Sample records for abiotic co2 flows

  1. Abiotic CO2 reduction during geologic carbon sequestration facilitated by Fe(II)-bearing minerals

    NASA Astrophysics Data System (ADS)

    Nielsen, L. C.; Maher, K.; Bird, D. K.; Brown, G. E.; Thomas, B.; Johnson, N. C.; Rosenbauer, R. J.

    2012-12-01

    Redox reactions involving subsurface minerals and fluids and can lead to the abiotic generation of hydrocarbons from CO2 under certain conditions. Depleted oil reservoirs and saline aquifers targeted for geologic carbon sequestration (GCS) can contain significant quantities of minerals such as ferrous chlorite, which could facilitate the abiotic reduction of carbon dioxide to n-carboxylic acids, hydrocarbons, and amorphous carbon (C0). If such reactions occur, the injection of supercritical CO2 (scCO2) could significantly alter the oxidation state of the reservoir and cause extensive reorganization of the stable mineral assemblage via dissolution and reprecipitation reactions. Naturally occurring iron oxide minerals such as magnetite are known to catalyze CO2 reduction, resulting in the synthesis of organic compounds. Magnetite is thermodynamically stable in Fe(II) chlorite-bearing mineral assemblages typical of some reservoir formations. Thermodynamic calculations demonstrate that GCS reservoirs buffered by the chlorite-kaolinite-carbonate(siderite/magnesite)-quartz assemblage favor the reduction of CO2 to n-carboxylic acids, hydrocarbons, and C0, although the extent of abiotic CO2 reduction may be kinetically limited. To investigate the rates of abiotic CO2 reduction in the presence of magnetite, we performed batch abiotic CO2 reduction experiments using a Dickson-type rocking hydrothermal apparatus at temperatures (373 K) and pressures (100 bar) within the range of conditions relevant to GCS. Blank experiments containing CO2 and H2 were used to rule out the possibility of catalytic activity of the experimental apparatus. Reaction of brine-suspended magnetite nanoparticles with scCO2 at H2 partial pressures typical of reservoir rocks - up to 100 and 0.1 bars respectively - was used to investigate the kinetics of magnetite-catalyzed abiotic CO2 reduction. Later experiments introducing ferrous chlorite (ripidolite) were carried out to determine the potential for

  2. Role of Biotic and Abiotic Processes on Soil CO2 Dynamics in the McMurdo Dry Valleys, Antarctica

    NASA Astrophysics Data System (ADS)

    Risk, D. A.; Macintyre, C. M.; Lee, C.; Cary, C.; Shanhun, F.; Almond, P. C.

    2016-12-01

    In the harsh conditions of the Antarctic Dry Valleys, microbial activity has been recorded via measurements of soil carbon dioxide (CO2) concentration and surface efflux. However, high temporal resolution studies in the Dry Valleys have also shown that abiotic solubility-driven processes can strongly influence (and perhaps even dominate) the CO2 dynamics in these low flux environments and suggests that biological activity may be lower than previously thought. In this study, we aim to improve our understanding of CO2 dynamics (biotic and abiotic) in Antarctic Dry Valley soils using long-term automated measurements of soil CO2 surface flux and soil profile concentration at several sites, often at sub-diel frequency. We hypothesize that soil CO2 variations are driven primarily by environmental factors affecting CO2 solubility in soil solution, mainly temperature, and that these processes may even overprint biologic production in representative Dry Valley soils. Monitoring of all sites revealed only one likely biotic CO2 production event, lasting three weeks during the Austral summer and reaching fluxes of 0.4 µmol/m2/s. Under more typical low flux conditions (<0.10 µmol/m2/s) we observed a cyclical daily sink/source pattern consistent with CO2 solubility cycling that would not generally have been evident with normal synoptic afternoon sampling campaigns. Subsurface CO2 monitoring and a lab-controlled Antarctic soil simulation experiment confirmed that abiotic processes are capable of dominating soil CO2 variability. Diel temperature cycles crossing the freezing boundary revealed a dual abiotic cycle of solubility cycling and gas exclusion from ice formation observed only by high temporal frequency measurements (30 min). This work demonstrates a need for a numerical model to partition the dynamic abiotic processes underlying any biotic CO2 production in order to understand potential climate-change induced increases in microbial productivity in terrestrial Antarctica.

  3. Biotic and abiotic effects on CO2 sequestration during microbially-induced calcium carbonate precipitation.

    PubMed

    Okyay, Tugba Onal; Rodrigues, Debora F

    2015-03-01

    In this study, CO2 sequestration was investigated through the microbially-induced calcium carbonate precipitation (MICP) process with isolates obtained from a cave called 'Cave Without A Name' (Boerne, TX, USA) and the Pamukkale travertines (Denizli, Turkey). The majority of the bacterial isolates obtained from these habitats belonged to the genera Sporosarcina, Brevundimonas, Sphingobacterium and Acinetobacter. The isolates were investigated for their capability to precipitate calcium carbonate and sequester CO2. Biotic and abiotic effects of CO2 sequestration during MICP were also investigated. In the biotic effect, we observed that the rate and concentration of CO2 sequestered was dependent on the species or strains. The main abiotic factors affecting CO2 sequestration during MICP were the pH and medium components. The increase in pH led to enhanced CO2 sequestration by the growth medium. The growth medium components, on the other hand, were shown to affect both the urease activity and CO2 sequestration. Through the Plackett-Burman experimental design, the most important growth medium component involved in CO2 sequestration was determined to be urea. The optimized medium composition by the Plackett-Burman design for each isolate led to a statistically significant increase, of up to 148.9%, in CO2 uptake through calcification mechanisms. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. 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

  5. Biotic and abiotic factors regulating forest floor CO2 flux across a range of forest age classes in the southern Appalachians

    Treesearch

    James M. Vose; Paul V. Bolstad

    2007-01-01

    We measured forest floor CO2 flux in three age classes of forest in the southern Appalachians: 20-year-old, 85-year-old, and old-growth. Our objectives were to quantify differences in forest floor CO2 flux among age classes, and determine the relative importance of abiotic and biotic driving variables. Forest floor CO

  6. Behavior of CO2/water flow in porous media for CO2 geological storage.

    PubMed

    Jiang, Lanlan; Yu, Minghao; Liu, Yu; Yang, Mingjun; Zhang, Yi; Xue, Ziqiu; Suekane, Tetsuya; Song, Yongchen

    2017-04-01

    A clear understanding of two-phase fluid flow properties in porous media is of importance to CO 2 geological storage. The study visually measured the immiscible and miscible displacement of water by CO 2 using MRI (magnetic resonance imaging), and investigated the factor influencing the displacement process in porous media which were filled with quartz glass beads. For immiscible displacement at slow flow rates, the MR signal intensity of images increased because of CO 2 dissolution; before the dissolution phenomenon became inconspicuous at flow rate of 0.8mLmin -1 . For miscible displacement, the MR signal intensity decreased gradually independent of flow rates, because supercritical CO 2 and water became miscible in the beginning of CO 2 injection. CO 2 channeling or fingering phenomena were more obviously observed with lower permeable porous media. Capillary force decreases with increasing particle size, which would increase permeability and allow CO 2 and water to invade into small pore spaces more easily. The study also showed CO 2 flow patterns were dominated by dimensionless capillary number, changing from capillary finger to stable flow. The relative permeability curve was calculated using Brooks-Corey model, while the results showed the relative permeability of CO 2 slightly decreases with the increase of capillary number. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Upward flow of supercritical CO2 with transition to gaseous conditions: Simulations for design of large-scale CO2 flow experiments at LUCI

    NASA Astrophysics Data System (ADS)

    Oldenburg, C. M.; Peters, C. A.; Dobson, P. F.; Doughty, C.

    2010-12-01

    Understanding the processes involved in large-scale upward flow of CO2 related to Geologic Carbon Sequestration (GCS) is critical to evaluating trapping mechanisms and potential impacts of CO2 leakage over long distances. The Laboratory for Underground CO2 Investigations (LUCI) is being planned to be built at DUSEL to host large-scale vertical CO2 and brine flow experiments. As conceived, LUCI would consist of a 500 m-long vertical raisebore approximately 3 m in diameter which will contain three suspended long-column pressure vessels. The long-column pressure vessels are planned to be 1 m in diameter with thermal control on the outer walls with a centralized inner fiberglass well for accommodating monitoring tools for determining phase saturation, porosity, temperature, and other properties of the flow region. The outer wall of the inner fiberglass well and the inner wall of the main vessel comprise the lateral boundaries of the long vertical annular regions that will be filled with porous media in which experiments investigating flow and transport, geochemical alterations of well cement, and biological processes involving injected CO2 will be performed. The large vertical extent of the column is needed to span the full range of CO2 conditions from supercritical (scCO2, P > 7.4 MPa, T > 31 °C) to gaseous CO2 that is believed to be significant as CO2 flows upwards. Here we consider the CO2-brine flow experiments in which the annular region will be pressurized at the top and bottom and contain brine-filled porous media through which scCO2 introduced at the bottom will flow upward. We are carrying out two-phase flow simulations of the buoyancy- and pressure-driven flow of CO2 and brine upward in the annular porous media region to further design the flow columns, e.g., to determine critical length and diameter requirements, as well as to plan the experiments to be performed. The simulations are carried out using TOUGH2/ECO2N, which models two-phase non-isothermal flow

  8. Identifying Planetary Biosignature Impostors: Spectral Features of CO and O4 Resulting from Abiotic O2/O3 Production

    NASA Astrophysics Data System (ADS)

    Schwieterman, Edward W.; Meadows, Victoria S.; Domagal-Goldman, Shawn D.; Deming, Drake; Arney, Giada N.; Luger, Rodrigo; Harman, Chester E.; Misra, Amit; Barnes, Rory

    2016-03-01

    O2 and O3 have been long considered the most robust individual biosignature gases in a planetary atmosphere, yet multiple mechanisms that may produce them in the absence of life have been described. However, these abiotic planetary mechanisms modify the environment in potentially identifiable ways. Here we briefly discuss two of the most detectable spectral discriminants for abiotic O2/O3: CO and O4. We produce the first explicit self-consistent simulations of these spectral discriminants as they may be seen by James Webb Space Telescope (JWST). If JWST-NIRISS and/or NIRSpec observe CO (2.35, 4.6 μm) in conjunction with CO2 (1.6, 2.0, 4.3 μm) in the transmission spectrum of a terrestrial planet it could indicate robust CO2 photolysis and suggest that a future detection of O2 or O3 might not be biogenic. Strong O4 bands seen in transmission at 1.06 and 1.27 μm could be diagnostic of a post-runaway O2-dominated atmosphere from massive H-escape. We find that for these false positive scenarios, CO at 2.35 μm, CO2 at 2.0 and 4.3 μm, and O4 at 1.27 μm are all stronger features in transmission than O2/O3 and could be detected with S/Ns ≳ 3 for an Earth-size planet orbiting a nearby M dwarf star with as few as 10 transits, assuming photon-limited noise. O4 bands could also be sought in UV/VIS/NIR reflected light (at 0.345, 0.36, 0.38, 0.445, 0.475, 0.53, 0.57, 0.63, 1.06, and 1.27 μm) by a next generation direct-imaging telescope such as LUVOIR/HDST or HabEx and would indicate an oxygen atmosphere too massive to be biologically produced.

  9. Identifying Planetary Biosignature Impostors: Spectral Features of CO and O4 Resulting from Abiotic O2/O3 Production

    NASA Technical Reports Server (NTRS)

    Schwieterman, Edward W.; Meadows, Victoria S.; Domagal-Goldman, Shawn D.; Deming, Drake; Arney, Giada N.; Luger, Rodrigo; Harman, Chester E.; Misra, Amit; Barnes, Rory

    2016-01-01

    O2 and O3 have been long considered the most robust individual biosignature gases in a planetary atmosphere, yet multiple mechanisms that may produce them in the absence of life have been described. However, these abiotic planetary mechanisms modify the environment in potentially identifiable ways. Here we briefly discuss two of the most detectable spectral discriminants for abiotic O2/O3: CO and O4. We produce the first explicit self-consistent simulations of these spectral discriminants as they may be seen by James Webb Space Telescope (JWST). If JWST-NIRISS (Near InfraRed Imager and Slitless Spectrograph) and/or NIRSpec (Near InfraRed Spectograph) observe CO (2.35, 4.6 micrometers) in conjunction with CO2 (1.6, 2.0, 4.3 micrometers) in the transmission spectrum of a terrestrial planet it could indicate robust CO2 photolysis and suggest that a future detection of O2 or O3 might not be biogenic. Strong O4 bands seen in transmission at 1.06 and 1.27 micrometers could be diagnostic of a post-runaway O2-dominated atmosphere from massive H-escape. We find that for these false positive scenarios, CO at 2.35 micrometers, CO2 at 2.0 and 4.3 micrometers, and O4 at 1.27 micrometers are all stronger features in transmission than O2/O3 and could be detected with sigal to noise ratios greater than or approximately 3 for an Earth-size planet orbiting a nearby M dwarf star with as few as 10 transits, assuming photon-limited noise. O4 bands could also be sought in UV/VIS/NIR reflected light (at 0.345, 0.36, 0.38, 0.445, 0.475, 0.53, 0.57, 0.63, 1.06, and 1.27 micrometers) by a next generation direct imaging telescope such as LUVOIR (Large Ultraviolet Visible Infrared)/HDST (High-Definition Space Telescope) or HabEx (Habitable-Exoplanet Imaging Mission) and would indicate an oxygen atmosphere too massive to be biologically produced.

  10. Studies of Martian polar regions. [using CO2 flow

    NASA Technical Reports Server (NTRS)

    Smith, C. I.; Clark, B. R.; Eschman, D. F.

    1974-01-01

    The flow law determined experimentally for solid CO2 establishes that an hypothesis of glacial flow of CO2 at the Martian poles is not physically unrealistic. Compression experiments carried out under 1 atmosphere pressure and constant strain rate conditions demonstrate that the strength of CO2 near its sublimation point is considerably less than the strength of water ice near its melting point. A plausible glacial model for the Martian polar caps was constructed. The CO2 deposited near the pole would have flowed outward laterally to relieve high internal shear stresses. The topography of the polar caps, and the uniform layering and general extent of the layered deposits were explained using this model.

  11. Effects of Mass Flow Rate on the Thermal-Flow Characteristics of Microwave CO2 Plasma.

    PubMed

    Hong, Chang-Ki; Na, Young-Ho; Uhm, Han-Sup; Kim, Youn-Jea

    2015-03-01

    In this study, the thermal-flow characteristics of atmospheric pressure microwave CO2 plasma were numerically investigated by simulation. The electric and gas flow fields in the reaction chamber with a microwave axial injection torch operated at 2.45 GHz were simulated. The microwave launcher had the standard rectangular waveguide WR340 geometry. The simulation was performed by using the COMSOL Multiphysics plasma model with various mass flow rates of CO2. The electric fields, temperature profiles and the density of electrons were graphically depicted for different CO2 inlet mass flow rates.

  12. IDENTIFYING PLANETARY BIOSIGNATURE IMPOSTORS: SPECTRAL FEATURES OF CO AND O{sub 4} RESULTING FROM ABIOTIC O{sub 2}/O{sub 3} PRODUCTION

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

    Schwieterman, Edward W.; Meadows, Victoria S.; Arney, Giada N.

    O{sub 2} and O{sub 3} have been long considered the most robust individual biosignature gases in a planetary atmosphere, yet multiple mechanisms that may produce them in the absence of life have been described. However, these abiotic planetary mechanisms modify the environment in potentially identifiable ways. Here we briefly discuss two of the most detectable spectral discriminants for abiotic O{sub 2}/O{sub 3}: CO and O{sub 4}. We produce the first explicit self-consistent simulations of these spectral discriminants as they may be seen by James Webb Space Telescope (JWST). If JWST-NIRISS and/or NIRSpec observe CO (2.35, 4.6 μm) in conjunction withmore » CO{sub 2} (1.6, 2.0, 4.3 μm) in the transmission spectrum of a terrestrial planet it could indicate robust CO{sub 2} photolysis and suggest that a future detection of O{sub 2} or O{sub 3} might not be biogenic. Strong O{sub 4} bands seen in transmission at 1.06 and 1.27 μm could be diagnostic of a post-runaway O{sub 2}-dominated atmosphere from massive H-escape. We find that for these false positive scenarios, CO at 2.35 μm, CO{sub 2} at 2.0 and 4.3 μm, and O{sub 4} at 1.27 μm are all stronger features in transmission than O{sub 2}/O{sub 3} and could be detected with S/Ns ≳ 3 for an Earth-size planet orbiting a nearby M dwarf star with as few as 10 transits, assuming photon-limited noise. O{sub 4} bands could also be sought in UV/VIS/NIR reflected light (at 0.345, 0.36, 0.38, 0.445, 0.475, 0.53, 0.57, 0.63, 1.06, and 1.27 μm) by a next generation direct-imaging telescope such as LUVOIR/HDST or HabEx and would indicate an oxygen atmosphere too massive to be biologically produced.« less

  13. How does natural groundwater flow affect CO2 dissolution in saline aquifers?

    NASA Astrophysics Data System (ADS)

    Rosenzweig, R.; Michel-Meyer, I.; Tsinober, A.; Shavit, U.

    2017-12-01

    The dissolution of supercritical CO2 in aquifer brine is one of the most important trapping mechanisms in CO2 geological storage. Diffusion-limited dissolution is a very slow process. However, since the CO2-rich water is slightly denser than the CO2-free water, when CO2-free water is overlaid by heavier CO2-rich water, convective instability results in fingers of dense CO2-rich water that propagate downwards, causing CO2-unsaturated water to move upwards. This convection process significantly accelerates the dissolution rate of CO2 into the aquifer water.Most previous works have neglected the effect of natural groundwater flow and assumed it has no effect on the dissolution dynamics. However, it was found that in some of the saline aquifers groundwater flow rate, although small, is not zero. In this research, we study the effect of groundwater flow on dissolution by performing laboratory experiments in a bead pack cell using a mixture of methanol and ethylene-glycol as a CO2 analog while varying the water horizontal flow rate. We find that water horizontal flow decreases the number of fingers, their wavelength and their propagation velocity. When testing high water flow rates, no fingers were developed and the dissolution process was entirely diffusive. The effect of water flow on the dissolution rate did not show a clear picture. When increasing the horizontal flow rate the convective dissolution flux slightly decreased and then increased again. It seems that the combination of density-driven flow, water horizontal flow, mechanical dispersion and molecular diffusion affect the dissolution rate in a complex and non-monotonic manner. These intriguing dynamics should be further studied to understand their effect on dissolution trapping.

  14. Flow Distribution Measurement Feasibility in Supercritical CO 2

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

    Lance, Blake

    2017-12-01

    Supercritical CO 2 (sCO 2) is a fluid of interest for advanced power cycles that can reach thermal to electric energy conversion efficiencies of 50% or higher. Of particular interest for fossil-fired natural gas is the Allam cycle that captures nearly all CO 2 emissions and exports it as a fluid stream where it may be of value. The combustion process conditions are unlike any before realized with 90-95% CO 2 concentration, temperatures around 1000°C, and pressures near 300 bar. This work outlines the experimental feasibility of flow measurements to acquire the first known data in pure sCO 2 atmore » similar but reduced temperature and pressure conditions.« less

  15. The abiotically driven biological pump in the ocean and short-term fluctuations in atmospheric CO 2 contents

    NASA Astrophysics Data System (ADS)

    Ittekkot, Venugopalan

    1993-07-01

    Current debates on the significance of the oceanic "biological pump" in the removal of atmospheric CO 2 pay more attention to the act of biological carbon-dioxide fixation (primary productivity) in the sea, but pay less or no attention to the equally relevant aspect of the transfer of the fixed carbon to a sink before its oxidation back to CO 2. The upper ocean obviously disqualifies as a sink for biologically fixed CO 2 because of gas-exchange with the atmosphere. The deep ocean, on the other hand, can be a sink at least at time scales of the ocean turnover. Transfer of newly-fixed CO 2 to the deep sea can be accelerated by abiogenic matter introduced to the sea surface from terrestrial sources. This matter acts as ballast and increases the density and settling rates of aggregates of freshly synthesized organic matter thereby facilitating their rapid removal from the upper ocean. Higher supply of abiogenic matter enhances the sequestering of fresh organic matter and in effect shifts the zone of organic matter remineralization from the upper ocean to the deep sea. Consistent with this abiogenic forcing, the rate of organic matter remineralization and the subsequent storage of the remineralized carbon in the deep sea are linked to bulk fluxes (mass accumulation rates) in the deep sea. This mechanism acts as an "abiotic boost" in the workings of the oceanic "biological pump" and results in an increase in deep sea carbon storage; the magnitude of carbon thus stored could have caused the observed short term fluctuations in atmospheric CO 2-contents during the glacial-interglacial cycles.

  16. Usage of CO2 microbubbles as flow-tracing contrast media in X-ray dynamic imaging of blood flows.

    PubMed

    Lee, Sang Joon; Park, Han Wook; Jung, Sung Yong

    2014-09-01

    X-ray imaging techniques have been employed to visualize various biofluid flow phenomena in a non-destructive manner. X-ray particle image velocimetry (PIV) was developed to measure velocity fields of blood flows to obtain hemodynamic information. A time-resolved X-ray PIV technique that is capable of measuring the velocity fields of blood flows under real physiological conditions was recently developed. However, technical limitations still remained in the measurement of blood flows with high image contrast and sufficient biocapability. In this study, CO2 microbubbles as flow-tracing contrast media for X-ray PIV measurements of biofluid flows was developed. Human serum albumin and CO2 gas were mechanically agitated to fabricate CO2 microbubbles. The optimal fabricating conditions of CO2 microbubbles were found by comparing the size and amount of microbubbles fabricated under various operating conditions. The average size and quantity of CO2 microbubbles were measured by using a synchrotron X-ray imaging technique with a high spatial resolution. The quantity and size of the fabricated microbubbles decrease with increasing speed and operation time of the mechanical agitation. The feasibility of CO2 microbubbles as a flow-tracing contrast media was checked for a 40% hematocrit blood flow. Particle images of the blood flow were consecutively captured by the time-resolved X-ray PIV system to obtain velocity field information of the flow. The experimental results were compared with a theoretically amassed velocity profile. Results show that the CO2 microbubbles can be used as effective flow-tracing contrast media in X-ray PIV experiments.

  17. Pitot pressure analyses in CO2 condensing rarefied hypersonic flows

    NASA Astrophysics Data System (ADS)

    Ozawa, T.; Suzuki, T.; Fujita, K.

    2016-11-01

    In order to improve the accuracy of rarefied aerodynamic prediction, a hypersonic rarefied wind tunnel (HRWT) was developed at Japan Aerospace Exploration Agency. While this wind tunnel has been limited to inert gases, such as nitrogen or argon, we recently extended the capability of HRWT to CO2 hypersonic flows for several Mars missions. Compared to our previous N2 cases, the condensation effect may not be negligible for CO2 rarefied aerodynamic measurements. Thus, in this work, we have utilized both experimental and numerical approaches to investigate the condensation and rarefaction effects in CO2 hypersonic nozzle flows.

  18. The effect of light level, CO2 flow rate, and anesthesia on the stress response of mice during CO2 euthanasia.

    PubMed

    Powell, Karin; Ethun, Kelly; Taylor, Douglas K

    2016-09-21

    Euthanasia protocols are designed to mitigate the stress experienced by animals, and an environment that induces minimal stress helps achieve that goal. A protocol that is efficient and practical in a typical animal research facility is also important. Light intensity, isoflurane, and CO2 flow rate were studied for their impact on the stress response of mice during CO2 euthanasia. Behavior was observed and scored during euthanasia and serum corticosterone was measured immediately after death. Unsurprisingly, animals euthanized with a high-flow rate of CO2 became unconscious in the least amount of time, while animals euthanized with a low-flow rate required the most time to reach unconsciousness. There was a significant increase in anxious behaviors in animals in the isoflurane group (F1,12 = 6.67, P = 0.024), the high-flow rate CO2 group (F1,12 = 10.24, P = 0.007), and bright chamber group (F1,12 = 7.27, P = 0.019). Serum corticosterone was highest in the isoflurane group (124.72 ± 83.98 ng/ml), however there was no significant difference in corticosterone levels observed for the other study variables of light and flow-rate. A darkened chamber and low CO2 flow rates help to decrease stress experienced during CO2 euthanasia, while the use of isoflurane was observed to increase the stress response during euthanasia.

  19. Coupled biotic-abiotic oxidation of organic matter by biogenic MnO_{2}

    NASA Astrophysics Data System (ADS)

    Gonzalez, Julia; Peña, Jasquelin

    2016-04-01

    labile fraction may lower solution pH into a regime that favours abiotic oxidation of recalcitrant C by MnO2. This project demonstrates that the co-occurrence of mineral particles with metabolically active cells provides a direct link between the C and Mn cycles.

  20. CO2 exsolution - challenges and opportunities in subsurface flow management

    NASA Astrophysics Data System (ADS)

    Zuo, Lin; Benson, Sally

    2014-05-01

    for storage security. Falta et al. [2013] show that if carbonated brine migrates upwards and exsolution occurs, brine migration would be greatly reduced and limited by the presence of exsolved CO2 and the consequent low relatively permeability to brine. Similarly, if an exsolved CO2 phase were to evolve in seals, for example, after CO2 injection stops, the effect would be to reduce the permeability to brine and the CO2 would have very low mobility. This flow blocking effect is also studied with water/oil/CO2 [Zuo et al., 2013]. Experiments show that exsolved CO2 performs as a secondary residual phase in porous media that effectively blocks established water flow paths and deviates water to residual oil zones, thereby increasing recovery. Overall, our studies suggest that CO2 exsolution provides an opportunity for mobility control in subsurface processes. However, the lack of simulation capability that accounts for differences between gas injection and gas exsolution creates challenges for modeling and hence, designing studies to exploit the mobility reduction capabilities of CO2 exsolution. Using traditional drainage multiphase flow parameterization in simulations involving exsolution will lead to large errors in transport rates. Development of process dependent parameterizations of multiphase flow properties will be a key next step and will help to unlock the benefits from gas exsolution. ACKNOWLEDGEMENT This work is funded by the Global Climate and Energy Project (GCEP) at Stanford University. This work was also supported by U.S. EPA, Science To Achieve Results (STAR) Program, Grant #: 834383, 2010-2012. REFERENCES Falta, R., L. Zuo and S.M. Benson (2013). Migration of exsolved CO2 following depressurization of saturated brines. Journal of Greenhouse Gas Science and Technology, 3(6), 503-515. Zuo, L., S.C.M. Krevor, R.W. Falta, and S.M. Benson (2012). An experimental study of CO2 exsolution and relative permeability measurements during CO2 saturated water

  1. Effect of inhalation of different mixtures of O2 and CO2 on retinal blood flow

    PubMed Central

    Luksch, A; Garhöfer, G; Imhof, A; Polak, K; Polska, E; Dorner, G T; Anzenhofer, S; Wolzt, M; Schmetterer, L

    2002-01-01

    Aim: To determine the effects of various mixtures of O2 and CO2 on retinal blood flow in healthy subjects. Methods: A randomised, double masked, four way crossover trial was carried out in 12 healthy male non-smoking subjects. Gas mixtures (100% O2, 97.5% O2 + 2.5% CO2, 95% O2 + 5% CO2, and 92% O2 + 8% CO2) were administered for 10 minutes each. Two non-invasive methods were used: laser Doppler velocimetry (LDV) for measurement of retinal blood velocity and fundus imaging with the Zeiss retinal vessel analyser (RVA) for the assessment of retinal vessel diameters. Arterial pH, pCO2, and pO2 were determined with an automatic blood gas analysis system. Retinal blood flow through a major temporal vein was calculated. Results: Retinal blood velocity, retinal vessel diameter, and retinal blood flow decreased during all breathing periods (p <0.001 each). Administration of 92% O2 + 8% CO2 significantly increased SBP, MAP, and PR (p <0.001 each, versus baseline), whereas the other gas mixtures had little effect on systemic haemodynamics. Addition of 2.5%, 5%, and 8% CO2 to oxygen caused a marked decrease in pH and an increase in pCO2 (p <0.001 versus pure oxygen). Conclusions: Breathing of pure oxygen and oxygen in combination with carbon dioxide significantly decreases retinal blood flow. Based on these data the authors speculate that hyperoxia induced vasoconstriction is not due to changes in intravascular pH and cannot be counteracted by an intravascular increase in pCO2. PMID:12234896

  2. Managing the Budget: Stock-Flow Reasoning and the CO2 Accumulation Problem.

    PubMed

    Newell, Ben R; Kary, Arthur; Moore, Chris; Gonzalez, Cleotilde

    2016-01-01

    The majority of people show persistent poor performance in reasoning about "stock-flow problems" in the laboratory. An important example is the failure to understand the relationship between the "stock" of CO2 in the atmosphere, the "inflow" via anthropogenic CO2 emissions, and the "outflow" via natural CO2 absorption. This study addresses potential causes of reasoning failures in the CO2 accumulation problem and reports two experiments involving a simple re-framing of the task as managing an analogous financial (rather than CO2 ) budget. In Experiment 1 a financial version of the task that required participants to think in terms of controlling debt demonstrated significant improvements compared to a standard CO2 accumulation problem. Experiment 2, in which participants were invited to think about managing savings, suggested that this improvement was fortuitous and coincidental rather than due to a fundamental change in understanding the stock-flow relationships. The role of graphical information in aiding or abetting stock-flow reasoning was also explored in both experiments, with the results suggesting that graphs do not always assist understanding. The potential for leveraging the kind of reasoning exhibited in such tasks in an effort to change people's willingness to reduce CO2 emissions is briefly discussed. Copyright © 2015 Cognitive Science Society, Inc.

  3. Occurrence of Volcanic CO2 by Groundwater Flow Systems in the Eifel Mountains, Germany

    NASA Astrophysics Data System (ADS)

    Weyer, K.; May, F.; Ellis, J. C.

    2011-12-01

    Weyer (2010) showed why and how discharge areas of regional groundwater flow systems are also discharge points of natural and stored CO2. As groundwater flow systems reach to great depth by penetrating aquitards and caprocks any successful design of on-shore geological carbon storage must regard the migration effects groundwater flow systems exert on stored CO2. Eventually all of the CO2 will be dissolved by groundwater and migrate to the discharge areas of these flow systems. By implication there will rarely be the anticipated permanent storage of CO2 in the subsurface. Instead the deep ground water flow will transport the dissolved CO2 into surface waters. A telling example of such a system is the Green River in Utah with its natural discharge points of volcanic CO2 and the artificial discharge point Crystal Geyser, a flowing abandoned well located at the bank of the Green River. The advantage of this situation is that there have been hydrogeological tools developed which allow the determination of the flow path of the groundwater flow systems and their approximate time scale to reach their groundwater discharge areas. These time spans may be as large as 50,000 to 100,000 years. In any case residence times of a thousand years and more would suffice in mitigating the atmospheric effect of CO2 discharge. The above concepts have so far not created much resonance in the scientific and practical world of geologic CO2 storage. Therefore the investigation of groundwater dynamics at areas with natural discharge of volcanic CO2 provides a test for the effect groundwater flow systems will exert on the geologic storage of CO2. The Eifel Mountains in Germany present such a natural laboratory as it contains over a hundred known Tertiary and Quaternary volcanoes. Its discharge points of water carrying CO2 are well-known as they have been used for generations for the production of carbonated mineral waters. For the western part of the Eifel-Mountains, May (2002) listed all

  4. Influence of Common Bean (Phaseolus vulgaris) Grown in Elevated CO2 on Apatite Dissolution

    NASA Astrophysics Data System (ADS)

    Olsen, A. A.; Morra, B.

    2016-12-01

    We ran a series of experiments to test the hypothesis that release of plant nutrients contained in apatite will be accelerated by the growth of Langstrath Stringless green bean in the presence of atmospheric CO2 meant to simulate possible future atmospheric conditions due a higher demand of nutrients and growth rate caused by elevated CO2. We hypothesize that elevated atmospheric CO2 will lead to both increased root growth and organic acid exudation. These two traits will lead to improved acquisition of P derived from apatite. Experiments were designed to investigate the effect of these changes on soil mineral weathering using plants grown under two conditions, ambient CO2 (400ppm) and elevated CO2 (1000ppm). Plants were grown in flow-through microcosms consisting of a mixture of quartz and apatite sands. Mini-greenhouses were utilized to control CO2 levels. Plant growth was sustained by a nutrient solution lacking in Ca and P. Calcium and P content of the leachate and plant tissue served as a proxy for apatite dissolution. Plants were harvested biweekly during the eight-week experiment and analyzed for Ca and P to calculate apatite dissolution kinetics. Preliminary results suggest that approximately four times more P and Ca are present in the leachate from experiments containing plants under both ambient and elevated CO2 levels than in abiotic experiments; however, the amounts of both P and Ca released in experiments conducted under both ambient and elevated CO2 levels are similar. Additionally, the amount of P in plant tissue grown under ambient and elevated CO2 conditions is similar. Plants grown in elevated CO2 had a greater root to shoot ratio. The planted microcosms were found to have a lower pH than abiotic controls most likely due to root respiration and exudation of organic acids.

  5. Abiotic controls on N2O emissions from soils and wetlands

    NASA Astrophysics Data System (ADS)

    Horwath, W. R.

    2016-12-01

    The increase in atmospheric nitrous oxide (N2O) is a critical climate change issue contributing to global warming. Most studies on N2O production attribute microbial processes and their associated enzymatic reactions to be the main driver affecting emissions. The role of redox capable iron, manganese and organic compounds that can react with intermediates in the nitrogen cycle has also been shown to produce N2O abiotically. The importance of the abiotic pathways, however, is highly debated. The abiotic production of N2O is related to biophysiochemical controls and unique isotopic signatures of nitrogen cycle intermediates (hydroxylamine, nitric oxide, and nitrite), redox-active metals (iron and manganese) and organic matter (humic and fulvic acids). In a range of soils, we find that the iron directly associated with organic compounds is the strongest variable relating to N2O emissions. In addition to these factors, management is also assumed to affect abiotic N2O production through its impact on nitrogen cycle intermediates, but the environmental and physiochemical conditions that are changed by management are rarely considered in the abiotic production of N2O. We find that the amount and quality of organic compounds in soils directly determines the fate of soil N2O production (i.e. be emitted or consumed). Water depth in rice paddies and wetlands also plays a significant role in partitioning production and consumption of N2O. What is evident from studies on N2O emission is that abiotic reactions are coupled to biotic processes and they cannot be easily separated. The biotic/abiotic interactions have important ecological outcomes that influence abiotic production mechanisms and should be recognized as important controllers of N2O production and consumption processes in soils and sediments.

  6. The Real Difference between Biotic and Abiotic Methane

    NASA Astrophysics Data System (ADS)

    Cao, X.; Bao, H.; Peng, Y.

    2017-12-01

    Methane has both biotic and abiotic origins, and the identification of these two origins has important implications not only in understanding terrestrial processes but also in searching for extraterrestrial life. Carbon and hydrogen isotopes in methane have been used to identify certain biosignatures, but such efforts often suffer from ambiguity. Recent advancement in our capability in measuring multiply substituted isotopologues of methane (i.e. 13CDH3 and 12CD2H2) has found large 12CD2H2 depletion in abiotic methane. Quantum tunneling has been proposed to account for the apparent abiotic signature. However, quantum tunneling is neither unique to abiotic processes nor consistent with the observed not-so-depleted hydrogen isotope composition. Here we constructed a general kinetic model for methane formation from CO2, and validated it by fitting its parameters to observed 13CDH3, 12CD2H2, and 12CDH3. Our model revealed that the fundamental difference between biotic and abiotic methane isotopic signatures is in the source of hydrogens during methane formation. Hydrogens in biotic methane originate from the stronger carbon-hydrogen and sulfur-hydrogen bonds, while hydrogens in abiotic methane originate from the much weaker metal-hydrogen adsorption bond. This hydrogen source difference results in abiotic methane being more depleted in 12CD2H2 than the biotic one. Our model also shows that the primary kinetic hydrogen isotope effect is at approximately 0.6 for both abiotic and biotic pathways, a normal value further nullifying the role of quantum tunneling. The active and exclusive shuttling of reduced hydrogen via strong chemical bonds like carbon-hydrogen and sulfur-hydrogen in coenzymes is proposed here to be a unique signature of life. In an ironic sense, it is the equilibrated hydrogen isotope composition in the hydrogen donors that distinguishes the living from the non-living.

  7. Study of the fluid flow characteristics in a porous medium for CO2 geological storage using MRI.

    PubMed

    Song, Yongchen; Jiang, Lanlan; Liu, Yu; Yang, Mingjun; Zhou, Xinhuan; Zhao, Yuechao; Dou, Binlin; Abudula, Abuliti; Xue, Ziqiu

    2014-06-01

    The objective of this study was to understand fluid flow in porous media. Understanding of fluid flow process in porous media is important for the geological storage of CO2. The high-resolution magnetic resonance imaging (MRI) technique was used to measure fluid flow in a porous medium (glass beads BZ-02). First, the permeability was obtained from velocity images. Next, CO2-water immiscible displacement experiments using different flow rates were investigated. Three stages were obtained from the MR intensity plot. With increasing CO2 flow rate, a relatively uniform CO2 distribution and a uniform CO2 front were observed. Subsequently, the final water saturation decreased. Using core analysis methods, the CO2 velocities were obtained during the CO2-water immiscible displacement process, which were applied to evaluate the capillary dispersion rate, viscous dominated fractional flow, and gravity flow function. The capillary dispersion rate dominated the effects of capillary, which was largest at water saturations of 0.5 and 0.6. The viscous-dominant fractional flow function varied with the saturation of water. The gravity fractional flow reached peak values at the saturation of 0.6. The gravity forces played a positive role in the downward displacements because they thus tended to stabilize the displacement process, thereby producing increased breakthrough times and correspondingly high recoveries. Finally, the relative permeability was also reconstructed. The study provides useful data regarding the transport processes in the geological storage of CO2. Crown Copyright © 2014. Published by Elsevier Inc. All rights reserved.

  8. Toward modeling of supercritical CO2 flow using the one-dimensional turbulence model

    NASA Astrophysics Data System (ADS)

    Schulz, F. T.; Glawe, C.; Schmidt, H.; Kerstein, A. R.

    2012-04-01

    Within the CCS (Carbon Capture and Storage) technology the transport of captured CO2 is increasingly regarded as the missing link in research. For industrial applications it is essential to transport CO2 from power plants to geological sites through pipelines and well bores. The effectiveness of such a transport could be increased by keeping CO2 in a supercritical state. This however requires a temperature of at least 31Celsius and a pressure above 73.8 bar. If these conditions are not maintained throughout the whole pipeline, which is challenging and expensive under non-laboratory conditions, density and phase changes and pressure fluctuations may result in harmful vibrations of the pipelines. Typically, simulations of pipeline flow are based on large-eddy simulations (LES) or the Reynolds averaged Navier-Stokes (RANS) equations which both do not resolve the smallest turbulent scales or even phase boundaries. Due to the effect that on pipe diameter scales the flow statistically changes predominantly in the wall normal direction one might consider 1D modeling approaches. The work presented here is part of the GeoEn II activities funded by the Federal Ministry of Education and Research (BMBF) to better understand risks and benefits of CCS technology. Our project goal is to better understand the small scale physics in turbulent CO2 flows and to improve subgrid-scale models used in LES codes. To achieve this we use ODT (One-Dimensional Turbulence), a statistical turbulence modeling strategy, where turbulent flow evolution along a notional 1D line of sight is emulated by applying instantaneous maps to represent the effect of individual turbulent eddies on property profiles along the line. The occurrence of an eddy itself is affected by the property profiles, resulting in a self-contained flow evolution that obeys the applicable conservation laws. Using a 1D ansatz permits a higher resolution of boundary and single phase density gradients which is key to understand the

  9. 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.

  10. Effects of Anode Flow Field Design on CO2 Bubble Behavior in μDMFC

    PubMed Central

    Li, Miaomiao; Liang, Junsheng; Liu, Chong; Sun, Gongquan; Zhao, Gang

    2009-01-01

    Clogging of anode flow channels by CO2 bubbles is a vital problem for further performance improvements of the micro direct methanol fuel cell (μDMFC). In this paper, a new type anode structure using the concept of the non-equipotent serpentine flow field (NESFF) to solve this problem was designed, fabricated and tested. Experiments comparing the μDMFC with and without this type of anode flow field were implemented using a home-made test loop. Results show that the mean-value, amplitude and frequency of the inlet-to-outlet pressure drops in the NESFF is far lower than that in the traditional flow fields at high μDMFC output current. Furthermore, the sequential images of the CO2 bubbles as well as the μDMFC performance with different anode flow field pattern were also investigated, and the conclusions are in accordance with those derived from the pressure drop experiments. Results of this study indicate that the non-equipotent design of the μDMFC anode flow field can effectively mitigate the CO2 clogging in the flow channels, and hence lead to a significant promotion of the μDMFC performance. PMID:22412313

  11. Integrated CO2 capture-fixation chemistry via interfacial ionic liquid catalyst in laminar gas/liquid flow

    NASA Astrophysics Data System (ADS)

    Vishwakarma, Niraj K.; Singh, Ajay K.; Hwang, Yoon-Ho; Ko, Dong-Hyeon; Kim, Jin-Oh; Babu, A. Giridhar; Kim, Dong-Pyo

    2017-03-01

    Simultaneous capture of carbon dioxide (CO2) and its utilization with subsequent work-up would significantly enhance the competitiveness of CO2-based sustainable chemistry over petroleum-based chemistry. Here we report an interfacial catalytic reaction platform for an integrated autonomous process of simultaneously capturing/fixing CO2 in gas-liquid laminar flow with subsequently providing a work-up step. The continuous-flow microreactor has built-in silicon nanowires (SiNWs) with immobilized ionic liquid catalysts on tips of cone-shaped nanowire bundles. Because of the superamphiphobic SiNWs, a stable gas-liquid interface maintains between liquid flow of organoamines in upper part and gas flow of CO2 in bottom part of channel. The intimate and direct contact of the binary reagents leads to enhanced mass transfer and facilitating reactions. The autonomous integrated platform produces and isolates 2-oxazolidinones and quinazolines-2,4(1H,3H)-diones with 81-97% yields under mild conditions. The platform would enable direct CO2 utilization to produce high-valued specialty chemicals from flue gases without pre-separation and work-up steps.

  12. Integrated CO2 capture-fixation chemistry via interfacial ionic liquid catalyst in laminar gas/liquid flow.

    PubMed

    Vishwakarma, Niraj K; Singh, Ajay K; Hwang, Yoon-Ho; Ko, Dong-Hyeon; Kim, Jin-Oh; Babu, A Giridhar; Kim, Dong-Pyo

    2017-03-06

    Simultaneous capture of carbon dioxide (CO 2 ) and its utilization with subsequent work-up would significantly enhance the competitiveness of CO 2 -based sustainable chemistry over petroleum-based chemistry. Here we report an interfacial catalytic reaction platform for an integrated autonomous process of simultaneously capturing/fixing CO 2 in gas-liquid laminar flow with subsequently providing a work-up step. The continuous-flow microreactor has built-in silicon nanowires (SiNWs) with immobilized ionic liquid catalysts on tips of cone-shaped nanowire bundles. Because of the superamphiphobic SiNWs, a stable gas-liquid interface maintains between liquid flow of organoamines in upper part and gas flow of CO 2 in bottom part of channel. The intimate and direct contact of the binary reagents leads to enhanced mass transfer and facilitating reactions. The autonomous integrated platform produces and isolates 2-oxazolidinones and quinazolines-2,4(1H,3H)-diones with 81-97% yields under mild conditions. The platform would enable direct CO 2 utilization to produce high-valued specialty chemicals from flue gases without pre-separation and work-up steps.

  13. Integrated CO2 capture-fixation chemistry via interfacial ionic liquid catalyst in laminar gas/liquid flow

    PubMed Central

    Vishwakarma, Niraj K.; Singh, Ajay K.; Hwang, Yoon-Ho; Ko, Dong-Hyeon; Kim, Jin-Oh; Babu, A. Giridhar; Kim, Dong-Pyo

    2017-01-01

    Simultaneous capture of carbon dioxide (CO2) and its utilization with subsequent work-up would significantly enhance the competitiveness of CO2-based sustainable chemistry over petroleum-based chemistry. Here we report an interfacial catalytic reaction platform for an integrated autonomous process of simultaneously capturing/fixing CO2 in gas–liquid laminar flow with subsequently providing a work-up step. The continuous-flow microreactor has built-in silicon nanowires (SiNWs) with immobilized ionic liquid catalysts on tips of cone-shaped nanowire bundles. Because of the superamphiphobic SiNWs, a stable gas–liquid interface maintains between liquid flow of organoamines in upper part and gas flow of CO2 in bottom part of channel. The intimate and direct contact of the binary reagents leads to enhanced mass transfer and facilitating reactions. The autonomous integrated platform produces and isolates 2-oxazolidinones and quinazolines-2,4(1H,3H)-diones with 81–97% yields under mild conditions. The platform would enable direct CO2 utilization to produce high-valued specialty chemicals from flue gases without pre-separation and work-up steps. PMID:28262667

  14. Benchmarking of vertically-integrated CO2 flow simulations at the Sleipner Field, North Sea

    NASA Astrophysics Data System (ADS)

    Cowton, L. R.; Neufeld, J. A.; White, N. J.; Bickle, M. J.; Williams, G. A.; White, J. C.; Chadwick, R. A.

    2018-06-01

    Numerical modeling plays an essential role in both identifying and assessing sub-surface reservoirs that might be suitable for future carbon capture and storage projects. Accuracy of flow simulations is tested by benchmarking against historic observations from on-going CO2 injection sites. At the Sleipner project located in the North Sea, a suite of time-lapse seismic reflection surveys enables the three-dimensional distribution of CO2 at the top of the reservoir to be determined as a function of time. Previous attempts have used Darcy flow simulators to model CO2 migration throughout this layer, given the volume of injection with time and the location of the injection point. Due primarily to computational limitations preventing adequate exploration of model parameter space, these simulations usually fail to match the observed distribution of CO2 as a function of space and time. To circumvent these limitations, we develop a vertically-integrated fluid flow simulator that is based upon the theory of topographically controlled, porous gravity currents. This computationally efficient scheme can be used to invert for the spatial distribution of reservoir permeability required to minimize differences between the observed and calculated CO2 distributions. When a uniform reservoir permeability is assumed, inverse modeling is unable to adequately match the migration of CO2 at the top of the reservoir. If, however, the width and permeability of a mapped channel deposit are allowed to independently vary, a satisfactory match between the observed and calculated CO2 distributions is obtained. Finally, the ability of this algorithm to forecast the flow of CO2 at the top of the reservoir is assessed. By dividing the complete set of seismic reflection surveys into training and validation subsets, we find that the spatial pattern of permeability required to match the training subset can successfully predict CO2 migration for the validation subset. This ability suggests that it

  15. ABIOTIC DEGRADATION OF TRICHLOROETHYLENE UNDER THERMAL REMEDIATION CONDITIONS

    EPA Science Inventory

    The degradation of TCE (C2HCl3) to carbon dioxide (CO2) and chloride (Cl-) has been reported to occur during thermal remediation of subsurface environments. The overall goal of this study was to evaluate abiotic degradation of TCE at el...

  16. pCO2 and pH regulation of cerebral blood flow

    PubMed Central

    Yoon, SeongHun; Zuccarello, Mario; Rapoport, Robert M.

    2012-01-01

    CO2 serves as one of the fundamental regulators of cerebral blood flow (CBF). It is widely considered that this regulation occurs through pCO2-driven changes in pH of the cerebral spinal fluid (CSF), with elevated and lowered pH causing direct relaxation and contraction of the smooth muscle, respectively. However, some findings also suggest that pCO2 acts independently of and/or in conjunction with altered pH. This action may be due to a direct effect of CSF pCO2 on the smooth muscle as well as on the endothelium, nerves, and astrocytes. Findings may also point to an action of arterial pCO2 on the endothelium to regulate smooth muscle contractility. Thus, the effects of pH and pCO2 may be influenced by the absence/presence of different cell types in the various experimental preparations. Results may also be influenced by experimental parameters including myogenic tone as well as solutions containing significantly altered HCO3− concentrations, i.e., solutions routinely employed to differentiate the effects of pH from pCO2. In sum, it appears that pCO2, independently and in conjunction with pH, may regulate CBF. PMID:23049512

  17. Membraneless laminar flow cell for electrocatalytic CO2 reduction with liquid product separation

    NASA Astrophysics Data System (ADS)

    Monroe, Morgan M.; Lobaccaro, Peter; Lum, Yanwei; Ager, Joel W.

    2017-04-01

    The production of liquid fuel products via electrochemical reduction of CO2 is a potential path to produce sustainable fuels. However, to be practical, a separation strategy is required to isolate the fuel-containing electrolyte produced at the cathode from the anode and also prevent the oxidation products (i.e. O2) from reaching the cathode. Ion-conducting membranes have been applied in CO2 reduction reactors to achieve this separation, but they represent an efficiency loss and can be permeable to some product species. An alternative membraneless approach is developed here to maintain product separation through the use of a laminar flow cell. Computational modelling shows that near-unity separation efficiencies are possible at current densities achievable now with metal cathodes via optimization of the spacing between the electrodes and the electrolyte flow rate. Laminar flow reactor prototypes were fabricated with a range of channel widths by 3D printing. CO2 reduction to formic acid on Sn electrodes was used as the liquid product forming reaction, and the separation efficiency for the dissolved product was evaluated with high performance liquid chromatography. Trends in product separation efficiency with channel width and flow rate were in qualitative agreement with the model, but the separation efficiency was lower, with a maximum value of 90% achieved.

  18. Surface heat flow and CO2 emissions within the Ohaaki hydrothermal field, Taupo Volcanic Zone, New Zealand

    USGS Publications Warehouse

    Rissmann, C.; Christenson, B.; Werner, C.; Leybourne, M.; Cole, J.; Gravley, D.

    2012-01-01

    Carbon dioxide emissions and heat flow have been determined from the Ohaaki hydrothermal field, Taupo Volcanic Zone (TVZ), New Zealand following 20a of production (116MW e). Soil CO2 degassing was quantified with 2663 CO2 flux measurements using the accumulation chamber method, and 2563 soil temperatures were measured and converted to equivalent heat flow (Wm -2) using published soil temperature heat flow functions. Both CO2 flux and heat flow were analysed statistically and then modelled using 500 sequential Gaussian simulations. Forty subsoil CO 2 gas samples were also analysed for stable C isotopes. Following 20a of production, current CO2 emissions equated to 111??6.7T/d. Observed heat flow was 70??6.4MW, compared with a pre-production value of 122MW. This 52MW reduction in surface heat flow is due to production-induced drying up of all alkali-Cl outflows (61.5MW) and steam-heated pools (8.6MW) within the Ohaaki West thermal area (OHW). The drying up of all alkali-Cl outflows at Ohaaki means that the soil zone is now the major natural pathway of heat release from the high-temperature reservoir. On the other hand, a net gain in thermal ground heat flow of 18MW (from 25MW to 43.3??5MW) at OHW is associated with permeability increases resulting from surface unit fracturing by production-induced ground subsidence. The Ohaaki East (OHE) thermal area showed no change in distribution of shallow and deep soil temperature contours despite 20a of production, with an observed heat flow of 26.7??3MW and a CO 2 emission rate of 39??3T/d. The negligible change in the thermal status of the OHE thermal area is attributed to the low permeability of the reservoir beneath this area, which has limited production (mass extraction) and sheltered the area from the pressure decline within the main reservoir. Chemistry suggests that although alkali-Cl outflows once contributed significantly to the natural surface heat flow (~50%) they contributed little (<1%) to pre-production CO 2

  19. Experimental study on the CO2-flow mechanism in the two different sandstones

    NASA Astrophysics Data System (ADS)

    Imasato, M.; Honda, H.; Kitamura, K.

    2016-12-01

    It is important to discuss the flow properties of CO2 in the reservoir for estimations of storage potential and safety of CCS operation. In this study, we conducted the CO2-injection tests into two different types of porous sandstones with extremely low CO2 flow rate (10µl/min) under supercritical CO2 conditions. It was measured CO2 saturation (SCO2) and differential pressure (ΔP) between upstream and downstream of specimen. It was also monitored P-wave velocity (Vp) and electrical impedance (Z) for the monitoring of CO2 behavior in the specimen. We set three Vp measurement lines in different height for monitoring the movement of CO2 front. The results of ΔP measurement indicated that the Berea sandstone showed no obvious change, but the Ainoura sandstone was increasing gradually and peaked in 73 hours. After that, ΔP of the Ainoura sandstone started reducing. Both sandstones showed stepwise Vp-reduction from the bottom Vp-measurement line, which is near CO2 injection end. There are large differences of CO2 arrival time at the bottom line between Berea and Ainoura sandstone. In case of Ainoura sandstone, it took 29 hours to reduce Vp which is the nearest to CO2 injection end, but in case of Berea sandstone, it took 3.3 hours. This is also confirmed the arrival time at the top channel, 2.5 hours in the Berea sandstone and 11 hours in the Ainoura sandstone. The impedances of both sandstones indicted the gradual increment. It took 25 hours to become constant in the Berea sandstone and 148 hours in the Ainoura sandstone. SCO2 of the Berea sandstone was about 6% and Ainoura sandstone reached over 20%. These results suggest that it is due to the difference of the pore structure of Berea sandstone and Ainoura sandstone.

  20. CO2-vegetation feedbacks and other climate changes implicated in reducing base flow

    NASA Astrophysics Data System (ADS)

    Trancoso, Ralph; Larsen, Joshua R.; McVicar, Tim R.; Phinn, Stuart R.; McAlpine, Clive A.

    2017-03-01

    Changes in the hydrological cycle have a significant impact in water limited environments. Globally, some of these regions are experiencing declining precipitation yet are simultaneously becoming greener, partly due to vegetation feedbacks associated with increasing atmospheric CO2 concentrations. Reduced precipitation together with increasing rates of actual evapotranspiration diminishes streamflow, especially base flow, a critical freshwater dry-season resource. Here we assess recent changes in base flow in Australia from 1981-2013 and 1950-2013 and separate the contribution of precipitation, potential evapotranspiration, and other factors on base flow trends. Our findings reveal that these other factors influencing the base flow trends are best explained by an increase in photosynthetic activity. These results provide the first robust observational evidence that increasing atmospheric CO2 and its associated vegetation feedbacks are reducing base flow in addition to other climatic impacts. These findings have broad implications for water resource management, especially in the world's water limited regions.

  1. Differential blood flow responses to CO2 in human internal and external carotid and vertebral arteries

    PubMed Central

    Sato, Kohei; Sadamoto, Tomoko; Hirasawa, Ai; Oue, Anna; Subudhi, Andrew W; Miyazawa, Taiki; Ogoh, Shigehiko

    2012-01-01

    Arterial CO2 serves as a mediator of cerebral blood flow (CBF), and its relative influence on the regulation of CBF is defined as cerebral CO2 reactivity. Our previous studies have demonstrated that there are differences in CBF responses to physiological stimuli (i.e. dynamic exercise and orthostatic stress) between arteries in humans. These findings suggest that dynamic CBF regulation and cerebral CO2 reactivity may be different in the anterior and posterior cerebral circulation. The aim of this study was to identify cerebral CO2 reactivity by measuring blood flow and examine potential differences in CO2 reactivity between the internal carotid artery (ICA), external carotid artery (ECA) and vertebral artery (VA). In 10 healthy young subjects, we evaluated the ICA, ECA, and VA blood flow responses by duplex ultrasonography (Vivid-e, GE Healthcare), and mean blood flow velocity in middle cerebral artery (MCA) and basilar artery (BA) by transcranial Doppler (Vivid-7, GE healthcare) during two levels of hypercapnia (3% and 6% CO2), normocapnia and hypocapnia to estimate CO2 reactivity. To characterize cerebrovascular reactivity to CO2, we used both exponential and linear regression analysis between CBF and estimated partial pressure of arterial CO2, calculated by end-tidal partial pressure of CO2. CO2 reactivity in VA was significantly lower than in ICA (coefficient of exponential regression 0.021 ± 0.008 vs. 0.030 ± 0.008; slope of linear regression 2.11 ± 0.84 vs. 3.18 ± 1.09% mmHg−1: VA vs. ICA, P < 0.01). Lower CO2 reactivity in the posterior cerebral circulation was persistent in distal intracranial arteries (exponent 0.023 ± 0.006 vs. 0.037 ± 0.009; linear 2.29 ± 0.56 vs. 3.31 ± 0.87% mmHg−1: BA vs. MCA). In contrast, CO2 reactivity in ECA was markedly lower than in the intra-cerebral circulation (exponent 0.006 ± 0.007; linear 0.63 ± 0.64% mmHg−1, P < 0.01). These findings indicate that vertebro-basilar circulation has lower CO2 reactivity than

  2. Thermal Analysis of Compressible CO2 Flow for Major Equipment of Fire Detection System

    NASA Technical Reports Server (NTRS)

    Zhang, Michael Y.; Lee, Wen-Ching; Keener, John F.; Smith, Frederick D.

    2001-01-01

    A thermal analysis of the compressible CO2 flow for the Portable Fire Extinguisher (PFE) system has been performed. The purpose of this analysis is to determine the discharged CO2 mass from the PFE tank through the Temporary Sleep Station (TeSS) nozzle in reflecting to the latest design of the extended nozzle, and to evaluate the thermal issues associated to the latest nozzle configuration. A SINDA/FLUINT model has been developed for this analysis. The model includes the PFE tank and the TeSS nozzle, and both have initial temperature of 72 of. In order to investigate the thermal effect on the nozzle due to discharging C02, the PFE TeSS nozzle pipe has been divided into three segments. This model also includes heat transfer predictions for PFE tank inner and outer wall surfaces. The simulation results show that the CO2 discharge rates have fulfilled the minimum flow requirements that the PFE system discharges 3.0 Ibm CO2 in 10 seconds and 5.5 Ibm of CO2 in 45 seconds during its operation. At 45 seconds, the PFE tank wall temperature is 63 OF, and the TeSS nozzle cover wall temperatures for the three segments are 47 OF, 53 OF and 37 OF, respectively. Thermal insulation for personal protection is used for the first two segments of the TeSS nozzle. The simulation results also indicate that at 50 seconds, the remaining CO2 in the tank may be near the triple point (gas, liquid and solid) state and, therefore, restricts the flow.

  3. Multiphase, multicomponent simulations and experiments of reactive flow, relevant for combining geologic CO2 sequestration with geothermal energy capture

    NASA Astrophysics Data System (ADS)

    Saar, Martin O.

    2011-11-01

    Understanding the fluid dynamics of supercritical carbon dioxide (CO2) in brine- filled porous media is important for predictions of CO2 flow and brine displacement during geologic CO2 sequestration and during geothermal energy capture using sequestered CO2 as the subsurface heat extraction fluid. We investigate multiphase fluid flow in porous media employing particle image velocimetry experiments and lattice-Boltzmann fluid flow simulations at the pore scale. In particular, we are interested in the motion of a drop (representing a CO2 bubble) through an orifice in a plate, representing a simplified porous medium. In addition, we study single-phase/multicomponent reactive transport experimentally by injecting water with dissolved CO2 into rocks/sediments typically considered for CO2 sequestration to investigate how resultant fluid-mineral reactions modify permeability fields. Finally, we investigate numerically subsurface CO2 and heat transport at the geologic formation scale.

  4. LSU network hubs integrate abiotic and biotic stress responses via interaction with the superoxide dismutase FSD2

    PubMed Central

    Garcia-Molina, Antoni; Altmann, Melina; Alkofer, Angela; Epple, Petra M.; Dangl, Jeffery L.

    2017-01-01

    Abstract In natural environments, plants often experience different stresses simultaneously, and adverse abiotic conditions can weaken the plant immune system. Interactome mapping revealed that the LOW SULPHUR UPREGULATED (LSU) proteins are hubs in an Arabidopsis protein interaction network that are targeted by virulence effectors from evolutionarily diverse pathogens. Here we show that LSU proteins are up-regulated in several abiotic and biotic stress conditions, such as nutrient depletion or salt stress, by both transcriptional and post-translational mechanisms. Interference with LSU expression prevents chloroplastic reactive oxygen species (ROS) production and proper stomatal closure during sulphur stress. We demonstrate that LSU1 interacts with the chloroplastic superoxide dismutase FSD2 and stimulates its enzymatic activity in vivo and in vitro. Pseudomonas syringae virulence effectors interfere with this interaction and preclude re-localization of LSU1 to chloroplasts. We demonstrate that reduced LSU levels cause a moderately enhanced disease susceptibility in plants exposed to abiotic stresses such as nutrient deficiency, high salinity, or heavy metal toxicity, whereas LSU1 overexpression confers significant disease resistance in several of these conditions. Our data suggest that the network hub LSU1 plays an important role in co-ordinating plant immune responses across a spectrum of abiotic stress conditions. PMID:28207043

  5. CO2 Dissociation by Low Current Gliding Discharge in the Reverse Vortex Flow

    NASA Astrophysics Data System (ADS)

    Gutsol, Alexander

    2012-10-01

    If performed with high energy efficiency, plasma-chemical dissociation of carbon dioxide can be a way of converting and storing energy when there is an excess of electric energy, for example generated by solar elements of wind turbines. CO2 dissociation with efficiency of up to 90% was reported earlier for low pressure microwave discharge in supersonic flow. A new plasma-chemical system uses a low current gliding discharge in the reverse vortex flow of plasma gas. The system is a development of the Gliding Arc in Tornado reactor. The system was used to study dissociation of CO2 in wide ranges of the following experimental parameters: reactor pressure (15-150 kPa), discharge current (50-500 mA), gas flow rate (3-30 liters per minute), and electrode gap length (1-10 cm). Additionally, the effect of thermal energy recuperation on CO2 dissociation efficiency was tested. Plasma chemical efficiency of CO2 dissociation is very low (about 3%) in a short discharge at low pressures (about 15 kPa) when it is defined by electronic excitation. The highest efficiency (above 40%) was reached at pressures 50-70 kPa in a long discharge with thermal energy recuperation. It means that the process is controlled by thermal dissociation with subsequent effective quenching. Plasma chemical efficiency was determined from the data of chromatographic analysis and oscilloscope electric power integration, and also was checked calorimetrically by the thermal balance of the system.

  6. Effect of H2 and redox condition on biotic and abiotic MTBE transformation

    USGS Publications Warehouse

    Bradley, P.M.; Chapelle, F.H.; Landmeyer, J.E.

    2006-01-01

    Laboratory studies conducted with surface water sediment from a methyl tert-butyl ether (MTBE)-contaminated site in South Carolina demonstrated that, under methanogenic conditions, [U-14C] MTBE was transformed to 14C tert-butyl alcohol (TBA) with no measurable production of 14CO2. Production of TBA was not attributed to the activity of methanogenic microorganisms, however, because comparable transformation of [U-14C] MTBE to 14C-TBA also was observed in heat-sterilized controls with dissolved H2 concentrations > 5 nM. The results suggest that the transformation of MTBE to TBA may be an abiotic process that is driven by biologically produced H2 under in situ conditions. In contrast, mineralization of [U-14C] MTBE to 14CO2 was completely inhibited by heat sterilization and only observed in treatments characterized by dissolved H2 concentrations < 2 nM. These results suggest that the pathway of MTBE transformation is influenced by in situ H2 concentrations and that in situ H2 concentrations may be an useful indicator of MTBE transformation pathways in ground water systems.

  7. Determination of the equation parameters of carbon flow curves and estimated carbon flow and CO2 emissions from broiler production.

    PubMed

    Henn, J D; Bockor, L; Borille, R; Coldebella, A; Ribeiro, A M L; Kessler, A M

    2015-09-01

    The objective of this study was to determine the equation parameters of carbon (i.e., C) flow curves and to estimate C flow and carbon dioxide (i.e., CO2) emissions from the production of 1- to 49-day-old broilers from different genetic strains. In total, 384 1-day-old chicks were used, distributed into 4 groups: high-performance males (Cobb-M) and females (Cobb-F), and intermediate-performance males (C44-M) and females (C44-F), with 6 replicates/treatment according to a completely randomized study design. Carbon intake and retention were calculated based on diet and body C composition, and expired C was stoichiometrically estimated as digestible C intake-C retention-C in the urine. Litter C emission was estimated as initial litter C+C in the excreta-final litter C. Carbon flow curves were determined fitting data by nonlinear regression using the Gompertz function. Expired CO2 was calculated based on expired C. The applied nonlinear model presented goodness-of-fit for all responses (R2>0.99). Carbon dioxide production was highly correlated with growth rate. At 42 d age, CO2 expiration (g/bird) was 3,384.4 for Cobb-M, 2,947.9 for Cobb-F, 2,512.5 for C44-M, and 2185.1 for C44-F. Age also significantly affected CO2 production: to achieve 2.0 kg BW, CO2 expiration (g/bird) was 1,794.3 for Cobb-M, 2,016.5 for Cobb-F, 2617.7 for C44-M, and 3,092.3 for C44-F. The obtained equations present high predictability to estimate individual CO2 emissions in strains of Cobb and C44 broilers of any weight, or age, reared between 1 and 49 d age. © 2015 Poultry Science Association Inc.

  8. Hydrologic Responses to CO2 Injection in Basalts Based on Flow-through Experiments

    NASA Astrophysics Data System (ADS)

    Thomas, D.; Hingerl, F.; Garing, C.; Bird, D. K.; Benson, S. M.; Maher, K.

    2015-12-01

    Experimental studies of basalt-CO2 interactions have increased our ability to predict geochemical responses within a mafic reservoir during geologic CO2 sequestration. However, the lack of flow-through experiments prevents the use of coupled hydrologic-geochemical models to predict evolution of permeability and porosity, critical parameters for assessing storage feasibility. We present here results of three flow-through experiments on an intact basalt core during which we employed X-ray Computed Tomography (CT) to quantify porosity evolution and fluid flow. Using a single core of glassy basaltic tuff from the Snake River Plain (Menan Buttes complex), we performed tracer tests using a solution of NaI (~100,000 ppm) before and after injection of CO2-saturated water at reservoir conditions (90 bar, 50°C) to image porosity and flow path distribution. During the tracer tests, CT scans were taken at 2.5-minute intervals, and outlet fluid was discretely sampled at the same intervals and subsequently measured via ICP-MS, enabling interpretation of the tracer breakthrough curve through both imaging and geochemical analyses. Comparison of the porosity distribution from before and after injection of CO2 shows an overall decrease in core-averaged porosity from 34% to 31.1%. Permeability decreased exponentially from ~4.9x10-12 m2 to 1.18 x10-12 m2. The decrease in porosity and permeability suggests geochemical transformations in the mineral assemblage of the core, which we observe through petrographic analysis of an unaltered sample of the same lithology in contrast with the altered core. There is a significant increase in grain coatings, as well as reduction in the grain size, suggesting dissolution re-precipitation mechanisms. Finally, to develop a framework for the coupled geochemical and hydrologic responses observed experimentally, we have calibrated a reactive transport model at the core scale using the TOUGHREACT simulator [1]. [1] Xu et al. (2011) Comput. Geosci.

  9. Estimating reservoir permeability from gravity current modeling of CO2 flow at Sleipner storage project, North Sea

    NASA Astrophysics Data System (ADS)

    Cowton, L. R.; Neufeld, J. A.; Bickle, M.; White, N.; White, J.; Chadwick, A.

