Data System (ADS)

Pfister, S.; Gardiner, J.; Phan, T. T.; Macpherson, G. L.; Diehl, J. R.; Lopano, C. L.; Stewart, B. W.; Capo, R. C.

2014-12-01

Injection of supercritical CO2 for enhanced oil recovery (EOR) presents an opportunity to evaluate the effects of CO2 on reservoir properties and formation waters during geologic carbon sequestration. Produced water from oil wells tapping a carbonate-hosted reservoir at an active EOR site in the Permian Basin of Texas both before and after injection were sampled to evaluate geochemical and isotopic changes associated with water-rock-CO2 interaction. Produced waters from the carbonate reservoir rock are Na-Cl brines with TDS levels of 16.5-34 g/L and detectable H2S. These brines are potentially diluted with shallow groundwater from earlier EOR water flooding. Initial lithium isotope data (δ7Li) from pre-injection produced water in the EOR field fall within the range of Gulf of Mexico Coastal sedimentary basin and Appalachian basin values (Macpherson et al., 2014, Geofluids, doi: 10.1111/gfl.12084). Pre-injection produced water 87Sr/86Sr ratios (0.70788-0.70795) are consistent with mid-late Permian seawater/carbonate. CO2 injection took place in October 2013, and four of the wells sampled in May 2014 showed CO2 breakthrough. Preliminary comparison of pre- and post-injection produced waters indicates no significant changes in the major inorganic constituents following breakthrough, other than a possible drop in K concentration. Trace element and isotope data from pre- and post-breakthrough wells are currently being evaluated and will be presented.

Gas composition of the January 1983 eruption of Kilauea Volcano, Hawaii

USGS Publications Warehouse

Greenland, L.P.

1984-01-01

Gas collections were made from a ???900??C vent both by conventional evacuated-bottle/wet-chemical techniques and by manual pumping of flowthrough bottles. The complete analyses suggest an equilibrium assemblage quenched at 1,010??C, about midway between fountain and vent temperatures. I suggest that the very low C S ratio is due to degassing of CO2 during storage of the magma in a shallow reservoir before eruption. The two sampling techniques yielded analytical data in mutual agreement. ?? 1984.

Unraveling the dynamics of magmatic CO2 degassing at Mammoth Mountain, California

NASA Astrophysics Data System (ADS)

Peiffer, Loïc; Wanner, Christoph; Lewicki, Jennifer L.

2018-02-01

The accumulation of magmatic CO2 beneath low-permeability barriers may lead to the formation of CO2-rich gas reservoirs within volcanic systems. Such accumulation is often evidenced by high surface CO2 emissions that fluctuate over time. The temporal variability in surface degassing is believed in part to reflect a complex interplay between deep magmatic degassing and the permeability of degassing pathways. A better understanding of the dynamics of CO2 degassing is required to improve monitoring and hazards mitigation in these systems. Owing to the availability of long-term records of CO2 emissions rates and seismicity, Mammoth Mountain in California constitutes an ideal site towards such predictive understanding. Mammoth Mountain is characterized by intense soil CO2 degassing (up to ∼1000 t d-1) and tree kill areas that resulted from leakage of CO2 from a CO2-rich gas reservoir located in the upper ∼4 km. The release of CO2-rich fluids from deeper basaltic intrusions towards the reservoir induces seismicity and potentially reactivates faults connecting the reservoir to the surface. While this conceptual model is well-accepted, there is still a debate whether temporally variable surface CO2 fluxes directly reflect degassing of intrusions or variations in fault permeability. Here, we report the first large-scale numerical model of fluid and heat transport for Mammoth Mountain. We discuss processes (i) leading to the initial formation of the CO2-rich gas reservoir prior to the occurrence of high surface CO2 degassing rates and (ii) controlling current CO2 degassing at the surface. Although the modeling settings are site-specific, the key mechanisms discussed in this study are likely at play at other volcanic systems hosting CO2-rich gas reservoirs. In particular, our model results illustrate the role of convection in stripping a CO2-rich gas phase from a rising hydrothermal fluid and leading to an accumulation of a large mass of CO2 (∼107-108 t) in a shallow gas reservoir. Moreover, we show that both, short-lived (months to years) and long-lived (hundreds of years) events of magmatic fluid injection can lead to critical pressures within the reservoir and potentially trigger fault reactivation. Our sensitivity analysis suggests that observed temporal fluctuations in surface degassing are only indirectly controlled by variations in magmatic degassing and are mainly the result of temporally variable fault permeability. Finally, we suggest that long-term CO2 emission monitoring, seismic tomography and coupled thermal-hydraulic-mechanical modeling are important for CO2-related hazard mitigation.

Experimental study of potential wellbore cement carbonation by various phases of carbon dioxide during geologic carbon sequestration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jung, Hun Bok; Um, Wooyong

2013-08-16

Hydrated Portland cement was reacted with carbon dioxide (CO2) in supercritical, gaseous, and aqueous phases to understand the potential cement alteration processes along the length of a wellbore, extending from deep CO2 storage reservoir to the shallow subsurface during geologic carbon sequestration. The 3-D X-ray microtomography (XMT) images displayed that the cement alteration was significantly more extensive by CO2-saturated synthetic groundwater than dry or wet supercritical CO2 at high P (10 MPa)-T (50°C) conditions. Scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) analysis also exhibited a systematic Ca depletion and C enrichment in cement matrix exposed to CO2-saturated groundwater. Integratedmore » XMT, XRD, and SEM-EDS analyses identified the formation of extensive carbonated zone filled with CaCO3(s), as well as the porous degradation front and the outermost silica-rich zone in cement after exposure to CO2-saturated groundwater. The cement alteration by CO2-saturated groundwater for 2-8 months overall decreased the porosity from 31% to 22% and the permeability by an order of magnitude. Cement alteration by dry or wet supercritical CO2 was slow and minor compared to CO2-saturated groundwater. A thin single carbonation zone was formed in cement after exposure to wet supercritical CO2 for 8 months or dry supercritical CO2 for 15 months. Extensive calcite coating was formed on the outside surface of a cement sample after exposure to wet gaseous CO2 for 1-3 months. The chemical-physical characterization of hydrated Portland cement after exposure to various phases of carbon dioxide indicates that the extent of cement carbonation can be significantly heterogeneous depending on CO2 phase present in the wellbore environment. Both experimental and geochemical modeling results suggest that wellbore cement exposure to supercritical, gaseous, and aqueous phases of CO2 during geologic carbon sequestration is unlikely to damage the wellbore integrity because cement alteration by all phases of CO2 is dominated by carbonation reaction. This is consistent with previous field studies of wellbore cement with extensive carbonation after exposure to CO2 for 3 decades. However, XMT imaging indicates that preferential cement alteration by supercritical CO2 or CO2-saturated groundwater can occur along the cement-steel or cement-rock interfaces. This highlights the importance of further investigation of cement degradation along the interfaces of wellbore materials to ensure permanent geologic carbon storage.« less

Carbon isotope fractionation of dissolved inorganic carbon (DIC) due to outgassing of carbon dioxide from a headwater stream

USGS Publications Warehouse

Doctor, D.H.; Kendall, C.; Sebestyen, S.D.; Shanley, J.B.; Ohte, N.; Boyer, E.W.

2008-01-01

The stable isotopic composition of dissolved inorganic carbon (??13C-DIC) was investigated as a potential tracer of streamflow generation processes at the Sleepers River Research Watershed, Vermont, USA. Downstream sampling showed ?? 13C-DIC increased between 3-5??? from the stream source to the outlet weir approximately 0??5 km downstream, concomitant with increasing pH and decreasing PCO2. An increase in ??13C-DIC of 2.4 ?? 0??1??? per log unit decrease of excess PCO2 (stream PCO2 normalized to atmospheric PCO2) was observed from downstream transect data collected during snowmelt. Isotopic fractionation of DIC due to CO2 outgassing rather than exchange with atmospheric CO2 may be the primary cause of increased ?? 13C-DIC values downstream when PCO2 of surface freshwater exceeds twice the atmospheric CO2 concentration. Although CO2 outgassing caused a general increase in stream ??13C-DIC values, points of localized groundwater seepage into the stream were identified by decreases in ??13C-DIC and increases in DIC concentration of the stream water superimposed upon the general downstream trend. In addition, comparison between snowmelt, early spring and summer seasons showed that DIC is flushed from shallow groundwater flowpaths during snowmelt and is replaced by a greater proportion of DIC derived from soil CO2 during the early spring growing season. Thus, in spite of effects from CO2 outgassing, ??13C of DIC can be a useful indicator of groundwater additions to headwater streams and a tracer of carbon dynamics in catchments. Copyright ?? 2007 John Wiley & Sons, Ltd.

Shallow system rejuvenation and magma discharge trends at Piton de la Fournaise volcano (La Réunion Island)

NASA Astrophysics Data System (ADS)

Coppola, D.; Di Muro, A.; Peltier, A.; Villeneuve, N.; Ferrazzini, V.; Favalli, M.; Bachèlery, P.; Gurioli, L.; Harris, A. J. L.; Moune, S.; Vlastélic, I.; Galle, B.; Arellano, S.; Aiuppa, A.

2017-04-01

Basaltic magma chambers are often characterized by emptying and refilling cycles that influence their evolution in space and time, and the associated eruptive activity. During April 2007, the largest historical eruption of Piton de la Fournaise (Île de La Réunion, France) drained the shallow plumbing system (> 240 ×106 m3) and resulted in collapse of the 1-km-wide summit crater. Following these major events, Piton de la Fournaise entered a seven-year long period of near-continuous deflation interrupted, in June 2014, by a new phase of significant inflation. By integrating multiple datasets (lava discharge rates, deformation, seismicity, gas flux, gas composition, and lava chemistry), we here show that the progressive migration of magma from a deeper (below sea level) storage zone gradually rejuvenated and pressurized the above-sea-level portion of the magmatic system consisting of a vertically-zoned network of relatively small-volume magma pockets. Continuous inflation provoked four small (< 5 ×106 m3) eruptions from vents located close to the summit cone and culminated, during August-October 2015, with a chemically zoned eruption that erupted 45 ± 15 ×106 m3 of lava. This two-month-long eruption evolved through (i) an initial phase of waning discharge, associated to the withdrawal of differentiated magma from the shallow system, into (ii) a month-long phase of increasing lava and SO2 fluxes at the effusive vent, coupled with CO2 enrichment of summit fumaroles, and involving emission of less differentiated lavas, to end with, (iii) three short-lived (∼2 day-long) pulses in lava and gas flux, coupled with arrival of cumulative olivine at the surface and deflation. The activity observed at Piton de la Fournaise in 2014 and 2015 points to a new model of shallow system rejuvenation and discharge, whereby continuous magma supply causes eruptions from increasingly deeper and larger magma storage zones. Downward depressurization continues until unloading of the deepest, least differentiated magma triggers pulses in lava and gas flux, accompanied by rapid contraction of the volcano edifice, that empties the main shallow reservoir and terminates the cycle. Such an unloading process may characterize the evolution of shallow magmatic systems at other persistently active effusive centers.

Ocean acidification decreases plankton respiration: evidence from a mesocosm experiment

NASA Astrophysics Data System (ADS)

Spilling, Kristian; Paul, Allanah J.; Virkkala, Niklas; Hastings, Tom; Lischka, Silke; Stuhr, Annegret; Bermúdez, Rafael; Czerny, Jan; Boxhammer, Tim; Schulz, Kai G.; Ludwig, Andrea; Riebesell, Ulf

2016-08-01

Anthropogenic carbon dioxide (CO2) emissions are reducing the pH in the world's oceans. The plankton community is a key component driving biogeochemical fluxes, and the effect of increased CO2 on plankton is critical for understanding the ramifications of ocean acidification on global carbon fluxes. We determined the plankton community composition and measured primary production, respiration rates and carbon export (defined here as carbon sinking out of a shallow, coastal area) during an ocean acidification experiment. Mesocosms ( ˜ 55 m3) were set up in the Baltic Sea with a gradient of CO2 levels initially ranging from ambient ( ˜ 240 µatm), used as control, to high CO2 (up to ˜ 1330 µatm). The phytoplankton community was dominated by dinoflagellates, diatoms, cyanobacteria and chlorophytes, and the zooplankton community by protozoans, heterotrophic dinoflagellates and cladocerans. The plankton community composition was relatively homogenous between treatments. Community respiration rates were lower at high CO2 levels. The carbon-normalized respiration was approximately 40 % lower in the high-CO2 environment compared with the controls during the latter phase of the experiment. We did not, however, detect any effect of increased CO2 on primary production. This could be due to measurement uncertainty, as the measured total particular carbon (TPC) and combined results presented in this special issue suggest that the reduced respiration rate translated into higher net carbon fixation. The percent carbon derived from microscopy counts (both phyto- and zooplankton), of the measured total particular carbon (TPC), decreased from ˜ 26 % at t0 to ˜ 8 % at t31, probably driven by a shift towards smaller plankton (< 4 µm) not enumerated by microscopy. Our results suggest that reduced respiration leads to increased net carbon fixation at high CO2. However, the increased primary production did not translate into increased carbon export, and consequently did not work as a negative feedback mechanism for increasing atmospheric CO2 concentration.

A strong CO2 sink enhanced by eutrophication in a tropical coastal embayment (Guanabara Bay, Rio de Janeiro, Brazil)

NASA Astrophysics Data System (ADS)

Cotovicz, L. C., Jr.; Knoppers, B. A.; Brandini, N.; Costa Santos, S. J.; Abril, G.

2015-10-01

In contrast to its small surface area, the coastal zone plays a disproportionate role in the global carbon cycle. Carbon production, transformation, emission and burial rates at the land-ocean interface are significant at the global scale but still poorly known, especially in tropical regions. Surface water pCO2 and ancillary parameters were monitored during nine field campaigns between April 2013 and April 2014 in Guanabara Bay, a tropical eutrophic to hypertrophic semi-enclosed estuarine embayment surrounded by the city of Rio de Janeiro, southeast Brazil. Water pCO2 varied between 22 and 3715 ppmv in the bay, showing spatial, diurnal and seasonal trends that mirrored those of dissolved oxygen (DO) and chlorophyll a (Chl a). Marked pCO2 undersaturation was prevalent in the shallow, confined and thermally stratified waters of the upper bay, whereas pCO2 oversaturation was restricted to sites close to the small river mouths and small sewage channels, which covered only 10 % of the bay's area. Substantial daily variations in pCO2 (up to 395 ppmv between dawn and dusk) were also registered and could be integrated temporally and spatially for the establishment of net diurnal, seasonal and annual CO2 fluxes. In contrast to other estuaries worldwide, Guanabara Bay behaved as a net sink of atmospheric CO2, a property enhanced by the concomitant effects of strong radiation intensity, thermal stratification, and high availability of nutrients, which promotes phytoplankton development and net autotrophy. The calculated CO2 fluxes for Guanabara Bay ranged between -9.6 and -18.3 mol C m-2 yr-1, of the same order of magnitude as the organic carbon burial and organic carbon inputs from the watershed. The positive and high net community production (52.1 mol C m-2 yr-1) confirms the high carbon production in the bay. This autotrophic metabolism is apparently enhanced by eutrophication. Our results show that global CO2 budgetary assertions still lack information on tropical, marine-dominated estuarine systems, which are affected by thermal stratification and eutrophication and behave specifically with respect to atmospheric CO2.

Strategies of dissolved inorganic carbon use in macroalgae across a gradient of terrestrial influence: implications for the Great Barrier Reef in the context of ocean acidification

NASA Astrophysics Data System (ADS)

Diaz-Pulido, Guillermo; Cornwall, Christopher; Gartrell, Patrick; Hurd, Catriona; Tran, Dien V.

2016-12-01

Macroalgae are generally used as indicators of coral reef status; thus, understanding the drivers and mechanisms leading to increased macroalgal abundance are of critical importance. Ocean acidification (OA) due to elevated carbon dioxide (CO2) concentrations has been suggested to stimulate macroalgal growth and abundance on reefs. However, little is known about the physiological mechanisms by which reef macroalgae use CO2 from the bulk seawater for photosynthesis [i.e., (1) direct uptake of bicarbonate (HCO3 -) and/or CO2 by means of carbon concentrating mechanisms (CCM) and (2) the diffusive uptake of CO2], which species could benefit from increased CO2 or which habitats may be more susceptible to acidification-induced algal proliferations. Here, we provide the first quantitative examination of CO2-use strategies in coral reef macroalgae and provide information on how the proportion of species and the proportional abundance of species utilising each of the carbon acquisition strategies varies across a gradient of terrestrial influence (from inshore to offshore reefs) in the Great Barrier Reef (GBR). Four macroalgal groups were identified based on their carbon uptake strategies: (1) CCM-only (HCO3 - only users); (2) CCM-HCO3 -/CO2 (active uptake HCO3 - and/or CO2 use); (3) Non-CCM species (those relying on diffusive CO2 uptake); and (4) Calcifiers. δ13C values of macroalgae, confirmed by pH drift assays, show that diffusive CO2 use is more prevalent in deeper waters, possibly due to low light availability that limits activity of CCMs. Inshore shallow reefs had a higher proportion of CCM-only species, while reefs further away from terrestrial influence and exposed to better water quality had a higher number of non-CCM species than inshore and mid-shelf reefs. As non-CCM macroalgae are more responsive to increased seawater CO2 and OA, reef slopes of the outer reefs are probably the habitats most vulnerable to the impacts of OA. Our results suggest a potentially important role of carbon physiology in structuring macroalgal communities in the GBR.

Molecular Cobalt Catalysts for O 2 Reduction: Low-Overpotential Production of H 2 O 2 and Comparison with Iron-Based Catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yu-Heng; Pegis, Michael L.; Mayer, James M.

A series of mononuclear pseudo-macrocyclic cobalt complexes have been investigated as catalysts for O2 reduction. Each of these complexes, with CoIII/II reduction potentials that span nearly 400 mV, mediate highly selective two- electron reduction of O2 to H2O2 (93–99%) using decamethylferrocene (Fc*) as the reductant and acetic acid as the proton source. Kinetic studies reveal that the rate exhibits a first- order dependence on [Co] and [AcOH], but no dependence on [O2] or [Fc*]. A linear correlation is observed between log(TOF) vs. E1/2(CoIII/II) for the different cobalt complexes (TOF = turnover frequency). The thermodynamic potential for+ O2 reduction to H2O2more » was estimated by measuring the H /H2 open-circuit potential under the reaction conditions. This value provides the basis for direct assessment of the thermodynamic efficiency of the different catalysts and shows that H2O2 is formed with overpotentials as low as 90 mV. These results are compared with a recently reported series of Fe-porphyrin complexes, which catalyze four-electron reduction of O2 to H2O. The data show that the TOFs of the Co complexes exhibit a shallower dependence on E1/2(MIII/II) than the Fe complexes. This behavior, which underlies the low overpotential, is rationalized on the basis of the catalytic rate law.« less

Variations of geothermometry and chemical-isotopic compositions of hot spring fluids in the Rehai geothermal field, southwestern China

NASA Astrophysics Data System (ADS)

Du, Jianguo; Liu, Congqiang; Fu, Bihong; Ninomiya, Yoshiki; Zhang, Youlian; Wang, Chuanyuan; Wang, Hualiu; Sun, Zigang

2005-04-01

Geothermal variations, origins of carbon-bearing components and reservoir temperatures in the Rehai geothermal field (RGF) of Tengchong volcanic area, Yunnan Province, southwestern China, are discussed on the basis of carbon isotope compositions, combined with helium isotope ratios and geothermal data from 1973 to 2000. δ 13C values of CO 2, CH 4, HCO 3-, CO 3= and travertine in the hot springs range from -7.6‰ to -1.18‰, -56.9‰ to -19.48‰, -6.7‰ to -4.2‰, -6.4‰ to -4.2‰ and -27.1‰ to +0.6‰, respectively. The carbon dioxide probably has a mantle/magma origin, but CH 4 and He have multiple origins. HCO 3- and CO 3= in RGF thermal fluids are predominantly derived from igneous carbon dioxide, but other ions originate from rocks through which the fluids circulate. The 13C values of CO 2, HCO 3- (aq) and CO 3= (aq) illustrate that isotopic equilibriums between CO 2 and HCO 3- (aq), and CO 3= (aq) and between DIC and travertine were not achieved, and no carbon isotope fractionation between HCO 3- (aq) and CO 3= (aq) of the hot springs in RGF was found. Using various geothermometers, temperatures of the geothermal reservoirs are estimated in a wide range from 69 °C to 450 °C that fluctuated from time to time. The best estimate of subsurface reservoir temperature may be 250-300 °C. Contributions of mantle fluids and shallow crust fluids in Rehai geothermal field varied with time, which resulted in variations of chemical and isotopic compositions and reservoir temperatures.

Mechanisms controlling Cu, Fe, Mn, and Co profiles in peat of the Filson Creek Fen, northeastern Minnesota

USGS Publications Warehouse

Walton-Day, K.; Filipek, L.H.; Papp, C.S.E.

1990-01-01

Filson Creek Fen, located in northeastern Minnesota, overlies a Cu-Ni sulfide deposit. A site in the fen was studied to evaluate the hydrogeochemical mechanisms governing the development of Fe, Mn, Co, and Cu profiles in the peat. At the study site, surface peat approximately 1 m thick is separated from the underlying mineralized bedrock by a 6-12 m thickness of lake and glaciofluvial sediments and till. Concentrations of Fe, Mn, Co, and Cu in peat and major elements in pore water delineate a shallow, relatively oxidized, Cu-rich zone overlying a deeper, reduced, Fe-, Mn-, and Co-rich zone within the peat. Sequential metal extractions from peat samples reveal that 40-55% of the Cu in the shallow zone is associated with organic material, whereas the remaining Cu is distributed between iron-oxide, sulfide, and residual fractions. Sixty to seventy percent of the Fe, Mn, and Co concentrated in the deeper zone occur in the residual phase. The metal profiles and associations probably result from non-steady-state input of metals and detritus into the fen during formation of the peat column. The enrichment of organic-associated Cu in the upper, oxidized zone represents a combination of Cu transported into the fen with detrital plant fragments and soluble Cu, derived from weathering of outcrop and subcrop of the mineral deposit, transported into the fen, and fixed onto organic matter in the peat. The variable stratigraphy of the peat indicates that weathering processes and surface vegetation have changed through time in the fen. The Fe, Mn, and Co maxima at the base of the peat are associated with a maximum in detrital matter content of the peat resulting from a transition between the underlying inorganic sedimentary environment to an organic sedimentary environment. The chemistry of sediments and ground water collected beneath the peat indicate that mobilization of metals from sulfide minerals in the buried mineral deposit or glacial deposits is minimal. Therefore, the primary source of Cu to the peat at the study site is outcrops and shallow subcrops of the mineral deposit adjacent to the fen. ?? 1990.

Plant identity and shallow soil moisture are primary drivers of stomatal conductance in the savannas of Kruger National Park.

PubMed

Tobin, Rebecca L; Kulmatiski, Andrew

2018-01-01

Our goal was to describe stomatal conductance (gs) and the site-scale environmental parameters that best predict gs in Kruger National Park (KNP), South Africa. Dominant grass and woody species were measured over two growing seasons in each of four study sites that represented the natural factorial combination of mean annual precipitation [wet (750 mm) or dry (450 mm)] and soil type (clay or sand) found in KNP. A machine-learning (random forest) model was used to describe gs as a function of plant type (species or functional group) and site-level environmental parameters (CO2, season, shortwave radiation, soil type, soil moisture, time of day, vapor pressure deficit and wind speed). The model explained 58% of the variance among 6,850 gs measurements. Species, or plant functional group, and shallow (0-20 cm) soil moisture had the greatest effect on gs. Atmospheric drivers and soil type were less important. When parameterized with three years of observed environmental data, the model estimated mean daytime growing season gs as 68 and 157 mmol m-2 sec-1 for grasses and woody plants, respectively. The model produced here could, for example, be used to estimate gs and evapotranspiration in KNP under varying climate conditions. Results from this field-based study highlight the role of species identity and shallow soil moisture as primary drivers of gs in savanna ecosystems of KNP.

The effect of CO2 and Nd:YAP lasers on CAD/CAM Ceramics: SEM, EDS and thermal studies.

PubMed

El Gamal, Ahmed; Fornaini, Carlo; Rocca, Jean Paul; Muhammad, Omid H; Medioni, Etienne; Cucinotta, Annamaria; Brulat-Bouchard, Nathalie

2016-03-31

The objective of this study was to investigate the interaction of infrared laser light on Computer Aided Design and Computer Aided Manufacturing (CAD/CAM) ceramic surfaces. Sixty CAD/CAM ceramic discs were prepared and divided into two different groups: lithiumdisilicate ceramic (IPSe.maxCADs) and Zirconia ceramic (IPSe.maxZirCADs). The laser irradiation was performed on graphite and non-graphite surfaces with a Carbon Dioxide laser at 5W and 10W power in continuous mode (CW mode) and with Neodymium Yttrium Aluminum Perovskite (Nd:YAP) laser at 10W. Surface textures and compositions were examined using Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS). Thermal elevation was measured by thermocouple during laser irradiation. The SEM observation showed a rough surface plus cracks and fissures on CO2 10W samples and melting areas in Nd:YAP samples; moreover, with CO2 5W smooth and shallow surfaces were observed. EDS analysis revealed that laser irradiation does not result in modifications of the chemical composition even if minor changes in the atomic mass percentage of the components were registered. Thermocouple showed several thermal changes during laser irradiation. CO2 and Nd:YAP lasers modify CAD/CAM ceramic surface without chemical composition modifications.

Experiential, autonomic, and respiratory correlates of CO2 reactivity in individuals with high and low anxiety sensitivity.

PubMed

Blechert, Jens; Wilhelm, Frank H; Meuret, Alicia E; Wilhelm, Eva M; Roth, Walton T

2013-10-30

Psychometric studies indicate that anxiety sensitivity (AS) is a risk factor for anxiety disorders such as panic disorder (PD). To better understand the psychophysiological basis of AS and its relation to clinical anxiety, we examined whether high-AS individuals show similarly elevated reactivity to inhalations of carbon dioxide (CO2) as previously reported for PD and social phobia in this task. Healthy individuals with high and low AS were exposed to eight standardized inhalations of 20% CO2-enriched air, preceded and followed by inhalations of room air. Anxiety and dyspnea, in addition to autonomic and respiratory responses were measured every 15 s. Throughout the task, high AS participants showed a respiratory pattern of faster, shallower breathing and reduced inhalation of CO2 indicative of anticipatory or contextual anxiety. In addition, they showed elevated dyspnea responses to the second set of air inhalations accompanied by elevated heart rate, which could be due to sensitization or conditioning. Respiratory abnormalities seem to be common to high AS individuals and PD patients when considering previous findings with this task. Similarly, sensitization or conditioning of anxious and dyspneic symptoms might be common to high AS and clinical anxiety. Respiratory conditionability deserves greater attention in anxiety disorder research. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Caldera unrest driven by CO2-induced drying of the deep hydrothermal system.

PubMed

Moretti, R; Troise, C; Sarno, F; De Natale, G

2018-05-29

Interpreting volcanic unrest is a highly challenging and non-unique problem at calderas, since large hydrothermal systems may either hide or amplify the dynamics of buried magma(s). Here we use the exceptional ground displacement and geochemical datasets from the actively degassing Campi Flegrei caldera (Southern Italy) to show that ambiguities disappear when the thermal evolution of the deep hydrothermal system is accurately tracked. By using temperatures from the CO 2 -CH 4 exchange of 13 C and thermodynamic analysis of gas ascending in the crust, we demonstrate that after the last 1982-84 crisis the deep hydrothermal system evolved through supercritical conditions under the continuous isenthalpic inflow of hot CO 2 -rich gases released from the deep (~8 km) magma reservoir of regional size. This resulted in the drying of the base of the hot hydrothermal system, no more buffered along the liquid-vapour equilibrium, and excludes any shallow arrival of new magma, whose abundant steam degassing due to decompression would have restored liquid-vapour equilibrium. The consequent CO 2 -infiltration and progressive heating of the surrounding deforming rock volume cause the build-up of pore pressure in aquifers, and generate the striking temporal symmetry that characterizes the ongoing uplift and the post-1984 subsidence, both originated by the same but reversed deformation mechanism.

Can Earthworm "mix up" Soil Carbon Budgets in Temperate Forests Under Elevated Carbon Dioxide?

NASA Astrophysics Data System (ADS)

Sánchez-de León, Y.; González-Meler, M.; Sturchio, N. C.; Wise, D. H.; Norby, R. J.

2008-12-01

The effects of global change on earthworms and their associated feedbacks on soil and ecosystem processes have been largely overlooked. We studied how the responses of a temperate deciduous forest to elevated carbon dioxide atmospheric concentrations (e[CO2]) influence earthworms and the soil processes affected by them. Our objectives were to: i) identify soil layers of active soil mixing under e[CO2] and current carbon dioxide atmospheric concentrations (c[CO2]) using fallout cesium (137Cs), ii) study how e[CO2] affects earthworm populations, iii) understand the relationship between soil mixing and earthworms at our study site, and iv) identify the implications of earthworm-mediated soil mixing for the carbon budget of a temperate forest. To study soil mixing, we measured vertical 137Cs activity in soil cores (0-24 cm depth) collected in replicated e[CO2] and c[CO2] sweetgum (Liquidambar styraciflua) plots (n = 2) in a Free Air CO2 Enrichment (FACE) ecosystem experiment at Oak Ridge National Laboratory. We measured earthworm density and fresh weight in the plots in areas adjacent to where soil cores were taken. Preliminary results on the vertical distribution of 137Cs in the c[CO2] treatments showed that higher 137Cs activity was located from 8-16 cm depth and no 137Cs activity was measured below 20 cm. In contrast, in the e[CO2] treatment, peak 137Cs activity was slightly deeper (10-18 cm), and 137Cs activity was still measured below 22 cm. Mean earthworm density was higher in e[CO2] than c[CO2] treatments (168 m-2 and 87 m-2, respectively; p = 0.046); earthworm fresh weights, however, did not differ significantly between treatments (32 g m-2 and 18 g m-2, respectively; p = 0.182). The 137Cs vertical distribution suggest that soil mixing occurs deeper in e[CO2] than in c[CO2] treatments, which is consistent with higher earthworm densities in e[CO2] than in c[CO2] treatments. Mixing deeper low carbon content soil with shallower high carbon soil may result in a dilution of net carbon inputs in forest soils exposed to e[CO2]. Vertical dilution of new carbon may explain why carbon accrual is detected only near the surface at this FACE site. By identifying the depths of active soil mixing and possible soil mixing mechanisms (e.g. earthworms), accounting of new organic carbon accrual could be more reliably determined for forest soils in response to e[CO2] conditions.

Mapping the Spatial Distribution of CO2 release from Kīlauea Volcano, Hawaii, USA

NASA Astrophysics Data System (ADS)

Elias, T.; Werner, C. A.; Kern, C.; Sutton, A. J.; Hauri, E. H.; Kelly, P. J.

2014-12-01

Kīlauea Volcano is a large emitter of volcanic CO2 with emission rates ranging from 7500-30,000 t/d. However, Kīlauea presents a challenging situation for CO2 emission rate measurement in that the main source of SO2 is the active vent in Halema'uma'u Crater, whereas CO2 emits mainly from a large (> 1km2) diffuse region east of the vent. Previous researchers recognized this issue and advocated for the use of a plume-integrated concentration ratio paired with the SO2 emission to determine CO2 emission rates; however, this worked best prior to the opening of the summit vent in 2008, or when SO2emission was still diffuse as opposed to focused degassing from the vent. We used two techniques to study the spatial distribution and temporal variability of CO2 release from the summit caldera in July, 2014. Eddy covariance measurements made at 14 locations in the area of diffuse emission resulted in elevated fluxes that generally ranged from 500 to > 5000 g/m2d, or typical of other volcanic and hydrothermal areas worldwide. MultiGas measurements of the CO2 and SO2 concentration in air at 1-m above the ground identified approximately seven areas of elevated area of CO2 degassing in the caldera. The CO2 concentrations in air were spatially well correlated to approximately 100 m and displayed anisotropy that was consistent with the measured wind direction. Areas of highest CO2 concentration correlated with the areas of highest flux using the eddy covariance method and were found near the middle of the caldera approximately 1 km NE of the active vent. This area overlies the inferred location of the shallow summit reservoir, and is characterized by linear fractures with adhered sublimate deposits at the surface. A few of the fractures are visibly fuming, but much of the degassing in the area is not apparent. Future work includes monitoring the fluxes in this area over time, and attempting to quantify emission rates from the areas of measured flux.

Training Graduate and Undergraduate Students in Simulation and Risk Assessment for Carbon Sequestration

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCray, John

Capturing carbon dioxide (CO2) and injecting it into deep underground formations for storage (carbon capture and underground storage, or CCUS) is one way of reducing anthropogenic CO2 emissions. Gas or aqueous-phase leakage may occur due to transport via faults and fractures, through faulty well bores, or through leaky confining materials. Contaminants of concern include aqueous salts and dissolved solids, gaseous or aqueous-phase organic contaminants, and acidic gas or aqueous-phase fluids that can liberate metals from aquifer minerals. Understanding the mechanisms and parameters that can contribute to leakage of the CO2 and the ultimate impact on shallow water aquifers that overliemore » injection formations is an important step in evaluating the efficacy and risks associated with long-term CO2 storage. Three students were supported on the grant Training Graduate and Undergraduate Students in Simulation and Risk Assessment for Carbon Sequestration. These three students each examined a different aspect of simulation and risk assessment related to carbon dioxide sequestration and the potential impacts of CO2 leakage. Two performed numerical simulation studies, one to assess leakage rates as a function of fault and deep reservoir parameters and one to develop a method for quantitative risk assessment in the event of a CO2 leak and subsequent changes in groundwater chemistry. A third student performed an experimental evaluation of the potential for metal release from sandstone aquifers under simulated leakage conditions. This study has resulted in two student first-authored published papers {Siirila, 2012 #560}{Kirsch, 2014 #770} and one currently in preparation {Menke, In prep. #809}.« less

Relationship between root water uptake and soil respiration: A modeling perspective

NASA Astrophysics Data System (ADS)

Teodosio, Bertrand; Pauwels, Valentijn R. N.; Loheide, Steven P.; Daly, Edoardo

2017-08-01

Soil moisture affects and is affected by root water uptake and at the same time drives soil CO2 dynamics. Selecting root water uptake formulations in models is important since this affects the estimation of actual transpiration and soil CO2 efflux. This study aims to compare different models combining the Richards equation for soil water flow to equations describing heat transfer and air-phase CO2 production and flow. A root water uptake model (RWC), accounting only for root water compensation by rescaling water uptake rates across the vertical profile, was compared to a model (XWP) estimating water uptake as a function of the difference between soil and root xylem water potential; the latter model can account for both compensation (XWPRWC) and hydraulic redistribution (XWPHR). Models were compared in a scenario with a shallow water table, where the formulation of root water uptake plays an important role in modeling daily patterns and magnitudes of transpiration rates and CO2 efflux. Model simulations for this scenario indicated up to 20% difference in the estimated water that transpired over 50 days and up to 14% difference in carbon emitted from the soil. The models showed reduction of transpiration rates associated with water stress affecting soil CO2 efflux, with magnitudes of soil CO2 efflux being larger for the XWPHR model in wet conditions and for the RWC model as the soil dried down. The study shows the importance of choosing root water uptake models not only for estimating transpiration but also for other processes controlled by soil water content.

Elevated [CO2] mitigates the effect of surface drought by stimulating root growth to access sub-soil water.

PubMed

Uddin, Shihab; Löw, Markus; Parvin, Shahnaj; Fitzgerald, Glenn J; Tausz-Posch, Sabine; Armstrong, Roger; O'Leary, Garry; Tausz, Michael

2018-01-01

Through stimulation of root growth, increasing atmospheric CO2 concentration ([CO2]) may facilitate access of crops to sub-soil water, which could potentially prolong physiological activity in dryland environments, particularly because crops are more water use efficient under elevated [CO2] (e[CO2]). This study investigated the effect of drought in shallow soil versus sub-soil on agronomic and physiological responses of wheat to e[CO2] in a glasshouse experiment. Wheat (Triticum aestivum L. cv. Yitpi) was grown in split-columns with the top (0-30 cm) and bottom (31-60 cm; 'sub-soil') soil layer hydraulically separated by a wax-coated, root-penetrable layer under ambient [CO2] (a[CO2], ∼400 μmol mol-1) or e[CO2] (∼700 μmol mol-1) [CO2]. Drought was imposed from stem-elongation in either the top or bottom soil layer or both by withholding 33% of the irrigation, resulting in four water treatments (WW, WD, DW, DD; D = drought, W = well-watered, letters denote water treatment in top and bottom soil layer, respectively). Leaf gas exchange was measured weekly from stem-elongation until anthesis. Above-and belowground biomass, grain yield and yield components were evaluated at three developmental stages (stem-elongation, anthesis and maturity). Compared with a[CO2], net assimilation rate was higher and stomatal conductance was lower under e[CO2], resulting in greater intrinsic water use efficiency. Elevated [CO2] stimulated both above- and belowground biomass as well as grain yield, however, this stimulation was greater under well-watered (WW) than drought (DD) throughout the whole soil profile. Imposition of drought in either or both soil layers decreased aboveground biomass and grain yield under both [CO2] compared to the well-watered treatment. However, the greatest 'CO2 fertilisation effect' was observed when drought was imposed in the top soil layer only (DW), and this was associated with e[CO2]-stimulation of root growth especially in the well-watered bottom layer. We suggest that stimulation of belowground biomass under e[CO2] will allow better access to sub-soil water during grain filling period, when additional water is converted into additional yield with high efficiency in Mediterranean-type dryland agro-ecosystems. If sufficient water is available in the sub-soil, e[CO2] may help mitigating the effect of drying surface soil.

Framework of barrier reefs threatened by ocean acidification.

PubMed

Comeau, Steeve; Lantz, Coulson A; Edmunds, Peter J; Carpenter, Robert C

2016-03-01

To date, studies of ocean acidification (OA) on coral reefs have focused on organisms rather than communities, and the few community effects that have been addressed have focused on shallow back reef habitats. The effects of OA on outer barrier reefs, which are the most striking of coral reef habitats and are functionally and physically different from back reefs, are unknown. Using 5-m long outdoor flumes to create treatment conditions, we constructed coral reef communities comprised of calcified algae, corals, and reef pavement that were assembled to match the community structure at 17 m depth on the outer barrier reef of Moorea, French Polynesia. Communities were maintained under ambient and 1200 μatm pCO2 for 7 weeks, and net calcification rates were measured at different flow speeds. Community net calcification was significantly affected by OA, especially at night when net calcification was depressed ~78% compared to ambient pCO2 . Flow speed (2-14 cm s(-1) ) enhanced net calcification only at night under elevated pCO2 . Reef pavement also was affected by OA, with dissolution ~86% higher under elevated pCO2 compared to ambient pCO2 . These results suggest that net accretion of outer barrier reef communities will decline under OA conditions predicted within the next 100 years, largely because of increased dissolution of reef pavement. Such extensive dissolution poses a threat to the carbonate foundation of barrier reef communities. © 2015 John Wiley & Sons Ltd.

Eruption and degassing dynamics of the major August 2015 Piton de la Fournaise eruption

NASA Astrophysics Data System (ADS)

Di Muro, Andrea; Arellano, Santiago; Aiuppa, Alessandro; Bachelery, Patrick; Boudoire, Guillaume; Coppola, Diego; Ferrazzini, Valerie; Galle, Bo; Giudice, Gaetano; Gurioli, Lucia; Harris, Andy; Liuzzo, Marco; Metrich, Nicole; Moune, Severine; Peltier, Aline; Villeneuve, Nicolas; Vlastelic, Ivan

2016-04-01

Piton de la Fournaise (PdF) shield volcano is one of the most active basaltic volcanoes in the World with one eruption every nine months, on average. This frequent volcanic activity is broadly bimodal, with frequent small volume, short lived eruptions (< 30 Mm3, most being < 10 Mm3) and less frequent relatively large (50-210 Mm3) and long lasting (months) eruptions. After the major caldera forming event of 2007, the volcano produced several short lived small volume summit to proximal eruptions of relatively evolved cotectic magmas and relatively long repose periods (up to 3.5 years between 2010 and 2014). The August 2015 eruption was the first large (45±15 Mm3) and long lasting (2 months) eruption since 2007 and the only event to be fully monitored by the new gas geochemical network of Piton de la Fournaise volcanological observatory (DOAS, MultiGaS, diffuse CO2 soil emissions). Regular lava and tephra sampling was also performed for geochemical and petrological analysis. The eruption was preceded by a significant increase in CO2 soil emissions at distal soil stations (ca. 15 km from the summit), with CO2 enrichment also being recorded at summit low temperature fumaroles. Eruptive products were spectacularly zoned, with plagioclase and pyroxene being abundant in the early erupted products and olivine being the main phase in the late-erupted lavas. Total gas emissions at the eruptive vent underwent a decrease during the first half of the eruption and then an increase, mirroring the time evolution of magma discharge rate (from 5-10 m3/s in September to 15-30 m3/s in late-October) and the progressive change in magma composition. In spite of significant evolution in magma and gas output, CO2/SO2 ratios in high temperature gases remained quite low (< 0.3) and with little temporal change. Geochemical data indicated that this relatively long-lived eruption corresponded to the progressive drainage of most of the shallow part of PdF plumbing system, triggered by a new pulse of deep magma. While erupted magma and high temperature gases were mostly provided by the shallow part of the system, distal sites and summit low temperature fumaroles recorded a deeper triggering mechanism.

Natural contamination with arsenic and other trace elements in groundwater of the Central-West region of Chaco, Argentina.

PubMed

Blanes, Patricia S; Buchhamer, Edgar E; Giménez, María C

2011-01-01

This study covered the central agricultural region of the Chaco province, which lacks a permanent river networks. However, during the rainy period there is localized groundwater recharge. About 84 groundwater samples were taken during the period April-December 2007. These groundwater samples were collected from two different depths: 62 samples from shallow wells (4 to 20 m) and 24 samples from deep wells (20 to 100 m). Chemical variables were determined: pH, specific conductance, total dissolved solid, hardness, alkalinity, HCO(3)-, CO(3)(2-), SO(4)(2-), Cl-, NO(3)-, NO(2) -, NH(4)+, F-, As((tot)), Na+, K+, Ca2+, Mg2+, Fe, Cu, Ni, Pb and Zn. The chemical composition of groundwater in the study area is dominantly sodium bicarbonate and sodium chloride bicarbonate, comprising more than 60% (52/86) of shallow and deep groundwater samples. Of the 86 analyzed groundwater samples, 88% exceeded the WHO (World Health Organization) and CAA (Código Alimentario Argentino) standards (10 μg/L) for As (arsenic) and 9% exceeded the WHO standard (1.5 mg/L) for F(-).Groundwater highly contaminated with As (max. 1,073 μg/L) and F- (max. 4.2 mg/L) was found in shallow aquifer. The contaminated groundwater is characterized by high pH (max. 8.9), alkalinity (max. HCO(3)- 1,932 mg/L), SO(4)(2-) (max. 11,862 mg/L), Na(+) (max. 3,158 mg/L), Cl(-) (max. 10,493 mg/L) and electric conductivity greater than 33.3 μS/cm. Other associated elements (Ni, Pb, Cu and Zn) are present in low concentrations, except for Fe that in 32% of samples exceeded the guideline value of 0.3 mg/L suggested by the CAA.

Using the Bongwana natural CO2 release to understand leakage processes and develop monitoring

NASA Astrophysics Data System (ADS)

Jones, David; Johnson, Gareth; Hicks, Nigel; Bond, Clare; Gilfillan, Stuart; Kremer, Yannick; Lister, Bob; Nkwane, Mzikayise; Maupa, Thulani; Munyangane, Portia; Robey, Kate; Saunders, Ian; Shipton, Zoe; Pearce, Jonathan; Haszeldine, Stuart

2016-04-01

Natural CO2 leakage along the Bongwana Fault in South Africa is being studied to help understand processes of CO2 leakage and develop monitoring protocols. The Bongwana Fault crops out over approximately 80 km in KwaZulu-Natal province, South Africa. In outcrop the fault is expressed as a broad fracture corridor in Dwyka Tillite, with fractures oriented approximately N-S. Natural emissions of CO2 occur at various points along the fault, manifest as travertine cones and terraces, bubbling in the rivers and as gas fluxes through soil. Exposed rock outcrop shows evidence for Fe-staining around fractures and is locally extensively kaolinitised. The gas has also been released through a shallow water well, and was exploited commercially in the past. Preliminary studies have been carried out to better document the surface emissions using near surface gas monitoring, understand the origin of the gas through major gas composition and stable and noble gas isotopes and improve understanding of the structural controls on gas leakage through mapping. In addition the impact of the leaking CO2 on local water sources (surface and ground) is being investigated, along with the seismic activity of the fault. The investigation will help to build technical capacity in South Africa and to develop monitoring techniques and plans for a future CO2 storage pilot there. Early results suggest that CO2 leakage is confined to a relatively small number of spatially-restricted locations along the weakly seismically active fault. Fracture permeability appears to be the main method by which the CO2 migrates to the surface. The bulk of the CO2 is of deep origin with a minor contribution from near surface biogenic processes as determined by major gas composition. Water chemistry, including pH, DO and TDS is notably different between CO2-rich and CO2-poor sites. Soil gas content and flux effectively delineates the fault trace in active leakage sites. The fault provides an effective testing ground for field-based monitoring with results to date indicating the methods and technologies tested successfully detect leaking CO2. Further work will investigate the source of the CO2 and attempt to quantify CO2 flux rates and detection thresholds.

Stable carbon isotopic evidence of methane consumption and production in three alpine ecosystems on the Qinghai-Tibetan Plateau

NASA Astrophysics Data System (ADS)

Kato, Tomomichi; Yamada, Keita; Tang, Yanhong; Yoshida, Naohiro; Wada, Eitaro

2013-10-01

To understand the mechanisms of soil CH4 consumption and production in alpine ecosystems, we for the first time examined the stable carbon isotope ratio of CH4 (δ13C-CH4) at three major grassland vegetation types, alpine meadow, alpine shrub, and alpine wetland, on the Qinghai-Tibetan Plateau. The alpine meadow and shrub showed net CH4 absorption in their vertical profiles of CH4 concentration in summer, but a difference in their processes. Whereas the alpine shrub was dominated by CH4 consumption in its soil profile, CH4 production in the alpine meadow could slightly cancel consumed CH4 in shallow soil from -0.3 to -0.1 m. This potential CH4 production can be attributed to the relatively wet soil type of that ecosystem, which might allow methanogenesis to act in moist soil lumps in the shallow layer. The alpine wetland differed in methane production, consumption, and transport pathways between hummock and hollow plots. In summer, both plots were enriched in 13C-CH4 in dissolved CH4 in soil pore water, suggesting that CH4 production was conducted mainly by acetate fermentation. In autumn, CH4 production was shifted toward CO2/H2 reduction. Furthermore, in hummocks, plant-mediated transport of CH4 by vascular plants appeared to perform passive CH4 flow from deep soil to atmosphere, which allowed the produced CH4 to bypass the oxidation zone in shallow soil. In hollows, however, CH4 produced in shallow soil was subject to simultaneous oxidation. The fractional oxidation rate on gross CH4 production in hollows was estimated by simple mass balance model at 7-17% in summer and 35-36% in autumn.

Shallow gas in Cenozoic sediments of the Southern North Sea

NASA Astrophysics Data System (ADS)

Trampe, Anna F.; Lutz, Rüdiger; Franke, Dieter; Thöle, Hauke; Arfai, Jashar

2013-04-01

Shallow petroleum systems in the southern North Sea are known for several decades but they were not actively explored for a long time. In recent years these unconventional shallow petroleum systems are studied in greater detail and one shallow gas field (A-12) is in production in the Netherlands. Additionally, oil was encountered in Miocene sandstones in the southern Danish North Sea (Lille John well) just north of the Danish-German border. Seismic amplitude anomalies are an indication for hydrocarbons in sediments. Therefore we have mapped the occurrence of seismic amplitude anomalies in the German North Sea based on more than 25.000 km of 2D seismic data and around 4.000 km2 of 3D seismic data. Amplitude anomalies are ubiquitous phenomena in the study area. These anomalies are not only caused by hydrocarbons but also by changing lithologies e.g. peat or fluid migration. Therefore several classes of seismic anomalies, e.g. bright spots, chimneys, blanking areas and velocity pull-down were mapped. Examples for these classes were studied with AVO (amplitude variation with offset) analyses to verify the existence or non-existence of gas in the sediments. Shallow gas can be produced and transported through the dense pipeline grid of the southern and central North Sea or it could be burned offshore close to wind parks in small power plants and the electric energy then transported through the existing power connections of the wind parks. Thus enabling a continuous energy supply during calm wind periods. This study is carried out within the framework of the project "Geoscientific Potential of the German North Sea (GPDN)" in which the Cenozoic sedimentary system was mapped in great detail. A detailed model of delta evolution (Baltic river system) was developed which serves as a structural framework. The studied interval is time equivalent to the Utsira formation which is used offshore Norway for sequestration of CO2. These different possibilities of using or exploiting the underground emphasize the need for detailed knowledge on the underground for sound decisions on the future use of this area.

Tropical coral reef habitat in a geoengineered, high-CO2 world

NASA Astrophysics Data System (ADS)

Couce, E.; Irvine, P. J.; Gregorie, L. J.; Ridgwell, A.; Hendy, E. J.

2013-05-01

Continued anthropogenic CO2 emissions are expected to impact tropical coral reefs by further raising sea surface temperatures (SST) and intensifying ocean acidification (OA). Although geoengineering by means of solar radiation management (SRM) may mitigate temperature increases, OA will persist, raising important questions regarding the impact of different stressor combinations. We apply statistical Bioclimatic Envelope Models to project changes in shallow water tropical coral reef habitat as a single niche (without resolving biodiversity or community composition) under various representative concentration pathway and SRM scenarios, until 2070. We predict substantial reductions in habitat suitability centered on the Indo-Pacific Warm Pool under net anthropogenic radiative forcing of ≥3.0 W/m2. The near-term dominant risk to coral reefs is increasing SSTs; below 3 W/m2 reasonably favorable conditions are maintained, even when achieved by SRM with persisting OA. "Optimal" mitigation occurs at 1.5 W/m2 because tropical SSTs overcool in a fully geoengineered (i.e., preindustrial global mean temperature) world.

Chemical and stable isotopic evidence for water/rock interaction and biogenic origin of coalbed methane, Fort Union Formation, Powder River Basin, Wyoming and Montana U.S.A

USGS Publications Warehouse

Rice, C.A.; Flores, R.M.; Stricker, G.D.; Ellis, M.S.

2008-01-01

Significant amounts (> 36??million m3/day) of coalbed methane (CBM) are currently being extracted from coal beds in the Paleocene Fort Union Formation of the Powder River Basin of Wyoming and Montana. Information on processes that generate methane in these coalbed reservoirs is important for developing methods that will stimulate additional production. The chemical and isotopic compositions of gas and ground water from CBM wells throughout the basin reflect generation processes as well as those that affect water/rock interaction. Our study included analyses of water samples collected from 228 CBM wells. Major cations and anions were measured for all samples, ??DH2O and ??18OH2O were measured for 199 of the samples, and ??DCH4 of gas co-produced with water was measured for 100 of the samples. Results show that (1) water from Fort Union Formation coal beds is exclusively Na-HCO3-type water with low dissolved SO4 content (median < 1??mg/L) and little or no dissolved oxygen (< 0.15??mg/L), whereas shallow groundwater (depth generally < 120??m) is a mixed Ca-Mg-Na-SO4-HCO3 type; (2) water/rock interactions, such as cation exchange on clay minerals and precipitation/dissolution of CaCO3 and SO4 minerals, account for the accumulation of dissolved Na and depletion of Ca and Mg; (3) bacterially-mediated oxidation-reduction reactions account for high HCO3 (270-3310??mg/L) and low SO4 (median < 0.15??mg/L) values; (4) fractionation between ??DCH4 (- 283 to - 328 per mil) and ??DH2O (- 121 to - 167 per mil) indicates that the production of methane is primarily by biogenic CO2 reduction; and (5) values of ??DH2O and ??18OH2O (- 16 to - 22 per mil) have a wide range of values and plot near or above the global meteoric water line, indicating that the original meteoric water has been influenced by methanogenesis and by being mixed with surface and shallow groundwater.

Fault-controlled advective, diffusive, and eruptive CO 2 leakage from natural reservoirs in the Colorado Plateau, East-Central Utah

NASA Astrophysics Data System (ADS)

Jung, Na-Hyun

This study investigated a natural analogue for CO2 leakage near Green River, Utah, aiming to understand the influence of various factors on CO2 leakage and to reliably predict underground CO2 behavior after injection for geologic CO2 sequestration. Advective, diffusive, and eruptive characteristics of CO2 leakage were assessed via a soil CO2 flux survey and numerical modeling. The field results show anomalous CO2 fluxes (> 10 g m-2 d-1 ) along the faults, particularly adjacent to CO2-driven cold springs and geysers (e.g., 36,259 g m-2 d-1 at Crystal Geyser), ancient travertines (e.g., 5,917 g m-2 d-1), joint zones in sandstone (e.g., 120 g m-2 d-1), and brine discharge zones (e.g., 5,515 g m-2 d-1). Combined with similar isotopic ratios of gas and progressive evolution of brine chemistry at springs and geysers, a gradual decrease of soil CO2 flux from the Little Grand Wash (LGW; ~36,259 g m -2 d-1) to Salt Wash (SW; ~1,428 g m-2 d-1) fault zones reveals the same CO2 origin and potential southward transport of CO2 over 10-20 km. The numerical simulations exhibit lateral transport of free CO2 and CO2-rich brine from the LGW to SW fault zones through the regional aquifers (e.g., Entrada, Navajo, Kayenta, Wingate, White Rim). CO2 travels predominantly as an aqueous phase (XCO2=~0.045) as previously suggested, giving rise to the convective instability that further accelerates CO2 dissolution. While the buoyant free CO2 always tends to ascend, a fraction of dense CO2-rich brine flows laterally into the aquifer and mixes with the formation fluids during upward migration along the fault. The fault always enhances advective CO2 transport regardless of its permeability (k). However, only low-k fault prevents unconditional upright migration of CO2 and induces fault-parallel movement, feeding the northern aquifers with more CO2. Low-k fault also impedes lateral southward fluid flow from the northern aquifers, developing anticlinal CO2 traps at shallow depths (<300 m). The regional k of the LGW fault in which CO2 flux coincides with the field spatial variation is estimated between 0.01.kh<0.1 md and 0.5.k v<1 md. The anticlinal trap serves as an essential fluid source and conducive environment for intensifying eruption at Crystal Geyser. Geyser-like discharge in the simulations sensitively responds to varying well permeability and radius, and CO2 recharge rate. Indeed, the cycling behavior of wellbore CO2 leakage turns into a constant discharge with time, indicating the potential switch of Crystal Geyser to a CO2-driven cold-water spring or even fumarole.

In situ evaluation of air-sea CO2 gas transfer velocity in an inner estuary using eddy covariance - with a special focus on the importance of using reliable CO2-fluxes

NASA Astrophysics Data System (ADS)

Jørgensen, E. T.; Sørensen, L. L.; Jensen, B.; Sejr, M. K.

2012-04-01

The air-sea exchange of CO2 or CO2 flux is driven by the difference in the partial pressure of CO2 in the water and the atmosphere (ΔpCO2), the solubility of CO2 (K0) and the gas transfer velocity (k) (Wanninkhof et al., 2009;Weiss, 1974) . ΔpCO2 and K0 are determined with relatively high precision and it is estimated that the biggest uncertainty when modelling the air-sea flux is the parameterization of k. As an example; the estimated global air-sea flux increases by 70 % when using the parameterization by Wanninkhof and McGillis (1999) instead of Wanninkhof (1992) (Rutgersson et al., 2008). In coastal areas the uncertainty is even higher and only few studies have focused on determining transfer velocity for the coastal waters and even fewer on estuaries (Borges et al., 2004;Rutgersson et al., 2008). The transfer velocity (k600) of CO2 in the inner estuary of Roskilde Fjord, Denmark was investigated using eddy covariance CO2 fluxes (ECM) and directly measured ΔpCO2 during May and June 2010. The data was strictly sorted to heighten the certainty of the results and the outcome was; DS1; using only ECM, and DS2; including the inertial dissipation method (IDM). The inner part of Roskilde Fjord showed to be a very biological active CO2 sink and preliminary results showed that the average k600 was more than 10 times higher than transfer velocities from similar studies of other coastal areas. The much higher transfer velocities were estimated to be caused by the greater fetch and shallower water in Roskilde Fjord, which indicated that turbulence in both air and water influence k600. The wind speed parameterization of k600 using DS1 showed some scatter but when including IDM the r2 of DS2 reached 0.93 with an exponential parameterization, where U10 was based on the Businger-Dyer relationships using friction velocity and atmospheric stability. This indicates that some of the uncertainties coupled with CO2 fluxes calculated by the ECM are removed when including the IDM.

Time-lapse 3-D electrical resistance tomography inversion for crosswell monitoring of dissolved and supercritical CO 2 flow at two field sites: Escatawpa and Cranfield, Mississippi, USA

DOE PAGES

Commer, Michael; Doetsch, Joseph; Dafflon, Baptiste; ...

2016-06-01

In this study, we advance the understanding of three-dimensional (3-D) electrical resistivity tomography (ERT) for monitoring long-term CO 2 storage by analyzing two previously published field time-lapse data sets. We address two important aspects of ERT inversion-the issue of resolution decay, a general impediment to the ERT method, and the issue of potentially misleading imaging artifacts due to 2-D model assumptions. The first study analyzes data from a shallow dissolved-CO 2 injection experiment near Escatawpa (Mississippi), where ERT data were collected in a 3-D crosswell configuration. Here, we apply a focusing approach designed for crosswell configurations to counteract resolution lossmore » in the inter-wellbore area, with synthetic studies demonstrating its effectiveness. The 3-D field data analysis reveals an initially southwards-trending flow path development and a dispersing plume development in the downgradient inter-well region. The second data set was collected during a deep (over 3 km) injection of supercritical CO 2 near Cranfield (Mississippi). Comparative 2-D and 3-D inversions reveal the projection of off-planar anomalies onto the cross-section, a typical artifact introduced by 2-D model assumptions. Conforming 3-D images from two different algorithms support earlier hydrological investigations, indicating a conduit system where flow velocity variations lead to a circumvention of a close observation well and an onset of increased CO 2 saturation downgradient from this well. We relate lateral permeability variations indicated by an independently obtained hydrological analysis to this consistently observed pattern in the CO 2 spatial plume evolution.« less

The urban atmosphere as a non-point source for the transport of MTBE and other volatile organic compounds (VOCS) to shallow groundwater

USGS Publications Warehouse

Pankow, J.F.; Thomson, N.R.; Johnson, Richard L.; Baehr, A.L.; Zogorski, J.S.

1997-01-01

Infiltration and dispersion (including molecular diffusion) can transport volatile organic compounds (VOCs) from urban air into shallow groundwater. The gasoline additive methyl-tert-butyl ether (MTBE) is of special interest because of its (1) current levels in some urban air, (2) strong partitioning from air into water, (3) resistance to degradation, (4) use as an octane-booster since the 1970s, (5) rapidly increasing use in the 1990s to reduce CO and O3 in urban air, and (6) its frequent detection at low microgram per liter levels in shallow urban groundwater in Denver, New England, and elsewhere. Numerical simulations were conducted using a 1-D model domain set in medium sand (depth to water table = 5 m) to provide a test of whether MTBE and other atmospheric VOCs could move to shallow groundwater within the 10−15 y time frame over which MTBE has now been used in large amounts. Degradation and sorption were assumed negligible. In case 1 (no infiltration, steady atmospheric source), 10 y was not long enough to permit significant VOC movement by diffusion into shallow groundwater. Case 2 considered a steady atmospheric source plus 36 cm/y of net infiltration; groundwater at 2 m below the water table became nearly saturated with atmospheric levels of VOC within 5 y. Case 3 was similar to case 2, but considered the source to be seasonal, being “on” for only 5 of 12 months each year, as with the use of MTBE during the winter fuel-oxygenate season; groundwater at 2 m below the water table became equilibrated with 5/12 of the “source-on” concentration within 5 y. Cases 4 and 5 added an evapotranspiration (ET) loss of 36 cm/y, resulting in no net recharge. Case 4 took the ET from the surface, and case 5 took the ET from the capillary fringe at a depth of 3.5 m. Net VOC mass transfer to shallow groundwater after 5 y was less for both cases 4 and 5 than for case 3. However, it was significantly greater for cases 4 and 5 than for case 1, even though cases 1, 4, and 5 were all no-net recharge cases. The mechanism responsible for this effect was the dispersion acting on each downward infiltration event, and also on the ET-induced flow. The ability of MTBE to reach groundwater in cases 2−5 is taken as evidence of the potential importance of urban air as a non-point source for VOCs in shallow urban groundwater. Two subcases were run for both case 4 and case 5:  subcase a (water and VOCs move with ET) and subcase b (water only moves with ET).