    2017-12-01

    Vertically-integrated gravity current models enable computationally efficient simulations of CO2 flow in sub-surface reservoirs. These simulations can be used to investigate the properties of reservoirs by minimizing differences between observed and modeled CO2 distributions. At the Sleipner project, about 1 Mt yr-1 of supercritical CO2 is injected at a depth of 1 km into a pristine saline aquifer with a thick shale caprock. Analysis of time-lapse seismic reflection surveys shows that CO2 is distributed within 9 discrete layers. The trapping mechanism comprises a stacked series of 1 m thick, impermeable shale horizons that are spaced at 30 m intervals through the reservoir. Within the stratigraphically highest reservoir layer, Layer 9, a submarine channel deposit has been mapped on the pre-injection seismic survey. Detailed measurements of the three-dimensional CO2 distribution within Layer 9 have been made using seven time-lapse surveys, providing a useful benchmark against which numerical flow simulations can be tested. Previous simulations have, in general, been largely unsuccessful in matching the migration rate of CO2 in this layer. Here, CO2 flow within Layer 9 is modeled as a vertically-integrated gravity current that spreads beneath a structurally complex caprock using a two-dimensional grid, considerably increasing computational efficiency compared to conventional three-dimensional simulators. This flow model is inverted to find the optimal reservoir permeability in Layer 9 by minimizing the difference between observed and predicted distributions of CO2 as a function of space and time. A three parameter inverse model, comprising reservoir permeability, channel permeability and channel width, is investigated by grid search. The best-fitting reservoir permeability is 3 Darcys, which is consistent with measurements made on core material from the reservoir. Best-fitting channel permeability is 26 Darcys. Finally, the ability of this simplified numerical model

  10. Impacts of 3 years of elevated atmospheric CO2 on rhizosphere carbon flow and microbial community dynamics.

    PubMed

    Drigo, Barbara; Kowalchuk, George A; Knapp, Brigitte A; Pijl, Agata S; Boschker, Henricus T S; van Veen, Johannes A

    2013-02-01

    Carbon (C) uptake by terrestrial ecosystems represents an important option for partially mitigating anthropogenic CO2 emissions. Short-term atmospheric elevated CO2 exposure has been shown to create major shifts in C flow routes and diversity of the active soil-borne microbial community. Long-term increases in CO2 have been hypothesized to have subtle effects due to the potential adaptation of soil microorganism to the increased flow of organic C. Here, we studied the effects of prolonged elevated atmospheric CO2 exposure on microbial C flow and microbial communities in the rhizosphere. Carex arenaria (a nonmycorrhizal plant species) and Festuca rubra (a mycorrhizal plant species) were grown at defined atmospheric conditions differing in CO2 concentration (350 and 700 ppm) for 3 years. During this period, C flow was assessed repeatedly (after 6 months, 1, 2, and 3 years) by (13) C pulse-chase experiments, and label was tracked through the rhizosphere bacterial, general fungal, and arbuscular mycorrhizal fungal (AMF) communities. Fatty acid biomarker analyses and RNA-stable isotope probing (RNA-SIP), in combination with real-time PCR and PCR-DGGE, were used to examine microbial community dynamics and abundance. Throughout the experiment the influence of elevated CO2 was highly plant dependent, with the mycorrhizal plant exerting a greater influence on both bacterial and fungal communities. Biomarker data confirmed that rhizodeposited C was first processed by AMF and subsequently transferred to bacterial and fungal communities in the rhizosphere soil. Over the course of 3 years, elevated CO2 caused a continuous increase in the (13) C enrichment retained in AMF and an increasing delay in the transfer of C to the bacterial community. These results show that, not only do elevated atmospheric CO2 conditions induce changes in rhizosphere C flow and dynamics but also continue to develop over multiple seasons, thereby affecting terrestrial ecosystems C utilization processes

  11. Future Climate CO2 Levels Mitigate Stress Impact on Plants: Increased Defense or Decreased Challenge?

    PubMed Central

    AbdElgawad, Hamada; Zinta, Gaurav; Beemster, Gerrit T. S.; Janssens, Ivan A.; Asard, Han

    2016-01-01

    Elevated atmospheric CO2 can stimulate plant growth by providing additional C (fertilization effect), and is observed to mitigate abiotic stress impact. Although, the mechanisms underlying the stress mitigating effect are not yet clear, increased antioxidant defenses, have been held primarily responsible (antioxidant hypothesis). A systematic literature analysis, including “all” papers [Web of Science (WoS)-cited], addressing elevated CO2 effects on abiotic stress responses and antioxidants (105 papers), confirms the frequent occurrence of the stress mitigation effect. However, it also demonstrates that, in stress conditions, elevated CO2 is reported to increase antioxidants, only in about 22% of the observations (e.g., for polyphenols, peroxidases, superoxide dismutase, monodehydroascorbate reductase). In most observations, under stress and elevated CO2 the levels of key antioxidants and antioxidant enzymes are reported to remain unchanged (50%, e.g., ascorbate peroxidase, catalase, ascorbate), or even decreased (28%, e.g., glutathione peroxidase). Moreover, increases in antioxidants are not specific for a species group, growth facility, or stress type. It seems therefore unlikely that increased antioxidant defense is the major mechanism underlying CO2-mediated stress impact mitigation. Alternative processes, probably decreasing the oxidative challenge by reducing ROS production (e.g., photorespiration), are therefore likely to play important roles in elevated CO2 (relaxation hypothesis). Such parameters are however rarely investigated in connection with abiotic stress relief. Understanding the effect of elevated CO2 on plant growth and stress responses is imperative to understand the impact of climate changes on plant productivity. PMID:27200030

  12. Site-specific 15N isotopic signatures of abiotically produced N2O

    NASA Astrophysics Data System (ADS)

    Heil, Jannis; Wolf, Benjamin; Brüggemann, Nicolas; Emmenegger, Lukas; Tuzson, Béla; Vereecken, Harry; Mohn, Joachim

    2014-08-01

    Efficient nitrous oxide (N2O) mitigation strategies require the identification of the main source and sink processes and their contribution to total soil N2O production. Several abiotic reactions of nitrification intermediates leading to N2O production are known, but their contribution to total N2O production in soils is uncertain. As the site preference (SP) of 15N in N2O is a promising tool to give more insight into N2O production processes, we investigated the SP of N2O produced by different abiotic reactions in a laboratory study. All reactions involved the nitrification intermediate hydroxylamine (NH2OH) in combination with nitrite (NO2-), Fe3+, Fe2+ and Cu2+, reactants commonly or potentially found in soils, at different concentrations and pH values. N2O production and its four main isotopic species (14N14N16O, 15N14N16O, 14N15N16O, and 14N14N18O) were quantified simultaneously and online at high temporal resolution using quantum cascade laser absorption spectroscopy. Thereby, our study presents the first continuous analysis of δ18O in N2O. The experiments revealed the possibility of purely abiotic reactions over a wide range of acidity (pH 3-8) by different mechanisms. All studied abiotic pathways produced N2O with a characteristic SP in the range of 34-35‰, unaffected by process conditions and remaining constant over the course of the experiments. These findings reflect the benefit of continuous N2O isotopic analysis by laser spectroscopy, contribute new information to the challenging source partitioning of N2O emissions from soils, and emphasize the potentially significant role of coupled biotic-abiotic reactions in soils.

  13. Membraneless laminar flow cell for electrocatalytic CO 2 reduction with liquid product separation

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

    Monroe, Morgan M.; Lobaccaro, Peter; Lum, Yanwei

    The production of liquid fuel products via electrochemical reduction of CO 2 is a potential path to produce sustainable fuels. However, to be practical, a separation strategy is required to isolate the fuel-containing electrolyte produced at the cathode from the anode and also prevent the oxidation products (i.e. O 2) from reaching the cathode. Ion-conducting membranes have been applied in CO 2 reduction reactors to achieve this separation, but they represent an efficiency loss and can be permeable to some product species. An alternative membraneless approach is developed here to maintain product separation through the use of a laminar flowmore » cell. Computational modelling shows that near-unity separation efficiencies are possible at current densities achievable now with metal cathodes via optimization of the spacing between the electrodes and the electrolyte flow rate. Laminar flow reactor prototypes were fabricated with a range of channel widths by 3D printing. CO 2 reduction to formic acid on Sn electrodes was used as the liquid product forming reaction, and the separation efficiency for the dissolved product was evaluated with high performance liquid chromatography. Trends in product separation efficiency with channel width and flow rate were in qualitative agreement with the model, but the separation efficiency was lower, with a maximum value of 90% achieved.« less

  14. Membraneless laminar flow cell for electrocatalytic CO 2 reduction with liquid product separation

    DOE PAGES

    Monroe, Morgan M.; Lobaccaro, Peter; Lum, Yanwei; ...

    2017-03-16

    The production of liquid fuel products via electrochemical reduction of CO 2 is a potential path to produce sustainable fuels. However, to be practical, a separation strategy is required to isolate the fuel-containing electrolyte produced at the cathode from the anode and also prevent the oxidation products (i.e. O 2) from reaching the cathode. Ion-conducting membranes have been applied in CO 2 reduction reactors to achieve this separation, but they represent an efficiency loss and can be permeable to some product species. An alternative membraneless approach is developed here to maintain product separation through the use of a laminar flowmore » cell. Computational modelling shows that near-unity separation efficiencies are possible at current densities achievable now with metal cathodes via optimization of the spacing between the electrodes and the electrolyte flow rate. Laminar flow reactor prototypes were fabricated with a range of channel widths by 3D printing. CO 2 reduction to formic acid on Sn electrodes was used as the liquid product forming reaction, and the separation efficiency for the dissolved product was evaluated with high performance liquid chromatography. Trends in product separation efficiency with channel width and flow rate were in qualitative agreement with the model, but the separation efficiency was lower, with a maximum value of 90% achieved.« less

  15. Optimization of Operation Parameters for Helical Flow Cleanout with Supercritical CO2 in Horizontal Wells Using Back-Propagation Artificial Neural Network.

    PubMed

    Song, Xianzhi; Peng, Chi; Li, Gensheng; He, Zhenguo; Wang, Haizhu

    2016-01-01

    Sand production and blockage are common during the drilling and production of horizontal oil and gas wells as a result of formation breakdown. The use of high-pressure rotating jets and annular helical flow is an effective way to enhance horizontal wellbore cleanout. In this paper, we propose the idea of using supercritical CO2 (SC-CO2) as washing fluid in water-sensitive formation. SC-CO2 is manifested to be effective in preventing formation damage and enhancing production rate as drilling fluid, which justifies tis potential in wellbore cleanout. In order to investigate the effectiveness of SC-CO2 helical flow cleanout, we perform the numerical study on the annular flow field, which significantly affects sand cleanout efficiency, of SC-CO2 jets in horizontal wellbore. Based on the field data, the geometry model and mathematical models were built. Then a numerical simulation of the annular helical flow field by SC-CO2 jets was accomplished. The influences of several key parameters were investigated, and SC-CO2 jets were compared to conventional water jets. The results show that flow rate, ambient temperature, jet temperature, and nozzle assemblies play the most important roles on wellbore flow field. Once the difference between ambient temperatures and jet temperatures is kept constant, the wellbore velocity distributions will not change. With increasing lateral nozzle size or decreasing rear/forward nozzle size, suspending ability of SC-CO2 flow improves obviously. A back-propagation artificial neural network (BP-ANN) was successfully employed to match the operation parameters and SC-CO2 flow velocities. A comprehensive model was achieved to optimize the operation parameters according to two strategies: cost-saving strategy and local optimal strategy. This paper can help to understand the distinct characteristics of SC-CO2 flow. And it is the first time that the BP-ANN is introduced to analyze the flow field during wellbore cleanout in horizontal wells.

  16. Optimization of Operation Parameters for Helical Flow Cleanout with Supercritical CO2 in Horizontal Wells Using Back-Propagation Artificial Neural Network

    PubMed Central

    Song, Xianzhi; Peng, Chi; Li, Gensheng

    2016-01-01

    Sand production and blockage are common during the drilling and production of horizontal oil and gas wells as a result of formation breakdown. The use of high-pressure rotating jets and annular helical flow is an effective way to enhance horizontal wellbore cleanout. In this paper, we propose the idea of using supercritical CO2 (SC-CO2) as washing fluid in water-sensitive formation. SC-CO2 is manifested to be effective in preventing formation damage and enhancing production rate as drilling fluid, which justifies tis potential in wellbore cleanout. In order to investigate the effectiveness of SC-CO2 helical flow cleanout, we perform the numerical study on the annular flow field, which significantly affects sand cleanout efficiency, of SC-CO2 jets in horizontal wellbore. Based on the field data, the geometry model and mathematical models were built. Then a numerical simulation of the annular helical flow field by SC-CO2 jets was accomplished. The influences of several key parameters were investigated, and SC-CO2 jets were compared to conventional water jets. The results show that flow rate, ambient temperature, jet temperature, and nozzle assemblies play the most important roles on wellbore flow field. Once the difference between ambient temperatures and jet temperatures is kept constant, the wellbore velocity distributions will not change. With increasing lateral nozzle size or decreasing rear/forward nozzle size, suspending ability of SC-CO2 flow improves obviously. A back-propagation artificial neural network (BP-ANN) was successfully employed to match the operation parameters and SC-CO2 flow velocities. A comprehensive model was achieved to optimize the operation parameters according to two strategies: cost-saving strategy and local optimal strategy. This paper can help to understand the distinct characteristics of SC-CO2 flow. And it is the first time that the BP-ANN is introduced to analyze the flow field during wellbore cleanout in horizontal wells. PMID

  17. 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

  18. LSU network hubs integrate abiotic and biotic stress responses via interaction with the superoxide dismutase FSD2.

    PubMed

    Garcia-Molina, Antoni; Altmann, Melina; Alkofer, Angela; Epple, Petra M; Dangl, Jeffery L; Falter-Braun, Pascal

    2017-02-01

    In natural environments, plants often experience different stresses simultaneously, and adverse abiotic conditions can weaken the plant immune system. Interactome mapping revealed that the LOW SULPHUR UPREGULATED (LSU) proteins are hubs in an Arabidopsis protein interaction network that are targeted by virulence effectors from evolutionarily diverse pathogens. Here we show that LSU proteins are up-regulated in several abiotic and biotic stress conditions, such as nutrient depletion or salt stress, by both transcriptional and post-translational mechanisms. Interference with LSU expression prevents chloroplastic reactive oxygen species (ROS) production and proper stomatal closure during sulphur stress. We demonstrate that LSU1 interacts with the chloroplastic superoxide dismutase FSD2 and stimulates its enzymatic activity in vivo and in vitro. Pseudomonas syringae virulence effectors interfere with this interaction and preclude re-localization of LSU1 to chloroplasts. We demonstrate that reduced LSU levels cause a moderately enhanced disease susceptibility in plants exposed to abiotic stresses such as nutrient deficiency, high salinity, or heavy metal toxicity, whereas LSU1 overexpression confers significant disease resistance in several of these conditions. Our data suggest that the network hub LSU1 plays an important role in co-ordinating plant immune responses across a spectrum of abiotic stress conditions. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  19. Methane clumped isotopes in the Songliao Basin (China): New insights into abiotic vs. biotic hydrocarbon formation

    NASA Astrophysics Data System (ADS)

    Shuai, Yanhua; Etiope, Giuseppe; Zhang, Shuichang; Douglas, Peter M. J.; Huang, Ling; Eiler, John M.

    2018-01-01

    Abiotic hydrocarbon gas, typically generated in serpentinized ultramafic rocks and crystalline shields, has important implications for the deep biosphere, petroleum systems, the carbon cycle and astrobiology. Distinguishing abiotic gas (produced by chemical reactions like Sabatier synthesis) from biotic gas (produced from degradation of organic matter or microbial activity) is sometimes challenging because their isotopic and molecular composition may overlap. Abiotic gas has been recognized in numerous locations on the Earth, although there are no confirmed instances where it is the dominant source of commercially valuable quantities in reservoir rocks. The deep hydrocarbon reservoirs of the Xujiaweizi Depression in the Songliao Basin (China) have been considered to host significant amounts of abiotic methane. Here we report methane clumped-isotope values (Δ18) and the isotopic composition of C1-C3 alkanes, CO2 and helium of five gas samples collected from those Xujiaweizi deep reservoirs. Some geochemical features of these samples resemble previously suggested identifiers of abiotic gas (13C-enriched CH4; decrease in 13C/12C ratio with increasing carbon number for the C1-C4 alkanes; abundant, apparently non-biogenic CO2; and mantle-derived helium). However, combining these constraints with new measurements of the clumped-isotope composition of methane and careful consideration of the geological context, suggests that the Xujiaweizi depression gas is dominantly, if not exclusively, thermogenic and derived from over-mature source rocks, i.e., from catagenesis of buried organic matter at high temperatures. Methane formation temperatures suggested by clumped-isotopes (167-213 °C) are lower than magmatic gas generation processes and consistent with the maturity of local source rocks. Also, there are no geological conditions (e.g., serpentinized ultramafic rocks) that may lead to high production of H2 and thus abiotic production of CH4 via CO2 reduction. We propose

  20. Changes in migration mode of brine and supercritical CO2 in imbibition process under steady flow state of very slow fluid velocities

    NASA Astrophysics Data System (ADS)

    Kogure, Tetsuya; Zhang, Yi; Nishizawa, Osamu; Xue, Ziqiu

    2018-05-01

    Relative permeability curves and flow mechanisms of CO2 and brine in Berea sandstone were investigated during a two-phase flow imbibition process, where CO2 saturation in the rock decreased from 55 per cent to 9 per cent by stepwise decrease of CO2/brine injection ratios. Total fluid flow velocity was 4.25 × 10-6 m/s, corresponding to the capillary number of order ˜10-8 for CO2 flow. The relative permeability curves showed a slight hysteresis compared to those during the drainage process. Local CO2 saturation and the differential pressure showed temporal fluctuations when the average differential pressure showed constant values or very small trends. The fluctuations in local CO2 saturation correlate with local porosity distributions. The differential pressure between the inlet and outlet ends showed the largest fluctuation when the CO2/brine ratio equals to one. A final brine-only injection resulted in more CO2 trapped within low porosity zones. These results suggest important roles of ganglion dynamics in the low flow rate ranges, where fluid pathways undergo repetitive brine snap-off and coalescence of CO2 ganglia that causes morphological changes in distributions of CO2 pathways.

  1. Numerical analysis of radial inward flow turbine for CO2 based closed loop Brayton cycle

    NASA Astrophysics Data System (ADS)

    Kisan, Jadhav Amit; Govardhan, M.

    2017-06-01

    Last few decades have witnessed a phenomenal growth in the demand for power, which has driven the suppliers to find new sources of energy and increase the efficiency of power generation process. Power generation cycles are either steam based Rankine cycle or closed loop Brayton cycles providing an efficiency of 30 to 40%. An upcoming technology in this regard is the CO2 based Brayton cycle operating near the critical region which has applications in vast areas. Power generation of CO2 based Brayton cycle can vary from few kilowatts for waste heat recovery to hundreds of megawatts in sodium cooled fast reactors. A CO2 based Brayton cycle is being studied for power generation especially in mid-sized concentrated solar power plants by numerous research groups around the world. One of the main components of such a setting is its turbine. Simulating the flow conditions inside the turbine becomes very crucial in order to accurately predict the performance of the system. The flow inside radial inflow turbine is studied at various inlet temperatures and mass flow rates in order to predict the behavior of the turbine under various boundary conditions. The performance investigation of the turbine system is done on the basis of parameters such as total efficiency, pressure ratio, and power coefficient. Effect of different inlet stagnation temperature and exit mass flow rates on these parameters is also studied. Results obtained are encouraging for the use of CO2 as working fluid in Brayton cycle.

  2. Bacteria in deep coastal plain sediments of Maryland: A possible source of CO2 to groundwater

    NASA Astrophysics Data System (ADS)

    Chapelle, Francis H.; Zelibor, Joseph L., Jr.; Grimes, D. Jay; Knobel, Leroy L.

    1987-08-01

    Nineteen cores of unconsolidated Coastal Plain sediments obtained from depths of 14 to 182 m below land surface near Waldorf, Maryland, were collected and examined for metabolically active bacteria. The age of the sediments cored range from Miocene to Early Cretaceous. Acridine orange direct counts of total (viable and nonviable) bacteria in core subsamples ranged from 108 to 104 bacteria/g of dry sediment. Direct counts of viable bacteria ranged from 106 to 103 bacteria/g of dry sediment. Three cores contained viable methanogenic bacteria, and seven cores contained viable sulfate-reducing bacteria. The observed presence of bacteria in these sediments suggest that heterotrophic bacterial metabolism, with lignitic organic material as the primary substrate, is a plausible source of CO2 to groundwater. However, the possibility that abiotic processes also produce CO2 cannot be ruled out. Estimated rates of CO2 production in the noncalcareous Magothy/Upper Patapsco and Lower Patapsco aquifers based on mass balance of dissolved inorganic carbon, groundwater flow rates, and flow path segment lengths are in the range 10-3 to 10-5 mmol L-1 yr-1. Isotope balance calculations suggest that aquifer-generated CO2 is much heavier isotopically (˜—10 to + 5 per mil) than lignite (˜-24 per mil) present in these sediments. This may reflect isotopic fractionation during methanogenesis and possibly other bacterially mediated processes.

  3. Effect of Feed Gas Flow Rate on CO2 Absorption through Super Hydrophobic Hollow Fiber membrane Contactor

    NASA Astrophysics Data System (ADS)

    Kartohardjono, Sutrasno; Alexander, Kevin; Larasati, Annisa; Sihombing, Ivander Christian

    2018-03-01

    Carbon dioxide is pollutant in natural gas that could reduce the heating value of the natural gas and cause problem in transportation due to corrosive to the pipeline. This study aims to evaluate the effects of feed gas flow rate on CO2 absorption through super hydrophobic hollow fiber contactor. Polyethyleneglycol-300 (PEG-300) solution was used as absorbent in this study, whilst the feed gas used in the experiment was a mixture of 30% CO2 and 70% CH4. There are three super hydrophobic hollow fiber contactors sized 6 cm and 25 cm in diameter and length used in this study, which consists of 1000, 3000 and 5000 fibers, respectively. The super hydrophobic fiber membrane used is polypropylene-based with outer and inner diameter of about 525 and 235 μm, respectively. In the experiments, the feed gas was sent through the shell side of the membrane contactor, whilst the absorbent solution was pumped through the lumen fibers. The experimental results showed that the mass transfer coefficient, flux, absorption efficiency for CO2-N2 system and CO2 loading increased with the feed gas flow rate, but the absorption efficiency for CO2-N2 system decreased. The mass transfer coefficient and the flux, at the same feed gas flow rate, decreased with the number of fibers in the membrane contactor, but the CO2 absorption efficiency and the CO2 loading increased.

  4. Post-injection Multiphase Flow Modeling and Risk Assessments for Subsurface CO2 Storage in Naturally Fractured Reservoirs

    NASA Astrophysics Data System (ADS)

    Jin, G.

    2015-12-01

    Subsurface storage of carbon dioxide in geological formations is widely regarded as a promising tool for reducing global atmospheric CO2 emissions. Successful geologic storage for sequestrated carbon dioxides must prove to be safe by means of risk assessments including post-injection analysis of injected CO2 plumes. Because fractured reservoirs exhibit a higher degree of heterogeneity, it is imperative to conduct such simulation studies in order to reliably predict the geometric evolution of plumes and risk assessment of post CO2injection. The research has addressed the pressure footprint of CO2 plumes through the development of new techniques which combine discrete fracture network and stochastic continuum modeling of multiphase flow in fractured geologic formations. A subsequent permeability tensor map in 3-D, derived from our preciously developed method, can accurately describe the heterogeneity of fracture reservoirs. A comprehensive workflow integrating the fracture permeability characterization and multiphase flow modeling has been developed to simulate the CO2plume migration and risk assessments. A simulated fractured reservoir model based on high-priority geological carbon sinks in central Alabama has been employed for preliminary study. Discrete fracture networks were generated with an NE-oriented regional fracture set and orthogonal NW-fractures. Fracture permeability characterization revealed high permeability heterogeneity with an order of magnitude of up to three. A multiphase flow model composed of supercritical CO2 and saline water was then applied to predict CO2 plume volume, geometry, pressure footprint, and containment during and post injection. Injection simulation reveals significant permeability anisotropy that favors development of northeast-elongate CO2 plumes, which are aligned with systematic fractures. The diffusive spreading front of the CO2 plume shows strong viscous fingering effects. Post-injection simulation indicates significant

  5. Stable Carbon Isotopic Signatures of Abiotic Organics from Hydrothermal Synthesis Experiments

    NASA Technical Reports Server (NTRS)

    Stern, Jennifer C.; Summers, David P.; Kubo, Mike; Yassar, Saima

    2006-01-01

    Stable carbon isotopes can be powerful biogeochemical markers in the study of life's origins. Biogenic carbon fixation produces organics that are depleted in C-13 by about -20 to -30%0. Less attention has been paid to the isotopic signatures of abiotic processes. The possibility of abiotic processes producing organics with morphologies and isotopic signatures in the biogenic range has been at the center of recent debate over the Earth's earliest microfossils. The abiotic synthesis of organic compounds in hydrothermal environments is one possible source of endogenous organic matter to the prebiotic earth. Simulated hydrothermal settings have been shown to synthesize, among other things, single chain amphiphiles and simple lipids from a mix of CO, CO2, and H2. A key characteristic of these amphiphilic molecules is the ability to self-assemble in aqueous phases into more organized structures called vesicles, which form a selectively permeable boundary and serve the function of containing and concentrating other organic molecules. The ability to form cell like structures also makes these compounds more likely to be mistaken for biogenic. Hydrothermal simulation experiments were conducted from oxalic or formic acid in water at 175 C for 72 hr. The molecular and isotopic composition of the products of these reactions were determined and compared to biogenic fractionations . Preliminary results indicate isotopic fractionation during abiotic hydrocarbon synthesis in hydrothermal environments is on par with biological carbon fixation.

  6. Quantifying the Effects of Spatial Uncertainty in Fracture Permeability on CO2 Leakage through Columbia River Basalt Flow Interiors

    NASA Astrophysics Data System (ADS)

    Gierzynski, A.; Pollyea, R.

    2016-12-01

    Recent studies suggest that continental flood basalts may be suitable for geologic carbon sequestration, due to fluid-rock reactions that mineralize injected CO2 on relatively short time-scales. Flood basalts also possess a morphological structure conducive to injection, with alternating high-permeability (flow margin) and low-permeability (flow interior) layers. However, little information exists on the behavior of CO2 migration within field-scale fracture networks, particularly within flow interiors and at conditions near the critical point for CO2. In this study, numerical simulation is used to investigate the influence of fracture permeability uncertainty during gravity-driven CO2 migration within a jointed basalt flow interior as CO2 undergoes phase change from supercritical fluid to a subcritical phase. The model domain comprises a 2D fracture network mapped with terrestrial LiDAR scans of Columbia River Basalt acquired near Starbuck, WA. The model domain is 5 m × 5 m with bimodal heterogeneity (fracture and matrix), and initial conditions corresponding to a hydrostatic pressure gradient between 750 and 755 m depth. Under these conditions, the critical point for CO2 occurs 1.5 m above the bottom of the domain. For this model scenario, CO2 enters the base of the fracture network at 0.5 MPa overpressure, and matrix permeability is assumed constant. Fracture permeability follows a lognormal distribution on the basis of fracture aperture values from literature. In order to account for spatial uncertainty, the lognormal fracture permeability distribution is randomly located in the model domain and CO2 migration is simulated within the same fracture network for 50 equally probable realizations. Model results suggest that fracture connectivity, which is independent of permeability distribution, governs the path taken by buoyant CO2 as it rises through the flow interior; however, the permeability distribution strongly governs the CO2 flux magnitude. In particular

  7. CO2 clearance by membrane lungs.

    PubMed

    Sun, Liqun; Kaesler, Andreas; Fernando, Piyumindri; Thompson, Alex J; Toomasian, John M; Bartlett, Robert H

    2018-05-01

    Commercial membrane lungs are designed to transfer a specific amount of oxygen per unit of venous blood flow. Membrane lungs are much more efficient at removing CO 2 than adding oxygen, but the range of CO 2 transfer is rarely reported. Commercial membrane lungs were studied with the goal of evaluating CO 2 removal capacity. CO 2 removal was measured in 4 commercial membrane lungs under standardized conditions. CO 2 clearance can be greater than 4 times that of oxygen at a given blood flow when the gas to blood flow ratio is elevated to 4:1 or 8:1. The CO 2 clearance was less dependent on surface area and configuration than oxygen transfer. Any ECMO system can be used for selective CO 2 removal.

  8. CFD convective flow simulation of the varying properties of CO2-H2O mixtures in geothermal systems.

    PubMed

    Yousefi, S; Atrens, A D; Sauret, E; Dahari, M; Hooman, K

    2015-01-01

    Numerical simulation of a geothermal reservoir, modelled as a bottom-heated square box, filled with water-CO2 mixture is presented in this work. Furthermore, results for two limiting cases of a reservoir filled with either pure water or CO2 are presented. Effects of different parameters including CO2 concentration as well as reservoir pressure and temperature on the overall performance of the system are investigated. It has been noted that, with a fixed reservoir pressure and temperature, any increase in CO2 concentration leads to better performance, that is, stronger convection and higher heat transfer rates. With a fixed CO2 concentration, however, the reservoir pressure and temperature can significantly affect the overall heat transfer and flow rate from the reservoir. Details of such variations are documented and discussed in the present paper.

  9. STABILITY OF CO{sub 2} ATMOSPHERES ON DESICCATED M DWARF EXOPLANETS

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

    Gao, Peter; Hu, Renyu; Li, Cheng

    2015-06-20

    We investigate the chemical stability of CO{sub 2}-dominated atmospheres of desiccated M dwarf terrestrial exoplanets using a one-dimensional photochemical model. Around Sun-like stars, CO{sub 2} photolysis by Far-UV (FUV) radiation is balanced by recombination reactions that depend on water abundance. Planets orbiting M dwarf stars experience more FUV radiation, and could be depleted in water due to M dwarfs’ prolonged, high-luminosity pre-main sequences. We show that, for water-depleted M dwarf terrestrial planets, a catalytic cycle relying on H{sub 2}O{sub 2} photolysis can maintain a CO{sub 2} atmosphere. However, this cycle breaks down for atmospheric hydrogen mixing ratios <1 ppm, resultingmore » in ∼40% of the atmospheric CO{sub 2} being converted to CO and O{sub 2} on a timescale of 1 Myr. The increased O{sub 2} abundance leads to high O{sub 3} concentrations, the photolysis of which forms another CO{sub 2}-regenerating catalytic cycle. For atmospheres with <0.1 ppm hydrogen, CO{sub 2} is produced directly from the recombination of CO and O. These catalytic cycles place an upper limit of ∼50% on the amount of CO{sub 2} that can be destroyed via photolysis, which is enough to generate Earth-like abundances of (abiotic) O{sub 2} and O{sub 3}. The conditions that lead to such high oxygen levels could be widespread on planets in the habitable zones of M dwarfs. Discrimination between biological and abiotic O{sub 2} and O{sub 3} in this case can perhaps be accomplished by noting the lack of water features in the reflectance and emission spectra of these planets, which necessitates observations at wavelengths longer than 0.95 μm.« less

  10. 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

  11. The Promoter of AtUSP Is Co-regulated by Phytohormones and Abiotic Stresses in Arabidopsis thaliana.

    PubMed

    Bhuria, Monika; Goel, Parul; Kumar, Sanjay; Singh, Anil K

    2016-01-01

    Universal stress proteins (USPs) are known to be expressed in response to various abiotic stresses in a wide variety of organisms, such as bacteria, archaebacteria, protists, algae, fungi, plants, and animals. However, in plants, biological function of most of the USPs still remains obscure. In the present study, Arabidopsis USP gene ( AtUSP ) showed induction in response to abscisic acid (ABA) and various abiotic stresses viz . heat, dehydration, salt, osmotic, and cold stresses. Additionally, in silico analysis of AtUSP promoter identified several cis -elements responsive to phytohormones and abiotic stresses such as ABRE, ERE, DRE, and HSE, etc. To functionally validate the AtUSP promoter, the 1115 bp region of promoter was characterized under phytohormone and abiotic stress treatments. Deletion analysis of promoter was carried out by cloning the full length promoter (D0) and its three 5' deletion derivatives, D1 (964 bp), D2 (660 bp), and D3 (503 bp) upstream of the β-glucuronidase (GUS) reporter gene, which were then stably transformed in Arabidopsis plants. The AtUSP promoter (D0) showed minimal activity under non-stress conditions which was enhanced in response to phytohormone treatments (ABA and ACC) and abiotic stresses such as dehydration, heat, cold, salt, and osmotic stresses. The seedlings harboring D1 and D2 deletion fragments showed constitutive GUS expression even under control condition with increased activity almost under all the treatments. However, D3 seedlings exhibited complete loss of activity under control condition with induction under ACC treatment, dehydration, heat, oxidative, salt, and osmotic stresses. Thus, present study clearly showed that AtUSP promoter is highly inducible by phytohormones and multiple abiotic stresses and it can be exploited as stress inducible promoter to generate multi-stress tolerant crops with minimal effects on their other important traits.

  12. Comparative Investigation on the Heat Transfer Characteristics of Gaseous CO2 and Gaseous Water Flowing Through a Single Granite Fracture

    NASA Astrophysics Data System (ADS)

    He, Yuanyuan; Bai, Bing; Li, Xiaochun

    2017-11-01

    CO2 and water are two commonly employed heat transmission fluids in several fields. Their temperature and pressure determine their phase states, thus affecting the heat transfer performance of the water/CO2. The heat transfer characteristics of gaseous CO2 and gaseous water flowing through fractured hot dry rock still need a great deal of investigation, in order to understand and evaluate the heat extraction in enhanced geothermal systems. In this work, we develop a 2D numerical model to compare the heat transfer performance of gaseous CO2 and gaseous water flowing through a single fracture aperture of 0.2 mm in a φ 50 × 50 mm cylindrical granite sample with a confining temperature of 200°C under different inlet mass flow rates. Our results indicate that: (1) the final outlet temperatures of the fluid are very close to the outer surface temperature under low inlet mass flow rate, regardless of the sample length. (2) Both the temperature of the fluid (gaseous CO2/gaseous water) and inner surface temperature rise sharply at the inlet, and the inner surface temperature is always higher than the fluid temperature. However, their temperature difference becomes increasingly small. (3) Both the overall heat transfer coefficient (OHTC) and local heat transfer coefficient (LHTC) of gaseous CO2 and gaseous water increase with increasing inlet mass flow rates. (4) Both the OHTC and LHTC of gaseous CO2 are lower than those of gaseous water under the same conditions; therefore, the heat mining performance of gaseous water is superior to gaseous CO2 under high temperature and low pressure.

  13. Micro-PIV measurements of multiphase flow of water and liquid CO2 in 2-D heterogeneous porous micromodels

    NASA Astrophysics Data System (ADS)

    Li, Yaofa; Kazemifar, Farzan; Blois, Gianluca; Christensen, Kenneth T.

    2017-07-01

    We present an experimental study of pore-scale flow dynamics of liquid CO2 and water in a two-dimensional heterogeneous porous micromodel, inspired by the structure of a reservoir rock, at reservoir-relevant conditions (80 bar, 21°C). The entire process of CO2 infiltration into a water-saturated micromodel was captured using fluorescence microscopy and the micro-PIV method, which together reveal complex fluid displacement patterns and abrupt changes in velocity. The CO2 front migrated through the resident water in an intermittent manner, forming dendritic structures, termed fingers, in directions along, normal to, and even opposing the bulk pressure gradient. Such characteristics indicate the dominance of capillary fingering through the micromodel. Velocity burst events, termed Haines jumps, were also captured in the heterogeneous micromodel, during which the local Reynolds number was estimated to be ˜21 in the CO2 phase, exceeding the range of validity of Darcy's law. Furthermore, these drainage events were observed to be cooperative (i.e., across multiple pores simultaneously), with the zone of influence of such events extending beyond tens of pores, confirming, in a quantitative manner, that Haines jumps are nonlocal phenomena. After CO2 completely breaks through the porous section, shear-induced circulations caused by flowing CO2 were also observed, in agreement with previous studies using a homogeneous porous micromodel. To our knowledge, this study is the first quantitative measurement that incorporates both reservoir-relevant conditions and rock-inspired heterogeneity, and thus will be useful for pore-scale model development and validation.

  14. CFD Convective Flow Simulation of the Varying Properties of CO2-H2O Mixtures in Geothermal Systems

    PubMed Central

    Yousefi, S.; Atrens, A. D.; Sauret, E.; Dahari, M.; Hooman, K.

    2015-01-01

    Numerical simulation of a geothermal reservoir, modelled as a bottom-heated square box, filled with water-CO2 mixture is presented in this work. Furthermore, results for two limiting cases of a reservoir filled with either pure water or CO2 are presented. Effects of different parameters including CO2 concentration as well as reservoir pressure and temperature on the overall performance of the system are investigated. It has been noted that, with a fixed reservoir pressure and temperature, any increase in CO2 concentration leads to better performance, that is, stronger convection and higher heat transfer rates. With a fixed CO2 concentration, however, the reservoir pressure and temperature can significantly affect the overall heat transfer and flow rate from the reservoir. Details of such variations are documented and discussed in the present paper. PMID:25879074

  15. Measured Fluid Flow in an Active H2O-CO2 Geothermal Well as an Analog to Fluid Flow in Fractures on Mars: Preliminary Report

    NASA Technical Reports Server (NTRS)

    Kieffer, Susan W.; Brown, K. L.; Simmons, Stuart F.; Watson, Arnold

    2004-01-01

    Water in the Earth's crust generally contains dissolved gases such as CO2. Models for both 'Blue Mars' (H2O-driven processes) and 'White Mars' (CO2-driven processes) predict liquid H2O with dissolved CO2 at depth. The fate of dissolved CO2 as this mixture rises toward the surface has not been quantitatively explored. Our approach is a variation on NASA's 'Follow the Water' as we 'Follow the Fluid' from depth to the surface in hydrothermal areas on Earth and extrapolate our results to Mars. This is a preliminary report on a field study of fluid flow in a producing geothermal well. For proprietary reasons, the name and location of this well cannot be revealed, so we have named it 'Earth1' for this study.

  16. Microbial dissolution of calcite at T = 28 °C and ambient pCO 2

    NASA Astrophysics Data System (ADS)

    Jacobson, Andrew D.; Wu, Lingling

    2009-04-01

    This study used batch reactors to quantify the mechanisms and rates of calcite dissolution in the presence and absence of a single heterotrophic bacterial species ( Burkholderia fungorum). Experiments were conducted at T = 28°C and ambient pCO 2 over time periods spanning either 21 or 35 days. Bacteria were supplied with minimal growth media containing either glucose or lactate as a C source, NH 4+ as an N source, and H 2PO 4- as a P source. Combining stoichiometric equations for microbial growth with an equilibrium mass-balance model of the H 2O-CO 2-CaCO 3 system demonstrates that B. fungorum affected calcite dissolution by modifying pH and alkalinity during utilization of ionic N and C species. Uptake of NH 4+ decreased pH and alkalinity, whereas utilization of lactate, a negatively charged organic anion, increased pH and alkalinity. Calcite in biotic glucose-bearing reactors dissolved by simultaneous reaction with H 2CO 3 generated by dissolution of atmospheric CO 2 (H 2CO 3 + CaCO 3 → Ca 2+ + 2HCO 3-) and H + released during NH 4+ uptake (H + + CaCO 3 → Ca 2+ + HCO 3-). Reaction with H 2CO 3 and H + supplied ˜45% and 55% of the total Ca 2+ and ˜60% and 40% of the total HCO 3-, respectively. The net rate of microbial calcite dissolution in the presence of glucose and NH 4+ was ˜2-fold higher than that observed for abiotic control experiments where calcite dissolved only by reaction with H 2CO 3. In lactate bearing reactors, most H + generated by NH 4+ uptake reacted with HCO 3- produced by lactate oxidation to yield CO 2 and H 2O. Hence, calcite in biotic lactate-bearing reactors dissolved by reaction with H 2CO 3 at a net rate equivalent to that calculated for abiotic control experiments. This study suggests that conventional carbonate equilibria models can satisfactorily predict the bulk fluid chemistry resulting from microbe-calcite interactions, provided that the ionic forms and extent of utilization of N and C sources can be constrained. Because

  17. Do elevated temperature and CO2 generally have counteracting effects on phenolic phytochemistry of boreal trees?

    Treesearch

    T.O. Veteli; W.J. Mattson; P. Niemela; R. Julkunen-Tiitto; S. Kellomaki; K. Kuokkanen; A. Lavola

    2007-01-01

    Global climate change includes concomitant changes in many components of the abiotic flux necessary for plant life. In this paper, we investigate the combined effects of elevated CO2 (720 ppm) and temperature (+2 K) on the phytochemistry of three deciduous tree species. The analysis revealed that elevated CO2 generally...

  18. The hysteresis response of soil CO 2 concentration and soil respiration to soil temperature

    DOE PAGES

    Zhang, Quan; Katul, Gabriel G.; Oren, Ram; ...

    2015-07-20

    Diurnal hysteresis between soil temperature (T s) and both CO 2 concentration ([CO 2]) and soil respiration rate (R s) were reported across different field experiments. However, the causes of these hysteresis patterns remain a subject of debate, with biotic and abiotic factors both invoked as explanations. Here, to address these issues, a CO 2 gas transport model is developed by combining a layer-wise mass conservation equation for subsurface gas phase CO 2, Fickian diffusion for gas transfer, and a CO 2 source term that depends on soil temperature, moisture, and photosynthetic rate. Using this model, a hierarchy of numericalmore » experiments were employed to disentangle the causes of the hysteretic [CO 2]-T s and CO 2 flux T s (i.e., F-T s) relations. Model results show that gas transport alone can introduce both [CO 2]-T s and F-T s hystereses and also confirm prior findings that heat flow in soils lead to [CO 2] and F being out of phase with T s, thereby providing another reason for the occurrence of both hystereses. The area (A hys) of the [CO 2]-T s hysteresis near the surface increases, while the A hys of the Rs-Ts hysteresis decreases as soils become wetter. Moreover, a time-lagged carbon input from photosynthesis deformed the [CO 2]-T s and R s-T s patterns, causing a change in the loop direction from counterclockwise to clockwise with decreasing time lag. An asymmetric 8-shaped pattern emerged as the transition state between the two loop directions. Lastly, tracing the pattern and direction of the hysteretic [CO 2]-T s and R s-T s relations can provide new ways to fingerprint the effects of photosynthesis stimulation on soil microbial activity and detect time lags between rhizospheric respiration and photosynthesis.« less

  19. Constraining Path-Dependent Processes During Basalt-CO2 Interactions with Observations From Flow-Through and Batch Experiments

    NASA Astrophysics Data System (ADS)

    Thomas, D.; Garing, C.; Zahasky, C.; Harrison, A. L.; Bird, D. K.; Benson, S. M.; Oelkers, E. H.; Maher, K.

    2017-12-01

    Predicting the timing and magnitude of CO2 storage in basaltic rocks relies partly on quantifying the dependence of reactivity on flow path and mineral distribution. Flow-through experiments that use intact cores are advantageous because the spatial heterogeneity of pore space and reactive phases is preserved. Combining aqueous geochemical analyses and petrologic characterization with non-destructive imaging techniques (e.g. micro-computed tomography) constrains the relationship between irreversible reactions, pore connectivity and accessible surface area. Our work enhances these capabilities by dynamically imaging flow through vesicular basalts with Positron Emission Tomography (PET) scanning. PET highlights the path a fluid takes by detecting photons produced during radioactive decay of an injected radiotracer (FDG). We have performed single-phase, CO2-saturated flow-through experiments with basaltic core from Iceland at CO2 sequestration conditions (50 °C; 76-90 bar Ptot). Constant flow rate and continuous pressure measurements at the inlet and outlet of the core constrain permeability. We monitor geochemical evolution through cation and anion analysis of outlet fluid sampled periodically. Before and after reaction, we perform PET scans and characterize the core using micro-CT. The PET scans indicate a discrete, localized flow path that appears to be a micro-crack connecting vesicles, suggesting that vesicle-lining minerals are immediately accessible and important reactants. Rapid increases in aqueous cation concentration, pH and HCO3- indicate that the rock reacts nearly immediately after CO2 injection. After 24 hours the solute release decreases, which may reflect a transition to reaction with phases with slower kinetic dissolution rates (e.g. zeolites and glasses to feldspar), a decrease in available reactive surface area or precipitation. We have performed batch experiments using crushed material of the same rock to elucidate the effect of flow path

  20. Impact of membrane lung surface area and blood flow on extracorporeal CO2 removal during severe respiratory acidosis.

    PubMed

    Karagiannidis, Christian; Strassmann, Stephan; Brodie, Daniel; Ritter, Philine; Larsson, Anders; Borchardt, Ralf; Windisch, Wolfram

    2017-12-01

    Veno-venous extracorporeal CO 2 removal (vv-ECCO 2 R) is increasingly being used in the setting of acute respiratory failure. Blood flow rates through the device range from 200 ml/min to more than 1500 ml/min, and the membrane surface areas range from 0.35 to 1.3 m 2 . The present study in an animal model with similar CO 2 production as an adult patient was aimed at determining the optimal membrane lung surface area and technical requirements for successful vv-ECCO 2 R. Four different membrane lungs, with varying lung surface areas of 0.4, 0.8, 1.0, and 1.3m 2 were used to perform vv-ECCO 2 R in seven anesthetized, mechanically ventilated, pigs with experimentally induced severe respiratory acidosis (pH 7.0-7.1) using a 20Fr double-lumen catheter with a sweep gas flow rate of 8 L/min. During each experiment, the blood flow was increased stepwise from 250 to 1000 ml/min. Amelioration of severe respiratory acidosis was only feasible when blood flow rates from 750 to 1000 ml/min were used with a membrane lung surface area of at least 0.8 m 2 . Maximal CO 2 elimination was 150.8 ml/min, with pH increasing from 7.01 to 7.30 (blood flow 1000 ml/min; membrane lung 1.3 m 2 ). The membrane lung with a surface of 0.4 m 2 allowed a maximum CO 2 elimination rate of 71.7 mL/min, which did not result in the normalization of pH, even with a blood flow rate of 1000 ml/min. Also of note, an increase of the surface area above 1.0 m 2 did not result in substantially higher CO 2 elimination rates. The pressure drop across the oxygenator was considerably lower (<10 mmHg) in the largest membrane lung, whereas the smallest revealed a pressure drop of more than 50 mmHg with 1000 ml blood flow/min. In this porcine model, vv-ECCO 2 R was most effective when using blood flow rates ranging between 750 and 1000 ml/min, with a membrane lung surface of at least 0.8 m 2 . In contrast, low blood flow rates (250-500 ml/min) were not sufficient to completely correct severe

  1. Elimination of laparoscopic lens fogging using directional flow of CO2.

    PubMed

    Calhoun, John Teague; Redan, Jay A

    2014-01-01

    Surgeons constantly struggle with the formation of condensation on the lens of a laparoscope, which prolongs procedures and reduces visibility of the abdominal cavity. The goal of this project was to build a device that would direct a flow of carbon dioxide (CO2) into an open chamber surrounding the lens of a laparoscope, acting to keep moisture away from the lens and eliminate condensation. The device isolates the lens of the laparoscope from the humid environment of the intraperitoneal cavity by creating a microenvironment of dry CO2. This was accomplished by building a communicating sleeve that created an open chamber around the distal 2 to 3 cm of the scope. Into this cavity, dry cool CO2 was pumped in from an insufflator so that the path of the gas would surround the lens of the scope and escape through a single outlet location through which the scope views the intraperitoneal cavity. This chamber is proposed to isolate the lens with a high percentage of dry CO2 and low humidity. The device was tested in 7 different adverse conditions that were meant to challenge the ability of the device to maintain the viewing field with no perceptible obstruction. In all of the conditions tested, 25 trials total, the device successfully prevented and/or eliminated laparoscopic lens fogging. The device designed for this project points to the potential of a simple and effective mechanical method for eliminating laparoscopic lens fogging.

  2. 40 CFR 98.473 - Calculating CO2 received.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    .... (a) You must calculate and report the annual mass of CO2 received by pipeline using the procedures in... applicable. (1) For a mass flow meter, you must calculate the total annual mass of CO2 in a CO2 stream received in metric tons by multiplying the mass flow by the CO2 concentration in the flow, according to...

  3. 40 CFR 98.473 - Calculating CO2 received.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    .... (a) You must calculate and report the annual mass of CO2 received by pipeline using the procedures in... applicable. (1) For a mass flow meter, you must calculate the total annual mass of CO2 in a CO2 stream received in metric tons by multiplying the mass flow by the CO2 concentration in the flow, according to...

  4. 40 CFR 98.473 - Calculating CO2 received.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    .... (a) You must calculate and report the annual mass of CO2 received by pipeline using the procedures in... applicable. (1) For a mass flow meter, you must calculate the total annual mass of CO2 in a CO2 stream received in metric tons by multiplying the mass flow by the CO2 concentration in the flow, according to...

  5. 40 CFR 98.473 - Calculating CO2 received.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    .... (a) You must calculate and report the annual mass of CO2 received by pipeline using the procedures in... applicable. (1) For a mass flow meter, you must calculate the total annual mass of CO2 in a CO2 stream received in metric tons by multiplying the mass flow by the CO2 concentration in the flow, according to...

  6. Modelling CO2 flow in naturally fractured geological media using MINC and multiple subregion upscaling procedure

    NASA Astrophysics Data System (ADS)

    Tatomir, Alexandru Bogdan A. C.; Flemisch, Bernd; Class, Holger; Helmig, Rainer; Sauter, Martin

    2017-04-01

    Geological storage of CO2 represents one viable solution to reduce greenhouse gas emission in the atmosphere. Potential leakage of CO2 storage can occur through networks of interconnected fractures. The geometrical complexity of these networks is often very high involving fractures occurring at various scales and having hierarchical structures. Such multiphase flow systems are usually hard to solve with a discrete fracture modelling (DFM) approach. Therefore, continuum fracture models assuming average properties are usually preferred. The multiple interacting continua (MINC) model is an extension of the classic double porosity model (Warren and Root, 1963) which accounts for the non-linear behaviour of the matrix-fracture interactions. For CO2 storage applications the transient representation of the inter-porosity two phase flow plays an important role. This study tests the accuracy and computational efficiency of the MINC method complemented with the multiple sub-region (MSR) upscaling procedure versus the DFM. The two phase flow MINC simulator is implemented in the free-open source numerical toolbox DuMux (www.dumux.org). The MSR (Gong et al., 2009) determines the inter-porosity terms by solving simplified local single-phase flow problems. The DFM is considered as the reference solution. The numerical examples consider a quasi-1D reservoir with a quadratic fracture system , a five-spot radial symmetric reservoir, and a completely random generated fracture system. Keywords: MINC, upscaling, two-phase flow, fractured porous media, discrete fracture model, continuum fracture model

  7. High efficiency of CO2-activated graphite felt as electrode for vanadium redox flow battery application

    NASA Astrophysics Data System (ADS)

    Chang, Yu-Chung; Chen, Jian-Yu; Kabtamu, Daniel Manaye; Lin, Guan-Yi; Hsu, Ning-Yih; Chou, Yi-Sin; Wei, Hwa-Jou; Wang, Chen-Hao

    2017-10-01

    A simple method for preparing CO2-activated graphite felt as an electrode in a vanadium redox flow battery (VRFB) was employed by the direct treatment in a CO2 atmosphere at a high temperature for a short period. The CO2-activated graphite felt demonstrates excellent electrochemical activity and reversibility. The VRFB using the CO2-activated graphite felts in the electrodes has coulombic, voltage, and energy efficiencies of 94.52%, 88.97%, and 84.15%, respectively, which is much higher than VRFBs using the electrodes of untreated graphite felt and N2-activated graphite felt. The efficiency enhancement was attributed to the higher number of oxygen-containing functional groups on the graphite felt that are formed during the CO2-activation, leading to improving the electrochemical behaviour of the resultant VRFB.

  8. Mass transfers induced by flow of CO2 rich-brine through fractured cement: experiment and modeling

    NASA Astrophysics Data System (ADS)

    Habdoulghafour, H.; Luquot, L.; Gouze, P.

    2011-12-01

    Long-term confinement failure is a key issue in the assessment of the confidence levels of CO2 storage. Evaluating the potential for CO2 leakage through wells (casing, cements and interfaces with the cap-rock) is of primary importance for the analysis of latent and short-range risks of confinement failure. Some controversy remains regarding the risk of conventional cements. While some researchers argue that they may fail, EOR oil industry experience suggests the opposite. The issue is non-trivial. Experimental investigations on cement alteration mechanism triggered by CO2-rich brine show that both carbonation and de-carbonation mechanisms may occur and are the dominant mass exchange processes. It is tempting to conclude from the results of batch experiments that cement carbonation tends to decrease porosity and permeability, whereas de-carbonation increases both, but these assumptions must be tested using realistic flow-through experiments. Here we investigated the effect of CO2 rich-brine flowing through fractured portlandite-rich cement plugs. Experiments were carried out under realistic in situ conditions (T=80°C and P=10 MPa). Monitoring the fluid composition at the outlet allows us to measure the rate at which portlandite and CSH are dissolved and Ca-carbonate (calcite) precipitated. The precipitation of carbonate limits the fluid access to the inner part of cement (by diffusion) but, in the condition of forced flow-through CO2-rich brine in the fracture, this carbonate layer is subsequently dissolved as showed by the X-ray micro tomography performed post-mortem. Despite these coupled dissolution-precipitation mechanisms (and the on-going reaction front displacement), the permeability of the fracture remains almost constant during the experiment because the effective aperture controlled by the undissolved fraction of the cement (i.e. silica-rich minerals) is preserved. For the studied conditions, it can be concluded that the flow properties of the fractured

  9. Biotic and abiotic degradation of CL-20 and RDX in soils.

    PubMed

    Crocker, Fiona H; Thompson, Karen T; Szecsody, James E; Fredrickson, Herbert L

    2005-01-01

    The caged cyclic nitramine 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) is a new explosive that has the potential to replace existing military explosives, but little is known about its environmental toxicity, transport, and fate. We quantified and compared the aerobic environmental fate of CL-20 to the widely used cyclic nitramine explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in surface and subsurface soil microcosms. Soil-free controls and biologically attenuated soil controls were used to separate abiotic processes from biologically mediated processes. Both abiotic and biological processes significantly degraded CL-20 in all soils examined. Apparent abiotic, first-order degradation rates (k) for CL-20 were not significantly different between soil-free controls (0.018 < k < 0.030 d(-1)) and biologically attenuated soil controls (0.003 < k < 0.277 d(-1)). The addition of glucose to biologically active soil microcosms significantly increased CL-20 degradation rates (0.068 < k < 1.22 d(-1)). Extents of mineralization of (14)C-CL-20 to (14)CO(2) in biologically active soil microcosms were 41.1 to 55.7%, indicating that the CL-20 cage was broken, since all carbons are part of the heterocyclic cage. Under aerobic conditions, abiotic degradation rates of RDX were generally slower (0 < k < 0.032 d(-1)) than abiotic CL-20 degradation rates. In biologically active soil microcosms amended with glucose aerobic RDX degradation rates varied between 0.010 and 0.474 d(-1). Biodegradation was a key factor in determining the environmental fate of RDX, while a combination of biotic and abiotic processes was important with CL-20. Our data suggest that CL-20 should be less recalcitrant than RDX in aerobic soils.

  10. Soil CO2 emissions as a proxy for heat and mass flow assessment, Taupō Volcanic Zone, New Zealand

    USGS Publications Warehouse

    Bloomberg, S.; Werner, Cynthia A.; Rissmann, C.F.; Mazot, A.; Horton, Travis B.; Gravley, D; Kennedy, B.; Oze, C

    2014-01-01

    The quantification of heat and mass flow between deep reservoirs and the surface is important for understanding magmatic and hydrothermal systems. Here, we use high-resolution measurement of carbon dioxide flux (φCO2) and heat flow at the surface to characterize the mass (CO2 and steam) and heat released to the atmosphere from two magma-hydrothermal systems. Our soil gas and heat flow surveys at Rotokawa and White Island in the Taupō Volcanic Zone, New Zealand, include over 3000 direct measurements of φCO2 and soil temperature and 60 carbon isotopic values on soil gases. Carbon dioxide flux was separated into background and magmatic/hydrothermal populations based on the measured values and isotopic characterization. Total CO2 emission rates (ΣCO2) of 441 ± 84 t d−1 and 124 ± 18 t d−1were calculated for Rotokawa (2.9 km2) and for the crater floor at White Island (0.3 km2), respectively. The total CO2 emissions differ from previously published values by +386 t d−1 at Rotokawa and +25 t d−1 at White Island, demonstrating that earlier research underestimated emissions by 700% (Rotokawa) and 25% (White Island). These differences suggest that soil CO2 emissions facilitate more robust estimates of the thermal energy and mass flux in geothermal systems than traditional approaches. Combining the magmatic/hydrothermal-sourced CO2 emission (constrained using stable isotopes) with reservoir H2O:CO2mass ratios and the enthalpy of evaporation, the surface expression of thermal energy release for the Rotokawa hydrothermal system (226 MWt) is 10 times greater than the White Island crater floor (22.5 MWt).

  11. Detection of Abiotic Methane in Terrestrial Continental Hydrothermal Systems: Implications for Methane on Mars

    NASA Technical Reports Server (NTRS)

    Socki, Richard A.; Niles, Paul B.; Gibson, Everett K., Jr.; Romanek, Christopher S.; Zhang, Chuanlun L.; Bissada, Kadry K.

    2008-01-01

    The recent detection of methane in the Martian atmosphere and the possibility that its origin could be attributed to biological activity, have highlighted the importance of understanding the mechanisms of methane formation and its usefulness as a biomarker. Much debate has centered on the source of the methane in hydrothermal fluids, whether it is formed biologically by microorganisms, diagenetically through the decomposition of sedimentary organic matter, or inorganically via reduction of CO2 at high temperatures. Ongoing research has now shown that much of the methane present in sea-floor hydrothermal systems is probably formed through inorganic CO2 reduction processes at very high temperatures (greater than 400 C). Experimental results have indicated that methane might form inorganically at temperatures lower still, however these results remain controversial. Currently, methane in continental hydrothermal systems is thought to be formed mainly through the breakdown of sedimentary organic matter and carbon isotope equilibrium between CO2 and CH4 is thought to be rarely present if at all. Based on isotopic measurements of CO2 and CH4 in two continental hydrothermal systems, we suggest that carbon isotope equilibration exists at temperatures as low as 155 C. This would indicate that methane is forming through abiotic CO2 reduction at lower temperatures than previously thought and could bolster arguments for an abiotic origin of the methane detected in the martian atmosphere.

  12. Fast Abiotic Production of Methane at Temperatures Below 100°C

    NASA Astrophysics Data System (ADS)

    Etiope, G.; Ionescu, A.

    2015-12-01

    Fischer-Tropsch Type (FTT) reactions, e.g., the Sabatier synthesis between H2 and CO2, are considered a main source of abiotic methane on Earth and likely on other planets. Several laboratory FTT experiments demonstrated abiotic CH4 production at temperatures above 200°C, by using Fe, Ni or Cr catalysts, simulating hydrothermal conditions in peridotite-hosted systems in mid-ocean ridges. Nevertheless, at least on laboratory experiment time-scale, Fe-Ni-Cr catalysts do not support CH4 generation at T<100°C, such as those of land-based serpentinization systems. We have recently reported rapid production of considerable amounts of CH4 (>800 ppmv in 155 mL bottles after 1 day) via Sabatier reaction at 90, 50 and 25°C, using small concentrations of non-pretreated ruthenium (Ru) equivalent to those occurring in chromitites in continental ultramafic rocks (Etiope & Ionescu, 2014; Geofluids, doi:10.1111/gfl.12106). We have repeated the experiments by using 13C-enriched CO2 and we confirm fast production of CH4at percentage levels. The experiments performed so far show that: 1. considerable amounts of CH4can be produced in dry conditions below 100°C with small quantities of Ru; 2. under the same experimental conditions (<100°C), Fe, Ni and Cr oxides do not produce CH4; 3. low T Sabatier reaction can produce CH4 with a large C isotope fractionation between CO2 and CH4, leading to relatively " light" (13C-depleted) CH4, resembling microbial gas; 4. the CO2-CH4isotope separation decreases over time and by increasing the temperature; 5. minor amounts of C2-C6hydrocarbons are also generated. Our laboratory data are compatible with the isotopic patterns of CH4 naturally occurring in land-based seeps and springs. Our experiments suggest that Ru-enriched chromitites could potentially generate CH4 at low T. Since Ru is reported in Martian meteorites, low T abiotic CH4 production on Mars via Sabatier reaction cannot be excluded (Etiope et al. 2013, Icarus, 224, 276-285).

  13. Arbuscular mycorrhizal fungal responses to abiotic stresses: A review.

    PubMed

    Lenoir, Ingrid; Fontaine, Joël; Lounès-Hadj Sahraoui, Anissa

    2016-03-01

    The majority of plants live in close collaboration with a diversity of soil organisms among which arbuscular mycorrhizal fungi (AMF) play an essential role. Mycorrhizal symbioses contribute to plant growth and plant protection against various environmental stresses. Whereas the resistance mechanisms induced in mycorrhizal plants after exposure to abiotic stresses, such as drought, salinity and pollution, are well documented, the knowledge about the stress tolerance mechanisms implemented by the AMF themselves is limited. This review provides an overview of the impacts of various abiotic stresses (pollution, salinity, drought, extreme temperatures, CO2, calcareous, acidity) on biodiversity, abundance and development of AMF and examines the morphological, biochemical and molecular mechanisms implemented by AMF to survive in the presence of these stresses. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Multiphase Flow Characteristics of Heterogeneous Rocks From CO2 Storage Reservoirs in the United Kingdom

    NASA Astrophysics Data System (ADS)

    Reynolds, Catriona A.; Blunt, Martin J.; Krevor, Samuel

    2018-02-01

    We have studied the impact of heterogeneity on relative permeability and residual trapping for rock samples from the Bunter sandstone of the UK Southern North Sea, the Ormskirk sandstone of the East Irish Sea, and the Captain sandstone of the UK Northern North Sea. Reservoir condition CO2-brine relative permeability measurements were made while systematically varying the ratio of viscous to capillary flow potential, across a range of flow rates, fractional flow, and during drainage and imbibition displacement. This variation resulted in observations obtained across a range of core-scale capillary number 0.2

  15. Coupled Model for CO2 Leaks from Geological Storage: Geomechanics, Fluid Flow and Phase Transitions

    NASA Astrophysics Data System (ADS)

    Gor, G.; Prevost, J.

    2013-12-01

    Deep saline aquifers are considered as a promising option for long-term storage of carbon dioxide. However, risk of CO2 leakage from the aquifers through faults, natural or induced fractures or abandoned wells cannot be disregarded. Therefore, modeling of various leakage scenarios is crucial when selecting a site for CO2 sequestration and choosing proper operational conditions. Carbon dioxide is injected into wells at supercritical conditions (t > 31.04 C, P > 73.82 bar), and these conditions are maintained in the deep aquifers (at 1-2 km depth) due to hydrostatic pressure and geothermal gradient. However, if CO2 and brine start to migrate from the aquifer upward, both pressure and temperature will decrease, and at the depth of 500-750 m, the conditions for CO2 will become subcritical. At subcritical conditions, CO2 starts boiling and the character of the flow changes dramatically due to appearance of the third (vapor) phase and latent heat effects. When modeling CO2 leaks, one needs to couple the multiphase flow in porous media with geomechanics. These capabilities are provided by Dynaflow, a finite element analysis program [1]; Dynaflow has already showed to be efficient for modeling caprock failure causing CO2 leaks [2, 3]. Currently we have extended the capabilities of Dynaflow with the phase transition module, based on two-phase and three-phase isenthalpic flash calculations [4]. We have also developed and implemented an efficient method for solving heat and mass transport with the phase transition using our flash module. Therefore, we have developed a robust tool for modeling CO2 leaks. In the talk we will give a brief overview of our method and illustrate it with the results of simulations for characteristic test cases. References: [1] J.H. Prevost, DYNAFLOW: A Nonlinear Transient Finite Element Analysis Program. Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ. http://www.princeton.edu/~dynaflow/ (last update 2013

  16. Simultaneous Online Measurement of H2O and CO2 in the Humid CO2 Adsorption/Desorption Process.

    PubMed

    Yu, Qingni; Ye, Sha; Zhu, Jingke; Lei, Lecheng; Yang, Bin

    2015-01-01

    A dew point meter (DP) and an infrared (IR) CO2 analyzer were assembled in a humid CO2 adsorption/desorption system in series for simultaneous online measurements of H2O and CO2, respectively. The humidifier, by using surface-flushing on a saturated brine solution was self-made for the generation of humid air flow. It was found that by this method it became relatively easy to obtain a low H2O content in air flow and that its fluctuation could be reduced compared to the bubbling method. Water calibration for the DP-IR detector is necessary to be conducted for minimizing the measurement error of H2O. It demonstrated that the relative error (RA) for simultaneous online measurements H2O and CO2 in the desorption process is lower than 0.1%. The high RA in the adsorption of H2O is attributed to H2O adsorption on the transfer pipe and amplification of the measurement error. The high accuracy of simultaneous online measurements of H2O and CO2 is promising for investigating their co-adsorption/desorption behaviors, especially for direct CO2 capture from ambient air.

  17. Evaluating reaction pathways of hydrothermal abiotic organic synthesis at elevated temperatures and pressures using carbon isotopes

    NASA Astrophysics Data System (ADS)

    Fu, Qi; Socki, Richard A.; Niles, Paul B.

    2015-04-01

    Experiments were performed to better understand the role of environmental factors on reaction pathways and corresponding carbon isotope fractionations during abiotic hydrothermal synthesis of organic compounds using piston cylinder apparatus at 750 °C and 5.5 kbars. Chemical compositions of experimental products and corresponding carbon isotopic values were obtained by a Pyrolysis-GC-MS-IRMS system. Alkanes (methane and ethane), straight-chain saturated alcohols (ethanol and n-butanol) and monocarboxylic acids (formic and acetic acids) were generated with ethanol being the only organic compound with higher δ13C than CO2. CO was not detected in experimental products owing to the favorable water-gas shift reaction under high water pressure conditions. The pattern of δ13C values of CO2, carboxylic acids and alkanes are consistent with their equilibrium isotope relationships: CO2 > carboxylic acids > alkanes, but the magnitude of the fractionation among them is higher than predicted isotope equilibrium values. In particular, the isotopic fractionation between CO2 and CH4 remained constant at ∼31‰, indicating a kinetic effect during CO2 reduction processes. No "isotope reversal" of δ13C values for alkanes or carboxylic acids was observed, which indicates a different reaction pathway than what is typically observed during Fischer-Tropsch synthesis under gas phase conditions. Under constraints imposed in experiments, the anomalous 13C isotope enrichment in ethanol suggests that hydroxymethylene is the organic intermediate, and that the generation of other organic compounds enriched in 12C were facilitated by subsequent Rayleigh fractionation of hydroxymethylene reacting with H2 and/or H2O. Carbon isotope fractionation data obtained in this study are instrumental in assessing the controlling factors on abiotic formation of organic compounds in hydrothermal systems. Knowledge on how environmental conditions affect reaction pathways of abiotic synthesis of organic

  18. 40 CFR 98.423 - Calculating CO2 supply.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... as allowed in paragraph (b) of this section, calculate the annual mass of CO2 captured, extracted... mass of CO2 for all flow meters according to the procedures specified in paragraph (a)(3) of this section. (1) For each mass flow meter, you shall calculate quarterly the mass of CO2 in a CO2 stream in...

  19. 40 CFR 98.423 - Calculating CO2 supply.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... as allowed in paragraph (b) of this section, calculate the annual mass of CO2 captured, extracted... mass of CO2 for all flow meters according to the procedures specified in paragraph (a)(3) of this section. (1) For each mass flow meter, you shall calculate quarterly the mass of CO2 in a CO2 stream in...

  20. 40 CFR 98.423 - Calculating CO2 supply.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... as allowed in paragraph (b) of this section, calculate the annual mass of CO2 captured, extracted... mass of CO2 for all flow meters according to the procedures specified in paragraph (a)(3) of this section. (1) For each mass flow meter, you shall calculate quarterly the mass of CO2 in a CO2 stream in...

  1. Biotic and abiotic controls on diurnal fluctuations in labile soil phosphorus of a wet tropical forest.

    PubMed

    Vandecar, Karen L; Lawrence, Deborah; Wood, Tana; Oberbauer, Steven F; Das, Rishiraj; Tully, Katherine; Schwendenmann, Luitgard

    2009-09-01

    The productivity of many tropical wet forests is generally limited by bioavailable phosphorus (P). Microbial activity is a key regulator of P availability in that it determines both the supply of P through organic matter decomposition and the depletion of bioavailable P through microbial uptake. Both microbial uptake and mineralization occur rapidly, and their net effect on P availability varies with soil moisture, temperature, and soil organic matter quantity and quality. Exploring the mechanisms driving P availability at fine temporal scales can provide insight into the coupling of carbon, water, and nutrient cycles, and ultimately, the response of tropical forests to climate change. Despite the recognized importance of P cycling to the dynamics of wet tropical forests and their potential sensitivity to short-term fluctuations in bioavailable P, the diurnal pattern of P remains poorly understood. This study quantifies diurnal fluctuations in labile soil P and evaluates the importance of biotic and abiotic factors in driving these patterns. To this end, measurements of labile P were made every other hour in a Costa Rican wet tropical forest oxisol. Spatial and temporal variation in Bray-extractable P were investigated in relation to ecosystem carbon flux, soil CO2 efflux, soil moisture, soil temperature, solar radiation, and sap-flow velocity. Spatially averaged bi-hourly (every two hours) labile P ranged from 0.88 to 2.48 microg/g across days. The amplitude in labile P throughout the day was 0.61-0.82 microg/g (41-54% of mean P concentrations) and was characterized by a bimodal pattern with a decrease at midday. Labile P increased with soil CO2 efflux and soil temperature and declined with increasing sap flow and solar radiation. Together, soil CO2 efflux, soil temperature, and sap flow explained 86% of variation in labile P.