Monitoring Shallow Subsurface CO2 Migration using Electrical Imaging Technique, Pilot Site in Brazil

NASA Astrophysics Data System (ADS)

Oliva, A.; Chang, H. K.; Moreira, A.

2013-12-01

Carbon Capture and Geological Sequestration (CCGS or CCS) is one of the main technological strategies targeting Greenhouse Gases (GHG) emissions reduction, with special emphasis on carbon dioxide (CO2) coming from industrial sources. CCGS integrates the so called Carbon Management Strategies, as indicated by the Intergovernmental Panel on Climate Change (IPCC), and is the basis of main technical route likely to enable substantial emission reduction in a safe, quick and cost-effective way. Currently one of the main challenges in the area of CO2 storage research is to grant the development, testing and validation of accurate and efficient measuring, monitoring and verification (MMV) techniques to be deployed at the final storage site, targeting maximum storage efficiency at the minimal leakage risk levels. The implementation of the first CO2 MMV field lab in Brazil, located in Florianópolis, Santa Catarina state, offered an excellent opportunity for running controlled release experiments in a real open air environment. The purpose of this work is to present the results of a time lapse monitoring experiment of CO2 migration in both saturated and unsaturated sand-rich sediments, using electrical imaging technique. The experiment covered an area of approximately 6300 m2 and CO2 was continuously injected at depth of 8 m, during 12 days, at an average rate of 90 g/ day, totalizing 1080 g of injected CO2. 2D and 3D electrical images using Wenner array were acquired daily during 13 consecutive days. Comparison of post injection electrical imaging results with pre injection images shows change in resistivity values consistent with migration pathways of CO2. A pronounced increase in resistivity values (up to ~ 500 ohm.m) with respect to the pre-injection values occurs in the vicinity of the injection well. Background values of 530 ohm.m have changed to 1118 ohm.m, right after injection. Changes in resistivity values progressively diminish outward of the well, following groundwater flow path.

Climate Sensitivity to Shallow Groundwater Dynamics Inferred from Historical Groundwater Level Observations and Climate Data

NASA Astrophysics Data System (ADS)

Seyoum, W. M.; Wahls, B.

2017-12-01

The effect of land surface processes (e.g., change in vegetation and snow cover, and change in soil moisture) on climate is well understood. However, the connection between shallow groundwater fluctuation and regional climate variability is still unresolved. This project focuses on sensitivity of climate to shallow groundwater dynamics by analyzing the impact of shallow groundwater on soil moisture and precipitation. The study use co-located measurements of daily soil moisture, depth to groundwater level (DGWL), and climate (precipitation (R) and air temperature) data. Statistical relationship between soil moisture and DGWL at different depth established. Frequency, mean and cumulative climate extremes (R90, R99, R < 1mm) examined and compared with depth to groundwater level information at Bellville station, IL. Result indicate soil moisture has a strong inverse relationship with depth to groundwater level (r -0.75) when DGWL is between 0 to 2 m (critical depth) depth from the ground. Beyond this depth, there is no statistically significant correlation or trend between soil moisture and GWL. Within this critical depth, soil moisture is more or less constant during wet days (R ≥ 1mm) even though DGWL is fluctuating. However, soil moisture decrease exponentially as DGWL declining during dry days (R < 1mm). Thus, soil moisture is highly likely dependent on groundwater feedback in the critical depth. Comparison of DGWL with frequency and cumulative of subsequent summer and fall extreme precipitation (DGWL leading by 4-7 months) indicate higher frequency and magnitude of extreme wet precipitation (Rm > 150 mm) occur when DGWL is within the critical depth. As DGWL decreases below 2 m, frequency and magnitude of extreme precipitation diminishes. On the other hand, DGWL has no significant relationship with subsequent extreme dry condition, there is no statistically significant trend between frequency of R < 1mm and DGWL. Generally, depth to groundwater level influence soil moisture within 0 to 2 m depth form the ground. Groundwater level close to the ground (0 - 2 m) seems likely influence subsequent extreme wet condition while not conclusive is the influence of declining groundwater level (beyond 2 m) to subsequent dry conditions. The result support the broad hypothesis that shallow groundwater can influence climate.

Bioavailable metals and cellular effects in the digestive gland of marine limpets living close to shallow water hydrothermal vents.

PubMed

Cunha, Luís; Amaral, André; Medeiros, Vera; Martins, Gustavo M; Wallenstein, Francisco F M M; Couto, Ruben P; Neto, Ana I; Rodrigues, Armindo

2008-04-01

The pressure exerted by shallow water hydrothermal vents on edible gastropods and their cellular responses triggered by these stresses are almost unknown. The aims of this study were to evaluate the bioavailability of metals in the Macaronesian endemic limpet Patella candei gomesii living close to shallow water hydrothermal vents, and the structural differences in their digestive gland as well as the levels of apoptosis in that organ. Limpets were sampled in four sites, two with the presence of hydrothermalism and the other two without it. Whole body concentrations of several metals (Ca, Cd, Cs, Co, Cu, Fe, Hg, Mg, Mn, Pb, Rb, Se, Sr, and Zn) were obtained, morphometry analysis of the digestive gland and TUNEL test for apoptosis were also performed. Results revealed that the presence of shallow water hydrothermal vents is a source of chronic metal stress to limpets, imposing modifications in the morphometry and cell composition of the digestive gland of those limpets that may constitute cell and tissue adaptations to the environment they live in. This study sets up new baseline data for further research on the influence of shallow water hydrothermal vents over communities living in these habitats.

Open-path FTIR spectroscopy of magma degassing processes during eight lava fountains on Mount Etna

NASA Astrophysics Data System (ADS)

La Spina, Alessandro; Burton, Mike; Allard, Patrick; Alparone, Salvatore; Murè, Filippo

2016-04-01

In June-July 2001 a series of 16 discrete lava fountain paroxysms occurred at the Southeast summit crater (SEC) of Mount Etna, preceding a 28-day long violent flank eruption. Each paroxysm was preceded by lava effusion, growing seismic tremor and a crescendo of Strombolian explosive activity culminating into powerful lava fountaining up to 500m in height. During 8 of these 16 events we could measure the chemical composition of the magmatic gas phase (H2O, CO2, SO2, HCl, HF and CO), using open-path Fourier transform infrared (OP-FTIR) spectrometry at ˜1-2km distance from SEC and absorption spectra of the radiation emitted by hot lava fragments. We show that each fountaining episode was characterized by increasingly CO2-rich gas release, with CO2/SO2and CO2/HCl ratios peaking in coincidence with maxima in seismic tremor and fountain height, whilst the SO2/HCl ratio showed a weak inverse relationship with respect to eruption intensity. Moreover, peak values in both CO2/SO2ratio and seismic tremor amplitude for each paroxysm were found to increase linearly in proportion with the repose interval (2-6 days) between lava fountains. These observations, together with a model of volatile degassing at Etna, support the following driving process. Prior to and during the June-July 2001 lava fountain sequence, the shallow (˜2km) magma reservoir feeding SEC received an increasing influx of deeply derived carbon dioxide, likely promoted by the deep ascent of volatile-rich primitive basalt that produced the subsequent flank eruption. This CO2-rich gas supply led to gas accumulation and overpressure in SEC reservoir, generating a bubble foam layer whose periodical collapse powered the successive fountaining events. The anti-correlation between SO2/HCl and eruption intensity is best explained by enhanced syn-eruptive degassing of chlorine from finer particles produced during more intense magma fragmentation.

Abiotic and seasonal control of soil-produced CO2 efflux in karstic ecosystems located in Oceanic and Mediterranean climates

NASA Astrophysics Data System (ADS)

Garcia-Anton, Elena; Cuezva, Soledad; Fernandez-Cortes, Angel; Alvarez-Gallego, Miriam; Pla, Concepcion; Benavente, David; Cañaveras, Juan Carlos; Sanchez-Moral, Sergio

2017-09-01

This study characterizes the processes involved in seasonal CO2 exchange between soils and shallow underground systems and explores the contribution of the different biotic and abiotic sources as a function of changing weather conditions. We spatially and temporally investigated five karstic caves across the Iberian Peninsula, which presented different microclimatic, geologic and geomorphologic features. The locations present Mediterranean and Oceanic climates. Spot air sampling of CO2 (g) and δ13CO2 in the caves, soils and outside atmospheric air was periodically conducted. The isotopic ratio of the source contribution enhancing the CO2 concentration was calculated using the Keeling model. We compared the isotopic ratio of the source in the soil (δ13Cs-soil) with that in the soil-underground system (δ13Cs-system). Although the studied field sites have different features, we found common seasonal trends in their values, which suggests a climatic control over the soil air CO2 and the δ13CO2 of the sources of CO2 in the soil (δ13Cs-soil) and the system (δ13Cs-system). The roots respiration and soil organic matter degradation are the main source of CO2 in underground environments, and the inlet of the gas is mainly driven by diffusion and advection. Drier and warmer conditions enhance soil-exterior CO2 interchange, reducing the CO2 concentration and increasing the δ13CO2 of the soil air. Moreover, the isotopic ratio of the source of CO2 in both the soil and the system tends to heavier values throughout the dry and warm season. We conclude that seasonal variations of soil CO2 concentration and its 13C/12C isotopic ratio are mainly regulated by thermo-hygrometric conditions. In cold and wet seasons, the increase of soil moisture reduces soil diffusivity and allows the storage of CO2 in the subsoil. During dry and warm seasons, the evaporation of soil water favours diffusive and advective transport of soil-derived CO2 to the atmosphere. The soil CO2 diffusion is enough important during this season to modify the isotopic ratio of soil produced CO2 (3-6‰ heavier). Drought induces release of CO2 with an isotopic ratio heavier than produced by organic sources. Consequently, climatic conditions drive abiotic processes that turn regulate a seasonal storage of soil-produced CO2 within soil and underground systems. The results here obtained imply that abiotic emissions of soil-produced CO2 must be an inherent consequence of droughts, which intensification has been forecasted at global scale in the next 100 years.

Rapid emergence of life shown by discovery of 3,700-million-year-old microbial structures.

PubMed

Nutman, Allen P; Bennett, Vickie C; Friend, Clark R L; Van Kranendonk, Martin J; Chivas, Allan R

2016-09-22

Biological activity is a major factor in Earth's chemical cycles, including facilitating CO 2 sequestration and providing climate feedbacks. Thus a key question in Earth's evolution is when did life arise and impact hydrosphere-atmosphere-lithosphere chemical cycles? Until now, evidence for the oldest life on Earth focused on debated stable isotopic signatures of 3,800-3,700 million year (Myr)-old metamorphosed sedimentary rocks and minerals from the Isua supracrustal belt (ISB), southwest Greenland. Here we report evidence for ancient life from a newly exposed outcrop of 3,700-Myr-old metacarbonate rocks in the ISB that contain 1-4-cm-high stromatolites-macroscopically layered structures produced by microbial communities. The ISB stromatolites grew in a shallow marine environment, as indicated by seawater-like rare-earth element plus yttrium trace element signatures of the metacarbonates, and by interlayered detrital sedimentary rocks with cross-lamination and storm-wave generated breccias. The ISB stromatolites predate by 220 Myr the previous most convincing and generally accepted multidisciplinary evidence for oldest life remains in the 3,480-Myr-old Dresser Formation of the Pilbara Craton, Australia. The presence of the ISB stromatolites demonstrates the establishment of shallow marine carbonate production with biotic CO 2 sequestration by 3,700 million years ago (Ma), near the start of Earth's sedimentary record. A sophistication of life by 3,700 Ma is in accord with genetic molecular clock studies placing life's origin in the Hadean eon (>4,000 Ma).

The Effects of Different Scales of Topographic Variation on Shallow Groundwater Flow in an Arctic Watershed

NASA Astrophysics Data System (ADS)

Nicholaides, K. D.; O'Connor, M.; Cardenas, M. B.; Neilson, B. T.; Kling, G. W.

2017-12-01

Arctic permafrost degradation is occurring as global temperatures increase. In addition, recent evidence shows the Arctic is shifting from a sink to a source of carbon to the atmosphere. However, the cause of this shift is unclear, as is the role of newly exposed organic soil carbon leaching into groundwater and transported to surface water. This soil carbon may be photo-oxidized to CO2 or microbially respired to CO2 and methane, adding greenhouse gases to the atmosphere. The fate of carbon in permafrost is largely governed by the length of time spent in transport and the surface or subsurface route it follows. However, groundwater flow regimes within shallow active layer aquifers overlying permafrost is poorly understood. We determined to what extent smaller scale topography influences groundwater flow and residence times in arctic tundra. The study focused on Imnavait Creek watershed, a 1st-order drainage on the Alaskan North Slope underlain by continuous permafrost. We used direct measurements of hydraulic conductivities and porosities over a range of depths as well as basin-scale topography to develop vertically-integrated groundwater flow models. By systematically decreasing the amount of topographic detail, we were able to compare the influence of more detailed topography on groundwater flow estimates. Scaling up this model will be a useful tool in understanding how larger basins in permafrost will respond to future climate change and their contributions to greenhouse gases in the atmosphere.

Sundaland Peat Carbon Dynamics and Its Contribution to the Holocene Atmospheric CO2 Concentration

NASA Astrophysics Data System (ADS)

Abrams, Jesse F.; Hohn, Sönke; Rixen, Tim; Merico, Agostino

2018-04-01

The Sunda Shelf is a large submerged extension of the continental shelf of mainland Asia, joining the islands of Borneo, Java, and Sumatra and forming the shallow seabed of the South China Sea. Recent studies identified present-day peatlands in Southeast Asia as a globally important carbon reservoir. However, little is known about Sundaland paleopeatlands and their role in the global carbon cycle since the Last Glacial Maximum. Using a topography-based, sea level-driven model, we estimate the potential spatial extent of peatlands during the late Pleistocene and early Holocene across the low-lying Sundaland plains. We then use the estimated peatland area together with data on carbon accumulation rates to calculate the total peat carbon pool on the Sunda Shelf. Finally, using a global biogeochemical model, we analyze the relative influence of the predicted Sundaland peat dynamics and other carbon change mechanisms, specifically high-latitude forest growth and peat formation, shallow sea carbonate deposition, ocean warming, and combinations of them, on the global carbon cycle of the Holocene. We identify a feedback mechanism between sea level and peatland carbon sequestration in Sundaland that reduced atmospheric CO2 concentration by about 4-5 ppm and increased δ13C by 0.05‰ during the Holocene. We also show that a concurrence of mechanisms that includes Sundaland peat dynamics produces model results that are consistent with proxy records, especially with respect to δ13C.

Water level, vegetation composition and plant productivity explain greenhouse gas fluxes in temperate cutover fens after inundation

NASA Astrophysics Data System (ADS)

Minke, M.; Augustin, J.; Burlo, A.; Yarmashuk, T.; Chuvashova, H.; Thiele, A.; Freibauer, A.; Tikhonov, V.; Hoffmann, M.

2015-10-01

Rewetting of temperate continental cutover peatlands generally implies the creation of flooded areas, which are - dependent on water depth - colonized by helophytes such as Eriophorum angustifolium, Carex spp., Typha latifolia or Phragmites australis. Reeds of Typha and Phragmites are reported to be large sources of methane, but data on net CO2 uptake are contradictory for Typha and rare for Phragmites. This paper describes the effect of vegetation, water level and nutrient conditions on greenhouse gas (GHG) emissions for representative vegetation types along water level gradients at two rewetted cutover fens (mesotrophic and eutrophic) in Belarus. Greenhouse emissions were measured with manual chambers in weekly to few - weekly intervals over a two years period and interpolated by modelling. All sites had negligible nitrous oxide exchange rates. Most sites were carbon sinks and small GHG sources. Methane emissions were generally associated with net ecosystem CO2 uptake. Small sedges were minor methane emitters and net CO2 sinks, while Phragmites australis sites released large amounts of methane and sequestered very much CO2. Variability of both fluxes increased with site productivity. Floating mats composed of Carex tussocks and Typha latifolia were a source for both methane and CO2. We conclude that shallow, stable flooding is a better measure to arrive at low GHG emissions than deep flooding, and that the risk of high GHG emissions consequent on rewetting is larger for eutrophic than for mesotrophic peatlands.

Seismic Investigation of Magmatic Unrest Beneath Mammoth Mountain, California Using Waveform Cross-Correlation

NASA Astrophysics Data System (ADS)

Lin, G.

2012-12-01

We investigate the seismic and magmatic activity during an 11-month-long seismic swarm between 1989 and 1990 beneath Mammoth Mountain (MM) at the southwest rim of Long Valley caldera in eastern California. This swarm is believed to be results of a shallow intrusion of magma beneath MM. It was followed by the emissions of carbon dioxide (CO2) gas, which caused tree-killings in 1990 and posed a significant human health risk around MM. In this study, we develop a new three-dimensional (3-D) P-wave velocity model using first-arrival picks by applying the simul2000 tomographic algorithm. The resulting 3-D model is correlated with the surface geological features at shallow depths and is used to constrain absolute earthquake locations for all local events in our study. We compute both P- and S-wave differential times using a time-domain waveform cross-correlation method. We then apply similar event cluster analysis and differential time location approach to further improve relative event location accuracy. A dramatic sharpening of seismicity pattern is obtained after these processes. The estimated uncertainties are a few meters in relative location and ~100 meters in absolute location. We also apply a high-resolution approach to estimate in situ near-source Vp/Vs ratios using differential times from waveform cross-correlation. This method provides highly precise results because cross-correlation can measure differential times to within a few milliseconds and can achieve a precision of 0.001 in estimated Vp/Vs ratio. Our results show a circular ring-like seismicity pattern with a diameter of 2 km between 3 and 8 km depth. These events are distributed in an anomalous body with low Vp and high Vp/Vs, which may be caused by over-pressured magmatically derived fluids. At shallower depths, we observe very low Vp/Vs anomalies beneath MM from the surface to 1 km below sea level whose locations agree with the proposed CO2 reservoir in previous studies. The systematic spatial and temporal migration of seismicity suggests fluid involvement in the seismic swarm. Our results will provide more robust constraints on the crustal structure and volcanic processes beneath Mammoth Mountain.

Response of anaerobic carbon cycling to water table manipulation in an Alaskan rich fen

USGS Publications Warehouse

Kane, E.S.; Chivers, M.R.; Turetsky, M.R.; Treat, C.C.; Petersen, D.G.; Waldrop, M.; Harden, J.W.; McGuire, A.D.

2013-01-01

To test the effects of altered hydrology on organic soil decomposition, we investigated CO2 and CH4 production potential of rich-fen peat (mean surface pH = 6.3) collected from a field water table manipulation experiment including control, raised and lowered water table treatments. Mean anaerobic CO2 production potential at 10 cm depth (14.1 ± 0.9 μmol C g−1 d−1) was as high as aerobic CO2 production potential (10.6 ± 1.5 μmol C g−1 d−1), while CH4 production was low (mean of 7.8 ± 1.5 nmol C g−1 d−1). Denitrification enzyme activity indicated a very high denitrification potential (197 ± 23 μg N g−1 d−1), but net NO-3 reduction suggested this was a relatively minor pathway for anaerobic CO2 production. Abundances of denitrifier genes (nirK and nosZ) did not change across water table treatments. SO2-4 reduction also did not appear to be an important pathway for anaerobic CO2 production. The net accumulation of acetate and formate as decomposition end products in the raised water table treatment suggested that fermentation was a significant pathway for carbon mineralization, even in the presence of NO-3. Dissolved organic carbon (DOC) concentrations were the strongest predictors of potential anaerobic and aerobic CO2 production. Across all water table treatments, the CO2:CH4 ratio increased with initial DOC leachate concentrations. While the field water table treatment did not have a significant effect on mean CO2 or CH4 production potential, the CO2:CH4 ratio was highest in shallow peat incubations from the drained treatment. These data suggest that with continued drying or with a more variable water table, anaerobic CO2 production may be favored over CH4 production in this rich fen. Future research examining the potential for dissolved organic substances to facilitate anaerobic respiration, or alternative redox processes that limit the effectiveness of organic acids as substrates in anaerobic metabolism, would help explain additional uncertainty concerning carbon mineralization in this system.

Investigation on H-containing shallow trap of hydrogenated TiO2 with in situ Fourier transform infrared diffuse reflection spectroscopy.

PubMed

Han, Bing; Hang Hu, Yun

2017-07-28

A novel technique, high temperature high pressure in situ Fourier transform infrared diffuse reflection spectroscopy, was successfully used to investigate the formation and stability of shallow trap states in P25 TiO 2 nanoparticles. Two types of shallow traps (with and without H atoms) were identified. The H-containing shallow trap can be easily generated by heating in H 2 atmosphere. However, the trap is unstable in vacuum at 600 °C. In contrast, the H-free shallow trap, which can be formed by heating in vacuum, is stable even at 600 °C. The energy gaps between shallow trap states and the conduction band are 0.09 eV for H-containing shallow trap and 0.13 eV for H-free shallow trap, indicating that the H-containing shallow trap state is closer to the conduction band than that without H.

Achieving high time-resolution with a new flow-through type analyzer for total inorganic carbon in seawater.

PubMed

Kimoto, Hideshi; Nozaki, Ken; Kudo, Setsuko; Kato, Ken; Negishi, Akira; Kayanne, Hajime

2002-03-01

A fully automated, continuous-flow-through type analyzer was developed to observe rapid changes in the concentration of total inorganic carbon (CT) in coastal zones. Seawater and an H3PO4 solution were fed into the analyzer's mixing coil by two high-precision valveless piston pumps. The CO2 was stripped from the seawater and moved into a carrier gas, using a newly developed continuous-flow-through CO2 extractor. A mass flow controller was used to assure a precise flow rate of the carrier gas. The CO2 concentration was then determined with a nondispersive infrared gas analyzer. This analyzer achieved a time-resolution of as good as 1 min. In field experiments on a shallow reef flat of Shiraho (Ishigaki Island, Southwest Japan), the analyzer detected short-term, yet extreme, variations in CT which manual sampling missed. Analytical values obtained by the analyzer on the boat were compared with those determined by potentiometric titration with a closed cell in a laboratory: CT(flow-through) = 0.980 x CT(titration) + 38.8 with r2 = 0.995 (n = 34; September 1998).

A product of its environment: the epaulette shark (Hemiscyllium ocellatum) exhibits physiological tolerance to elevated environmental CO2

PubMed Central

Heinrich, Dennis D. U.; Rummer, Jodie L.; Morash, Andrea J.; Watson, Sue-Ann; Simpfendorfer, Colin A.; Heupel, Michelle R.; Munday, Philip L.

2014-01-01

Ocean acidification, resulting from increasing anthropogenic CO2 emissions, is predicted to affect the physiological performance of many marine species. Recent studies have shown substantial reductions in aerobic performance in some teleost fish species, but no change or even enhanced performance in others. Notably lacking, however, are studies on the effects of near-future CO2 conditions on larger meso and apex predators, such as elasmobranchs. The epaulette shark (Hemiscyllium ocellatum) lives on shallow coral reef flats and in lagoons, where it may frequently encounter short-term periods of environmental hypoxia and elevated CO2, especially during nocturnal low tides. Indeed, H. ocellatum is remarkably tolerant to short periods (hours) of hypoxia, and possibly hypercapnia, but nothing is known about its response to prolonged exposure. We exposed H. ocellatum individuals to control (390 µatm) or one of two near-future CO2 treatments (600 or 880 µatm) for a minimum of 60 days and then measured key aspects of their respiratory physiology, namely the resting oxygen consumption rate, which is used to estimate resting metabolic rate, and critical oxygen tension, a proxy for hypoxia sensitivity. Neither of these respiratory attributes was affected by the long-term exposure to elevated CO2. Furthermore, there was no change in citrate synthase activity, a cellular indicator of aerobic energy production. Plasma bicarbonate concentrations were significantly elevated in sharks exposed to 600 and 880 µatm CO2 treatments, indicating that acidosis was probably prevented by regulatory changes in acid–base relevant ions. Epaulette sharks may therefore possess adaptations that confer tolerance to CO2 levels projected to occur in the ocean by the end of this century. It remains uncertain whether other elasmobranchs, especially pelagic species that do not experience such diurnal fluctuations in their environment, will be equally tolerant. PMID:27293668

Microbiological and Geochemical Survey of CO2-Dominated Mofette and Mineral Waters of the Cheb Basin, Czech Republic.

PubMed

Krauze, Patryk; Kämpf, Horst; Horn, Fabian; Liu, Qi; Voropaev, Andrey; Wagner, Dirk; Alawi, Mashal

2017-01-01

The Cheb Basin (NW Bohemia, Czech Republic) is a shallow, neogene intracontinental basin. It is a non-volcanic region which features frequent earthquake swarms and large-scale diffuse degassing of mantle-derived CO 2 at the surface that occurs in the form of CO 2 -rich mineral springs and wet and dry mofettes. So far, the influence of CO 2 degassing onto the microbial communities has been studied for soil environments, but not for aquatic systems. We hypothesized, that deep-trenching CO 2 conduits interconnect the subsurface with the surface. This admixture of deep thermal fluids should be reflected in geochemical parameters and in the microbial community compositions. In the present study four mineral water springs and two wet mofettes were investigated through an interdisciplinary survey. The waters were acidic and differed in terms of organic carbon and anion/cation concentrations. Element geochemical and isotope analyses of fluid components were used to verify the origin of the fluids. Prokaryotic communities were characterized through quantitative PCR and Illumina 16S rRNA gene sequencing. Putative chemolithotrophic, anaerobic and microaerophilic organisms connected to sulfur (e.g., Sulfuricurvum, Sulfurimonas ) and iron (e.g., Gallionella, Sideroxydans ) cycling shaped the core community. Additionally, CO 2 -influenced waters form an ecosystem containing many taxa that are usually found in marine or terrestrial subsurface ecosystems. Multivariate statistics highlighted the influence of environmental parameters such as pH, Fe 2+ concentration and conductivity on species distribution. The hydrochemical and microbiological survey introduces a new perspective on mofettes. Our results support that mofettes are either analogs or rather windows into the deep biosphere and furthermore enable access to deeply buried paleo-sediments.

Microbiological and Geochemical Survey of CO2-Dominated Mofette and Mineral Waters of the Cheb Basin, Czech Republic

PubMed Central

Krauze, Patryk; Kämpf, Horst; Horn, Fabian; Liu, Qi; Voropaev, Andrey; Wagner, Dirk; Alawi, Mashal

2017-01-01

The Cheb Basin (NW Bohemia, Czech Republic) is a shallow, neogene intracontinental basin. It is a non-volcanic region which features frequent earthquake swarms and large-scale diffuse degassing of mantle-derived CO2 at the surface that occurs in the form of CO2-rich mineral springs and wet and dry mofettes. So far, the influence of CO2 degassing onto the microbial communities has been studied for soil environments, but not for aquatic systems. We hypothesized, that deep-trenching CO2 conduits interconnect the subsurface with the surface. This admixture of deep thermal fluids should be reflected in geochemical parameters and in the microbial community compositions. In the present study four mineral water springs and two wet mofettes were investigated through an interdisciplinary survey. The waters were acidic and differed in terms of organic carbon and anion/cation concentrations. Element geochemical and isotope analyses of fluid components were used to verify the origin of the fluids. Prokaryotic communities were characterized through quantitative PCR and Illumina 16S rRNA gene sequencing. Putative chemolithotrophic, anaerobic and microaerophilic organisms connected to sulfur (e.g., Sulfuricurvum, Sulfurimonas) and iron (e.g., Gallionella, Sideroxydans) cycling shaped the core community. Additionally, CO2-influenced waters form an ecosystem containing many taxa that are usually found in marine or terrestrial subsurface ecosystems. Multivariate statistics highlighted the influence of environmental parameters such as pH, Fe2+ concentration and conductivity on species distribution. The hydrochemical and microbiological survey introduces a new perspective on mofettes. Our results support that mofettes are either analogs or rather windows into the deep biosphere and furthermore enable access to deeply buried paleo-sediments. PMID:29321765

Assessing the Internal Consistency of the Marine Carbon Dioxide System at High Latitudes: The Labrador Sea AR7W Line Study Case

NASA Astrophysics Data System (ADS)

Raimondi, L.; Azetsu-Scott, K.; Wallace, D.

2016-02-01

This work assesses the internal consistency of ocean carbon dioxide through the comparison of discrete measurements and calculated values of four analytical parameters of the inorganic carbon system: Total Alkalinity (TA), Dissolved Inorganic Carbon (DIC), pH and Partial Pressure of CO2 (pCO2). The study is based on 486 seawater samples analyzed for TA, DIC and pH and 86 samples for pCO2 collected during the 2014 Cruise along the AR7W line in Labrador Sea. The internal consistency has been assessed using all combinations of input parameters and eight sets of thermodynamic constants (K1, K2) in calculating each parameter through the CO2SYS software. Residuals of each parameter have been calculated as the differences between measured and calculated values (reported as ΔTA, ΔDIC, ΔpH and ΔpCO2). Although differences between the selected sets of constants were observed, the largest were obtained using different pairs of input parameters. As expected the couple pH-pCO2 produced to poorest results, suggesting that measurements of either TA or DIC are needed to define the carbonate system accurately and precisely. To identify signature of organic alkalinity we isolated the residuals in the bloom area. Therefore only ΔTA from surface waters (0-30 m) along the Greenland side of the basin were selected. The residuals showed that no measured value was higher than calculations and therefore we could not observe presence of organic bases in the shallower water column. The internal consistency in characteristic water masses of Labrador Sea (Denmark Strait Overflow Water, North East Atlantic Deep Water, Newly-ventilated Labrador Sea Water, Greenland and Labrador Shelf waters) will also be discussed.