  2. Flow behaviour of supercritical CO2 and brine in Berea sandstone during drainage and imbibition revealed by medical X-ray CT images

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Nishizawa, Osamu; Kiyama, Tamotsu; Chiyonobu, Shun; Xue, Ziqiu

    2014-06-01

    We injected Berea sandstone with supercritical CO2 and imaged the results with a medical X-ray computed tomography (CT) scanner. The images were acquired by injecting CO2 into a core of brine-saturated sandstone (drainage), and additional images were acquired during reinjection of brine (imbibition) after drainage. We then analysed the temporal variations of CO2 saturation maps obtained from the CT images. The experiments were performed under a confining pressure of 12 MPa, a pore pressure of 10 MPa and a temperature of 40 °C. Porosity and CO2 saturation were calculated for each image voxel of the rock on the basis of the Hounsfield unit values (CT numbers) measured at three states of saturation: dry, full brine saturation and full CO2 saturation. The saturation maps indicated that the distributions of CO2 and brine were controlled by the sub-core-scale heterogeneities which consisted of a laminated structure (bedding) with high- and low-porosity layers. During drainage, CO2 preferentially flowed through the high-porosity layers where most of the CO2 was entrapped during low flow-rate imbibition. The entrapped CO2 was flushed out when high flow-rate imbibition commenced. Plots of the voxel's CT number against porosity revealed the relationship between fluid replacement and porosity. By reference to the CT numbers at the full brine-saturated stage, differential CT numbers were classified into three bins corresponding to voxel porosity: high, medium and low porosity. Distributions of the differential CT number for the three porosity bins were bimodal and in order with respect to the porosity bins during both drainage and imbibitions; however, the order differed between the two stages. This difference suggested that different replacement mechanisms operated for the two processes. Spatial autocorrelation of CO2 saturation maps on sections perpendicular to the flow direction revealed remarkable changes during passage of the replacement fronts during both drainage and

  3. In-loop flow [11 C]CO2 fixation and radiosynthesis of N,N'-[11 C]dibenzylurea.

    PubMed

    Downey, Joseph; Bongarzone, Salvatore; Hader, Stefan; Gee, Antony D

    2018-03-01

    Cyclotron-produced carbon-11 is a highly valuable radionuclide for the production of positron emission tomography (PET) radiotracers. It is typically produced as relatively unreactive carbon-11 carbon dioxide ([ 11 C]CO 2 ), which is most commonly converted into a more reactive precursor for synthesis of PET radiotracers. The development of [ 11 C]CO 2 fixation methods has more recently enabled the direct radiolabelling of a diverse array of structures directly from [ 11 C]CO 2 , and the advantages afforded by the use of a loop-based system used in 11 C-methylation and 11 C-carboxylation reactions inspired us to apply the [ 11 C]CO 2 fixation "in-loop." In this work, we developed and investigated a new ethylene tetrafluoroethylene (ETFE) loop-based [ 11 C]CO 2 fixation method, enabling the fast and efficient, direct-from-cyclotron, in-loop trapping of [ 11 C]CO 2 using mixed DBU/amine solutions. An optimised protocol was integrated into a proof-of-concept in-loop flow radiosynthesis of N,N'-[ 11 C]dibenzylurea. This reaction exhibited an average 78% trapping efficiency and a crude radiochemical purity of 83% (determined by radio-HPLC), giving an overall nonisolated radiochemical yield of 72% (decay-corrected) within just 3 minutes from end of bombardment. This proof-of-concept reaction has demonstrated that efficient [ 11 C]CO 2 fixation can be achieved in a low-volume (150 μL) ETFE loop and that this can be easily integrated into a rapid in-loop flow radiosynthesis of carbon-11-labelled products. This new in-loop methodology will allow fast radiolabelling reactions to be performed using cheap/disposable ETFE tubing setup (ideal for good manufacturing practice production) thereby contributing to the widespread usage of [ 11 C]CO 2 trapping/fixation reactions for the production of PET radiotracers. © 2017 The Authors. Journal of Labelled Compounds and Radiopharmaceuticals Published by John Wiley & Sons, Ltd.

  4. Rapid and enhanced activation of microporous coordination polymers by flowing supercritical CO.sub.2

    DOEpatents

    Matzger, Adam J.; Liu, Baojian; Wong-Foy, Antek G.

    2016-07-19

    Flowing supercritical CO.sub.2 is used to activate metal organic framework materials (MOF). MOFs are activated directly from N,N-dimethylformamide (DMF) thus avoiding exchange with a volatile solvent. Most MCPs display increased surface areas directly after treatment although those with coordinatively unsaturated metal centers benefit from additional heating.

  5. In‐loop flow [11C]CO2 fixation and radiosynthesis of N,N′‐[11C]dibenzylurea

    PubMed Central

    Downey, Joseph; Bongarzone, Salvatore; Hader, Stefan

    2017-01-01

    Cyclotron‐produced carbon‐11 is a highly valuable radionuclide for the production of positron emission tomography (PET) radiotracers. It is typically produced as relatively unreactive carbon‐11 carbon dioxide ([11C]CO2), which is most commonly converted into a more reactive precursor for synthesis of PET radiotracers. The development of [11C]CO2 fixation methods has more recently enabled the direct radiolabelling of a diverse array of structures directly from [11C]CO2, and the advantages afforded by the use of a loop‐based system used in 11C‐methylation and 11C‐carboxylation reactions inspired us to apply the [11C]CO2 fixation “in‐loop.” In this work, we developed and investigated a new ethylene tetrafluoroethylene (ETFE) loop‐based [11C]CO2 fixation method, enabling the fast and efficient, direct‐from‐cyclotron, in‐loop trapping of [11C]CO2 using mixed DBU/amine solutions. An optimised protocol was integrated into a proof‐of‐concept in‐loop flow radiosynthesis of N,N′‐[11C]dibenzylurea. This reaction exhibited an average 78% trapping efficiency and a crude radiochemical purity of 83% (determined by radio‐HPLC), giving an overall nonisolated radiochemical yield of 72% (decay‐corrected) within just 3 minutes from end of bombardment. This proof‐of‐concept reaction has demonstrated that efficient [11C]CO2 fixation can be achieved in a low‐volume (150 μL) ETFE loop and that this can be easily integrated into a rapid in‐loop flow radiosynthesis of carbon‐11–labelled products. This new in‐loop methodology will allow fast radiolabelling reactions to be performed using cheap/disposable ETFE tubing setup (ideal for good manufacturing practice production) thereby contributing to the widespread usage of [11C]CO2 trapping/fixation reactions for the production of PET radiotracers. PMID:28977686

  6. Single-ended mid-infrared laser-absorption sensor for simultaneous in situ measurements of H2O, CO2, CO, and temperature in combustion flows.

    PubMed

    Peng, Wen Yu; Goldenstein, Christopher S; Mitchell Spearrin, R; Jeffries, Jay B; Hanson, Ronald K

    2016-11-20

    The development and demonstration of a four-color single-ended mid-infrared tunable laser-absorption sensor for simultaneous measurements of H2O, CO2, CO, and temperature in combustion flows is described. This sensor operates by transmitting laser light through a single optical port and measuring the backscattered radiation from within the combustion device. Scanned-wavelength-modulation spectroscopy with second-harmonic detection and first-harmonic normalization (scanned-WMS-2f/1f) was used to account for variable signal collection and nonabsorption losses in the harsh environment. Two tunable diode lasers operating near 2551 and 2482 nm were utilized to measure H2O concentration and temperature, while an interband cascade laser near 4176 nm and a quantum cascade laser near 4865 nm were used for measuring CO2 and CO, respectively. The lasers were modulated at either 90 or 112 kHz and scanned across the peaks of their respective absorption features at 1 kHz, leading to a measurement rate of 2 kHz. A hybrid demultiplexing strategy involving both spectral filtering and frequency-domain demodulation was used to decouple the backscattered radiation into its constituent signals. Demonstration measurements were made in the exhaust of a laboratory-scale laminar methane-air flat-flame burner at atmospheric pressure and equivalence ratios ranging from 0.7 to 1.2. A stainless steel reflective plate was placed 0.78 cm away from the sensor head within the combustion exhaust, leading to a total absorption path length of 1.56 cm. Detection limits of 1.4% H2O, 0.6% CO2, and 0.4% CO by mole were reported. To the best of the authors' knowledge, this work represents the first demonstration of a mid-infrared laser-absorption sensor using a single-ended architecture in combustion flows.

  7. Confinement Effects on Carbon Dioxide Methanation: A Novel Mechanism for Abiotic Methane Formation

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

    Le, Thu; Striolo, Alberto; Turner, C. Heath

    An important scientific debate focuses on the possibility of abiotic synthesis of hydrocarbons during oceanic crust-seawater interactions. While on-site measurements near hydrothermal vents support this possibility, laboratory studies have provided data that are in some cases contradictory. At conditions relevant for sub-surface environments it has been shown that classic thermodynamics favour the production of CO 2 from CH 4, while abiotic methane synthesis would require the opposite. However, confinement effects are known to alter reaction equilibria. This report shows that indeed thermodynamic equilibrium can be shifted towards methane production, suggesting that thermal hydrocarbon synthesis near hydrothermal vents and deeper inmore » the magma-hydrothermal system is possible. We report reactive ensemble Monte Carlo simulations for the CO 2 methanation reaction. We compare the predicted equilibrium composition in the bulk gaseous phase to that expected in the presence of confinement. In the bulk phase we obtain excellent agreement with classic thermodynamic expectations. When the reactants can exchange between bulk and a confined phase our results show strong dependency of the reaction equilibrium conversions, X CO2, on nanopore size, nanopore chemistry, and nanopore morphology. Some physical conditions that could shift significantly the equilibrium composition of the reactive system with respect to bulk observations are discussed.« less

  8. Confinement Effects on Carbon Dioxide Methanation: A Novel Mechanism for Abiotic Methane Formation

    DOE PAGES

    Le, Thu; Striolo, Alberto; Turner, C. Heath; ...

    2017-08-21

    An important scientific debate focuses on the possibility of abiotic synthesis of hydrocarbons during oceanic crust-seawater interactions. While on-site measurements near hydrothermal vents support this possibility, laboratory studies have provided data that are in some cases contradictory. At conditions relevant for sub-surface environments it has been shown that classic thermodynamics favour the production of CO 2 from CH 4, while abiotic methane synthesis would require the opposite. However, confinement effects are known to alter reaction equilibria. This report shows that indeed thermodynamic equilibrium can be shifted towards methane production, suggesting that thermal hydrocarbon synthesis near hydrothermal vents and deeper inmore » the magma-hydrothermal system is possible. We report reactive ensemble Monte Carlo simulations for the CO 2 methanation reaction. We compare the predicted equilibrium composition in the bulk gaseous phase to that expected in the presence of confinement. In the bulk phase we obtain excellent agreement with classic thermodynamic expectations. When the reactants can exchange between bulk and a confined phase our results show strong dependency of the reaction equilibrium conversions, X CO2, on nanopore size, nanopore chemistry, and nanopore morphology. Some physical conditions that could shift significantly the equilibrium composition of the reactive system with respect to bulk observations are discussed.« less

  9. Experimental investigation on predictive models for motive flow calculation through ejectors for transcritical CO2 heat pumps

    NASA Astrophysics Data System (ADS)

    Boccardi, G.; Lillo, G.; Mastrullo, R.; Mauro, A. W.; Saraceno, L.; Pieve, M.; Trinchieri, R.

    2017-11-01

    Nowadays, air conditioning systems, especially those used in residential and office buildings, contribute largely to the energy consumptions and to the direct and indirect emissions of greenhouse gases. Carbon dioxide (CO2) is an interesting option to replace traditional HFCs in vapor compression systems, due to its environmentally friendly characteristics: zero ODP and extremely low GWP. In the case of heat pumps, the use of ejection systems for the expansion phase can contribute to recovery a fraction of the mechanical energy otherwise dissipated as friction, bringing to significant benefits in terms of performance. Currently, at the laboratory DTE-PCU-SPCT of the research center ENEA (Casaccia) in cooperation with the Industrial Engineering Department of Federico II University of Naples, a project is in progress, in order to evaluate experimentally the effect of several ejectors geometries on the global performance of a CO2 heat pump working with a transcritical cycle. As a part of this project, measurements of the motive flow mass flow rate have been carried out, in transcritical CO2 conditions. The ejector sizing is a crucial point for the balancing of components and the correct operation of the CO2 heat pump and therefore the availability of reliable calculation methods for the motive flowrate would be useful. This paper presents the results obtained by a comparison between the new experimental data and the predictions of some predictive semi-empirical correlations available in the open literature for transcritical CO2 conditions. Their predictions are analyzed as a function of the main physical parameters of the process to assess their reliability compared to the experimental data. Based on these indications and of the available experimental data, a new semi-empirical correlations and a calculation method based on the hypothesis of isentropic and choked two-phase flow are presented.

  10. 40 CFR 98.423 - Calculating CO2 supply.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) Calculate the annual mass of CO2 captured, extracted, imported, or exported through each flow meter in... flow meters are used, you shall calculate the annual mass of CO2 for all flow meters according to the procedures specified in paragraph (a)(3) of this section. (1) For each mass flow meter, you shall calculate...

  11. Regulation of MIR Genes in Response to Abiotic Stress in Hevea brasiliensis

    PubMed Central

    Gébelin, Virginie; Leclercq, Julie; Hu, Songnian; Tang, Chaorong; Montoro, Pascal

    2013-01-01

    Increasing demand for natural rubber (NR) calls for an increase in latex yield and also an extension of rubber plantations in marginal zones. Both harvesting and abiotic stresses lead to tapping panel dryness through the production of reactive oxygen species. Many microRNAs regulated during abiotic stress modulate growth and development. The objective of this paper was to study the regulation of microRNAs in response to different types of abiotic stress and hormone treatments in Hevea. Regulation of MIR genes differs depending on the tissue and abiotic stress applied. A negative co-regulation between HbMIR398b with its chloroplastic HbCuZnSOD target messenger is observed in response to salinity. The involvement of MIR gene regulation during latex harvesting and tapping panel dryness (TPD) occurrence is further discussed. PMID:24084713

  12. Effect of Mineral Dissolution/Precipitation and CO2 Exsolution on CO2 transport in Geological Carbon Storage.

    PubMed

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

    2017-09-19

    Geological carbon sequestration (GCS) in deep saline aquifers is an effective means for storing carbon dioxide to address global climate change. As the time after injection increases, the safety of storage increases as the CO 2 transforms from a separate phase to CO 2 (aq) and HCO 3 - by dissolution and then to carbonates by mineral dissolution. However, subsequent depressurization could lead to dissolved CO 2 (aq) escaping from the formation water and creating a new separate phase which may reduce the GCS system safety. The mineral dissolution and the CO 2 exsolution and mineral precipitation during depressurization change the morphology, porosity, and permeability of the porous rock medium, which then affects the two-phase flow of the CO 2 and formation water. A better understanding of these effects on the CO 2 -water two-phase flow will improve predictions of the long-term CO 2 storage reliability, especially the impact of depressurization on the long-term stability. In this Account, we summarize our recent work on the effect of CO 2 exsolution and mineral dissolution/precipitation on CO 2 transport in GCS reservoirs. We place emphasis on understanding the behavior and transformation of the carbon components in the reservoir, including CO 2 (sc/g), CO 2 (aq), HCO 3 - , and carbonate minerals (calcite and dolomite), highlight their transport and mobility by coupled geochemical and two-phase flow processes, and consider the implications of these transport mechanisms on estimates of the long-term safety of GCS. We describe experimental and numerical pore- and core-scale methods used in our lab in conjunction with industrial and international partners to investigate these effects. Experimental results show how mineral dissolution affects permeability, capillary pressure, and relative permeability, which are important phenomena affecting the input parameters for reservoir flow modeling. The porosity and the absolute permeability increase when CO 2 dissolved water is

  13. Pore-scale imaging of capillary trapped supercritical CO2 as controlled by water-wet vs. CO2-wet media and grain shapes

    NASA Astrophysics Data System (ADS)

    Chaudhary, K.; Cardenas, M.; Wolfe, W. W.; Maisano, J. A.; Ketcham, R. A.; Bennett, P.

    2013-12-01

    The capillary trapping of supercritical CO2 (s-CO2) is postulated to comprise up to 90% of permanently trapped CO2 injected during geologic sequestration. Successive s-CO2/brine flooding experiments under reservoir conditions showed that water-wet rounded beads trapped 15% of injected s-CO2 both as clusters and as individual ganglia, whereas CO2¬-wet beads trapped only 2% of the injected s-CO2 as minute pockets in pore constrictions. Angular water-wet grains trapped 20% of the CO2 but flow was affected by preferential flow. Thus, capillary trapping is a viable mechanism for the permanent CO2 storage, but its success is constrained by the media wettability.

  14. Pathways for abiotic organic synthesis at submarine hydrothermal fields.

    PubMed

    McDermott, Jill M; Seewald, Jeffrey S; German, Christopher R; Sylva, Sean P

    2015-06-23

    Arguments for an abiotic origin of low-molecular weight organic compounds in deep-sea hot springs are compelling owing to implications for the sustenance of deep biosphere microbial communities and their potential role in the origin of life. Theory predicts that warm H2-rich fluids, like those emanating from serpentinizing hydrothermal systems, create a favorable thermodynamic drive for the abiotic generation of organic compounds from inorganic precursors. Here, we constrain two distinct reaction pathways for abiotic organic synthesis in the natural environment at the Von Damm hydrothermal field and delineate spatially where inorganic carbon is converted into bioavailable reduced carbon. We reveal that carbon transformation reactions in a single system can progress over hours, days, and up to thousands of years. Previous studies have suggested that CH4 and higher hydrocarbons in ultramafic hydrothermal systems were dependent on H2 generation during active serpentinization. Rather, our results indicate that CH4 found in vent fluids is formed in H2-rich fluid inclusions, and higher n-alkanes may likely be derived from the same source. This finding implies that, in contrast with current paradigms, these compounds may form independently of actively circulating serpentinizing fluids in ultramafic-influenced systems. Conversely, widespread production of formate by ΣCO2 reduction at Von Damm occurs rapidly during shallow subsurface mixing of the same fluids, which may support anaerobic methanogenesis. Our finding of abiogenic formate in deep-sea hot springs has significant implications for microbial life strategies in the present-day deep biosphere as well as early life on Earth and beyond.

  15. Pathways for abiotic organic synthesis at submarine hydrothermal fields

    PubMed Central

    McDermott, Jill M.; Seewald, Jeffrey S.; German, Christopher R.; Sylva, Sean P.

    2015-01-01

    Arguments for an abiotic origin of low-molecular weight organic compounds in deep-sea hot springs are compelling owing to implications for the sustenance of deep biosphere microbial communities and their potential role in the origin of life. Theory predicts that warm H2-rich fluids, like those emanating from serpentinizing hydrothermal systems, create a favorable thermodynamic drive for the abiotic generation of organic compounds from inorganic precursors. Here, we constrain two distinct reaction pathways for abiotic organic synthesis in the natural environment at the Von Damm hydrothermal field and delineate spatially where inorganic carbon is converted into bioavailable reduced carbon. We reveal that carbon transformation reactions in a single system can progress over hours, days, and up to thousands of years. Previous studies have suggested that CH4 and higher hydrocarbons in ultramafic hydrothermal systems were dependent on H2 generation during active serpentinization. Rather, our results indicate that CH4 found in vent fluids is formed in H2-rich fluid inclusions, and higher n-alkanes may likely be derived from the same source. This finding implies that, in contrast with current paradigms, these compounds may form independently of actively circulating serpentinizing fluids in ultramafic-influenced systems. Conversely, widespread production of formate by ΣCO2 reduction at Von Damm occurs rapidly during shallow subsurface mixing of the same fluids, which may support anaerobic methanogenesis. Our finding of abiogenic formate in deep-sea hot springs has significant implications for microbial life strategies in the present-day deep biosphere as well as early life on Earth and beyond. PMID:26056279

  16. Lattice Boltzmann simulations of supercritical CO2-water drainage displacement in porous media: CO2 saturation and displacement mechanism.

    PubMed

    Yamabe, Hirotatsu; Tsuji, Takeshi; Liang, Yunfeng; Matsuoka, Toshifumi

    2015-01-06

    CO2 geosequestration in deep aquifers requires the displacement of water (wetting phase) from the porous media by supercritical CO2 (nonwetting phase). However, the interfacial instabilities, such as viscous and capillary fingerings, develop during the drainage displacement. Moreover, the burstlike Haines jump often occurs under conditions of low capillary number. To study these interfacial instabilities, we performed lattice Boltzmann simulations of CO2-water drainage displacement in a 3D synthetic granular rock model at a fixed viscosity ratio and at various capillary numbers. The capillary numbers are varied by changing injection pressure, which induces changes in flow velocity. It was observed that the viscous fingering was dominant at high injection pressures, whereas the crossover of viscous and capillary fingerings was observed, accompanied by Haines jumps, at low injection pressures. The Haines jumps flowing forward caused a significant drop of CO2 saturation, whereas Haines jumps flowing backward caused an increase of CO2 saturation (per injection depth). We demonstrated that the pore-scale Haines jumps remarkably influenced the flow path and therefore equilibrium CO2 saturation in crossover domain, which is in turn related to the storage efficiency in the field-scale geosequestration. The results can improve our understandings of the storage efficiency by the effects of pore-scale displacement phenomena.

  17. Reaction processes and permeability changes during CO2-rich brine flow through fractured Portland cement

    NASA Astrophysics Data System (ADS)

    Abdoulghafour, H.; Luquot, L.; Gouze, P.

    2012-12-01

    So far, cement alteration was principally studied experimentally using batch reactor (with static or renewed fluid). All exhibit similar carbonation mechanisms. The acidic solution, formed by the dissolution of the CO2 into the pore water or directly surrounding the cement sample, diffuses into the cement and induces dissolution reactions of the cement hydrates in particular portlandite and CSH. The calcium released by the dissolution of these calcium bearing phases combining with carbonate ions of the fluid forms calcium carbonates. The cement pH, initially around 13, falls to values where carbonate ion is the most dominant element (pH ~ 9), then CaCO3 phases can precipitate. These studies mainly associate carbonation process with a reduction of porosity and permeability. Indeed an increase of volume (about 10%) is expected during the formation of calcite from portlandite (equation 2) assuming a stoichiometric reaction. Here we investigated the cement alteration mechanisms in the frame of a controlled continuous renewal of CO2-rich fluid in a fracture. This situation is that expected when seepage is activated by the mechanical failure of the cement material that initially seals two layers of distinctly different pressure: the storage reservoir and the aquifer above the caprock, for instance. We study the effect of flow rates from quasi-static flow to higher flow rates for well-connected fractures. In the quasi-static case we observed an extensive conversion of portlandite (Ca(OH)2) to calcite in the vicinity of the fracture similar to that observed in the published batch experiments. Eventually, the fracture was almost totally healed. The experiments with constant flow revealed a different behaviour triggered by the continuous renewing of the reactants and withdrawal of reaction products. We showed that calcite precipitation is more efficient for low flow rate. With intermediate flow rate, we measured that permeability increases slowly at the beginning of the

  18. A modified homogeneous relaxation model for CO2 two-phase flow in vapour ejector

    NASA Astrophysics Data System (ADS)

    Haida, M.; Palacz, M.; Smolka, J.; Nowak, A. J.; Hafner, A.; Banasiak, K.

    2016-09-01

    In this study, the homogenous relaxation model (HRM) for CO2 flow in a two-phase ejector was modified in order to increase the accuracy of the numerical simulations The two- phase flow model was implemented on the effective computational tool called ejectorPL for fully automated and systematic computations of various ejector shapes and operating conditions. The modification of the HRM was performed by a change of the relaxation time and the constants included in the relaxation time equation based on the experimental result under the operating conditions typical for the supermarket refrigeration system. The modified HRM was compared to the HEM results, which were performed based on the comparison of motive nozzle and suction nozzle mass flow rates.

  19. Recent developments in CO2 lasers

    NASA Astrophysics Data System (ADS)

    Du, Keming

    1993-05-01

    CO2 lasers have been used in industry mainly for such things as cutting, welding, and surface processing. To conduct a broad spectrum of high-speed and high-quality applications, most of the developments in industrial CO2 lasers at the ILT are aimed at increasing the output power, optimizing the beam quality, and reducing the production costs. Most of the commercial CO2 lasers above 5 kW are transverse-flow systems using dc excitation. The applications of these lasers are limited due to the lower beam quality, the poor point stability, and the lower modulation frequency. To overcome the problems we developed a fast axial- flow CO2 laser using rf excitation with an output of 13 kW. In section 2 some of the results are discussed concerning the gas flow, the discharge, the resonator design, optical effects of active medium, the aerodynamic window, and the modulation of the output power. The first CO2 lasers ever built are diffusion-cooled systems with conventional dc excited cylindrical discharge tubes surrounded by cooling jackets. The output power per unit length is limited to 50 W/m by those lasers with cylindrical tubes. In the past few years considerable increases in the output power were achieved, using new mechanical geometries, excitation- techniques, and resonator designs. This progress in diffusion-cooled CO2 lasers is presented in section 3.

  20. Effects of long-term elevated CO2 treatment on the inner and outer bark chemistry of sweetgum (Liquidambar styraciflua L.) trees

    Treesearch

    Thomas L. Eberhardt; Nicole Labbé; Chi-Leung So; Keonhee Kim; Karen G. Reed; Daniel J. Leduc; Jeffrey M. Warren

    2015-01-01

    Changes in plant tissue chemistry due to increasing atmospheric carbon dioxide (CO2) concentrations have direct implications for tissue resistance to abiotic and biotic stress while living, and soil nutrient cycling when senesced as litter. Although the effects of elevatedCO2 concentrations on tree foliar chemistry are well...

  1. Inter-annual variability of carbon fluxes in temperate forest ecosystems: effects of biotic and abiotic factors

    NASA Astrophysics Data System (ADS)

    Chen, M.; Keenan, T. F.; Hufkens, K.; Munger, J. W.; Bohrer, G.; Brzostek, E. R.; Richardson, A. D.

    2014-12-01

    Carbon dynamics in terrestrial ecosystems are influenced by both abiotic and biotic factors. Abiotic factors, such as variation in meteorological conditions, directly drive biophysical and biogeochemical processes; biotic factors, referring to the inherent properties of the ecosystem components, reflect the internal regulating effects including temporal dynamics and memory. The magnitude of the effect of abiotic and biotic factors on forest ecosystem carbon exchange has been suggested to vary at different time scales. In this study, we design and conduct a model-data fusion experiment to investigate the role and relative importance of the biotic and abiotic factors for inter-annual variability of the net ecosystem CO2 exchange (NEE) of temperate deciduous forest ecosystems in the Northeastern US. A process-based model (FöBAAR) is parameterized at four eddy-covariance sites using all available flux and biometric measurements. We conducted a "transplant" modeling experiment, that is, cross- site and parameter simulations with different combinations of site meteorology and parameters. Using wavelet analysis and variance partitioning techniques, analysis of model predictions identifies both spatial variant and spatially invariant parameters. Variability of NEE was primarily modulated by gross primary productivity (GPP), with relative contributions varying from hourly to yearly time scales. The inter-annual variability of GPP and NEE is more regulated by meteorological forcing, but spatial variability in certain model parameters (biotic response) has more substantial effects on the inter-annual variability of ecosystem respiration (Reco) through the effects on carbon pools. Both the biotic and abiotic factors play significant roles in modulating the spatial and temporal variability in terrestrial carbon cycling in the region. Together, our study quantifies the relative importance of both, and calls for better understanding of them to better predict regional CO2

  2. 'Design of CO-O2 recombination catalysts for closed-cycle CO2 lasers'

    NASA Technical Reports Server (NTRS)

    Guinn, K.; Goldblum, S.; Noskowski, E.; Herz, R.

    1989-01-01

    Pulsed CO2 lasers have many applications in aeronautics, space research, weather monitoring and other areas. Full exploitation of the potential of these lasers is hampered by the dissociation of CO2 that occurs during laser operation. The development of closed-cycle CO2 lasers requires active CO-O2 recombination (CO oxidation) catalysts and design methods for implementation of catalysts inside lasers. This paper will discuss the performance criteria and constraints involved in the design of monolith catalyst configurations for use in a closed-cycle laser and will present a design study performed with a computerized design program that had been written. Trade-offs between catalyst activity and dimensions, flow channel dimensions, pressure drop, O2 conversion and other variables will be discussed.

  3. Growing season net ecosystem CO2 exchange of two desert ecosystems with alkaline soils in Kazakhstan.

    PubMed

    Li, Longhui; Chen, Xi; van der Tol, Christiaan; Luo, Geping; Su, Zhongbo

    2014-01-01

    Central Asia is covered by vast desert ecosystems, and the majority of these ecosystems have alkaline soils. Their contribution to global net ecosystem CO2 exchange (NEE) is of significance simply because of their immense spatial extent. Some of the latest research reported considerable abiotic CO2 absorption by alkaline soil, but the rate of CO2 absorption has been questioned by peer communities. To investigate the issue of carbon cycle in Central Asian desert ecosystems with alkaline soils, we have measured the NEE using eddy covariance (EC) method at two alkaline sites during growing season in Kazakhstan. The diurnal course of mean monthly NEE followed a clear sinusoidal pattern during growing season at both sites. Both sites showed significant net carbon uptake during daytime on sunny days with high photosynthetically active radiation (PAR) but net carbon loss at nighttime and on cloudy and rainy days. NEE has strong dependency on PAR and the response of NEE to precipitation resulted in an initial and significant carbon release to the atmosphere, similar to other ecosystems. These findings indicate that biotic processes dominated the carbon processes, and the contribution of abiotic carbon process to net ecosystem CO2 exchange may be trivial in alkaline soil desert ecosystems over Central Asia.

  4. Growing season net ecosystem CO2 exchange of two desert ecosystems with alkaline soils in Kazakhstan

    PubMed Central

    Li, Longhui; Chen, Xi; van der Tol, Christiaan; Luo, Geping; Su, Zhongbo

    2014-01-01

    Central Asia is covered by vast desert ecosystems, and the majority of these ecosystems have alkaline soils. Their contribution to global net ecosystem CO2 exchange (NEE) is of significance simply because of their immense spatial extent. Some of the latest research reported considerable abiotic CO2 absorption by alkaline soil, but the rate of CO2 absorption has been questioned by peer communities. To investigate the issue of carbon cycle in Central Asian desert ecosystems with alkaline soils, we have measured the NEE using eddy covariance (EC) method at two alkaline sites during growing season in Kazakhstan. The diurnal course of mean monthly NEE followed a clear sinusoidal pattern during growing season at both sites. Both sites showed significant net carbon uptake during daytime on sunny days with high photosynthetically active radiation (PAR) but net carbon loss at nighttime and on cloudy and rainy days. NEE has strong dependency on PAR and the response of NEE to precipitation resulted in an initial and significant carbon release to the atmosphere, similar to other ecosystems. These findings indicate that biotic processes dominated the carbon processes, and the contribution of abiotic carbon process to net ecosystem CO2 exchange may be trivial in alkaline soil desert ecosystems over Central Asia. PMID:24455157

  5. CO2 hydrate formation and dissociation in cooled porous media: a potential technology for CO2 capture and storage.

    PubMed

    Yang, Mingjun; Song, Yongchen; Jiang, Lanlan; Zhu, Ningjun; Liu, Yu; Zhao, Yuechao; Dou, Binlin; Li, Qingping

    2013-09-03

    The purpose of this study was to investigate the hydrate formation and dissociation with CO2 flowing through cooled porous media at different flow rates, pressures, temperatures, and flow directions. CO2 hydrate saturation was quantified using the mean intensity of water. The experimental results showed that the hydrate block appeared frequently, and it could be avoided by stopping CO2 flooding early. Hydrate formed rapidly as the temperature was set to 274.15 or 275.15 K, but the hydrate formation delayed when it was 276.15 K. The flow rate was an important parameter for hydrate formation; a too high or too low rate was not suitable for CO2 hydration formation. A low operating pressure was also unacceptable. The gravity made hydrate form easily in the vertically upward flow direction. The pore water of the second cycle converted to hydrate more completely than that of the first cycle, which was a proof of the hydrate "memory effect". When the pressure was equal to atmospheric pressure, hydrate did not dissociate rapidly and abundantly, and a long time or reduplicate depressurization should be used in industrial application.

  6. Coupled multiphase reactive flow and mineral dissolution-precipitation kinetics: Examples of long-term CO2 sequestration in Utsira Sand, Norway and Mt. Simon Formation, Midwest USA

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Zhang, G.; Lu, P.; Hu, B.; Zhu, C.

    2017-12-01

    The extent of CO2 mineralization after CO2 injection into deep saline aquifers is a result of the complex coupling of multiphase fluid flow, mass transport, and brine-mineral reactions. The effects of dissolution rate laws and groundwater flow on the long-term fate of CO2 have been seriously overlooked. To investigate these effects, we conducted multiphase (CO2 and brine) coupled reactive transport modeling of CO2 storage in two sandy formations (Utsira Sand, Norway1,2 and Mt. Simon formation, USA 3) using ToughReact and simulated a series of scenarios. The results indicated that: (1) Different dissolution rate laws for feldspars can significantly affect the amount of CO2 mineralization. Increased feldspar dissolution will promote CO2 mineral trapping through the coupling between feldspar dissolution and carbonate mineral precipitation at raised pH. The predicted amount of CO2 mineral trapping when using the principle of detailed balancing-based rate law for feldspar dissolution is about twice as much as that when using sigmoidal rate laws in the literature. (2) Mineral trapping is twice as much when regional groundwater flow is taken into consideration in long-term simulations (e.g., 10,000 years) whereas most modeling studies neglected the regional groundwater flow back and effectively simulated a batch reactor process. Under the influence of regional groundwater flow, the fresh brine from upstream continuously dissolves CO2 at the tail of CO2 plume, generating a large acidified area where large amount of CO2 mineralization takes place. The upstream replenishment of groundwater results in ˜22% mineral trapping at year 10,000, compared to ˜4% when this effect is ignored. Refs: 1Zhang, G., Lu, P., Wei, X., Zhu, C. (2016). Impacts of Mineral Reaction Kinetics and Regional Groundwater Flow on Long-Term CO2 Fate at Sleipner. Energy & Fuels, 30(5), 4159-4180. 2Zhu, C., Zhang, G., Lu, P., Meng, L., Ji, X. (2015). Benchmark modeling of the Sleipner CO2 plume

  7. Photochemically assisted fast abiotic oxidation of manganese and formation of δ-MnO 2 nanosheets in nitrate solution

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

    Jung, Haesung; Chadha, Tandeep S.; Kim, Doyoon

    This study introduces a new and previously unconsidered fast abiotic formation of Mn(IV) oxides. We report photochemically assisted fast abiotic oxidation of Mn 2+ (aq) to Mn(IV) (s) by superoxide radicals generated from nitrate photolysis. This photochemical pathway generates randomly stacked layered birnessite (δ-MnO 2) nanosheets.

  8. Effects of contaminants in CO2 lasers.

    NASA Technical Reports Server (NTRS)

    Smith, N. S.

    1973-01-01

    A theoretical model which includes the effects of contaminants is developed for the high flow electric discharge CO2-N2-He laser. The model couples the excitation and relaxation processes, CO2 dissociation, and negative ion formation with the flow processes. An analysis of the effects of CO, O2, NO, and N2O impurities on the average small signal gain is presented. CO decreases the gain by collisional depopulation of the upper laser level, and O2, NO, and N2O reduce the gain by decreasing the electron density by forming stable negative ions. In particular, N2O exhibits a strong quenching effect because of its large dissociation cross section for the formation of O(-).

  9. 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

  10. Conversion of nitrogen oxides in N2:O2:CO2 and N2:O2:CO2:NO2 mixtures subjected to a dc corona discharge

    NASA Astrophysics Data System (ADS)

    Dors, Mirosław; Mizeraczyk, Jerzy

    1996-10-01

    This paper concerns the influence of a direct current (dc) corona discharge on production and reduction of NO, NO2 and N2O in N2:O2:CO2 and N2:O2:CO2:NO2 mixtures. The corona discharge was generated in a needle-to-plate reactor. The positively polarized electrode consisted of 7 needles. The grounded electrode was a stainless steel plate. The gas flow rate through the reactor was varied from 28 to 110 cm3/s. The time-averaged discharge current ranged from 0 to 6 mA. It was found that in the N2:O2:CO2 mixture the corona discharge produced NO, NO2 and N2O. In the N2:O2:CO2:NO2 mixture the reduction of NO2 was between 6-56%, depending on the concentration of O2, gas flow rate and corona discharge current. The NO2 reduction was accompanied by production of NO and N2O. The results show that efficient reduction of nitrogen oxides by a corona discharge cannot be expected in the mixtures containing N2 and O2 if reducing additives are not employed.

  11. Magma ascent and lava flow emplacement rates during the 2011 Axial Seamount eruption based on CO2 degassing

    NASA Astrophysics Data System (ADS)

    Jones, M. R.; Soule, S. A.; Gonnermann, H. M.; Le Roux, V.; Clague, D. A.

    2018-07-01

    Quantitative metrics for eruption rates at mid-ocean ridges (MORs) would improve our understanding of the structure and formation of the uppermost oceanic crust and would provide a means to link volcanic processes with the conditions of the underlying magmatic system. However, these metrics remain elusive because no MOR eruptions have been directly observed. The possibility of disequilibrium degassing in mid-ocean ridge basalts (MORB), due to high eruptive depressurization rates, makes the analysis of volatile concentrations in MORB glass a promising method for evaluating eruption rates. In this study, we estimate magma ascent and lava flow emplacement rates during the 2011 eruption of Axial Seamount based on numerical modeling of diffusion-controlled bubble growth and new measurements of dissolved volatiles, vesicularity, and vesicle size distributions in erupted basalts. This dataset provides a unique view of the variability in magma ascent (∼0.02-1.2 m/s) and lava flow rates (∼0.1-0.7 m/s) during a submarine MOR eruption based on 50 samples collected from a >10 km long fissure system and three individual lava flow lobes. Samples from the 2011 eruption display an unprecedented range in dissolved CO2 concentrations, nearly spanning the full range observed on the global MOR system. The variable vesicularity and dissolved CO2 concentrations in these samples can be explained by differences in the extent of degassing, dictated by flow lengths and velocities during both vertical ascent and horizontal flow along the seafloor. Our results document, for the first time, the variability in magma ascent rates during a submarine eruption (∼0.02-1.2 m/s), which spans the global range previously proposed based on CO2 degassing. The slowest ascent rates are associated with hummocky flows while faster ascent rates produce channelized sheet flows. This study corroborates degassing-based models for eruption rates using comparisons with independent methods and documents the

  12. Brine flow up a borehole caused by pressure perturbation from CO2 storage: Static and dynamic evaluations

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

    Birkholzer, J.T.; Nicot, J.-P.; Oldenburg, C.M.

    Industrial-scale storage of CO{sub 2} in saline sedimentary basins will cause zones of elevated pressure, larger than the CO{sub 2} plume itself. If permeable conduits (e.g., leaking wells) exist between the injection reservoir and overlying shallow aquifers, brine could be pushed upwards along these conduits and mix with groundwater resources. This paper discusses the potential for such brine leakage to occur in temperature- and salinity-stratified systems. Using static mass-balance calculations as well as dynamic well flow simulations, we evaluate the minimum reservoir pressure that would generate continuous migration of brine up a leaking wellbore into a freshwater aquifer. Since themore » brine invading the well is denser than the initial fluid in the wellbore, continuous flow only occurs if the pressure perturbation in the reservoir is large enough to overcome the increased fluid column weight after full invasion of brine into the well. If the threshold pressure is exceeded, brine flow rates are dependent on various hydraulic (and other) properties, in particular the effective permeability of the wellbore and the magnitude of pressure increase. If brine flow occurs outside of the well casing, e.g., in a permeable fracture zone between the well cement and the formation, the fluid/solute transfer between the migrating fluid and the surrounding rock units can strongly retard brine flow. At the same time, the threshold pressure for continuous flow to occur decreases compared to a case with no fluid/solute transfer.« less

  13. Bench-Scale Testing and Process Performance Projections of CO2 Capture by CO2–Binding Organic Liquids (CO2BOLs) With and Without Polarity-Swing-Assisted Regeneration

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

    Zheng, Feng; Heldebrant, David J.; Mathias, Paul M.

    This manuscript provides a detailed analysis of a continuous flow, bench scale study of the CO2BOL solvent platform with and without its Polarity Swing Assisted Regeneration (PSAR). This study encompassed four months of continuous flow testing of a candidate CO2BOL with a thermal regeneration and PSAR regeneration using decane antisolvent. In both regeneration schemes, steady state capture of >90 %CO2 was achieved using simulated flue gas at acceptable L/G ratios. Aspen Plus™ modeling was performed to assess process performance compared to previous equilibrium performance projections. This paper also includes net power projections, and comparisons to DOE’s Case 10 amine baseline.

  14. Pore-scale supercritical CO2 dissolution and mass transfer under imbibition conditions

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

    Chang, Chun; Zhou, Quanlin; Kneafsey, Timothy J.

    2016-06-01

    In modeling of geological carbon storage, dissolution of supercritical CO2 (scCO2) is often assumed to be instantaneous with equilibrium phase partitioning. In contrast, recent core-scale imbibition experiments have shown a prolonged depletion of residual scCO2 by dissolution, implying a non-equilibrium mechanism. In this study, eight pore-scale scCO2 dissolution experiments in a 2D heterogeneous, sandstone-analogue micromodel were conducted at supercritical conditions (9 MPa and 40 °C). The micromodel was first saturated with deionized (DI) water and drained by injecting scCO2 to establish a stable scCO2 saturation. DI water was then injected at constant flow rates after scCO2 drainage was completed. Highmore » resolution time-lapse images of scCO2 and water distributions were obtained during imbibition and dissolution, aided by a scCO2-soluble fluorescent dye introduced with scCO2 during drainage. These images were used to estimate scCO2 saturations and scCO2 depletion rates. Experimental results show that (1) a time-independent, varying number of water-flow channels are created during imbibition and later dominant dissolution by the random nature of water flow at the micromodel inlet, and (2) a time-dependent number of water-flow channels are created by coupled imbibition and dissolution following completion of dominant imbibition. The number of water-flow paths, constant or transient in nature, greatly affects the overall depletion rate of scCO2 by dissolution. The average mass fraction of dissolved CO2 (dsCO2) in water effluent varies from 0.38% to 2.72% of CO2 solubility, indicating non-equilibrium scCO2 dissolution in the millimeter-scale pore network. In general, the transient depletion rate decreases as trapped, discontinuous scCO2 bubbles and clusters within water-flow paths dissolve, then remains low with dissolution of large bypassed scCO2 clusters at their interfaces with longitudinal water flow, and finally increases with coupled transverse water

  15. Co-flow planar SOFC fuel cell stack

    DOEpatents

    Chung, Brandon W.; Pham, Ai Quoc; Glass, Robert S.

    2004-11-30

    A co-flow planar solid oxide fuel cell stack with an integral, internal manifold and a casing/holder to separately seal the cell. This construction improves sealing and gas flow, and provides for easy manifolding of cell stacks. In addition, the stack construction has the potential for an improved durability and operation with an additional increase in cell efficiency. The co-flow arrangement can be effectively utilized in other electrochemical systems requiring gas-proof separation of gases.

  16. Dynamic coupling of volcanic CO2 flow and wind at the HorseshoeLake tree kill, Mammoth Mountain, CA

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

    Lewicki, J.L.; Hilley, G.E.; Tosha, T.

    2006-11-20

    We investigate spatio-temporal relationships between soilCO2 flux (FCO2), meteorological variables, and topography over a ten-dayperiod (09/12/2006 to 09/21/2006) at the Horseshoe Lake tree kill,Mammoth Mountain, CA. Total CO2 discharge varied from 16 to 52 t d-1,suggesting a decline in CO2 emissions over decadal timescales. Weobserved systematic changes in FCO2 in space and time in association witha weather front with relatively high wind speeds from the west and lowatmospheric pressures. The largest FCO2 changes were observed inrelatively high elevation areas. The variations in FCO2 may be due todynamic coupling of wind-driven airflow through the subsurface and flowof source CO2 at depth.more » Our results highlight the influence of weatherfronts on volcanic gas flow in the near-surface environment and how thisinfluence can vary spatially within a study area.« less

  17. Industrial application of the decomposition of CO2 . NOx by large flow atmospheric microwave plasma LAMP employed in motorcar

    NASA Astrophysics Data System (ADS)

    Pandey, Anil; Niwa, Syunta; Morii, Yoshinari; Ikezawa, Shunjiro

    2012-10-01

    In order to decompose CO2 . NOx [1], we have developed the large flow atmospheric microwave plasma; LAMP [2]. It is very important to apply it for industrial innovation, so we have studied to apply the LAMP into motorcar. The characteristics of the developed LAMP are that the price is cheap and the decomposition efficiencies of CO2 . NOx are high. The mechanism was shown as the vertical configuration between the exhaust gas pipe and the waveguide was suitable [2]. The system was set up in the car body with a battery and an inverter. The battery is common between the engine and the inverter. In the application of motorcar, the flow is large, so the LAMP which has the merits of large flow, high efficient decomposition, and cheap apparatus will be superior.[4pt] [1] H. Barankova, L. Bardos, ISSP 2011, Kyoto.[0pt] [2] S. Ikezawa, S. Parajulee, S. Sharma, A. Pandey, ISSP 2011, Kyoto (2011) pp. 28-31; S. Ikezawa, S. Niwa, Y. Morii, JJAP meeting 2012, March 16, Waseda U. (2012).

  18. Delay-feedback control strategy for reducing CO2 emission of traffic flow system

    NASA Astrophysics Data System (ADS)

    Zhang, Li-Dong; Zhu, Wen-Xing

    2015-06-01

    To study the signal control strategy for reducing traffic emission theoretically, we first presented a kind of discrete traffic flow model with relative speed term based on traditional coupled map car-following model. In the model, the relative speed difference between two successive running cars is incorporated into following vehicle's acceleration running equation. Then we analyzed its stability condition with discrete control system stability theory. Third, we designed a delay-feedback controller to suppress traffic jam and decrease traffic emission based on modern controller theory. Last, numerical simulations are made to support our theoretical results, including the comparison of models' stability analysis, the influence of model type and signal control on CO2 emissions. The results show that the temporal behavior of our model is superior to other models, and the traffic signal controller has good effect on traffic jam suppression and traffic CO2 emission, which fully supports the theoretical conclusions.

  19. Dispersion of a Nanoliter Bolus in Microfluidic Co-Flow.

    PubMed

    Conway, A J; Saadi, W M; Sinatra, F L; Kowalski, G; Larson, D; Fiering, J

    2014-03-01

    Microfluidic systems enable reactions and assays on the scale of nanoliters. However, at this scale nonuniformities in sample delivery become significant. To determine the fundamental minimum sample volume required for a particular device, a detailed understanding of mass transport is required. Co-flowing laminar streams are widely used in many devices, but typically only in the steady-state. Because establishing the co-flow steady-state consumes excess sample volume and time, there is a benefit to operating devices in the transient state, which predominates as the volume of the co-flow reactor decreases. Analysis of the co-flow transient has been neglected thus far. In this work we describe the fabrication of a pneumatically controlled microfluidic injector constructed to inject a discrete 50nL bolus into one side of a two-stream co-flow reactor. Using dye for image analysis, injections were performed at a range of flow rates from 0.5-10μL/min, and for comparison we collected the co-flow steady-state data for this range. The results of the image analysis were also compared against theory and simulations for device validation. For evaluation, we established a metric that indicates how well the mass distribution in the bolus injection approximates steady-state co-flow. Using such analysis, transient-state injections can approximate steady-state conditions within predefined errors, allowing straight forward measurements to be performed with reduced reagent consumption.

  20. Spectral identification of abiotic O2 buildup from early runaways and rarefied atmospheres

    NASA Astrophysics Data System (ADS)

    Schwieterman, Edward; Meadows, Victoria; Domagal-Goldman, Shawn; Arney, Giada; Robinson, Tyler D.; Luger, Rodrigo; Barnes, Rory

    2016-01-01

    The spectral detection of oxygen (O2) in a planetary atmosphere has been considered a robust signature of life because O2 is highly reactive on planets with Earth-like redox buffers and because significant continuous abiotic sources were thought to be implausible. However, recent work has revealed the possibility that significant O2 may build-up in terrestrial atmospheres through (1) photochemical channels or (2) through the escape of hydrogen. We focus on the latter category here. Significant amounts of abiotic O2 could remain in the atmospheres of planets in the habitable zones of late type stars, where an early runaway greenhouse and massive hydrogen escape during the pre-main-sequence phase could have irreversibly oxidized the crust and mantle (Luger & Barnes 2015). Additionally, it has been hypothesized that O2 could accumulate in the atmospheres of planets with sufficiently low abundances of non-condensable gases such as N2 where water would not be cold trapped in the troposphere, leading to H-escape from UV photolysis in a wet stratosphere (Wordsworth & Pierrehumbert 2014). We self-consistently model the climate, photochemistry, and spectra of both rarefied and post-runaway, high-O2 atmospheres. Because an early runaway might not have lasted long enough for the entire water inventory to escape, we explore both completely desiccated scenarios and cases where a surface ocean remains. We find "habitable" surface conditions for a wide variety of oxygen abundances, atmospheric masses, and CO2 mixing ratios. If O2 builds up from massive or sustained H escape, the O2 abundance should be very high, and could be spectrally indicated by the presence of O2-O2 (O4) collisionally-induced absorption (CIA) features. We generate synthetic direct-imaging and transit transmission spectra of these atmospheres and calculate the strength of the UV/Visible and NIR O4 features. We find that while both the UV/Visible and NIR O4 features are strong in the radiance spectra of very

  1. Smoke Point in Co-flow Experiment

    NASA Technical Reports Server (NTRS)

    Urban, David L.; Sunderland, Peter B.; Yuan, Zeng-Guang

    2009-01-01

    The Smoke Point In Co-flow Experiment (SPICE) determines the point at which gas-jet flames (similar to a butane-lighter flame) begin to emit soot (dark carbonaceous particulate formed inside the flame) in microgravity. Studying a soot emitting flame is important in understanding the ability of fires to spread and in control of soot in practical combustion systems space. Previous experiments show that soot dominates the heat emitted from flames in normal gravity and microgravity fires. Control of this heat emission is critical for prevention of the spread of fires on Earth and in space for the design of efficient combustion systems (jet engines and power generation boilers). The onset of soot emission from small gas jet flames (similar to a butane-lighter flame) will be studied to provide a database that can be used to assess the interaction between fuel chemistry and flow conditions on soot formation. These results will be used to support combustion theories and to assess fire behavior in microgravity. The Smoke Point In Co-flow Experiment (SPICE) will lead to a o improved design of practical combustors through improved control of soot formation; o improved understanding of and ability to predict heat release, soot production and emission in microgravity fires; o improved flammability criteria for selection of materials for use in the next generation of spacecraft. The Smoke Point In Co-flow Experiment (SPICE) will continue the study of fundamental phenomena related to understanding the mechanisms controlling the stability and extinction of jet diffusion flames begun with the Laminar Soot Processes (LSP) on STS-94. SPICE will stabilize an enclosed laminar flame in a co-flowing oxidizer, measure the overall flame shape to validate the theoretical and numerical predictions, measure the flame stabilization heights, and measure the temperature field to verify flame structure predictions. SPICE will determine the laminar smoke point properties of non-buoyant jet

  2. Sedimentary reservoir oxidation during geologic CO2 sequestration

    NASA Astrophysics Data System (ADS)

    Lammers, Laura N.; Brown, Gordon E.; Bird, Dennis K.; Thomas, Randal B.; Johnson, Natalie C.; Rosenbauer, Robert J.; Maher, Katharine

    2015-04-01

    Injection of carbon dioxide into subsurface geologic reservoirs during geologic carbon sequestration (GCS) introduces an oxidizing supercritical CO2 phase into a subsurface geologic environment that is typically reducing. The resulting redox disequilibrium provides the chemical potential for the reduction of CO2 to lower free energy organic species. However, redox reactions involving carbon typically require the presence of a catalyst. Iron oxide minerals, including magnetite, are known to catalyze oxidation and reduction reactions of C-bearing species. If the redox conditions in the reservoir are modified by redox transformations involving CO2, such changes could also affect mineral stability, leading to dissolution and precipitation reactions and alteration of the long-term fate of CO2 in GCS reservoirs. We present experimental evidence that reservoirs with reducing redox conditions are favorable environments for the relatively rapid abiotic reduction of CO2 to organic molecules. In these experiments, an aqueous suspension of magnetite nanoparticles was reacted with supercritical CO2 under pressure and temperature conditions relevant to GCS in sedimentary reservoirs (95-210 °C and ∼100 bars of CO2). Hydrogen production was observed in several experiments, likely caused by Fe(II) oxidation either at the surface of magnetite or in the aqueous phase. Heating of the Fe(II)-rich system resulted in elevated PH2 and conditions favorable for the reduction of CO2 to acetic acid. Implications of these results for the long-term fate of CO2 in field-scale systems were explored using reaction path modeling of CO2 injection into reservoirs containing Fe(II)-bearing primary silicate minerals, with kinetic parameters for CO2 reduction obtained experimentally. The results of these calculations suggest that the reaction of CO2 with reservoir constituents will occur in two primary stages (1) equilibration of CO2 with organic acids resulting in mineral-fluid disequilibrium, and

  3. A model-based understanding of solid-oxide electrolysis cells (SOECs) for syngas production by H2O/CO2 co-electrolysis

    NASA Astrophysics Data System (ADS)

    Menon, Vikram; Fu, Qingxi; Janardhanan, Vinod M.; Deutschmann, Olaf

    2015-01-01

    High temperature co-electrolysis of H2O and CO2 offers a promising route for syngas (H2, CO) production via efficient use of heat and electricity. The performance of a SOEC during co-electrolysis is investigated by focusing on the interactions between transport processes and electrochemical parameters. Electrochemistry at the three-phase boundary is modeled by a modified Butler-Volmer approach that considers H2O electrolysis and CO2 electrolysis, individually, as electrochemically active charge transfer pathways. The model is independent of the geometrical structure. A 42-step elementary heterogeneous reaction mechanism for the thermo-catalytic chemistry in the fuel electrode, the dusty gas model (DGM) to account for multi-component diffusion through porous media, and a plug flow model for flow through the channels are used in the model. Two sets of experimental data are reproduced by the simulations, in order to deduce parameters of the electrochemical model. The influence of micro-structural properties, inlet cathode gas velocity, and temperature are discussed. Reaction flow analysis is performed, at OCV, to study methane production characteristics and kinetics during co-electrolysis. Simulations are carried out for configurations ranging from simple one-dimensional electrochemical button cells to quasi-two-dimensional co-flow planar cells, to demonstrate the effectiveness of the computational tool for performance and design optimization.

  4. Advances in crop proteomics: PTMs of proteins under abiotic stress.

    PubMed

    Wu, Xiaolin; Gong, Fangping; Cao, Di; Hu, Xiuli; Wang, Wei

    2016-03-01

    Under natural conditions, crop plants are frequently subjected to various abiotic environmental stresses such as drought and heat wave, which may become more prevalent in the coming decades. Plant acclimation and tolerance to an abiotic stress are always associated with significant changes in PTMs of specific proteins. PTMs are important for regulating protein function, subcellular localization and protein activity and stability. Studies of plant responses to abiotic stress at the PTMs level are essential to the process of plant phenotyping for crop improvement. The ability to identify and quantify PTMs on a large-scale will contribute to a detailed protein functional characterization that will improve our understanding of the processes of crop plant stress acclimation and stress tolerance acquisition. Hundreds of PTMs have been reported, but it is impossible to review all of the possible protein modifications. In this review, we briefly summarize several main types of PTMs regarding their characteristics and detection methods, review the advances in PTMs research of crop proteomics, and highlight the importance of specific PTMs in crop response to abiotic stress. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Concentration effects on biotic and abiotic processes in the removal of 1,1,2-trichloroethane and vinyl chloride using carbon-amended ZVI

    NASA Astrophysics Data System (ADS)

    Patterson, Bradley M.; Lee, Matthew; Bastow, Trevor P.; Wilson, John T.; Donn, Michael J.; Furness, Andrew; Goodwin, Bryan; Manefield, Mike

    2016-05-01

    A permeable reactive barrier, consisting of both zero valent iron (ZVI) and a biodegradable organic carbon, was evaluated for the remediation of 1,1,2-trichloroethane (1,1,2-TCA) contaminated groundwater. During an 888 day laboratory column study, degradation rates initially stabilized with a degradation half-life of 4.4 ± 0.4 days. Based on the accumulation of vinyl chloride (VC) and limited production of 1,1-dichloroethene (1,1-DCE) and 1,2-dichloroethane (1,2-DCA), the dominant degradation pathway was likely abiotic dichloroelimination to form VC. Degradation of VC was not observed based on the accumulation of VC and limited ethene production. After a step reduction in the influent concentration of 1,1,2-TCA from 170 ± 20 mg L- 1 to 39 ± 11 mg L- 1, the degradation half-life decreased 5-fold to 0.83 ± 0.17 days. The isotopic enrichment factor of 1,1,2-TCA also changed after the step reduction from - 14.6 ± 0.7‰ to - 0.72 ± 0.12‰, suggesting a possible change in the degradation mechanism from abiotic reductive degradation to biodegradation. Microbiological data suggested a co-culture of Desulfitobacterium and Dehalococcoides was responsible for the biodegradation of 1,1,2-TCA to ethene.

  6. ABIOTIC DEHALOGENATION OF 1,2-DICHLOROETHANE AND 1,2-DIBROMETHANE IN AQUEOUS SOLUTION CONTAINING HYDROGEN SULFIDE

    EPA Science Inventory

    The detection of significant levels of halogenated ali- phatic contaminants in groundwater resources in the U- nited States (1, 2) has spurred a considerable effort to understand the various mechanisms-both microbiological and abiotic-by which these compounds may be trans- formed...

  7. Fluid Flow Simulation For CO2-EOR and Sequestration Utilizing Geomechanical Constraints - Teapot Dome Oil Field, Wyoming

    NASA Astrophysics Data System (ADS)

    Chiaramonte, L.; Zoback, M. D.; Friedmann, J.; Stamp, V.

    2007-12-01

    Mature oil and gas reservoirs are attractive targets for geological sequestration of CO2 because of their potential storage capacities and the possible cost offsets from enhanced oil recovery (EOR). In this work we develop a 3D reservoir model and fluid flow simulation of the Tensleep Formation using geomechanical constraints to evaluate the feasibility of a CO2-EOR injection project at Teapot Dome Oil Field, WY. The objective of this work is to model the migration of the injected CO2 as well as to obtain limits on the rates and volumes of CO2 that can be injected without compromising seal integrity. Teapot Dome is an elongated asymmetrical, basement-cored anticline with a north-northwest axis. It is part of the Salt Creek structural trend, located in the southwestern edge of the Powder River Basin. The Tensleep Fm. in this area consists of interdune deposits such as eolian sandstones, sabkha carbonates, evaporites (mostly anhydrite), and some very low permeability dolomicrites. The average porosity is 0.10 ranging from 0.05-0.20. The average permeability is 30 mD, ranging from 10 - 100 mD. The average reservoir thickness is 50 ft. The reservoir has strong aquifer drive. In the area under study, the Tensleep Fm. has its structural crest at 1675 m. It presents a 3-way closure trap against a NE-SW fault to the north. We previously carried out a geomechanical stability analysis and found this fault to be able to support the increase in pressure due to the CO2 to be injected, even if the structure was "filled-to-spill". In this work we combine our previous geomechanical analysis, geostatistical reservoir modeling and fluid flow simulations to investigate critical questions regarding the feasibility of a CO2-EOR project in the Tensleep Fm. The analysis takes into consideration the initial trapping and sealing mechanisms of the reservoir, the consequences of past and present oil production on the initial properties, and the potential effect of CO2 injection on both the

  8. CO2 Washout Testing of NASA Space Suits

    NASA Technical Reports Server (NTRS)

    Norcross, Jason

    2012-01-01

    During the presentation "CO2 Washout Testing of NASA Spacesuits," Jason Norcross discussed the results of recent carbon dioxide CO2 washout testing of NASA spacesuits including the Rear Entry I-suit (REI), Enhanced Mobility Advanced Crew Escape Suit (EM-ACES), and possibly the ACES and Z-1 EVA prototype. When a spacesuit is used during ground testing, adequate CO2 washout must be provided for the suited subject. Symptoms of acute CO2 exposure depend on the partial pressure of CO2 (ppCO2) available to enter the lungs during respiration. The primary factors during ground-based testing that influence the ppCO2 level in the oronasal area include the metabolic rate of the subject and air flow through the suit. These tests were done to characterize inspired oronasal ppCO2 for a range of workloads and flow rates for which ground testing is nominally performed. During this presentation, Norcross provided descriptions of the spacesuits, test hardware, methodology, and results, as well as implications for future ground testing and verification of flight requirements.

  9. Methane-bearing fluids in subduction zones: an experimental study of abiotic methanogenesis during serpentinization at 12 kbar and 300°C

    NASA Astrophysics Data System (ADS)

    Lazar, C.; Manning, C. E.

    2009-12-01

    was approximately twice that of the low pressure experiment. In addition to this kinetic enhancement, high pressure strongly favors calcite dissolution (Caciagli and Manning, 2003), thus providing fluids rich in CO2, a reactant in the canonical hydrothermal abiotic methanogenesis reaction, CO2 + 4H2 = CH4 + 2H2O. Hydrogen should also be common within subduction zones, given the significant potential for serpentinization of ultramafic rocks in the forearc mantle and the oceanic lithospheric mantle. Metasomatism of the forearc mantle by CO2-H2O fluids, for example, should generate methane-rich fluids. The details of high pressure methane are complicated by graphite saturation, fluid flow, carbonate stability, fluid-rock ratio, and other geochemical parameters, to be addressed in the future. Nevertheless, given the likely widespread distribution of high pressure serpentinization environments throughout the Solar System, high pressure methane may play a role in atmospheric methane on Mars, the Faint Young Sun problem on the early Earth, the potential for life on Europa, and the synthesis of prebiotic chemicals on any geologically active planet.

  10. Response and adaptation of photosynthesis, respiration, and antioxidant systems to elevated CO2 with environmental stress in plants

    PubMed Central

    Xu, Zhenzhu; Jiang, Yanling; Zhou, Guangsheng

    2015-01-01

    It is well known that plant photosynthesis and respiration are two fundamental and crucial physiological processes, while the critical role of the antioxidant system in response to abiotic factors is still a focus point for investigating physiological stress. Although one key metabolic process and its response to climatic change have already been reported and reviewed, an integrative review, including several biological processes at multiple scales, has not been well reported. The current review will present a synthesis focusing on the underlying mechanisms in the responses to elevated CO2 at multiple scales, including molecular, cellular, biochemical, physiological, and individual aspects, particularly, for these biological processes under elevated CO2 with other key abiotic stresses, such as heat, drought, and ozone pollution, as well as nitrogen limitation. The present comprehensive review may add timely and substantial information about the topic in recent studies, while it presents what has been well established in previous reviews. First, an outline of the critical biological processes, and an overview of their roles in environmental regulation, is presented. Second, the research advances with regard to the individual subtopics are reviewed, including the response and adaptation of the photosynthetic capacity, respiration, and antioxidant system to CO2 enrichment alone, and its combination with other climatic change factors. Finally, the potential applications for plant responses at various levels to climate change are discussed. The above issue is currently of crucial concern worldwide, and this review may help in a better understanding of how plants deal with elevated CO2 using other mainstream abiotic factors, including molecular, cellular, biochemical, physiological, and whole individual processes, and the better management of the ecological environment, climate change, and sustainable development. PMID:26442017

  11. Absorption of CO2 from modified flue gases of power generation Tarahan chemically using NaOH and Na2CO3 and biologically using microalgae

    NASA Astrophysics Data System (ADS)

    Purba, Elida; Agustina, Dewi; Putri Pertama, Finka; Senja, Fita

    2018-03-01

    This research was carried out on the absorption of CO2 from the modified flue gases of power generation Tarahan using NaOH (sodium hydroxide) and Na2CO3 (sodium carbonate). The operation was conducted in a packed column absorber and then the output gases from the packed column was fed into photo-bioreactor for biological absorption. In the photo-bioreactor, two species of microalgae, N. occulata and T. chuii, were cultivated to both absorb CO2 gas and to produce biomass for algal oil. The aims of this research were, first, to determine the effect of absorbent flow rate on the reduction of CO2 and on the decrease of output gas temperature, second, to determine the characteristics of methyl ester obtained from biological absorption process. Flow rates of the absorbent were varied as 1, 2, and 3 l/min. The concentrations of NaOH and Na2CO3 were 1 M at a constant gas flow rate of 6 l/min. The output concentrations of CO2 from the absorber was analyzed using Gas Chromatography 2014-AT SHIMADZU Corp 08128. The results show that both of the absorbents give different trends. From the absorption using NaOH, it can be concluded that the higher the flow rate, the higher the absorption rate obtained. The highest flow rate achieved maximum absorption of 100%. On the other hand, absorption with Na2CO3 revealed the opposite trend where the higher the flow rates the lower the absorption rate. The highest absorption using Na2CO3 was obtained with the lowest flow rate, 1 l/min, that was 45,5%. As the effect of flow rate on output gas temperature, the temperature decreased with increasing flow rates for both absorbents. The output gas temperature for NaOH and Na2CO3 were consecutively 35 °C and 31 °C with inlet gas temperature of 50°C. Absorption of CO2 biologically resulted a reduction of CO2 up to 60% from the input gas concentration. Algal oil was extracted with mixed hexane and chloroform to obtain algal oil. Extracted oil was transesterified to methyl ester using sodium

  12. SERDP ER-1421 Abiotic and Biotic Mechanisms Controlling In Situ Remediation of NDMA: Final Report

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

    Szecsody, James E.; McKinley, James P.; Crocker, Fiona H.

    This laboratory-scale project was initiated to investigate in situ abiotic/biotic mineralization of NDMA. Under iron-reducing conditions, aquifer sediments showed rapid abiotic NDMA degradation to dimethylamine (DMA), nitrate, formate, and finally, CO2. These are the first reported experiments of abiotic NDMA mineralization. The NDMA reactivity of these different iron phases showed that adsorbed ferrous iron was the dominant reactive phase that promoted NDMA reduction, and other ferrous phases present (siderite, iron sulfide, magnetite, structural ferrous iron in 2:1 clays) did not promote NDMA degradation. In contrast, oxic sediments that were biostimulated with propane promoted biomineralization of NDMA by a cometabolic monooxygenasemore » enzyme process. Other monooxygenase enzyme processes were not stimulated with methane or toluene additions, and acetylene addition did not block mineralization. Although NDMA mineralization extent was the highest in oxic, biostimulated sediments (30 to 82%, compared to 10 to 26% for abiotic mineralization in reduced sediments), large 1-D column studies (high sediment/water ratio of aquifers) showed 5.6 times higher NDMA mineralization rates in reduced sediment (half-life 410 ± 147 h) than oxic biomineralization (half life 2293 ± 1866 h). Sequential reduced/oxic biostimulated sediment mineralization (half-life 3180 ± 1094 h) was also inefficient compared to reduced sediment. These promising laboratory-scale results for NDMA mineralization should be investigated at field scale. Future studies of NDMA remediation should focus on the comparison of this in situ abiotic NDMA mineralization (iron-reducing environments) to ex situ biomineralization, which has been shown successful in other studies.« less

  13. An Ribonuclease T2 Family Protein Modulates Acinetobacter baumannii Abiotic Surface Colonization

    PubMed Central

    Jacobs, Anna C.; Blanchard, Catlyn E.; Catherman, Seana C.; Dunman, Paul M.; Murata, Yoshihiko

    2014-01-01

    Acinetobacter baumannii is an emerging bacterial pathogen of considerable medical concern. The organism's transmission and ability to cause disease has been associated with its propensity to colonize and form biofilms on abiotic surfaces in health care settings. To better understand the genetic determinants that affect biomaterial attachment, we performed a transposon mutagenesis analysis of abiotic surface-colonization using A. baumannii strain 98-37-09. Disruption of an RNase T2 family gene was found to limit the organism's ability to colonize polystyrene, polypropylene, glass, and stainless steel surfaces. DNA microarray analyses revealed that in comparison to wild type and complemented cells, the RNase T2 family mutant exhibited reduced expression of 29 genes, 15 of which are predicted to be associated with bacterial attachment and surface-associated motility. Motility assays confirmed that RNase T2 mutant displays a severe motility defect. Taken together, our results indicate that the RNase T2 family protein identified in this study is a positive regulator of A. baumannii's ability to colonize inanimate surfaces and motility. Moreover, the enzyme may be an effective target for the intervention of biomaterial colonization, and consequently limit the organism's transmission within the hospital setting. PMID:24489668

  14. Steady-state flow of solid CO2: preliminary results

    USGS Publications Warehouse

    Durham, William B.; Kirby, Stephen H.; Stern, Laura A.

    1999-01-01

    To help answer the question of how much solid CO2 exists in the Martian south polar cap, we performed a series of laboratory triaxial deformation experiments at constant displacement rate in compression on jacketed cylinders of pure, polycrystalline CO2. Test conditions were temperatures 150 −8 ≤ ε ≤4.3×10−4 s−1. Most of the measurements follow a constitutive law of the form ε = Aσnexp(−Q/RT), where σ is the applied differential stress, R is the gas constant, and the other constants have values as follows: A = 103 86 MPa−ns−1, n = 5.6, and Q = 33 kJ/mol. Solid CO2 is markedly weaker than water ice. Our results suggest that the south polar cap on Mars is unlikely to be predominately solid CO2, because the elevation and estimated age of the cap is difficult to reconcile with the very weak rheology of the material.

  15. Influence of Capillary Force and Buoyancy on CO2 Migration During CO2 Injection in a Sandstone Reservoir

    NASA Astrophysics Data System (ADS)

    Wu, H.; Pollyea, R.

    2017-12-01

    Carbon capture and sequestration (CCS) is one component of a broad carbon management portfolio designed to mitigate adverse effects of anthropogenic CO2 emissions. During CCS, capillary trapping is an important mechanism for CO2 isolation in the disposal reservoir, and, as a result, the distribution of capillary force is an important factor affecting CO2 migration. Moreover, the movement of CO2 being injected to the reservoir is also affected by buoyancy, which results from the density difference between CO2 and brine. In order to understand interactions between capillary force and buoyancy, we implement a parametric modeling experiment of CO2 injections in a sandstone reservoir for combinations of the van Genuchten capillary pressure model that bound the range of capillary pressure-saturation curves measured in laboratory experiments. We simulate ten years supercritical CO2 (scCO2) injections within a 2-D radially symmetric sandstone reservoir for five combinations of the van Genuchten model parameters λ and entry pressure (P0). Results are analyzed on the basis of a modified dimensionless ratio, ω, which is similar to the Bond number and defines the relationship between buoyancy pressure and capillary pressure. We show how parametric variability affects the relationship between buoyancy and capillary force, and thus controls CO2 plume geometry. These results indicate that when ω >1, then buoyancy governs the system and CO2 plume geometry is governed by upward flow. In contrast, when ω <1, then buoyancy is smaller than capillary force and lateral flow governs CO2 plume geometry. As a result, we show that the ω ratio is an easily implemented screening tool for qualitative assessment of reservoir performance.