Space-time dynamics of carbon and environmental parameters related to carbon dioxide emissions in the Buor-Khaya Bay and adjacent part of the Laptev Sea

NASA Astrophysics Data System (ADS)

Semiletov, I. P.; Shakhova, N. E.; Pipko, I. I.; Pugach, S. P.; Charkin, A. N.; Dudarev, O. V.; Kosmach, D. A.; Nishino, S.

2013-09-01

This study aims to improve understanding of carbon cycling in the Buor-Khaya Bay (BKB) and adjacent part of the Laptev Sea by studying the inter-annual, seasonal, and meso-scale variability of carbon and related hydrological and biogeochemical parameters in the water, as well as factors controlling carbon dioxide (CO2) emission. Here we present data sets obtained on summer cruises and winter expeditions during 12 yr of investigation. Based on data analysis, we suggest that in the heterotrophic BKB area, input of terrestrially borne organic carbon (OC) varies seasonally and inter-annually and is largely determined by rates of coastal erosion and river discharge. Two different BKB sedimentation regimes were revealed: Type 1 (erosion accumulation) and Type 2 (accumulation). A Type 1 sedimentation regime occurs more often and is believed to be the quantitatively most important mechanism for suspended particular matter (SPM) and particulate organic carbon (POC) delivery to the BKB. The mean SPM concentration observed in the BKB under a Type 1 regime was one order of magnitude greater than the mean concentration of SPM (~ 20 mg L-1) observed along the Lena River stream in summer 2003. Loadings of the BKB water column with particulate material vary by more than a factor of two between the two regimes. Higher partial pressure of CO2 (pCO2), higher concentrations of nutrients, and lower levels of oxygen saturation were observed in the bottom water near the eroded coasts, implying that coastal erosion and subsequent oxidation of eroded organic matter (OM) rather than the Lena River serves as the predominant source of nutrients to the BKB. Atmospheric CO2 fluxes from the sea surface in the BKB vary from 1 to 95 mmol m-2 day-1 and are determined by specific features of hydrology and wind conditions, which change spatially, seasonally, and inter-annually. Mean values of CO2 emission from the shallow Laptev Sea were similar in September 1999 and 2005 (7.2 and 7.8 mmol m-2 day-1, respectively), while the CO2 efflux can be one order lower after a strong storm such as in September 2011. Atmospheric CO2 emissions from a thawed coastal ice complex in the BKB area varied from 9 to 439 mmol m-2 day-1, with the mean value ranged from 75.7 to 101 mmol m-2 day-1 in two years (September 2006 and 2009), suggesting that at the time of observations the eroded coastal area served as a more significant source of CO2 to the atmosphere than the tundra (mean value: 22.7 mmol m-2 day-1) on the neighboring Primorsky coastal plain (September 2006). The observed increase in the Lena River discharge since the 1990s suggests that increased levels of "satellite-derived" annual primary production could be explained by an increasing load of humic acids delivered to shelf water; in this water the color resulting from the presence of CDOM (colored dissolved organic matter) mimics the color resulting from the presence of Chl a when seen from space. Because the BKB area can be employed as an integrator of ongoing changes in the surrounding environment, we suggest that under ongoing changes, more nutrients, products of eroded OC transformation and river transport, will be delivered to the Arctic Ocean with its shrinking ice cover, potentially increasing primary production outside of the shallow East Siberian Arctic Shelf (ESAS). At the same time, because the ESAS is characterized by very low transparency which limits euphotic layer thickness, excessive pCO2 will not be utilized by photosynthesis but will rather be emitted to the atmosphere at increasing rates, affecting regional CO2 balance.

Geoelectrical image of the subsurface for CO2 geological storage in the Changhua site, Taiwan

NASA Astrophysics Data System (ADS)

Chiang, C. W.; Chiao, C. H.; Yang, M. W.; Yu, C. W.; Yang, C. H.; Chen, C. C.

2016-12-01

Global warming has recently become an important worldwide issue. Reduction of carbon dioxide (CO2) emission is recommended by Intergovernmental Panel on Climate Change, which geological storage is one of possible way to reduce the CO2 issue. The Taichung Power Plant is a coal-fired power plant operated by the Taiwan Power Company in Taichung, Taiwan, which is the largest coal-fired power station in the world. The power plant emits approximately 40 million tons annually which is also the world's largest CO2 emitter. Geophysical techniques are presented as the most useful tool to characterize the reservoir. The electrical resistivity tool was carried out applying audio-magnetotelluric (AMT) method, which could provide the depth resolution for evaluating the subsurface. A first survey of 20 AMT soundings was acquired to study the viability of the method to characterize the subsurface. Stations were deployed at approximately 500 m intervals and the data were recorded in the frequency range of 104-100 Hz. The dimensionality analysis proved the validity of the 1-D or 2-D assumption. The visualized model shows a layered electrical resistivity structure from shallow to depth of 3000 m. The preliminary result corresponds to seismic reflection and geological investigations that suggests a simple geological structure without complex geological processes in the area. It could be a suitable site for geological storage.

RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) biodegradation in aquifer sediments under manganese-reducing conditions

USGS Publications Warehouse

Bradley, Paul M.; Dinicola, Richard S.

2005-01-01

A shallow, RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine)–contaminated aquifer at Naval Submarine Base Bangor has been characterized as predominantly manganese-reducing, anoxic with local pockets of oxic conditions. The potential contribution of microbial RDX degradation to localized decreases observed in aquifer RDX concentrations was assessed in sediment microcosms amended with [U-14C] RDX. Greater than 85% mineralization of 14C-RDX to 14CO2 was observed in aquifer sediment microcosms under native, manganese-reducing, anoxic conditions. Significant increases in the mineralization of 14C-RDX to 14CO2 were observed in anoxic microcosms under NO3-amended or Mn(IV)-amended conditions. No evidence of 14C-RDX biodegradation was observed under oxic conditions. These results indicate that microbial degradation of RDX may contribute to natural attenuation of RDX in manganese-reducing aquifer systems.

RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) biodegradation in aquifer sediments under manganese-reducing conditions

USGS Publications Warehouse

Bradley, Paul M.; Dinicola, Richard S.

2005-01-01

A shallow, RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine)–contaminated aquifer at Naval Submarine Base Bangor has been characterized as predominantly manganese-reducing, anoxic with local pockets of oxic conditions. The potential contribution of microbial RDX degradation to localized decreases observed in aquifer RDX concentrations was assessed in sediment microcosms amended with [U-14C] RDX. Greater than 85% mineralization of14C-RDX to 14CO2 was observed in aquifer sediment microcosms under native, manganese-reducing, anoxic conditions. Significant increases in the mineralization of 14C-RDX to 14CO2 were observed in anoxic microcosms under NO3-amended or Mn(IV)-amended conditions. No evidence of 14C-RDX biodegradation was observed under oxic conditions. These results indicate that microbial degradation of RDX may contribute to natural attenuation of RDX in manganese-reducing aquifer systems.

Natural acidification changes the timing and rate of succession, alters community structure, and increases homogeneity in marine biofouling communities.

PubMed

Brown, Norah E M; Milazzo, Marco; Rastrick, Samuel P S; Hall-Spencer, Jason M; Therriault, Thomas W; Harley, Christopher D G

2018-01-01

Ocean acidification may have far-reaching consequences for marine community and ecosystem dynamics, but its full impacts remain poorly understood due to the difficulty of manipulating pCO 2 at the ecosystem level to mimic realistic fluctuations that occur on a number of different timescales. It is especially unclear how quickly communities at various stages of development respond to intermediate-scale pCO 2 change and, if high pCO 2 is relieved mid-succession, whether past acidification effects persist, are reversed by alleviation of pCO 2 stress, or are worsened by departures from prior high pCO 2 conditions to which organisms had acclimatized. Here, we used reciprocal transplant experiments along a shallow water volcanic pCO 2 gradient to assess the importance of the timing and duration of high pCO 2 exposure (i.e., discrete events at different stages of successional development vs. continuous exposure) on patterns of colonization and succession in a benthic fouling community. We show that succession at the acidified site was initially delayed (less community change by 8 weeks) but then caught up over the next 4 weeks. These changes in succession led to homogenization of communities maintained in or transplanted to acidified conditions, and altered community structure in ways that reflected both short- and longer-term acidification history. These community shifts are likely a result of interspecific variability in response to increased pCO 2 and changes in species interactions. High pCO 2 altered biofilm development, allowing serpulids to do best at the acidified site by the end of the experiment, although early (pretransplant) negative effects of pCO 2 on recruitment of these worms were still detectable. The ascidians Diplosoma sp. and Botryllus sp. settled later and were more tolerant to acidification. Overall, transient and persistent acidification-driven changes in the biofouling community, via both past and more recent exposure, could have important implications for ecosystem function and food web dynamics. © 2017 John Wiley & Sons Ltd.

Modelling the effects of ice-sheet activity on CO2 outgassing by Icelandic volcanoes

NASA Astrophysics Data System (ADS)

Armitage, J. J.; Ferguson, D.; Petersen, K. D.; Creyts, T. T.

2017-12-01

Glacial cycles may play a significant role in mediating the flux of magmatic CO2 between the Earth's mantle and atmosphere. In Iceland, it is thought that late-Pleistocene deglaciation led to a significant volcanic pulse, evidenced by increased post-glacial lava volumes and changes in melt chemistry consistent with depressurization. Investigating the extent to which glacial activity may have affected volcanic CO2 emissions from Iceland, and crucially over what timescale, requires detailed knowledge of how the magma system responded to the growth and collapse of the ice-sheet before and after the LGM. To investigate this, we coupled a model of magma generation and transport with a history of ice-sheet activity. Our results show that the emplacement and removal of the LGM ice-sheet likely led to two significant pulses of magmatic CO2. The first, and most significant of these, is associated with ice-sheet growth and occurs as the magma system recovers from glacial loading. This recovery happens from the base of the melting region upwards, producing a pulse of CO2 rich magma that is predicted to reach the surface around 20 ka after the loading event, close in time to the LGM. The second peak in CO2 output occurs abruptly following deglaciation as a consequence of increased rates of melt generation and transport in the shallow mantle. Although these post-glacial melts are relatively depleted in CO2, the increase in magma flux leads to a short-lived period of elevated CO2 emissions. Our results therefore suggest a negative feedback, whereby ice-sheet growth produces a delayed pulse of magmatic CO2, which, in addition to increased geothermal heat flux, may contribute towards driving deglaciation, which itself then causes further magmatism and CO2 outgassing. This model is consistent with the seismic structure of the asthenosphere below Iceland, and the established compositional and volumetric trends for sub- and post-glacial volcanism in Iceland. These trends show that the earliest subglacial events involved small volumes of enriched melts, while eruptions that were synchronous with or immediately followed deglaciation involved larger volumes of more depleted melts.

Injection and Monitoring at the Wallula Basalt Pilot Project

DOE PAGES

McGrail, B. Peter; Spane, Frank A.; Amonette, James E.; ...

2014-01-01

Continental flood basalts represent one of the largest geologic structures on earth but have received comparatively little attention for geologic storage of CO2. Flood basalt lava flows have flow tops that are porous, permeable, and have large potential capacity for storage of CO2. In appropriate geologic settings, interbedded sediment layers and dense low-permeability basalt rock flow interior sections may act as effective seals allowing time for mineralization reactions to occur. Previous laboratory experiments showed the relatively rapid chemical reaction of CO2-saturated pore water with basalts to form stable carbonate minerals. However, recent laboratory tests with water-saturated supercritical CO2 show thatmore » mineralization reactions occur in this phase as well, providing a second and potentially more important mineralization pathway than was previously understood. Field testing of these concepts is proceeding with drilling of the world’s first supercritical CO2 injection well in flood basalt being completed in May 2009 near the township of Wallula in Washington State and corresponding CO2 injection permit granted by the State of Washington in March 2011. Injection of a nominal 1000 MT of CO2 was completed in August 2013 and site monitoring is in progress. Well logging conducted immediately after injection termination confirmed the presence of CO2 predominantly within the upper flow top region, and showed no evidence of vertical CO2 migration outside the well casing. Shallow soil gas samples collected around the injection well show no evidence of leakage and fluid and gas samples collected from the injection zone show strongly elevated concentrations of Ca, Mg, Mn, and Fe and 13C/18O isotopic shifts that are consistent with basalt-water chemical reactions. If proven viable by this field test and others that are in progress or being planned, major flood basalts in the U.S., India, and perhaps Australia would provide significant additional CO2 storage capacity and additional geologic sequestration options in regions of these countries where conventional storage options are limited.« less

Long-term effects of conventional and reduced tillage systems on soil condition and yield of maize

NASA Astrophysics Data System (ADS)

Rátonyi, Tamás; Széles, Adrienn; Harsányi, Endre

2015-04-01

As a consequence of operations which neglect soil condition and consist of frequent soil disturbance, conventional tillage (primary tillage with autumn ploughing) results in the degradation and compaction of soil structure, as well as the reduction of organic matter. These unfavourable processes pose an increasing economic and environmental protection problem today. The unfavourable physical condition of soils on which conventional tillage was performed indicate the need for preserving methods and tools. The examinations were performed in the multifactorial long-term tillage experiment established at the Látókép experiment site of DE MÉK. The experiment site is located in the Hajdúság loess ridge (Hungary) and its soil is loess-based calcareous chernozem with deep humus layer. The physical soil type is mid-heavy adobe. The long-term experiment has a split-split plot design. The main plots are different tillage methods (autumn ploughing, spring shallow tillage) without replication. In this paper, the effect of conventional and reduced (shallow) tillage methods on soil conditions and maize yield was examined. A manual penetrometer was used to determine the physical condition and compactedness of the soil. The soil moisture content was determined with deep probe measurement (based on capacitive method). In addition to soil analyses, the yield per hectare of different plots was also observed. In reduced tillage, one compacted layer is shown in the soil resistance profile determined with a penetrometer, while there are two compacted layers in autumn ploughing. The highest resistance was measured in the case of primary tillage performed at the same depth for several years in the compacted (pan disk) layer developed under the developed layer in both treatments. The unfavourable impact of spring shallow primary tillage on physical soil conditions is shown by the fact that the compaction of the pan disk exceed the critical limit value of 3 MPa. Over the years, further deterioration of physical conditions were observed below the regularly cultivated layer. In shallow tillage, soil contained more moisture (at 40-50 cm deep and below) than in the ploughed treatment. There are multiple reasons for this phenomenon. This tillage method is moisture preserving as the depth of disturbance (15 cm) is lower than in ploughed treatments (25-30 cm). Soil surface is covered by stem residues after sowing, which may reduce the extent of evaporation. The soil surface CO2 emission was determined based on primary tillage depth, intensity and the period which passed since primary tillage. Spring shallow primary tillage resulted in higher CO2 emission than conventional tillage. The average maize yield was significantly higher in the autumn ploughing treatment (6,6-13,9 t/ha) in the first half (7 years) of the examined period (2000-2014). Higher average yields were observed in two years in the spring shallow tillage treatment and no significant yield difference was observed between tillage treatments in other examined years. Reduced (shallow) tillage increases the risk of near-surface soil compaction and the biological activity of the soil, while it reduces the moisture loss of the soil. Reducing tillage intensity does not necessarily reduce the average yield of the produced crop (maize).

Controlling mechanisms of surface partial pressure of CO2 in Jiaozhou Bay during summer and the influence of heavy rain

NASA Astrophysics Data System (ADS)

Li, Yunxiao; Yang, Xufeng; Han, Ping; Xue, Liang; Zhang, Longjun

2017-09-01

Due to the combined effects of natural processes and human activities, carbon source/sink processes and mechanisms in the coastal ocean are becoming more and more important in current ocean carbon cycle research. Based on differences in the ratio of total alkalinity (TA) to dissolved inorganic carbon (DIC) associated with terrestrial input, biological process (production and respiration), calcium carbonate (CaCO3) process (precipitation and dissolution) and CO2 evasion/invasion, we discuss the mechanisms controlling the surface partial pressure of CO2 (pCO2) in Jiaozhou Bay (JZB) during summer and the influence of heavy rain, via three cruises performed in mid-June, early July and late July of 2014. In mid-June and in early July, without heavy rain or obvious river input, sea surface pCO2 ranged from 521 to 1080 μatm and from 547 to 998 μatm, respectively. The direct input of DIC from sewage and the intense respiration produced large DIC additions and the highest pCO2 values in the northeast of the bay near the downtown of Qingdao. However, in the west of the bay, significant CaCO3 precipitation led to DIC removal but no obvious increase in pCO2, which was just close to that in the central area. Due to the shallow depth and longer water residence time in this region, this pattern may be related to the sustained release of CO2 into the atmosphere. In late July, heavy rain promoted river input in the western and eastern portions of JZB. Strong primary production led to a significant decrease in pCO2 in the western area, with the lowest pCO2 value of 252 μatm. However, in the northeastern area, the intense respiration remained, and the highest pCO2 value was 1149 μatm. The average air-sea CO2 flux in mid-June and early July was 20.23 mmol m- 2 d- 1 and 23.56 mmol m- 2 d- 1, respectively. In contrast, in late July, sources became sinks for atmospheric CO2 in the western and central areas of the bay, halving the average air-sea CO2 flux to a value of 10.58 mmol m- 2 d- 1. Therefore, without considering the impact of heavy rains, the estimated air-sea CO2 flux is likely inaccurate in coastal waters. Our study implies that more studies in the coastal ocean are needed to determine the duration and intensity of the CO2 sink after the occurrence of heavy rain as well as the magnitudes of the CO2 sink associated with varying rainfall intensities.

Reactive Transport Analysis of Fault 'Self-sealing' Associated with CO2 Storage

NASA Astrophysics Data System (ADS)

Patil, V.; McPherson, B. J. O. L.; Priewisch, A.; Franz, R. J.

2014-12-01

We present an extensive hydrologic and reactive transport analysis of the Little Grand Wash fault zone (LGWF), a natural analog of fault-associated leakage from an engineered CO2 repository. Injecting anthropogenic CO2 into the subsurface is suggested for climate change mitigation. However, leakage of CO2 from its target storage formation into unintended areas is considered as a major risk involved in CO2 sequestration. In the event of leakage, permeability in leakage pathways like faults may get sealed (reduced) due to precipitation or enhanced (increased) due to dissolution reactions induced by CO2-enriched water, thus influencing migration and fate of the CO2. We hypothesize that faults which act as leakage pathways can seal over time in presence of CO2-enriched waters. An example of such a fault 'self-sealing' is found in the LGWF near Green River, Utah in the Paradox basin, where fault outcrop shows surface and sub-surface fractures filled with calcium carbonate (CaCO3). The LGWF cuts through multiple reservoirs and seal layers piercing a reservoir of naturally occurring CO2, allowing it to leak into overlying aquifers. As the CO2-charged water from shallower aquifers migrates towards atmosphere, a decrease in pCO2 leads to supersaturation of water with respect to CaCO3, which precipitates in the fractures of the fault damage zone. In order to test the nature, extent and time-frame of the fault sealing, we developed reactive flow simulations of the LGWF. Model parameters were chosen based on hydrologic measurements from literature. Model geochemistry was constrained by water analysis of the adjacent Crystal Geyser and observations from a scientific drilling test conducted at the site. Precipitation of calcite in the top portion of the fault model led to a decrease in the porosity value of the damage zone, while clay precipitation led to a decrease in the porosity value of the fault core. We found that the results were sensitive to the fault architecture, relative permeability functions, kinetic parameters for mineral reactions and treatment of molecular diffusion. Major conclusions from this analysis are that a failed (leaking) engineered sequestration site may behave very similar to the LGWF and that under similar conditions some faults are likely to seal over time.

Unraveling the dynamics of magmatic CO2 degassing at Mammoth Mountain, California

USGS Publications Warehouse

Pfeiffer, Loic; Wanner, Christoph; Lewicki, Jennifer L.

2018-01-01

The accumulation of magmatic CO2 beneath low-permeability barriers may lead to the formation of CO2-rich gas reservoirs within volcanic systems. Such accumulation is often evidenced by high surface CO2 emissions that fluctuate over time. The temporal variability in surface degassing is believed in part to reflect a complex interplay between deep magmatic degassing and the permeability of degassing pathways. A better understanding of the dynamics of CO2 degassing is required to improve monitoring and hazards mitigation in these systems. Owing to the availability of long-term records of CO2 emissions rates and seismicity, Mammoth Mountain in California constitutes an ideal site towards such predictive understanding. Mammoth Mountain is characterized by intense soil CO2 degassing (up to ∼1000 t d−1) and tree kill areas that resulted from leakage of CO2 from a CO2-rich gas reservoir located in the upper ∼4 km. The release of CO2-rich fluids from deeper basaltic intrusions towards the reservoir induces seismicity and potentially reactivates faults connecting the reservoir to the surface. While this conceptual model is well-accepted, there is still a debate whether temporally variable surface CO2 fluxes directly reflect degassing of intrusions or variations in fault permeability. Here, we report the first large-scale numerical model of fluid and heat transport for Mammoth Mountain. We discuss processes (i) leading to the initial formation of the CO2-rich gas reservoir prior to the occurrence of high surface CO2 degassing rates and (ii) controlling current CO2 degassing at the surface. Although the modeling settings are site-specific, the key mechanisms discussed in this study are likely at play at other volcanic systems hosting CO2-rich gas reservoirs. In particular, our model results illustrate the role of convection in stripping a CO2-rich gas phase from a rising hydrothermal fluid and leading to an accumulation of a large mass of CO2 (∼107–108 t) in a shallow gas reservoir. Moreover, we show that both, short-lived (months to years) and long-lived (hundreds of years) events of magmatic fluid injection can lead to critical pressures within the reservoir and potentially trigger fault reactivation. Our sensitivity analysis suggests that observed temporal fluctuations in surface degassing are only indirectly controlled by variations in magmatic degassing and are mainly the result of temporally variable fault permeability. Finally, we suggest that long-term CO2 emission monitoring, seismic tomography and coupled thermal–hydraulic–mechanical modeling are important for CO2-related hazard mitigation.

Magmatic carbon dioxide emissions at Mammoth Mountain, California

USGS Publications Warehouse

Farrar, Christopher D.; Neil, John M.; Howle, James F.

1999-01-01

Carbon dioxide (CO2) of magmatic origin is seeping out of the ground in unusual quantities at several locations around the flanks of Mammoth Mountain, a dormant volcano in Eastern California. The most recent volcanic activity on Mammoth Mountain was steam eruptions about 600 years ago, but seismic swarms and long-period earthquakes over the past decade are evidence of an active magmatic system at depth. The CO2 emission probably began in 1990 but was not recognized until 1994. Seismic swarms and minor ground deformation during 1989, believed to be results of a shallow intrusion of magma beneath Mammoth Mountain, probably triggered the release of CO2, which persists in 1998. The CO2 gas is at ambient temperatures and emanates diffusely from the soil surface rather than flowing from distinct vents. The CO2 has collected in the soil by displacing air in the pore spaces and reaches concentrations of greater than 95 percent by volume in places. The total area affected by high CO2 concentrations and high CO2 flux from the soil surface was estimated at 60 hectares in 1997. Coniferous forest covering about 40 hectares has been killed by high CO2 concentrations in the root zone. In more than 300 soil-gas samples collected from depths of 0.5 to 2 m in 1995, CO2 concentrations ranged from background levels (less than 1 percent) to greater than 95 percent by volume. At 250 locations, CO2 flux was measured using a closed chamber in 1996; values, in grams per square meter per day, ranged from background (less than 25) to more than 30,000. On the basis of these data, the total emission of magmatic CO2 in 1996 is estimated to be about 530 megagrams per day. Concentrations of CO2 exceeding Occupational Safety and Health Administration standards have been measured in pits dug in soil and snow, in poorly ventilated buildings, and in below-ground valve-boxes around Mammoth Mountain. CO2 concentrations greater than 10 percent in poorly ventilated spaces are not uncommon on some parts of Mammoth Mountain. Humans and other animals exposed to CO2 concentrations greater than 10 percent could lose consciousness and die rapidly. With knowledge of the problem and reasonable caution, however, the health hazard to humans can be avoided. As noted earlier, the CO2 emission is related to magmatic activity at depth, but at present (1998) it does not portend an imminent volcanic eruption.

Greenhouse gas emissions from waste stabilisation ponds in Western Australia and Quebec (Canada).

PubMed

Glaz, Patricia; Bartosiewicz, Maciej; Laurion, Isabelle; Reichwaldt, Elke S; Maranger, Roxane; Ghadouani, Anas

2016-09-15

Waste stabilisation ponds (WSPs) are highly enriched environments that may emit large quantities of greenhouse gases (GHG), including CO2, CH4 and N2O. However, few studies provide detailed reports on these emissions. In the present study, we investigated GHG emissions from WSPs in Western Australia and Quebec, Canada, and compared emissions to WSPs from other climatic regions and to other types of aquatic ecosystems. Surface water GHG concentrations were related to phytoplankton biomass and nutrients. The CO2 was either emitted or absorbed by WSPs, largely as a function of phytoplankton dynamics and strong stratification in these shallow systems, whereas efflux of CH4 and N2O to the atmosphere was always observed albeit with highly variable emission rates, dependent on treatment phase and time of the day. The total global warming potential index (GWP index, calculated as CO2 equivalent) of emitted GHG from WSPs in Western Australia averaged 12.8 mmol m(-2) d(-1) (median), with CO2, CH4 and N2O respectively contributing 0%, 96.7% and 3.3% of the total emissions, while in Quebec WSPs this index was 194 mmol m(-2) d(-1), with a relative contribution of 93.8, 3.0 and 3.2% respectively. The CO2 fluxes from WSPs were of the same order of magnitude as those reported in hydroelectric reservoirs and constructed wetlands in tropical climates, whereas CH4 fluxes were considerably higher compared to other aquatic ecosystems. N2O fluxes were in the same range of values reported for WSPs in subtropical climate. Copyright © 2016 Elsevier Ltd. All rights reserved.

First results from TN273 studies of the SE Mariana Forearc rift

NASA Astrophysics Data System (ADS)

Ribeiro, J. M.; Stern, R. J.; Kelley, K. A.; Shaw, A. M.; Shimizu, N.; Martinez, F.; Ishii, T.; Ishizuka, O.; Manton, W. I.

2012-12-01

TN 273 aboard R/V Thomas Thompson (Dec. 22 2011- Jan. 22 2012) studied an unusual region of rifting affecting the southern Mariana forearc S.W. of Guam. The S.E. Mariana Forearc Rift (SEMFR) formed by diffuse tectonic and volcanic deformation (Martinez and Sleeper, this meeting) ~2.7-3.7 Ma ago to accommodate opening of the southernmost Mariana Trough backarc basin. A total of 730 km linear-track of SEMFR seafloor was surveyed with deep-towed side-scan sonar IMI-30. 14 dredges provided samples of SEMFR igneous rocks, analyzed for whole rock (WR) and glass compositions. These new results coupled with results of earlier investigations confirm that SEMFR is dominated by Miocene lavas along with minor gabbro and diabase. SEMFR lavas range in major element composition from primitive basalt to fractionated andesite (Mg# = 0.36-0.73; SiO2 = 50-57 wt%), mainly controlled by crystal fractionation. Rare Earth Element (REE) patterns range from LREE-depleted, N-MORB-like to flat patterns, reflecting different mantle processes (i.e. different sources, degree of melting …). Glassy rinds and olivine-hosted melt inclusions in these lavas contain variable volatile compositions (F = 75-358 ppm, S = 35-1126 ppm, Cl= 74-1400 ppm, CO2 = 15-520 ppm, 0.36-2.36 wt% H2O). SEMFR lavas show spider diagrams with positive anomalies in LILE and negative anomalies in HSFE. SEMFR lavas have backarc basin-like (BAB-like) chemical composition (H2O < 2.5wt%, Ba/Yb~20, Nb/Yb~1 and ɛNd~9) along with stronger enrichment in Rb and Cs than arc and BAB lavas, as demonstrated by their higher Rb/Th and Cs/Ba ratios in WR and glasses, which may reflect the role of the ultra-shallow fluids. Ultra-shallow fluids are derived from the top of the subducting slab, beneath the forearc, where most of the water and the fluid-mobile elements (Rb, Cs, Ba,) are thought to be released (Schmidt and Poli, 1998, EPSL, Savov et al., 2005, G-3). Our results suggest that i) SEMFR lavas formed by metasomatism of a BAB mantle source by ultra-shallow fluids, likely released from subducted sediments and the altered oceanic crust; and ii) the ultra-shallow fluid is aqueous and is characterized by enrichment in Cs and Rb, suggesting that Cs and Rb are decoupled from Ba in ultra-shallow subduction processes.

Carbon Exchange and Loss Processes on Mars

NASA Image and Video Library

2015-11-24

This graphic depicts paths by which carbon has been exchanged between Martian interior, surface rocks, polar caps, waters and atmosphere, and also depicts a mechanism by which carbon is lost from the atmosphere with a strong effect on isotope ratio. Carbon dioxide (CO2) to generate the Martian atmosphere originated in the planet's mantle and has been released directly through volcanoes or trapped in rocks crystallized from magmas and released later. Once in the atmosphere, the CO2 can exchange with the polar caps, passing from gas to ice and back to gas again. The CO2 can also dissolve into waters, which can then precipitate out solid carbonates, either in lakes at the surface or in shallow aquifers. Carbon dioxide gas in the atmosphere is continually lost to space at a rate controlled in part by the sun's activity. One loss mechanism is called ultraviolet photodissociation. It occurs when ultraviolet radiation (indicated on the graphic as "hv") encounters a CO2 molecule, breaking the bonds to first form carbon monoxide (CO) molecules and then carbon (C) atoms. The ratio of carbon isotopes remaining in the atmosphere is affected as these carbon atoms are lost to space, because the lighter carbon-12 (12C) isotope is more easily removed than the heavier carbon-13 (13C) isotope. This fractionation, the preferential loss of carbon-12 to space, leaves a fingerprint: enrichment of the heavy carbon-13 isotope, measured in the atmosphere of Mars today. http://photojournal.jpl.nasa.gov/catalog/PIA20163

Application of multiple tracers (SF6 and chloride) to identify the transport by characteristics of contaminant at two separate contaminated sites

NASA Astrophysics Data System (ADS)

Lee, K. K.; Lee, S. S.; Kim, H. H.; Koh, E. H.; Kim, M. O.; Lee, K.; Kim, H. J.