  16. Abiotic Versus Biotic Weathering Of Olivine As Possible Biosignatures

    NASA Technical Reports Server (NTRS)

    Longazo, Teresa G.; Wentworth, Susan J.; Clemett, Simon J.; Southam, Gordon; McKay, David S.

    2001-01-01

    We are investigating the weathering of silicate minerals by both purely inorganic, and biologically mediated processes using field-emission scanning electron microscopy (FESEM) and energy dispersive x-ray spectroscopy (EDS). By resolving surface textures and chemical compositions of weathered surfaces at the sub-micron scale we hope to be able to distinguish abiotic from biotic weathering processes and so establish a new biosignature applicable to the study of astromaterials including but not limited to the Martian meteorites. Sterilized olivine grains (San Carlos, Arizona) no more than 1-2 mm in their longest dimension were optically assayed to be uniform in color and free of inclusions were selected as weathering subjects. Prior to all experiments surface morphologies and Fe/Mg ratios were determined for each grain using FE-SEM and EDS. Experiments were divided into two categories abiotic and biotic and were compared with "naturally" weathered samples. For the preliminary experiments, two trials (open and closed to the ambient laboratory environment) were performed under abiotic conditions, and three trials under biotic conditions (control, day 1 and day 2). The open system abiotic trials used sterile grains heated at 98 C and 200 C for both 24 and 48 hours in 1L double distilled de-ionized water. The closed system abiotic trials were conducted under the same conditions but in a sealed two layer steel/Teflon "bomb" apparatus. The biotic trials used sterile grains mounted in a flow-through device attached to a wellhead on the Columbia River aquifer. Several discolored, altered, grains were selected to document "natural" weathering surface textures for comparison with the experimental samples. Preliminary results indicate there are qualitative differences in weathered surface textures among all the designed experiments. The olivine grains in abiotic trials displayed etching, pitting, denticulate margins, dissolution and clay formation. The scale of the features

  17. ABIOTIC O{sub 2} LEVELS ON PLANETS AROUND F, G, K, AND M STARS: POSSIBLE FALSE POSITIVES FOR LIFE?

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

    Harman, C. E.; Kasting, J. F.; Schwieterman, E. W.

    2015-10-20

    In the search for life on Earth-like planets around other stars, the first (and likely only) information will come from the spectroscopic characterization of the planet's atmosphere. Of the countless number of chemical species terrestrial life produces, only a few have the distinct spectral features and the necessary atmospheric abundance to be detectable. The easiest of these species to observe in Earth's atmosphere is O{sub 2} (and its photochemical byproduct, O{sub 3}). However, O{sub 2} can also be produced abiotically by photolysis of CO{sub 2}, followed by recombination of O atoms with each other. CO is produced in stoichiometric proportions. Whethermore » O{sub 2} and CO can accumulate to appreciable concentrations depends on the ratio of far-ultraviolet (FUV) to near-ultraviolet (NUV) radiation coming from the planet's parent star and on what happens to these gases when they dissolve in a planet's oceans. Using a one-dimensional photochemical model, we demonstrate that O{sub 2} derived from CO{sub 2} photolysis should not accumulate to measurable concentrations on planets around F- and G-type stars. K-star, and especially M-star planets, however, may build up O{sub 2} because of the low NUV flux from their parent stars, in agreement with some previous studies. On such planets, a “false positive” for life is possible if recombination of dissolved CO and O{sub 2} in the oceans is slow and if other O{sub 2} sinks (e.g., reduced volcanic gases or dissolved ferrous iron) are small. O{sub 3}, on the other hand, could be detectable at UV wavelengths (λ < 300 nm) for a much broader range of boundary conditions and stellar types.« less

  18. Abiotic and Biotic Formation of Amino Acids in the Enceladus Ocean.

    PubMed

    Steel, Elliot L; Davila, Alfonso; McKay, Christopher P

    2017-09-01

    The active plume at Enceladus' south pole makes the indirect sampling of its global ocean possible. The partially resolved chemistry of the plume, which points to conditions that are seemingly compatible with life, has made orbital sampling missions a priority. We present a conceptual model of energy flux, hydrothermal H 2 production, and both abiotic and biotic production of amino acids. Based on the energy flux observed at the south pole and the inferred internal hydrothermal activity, we estimate an H 2 production of 0.6-34 mol/s from serpentinization, sufficient to sustain abiotic and biotic amino acid synthesis of 1.6-87 and 1-44 g/s, respectively. Two-dimensional (2D) numerical simulations of the hydrothermal vent suggest that the vent fluids could reach the ice-water boundary in less than 11-55 days for a 50 km deep ocean diluted by ambient ocean water 10 to 1. Concentrations of glycine, alanine, α-amino isobutyric acid, and glutamic acid in the plume and in the ambient ocean could all be above 0.01 μM just due to abiotic production. Biological synthesis, if occurring, could produce a maximum of 90 μM concentrations of amino acids based on a methanogenic ecosystem consuming H 2 and CO 2 . Racemization timescales in the ocean are short compared with production timescales. Thus, no enantiomeric excess is expected in the ambient ocean, and if biology is present, enantiomeric excess at the vent fluids is expected to be less than 10% in the plume. From vent H 2 concentrations of 7.8 mM (e.g., Lost City) and assuming complete H 2 use and conversion to chemical energy by methanogens, cell production is estimated. Annual biomass production in the methanogenic-based biology model is 4 × 10 4 -2 × 10 6 kg/year. This corresponds to cell concentrations ∼10 9 cells/cm 3 in the vents and ∼10 8 cells/cm 3 in the plume, and when diluted into the ambient ocean, we predict cell concentrations of 80-4250 cells/cm 3 . Key Words: Abiotic organic

  19. Incorporating the Impacts of Small Scale Rock Heterogeneity into Models of Flow and Trapping in Target UK CO2 Storage Systems

    NASA Astrophysics Data System (ADS)

    Jackson, S. J.; Reynolds, C.; Krevor, S. C.

    2017-12-01

    Predictions of the flow behaviour and storage capacity of CO2 in subsurface reservoirs are dependent on accurate modelling of multiphase flow and trapping. A number of studies have shown that small scale rock heterogeneities have a significant impact on CO2flow propagating to larger scales. The need to simulate flow in heterogeneous reservoir systems has led to the development of numerical upscaling techniques which are widely used in industry. Less well understood, however, is the best approach for incorporating laboratory characterisations of small scale heterogeneities into models. At small scales, heterogeneity in the capillary pressure characteristic function becomes significant. We present a digital rock workflow that combines core flood experiments with numerical simulations to characterise sub-core scale capillary pressure heterogeneities within rock cores from several target UK storage reservoirs - the Bunter, Captain and Ormskirk sandstone formations. Measured intrinsic properties (permeability, capillary pressure, relative permeability) and 3D saturations maps from steady-state core flood experiments were the primary inputs to construct a 3D digital rock model in CMG IMEX. We used vertical end-point scaling to iteratively update the voxel by voxel capillary pressure curves from the average MICP curve; with each iteration more closely predicting the experimental saturations and pressure drops. Once characterised, the digital rock cores were used to predict equivalent flow functions, such as relative permeability and residual trapping, across the range of flow conditions estimated to prevail in the CO2 storage reservoirs. In the case of the Captain sandstone, rock cores were characterised across an entire 100m vertical transect of the reservoir. This allowed analysis of the upscaled impact of small scale heterogeneity on flow and trapping. Figure 1 shows the varying degree to which heterogeneity impacted flow depending on the capillary number in the

  20. 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

  1. Control system of an excitation power supply for fast axial flow CO2 lasersupda

    NASA Astrophysics Data System (ADS)

    Li, Bo; Jia, Xinting; Yuan, Hao; Gao, Yuhu; Wang, Youqing

    2009-08-01

    A switching power control system of fast axial flow CO2 lasers based on DSP is presented. The key techniques are described in detail, include the control principle, realization method and program design. The experiment showed that the system make the laser discharge stably and work in multi-mode. The discharge current can be adjusted from 3mA to 85mA continuously. 20-2000Hz frequency, 0-100% duty cycle laser pulse is achieved. The power supply can improve the processing efficiency and quality.

  2. CO2 Accounting and Risk Analysis for CO2 Sequestration at Enhanced Oil Recovery Sites.

    PubMed

    Dai, Zhenxue; Viswanathan, Hari; Middleton, Richard; Pan, Feng; Ampomah, William; Yang, Changbing; Jia, Wei; Xiao, Ting; Lee, Si-Yong; McPherson, Brian; Balch, Robert; Grigg, Reid; White, Mark

    2016-07-19

    Using CO2 in enhanced oil recovery (CO2-EOR) is a promising technology for emissions management because CO2-EOR can dramatically reduce sequestration costs in the absence of emissions policies that include incentives for carbon capture and storage. This study develops a multiscale statistical framework to perform CO2 accounting and risk analysis in an EOR environment at the Farnsworth Unit (FWU), Texas. A set of geostatistical-based Monte Carlo simulations of CO2-oil/gas-water flow and transport in the Morrow formation are conducted for global sensitivity and statistical analysis of the major risk metrics: CO2/water injection/production rates, cumulative net CO2 storage, cumulative oil/gas productions, and CO2 breakthrough time. The median and confidence intervals are estimated for quantifying uncertainty ranges of the risk metrics. A response-surface-based economic model has been derived to calculate the CO2-EOR profitability for the FWU site with a current oil price, which suggests that approximately 31% of the 1000 realizations can be profitable. If government carbon-tax credits are available, or the oil price goes up or CO2 capture and operating expenses reduce, more realizations would be profitable. The results from this study provide valuable insights for understanding CO2 storage potential and the corresponding environmental and economic risks of commercial-scale CO2-sequestration in depleted reservoirs.

  3. Using thermodynamics to assess biotic and abiotic impediments to root water uptake

    NASA Astrophysics Data System (ADS)

    Bechmann, Marcel; Hildebrandt, Anke; Kleidon, Axel

    2016-04-01

    Root water uptake has been the subject of extensive research, dealing with understanding the processes limiting transpiration and understanding strategies of plants to avoid water stress. Many of those studies use models of water flow from the soil through the plant into the atmosphere to learn about biotic and abiotic factors affecting plant water relations. One important question in this context is to identify those processes that are most limiting to water transport, and specifically whether these processes lie within the plant or the soil? Here, we propose to use a thermodynamic formulation of root water uptake to answer this question. The method allows us to separate the energy exported at the root collar into a sum of energy fluxes related to all processes along the flow path, notably including the effect of increasing water retention in drier soils. Evaluation of the several contributions allows us to identify and rank the processes by how much these impede water flow from the soil to the atmosphere. The application of this approach to a complex 3-dimensional root water uptake model reveals insights on the role of root versus soil resistances to limit water flow. We investigate the efficiency of root water uptake in an ensemble of root systems with varying root hydraulic properties. While root morphology is kept the same, root radial and axial resistances are artificially varied. Starting with entirely young systems (uptake roots, high radial, low axial conductance) we increasingly add older roots (transport roots, high axial, low radial conductance) to improve transport within root systems. This yields a range of root hydraulic architectures, where the extremes are limited either by radial uptake capacity or low capacity to transport water along the root system. We model root water uptake in this range of root systems with a 3-dimensional root water uptake model in two different soils, applying constant flux boundary conditions in a dry down experiment and

  4. Shifting carbon flow from roots into associated microbial communities in response to elevated atmospheric CO2.

    PubMed

    Drigo, Barbara; Pijl, Agata S; Duyts, Henk; Kielak, Anna M; Gamper, Hannes A; Houtekamer, Marco J; Boschker, Henricus T S; Bodelier, Paul L E; Whiteley, Andrew S; van Veen, Johannes A; Kowalchuk, George A

    2010-06-15

    Rising atmospheric CO(2) levels are predicted to have major consequences on carbon cycling and the functioning of terrestrial ecosystems. Increased photosynthetic activity is expected, especially for C-3 plants, thereby influencing vegetation dynamics; however, little is known about the path of fixed carbon into soil-borne communities and resulting feedbacks on ecosystem function. Here, we examine how arbuscular mycorrhizal fungi (AMF) act as a major conduit in the transfer of carbon between plants and soil and how elevated atmospheric CO(2) modulates the belowground translocation pathway of plant-fixed carbon. Shifts in active AMF species under elevated atmospheric CO(2) conditions are coupled to changes within active rhizosphere bacterial and fungal communities. Thus, as opposed to simply increasing the activity of soil-borne microbes through enhanced rhizodeposition, elevated atmospheric CO(2) clearly evokes the emergence of distinct opportunistic plant-associated microbial communities. Analyses involving RNA-based stable isotope probing, neutral/phosphate lipid fatty acids stable isotope probing, community fingerprinting, and real-time PCR allowed us to trace plant-fixed carbon to the affected soil-borne microorganisms. Based on our data, we present a conceptual model in which plant-assimilated carbon is rapidly transferred to AMF, followed by a slower release from AMF to the bacterial and fungal populations well-adapted to the prevailing (myco-)rhizosphere conditions. This model provides a general framework for reappraising carbon-flow paths in soils, facilitating predictions of future interactions between rising atmospheric CO(2) concentrations and terrestrial ecosystems.

  5. Outsourcing CO2 Emissions

    NASA Astrophysics Data System (ADS)

    Davis, S. J.; Caldeira, K. G.

    2009-12-01

    CO2 emissions from the burning of fossil fuels are the primary cause of global warming. Much attention has been focused on the CO2 directly emitted by each country, but relatively little attention has been paid to the amount of emissions associated with consumption of goods and services in each country. This consumption-based emissions inventory differs from the production-based inventory because of imports and exports of goods and services that, either directly or indirectly, involved CO2 emissions. Using the latest available data and reasonable assumptions regarding trans-shipment of embodied carbon through third-party countries, we developed a global consumption-based CO2 emissions inventory and have calculated associated consumption-based energy and carbon intensities. We find that, in 2004, 24% of CO2 emissions are effectively outsourced to other countries, with much of the developed world outsourcing CO2 emissions to emerging markets, principally China. Some wealthy countries, including Switzerland and Sweden, outsource over half of their consumption-based emissions, with many northern Europeans outsourcing more than three tons of emissions per person per year. The United States is both a big importer and exporter of emissions embodied in trade, outsourcing >2.6 tons of CO2 per person and at the same time as >2.0 tons of CO2 per person are outsourced to the United States. These large flows indicate that CO2 emissions embodied in trade must be taken into consideration when considering responsibility for increasing atmospheric greenhouse gas concentrations.

  6. The persistent and pernicious myth of the early CO2-N2 atmospheres of terrestrial planets

    NASA Astrophysics Data System (ADS)

    Shaw, G. H.

    2009-12-01

    The accepted model for early atmospheres of terrestrial planets has settled on a CO2-N2 composition. Unfortunately, while it is largely based on a brilliant geological analysis by Rubey, there is no compelling evidence whatsoever for such a composition as the first “permanent” atmosphere for Earth or any other planet. In fact, geological discoveries of the past 50+ years reveal several problems with a CO2-N2 atmosphere, some of which Rubey recognized in his own analysis. He clearly addressed the problem of timing of degassing, concluding that early massive degassing of CO2 would produce readily observed and profound effects, which are not evident. Modeling and constraints on the timing of planetary accretion and core formation indicate massive early degassing. If early degassing emitted CO2-N2, the effects are concealed. Plate tectonic recycling is not a solution, as conditions would have persisted beyond the time of the earliest rocks, which do not show the effects. Attempts to return degassed CO2 to the mantle are not only ad hoc, but inconsistent with early thermal structure of the Earth. Second, production of prebiotic organic compounds from a CO2-N2 atmosphere has been a nagging problem. At best this has been addressed by invoking hydrogen production from the mantle to provide reducing capacity. While hydrogen may be emitted in volcanic eruptions, it is exceedingly difficult to imagine this process generating enough organics to yield high concentrations in a global ocean. The recent fashion of invoking organic synthesis at deep-sea vents suffers from the same problem: how to achieve sufficient concentrations of organics in a global ocean by abiotic synthesis when hydrothermal activity stirs the solution and carries the prebiotic products off to great dilution? Suggesting life began at deep-sea vents, and continues to carry on chemosynthesis there, begs the question. Unless you get high enough concentrations of prebiotics by abiotic processes, you simply

  7. Abiotic influences on bicarbonate use in the giant kelp, Macrocystis pyrifera, in the Monterey Bay.

    PubMed

    Drobnitch, Sarah Tepler; Nickols, Kerry; Edwards, Matthew

    2017-02-01

    In the Monterey Bay region of central California, the giant kelp Macrocystis pyrifera experiences broad fluctuations in wave forces, temperature, light availability, nutrient availability, and seawater carbonate chemistry, all of which may impact their productivity. In particular, current velocities and light intensity may strongly regulate the supply and demand of inorganic carbon (Ci) as substrates for photosynthesis. Macrocystis pyrifera can acquire and utilize both CO 2 and bicarbonate (HCO 3 - ) as Ci substrates for photosynthesis and growth. Given the variability in carbon delivery (due to current velocities and varying [DIC]) and demand (in the form of saturating irradiance), we hypothesized that the proportion of CO 2 and bicarbonate utilized is not constant for M. pyrifera, but a variable function of their fluctuating environment. We further hypothesized that populations acclimated to different wave exposure and irradiance habitats would display different patterns of bicarbonate uptake. To test these hypotheses, we carried out oxygen evolution trials in the laboratory to measure the proportion of bicarbonate utilized by M. pyrifera via external CA under an orthogonal cross of velocity, irradiance, and acclimation treatments. Our Monterey Bay populations of M. pyrifera exhibited proportionally higher external bicarbonate utilization in high irradiance and high flow velocity conditions than in sub-saturating irradiance or low flow velocity conditions. However, there was no significant difference in proportional bicarbonate use between deep blades and canopy blades, nor between individuals from wave-exposed versus wave-protected sites. This study contributes a new field-oriented perspective on the abiotic controls of carbon utilization physiology in macroalgae. © 2016 Phycological Society of America.

  8. Co-optimization of CO 2 -EOR and Storage Processes under Geological Uncertainty

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

    Ampomah, William; Balch, Robert; Will, Robert

    This paper presents an integrated numerical framework to co-optimize EOR and CO 2 storage performance in the Farnsworth field unit (FWU), Ochiltree County, Texas. The framework includes a field-scale compositional reservoir flow model, an uncertainty quantification model and a neural network optimization process. The reservoir flow model has been constructed based on the field geophysical, geological, and engineering data. A laboratory fluid analysis was tuned to an equation of state and subsequently used to predict the thermodynamic minimum miscible pressure (MMP). A history match of primary and secondary recovery processes was conducted to estimate the reservoir and multiphase flow parametersmore » as the baseline case for analyzing the effect of recycling produced gas, infill drilling and water alternating gas (WAG) cycles on oil recovery and CO 2 storage. A multi-objective optimization model was defined for maximizing both oil recovery and CO 2 storage. The uncertainty quantification model comprising the Latin Hypercube sampling, Monte Carlo simulation, and sensitivity analysis, was used to study the effects of uncertain variables on the defined objective functions. Uncertain variables such as bottom hole injection pressure, WAG cycle, injection and production group rates, and gas-oil ratio among others were selected. The most significant variables were selected as control variables to be used for the optimization process. A neural network optimization algorithm was utilized to optimize the objective function both with and without geological uncertainty. The vertical permeability anisotropy (Kv/Kh) was selected as one of the uncertain parameters in the optimization process. The simulation results were compared to a scenario baseline case that predicted CO 2 storage of 74%. The results showed an improved approach for optimizing oil recovery and CO 2 storage in the FWU. The optimization process predicted more than 94% of CO 2 storage and most importantly about

  9. Co-optimization of CO 2 -EOR and Storage Processes under Geological Uncertainty

    DOE PAGES

    Ampomah, William; Balch, Robert; Will, Robert; ...

    2017-07-01

    This paper presents an integrated numerical framework to co-optimize EOR and CO 2 storage performance in the Farnsworth field unit (FWU), Ochiltree County, Texas. The framework includes a field-scale compositional reservoir flow model, an uncertainty quantification model and a neural network optimization process. The reservoir flow model has been constructed based on the field geophysical, geological, and engineering data. A laboratory fluid analysis was tuned to an equation of state and subsequently used to predict the thermodynamic minimum miscible pressure (MMP). A history match of primary and secondary recovery processes was conducted to estimate the reservoir and multiphase flow parametersmore » as the baseline case for analyzing the effect of recycling produced gas, infill drilling and water alternating gas (WAG) cycles on oil recovery and CO 2 storage. A multi-objective optimization model was defined for maximizing both oil recovery and CO 2 storage. The uncertainty quantification model comprising the Latin Hypercube sampling, Monte Carlo simulation, and sensitivity analysis, was used to study the effects of uncertain variables on the defined objective functions. Uncertain variables such as bottom hole injection pressure, WAG cycle, injection and production group rates, and gas-oil ratio among others were selected. The most significant variables were selected as control variables to be used for the optimization process. A neural network optimization algorithm was utilized to optimize the objective function both with and without geological uncertainty. The vertical permeability anisotropy (Kv/Kh) was selected as one of the uncertain parameters in the optimization process. The simulation results were compared to a scenario baseline case that predicted CO 2 storage of 74%. The results showed an improved approach for optimizing oil recovery and CO 2 storage in the FWU. The optimization process predicted more than 94% of CO 2 storage and most importantly about

  10. Increased soil emissions of potent greenhouse gases under increased atmospheric CO2.

    PubMed

    van Groenigen, Kees Jan; Osenberg, Craig W; Hungate, Bruce A

    2011-07-13

    Increasing concentrations of atmospheric carbon dioxide (CO(2)) can affect biotic and abiotic conditions in soil, such as microbial activity and water content. In turn, these changes might be expected to alter the production and consumption of the important greenhouse gases nitrous oxide (N(2)O) and methane (CH(4)) (refs 2, 3). However, studies on fluxes of N(2)O and CH(4) from soil under increased atmospheric CO(2) have not been quantitatively synthesized. Here we show, using meta-analysis, that increased CO(2) (ranging from 463 to 780 parts per million by volume) stimulates both N(2)O emissions from upland soils and CH(4) emissions from rice paddies and natural wetlands. Because enhanced greenhouse-gas emissions add to the radiative forcing of terrestrial ecosystems, these emissions are expected to negate at least 16.6 per cent of the climate change mitigation potential previously predicted from an increase in the terrestrial carbon sink under increased atmospheric CO(2) concentrations. Our results therefore suggest that the capacity of land ecosystems to slow climate warming has been overestimated. ©2011 Macmillan Publishers Limited. All rights reserved

  11. The relative abundances of resolved l2CH2D2 and 13CH3D and mechanisms controlling isotopic bond ordering in abiotic and biotic methane gases

    NASA Astrophysics Data System (ADS)

    Young, E. D.; Kohl, I. E.; Lollar, B. Sherwood; Etiope, G.; Rumble, D.; Li, S.; Haghnegahdar, M. A.; Schauble, E. A.; McCain, K. A.; Foustoukos, D. I.; Sutclife, C.; Warr, O.; Ballentine, C. J.; Onstott, T. C.; Hosgormez, H.; Neubeck, A.; Marques, J. M.; Pérez-Rodríguez, I.; Rowe, A. R.; LaRowe, D. E.; Magnabosco, C.; Yeung, L. Y.; Ash, J. L.; Bryndzia, L. T.

    2017-04-01

    We report measurements of resolved 12CH2D2 and 13CH3D at natural abundances in a variety of methane gases produced naturally and in the laboratory. The ability to resolve 12CH2D2 from 13CH3D provides unprecedented insights into the origin and evolution of CH4. The results identify conditions under which either isotopic bond order disequilibrium or equilibrium are expected. Where equilibrium obtains, concordant Δ12CH2D2 and Δ13CH3D temperatures can be used reliably for thermometry. We find that concordant temperatures do not always match previous hypotheses based on indirect estimates of temperature of formation nor temperatures derived from CH4/H2 D/H exchange, underscoring the importance of reliable thermometry based on the CH4 molecules themselves. Where Δ12CH2D2 and Δ13CH3D values are inconsistent with thermodynamic equilibrium, temperatures of formation derived from these species are spurious. In such situations, while formation temperatures are unavailable, disequilibrium isotopologue ratios nonetheless provide novel information about the formation mechanism of the gas and the presence or absence of multiple sources or sinks. In particular, disequilibrium isotopologue ratios may provide the means for differentiating between methane produced by abiotic synthesis vs. biological processes. Deficits in 12CH2D2 compared with equilibrium values in CH4 gas made by surface-catalyzed abiotic reactions are so large as to point towards a quantum tunneling origin. Tunneling also accounts for the more moderate depletions in 13CH3D that accompany the low 12CH2D2 abundances produced by abiotic reactions. The tunneling signature may prove to be an important tracer of abiotic methane formation, especially where it is preserved by dissolution of gas in cool hydrothermal systems (e.g., Mars). Isotopologue signatures of abiotic methane production can be erased by infiltration of microbial communities, and Δ12CH2D2 values are a key tracer of microbial recycling.

  12. Numerical Studies of Fluid Leakage from a Geologic DisposalReservoir for CO2 Show Self-Limiting Feedback between Fluid Flow and HeatTransfer

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

    Pruess, Karsten

    2005-03-22

    Leakage of CO2 from a hypothetical geologic storage reservoir along an idealized fault zone has been simulated, including transitions between supercritical, liquid, and gaseous CO2. We find strong non-isothermal effects due to boiling and Joule-Thomson cooling of expanding CO2. Leakage fluxes are limited by limitations in conductive heat transfer to the fault zone. The interplay between multiphase flow and heat transfer effects produces non-monotonic leakage behavior.

  13. A membraneless single compartment abiotic glucose fuel cell

    NASA Astrophysics Data System (ADS)

    Slaughter, Gymama; Sunday, Joshua

    2014-09-01

    A simple energy harvesting strategy has been developed to selectively catalyze glucose in the presence of oxygen in a glucose/O2 fuel cell. The anode consists of an abiotic catalyst Al/Au/ZnO, in which ZnO seed layer was deposited on the surface of Al/Au substrate using hydrothermal method. The cathode is constructed from a single rod of platinum with an outer diameter of 500 μm. The abiotic glucose fuel cell was studied in phosphate buffer solution (pH 7.4) containing 5 mM glucose at a temperature of 22 °C. The cell is characterized according to its open-circuit voltage, polarization profile, and power density plot. Under these conditions, the abiotic glucose fuel cell possesses an open-circuit voltage of 840 mV and delivered a maximum power density of 16.2 μW cm-2 at a cell voltage of 495 mV. These characteristics are comparable to biofuel cell utilizing a much more complex system design. Such low-cost lightweight abiotic catalyzed glucose fuel cells have a great promise to be optimized, miniaturized to power bio-implantable devices.

  14. A Critical Review of the Impacts of Leaking CO 2 Gas and Brine on Groundwater Quality

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

    Qafoku, Nikolla; Zheng, Liange; Bacon, Diana H.

    2015-09-30

    Geological carbon sequestration (GCS) is a global carbon emission reduction strategy involving the capture of CO 2 emitted from fossil fuel burning power plants, as well as the subsequent injection of the captured CO 2 gas into deep saline aquifers or depleted oil and gas reservoirs. A critical question that arises from the proposed GCS is the potential impacts of CO 2 injection on the quality of drinking-water systems overlying CO 2 sequestration storage sites. Although storage reservoirs are evaluated and selected based on their ability to safely and securely store emplaced fluids, leakage of CO 2 from storage reservoirsmore » is a primary risk factor and potential barrier to the widespread acceptance of geologic CO 2 sequestration (OR Harvey et al. 2013; Y-S Jun et al. 2013; DOE 2007). Therefore, a systematic understanding of how CO 2 leakage would affect the geochemistry of potable aquifers, and subsequently control or affect elemental and contaminant release via sequential and/or simultaneous abiotic and biotic processes and reactions is vital.« less

  15. The Relative Abundances of Resolved 12CH2D2 and 13CH3D and Mechanisms Controlling Isotopic Bond Ordering in Abiotic and Biotic Methane Gases

    NASA Astrophysics Data System (ADS)

    Young, E. D.; Kohl, I. E.; Sherwood Lollar, B.; Etiope, G.; Rumble, D.; Li, S.; Haghnegahdar, M. A.; Schauble, E. A.; McCain, K.; Foustoukos, D.; Sutcliffe, C. N.; Warr, O.; Ballentine, C. J.; Onstott, T. C.; Hosgormez, H.; Neubeck, A.; Marques, J. M.; Perez-Rodriguez, I. M.; Rowe, A. R.; LaRowe, D.; Magnabosco, C.; Bryndzia, T.

    2016-12-01

    We report measurements of resolved 12CH2D2 and 13CH3D at natural abundances in a variety of methane gases produced naturally and in the laboratory. The ability to resolve 12CH2D2 from 13CH3D provides unprecedented insights into the origin and evolution of CH4. The results identify conditions under which either isotopic bond order disequilibrium or equilibrium are expected. Where equilibrium obtains, concordant Δ12CH2D2 and Δ13CH3D temperatures can be used reliably for thermometry. We find that concordant temperatures do not always match previous hypotheses based on indirect estimates of temperature of formation nor temperatures derived from CH4/H2 D/H exchange, underscoring the importance of reliable thermometry based on the CH4 molecules themselves. Where Δ12CH2D2 and Δ13CH3D values are inconsistent with thermodynamic equilibrium, temperatures of formation derived from these species are spurious. In such situations, while formation temperatures are unavailable, disequilibrium isotopologue ratios nonetheless provide important information about the formation mechanism of the gas and the presence or absence of multiple sources or sinks. In particular, disequilibrium isotopologue ratios may provide the means for differentiating between methane produced by abiotic synthesis versus biological processes. Deficits in 12CH2D2 compared with equilibrium values in CH4 gas made by surface-catalyzed abiotic reactions are so large as to point towards a quantum tunneling origin. Tunneling also accounts for the more moderate depletions in 13CH3D that accompany the low 12CH2D2 abundances produced by abiotic reactions. The tunneling signature of abiotic CH4 formation may prove to be an important tracer of abiotic methane formation, especially where it is preserved by dissolution of gas in cool hydrothermal systems (e.g., Mars). Isotopologue signatures of abiotic methane production can be erased by infiltration of microbial communities, and Δ12CH2D2 values are a key tracer of

  16. Evolutionary History and Novel Biotic Interactions Determine Plant Responses to Elevated CO2 and Nitrogen Fertilization

    PubMed Central

    Wooliver, Rachel; Senior, John K.; Schweitzer, Jennifer A.; O'Reilly-Wapstra, Julianne M.; Langley, J. Adam; Chapman, Samantha K.; Bailey, Joseph K.

    2014-01-01

    A major frontier in global change research is predicting how multiple agents of global change will alter plant productivity, a critical component of the carbon cycle. Recent research has shown that plant responses to climate change are phylogenetically conserved such that species within some lineages are more productive than those within other lineages in changing environments. However, it remains unclear how phylogenetic patterns in plant responses to changing abiotic conditions may be altered by another agent of global change, the introduction of non-native species. Using a system of 28 native Tasmanian Eucalyptus species belonging to two subgenera, Symphyomyrtus and Eucalyptus, we hypothesized that productivity responses to abiotic agents of global change (elevated CO2 and increased soil N) are unique to lineages, but that novel interactions with a non-native species mediate these responses. We tested this hypothesis by examining productivity of 1) native species monocultures and 2) mixtures of native species with an introduced hardwood plantation species, Eucalyptus nitens, to experimentally manipulated soil N and atmospheric CO2. Consistent with past research, we found that N limits productivity overall, especially in elevated CO2 conditions. However, monocultures of species within the Symphyomyrtus subgenus showed the strongest response to N (gained 127% more total biomass) in elevated CO2 conditions, whereas those within the Eucalyptus subgenus did not respond to N. Root:shoot ratio (an indicator of resource use) was on average greater in species pairs containing Symphyomyrtus species, suggesting that functional traits important for resource uptake are phylogenetically conserved and explaining the phylogenetic pattern in plant response to changing environmental conditions. Yet, native species mixtures with E. nitens exhibited responses to CO2 and N that differed from those of monocultures, supporting our hypothesis and highlighting that both plant

  17. Evolutionary history and novel biotic interactions determine plant responses to elevated CO2 and nitrogen fertilization.

    PubMed

    Wooliver, Rachel; Senior, John K; Schweitzer, Jennifer A; O'Reilly-Wapstra, Julianne M; Langley, J Adam; Chapman, Samantha K; Bailey, Joseph K

    2014-01-01

    A major frontier in global change research is predicting how multiple agents of global change will alter plant productivity, a critical component of the carbon cycle. Recent research has shown that plant responses to climate change are phylogenetically conserved such that species within some lineages are more productive than those within other lineages in changing environments. However, it remains unclear how phylogenetic patterns in plant responses to changing abiotic conditions may be altered by another agent of global change, the introduction of non-native species. Using a system of 28 native Tasmanian Eucalyptus species belonging to two subgenera, Symphyomyrtus and Eucalyptus, we hypothesized that productivity responses to abiotic agents of global change (elevated CO2 and increased soil N) are unique to lineages, but that novel interactions with a non-native species mediate these responses. We tested this hypothesis by examining productivity of 1) native species monocultures and 2) mixtures of native species with an introduced hardwood plantation species, Eucalyptus nitens, to experimentally manipulated soil N and atmospheric CO2. Consistent with past research, we found that N limits productivity overall, especially in elevated CO2 conditions. However, monocultures of species within the Symphyomyrtus subgenus showed the strongest response to N (gained 127% more total biomass) in elevated CO2 conditions, whereas those within the Eucalyptus subgenus did not respond to N. Root:shoot ratio (an indicator of resource use) was on average greater in species pairs containing Symphyomyrtus species, suggesting that functional traits important for resource uptake are phylogenetically conserved and explaining the phylogenetic pattern in plant response to changing environmental conditions. Yet, native species mixtures with E. nitens exhibited responses to CO2 and N that differed from those of monocultures, supporting our hypothesis and highlighting that both plant

  18. 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.

  19. A phase-field lattice Boltzmann model for simulating multiphase flows in porous media: Application and comparison to experiments of CO2 sequestration at pore scale

    NASA Astrophysics Data System (ADS)

    Fakhari, Abbas; Li, Yaofa; Bolster, Diogo; Christensen, Kenneth T.

    2018-04-01

    We implement a phase-field based lattice-Boltzmann (LB) method for numerical simulation of multiphase flows in heterogeneous porous media at pore scales with wettability effects. The present method can handle large density and viscosity ratios, pertinent to many practical problems. As a practical application, we study multiphase flow in a micromodel representative of CO2 invading a water-saturated porous medium at reservoir conditions, both numerically and experimentally. We focus on two flow cases with (i) a crossover from capillary fingering to viscous fingering at a relatively small capillary number, and (ii) viscous fingering at a relatively moderate capillary number. Qualitative and quantitative comparisons are made between numerical results and experimental data for temporal and spatial CO2 saturation profiles, and good agreement is found. In particular, a correlation analysis shows that any differences between simulations and results are comparable to intra-experimental differences from replicate experiments. A key conclusion of this work is that system behavior is highly sensitive to boundary conditions, particularly inlet and outlet ones. We finish with a discussion on small-scale flow features, such as the emergence of strong recirculation zones as well as flow in which the residual phase is trapped, including a close look at the detailed formation of a water cone. Overall, the proposed model yields useful information, such as the spatiotemporal evolution of the CO2 front and instantaneous velocity fields, which are valuable for understanding the mechanisms of CO2 infiltration at the pore scale.

  20. ABIOTIC IN SITU TECHNOLOGIES FOR GROUNDWATER REMEDIATION CONFERENCE: PROCEEDINGS

    EPA Science Inventory

    The USEPA conference on Abiotic In Situ Technologies for Groundwater Remediation was held in Dallas, TX, 8/31-9/2/99. The goal of the meeting was to disseminate current information on abiotic in situ groundwater treatment echnologies. Although much information is being provided a...

  1. Nitrogen isotopic fractionation during abiotic synthesis of organic solid particles

    NASA Astrophysics Data System (ADS)

    Kuga, Maïa; Carrasco, Nathalie; Marty, Bernard; Marrocchi, Yves; Bernard, Sylvain; Rigaudier, Thomas; Fleury, Benjamin; Tissandier, Laurent

    2014-05-01

    The formation of organic compounds is generally assumed to result from abiotic processes in the Solar System, with the exception of biogenic organics on Earth. Nitrogen-bearing organics are of particular interest, notably for prebiotic perspectives but also for overall comprehension of organic formation in the young Solar System and in planetary atmospheres. We have investigated abiotic synthesis of organics upon plasma discharge, with special attention to N isotope fractionation. Organic aerosols were synthesized from N2-CH4 and N2-CO gaseous mixtures using low-pressure plasma discharge experiments, aimed at simulating chemistry occurring in Titan's atmosphere and in the protosolar nebula, respectively. The nitrogen content, the N speciation and the N isotopic composition were analyzed in the resulting organic aerosols. Nitrogen is efficiently incorporated into the synthesized solids, independently of the oxidation degree, of the N2 content of the starting gas mixture, and of the nitrogen speciation in the aerosols. The aerosols are depleted in 15N by 15-25‰ relative to the initial N2 gas, whatever the experimental setup is. Such an isotopic fractionation is attributed to mass-dependent kinetic effect(s). Nitrogen isotope fractionation upon electric discharge cannot account for the large N isotope variations observed among Solar System objects and reservoirs. Extreme N isotope signatures in the Solar System are more likely the result of self-shielding during N2 photodissociation, exotic effect during photodissociation of N2 and/or low temperature ion-molecule isotope exchange. Kinetic N isotope fractionation may play a significant role in the Titan's atmosphere. On the Titan's night side, 15N-depletion resulting from electron driven reactions may counterbalance photo-induced 15N enrichments occurring on the day's side. We also suggest that the low δ15N values of Archaean organic matter (Beaumont and Robert, 1999) are partly the result of abiotic synthesis of

  2. Carbon Isotopes of Alkanes in Hydrothermal Abiotic Organic Synthesis Processes at High Temperatures and Pressures: An Experimental Study

    NASA Technical Reports Server (NTRS)

    Fu, Qi; Socki, Richard A.; Niles, Paul B.

    2010-01-01

    Observation of methane in the Martian atmosphere has been reported by different detection techniques [1-4]. With more evidence showing extensive water-rock interaction in Martian history [5-7], abiotic formation by Fischer-Tropsch Type (FTT) synthesis during serpentization reactions may be one possible process responsible for methane generation on Mars [8, 9]. While the experimental studies performed to date leave little doubt that chemical reactions exist for the abiotic synthesis of organic compounds by mineral surface-catalyzed reactions [10-12], little is known about the reaction pathways by which CO2 and/or CO are reduced under hydrothermal conditions. Carbon and hydrogen isotope measurements of alkanes have been used as an effective tool to constrain the origin and reaction pathways of hydrocarbon formation. Alkanes generated by thermal breakdown of high molecular weight organic compounds have carbon and hydrogen isotopic signatures completely distinct from those formed abiotically [13-15]. Recent experimental studies, however, showed that different abiogenic hydrocarbon formation processes (e.g., polymerization vs. depolymerization) may have different carbon and hydrogen isotopic patterns [16]. Results from previous experiments studying decomposition of higher molecular weight organic compounds (lignite) also suggested that pressure could be a crucial factor affecting fractionation of carbon isotopes [17]. Under high pressure conditions, no experimental data are available describing fractionation of carbon isotope during mineral catalyzed FTT synthesis. Thus, hydrothermal experiments present an excellent opportunity to provide the requisite carbon isotope data. Such data can also be used to identify reaction pathways of abiotic organic synthesis under experimental conditions.

  3. FLAVODIIRON2 and FLAVODIIRON4 Proteins Mediate an Oxygen-Dependent Alternative Electron Flow in Synechocystis sp. PCC 6803 under CO2-Limited Conditions1[OPEN

    PubMed Central

    Shimakawa, Ginga; Shaku, Keiichiro; Nishi, Akiko; Hayashi, Ryosuke; Yamamoto, Hiroshi; Sakamoto, Katsuhiko; Makino, Amane; Miyake, Chikahiro

    2015-01-01

    This study aims to elucidate the molecular mechanism of an alternative electron flow (AEF) functioning under suppressed (CO2-limited) photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803. Photosynthetic linear electron flow, evaluated as the quantum yield of photosystem II [Y(II)], reaches a maximum shortly after the onset of actinic illumination. Thereafter, Y(II) transiently decreases concomitantly with a decrease in the photosynthetic oxygen evolution rate and then recovers to a rate that is close to the initial maximum. These results show that CO2 limitation suppresses photosynthesis and induces AEF. In contrast to the wild type, Synechocystis sp. PCC 6803 mutants deficient in the genes encoding FLAVODIIRON2 (FLV2) and FLV4 proteins show no recovery of Y(II) after prolonged illumination. However, Synechocystis sp. PCC 6803 mutants deficient in genes encoding proteins functioning in photorespiration show AEF activity similar to the wild type. In contrast to Synechocystis sp. PCC 6803, the cyanobacterium Synechococcus elongatus PCC 7942 has no FLV proteins with high homology to FLV2 and FLV4 in Synechocystis sp. PCC 6803. This lack of FLV2/4 may explain why AEF is not induced under CO2-limited photosynthesis in S. elongatus PCC 7942. As the glutathione S-transferase fusion protein overexpressed in Escherichia coli exhibits NADH-dependent oxygen reduction to water, we suggest that FLV2 and FLV4 mediate oxygen-dependent AEF in Synechocystis sp. PCC 6803 when electron acceptors such as CO2 are not available. PMID:25540330

  4. Extracorporeal CO2 removal by hemodialysis: in vitro model and feasibility.

    PubMed

    May, Alexandra G; Sen, Ayan; Cove, Matthew E; Kellum, John A; Federspiel, William J

    2017-12-01

    Critically ill patients with acute respiratory distress syndrome and acute exacerbations of chronic obstructive pulmonary disease often develop hypercapnia and require mechanical ventilation. Extracorporeal carbon dioxide removal can manage hypercarbia by removing carbon dioxide directly from the bloodstream. Respiratory hemodialysis uses traditional hemodialysis to remove CO 2 from the blood, mainly as bicarbonate. In this study, Stewart's approach to acid-base chemistry was used to create a dialysate that would maintain blood pH while removing CO 2 as well as determine the blood and dialysate flow rates necessary to remove clinically relevant CO 2 volumes. Bench studies were performed using a scaled down respiratory hemodialyzer in bovine or porcine blood. The scaling factor for the bench top experiments was 22.5. In vitro dialysate flow rates ranged from 2.2 to 24 mL/min (49.5-540 mL/min scaled up) and blood flow rates were set at 11 and 18.7 mL/min (248-421 mL/min scaled up). Blood inlet CO 2 concentrations were set at 50 and 100 mmHg. Results are reported as scaled up values. The CO 2 removal rate was highest at intermittent hemodialysis blood and dialysate flow rates. At an inlet pCO 2 of 50 mmHg, the CO 2 removal rate increased from 62.6 ± 4.8 to 77.7 ± 3 mL/min when the blood flow rate increased from 248 to 421 mL/min. At an inlet pCO 2 of 100 mmHg, the device was able to remove up to 117.8 ± 3.8 mL/min of CO 2 . None of the test conditions caused the blood pH to decrease, and increases were ≤0.08. When the bench top data is scaled up, the system removes a therapeutic amount of CO 2 standard intermittent hemodialysis flow rates. The zero bicarbonate dialysate did not cause acidosis in the post-dialyzer blood. These results demonstrate that, with further development, respiratory hemodialysis can be a minimally invasive extracorporeal carbon dioxide removal treatment option.

  5. Investigation of operating parameters on CO2 splitting by dielectric barrier discharge plasma

    NASA Astrophysics Data System (ADS)

    Pan, CHEN; Jun, SHEN; Tangchun, RAN; Tao, YANG; Yongxiang, YIN

    2017-12-01

    Experiments of CO2 splitting by dielectric barrier discharge (DBD) plasma were carried out, and the influence of CO2 flow rate, plasma power, discharge voltage, discharge frequency on CO2 conversion and process energy efficiency were investigated. It was shown that the absolute quantity of CO2 decomposed was only proportional to the amount of conductive electrons across the discharge gap, and the electron amount was proportional to the discharge power; the energy efficiency of CO2 conversion was almost a constant at a lower level, which was limited by CO2 inherent discharge character that determined a constant gap electric field strength. This was the main reason why CO2 conversion rate decreased as the CO2 flow rate increase and process energy efficiency was decreased a little as applied frequency increased. Therefore, one can improve the CO2 conversion by less feed flow rate or larger discharge power in DBD plasma, but the energy efficiency is difficult to improve.

  6. TOUGH2Biot - A simulator for coupled thermal-hydrodynamic-mechanical processes in subsurface flow systems: Application to CO2 geological storage and geothermal development

    NASA Astrophysics Data System (ADS)

    Lei, Hongwu; Xu, Tianfu; Jin, Guangrong

    2015-04-01

    Coupled thermal-hydrodynamic-mechanical processes have become increasingly important in studying the issues affecting subsurface flow systems, such as CO2 sequestration in deep saline aquifers and geothermal development. In this study, a mechanical module based on the extended Biot consolidation model was developed and incorporated into the well-established thermal-hydrodynamic simulator TOUGH2, resulting in an integrated numerical THM simulation program TOUGH2Biot. A finite element method was employed to discretize space for rock mechanical calculation and the Mohr-Coulomb failure criterion was used to determine if the rock undergoes shear-slip failure. Mechanics is partly coupled with the thermal-hydrodynamic processes and gives feedback to flow through stress-dependent porosity and permeability. TOUGH2Biot was verified against analytical solutions for the 1D Terzaghi consolidation and cooling-induced subsidence. TOUGH2Biot was applied to evaluate the thermal, hydrodynamic, and mechanical responses of CO2 geological sequestration at the Ordos CCS Demonstration Project, China and geothermal exploitation at the Geysers geothermal field, California. The results demonstrate that TOUGH2Biot is capable of analyzing change in pressure and temperature, displacement, stress, and potential shear-slip failure caused by large scale underground man-made activity in subsurface flow systems. TOUGH2Biot can also be easily extended for complex coupled process problems in fractured media and be conveniently updated to parallel versions on different platforms to take advantage of high-performance computing.

  7. Gaussian-reflectivity mirror resonator for a high-power transverse-flow CO2 laser.

    PubMed

    Ling, Dongxiong; Chen, Junruo; Li, Junchang

    2006-05-01

    A Gaussian-reflectivity mirror resonator is proposed to achieve high-quality laser beams. To analyze the laser fields in a Gaussian-reflectivity mirror resonator, the diffraction integral equations of a Gaussian-reflectivity mirror resonator are converted to the finite-sum matrix equations. Consequently, according to the Fox-Li laser self-reproducing principle, we describe the mode fields and their losses in the proposed resonator as eigenvectors and eigenvalues of a transfer matrix. The conclusion can be drawn from the numerical results that, if a Gaussian-reflectivity mirror is adopted for a plano-concave resonator, a fundamental mode can easily be obtained from a transverse-flow CO2 laser and high-quality laser beams can be expected.

  8. Influence of abiotic stress signals on secondary metabolites in plants

    PubMed Central

    Ramakrishna, Akula; Ravishankar, Gokare Aswathanarayana

    2011-01-01

    Plant secondary metabolites are unique sources for pharmaceuticals, food additives, flavors, and industrially important biochemicals. Accumulation of such metabolites often occurs in plants subjected to stresses including various elicitors or signal molecules. Secondary metabolites play a major role in the adaptation of plants to the environment and in overcoming stress conditions. Environmental factors viz. temperature, humidity, light intensity, the supply of water, minerals, and CO2 influence the growth of a plant and secondary metabolite production. Drought, high salinity, and freezing temperatures are environmental conditions that cause adverse effects on the growth of plants and the productivity of crops. Plant cell culture technologies have been effective tools for both studying and producing plant secondary metabolites under in vitro conditions and for plant improvement. This brief review summarizes the influence of different abiotic factors include salt, drought, light, heavy metals, frost etc. on secondary metabolites in plants. The focus of the present review is the influence of abiotic factors on secondary metabolite production and some of important plant pharmaceuticals. Also, we describe the results of in vitro cultures and production of some important secondary metabolites obtained in our laboratory. PMID:22041989

  9. CO2 transport over complex terrain

    USGS Publications Warehouse

    Sun, Jielun; Burns, Sean P.; Delany, A.C.; Oncley, S.P.; Turnipseed, A.A.; Stephens, B.B.; Lenschow, D.H.; LeMone, M.A.; Monson, Russell K.; Anderson, D.E.

    2007-01-01

    CO2 transport processes relevant for estimating net ecosystem exchange (NEE) at the Niwot Ridge AmeriFlux site in the front range of the Rocky Mountains, Colorado, USA, were investigated during a pilot experiment. We found that cold, moist, and CO2-rich air was transported downslope at night and upslope in the early morning at this forest site situated on a ???5% east-facing slope. We found that CO2 advection dominated the total CO2 transport in the NEE estimate at night although there are large uncertainties because of partial cancellation of horizontal and vertical advection. The horizontal CO2 advection captured not only the CO2 loss at night, but also the CO2 uptake during daytime. We found that horizontal CO2 advection was significant even during daytime especially when turbulent mixing was not significant, such as in early morning and evening transition periods and within the canopy. Similar processes can occur anywhere regardless of whether flow is generated by orography, synoptic pressure gradients, or surface heterogeneity as long as CO2 concentration is not well mixed by turbulence. The long-term net effect of all the CO2 budget terms on estimates of NEE needs to be investigated. ?? 2007 Elsevier B.V. All rights reserved.

  10. Virtual CO2 Emission Flows in the Global Electricity Trade Network.

    PubMed

    Qu, Shen; Li, Yun; Liang, Sai; Yuan, Jiahai; Xu, Ming

    2018-06-05

    Quantifying greenhouse gas emissions due to electricity consumption is crucial for climate mitigation in the electric power sector. Current practices primarily use production-based emission factors to quantify emissions for electricity consumption, assuming production and consumption of electricity take place within the same region. The increasingly intensified cross-border electricity trade complicates the accounting for emissions of electricity consumption. This study employs a network approach to account for the flows in the whole electricity trade network to estimate CO 2 emissions of electricity consumption for 137 major countries/regions in 2014. Results show that in some countries, especially those in Europe and Southern Africa, the impacts of electricity trade on the estimation of emission factors and embodied emissions are significant. The changes made to emission factors by considering intergrid electricity trade can have significant implications for emission accounting and climate mitigation when multiplied by total electricity consumption of the corresponding countries/regions.

  11. Abiotic Nitrous Oxide Production in Natural and Artificial Seawater

    NASA Astrophysics Data System (ADS)

    Ochoa, H.; Stanton, C. L.; Cavazos, A. R.; Ostrom, N. E.; Glass, J. B.

    2014-12-01

    The ocean contributes approximately one third of global sources of nitrous oxide (N2O) to the atmosphere. While nitrification is thought to be the dominant pathway for marine N2O production, mechanisms remain unresolved. Previous studies have carried the implicit assumption that marine N2O originates directly from enzymatic sources. However, abiotic production of N2O is possible via chemical reactions between nitrogenous intermediates and redox active trace metals in seawater. In this study, we investigated N2O production and isotopic composition in treatments with and without added hydroxylamine (NH2OH) and nitric oxide (NO), intermediates in microbial oxidation of ammonia to nitrite, and Fe(III). Addition of substrates to sterile artificial seawater was compared with filtered and unfiltered seawater from Sapelo Island, coastal Georgia, USA. N2O production was observed immediately after addition of Fe(III) in the presence of NH2OH at pH 8 in sterile artificial seawater. Highest N2O production was observed in the presence of Fe(III), NO, and NH2OH. The isotopomer site preference of abiotically produced N2O was consistent with previous studies (31 ± 2 ‰). Higher abiotic N2O production was observed in sterile artificial seawater (salinity: 35 ppt) than filtered Sapelo Island seawater (salinity: 25 ppt) whereas diluted sterile artificial seawater (18 ppt) showed lowest N2O production, suggesting that higher salinity promotes enhanced abiotic N2O production. Addition of Fe(III) to unfiltered Sapelo Island seawater stimulated N2O production. The presence of ammonia-oxidizing archaea (AOA), which lack known N2O producing enzymes, in Sapelo Island seawater was confirmed by successful amplification of the archaeal amoA gene, whereas ammonia-oxidizing bacteria (AOB), which contain N2O-producing enzymes were undetected. Given the few Fe-containing proteins present in AOA, it is likely that Fe(III) addition promoted N2O production via an abiotic vs. enzymatic N2O mechanism

  12. Inhibitory effect of carbon dioxide on the fed-batch culture of Ralstonia eutropha: evaluation by CO2 pulse injection and autogenous CO2 methods.

    PubMed

    Shang, Longan; Jiang, Min; Ryu, Chul Hee; Chang, Ho Nam; Cho, Soon Haeng; Lee, Jong Won

    2003-08-05

    In order to see the effect of CO(2) inhibition resulting from the use of pure oxygen, we carried out a comparative fed-batch culture study of polyhydroxybutyric acid (PHB) production by Ralstonia eutropha using air and pure oxygen in 5-L, 30-L, and 300-L fermentors. The final PHB concentrations obtained with pure O(2) were 138.7 g/L in the 5-L fermentor and 131.3 g/L in the 30-L fermentor, which increased 2.9 and 6.2 times, respectively, as compared to those obtained with air. In the 300-L fermentor, the fed-batch culture with air yielded only 8.4 g/L PHB. However, the maximal CO(2) concentrations in the 5-L fermentor increased significantly from 4.1% (air) to 15.0% (pure O(2)), while it was only 1.6% in the 30-L fermentor with air, but reached 14.2% in the case of pure O(2). We used two different experimental methods for evaluating CO(2) inhibition: CO(2) pulse injection and autogenous CO(2) methods. A 10 or 22% (v/v) CO(2) pulse with a duration of 3 or 6 h was introduced in a pure-oxygen culture of R. eutropha to investigate how CO(2) affects the synthesis of biomass and PHB. CO(2) inhibited the cell growth and PHB synthesis significantly. The inhibitory effect became stronger with the increase of the CO(2) concentration and pulse duration. The new proposed autogenous CO(2) method makes it possible to place microbial cells under different CO(2) level environments by varying the gas flow rate. Introduction of O(2) gas at a low flow rate of 0.42 vvm resulted in an increase of CO(2) concentration to 30.2% in the exit gas. The final PHB of 97.2 g/L was obtained, which corresponded to 70% of the PHB production at 1.0 vvm O(2) flow rate. This new method measures the inhibitory effect of CO(2) produced autogenously by cells through the entire fermentation process and can avoid the overestimation of CO(2) inhibition without introducing artificial CO(2) into the fermentor. Copyright 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 312-320, 2003.

  13. Modeling CO2 Storage in Fractured Reservoirs: Fracture-Matrix Interactions of Free-Phase and Dissolved CO2

    NASA Astrophysics Data System (ADS)

    Oldenburg, C. M.; Zhou, Q.; Birkholzer, J. T.

    2017-12-01

    The injection of supercritical CO2 (scCO2) in fractured reservoirs has been conducted at several storage sites. However, no site-specific dual-continuum modeling for fractured reservoirs has been reported and modeling studies have generally underestimated the fracture-matrix interactions. We developed a conceptual model for enhanced CO2 storage to take into account global scCO2 migration in the fracture continuum, local storage of scCO2 and dissolved CO2 (dsCO2) in the matrix continuum, and driving forces for scCO2 invasion and dsCO2 diffusion from fractures. High-resolution discrete fracture-matrix models were developed for a column of idealized matrix blocks bounded by vertical and horizontal fractures and for a km-scale fractured reservoir. The column-scale simulation results show that equilibrium storage efficiency strongly depends on matrix entry capillary pressure and matrix-matrix connectivity while the time scale to reach equilibrium is sensitive to fracture spacing and matrix flow properties. The reservoir-scale modeling results shows that the preferential migration of scCO2 through fractures is coupled with bulk storage in the rock matrix that in turn retards the fracture scCO2 plume. We also developed unified-form diffusive flux equations to account for dsCO2 storage in brine-filled matrix blocks and found solubility trapping is significant in fractured reservoirs with low-permeability matrix.

  14. FTIR study of CO2 and H2O/CO2 nanoparticles and their temporal evolution at 80 K.

    PubMed

    Taraschewski, M; Cammenga, H K; Tuckermann, R; Bauerecker, S

    2005-04-21

    Fourier transform infrared (FTIR) spectroscopy combined with a long-path collisional cooling cell was used to investigate the temporal evolution of CO2 nanoparticles and binary H2O/CO2 nanocomposites in the aerosol phase at 80 K. The experimental conditions for the formation of different CO2 particle shapes as slab, shell, sphere, cube, and needle have been studied by comparison with calculated data from the literature. The H2O/CO2 nanoparticles were generated with a newly developed multiple-pulse injection technique and with the simpler flow-in technique. The carbon dioxide nu3-vibration band at 2360 cm(-1) and the water ice OH-dangling band at 3700 cm(-1) were used to study the evolution of structure, shape, and contact area of the nanocomposites over 150 s. Different stages of binary nanocomposites with primary water ice cores were identified dependent on the injected CO2 portion: (a) disordered (amorphous) CO2 slabs on water particle surfaces, (b) globular crystalline CO2 humps sticking on the water cores, and (c) water cores being completely enclosed in bigger predominantly crystalline CO2 nanoparticles. However, regular CO2 shell structures on primary water particles showing both longitudinal (LO) and transverse (TO) optical mode features of the nu3-vibration band could not be observed. Experiments with reversed nucleation order indicate that H2O/CO2 composite particles with different initial structures evolve toward similar molecular nanocomposites with separated CO2 and H2O regions.

  15. Experimental investigation of geochemical and mineralogical effects of CO2 sequestration on flow characteristics of reservoir rock in deep saline aquifers

    PubMed Central

    Rathnaweera, T. D.; Ranjith, P. G.; Perera, M. S. A.

    2016-01-01

    Interactions between injected CO2, brine, and rock during CO2 sequestration in deep saline aquifers alter their natural hydro-mechanical properties, affecting the safety, and efficiency of the sequestration process. This study aims to identify such interaction-induced mineralogical changes in aquifers, and in particular their impact on the reservoir rock’s flow characteristics. Sandstone samples were first exposed for 1.5 years to a mixture of brine and super-critical CO2 (scCO2), then tested to determine their altered geochemical and mineralogical properties. Changes caused uniquely by CO2 were identified by comparison with samples exposed over a similar period to either plain brine or brine saturated with N2. The results show that long-term reaction with CO2 causes a significant pH drop in the saline pore fluid, clearly due to carbonic acid (as dissolved CO2) in the brine. Free H+ ions released into the pore fluid alter the mineralogical structure of the rock formation, through the dissolution of minerals such as calcite, siderite, barite, and quartz. Long-term CO2 injection also creates a significant CO2 drying-out effect and crystals of salt (NaCl) precipitate in the system, further changing the pore structure. Such mineralogical alterations significantly affect the saline aquifer’s permeability, with important practical consequences for the sequestration process. PMID:26785912

  16. Asymmetric biotic interactions and abiotic niche differences revealed by a dynamic joint species distribution model.

    PubMed

    Lany, Nina K; Zarnetske, Phoebe L; Schliep, Erin M; Schaeffer, Robert N; Orians, Colin M; Orwig, David A; Preisser, Evan L

    2018-05-01

    A species' distribution and abundance are determined by abiotic conditions and biotic interactions with other species in the community. Most species distribution models correlate the occurrence of a single species with environmental variables only, and leave out biotic interactions. To test the importance of biotic interactions on occurrence and abundance, we compared a multivariate spatiotemporal model of the joint abundance of two invasive insects that share a host plant, hemlock woolly adelgid (HWA; Adelges tsugae) and elongate hemlock scale (EHS; Fiorina externa), to independent models that do not account for dependence among co-occurring species. The joint model revealed that HWA responded more strongly to abiotic conditions than EHS. Additionally, HWA appeared to predispose stands to subsequent increase of EHS, but HWA abundance was not strongly dependent on EHS abundance. This study demonstrates how incorporating spatial and temporal dependence into a species distribution model can reveal the dependence of a species' abundance on other species in the community. Accounting for dependence among co-occurring species with a joint distribution model can also improve estimation of the abiotic niche for species affected by interspecific interactions. © 2018 by the Ecological Society of America.

  17. Species associations overwhelm abiotic conditions to dictate the structure and function of wood-decay fungal communities.

    PubMed

    Maynard, Daniel S; Covey, Kristofer R; Crowther, Thomas W; Sokol, Noah W; Morrison, Eric W; Frey, Serita D; van Diepen, Linda T A; Bradford, Mark A

    2018-04-01

    Environmental conditions exert strong controls on the activity of saprotrophic microbes, yet abiotic factors often fail to adequately predict wood decomposition rates across broad spatial scales. Given that species interactions can have significant positive and negative effects on wood-decay fungal activity, one possibility is that biotic processes serve as the primary controls on community function, with abiotic controls emerging only after species associations are accounted for. Here we explore this hypothesis in a factorial field warming- and nitrogen-addition experiment by examining relationships among wood decomposition rates, fungal activity, and fungal community structure. We show that functional outcomes and community structure are largely unrelated to abiotic conditions, with microsite and plot-level abiotic variables explaining at most 19% of the total variability in decomposition and fungal activity, and 2% of the variability in richness and evenness. In contrast, taxonomic richness, evenness, and species associations (i.e., co-occurrence patterns) exhibited strong relationships with community function, accounting for 52% of the variation in decomposition rates and 73% in fungal activity. A greater proportion of positive vs. negative species associations in a community was linked to strong declines in decomposition rates and richness. Evenness emerged as a key mediator between richness and function, with highly even communities exhibiting a positive richness-function relationship and uneven communities exhibiting a negative or null response. These results suggest that community-assembly processes and species interactions are important controls on the function of wood-decay fungal communities, ultimately overwhelming substantial differences in abiotic conditions. © 2018 by the Ecological Society of America.

  18. Recent and projected increases in atmospheric CO2 concentration can enhance gene flow between wild and genetically altered rice (Oryza sativa).

    PubMed

    Ziska, Lewis H; Gealy, David R; Tomecek, Martha B; Jackson, Aaron K; Black, Howard L

    2012-01-01

    Although recent and projected increases in atmospheric carbon dioxide can alter plant phenological development, these changes have not been quantified in terms of floral outcrossing rates or gene transfer. Could differential phenological development in response to rising CO(2) between genetically modified crops and wild, weedy relatives increase the spread of novel genes, potentially altering evolutionary fitness? Here we show that increasing CO(2) from an early 20(th) century concentration (300 µmol mol(-1)) to current (400 µmol mol(-1)) and projected, mid-21(st) century (600 µmol mol(-1)) values, enhanced the flow of genes from wild, weedy rice to the genetically altered, herbicide resistant, cultivated population, with outcrossing increasing from 0.22% to 0.71% from 300 to 600 µmol mol(-1). The increase in outcrossing and gene transfer was associated with differential increases in plant height, as well as greater tiller and panicle production in the wild, relative to the cultivated population. In addition, increasing CO(2) also resulted in a greater synchronicity in flowering times between the two populations. The observed changes reported here resulted in a subsequent increase in rice dedomestication and a greater number of weedy, herbicide-resistant hybrid progeny. Overall, these data suggest that differential phenological responses to rising atmospheric CO(2) could result in enhanced flow of novel genes and greater success of feral plant species in agroecosystems.

  19. Microfluidic co-flow of Newtonian and viscoelastic fluids for high-resolution separation of microparticles.

    PubMed

    Tian, Fei; Zhang, Wei; Cai, Lili; Li, Shanshan; Hu, Guoqing; Cong, Yulong; Liu, Chao; Li, Tiejun; Sun, Jiashu

    2017-09-12

    The microfluidic passive control of microparticles largely relies on the hydrodynamic effects of the carrier media such as Newtonian fluids and viscoelastic fluids. Yet the viscoelastic/Newtonian interfacial effect has been scarcely investigated, especially for high-resolution particle separation. Here we report a microfluidic co-flow of Newtonian (water or PBS) and viscoelastic fluids (PEO) for the size-dependent separation of microparticles. The co-flow condition generates a stable viscoelastic/Newtonian interface, giving rise to the wall-directed elastic lift forces that compete with the center-directed lift forces, and efficiently hinders the migration of microparticles from the Newtonian to the viscoelastic fluid in a size-dependent manner. An almost complete separation of a binary mixture of 1 μm and 2 μm polystyrene particles is achieved by the co-flow of water and a very dilute PEO solution (100 ppm), whereas the sole use of water or PEO could not lead to an efficient separation. This co-flow microfluidic system is also applied for the separation of Staphylococcus aureus (1 μm) from platelets (2-3 μm) with >90% efficiencies and purities.

  20. Annual soil CO_{2} production in Moscow Botanical Garden (Russia).

    NASA Astrophysics Data System (ADS)

    Udovenko, Maria; Goncharova, Olga; Matyshak, Georgy

    2017-04-01

    Soil respiration is an essential component of the carbon cycle, determining 25-40 % of carbon dioxide in the atmosphere. Urban soils are subject to significant anthropogenic influences. Anthropogenic impact affects both the plants and the soil microbiota. So, soil CO2 efflux and soil profile CO2 concentration probably differ in urban and natural soils. Influence of abiotic factors on soil carbon dioxide production is explored insufficiently. The research of their impact on soil carbon dioxide production is necessary to predict soil response to anthropogenic climate change. The aim of this study was estimation of annual soil CO2 production and the impact of climatic factors on it. The research took place in Moscow State University Botanical Garden Arboretum (southern taiga). Investigations were carried out at two sites: the areas planted with Picea obovata and Carpinus betulus. The study was conducted with 1-2 weeks intervals between November 2014 and December 2015. Emission measurement were carried out by closed chamber technique, profile concentration were measured by soil air sampling tubes method. Annual carbon dioxide soil surface efflux of soil planted with Picea obovata was 1370 gCO2/(m2 * year), soil planted with Carpinus betulus - 1590 gCO2/(m2 * year). Soil CO2 concentration increased with depth in average of 3300 to 12000 ppm (at 80 cm depth). Maximum concentration values are confined to the end of vegetation period (high biological activity) and to beginning of spring (spring ice cover of soil prevents CO2 emission). Soil CO2 efflux depends on soil temperature at 10 cm depth (R = 0.89; p <0.05), in a less degree it correlate with soil surface temperature and with soil temperature at 20 cm depth (r=0.88; p<0.05). Soil moisture has a little effect on CO2 efflux in the annual cycle (r=-0.16; p<0.05). However in vegetation period efflux of carbon dioxide largely depends on soil moisture, due to the fact, that soil moisture is limiting factor for soil

  1. Cerebral autoregulation and flow/metabolism coupling during cardiopulmonary bypass: the influence of PaCO/sub 2/

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

    Murkin, J.M.; Farrar, J.K.; Tweed, W.A.

    Measurement of /sup 133/Xe clearance and effluent cerebral venous blood sampling were used in 38 patients to determine the effects of cardiopulmonary bypass, and of maintaining temperature corrected or noncorrected PaCO/sub 2/ at 40 mm Hg on regulation of cerebral blood flow (CBF) and flow/metabolism coupling. After induction of anesthesia with diazepam and fentanyl, mean CBF was 25 ml X 100 g-1 X min-1 and cerebral oxygen consumption, 1.67 ml X 100 g-1 X min-1. Cerebral oxygen consumption during nonpulsatile cardiopulmonary bypass at 26 degrees C was reduced to 0.42 ml X 100 g-1 X min-1 in both groups. CBFmore » was reduced to 14-15 ml X 100 g-1 X min-1 in the non-temperature-corrected group (n = 21), was independent of cerebral perfusion pressure over the range of 20-100 mm Hg, but correlated with cerebral oxygen consumption. In the temperature-corrected group (n = 17), CBF varied from 22 to 32 ml X 100 g-1 X min-1, and flow/metabolism coupling was not maintained (i.e., CBF and cerebral oxygen consumption varied independently). However, variation in CBF correlated significantly with cerebral perfusion pressure over the pressure range of 15-95 mm Hg. This study demonstrates a profound reduction in cerebral oxygen consumption during hypothermic nonpulsatile cardiopulmonary bypass. When a non-temperature-corrected PaCO/sub 2/ of approximately 40 mm Hg was maintained, CBF was lower, and analysis of pooled data suggested that CBF regulation was better preserved, i.e., CBF was independent of pressure changes and dependent upon cerebral oxygen consumption.« less

  2. Effects of abiotic factors on ecosystem health of Taihu Lake, China based on eco-exergy theory

    NASA Astrophysics Data System (ADS)

    Wang, Ce; Bi, Jun; Fath, Brian D.

    2017-02-01

    A lake ecosystem is continuously exposed to environmental stressors with non-linear interrelationships between abiotic factors and aquatic organisms. Ecosystem health depicts the capacity of system to respond to external perturbations and still maintain structure and function. In this study, we explored the effects of abiotic factors on ecosystem health of Taihu Lake in 2013, China from a system-level perspective. Spatiotemporal heterogeneities of eco-exergy and specific eco-exergy served as thermodynamic indicators to represent ecosystem health in the lake. The results showed the plankton community appeared more energetic in May, and relatively healthy in Gonghu Bay with both higher eco-exergy and specific eco-exergy; a eutrophic state was likely discovered in Zhushan Bay with higher eco-exergy but lower specific eco-exergy. Gradient Boosting Machine (GBM) approach was used to explain the non-linear relationships between two indicators and abiotic factors. This analysis revealed water temperature, inorganic nutrients, and total suspended solids greatly contributed to the two indicators that increased. However, pH rise driven by inorganic carbon played an important role in undermining ecosystem health, particularly when pH was higher than 8.2. This implies that climate change with rising CO2 concentrations has the potential to aggravate eutrophication in Taihu Lake where high nutrient loads are maintained.