2016-12-01

Multiple tracers were applied for source and pathway detection at two different sites. CO2 gas injected in the subsurface for a shallow-depth CO2 injection and leak test can be regarded as a potential contaminant source. Therefore, it is necessary to identify the migration pattern of CO2 gas. Also, at a DNAPL contaminated site, it is important to figure out the characteristics of plume evolution from the source zone. In this study, multiple tracers (SF6 and chloride) were used to evaluate the applicability of volatile and non-volatile tracers and to identify the characteristics of contaminant transport at each CO2 injection and leak test site and DNAPL contaminated site. Firstly, at the CO2 test site, multiple tracers were used to perform the single well push-drift-pull tracer test at total 3 specific depth zones. As results of tests, volatile and non-volatile tracers showed different mass recovery percentage. Most of chloride mass was recovered but less than half of SF6 mass was recovered due to volatile property. This means that only gaseous SF6 leak out to unsaturated zone. However, breakthrough curves of both tracers indicated similar peak time, effective porosity, and regional groundwater velocity. Also, at both contaminated sites, natural gradient tracer tests were performed with multiple tracers. With the results of natural gradient tracer test, it was possible to confirm the applicability of multiple tracers and to understand the contaminant transport in highly heterogeneous aquifer systems through the long-term monitoring of tracers. Acknowledgement: financial support was provided by the R&D Project on Environmental Management of Geologic CO2 Storage)" from the KEITI (Project Number: 2014001810003) and Korea Ministry of Environment as "The GAIA project (2014000540010)".

Targeted Pressure Management During CO 2 Sequestration: Optimization of Well Placement and Brine Extraction

DOE PAGES

Cihan, Abdullah; Birkholzer, Jens; Bianchi, Marco

2014-12-31

Large-scale pressure increases resulting from carbon dioxide (CO 2) injection in the subsurface can potentially impact caprock integrity, induce reactivation of critically stressed faults, and drive CO 2 or brine through conductive features into shallow groundwater. Pressure management involving the extraction of native fluids from storage formations can be used to minimize pressure increases while maximizing CO2 storage. However, brine extraction requires pumping, transportation, possibly treatment, and disposal of substantial volumes of extracted brackish or saline water, all of which can be technically challenging and expensive. This paper describes a constrained differential evolution (CDE) algorithm for optimal well placement andmore » injection/ extraction control with the goal of minimizing brine extraction while achieving predefined pressure contraints. The CDE methodology was tested for a simple optimization problem whose solution can be partially obtained with a gradient-based optimization methodology. The CDE successfully estimated the true global optimum for both extraction well location and extraction rate, needed for the test problem. A more complex example application of the developed strategy was also presented for a hypothetical CO 2 storage scenario in a heterogeneous reservoir consisting of a critically stressed fault nearby an injection zone. Through the CDE optimization algorithm coupled to a numerical vertically-averaged reservoir model, we successfully estimated optimal rates and locations for CO 2 injection and brine extraction wells while simultaneously satisfying multiple pressure buildup constraints to avoid fault activation and caprock fracturing. The study shows that the CDE methodology is a very promising tool to solve also other optimization problems related to GCS, such as reducing ‘Area of Review’, monitoring design, reducing risk of leakage and increasing storage capacity and trapping.« less

Carbon isotope composition of CO2-rich inclusions in cumulate-forming mantle minerals from Stromboli volcano (Italy)

NASA Astrophysics Data System (ADS)

Gennaro, Mimma Emanuela; Grassa, Fausto; Martelli, Mauro; Renzulli, Alberto; Rizzo, Andrea Luca

2017-10-01

We report on measurements of concentration and carbon isotope composition (δ13CCO2) of CO2 trapped in fluid inclusions of olivine and clinopyroxene crystals separated from San Bartolo ultramafic cumulate Xenoliths (SBX) formed at mantle depth (i.e., beneath a shallow Moho supposed to be at 14.8 km). These cumulates, erupted about 2 ka ago at Stromboli volcano (Italy), have been already investigated by Martelli et al. (2014) mainly for Sr-Nd isotopes and for their noble gases geochemistry. The concentration of CO2 varies of one order of magnitude from 3.8·10- 8 mol g- 1 to 4.8·10- 7 mol g- 1, with δ13C values between - 2.8‰ and - 1.5‰ vs V-PDB. These values overlap the range of measurements performed in the crater gases emitted at Stromboli (- 2.5‰ < δ13CCO2 < - 1.0‰). Since SBX formed from relatively primitive mantle-derived basic magmas, we argue that the isotope composition displayed by fluid inclusions and surface gases can be considered representative of the magma volatile imprinting released by partial melting of the mantle source beneath Stromboli (- 2.8‰ < δ13C < - 1.0‰). In addition, the δ13C signature of CO2 is not significantly modified by fractionation due to magmatic degassing or intracrustal contamination processes owing to magma ascent and residence within the volcano plumbing system. Such δ13C values are higher than those commonly reported for MORB-like upper mantle (- 8 ÷ - 4‰) and likely reflect the source contamination of the local mantle wedge by CO2 coming from the decarbonation of the sediments carried by the subducting Ionian slab with a contribution of organic carbon up to 7%.

Sixty thousand years of magmatic volatile history before the caldera-forming eruption of Mount Mazama, Crater Lake, Oregon

USGS Publications Warehouse

Wright, Heather M.; Bacon, Charles R.; Vazquez, Jorge A.; Sisson, Thomas W.

2012-01-01

The well-documented eruptive history of Mount Mazama, Oregon, provides an excellent opportunity to use pre-eruptive volatile concentrations to study the growth of an explosive silicic magmatic system. Melt inclusions (MI) hosted in pyroxene and plagioclase crystals from eight dacitic–rhyodacitic eruptive deposits (71–7.7 ka) were analyzed to determine variations in volatile-element concentrations and changes in magma storage conditions leading up to and including the climactic eruption of Crater Lake caldera. Temperatures (Fe–Ti oxides) increased through the series of dacites, then decreased, and increased again through the rhyodacites (918–968 to ~950 to 845–895 °C). Oxygen fugacity began at nickel–nickel-oxide buffer (NNO) +0.8 (71 ka), dropped slightly to NNO +0.3, and then climbed to its highest value with the climactic eruption (7.7 ka) at NNO +1.1 log units. In parallel with oxidation state, maximum MI sulfur concentrations were high early in the eruptive sequence (~500 ppm), decreased (to ~200 ppm), and then increased again with the climactic eruption (~500 ppm). Maximum MI sulfur correlates with the Sr content (as a proxy for LREE, Ba, Rb, P2O5) of recharge magmas, represented by basaltic andesitic to andesitic enclaves and similar-aged lavas. These results suggest that oxidized Sr-rich recharge magmas dominated early and late in the development of the pre-climactic dacite–rhyodacite system. Dissolved H2O concentrations in MI do not, however, correlate with these changes in dominant recharge magma, instead recording vapor solubility relations in the developing shallow magma storage and conduit region. Dissolved H2O concentrations form two populations through time: the first at 3–4.6 wt% (with a few extreme values up to 6.1 wt%) and the second at ≤2.4 wt%. CO2 concentrations measured in a subset of these inclusions reach up to 240 ppm in early-erupted deposits (71 ka) and are below detection in climactic deposits (7.7 ka). Combined H2O and CO2 concentrations and solubility models indicate a dominant storage region at 4–7 km (up to 12 km), with drier inclusions that diffusively re-equilibrated and/or were trapped at shallower depths. Boron and Cl (except in the climactic deposit) largely remained in the melt, suggesting vapor–melt partition coefficients and gas fractions were low. Modeled Li, F, and S vapor–melt partition coefficients are higher than those of B and Cl. The decrease in maximum MI CO2 concentration following the earliest dacitic eruptions is interpreted to result from a broadening of the shallow storage region to greater than the diameter of subjacent feeders, so that greater proportions of reservoir magma were to the side of CO2-bearing vapor bubbles ascending vertically from the locus of recharge magma injection, thereby escaping recarbonation by streaming vapor bubbles. The Mazama melt inclusions provide a picture of a growing magma storage region, where chemical variations in melt and magma occur due to changes in the nature and supply rate of magma recharge, the timing of degassing, and the possible degree of equilibration with gases from below.

The parsec-scale relationship between ICO and AV in local molecular clouds

NASA Astrophysics Data System (ADS)

Lee, Cheoljong; Leroy, Adam K.; Bolatto, Alberto D.; Glover, Simon C. O.; Indebetouw, Remy; Sandstrom, Karin; Schruba, Andreas

2018-03-01

We measure the parsec-scale relationship between integrated CO intensity (ICO) and visual extinction (AV) in 24 local molecular clouds using maps of CO emission and dust optical depth from Planck. This relationship informs our understanding of CO emission across environments, but clean Milky Way measurements remain scarce. We find uniform ICO for a given AV, with the results bracketed by previous studies of the Pipe and Perseus clouds. Our measured ICO-AV relation broadly agrees with the standard Galactic CO-to-H2 conversion factor, the relation found for the Magellanic clouds at coarser resolution, and numerical simulations by Glover & Clark (2016). This supports the idea that CO emission primarily depends on shielding, which protects molecules from dissociating radiation. Evidence for CO saturation at high AV and a threshold for CO emission at low AV varies remains uncertain due to insufficient resolution and ambiguities in background subtraction. Resolution of order 0.1 pc may be required to measure these features. We use this ICO-AV relation to predict how the CO-to-H2 conversion factor (XCO) would change if the Solar Neighbourhood clouds had different dust-to-gas ratio (metallicity). The calculations highlight the need for improved observations of the CO emission threshold and H I shielding layer depth. They are also sensitive to the shape of the column density distribution. Because local clouds collectively show a self-similar distribution, we predict a shallow metallicity dependence for XCO down to a few tenths of solar metallicity. However, our calculations also imply dramatic variations in cloud-to-cloud XCO at subsolar metallicity.

Community metabolism in shallow coral reef and seagrass ecosystems, lower Florida Keys

USGS Publications Warehouse

Turk, Daniela; Yates, Kimberly K.; Vega-Rodriguez, Maria; Toro-Farmer, Gerardo; L'Esperance, Chris; Melo, Nelson; Ramsewak, Deanesch; Estrada, S. Cerdeira; Muller-Karger, Frank E.; Herwitz, Stan R.; McGillis, Wade

2016-01-01

Diurnal variation of net community production (NEP) and net community calcification (NEC) were measured in coral reef and seagrass biomes during October 2012 in the lower Florida Keys using a mesocosm enclosure and the oxygen gradient flux technique. Seagrass and coral reef sites showed diurnal variations of NEP and NEC, with positive values at near-seafloor light levels >100–300 µEinstein m-2 s-1. During daylight hours, we detected an average NEP of 12.3 and 8.6 mmol O2 m-2 h-1 at the seagrass and coral reef site, respectively. At night, NEP at the seagrass site was relatively constant, while on the coral reef, net respiration was highest immediately after dusk and decreased during the rest of the night. At the seagrass site, NEC values ranged from 0.20 g CaCO3 m-2 h-1 during daylight to -0.15 g CaCO3 m-2 h-1 at night, and from 0.17 to -0.10 g CaCO3 m-2 h-1 at the coral reef site. There were no significant differences in pH and aragonite saturation states (Ωar) between the seagrass and coral reef sites. Decrease in light levels during thunderstorms significantly decreased NEP, transforming the system from net autotrophic to net heterotrophic.

Shallow tillage generates higher N2O emissions: results of continuous chamber-based measurement in a winter wheat field.

NASA Astrophysics Data System (ADS)

Broux, François; Lognoul, Margaux; Theodorakopoulos, Nicolas; Hiel, Marie-Pierre; Bodson, Bernard; Heinesch, Bernard; Aubinet, Marc

2017-04-01

Agriculture is one of the most important contributors to GHG emission, notably through fertilized croplands. Though, few publications have studied simultaneously and through continuous measurement the N2O and CO2 emissions in cultivated lands. We conducted this study to assess the effect of farming practices and climate on both N2O and CO2 emissions from a winter wheat crop. The experiment was held in an experimental field in the loamy region in Belgium from March 2016 till crop harvest in August 2016. The fluxes were measured on two nearby parcels in a winter wheat field with restitution of the residues from previous crop. For the past 8 years, one parcel was subjected to a shallow tillage (ST, 10 cm depth) and the other one to a conventional tillage (CT, 25 cm depth). On each parcel, the emissions are assessed with homemade automated closed chambers. Measurement continuity and good temporal resolution (one mean flux every 4 hours) of the system allowed a fine detection and quantification of the emission peaks which usually represent the major part of N2O fluxes. In addition to gas fluxes, soil water content and temperature were measured continuously. Soil samples were taken regularly to determine soil pH, soil organic carbon and nitrogen pools (total, NO3- and NH4+) and study microbial diversity and nitrification/denitrification gene expression. Unexpectedly, results showed N2O emissions twice as large in the ST parcel as in the CT parcel. On the contrary, less important CO2 emissions were observed under ST. Several emission peaks of N2O were observed during the measurement period. The peaks occurred after fertilization events and seemed to be triggered by an elevation of soil water content. Interesting links could be made between soil NH4-N and NO3-N pools and N2O emissions. Nitrification being the main process originating the fluxes was suggested on the one hand by the temporal evolution of nitrogen pools and N2O emissions and on the other hand by the relation between spatial variability of the emissions with the soil nitrate content. A comparison of the emissions between ST and CT and a discussion on peaks temporal dynamic, focusing on their intensity, duration and starting time will be presented.

Bubble Stripping as a Tool to Reduce High Dissolved CO2 in Coastal Marine Ecosystems

NASA Astrophysics Data System (ADS)

Koweek, D.; Mucciarone, D. A.; Dunbar, R. B.

2016-02-01

High dissolved CO2 concentrations in coastal ecosystems are a common occurrence due to a combination of large ecosystem metabolism and long residence times. Many of the socially, commercially, and recreationally important species may have adapted to this natural variability over time. However, eutrophication and ocean acidification may be perturbing the water chemistry beyond the bounds of tolerance for these organisms. We are currently limited in our ability to deal with the geochemical changes unfolding in our coastal ocean. This study helps to address this deficit of solutions by introducing bubble stripping as a novel geochemical engineering approach to reducing high CO2 in coastal marine ecosystems. We use an empirically validated numerical model to find that air/sea gas exchange rates within a bubbled system are 1-2 orders of magnitude higher than within a non-bubbled system. By coupling bubbling-enhanced ventilation to a coastal ecosystem metabolism model, we demonstrate that strategically timed bubble plumes can mitigate exposure to high CO2 under present-day conditions and that exposure mitigation is enhanced in the more acidic conditions predicted by the end of the century. The Fifth Assessment Report of the Intergovernmental Panel on Climate Change emphasizes the need to both adapt to and mitigate the effects of climate change and ocean acidification. We believe shallow water bubble stripping could be one approach for reducing high CO2 conditions in coastal ecosystems and should be added to the growing list of engineering approaches intended to increase coastal resilience in a changing ocean.

Co- and post-seismic shallow fault physics from near-field geodesy, seismic tomography, and mechanical modeling

NASA Astrophysics Data System (ADS)

Nevitt, J.; Brooks, B. A.; Catchings, R.; Goldman, M.; Criley, C.; Chan, J. H.; Glennie, C. L.; Ericksen, T. L.; Madugo, C. M.

2017-12-01

The physics governing near-surface fault slip and deformation are largely unknown, introducing significant uncertainty into seismic hazard models. Here we combine near-field measurements of surface deformation from the 2014 M6.0 South Napa earthquake with high-resolution seismic imaging and finite element models to investigate the effects of rupture speed, elastic heterogeneities, and plasticity on shallow faulting. We focus on two sites that experienced either predominantly co-seismic or post-seismic slip. We measured surface deformation with mobile laser scanning of deformed vine rows within 300 m of the fault at 1 week and 1 month after the event. Shear strain profiles for the co- and post-seismic sites are similar, with maxima of 0.012 and 0.013 and values exceeding 0.002 occurring within 26 m- and 18 m-wide zones, respectively. That the rupture remained buried at the two sites and produced similar deformation fields suggests that permanent deformation due to dynamic stresses did not differ significantly from the quasi-static case, which might be expected if the rupture decelerated as it approached the surface. Active-source seismic surveys, 120 m in length with 1 m geophone/shot spacing, reveal shallow compliant zones of reduced shear modulus. For the co- and post-seismic sites, the tomographic anomaly (Vp/Vs > 5) at 20 m depth has a width of 80 m and 50 m, respectively, much wider than the observed surface displacement fields. We investigate this discrepancy with a suite of finite element models in which a planar fault is buried 5 m below the surface. The model continuum is defined by either homogeneous or heterogeneous elastic properties, with or without Drucker-Prager plastic yielding, with properties derived from lab testing of similar near-surface materials. We find that plastic yielding can greatly narrow the surface displacement zone, but that the width of this zone is largely insensitive to changes in the elastic structure (i.e., the presence of a compliant zone).

Identifying sources, formation pathways and geological controls of methane in shallow groundwater above unconventional natural gas plays in Alberta, Canada

NASA Astrophysics Data System (ADS)

Mayer, B.; Humez, P.; Nightingale, M.; Ing, J.; Kingston, A. W.; Clarkson, C.; Cahill, A.; Parker, B. L.; Cherry, J. A.; Millot, R.; Kloppmann, W.; Osadetz, K.; Lawton, D.

2015-12-01

With the advent of shale gas development facilitated by hydraulic fracturing it has become increasingly important to develop tracer tools to scientifically determine potential impacts of stray gases on shallow aquifers. To assess potential future impacts on shallow aquifers by leakage of natural gas from unconventional energy resource development, it is essential to establish a reliable baseline. Occurrence of methane in shallow groundwater in Alberta (Canada) between 2006 and 2014 was assessed and was ubiquitous in 186 sampled monitoring wells. Free and dissolved gas sampling and measurement approaches yielded comparable results with often low methane concentrations in shallow groundwater, but in 28 samples methane exceeded 10 mg/L in dissolved gas and 300,000 ppmv in free gas. Methane concentrations in free and dissolved gas samples were found to increase with well depth and were especially elevated in groundwater obtained from aquifers containing coal seams and shale units. Carbon isotope ratios of methane averaged -69.7 ± 11.1 ‰ in free gas and -65.6 ± 8.9 ‰ in dissolved gas. δ13C values were not found to vary with well depth or lithology indicating that the methane in Alberta groundwater was formed via a similar mechanism. The low δ13C values in concert with average δ2H values of -289 ± 44 ‰ suggest that most methane was of biogenic origin predominantly generated via CO2 reduction. This interpretation is confirmed by gas dryness parameters typically >500 due to only small amounts of ethane and a lack of propane in most samples. Novel approaches of in-situ concentration and isotope measurements for methane during drilling of a 530 m deep well yielded a mud-gas profile characterizing natural gas occurrences in the intermediate zone. Comparison with mudgas profile carbon isotope data revealed that methane in the investigated shallow groundwater in Alberta is isotopically similar to hydrocarbon gases found in 100-250 meter depths in the Western Canadian Sedimentary Basin and is currently not sourced from thermogenic hydrocarbon occurrences in deeper portions of the basin. The assembled data set provides evidence that potential stray gas contamination by isotopically distinct deeper thermogenic gases from the intermediate or from production zones can be effectively detected by suitable monitoring programs.

Effect of Sampling Depth on Air-Sea CO2 Flux Estimates in River-Stratified Arctic Coastal Waters

NASA Astrophysics Data System (ADS)

Miller, L. A.; Papakyriakou, T. N.

2015-12-01

In summer-time Arctic coastal waters that are strongly influenced by river run-off, extreme stratification severely limits wind mixing, making it difficult to effectively sample the surface 'mixed layer', which can be as shallow as 1 m, from a ship. During two expeditions in southwestern Hudson Bay, off the Nelson, Hayes, and Churchill River estuaries, we confirmed that sampling depth has a strong impact on estimates of 'surface' pCO2 and calculated air-sea CO2 fluxes. We determined pCO2 in samples collected from 5 m, using a typical underway system on the ship's seawater supply; from the 'surface' rosette bottle, which was generally between 1 and 3 m; and using a niskin bottle deployed at 1 m and just below the surface from a small boat away from the ship. Our samples confirmed that the error in pCO2 derived from typical ship-board versus small-boat sampling at a single station could be nearly 90 μatm, leading to errors in the calculated air-sea CO2 flux of more than 0.1 mmol/(m2s). Attempting to extrapolate such fluxes over the 6,000,000 km2 area of the Arctic shelves would generate an error approaching a gigamol CO2/s. Averaging the station data over a cruise still resulted in an error of nearly 50% in the total flux estimate. Our results have implications not only for the design and execution of expedition-based sampling, but also for placement of in-situ sensors. Particularly in polar waters, sensors are usually deployed on moorings, well below the surface, to avoid damage and destruction from drifting ice. However, to obtain accurate information on air-sea fluxes in these areas, it is necessary to deploy sensors on ice-capable buoys that can position the sensors in true 'surface' waters.

Reduced order models for assessing CO 2 impacts in shallow unconfined aquifers

DOE PAGES

Keating, Elizabeth H.; Harp, Dylan H.; Dai, Zhenxue; ...

2016-01-28

Risk assessment studies of potential CO 2 sequestration projects consider many factors, including the possibility of brine and/or CO 2 leakage from the storage reservoir. Detailed multiphase reactive transport simulations have been developed to predict the impact of such leaks on shallow groundwater quality; however, these simulations are computationally expensive and thus difficult to directly embed in a probabilistic risk assessment analysis. Here we present a process for developing computationally fast reduced-order models which emulate key features of the more detailed reactive transport simulations. A large ensemble of simulations that take into account uncertainty in aquifer characteristics and CO 2/brinemore » leakage scenarios were performed. Twelve simulation outputs of interest were used to develop response surfaces (RSs) using a MARS (multivariate adaptive regression splines) algorithm (Milborrow, 2015). A key part of this study is to compare different measures of ROM accuracy. We then show that for some computed outputs, MARS performs very well in matching the simulation data. The capability of the RS to predict simulation outputs for parameter combinations not used in RS development was tested using cross-validation. Again, for some outputs, these results were quite good. For other outputs, however, the method performs relatively poorly. Performance was best for predicting the volume of depressed-pH-plumes, and was relatively poor for predicting organic and trace metal plume volumes. We believe several factors, including the non-linearity of the problem, complexity of the geochemistry, and granularity in the simulation results, contribute to this varied performance. The reduced order models were developed principally to be used in probabilistic performance analysis where a large range of scenarios are considered and ensemble performance is calculated. We demonstrate that they effectively predict the ensemble behavior. But, the performance of the RSs is much less accurate when used to predict time-varying outputs from a single simulation. If an analysis requires only a small number of scenarios to be investigated, computationally expensive physics-based simulations would likely provide more reliable results. Finally, if the aggregate behavior of a large number of realizations is the focus, as will be the case in probabilistic quantitative risk assessment, the methodology presented here is relatively robust.« less

Effects of co-inoculation with arbuscular mycorrhizal fungi and rhizobia on soybean growth as related to root architecture and availability of N and P.

PubMed

Wang, Xiurong; Pan, Qiang; Chen, Fengxian; Yan, Xiaolong; Liao, Hong

2011-04-01

Soybean plants can form tripartite symbiotic associations with rhizobia and arbuscular mycorrhizal (AM) fungi, but little is known about effects of co-inoculation with rhizobia and AM fungi on plant growth, or their relationships to root architecture as well as nitrogen (N) and phosphorus (P) availability. In the present study, two soybean genotypes contrasting in root architecture were grown in a field experiment to evaluate relationships among soybean root architecture, AMF colonization, and nodulation under natural conditions. Additionally, a soil pot experiment in greenhouse was conducted to investigate the effects of co-inoculation with rhizobia and AM fungi on soybean growth, and uptake of N and P. Our results indicated that there was a complementary relationship between root architecture and AMF colonization in the field. The deep root soybean genotype had greater AMF colonization at low P, but better nodulation with high P supply than the shallow root genotype. A synergistic relationship dependent on N and P status exists between rhizobia and AM fungi on soybean growth. Co-inoculation with rhizobia and AM fungi significantly increased soybean growth under low P and/or low N conditions as indicated by increased shoot dry weight, along with plant N and P content. There were no significant effects of inoculation under adequate N and P conditions. Furthermore, the effects of co-inoculation were related to root architecture. The deep root genotype, HN112, benefited more from co-inoculation than the shallow root genotype, HN89. Our results elucidate new insights into the relationship between rhizobia, AM fungi, and plant growth under limitation of multiple nutrients, and thereby provides a theoretical basis for application of co-inoculation in field-grown soybean.

Plant identity and shallow soil moisture are primary drivers of stomatal conductance in the savannas of Kruger National Park

PubMed Central

Tobin, Rebecca L.

2018-01-01

Our goal was to describe stomatal conductance (gs) and the site-scale environmental parameters that best predict gs in Kruger National Park (KNP), South Africa. Dominant grass and woody species were measured over two growing seasons in each of four study sites that represented the natural factorial combination of mean annual precipitation [wet (750 mm) or dry (450 mm)] and soil type (clay or sand) found in KNP. A machine-learning (random forest) model was used to describe gs as a function of plant type (species or functional group) and site-level environmental parameters (CO2, season, shortwave radiation, soil type, soil moisture, time of day, vapor pressure deficit and wind speed). The model explained 58% of the variance among 6,850 gs measurements. Species, or plant functional group, and shallow (0–20 cm) soil moisture had the greatest effect on gs. Atmospheric drivers and soil type were less important. When parameterized with three years of observed environmental data, the model estimated mean daytime growing season gs as 68 and 157 mmol m-2 sec-1 for grasses and woody plants, respectively. The model produced here could, for example, be used to estimate gs and evapotranspiration in KNP under varying climate conditions. Results from this field-based study highlight the role of species identity and shallow soil moisture as primary drivers of gs in savanna ecosystems of KNP. PMID:29373605

A homemade sand-volcano in a gassy alluvial plain (Medolla, Italy): when shallow drilling triggers violent degassing

NASA Astrophysics Data System (ADS)

Capaccioni, Bruno; Coltorti, Massimo; Todesco, Micol; Cremoni, Stefano; Di Giuseppe, Dario; Faccini, Barbara; Tessari, Umberto

2017-04-01

Sand volcanoes are remarkable geological features which form when shallow, water-saturated sand deposits are set in motion and reach the surface. This commonly occurs during earthquakes, as a result of liquefaction of waterlogged bodies, but some of these sand emissions are unrelated to seismic events. We present the case of a sand eruption triggered by a Cone Penetration Test (CPT) near Medolla (Italy), on the 10th of October 2014. A large amount of natural gas (CO2 and CH4)was erupted together with a mixture of water and sand, creating a sand volcano. The event was recorded and its evolution and final result were analyzed from several points of view. Our multidisciplinary approach involved morphological and sedimentological studies on the sand-volcano, chemical and isotopic analysis of discharged gases, repeated measurements of gas flux on the drill hole and of diffuse degassing in the surrounding area and numerical modelling of the aquifer feeding the discharge. Our results suggest that a geyser discharging a mixture of gas and water, capable of building a sand volcano, requires the presence of a shallow pressurized reservoir (1.2 MPa) where water coexists with a small amount of exsolved gas (a volume fraction of 0.05). The violent degassing occurred in Medolla confirms the role that a free gas phase may have in favoring the mobilization of liquid water and loose deposits, even in the absence of a seismic event.

The influence of agricultural management on soil's CO2 regime in semi-arid and arid regions

NASA Astrophysics Data System (ADS)

Eshel, G.; Lifshithz, D.; Sternberg, M.; Ben-Dor, E.; Bonfile, D. J.; Arad, B.; Mingelgrin, U.; Fine, P.; Levy, G. J.

2008-12-01

Two of the more important parameters which may help us better evaluate the impact of agricultural practices on the global carbon cycle are the in-situ soil pCO2 profile and the corresponding CO2 fluxes to the atmosphere. In an ongoing study, we monitored the pCO2 to a depth of 5 m in two adjacent irrigated Avocado orchards in the coastal plain of Israel (semi-arid region), and to a depth of 2 m in a semi- arid rain-fed and a arid rain-fed wheat fields in southern Israel. The soil pCO2 profiles and CO2 fluxes measurements were supplemented by measurements of soil moisture and temperature. The results showed differences in the CO2 profiles (both in the depth of the highest concentration and its absolute values) and the CO2 fluxes between the orchards and the wheat fields as well as along the year. In the irrigated Avocado orchards pCO2 values were in the range of 1.5 kPa at a depth of 0.5 m up to 8 kPa at depths of 3-5 m (even though Avocado trees are characterized by shallow roots). Such levels could affect reactions (e.g., enhancement of inorganic carbon dissolution) that may take place in the soil and some of its chemical properties (e.g., pH). As expected, soil pCO2 was affected by soil moisture and temperature, and the distance from the trees. Maximum soil respiration was observed during the summer when the orchards are under irrigation. In the wheat fields pCO2 level ranged from 0.2- 0.6 kPa at a depth of 0.2 m to 0.2-1 kPa at depths of 1-1.5 m (in arid and semiarid respectively). These pCO2 levels were much lower than those obtained in the irrigated orchards and seemed to depend on the wheat growing cycle (high concentration were noted at depth of 1-1.5 m close to the end of grain filling) and precipitation gradient (arid vs. semiarid). Since CO2 fluxes are directly affected by the pCO2 profile and soil moister and temperature the CO2 fluxes from the wheat fields were much lower (0.02- 0.2 ml min-1 m-2) compared to those obtained from the Avocado orchards (2-7 ml min-1 m-2). Our results clearly demonstrate the large variability in soil pCO2 concentration and flux to the atmosphere, and its dependence on the soil moisture regime (annual precipitation and irrigation) and type of cropping (orchard vs. field crop).

FTIR microspectroscopy and SIMS study of water-poor cordierite from El Hoyazo, Spain: Application to mineral and melt devolatilization

NASA Astrophysics Data System (ADS)

Della Ventura, Giancarlo; Bellatreccia, Fabio; Cesare, Bernardo; Harley, Simon; Piccinini, Massimo

2009-12-01

This paper reports the microchemical and microspectroscopic FTIR study of cordierite from a partially melted graphite-bearing granulitic enclave within the dacitic lava dome of El Hoyazo (SE Spain). Optically transparent single-crystals, hand picked from the rock, were oriented using X-ray diffraction and studied by Fourier-transform infrared (FTIR). Single-crystal FTIR spectroscopy shows that the examined cordierite is CO 2-rich and almost H 2O-free. Two weak and sharp peaks are observed at 3708 and 3595 cm - 1 , respectively, which are strongly polarised for E // a. These peaks are assigned to combination modes of CO 2. Very weak bands due to H 2O molecules oriented with the H…H vector // c (type I water) are occasionally observed in certain zones of the grains, associated with absorptions due to hydrated inclusions of alteration products. The very intense bands observed in the 2600-2000 cm - 1 region are assigned to CO 2 molecules oriented // a; the spectra also show the presence of 13C and 18O, and weak amounts of CO in the sample. Microspectrometric mapping shows that the distribution of C is relatively homogeneous, whereas that of H 2O is complicated by a very broad absorption extending from 3700 to 3100 cm - 1 . High-resolution FTIR imaging, done using a focal-plane array of detectors, shows that this broad absorption is associated with microfractures. SIMS analyses give an average concentration of H 2O = 0.033 ± 0.007 wt.% and CO 2 = 0.21 ± 0.07 wt.%. On the basis of these data, molar absorption coefficients can be calibrated for CO 2: ɛiCO2 (integrated) = 11,000 ± 4000 l/(mol cm - 2 ) and ɛlCO2 (linear) = 800 ± 250 l/(mol cm - 1 ). Due to the extremely low amount of H 2O and its inhomogeneous distribution, calibration of absorption ɛH2O coefficients is unreliable. The very low H 2O contents in the El Hoyazo cordierite indicate continued mineral-melt volatile exchange during decompression from ˜ 5 kbar to significantly shallower levels.

The effect of CO2 and Nd:YAP lasers on CAD/CAM Ceramics: SEM, EDS and thermal studies

PubMed Central

Fornaini, Carlo; Rocca, Jean Paul; Muhammad, Omid H; Medioni, Etienne; Cucinotta, Annamaria; Brulat-Bouchard, Nathalie

2016-01-01

Background and aims: The objective of this study was to investigate the interaction of infrared laser light on Computer Aided Design and Computer Aided Manufacturing (CAD/CAM) ceramic surfaces. Material and Methods: Sixty CAD/CAM ceramic discs were prepared and divided into two different groups: lithiumdisilicate ceramic (IPSe.maxCADs) and Zirconia ceramic (IPSe.maxZirCADs). The laser irradiation was performed on graphite and non-graphite surfaces with a Carbon Dioxide laser at 5W and 10W power in continuous mode (CW mode) and with Neodymium Yttrium Aluminum Perovskite (Nd:YAP) laser at 10W. Surface textures and compositions were examined using Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS). Thermal elevation was measured by thermocouple during laser irradiation. Results: The SEM observation showed a rough surface plus cracks and fissures on CO2 10W samples and melting areas in Nd:YAP samples; moreover, with CO2 5W smooth and shallow surfaces were observed. EDS analysis revealed that laser irradiation does not result in modifications of the chemical composition even if minor changes in the atomic mass percentage of the components were registered. Thermocouple showed several thermal changes during laser irradiation. Conclusion: CO2 and Nd:YAP lasers modify CAD/CAM ceramic surface without chemical composition modifications. PMID:27141152

Assessment of CO2 discharge in a spring using time-variant stable carbon isotope data as a natural analogue study of CO2 leakage

NASA Astrophysics Data System (ADS)

Yu, Soonyoung; Chae, Gitak; Jo, Minki; Kim, Jeong-Chan; Yun, Seong-Taek

2015-04-01

CO2-rich springs have been studied as a natural analogue of CO2 leakage through shallow subsurface environment, as they provide information on the behaviors of CO2 during the leakage from geologic CO2 storage sites. For this study, we monitored the δ13C values as well as temperature, pH, EC, DO, and alkalinity for a CO2-rich spring for 48 hours. The water samples (N=47) were collected every hour in stopper bottles without headspace to avoid the interaction with air and the CO2 degassing. The δ13C values of total dissolved inorganic carbon (TDIC) in the water samples were analyzed using a cavity ring-down spectroscopy (CRDS) system (Picarro). The values of δ13CTDIC, temperature, pH, EC, DO, and alkalinity were in the range of -9.43 ~ -8.91 o 12.3 ~ 13.2oC, 4.86 ~ 5.02, 186 ~ 189 μS/cm, 1.8 ~ 3.4 mg/L, and 0.74 ~ 0.95 meq/L, respectively. The concentrations of TDIC calculated using pH and alkalinity values were between 22.5 and 34.8 mmol/L. The δ13CTDIC data imply that dissolved carbon in the spring was derived from a deep-seated source (i.e., magmatic) that was slightly intermixed with soil CO2. Careful examination of the time-series variation of measured parameters shows the following characteristics: 1) the δ13CTDIC values are negatively correlated with pH (r = -0.59) and positively correlated with TDIC (r = 0.58), and 2) delay times of the change of pH and alkalinity following the change of δ13CTDIC values are 0 and -3 hours, respectively; the pH change occurs simultaneously with the change of δ13CTDIC, while the alkalinity change happens before 3 hours. Our results indicate that the studied CO2-rich spring is influenced by the intermittent supply of deep-seated CO2. [Acknowledgment] This work was financially supported by the fundamental research project of KIGAM and partially by the "Geo-Advanced Innovative Action (GAIA) Project (2014000530003)" from Korea Ministry of Environment (MOE).

Surface drilling technologies for Mars

NASA Technical Reports Server (NTRS)

Blacic, J. D.; Rowley, J. C.; Cort, G. E.

1986-01-01

Rock drilling and coring conceptual designs for the surface activities associated with a manned Mars mission are proposed. Straightforward extensions of equipment and procedures used on Earth are envisioned for the sample coring and shallow high explosive shot holes needed for tunneling and seismic surveying. A novel rocket exhaust jet piercing method is proposed for very rapid drilling of shot holes required for explosive excavation of emergency radiation shelters. Summaries of estimated equipment masses and power requirements are provided, and the indicated rotary coring rigs are scaled from terrestrial equipment and use compressed CO2 from the Martian atmosphere for core bit cooling and cuttings removal. A mass of 120 kg and power of 3 kW(e) are estimated for a 10 m depth capability. A 100 m depth capacity core rig requires about 1150 kg and 32 km(e). The rocket exhaust jet equipment devised for shallow (3m) explosive emplacement shot holes requires no surface power beyond an electrical ignition system, and might have a 15 kg mass.

Constraints on magma processes, subsurface conditions, and total volatile flux at Bezymianny Volcano in 2007–2010 from direct and remote volcanic gas measurements

USGS Publications Warehouse

Lopez, Taryn; Ushakov, Sergey; Izbekov, Pavel; Tassi, Franco; Cahill, Cathy; Neill, Owen; Werner, Cynthia A.

2013-01-01

Direct and remote measurements of volcanic gas composition, SO2 flux, and eruptive SO2 mass from Bezymianny Volcano were acquired between July 2007 and July 2010. Chemical composition of fumarolic gases, plume SO2 flux from ground and air-based ultraviolet remote sensing (FLYSPEC), and eruptive SO2 mass from Ozone Monitoring Instrument (OMI) satellite observations were used along with eruption timing to elucidate magma processes and subsurface conditions, and to constrain total volatile flux. Bezymianny Volcano had five explosive magmatic eruptions between May 2007 and June 2010. The most complete volcanic gas datasets were acquired for the October 2007, December 2009, and May 2010 eruptions. Gas measurements collected prior to the October 2007 eruption have a relatively high ratio of H2O/CO2 (81.2), a moderate ratio of CO2/S (5.47), and a low ratio of S/HCl (0.338), along with moderate SO2 and CO2 fluxes of 280 and 980 t/d, respectively, and high H2O and HCl fluxes of ~ 45,000 and ~ 440 t/d, respectively. These results suggest degassing of shallow magma (consistent with observations of lava extrusion) along with potential minor degassing of a deeper magma source. Gas measurements collected prior to the December 2009 eruption are characterized by relatively low H2O/CO2 (4.13), moderate CO2/S (6.84), and high S/HCl (18.7) ratios, along with moderate SO2 and CO2 fluxes of ~ 220 and ~ 1000 t/d, respectively, and low H2O and HCl fluxes of ~ 1700 and ~ 7 t/d, respectively. These trends are consistent with degassing of a deeper magma source. Fumarole samples collected ~ 1.5 months following the May 2010 eruption are characterized by high H2O/CO2 (63.0), low CO2/S (0.986), and moderate S/HCl (6.09) ratios. These data are consistent with degassing of a shallow, volatile-rich magma source, likely related to the May eruption. Passive and eruptive SO2 measurements are used to calculate a total annual SO2 mass of 109 kt emitted in 2007, with passive emissions comprising ~ 87–95% of the total. Total annual volatile masses for the study period are estimated to range from 1.1 × 106 to 18 × 106 t/year. Annual CO2 masses are ~ 8 to 40 times larger than can be explained by degassing of dissolved CO2 within eruptive magma, suggesting that the eruptive magma contained a significant quantity of exsolved volatiles sourced either from the eruptive melt or unerupted magma at depth. Variable total volatile fluxes ranging from ~ 3000 t/d in 2009 to ~ 49,000 t/d in 2007 are attributed to variations in the depth of gas exsolution and separation from the melt under open-system degassing conditions. We propose that exsolved volatiles are quickly transported to the surface from ascending magma via permeable flow through a bubble and/or fracture network within the conduit and thus retain their equilibrium composition at the time of segregation from melt. The composition of surface CO2 and H2O emissions from 2007 to 2009 are compared with modeled exsolved fluid compositions for a magma body ascending from entrapment depths to estimate depth of fluid exsolution and separation from the melt. We find that at the time of sample collection magma had already begun ascent from the mid-crustal storage region and was located at maximum depths of ~ 3.7 km in August 2007, approximately 2 months prior to the next magmatic eruption, and ~ 4.6 km in July of 2009 approximately five months prior to the next magmatic eruption. These findings suggest that the exsolved gas composition at Bezymianny Volcano may be used to detect magma ascent prior to eruption.

Inversion of Coeval Shear and Normal Stress of Piton de la Fournaise Flank Displacement

NASA Astrophysics Data System (ADS)

Cayol, V.; Tridon, M.; Froger, J. L.; Augier, A.; Bachelery, P.

2016-12-01

The April 2007 eruption of Piton de la Fournaise was the biggest volcano eruptive crisis of the 20th and 21st centuries. InSAR captured a large (1.4 m) co-eruptive seaward slip of the volcano's eastern flank, which continued for more than a year at a decreasing rate. Co-eruptive uplift and post-eruptive subsidence were also observed. While it is generally agreed that flank displacement is induced by fault slip, we investigate wether this flank displacement might have been induced by a sheared sill, as suggested by observations of sheared sills at Piton des Neiges. To test this hypothesis, we develop a new method to invert a quadrangular curved source submitted to co-eval pressure and shear stress changes. This method, based on boundary elements, is applied to co-eruptive and post-eruptive InSAR data. We find that co-eruptive displacement is explained by a 2 km by 2 km detachment fault, parallel to the flank and probably coincident with a lithological discontinuity. The fracture is shallow enough to induce the co-eval uplift characteristic of a detachment fold. We determine the co-eruptive overpressure is zero, which indicates that the fracture is not a sheared sill. This finding confirms a previous determination obtained using a decision tree based on ratios of maximum displacements. The determined shear stress change of 2 MPa is conistent with the eastern flank loaded by previously intruded rift dikes. Post-eruptive displacement is well explained by slip and closure of the same fracture but over a larger (5 km by 8 km). This displacements is consistent with relaxation and the co-eruptive flank displacement and causal link between both displacement is investigated.

Benthic foraminiferal paleoecology and depositional patterns during the Albian at DSDP Site 327 (Falkland Plateau)

NASA Astrophysics Data System (ADS)

Lopes, Fernando M.; Koutsoukos, Eduardo A. M.; Kochhann, Karlos G. D.; Savian, Jairo F.; Fauth, Gerson

2017-10-01

The present paleoenvironmental study uses a spectrum of analytical methods, such as benthic foraminiferal assemblages, total organic carbon (TOC), calcium carbonate (CaCO3) contents and magnetic susceptibility (MS), to monitor variations in primary productivity, bottom-water oxygenation and depositional patterns within the Albian interval recovered at DSDP Site 327, Hole A, Falkland Plateau. Thirty-three benthic foraminiferal species were identified in the studied section and, based on the abundances of morphogroups (epifaunal and shallow infaunal), two distinct associations were identified. Stratigraphic intervals dominated by the epifaunal morphogroup can be interpreted as indicative of bottom-waters with low-oxygen content. However, these decreases in oxygenation were not vigorous enough to establish a dominance of deep-infaunal morphotypes, as supported by the low TOC values. Intervals dominated by the shallow infaunal morphogroup were interpreted as subjected to moderate to high nutrient flux to the ocean floor. These intervals are associated with high MS values and low CaCO3 content, suggesting that dissolution processes, rather than increased primary productivity, controlled CaCO3 accumulation in the studied section. Furthermore, faunal analysis points to deposition in an outer neritic to upper bathyal paleoenvironment.

Acoustic MIMO communications in a very shallow water channel

NASA Astrophysics Data System (ADS)

Zhou, Yuehai; Cao, Xiuling; Tong, Feng

2015-12-01

Underwater acoustic channels pose significant difficulty for the development of high speed communication due to highly limited band-width as well as hostile multipath interference. Enlightened by rapid progress of multiple input multiple output (MIMO) technologies in wireless communication scenarios, MIMO systems offer a potential solution by enabling multiple spatially parallel communication channels to improve communication performance as well as capacity. For MIMO acoustic communications, deep sea channels offer substantial spatial diversity among multiple channels that can be exploited to address simultaneous multipath and co-channel interference. At the same time, there are increasing requirements for high speed underwater communication in very shallow water area (for example, a depth less than 10 m). In this paper, a space-time multichannel adaptive receiver consisting of multiple decision feedback equalizers (DFE) is adopted as the receiver for a very shallow water MIMO acoustic communication system. The performance of multichannel DFE receivers with relatively small number of receiving elements are analyzed and compared with that of the multichannel time reversal receiver to evaluate the impact of limited spatial diversity on multi-channel equalization and time reversal processing. The results of sea trials in a very shallow water channel are presented to demonstrate the feasibility of very shallow water MIMO acoustic communication.

Methane, Carbon Dioxide and Nitrous Oxide Fluxes in Soil Profile under a Winter Wheat-Summer Maize Rotation in the North China Plain

PubMed Central

Wang, Yuying; Hu, Chunsheng; Ming, Hua; Oenema, Oene; Schaefer, Douglas A.; Dong, Wenxu; Zhang, Yuming; Li, Xiaoxin

2014-01-01

The production and consumption of the greenhouse gases (GHGs) methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O) in soil profile are poorly understood. This work sought to quantify the GHG production and consumption at seven depths (0–30, 30–60, 60–90, 90–150, 150–200, 200–250 and 250–300 cm) in a long-term field experiment with a winter wheat-summer maize rotation system, and four N application rates (0; 200; 400 and 600 kg N ha−1 year−1) in the North China Plain. The gas samples were taken twice a week and analyzed by gas chromatography. GHG production and consumption in soil layers were inferred using Fick’s law. Results showed nitrogen application significantly increased N2O fluxes in soil down to 90 cm but did not affect CH4 and CO2 fluxes. Soil moisture played an important role in soil profile GHG fluxes; both CH4 consumption and CO2 fluxes in and from soil tended to decrease with increasing soil water filled pore space (WFPS). The top 0–60 cm of soil was a sink of atmospheric CH4, and a source of both CO2 and N2O, more than 90% of the annual cumulative GHG fluxes originated at depths shallower than 90 cm; the subsoil (>90 cm) was not a major source or sink of GHG, rather it acted as a ‘reservoir’. This study provides quantitative evidence for the production and consumption of CH4, CO2 and N2O in the soil profile. PMID:24892931

Boron isotope fractionation in magma via crustal carbonate dissolution

PubMed Central

Deegan, Frances M.; Troll, Valentin R.; Whitehouse, Martin J.; Jolis, Ester M.; Freda, Carmela

2016-01-01

Carbon dioxide released by arc volcanoes is widely considered to originate from the mantle and from subducted sediments. Fluids released from upper arc carbonates, however, have recently been proposed to help modulate arc CO2 fluxes. Here we use boron as a tracer, which substitutes for carbon in limestone, to further investigate crustal carbonate degassing in volcanic arcs. We performed laboratory experiments replicating limestone assimilation into magma at crustal pressure-temperature conditions and analysed boron isotope ratios in the resulting experimental glasses. Limestone dissolution and assimilation generates CaO-enriched glass near the reaction site and a CO2-dominated vapour phase. The CaO-rich glasses have extremely low δ11B values down to −41.5‰, reflecting preferential partitioning of 10B into the assimilating melt. Loss of 11B from the reaction site occurs via the CO2 vapour phase generated during carbonate dissolution, which transports 11B away from the reaction site as a boron-rich fluid phase. Our results demonstrate the efficacy of boron isotope fractionation during crustal carbonate assimilation and suggest that low δ11B melt values in arc magmas could flag shallow-level additions to the subduction cycle. PMID:27488228

Boron isotope fractionation in magma via crustal carbonate dissolution

NASA Astrophysics Data System (ADS)

Deegan, Frances M.; Troll, Valentin R.; Whitehouse, Martin J.; Jolis, Ester M.; Freda, Carmela

2016-08-01

Carbon dioxide released by arc volcanoes is widely considered to originate from the mantle and from subducted sediments. Fluids released from upper arc carbonates, however, have recently been proposed to help modulate arc CO2 fluxes. Here we use boron as a tracer, which substitutes for carbon in limestone, to further investigate crustal carbonate degassing in volcanic arcs. We performed laboratory experiments replicating limestone assimilation into magma at crustal pressure-temperature conditions and analysed boron isotope ratios in the resulting experimental glasses. Limestone dissolution and assimilation generates CaO-enriched glass near the reaction site and a CO2-dominated vapour phase. The CaO-rich glasses have extremely low δ11B values down to -41.5‰, reflecting preferential partitioning of 10B into the assimilating melt. Loss of 11B from the reaction site occurs via the CO2 vapour phase generated during carbonate dissolution, which transports 11B away from the reaction site as a boron-rich fluid phase. Our results demonstrate the efficacy of boron isotope fractionation during crustal carbonate assimilation and suggest that low δ11B melt values in arc magmas could flag shallow-level additions to the subduction cycle.

Boron isotope fractionation in magma via crustal carbonate dissolution.

PubMed

Deegan, Frances M; Troll, Valentin R; Whitehouse, Martin J; Jolis, Ester M; Freda, Carmela

2016-08-04

Carbon dioxide released by arc volcanoes is widely considered to originate from the mantle and from subducted sediments. Fluids released from upper arc carbonates, however, have recently been proposed to help modulate arc CO2 fluxes. Here we use boron as a tracer, which substitutes for carbon in limestone, to further investigate crustal carbonate degassing in volcanic arcs. We performed laboratory experiments replicating limestone assimilation into magma at crustal pressure-temperature conditions and analysed boron isotope ratios in the resulting experimental glasses. Limestone dissolution and assimilation generates CaO-enriched glass near the reaction site and a CO2-dominated vapour phase. The CaO-rich glasses have extremely low δ(11)B values down to -41.5‰, reflecting preferential partitioning of (10)B into the assimilating melt. Loss of (11)B from the reaction site occurs via the CO2 vapour phase generated during carbonate dissolution, which transports (11)B away from the reaction site as a boron-rich fluid phase. Our results demonstrate the efficacy of boron isotope fractionation during crustal carbonate assimilation and suggest that low δ(11)B melt values in arc magmas could flag shallow-level additions to the subduction cycle.

Detection and impacts of leakage from sub-seafloor deep geological carbon dioxide storage

NASA Astrophysics Data System (ADS)

Blackford, Jerry; Stahl, Henrik; Bull, Jonathan M.; Bergès, Benoît J. P.; Cevatoglu, Melis; Lichtschlag, Anna; Connelly, Douglas; James, Rachael H.; Kita, Jun; Long, Dave; Naylor, Mark; Shitashima, Kiminori; Smith, Dave; Taylor, Peter; Wright, Ian; Akhurst, Maxine; Chen, Baixin; Gernon, Tom M.; Hauton, Chris; Hayashi, Masatoshi; Kaieda, Hideshi; Leighton, Timothy G.; Sato, Toru; Sayer, Martin D. J.; Suzumura, Masahiro; Tait, Karen; Vardy, Mark E.; White, Paul R.; Widdicombe, Steve

2014-11-01

Fossil fuel power generation and other industrial emissions of carbon dioxide are a threat to global climate, yet many economies will remain reliant on these technologies for several decades. Carbon dioxide capture and storage (CCS) in deep geological formations provides an effective option to remove these emissions from the climate system. In many regions storage reservoirs are located offshore, over a kilometre or more below societally important shelf seas. Therefore, concerns about the possibility of leakage and potential environmental impacts, along with economics, have contributed to delaying development of operational CCS. Here we investigate the detectability and environmental impact of leakage from a controlled sub-seabed release of CO2. We show that the biological impact and footprint of this small leak analogue (<1 tonne CO2 d-1) is confined to a few tens of metres. Migration of CO2 through the shallow seabed is influenced by near-surface sediment structure, and by dissolution and re-precipitation of calcium carbonate naturally present in sediments. Results reported here advance the understanding of environmental sensitivity to leakage and identify appropriate monitoring strategies for full-scale carbon storage operations.

Fabrication of mirror templates in silica with micron-sized radii of curvature

NASA Astrophysics Data System (ADS)

Najer, Daniel; Renggli, Martina; Riedel, Daniel; Starosielec, Sebastian; Warburton, Richard J.

2017-01-01

We present the fabrication of exceptionally small-radius concave microoptics on fused silica substrates using CO2 laser ablation and subsequent reactive ion etching. The protocol yields on-axis near-Gaussian depressions with a radius of curvature ≲5 μm at shallow depth and low surface roughness of 2 Å. This geometry is appealing for cavity quantum electrodynamics where small mode volumes and low scattering losses are desired. We study the optical performance of the structures within a tunable Fabry-Pérot type microcavity and demonstrate near-coating-limited loss rates ( F = 25 000 ) and small focal lengths consistent with their geometrical dimensions.

Applying monitoring, verification, and accounting techniques to a real-world, enhanced oil recovery operational CO2 leak

USGS Publications Warehouse

Wimmer, B.T.; Krapac, I.G.; Locke, R.; Iranmanesh, A.

2011-01-01

The use of carbon dioxide (CO2) for enhanced oil recovery (EOR) is being tested for oil fields in the Illinois Basin, USA. While this technology has shown promise for improving oil production, it has raised some issues about the safety of CO2 injection and storage. The Midwest Geological Sequestration Consortium (MGSC) organized a Monitoring, Verification, and Accounting (MVA) team to develop and deploy monitoring programs at three EOR sites in Illinois, Indiana, and Kentucky, USA. MVA goals include establishing baseline conditions to evaluate potential impacts from CO2 injection, demonstrating that project activities are protective of human health and the environment, and providing an accurate accounting of stored CO2. This paper focuses on the use of MVA techniques in monitoring a small CO2 leak from a supply line at an EOR facility under real-world conditions. The ability of shallow monitoring techniques to detect and quantify a CO2 leak under real-world conditions has been largely unproven. In July of 2009, a leak in the pipe supplying pressurized CO2 to an injection well was observed at an MGSC EOR site located in west-central Kentucky. Carbon dioxide was escaping from the supply pipe located approximately 1 m underground. The leak was discovered visually by site personnel and injection was halted immediately. At its largest extent, the hole created by the leak was approximately 1.9 m long by 1.7 m wide and 0.7 m deep in the land surface. This circumstance provided an excellent opportunity to evaluate the performance of several monitoring techniques including soil CO2 flux measurements, portable infrared gas analysis, thermal infrared imagery, and aerial hyperspectral imagery. Valuable experience was gained during this effort. Lessons learned included determining 1) hyperspectral imagery was not effective in detecting this relatively small, short-term CO2 leak, 2) even though injection was halted, the leak remained dynamic and presented a safety risk concern during monitoring activities and, 3) the atmospheric and soil monitoring techniques used were relatively cost-effective, easily and rapidly deployable, and required minimal manpower to set up and maintain for short-term assessments. However, characterization of CO2 distribution near the land surface resulting from a dynamic leak with widely variable concentrations and fluxes was challenging. ?? 2011 Published by Elsevier Ltd.

Organic matter composition and substrate diversity under elevated CO2 in the Mojave Desert

NASA Astrophysics Data System (ADS)

Tfaily, M. M.; Hess, N. J.; Koyama, A.; Evans, R. D.

2016-12-01

Little is known about how rising atmospheric CO2 concentration will impact long-term plant biomass or the dynamics of soil organic matter (SOM) in arid ecosystems. In this study, we investigated the change in the molecular composition of SOM by high resolution mass spectrometry after 10 years exposure to elevated atmospheric CO2 concentrations at the Nevada Desert FACE Facility. Samples were collected from soil profiles from 0 to 1m in 0.2m increments under the dominant evergreen shrub (Larrea tridentata). The differences in the composition of SOM were more evident in soils close to the surface and consistent with higher bulk soil organic carbon (C) and total nitrogen (N) concentrations under elevated than ambient CO2, reflecting increased net productivity of shrubs under elevated CO2, which could be attributed to increased litter input from above-ground biomass and/or shallow roots, root exudation and/or microbial residues. This was further supported by the significant increase in the abundance of amino sugars-, protein- and carbohydrate-like compounds. These compounds are involved in diverse pathways ranging from sugars and amino-acid metabolism to lipid biosynthesis. This indicates increased activity and metabolism under elevated CO2 and suggests that elevated CO2 have altered microbial C use patterns, reflecting changes in the quality and quantity of soil C inputs. A significant increase in the mineral-bound soil organic C was also observed in the surface soils under elevated CO2. This was accompanied by increased microbial residues as identified by mass spectrometry that supports microbial lipid analysis, and reflecting accelerated microbial turnover under elevated CO2. Fungal neutral lipid fatty acids (NLFA) abundance doubled under elevated CO2. When provided with excess labile compounds, such as root exudates, and with limited supply of nutrients, fungi assimilate the excess labile C and store it as NLFA likely contributing to increased total N concentrations. This was further supported by the presence of acetyl glucosamine, a typical amino sugar, present in the chitin of fungi, under elevated than ambient CO2. Our results suggest that arid ecosystems, limited by water, may have a different C storage potential under changing climates than other ecosystems that are limited by N or P.

Storm Driven Upwelling Responsible for pCO2-rich Water Intrusion in the South Atlantic Bight

NASA Astrophysics Data System (ADS)

Noakes, S.; Gledhill, D. K.

2016-02-01

Gray's Reef National Marine Sanctuary (GRNMS) is located approximately 20 miles offshore Georgia along the inner to middle shelf of the South Atlantic Bight (SAB). The University of Georgia (UGA) and the Pacific Marine Environmental Lab have maintained a high resolution pCO2 system for almost a decade on the National Data Buoy Center's buoy moored at GRNMS. To support the surface monitoring and set the stage for benthic monitoring at GRNMS, UGA and GRNMS have established a seafloor observatory that monitors pCO2, pH and water quality parameters. Traditional thought had held that given the relatively shallow water depth at GRNMS, the pCO2 measured on the surface could be extrapolated to the seafloor and utilized to monitor the benthic community. However, seafloor pCO2 data collected to date have revealed unusual episodes of subsurface pCO2-rich water moving through GRNMS that had not been previously identified by surface monitoring. Many of these events correspond with major storms that have either formed off the SAB or passed nearby GRNMS. Based on the surface data collected to date, temperature driven seasonal pCO2 changes occur naturally on an annual scale in the SAB which also affects the pH. However, the storms appear to have induced upwelling of pCO2-rich water from the deep Atlantic Ocean pushing it inward over the long continental shelf towards GRNMS. The result of the upwelling is a sharp increase of subsurface pCO2 lasting only days to weeks as compared to the seasonal cycle. It is part of the natural weather patterns for storms to form off the SAB or pass nearby, but depending on if the storm frequency increases due to global climate change, this process may become more of an impact on the benthic community. How this affects the benthic community has yet to be determined, but it is clear that they have adapted to seasonal fluctuations for survival. These upwellings are obviously adding to the SAB total carbon budget and affecting the benthic water quality, but to what extent have yet to be determined.

CO2-filled vesicles in mid-ocean basalt

USGS Publications Warehouse

Moore, J.G.; Batchelder, J.N.; Cunningham, C.G.

1977-01-01

Volatile-filled vesicles are present in minor amounts in all samples of mid-ocean basalt yet collected (and presumably erupted) down to depths of 4.8 km. When such vesicles are pierced in liquid under standard conditions, the volume expansion of the gas is 0.2 ?? 0.05 times the eruption pressure in bars or 20 ?? 5 times the eruption depth in km. Such expansion could be used as a measure of eruption depth. A variety of techniques: (1) vacuum crushing and gas chromatographic, freezing separation, and mass spectrographic analyses; (2) measurements of phase changes on a freezing microscope stage; (3) microscopic chemical and solubility observations; and (4) volume change measurements, all indicate that CO2 comprises more than 95% by volume of the vesicle gas in several submarine basalt samples from the Atlantic and Pacific. The CO2 held in vesicles is present in quantities about equal to or greater than that presumed to be dissolved in the glass (melt) and amounts to 400-900 ppm of the rock. The rigid temperature of the glass is 800-1000??C and increases for shallower samples. A sulfur gas was originally present in subordinate amounts in the vesicles, but has largely reacted with iron in the vesicle walls to produce sulfide spherules. ?? 1977.