  3. Effects of abiotic factors on ecosystem health of Taihu Lake, China based on eco-exergy theory

    PubMed Central

    Wang, Ce; Bi, Jun; Fath, Brian D.

    2017-01-01

    A lake ecosystem is continuously exposed to environmental stressors with non-linear interrelationships between abiotic factors and aquatic organisms. Ecosystem health depicts the capacity of system to respond to external perturbations and still maintain structure and function. In this study, we explored the effects of abiotic factors on ecosystem health of Taihu Lake in 2013, China from a system-level perspective. Spatiotemporal heterogeneities of eco-exergy and specific eco-exergy served as thermodynamic indicators to represent ecosystem health in the lake. The results showed the plankton community appeared more energetic in May, and relatively healthy in Gonghu Bay with both higher eco-exergy and specific eco-exergy; a eutrophic state was likely discovered in Zhushan Bay with higher eco-exergy but lower specific eco-exergy. Gradient Boosting Machine (GBM) approach was used to explain the non-linear relationships between two indicators and abiotic factors. This analysis revealed water temperature, inorganic nutrients, and total suspended solids greatly contributed to the two indicators that increased. However, pH rise driven by inorganic carbon played an important role in undermining ecosystem health, particularly when pH was higher than 8.2. This implies that climate change with rising CO2 concentrations has the potential to aggravate eutrophication in Taihu Lake where high nutrient loads are maintained. PMID:28220835

  4. Precursory signals of the 2014-15 Fogo eruption (Cape Verde) detected by surface CO2 emission and heat flow observations

    NASA Astrophysics Data System (ADS)

    Pérez, Nemesio M.; Dionis, Samara; Fernandes, Paulo; Barrancos, José; Rodríguez, Fátima; Bandomo, Zuleyka; Hernández, Pedro A.; Melián, Gladys V.; Silva, Sónia; Padilla, Germán; Padrón, Eleazar; Cabral, Jeremias; Calvo, David; Asensio-Ramos, María; Pereira, José Manuel; Gonçalves, António A.; Barros, Inocencio; Semedo, Helio

    2015-04-01

    2010, the diffuse CO2 emission rate was 219 ± 36 t d-1 (Dionis et al., 2015). The second anomalous period started on March 2014, eight months before the 2014-15 Fogo eruption onset, and reached a relatively high value of 337 ± 119 t d-1 on August 30, 2014. It was likely caused by rising of magmatic gases from a second magma intrusion which ended on an eruption. Heat flow temporal evolution during the observation period also shows a quasi-continuous increase before the eruption onset, with the maximum observed heat flow (16.4 ± 3.4 MW) on March 2014. These geochemical and geophysical evidences are clearly precursory signals of the 2014-15 Fogo eruption. Dawson, G.B. (1964), N Z J Geol Geophys 7:155-171; Dionis S. et al. (2015), Bull. Volcanol., in press

  5. Controls of Evapotranspiration and CO2 Fluxes from Scots Pine by Surface Conductance and Abiotic Factors

    PubMed Central

    Zha, Tianshan; Li, Chunyi; Kellomäki, Seppo; Peltola, Heli; Wang, Kai-Yun; Zhang, Yuqing

    2013-01-01

    Evapotranspiration (E) and CO2 flux (Fc) in the growing season of an unusual dry year were measured continuously over a Scots pine forest in eastern Finland, by eddy covariance techniques. The aims were to gain an understanding of their biological and environmental control processes. As a result, there were obvious diurnal and seasonal changes in E, Fc, surface conductance (gc), and decoupling coefficient (Ω), showing similar trends to those in radiation (PAR) and vapour pressure deficit (δ). The maximum mean daily values (24-h average) for E, Fc, gc, and Ω were 1.78 mmol m−2 s−1, −11.18 µmol m−2 s−1, 6.27 mm s−1, and 0.31, respectively, with seasonal averages of 0.71 mmol m−2 s−1, −4.61 µmol m−2 s−1, 3.3 mm s−1, and 0.16. E and Fc were controlled by combined biological and environmental variables. There was curvilinear dependence of E on gc and Fc on gc. Among the environmental variables, PAR was the most important factor having a positive linear relationship to E and curvilinear relationship to Fc, while vapour pressure deficit was the most important environmental factor affecting gc. Water use efficiency was slightly higher in the dry season, with mean monthly values ranging from 6.67 to 7.48 μmol CO2 (mmol H2O)−1 and a seasonal average of 7.06 μmol CO2 (μmol H2O)−1. Low Ω and its close positive relationship with gc indicate that evapotranspiration was sensitive to surface conductance. Mid summer drought reduced surface conductance and decoupling coefficient, suggesting a more biotic control of evapotranspiration and a physiological acclimation to dry air. Surface conductance remained low and constant under dry condition, supporting that a constant value of surface constant can be used for modelling transpiration under drought condition. PMID:23894401

  6. Controls of evapotranspiration and CO2 fluxes from scots pine by surface conductance and abiotic factors.

    PubMed

    Zha, Tianshan; Li, Chunyi; Kellomäki, Seppo; Peltola, Heli; Wang, Kai-Yun; Zhang, Yuqing

    2013-01-01

    Evapotranspiration (E) and CO2 flux (Fc ) in the growing season of an unusual dry year were measured continuously over a Scots pine forest in eastern Finland, by eddy covariance techniques. The aims were to gain an understanding of their biological and environmental control processes. As a result, there were obvious diurnal and seasonal changes in E, Fc , surface conductance (gc ), and decoupling coefficient (Ω), showing similar trends to those in radiation (PAR) and vapour pressure deficit (δ). The maximum mean daily values (24-h average) for E, Fc , gc , and Ω were 1.78 mmol m(-2) s(-1), -11.18 µmol m(-2) s(-1), 6.27 mm s(-1), and 0.31, respectively, with seasonal averages of 0.71 mmol m(-2) s(-1), -4.61 µmol m(-2) s(-1), 3.3 mm s(-1), and 0.16. E and Fc were controlled by combined biological and environmental variables. There was curvilinear dependence of E on gc and Fc on gc . Among the environmental variables, PAR was the most important factor having a positive linear relationship to E and curvilinear relationship to Fc , while vapour pressure deficit was the most important environmental factor affecting gc . Water use efficiency was slightly higher in the dry season, with mean monthly values ranging from 6.67 to 7.48 μmol CO2 (mmol H2O)(-1) and a seasonal average of 7.06 μmol CO2 (μmol H2O)(-1). Low Ω and its close positive relationship with gc indicate that evapotranspiration was sensitive to surface conductance. Mid summer drought reduced surface conductance and decoupling coefficient, suggesting a more biotic control of evapotranspiration and a physiological acclimation to dry air. Surface conductance remained low and constant under dry condition, supporting that a constant value of surface constant can be used for modelling transpiration under drought condition.

  7. The shifting influence of abiotic drivers during landslide succession in Puerto Rico

    Treesearch

    L. R. Walker; A. B. Shiels; P. J. Bellingham; A. D. Sparrow; N. Fetcher; F. H. Landau; D. J. Lodge

    2013-01-01

    Summary 1. Abiotic variables are critical drivers of succession in most primary seres, but how their influence on biota changes over time is rarely examined. Landslides provide good model systems for examining abiotic influences because they are spatially and temporally heterogeneous habitats with distinct abiotic and biotic gradients and post-landslide erosion. 2. In...

  8. Space Suit CO2 Washout During Intravehicular Activity

    NASA Technical Reports Server (NTRS)

    Augustine, Phillip M.; Navarro, Moses; Conger, Bruce; Sargusingh, Miriam M.

    2010-01-01

    Space suit carbon dioxide (CO2) washout refers to the removal of CO2 gas from the oral-nasal area of a suited astronaut's (or crewmember's) helmet using the suit's ventilation system. Inadequate washout of gases can result in diminished mental/cognitive abilities as well as headaches and light headedness. In addition to general discomfort, these ailments can impair an astronaut s ability to perform mission-critical tasks ranging from flying the space vehicle to performing lunar extravehicular activities (EVAs). During design development for NASA s Constellation Program (CxP), conflicting requirements arose between the volume of air flow that the new Orion manned space vehicle is allocated to provide to the suited crewmember and the amount of air required to achieve CO2 washout in a space suit. Historically, space suits receive 6.0 actual cubic feet per minute (acfm) of air flow, which has adequately washed out CO2 for EVAs. For CxP, the Orion vehicle will provide 4.5 acfm of air flow to the suit. A group of subject matter experts (SM Es) among the EVA Systems community came to an early consensus that 4.5 acfm may be acceptable for low metabolic rate activities. However, this value appears very risky for high metabolic rates, hence the need for further analysis and testing. An analysis was performed to validate the 4.5 acfm value and to determine if adequate CO2 washout can be achieved with the new suit helmet design concepts. The analysis included computational fluid dynamic (CFD) modeling cases, which modeled the air flow and breathing characteristics of a human wearing suit helmets. Helmet testing was performed at the National Institute of Occupational Safety and Health (NIOSH) in Pittsburgh, Pennsylvania, to provide a gross-level validation of the CFD models. Although there was not a direct data correlation between the helmet testing and the CFD modeling, the testing data showed trends that are very similar to the CFD modeling. Overall, the analysis yielded

  9. High Fidelity Computational Analysis of CO2 Trapping at Pore Scales

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

    Kumar, Vinod

    2013-07-13

    With an alarming rise in carbon dioxide (CO2) emission from anthropogenic sources, CO2 sequestration has become an attractive choice to mitigate the emission. Some popular storage media for CO{sub 2} are oil reservoirs, deep coal-bed, and deep oceanic-beds. These have been used for the long term CO{sub 2} storage. Due to special lowering viscosity and surface tension property of CO{sub 2}, it has been widely used for enhanced oil recovery. The sites for CO{sub 2} sequestration or enhanced oil recovery mostly consist of porous rocks. Lack of knowledge of molecular mobility under confinement and molecule-surface interactions between CO2 and naturalmore » porous media results in generally governed by unpredictable absorption kinetics and total absorption capacity for injected fluids, and therefore, constitutes barriers to the deployment of this technology. Therefore, it is important to understand the flow dynamics of CO{sub 2} through the porous microstructures at the finest scale (pore-scale) to accurately predict the storage potential and long-term dynamics of the sequestered CO{sub 2}. This report discusses about pore-network flow modeling approach using variational method and analyzes simulated results this method simulations at pore-scales for idealized network and using Berea Sandstone CT scanned images. Variational method provides a promising way to study the kinetic behavior and storage potential at the pore scale in the presence of other phases. The current study validates variational solutions for single and two-phase Newtonian and single phase non-Newtonian flow through angular pores for special geometries whose analytical and/or empirical solutions are known. The hydraulic conductance for single phase flow through a triangular duct was also validated against empirical results derived from lubricant theory.« less

  10. Dual stable isotopes of CH 4 from Yellowstone hot-springs suggest hydrothermal processes involving magmatic CO 2

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

    Moran, James J.; Whitmore, Laura M.; Jay, Zackary J.

    Volcanism and post-magmatism contribute both significant annual CH 4 fluxes to the atmosphere (on par with other natural sources such as forest fire and wild animal emissions) and have been implicated in past climate-change events. The Yellowstone hot spot is one of the largest volcanic systems on Earth and is known to emit methane in addition to other greenhouse gases (e.g. carbon dioxide) but the ultimate source of this methane flux has not been elucidated. Here we use dual stable isotope analysis (δ 2H and δ 13C) of CH 4(g) sampled from ten high-temperature geothermal pools in Yellowstone National Parkmore » to show that the predominant flux of CH4(g) is abiotic. The average δ 13C and δ 2H values of CH 4(g) emitted from hot springs (-26.7 (±2.4) and -236.9 (±12.0) ‰, respectively) are not consistent with biotic (microbial or thermogenic) methane sources, but are within previously reported ranges for abiotic methane production. Correlation between δ 13C CH4 and δ 13C-dissolved inorganic C (DIC) also suggests that CO 2 is a parent C source for the observed CH 4(g). Moreover, CH 4-CO 2 isotopic geothermometry was used to estimate CH 4(g) formation temperatures ranging from ~ 250 - 350°C, which is just below the temperature estimated for the hydrothermal reservoir and consistent with the hypothesis that subsurface, rock-water interactions are responsible for large methane fluxes from this volcanic system. An understanding of conditions leading to the abiotic production of methane and associated isotopic signatures are central to understanding the evolutionary history of deep carbon sources on Earth.« less

  11. Stereotactic CO2 laser therapy for hydrocephalus

    NASA Astrophysics Data System (ADS)

    Kozodoy-Pins, Rebecca L.; Harrington, James A.; Zazanis, George A.; Nosko, Michael G.; Lehman, Richard M.

    1994-05-01

    A new fiber-optic delivery system for CO2 radiation has been used to successfully treat non-communicating hydrocephalus. This system consists of a hollow sapphire waveguide employed in the lumen of a stereotactically-guided neuroendoscope. CO2 gas flows through the bore of the hollow waveguide, creating a path for the laser beam through the cerebrospinal fluid (CSF). This delivery system has the advantages of both visualization and guided CO2 laser radiation without the same 4.3 mm diameter scope. Several patients with hydrocephalus were treated with this new system. The laser was used to create a passage in the floor of the ventricle to allow the flow of CSF from the ventricles to the sub-arachnoid space. Initial postoperative results demonstrated a relief of the clinical symptoms. Long-term results will indicate if this type of therapy will be superior to the use of implanted silicone shunts. Since CO2 laser radiation at 10.6 micrometers is strongly absorbed by the water in tissue and CSF, damage to tissue surrounding the lesion with each laser pulse is limited. The accuracy and safety of this technique may prove it to be an advantageous therapy for obstructive hydrocephalus.

  12. Industrial 30-kW CO2 laser with fast axial gas flow and rf excitation

    NASA Astrophysics Data System (ADS)

    Habich, Uwe; Loosen, Peter; Hertzler, Christoph; Wollermann-Windgasse, Reinhard

    1996-03-01

    A CO2 laser with fast axial gas flow was set up and operated with a maximum cw output power above 30 kW. The laser makes use of 8 rf-excited discharges which were optimized regarding to the gas-flow, to the discharge homogeneity and to the optical properties of the gain medium. Results of experimental investigation of these topics are described as well as performance characteristics of the laser system equipped with a stable and an unstable resonator, respectively. With an unstable resonator and an aerodynamic window for the extraction of the beam the laser system gives a beam quality which is close to the diffraction limit for this type of resonator. Disregarding the difficulties which are related to the definition and measurement of beam quality for unstable resonators, the beam quality could be described as M2 equals 3. Measured far field intensity profiles in the focal plane of a focusing optics are presented as well as the beam propagation behavior near focus. First results of applications in materials processing are discussed.

  13. Increasing atmospheric CO2 reduces metabolic and physiological differences between isoprene- and non-isoprene-emitting poplars.

    PubMed

    Way, Danielle A; Ghirardo, Andrea; Kanawati, Basem; Esperschütz, Jürgen; Monson, Russell K; Jackson, Robert B; Schmitt-Kopplin, Philippe; Schnitzler, Jörg-Peter

    2013-10-01

    Isoprene, a volatile organic compound produced by some plant species, enhances abiotic stress tolerance under current atmospheric CO2 concentrations, but its biosynthesis is negatively correlated with CO2 concentrations. We hypothesized that losing the capacity to produce isoprene would require stronger up-regulation of other stress tolerance mechanisms at low CO2 than at higher CO2 concentrations. We compared metabolite profiles and physiological performance in poplars (Populus × canescens) with either wild-type or RNAi-suppressed isoprene emission capacity grown at pre-industrial low, current atmospheric, and future high CO2 concentrations (190, 390 and 590 ppm CO2 , respectively). Suppression of isoprene biosynthesis led to significant rearrangement of the leaf metabolome, increasing stress tolerance responses such as xanthophyll cycle pigment de-epoxidation and antioxidant levels, as well as altering lipid, carbon and nitrogen metabolism. Metabolic and physiological differences between isoprene-emitting and suppressed lines diminished as growth CO2 concentrations rose. The CO2 dependence of our results indicates that the effects of isoprene biosynthesis are strongest at pre-industrial CO2 concentrations. Rising CO2 may reduce the beneficial effects of biogenic isoprene emission, with implications for species competition. This has potential consequences for future climate warming, as isoprene emitted from vegetation has strong effects on global atmospheric chemistry. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  14. Biotic and abiotic degradation of 1,1,2,2-tetrachloroethane in wetland sediments: Geochemical and microbial community analyses

    USGS Publications Warehouse

    Lorah, M.M.; Voytek, M.A.; Kirshtein, J.

    2000-01-01

    Additional microcosm experiments with the wetland sediment and groundwater at the Aberdeen Proving Ground, MD, site was presented to assist in elucidating the conditions under which these potentially competing biotic and abiotic degradation reactions for 1,1,2,2-tetrachloroethane (PCA) occur in the environment and to evaluate potential seasonal changes in degradation reactions. PCA concentration decreased to below detection within 21 days in the March 1999 experiment, while PCA was still present at day 35 in the July 1999 experiment. Compared to March 1999 experiment, peak concentrations of all daughter products except trichloroethylene (TCE) were delayed in the July 1999 experiment. The relative intensity of the peaks was directly related to the biomass present for each fragment length (bp, base pair). The relative intensities were lower in sediment collected in August 1999 than in March 1999, especially in the bp size range of ??? 160??-240??. These microbial community analyses, along with the geochemical analyses of the microcosms, provide evidence that abiotic production of TCE from PCA degradation is more significant under conditions of low bacterial biomass in the wetland sediments.

  15. An experimental study of basaltic glass-H2O-CO2 interaction at 22 and 50 °C: Implications for subsurface storage of CO2

    NASA Astrophysics Data System (ADS)

    Galeczka, Iwona; Wolff-Boenisch, Domenik; Oelkers, Eric H.; Gislason, Sigurdur R.

    2014-02-01

    A novel high pressure column flow reactor was used to investigate the evolution of solute chemistry along a 2.3 m flow path during pure water- and CO2-charged water-basaltic glass interaction experiments at 22 and 50 °C and 10-5.7 to 22 bars partial pressure of CO2. Experimental results and geochemical modelling showed the pH of injected pure water evolved rapidly from 6.7 to 9-9.5 and most of the iron released to the fluid phase was subsequently consumed by secondary minerals, similar to natural meteoric water-basalt systems. In contrast to natural systems, however, the aqueous aluminium concentration remained relatively high along the entire flow path. The aqueous fluid was undersaturated with respect to basaltic glass and carbonate minerals, but supersaturated with respect to zeolites, clays, and Fe hydroxides. As CO2-charged water replaced the alkaline fluid within the column, the fluid briefly became supersaturated with respect to siderite. Basaltic glass dissolution in the column reactor, however, was insufficient to overcome the pH buffer capacity of CO2-charged water. The pH of this CO2-charged water rose from an initial 3.4 to only 4.5 in the column reactor. This acidic reactive fluid was undersaturated with respect to carbonate minerals but supersaturated with respect to clays and Fe hydroxides at 22 °C, and with respect to clays and Al hydroxides at 50 °C. Basaltic glass dissolution in the CO2-charged water was closer to stoichiometry than in pure water. The mobility and aqueous concentration of several metals increased significantly with the addition of CO2 to the inlet fluid, and some metals, including Mn, Cr, Al, and As exceeded the allowable drinking water limits. Iron became mobile and the aqueous Fe2+/Fe3+ ratio increased along the flow path. Although carbonate minerals did not precipitate in the column reactor in response to CO2-charged water-basaltic glass interaction, once this fluid exited the reactor, carbonates precipitated as the fluid

  16. CO Oxidation and Subsequent CO 2 Chemisorption on Alkaline Zirconates: Li 2 ZrO 3 and Na 2 ZrO 3

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

    Alcántar-Vázquez, Brenda; Duan, Yuhua; Pfeiffer, Heriberto

    Here, two different alkaline zirconates (Li 2ZrO 3 and Na 2ZrO 3) were studied as possible bifunctional catalytic-captor materials for CO oxidation and the subsequent CO 2 chemisorption process. Initially, CO oxidation reactions were analyzed in a catalytic reactor coupled to a gas chromatograph, using Li 2ZrO 3 and Na 2ZrO 3, under different O 2 partial flows. We found results clearly showed that Na 2ZrO 3 possesses much better catalytic properties than Li 2ZrO 3. After the CO-O 2 oxidation catalytic analysis, CO2 chemisorption process was analyzed by thermogravimetric analysis, only for the Na 2ZrO 3 ceramic. The resultsmore » confirmed that Na 2ZrO 3 is able to work as a bifunctional material (CO oxidation and subsequent CO 2 chemisorption), although the kinetic CO 2 capture process was not the best one under the physicochemical condition used in this case. For Na 2ZrO 3, the best CO conversions were found between 445 and 580 °C (100%), while Li 2ZrO 3 only showed a 35% of efficiency between 460 and 503 °C. However, in the Na 2ZrO 3 case, at temperatures higher than 580 °C its catalytic activity gradually decreases as a result of CO 2 capture process. Finally, all these experiments were compared and supported with theoretical thermodynamic data.« less

  17. CO Oxidation and Subsequent CO 2 Chemisorption on Alkaline Zirconates: Li 2 ZrO 3 and Na 2 ZrO 3

    DOE PAGES

    Alcántar-Vázquez, Brenda; Duan, Yuhua; Pfeiffer, Heriberto

    2016-08-26

    Here, two different alkaline zirconates (Li 2ZrO 3 and Na 2ZrO 3) were studied as possible bifunctional catalytic-captor materials for CO oxidation and the subsequent CO 2 chemisorption process. Initially, CO oxidation reactions were analyzed in a catalytic reactor coupled to a gas chromatograph, using Li 2ZrO 3 and Na 2ZrO 3, under different O 2 partial flows. We found results clearly showed that Na 2ZrO 3 possesses much better catalytic properties than Li 2ZrO 3. After the CO-O 2 oxidation catalytic analysis, CO2 chemisorption process was analyzed by thermogravimetric analysis, only for the Na 2ZrO 3 ceramic. The resultsmore » confirmed that Na 2ZrO 3 is able to work as a bifunctional material (CO oxidation and subsequent CO 2 chemisorption), although the kinetic CO 2 capture process was not the best one under the physicochemical condition used in this case. For Na 2ZrO 3, the best CO conversions were found between 445 and 580 °C (100%), while Li 2ZrO 3 only showed a 35% of efficiency between 460 and 503 °C. However, in the Na 2ZrO 3 case, at temperatures higher than 580 °C its catalytic activity gradually decreases as a result of CO 2 capture process. Finally, all these experiments were compared and supported with theoretical thermodynamic data.« less

  18. Discharge stabilization studies of CO laser gas mixtures in quasi-steady supersonic flow

    NASA Technical Reports Server (NTRS)

    Srinivasan, G.; Smith, J. A.

    1976-01-01

    Experiments were conducted to study the applicability of a double discharge stabilization scheme in conditions appropriate for high energy CO lasers in supersonic flows. A Ludwieg tube impulse flow facility and a ballasted capacitor bank provided essentially steady flow and discharge conditions (d.c.) for times longer than ten electrode length-flow transit times. Steady, arc-free, volume discharges were produced in a Mach 3 test cavity using an auxiliary discharge to stabilize the main discharge in N2 and He/CO mixture. A signigicant result is the lack of observed plasma E/N changes in response to auxiliary discharge current changes. Also, where glow discharges were obtained, the energy loading achieved was very much less than the threshold level required for laser operation.

  19. Pore-scale simulation of CO2-water-rock interactions

    NASA Astrophysics Data System (ADS)

    Deng, H.; Molins, S.; Steefel, C. I.; DePaolo, D. J.

    2017-12-01

    In Geologic Carbon Storage (GCS) systems, the migration of scCO2 versus CO2-acidifed brine ultimately determines the extent of mineral trapping and caprock integrity, i.e. the long-term storage efficiency and security. While continuum scale multiphase reactive transport models are valuable for large scale investigations, they typically (over-)simplify pore-scale dynamics and cannot capture local heterogeneities that may be important. Therefore, pore-scale models are needed in order to provide mechanistic understanding of how fine scale structural variations and heterogeneous processes influence the transport and geochemistry in the context of multiphase flow, and to inform parameterization of continuum scale modeling. In this study, we investigate the interplay of different processes at pore scale (e.g. diffusion, reactions, and multiphase flow) through the coupling of a well-developed multiphase flow simulator with a sophisticated reactive transport code. The objectives are to understand where brine displaced by scCO2 will reside in a rough pore/fracture, and how the CO2-water-rock interactions may affect the redistribution of different phases. In addition, the coupled code will provide a platform for model testing in pore-scale multiphase reactive transport problems.

  20. Coupled Abiotic-Biotic Degradation of Bisphenol A

    NASA Astrophysics Data System (ADS)

    Im, J.; Prevatte, C.; Campagna, S. R.; Loeffler, F.

    2014-12-01

    Bisphenol A (BPA) is a ubiquitous environmental contaminant with weak estrogenic activity. BPA is readily biodegradable with oxygen available, but is recalcitrant to microbial degradation under anoxic conditions. However, BPA is susceptible to abiotic transformation under anoxic conditions. To better understand the fate of BPA in anoxic environments, the kinetics of BPA transformation by manganese oxide (d-MnO2) were investigated. BPA was rapidly transformed by MnO2 with a pseudo-first-order rate constant of 0.413 min-1. NMR and LC-MS analyses identified 4-hydroxycumyl alcohol (HCA) as a major intermediate. Up to 64% of the initial amount of BPA was recovered as HCA within 5 min, but the conversion efficiency decreased with time, suggesting that HCA was further degraded by MnO2. Further experiments confirmed that HCA was also susceptible to transformation by MnO2, albeit at 5-fold lower rates than BPA transformation. Mass balance approaches suggested that HCA was the major BPA transformation intermediate, but other compounds may also be formed. The abiotic transformation of BPA by MnO2 was affected by pH, and 10-fold higher transformation rates were observed at pH 4.5 than at pH 10. Compared to BPA, HCA has a lower octanol-water partitioning coefficient (Log Kow) of 0.76 vs 2.76 for BPA and a higher aqueous solubility of 2.65 g L-1 vs 0.31 g L-1 for BPA, suggesting higher mobility of HCA in the environment. Microcosms established with freshwater sediment materials collected from four geographically distinct locations and amended with HCA demonstrated rapid HCA biodegradation under oxic, but not under anoxic conditions. These findings suggest that BPA is not inert under anoxic conditions and abiotic reactions with MnO2 generate HCA, which has increased mobility and is susceptible to aerobic degradation. Therefore, coupled abiotic-biotic processes can affect the fate and longevity of BPA in terrestrial environments.

  1. An experimental study of basaltic glass-H2O-CO2 interaction at 22 and 50 ° C: Implications for subsurface storage of CO2

    NASA Astrophysics Data System (ADS)

    Galeczka, Iwona; Wolff-Boenisch, Domenik; Oelkers, Eric H.; Gislason, Sigurdur R.

    2014-05-01

    A novel high pressure column flow reactor (HPCFR) was used to investigate the evolution of fluid chemistry along a 2.3 meter flow path during 37-104 days of pure water- and CO2-charged water- (0.3 M CO2(aq)) basaltic glass interaction experiments at 22 and 50 ° C. The scale of the HPCFR, the ability to sample a reactive fluid at discrete spatial intervals under pressure and the possibility to measure the dissolved inorganic carbon and pH in situ all render the HPCFR unique in comparison with other reactors constructed for studies of CO2-charged water-rock interaction. During the pure water-basaltic glass interaction experiment, the pH of the injected water evolved rapidly from 6.7 to 9-9.5 and most of the dissolved iron was consumed by secondary mineral formation, similar to natural basaltic groundwater systems. In contrast to natural systems, however, the dissolved aluminium concentration remained relatively high along the entire flow path. The reactive fluid was undersaturated with respect to basaltic glass and carbonate minerals, but supersaturated with respect to zeolites, clays, and Fe hydroxides. Basaltic glass dissolution in the CO2-charged water was closer to stoichiometry than in pure water. The mobility of metals increased significantly in the reactive fluid and the concentration of some metals, including Mn, Fe, Cr, Al, and As exceeded the WHO (World Health Organisation) allowable drinking water limits. Iron was mobile and the aqueous Fe2+/Fe3+ ratio increased along the flow path. Basaltic glass dissolution in the CO2-charged water did not overcome the pH buffer capacity of the fluid. The pH rose only from an initial pH of 3.4 to 4.5 along the first 18.5 cm of the column, then remained constant during the remaining 2.1 meters of the flow path. Increasing the temperature of the CO2-charged fluid from 22 to 50 ° C increased the relative amount of dissolved divalent iron along the flow path. After a significant initial increase along the first metre of

  2. Shock shapes on blunt bodies in hypersonic-hypervelocity helium, air, and CO2 flows, and calibration results in Langley 6-inch expansion tube

    NASA Technical Reports Server (NTRS)

    Miller, C. G., III

    1975-01-01

    Shock shape results for flat-faced cylinders, spheres, and spherically blunted cones in various test gases, along with preliminary results from a calibration study performed in the Langley 6-inch expansion tube are presented. Free-stream velocities from 5 to 7 km/sec are generated at hypersonic conditions with helium, air, and CO2, resulting in normal shock density ratios from 4 to 19. Ideal-gas shock shape predictions, in which an effective ratio of specific heats is used as input, are compared with the measured results. The effect of model diameter is examined to provide insight to the thermochemical state of the flow in the shock layer. The regime for which equilibrium exists in the shock layer for the present air and CO2 test conditions is defined. Test core flow quality, test repeatability, and comparison of measured and predicted expansion-tube flow quantities are discussed.

  3. Nitrogen-based catalysts for the electrochemical reduction of CO2 to CO.

    PubMed

    Tornow, Claire E; Thorson, Michael R; Ma, Sichao; Gewirth, Andrew A; Kenis, Paul J A

    2012-12-05

    The synthesis and application of carbon-supported, nitrogen-based organometallic silver catalysts for the reduction of CO(2) is studied using an electrochemical flow reactor. Their performance toward the selective formation of CO is similar to the performance achieved when using Ag as the catalyst, but comparatively at much lower silver loading. Faradaic efficiencies of the organometallic catalyst are higher than 90%, which are comparable to those of Ag. Furthermore, with the addition of an amine ligand to Ag/C, the partial current density for CO increases significantly, suggesting a possible co-catalyst mechanism. Additional improvements in activity and selectivity may be achieved as greater insight is obtained on the mechanism of CO(2) reduction and on how these complexes assemble on the carbon support.

  4. 40 CFR 75.13 - Specific provisions for monitoring CO2 emissions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 16 2010-07-01 2010-07-01 false Specific provisions for monitoring CO2... monitoring CO2 emissions. (a) CO 2 continuous emission monitoring system. If the owner or operator chooses to... operating requirements in § 75.10 for a CO2 continuous emission monitoring system and flow monitoring system...

  5. 40 CFR 75.13 - Specific provisions for monitoring CO2 emissions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 16 2011-07-01 2011-07-01 false Specific provisions for monitoring CO2... monitoring CO2 emissions. (a) CO 2 continuous emission monitoring system. If the owner or operator chooses to... operating requirements in § 75.10 for a CO2 continuous emission monitoring system and flow monitoring system...

  6. 40 CFR 75.13 - Specific provisions for monitoring CO2 emissions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 17 2012-07-01 2012-07-01 false Specific provisions for monitoring CO2... monitoring CO2 emissions. (a) CO 2 continuous emission monitoring system. If the owner or operator chooses to... operating requirements in § 75.10 for a CO2 continuous emission monitoring system and flow monitoring system...

  7. Interannual variability of Net Ecosystem CO2 Exchange and its component fluxes in a subalpine Mediterranean ecosystem (SE Spain)

    NASA Astrophysics Data System (ADS)

    Chamizo, Sonia; Serrano-Ortiz, Penélope; Sánchez-Cañete, Enrique P.; Domingo, Francisco; Arnau-Rosalén, Eva; Oyonarte, Cecilio; Pérez-Priego, Óscar; López-Ballesteros, Ana; Kowalski, Andrew S.

    2015-04-01

    Recent decades under climate change have seen increasing interest in quantifying the carbon (C) balance of different terrestrial ecosystems, and their behavior as sources or sinks of C. Both CO2 exchange between terrestrial ecosystems and the atmosphere and identification of its drivers are key to understanding land-surface feedbacks to climate change. The eddy covariance (EC) technique allows measurements of net ecosystem C exchange (NEE) from short to long time scales. In addition, flux partitioning models can extract the components of net CO2 fluxes, including both biological processes of photosynthesis or gross primary production (GPP) and respiration (Reco), and also abiotic drivers like subsoil CO2 ventilation (VE), which is of particular relevance in semiarid environments. The importance of abiotic processes together with the strong interannual variability of precipitation, which strongly affects CO2 fluxes, complicates the accurate characterization of the C balance in semiarid landscapes. In this study, we examine 10 years of interannual variability of NEE and its components at a subalpine karstic plateau, El Llano de los Juanes, in the Sierra de Gádor (Almería, SE Spain). Results show annual NEE ranging from 55 g C m-2 (net emission) to -54 g C m-2 (net uptake). Among C flux components, GPP was the greatest contributing 42-57% of summed component magnitudes, while contributions by Reco and VE ranged from 27 to 46% and from 3 to 18%, respectively. Annual precipitation during the studied period exhibited high interannual variability, ranging from 210 mm to 1374 mm. Annual precipitation explained 50% of the variance in Reco, 59% of that in GPP, and 56% for VE. While Reco and GPP were positively correlated with annual precipitation (correlation coefficient, R, of 0.71 and 0.77, respectively), VE showed negative correlation with this driver (R = -0.74). During the driest year (2004-2005), annual GPP and Reco reached their lowest values, while contribution of

  8. Individual Cell Based Traits Obtained by Scanning Flow-Cytometry Show Selection by Biotic and Abiotic Environmental Factors during a Phytoplankton Spring Bloom

    PubMed Central

    Pomati, Francesco; Kraft, Nathan J. B.; Posch, Thomas; Eugster, Bettina; Jokela, Jukka; Ibelings, Bas W.

    2013-01-01

    In ecology and evolution, the primary challenge in understanding the processes that shape biodiversity is to assess the relationship between the phenotypic traits of organisms and the environment. Here we tested for selection on physio-morphological traits measured by scanning flow-cytometry at the individual level in phytoplankton communities under a temporally changing biotic and abiotic environment. Our aim was to study how high-frequency temporal changes in the environment influence biodiversity dynamics in a natural community. We focused on a spring bloom in Lake Zurich (Switzerland), characterized by rapid changes in phytoplankton, water conditions, nutrients and grazing (mainly mediated by herbivore ciliates). We described bloom dynamics in terms of taxonomic and trait-based diversity and found that diversity dynamics of trait-based groups were more pronounced than those of identified phytoplankton taxa. We characterized the linkage between measured phytoplankton traits, abiotic environmental factors and abundance of the main grazers and observed weak but significant correlations between changing abiotic and biotic conditions and measured size-related and fluorescence-related traits. We tested for deviations in observed community-wide distributions of focal traits from random patterns and found evidence for both clustering and even spacing of traits, occurring sporadically over the time series. Patterns were consistent with environmental filtering and phenotypic divergence under herbivore pressure, respectively. Size-related traits showed significant even spacing during the peak of herbivore abundance, suggesting that morphology-related traits were under selection from grazing. Pigment distribution within cells and colonies appeared instead to be associated with acclimation to temperature and water chemistry. We found support for trade-offs among grazing resistance and environmental tolerance traits, as well as for substantial periods of dynamics in which

  9. Individual cell based traits obtained by scanning flow-cytometry show selection by biotic and abiotic environmental factors during a phytoplankton spring bloom.

    PubMed

    Pomati, Francesco; Kraft, Nathan J B; Posch, Thomas; Eugster, Bettina; Jokela, Jukka; Ibelings, Bas W

    2013-01-01

    In ecology and evolution, the primary challenge in understanding the processes that shape biodiversity is to assess the relationship between the phenotypic traits of organisms and the environment. Here we tested for selection on physio-morphological traits measured by scanning flow-cytometry at the individual level in phytoplankton communities under a temporally changing biotic and abiotic environment. Our aim was to study how high-frequency temporal changes in the environment influence biodiversity dynamics in a natural community. We focused on a spring bloom in Lake Zurich (Switzerland), characterized by rapid changes in phytoplankton, water conditions, nutrients and grazing (mainly mediated by herbivore ciliates). We described bloom dynamics in terms of taxonomic and trait-based diversity and found that diversity dynamics of trait-based groups were more pronounced than those of identified phytoplankton taxa. We characterized the linkage between measured phytoplankton traits, abiotic environmental factors and abundance of the main grazers and observed weak but significant correlations between changing abiotic and biotic conditions and measured size-related and fluorescence-related traits. We tested for deviations in observed community-wide distributions of focal traits from random patterns and found evidence for both clustering and even spacing of traits, occurring sporadically over the time series. Patterns were consistent with environmental filtering and phenotypic divergence under herbivore pressure, respectively. Size-related traits showed significant even spacing during the peak of herbivore abundance, suggesting that morphology-related traits were under selection from grazing. Pigment distribution within cells and colonies appeared instead to be associated with acclimation to temperature and water chemistry. We found support for trade-offs among grazing resistance and environmental tolerance traits, as well as for substantial periods of dynamics in which

  10. Study on the Fluid Flow Characteristics of Coherent Jets with CO2 and O2 Mixed Injection in Electric Arc Furnace Steelmaking Processes

    NASA Astrophysics Data System (ADS)

    Wei, Guangsheng; Zhu, Rong; Wu, Xuetao; Yang, Lingzhi; Dong, Kai; Cheng, Ting; Tang, Tianping

    2018-06-01

    As an efficient oxygen supplying technology, coherent jets are widely applied in electric arc furnace (EAF) steelmaking processes to strengthen chemical energy input, speed up smelting rhythm, and promote the uniformity of molten bath temperature and compositions. Recently, the coherent jet with CO2 and O2 mixed injection (COMI) was proposed and demonstrated great application potentiality in reducing the dust production in EAF steelmaking. In the present study, based on the eddy dissipation concept model, a computational fluid dynamics model of coherent jets with COMI was built with the overall and detailed chemical kinetic mechanisms (GRI-Mech 3.0). Compared with one-step combustion reaction, GRI-Mech 3.0 consists of 325 elementary reactions with 53 components and can predict more accurate results. The numerical simulation results were validated by the combustion experiment data. The jet behavior and the fluid flow characteristics of coherent jets with COMI under 298 K and 1700 K (25 °C and 1427 °C) were studied and the results showed that for coherent jets with COMI, the chemical effect of CO2 significantly weakened the shrouding combustion reactions of CH4 and the relative importance of the chemical effect of CO2 increases with CO2 concentration increasing. The potential core length of coherent jet decreases with the volume fraction of CO2 increasing. Moreover, it also can be found that the potential core length of coherent jets was prolonged with higher ambient temperature.

  11. Study on the Fluid Flow Characteristics of Coherent Jets with CO2 and O2 Mixed Injection in Electric Arc Furnace Steelmaking Processes

    NASA Astrophysics Data System (ADS)

    Wei, Guangsheng; Zhu, Rong; Wu, Xuetao; Yang, Lingzhi; Dong, Kai; Cheng, Ting; Tang, Tianping

    2018-03-01

    As an efficient oxygen supplying technology, coherent jets are widely applied in electric arc furnace (EAF) steelmaking processes to strengthen chemical energy input, speed up smelting rhythm, and promote the uniformity of molten bath temperature and compositions. Recently, the coherent jet with CO2 and O2 mixed injection (COMI) was proposed and demonstrated great application potentiality in reducing the dust production in EAF steelmaking. In the present study, based on the eddy dissipation concept model, a computational fluid dynamics model of coherent jets with COMI was built with the overall and detailed chemical kinetic mechanisms (GRI-Mech 3.0). Compared with one-step combustion reaction, GRI-Mech 3.0 consists of 325 elementary reactions with 53 components and can predict more accurate results. The numerical simulation results were validated by the combustion experiment data. The jet behavior and the fluid flow characteristics of coherent jets with COMI under 298 K and 1700 K (25 °C and 1427 °C) were studied and the results showed that for coherent jets with COMI, the chemical effect of CO2 significantly weakened the shrouding combustion reactions of CH4 and the relative importance of the chemical effect of CO2 increases with CO2 concentration increasing. The potential core length of coherent jet decreases with the volume fraction of CO2 increasing. Moreover, it also can be found that the potential core length of coherent jets was prolonged with higher ambient temperature.

  12. Geological factors affecting CO2 plume distribution

    USGS Publications Warehouse

    Frailey, S.M.; Leetaru, H.

    2009-01-01

    Understanding the lateral extent of a CO2 plume has important implications with regards to buying/leasing pore volume rights, defining the area of review for an injection permit, determining the extent of an MMV plan, and managing basin-scale sequestration from multiple injection sites. The vertical and lateral distribution of CO2 has implications with regards to estimating CO2 storage volume at a specific site and the pore pressure below the caprock. Geologic and flow characteristics such as effective permeability and porosity, capillary pressure, lateral and vertical permeability anisotropy, geologic structure, and thickness all influence and affect the plume distribution to varying degrees. Depending on the variations in these parameters one may dominate the shape and size of the plume. Additionally, these parameters do not necessarily act independently. A comparison of viscous and gravity forces will determine the degree of vertical and lateral flow. However, this is dependent on formation thickness. For example in a thick zone with injection near the base, the CO2 moves radially from the well but will slow at greater radii and vertical movement will dominate. Generally the CO2 plume will not appreciably move laterally until the caprock or a relatively low permeability interval is contacted by the CO2. Conversely, in a relatively thin zone with the injection interval over nearly the entire zone, near the wellbore the CO2 will be distributed over the entire vertical component and will move laterally much further with minimal vertical movement. Assuming no geologic structure, injecting into a thin zone or into a thick zone immediately under a caprock will result in a larger plume size. With a geologic structure such as an anticline, CO2 plume size may be restricted and injection immediately below the caprock may have less lateral plume growth because the structure will induce downward vertical movement of the CO2 until the outer edge of the plume reaches a spill

  13. CARBON AND NUTRIENT FLOW THROUGH MULTIPLE TROPHIC LEVELS IN A CO2-ENRICHED SOUTHERN PINE FOREST COMMUNITY - FINAL TECHNICAL REPORT

    USDA-ARS?s Scientific Manuscript database

    The ability to predict the consequences of global change is predicated on our understanding of controls of energy and material flows through ecosystems. Research was conducted at the Forest Atmosphere CO2 Transfer and Storage-1 (FACTS-1) site at Duke University. This is a flagship experiment of the ...

  14. 2. COLD FLOW LABORATORY, VIEW TOWARDS NORTH. Glenn L. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. COLD FLOW LABORATORY, VIEW TOWARDS NORTH. - Glenn L. Martin Company, Titan Missile Test Facilities, Cold Flow Laboratory Building B, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

  15. Assessment of derelict soil quality: Abiotic, biotic and functional approaches.

    PubMed

    Vincent, Quentin; Auclerc, Apolline; Beguiristain, Thierry; Leyval, Corinne

    2018-02-01

    The intensification and subsequent closing down of industrial activities during the last century has left behind large surfaces of derelict lands. Derelict soils have low fertility, can be contaminated, and many of them remain unused. However, with the increasing demand of soil surfaces, they might be considered as a resource, for example for non-food biomass production. The study of their physico-chemical properties and of their biodiversity and biological activity may provide indications for their potential re-use. The objective of our study was to investigate the quality of six derelict soils, considering abiotic, biotic, and functional parameters. We studied (i) the soil bacteria, fungi, meso- and macro-fauna and plant communities of six different derelict soils (two from coking plants, one from a settling pond, two constructed ones made from different substrates and remediated soil, and an inert waste storage one), and (ii) their decomposition function based on the decomposer trophic network, enzyme activities, mineralization activity, and organic pollutant degradation. Biodiversity levels in these soils were high, but all biotic parameters, except the mycorrhizal colonization level, discriminated them. Multivariate analysis showed that biotic parameters co-varied more with fertility proxies than with soil contamination parameters. Similarly, functional parameters significantly co-varied with abiotic parameters. Among functional parameters, macro-decomposer proportion, enzyme activity, average mineralization capacity, and microbial polycyclic aromatic hydrocarbon degraders were useful to discriminate the soils. We assessed their quality by combining abiotic, biotic, and functional parameters: the compost-amended constructed soil displayed the highest quality, while the settling pond soil and the contaminated constructed soil displayed the lowest. Although differences among the soils were highlighted, this study shows that derelict soils may provide a

  16. CO2 Washout Testing of the REI and EM-ACES Space Suits

    NASA Technical Reports Server (NTRS)

    Mitchell, Kate; Norcross, Jason

    2011-01-01

    Requirements for using a space suit during ground testing include providing adequate carbon dioxide (CO2) washout for the suited subject. Acute CO2 exposure can lead to symptoms including headache, dyspnea, lethargy and eventually unconsciousness or even death. Symptoms depend on several factors including partial pressure of CO2 (ppCO2), duration of exposure, metabolic rate of the subject and physiological differences between subjects. The objective of this test was to characterize inspired oronasal ppCO2 in the Rear Entry I-Suit (REI) and the Enhanced Mobility Advanced Crew Escape Suit (EM-ACES) across a range of workloads and flow rates for which ground testing is nominally performed. Three subjects were tested in each suit. In all but one case, each subject performed the test twice to allow for comparison between tests. Suit pressure was maintained at 4.3 psid. Subjects wore the suit while resting, performing arm ergometry, and walking on a treadmill to generate metabolic workloads of approximately 500 to 3000 BTU/hr. Supply airflow was varied at 6, 5 and 4 actual cubic feet per minute (ACFM) at each workload. Subjects wore an oronasal mask with an open port in front of the mouth and were allowed to breathe freely. Oronasal ppCO2 was monitored real-time via gas analyzers with sampling tubes connected to the oronasal mask. Metabolic rate was calculated from the total CO2 production measured by an additional gas analyzer at the air outlet from the suit. Real-time metabolic rate was used to adjust the arm ergometer or treadmill workload to meet target metabolic rates. In both suits, inspired CO2 was primarily affected by the metabolic rate of the subject, with increased metabolic rate resulting in increased inspired ppCO2. Suit flow rate also affected inspired ppCO2, with decreased flow causing small increases in inspired ppCO2. The effect of flow was more evident at metabolic rates greater than or equal to 2000 BTU/hr. Results were consistent between suits, with

  17. 40 CFR 98.443 - Calculating CO2 geologic sequestration.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... each gas-liquid separator for which flow is measured using a mass flow meter, you must calculate...) For each gas-liquid separator for which flow is measured using a volumetric flow meter, you must...) To aggregate production data, you must sum the mass of all of the CO2 separated at each gas-liquid...

  18. Preferential flow pathways revealed by field based stable isotope analysis of CO2 by mid-infrared laser spectroscopy

    NASA Astrophysics Data System (ADS)

    van Geldern, Robert; Nowak, Martin; Zimmer, Martin; Szizybalski, Alexandra; Myrttinen, Anssi; Barth, Johannes A. C.; Jost, Hj

    2016-04-01

    A newly developed and commercially available isotope ratio laser spectrometer for CO2 analyses has been tested during a 10-day field monitoring campaign at the Ketzin pilot site for CO2 storage in northern Germany. The laser instrument is based on tunable laser direct absorption in the mid-infrared. The instrument recorded a continuous 10-day carbon stable isotope data set with 30 minutes resolution directly on-site in a field-based laboratory container during a tracer experiment. To test the instruments performance and accuracy the monitoring campaign was accompanied by daily CO2 sampling for laboratory analyses with isotope ratio mass spectrometry (IRMS). The carbon stable isotope ratios measured by conventional IRMS technique and by the new mid-infrared laser spectrometer agree remarkably well within 2σ analytical precision (<0.3 ‰). This proves the capability of the new mid-infrared direct absorption technique to measure high precision and accurate real-time table isotope data directly in the field. The injected CO2 tracer had a distinct δ13C value that was largely different from the reservoir background value. The laser spectroscopy data revealed a prior to this study unknown, intensive dynamic with fast changing δ13C values. The arrival pattern of the tracer suggest that the observed fluctuations were probably caused by migration along separate and distinct preferential flow paths between injection well and observation well. The new technique might contribute to a better tracing of the migration of the underground CO2 plume and help to ensure the long-term integrity of the reservoir.

  19. The Field-Laboratory for CO2 Storage 'CO2SINK

    NASA Astrophysics Data System (ADS)

    Würdemann, Hilke; Möller, Fabian; Kühn, Michael; Borm, Günter; Schilling, Frank R.

    2010-05-01

    observation wells are equipped with 'smart casing technology' containing a Distributed Temperature Sensing (DTS) and electrodes for Electrical Resistivity Tomography (ERT) behind casing, facing the rocks. The geophysical monitoring includes crosshole seismic experiments, Vertical Seismic Profiling (VSP) and Moving Source Profiling (MSP), star seismic experiments and 4-D seismics. Gas membrane sensors (GMS) monitored the arrival of CO2 at the observation wells: CO2 arrived after injection of about 500 t of CO2.at the first well. Arrival in the second well was 9 months after start of injection, having injected an amount of about 11,000 t. Prior to CO2, the arrival of the gas tracers nitrogen and krypton was observed. Pressure and temperature logs showed a supercritical state of the CO2 in all three wells at depth of the storage formation after arrival of CO2. Downhole samples of the brine showed changes in the fluid composition and the activity of biocenosis due CO2 exposure (Morozova et al., EGU General Assembly 2010). Numerical models are benchmarked via the monitoring results indicating a sufficient match for the arrival at the first observation well. First results of ERT measurements indicate an anisotopic flow of CO2 coinciding with the 'on-time' arrival of CO2 at the first well and the late arrival at the second well. Time lapse crosshole seismics showed no considerable change in seismic velocity between the two observation wells within the first two repeats after injection of 660 t and 1,700 t of CO2, respectively. However, after injection of 18,000 t CO2 all time-lapse surveys showed a clearly observable signature of the CO2 propagating in the Stuttgart formation. In May 2010 results from twenty months of operation and monitoring the storage operation will be presented. Morozova, D., Zettlitzer, M.., Vieth A., Würdemann, H., (2010). Microbial community response to the CO2 injection and storage in the saline aquifer, Ketzin, Germany. European Geosciences Union (EGU

  20. Abiotic methane formation during experimental serpentinization of olivine

    PubMed Central

    2016-01-01

    Fluids circulating through actively serpentinizing systems are often highly enriched in methane (CH4). In many cases, the CH4 in these fluids is thought to derive from abiotic reduction of inorganic carbon, but the conditions under which this process can occur in natural systems remain unclear. In recent years, several studies have reported abiotic formation of CH4 during experimental serpentinization of olivine at temperatures at or below 200 °C. However, these results seem to contradict studies conducted at higher temperatures (300 °C to 400 °C), where substantial kinetic barriers to CH4 synthesis have been observed. Here, the potential for abiotic formation of CH4 from dissolved inorganic carbon during olivine serpentinization is reevaluated in a series of laboratory experiments conducted at 200 °C to 320 °C. A 13C-labeled inorganic carbon source was used to unambiguously determine the origin of CH4 generated in the experiments. Consistent with previous high-temperature studies, the results indicate that abiotic formation of CH4 from reduction of dissolved inorganic carbon during the experiments is extremely limited, with nearly all of the observed CH4 derived from background sources. The results indicate that the potential for abiotic synthesis of CH4 in low-temperature serpentinizing environments may be much more limited than some recent studies have suggested. However, more extensive production of CH4 was observed in one experiment performed under conditions that allowed an H2-rich vapor phase to form, suggesting that shallow serpentinization environments where a separate gas phase is present may be more favorable for abiotic synthesis of CH4. PMID:27821742

  1. Abiotic methane formation during experimental serpentinization of olivine.

    PubMed

    McCollom, Thomas M

    2016-12-06

    Fluids circulating through actively serpentinizing systems are often highly enriched in methane (CH 4 ). In many cases, the CH 4 in these fluids is thought to derive from abiotic reduction of inorganic carbon, but the conditions under which this process can occur in natural systems remain unclear. In recent years, several studies have reported abiotic formation of CH 4 during experimental serpentinization of olivine at temperatures at or below 200 °C. However, these results seem to contradict studies conducted at higher temperatures (300 °C to 400 °C), where substantial kinetic barriers to CH 4 synthesis have been observed. Here, the potential for abiotic formation of CH 4 from dissolved inorganic carbon during olivine serpentinization is reevaluated in a series of laboratory experiments conducted at 200 °C to 320 °C. A 13 C-labeled inorganic carbon source was used to unambiguously determine the origin of CH 4 generated in the experiments. Consistent with previous high-temperature studies, the results indicate that abiotic formation of CH 4 from reduction of dissolved inorganic carbon during the experiments is extremely limited, with nearly all of the observed CH 4 derived from background sources. The results indicate that the potential for abiotic synthesis of CH 4 in low-temperature serpentinizing environments may be much more limited than some recent studies have suggested. However, more extensive production of CH 4 was observed in one experiment performed under conditions that allowed an H 2 -rich vapor phase to form, suggesting that shallow serpentinization environments where a separate gas phase is present may be more favorable for abiotic synthesis of CH 4 .

  2. Transgenic banana plants overexpressing a native plasma membrane aquaporin MusaPIP1;2 display high tolerance levels to different abiotic stresses.

    PubMed

    Sreedharan, Shareena; Shekhawat, Upendra K S; Ganapathi, Thumballi R

    2013-10-01

    Water transport across cellular membranes is regulated by a family of water channel proteins known as aquaporins (AQPs). As most abiotic stresses like suboptimal temperatures, drought or salinity result in cellular dehydration, it is imperative to study the cause-effect relationship between AQPs and the cellular consequences of abiotic stress stimuli. Although plant cells have a high isoform diversity of AQPs, the individual and integrated roles of individual AQPs in optimal and suboptimal physiological conditions remain unclear. Herein, we have identified a plasma membrane intrinsic protein gene (MusaPIP1;2) from banana and characterized it by overexpression in transgenic banana plants. Cellular localization assay performed using MusaPIP1;2::GFP fusion protein indicated that MusaPIP1;2 translocated to plasma membrane in transformed banana cells. Transgenic banana plants overexpressing MusaPIP1;2 constitutively displayed better abiotic stress survival characteristics. The transgenic lines had lower malondialdehyde levels, elevated proline and relative water content and higher photosynthetic efficiency as compared to equivalent controls under different abiotic stress conditions. Greenhouse-maintained hardened transgenic plants showed faster recovery towards normal growth and development after cessation of abiotic stress stimuli, thereby underlining the importance of these plants in actual environmental conditions wherein the stress stimuli is often transient but severe. Further, transgenic plants where the overexpression of MusaPIP1;2 was made conditional by tagging it with a stress-inducible native dehydrin promoter also showed similar stress tolerance characteristics in in vitro and in vivo assays. Plants developed in this study could potentially enable banana cultivation in areas where adverse environmental conditions hitherto preclude commercial banana cultivation. © 2013 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons

  3. Co-Flow Hollow Cathode Technology

    NASA Technical Reports Server (NTRS)

    Hofer, Richard R.; Goebel, Dan M.

    2011-01-01

    Hall thrusters utilize identical hollow cathode technology as ion thrusters, yet must operate at much higher mass flow rates in order to efficiently couple to the bulk plasma discharge. Higher flow rates are necessary in order to provide enough neutral collisions to transport electrons across magnetic fields so that they can reach the discharge. This higher flow rate, however, has potential life-limiting implications for the operation of the cathode. A solution to the problem involves splitting the mass flow into the hollow cathode into two streams, the internal and external flows. The internal flow is fixed and set such that the neutral pressure in the cathode allows for a high utilization of the emitter surface area. The external flow is variable depending on the flow rate through the anode of the Hall thruster, but also has a minimum in order to suppress high-energy ion generation. In the co-flow hollow cathode, the cathode assembly is mounted on thruster centerline, inside the inner magnetic core of the thruster. An annular gas plenum is placed at the base of the cathode and propellant is fed throughout to produce an azimuthally symmetric flow of gas that evenly expands around the cathode keeper. This configuration maximizes propellant utilization and is not subject to erosion processes. External gas feeds have been considered in the past for ion thruster applications, but usually in the context of eliminating high energy ion production. This approach is adapted specifically for the Hall thruster and exploits the geometry of a Hall thruster to feed and focus the external flow without introducing significant new complexity to the thruster design.

  4. Dissolved CO2 Increases Breakthrough Porosity in Natural Porous Materials.

    PubMed

    Yang, Y; Bruns, S; Stipp, S L S; Sørensen, H O

    2017-07-18

    When reactive fluids flow through a dissolving porous medium, conductive channels form, leading to fluid breakthrough. This phenomenon is caused by the reactive infiltration instability and is important in geologic carbon storage where the dissolution of CO 2 in flowing water increases fluid acidity. Using numerical simulations with high resolution digital models of North Sea chalk, we show that the breakthrough porosity is an important indicator of dissolution pattern. Dissolution patterns reflect the balance between the demand and supply of cumulative surface. The demand is determined by the reactive fluid composition while the supply relies on the flow field and the rock's microstructure. We tested three model scenarios and found that aqueous CO 2 dissolves porous media homogeneously, leading to large breakthrough porosity. In contrast, solutions without CO 2 develop elongated convective channels known as wormholes, with low breakthrough porosity. These different patterns are explained by the different apparent solubility of calcite in free drift systems. Our results indicate that CO 2 increases the reactive subvolume of porous media and reduces the amount of solid residual before reactive fluid can be fully channelized. Consequently, dissolved CO 2 may enhance contaminant mobilization near injection wellbores, undermine the mechanical sustainability of formation rocks and increase the likelihood of buoyance driven leakage through carbonate rich caprocks.

  5. Hydrogen peroxide priming modulates abiotic oxidative stress tolerance: insights from ROS detoxification and scavenging

    PubMed Central

    Hossain, Mohammad A.; Bhattacharjee, Soumen; Armin, Saed-Moucheshi; Qian, Pingping; Xin, Wang; Li, Hong-Yu; Burritt, David J.; Fujita, Masayuki; Tran, Lam-Son P.

    2015-01-01

    Plants are constantly challenged by various abiotic stresses that negatively affect growth and productivity worldwide. During the course of their evolution, plants have developed sophisticated mechanisms to recognize external signals allowing them to respond appropriately to environmental conditions, although the degree of adjustability or tolerance to specific stresses differs from species to species. Overproduction of reactive oxygen species (ROS; hydrogen peroxide, H2O2; superoxide, O2⋅-; hydroxyl radical, OH⋅ and singlet oxygen, 1O2) is enhanced under abiotic and/or biotic stresses, which can cause oxidative damage to plant macromolecules and cell structures, leading to inhibition of plant growth and development, or to death. Among the various ROS, freely diffusible and relatively long-lived H2O2 acts as a central player in stress signal transduction pathways. These pathways can then activate multiple acclamatory responses that reinforce resistance to various abiotic and biotic stressors. To utilize H2O2 as a signaling molecule, non-toxic levels must be maintained in a delicate balancing act between H2O2 production and scavenging. Several recent studies have demonstrated that the H2O2-priming can enhance abiotic stress tolerance by modulating ROS detoxification and by regulating multiple stress-responsive pathways and gene expression. Despite the importance of the H2O2-priming, little is known about how this process improves the tolerance of plants to stress. Understanding the mechanisms of H2O2-priming-induced abiotic stress tolerance will be valuable for identifying biotechnological strategies to improve abiotic stress tolerance in crop plants. This review is an overview of our current knowledge of the possible mechanisms associated with H2O2-induced abiotic oxidative stress tolerance in plants, with special reference to antioxidant metabolism. PMID:26136756

  6. Formation of an optical pulsed discharge in a supersonic air flow by radiation of a repetitively pulsed CO{sub 2} laser

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

    Malov, Aleksei N; Orishich, Anatolii M

    Results of optimisation of repetitively pulsed CO{sub 2}-laser generation are presented for finding physical conditions of forming stable burning of an optical pulsed discharge (OPD) in a supersonic air flow and for studying the influence of pulse parameters on the energy absorption efficiency of laser radiation in plasma. The optical discharge in a supersonic air flow was formed by radiation of a repetitively pulsed CO{sub 2} laser with mechanical Q-switching excited by a discharge with a convective cooling of the working gas. For the first time the influence of radiation pulse parameters on the ignition conditions and stable burning ofmore » the OPD in a supersonic air flow was investigated and the efficiency of laser radiation absorption in plasma was studied. The influence of the air flow velocity on stability of plasma production was investigated. It was shown that stable burning of the OPD in a supersonic flow is realised at a high pulse repetition rate where the interval between radiation pulses is shorter than the time of plasma blowing-off. Study of the instantaneous value of the absorption coefficient shows that after a breakdown in a time lapse of 100 - 150 ns, a quasi-stationary 'absorption phase' is formed with the duration of {approx}1.5 ms, which exists independently of air flow and radiation pulse repetition rate. This phase of strong absorption is, seemingly, related to evolution of the ionisation wave. (laser applications and other topics in quantum electronics)« less

  7. CO2 storage capacity estimates from fluid dynamics (Invited)

    NASA Astrophysics Data System (ADS)

    Juanes, R.; MacMinn, C. W.; Szulczewski, M.

    2009-12-01

    We study a sharp-interface mathematical model for the post-injection migration of a plume of CO2 in a deep saline aquifer under the influence of natural groundwater flow, aquifer slope, gravity override, and capillary trapping. The model leads to a nonlinear advection-diffusion equation, where the diffusive term describes the upward spreading of the CO2 against the caprock. We find that the advective terms dominate the flow dynamics even for moderate gravity override. We solve the model analytically in the hyperbolic limit, accounting rigorously for the injection period—using the true end-of-injection plume shape as an initial condition. We extend the model by incorporating the effect of CO2 dissolution into the brine, which—we find—is dominated by convective mixing. This mechanism enters the model as a nonlinear sink term. From a linear stability analysis, we propose a simple estimate of the convective dissolution flux. We then obtain semi-analytic estimates of the maximum plume migration distance and migration time for complete trapping. Our analytical model can be used to estimate the storage capacity (from capillary and dissolution trapping) at the geologic basin scale, and we apply the model to various target formations in the United States. Schematic of the migration of a CO2 plume at the geologic basin scale. During injection, the CO2 forms a plume that is subject to gravity override. At the end of the injection, all the CO2 is mobile. During the post-injection period, the CO2 migrates updip and also driven by regional groundwater flow. At the back end of the plume, where water displaces CO2, the plume leaves a wake or residual CO2 due to capillary trapping. At the bottom of the moving plume, CO2 dissolves into the brine—a process dominated by convective mixing. These two mechanisms—capillary trapping and convective dissolution—reduce the size of the mobile plume as it migrates. In this communication, we present an analytical model that predicts

  8. Dynamic Response of CoSb2O6 Trirutile-Type Oxides in a CO2 Atmosphere at Low-Temperatures

    PubMed Central

    Guillén-Bonilla, Alex; Rodríguez-Betancourtt, Verónica-María; Flores-Martínez, Martín; Blanco-Alonso, Oscar; Reyes-Gómez, Juan; Gildo-Ortiz, Lorenzo; Guillén-Bonilla, Héctor

    2014-01-01

    Experimental work on the synthesis of the CoSb2O6 oxide and its CO2 sensing properties is presented here. The oxide was synthesized by a microwave-assisted colloidal method in presence of ethylenediamine after calcination at 600 °C. This CoSb2O6 oxide crystallized in a tetragonal structure with cell parameters a = 4.6495 and c = 9.2763 Å, and space group P42/mnm. To prove its physical, chemical and sensing properties, the oxide was subjected to a series of tests: Raman spectroscopy, Scanning Electron Microscopy (SEM) and impedance (Z) measurements. Microstructures, like columns, bars and hollow hemispheres, were observed. For the CO2 sensing test, a thick film of CoSb2O6 was used, measuring the impedance variations on the presence of air/CO2 flows (0.100 sccm/0.100 sccm) using AC (alternating current) signals in the frequency-range 0.1–100 kHz and low relative temperatures (250 and 300 °C). The CO2 sensing results were quite good. PMID:25162232

  9. Chinese CO2 emission flows have reversed since the global financial crisis.

    PubMed

    Mi, Zhifu; Meng, Jing; Guan, Dabo; Shan, Yuli; Song, Malin; Wei, Yi-Ming; Liu, Zhu; Hubacek, Klaus

    2017-11-23

    This study seeks to estimate the carbon implications of recent changes in China's economic development patterns and role in global trade in the post-financial-crisis era. We utilised the latest socioeconomic datasets to compile China's 2012 multiregional input-output (MRIO) table. Environmentally extended input-output analysis and structural decomposition analysis (SDA) were applied to investigate the driving forces behind changes in CO 2 emissions embodied in China's domestic and foreign trade from 2007 to 2012. Here we show that emission flow patterns have changed greatly in both domestic and foreign trade since the financial crisis. Some economically less developed regions, such as Southwest China, have shifted from being a net emission exporter to being a net emission importer. In terms of foreign trade, emissions embodied in China's exports declined from 2007 to 2012 mainly due to changes in production structure and efficiency gains, while developing countries became the major destination of China's export emissions.

  10. Experimental observation of permeability changes in dolomite at CO2 sequestration conditions.

    PubMed

    Tutolo, Benjamin M; Luhmann, Andrew J; Kong, Xiang-Zhao; Saar, Martin O; Seyfried, William E

    2014-02-18

    Injection of cool CO2 into geothermally warm carbonate reservoirs for storage or geothermal energy production may lower near-well temperature and lead to mass transfer along flow paths leading away from the well. To investigate this process, a dolomite core was subjected to a 650 h, high pressure, CO2 saturated, flow-through experiment. Permeability increased from 10(-15.9) to 10(-15.2) m(2) over the initial 216 h at 21 °C, decreased to 10(-16.2) m(2) over 289 h at 50 °C, largely due to thermally driven CO2 exsolution, and reached a final value of 10(-16.4) m(2) after 145 h at 100 °C due to continued exsolution and the onset of dolomite precipitation. Theoretical calculations show that CO2 exsolution results in a maximum pore space CO2 saturation of 0.5, and steady state relative permeabilities of CO2 and water on the order of 0.0065 and 0.1, respectively. Post-experiment imagery reveals matrix dissolution at low temperatures, and subsequent filling-in of flow passages at elevated temperature. Geochemical calculations indicate that reservoir fluids subjected to a thermal gradient may exsolve and precipitate up to 200 cm(3) CO2 and 1.5 cm(3) dolomite per kg of water, respectively, resulting in substantial porosity and permeability redistribution.

  11. Inversion analysis of estimating interannual variability and its uncertainties in biotic and abiotic parameters of a parsimonious physiologically based model after wind disturbance

    NASA Astrophysics Data System (ADS)

    Toda, M.; Yokozawa, M.; Richardson, A. D.; Kohyama, T.

    2011-12-01

    The effects of wind disturbance on interannual variability in ecosystem CO2 exchange have been assessed in two forests in northern Japan, i.e., a young, even-aged, monocultured, deciduous forest and an uneven-aged mixed forest of evergreen and deciduous trees, including some over 200 years old using eddy covariance (EC) measurements during 2004-2008. The EC measurements have indicated that photosynthetic recovery of trees after a huge typhoon occurred during early September in 2004 activated annual carbon uptake of both forests due to changes in physiological response of tree leaves during their growth stages. However, little have been resolved about what biotic and abiotic factors regulated interannual variability in heat, water and carbon exchange between an atmosphere and forests. In recent years, an inverse modeling analysis has been utilized as a powerful tool to estimate biotic and abiotic parameters that might affect heat, water and CO2 exchange between the atmosphere and forest of a parsimonious physiologically based model. We conducted the Bayesian inverse model analysis for the model with the EC measurements. The preliminary result showed that the above model-derived NEE values were consistent with observed ones on the hourly basis with optimized parameters by Baysian inversion. In the presentation, we would examine interannual variability in biotic and abiotic parameters related to heat, water and carbon exchange between the atmosphere and forests after disturbance by typhoon.

  12. Steady-state studies of the reactions of H2O-CO and CO2-H2 mixtures with liquid iron

    NASA Astrophysics Data System (ADS)

    Sasaki, Y.; Belton, G. R.

    1998-08-01

    Studies have been made of the steady-stata composition of liquid iron exposed to high flow rates of H2O-CO mixtures at 1550 °C to 1700 °C and CO2-H2 mixtures at 1600 °C. Values of the steady-state activity of oxygen have been established by measurement of either the carbon concentration or the silicon concentration when the iron was held in a silica crucible. Additions of sulfur or selenium to the iron have been found to result in steady-state oxygen activities, which differ significantly from those expected from water-gas equilibrium. The results are interpreted to show that the ratio of the apparent first-order rate constants for the reactions of H2O and CO2 with liquid iron is about 3 at 1600 °C. It is shown that the dependencies of the rate constants on the activities of sulfur, oxygen, and selenium must, even if complex, be similar for the H2O and CO2 reactions with liquid iron, to a good approximation.

  13. Progress and challenges for abiotic stress proteomics of crop plants.

    PubMed

    Barkla, Bronwyn J; Vera-Estrella, Rosario; Pantoja, Omar

    2013-06-01

    Plants are continually challenged to recognize and respond to adverse changes in their environment to avoid detrimental effects on growth and development. Understanding the mechanisms that crop plants employ to resist and tolerate abiotic stress is of considerable interest for designing agriculture breeding strategies to ensure sustainable productivity. The application of proteomics technologies to advance our knowledge in crop plant abiotic stress tolerance has increased dramatically in the past few years as evidenced by the large amount of publications in this area. This is attributed to advances in various technology platforms associated with MS-based techniques as well as the accessibility of proteomics units to a wider plant research community. This review summarizes the work which has been reported for major crop plants and evaluates the findings in context of the approaches that are widely employed with the aim to encourage broadening the strategies used to increase coverage of the proteome. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. The core regulatory network of the abscisic acid pathway in banana: genome-wide identification and expression analyses during development, ripening, and abiotic stress.