Year-round CH4 and CO2 flux dynamics in two contrasting freshwater ecosystems of the subarctic

NASA Astrophysics Data System (ADS)

Jammet, Mathilde; Dengel, Sigrid; Kettner, Ernesto; Parmentier, Frans-Jan W.; Wik, Martin; Crill, Patrick; Friborg, Thomas

2017-11-01

Lakes and wetlands, common ecosystems of the high northern latitudes, exchange large amounts of the climate-forcing gases methane (CH4) and carbon dioxide (CO2) with the atmosphere. The magnitudes of these fluxes and the processes driving them are still uncertain, particularly for subarctic and Arctic lakes where direct measurements of CH4 and CO2 emissions are often of low temporal resolution and are rarely sustained throughout the entire year. Using the eddy covariance method, we measured surface-atmosphere exchange of CH4 and CO2 during 2.5 years in a thawed fen and a shallow lake of a subarctic peatland complex. Gas exchange at the fen exhibited the expected seasonality of a subarctic wetland with maximum CH4 emissions and CO2 uptake in summer, as well as low but continuous emissions of CH4 and CO2 throughout the snow-covered winter. The seasonality of lake fluxes differed, with maximum CO2 and CH4 flux rates recorded at spring thaw. During the ice-free seasons, we could identify surface CH4 emissions as mostly ebullition events with a seasonal trend in the magnitude of the release, while a net CO2 flux indicated photosynthetic activity. We found correlations between surface CH4 emissions and surface sediment temperature, as well as between diel CO2 uptake and diel solar input. During spring, the breakdown of thermal stratification following ice thaw triggered the degassing of both CH4 and CO2. This spring burst was observed in 2 consecutive years for both gases, with a large inter-annual variability in the magnitude of the CH4 degassing. On the annual scale, spring emissions converted the lake from a small CO2 sink to a CO2 source: 80 % of total annual carbon emissions from the lake were emitted as CO2. The annual total carbon exchange per unit area was highest at the fen, which was an annual sink of carbon with respect to the atmosphere. Continuous respiration during the winter partly counteracted the fen summer sink by accounting for, as both CH4 and CO2, 33 % of annual carbon exchange. Our study shows (1) the importance of overturn periods (spring or fall) for the annual CH4 and CO2 emissions of northern lakes, (2) the significance of lakes as atmospheric carbon sources in subarctic landscapes while fens can be a strong carbon sink, and (3) the potential for ecosystem-scale eddy covariance measurements to improve the understanding of short-term processes driving lake-atmosphere exchange of CH4 and CO2.

Surface ozone scenario and air quality in the north-central part of India.

PubMed

Saini, Renuka; Taneja, Ajay; Singh, Pradyumn

2017-09-01

Tropospheric pollutants including surface ozone (O 3 ), nitrogen dioxide (NO 2 ), carbon monoxide (CO) and meteorological parameters were measured at a traffic junction (78°2' E and 27°11' N) in Agra, India from January 2012 to December 2012. Temporal analysis of pollutants suggests that annual average mixing ratios of tropospheric pollutants were: O 3 - 22.97±23.36ppbV, NO 2 - 19.84±16.71ppbV and CO - 0.91±0.86ppmV, with seasonal variations of O 3 having maximum mixing ratio during summer season (32.41±19.31ppbV), whereas lowest was found in post-monsoon season (8.74±3.8ppbV). O 3 precursors: NO 2 and CO, showed inverse relationship with O 3 . Seasonal variation and high O 3 episodes during summer are associated with meteorological parameters such as high solar radiation, atmospheric temperature and transboundary transport. The interdependence of these variables showed a link between the daytime mixing ratios of O 3 with the nighttime level of NO 2 . The mixing ratios of CO and NO 2 showed tight correlations, which confirms the influence of vehicular emissions combined with other anthropogenic activities due to office/working hours, shallowing, and widening of boundary layer. FLEXTRA backward trajectories for the O 3 episode days clearly indicate the transport from the NW and W to S/SE and SW direction at Agra in different seasons. Copyright © 2017. Published by Elsevier B.V.

The comparative limnology of Lakes Nyos and Monoun, Cameroon

USGS Publications Warehouse

Kling, George; Evans, William C; Tanyileke, Gregory

2015-01-01

Lakes Nyos and Monoun are known for the dangerous accumulation of CO2 dissolved in stagnant bottom water, but the shallow waters that conceal this hazard are dilute and undergo seasonal changes similar to other deep crater lakes in the tropics. Here we discuss these changes with reference to climatic and water-column data collected at both lakes during the years following the gas release disasters in the mid-1980s. The small annual range in mean daily air temperatures leads to an equally small annual range of surface water temperatures (ΔT ~6–7 °C), reducing deep convective mixing of the water column. Weak mixing aids the establishment of meromixis, a requisite condition for the gradual buildup of CO2 in bottom waters and perhaps the unusual condition that most explains the rarity of such lakes. Within the mixolimnion, a seasonal thermocline forms each spring and shallow diel thermoclines may be sufficiently strong to isolate surface water and allow primary production to reduce PCO2 below 300 μatm, inducing a net influx of CO2 from the atmosphere. Surface water O2 and pH typically reach maxima at this time, with occasional O2 oversaturation. Mixing to the chemocline occurs in both lakes during the winter dry season, primarily due to low humidity and cool night time air temperature. An additional period of variable mixing, occasionally reaching the chemocline in Lake Monoun, occurs during the summer monsoon season in response to increased frequency of major storms. The mixolimnion encompassed the upper ~40–50 m of Lake Nyos and upper ~15–20 m of Lake Monoun prior to the installation of degassing pipes in 2001 and 2003, respectively. Degassing caused chemoclines to deepen rapidly. Piping of anoxic, high-TDS bottom water to the lake surface has had a complex effect on the mixolimnion. Algal growth stimulated by increased nutrients (N and P) initially stimulated photosynthesis and raised surface water O2 in Lake Nyos, but O2 removal through oxidation of iron was also enhanced and appeared to dominate at Lake Monoun. Depth-integrated O2 contents decreased in both lakes as did water transparency. No dangerous instabilities in water-column structure were detected over the course of degassing. While Nyos-type lakes are extremely rare, other crater lakes can pose dangers from gas releases and monitoring is warranted.

Design of an efficient space constrained diffuser for supercritical CO2 turbines

NASA Astrophysics Data System (ADS)

Keep, Joshua A.; Head, Adam J.; Jahn, Ingo H.

2017-03-01

Radial inflow turbines are an arguably relevant architecture for energy extraction from ORC and supercritical CO 2 power cycles. At small scale, design constraints can prescribe high exit velocities for such turbines, which lead to high kinetic energy in the turbine exhaust stream. The inclusion of a suitable diffuser in a radial turbine system allows some exhaust kinetic energy to be recovered as static pressure, thereby ensuring efficient operation of the overall turbine system. In supercritical CO 2 Brayton cycles, the high turbine inlet pressure can lead to a sealing challenge if the rotor is supported from the rotor rear side, due to the seal operating at rotor inlet pressure. An alternative to this is a cantilevered layout with the rotor exit facing the bearing system. While such a layout is attractive for the sealing system, it limits the axial space claim of any diffuser. Previous studies into conical diffuser geometries for supercritical CO 2 have shown that in order to achieve optimal static pressure recovery, longer geometries of a shallower cone angle are necessitated when compared to air. A diffuser with a combined annular-radial arrangement is investigated as a means to package the aforementioned geometric characteristics into a limited space claim for a 100kW radial inflow turbine. Simulation results show that a diffuser of this design can attain static pressure rise coefficients greater than 0.88. This confirms that annular-radial diffusers are a viable design solution for supercritical CO2 radial inflow turbines, thus enabling an alternative cantilevered rotor layout.

Revealing fate of CO2 leakage pathways in the Little Grand Wash Fault, Green River, Utah

NASA Astrophysics Data System (ADS)

Han, K.; Han, W. S.; Watson, Z. T.; Guyant, E.; Park, E.

2015-12-01

To assure long-term security of geologic carbon sequestration site, evaluation of natural CO2 leakage should be preceded before actual construction of the CO2 facility by comparing natural and artificial reservoir systems. The Little Grand Wash fault is located at the northwestern margin of the Paradox Basin and roles on a bypass of deep subsurface CO2 and brine water onto the surface, e.g., cold water geyser, CO2 spring, and surface travertine deposits. CO2 degassed out from brine at the Little Grand Wash fault zone may react with formation water and minerals while migrating through the fault conduit. Leakage observed by soil CO2 flux on the fault trace shows this ongoing transition of CO2, from supersaturated condition in deep subsurface to shallow surface equilibria. The present study aims to investigate the reactions induced by changes in hydrological and mineralogical factors inside of the fault zone. The methodology to develop site-specific geochemical model of the Little Grand Wash Fault combines calculated mechanical movements of each fluid end-member, along with chemical reactions among fluid, free CO2 gas and rock formations. Reactive transport modeling was conducted to simulate these property changes inside of the fault zone, using chemistry dataset based on 86 effluent samples of CO2 geysers, springs and in situ formation water from Entrada, Carmel, and Navajo Sandstone. Meanwhile, one- and two-dimensional models were separately developed to delineate features mentioned above. The results from the 3000-year simulation showed an appearance of self-sealing processes near the surface of the fault conduit. By tracking physicochemical changes at the depth of 15 m on the 2-dimensional model, significant changes induced by fluid mixing were indicated. Calculated rates of precipitation for calcite, illite, and pyrite showed increase in 2.6 x 10-4, 2.25 x 10-5, and 3.0 x 10-6 in mineral volume fraction at the depth of 15m, respectively. Concurrently, permeability and porosity were decreased 4.0 x 10-18 m2 and 3.0 x 10-4 due to precipitation of minerals. At the middle of the fault conduit (400 m), however, indicates consistent dissolution of minerals in formation which enhances vertical fluid migration.

Mushy Magma beneath Yellowstone

NASA Astrophysics Data System (ADS)

Chu, R.; Helmberger, D. V.; Sun, D.; Jackson, J. M.; Zhu, L.

2009-12-01

A recent prospective on the Yellowstone Caldera discounts its explosive potential based on inferences from tomographic studies on regional earthquake data which suggests a high degree of crystallization of the underlying magma body. In this study, we analyzed P-wave receiver functions recorded by broadband stations above the caldera from 100 teleseismic earthquakes between January and November 2008. After applying a number of waveform modeling tools, we obtained much lower seismic velocities than previous estimates, 2.3 km/sec (Vp) and 1.1 km/sec (Vs), with a thickness of 3.6 km in the upper crust. This shallow low velocity zone is severe enough to cause difficulties with seismic tool applications. In particular, seismologists expect teleseismic P-waves to arrive with motions up and away or down and back. Many of the observations recorded by the Yellowstone Intermountain Seismic Array, however, violate this assumption. We show that many of the first P-wave arrivals observed at seismic stations on the edge of the caldera do not travel through the magma body but have taken longer but faster paths around the edge or wrap-around phases. Three stations near the trailing edge have reversal radial-component motions, while stations near the leading edge do not. Adding our constraints on geometry, we conclude that this relatively shallow magma body has a volume of over 4,300 km3. We estimate the magma body by assuming a fluid-saturated porous material consisting of granite and a mixture of rhyolite melt and supercritical water and CO2 at temperatures of 800 oC and pressure at 5 km (0.1 GPa).Theoretical calculations of seismic wave speed suggests that the magma body beneath the Yellowstone Caldera has a porosity of 32% filled with 92% rhyolite melt and 8% water-CO2 by volume.

Effects of landfill gas on subtropical woody plants

NASA Astrophysics Data System (ADS)

Chan, G. Y. S.; Wong, M. H.; Whitton, B. A.

1991-05-01

An account is given of the influence of landfill gas on tree growth in the field at Gin Drinkers' Bay (GDB) landfill, Hong Kong, and in the laboratory. Ten species ( Acacia confusa, Albizzia lebbek, Aporusa chinensis, Bombax malabaricum, Castanopsis fissa, Liquidambar formosana, Litsea glutinosa, Machilus breviflora, Pinus elliottii, and Tristania conferta), belonging to eight families, were transplanted to two sites, one with a high concentration of landfill gas in the cover soil (high-gas site, HGS) and the other with a relatively low concentration of gas (low-gas site, LGS). Apart from the gaseous composition, the general soil properties were similar. A strong negative correlation between tree growth and landfill gas concentration was observed. A laboratory study using the simulated landfill gas to fumigate seedlings of the above species showed that the adventitious root growth of Aporusa chinensis, Bombax malabaricum, Machilus breviflora, and Tristania confera was stimulated by the gas, with shallow root systems being induced. Acacia confusa, Albizzia lebbek, and Litsea glutinosa were gas-tolerant, while root growth of Castanopsis fissa, Liquidambar formosana, and Pinus elliottii was inhibited. In most cases, shoot growth was not affected, exceptions being Bombax malabaricum, Liquidambar formosana, and Tristania conferta, where stunted growth and/or reduced foliation was observed. A very high CO2 concentration in cover soil limits the depth of the root system. Trees with a shallow root system become very susceptible to water stress. The effects of low O2 concentration in soil are less important than the effects of high CO2 concentration. Acacia confusa, Albizzia lebbek, and Tristania conferta are suited for growth on subtropical completed landfills mainly due to their gas tolerance and/or drought tolerance.

Linking Sediment Microbial Communities to Carbon Cycling in High-Latitude Lakes

NASA Astrophysics Data System (ADS)

Emerson, J. B.; Varner, R. K.; Johnson, J. E.; Owusu-Dommey, A.; Binder, M.; Woodcroft, B. J.; Wik, M.; Freitas, N. L.; Boyd, J. A.; Crill, P. M.; Saleska, S. R.; Tyson, G. W.; Rich, V. I.

2015-12-01

It is well recognized that thawing permafrost peatlands are likely to provide a positive feedback to climate change via CH4 and CO2 emissions. High-latitude lakes in these landscapes have also been identified as sources of CH4 and CO2 loss to the atmosphere. To investigate microbial contributions to carbon loss from high-latitude lakes, we characterized sediment geochemistry and microbiota via cores collected from deep and shallow regions of two lakes (Inre Harrsjön and Mellersta Harrsjön) in Arctic Sweden in July, 2012. These lakes are within the Stordalen Mire long-term ecological area, a focal site for investigating the impacts of climate change-related permafrost thaw, and the lakes in this area are responsible for ~55% of the CH4 loss from this hydrologically interconnected system. Across 40 samples from 4 to 40 cm deep within four sediment cores, Illumina 16S rRNA gene sequencing revealed that the sedimentary microbiota was dominated by candidate phyla OP9 and OP8 (Atribacteria and Aminicenantes, respectively, including putative fermenters and anaerobic respirers), predicted methanotrophic Gammaproteobacteria, and predicted methanogenic archaea from the Thermoplasmata Group E2 clade. We observed some overlap in community structure with nearby peatlands, which tend to be dominated by methanogens and Acidobacteria. Sediment microbial communities differed significantly between lakes, by overlying lake depth (shallow vs. deep), and by depth within a core, with each trend corresponding to parallel differences in biogeochemical measurements. Overall, our results support the potential for significant microbial controls on carbon cycling in high-latitude lakes associated with thawing permafrost, and ongoing metagenomic analyses of focal samples will yield further insight into the functional potential of these microbial communities and their dominant members.

CO(2) partial pressure and calcite saturation in springs - useful data for identifying infiltration areas in mountainous environments.

PubMed

Hilberg, Sylke; Brandstätter, Jennifer; Glück, Daniel

2013-04-01

Mountainous regions such as the Central European Alps host considerable karstified or fractured groundwater bodies, which meet many of the demands concerning drinking water supply, hydropower or agriculture. Alpine hydrogeologists are required to describe the dynamics in fractured aquifers in order to assess potential impacts of human activities on water budget and quality. Delineation of catchment areas by means of stable isotopes and hydrochemical data is a well established method in alpine hydrogeology. To achieve reliable results, time series of (at least) one year and spatial and temporal close-meshed data are necessary. In reality, test sites in mountainous regions are often inaccessible due to the danger of avalanches in winter. The aim of our work was to assess a method based on the processes within the carbonic acid system to delineate infiltration areas by means of single datasets consisting of the main hydrochemical parameters of each spring. In three geologically different mountainous environments we managed to classify the investigated springs into four groups. (1) High PCO2 combined with slight super-saturation in calcite, indicating relatively low infiltration areas. (2) Low PCO2 near atmospheric conditions in combination with calcite saturation, which is indicative of relatively high infiltration areas and a fractured aquifer which is not covered by topsoil layers. (3) High PCO2 in combination with sub-saturation in calcite, representing a shallow aquifer with a significant influence of the topsoil layer. (4) The fourth group of waters is characterized by low PCO2 and sub-saturation in calcite, which is interpreted as evidence for a shallow aquifer without significant influence of any hard rock aquifer or topsoil layer. This study shows that CO2-partial pressure can be an ideal natural tracer to estimate the elevation of infiltration areas, especially in non-karstified fractured groundwater bodies.

Development and Testing of a Scanning Differential Absorption Lidar For Carbon Sequestration Site Monitoring

NASA Astrophysics Data System (ADS)

Soukup, B.; Johnson, W.; Repasky, K. S.; Carlsten, J. L.

2013-12-01

A scanning differential absorption lidar (DIAL) instrument for carbon sequestration site monitoring is under development and testing at Montana State University. The laser transmitter uses two tunable discrete mode laser diodes (DMLD) operating in the continuous wave (cw) mode with one locked to the on-line absorption wavelength at 1571.4067 nm and the second operating at the off-line wavelength at 1571.2585 nm. Two in-line fiber optic switches are used to switch between on-line and off-line operation. After the fiber optic switches, an acousto-optic modulator (AOM) is used to generate a pulse train used to injection seed an erbium doped fiber amplifier (EDFA) to produce eye-safe laser pulses with maximum pulse energies of 66 J and a pulse repetition frequency of 15 kHz. The DIAL receiver uses a 28 cm diameter Schmidt-Cassegrain telescope to collect that backscattered light, which is then monitored using a fiber coupled photo-multiplier tube (PMT) module operating in the photon counting mode. The PMT has a 3% quantum efficiency, a dark count rate of 90 kHz, and a maximum count rate of 1 MHz. Recently, a fiber coupled avalanche photodiode (APD) operating in the geiger mode has been incorporated into the DIAL receiver. The APD has a quantum efficiency of 10%, a dark count rate of 10 kHz, and a maximum count rate of 1 MHz and provides a much larger dynamic range than the PMT. Both the PMT and APD provide TTL logic pulses that are monitored using a multichannel scaler card used to count the return photons as a function of time of flight and are thus interchangeable. The DIAL instrument was developed at the 1.571 m wavelength to take advantage of commercial-off-the-shelf components. The instrument is operated using a custom Labview program that switches to the DMLD operating at the on-line wavelength, locks this laser to a user defined wavelength setting, and collects return signals for a user defined time. The control program switches to the DMLD operating at the off-line wavelength where data is again collected for a user defined time. The control program repeats this process until stopped by the operator. The DIAL instrument has been operated at the Zero Emission Research Technology (ZERT) field site located on the Montana State University campus and at the Big Sky Carbon Sequestration Partnership site located in north-central Montana. Data collected by the DIAL instrument at both field sites demonstrate that the DIAL is capable of retrieving night time CO2 number density profiles out to a range of 2.5 km with a 150 m range resolution. The DIAL retrievals are validated using a co-located Li-COR 820 gas analyzer placed along the DIAL optical path allowing comparison at a single range as a function of time.

Rapid emergence of life shown by discovery of 3,700-million-year-old microbial structures

NASA Astrophysics Data System (ADS)

Nutman, Allen P.; Bennett, Vickie C.; Friend, Clark R. L.; van Kranendonk, Martin J.; Chivas, Allan R.

2016-09-01

Biological activity is a major factor in Earth’s chemical cycles, including facilitating CO2 sequestration and providing climate feedbacks. Thus a key question in Earth’s evolution is when did life arise and impact hydrosphere-atmosphere-lithosphere chemical cycles? Until now, evidence for the oldest life on Earth focused on debated stable isotopic signatures of 3,800-3,700 million year (Myr)-old metamorphosed sedimentary rocks and minerals from the Isua supracrustal belt (ISB), southwest Greenland. Here we report evidence for ancient life from a newly exposed outcrop of 3,700-Myr-old metacarbonate rocks in the ISB that contain 1-4-cm-high stromatolites—macroscopically layered structures produced by microbial communities. The ISB stromatolites grew in a shallow marine environment, as indicated by seawater-like rare-earth element plus yttrium trace element signatures of the metacarbonates, and by interlayered detrital sedimentary rocks with cross-lamination and storm-wave generated breccias. The ISB stromatolites predate by 220 Myr the previous most convincing and generally accepted multidisciplinary evidence for oldest life remains in the 3,480-Myr-old Dresser Formation of the Pilbara Craton, Australia. The presence of the ISB stromatolites demonstrates the establishment of shallow marine carbonate production with biotic CO2 sequestration by 3,700 million years ago (Ma), near the start of Earth’s sedimentary record. A sophistication of life by 3,700 Ma is in accord with genetic molecular clock studies placing life’s origin in the Hadean eon (>4,000 Ma).

Chemolithoautotrophy in a shallow-sea hydrothermal system, Milos Island, Greece

NASA Astrophysics Data System (ADS)

Lu, G. S.; LaRowe, D.; Gilhooly, W., III; Druschel, G. K.; Fike, D. A.; Amend, J.

2017-12-01

In recent decades, numerous (hyper)thermophilic microorganisms have been isolated from hydrothermal venting systems. Although they have been shown to have the capabilities to catalyze a wide variety of reactions to gain energy, few pure cultures have been isolated from these environments. In order to more fully understand the catabolic potential of organisms living in and near hydrothermal vents, we have calculated the Gibbs energies (ΔGr) of 730 redox reactions that could be supplying energy to organisms in the shallow-sea hydrothermal sediments of Paleochori Bay, Milos Island, Greece. This analysis required in-depth geochemical data on the pore fluids and minerals in these sediments near the vent site at several depths. The geochemical profiles of Saganaki vent show steep gradients in temperature, pH, and redox-sensitive compounds resulting from the mixing of hot ( 75oC), acidic ( pH 4), chemically reduced venting fluid with colder, slightly basic and oxidized seawater. We determined values of ΔGr for 47 sediment porewater samples along a 20cm x 2m transect for metabolic reactions involving 23 inorganic H-, O-, C-, N-, S-, Fe-, Mn-, and As- bearing compounds. 379 of the reactions considered were exergonic at one or more sampling locations. The most exergonic reactions were anaerobic CO oxidation with NO2- (136 - 162 kJ/mol e-), followed by the O2/CO, NO3-/CO, and NO2-/ H2S redox pairs. ΔGr values exhibit significant variation among sites as temperature, pH and chemical concentration vary, especially concentrations of Fe2+, Mn2+, and H2S. A great diversity of energy sources are available for microbial populations to exploit: in hotter sediments, sulfide oxidation coupled to nitrite reduction yields large amounts of energy per kg of sediment, whereas aerobic S0 oxidation is more energy-yielding in cooler areas. Our results show that at Saganaki there is a substantial amount of energy available from to microorganisms from sulfur-redox reactions. 16S rRNA pyrotag sequencing data point to diverse microbial populations at Saganaki, which is consistent with our bioenergetic profile, particularly when the thermodynamic calculations are normalized per kg of venting fluid. These data suggest a complex spatial distribution of microbial physiologies that is in good agreement with predicted energy yields.

Seismic and Gas Analyses Imply Magmatic Intrusion at Iliamna Volcano, Alaska in 2012

NASA Astrophysics Data System (ADS)

Prejean, S. G.; Werner, C. A.; Buurman, H.; Doukas, M. P.; Kelly, P. J.; Kern, C.; Ketner, D.; Stihler, S.; Thurber, C. H.; West, M. E.

2012-12-01

In early 2012, Iliamna Volcano, an ice-covered andesitic stratovolcano located in the Cook Inlet region of Alaska, had a vigorous earthquake swarm that included both brittle-failure earthquakes (M<=3.0) and smaller repeating low-frequency events. The swarm peaked in late February and early March with a maximum rate of roughly 1 event per minute. Initial earthquake locations were poor, as the normally sparse network (6 stations) was further compromised by outages. In an attempt to improve earthquake locations we linked differential travel times from this swarm to previous high-quality earthquake relocations (Statz-Boyer, et al., 2009, J. Volc. Geotherm. Res., v. 184, p. 323-332) using TomoDD. This analysis can be done quickly during unrest episodes if the optimal parameterization for the inversion and differential travel times for historical earthquakes have been determined previously. Relocated hypocenters shifted significantly westward from initial catalog locations, aligning on a ~N-S trending structure south of the volcano's edifice at 0-4 km depth. This crustal volume has otherwise been seismically quiet except during a possible magmatic intrusion at Iliamna in 1996, when it sustained a similar swarm (Roman et al., 2004, J. Volc. Geotherm. Res., v. 130, p. 265-284). Analysis of the relative amplitudes between the small low-frequency and located brittle failure events indicates that their sources are geographically separate, with the low-frequency events sourced closer to the fumarolically active summit region, ~4 km north of the brittle failure events. Airborne gas-emission measurements on March 17 revealed emission rates of up to 2000 and 580 tonnes per day (t/d) of CO2 and SO2, respectively, and a molar C/S ratio of 5. Visual observations from the flight revealed unusually vigorous fumarole activity near the summit. Subsequent measurements on June 20 and 22 showed continued high emissions of up to 1190 and 440 t/d of CO2 and SO2, respectively, with a C/S ratio of 4. These emission measurements are similar to those measured during the height of the 1996 unrest episode and are significantly above background measurements between 1998 and August 2011, which were typically below 100 and 60 t/d of CO2 and SO2. Taken together, gas and seismic data suggest that the earthquake swarm was driven by magmatic intrusion. Gas flux rates are consistent with those measured for degassing andesitic magmas in the shallow crust at other Cook Inlet volcanoes. Increased heat and degassing likely caused small low-frequency events in the shallow hydrothermal system near the volcano's summit, and/or may have destabilized the glacier, triggering shallow low-frequency glacial events. This unrest episode demonstrates how magmatic intrusions can cause spatially disparate earthquake swarms in hydrothermal systems and on pre-existing crustal structures.

Soil gas anomalies along the Watukosek fault system, East Java, Indonesia

NASA Astrophysics Data System (ADS)

Sciarra, A.; Ruggiero, L.; Bigi, S.; Mazzini, A.

2017-12-01

Two soil gas surveys were carried out in the Sidoarjo district (East Java, Indonesia) to investigate the gas leaking properties along fractured zones that coincide with a strike-slip system in NE Java, the Watukosek Fault System. This structure has been the focus of attention since the beginning of the spectacular Lusi mud eruption on the 29th May 2006. This fault system appear to be a sinistral strike-slip system that originates from the Arjuno-Welirang volcanic complex, intersects the active Lusi eruption site displaying a system of antithetic faults, and extends towards the NE of Java where mud volcanic structures reside. In the Lusi region we completed two geochemical surveys (222Rn and 220Rn activity, CO2 and CH4 flux and concentration) along four profiles crossing the Watukosek fault system. In May 2015 two profiles ( 1.2 km long) were performed inside the 7 km2 embankment area framing the erupted mud breccia zone and across regions characterized by intense fracturing and surface deformation. In April 2017 two additional profiles ( 4 km long) were carried out in the northern and southern part outside the Lusi embankment mud eruption area, intersecting the direction of main Watukosek fault system. All the profiles highlight that the fractured zones have the highest 222Rn activity, CO2 and CH4 flux and concentration values. The relationship existing among the measured parameters suggest that the Watukosek fault system acts as a preferential pathway for active rise of deep fluids. In addition the longer profiles outside the embankment show very high average values of CO2 (5 - 8 %,v/v) and 222Rn (17 - 11.5 kBq/m3), while soil gas collected along the profiles inside the Lusi mud eruption are CH4-dominant (up to 4.5%,v/v).This suggests that inside the embankment area (i.e. covered by tens of meters thick deposits of erupted mud breccia) the seepage is overall methane-dominated. This is likely the result of microbial reactions ongoing in the organic-rich sediments producing shallow gas that gets mixed with deeper rising fluids. In contrasts profiles collected in areas not covered by the organic rich mud breccia, and that are crossing the main Watukosek fault system, have the highest 222Rn activity and CO2 concentration values. We suggest that at these localities the rise of deep fluids is not affected by shallower gas production.

Multi-isotope tracing of CO2 leakage and water-rock interaction in a natural CCS analogue.