    PubMed

    Hu, Wei; Yan, Yan; Shi, Haitao; Liu, Juhua; Miao, Hongxia; Tie, Weiwei; Ding, Zehong; Ding, XuPo; Wu, Chunlai; Liu, Yang; Wang, Jiashui; Xu, Biyu; Jin, Zhiqiang

    2017-08-29

    Abscisic acid (ABA) signaling plays a crucial role in developmental and environmental adaptation processes of plants. However, the PYL-PP2C-SnRK2 families that function as the core components of ABA signaling are not well understood in banana. In the present study, 24 PYL, 87 PP2C, and 11 SnRK2 genes were identified from banana, which was further supported by evolutionary relationships, conserved motif and gene structure analyses. The comprehensive transcriptomic analyses showed that banana PYL-PP2C-SnRK2 genes are involved in tissue development, fruit development and ripening, and response to abiotic stress in two cultivated varieties. Moreover, comparative expression analyses of PYL-PP2C-SnRK2 genes between BaXi Jiao (BX) and Fen Jiao (FJ) revealed that PYL-PP2C-SnRK2-mediated ABA signaling might positively regulate banana fruit ripening and tolerance to cold, salt, and osmotic stresses. Finally, interaction networks and co-expression assays demonstrated that the core components of ABA signaling were more active in FJ than in BX in response to abiotic stress, further supporting the crucial role of the genes in tolerance to abiotic stress in banana. This study provides new insights into the complicated transcriptional control of PYL-PP2C-SnRK2 genes, improves the understanding of PYL-PP2C-SnRK2-mediated ABA signaling in the regulation of fruit development, ripening, and response to abiotic stress, and identifies some candidate genes for genetic improvement of banana.

  15. A radiatively pumped CW CO2 laser

    NASA Technical Reports Server (NTRS)

    Insuik, R. J.; Christiansen, W. H.

    1984-01-01

    A proof of principle experiment to demonstrate the physics of a radiatively pumped laser has been carried out. For the first time, a blackbody cavity has optically pumped a CW CO2 laser. Results are presented from a series of experiments using mixtures of CO2, He, and Ar in which maximum output power was obtained with a 20 percent CO2-15 percent He-65 percent Ar mixture. The dependence of the output power on the blackbody temperature and the cooling gas flow rate is also discussed. By appropriately varying these parameters, continuous output powers of 8-10 mW have been achieved.

  16. The crystallization kinetic model of nano-CaCO3 in CO2-ammonia-phosphogypsum three-phase reaction system

    NASA Astrophysics Data System (ADS)

    Liu, Hao; Lan, Peiqiang; Lu, Shangqing; Wu, Sufang

    2018-06-01

    Phosphogypsum (PG) as a low-cost calcium resource was used to prepare nano-CaCO3 in a three-phase system by reactions. Based on the population balance equation, nano-CaCO3 crystal nucleation and growth model in the gas (CO2)-liquid (NH3·H2O)-solid (CaSO4) three-phase system was established. The crystallization kinetic model of nano-CaCO3 in CO2-NH3·H2O-CaSO4 reactions system was experimental developed over an optimized temperature range of 20-40 °C and CO2 flow rate range of 138-251 ml/min as rCaCO3 =kn 32 πM2γ3/3R3ρ2T3 (C -C∗)0.8/[ ln (C /C∗) ]3 + πρ/3M kg3 kn(C -C∗) 2t3 , where nano-CaCO3 nucleation rate constant was kn = 6.24 ×1019 exp(-15940/RT) and nano-CaCO3 growth rate constant was kg = 0.79 exp(-47650/RT) respectively. Research indicated that nucleation rates and growth rates both increased with the increasing of temperature and CO32- ion concentration. And crystal growth was dependent on temperature more than that of nucleation process because the activation energy of CaCO3 growth was bigger than that of CaCO3 nucleation. Decreasing the reaction temperature and CO2 flow rate was more beneficial for producing nano-size CaCO3 because of the lower CaCO3 growth rates. The deduced kinetic equation could briefly predict the average particle sizes of nano-CaCO3.

  17. Advanced buffer materials for indoor air CO2 control in commercial buildings.

    PubMed

    Rajan, P E; Krishnamurthy, A; Morrison, G; Rezaei, F

    2017-11-01

    In this study, we evaluated solid sorbents for their ability to passively control indoor CO 2 concentration in buildings or rooms with cyclic occupancy (eg, offices, bedrooms). Silica supported amines were identified as suitable candidates and systematically evaluated in the removal of CO 2 from indoor air by equilibrium and dynamic techniques. In particular, sorbents with various amine loadings were synthesized using tetraethylenepentamine (TEPA), poly(ethyleneimine) (PEI) and a silane coupling agent 3-aminopropyltriethoxysilane (APS). TGA analysis indicates that TEPA impregnated silica not only displays a relatively high adsorption capacity when exposed to ppm level CO 2 concentrations, but also is capable of desorbing the majority of CO 2 by air flow (eg, by concentration gradient). In 10 L flow-through chamber experiments, TEPA-based sorbents reduced outlet CO 2 by up to 5% at 50% RH and up to 93% of CO 2 adsorbed over 8 hours was desorbed within 16 hours. In 8 m 3 flow-through chamber experiments, 18 g of the sorbent powder spread over a 2 m 2 area removed approximately 8% of CO 2 injected. By extrapolating these results to real buildings, we estimate that meaningful reductions in the CO 2 can be achieved, which may help reduce energy requirements for ventilation and/or improve air quality. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  18. A Multi-scale Approach for CO2 Accounting and Risk Analysis in CO2 Enhanced Oil Recovery Sites

    NASA Astrophysics Data System (ADS)

    Dai, Z.; Viswanathan, H. S.; Middleton, R. S.; Pan, F.; Ampomah, W.; Yang, C.; Jia, W.; Lee, S. Y.; McPherson, B. J. O. L.; Grigg, R.; White, M. D.

    2015-12-01

    Using carbon dioxide in enhanced oil recovery (CO2-EOR) is a promising technology for emissions management because CO2-EOR can dramatically reduce carbon sequestration costs in the absence of greenhouse gas emissions policies that include incentives for carbon capture and storage. This study develops a multi-scale approach to perform CO2 accounting and risk analysis for understanding CO2 storage potential within an EOR environment at the Farnsworth Unit of the Anadarko Basin in northern Texas. A set of geostatistical-based Monte Carlo simulations of CO2-oil-water flow and transport in the Marrow formation are conducted for global sensitivity and statistical analysis of the major risk metrics: CO2 injection rate, CO2 first breakthrough time, CO2 production rate, cumulative net CO2 storage, cumulative oil and CH4 production, and water injection and production rates. A global sensitivity analysis indicates that reservoir permeability, porosity, and thickness are the major intrinsic reservoir parameters that control net CO2 injection/storage and oil/CH4 recovery rates. The well spacing (the distance between the injection and production wells) and the sequence of alternating CO2 and water injection are the major operational parameters for designing an effective five-spot CO2-EOR pattern. The response surface analysis shows that net CO2 injection rate increases with the increasing reservoir thickness, permeability, and porosity. The oil/CH4 production rates are positively correlated to reservoir permeability, porosity and thickness, but negatively correlated to the initial water saturation. The mean and confidence intervals are estimated for quantifying the uncertainty ranges of the risk metrics. The results from this study provide useful insights for understanding the CO2 storage potential and the corresponding risks of commercial-scale CO2-EOR fields.

  19. SERDP ER-1376 Enhancement of In Situ Bioremediation of Energetic Compounds by Coupled Abiotic/Biotic Processes:Final Report for 2004 - 2006

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

    Szecsody, James E.; Comfort, Steve; Fredrickson, Herbert L.

    2007-08-07

    This project was initiated by SERDP to quantify processes and determine the effectiveness of abiotic/biotic mineralization of energetics (RDX, HMX, TNT) in aquifer sediments by combinations of biostimulation (carbon, trace nutrient additions) and chemical reduction of sediment to create a reducing environment. Initially it was hypothesized that a balance of chemical reduction of sediment and biostimulation would increase the RDX, HMX, and TNT mineralization rate significantly (by a combination of abiotic and biotic processes) so that this abiotic/biotic treatment may be a more efficient for remediation than biotic treatment alone in some cases. Because both abiotic and biotic processes aremore » involved in energetic mineralization in sediments, it was further hypothesized that consideration for both abiotic reduction and microbial growth was need to optimize the sediment system for the most rapid mineralization rate. Results show that there are separate optimal abiotic/biostimulation aquifer sediment treatments for RDX/HMX and for TNT. Optimal sediment treatment for RDX and HMX (which have chemical similarities and similar degradation pathways) is mainly chemical reduction of sediment, which increased the RDX/HMX mineralization rate 100 to150 times (relative to untreated sediment), with additional carbon or trace nutrient addition, which increased the RDX/HMX mineralization rate an additional 3 to 4 times. In contrast, the optimal aquifer sediment treatment for TNT involves mainly biostimulation (glucose addition), which stimulates a TNT/glucose cometabolic degradation pathway (6.8 times more rapid than untreated sediment), degrading TNT to amino-intermediates that irreversibly sorb (i.e., end product is not CO2). The TNT mass migration risk is minimized by these transformation reactions, as the triaminotoluene and 2,4- and 2,6-diaminonitrotoluene products that irreversibly sorb are no longer mobile in the subsurface environment. These transformation rates are

  20. Huge, CO2-charged debris-flow deposits and tectonic sagging in the northern plains of Mars

    USGS Publications Warehouse

    Tanaka, K.L.; Banerdt, W.B.; Kargel, J.S.; Hoffman, N.

    2001-01-01

    The northern plains of Mars contain a vast deposit, covering one-sixth of the planet, that apparently resulted in extensive lithospheric deformation. The center of the deposit may be as much as 2-3 km thick. The deposit has lobate margins consistent with the flow of fluidized debris for hundreds to thousands of kilometers derived from highland and high-plains sources. The deposit surface lowers inward by ???900 m in places and is locally bordered by a bulge ???300 m high. Similar deformation accompanied development of Pleistocene ice sheets on Earth. The lack of burial of a large inlier of older terrain and the response time of the mantle to the loading require that the deposit was emplaced in <1000 yr, assuming that the deposit was originally flat. We account for what may have been the largest catastrophic erosional and/or depositional event in solar system history by invoking pore-filling subsurface CO2 as an active agent in the processes of source-rock collapse and debris flow.

  1. Microbial Life Driving Low-Temperature Basalt Alteration in the Subsurface: Decoupling Abiotic Processes from Biologically-Mediated Rock Alteration

    NASA Astrophysics Data System (ADS)

    Moore, R.; Lecoeuvre, A.; Stephant, S.; Dupraz, S.; Ranchou-Peyruse, M.; Ranchou-Peyruse, A.; Gérard, E.; Ménez, B.

    2017-12-01

    Microorganisms are involved with specific rock alteration processes in the deep subsurface. It is a challenge to link any contribution microbial life may have on rock alteration with specific functions or phyla because many alteration features and secondary minerals produced by metabolic processes can also produce abiotically. Here, two flow-through experiments were designed to mimic the circulation of a CO2-rich fluid through crystalline basalt. In order to identify microbially-mediated alteration and be able to link it with specific metabolisms represented in the subsurface, a relatively fresh crystalline basalt substrate was subsampled, sterilized and used as the substrate for both experiments. In one experiment, the substrate was left sterile, and in the other it was inoculated with an enrichment culture derived from the same aquifer as the rock substrate. Initial results show that the inoculum contained Proteobacteria and Firmicutes, which have diverse metabolic potentials. Fluid and rock analyses before, during, and after the experiments show that mineralogy, fluid chemistry, and dissolution processes differ between the sterile and inoculated systems. In the inoculated experiment iron-rich orthopyroxenes were preferentially dissolved while in the sterile system clinopyroxenes and plagioclases both exhibited a higher degree of dissolution. Additionally, the patterns of CO2 consumption and production over the duration of both experiments is different. This suggest that in a low-temperature basalt system with microorganisms CO2 is either consumed to produce biomass, or that carbonates are produced and then subsequently preserved. This suite of results combined with molecular ecology analyses can be used to conclude that in low-temperature basalts microorganisms play an intrinsic role in rock alteration.

  2. Development of a preprototype sabatier CO2 reduction subsystem

    NASA Technical Reports Server (NTRS)

    Kleiner, G. N.; Birbara, P.

    1980-01-01

    A preoprototype Sabatier CO2 Reduction Subsystem was successfully designed, fabricated and tested. The lightweight, quick starting reactor utilizes a highly active and physically durable methanation catalyst composed of ruthenium on alumina. The use of this improved catalyst permits a single straight through plug flow design with an average lean component H2/CO2 conversion efficiency of over 99% over a range of H2/CO2 molar ratios of 1.8 to 5 while operating with flows equivalent to a crew size of one person steadystate to 3 persons cyclical (equivalent to 5 persons steady state). The reactor requires no heater operation after start-up even during simulated 55 minute lightside/39 minute darkside orbital operation over the above range of molar ratios and crew loadings. The subsystem's operation and performance is controlled by a microprocessor and displayed on a nineteen inch multi-colored cathode ray tube.

  3. Assessment of the Brain's Macro- and Micro-Circulatory Blood Flow Responses to CO2 via Transfer Function Analysis.

    PubMed

    Müller, Martin W-D; Österreich, Mareike; Müller, Andreas; Lygeros, John

    2016-01-01

    At present, there is no standard bedside method for assessing cerebral autoregulation (CA) with high temporal resolution. We combined the two methods most commonly used for this purpose, transcranial Doppler sonography (TCD, macro-circulation level), and near-infrared spectroscopy (NIRS, micro-circulation level), in an attempt to identify the most promising approach. In eight healthy subjects (5 women; mean age, 38 ± 10 years), CA disturbance was achieved by adding carbon dioxide (CO2) to the breathing air. We simultaneously recorded end-tidal CO2 (ETCO2), blood pressure (BP; non-invasively at the fingertip), and cerebral blood flow velocity (CBFV) in both middle cerebral arteries using TCD and determined oxygenated and deoxygenated hemoglobin levels using NIRS. For the analysis, we used transfer function calculations in the low-frequency band (0.07-0.15 Hz) to compare BP-CBFV, BP-oxygenated hemoglobin (OxHb), BP-tissue oxygenation index (TOI), CBFV-OxHb, and CBFV-TOI. ETCO2 increased from 37 ± 2 to 44 ± 3 mmHg. The CO2-induced CBFV increase significantly correlated with the OxHb increase (R (2) = 0.526, p < 0.001). Compared with baseline, the mean CO2 administration phase shift (in radians) significantly increased (p < 0.005) from -0.67 ± 0.20 to -0.51 ± 0.25 in the BP-CBFV system, and decreased from 1.21 ± 0.81 to -0.05 ± 0.91 in the CBFV-OxHb system, and from 0.94 ± 1.22 to -0.24 ± 1.0 in the CBFV-TOI system; no change was observed for BP-OxHb (0.38 ± 1.17 to 0.41 ± 1.42). Gain changed significantly only in the BP-CBFV system. The correlation between the ETCO2 change and phase change was higher in the CBFV-OxHb system [r = -0.60; 95% confidence interval (CI): -0.16, -0.84; p < 0.01] than in the BP-CBFV system (r = 0.52; 95% CI: 0.03, 0.08; p < 0.05). The transfer function characterizes the blood flow transition from macro- to micro-circulation by time delay only. The CBFV-OxHb system response with a broader phase shift distribution offers the prospect

  4. CO2 Washout Testing of the REI and EM-ACES Space Suits

    NASA Technical Reports Server (NTRS)

    Mitchell, Kathryn C.; Norcross, Jason

    2012-01-01

    When a space suit is used during ground testing, adequate carbon dioxide (CO2) washout must be provided for the suited subject. Symptoms of acute CO2 exposure depend on partial pressure of CO2 (ppCO2), metabolic rate of the subject, and other factors. This test was done to characterize inspired oronasal ppCO2 in the Rear Entry I-Suit (REI) and the Enhanced Mobility Advanced Crew Escape Suit (EM-ACES) for a range of workloads and flow rates for which ground testing is nominally performed. Three subjects were tested in each suit. In all but one case, each subject performed the test twice. Suit pressure was maintained at 4.3 psid. Subjects wore the suit while resting, performing arm ergometry, and walking on a treadmill to generate metabolic workloads of about 500 to 3000 BTU/hr. Supply airflow was varied between 6, 5, and 4 actual cubic feet per minute (ACFM) at each workload. Subjects wore an oronasal mask with an open port in front of the mouth and were allowed to breathe freely. Oronasal ppCO2 was monitored in real time by gas analyzers with sampling tubes connected to the mask. Metabolic rate was calculated from the total CO2 production measured by an additional gas analyzer at the suit air outlet. Real-time metabolic rate was used to adjust the arm ergometer or treadmill workload to meet target metabolic rates. In both suits, inspired CO2 was affected mainly by the metabolic rate of the subject: increased metabolic rate significantly (P < 0.05) increased inspired ppCO2. Decreased air flow caused small increases in inspired ppCO2. The effect of flow was more evident at metabolic rates . 2000 BTU/hr. CO2 washout values of the EM-ACES were slightly but not significantly better than those of the REI suit. Regression equations were developed for each suit to predict the mean inspired ppCO2 as a function of metabolic rate and suit flow rate. This paper provides detailed descriptions of the test hardware, methodology, and results as well as implications for future

  5. Abiotic ozone and oxygen in atmospheres similar to prebiotic Earth

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

    Domagal-Goldman, Shawn D.; Segura, Antígona; Claire, Mark W.

    The search for life on planets outside our solar system will use spectroscopic identification of atmospheric biosignatures. The most robust remotely detectable potential biosignature is considered to be the detection of oxygen (O{sub 2}) or ozone (O{sub 3}) simultaneous to methane (CH{sub 4}) at levels indicating fluxes from the planetary surface in excess of those that could be produced abiotically. Here we use an altitude-dependent photochemical model with the enhanced lower boundary conditions necessary to carefully explore abiotic O{sub 2} and O{sub 3} production on lifeless planets with a wide variety of volcanic gas fluxes and stellar energy distributions. Onmore » some of these worlds, we predict limited O{sub 2} and O{sub 3} buildup, caused by fast chemical production of these gases. This results in detectable abiotic O{sub 3} and CH{sub 4} features in the UV-visible, but no detectable abiotic O{sub 2} features. Thus, simultaneous detection of O{sub 3} and CH{sub 4} by a UV-visible mission is not a strong biosignature without proper contextual information. Discrimination between biological and abiotic sources of O{sub 2} and O{sub 3} is possible through analysis of the stellar and atmospheric context—particularly redox state and O atom inventory—of the planet in question. Specifically, understanding the spectral characteristics of the star and obtaining a broad wavelength range for planetary spectra should allow more robust identification of false positives for life. This highlights the importance of wide spectral coverage for future exoplanet characterization missions. Specifically, discrimination between true and false positives may require spectral observations that extend into infrared wavelengths and provide contextual information on the planet's atmospheric chemistry.« less

  6. 40 CFR 75.13 - Specific provisions for monitoring CO 2 emissions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... the general operating requirements in § 75.10 for a CO2 continuous emission monitoring system and flow... specified in §§ 75.11(a) through (e) or § 75.16, except that the phrase “CO2 continuous emission monitoring system” shall apply rather than “SO2 continuous emission monitoring system,” the phrase “CO2...

  7. 40 CFR 75.13 - Specific provisions for monitoring CO 2 emissions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... the general operating requirements in § 75.10 for a CO2 continuous emission monitoring system and flow... specified in §§ 75.11(a) through (e) or § 75.16, except that the phrase “CO2 continuous emission monitoring system” shall apply rather than “SO2 continuous emission monitoring system,” the phrase “CO2...

  8. Metabolite pools and carbon flow during C4 photosynthesis in maize: 13CO2 labeling kinetics and cell type fractionation.

    PubMed

    Arrivault, Stéphanie; Obata, Toshihiro; Szecówka, Marek; Mengin, Virginie; Guenther, Manuela; Hoehne, Melanie; Fernie, Alisdair R; Stitt, Mark

    2017-01-01

    Worldwide efforts to engineer C 4 photosynthesis into C 3 crops require a deep understanding of how this complex pathway operates. CO 2 is incorporated into four-carbon metabolites in the mesophyll, which move to the bundle sheath where they are decarboxylated to concentrate CO 2 around RuBisCO. We performed dynamic 13 CO 2 labeling in maize to analyze C flow in C 4 photosynthesis. The overall labeling kinetics reflected the topology of C 4 photosynthesis. Analyses of cell-specific labeling patterns after fractionation to enrich bundle sheath and mesophyll cells revealed concentration gradients to drive intercellular diffusion of malate, but not pyruvate, in the major CO 2 -concentrating shuttle. They also revealed intercellular concentration gradients of aspartate, alanine, and phosphenolpyruvate to drive a second phosphoenolpyruvate carboxykinase (PEPCK)-type shuttle, which carries 10-14% of the carbon into the bundle sheath. Gradients also exist to drive intercellular exchange of 3-phosphoglycerate and triose-phosphate. There is rapid carbon exchange between the Calvin-Benson cycle and the CO 2 -concentrating shuttle, equivalent to ~10% of carbon gain. In contrast, very little C leaks from the large pools of metabolites in the C concentration shuttle into respiratory metabolism. We postulate that the presence of multiple shuttles, alongside carbon transfer between them and the Calvin-Benson cycle, confers great flexibility in C 4 photosynthesis. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  9. Stomata Prioritize Their Responses to Multiple Biotic and Abiotic Signal Inputs

    PubMed Central

    Chen, Peilei; Qiu, Muqing; Jiang, Kun; Wang, Genxuan

    2014-01-01

    Stomata are microscopic pores in leaf epidermis that regulate gas exchange between plants and the environment. Being natural openings on the leaf surface, stomata also serve as ports for the invasion of foliar pathogenic bacteria. Each stomatal pore is enclosed by a pair of guard cells that are able to sense a wide spectrum of biotic and abiotic stresses and respond by precisely adjusting the pore width. However, it is not clear whether stomatal responses to simultaneously imposed biotic and abiotic signals are mutually dependent on each other. Here we show that a genetically engineered Escherichia coli strain DH5α could trigger stomatal closure in Vicia faba, an innate immune response that might depend on NADPH oxidase-mediated ROS burst. DH5α-induced stomatal closure could be abolished or disguised under certain environmental conditions like low [CO2], darkness, and drought, etc. Foliar spraying of high concentrations of ABA could reduce stomatal aperture in high humidity-treated faba bean plants. Consistently, the aggressive multiplication of DH5α bacteria in Vicia faba leaves under high humidity could be alleviated by exogenous application of ABA. Our data suggest that a successful colonization of bacteria on the leaf surface is correlated with stomatal aperture regulation by a specific set of environmental factors. PMID:25003527

  10. Analysis of global gene expression in Brachypodium distachyon reveals extensive network plasticity in response to abiotic stress.

    PubMed

    Priest, Henry D; Fox, Samuel E; Rowley, Erik R; Murray, Jessica R; Michael, Todd P; Mockler, Todd C

    2014-01-01

    Brachypodium distachyon is a close relative of many important cereal crops. Abiotic stress tolerance has a significant impact on productivity of agriculturally important food and feedstock crops. Analysis of the transcriptome of Brachypodium after chilling, high-salinity, drought, and heat stresses revealed diverse differential expression of many transcripts. Weighted Gene Co-Expression Network Analysis revealed 22 distinct gene modules with specific profiles of expression under each stress. Promoter analysis implicated short DNA sequences directly upstream of module members in the regulation of 21 of 22 modules. Functional analysis of module members revealed enrichment in functional terms for 10 of 22 network modules. Analysis of condition-specific correlations between differentially expressed gene pairs revealed extensive plasticity in the expression relationships of gene pairs. Photosynthesis, cell cycle, and cell wall expression modules were down-regulated by all abiotic stresses. Modules which were up-regulated by each abiotic stress fell into diverse and unique gene ontology GO categories. This study provides genomics resources and improves our understanding of abiotic stress responses of Brachypodium.

  11. Influence of CO2 on the long-term chemomechanical behavior of an oolitic limestone

    NASA Astrophysics Data System (ADS)

    Grgic, D.

    2011-07-01

    In order to study the long-term mechanical and petrographical evolutions of a carbonate rock (oolitic limestone) during storage of CO2, CO2 injection tests were performed in triaxial cells at temperature and mechanical stresses (isotropic and deviatoric) corresponding to the depth of the Dogger carbonate reservoirs of the Paris basin (˜800 m). We used a specific "flow-through" triaxial cell which allowed us to measure very low strain rates in both axial and lateral directions, while ensuring the sealing of the samples during the injection of CO2. Under isotropic loading, neither the dynamic percolation (i.e., flow-through tests) of dry supercritical/gaseous CO2, nor the diffusion of CO2, into initially saturated samples was shown to produce significant axial compaction and calcite dissolution. Indeed, even though the interstitial aqueous fluid becomes acidic, the progressive increase in dissolved species induces the H2O-CO2-calcite re-equilibrium. The dynamic injection of CO2-saturated solution induced significant axial compaction due to the dissolution of calcite at the sample/piston interface only under open flow conditions (i.e., the injected acidic solution is continuously renewed). Under closed flow conditions (i.e., acidic solution recirculation or no-flow conditions) which reproduce the physicochemical conditions of CO2 storage at the field scale better, the rapid H2O-CO2-calcite re-equilibrium inhibits calcite dissolution. Under deviatoric loading and closed conditions, the diffusion of CO2 induced a very small increase in the PSC (pressure solution creep) process which was stopped by the H2O-CO2-calcite re-equilibrium inside the sample. Therefore, a significant compaction of limestone samples was obtained only under open conditions and is mainly due to a purely chemical mechanism (calcite dissolution), while the contribution of the chemo-mechanical mechanism (PSC) was found to not be of any great importance. In the context of massive injection of CO2 at

  12. Catholyte-Free Electrocatalytic CO2 Reduction to Formate.

    PubMed

    Lee, Wonhee; Kim, Young Eun; Youn, Min Hye; Jeong, Soon Kwan; Park, Ki Tae

    2018-04-16

    Electrochemical reduction of carbon dioxide (CO 2 ) into value-added chemicals is a promising strategy to reduce CO 2 emission and mitigate climate change. One of the most serious problems in electrocatalytic CO 2 reduction (CO 2 R) is the low solubility of CO 2 in an aqueous electrolyte, which significantly limits the cathodic reaction rate. This paper proposes a facile method of catholyte-free electrocatalytic CO 2 reduction to avoid the solubility limitation using commercial tin nanoparticles as a cathode catalyst. Interestingly, as the reaction temperature rises from 303 K to 363 K, the partial current density (PCD) of formate improves more than two times with 52.9 mA cm -2 , despite the decrease in CO 2 solubility. Furthermore, a significantly high formate concentration of 41.5 g L -1 is obtained as a one-path product at 343 K with high PCD (51.7 mA cm -2 ) and high Faradaic efficiency (93.3 %) via continuous operation in a full flow cell at a low cell voltage of 2.2 V. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. SUBTASK 2.19 – OPERATIONAL FLEXIBILITY OF CO2 TRANSPORT AND STORAGE

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

    Jensen, Melanie; Schlasner, Steven; Sorensen, James

    2014-12-31

    Carbon dioxide (CO2) is produced in large quantities during electricity generation and by industrial processes. These CO2 streams vary in terms of both composition and mass flow rate, sometimes substantially. The impact of a varying CO2 stream on pipeline and storage operation is not fully understood in terms of either operability or infrastructure robustness. This study was performed to summarize basic background from the literature on the topic of operational flexibility of CO2 transport and storage, but the primary focus was on compiling real-world lessons learned about flexible operation of CO2 pipelines and storage from both large-scale field demonstrations andmore » commercial operating experience. Modeling and pilot-scale results of research in this area were included to illustrate some of the questions that exist relative to operation of carbon capture and storage (CCS) projects with variable CO2 streams. It is hoped that this report’s real-world findings provide readers with useful information on the topic of transport and storage of variable CO2 streams. The real-world results were obtained from two sources. The first source consisted of five full-scale, commercial transport–storage projects: Sleipner, Snøhvit, In Salah, Weyburn, and Illinois Basin–Decatur. These scenarios were reviewed to determine the information that is available about CO2 stream variability/intermittency on these demonstration-scale projects. The five projects all experienced mass flow variability or an interruption in flow. In each case, pipeline and/or injection engineers were able to accommodate any issues that arose. Significant variability in composition has not been an issue at these five sites. The second source of real- world results was telephone interviews conducted with experts in CO2 pipeline transport, injection, and storage during which commercial anecdotal information was acquired to augment that found during the literature search of the five full

  14. Micro-PIV Study of Supercritical CO2-Water Interactions in Porous Micromodels

    NASA Astrophysics Data System (ADS)

    Kazemifar, Farzan; Blois, Gianluca; Christensen, Kenneth T.

    2015-11-01

    Multiphase flow of immiscible fluids in porous media is encountered in numerous natural systems and engineering applications such as enhanced oil recovery (EOR), and CO2 sequestration among others. Geological sequestration of CO2 in saline aquifers has emerged as a viable option for reducing CO2 emissions, and thus it has been the subject of numerous studies in recent years. A key objective is improving the accuracy of numerical models used for field-scale simulations by incorporation/better representation of the pore-scale flow physics. This necessitates experimental data for developing, testing and validating such models. We have studied drainage and imbibition processes in a homogeneous, two-dimensional porous micromodel with CO2 and water at reservoir-relevant conditions. Microscopic particle image velocimetry (micro-PIV) technique was applied to obtain spatially- and temporally-resolved velocity vector fields in the aqueous phase. The results provide new insight into the flow processes at the pore scale.

  15. Abiotic and biotic dynamics during the initial stages of high solids switchgrass degradation.

    PubMed

    Fontenelle, L T; Corgie, S C; Walker, L P

    2011-07-01

    An understanding of the underlying dynamics of how biotic variables drive changes in abiotic parameters in the early stages of biomass biodegradation is essential for better control of the process. Probe hybridization was used to quantitatively study the growth of bacteria, yeast and fungi for three levels of initial moisture content (60, 65 and 75% MC) over a period of 64 h. Changes in abiotic parameters were also documented. By 64 h, samples were significantly differentiated both in temporal and spatial dimension, proving that considerable changes had occurred in these initial stages. Maximum carbon (C) conversion occurred in the 75% MC reactor at a peak value of 49%, with 40% and 37% in the 65 and 60% MC reactors, respectively. Higher temperature, higher pH, higher rates of O2 consumption and CO2 evolution were also observed in the highest moisture reactor; suggesting that of the three MCs studied, 75% MC was the optimal one for the process. MC during the process also proved to be important because it greatly influenced variation in the spatial dimension, further underscoring the importance of characterizing changes with bed height. Most importantly, we were able to positively correlate the rate of substrate degradation with bacterial biomass levels and highlight the critical role of bacteria in biological decomposition.

  16. Modelling of Seismic and Resistivity Responses during the Injection of CO2 in Sandstone Reservoir

    NASA Astrophysics Data System (ADS)

    Omar, Muhamad Nizarul Idhafi Bin; Almanna Lubis, Luluan; Nur Arif Zanuri, Muhammad; Ghosh, Deva P.; Irawan, Sonny; Regassa Jufar, Shiferaw

    2016-07-01

    Enhanced oil recovery plays vital role in production phase in a producing oil field. Initially, in many cases hydrocarbon will naturally flow to the well as respect to the reservoir pressure. But over time, hydrocarbon flow to the well will decrease as the pressure decrease and require recovery method so called enhanced oil recovery (EOR) to recover the hydrocarbon flow. Generally, EOR works by injecting substances, such as carbon dioxide (CO2) to form a pressure difference to establish a constant productive flow of hydrocarbon to production well. Monitoring CO2 performance is crucial in ensuring the right trajectory and pressure differences are established to make sure the technique works in recovering hydrocarbon flow. In this paper, we work on computer simulation method in monitoring CO2 performance by seismic and resistivity model, enabling geoscientists and reservoir engineers to monitor production behaviour as respect to CO2 injection.

  17. 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

  18. CO2 hydrogenation on a metal hydride surface.

    PubMed

    Kato, Shunsuke; Borgschulte, Andreas; Ferri, Davide; Bielmann, Michael; Crivello, Jean-Claude; Wiedenmann, Daniel; Parlinska-Wojtan, Magdalena; Rossbach, Peggy; Lu, Ye; Remhof, Arndt; Züttel, Andreas

    2012-04-28

    The catalytic hydrogenation of CO(2) at the surface of a metal hydride and the corresponding surface segregation were investigated. The surface processes on Mg(2)NiH(4) were analyzed by in situ X-ray photoelectron spectroscopy (XPS) combined with thermal desorption spectroscopy (TDS) and mass spectrometry (MS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS). CO(2) hydrogenation on the hydride surface during hydrogen desorption was analyzed by catalytic activity measurement with a flow reactor, a gas chromatograph (GC) and MS. We conclude that for the CO(2) methanation reaction, the dissociation of H(2) molecules at the surface is not the rate controlling step but the dissociative adsorption of CO(2) molecules on the hydride surface. This journal is © the Owner Societies 2012

  19. Physical Activation of Oil Palm Empty Fruit Bunch via CO2 Activation Gas for CO2 Adsorption

    NASA Astrophysics Data System (ADS)

    Joseph, C. G.; Quek, K. S.; Daud, W. M. A. W.; Moh, P. Y.

    2017-06-01

    In this study, different parameters for the preparation of activated carbon were investigated for their yield and CO2 capture capabilities. The activated carbon was prepared from Oil Palm Empty Fruit Bunch (OPEFB) via a 2-step physical activation process. The OPEFB was pyrolyzed under inert conditions at 500 °C and activated via CO2. A 2-factorial design was employed and the effects of activation temperature, activation dwell time and gas flow rate on yield and CO2 capture capabilities were compared and studied. The yield obtained ranged from between 20 - 26, whereby the temperature was determined to be the most significant factor in influencing CO2 uptake. The CO2 capture capacity was determined using Temperature Programmed Desorption (TPD) technique. The CO2 uptake of EFB activated carbon achieved was between 1.85 - 2.09 mmol/g. TPD analysis has shown that the surface of AC were of basic nature. AC was found to be able to withhold the CO2 up to 663°C before maximum desorption occurs. The surface area and pore size of OPEFB obtained from BET analysis is 2.17 m2 g-1 and 0.01 cm3 g-1. After activation, both surface area and pore size increased with a maximum observed surface area and pore size of 548.07 m2 g-1 and 0.26 cm3 g-1. Surface morphology, functional groups, pore size and surface area were analyzed using SEM, FT-IR, TPD and BET.

  20. Nanoscale Controls on CO2-water-rock Interactions in Saline Reservoirs

    NASA Astrophysics Data System (ADS)

    Deyoreo, J.; Depaolo, D. J.

    2009-12-01

    It is becoming increasingly widely recognized that geologic sequestration of CO2, when combined with economical means of capture, may be one of the most effective approaches to reducing net CO2 emissions to the atmosphere over the next century. Injection of CO2 into saline geologic formations involves forcing a buoyant, low-viscosity fluid into a more dense, higher viscosity fluid. The difference in wetting properties of the two fluids, their partial miscibility, the fact that CO2 and H2O form an acid, and the heterogeneity of geologic formations combine to make the flow and transport details fascinating but difficult to fully characterize and predict. A major question is whether the flow of CO2 into subsurface formations, the efficiency of pore space filling, and the trapping efficiency can be not only predicted but controlled over the decades of injection that might be associated with the life of a power plant. The major technological gaps to controlling and ultimately sequestering subsurface CO2 can be traced to far-from-equilibrum processes that originate at the molecular and nanoscale, but are expressed as complex emergent behavior at larger scales. Essential knowledge gaps involve the effects of nanoscale confinement on material properties, flow and chemical reactions, the effects of nanoparticles, mineral surface dynamics, and microbiota on mineral dissolution/precipitation and fluid flow, and the dynamics of fluid-fluid and fluid-mineral interfaces. To address these scientific and technical challenges, the Energy Frontier Research Center recently established, involving collaboration between LBNL, ORNL, MIT, UC Berkeley, UC Davis and LLNL, will attempt to bring new approaches to the study of nanoscale phenomena in fluid-rock systems to bear on the problem of CO2 behavior in saline formations. The stated goal is to use molecular, nanoscale, and pore-network scale approaches to control flow, dissolution, and precipitation in deep subsurface rock formations to

  1. 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).

  2. Oscillations and patterns in a model of simultaneous CO and C2H2 oxidation and NO(x) reduction in a cross-flow reactor.

    PubMed

    Hadač, Otto; Kohout, Martin; Havlica, Jaromír; Schreiber, Igor

    2015-03-07

    A model describing simultaneous catalytic oxidation of CO and C2H2 and reduction of NOx in a cross-flow tubular reactor is explored with the aim of relating spatiotemporal patterns to specific pathways in the mechanism. For that purpose, a detailed mechanism proposed for three-way catalytic converters is split into two subsystems, (i) simultaneous oxidation of CO and C2H2, and (ii) oxidation of CO combined with NOx reduction. The ability of these two subsystems to display mechanism-specific dynamical effects is studied initially by neglecting transport phenomena and applying stoichiometric network and bifurcation analyses. We obtain inlet temperature - inlet oxygen concentration bifurcation diagrams, where each region possessing specific dynamics - oscillatory, bistable and excitable - is associated with a dominant reaction pathway. Next, the spatiotemporal behaviour due to reaction kinetics combined with transport processes is studied. The observed spatiotemporal patterns include phase waves, travelling fronts, pulse waves and spatiotemporal chaos. Although these types of pattern occur generally when the kinetic scheme possesses autocatalysis, we find that some of their properties depend on the underlying dominant reaction pathway. The relation of patterns to specific reaction pathways is discussed.

  3. Impacts of relative permeability on CO2 phase behavior, phase distribution, and trapping mechanisms

    NASA Astrophysics Data System (ADS)

    Moodie, N.; McPherson, B. J. O. L.; Pan, F.

    2015-12-01

    A critical aspect of geologic carbon storage, a carbon-emissions reduction method under extensive review and testing, is effective multiphase CO2 flow and transport simulation. Relative permeability is a flow parameter particularly critical for accurate forecasting of multiphase behavior of CO2 in the subsurface. The relative per­meability relationship assumed and especially the irreducible saturation of the gas phase greatly impacts predicted CO2 trapping mechanisms and long-term plume migration behavior. A primary goal of this study was to evaluate the impact of relative permeability on efficacy of regional-scale CO2 sequestration models. To accomplish this we built a 2-D vertical cross-section of the San Rafael Swell area of East-central Utah. This model simulated injection of CO2 into a brine aquifer for 30 years. The well was then shut-in and the CO2 plume behavior monitored for another 970 years. We evaluated five different relative permeability relationships to quantify their relative impacts on forecasted flow results of the model, with all other parameters maintained uniform and constant. Results of this analysis suggest that CO2 plume movement and behavior are significantly dependent on the specific relative permeability formulation assigned, including the assumed irreducible saturation values of CO2 and brine. More specifically, different relative permea­bility relationships translate to significant differences in CO2 plume behavior and corresponding trapping mechanisms.

  4. Constraining the role of iron in environmental nitrogen transformations. Dual stable isotope systematics of abiotic NO 2- reduction by Fe(II) and its production of N 2O

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

    Johnston, David; Wankel, Scott David; Buchwald, Carolyn

    Redox reactions involving nitrogen and iron have been shown to have important implications for mobilization of priority contaminants. Thus, an understanding of the linkages between their biogeochemical cycling is critical for predicting subsurface mobilization of radionuclides such as uranium. Despite mounting evidence for biogeochemical interactions between iron and nitrogen, our understanding of their environmental importance remains limited. Here we present an investigation of abiotic nitrite (NO 2 -) reduction by Fe(II) or ‘chemodenitrification,’ and its relevance to the production of nitrous oxide (N 2O), specifically focusing on dual (N and O) isotope systematics under a variety of environmentally relevant conditions.more » We observe a range of kinetic isotope effects that are regulated by reaction rates, with faster rates at higher pH (~8), higher concentrations of Fe(II) and in the presence of mineral surfaces. A clear non-linear relationship between rate constant and kinetic isotope effects of NO 2 - reduction was evident (with larger isotope effects at slower rates) and is interpreted as reflecting the dynamics of Fe(II)-N reaction intermediates. N and O isotopic composition of product N 2O also suggests a complex network of parallel and/or competing pathways. Our findings suggest that NO 2 - reduction by Fe(II) may represent an important abiotic source of environmental N 2O, especially in iron-rich environments experiencing dynamic redox variations. This study provides a multi-compound, multi-isotope framework for evaluating the environmental occurrence of abiotic NO 2 - reduction and N 2O formation, helping future studies constrain the relative roles of abiotic and biological N 2O production pathways.« less

  5. Relationships between the Efficiencies of Photosystems I and II and Stromal Redox State in CO(2)-Free Air : Evidence for Cyclic Electron Flow in Vivo.

    PubMed

    Harbinson, J; Foyer, C H

    1991-09-01

    The responses of the efficiencies of photosystems I and II, stromal redox state (as indicated by NADP-malate dehydrogenase activation state), and activation of the Benson-Calvin cycle enzymes ribulose 1,5-bisphosphate carboxylase and fructose 1,6-bisphosphatase to varying irradiance were measured in pea (Pisum sativum L.) leaves operating close to the CO(2) compensation point. A comparison of the relationships among these parameters obtained from leaves in air was made with those obtained when the leaves were maintained in air from which the CO(2) had been removed. P700 was more oxidized at any measured irradiance in CO(2)-free air than in air. The relationship between the quantum efficiencies of the photosystems in CO(2)-free air was distinctly curvilinear in contrast to the predominantly linear relationship obtained with leaves in air. This nonlinearity may be consistent with the operation of cyclic electron flow around photosystem I because the quantum efficiency of photosystem II was much more restricted than the quantum efficiency of photosystem I. In CO(2)-free air, measured NADP-malate dehydrogenase activities varied considerably at low irradiances. However, at high irradiance the activity of the enzyme was low, implying that the stroma was oxidized. In contrast, fructose-1,6-bisphosphatase activities tended to increase with increasing electron flux through the photosystems. Ribulose-1,5-bisphosphate carboxylase activity remained relatively constant with respect to irradiance in CO(2)-free air, with an activation state 50% of maximum. We conclude that, at the CO(2) compensation point and high irradiance, low redox states are favored and that cyclic electron flow may be substantial. These two features may be the requirements necessary to trigger and maintain the dissipative processes in the thylakoid membrane.

  6. Integrity of Pre-existing Wellbores in Geological Sequestration of CO 2 – Assessment Using a Coupled Geomechanics-fluid Flow Model

    DOE PAGES

    Kelkar, Sharad; Carey, J. William; Dempsey, David; ...

    2014-12-31

    Assessment of potential CO 2 and brine leakage from wellbores is central to any consideration of the viability of geological CO 2 sequestration. Depleted oil and gas reservoirs are some of the potential candidates for consideration as sequestration sites. The sequestration sites are expected to cover laterally extensive areas to be of practical interest. Hence there is a high likelihood that such sites will contain many pre-existing abandoned wells. Most existing work on wellbore integrity has focused on field and laboratory studies of chemical reactivity. Very little work has been done on the impacts of mechanical stresses on wellbore performance.more » This study focuses on the potential enhancement of fluid flow pathways in the near-wellbore environment due to modifications in the geomechanical stress field resulting from the CO 2 injection operations. The majority of the operational scenarios for CO 2 sequestration lead to significant rise in the formation pore pressure. This is expected to lead to an expansion of the reservoir rock and build-up of shear stresses near wellbores where the existence of cement and casing are expected to constrain the expansion. If the stress buildup is large enough, this can lead to failure with attendant permeability enhancement that can potentially provide leakage pathways to shallower aquifers and the surface. In this study, we use a numerical model to simulate key features of a wellbore (casing, annulus and cement) embedded in a system that includes the upper aquifer, caprock, and storage aquifer. We present the sensitivity of damage initiation and propagation to various operational and formation parameters. We consider Mohr-Coulomb shear-failure models; tensile failure is also likely to occur but will require higher stress changes and will be preceded by shear failure. The modeling is performed using the numerical simulator FEHM developed at LANL that models coupled THM processes during multi-phase fluid flow and

  7. 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.

  8. Predicting macropores in space and time by earthworms and abiotic controls

    NASA Astrophysics Data System (ADS)

    Hohenbrink, Tobias Ludwig; Schneider, Anne-Kathrin; Zangerlé, Anne; Reck, Arne; Schröder, Boris; van Schaik, Loes

    2017-04-01

    Macropore flow increases infiltration and solute leaching. The macropore density and connectivity, and thereby the hydrological effectiveness, vary in space and time due to earthworms' burrowing activity and their ability to refill their burrows in order to survive drought periods. The aim of our study was to predict the spatiotemporal variability of macropore distributions by a set of potentially controlling abiotic variables and abundances of different earthworm species. We measured earthworm abundances and effective macropore distributions using tracer rainfall infiltration experiments in six measurement campaigns during one year at six field sites in Luxembourg. Hydrologically effective macropores were counted in three soil depths (3, 10, 30 cm) and distinguished into three diameter classes (<2, 2-6, >6 mm). Earthworms were sampled and determined to species-level. In a generalized linear modelling framework, we related macropores to potential spatial and temporal controlling factors. Earthworm species such as Lumbricus terrestris and Aporrectodea longa, local abiotic site conditions (land use, TWI, slope), temporally varying weather conditions (temperature, humidity, precipitation) and soil moisture affected the number of effective macropores. Main controlling factors and explanatory power of the models (uncertainty and model performance) varied depending on the depth and diameter class of macropores. We present spatiotemporal predictions of macropore density by daily-resolved, one year time series of macropore numbers and maps of macropore distributions at specific dates in a small-scale catchment with 5 m resolution.

  9. Injectivity Evaluation for Offshore CO 2 Sequestration in Marine Sediments

    DOE PAGES

    Dai, Zhenxue; Zhang, Ye; Stauffer, Philip; ...

    2017-08-18

    Global and regional climate change caused by greenhouse gases emissions has stimulated interest in developing various technologies (such as carbon dioxide (CO 2) geologic sequestration in brine reservoirs) to reduce the concentrations of CO 2 in the atmosphere. Our study develops a statistical framework to identify gravitational CO 2 trapping processes and to quantitatively evaluate both CO 2 injectivity (or storage capacity) and leakage potential from marine sediments which exhibit heterogeneous permeability and variable thicknesses. Here, we focus on sets of geostatistically-based heterogeneous models populated with fluid flow parameters from several reservoir sites in the U.S. Gulf of Mexico (GOM).more » A computationally efficient uncertainty quantification study was conducted with results suggesting that permeability heterogeneity and anisotropy, seawater depth, and sediment thickness can all significantly impact CO 2 flow and trapping. Large permeability/porosity heterogeneity can enhance gravitational, capillary, and dissolution trapping, which acts to deter CO 2 upward migration and subsequent leakage onto the seafloor. When log permeability variance is 5, self-sealing with heterogeneity-enhanced gravitation trapping can be achieved even when water depth is 1.2 km. This extends the previously identified self-sealing condition that water depth be greater than 2.7 km. Our results have yielded valuable insight into the conditions under which safe storage of CO 2 can be achieved in offshore environments. The developed statistical framework is general and can be adapted to study other offshore sites worldwide.« less

  10. Injectivity Evaluation for Offshore CO 2 Sequestration in Marine Sediments

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

    Dai, Zhenxue; Zhang, Ye; Stauffer, Philip

    Global and regional climate change caused by greenhouse gases emissions has stimulated interest in developing various technologies (such as carbon dioxide (CO 2) geologic sequestration in brine reservoirs) to reduce the concentrations of CO 2 in the atmosphere. Our study develops a statistical framework to identify gravitational CO 2 trapping processes and to quantitatively evaluate both CO 2 injectivity (or storage capacity) and leakage potential from marine sediments which exhibit heterogeneous permeability and variable thicknesses. Here, we focus on sets of geostatistically-based heterogeneous models populated with fluid flow parameters from several reservoir sites in the U.S. Gulf of Mexico (GOM).more » A computationally efficient uncertainty quantification study was conducted with results suggesting that permeability heterogeneity and anisotropy, seawater depth, and sediment thickness can all significantly impact CO 2 flow and trapping. Large permeability/porosity heterogeneity can enhance gravitational, capillary, and dissolution trapping, which acts to deter CO 2 upward migration and subsequent leakage onto the seafloor. When log permeability variance is 5, self-sealing with heterogeneity-enhanced gravitation trapping can be achieved even when water depth is 1.2 km. This extends the previously identified self-sealing condition that water depth be greater than 2.7 km. Our results have yielded valuable insight into the conditions under which safe storage of CO 2 can be achieved in offshore environments. The developed statistical framework is general and can be adapted to study other offshore sites worldwide.« less

  11. Real-time breath gas analysis of CO and CO2 using an EC-QCL

    NASA Astrophysics Data System (ADS)

    Ghorbani, Ramin; Schmidt, Florian M.

    2017-05-01

    Real-time breath gas analysis is a promising, non-invasive tool in medical diagnostics, and well-suited to investigate the physiology of carbon monoxide (CO), a potential biomarker for oxidative stress and respiratory diseases. A sensor for precise, breath-cycle resolved, simultaneous detection of exhaled CO (eCO) and carbon dioxide (eCO2) was developed based on a continuous wave, external-cavity quantum cascade laser (EC-QCL), a low-volume multi-pass cell and wavelength modulation spectroscopy. The system achieves a noise-equivalent (1σ) sensitivity of 8.5 × 10-8 cm-1 Hz-1/2 and (2σ) detection limits of 9 ± 2 ppbv and 650 ± 7 ppmv at 0.14 s spectrum acquisition time for CO and CO2, respectively. Integration over 15 s yields a precision of 0.6 ppbv for CO. The fact that the eCO2 expirograms measured by capnography and laser spectroscopy have essentially identical shape confirms true real-time detection. It is found that the individual eCO exhalation profiles from healthy non-smokers have a slightly different shape than the eCO2 profiles and exhibit a clear dependence on exhalation flow rate and breath-holding time. Detection of indoor air CO and broadband breath profiling across the 93 cm-1 mode-hop-free tuning range of the EC-QCL are also demonstrated.

  12. Negative CO2 emissions via subsurface mineral carbonation in fractured peridotite

    NASA Astrophysics Data System (ADS)

    Kelemen, P. B.; Matter, J.

    2014-12-01

    Uptake of CO2 from surface water via mineral carbonation in peridotite can be engineered to achieve negative CO2 emissions. Reaction with peridotite, e.g., CO2 + olivine (A), serpentine (B) and brucite (C), forms inert, non-toxic, solid carbonates such as magnesite. Experimental studies show that A can be 80% complete in a few hours with 30 micron powders and elevated P(CO2) [1,2,3]. B is slower, but in natural systems the rate of B+C is significant [4]. Methods for capture of dilute CO2 via mineral carbonation [4,5,6,7] are not well known, though CO2 storage via mineral carbonation has been discussed for decades [8,9]. Where crushed peridotite is available, as in mine tailings, increased air or water flow could enhance CO2 uptake at a reasonable cost [4,5]. Here we focus on enhancing subsurface CO2 uptake from surface water flowing in fractured peridotite, in systems driven by thermal convection such as geothermal power plants. Return of depleted water to the surface would draw down CO2 from the air [6,7]. CO2 uptake from water, rate limited by flow in input and output wells, could exceed 1000 tons CO2/yr [7]. If well costs minus power sales were 0.1M to 1M and each system lasts 10 years this costs < 10 to 100 per ton CO2. As for other CCS methods, upscaling requires infrastructure resembling the oil industry. Uptake of 1 Gt CO2/yr at 1000 t/well/yr requires 1M wells, comparable to the number of producing oil and gas wells in the USA. Subsurface CO2 uptake could first be applied in coastal, sub-seafloor peridotite with onshore drilling. Sub-seafloor peridotite is extensive off Oman, New Caledonia and Papua New Guinea, with smaller amounts off Spain, Morocco, USA, etc. This would be a regional contribution, used in parallel with other methods elsewhere. To achieve larger scale is conceivable. There is a giant mass of seafloor peridotite along slow-spreading mid-ocean ridges. Could robotic drills enhance CO2 uptake at a reasonable cost, while fabric chimneys

  13. MICROSCALE METABOLIC, REDOX AND ABIOTIC REACTIONS IN HANFORD 300 AREA SUBSURFACE SEDIMENTS

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

    Beyenal, Haluk; McLEan, Jeff; Majors, Paul

    2013-11-14

    The Hanford 300 Area is a unique site due to periodic hydrologic influence of river water resulting in changes in groundwater elevation and flow direction. This area is also highly subject to uranium remobilization, the source of which is currently believed to be the region at the base of the vadose zone that is subject to period saturation due to the changes in the water levels in the Columbia River. We found that microbial processes and redox and abiotic reactions which operate at the microscale were critical to understanding factors controlling the macroscopic fate and transport of contaminants in themore » subsurface. The combined laboratory and field research showed how microscale conditions control uranium mobility and how biotic, abiotic and redox reactions relate to each other. Our findings extended the current knowledge to examine U(VI) reduction and immobilization using natural 300 Area communities as well as selected model organisms on redox-sensitive and redox-insensitive minerals. Using innovative techniques developed specifically to probe biogeochemical processes at the microscale, our research expanded our current understanding of the roles played by mineral surfaces, bacterial competition, and local biotic, abiotic and redox reaction rates on the reduction and immobilization of uranium.« less

  14. CO2 Effects in Space: Relationship to Intracranial Hypertension

    NASA Technical Reports Server (NTRS)

    Alexander, David J.

    2011-01-01

    This slide presentation reviews the effects of enhanced exposure to CO2 on Earth and in space. The effects of enhanced exposure to CO2 are experienced in almost all bodily systems. In space some of the effects are heightened due to the fluid shifts to the thorax and head. This fluid shift results in increased intracranial pressure, congested cerebral circulation, increased Cerebral Blood Flow (CBF) and Intravenous dilatation. The mechanism of the effect of CO2 on CBF is diagrammed, as is the Cerebrospinal Fluid (CSF) production. A listing of Neuroendocrine targets is included.

  15. Dual stable isotopes of CH 4 from Yellowstone hot-springs suggest hydrothermal processes involving magmatic CO 2

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

    Moran, James J.; Whitmore, Laura M.; Jay, Zackary J.

    Volcanism and post-magmatism contribute significant annual methane (CH 4) fluxes to the atmosphere (on par with other natural sources such as forest fire and wild animal emissions) and have been implicated in past climate-change events. The Yellowstone hot spot is one of the largest volcanic systems on Earth and is known to emit CH 4 (as well as carbon dioxide (CO 2) and other gases), but the ultimate sources of this CH 4 flux have not been elucidated. In this paper, we use dual stable isotope analysis (δ 2H and δ 13C) of CH 4 sampled from ten high-temperature geothermalmore » pools in Yellowstone National Park along with other isotopic and gas analyses to evaluate potential sources of methane. The average δ 13C and δ 2H values of CH 4 emitted from hot springs ( 26.7 (± 2.4) and - 236.9 (± 12.0) ‰, respectively) are inconsistent with microbial methanogenesis but do not allow distinction between thermogenic and abiotic sources. Correlation between δ 13C CH4 and δ 13C of dissolved inorganic C (DIC) is consistent with DIC as the parent C source for the observed CH 4, or with equilibration of CH 4 and DIC. Methane formation temperatures estimated by isotopic geothermometry based on δ 13C CH4 and δ 13C CO2 ranged from ~ 250–350 °C, which is just below previous temperature estimates for the hydrothermal reservoir. Further, the δ 2H H2O of the thermal springs and the measured δ 2H CH4 values are consistent with equilibration between the source water and the CH 4 at the formation temperatures. Though the ultimate origin of the CH 4 could be attributed to either abiotic of themorgenic processes with subsequent isotopic equilibration, the C 1/C 2+ composition of the gases is more consistent with abiotic origins for most of the samples. Finally, our data support the hypothesis that subsurface rock-water interactions are responsible for at least a significant fraction of the CH 4 flux from the Yellowstone National Park volcanic system.« less

  16. Dual stable isotopes of CH 4 from Yellowstone hot-springs suggest hydrothermal processes involving magmatic CO 2

    DOE PAGES

    Moran, James J.; Whitmore, Laura M.; Jay, Zackary J.; ...

    2017-05-16

    Volcanism and post-magmatism contribute significant annual methane (CH 4) fluxes to the atmosphere (on par with other natural sources such as forest fire and wild animal emissions) and have been implicated in past climate-change events. The Yellowstone hot spot is one of the largest volcanic systems on Earth and is known to emit CH 4 (as well as carbon dioxide (CO 2) and other gases), but the ultimate sources of this CH 4 flux have not been elucidated. In this paper, we use dual stable isotope analysis (δ 2H and δ 13C) of CH 4 sampled from ten high-temperature geothermalmore » pools in Yellowstone National Park along with other isotopic and gas analyses to evaluate potential sources of methane. The average δ 13C and δ 2H values of CH 4 emitted from hot springs ( 26.7 (± 2.4) and - 236.9 (± 12.0) ‰, respectively) are inconsistent with microbial methanogenesis but do not allow distinction between thermogenic and abiotic sources. Correlation between δ 13C CH4 and δ 13C of dissolved inorganic C (DIC) is consistent with DIC as the parent C source for the observed CH 4, or with equilibration of CH 4 and DIC. Methane formation temperatures estimated by isotopic geothermometry based on δ 13C CH4 and δ 13C CO2 ranged from ~ 250–350 °C, which is just below previous temperature estimates for the hydrothermal reservoir. Further, the δ 2H H2O of the thermal springs and the measured δ 2H CH4 values are consistent with equilibration between the source water and the CH 4 at the formation temperatures. Though the ultimate origin of the CH 4 could be attributed to either abiotic of themorgenic processes with subsequent isotopic equilibration, the C 1/C 2+ composition of the gases is more consistent with abiotic origins for most of the samples. Finally, our data support the hypothesis that subsurface rock-water interactions are responsible for at least a significant fraction of the CH 4 flux from the Yellowstone National Park volcanic system.« less

  17. Wettability impact on supercritical CO2 capillary trapping: Pore-scale visualization and quantification

    NASA Astrophysics Data System (ADS)

    Hu, Ran; Wan, Jiamin; Kim, Yongman; Tokunaga, Tetsu K.

    2017-08-01

    How the wettability of pore surfaces affects supercritical (sc) CO2 capillary trapping in geologic carbon sequestration (GCS) is not well understood, and available evidence appears inconsistent. Using a high-pressure micromodel-microscopy system with image analysis, we studied the impact of wettability on scCO2 capillary trapping during short-term brine flooding (80 s, 8-667 pore volumes). Experiments on brine displacing scCO2 were conducted at 8.5 MPa and 45°C in water-wet (static contact angle θ = 20° ± 8°) and intermediate-wet (θ = 94° ± 13°) homogeneous micromodels under four different flow rates (capillary number Ca ranging from 9 × 10-6 to 8 × 10-4) with a total of eight conditions (four replicates for each). Brine invasion processes were recorded and statistical analysis was performed for over 2000 images of scCO2 saturations, and scCO2 cluster characteristics. The trapped scCO2 saturation under intermediate-wet conditions is 15% higher than under water-wet conditions under the slowest flow rate (Ca ˜ 9 × 10-6). Based on the visualization and scCO2 cluster analysis, we show that the scCO2 trapping process in our micromodels is governed by bypass trapping that is enhanced by the larger contact angle. Smaller contact angles enhance cooperative pore filling and widen brine fingers (or channels), leading to smaller volumes of scCO2 being bypassed. Increased flow rates suppress this wettability effect.

  18. CO and NO2 pollution in a long two-way traffic road tunnel: investigation of NO2/NOx ratio and modelling of NO2 concentration.

    PubMed

    Indrehus, O; Vassbotn, P

    2001-02-01

    The CO, NO and NO2 concentrations, visibility and air flow velocity were measured using continuous analysers in a long Norwegian road tunnel (7.5 km) with traffic in both directions in April 1994 and 1995. The traffic density was monitored at the same time. The NO2 concentration exceeded Norwegian air quality limits for road tunnels 17% of the time in 1994. The traffic through the tunnel decreased from 1994 to 1995, and the mean NO2 concentration was reduced from 0.73 to 0.22 ppm. The ventilation fan control, based on the CO concentration only, was unsatisfactory and the air flow was sometimes low for hours. Models for NO2 concentration based on CO concentration and absolute air flow velocity were developed and tested. The NO2/NOx ratio showed an increase for NOx levels above 2 ppm; a likely explanation for this phenomenon is NO oxidation by O2. Exposure to high NO2 concentrations may represent a health risk for people with respiratory and cardiac diseases. In long road tunnels with two-way traffic, this study indicates that ventilation fan control based on CO concentration should be adjusted for changes in vehicle CO emission and should be supplemented by air flow monitoring to limit the NO2 concentration.

  19. Using Pressure and Volumetric Approaches to Estimate CO2 Storage Capacity in Deep Saline Aquifers

    DOE PAGES

    Thibeau, Sylvain; Bachu, Stefan; Birkholzer, Jens; ...

    2014-12-31

    Various approaches are used to evaluate the capacity of saline aquifers to store CO 2, resulting in a wide range of capacity estimates for a given aquifer. The two approaches most used are the volumetric “open aquifer” and “closed aquifer” approaches. We present four full-scale aquifer cases, where CO 2 storage capacity is evaluated both volumetrically (with “open” and/or “closed” approaches) and through flow modeling. These examples show that the “open aquifer” CO 2 storage capacity estimation can strongly exceed the cumulative CO 2 injection from the flow model, whereas the “closed aquifer” estimates are a closer approximation to themore » flow-model derived capacity. An analogy to oil recovery mechanisms is presented, where the primary oil recovery mechanism is compared to CO 2 aquifer storage without producing formation water; and the secondary oil recovery mechanism (water flooding) is compared to CO 2 aquifer storage performed simultaneously with extraction of water for pressure maintenance. This analogy supports the finding that the “closed aquifer” approach produces a better estimate of CO 2 storage without water extraction, and highlights the need for any CO 2 storage estimate to specify whether it is intended to represent CO 2 storage capacity with or without water extraction.« less

  20. Advanced CO2 Removal and Reduction System

    NASA Technical Reports Server (NTRS)

    Alptekin, Gokhan; Dubovik, Margarita; Copeland, Robert J.

    2011-01-01

    An advanced system for removing CO2 and H2O from cabin air, reducing the CO2, and returning the resulting O2 to the air is less massive than is a prior system that includes two assemblies . one for removal and one for reduction. Also, in this system, unlike in the prior system, there is no need to compress and temporarily store CO2. In this present system, removal and reduction take place within a single assembly, wherein removal is effected by use of an alkali sorbent and reduction is effected using a supply of H2 and Ru catalyst, by means of the Sabatier reaction, which is CO2 + 4H2 CH4 + O2. The assembly contains two fixed-bed reactors operating in alternation: At first, air is blown through the first bed, which absorbs CO2 and H2O. Once the first bed is saturated with CO2 and H2O, the flow of air is diverted through the second bed and the first bed is regenerated by supplying it with H2 for the Sabatier reaction. Initially, the H2 is heated to provide heat for the regeneration reaction, which is endothermic. In the later stages of regeneration, the Sabatier reaction, which is exothermic, supplies the heat for regeneration.

  1. Removal of CO2 in a multistage fluidized bed reactor by diethanol amine impregnated activated carbon.

    PubMed

    Das, Dipa; Samal, Debi Prasad; Meikap, Bhim C

    2016-07-28

    To mitigate the emission of carbon dioxide (CO2), we have developed and designed a four-stage fluidized bed reactor. There is a counter current exchange between solid adsorbent and gas flow. In this present investigation diethanol amine (DEA) impregnated activated carbon made from green coconut shell was used as adsorbent. This type of adsorbent not only adsorbs CO2 due to the presence of pore but also chemically reacts with CO2 and form secondary zwitterions. Sampling and analysis of CO2 was performed using Orsat apparatus. The effect of initial CO2 concentration, gas velocity, solid rate, weir height etc. on removal efficiency of CO2 have been investigated and presented. The percentage removal of CO2 has been found close to 80% under low gas flow rate (0.188 m/s), high solid flow rate (4.12 kg/h) and weir height of 50 mm. From this result it has been found out that multistage fluidized bed reactor may be a suitable equipment for removal of CO2 from flue gas.

  2. Deep aquifer prokaryotic community responses to CO2 geosequestration

    NASA Astrophysics Data System (ADS)

    Mu, A.; Moreau, J. W.

    2015-12-01

    Little is known about potential microbial responses to supercritical CO2 (scCO2) injection into deep subsurface aquifers, a currently experimental means for mitigating atmospheric CO2 pollution being trialed at several locations around the world. One such site is the Paaratte Formation of the Otway Basin (~1400 m below surface; 60°C; 2010 psi), Australia. Microbial responses to scCO2 are important to understand as species selection may result in changes to carbon and electron flow. A key aim is to determine if biofilm may form in aquifer pore spaces and reduce aquifer permeability and storage. This study aimed to determine in situ, using 16S rRNA gene, and functional metagenomic analyses, how the microbial community in the Otway Basin geosequestration site responded to experimental injection of 150 tons of scCO2. We demonstrate an in situ sampling approach for detecting deep subsurface microbial community changes associated with geosequestration. First-order level analyses revealed a distinct shift in microbial community structure following the scCO2 injection event, with proliferation of genera Comamonas and Sphingobium. Similarly, functional profiling of the formation revealed a marked increase in biofilm-associated genes (encoding for poly-β-1,6-N-acetyl-D-glucosamine). Global analysis of the functional gene profile highlights that scCO2 injection potentially degraded the metabolism of CH4 and lipids. A significant decline in carboxydotrophic gene abundance (cooS) and an anaerobic carboxydotroph OTU (Carboxydocella), was observed in post-injection samples. The potential impacts on the flow networks of carbon and electrons to heterotrophs are discussed. Our findings yield insights for other subsurface systems, such as hydrocarbon-rich reservoirs and high-CO2 natural analogue sites.

  3. A novel pump-driven veno-venous gas exchange system during extracorporeal CO2-removal.

    PubMed

    Hermann, Alexander; Riss, Katharina; Schellongowski, Peter; Bojic, Andja; Wohlfarth, Philipp; Robak, Oliver; Sperr, Wolfgang R; Staudinger, Thomas

    2015-10-01

    Pump-driven veno-venous extracorporeal CO2-removal (ECCO2-R) increasingly takes root in hypercapnic lung failure to minimize ventilation invasiveness or to avoid intubation. A recently developed device (iLA activve(®), Novalung, Germany) allows effective decarboxylation via a 22 French double lumen cannula. To assess determinants of gas exchange, we prospectively evaluated the performance of ECCO2-R in ten patients receiving iLA activve(®) due to hypercapnic respiratory failure. Sweep gas flow was increased in steps from 1 to 14 L/min at constant blood flow (phase 1). Similarly, blood flow was gradually increased at constant sweep gas flow (phase 2). At each step gas transfer via the membrane as well as arterial blood gas samples were analyzed. During phase 1, we observed a significant increase in CO2 transfer together with a decrease in PaCO2 levels from a median of 66 mmHg (range 46-85) to 49 (31-65) mmHg from 1 to 14 L/min sweep gas flow (p < 0.0001), while arterial oxygenation deteriorated with high sweep gas flow rates. During phase 2, oxygen transfer significantly increased leading to an increase in PaO2 from 67 (49-87) at 0.5 L/min to 117 (66-305) mmHg at 2.0 L/min (p < 0.0001). Higher blood flows also significantly enhanced decarboxylation (p < 0.0001). Increasing sweep gas flow results in effective CO2-removal, which can be further reinforced by raising blood flow. The clinically relevant oxygenation effect in this setting could broaden the range of indications of the system and help to set up an individually tailored configuration.

  4. Widespread abiotic methane in chromitites.

    PubMed

    Etiope, G; Ifandi, E; Nazzari, M; Procesi, M; Tsikouras, B; Ventura, G; Steele, A; Tardini, R; Szatmari, P

    2018-06-07

    Recurring discoveries of abiotic methane in gas seeps and springs in ophiolites and peridotite massifs worldwide raised the question of where, in which rocks, methane was generated. Answers will impact the theories on life origin related to serpentinization of ultramafic rocks, and the origin of methane on rocky planets. Here we document, through molecular and isotopic analyses of gas liberated by rock crushing, that among the several mafic and ultramafic rocks composing classic ophiolites in Greece, i.e., serpentinite, peridotite, chromitite, gabbro, rodingite and basalt, only chromitites, characterized by high concentrations of chromium and ruthenium, host considerable amounts of 13 C-enriched methane, hydrogen and heavier hydrocarbons with inverse isotopic trend, which is typical of abiotic gas origin. Raman analyses are consistent with methane being occluded in widespread microfractures and porous serpentine- or chlorite-filled veins. Chromium and ruthenium may be key metal catalysts for methane production via Sabatier reaction. Chromitites may represent source rocks of abiotic methane on Earth and, potentially, on Mars.

  5. Membraneless water filtration using CO2

    NASA Astrophysics Data System (ADS)

    Shin, Sangwoo; Shardt, Orest; Warren, Patrick B.; Stone, Howard A.

    2017-05-01

    Water purification technologies such as microfiltration/ultrafiltration and reverse osmosis utilize porous membranes to remove suspended particles and solutes. These membranes, however, cause many drawbacks such as a high pumping cost and a need for periodic replacement due to fouling. Here we show an alternative membraneless method for separating suspended particles by exposing the colloidal suspension to CO2. Dissolution of CO2 into the suspension creates solute gradients that drive phoretic motion of particles. Due to the large diffusion potential generated by the dissociation of carbonic acid, colloidal particles move either away from or towards the gas-liquid interface depending on their surface charge. Using the directed motion of particles induced by exposure to CO2, we demonstrate a scalable, continuous flow, membraneless particle filtration process that exhibits low energy consumption, three orders of magnitude lower than conventional microfiltration/ultrafiltration processes, and is essentially free from fouling.

  6. Membraneless water filtration using CO2

    PubMed Central

    Shin, Sangwoo; Shardt, Orest; Warren, Patrick B.; Stone, Howard A.

    2017-01-01

    Water purification technologies such as microfiltration/ultrafiltration and reverse osmosis utilize porous membranes to remove suspended particles and solutes. These membranes, however, cause many drawbacks such as a high pumping cost and a need for periodic replacement due to fouling. Here we show an alternative membraneless method for separating suspended particles by exposing the colloidal suspension to CO2. Dissolution of CO2 into the suspension creates solute gradients that drive phoretic motion of particles. Due to the large diffusion potential generated by the dissociation of carbonic acid, colloidal particles move either away from or towards the gas–liquid interface depending on their surface charge. Using the directed motion of particles induced by exposure to CO2, we demonstrate a scalable, continuous flow, membraneless particle filtration process that exhibits low energy consumption, three orders of magnitude lower than conventional microfiltration/ultrafiltration processes, and is essentially free from fouling. PMID:28462929

  7. Effects of composition of the micro porous layer and the substrate on performance in the electrochemical reduction of CO2 to CO

    NASA Astrophysics Data System (ADS)

    Kim, Byoungsu; Hillman, Febrian; Ariyoshi, Miho; Fujikawa, Shigenori; Kenis, Paul J. A.

    2016-04-01

    With the development of better catalysts, mass transport limitations are becoming a challenge to high throughput electrochemical reduction of CO2 to CO. In contrast to optimization of electrodes for fuel cells, optimization of gas diffusion electrodes (GDE) - consisting of a carbon fiber substrate (CFS), a micro porous layer (MPL), and a catalyst layer (CL) - for CO2 reduction has not received a lot of attention. Here, we studied the effect of the MPL and CFS composition on cathode performance in electroreduction of CO2 to CO. In a flow reactor, optimized GDEs exhibited a higher partial current density for CO production than Sigracet 35BC, a commercially available GDE. By performing electrochemical impedance spectroscopy in a CO2 flow reactor we determined that a loading of 20 wt% PTFE in the MPL resulted in the best performance. We also investigated the influence of the thickness and wet proof level of CFS with two different feeds, 100% CO2 and the mixture of 50% CO2 and N2, determining that thinner and lower wet proofing of the CFS yields better cathode performance than when using a thicker and higher wet proof level of CFS.

  8. Experimental and Numerical Investigation of Two Dimensional CO2 Adsorption/Desorption in Packed Sorption Beds under Non-Ideal Flows

    NASA Technical Reports Server (NTRS)

    Mohamadinejad, H.; Knox, J. C.; Smith, J. E.; Croomes, Scott (Technical Monitor)

    2001-01-01

    The experimental results of CO2 adsorption and desorption in a packed column indicated that the concentration wave front at the center of the packed column differs from those which are close to the wall of column filled with adsorbent material even though the ratio of column diameter to the particle size is greater than 20. The comparison of the experimental results with one dimensional model of packed column shows that in order to simulate the average breakthrough in a packed column a two dimensional (radial and axial) model of packed column is needed. In this paper the mathematical model of a non-slip flow through a packed column with 2 inches in diameter and 18 inches in length filled with 5A zeolite pellets is presented. The comparison of experimental results of CO2 absorption and desorption for the mixed and central breakthrough of the packed column with numerical results is also presented.

  9. Diagnosing Abiotic Degradation

    EPA Science Inventory

    The abiotic degradation of chlorinated solvents in ground water can be difficult to diagnose. Under current practice, most of the “evidence” is negative; specifically the apparent disappearance of chlorinated solvents with an accumulation of vinyl chloride, ethane, ethylene, or ...

  10. The Stable Isotope Fractionation of Abiotic Reactions: A Benchmark in the Detection of Life

    NASA Technical Reports Server (NTRS)

    Summers, David P.

    2003-01-01

    mil to as low as -60 % (potentially comparable to that which accompanies the biosynthesis of organic matter). We need to understand what kind of fractionations are observed with reactions under the non-reducing or mildly reducing conditions now thought to be present on the early Earth. While nitrogen is receiving increased attention as a tool for these kinds of analyses, almost nothing is known about the isotope fractionation that one would expect for abiotic sources of fixed/reduced nitrogen. This project will measure the fixation from a series of abiotic reactions that may have been present on the early Earth (and other terrestrial planets) and produced organic material that could have ended up in the rock record. The work will look at a number of reactions, under a non- reducing, or mildly reducing, atmosphere, covering sources of prebiotic organic C & N from shock heating, to photochemistry, to hydrothermal reactions. Some reactions that we plan to study are; Shock heating of a non-reducing atmosphere to produce CO and NO (in collaboration with Chris McKay), formation of formaldehyde (and related compounds) from COY the formation of ammonia from nitrogen oxides (ultimately from NO) by ferrous iron reduction, and the hydrothermal synthesis of compounds including the hydrocarboxylation/hydrocarbonylation reaction (in collaboration with George Cody), reactions of oxalate to form hydrocarbons and other oxygenated compounds and the formation of lipids from oxalic/formic acid (in collaboration with Tom McCollom), and reactions of carbon monoxide & carbon dioxide with N2, ammonia or nitritehitrate to form hydrogen cyanide, nitriles, ammonia/amines and nitrous

  11. Differential expression of poplar sucrose nonfermenting1-related protein kinase 2 genes in response to abiotic stress and abscisic acid.

    PubMed

    Yu, Xiang; Takebayashi, Arika; Demura, Taku; Ohtani, Misato

    2017-09-01

    Knowledge on the responses of woody plants to abiotic stress can inform strategies to breed improved tree varieties and to manage tree species for environmental conservation and the production of lignocellulosic biomass. In this study, we examined the expression patterns of poplar (Populus trichocarpa) genes encoding members of the sucrose nonfermenting1-related protein kinase 2 (SnRK2) family, which are core components of the abiotic stress response. The P. trichocarpa genome contains twelve SnRK2 genes (PtSnRK2.1- PtSnRK2.12) that can be divided into three subclasses (I-III) based on the structures of their encoded kinase domains. We found that PtSnRK2s are differentially expressed in various organs. In MS medium-grown plants, all of the PtSnRK2 genes were significantly upregulated in response to abscisic acid (ABA) treatment, whereas osmotic and salt stress treatments induced only some (four and seven, respectively) of the PtSnRK2 genes. By contrast, soil-grown plants showed increased expression of most PtSnRK2 genes under drought and salt treatments, but not under ABA treatment. In soil-grown plants, drought stress induced SnRK2 subclass II genes in all tested organs (leaves, stems, and roots), whereas subclass III genes tended to be upregulated in leaves only. These results suggest that the PtSnRK2 genes are involved in abiotic stress responses, are at least partially activated by ABA, and show organ-specific responses.

  12. VUV photoionization cross sections of HO2, H2O2, and H2CO.

    PubMed

    Dodson, Leah G; Shen, Linhan; Savee, John D; Eddingsaas, Nathan C; Welz, Oliver; Taatjes, Craig A; Osborn, David L; Sander, Stanley P; Okumura, Mitchio

    2015-02-26

    The absolute vacuum ultraviolet (VUV) photoionization spectra of the hydroperoxyl radical (HO2), hydrogen peroxide (H2O2), and formaldehyde (H2CO) have been measured from their first ionization thresholds to 12.008 eV. HO2, H2O2, and H2CO were generated from the oxidation of methanol initiated by pulsed-laser-photolysis of Cl2 in a low-pressure slow flow reactor. Reactants, intermediates, and products were detected by time-resolved multiplexed synchrotron photoionization mass spectrometry. Absolute concentrations were obtained from the time-dependent photoion signals by modeling the kinetics of the methanol oxidation chemistry. Photoionization cross sections were determined at several photon energies relative to the cross section of methanol, which was in turn determined relative to that of propene. These measurements were used to place relative photoionization spectra of HO2, H2O2, and H2CO on an absolute scale, resulting in absolute photoionization spectra.

  13. De novo transcriptome sequence assembly and identification of AP2/ERF transcription factor related to abiotic stress in parsley (Petroselinum crispum).

    PubMed

    Li, Meng-Yao; Tan, Hua-Wei; Wang, Feng; Jiang, Qian; Xu, Zhi-Sheng; Tian, Chang; Xiong, Ai-Sheng

    2014-01-01

    Parsley is an important biennial Apiaceae species that is widely cultivated as herb, spice, and vegetable. Previous studies on parsley principally focused on its physiological and biochemical properties, including phenolic compound and volatile oil contents. However, little is known about the molecular and genetic properties of parsley. In this study, 23,686,707 high-quality reads were obtained and assembled into 81,852 transcripts and 50,161 unigenes for the first time. Functional annotation showed that 30,516 unigenes had sequence similarity to known genes. In addition, 3,244 putative simple sequence repeats were detected in curly parsley. Finally, 1,569 of the identified unigenes belonged to 58 transcription factor families. Various abiotic stresses have a strong detrimental effect on the yield and quality of parsley. AP2/ERF transcription factors have important functions in plant development, hormonal regulation, and abiotic response. A total of 88 putative AP2/ERF factors were identified from the transcriptome sequence of parsley. Seven AP2/ERF transcription factors were selected in this study to analyze the expression profiles of parsley under different abiotic stresses. Our data provide a potentially valuable resource that can be used for intensive parsley research.

  14. De Novo Transcriptome Sequence Assembly and Identification of AP2/ERF Transcription Factor Related to Abiotic Stress in Parsley (Petroselinum crispum)

    PubMed Central

    Wang, Feng; Jiang, Qian; Xu, Zhi-Sheng; Tian, Chang; Xiong, Ai-Sheng

    2014-01-01

    Parsley is an important biennial Apiaceae species that is widely cultivated as herb, spice, and vegetable. Previous studies on parsley principally focused on its physiological and biochemical properties, including phenolic compound and volatile oil contents. However, little is known about the molecular and genetic properties of parsley. In this study, 23,686,707 high-quality reads were obtained and assembled into 81,852 transcripts and 50,161 unigenes for the first time. Functional annotation showed that 30,516 unigenes had sequence similarity to known genes. In addition, 3,244 putative simple sequence repeats were detected in curly parsley. Finally, 1,569 of the identified unigenes belonged to 58 transcription factor families. Various abiotic stresses have a strong detrimental effect on the yield and quality of parsley. AP2/ERF transcription factors have important functions in plant development, hormonal regulation, and abiotic response. A total of 88 putative AP2/ERF factors were identified from the transcriptome sequence of parsley. Seven AP2/ERF transcription factors were selected in this study to analyze the expression profiles of parsley under different abiotic stresses. Our data provide a potentially valuable resource that can be used for intensive parsley research. PMID:25268141

  15. Oxygen and sulfur isotope systematics of sulfate produced by bacterial and abiotic oxidation of pyrite

    USGS Publications Warehouse

    Balci, N.; Shanks, Wayne C.; Mayer, B.; Mandernack, K.W.

    2007-01-01

    To better understand reaction pathways of pyrite oxidation and biogeochemical controls on ??18O and ??34S values of the generated sulfate in acid mine drainage (AMD) and other natural environments, we conducted a series of pyrite oxidation experiments in the laboratory. Our biological and abiotic experiments were conducted under aerobic conditions by using O2 as an oxidizing agent and under anaerobic conditions by using dissolved Fe(III)aq as an oxidant with varying ??18OH2O values in the presence and absence of Acidithiobacillus ferrooxidans. In addition, aerobic biological experiments were designed as short- and long-term experiments where the final pH was controlled at ???2.7 and 2.2, respectively. Due to the slower kinetics of abiotic sulfide oxidation, the aerobic abiotic experiments were only conducted as long term with a final pH of ???2.7. The ??34SSO4 values from both the biological and abiotic anaerobic experiments indicated a small but significant sulfur isotope fractionation (???-0.7???) in contrast to no significant fractionation observed from any of the aerobic experiments. Relative percentages of the incorporation of water-derived oxygen and dissolved oxygen (O2) to sulfate were estimated, in addition to the oxygen isotope fractionation between sulfate and water, and dissolved oxygen. As expected, during the biological and abiotic anaerobic experiments all of the sulfate oxygen was derived from water. The percentage incorporation of water-derived oxygen into sulfate during the oxidation experiments by O2 varied with longer incubation and lower pH, but not due to the presence or absence of bacteria. These percentages were estimated as 85%, 92% and 87% from the short-term biological, long-term biological and abiotic control experiments, respectively. An oxygen isotope fractionation effect between sulfate and water (??18 OSO4 s(-) H2 O) of ???3.5??? was determined for the anaerobic (biological and abiotic) experiments. This measured ??18 OSO42 - s(-) H2

  16. Experimental Quantification of Pore-Scale Flow Phenomena in 2D Heterogeneous Porous Micromodels: Multiphase Flow Towards Coupled Solid-Liquid Interactions

    NASA Astrophysics Data System (ADS)

    Li, Y.; Kazemifar, F.; Blois, G.; Christensen, K. T.

    2017-12-01

    Geological sequestration of CO2 within saline aquifers is a viable technology for reducing CO2 emissions. Central to this goal is accurately predicting both the fidelity of candidate sites pre-injection of CO2 and its post-injection migration. Moreover, local fluid pressure buildup may cause activation of small pre-existing unidentified faults, leading to micro-seismic events, which could prove disastrous for societal acceptance of CCS, and possibly compromise seal integrity. Recent evidence shows that large-scale events are coupled with pore-scale phenomena, which necessitates the representation of pore-scale stress, strain, and multiphase flow processes in large-scale modeling. To this end, the pore-scale flow of water and liquid/supercritical CO2 is investigated under reservoir-relevant conditions, over a range of wettability conditions in 2D heterogeneous micromodels that reflect the complexity of a real sandstone. High-speed fluorescent microscopy, complemented by a fast differential pressure transmitter, allows for simultaneous measurement of the flow field within and the instantaneous pressure drop across the micromodels. A flexible micromodel is also designed and fabricated, to be used in conjunction with the micro-PIV technique, enabling the quantification of coupled solid-liquid interactions.

  17. Gross primary production controls the subsequent winter CO2 exchange in a boreal peatland.

    PubMed

    Zhao, Junbin; Peichl, Matthias; Öquist, Mats; Nilsson, Mats B

    2016-12-01

    In high-latitude regions, carbon dioxide (CO 2 ) emissions during the winter represent an important component of the annual ecosystem carbon budget; however, the mechanisms that control the winter CO 2 emissions are currently not well understood. It has been suggested that substrate availability from soil labile carbon pools is a main driver of winter CO 2 emissions. In ecosystems that are dominated by annual herbaceous plants, much of the biomass produced during the summer is likely to contribute to the soil labile carbon pool through litter fall and root senescence in the autumn. Thus, the summer carbon uptake in the ecosystem may have a significant influence on the subsequent winter CO 2 emissions. To test this hypothesis, we conducted a plot-scale shading experiment in a boreal peatland to reduce the gross primary production (GPP) during the growing season. At the growing season peak, vascular plant biomass in the shaded plots was half that in the control plots. During the subsequent winter, the mean CO 2 emission rates were 21% lower in the shaded plots than in the control plots. In addition, long-term (2001-2012) eddy covariance data from the same site showed a strong correlation between the GPP (particularly the late summer and autumn GPP) and the subsequent winter net ecosystem CO 2 exchange (NEE). In contrast, abiotic factors during the winter could not explain the interannual variation in the cumulative winter NEE. Our study demonstrates the presence of a cross-seasonal link between the growing season biotic processes and winter CO 2 emissions, which has important implications for predicting winter CO 2 emission dynamics in response to future climate change. © 2016 John Wiley & Sons Ltd.

  18. The Wagner-Nelson method can generate an accurate gastric emptying flow curve from CO2 data obtained by a 13C-labeled substrate breath test.

    PubMed

    Sanaka, Masaki; Yamamoto, Takatsugu; Ishii, Tarou; Kuyama, Yasushi

    2004-01-01

    In pharmacokinetics, the Wagner-Nelson (W-N) method can accurately estimate the rate of drug absorption from its urinary elimination rate. A stable isotope (13C) breath test attempts to estimate the rate of absorption of 13C, as an index of gastric emptying rate, from the rate of pulmonary elimination of 13CO2. The time-gastric emptying curve determined by the breath test is quite different from that determined by scintigraphy or ultrasonography. In this report, we have shown that the W-N method can adjust the difference. The W-N equation to estimate gastric emptying from breath data is as follows: the fractional cumulative amount of gastric contents emptied by time t = Abreath (t)/Abreath (infinity) + (1/0.65).d[Abreath (t)/Abreath (infinity) ]/dt, where Abreath (t) = the cumulative recovery of 13CO2 in breath by time t and Abreath ( infinity ) = the ultimate cumulative 13CO2 recovery. The emptying flow curve generated by ultrasonography was compared with that generated by the W-N method-adjusted breath test in 6 volunteers. The emptying curves by the W-N method were almost identical to those by ultrasound. The W-N method can generate an accurate emptying flow curve from 13CO2 data, and it can adjust the difference between ultrasonography and the breath test. Copyright 2004 S. Karger AG, Basel

  19. Supercritical CO2 Extraction of Lavandula angustifolia Mill. Flowers: Optimisation of Oxygenated Monoterpenes, Coumarin and Herniarin Content.

    PubMed

    Jerković, Igor; Molnar, Maja; Vidović, Senka; Vladić, Jelena; Jokić, Stela

    2017-11-01

    Lavandula angustifolia is good source of oxygenated monoterpenes containing coumarins as well, which are all soluble in supercritical CO 2 (SC-CO 2 ). The study objective is to investigate SC-CO 2 extraction parameters on: the total yield; GC-MS profile of the extracts; relative content of oxygenated monoterpenes; the amount of coumarin and herniarin; and to determine optimal SC-CO 2 extraction conditions by response surface methodology (RSM). SC-CO 2 extraction was performed under different pressure, temperature and CO 2 flow rate determined by Box-Behnken design (BBD). The sample mass and the extraction time were kept constant. The chemical profiles and relative content of oxygenated monoterpenes (as coumarin equivalents, CE) were determined by GC-MS. Coumarin and herniarin concentrations were dosed by HPLC. SC-CO 2 extracts contained linalool (57.4-217.9 mg CE/100 g), camphor (10.6-154.4 mg CE/100 g), borneol (6.2-99.9 mg CE/100 g), 1,8-cineole (5.0-70.4 mg CE/100 g), linalyl acetate (86.1-267.9 mg CE/100 g), coumarin (0.95-18.16 mg/100 g), and herniarin (0.95-13.63 mg/100 g). The interaction between the pressure and CO 2 flow rate as well as between the temperature and CO 2 flow rate showed statistically significant influence on the extraction yield. Applying BBD, the optimum extraction conditions for higher monoterpenes and lower coumarin content were at 10 MPa, 41°C and CO 2 flow rate 2.3 kg/h, and at 30 MPa, 50°C and CO 2 flow rate 3 kg/h for higher monoterpenes and coumarin content. SC-CO 2 extraction is a viable technique for obtaining lavender extracts with desirable flavour components. The second-order model based on BBD predicts the results for SC-CO 2 extraction quite satisfactorily. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  20. Continuous N-alkylation reactions of amino alcohols using γ-Al2O3 and supercritical CO2: unexpected formation of cyclic ureas and urethanes by reaction with CO2.

    PubMed

    Streng, Emilia S; Lee, Darren S; George, Michael W; Poliakoff, Martyn

    2017-01-01

    The use of γ-Al 2 O 3 as a heterogeneous catalyst in scCO 2 has been successfully applied to the amination of alcohols for the synthesis of N -alkylated heterocycles. The optimal reaction conditions (temperature and substrate flow rate) were determined using an automated self-optimising reactor, resulting in moderate to high yields of the target products. Carrying out the reaction in scCO 2 was shown to be beneficial, as higher yields were obtained in the presence of CO 2 than in its absence. A surprising discovery is that, in addition to cyclic amines, cyclic ureas and urethanes could be synthesised by incorporation of CO 2 from the supercritical solvent into the product.

  1. Porous carbon from local coconut shell char by CO2 and H2O activation in the presence of K2CO3

    NASA Astrophysics Data System (ADS)

    Vi, Nguyen Ngoc Thuy; Truyen, Dang Hai; Trung, Bien Cong; An, Ngo Thanh; Van Dung, Nguyen; Long, Nguyen Quang

    2017-09-01

    Vietnamese coconut shell char was activated by steam and carbon dioxide at low temperatures with the presence of K2CO3 as a catalyst. The effects of process parameters on adsorption capability of the product including different ratio of impregnation of activation agents, activation temperature, activation time were investigated in this study. Iodine number, methylene blue adsorption capacity, specific surface area and pore size distribution were measured to assess the properties of the activated carbon. Accordingly, the porous carbon was applied for toluene removal by adsorption technology. Significant increases in specific surface area and the toluene adsorption capacity were observed when the coconut shell char was activated in CO2 flow at 720 °C for 150 minutes and the K2CO3/char weight ratio of 0.5.

  2. Assessment of fluid distribution and flow properties in two phase fluid flow using X-ray CT technology

    NASA Astrophysics Data System (ADS)

    Jiang, Lanlan; Wu, Bohao; Li, Xingbo; Wang, Sijia; Wang, Dayong; Zhou, Xinhuan; Zhang, Yi

    2018-04-01

    To study on microscale distribution of CO2 and brine during two-phase flow is crucial for understanding the trapping mechanisms of CO2 storage. In this study, CO2-brine flow experiments in porous media were conducted using X-ray computed tomography. The porous media were packed with glass beads. The pore structure (porosity/tortuosity) and flow properties at different flow rates and flow fractions were investigated. The results showed that porosity of the packed beads differed at different position as a result of heterogeneity. The CO2 saturation is higher at low injection flow rates and high CO2 fractions. CO2 distribution at the pore scale was also visualized. ∅ Porosity of porous media CT brine_ sat grey value of sample saturated with brine CT dry grey value of sample saturated with air CT brine grey value of pure brine CT air grey value of pure air CT flow grey values of sample with two fluids occupying the pore space {CT}_{CO_2_ sat} grey value of sample saturated with CO2 {f}_{CO_2}({S}_{CO_2}) CO2 fraction {q}_{CO_2} the volume flow rate for CO2 q brine the volume flow rate for brine L Thickness of the porous media, mm L e a bundle of capillaries of equal length, mm τ Tortuosity, calculated from L e / L.

  3. Fault-Related CO 2 Degassing, Geothermics, and Fluid Flow in Southern California Basins--Physiochemical Evidence and Modeling

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

    Garven, Grant

    2015-08-11

    Our studies have had an important impact on societal issues. Experimental and field observations show that CO 2 degassing, such as might occur from stored CO 2 reservoir gas, can result in significant stable isotopic disequilibrium. In the offshore South Ellwood field of the Santa Barbara channel, we show how oil production has reduced natural seep rates in the area, thereby reducing greenhouse gases. Permeability is calculated to be ~20-30 millidarcys for km-scale fault-focused fluid flow, using changes in natural gas seepage rates from well production, and poroelastic changes in formation pore-water pressure. In the Los Angeles (LA) basin, ourmore » characterization of formation water chemistry, including stable isotopic studies, allows the distinction between deep and shallow formations waters. Our multiphase computational-based modeling of petroleum migration demonstrates the important role of major faults on geological-scale fluid migration in the LA basin, and show how petroleum was dammed up against the Newport-Inglewood fault zone in a “geologically fast” interval of time (less than 0.5 million years). Furthermore, these fluid studies also will allow evaluation of potential cross-formational mixing of formation fluids. Lastly, our new study of helium isotopes in the LA basin shows a significant leakage of mantle helium along the Newport Inglewood fault zone (NIFZ), at flow rates up to 2 cm/yr. Crustal-scale fault permeability (~60 microdarcys) and advective versus conductive heat transport rates have been estimated using the observed helium isotopic data. The NIFZ is an important deep-seated fault that may crosscut a proposed basin decollement fault in this heavily populated area, and appears to allow seepage of helium from the mantle sources about 30 km beneath Los Angeles. The helium study has been widely cited in recent weeks by the news media, both in radio and on numerous web sites.« less

  4. Dehydrating and Sterilizing Wastes Using Supercritical CO2

    NASA Technical Reports Server (NTRS)

    Brown, Ian J.

    2006-01-01

    A relatively low-temperature process for dehydrating and sterilizing biohazardous wastes in an enclosed life-support system exploits (1) the superior mass-transport properties of supercritical fluids in general and (2) the demonstrated sterilizing property of supercritical CO2 in particular. The wastes to be treated are placed in a chamber. Liquid CO2, drawn from storage at a pressure of 850 psi (approx.=5.9 MPa) and temperature of 0 C, is compressed to pressure of 2 kpsi (approx.=14 MPa) and made to flow into the chamber. The compression raises the temperature to 10 C. The chamber and its contents are then further heated to 40 C, putting the CO2 into a supercritical state, in which it kills microorganisms in the chamber. Carrying dissolved water, the CO2 leaves the chamber through a back-pressure regulator, through which it is expanded back to the storage pressure. The expanded CO2 is refrigerated to extract the dissolved water as ice, and is then returned to the storage tank at 0 C

  5. Enhance performance of micro direct methanol fuel cell by in situ CO2 removal using novel anode flow field with superhydrophobic degassing channels

    NASA Astrophysics Data System (ADS)

    Liang, Junsheng; Luo, Ying; Zheng, Sheng; Wang, Dazhi

    2017-05-01

    Capillary blocking caused by CO2 bubbles in anode flow field (AFF) is one of the bottlenecks for performance improvement of a micro direct methanol fuel cell (μDMFC). In this work, we present a novel AFF structure with nested layout of hydrophilic fuel channels and superhydrophobic degassing channels which can remove most of CO2 from AFF before it is released to the fuel channels. The new AFFs are fabricated on Ti substrates by using micro photochemical etching combined with anodization and fluorination treatments. Performance of the μDMFCs with and without superhydrophobic degassing channels in their AFF is comparatively studied. Results show that the superhydrophobic degassing channels can significantly speed up the exhaust of CO2 from the AFF. CO2 clogging is not observed in the new AFFs even when their comparison AFFs have been seriously blocked by CO2 slugs under the same operating conditions. 55% and 60% of total CO2 produced in μDMFCs with N-serpentine and N-spiral AFF can be respectively removed by the superhydrophobic degassing channels. The power densities of the μDMFCs equipped with new serpentine and spiral AFFs are respectively improved by 30% and 90% compared with those using conventional AFFs. This means that the new AFFs developed in this work can effectively prevent CO2-induced capillary blocking in the fuel channels, and finally significantly improve the performance of the μDMFCs.

  6. The relationship between transpiration and nutrient uptake in wheat changes under elevated atmospheric CO2.

    PubMed

    Houshmandfar, Alireza; Fitzgerald, Glenn J; O'Leary, Garry; Tausz-Posch, Sabine; Fletcher, Andrew; Tausz, Michael

    2017-12-04

    The impact of elevated [CO 2 ] (e[CO 2 ]) on crops often includes a decrease in their nutrient concentrations where reduced transpiration-driven mass flow of nutrients has been suggested to play a role. We used two independent approaches, a free-air CO 2 enrichment (FACE) experiment in the South Eastern wheat belt of Australia and a simulation study employing the agricultural production systems simulator (APSIM), to show that transpiration (mm) and nutrient uptake (g m -2 ) of nitrogen (N), potassium (K), sulfur (S), calcium (Ca), magnesium (Mg) and manganese (Mn) in wheat are correlated under e[CO 2 ], but that nutrient uptake per unit water transpired is higher under e[CO 2 ] than under ambient [CO 2 ] (a[CO 2 ]). This result suggests that transpiration-driven mass flow of nutrients contributes to decreases in nutrient concentrations under e[CO 2 ], but cannot solely explain the overall decline. © 2017 Scandinavian Plant Physiology Society.

  7. Carbon flow from volcanic CO2 into soil microbial communities of a wetland mofette

    USGS Publications Warehouse

    Beulig, Felix; Heuer, Verena B.; Akob, Denise M.; Viehweger, Bernhard; Elvert, Marcus; Herrmann, Martina; Hinrichs, Kai-Uwe; Küsel, Kirsten

    2015-01-01

    Effects of extremely high carbon dioxide (CO2) concentrations on soil microbial communities and associated processes are largely unknown. We studied a wetland area affected by spots of subcrustal CO2 degassing (mofettes) with focus on anaerobic autotrophic methanogenesis and acetogenesis because the pore gas phase was largely hypoxic. Compared with a reference soil, the mofette was more acidic (ΔpH ~0.8), strongly enriched in organic carbon (up to 10 times), and exhibited lower prokaryotic diversity. It was dominated by methanogens and subdivision 1Acidobacteria, which likely thrived under stable hypoxia and acidic pH. Anoxic incubations revealed enhanced formation of acetate and methane (CH4) from hydrogen (H2) and CO2 consistent with elevated CH4 and acetate levels in the mofette soil. 13CO2 mofette soil incubations showed high label incorporations with ~512 ng13C g (dry weight (dw)) soil−1 d−1 into the bulk soil and up to 10.7 ng 13C g (dw) soil−1 d−1 into almost all analyzed bacterial lipids. Incorporation of CO2-derived carbon into archaeal lipids was much lower and restricted to the first 10 cm of the soil. DNA-SIP analysis revealed that acidophilic methanogens affiliated withMethanoregulaceae and hitherto unknown acetogens appeared to be involved in the chemolithoautotrophic utilization of 13CO2. Subdivision 1 Acidobacteriaceae assimilated 13CO2 likely via anaplerotic reactions because Acidobacteriaceae are not known to harbor enzymatic pathways for autotrophic CO2 assimilation. We conclude that CO2-induced geochemical changes promoted anaerobic and acidophilic organisms and altered carbon turnover in affected soils.

  8. CO2 reforming of methane: valorizing CO2 by means of Dielectric Barrier Discharge

    NASA Astrophysics Data System (ADS)

    Machrafi, H.; Cavadias, S.; Amouroux, J.

    2011-03-01

    The impact of pollution on the environment is causing several problems that are to be reduced as much as possible. One important example is the production of CO2 that is emitted by many transport and industrial applications. An interesting solution is to view CO2 as a source instead of a product that can be stocked. The case considered in this work is the CO2 reformation of methane producing hydrogen and CO. It is an endothermic reaction, for which the activition barrier needs to be overcome. The method of Dielectric Barrier Discharge can do this efficiently. The process relies on the collision of electrons, which are accelerated under an electrical field that is created in the discharge area. This leads to the formation of reactive species, which facilitate the abovementioned reaction. The determination of the electron density is performed by PLASIMO. The study is subsequently continued using the Reaction Engineering module in COMSOL (with an incorporated kinetic mechanism) in order to model the discharge phase. Then COMSOL (continuity and Navier-Stokes equations) is used to model the flow in the post-discharge phase. The results showed that both a 2D and 3D model can be used to model the chemical-plasma process. These methods need strongly reduced kinetic mechanism, which in some cases can cause loss of precision. It is also observed that the present experimental set-up that is modeled needs to be improved. A suggestion is made.

  9. Studies of CW lasing action in CO2-CO, N2O-CO, CO2-H2O, and N2O-H2O mixtures pumped by blackbody radiation

    NASA Technical Reports Server (NTRS)

    Abel, Robert W.; Christiansen, Walter H.; Li, Jian-Guo

    1988-01-01

    A proof of principle experiment to evaluate the efficacy of CO and H2O in increasing the power output for N2O and CO2 lasing mixtures has been conducted and theoretically analyzed for a blackbody radiation-pumped laser. The results for N2O-CO, CO2-CO, N2O-H2O and CO2-H2O mixtures are presented. Additions of CO to the N2O lasant increased power up to 28 percent for N2O laser mixtures, whereas additions of CO to the CO2 lasant, and the addition of H2O to both the CO2 and N2O lasants, resulted in decreased output power.

  10. Modeling of CO 2 sequestration in coal seams: Role of CO 2 -induced coal softening on injectivity, storage efficiency and caprock deformation: Original Research Article: Modeling of CO 2 sequestration in coal seams

    DOE PAGES

    Ma, Tianran; Rutqvist, Jonny; Liu, Weiqun; ...

    2017-01-30

    An effective and safe operation for sequestration of CO 2 in coal seams requires a clear understanding of injection-induced coupled hydromechanical processes such as the evolution of pore pressure, permeability, and induced caprock deformation. In this study, CO 2 injection into coal seams was studied using a coupled flow-deformation model with a new stress-dependent porosity and permeability model that considers CO 2 -induced coal softening. Based on triaxial compression tests of coal samples extracted from the site of the first series of enhanced coalbed methane field tests in China, a softening phenomenon that a substantial (one-order-of-magnitude) decrease of Young's modulusmore » and an increase of Poisson's ratio with adsorbed CO 2 content was observed. Such softening was considered in the numerical simulation through an exponential relation between elastic properties (Young's modulus and Poisson's ratio) and CO 2 pressure considering that CO 2 content is proportional to the CO 2 pressure. Our results of the numerical simulation show that the softening of the coal strongly affects the CO 2 sequestration performance, first by impeding injectivity and stored volume (cumulative injection) during the first week of injection, and thereafter by softening mediated rebound in permeability that tends to increase injectivity and storage over the longer term. A sensitivity study shows that stronger CO 2 -induced coal softening and higher CO 2 injection pressure contribute synergistically to increase a significant increase of CO 2 injectivity and adsorption, but also result in larger caprock deformations and uplift. This study demonstrates the importance of considering the CO 2 -induced softening when analyzing the performance and environmental impact of CO 2 -sequestration operations in unminable coal seams.« less

  11. Modeling of CO 2 sequestration in coal seams: Role of CO 2 -induced coal softening on injectivity, storage efficiency and caprock deformation: Original Research Article: Modeling of CO 2 sequestration in coal seams

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

    Ma, Tianran; Rutqvist, Jonny; Liu, Weiqun

    An effective and safe operation for sequestration of CO 2 in coal seams requires a clear understanding of injection-induced coupled hydromechanical processes such as the evolution of pore pressure, permeability, and induced caprock deformation. In this study, CO 2 injection into coal seams was studied using a coupled flow-deformation model with a new stress-dependent porosity and permeability model that considers CO 2 -induced coal softening. Based on triaxial compression tests of coal samples extracted from the site of the first series of enhanced coalbed methane field tests in China, a softening phenomenon that a substantial (one-order-of-magnitude) decrease of Young's modulusmore » and an increase of Poisson's ratio with adsorbed CO 2 content was observed. Such softening was considered in the numerical simulation through an exponential relation between elastic properties (Young's modulus and Poisson's ratio) and CO 2 pressure considering that CO 2 content is proportional to the CO 2 pressure. Our results of the numerical simulation show that the softening of the coal strongly affects the CO 2 sequestration performance, first by impeding injectivity and stored volume (cumulative injection) during the first week of injection, and thereafter by softening mediated rebound in permeability that tends to increase injectivity and storage over the longer term. A sensitivity study shows that stronger CO 2 -induced coal softening and higher CO 2 injection pressure contribute synergistically to increase a significant increase of CO 2 injectivity and adsorption, but also result in larger caprock deformations and uplift. This study demonstrates the importance of considering the CO 2 -induced softening when analyzing the performance and environmental impact of CO 2 -sequestration operations in unminable coal seams.« less

  12. Abiotic Bromination of Soil Organic Matter

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

    Leri, Alessandra C.; Ravel, Bruce

    Biogeochemical transformations of plant-derived soil organic matter (SOM) involve complex abiotic and microbially mediated reactions. One such reaction is halogenation, which occurs naturally in the soil environment and has been associated with enzymatic activity of decomposer organisms. Building on a recent finding that naturally produced organobromine is ubiquitous in SOM, we hypothesized that inorganic bromide could be subject to abiotic oxidations resulting in bromination of SOM. Through lab-based degradation treatments of plant material and soil humus, we have shown that abiotic bromination of particulate organic matter occurs in the presence of a range of inorganic oxidants, including hydrogen peroxide andmore » assorted forms of ferric iron, producing both aliphatic and aromatic forms of organobromine. Bromination of oak and pine litter is limited primarily by bromide concentration. Fresh plant material is more susceptible to bromination than decayed litter and soil humus, due to a labile pool of mainly aliphatic compounds that break down during early stages of SOM formation. As the first evidence of abiotic bromination of particulate SOM, this study identifies a mechanistic source of the natural organobromine in humic substances and the soil organic horizon. Formation of organobromine through oxidative treatments of plant material also provides insights into the relative stability of aromatic and aliphatic components of SOM.« less

  13. Abiotic Bromination of Soil Organic Matter.

    PubMed

    Leri, Alessandra C; Ravel, Bruce

    2015-11-17

    Biogeochemical transformations of plant-derived soil organic matter (SOM) involve complex abiotic and microbially mediated reactions. One such reaction is halogenation, which occurs naturally in the soil environment and has been associated with enzymatic activity of decomposer organisms. Building on a recent finding that naturally produced organobromine is ubiquitous in SOM, we hypothesized that inorganic bromide could be subject to abiotic oxidations resulting in bromination of SOM. Through lab-based degradation treatments of plant material and soil humus, we have shown that abiotic bromination of particulate organic matter occurs in the presence of a range of inorganic oxidants, including hydrogen peroxide and assorted forms of ferric iron, producing both aliphatic and aromatic forms of organobromine. Bromination of oak and pine litter is limited primarily by bromide concentration. Fresh plant material is more susceptible to bromination than decayed litter and soil humus, due to a labile pool of mainly aliphatic compounds that break down during early stages of SOM formation. As the first evidence of abiotic bromination of particulate SOM, this study identifies a mechanistic source of the natural organobromine in humic substances and the soil organic horizon. Formation of organobromine through oxidative treatments of plant material also provides insights into the relative stability of aromatic and aliphatic components of SOM.

  14. Ignition and Combustion of Pulverized Coal and Biomass under Different Oxy-fuel O2/N2 and O2/CO2 Environments

    NASA Astrophysics Data System (ADS)

    Khatami Firoozabadi, Seyed Reza

    This work studied the ignition and combustion of burning pulverized coals and biomasses particles under either conventional combustion in air or oxy-fuel combustion conditions. Oxy-fuel combustion is a 'clean-coal' process that takes place in O2/CO2 environments, which are achieved by removing nitrogen from the intake gases and recirculating large amounts of flue gases to the boiler. Removal of nitrogen from the combustion gases generates a high CO2-content, sequestration-ready gas at the boiler effluent. Flue gas recirculation moderates the high temperatures caused by the elevated oxygen partial pressure in the boiler. In this study, combustion of the fuels took place in a laboratory laminar-flow drop-tube furnace (DTF), electrically-heated to 1400 K, in environments containing various mole fractions of oxygen in either nitrogen or carbon-dioxide background gases. The experiments were conducted at two different gas conditions inside the furnace: (a) quiescent gas condition (i.e., no flow or inactive flow) and, (b) an active gas flow condition in both the injector and furnace. Eight coals from different ranks (anthracite, semi-snthracite, three bituminous, subbituminous and two lignites) and four biomasses from different sources were utilized in this work to study the ignition and combustion characteristics of solid fuels in O2/N2 or O2/CO2 environments. The main objective is to study the effect of replacing background N2 with CO2, increasing O2 mole fraction and fuel type and rank on a number of qualitative and quantitative parameters such as ignition/combustion mode, ignition temperature, ignition delay time, combustion temperatures, burnout times and envelope flame soot volume fractions. Regarding ignition, in the quiescent gas condition, bituminous and sub-bituminous coal particles experienced homogeneous ignition in both O2/N 2 and O2/CO2 atmospheres, while in the active gas flow condition, heterogeneous ignition was evident in O2/CO 2. Anthracite, semi

  15. The Impeller Exit Flow Coefficient As a Performance Map Variable for Predicting Centrifugal Compressor Off-Design Operation Applied to a Supercritical CO 2 Working Fluid

    DOE PAGES

    Liese, Eric; Zitney, Stephen E.

    2017-06-26

    A multi-stage centrifugal compressor model is presented with emphasis on analyzing use of an exit flow coefficient vs. an inlet flow coefficient performance parameter to predict off-design conditions in the critical region of a supercritical carbon dioxide (CO 2) power cycle. A description of the performance parameters is given along with their implementation in a design model (number of stages, basic sizing, etc.) and a dynamic model (for use in transient studies). A design case is shown for two compressors, a bypass compressor and a main compressor, as defined in a process simulation of a 10 megawatt (MW) supercritical COmore » 2 recompression Brayton cycle. Simulation results are presented for a simple open cycle and closed cycle process with changes to the inlet temperature of the main compressor which operates near the CO 2 critical point. Results showed some difference in results using the exit vs. inlet flow coefficient correction, however, it was not significant for the range of conditions examined. Here, this paper also serves as a reference for future works, including a full process simulation of the 10 MW recompression Brayton cycle.« less

  16. The Impeller Exit Flow Coefficient As a Performance Map Variable for Predicting Centrifugal Compressor Off-Design Operation Applied to a Supercritical CO 2 Working Fluid

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

    Liese, Eric; Zitney, Stephen E.

    A multi-stage centrifugal compressor model is presented with emphasis on analyzing use of an exit flow coefficient vs. an inlet flow coefficient performance parameter to predict off-design conditions in the critical region of a supercritical carbon dioxide (CO 2) power cycle. A description of the performance parameters is given along with their implementation in a design model (number of stages, basic sizing, etc.) and a dynamic model (for use in transient studies). A design case is shown for two compressors, a bypass compressor and a main compressor, as defined in a process simulation of a 10 megawatt (MW) supercritical COmore » 2 recompression Brayton cycle. Simulation results are presented for a simple open cycle and closed cycle process with changes to the inlet temperature of the main compressor which operates near the CO 2 critical point. Results showed some difference in results using the exit vs. inlet flow coefficient correction, however, it was not significant for the range of conditions examined. Here, this paper also serves as a reference for future works, including a full process simulation of the 10 MW recompression Brayton cycle.« less

  17. Effect of upper airway CO2 pattern on ventilatory frequency in tegu lizards.

    PubMed

    Ballam, G O; Coates, E L

    1989-07-01

    Nasal CO2-sensitive receptors are reported to depress ventilatory frequency in several reptilian species in response to constant low levels of inspired CO2. The purpose of this study was to determine the influence of phasic patterns of CO2 in the upper airways on ventilation. Awake lizards (Tupinambis nigropunctatus) breathed through an endotracheal tube from an isolated gas source. A second gas mixture was forced at constant flow into the external nares. A concentration of 4% CO2 was intermittently pulsed through the nares in a square-wave pattern with a frequency of 60, 12, 6, 4.2, 1.8, and 0.6 cycles/min. Concentrations of 2, 3, 4, and 6% CO2 were also pulsed through the nares at 12 cycles/min and compared with sustained levels of 1, 1.5, 2, and 3%. Additionally, 0 or 3% CO2 was forced through the upper airways with a servo system designed to mimic normal ventilatory flow and gas concentrations. No changes in breathing pattern were noted during any of the pulsing protocols, although a significant breathing frequency depression was present with sustained levels of CO2 of comparable mean concentrations. We conclude that ventilatory control is selectively responsive to sustained levels of environmental CO2 but not to phasic changes in upper airway CO2 concentration.

  18. Abiotic stress responses in plants: roles of calmodulin-regulated proteins.

    PubMed

    Virdi, Amardeep S; Singh, Supreet; Singh, Prabhjeet

    2015-01-01

    Intracellular changes in calcium ions (Ca(2+)) in response to different biotic and abiotic stimuli are detected by various sensor proteins in the plant cell. Calmodulin (CaM) is one of the most extensively studied Ca(2+)-sensing proteins and has been shown to be involved in transduction of Ca(2+) signals. After interacting with Ca(2+), CaM undergoes conformational change and influences the activities of a diverse range of CaM-binding proteins. A number of CaM-binding proteins have also been implicated in stress responses in plants, highlighting the central role played by CaM in adaptation to adverse environmental conditions. Stress adaptation in plants is a highly complex and multigenic response. Identification and characterization of CaM-modulated proteins in relation to different abiotic stresses could, therefore, prove to be essential for a deeper understanding of the molecular mechanisms involved in abiotic stress tolerance in plants. Various studies have revealed involvement of CaM in regulation of metal ions uptake, generation of reactive oxygen species and modulation of transcription factors such as CAMTA3, GTL1, and WRKY39. Activities of several kinases and phosphatases have also been shown to be modulated by CaM, thus providing further versatility to stress-associated signal transduction pathways. The results obtained from contemporary studies are consistent with the proposed role of CaM as an integrator of different stress signaling pathways, which allows plants to maintain homeostasis between different cellular processes. In this review, we have attempted to present the current state of understanding of the role of CaM in modulating different stress-regulated proteins and its implications in augmenting abiotic stress tolerance in plants.

  19. Development of an advanced Sabatier CO2 reduction subsystem

    NASA Technical Reports Server (NTRS)

    Kleiner, G. N.; Cusick, R. J.

    1981-01-01

    A preprototype Sabatier CO2 reduction subsystem was successfully designed, fabricated and tested. The lightweight, quick starting (less than 5 minutes) reactor utlizes a highly active and physically durable methanation catalyst composed of ruthenium on alumina. The use of this improved catalyst permits a simple, passively controlled reactor design with an average lean component H2/CO2 conversion efficiency of over 99% over a range of H2/CO2 molar ratios of 1.8 to 5 while operating with process flows equivalent to a crew size of up to five persons. The subsystem requires no heater operation after start-up even during simulated 55 minute lightside/39 minute darkside orbital operation.

  20. 10 MW Supercritical CO2 Turbine Test

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

    Turchi, Craig

    2014-01-29

    The Supercritical CO2 Turbine Test project was to demonstrate the inherent efficiencies of a supercritical carbon dioxide (s-CO2) power turbine and associated turbomachinery under conditions and at a scale relevant to commercial concentrating solar power (CSP) projects, thereby accelerating the commercial deployment of this new power generation technology. The project involved eight partnering organizations: NREL, Sandia National Laboratories, Echogen Power Systems, Abengoa Solar, University of Wisconsin at Madison, Electric Power Research Institute, Barber-Nichols, and the CSP Program of the U.S. Department of Energy. The multi-year project planned to design, fabricate, and validate an s-CO2 power turbine of nominally 10 MWemore » that is capable of operation at up to 700°C and operates in a dry-cooled test loop. The project plan consisted of three phases: (1) system design and modeling, (2) fabrication, and (3) testing. The major accomplishments of Phase 1 included: Design of a multistage, axial-flow, s-CO2 power turbine; Design modifications to an existing turbocompressor to provide s-CO2 flow for the test system; Updated equipment and installation costs for the turbomachinery and associated support infrastructure; Development of simulation tools for the test loop itself and for more efficient cycle designs that are of greater commercial interest; Simulation of s-CO2 power cycle integration into molten-nitrate-salt CSP systems indicating a cost benefit of up to 8% in levelized cost of energy; Identification of recuperator cost as a key economic parameter; Corrosion data for multiple alloys at temperatures up to 650ºC in high-pressure CO2 and recommendations for materials-of-construction; and Revised test plan and preliminary operating conditions based on the ongoing tests of related equipment. Phase 1 established that the cost of the facility needed to test the power turbine at its full power and temperature would exceed the planned funding for Phases 2 and

  1. Assessment of CO2 Mineralization and Dynamic Rock Properties at the Kemper Pilot CO2 Injection Site

    NASA Astrophysics Data System (ADS)

    Qin, F.; Kirkland, B. L.; Beckingham, L. E.

    2017-12-01

    CO2-brine-mineral reactions following CO2 injection may impact rock properties including porosity, permeability, and pore connectivity. The rate and extent of alteration largely depends on the nature and evolution of reactive mineral interfaces. In this work, the potential for geochemical reactions and the nature of the reactive mineral interface and corresponding hydrologic properties are evaluated for samples from the Lower Tuscaloosa, Washita-Fredericksburg, and Paluxy formations. These formations have been identified as future regionally extensive and attractive CO2 storage reservoirs at the CO2 Storage Complex in Kemper County, Mississippi, USA (Project ECO2S). Samples from these formations were obtained from the Geological Survey of Alabama and evaluated using a suite of complementary analyses. The mineral composition of these samples will be determined using petrography and powder X-ray Diffraction (XRD). Using these compositions, continuum-scale reactive transport simulations will be developed and the potential CO2-brine-mineral interactions will be examined. Simulations will focus on identifying potential reactive minerals as well as the corresponding rate and extent of reactions. The spatial distribution and accessibility of minerals to reactive fluids is critical to understanding mineral reaction rates and corresponding changes in the pore structure, including pore connectivity, porosity and permeability. The nature of the pore-mineral interface, and distribution of reactive minerals, will be determined through imaging analysis. Multiple 2D scanning electron microscopy (SEM) backscattered electron (BSE) images and energy dispersive x-ray spectroscopy (EDS) images will be used to create spatial maps of mineral distributions. These maps will be processed to evaluate the accessibility of reactive minerals and the potential for flow-path modifications following CO2 injection. The "Establishing an Early CO2 Storage Complex in Kemper, MS" project is funded by

  2. Improving CO2 permeation and separation performance of CO2-philic polymer membrane by blending CO2 absorbents

    NASA Astrophysics Data System (ADS)

    Cheng, Jun; Hu, Leiqing; Li, Yannan; Liu, Jianzhong; Zhou, Junhu; Cen, Kefa

    2017-07-01

    To research effects of CO2 absorption capacity and type of CO2 absorbent on the CO2 separation and free-volume properties of facilitated transport membranes, two types of CO2 absorbents, namely monoethanolamine (MEA) and ionic liquids (ILs:[P66614][Triz] and [P66614][2-Op]), were adopted. The CO2 absorption capacities of MEA, [P66614][Triz] and [P66614][2-Op] were about 0.561 mol CO2 per mol, 0.95 mol CO2 per mol and 1.60 mol CO2 per mol, respectively. All mean free-volume hole radiuses of membranes decreased after blending CO2 absorbents. After polymer membrane blended with two ILs, number of free-volume hole increased, resulting in modest increase of the fractional free volume. Both CO2 permeability and selectivity increased after blending MEA and ILs. The increasing range of CO2 permeability corresponded with CO2 absorption capacity of CO2 absorbents, and membrane blending with [P66614][2-Op] showed the highest CO2 permeability of 672.1 Barrers at 25 °C. Pebax/PEGDME membrane blending with MEA obtained the highest CO2/H2 and CO2/CH4 selectivity at 17.8 and 20.5, respectively.

  3. White Mars: A New Model for Mars' Surface and Atmosphere Based on CO 2

    NASA Astrophysics Data System (ADS)

    Hoffman, Nick

    2000-08-01

    A new model is presented for the Amazonian outburst floods on Mars. Rather than the working fluid being water, with the associated difficulties in achieving warm and wet conditions on Mars and on collecting and removing the water before and after the floods, instead this model suggests that CO 2 is the active agent in the "floods." The flow is not a conventional liquid flood but is instead a gas-supported density flow akin to terrestrial volcanic pyroclastic flows and surges and at cryogenic temperatures with support from degassing of CO 2-bearing ices. The flows are not sourced from volcanic vents, but from the collapse of thick layered regolith containing liquid CO 2 to form zones of chaotic terrain, as shown by R. St. J. Lambert and V. E. Chamberlain (1978, Icarus34, 568-580; 1992, Workshop on the Evolution of the Martian Atmosphere). Submarine turbidites are also analagous in the flow mechanism, but the martian cryogenic flows were both dry and subaerial, so there is no need for a warm and wet epoch nor an ocean on Mars. Armed with this new model for the floods we review the activity of volatiles on the surface of Mars in the context of a cold ice world—"White Mars." We find that many of the recognized paradoxes about Mars' surface and atmosphere are resolved. In particular, the lack of carbonates on Mars is due to the lack of liquid water. The CO 2 of the primordial atmosphere and the H 2O inventory remain largely sequestered in subsurface ices. The distribution of water ice on modern Mars is also reevaluated, with important potential consequences for future Mars exploration. The model for collapse of terrain due to ices that show decompression melting, and the generation of nonaqueous flows in these circumstances may also be applicable to outer Solar System bodies, where CO 2, SO 2, N 2, and other ices are stable.

  4. Large Eddy Simulation of Supercritical CO2 Through Bend Pipes

    NASA Astrophysics Data System (ADS)

    He, Xiaoliang; Apte, Sourabh; Dogan, Omer

    2017-11-01

    Supercritical Carbon Dioxide (sCO2) is investigated as working fluid for power generation in thermal solar, fossil energy and nuclear power plants at high pressures. Severe erosion has been observed in the sCO2 test loops, particularly in nozzles, turbine blades and pipe bends. It is hypothesized that complex flow features such as flow separation and property variations may lead to large oscillations in the wall shear stresses and result in material erosion. In this work, large eddy simulations are conducted at different Reynolds numbers (5000, 27,000 and 50,000) to investigate the effect of heat transfer in a 90 degree bend pipe with unit radius of curvature in order to identify the potential causes of the erosion. The simulation is first performed without heat transfer to validate the flow solver against available experimental and computational studies. Mean flow statistics, turbulent kinetic energy, shear stresses and wall force spectra are computed and compared with available experimental data. Formation of counter-rotating vortices, named Dean vortices, are observed. Secondary flow pattern and swirling-switching flow motions are identified and visualized. Effects of heat transfer on these flow phenomena are then investigated by applying a constant heat flux at the wall. DOE Fossil Energy Crosscutting Technology Research Program.

  5. 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

  6. Airborne testing and demonstration of a new flight system based on an Aerodyne N2O-CO2-CO-H2O mini-spectrometer

    NASA Astrophysics Data System (ADS)

    Gvakharia, A.; Kort, E. A.; Smith, M. L.; Conley, S.

    2017-12-01

    Nitrous oxide (N2O) is a powerful greenhouse gas and ozone depleting substance. With high atmospheric backgrounds and small relative signals, N2O emissions have been challenging to observe and understand on regional scales with traditional instrumentation. Fast-response airborne measurements with high precision and accuracy can potentially bridge this observational gap. Here we present flight assessments of a new flight system based on an Aerodyne mini-spectrometer as well as a Los Gatos N2O/CO analyzer during the Fertilizer Emissions Airborne Study (FEAST). With the Scientific Aviation Mooney aircraft, we conducted test flights for both analyzers where a known calibration gas was sampled throughout the flight (`null' tests). Clear altitude/cabin-pressure dependencies were observed for both analyzers if operated in an "off-the-shelf' manner. For the remainder of test flights and the FEAST campaign we used a new flight system based on an Aerodyne mini-spectrometer with the addition of a custom pressure control/calibration system. Instead of using traditional approaches with spectral-zeros and infrequent in-flight calibrations, we employ a high-flow system with stable flow control to enable high frequency (2 minutes), short duration (15 seconds) sampling of a known calibration gas. This approach, supported by the null test, enables correction for spectral drift caused by a variety of factors while maintaining a 90% duty cycle for 1Hz sampling from an aircraft. Preliminary in-flight precisions are estimated at 0.05 ppb, 0.1 ppm, 1 ppb, and 10 ppm for N2O, CO2, CO, and H2O respectively. We also present a further 40 hours of inter-comparison in flight with a Picarro 2301-f ring-down spectrometer demonstrating consistency between CO2 and H2O measurements and no altitude dependent error.

  7. Are karrikins involved in plant abiotic stress responses?

    PubMed

    Li, Weiqiang; Tran, Lam-Son Phan

    2015-09-01

    Recent reports have shown that strigolactones play a positive role in plant responses to drought and salt stress through MAX2 (More Axillary Growth 2). Increasing evidence suggests that MAX2 is also involved in karrikin signaling, raising the question whether karrikins play any role in plant adaptation to abiotic stresses. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Effect of voluntary hyperventilation with supplemental CO2 on pulmonary O2 uptake and leg blood flow kinetics during moderate-intensity exercise.

    PubMed

    Chin, Lisa M K; Heigenhauser, George J F; Paterson, Donald H; Kowalchuk, John M

    2013-12-01

    Pulmonary O2 uptake (V(O₂p)) and leg blood flow (LBF) kinetics were examined at the onset of moderate-intensity exercise, during hyperventilation with and without associated hypocapnic alkalosis. Seven male subjects (25 ± 6 years old; mean ± SD) performed alternate-leg knee-extension exercise from baseline to moderate-intensity exercise (80% of estimated lactate threshold) and completed four to six repetitions for each of the following three conditions: (i) control [CON; end-tidal partial pressure of CO2 (P(ET, CO₂)) ~40 mmHg], i.e. normal breathing with normal inspired CO2 (0.03%); (ii) hypocapnia (HYPO; P(ET, CO₂) ~20 mmHg), i.e. sustained hyperventilation with normal inspired CO2 (0.03%); and (iii) normocapnia (NORMO; P(ET, CO₂) ~40 mmHg), i.e. sustained hyperventilation with elevated inspired CO2 (~5%). The V(O₂p) was measured breath by breath using mass spectrometry and a volume turbine. Femoral artery mean blood velocity was measured by Doppler ultrasound, and LBF was calculated from femoral artery diameter and mean blood velocity. Phase 2 V(O₂p) kinetics (τV(O₂p)) was different (P < 0.05) amongst all three conditions (CON, 19 ± 7 s; HYPO, 43 ± 17 s; and NORMO, 30 ± 8 s), while LBF kinetics (τLBF) was slower (P < 0.05) in HYPO (31 ± 9 s) compared with both CON (19 ± 3 s) and NORMO (20 ± 6 s). Similar to previous findings, HYPO was associated with slower V(O₂p) and LBF kinetics compared with CON. In the present study, preventing the fall in end-tidal P(CO₂) (NORMO) restored LBF kinetics, but not V(O₂p) kinetics, which remained 'slowed' relative to CON. These data suggest that the hyperventilation manoeuvre itself (i.e. independent of induced hypocapnic alkalosis) may contribute to the slower V(O₂p) kinetics observed during HYPO.

  9. Support media can steer methanogenesis in the presence of phenol through biotic and abiotic effects.

    PubMed

    Poirier, Simon; Déjean, Sébastien; Chapleur, Olivier

    2018-09-01

    A wide variety of inhibitors can induce anaerobic digester disruption. To avoid performance losses, support media can be used to mitigate inhibitions. However, distinguishing the physico-chemical from the biological mechanisms of such strategies remains delicate. In this framework, the impact of 10  g/L of different types of zeolites and activated carbons (AC) on microbial community dynamics during anaerobic digestion of biowaste in the presence of 1.3 g/L of phenol was evaluated with 16 S rRNA gene sequencing. In the presence of AC, methanogenesis inhibition was rapidly removed due to a decrease of phenol concentration. This abiotic effect related to the physico-chemical properties of AC led to increased final CH4 and CO2 productions by 29-31% compared to digesters incubated without support. Interestingly, although zeolite did not adsorb phenol, final CH4 and CO2 production reached comparable levels as with AC. Nevertheless, compared to digesters incubated without support, methanogenesis lag phase duration was less reduced in the presence of zeolites (5 ± 1 days) than in the presence of activated carbons (12 ± 2 days). Both types of support induced biotic effects. AC and zeolite both allowed the preservation of the major representative archaeal genus of the non-inhibited ecosystem, Methanosarcina. By contrast, they distinctly shaped bacterial populations. OTUs belonging to class W5 became dominant at the expense of OTUs assigned to orders Clostridiales, Bacteroidales and Anaerolinales in the presence of AC. Zeolite enhanced the implantation of OTUs assigned to bacterial phylum Cloacimonetes. This study highlighted that supports can induce biotic and abiotic effects within digesters inhibited with phenol, showing potentialities to enhance anaerobic digestion stability under disrupting conditions. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Diffuse CO2 degassing at Vesuvio, Italy

    NASA Astrophysics Data System (ADS)

    Frondini, Francesco; Chiodini, Giovanni; Caliro, Stefano; Cardellini, Carlo; Granieri, Domenico; Ventura, Guido

    2004-10-01

    At Vesuvio, a significant fraction of the rising hydrothermal-volcanic fluids is subjected to a condensation and separation process producing a CO2-rich gas phase, mainly expulsed through soil diffuse degassing from well defined areas called diffuse degassing structures (DDS), and a liquid phase that flows towards the outer part of the volcanic cone. A large amount of thermal energy is associated with the steam condensation process and subsequent cooling of the liquid phase. The total amount of volcanic-hydrothermal CO2 discharged through diffuse degassing has been computed through a sequential Gaussian simulation (sGs) approach based on several hundred accumulation chamber measurements and, at the time of the survey, amounted to 151 t d-1. The steam associated with the CO2 output, computed assuming that the original H2O/CO2 ratio of hydrothermal fluids is preserved in fumarolic effluents, is 553 t d-1, and the energy produced by the steam condensation and cooling of the liquid phase is 1.47×1012 J d-1 (17 MW). The location of the CO2 and temperature anomalies show that most of the gas is discharged from the inner part of the crater and suggests that crater morphology and local stratigraphy exert strong control on CO2 degassing and subsurface steam condensation. The amounts of gas and energy released by Vesuvio are comparable to those released by other volcanic degassing areas of the world and their estimates, through periodic surveys of soil CO2 flux, can constitute a useful tool to monitor volcanic activity.

  11. Conductivity measurements on H 2O-bearing CO 2-rich fluids

    DOE PAGES

    Capobianco, Ryan M.; Miroslaw S. Gruszkiewicz; Bodnar, Robert J.; ...

    2014-09-10

    Recent studies report rapid corrosion of metals and carbonation of minerals in contact with carbon dioxide containing trace amounts of dissolved water. One explanation for this behavior is that addition of small amounts of H 2O to CO 2 leads to significant ionization within the fluid, thus promoting reactions at the fluid-solid interface analogous to corrosion associated with aqueous fluids. The extent of ionization in the bulk CO 2 fluid was determined using a flow-through conductivity cell capable of detecting very low conductivities. Experiments were conducted from 298 to 473 K and 7.39 to 20 MPa with H 2O concentrationsmore » up to ~1600 ppmw (xH 2O ≈ 3.9 x 10 -3), corresponding to the H 2O solubility limit in liquid CO 2 at ambient temperature. All solutions showed conductivities <10 nS/cm, indicating that the solutions were essentially ion-free. Furthermore, this observation suggests that the observed corrosion and carbonation reactions are not the result of ionization in CO 2-rich bulk phase, but does not preclude ionization in the fluid at the fluid-solid interface.« less

  12. Development of a preprototype Sabatier CO2 reduction subsystem

    NASA Technical Reports Server (NTRS)

    Kleiner, G. N.; Birbara, P.

    1981-01-01

    A lightweight, quick starting reactor utilizes a highly active and physically durable methanation catalyst composed of ruthenium on alumina. The use of this improved catalyst permits a single straight through plug flow design with an average lean component H2/CO2 conversion efficiency of over 99% over a range of H2/CO2 molar ratios of 1.8 to 5 while operating with flows equivalent to a crew size of one person steadystate to 3 persons cyclical. The reactor requires no heater operation after start-up even during simulated 55 minute lightside/39 minute darkside orbital operation over the above range of molar ratios and crew loadings. Subsystem performance was proven by parametric testing and endurance testing over a wide range of crew sizes and metabolic loadings. The subsystem's operation and performance is controlled by a microprocessor and displayed on a nineteen inch multi-colored cathode ray tube.

  13. StimuFrac Compressibility as a Function of CO2 Molar Fraction

    DOE Data Explorer

    Carlos A. Fernandez

    2016-04-29

    Compressibility values were obtained in a range of pressures at 250degC by employing a fixed volume view cell completely filled with PAA aqueous solution and injecting CO2 at constant flow rate (0.3mL/min). Pressure increase as a function of supercritical CO2 (scCO2) mass fraction in the mixture was monitored. The plot shows the apparent compressibility of Stimufrac as a function of scCO2 mass fraction obtained in a pressure range between 2100-7000 psi at 250degC. At small mass fractions of scCO2 the compressibility increases probably due to the dissolution/reaction of CO2 in aqueous PAA and reaches a maximum at mCO2/mH2O = 0.06. Then, compressibility decreases showing a linear relationship with scCO2 mass fraction due to the continuous increase in density of the binary fluid associated to the pressure increase.

  14. The interaction between abiotic photodegradation and microbial decomposition under ultraviolet radiation.

    PubMed

    Wang, Jing; Liu, Lingli; Wang, Xin; Chen, Yiwei

    2015-05-01

    Elevated ultraviolet (UV) radiation has been demonstrated to stimulate litter decomposition. Despite years of research, it is still not fully understood whether the acceleration in litter degradation is primarily attributed to abiotic photodegradation or the combined effects of abiotic photodegradation and microbial decomposition. In this study, we used meta-analysis to synthesize photodegradation studies and compared the effects of UV radiation on litter decomposition between abiotic and biotic conditions. We also conducted a microcosm experiment to assess the effects of UV radiation on litter biodegradability and microbial activity. Overall, our meta-analysis found that under abiotic photodegradation, UV radiation reduced the remaining litter mass by 1.44% (95% CI: 0.85% to 2.08%), did not affect the remaining lignin and increased the dissolved organic carbon (DOC) concentration by 14.01% (1.49-23.67%). Under combined abiotic photodegradation and microbial decomposition, UV radiation reduced the remaining litter mass and lignin by 1.60% (0.04-3.58%) and 16.07% (9.27-24.23%), respectively, but did not alter DOC concentration. UV radiation had no significant impact on soil microbial biomass carbon (MBC), but it reduced microbial respiration by 44.91% (2.26-78.62%) and altered the composition of the microbial community. In addition, UV radiation reduced nitrogen (N) immobilization by 19.44% (4.77-37.92%). Our microcosm experiment further indicated that DOC concentration and the amount of respired C in UV-treated litter increased with UV exposure time, suggesting that longer UV exposure resulted in greater biodegradability. Overall, our study suggested that UV exposure could increase litter biodegradability by increasing the microbial accessibility of lignin, as well as the labile carbon supply to microbes. However, the remaining litter mass was not different between the abiotic and biotic conditions, most likely because the positive effect of UV radiation on litter

  15. High pressurized CO2 release CFD calculations from onshore pipeline leakages

    NASA Astrophysics Data System (ADS)

    Herzog, Nicoleta; Gorenz, Paul; Egbers, Christoph

    2013-04-01

    Emissions from high pressurized pipelines can be determined on the basis of hydrodynamical and thermophysical calculations of the escaped fluid. If a rupture occurs when CO2 is onshore transported in liquid form there will be initially a large pressure drop in the pipeline, the pressure will fall until the liquid becomes a mixture of saturated vapor/liquid. In the vicinity of the rupture, liquid CO2 will escape and immediately vaporize and expand, some of the liquid will desublimate into dry ice, which will precipitate onto the ground [1, 2]. The period of time taken for a large amount of carbon dioxide to be discharged would be short. Initially CO2 will escape by pushing the overlying soil upwards at an explosion-like speed. After the pressure in the pipe fell the flow profile of the escaping gas will almost be as described for gaseous material transport. The expansion of carbon dioxide will occur at sonic speed and will continue to do so until the pressure ratio between the CO2 and the ambient air is lower than about 1.9 [3]. As a result of the expansion also the temperature of the escaping gas will fall drastically and a cloud of cold gas will form which is then dispersed and slowly mixed with ambient air. The rate of emptying the pipeline is controlled by the pipe cross-section area and the speed of the escaping gas, or by the pressure difference between the pipeline and the atmosphere. Therefore the mass flow will be largest immediately after the accident with an exponential decay in time. In this study a two-phase model is applied to a high pressurized pipeline through which liquid carbon dioxide flows. A leakage is considered to be at different positions along the pipeline and the release pressure is calculated over several parameter ranges. It is also intended to characterize from hydrodynamical point of view the dispersion of released CO2 in the ambient medium by means of CFD simulations which includes multiphase flow treatment. For that a turbulent two

  16. Solvent Effects on the Photothermal Regeneration of CO 2 in Monoethanolamine Nanofluids

    DOE PAGES

    Nguyen, Du; Stolaroff, Joshuah; Esser-Kahn, Aaron

    2015-11-02

    We present that a potential approach to reduce energy costs associated with carbon capture is to use external and renewable energy sources. The photothermal release of CO 2 from monoethanolamine mediated by nanoparticles is a unique solution to this problem. When combined with light-absorbing nanoparticles, vapor bubbles form inside the capture solution and release the CO 2 without heating the bulk solvent. The mechanism by which CO 2 is released remained unclear, and understanding this process would improve the efficiency of photothermal CO 2 release. Here we report the use of different cosolvents to improve or reduce the photothermal regenerationmore » of CO 2 captured by monoethanolamine. We found that properties that reduce the residence time of the gas bubbles (viscosity, boiling point, and convection direction) can enhance the regeneration efficiencies. The reduction of bubble residence times minimizes the reabsorption of CO 2 back into the capture solvent where bulk temperatures remain lower than the localized area surrounding the nanoparticle. These properties shed light on the mechanism of release and indicated methods for improving the efficiency of the process. We used this knowledge to develop an improved photothermal CO 2 regeneration system in a continuously flowing setup. Finally, using techniques to reduce residence time in the continuously flowing setup, such as alternative cosolvents and smaller fluid volumes, resulted in regeneration efficiency enhancements of over 200%.« less

  17. Solvent Effects on the Photothermal Regeneration of CO 2 in Monoethanolamine Nanofluids

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

    Nguyen, Du; Stolaroff, Joshuah; Esser-Kahn, Aaron

    We present that a potential approach to reduce energy costs associated with carbon capture is to use external and renewable energy sources. The photothermal release of CO 2 from monoethanolamine mediated by nanoparticles is a unique solution to this problem. When combined with light-absorbing nanoparticles, vapor bubbles form inside the capture solution and release the CO 2 without heating the bulk solvent. The mechanism by which CO 2 is released remained unclear, and understanding this process would improve the efficiency of photothermal CO 2 release. Here we report the use of different cosolvents to improve or reduce the photothermal regenerationmore » of CO 2 captured by monoethanolamine. We found that properties that reduce the residence time of the gas bubbles (viscosity, boiling point, and convection direction) can enhance the regeneration efficiencies. The reduction of bubble residence times minimizes the reabsorption of CO 2 back into the capture solvent where bulk temperatures remain lower than the localized area surrounding the nanoparticle. These properties shed light on the mechanism of release and indicated methods for improving the efficiency of the process. We used this knowledge to develop an improved photothermal CO 2 regeneration system in a continuously flowing setup. Finally, using techniques to reduce residence time in the continuously flowing setup, such as alternative cosolvents and smaller fluid volumes, resulted in regeneration efficiency enhancements of over 200%.« less

  18. CO2 plume management in saline reservoir sequestration

    USGS Publications Warehouse

    Frailey, S.M.; Finley, R.J.