NASA Astrophysics Data System (ADS)

Kloppmann, Wolfram; Gemeni, Vasiliki; Lions, Julie; Koukouzas, Nikolaos; Humez, Pauline; Vasilatos, Charalampos; Millot, Romain; Pauwels, Hélène

2015-04-01

Natural analogues of CO2 accumulation and, potentially, leakage, provide a highly valuable opportunity to study (1) geochemical processes within a CO2-reservoir and the overlying aquifers or aquicludes, i.e. gas-water-rock interactions, (2) geology and tightness of reservoirs over geological timescales, (3) potential or real leakage pathways, (3) impact of leakage on shallow groundwater resources quality, and (4) direct and indirect geochemical indicators of gas leakage (Lions et al., 2014, Humez et al., 2014). The Florina Basin in NW Macedonia, Greece, contains a deep CO2-rich aquifer within a graben structure. The graben filling consists of highly heterogeneous Neogene clastic sediments constituted by components from the adjacent massifs including carbonates, schists, gneiss as well as some ultramafic volcanic rocks. Clay layers are observed that isolate hydraulically the deep, partly artesian aquifer. Organic matter, in form of lignite accumulations, is abundant in the Neogene series. The underlying bedrocks are metamorphic carbonates and silicate rocks. The origin of the CO2 accumulation is controversial (deep, partially mantle-derived D'Allessandro et al., 2008 or resulting from thermal decomposition of carbonates, Hatziyannis and Arvanitis, 2011). Groundwaters have been sampled from springs and borewells over 3 years at different depths. First results on major, minor and trace elements give evidence of water-rock interaction, mainly with carbonates but also with ultramafic components but do not indicate that CO2-seepage is the principal driver of those processes (Gemeni et al., submitted). Here we present isotope data on a selection of groundwaters (δ2H , δ18O, δ13CTDIC, 87Sr/86Sr, δ11B, δ7Li). Stable isotopes of water indicate paleo-recharge for some of the groundwaters, limited exchange with gaseous CO2 and, in one case, possibly thermal exchange processes with silicates. Sr isotope ratios vary between marine ratios and radiogenic values indicating interaction with carbonates and silicates. Both δ11B and δ7Li show a very large range of variation and fairly good correlation, between -29.7 o and +24o vs. NBS951 for boron and -11o and +20.4o vs. L-SVEC for lithium. The negative δ11B and δ7Li values are among the lowest reported in literature for groundwaters, comparable only to values observed for boron in case of geothermal fluids interaction with clay minerals (Pennisi et al., 2009) or in some amphiboles (e.g. Gillis et al., 2003) or lithium in ultramafic rocks (Nishio et al., 2004). Those variations reflect water-rock interaction with the silicate fraction of the highly heterogeneous graben filling but no clear indication of enhanced reactions due to CO2 intrusion has been found. The δ13C values of TDIC are also strongly variable (-10.5 to +15 o vs. PDB), reflecting biogenic inputs (e.g. from lignite layers), dissolution of carbonates and, potentially, methanogenesis through CO2 reduction. D' Alessandro W., Bellomo S., Brusca L., Karakazanis S., Kyriakopoulos K., and Liotta M. (2011) The impact on water quality of the high carbon dioxide contents of the groundwater in the area of Florina (N. Greece), Advances in the Research of Aquatic Environment. Springer. Gillis K. M., Coogan L. A., and Chaussidon M. (2003) Volatile element (B, Cl, F) behaviour in the roof of an axial magma chamber from the East Pacific Rise. Earth and Planetary Science Letters 213, 447-462. Hatziyannis G. and Arvanitits A. (2011) Natural analogues of CO2 leakage in Florina area, N. Greece., 2nd CGS Europe Knowledge Sharing Workshop Natural Analogues, Maria Laach, Germany, October 17-19, 2011, pp. Humez P., Negrel P., Lagneau V., Lions J., Kloppmann W., Gal F., Millot R., Guerrot C., Flehoc C., Widory D., and Girard J. F. (2014) CO2-water-mineral reactions during CO2 leakage: Geochemical and isotopic monitoring of a CO2 injection field test. Chem. Geol. 368, 11-30. Lions J., Humez P., Pauwels H., Kloppmann W., and Czernichowski-Lauriol I. (2014) Tracking leakage from a natural CO2 reservoir (Montmiral, France) through the chemistry and isotope signatures of shallow groundwater. Greenhouse Gases-Science and Technology 4, 225-243. Pennisi M., Bianchini G., Kloppmann W., and Muti A. (2009) Chemical and isotopic (B, Sr) composition of alluvial sediments as archive of a past hydrothermal outflow. Chem. Geol. 266, 123-134. Gemeni V., Vasilatos C., Koukouzas N., Kanellopoulos C. (submitted) Factors controlling the chemistry of the groundwater in a CO2 natural field: The case of Florina Basin, W. Macedonia, Greece. Submitted to Appl. Geochem.

Developing a Comprehensive Risk Assessment Framework for Geological Storage CO 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duncan, Ian

2014-08-31

The operational risks for CCS projects include: risks of capturing, compressing, transporting and injecting CO₂; risks of well blowouts; risk that CO 2 will leak into shallow aquifers and contaminate potable water; and risk that sequestered CO 2 will leak into the atmosphere. This report examines these risks by using information on the risks associated with analogue activities such as CO 2 based enhanced oil recovery (CO 2-EOR), natural gas storage and acid gas disposal. We have developed a new analysis of pipeline risk based on Bayesian statistical analysis. Bayesian theory probabilities may describe states of partial knowledge, even perhapsmore » those related to non-repeatable events. The Bayesian approach enables both utilizing existing data and at the same time having the capability to adsorb new information thus to lower uncertainty in our understanding of complex systems. Incident rates for both natural gas and CO 2 pipelines have been widely used in papers and reports on risk of CO 2 pipelines as proxies for the individual risk created by such pipelines. Published risk studies of CO 2 pipelines suggest that the individual risk associated with CO2 pipelines is between 10 -3 and 10 -4, which reflects risk levels approaching those of mountain climbing, which many would find unacceptably high. This report concludes, based on a careful analysis of natural gas pipeline failures, suggests that the individual risk of CO 2 pipelines is likely in the range of 10-6 to 10-7, a risk range considered in the acceptable to negligible range in most countries. If, as is commonly thought, pipelines represent the highest risk component of CCS outside of the capture plant, then this conclusion suggests that most (if not all) previous quantitative- risk assessments of components of CCS may be orders of magnitude to high. The potential lethality of unexpected CO 2 releases from pipelines or wells are arguably the highest risk aspects of CO 2 enhanced oil recovery (CO2-EOR), carbon capture, and storage (CCS). Assertions in the CCS literature, that CO 2 levels of 10% for ten minutes, or 20 to 30% for a few minutes are lethal to humans, are not supported by the available evidence. The results of published experiments with animals exposed to CO 2, from mice to monkeys, at both normal and depleted oxygen levels, suggest that lethal levels of CO 2 toxicity are in the range 50 to 60%. These experiments demonstrate that CO 2 does not kill by asphyxia, but rather is toxic at high concentrations. It is concluded that quantitative risk assessments of CCS have overestimated the risk of fatalities by using values of lethality a factor two to six lower than the values estimated in this paper. In many dispersion models of CO 2 releases from pipelines, no fatalities would be predicted if appropriate levels of lethality for CO 2 had been used in the analysis.« less

Spatial variability of greenhouse gases emissions (CO2, CH4, N2O) in a tropical hydroelectric reservoir flooding primary forest (Petit Saut Reservoir, French Guiana)

NASA Astrophysics Data System (ADS)

Cailleaud, Emilie; Guérin, Frédéric; Bouillon, Steven; Sarrazin, Max; Serça, Dominique

2014-05-01

At the Petit Saut Reservoir (PSR, French Guiana, South America), vertical profiles were performed at 5 stations in the open waters (OW) and 6 stations in two shallow flooded forest (FF) areas between April 2012 and September 2013. Measurements included physico-chemical parameters, ammonium, nitrate and dissolved greenhouse gas (CO2, CH4, N2O) concentrations, dissolved and particulate organic carbon (DOC, POC) and nitrogen (PN), δ13C-POC and δ15N-PN . The diffusive fluxes were calculated from surface concentrations. The aim of this study was to estimate the spatial variations of greenhouse gas emissions at a dentrical hydroelectric reservoir located in the tropics and flooding primary forest. Twenty years after impoundment, the water column of the PSR is permanently and tightly stratified thermally in the FF whereas in the OW, the thermal gradients are not as stable. The different hydrodynamical behaviours between the two different zones have significant consequences on the biogeochemistry: oxygen barely diffuses down to the hypolimnion in the FF whereas destratification occurs sporadically during the rainy season in the OW. Although we found the same range of POC in the FF and the OW (2.5-29 μmol L-1) and 20% more DOC at the bottom of OW than in the FF (229-878 μmol L-1), CO2 and CH4 concentrations were always significantly higher in the FF (CO2: 11-1412 μmol L-1, CH4: 0.001-1015 μmol L-1) than in the OW. On average, the CO2 concentrations were 30-40% higher in the FF than in the OW and the CH4 concentrations were three times higher in the FF than in the OW. The δ13C-POC and C:N values did not suggest substantial differences in the sources of OM between the FF and OW. At all stations, POC at the bottom has an isotopic signature slightly lighter than the terrestrial OM in the surrounding forest whereas the isotopic signature of surface POM would result from phytoplankton and methanotrophs. The vertical profiles of nitrogen compounds reveal that the main source of nitrogen in the water column of the PSR is the NH4+ produced during the mineralisation of the OM at the bottom of the reservoir. In OW, the production of NO3- and N2O is enhanced compared to the FF. As a result, N2O concentrations are three times higher at the bottom of OW but surface concentrations are similar in the FF and OW. CO2 diffusive fluxes are 40% higher and CH4 diffusive fluxes are three times higher in FF (CO2: 42±20 mmol m-2 d-1 ; CH4: 0.7±1.4 mmol m-2 d-1) than in OW (CO2: 27±17 mmol m-2 d-1 ; CH4: 0.2±0.3 mmol m-2 d-1). In shallow FF, average CH4 ebullition is 3±10 mmol m-2 d-1 whereas ebullition was never observed in OW. N2O emissions did not exhibit any spatial variability (9±4 μmol m-2 d-1). At the PSR, FF which represents one third of the surface area, is responsible of half of the GHG emissions from the reservoir. This implies that the emissions from most of the tropical reservoirs flooding primary forest need to be reassessed since FF environments are usually overlooked.

Variations in coal characteristics and their possible implications for CO2 sequestration: Tanquary injection site, southeastern Illinois, USA

USGS Publications Warehouse

Morse, D.G.; Mastalerz, Maria; Drobniak, A.; Rupp, J.A.; Harpalani, S.

2010-01-01

As part of the U.S. Department of Energy's Regional Sequestration Partnership program, the potential for sequestering CO2 in the largest bituminous coal reserve in United States - the Illinois Basin - is being assessed at the Tanquary site in Wabash County, southeastern Illinois. To accomplish the main project objectives, which are to determine CO2 injection rates and storage capacity, we developed a detailed coal characterization program. The targeted Springfield Coal occurs at 274m (900ft) depth, is 2.1m (7ft) thick, and is of high volatile B bituminous rank, having an average vitrinite reflectance (Ro) of 0.63%. Desorbed Springfield Coal gas content in cores from four wells ~15 to ~30m (50 to 100ft) apart varies from 4.7-6.6cm3/g (150 to 210scf/ton, dmmf) and consists, generally, of >92% CH4 with lesser amounts of N2 and then CO2. Adsorption isotherms indicate that at least three molecules of CO2 can be stored for each displaced CH4 molecule. Whole seam petrographic composition, which affects sequestration potential, averages 76.5% vitrinite, 4.2% liptinite, 11.6% inertinite, and 7.7% mineral matter. Sulfur content averages 1.59%. Well-developed coal cleats with 1 to 2cm spacing contain partial calcite and/or kaolinite fillings that may decrease coal permeability. The shallow geophysical induction log curves show much higher resistivity in the lower part of the Springfield Coal than the medium or deep curves because of invasion by freshwater drilling fluid, possibly indicating higher permeability. Gamma-ray and bulk density vary, reflecting differences in maceral, ash, and pyrite content. Because coal properties vary across the basin, it is critical to characterize injection site coals to best predict the potential for CO2 injection and storage capacity. ?? 2010 Elsevier B.V.

Assessment of acidification and eutrophication in the coastal waters of Bolinao, Pangasinan, Philippines

NASA Astrophysics Data System (ADS)

Lagumen, M. C. T.; San Diego-McGlone, M. L.

2014-12-01

Ocean acidification is becoming a global concern due to its potential effects on marine resources. In coastal areas, an emerging problem is ocean acidicification due to eutrophication resulting from human activities. The coastal water of Bolinao, Pangasinan, Philippines has become eutrophic due to increased nutrient loading from unconsumed fish feeds in fish cages. Mariculture is a big industry in Bolinao. In over a decade, the area has experienced decreased oxygen levels leading to hypoxia, fish kills, and algal blooms. The decomposition of organic matter from unconsumed fish feeds results not only to high nutrient buildup but also increased CO2 and acidity in the area. Nutrients (ammonia, nitrate, nitrite, phosphate and silicate), total alkalinity (TA), dissolved inorganic carbon (DIC), pH, dissolved oxygen (DO), aragonite saturation state (Ωarg) and partial pressure of carbon dioxide (pCO2) were measured to determine the combined effect of acidification and eutrophication in Bolinao. Monitoring results have shown an increase in nutrients by 30% to 70% in over a decade. Stratified water during rainy season have resulted in low DO (<5.5) and acidic water (<7.5) with high pCO2 level (>900 μatm). Shallow stations with poor water circulation have shown undersaturated aragonite state (< 2.0) and high pCO2 levels of 800 matm. The eutrophic and acidified coastal waters of Bolinao are already affecting the seagrass and coral reef ecosystems in the area.

Carbon dioxide degassing at the groundwater-stream-atmosphere interface: isotopic equilibration and hydrological mass balance in a sandy watershed

NASA Astrophysics Data System (ADS)

Deirmendjian, Loris; Abril, Gwenaël

2018-03-01

Streams and rivers emit significant amounts of CO2 and constitute a preferential pathway of carbon transport from terrestrial ecosystems to the atmosphere. However, the estimation of CO2 degassing based on the water-air CO2 gradient, gas transfer velocity and stream surface area is subject to large uncertainties. Furthermore, the stable isotope signature of dissolved inorganic carbon (δ13C-DIC) in streams is strongly impacted by gas exchange, which makes it a useful tracer of CO2 degassing under specific conditions. For this study, we characterized the annual transfers of dissolved inorganic carbon (DIC) along the groundwater-stream-river continuum based on DIC concentrations, stable isotope composition and measurements of stream discharges. We selected a homogeneous, forested and sandy lowland watershed as a study site, where the hydrology occurs almost exclusively through drainage of shallow groundwater (no surface runoff). We observed the first general spatial pattern of decreases in pCO2 and DIC and an increase in δ13C-DIC from groundwater to stream orders 1 and 2, which was due to the experimentally verified faster degassing of groundwater 12C-DIC compared to 13C-DIC. This downstream enrichment in 13C-DIC could be modelled by simply considering the isotopic equilibration of groundwater-derived DIC with the atmosphere during CO2 degassing. A second spatial pattern occurred between stream orders 2 and 4, consisting of an increase in the proportion of carbonate alkalinity to the DIC accompanied by the enrichment of 13C in the stream DIC, which was due to the occurrence of carbonate rock weathering downstream. We could separate the contribution of these two processes (gas exchange and carbonate weathering) in the stable isotope budget of the river network. Thereafter, we built a hydrological mass balance based on drainages and the relative contribution of groundwater in streams of increasing order. After combining with the dissolved CO2 concentrations, we quantified CO2 degassing for each stream order for the whole watershed. Approximately 75% of the total CO2 degassing from the watershed occurred in first- and second-order streams. Furthermore, from stream order 2-4, our CO2 degassing fluxes compared well with those based on stream hydraulic geometry, water pCO2, gas transfer velocity, and stream surface area. In first-order streams, however, our approach showed CO2 fluxes that were twice as large, suggesting that a fraction of degassing occurred as hotspots in the vicinity of groundwater resurgence and was missed by conventional stream sampling.

Preliminary Modelling of the Effect of Impurity in CO2 Streams on the Storage Capacity and the Plume Migration in Pohang Basin, Korea

NASA Astrophysics Data System (ADS)

Park, Yongchan; Choi, Byoungyoung; Shinn, Youngjae

2015-04-01

Captured CO2 streams contain various levels of impurities which vary depending on the combustion technology and CO2 sources such as a power plant and iron and steel production processes. Common impurities or contaminants are non-condensable gases like nitrogen, oxygen and hydrogen, and are also air pollutants like sulphur and nitrogen oxides. Specifically for geological storage, the non-condensable gases in CO2 streams are not favourable because they can decrease density of the injected CO2 stream and can affect buoyancy of the plume. However, separation of these impurities to obtain the CO2 purity higher than 99% would greatly increase the cost of capture. In 2010, the Korean Government announced a national framework to develop CCS, with the aim of developing two large scale integrated CCS projects by 2020. In order to achieve this goal, a small scale injection project into Pohang basin near shoreline has begun which is seeking the connection with a capture project, especially at a steel company. Any onshore sites that are suitable for the geological storage are not identified by this time so we turned to the shallow offshore Pohang basin where is close to a large-scale CO2 source. Currently, detailed site surveys are being undertaken and the collected data were used to establish a geological model of the basin. In this study, we performed preliminary modelling study on the effect of impurities on the geological storage using the geological model. Using a potential compositions of impurities in CO2 streams from the steel company, we firstly calculated density and viscosity of CO2 streams as a function of various pressure and temperature conditions with CMG-WINPROP and then investigated the effect of the non-condensable gases on storage capacity, injectivity and plume migrations with CMG-GEM. Further simulations to evaluate the areal and vertical sweep efficiencies by impurities were perform in a 2D vertical cross section as well as in a 3D simulation grid. Also, pressure increases caused by the impurities and the partitioning between CO2 and other non-condensable gases were explored. In addition, the possibility of using these contaminants as a tracer were examined.

Final Scientific/Technical Report for project “Geomechanical Monitoring for CO 2 Hub Storage: Production and Injection at Kevin Dome

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daley, Thomas M.; Vasco, Don; Ajo-Franklin, Jonathan

After learning that the TDS value in the target injection formation at the Kevin Dome site is too low to qualify for an EPA Class VI CO2 injection permit, the BSCSP project was re-scoped such that injection of CO2 is no longer planned. With no injection planned, the Geomechanics project was closed. In this final report, we describe the objective and approach of the project as proposed, and the limited results obtained before stopping work. The objective of the proposed research was the development & validation of an integrated monitoring approach for quantifying the interactions between large-scale geological carbon storagemore » (GCS) and subsurface geomechanical state, particularly perturbations relevant to reservoir integrity such as fault reactivation and induced fracturing. In the short period of work before knowing the fate of the Kevin Dome project, we (1) researched designs for both the proposed InSAR corner reflectors as well as the near-surface 3C seismic stations; (2) developed preliminary elastic geomechanical models; (3) developed a second generation deformation prediction for the BSCSP Kevin Dome injection site; and (4) completed a preliminary map of InSAR monuments and shallow MEQ wells in the vicinity of the BSCSP injection pad.« less

The AT-LESS CO(1-0) survey of submillimetre galaxies in the Extended Chandra Deep Field South: First results on cold molecular gas in galaxies at z ˜ 2

NASA Astrophysics Data System (ADS)

Huynh, Minh T.; Emonts, B. H. C.; Kimball, A. E.; Seymour, N.; Smail, Ian; Swinbank, A. M.; Brandt, W. N.; Casey, C. M.; Chapman, S. C.; Dannerbauer, H.; Hodge, J. A.; Ivison, R. J.; Schinnerer, E.; Thomson, A. P.; van der Werf, P.; Wardlow, J. L.

2017-05-01

We present the first results from our ongoing Australia Telescope Compact Array survey of 12CO(1-0) in Atacama Large Millimeter Array (ALMA)-identified submillimetre galaxies (SMGs) in the Extended Chandra Deep Field South. Strong detections of 12CO(1-0) emission from two SMGs, ALESS 122.1 (z = 2.0232) and ALESS 67.1 (z = 2.1230), were obtained. We estimate gas masses of Mgas ˜ 1.3 × 1011 M⊙ and Mgas ˜ 1.0 × 1011 M⊙ for ALESS 122.1 and ALESS 67.1, respectively, adopting αCO = 1.0. Dynamical mass estimates from the kinematics of the 12CO(1-0) line yields Mdyn sin2 I = (2.1 ± 1.1) × 1011 M⊙ and (3.2 ± 0.9) × 1011 M⊙ for ALESS 122.1 and ALESS 67.1, respectively. This is consistent with the total baryonic mass estimates of these two systems. We examine star formation efficiency, using the LFIR versus L^' }_{CO(1-0)} relation for samples of local ultraluminous infrared galaxies (ULIRGs) and Luminous Infrared Galaxies (LIRGs), and more distant star-forming galaxies, with 12CO(1-0) detections. We find some evidence of a shallower slope for ULIRGs and SMGs compared to less luminous systems, but a larger sample is required for definite conclusions. We determine gas-to-dust ratios of 170 ± 30 and 140 ± 30 for ALESS 122.1 and ALESS 67.1, respectively, showing that ALESS 122.1 has an unusually large gas reservoir. By combining the 38.1 GHz continuum detection of ALESS 122.1 with 1.4 and 5.5 GHz data, we estimate that the free-free contribution to radio emission at 38.1 GHz is 34 ± 17 μJy, yielding a star formation rate (1400 ± 700 M⊙ yr-1) consistent with that from the infrared luminosity.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kashgarian, M; Guilderson, T P

We utilize monthly {sup 14}C data derived from coral archives in conjunction with ocean circulation models to address two questions: (1) how does the shallow circulation of the tropical Pacific vary on seasonal to decadal time scales and (2) which dynamic processes determine the mean vertical structure of the equatorial Pacific thermocline. Our results directly impact the understanding of global climate events such as the El Nino-Southern Oscillation (ENSO). To study changes in ocean circulation and water mass distribution involved in the genesis and evolution of ENSO and decadal climate variability, it is necessary to have records of climate variablesmore » several decades in length. Continuous instrumental records are limited because technology for continuous monitoring of ocean currents (e.g. satellites and moored arrays) has only recently been available, and ships of opportunity archives such as COADS contain large spatial and temporal biases. In addition, temperature and salinity in surface waters are not conservative and thus can not be independently relied upon to trace water masses, reducing the utility of historical observations. Radiocarbon in sea water is a quasi-conservative water mass tracer and is incorporated into coral skeletal material, thus coral {sup 14}C records can be used to reconstruct changes in shallow circulation that would be difficult to characterize using instrumental data. High resolution {Delta}{sup 14}C timeseries such as ours, provide a powerful constraint on the rate of surface ocean mixing and hold great promise to augment one time oceanographic surveys. {Delta}{sup 14}C timeseries such as these, not only provide fundamental information about the shallow circulation of the Pacific, but can also be directly used as a benchmark for the next generation of high resolution ocean models used in prognosticating climate. The measurement of {Delta}{sup 14}C in biological archives such as tree rings and coral growth bands is a direct record of the invasion of fossil fuel CO{sub 2} and bomb {sup 14}C into the atmosphere and surface oceans. Therefore the {Delta}{sup 14}C data that are produced in this study can be used to validate the ocean uptake of fossil fuel CO2 in coupled ocean-atmosphere models. This study takes advantage of the quasi-conservative nature of {sup 14}C as a water mass tracer by using {Delta}{sup 14}C time series in corals to identify changes in the shallow circulation of the Pacific. Although the data itself provides fundamental information on surface water mass movement the true strength is a combined approach which is greater than the individual parts; the data helps uncover deficiencies in ocean circulation models and the model results place long {Delta}{sup 14}C time series in a dynamic framework which helps to identify those locations where additional observations are most needed.« less

Modeling CO 2 emissions from Arctic lakes: Model development and site-level study

DOE PAGES

Tan, Zeli; Zhuang, Qianlai; Shurpali, Narasinha J.; ...

2017-09-14

Recent studies indicated that Arctic lakes play an important role in receiving, processing, and storing organic carbon exported from terrestrial ecosystems. To quantify the contribution of Arctic lakes to the global carbon cycle, we developed a one-dimensional process-based Arctic Lake Biogeochemistry Model (ALBM) that explicitly simulates the dynamics of organic and inorganic carbon in Arctic lakes. By realistically modeling water mixing, carbon biogeochemistry, and permafrost carbon loading, the model can reproduce the seasonal variability of CO 2 fluxes from the study Arctic lakes. The simulated area-weighted CO 2 fluxes from yedoma thermokarst lakes, nonyedoma thermokarst lakes, and glacial lakes aremore » 29.5, 13.0, and 21.4 g C m -2 yr -1, respectively, close to the observed values (31.2, 17.2, and 16.5 ± 7.7 g C m -2 yr -1, respectively). The simulations show that the high CO 2 fluxes from yedoma thermokarst lakes are stimulated by the biomineralization of mobilized labile organic carbon from thawing yedoma permafrost. The simulations also imply that the relative contribution of glacial lakes to the global carbon cycle could be the largest because of their much larger surface area and high biomineralization and carbon loading. According to the model, sunlight-induced organic carbon degradation is more important for shallow nonyedoma thermokarst lakes but its overall contribution to the global carbon cycle could be limited. Overall, the ALBM can simulate the whole-lake carbon balance of Arctic lakes, a difficult task for field and laboratory experiments and other biogeochemistry models.« less

Chemical and stable isotopic composition of water and gas in the Fort Union Formation of the Powder River Basin, Wyoming and Montana: Evidence for water/rock interaction and the biogenic origin of coalbed natural gas

USGS Publications Warehouse

Rice, Cynthia A.; Flores, Romeo M.; Stricker, Gary D.; Ellis, Margaret S.

2008-01-01

Significant amounts (> 36 million m3/day) of coalbed methane (CBM) are currently being extracted from coal beds in the Paleocene Fort Union Formation of the Powder River Basin of Wyoming and Montana. Information on processes that generate methane in these coalbed reservoirs is important for developing methods that will stimulate additional production. The chemical and isotopic compositions of gas and ground water from CBM wells throughout the basin reflect generation processes as well as those that affect water/rock interaction. Our study included analyses of water samples collected from 228 CBM wells. Major cations and anions were measured for all samples, δDH2O and δ18OH2O were measured for 199 of the samples, and δDCH4 of gas co-produced with water was measured for 100 of the samples. Results show that (1) water from Fort Union Formation coal beds is exclusively Na–HCO3-type water with low dissolved SO4 content (median < 1 mg/L) and little or no dissolved oxygen (< 0.15 mg/L), whereas shallow groundwater (depth generally < 120 m) is a mixed Ca–Mg–Na–SO4–HCO3 type; (2) water/rock interactions, such as cation exchange on clay minerals and precipitation/dissolution of CaCO3 and SO4 minerals, account for the accumulation of dissolved Na and depletion of Ca and Mg; (3) bacterially-mediated oxidation–reduction reactions account for high HCO3 (270–3310 mg/L) and low SO4 (median < 0.15 mg/L) values; (4) fractionation between δDCH4 (− 283 to − 328 per mil) and δDH2O (− 121 to − 167 per mil) indicates that the production of methane is primarily by biogenic CO2 reduction; and (5) values of δDH2O and δ18OH2O (− 16 to − 22 per mil) have a wide range of values and plot near or above the global meteoric water line, indicating that the original meteoric water has been influenced by methanogenesis and by being mixed with surface and shallow groundwater.

The Effect of Aging on the Ventilatory Response to Wearing a Chemical, Biological, Radiological, and Nuclear Hood Respirator at Rest and During Mild Exercise.

PubMed

Ofir, Dror; Yanir, Yoav; Eynan, Mirit; Aviner, Ben; Biram, Adi; Mullokandov, Michael; Bar, Ronen; Arieli, Yehuda

2017-01-01

Structural changes in the human body resulting from aging may affect the response to altered levels of O 2 and CO 2 . An abnormal ventilatory response to a buildup of CO 2 in the inspired air due to rebreathing may result in adverse effects, which will impair the individual's ability to function under stress. The purpose of this study was to evaluate the effect of age on the respiratory response to wearing an escape hood at rest and during mild exercise. Subjects were seven healthy, young adult males (20-30 years) and seven healthy, middle-aged males (45-65 years). Inspired CO 2 and O 2 , breathing pattern (tidal volume [V T ] and breathing frequency [F]), and mouth inspiratory and expiratory pressures, were measured at rest and during mild exercise (50 w) while wearing the CAPS 2000 escape hood (Shalon Chemical Industries and Supergum-Rubber and Plastic Technology, Tel Aviv, Israel). Resting inspired CO 2 was higher in the middle-aged group compared with the young group (2.25% ± 0.42% and 1.80% ± 0.34%, respectively; p < 0.05). Breathing pattern in the middle-aged group tended to be shallower and faster compared with the young group (V T : 0.69 ± 0.27 L and 0.79 ± 0.32 L, respectively; F: 14.7 ± 4.0 breaths/min and 12.4 ± 2.8 breaths/min, respectively). During exercise, there was a trend toward a high inspired CO 2 in the middle-aged group compared with the young group (2.18% ± 0.40% CO 2 and 1.94% ± 0.70% CO 2 , respectively). A correlation was found between age and inspired CO 2 when wearing the escape hood (r 2 = 0.375; p < 0.05). The age-related decrease in pulmonary function, together with the finding in this study of a higher inspired CO 2 in middle-aged subjects wearing the CAPS 2000, may represent a greater risk for persons of middle age wearing an escape hood. On the basis of this study, it would appear reasonable to recommend that new respirators be evaluated on subjects from different age groups, to ensure the safety of both young and old. Reprint & Copyright © 2017 Association of Military Surgeons of the U.S.

Variable mixing and degassing of mantle CO2 within continental subsurface water bodies evidenced by compared gas geochemistry and fluid-phase equilibrium modeling

NASA Astrophysics Data System (ADS)

Virgile, R.

2016-12-01

The continental degassing of mantle volatiles is known from a variety of areas characterized by Asthenosphere updoming, such as the US Basin and Range and the European Cenozoic Rift System. Mantle degassing is there usually associated to magmatic provinces where non-volcanic upwellings of cold to hot waters are frequently associated with high CO2 gas loads. The resulting aquifers, springs and mofets express variable gas compositions which are often attributed to the mixing of crustal and mantle CO2, and less often to the variable degassing states of the waters. Indeed, the compositions of water and gas in CO2, δ13C and the noble gases may justify both models. However, the implications of each model for the bulk degassing mass quantification of mantle volatiles are drastically different, and would therefore need to be confirmed or rejected on a case by case basis. We introduce here a new model for predicting fluid phase equilibrium for systems comprising CO2-CH4-H2-H2S-N2-O2-He-Ne-Ar-Kr-Xe-H2O-NaCl at shallow subsurface conditions (1-250 bars, 0-150°C). The model was applied in P-T conditions comparable to non-volcanic CO2 degassing systems, where initial fluids were defined as variable mixtures of air equilibrated water (AEW) and mantle volatiles (CO2, He, CO2/3He = 5 x109). Literature data from European non-volcanic mantle degassing systems were compiled and compared to different modeling scenarios. The distribution of the CO2/3He (from 108 to 1012) and N2/3He (from 106 to 1011) ratios in natural samples are consistent with the open system degassing of initial fluids at depths above 2000m, with variable recharges of AEW. Initial single phase fluids are composed of up to 300 mol.m-3 CO2, 7 x10-3 mol.m-3 He and N2 with typical AEW contents (0.5 mol.m-3). Most degassed systems correspond to 98% degassed initial fluids, which incorporated up to 10% of fresh AEW subsequently to degassing. Our results suggest that fluid phase fractionation effects alone are sufficient to generate the range of compositions observed in the studied natural water-gas systems, without the need to invoke a crustal CO2 end-member.