    2011-01-01

    A significant difference between injecting CO2 into saline aquifers for sequestration and injecting fluids into oil reservoirs or natural gas into aquifer storage reservoirs is the availability and use of other production and injection wells surrounding the primary injection well(s). Of major concern for CO2 sequestration using a single well is the distribution of pressure and CO2 saturation within the injection zone. Pressure is of concern with regards to caprock integrity and potential migration of brine or CO2 outside of the injection zone, while CO2 saturation is of interest for storage rights and displacement efficiency. For oil reservoirs, the presence of additional wells is intended to maximize oil recovery by injecting CO2 into the same hydraulic flow units from which the producing wells are withdrawing fluids. Completing injectors and producers in the same flow unit increases CO2 throughput, maximizes oil displacement efficiency, and controls pressure buildup. Additional injectors may surround the CO2 injection well and oil production wells in order to provide external pressure to these wells to prevent the injected CO2 from migrating from the pattern between two of the producing wells. Natural gas storage practices are similar in that to reduce the amount of "cushion" gas and increase the amount of cycled or working gas, edge wells may be used for withdrawal of gas and center wells used for gas injection. This reduces loss of gas to the formation via residual trapping far from the injection well. Moreover, this maximizes the natural gas storage efficiency between the injection and production wells and reduces the areal extent of the natural gas plume. Proposed U.S. EPA regulations include monitoring pressure and suggest the "plume" may be defined by pressure in addition to the CO2 saturated area. For pressure monitoring, it seems that this can only be accomplished by injection zone monitoring wells. For pressure, these wells would not need to be very

  19. Development of a CO 2 Chemical Sensor for Downhole CO 2 Monitoring in Carbon Sequestration

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

    Liu, Ning

    Geologic storage of carbon dioxide (CO 2) has been proposed as a viable means for reducing anthropogenic CO 2 emissions. The means for geological sequestration of CO 2 is injection of supercritical CO 2 underground, which requires the CO 2 to remain either supercritical, or in solution in the water/brine present in the underground formation. However, there are aspects of geologic sequestration that need further study, particularly in regards to safety. To date, none of the geologic sequestration locations have been tested for storage integrity under the changing stress conditions that apply to the sequestration of very large amounts ofmore » CO 2. Establishing environmental safety and addressing public concerns require widespread monitoring of the process in the deep subsurface. In addition, studies of subsurface carbon sequestration such as flow simulations, models of underground reactions and transports require a comprehensive monitoring process to accurately characterize and understand the storage process. Real-time information about underground CO 2 movement and concentration change is highly helpful for: (1) better understanding the uncertainties present in CO 2 geologic storage; (2) improvement of simulation models; and (3) evaluation of the feasibility of geologic CO 2 storage. Current methods to monitor underground CO 2 storage include seismic, geoelectric, isotope and tracer methods, and fluid sampling analysis. However, these methods commonly resulted low resolution, high cost, and the inability to monitor continuously over the long time scales of the CO 2 storage process. A preferred way of monitoring in-situ underground CO 2 migration is to continuous measure CO 2 concentration change in brine during the carbon storage process. An approach to obtain the real time information on CO 2 concentration change in formation solution is highly demanded in carbon storage to understand the CO 2 migration subsurface and to answer the public safety problem. The

  20. Laboratory Study of the Displacement Coalbed CH4 Process and Efficiency of CO2 and N2 Injection

    PubMed Central

    Wang, Liguo; Wang, Yongkang

    2014-01-01

    ECBM displacement experiments are a direct way to observe the gas displacement process and efficiency by inspecting the produced gas composition and flow rate. We conducted two sets of ECBM experiments by injecting N2 and CO2 through four large parallel specimens (300 × 50 × 50 mm coal briquette). N2 or CO2 is injected at pressures of 1.5, 1.8, and 2.2 MPa and various crustal stresses. The changes in pressure along the briquette and the concentration of the gas mixture flowing out of the briquette were analyzed. Gas injection significantly enhances CBM recovery. Experimental recoveries of the original extant gas are in excess of 90% for all cases. The results show that the N2 breakthrough occurs earlier than the CO2 breakthrough. The breakthrough time of N2 is approximately 0.5 displaced volumes. Carbon dioxide, however, breaks through at approximately 2 displaced volumes. Coal can adsorb CO2, which results in a slower breakthrough time. In addition, ground stress significantly influences the displacement effect of the gas injection. PMID:24741346

  1. Equilibrium model analysis of waste plastics gasification using CO2 and steam.

    PubMed

    Kannan, P; Lakshmanan, G; Al Shoaibi, A; Srinivasakannan, C

    2017-12-01

    Utilization of carbon dioxide (CO 2 ) in thermochemical treatment of waste plastics may significantly help to improve CO 2 recycling, thus simultaneously curtailing dioxins/furans and CO 2 emissions. Although CO 2 is not such an effective gasifying agent as steam, a few investigations have explored the utilization of CO 2 in conjunction with steam to achieve somewhat higher carbon conversion. This work presents a comparative evaluation study of CO 2 and steam gasification of a typical post-consumer waste plastics mixture using an Aspen Plus equilibrium model. The effect of flow rate of gasifying medium (CO 2 and/or steam) and gasification temperature on product gas composition, carbon conversion, and cold gas efficiency has been analyzed. Simulation results demonstrate that CO 2 can serve as a potential gasifying agent for waste plastics gasification. The resulting product gas was rich in CO whereas CO 2 -steam blends yield a wider H 2 /CO ratio, thus extending the applications of the product gas.

  2. An Experimental Study of Effects in Soils by Potential CO2 Seepage

    NASA Astrophysics Data System (ADS)

    Wei, Y.; Caramanna, G.; Nathanail, P.; Steven, M.; Maroto-Valer, M.

    2011-12-01

    Potential CO2 seepage during a CCS project will not only reduce its performing efficiency, but can also impact the local environment. Though scientists announce with confidence that CCS is a safe technology to store CO2 deep underground, it is essential to study the effects of CO2 seepage, to avoid any possible influences on soils. As a simplified environment, laboratory experiments can easily be controlled and vital to be studied to be compared with more complex natural analogues and modelling works. Recent research focuses on the effects on ecosystems of CO2 leakage. However, the impacts of long-term, low level exposure for both surface and subsurface ecosystems, as well as soil geochemistry changes are currently not clear. Moreover, previous work has focussed on pure CO2 leakage only and its impacts on the ecosystem. However, in a more realistic scenario the gas coming from a capture process may contain impurities, such as SO2, which are more dangerous than pure CO2 and could cause more severe consequences. Therefore, it is critical to assess the potential additional risks caused by CO2 leakage with impurities. Accordingly, both a batch and a continuous flow reactor were designed and used to study potential impacts caused by the CO2 seepage, focusing on soil geochemistry changes, due to different concentrations of CO2/SO2 mixtures. Stage 1- Batch experiments. In this stage, a soil sample was collected from the field and exposed to a controlled CO2/SO2 gas mixtures (100% CO2 and CO2:SO2=99:1). The water soluble fractions were measured before and after incubation. With 100% CO2 incubation it was found that: 1) the pH in the soil sample did not change significantly; 2) for soils with different moisture levels, greater moisture in the soil results in higher CO2 uptake during incubation; and 3) for sandy soils, small changes in CaCl2-exchangeable metal concentration, were observed after CO2 incubation. However, the increased concentration of toxic elements is still

  3. Development of a Novel Catalytic Membrane Reactor for Heterogeneous Catalysis in Supercritical CO2

    PubMed Central

    Islam, Nazrul M.; Chatterjee, Maya; Ikushima, Yutaka; Yokoyama, Toshiro; Kawanami, Hajime

    2010-01-01

    A novel type of high-pressure membrane reactor has been developed for hydrogenation in supercritical carbon dioxide (scCO2). The main objectives of the design of the reactor are the separate feeding of hydrogen and substrate in scCO2 for safe reactions in a continuous flow process, and to reduce the reaction time. By using this new reactor, hydrogenation of cinnamaldehyde into hydrocinnamaldehyde has been successfully carried out with 100% selectivity at 50 °C in 10 MPa (H2: 1 MPa, CO2: 9 MPa) with a flow rate of substrate ranging from 0.05 to 1.0 mL/min. PMID:20162008

  4. Abiotic stress responses in plants: roles of calmodulin-regulated proteins

    PubMed Central

    Virdi, Amardeep S.; Singh, Supreet; Singh, Prabhjeet

    2015-01-01

    Intracellular changes in calcium ions (Ca2+) in response to different biotic and abiotic stimuli are detected by various sensor proteins in the plant cell. Calmodulin (CaM) is one of the most extensively studied Ca2+-sensing proteins and has been shown to be involved in transduction of Ca2+ signals. After interacting with Ca2+, CaM undergoes conformational change and influences the activities of a diverse range of CaM-binding proteins. A number of CaM-binding proteins have also been implicated in stress responses in plants, highlighting the central role played by CaM in adaptation to adverse environmental conditions. Stress adaptation in plants is a highly complex and multigenic response. Identification and characterization of CaM-modulated proteins in relation to different abiotic stresses could, therefore, prove to be essential for a deeper understanding of the molecular mechanisms involved in abiotic stress tolerance in plants. Various studies have revealed involvement of CaM in regulation of metal ions uptake, generation of reactive oxygen species and modulation of transcription factors such as CAMTA3, GTL1, and WRKY39. Activities of several kinases and phosphatases have also been shown to be modulated by CaM, thus providing further versatility to stress-associated signal transduction pathways. The results obtained from contemporary studies are consistent with the proposed role of CaM as an integrator of different stress signaling pathways, which allows plants to maintain homeostasis between different cellular processes. In this review, we have attempted to present the current state of understanding of the role of CaM in modulating different stress-regulated proteins and its implications in augmenting abiotic stress tolerance in plants. PMID:26528296

  5. Zeolites for CO2-CO-O2 Separation to Obtain CO2-Neutral Fuels.

    PubMed

    Perez-Carbajo, Julio; Matito-Martos, Ismael; Balestra, Salvador R G; Tsampas, Mihalis N; van de Sanden, Mauritius C M; Delgado, José A; Águeda, V Ismael; Merkling, Patrick J; Calero, Sofia

    2018-06-20

    Carbon dioxide release has become an important global issue due to the significant and continuous rise in atmospheric CO 2 concentrations and the depletion of carbon-based energy resources. Plasmolysis is a very energy-efficient process for reintroducing CO 2 into energy and chemical cycles by converting CO 2 into CO and O 2 utilizing renewable electricity. The bottleneck of the process is that CO remains mixed with O 2 and residual CO 2 . Therefore, efficient gas separation and recuperation are essential for obtaining pure CO, which, via water gas shift and Fischer-Tropsch reactions, can lead to the production of CO 2 -neutral fuels. The idea behind this work is to provide a separation mechanism based on zeolites to optimize the separation of carbon dioxide, carbon monoxide, and oxygen under mild operational conditions. To achieve this goal, we performed a thorough screening of available zeolites based on topology and adsorptive properties using molecular simulation and ideal adsorption solution theory. FAU, BRE, and MTW are identified as suitable topologies for these separation processes. FAU can be used for the separation of carbon dioxide from carbon monoxide and oxygen and BRE or MTW for the separation of carbon monoxide from oxygen. These results are reinforced by pressure swing adsorption simulations at room temperature combining adsorption columns with pure silica FAU zeolite and zeolite BRE at a Si/Al ratio of 3. These zeolites have the added advantage of being commercially available.

  6. Experimental Investigations into CO2 Interactions with Injection Well Infrastructure for CO2 Storage

    NASA Astrophysics Data System (ADS)

    Syed, Amer; Shi, Ji-Quan; Durucan, Sevket; Nash, Graham; Korre, Anna

    2013-04-01

    outer steel ring. A radial pressure is maintained on the wellbore casing during cement setting, i.e., the casing is in a state of tension, so that a microannulus can be created by subsequent contraction of CLM when the radial pressure is relieved. The aperture (permeability) of the microannulus can be controlled by varying the CLM pressure on the casing, which is maintained throughout a flow test. During a test, pure CO2/brine saturated CO2 is flown through the microannulus over a period of time to study its permeability behaviour under simulated downhole conditions. Evolution in permeability is monitored and the effluent is collected and analysed regularly. These experimental results will be used as an input to implement a time-dependent microannulus permeability in the numerical model to assess the impact of such behaviour on the storage performance of a CO2 storage reservoir. The results of the first set of experiments, where the permeability behaviour of pure CO2 was monitored over a 3 months period, are presented and discussed in this paper.

  7. A Nitrogen-Doped Carbon Catalyst for Electrochemical CO2 Conversion to CO with High Selectivity and Current Density.

    PubMed

    Jhong, Huei-Ru Molly; Tornow, Claire E; Smid, Bretislav; Gewirth, Andrew A; Lyth, Stephen M; Kenis, Paul J A

    2017-03-22

    We report characterization of a non-precious metal-free catalyst for the electrochemical reduction of CO 2 to CO; namely, a pyrolyzed carbon nitride and multiwall carbon nanotube composite. This catalyst exhibits a high selectivity for production of CO over H 2 (approximately 98 % CO and 2 % H 2 ), as well as high activity in an electrochemical flow cell. The CO partial current density at intermediate cathode potentials (V=-1.46 V vs. Ag/AgCl) is up to 3.5× higher than state-of-the-art Ag nanoparticle-based catalysts, and the maximum current density is 90 mA cm -2 . The mass activity and energy efficiency (up to 48 %) were also higher than the Ag nanoparticle reference. Moving away from precious metal catalysts without sacrificing activity or selectivity may significantly enhance the prospects of electrochemical CO 2 reduction as an approach to reduce atmospheric CO 2 emissions or as a method for load-leveling in relation to the use of intermittent renewable energy sources. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Role of sugars under abiotic stress.

    PubMed

    Sami, Fareen; Yusuf, Mohammad; Faizan, Mohammad; Faraz, Ahmad; Hayat, Shamsul

    2016-12-01

    Sugars are the most important regulators that facilitate many physiological processes, such as photosynthesis, seed germination, flowering, senescence, and many more under various abiotic stresses. Exogenous application of sugars in low concentration promote seed germination, up regulates photosynthesis, promotes flowering, delayed senescence under various unfavorable environmental conditions. However, high concentration of sugars reverses all these physiological process in a concentration dependent manner. Thus, this review focuses the correlation between sugars and their protective functions in several physiological processes against various abiotic stresses. Keeping in mind the multifaceted role of sugars, an attempt has been made to cover the role of sugar-regulated genes associated with photosynthesis, seed germination and senescence. The concentration of sugars determines the expression of these sugar-regulated genes. This review also enlightens the interaction of sugars with several phytohormones, such as abscisic acid, ethylene, cytokinins and gibberellins and its effect on their biosynthesis under abiotic stress conditions. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  9. Modeling and optimal design of CO2 Direct Air Capture systems in large arrays

    NASA Astrophysics Data System (ADS)

    Sadri Irani, Samaneh; Luzzatto-Fegiz, Paolo

    2017-11-01

    As noted by the 2014 IPCC report, while the rise in atmospheric CO2 would be slowed by emissions reductions, removing atmospheric CO2 is an important part of possible paths to climate stabilization. Direct Air Capture of CO2 with chemicals (DAC) is one of several proposed carbon capture technologies. There is an ongoing debate on whether DAC is an economically viable approach to alleviate climate change. In addition, like all air capture strategies, DAC is strongly constrained by the net-carbon problem, namely the need to control CO2 emissions associated with the capture process (for example, if DAC not powered by renewables). Research to date has focused on the chemistry and economics of individual DAC devices. However, the fluid mechanics of their large-scale deployment has not been examined in the literature, to the best of our knowledge. In this presentation, we develop a model for flow through an array of DAC devices, varying their lateral extent and their separation. We build on a recent theory of canopy flows, introducing terms for CO2 entrainment into the array boundary layer, and transport into the farm. In addition, we examine the possibility of driving flow passively by wind, thereby reducing energy consumption. The optimal operational design is established considering the total cost, drag force, energy consumption and total CO2 capture.

  10. Uncertainty Quantification for CO2-Enhanced Oil Recovery

    NASA Astrophysics Data System (ADS)

    Dai, Z.; Middleton, R.; Bauman, J.; Viswanathan, H.; Fessenden-Rahn, J.; Pawar, R.; Lee, S.

    2013-12-01

    CO2-Enhanced Oil Recovery (EOR) is currently an option for permanently sequestering CO2 in oil reservoirs while increasing oil/gas productions economically. In this study we have developed a framework for understanding CO2 storage potential within an EOR-sequestration environment at the Farnsworth Unit of the Anadarko Basin in northern Texas. By coupling a EOR tool--SENSOR (CEI, 2011) with a uncertainty quantification tool PSUADE (Tong, 2011), we conduct an integrated Monte Carlo simulation of water, oil/gas components and CO2 flow and reactive transport in the heterogeneous Morrow formation to identify the key controlling processes and optimal parameters for CO2 sequestration and EOR. A global sensitivity and response surface analysis are conducted with PSUADE to build numerically the relationship among CO2 injectivity, oil/gas production, reservoir parameters and distance between injection and production wells. The results indicate that the reservoir permeability and porosity are the key parameters to control the CO2 injection, oil and gas (CH4) recovery rates. The distance between the injection and production wells has large impact on oil and gas recovery and net CO2 injection rates. The CO2 injectivity increases with the increasing reservoir permeability and porosity. The distance between injection and production wells is the key parameter for designing an EOR pattern (such as a five (or nine)-spot pattern). The optimal distance for a five-spot-pattern EOR in this site is estimated from the response surface analysis to be around 400 meters. Next, we are building the machinery into our risk assessment framework CO2-PENS to utilize these response surfaces and evaluate the operation risk for CO2 sequestration and EOR at this site.

  11. The e-beam sustained CO2 laser amplifier

    NASA Technical Reports Server (NTRS)

    Brown, M. J.; Shaw, S. R.; Evans, M. H.; Smith, I. M.; Holman, W.

    1990-01-01

    The design features of an e-beam sustained CO2 amplifier are described. The amplifier is designed specifically as a catalyst test-bed to study the performance of room temperature precious metal CO-oxidation catalysts under e-beam sustained operation. The amplifier has been designed to provide pulse durations of 30 microseconds in a discharge volume of 2 litres. With a gas flow velocity of 2 metres per second, operation at repetition rates of 10 Hz is accommodated. The system is designed for sealed-off operation and a catalyst bed is housed in the gas circulation system downstream from the discharge region. CO and oxygen monitors are used for diagnosis of gas composition in the amplifier so that catalyst performance can be monitored in situ during sealed lifetests.

  12. Pore-scale Modeling of CO2 Local Trapping in Heterogeneous Porous Media with Inter-granular Cements

    NASA Astrophysics Data System (ADS)

    Wang, D.; Li, Y.

    2017-12-01

    Based on pore-scale modeling of CO2/brine multiphase flow in heterogeneous porous media with inter-granular cements, we numerically analyze the effects of cement-modified pore structure on CO2 local trapping. Results indicate: 1) small pore throat is the main reason for causing CO2 local trapping in front of low-porosity layers (namely dense layers) formed by inter-granular cements; 2) in the case of the same pore throat size, the smaller particle size can increase the number of flow paths for CO2 plume and equivalently enhances local permeability, which may counteract the impediment of high capillary pressure on CO2 migration to some extent and consequently disables CO2 local capillary trapping; 3) the isolated pores by inter-granular cements can lead to dramatic reduction of CO2 saturation inside the dense layers, whereas the change of connectivity of some pores due to the cements can increase CO2 accumulation in front of the dense layers by lowering the displacement area of CO2 plume.

  13. Clustered metallothionein genes are co-regulated in rice and ectopic expression of OsMT1e-P confers multiple abiotic stress tolerance in tobacco via ROS scavenging

    PubMed Central

    2012-01-01

    Background Metallothioneins (MT) are low molecular weight, cysteine rich metal binding proteins, found across genera and species, but their function(s) in abiotic stress tolerance are not well documented. Results We have characterized a rice MT gene, OsMT1e-P, isolated from a subtractive library generated from a stressed salinity tolerant rice genotype, Pokkali. Bioinformatics analysis of the rice genome sequence revealed that this gene belongs to a multigenic family, which consists of 13 genes with 15 protein products. OsMT1e-P is located on chromosome XI, away from the majority of other type I genes that are clustered on chromosome XII. Various members of this MT gene cluster showed a tight co-regulation pattern under several abiotic stresses. Sequence analysis revealed the presence of conserved cysteine residues in OsMT1e-P protein. Salinity stress was found to regulate the transcript abundance of OsMT1e-P in a developmental and organ specific manner. Using transgenic approach, we found a positive correlation between ectopic expression of OsMT1e-P and stress tolerance. Our experiments further suggest ROS scavenging to be the possible mechanism for multiple stress tolerance conferred by OsMT1e-P. Conclusion We present an overview of MTs, describing their gene structure, genome localization and expression patterns under salinity and development in rice. We have found that ectopic expression of OsMT1e-P enhances tolerance towards multiple abiotic stresses in transgenic tobacco and the resultant plants could survive and set viable seeds under saline conditions. Taken together, the experiments presented here have indicated that ectopic expression of OsMT1e-P protects against oxidative stress primarily through efficient scavenging of reactive oxygen species. PMID:22780875

  14. Clustered metallothionein genes are co-regulated in rice and ectopic expression of OsMT1e-P confers multiple abiotic stress tolerance in tobacco via ROS scavenging.

    PubMed

    Kumar, Gautam; Kushwaha, Hemant Ritturaj; Panjabi-Sabharwal, Vaishali; Kumari, Sumita; Joshi, Rohit; Karan, Ratna; Mittal, Shweta; Pareek, Sneh L Singla; Pareek, Ashwani

    2012-07-10

    Metallothioneins (MT) are low molecular weight, cysteine rich metal binding proteins, found across genera and species, but their function(s) in abiotic stress tolerance are not well documented. We have characterized a rice MT gene, OsMT1e-P, isolated from a subtractive library generated from a stressed salinity tolerant rice genotype, Pokkali. Bioinformatics analysis of the rice genome sequence revealed that this gene belongs to a multigenic family, which consists of 13 genes with 15 protein products. OsMT1e-P is located on chromosome XI, away from the majority of other type I genes that are clustered on chromosome XII. Various members of this MT gene cluster showed a tight co-regulation pattern under several abiotic stresses. Sequence analysis revealed the presence of conserved cysteine residues in OsMT1e-P protein. Salinity stress was found to regulate the transcript abundance of OsMT1e-P in a developmental and organ specific manner. Using transgenic approach, we found a positive correlation between ectopic expression of OsMT1e-P and stress tolerance. Our experiments further suggest ROS scavenging to be the possible mechanism for multiple stress tolerance conferred by OsMT1e-P. We present an overview of MTs, describing their gene structure, genome localization and expression patterns under salinity and development in rice. We have found that ectopic expression of OsMT1e-P enhances tolerance towards multiple abiotic stresses in transgenic tobacco and the resultant plants could survive and set viable seeds under saline conditions. Taken together, the experiments presented here have indicated that ectopic expression of OsMT1e-P protects against oxidative stress primarily through efficient scavenging of reactive oxygen species.

  15. Impact of fluid injection velocity on CO2 saturation and pore pressure in porous sandstone

    NASA Astrophysics Data System (ADS)

    Kitamura, Keigo; Honda, Hiroyuki; Takaki, Shinnosuke; Imasato, Mitsunori; Mitani, Yasuhiro

    2017-04-01

    The elucidation of CO2 behavior in sandstone is an essential issue to understand the fate of injecting CO2 in reservoirs. Injected CO2 invades pore spaces and replaces with resident brine and forms complex two-phase flow with brine. It is considered that this complex CO2 flow arises CO2 saturation (SCO_2)and pore fluid pressure(Pp) and makes various types of CO2 distribution pattern in pore space. The estimation of SCO_2 in the reservoir is one of important task in CCS projects. Fluid pressure (Pp) is also important to estimate the integrity of CO2 reservoir and overlying cap rocks. Generally, elastic waves are used to monitor the changes of SCO_2. Previous experimental and theoretical studies indicated that SCO_2 and Pp are controlled by the fluid velocity (flow rate) of invaded phase. In this study, we conducted the CO2 injection test for Berea sandstone (φ=18.1{%}) under deep CO2 reservoir conditions (confining pressure: 20MPa; temperature: 40 rC). We try to estimate the changes of SCO_2 and Pp with changing CO2 injection rate (FR) from 10 to 5000 μ l/min for Berea sandstone. P-wave velocities (Vp) are also measured during CO2 injection test and used to investigate the relationships between SCO2 and these geophysical parameters. We set three Vp-measurement channels (ch.1, ch2 and ch.3 from the bottom) monitor the CO2 behavior. The result shows step-wise SCO_2 changes with increasing FR from 9 to 25 {%} in low-FR condition (10-500 μ l/min). Vp also shows step wise change from ch1 to ch.3. The lowermost channel (ch.1) indicates that Vp-reduction stops around 4{%} at 10μ m/min condition. However, ch.3 changes slightly from 4{%} at 10 μ l/min to 5{%} at 100 μ l/min. On the other hand, differential Pp (Δ P) dose not shows obvious changes from 10kPa to 30kPa. Over 1000 μ l/min, SCO_2 increases from 35 to 47 {%}. Vp of all channels show slight reductions and Vp-reductions reach constant values as 8{%}, 6{%} and 8{%}, respectively at 5000{}μ l/min. On the other

  16. [Study on supercritical CO2 extraction of xiaoyaosan and its GC-MS fingerprint].

    PubMed

    Zuo, Ya-Mei; Tian, Jun-Sheng; Guo, Xiao-Qing; Zhou, Yu-Zhi; Gao, Xiao-Xia; Qin, Xue-Mei

    2014-02-01

    To determine the optimum conditions of supercritical CO2 extraction of Xiaoyaosan, and establish its fingerprint by gas chromatography-mass spectrometry (GC-MS), the yield of extract were investigated, an orthogonal test was used to quantify the effects of extraction temperature, pressure, CO2 flow rate and time, and fingerprint analysis of different batches of extracts were by GC-MS. The optimal extraction conditions were determined as follows: extraction pressure 20 MPa, extraction temperature 50 degrees C, CO2 flow rate 25 kg x h(-1), extraction time 3 h, and average yield 2.2%. The GC-MS fingerprint was established and 27 common peaks were found, whose contents add up to 81.89% of the total peak area. Among them, 21 compounds were identified, accounting for 53.20% of the total extract. The extraction process is reasonable and favorable for industrial production. The GC-MS method is accurate, reliable, reproducible, and can be used for quality control of supercritical CO2 extract from Xiaoyaosan.

  17. Sample environment for in situ synchrotron XRD measurements for CO2 interaction with subsurface materials

    NASA Astrophysics Data System (ADS)

    Elbakhshwan, M.; Gill, S.; Weidner, R.; Ecker, L.

    2017-12-01

    Sequestration of CO2 in geological formations requires a deep understanding of its interaction with the cement-casing components in the depleted oil and gas wells. Portland cement is used to seal the wellbores; however it tends to interact with the CO2. Therefore it is critical to investigate the wellbore integrity over long term exposure to CO2. Studies showed that, CO2 leakage is due to the flow through the casing-cement microannulus, cement-cement fractures, or the cement-caprock interface. The objective of this work is to gain a better understanding of the dissolution process of the cement-casing in the CO2 flow channels alongside with the carbonation reactions at the interfaces using XRF, XANES and X-ray tomography techniques. In this study, a synthetic wellbore system, consisting of cement with an embedded rectangular length of steel casing that had grooves to accommodate fluid flow, was used to investigate the casing-cement microannulus through core-flood experiments. The objective of this work is to gain a better understanding of the dissolution process of the cement-casing in the CO2 flow channels alongside with the carbonation reactions at the interfaces using a sample environment designed and built for in situ X-ray diffraction in the National Synchrotron Light Source II (NSLS II). The formation of carbonate phases at cement -fluid and cement-steel/fluid interfaces will be monitored in real time. Samples may be exposed to super critical CO2 at pressures above 1100 psi and temperatures around 50°C. The reaction cell is built from hastealloy to provide corrosion resistance, while the experimental temperature and pressure are controlled with thermocouples and pressure vessel.

  18. Mycobacterium ulcerans dynamics in aquatic ecosystems are driven by a complex interplay of abiotic and biotic factors

    PubMed Central

    Garchitorena, Andrés; Guégan, Jean-François; Léger, Lucas; Eyangoh, Sara; Marsollier, Laurent; Roche, Benjamin

    2015-01-01

    Host–parasite interactions are often embedded within complex host communities and can be influenced by a variety of environmental factors, such as seasonal variations in climate or abiotic conditions in water and soil, which confounds our understanding of the main drivers of many multi-host pathogens. Here, we take advantage of a combination of large environmental data sets on Mycobacterium ulcerans (MU), an environmentally persistent microorganism associated to freshwater ecosystems and present in a large variety of aquatic hosts, to characterize abiotic and biotic factors driving the dynamics of this pathogen in two regions of Cameroon. We find that MU dynamics are largely driven by seasonal climatic factors and certain physico-chemical conditions in stagnant and slow-flowing ecosystems, with an important role of pH as limiting factor. Furthermore, water conditions can modify the effect of abundance and diversity of aquatic organisms on MU dynamics, which suggests a different contribution of two MU transmission routes for aquatic hosts (trophic vs environmental transmission) depending on local abiotic factors. DOI: http://dx.doi.org/10.7554/eLife.07616.001 PMID:26216042

  19. Characterization of a common wheat (Triticum aestivum L.) TaSnRK2.7 gene involved in abiotic stress responses

    PubMed Central

    Zhang, Hongying; Mao, Xinguo; Jing, Ruilian; Chang, Xiaoping; Xie, Huimin

    2011-01-01

    Sucrose non-fermenting-1-related protein kinase 2 (SnRK2) plays a key role in the plant stress signalling transduction pathway via phosphorylation. Here, a SnRK2 member of common wheat, TaSnRK2.7, was cloned and characterized. Southern blot analysis suggested that the common wheat genome contains three copies of TaSnRK2.7. Subcellular localization showed the presence of TaSnRK2.7 in the cell membrane, cytoplasm, and nucleus. Expression patterns revealed that TaSnRK2.7 is expressed strongly in roots, and responds to polyethylene glycol, NaCl, and cold stress, but not to abscisic acid (ABA) application, suggesting that TaSnRK2.7 might participate in non-ABA-dependent signal transduction pathways. TaSnRK2.7 was transferred to Arabidopsis under the control of the CaMV-35S promoter. Function analysis showed that TaSnRK2.7 is involved in carbohydrate metabolism, decreasing osmotic potential, enhancing photosystem II activity, and promoting root growth. Its overexpression results in enhanced tolerance to multi-abiotic stress. Therefore, TaSnRK2.7 is a multifunctional regulatory factor in plants, and has the potential to be utilized in transgenic breeding to improve abiotic stress tolerance in crop plants. PMID:21030389

  20. CO2 adhesion on hydrated mineral surfaces.

    PubMed

    Wang, Shibo; Tao, Zhiyuan; Persily, Sara M; Clarens, Andres F

    2013-10-15

    Hydrated mineral surfaces in the environment are generally hydrophilic but in certain cases can strongly adhere CO2, which is largely nonpolar. This adhesion can significantly alter the wettability characteristics of the mineral surface and consequently influence capillary/residual trapping and other multiphase flow processes in porous media. Here, the conditions influencing adhesion between CO2 and homogeneous mineral surfaces were studied using static pendant contact angle measurements and captive advancing/receding tests. The prevalence of adhesion was sensitive to both surface roughness and aqueous chemistry. Adhesion was most widely observed on phlogopite mica, silica, and calcite surfaces with roughness on the order of ~10 nm. The incidence of adhesion increased with ionic strength and CO2 partial pressure. Adhesion was very rarely observed on surfaces equilibrated with brines containing strong acid or base. In advancing/receding contact angle measurements, adhesion could increase the contact angle by a factor of 3. These results support an emerging understanding of adhesion of, nonpolar nonaqueous phase fluids on mineral surfaces influenced by the properties of the electrical double layer in the aqueous phase film and surface functional groups between the mineral and CO2.

  1. Pore scale study of multiphase multicomponent reactive transport during CO2 dissolution trapping

    NASA Astrophysics Data System (ADS)

    Chen, Li; Wang, Mengyi; Kang, Qinjun; Tao, Wenquan

    2018-06-01

    Solubility trapping is crucial for permanent CO2 sequestration in deep saline aquifers. For the first time, a pore-scale numerical method is developed to investigate coupled scCO2-water two-phase flow, multicomponent (CO2(aq), H+, HCO3-, CO32- and OH-) mass transport, heterogeneous interfacial dissolution reaction, and homogeneous dissociation reactions. Pore-scale details of evolutions of multiphase distributions and concentration fields are presented and discussed. Time evolutions of several variables including averaged CO2(aq) concentration, scCO2 saturation, and pH value are analyzed. Specific interfacial length, an important variable which cannot be determined but is required by continuum models, is investigated in detail. Mass transport coefficient or efficient dissolution rate is also evaluated. The pore-scale results show strong non-equilibrium characteristics during solubility trapping due to non-uniform distributions of multiphase as well as slow mass transport process. Complicated coupling mechanisms between multiphase flow, mass transport and chemical reactions are also revealed. Finally, effects of wettability are also studied. The pore-scale studies provide deep understanding of non-linear non-equilibrium multiple physicochemical processes during CO2 solubility trapping processes, and also allow to quantitatively predict some important empirical relationships, such as saturation-interfacial surface area, for continuum models.

  2. Coordinated Actions of Glyoxalase and Antioxidant Defense Systems in Conferring Abiotic Stress Tolerance in Plants

    PubMed Central

    Hasanuzzaman, Mirza; Nahar, Kamrun; Hossain, Md. Shahadat; Mahmud, Jubayer Al; Rahman, Anisur; Inafuku, Masashi; Oku, Hirosuke; Fujita, Masayuki

    2017-01-01

    Being sessile organisms, plants are frequently exposed to various environmental stresses that cause several physiological disorders and even death. Oxidative stress is one of the common consequences of abiotic stress in plants, which is caused by excess generation of reactive oxygen species (ROS). Sometimes ROS production exceeds the capacity of antioxidant defense systems, which leads to oxidative stress. In line with ROS, plants also produce a high amount of methylglyoxal (MG), which is an α-oxoaldehyde compound, highly reactive, cytotoxic, and produced via different enzymatic and non-enzymatic reactions. This MG can impair cells or cell components and can even destroy DNA or cause mutation. Under stress conditions, MG concentration in plants can be increased 2- to 6-fold compared with normal conditions depending on the plant species. However, plants have a system developed to detoxify this MG consisting of two major enzymes: glyoxalase I (Gly I) and glyoxalase II (Gly II), and hence known as the glyoxalase system. Recently, a novel glyoxalase enzyme, named glyoxalase III (Gly III), has been detected in plants, providing a shorter pathway for MG detoxification, which is also a signpost in the research of abiotic stress tolerance. Glutathione (GSH) acts as a co-factor for this system. Therefore, this system not only detoxifies MG but also plays a role in maintaining GSH homeostasis and subsequent ROS detoxification. Upregulation of both Gly I and Gly II as well as their overexpression in plant species showed enhanced tolerance to various abiotic stresses including salinity, drought, metal toxicity, and extreme temperature. In the past few decades, a considerable amount of reports have indicated that both antioxidant defense and glyoxalase systems have strong interactions in conferring abiotic stress tolerance in plants through the detoxification of ROS and MG. In this review, we will focus on the mechanisms of these interactions and the coordinated action of

  3. Ar + CO2 and He + CO2 Plasmas in ASTRAL

    NASA Astrophysics Data System (ADS)

    Boivin, R. F.; Gardner, A.; Munoz, J.; Kamar, O.; Loch, S.

    2007-11-01

    Spectroscopy study of the ASTRAL helicon plasma source running Ar + CO2 and He + CO2 gas mixes is presented. ASTRAL produces plasmas with the following parameters: ne = 10^10 - 10^13 cm-3, Te = 2 - 10 eV and Ti = 0.03 - 0.5 eV, B-field <= 1.3 kGauss, rf power <= 2 kWatt. A 0.33 m scanning monochromator is used for this study. Using Ar + CO2 gas mixes, very different plasmas are observed as the concentration of CO2 is changed. At low CO2 concentration, the bluish plasma is essentially atomic and argon transitions dominate the spectra. Weak C I and O I lines are present in the 750 - 1000 nm range. At higher CO2 concentration, the plasma becomes essentially molecular and is characterized by intense, white plasma columns. Here, spectra are filled with molecular bands (CO2, CO2^+, CO and CO^+). Limited molecular dissociative excitation processes associated with the production of C I and O I emission are also observed. On the other hand, He + CO2 plasmas are different. Here, rf matches are only possible at low CO2 concentration. Under these conditions, the spectra are characterized by strong C I and O I transitions with little or no molecular bands. Strong dissociative processes observed in these plasmas can be link to the high Te associated with He plasmas. An analysis of the spectra with possible scientific and industrial applications will be presented.

  4. Bioinformatic and expression analyses on carotenoid dioxygenase genes in fruit development and abiotic stress responses in Fragaria vesca.

    PubMed

    Wang, Yong; Ding, Guanqun; Gu, Tingting; Ding, Jing; Li, Yi

    2017-08-01

    Carotenoid dioxygenases, including 9-cis-epoxycarotenoid dioxygenases (NCEDs) and carotenoid cleavage dioxygenases (CCDs), can selectively cleave carotenoids into various apocarotenoid products that play important roles in fleshy fruit development and abiotic stress response. In this study, we identified 12 carotenoid dioxygenase genes in diploid strawberry Fragaria vesca, and explored their evolution with orthologous genes from nine other species. Phylogenetic analyses suggested that the NCED and CCDL groups moderately expanded during their evolution, whereas gene numbers of the CCD1, CCD4, CCD7, and CCD8 groups maintained conserved. We characterized the expression profiles of FveNCED and FveCCD genes during flower and fruit development, and in response to several abiotic stresses. FveNCED1 expression positively responded to osmotic, cold, and heat stresses, whereas FveNCED2 was only induced under cold stress. In contrast, FveNCED2 was the unique gene highly and continuously increasing in receptacle during fruit ripening, which co-occurred with the increase in endogenous abscisic acid (ABA) content previously reported in octoploid strawberry. The differential expression patterns suggested that FveNCED1 and FveNCED2 were key genes for ABA biosynthesis in abiotic stress responses and fruit ripening, respectively. FveCCD1 exhibited the highest expression in most stages of flower and fruit development, while the other FveCCDs were expressed in a subset of stages and tissues. Our study suggests distinct functions of FveNCED and FveCCD genes in fruit development and stress responses and lays a foundation for future study to understand the roles of these genes and their metabolites, including ABA and other apocarotenoid products, in the growth and development of strawberry.

  5. A new set-up for simultaneous high-precision measurements of CO2, δ13C-CO2 and δ18O-CO2 on small ice core samples

    NASA Astrophysics Data System (ADS)

    Jenk, Theo Manuel; Rubino, Mauro; Etheridge, David; Ciobanu, Viorela Gabriela; Blunier, Thomas

    2016-08-01

    Palaeoatmospheric records of carbon dioxide and its stable carbon isotope composition (δ13C) obtained from polar ice cores provide important constraints on the natural variability of the carbon cycle. However, the measurements are both analytically challenging and time-consuming; thus only data exist from a limited number of sampling sites and time periods. Additional analytical resources with high analytical precision and throughput are thus desirable to extend the existing datasets. Moreover, consistent measurements derived by independent laboratories and a variety of analytical systems help to further increase confidence in the global CO2 palaeo-reconstructions. Here, we describe our new set-up for simultaneous measurements of atmospheric CO2 mixing ratios and atmospheric δ13C and δ18O-CO2 in air extracted from ice core samples. The centrepiece of the system is a newly designed needle cracker for the mechanical release of air entrapped in ice core samples of 8-13 g operated at -45 °C. The small sample size allows for high resolution and replicate sampling schemes. In our method, CO2 is cryogenically and chromatographically separated from the bulk air and its isotopic composition subsequently determined by continuous flow isotope ratio mass spectrometry (IRMS). In combination with thermal conductivity measurement of the bulk air, the CO2 mixing ratio is calculated. The analytical precision determined from standard air sample measurements over ice is ±1.9 ppm for CO2 and ±0.09 ‰ for δ13C. In a laboratory intercomparison study with CSIRO (Aspendale, Australia), good agreement between CO2 and δ13C results is found for Law Dome ice core samples. Replicate analysis of these samples resulted in a pooled standard deviation of 2.0 ppm for CO2 and 0.11 ‰ for δ13C. These numbers are good, though they are rather conservative estimates of the overall analytical precision achieved for single ice sample measurements. Facilitated by the small sample requirement

  6. An Advanced Reservoir Simulator for Tracer Transport in Multicomponent Multiphase Compositional Flow and Applications to the Cranfield CO2 Sequestration Site

    NASA Astrophysics Data System (ADS)

    Moortgat, J.

    2015-12-01

    Reservoir simulators are widely used to constrain uncertainty in the petrophysical properties of subsurface formations by matching the history of injection and production data. However, such measurements may be insufficient to uniquely characterize a reservoir's properties. Monitoring of natural (isotopic) and introduced tracers is a developing technology to further interrogate the subsurface for applications such as enhanced oil recovery from conventional and unconventional resources, and CO2 sequestration. Oak Ridge National Laboratory has been piloting this tracer technology during and following CO2 injection at the Cranfield, Mississippi, CO2 sequestration test site. Two campaigns of multiple perfluorocarbon tracers were injected together with CO2 and monitored at two wells at 68 m and 112 m from the injection site. The tracer data suggest that multiple CO2 flow paths developed towards the monitoring wells, indicative of either channeling through high permeability pathways or of fingering. The results demonstrate that tracers provide an important complement to transient pressure data. Numerical modeling is essential to further explain and interpret the observations. To aid the development of tracer technology, we enhanced a compositional multiphase reservoir simulator to account for tracer transport. Our research simulator uses higher-order finite element (FE) methods that can capture the small-scale onset of fingering on the coarse grids required for field-scale modeling, and allows for unstructured grids and anisotropic heterogeneous permeability fields. Mass transfer between fluid phases and phase behavior are modeled with rigorous equation-of-state based phase-split calculations. We present our tracer simulator and preliminary results related to the Cranfield experiments. Applications to noble gas tracers in unconventional resources are presented by Darrah et al.

  7. Elevated CO2 improves lipid accumulation by increasing carbon metabolism in Chlorella sorokiniana.

    PubMed

    Sun, Zhilan; Chen, Yi-Feng; Du, Jianchang

    2016-02-01

    Supplying microalgae with extra CO2 is a promising means for improving lipid production. The molecular mechanisms involved in lipid accumulation under conditions of elevated CO2, however, remain to be fully elucidated. To understand how elevated CO2 improves lipid production, we performed sequencing of Chlorella sorokiniana LS-2 cellular transcripts during growth and compared transcriptional dynamics of genes involved in carbon flow from CO2 to triacylglycerol. These analyses identified the majority genes of carbohydrate metabolism and lipid biosynthesis pathways in C. sorokiniana LS-2. Under high doses of CO2 , despite down-regulation of most de novo fatty acid biosynthesis genes, genes involved in carbohydrate metabolic pathways including carbon fixation, chloroplastic glycolysis, components of the pyruvate dehydrogenase complex (PDHC) and chloroplastic membrane transporters were upexpressed at the prolonged lipid accumulation phase. The data indicate that lipid production is largely independent of de novo fatty acid synthesis. Elevated CO2 might push cells to channel photosynthetic carbon precursors into fatty acid synthesis pathways, resulting in an increase of overall triacylglycerol generation. In support of this notion, genes involved in triacylglycerol biosynthesis were substantially up-regulated. Thus, elevated CO2 may influence regulatory dynamics and result in increased carbon flow to triacylglycerol, thereby providing a feasible approach to increase lipid production in microalgae. © 2015 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

  8. Modeling of Compositional Effects of Foam Assisted CO2 Storage Processes

    NASA Astrophysics Data System (ADS)

    Naderi Beni, A.; Varavei, A.; Farajzadeh, R.; Delshad, M.

    2012-12-01

    Foaming of carbon dioxide (CO2, e.g. from fossil-fuel power plants) has been proposed as a possible strategy to resolve the limitations of direct disposal of CO2 into (saline) aquifers. Such limitations include gravity segregation that may damage the caprock and aquifer rock property alteration as a result of geochemical interactions. Foam may also block the CO2 leakage paths, resulting in an overall storage security enhancement. In this regard, specific aspects of composition and type of gas (N2 vs. CO2) may affect the foaming properties of gas-surfactant systems. The aim of this study is to determine these effects on the foaming properties of gas-surfactant solutions. To this end, we study the physics of foam assisted CO2 storage by modeling coreflood experiments. Different options such as simplified population balance foam model and a table-look-up approach were used to couple the fluid flow and mass transport equations in a reservoir simulator. Both laboratory and numerical results show that three regions along the flow direction can be distinguished: (i) an upstream region characterized by low liquid saturation, (ii) a region downstream of the foam front where the liquid saturation is still unchanged with a value of one and (iii) a frontal region characterized by a mixing of flowing foam and liquid, exhibiting fine fingering effects. It is also shown that the extent of the fingering behavior caused by the rock heterogeneity depends on foam strength. Additionally, permeation of gas through foam films is a strong function of water salinity and appears to have significant impact on foam in CO2 storage. It further turns out that the amount of dissolved CO2 in brine can be considerable and, therefore, the effect of water solubility cannot be neglected in simulation studies. In summary, the differences in the foaming behavior of nitrogen and carbon dioxide can be explained by the differences in their physical properties of solubility in water, interfacial tension, p

  9. [Transgenic rice breeding for abiotic stress tolerance--present and future].

    PubMed

    Zhao, Feng-Yun; Zhang, Hui

    2007-01-01

    Environmental stresses and the continuing deterioration of arable land, along with an explosive increase in world population, pose serious threats to global agricultural production and food security. Improving the tolerance of the major crop plants to abiotic stresses has been a main goal in agriculture for a long time. As rice is considered one of the major crops, the development of new cultivars with enhanced abiotic stress-tolerance will undoubtedly have an important effect on global food production. The transgenic approach offers an attractive alternative to conventional techniques for the genetic improvement of rice cultivars. In recent years, an array of stress-related genes has already been transferred to rice to improve its resistance against abiotic stresses. Many transgenic rice plants with enhanced abiotic stress-tolerance have been obtained. This article focuses on the progress in the study of abiotic stress tolerance in transgenic rice breeding.

  10. Autotrophic and heterotrophic soil respiration determined with trenching, soil CO2 fluxes and 13CO2/12CO2 concentration gradients in a boreal forest ecosystem

    NASA Astrophysics Data System (ADS)

    Pumpanen, Jukka; Shurpali, Narasinha; Kulmala, Liisa; Kolari, Pasi; Heinonsalo, Jussi

    2017-04-01

    Soil CO2 efflux forms a substantial part of the ecosystem carbon balance, and it can contribute more than half of the annual ecosystem respiration. Recently assimilated carbon which has been fixed in photosynthesis during the previous days plays an important role in soil CO2 efflux, and its contribution is seasonally variable. Moreover, the recently assimilated C has been shown to stimulate the decomposition of recalcitrant C in soil and increase the mineralization of nitrogen, the most important macronutrient limiting gross primary productivity (GPP) in boreal ecosystems. Podzolic soils, typical in boreal zone, have distinctive layers with different biological and chemical properties. The biological activity in different soil layers has large seasonal variation due to vertical gradient in temperature, soil organic matter and root biomass. Thus, the source of CO2 and its components have a vertical gradient which is seasonally variable. The contribution of recently assimilated C and its seasonal as well as spatial variation in soil are difficult to assess without disturbing the system. The most common method of partitioning soil respiration into its components is trenching which entails the roots being cut or girdling where the flow of carbohydrates from the canopy to roots has been isolated by cutting of the phloem. Other methods for determining the contribution of autotrophic (Ra) and heterotrophic (Rh) respiration components in soil CO2 efflux are pulse labelling with 13CO2 or 14CO2 or the natural abundance of 13C and/or 14C isotopes. Also differences in seasonal and short-term temperature response of soil respiration have been used to separate Ra and Rh. We compared the seasonal variation in Ra and Rh using the trenching method and differences between seasonal and short-term temperature responses of soil respiration. I addition, we estimated the vertical variation in soil biological activity using soil CO2 concentration and the natural abundance of 13C and 12C

  11. Convective Instability and Mass Transport of the Diffusion Layer in CO2 Sequestration

    NASA Astrophysics Data System (ADS)

    Backhaus, S.

    2011-12-01

    The long-term fate of supercritical (sc) CO2 in saline aquifers is critical to the security of carbon sequestration, an important option for eliminating or reducing the emissions of this most prevalent greenhouse gas. scCO2 is less dense than brine and floats to the top of the aquifer where it is trapped in a metastable state by a geologic feature such as a low permeability cap rock. Dissolution into the underlying brine creates a CO2-brine mixture that is denser than brine, eliminating buoyancy and removing the threat of CO2 escaping back to the atmosphere. If molecular diffusion were the only dissolution mechanism, the CO2 waste stream from a typical large coal-fired electrical power plant may take upward of 10,000 years to no longer pose a threat, however, a convective instability of the dense diffusion boundary layer between the scCO2 and the brine can dramatically increase the dissolution rates, shortening the lifetime of the scCO2 waste pool. We present results of 2D and 3D similitude-correct, laboratory-scale experiments using an analog fluid system. The experiments and flow visualization reveal the onset of the convective instability, the dynamics of the fluid flows during the convective processes, and the long-term mass transfer rates.

  12. Optical discharge with absorption of repetitive CO{sub 2} laser pulses in supersonic air flow: wave structure and condition of a quasi-steady state

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

    Bobarykina, T A; Malov, A N; Orishich, A M

    We report a study of the wave structure formed by an optical discharge plasma upon the absorption of repetitively pulsed CO{sub 2} laser radiation in a supersonic (M = 1.36) air flow. Experimental data are presented on the configuration of the head shock wave and the geometry and characteristic dimensions of breakdown regions behind a laser plasma pulsating in the flow at a frequency of up to 150 kHz. The data are compared to calculation in a point explosion model with allowance for counterpressure, which makes it possible to identify the relationship between laser radiation and supersonic flow parameters thatmore » ensures quasisteady- state energy delivery and is necessary for extending the possibilities of controlling the structure of supersonic flows. (interaction of laser radiation with matter)« less

  13. Impact of CO2 injection protocol on fluid-solid reactivity: high-pressure and temperature microfluidic experiments in limestone

    NASA Astrophysics Data System (ADS)

    Jimenez-Martinez, Joaquin; Porter, Mark; Carey, James; Guthrie, George; Viswanathan, Hari

    2017-04-01

    Geological sequestration of CO2 has been proposed in the last decades as a technology to reduce greenhouse gas emissions to the atmosphere and mitigate the global climate change. However, some questions such as the impact of the protocol of CO2 injection on the fluid-solid reactivity remain open. In our experiments, two different protocols of injection are compared at the same conditions (8.4 MPa and 45 C, and constant flow rate 0.06 ml/min): i) single phase injection, i.e., CO2-saturated brine; and ii) simultaneous injection of CO2-saturated brine and scCO2. For that purpose, we combine a unique high-pressure/temperature microfluidics experimental system, which allows reproducing geological reservoir conditions in geo-material substrates (i.e., limestone, Cisco Formation, Texas, US) and high resolution optical profilometry. Single and multiphase flow through etched fracture networks were optically recorded with a microscope, while processes of dissolution-precipitation in the etched channels were quantified by comparison of the initial and final topology of the limestone micromodels. Changes in hydraulic conductivity were quantified from pressure difference along the micromodel. The simultaneous injection of CO2-saturated brine and scCO2, reduced the brine-limestone contact area and also created a highly heterogeneous velocity field (i.e., low velocities regions or stagnation zones, and high velocity regions or preferential paths), reducing rock dissolution and enhancing calcite precipitation. The results illustrate the contrasting effects of single and multiphase flow on chemical reactivity and suggest that multiphase flow by isolating parts of the flow system can enhance CO2 mineralization.

  14. Experimental Study of Abiotic Organic Synthesis at High Temperature and Pressure Conditions: Carbon Isotope and Mineral Surface Characterizations

    NASA Astrophysics Data System (ADS)

    Fu, Q.; Socki, R. A.; Niles, P. B.

    2010-12-01

    Abiotic organic synthesis processes have been proposed as potential mechanisms for methane generation in subseafloor hydrothermal systems on Earth, and on other planets. To better understand the detailed reaction pathways and carbon isotope fractionations in this process under a wide range of physical and chemical conditions, hydrothermal experiments at high temperature (750 °C) and pressure (0.55 GPa) were performed using piston cylinder apparatus. Formic acid was used as the source of CO2 and H2, and magnetite was the mineral catalyst. The chemical and carbon isotopic compositions of dissolved organic products were determined by GC-C-MS-IRMS, while organic intermediaries on the mineral catalyst were characterized by Pyrolysis-GC-MS. Among experimental products, dissolved CO2 was the dominant carbon species with a relative abundance of 88 mol%. Dissolved CH4 and C2H6 were also identified with a mole ratio of CH4 over C2H6 of 15:1. No dissolved CO was detected in the experiment, which might be attributable to the loss of H2 through the Au capsule used in the experiments at high temperature and pressure conditions and corresponding conversion of CO to CO2 by the water-gas shift reaction. Carbon isotope results showed that the δ13C values of CH4 and C2H6 were -50.3‰ and -39.3‰ (V-PDB), respectively. CO2 derived from decarboxylation of formic acid had a δ13C value of -19.2‰, which was 3.2‰ heavier than its source, formic acid. The δ13C difference between CO2 and CH4 was 31.1‰, which was higher than the value of 9.4‰ calculated from theoretical isotopic equilibrium predictions at experimental conditions, suggesting the presence of a kinetic isotope effect. This number was also higher than the values (4.6 to 27.1‰) observed in similar experiments previously performed at 400 °C and 50 MPa with longer reaction times. CH4 is 11.0‰ less enriched in 13C than C2H6. Alcohols were observed as carbon compounds on magnetite surfaces by Pyrolysis-GC-MS, which

  15. Experimental Study of Abiotic Organic Synthesis at High Temperature and Pressure Conditions: Carbon Isotope and Mineral Surface Characterizations

    NASA Technical Reports Server (NTRS)

    Fu, Qi; Socki, R. A.; Niles, P. B.

    2010-01-01

    Abiotic organic synthesis processes have been proposed as potential mechanisms for methane generation in subseafloor hydrothermal systems on Earth, and on other planets. To better understand the detailed reaction pathways and carbon isotope fractionations in this process under a wide range of physical and chemical conditions, hydrothermal experiments at high temperature (750 C) and pressure (0.55 GPa) were performed using piston cylinder apparatus. Formic acid was used as the source of CO2 and H2, and magnetite was the mineral catalyst. The chemical and carbon isotopic compositions of dissolved organic products were determined by GC-C-MS-IRMS, while organic intermediaries on the mineral catalyst were characterized by Pyrolysis-GC-MS. Among experimental products, dissolved CO2 was the dominant carbon species with a relative abundance of 88 mol%. Dissolved CH4 and C2H6 were also identified with a mole ratio of CH4 over C2H6 of 15:1. No dissolved CO was detected in the experiment, which might be attributable to the loss of H2 through the Au capsule used in the experiments at high temperature and pressure conditions and corresponding conversion of CO to CO2 by the water-gas shift reaction. Carbon isotope results showed that the 13C values of CH4 and C2H6 were -50.3% and -39.3% (V-PDB), respectively. CO2 derived from decarboxylation of formic acid had a (sigma)C-13 value of -19.2%, which was 3.2% heavier than its source, formic acid. The (sigma)C-13 difference between CO2 and CH4 was 31.1%, which was higher than the value of 9.4% calculated from theoretical isotopic equilibrium predictions at experimental conditions, suggesting the presence of a kinetic isotope effect. This number was also higher than the values (4.6 to 27.1%) observed in similar experiments previously performed at 400 C and 50 MPa with longer reaction times. CH4 is 11.0% less enriched in C-13 than C2H6. Alcohols were observed as carbon compounds on magnetite surfaces by Pyrolysis-GC-MS, which confirms

  16. Atmospheric CO2 capture for the artificial photosynthetic system

    NASA Astrophysics Data System (ADS)

    Nogalska, Adrianna; Zukowska, Adrianna; Garcia-Valls, Ricard

    2017-11-01

    The scope of these studies is to evaluate the ambient CO2 capture abilities of the membrane contactor system in the same conditions as leaves works during photosynthesis, such as ambient temperature, pressure and low CO2 concentration, where the only driving force is the concentration gradient. The polysulfone membrane was made by phase inversion process and characterized by ESEM micrographs which were used to determine the thickness, asymmetry and pore size. Besides, the porosity of the membrane was measured from the membrane and polysulfone density correlation and hydrophobicity was analyzed by contact angle measurements. Moreover, the compatibility of the membrane and absorbent solution was evaluated, in order to exclude wetting issues. The prepared membranes were introduced in a cross flow module and used as contactor between the CO2 and the potassium hydroxide solution, as absorbing media. The influence of the membrane thickness, absorbent stirring rate and absorption time, on CO2 capture were evaluated. The results show that the efficiency of our CO2 capture system is similar to stomatal carbon dioxide assimilation rate.

  17. Progress Toward Measuring CO2 Isotopologue Fluxes in situ with the LLNL Miniature, Laser-based CO2 Sensor

    NASA Astrophysics Data System (ADS)

    Osuna, J. L.; Bora, M.; Bond, T.

    2015-12-01

    One method to constrain photosynthesis and respiration independently at the ecosystem scale is to measure the fluxes of CO2­ isotopologues. Instrumentation is currently available to makes these measurements but they are generally costly, large, bench-top instruments. Here, we present progress toward developing a laser-based sensor that can be deployed directly to a canopy to passively measure CO2 isotopologue fluxes. In this study, we perform initial proof-of-concept and sensor characterization tests in the laboratory and in the field to demonstrate performance of the Lawrence Livermore National Laboratory (LLNL) tunable diode laser flux sensor. The results shown herein demonstrate measurement of bulk CO2 as a first step toward achieving flux measurements of CO2 isotopologues. The sensor uses a Vertical Cavity Surface Emitting Laser (VCSEL) in the 2012 nm range. The laser is mounted in a multi-pass White Cell. In order to amplify the absorption signal of CO2 in this range we employ wave modulation spectroscopy, introducing an alternating current (AC) bias component where f is the frequency of modulation on the laser drive current in addition to the direct current (DC) emission scanning component. We observed a strong linear relationship (r2 = 0.998 and r2 = 0.978 at all and low CO2 concentrations, respectively) between the 2f signal and the CO2 concentration in the cell across the range of CO2 concentrations relevant for flux measurements. We use this calibration to interpret CO2 concentration of a gas flowing through the White cell in the laboratory and deployed over a grassy field. We will discuss sensor performance in the lab and in situ as well as address steps toward achieving canopy-deployed, passive measurements of CO2 isotopologue fluxes. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-675788

  18. Efficient Reservoir Simulation with Cubic Plus Association and Cross-Association Equation of State for Multicomponent Three-Phase Compressible Flow with Applications in CO2 Storage and Methane Leakage

    NASA Astrophysics Data System (ADS)

    Moortgat, J.

    2017-12-01

    We present novel simulation tools to model multiphase multicomponent flow and transport in porous media for mixtures that contain non-polar hydrocarbons, self-associating polar water, and cross-associating molecules like methane, ethane, unsaturated hydrocarbons, CO2 and H2S. Such mixtures often occur when CO2 is injected and stored in saline aquifers, or when methane is leaking into groundwater. To accurately predict the species transfer between aqueous, gaseous and oleic phases, and the subsequent change in phase properties, the self- and cross-associating behavior of molecules needs to be taken into account, particularly at the typical temperatures and pressures in deep formations. The Cubic-Plus-Association equation-of-state (EOS) has been demonstrated to be highly accurate for such problems but its excessive computational cost has prevented widespread use in reservoir simulators. We discuss the thermodynamical framework and develop sophisticated numerical algorithms that allow reservoir simulations with efficiencies comparable to a simple cubic EOS. This approach improves our predictive powers for highly nonlinear fluid behavior related to geological carbon sequestration, such as density driven flow and natural convection (solubility trapping), evaporation of water into the CO2-rich gas phase, and competitive dissolution-evaporation when CO2 is injected in, e.g., methane saturated aquifers. Several examples demonstrate the accuracy and robustness of this EOS framework for complex applications.

  19. Solar Spectrum Photocatalytic Conversion of CO2 and Water Vapor Into Hydrocarbons Using TiO2 Nanoparticle Membranes

    NASA Astrophysics Data System (ADS)

    Rani, Sanju; Bao, Ningzhong; Roy, Somnath C.

    2014-01-01

    A viable option for recycling carbon dioxide is through the sunlight-powered photocatalytic conversion of CO2 and water vapor into hydrocarbon fuels over highly active nanocatalysts. With photocatalytic CO2 reduction sunlight, a renewable energy source as durable as the sun, is used to drive the catalytic reaction with the resultant fuel products compatible with the current hydrocarbon-based energy infrastructure. The use of co-catalyst (Cu, Pt)-sensitized TiO2 nanoparticle wafers in the photocatalytic conversion of CO2 and water vapor to hydrocarbon fuels, with optimal humidity levels and exposure times established. We also attempted to increase product formation by sputtering both co-catalysts on the nanoparticle wafer's surface, with the resulting product rates significantly higher than that of either the Cu or Pt coated samples. When the TiO2 nanoparticle wafers are used in a flow-through membrane implementation we find a significant increase in product rates of formation, including methane, hydrogen, and carbon monoxide. We believe that nanocatalyst-based flow-through membranes are a viable route for achieving large-scale and low cost photocatalytic solar fuel production.

  20. Transport and transformation of soil-derived CO2, CH4 and DOC sustain CO2 supersaturation in small boreal streams.

    PubMed

    Rasilo, Terhi; Hutchins, Ryan H S; Ruiz-González, Clara; Del Giorgio, Paul A

    2017-02-01

    Streams are typically supersaturated in carbon dioxide (CO 2 ) and methane (CH 4 ), and are recognized as important components of regional carbon (C) emissions in northern landscapes. Whereas there is consensus that in most of the systems the CO 2 emitted by streams represents C fixed in the terrestrial ecosystem, the pathways delivering this C to streams are still not well understood. We assessed the contribution of direct soil CO 2 injection versus the oxidation of soil-derived dissolved organic C (DOC) and CH 4 in supporting CO 2 supersaturation in boreal streams in Québec. We measured the concentrations of CO 2 , CH 4 and DOC in 43 streams and adjacent soil waters during summer base-flow period. A mass balance approach revealed that all three pathways are significant, and that the mineralization of soil-derived DOC and CH 4 accounted for most of the estimated stream CO 2 emissions (average 75% and 10%, respectively), and that these estimated contributions did not change significantly between the studied low order (≤3) streams. Whereas some of these transformations take place in the channel proper, our results suggest that they mainly occur in the hyporheic zones of the streams. Our results further show that stream CH 4 emissions can be fully explained by soil CH 4 inputs. This study confirms that these boreal streams, and in particular their hyporheic zones, are extremely active processors of soil derived DOC and CH 4 , not just vents for soil produced CO 2 . Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Local CO2-induced swelling of shales

    NASA Astrophysics Data System (ADS)

    Pluymakers, Anne; Dysthe, Dag Kristian

    2017-04-01

    In heterogeneous shale rocks, CO2 adsorbs more strongly to organic matter than to the other components. CO2-induced swelling of organic matter has been shown in coal, which is pure carbon. The heterogeneity of the shale matrix makes an interesting case study. Can local swelling through adsorption of CO2 to organic matter induce strain in the surrounding shale matrix? Can fractures close due to CO2-induced swelling of clays and organic matter? We have developed a new generation of microfluidic high pressure cells (up to 100 bar), which can be used to study flow and adsorption phenomena at the microscale in natural geo-materials. The devices contain one transparent side and a shale sample on the other side. The shale used is the Pomeranian shale, extracted from 4 km depth in Poland. This formation is a potential target of a combined CO2-storage and gas extraction project. To answer the first question, we place the pressure cell under a Veeco NT1100 Interferometer, operated in Vertical Scanning Interferometry mode and equipped with a Through Transmissive Media objective. This allows for observation of local swelling or organic matter with nanometer vertical resolution and micrometer lateral resolution. We expose the sample to CO2 atmospheres at different pressures. Comparison of the interferometry data and using SEM-EDS maps plus optical microscopy delivers local swelling maps where we can distinguish swelling of different mineralogies. Preliminary results indicate minor local swelling of organic matter, where the total amount is both time- and pressure-dependent.

  2. Abiotic uptake of gases by organic soils

    NASA Astrophysics Data System (ADS)

    Smagin, A. V.

    2007-12-01

    Methodological and experimental studies of the abiotic uptake of gaseous substances by organic soils were performed. The static adsorption method of closed vessels for assessing the interaction of gases with the solid and liquid soil phases and the dynamic method of determining the sorption isotherms of gases by soils were analyzed. The theoretical substantiation of the methods and their practical implementations on the basis of a PGA-7 portable gas analyzer (Russia) were considered. Good agreement between the equilibrium sorption isotherms of the gases and the Langmuir model was revealed; for the real ranges of natural gas concentrations, this model can be reduced to the linear Henry equation. The limit values of the gas sorption (Langmuir monolayer capacity) are typical for dry samples; they vary from 670 4000 g/m3 for methane and oxygen to 20 000 25 000 g/m3 for carbon dioxide. The linear distribution coefficients of gases between the solid and gas phases of organic soils (Henry constants) are 8 18 units for poorly sorbed gases (O2, CH4) and 40 60 units for CO2. The kinetics of the chemicophysical uptake of gases by the soil studied is linear in character and obeys the relaxation kinetic model of the first order with the corresponding relaxation constants, which vary from 1 h -1 in wet samples to 10 h -1 in dry samples.

  3. Pore scale study of multiphase multicomponent reactive transport during CO 2 dissolution trapping

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

    Chen, Li; Wang, Mengyi; Kang, Qinjun

    Solubility trapping is crucial for permanent CO 2 sequestration in deep saline aquifers. For the first time, a pore-scale numerical method is developed to investigate coupled scCO 2-water two-phase flow, multicomponent (CO 2(aq), H +, HCO 3 –, CO 3 2 – and OH –) mass transport, heterogeneous interfacial dissolution reaction, and homogeneous dissociation reactions. Pore-scale details of evolutions of multiphase distributions and concentration fields are presented and discussed. Time evolutions of several variables including averaged CO 2(aq) concentration, scCO 2 saturation, and pH value are analyzed. Specific interfacial length, an important variable which cannot be determined but is requiredmore » by continuum models, is investigated in detail. Mass transport coefficient or efficient dissolution rate is also evaluated. The pore-scale results show strong non-equilibrium characteristics during solubility trapping due to non-uniform distributions of multiphase as well as slow mass transport process. Complicated coupling mechanisms between multiphase flow, mass transport and chemical reactions are also revealed. Lastly, effects of wettability are also studied. The pore-scale studies provide deep understanding of non-linear non-equilibrium multiple physicochemical processes during CO 2 solubility trapping processes, and also allow to quantitatively predict some important empirical relationships, such as saturation-interfacial surface area, for continuum models.« less

  4. Pore scale study of multiphase multicomponent reactive transport during CO 2 dissolution trapping

    DOE PAGES

    Chen, Li; Wang, Mengyi; Kang, Qinjun; ...

    2018-04-26

    Solubility trapping is crucial for permanent CO 2 sequestration in deep saline aquifers. For the first time, a pore-scale numerical method is developed to investigate coupled scCO 2-water two-phase flow, multicomponent (CO 2(aq), H +, HCO 3 –, CO 3 2 – and OH –) mass transport, heterogeneous interfacial dissolution reaction, and homogeneous dissociation reactions. Pore-scale details of evolutions of multiphase distributions and concentration fields are presented and discussed. Time evolutions of several variables including averaged CO 2(aq) concentration, scCO 2 saturation, and pH value are analyzed. Specific interfacial length, an important variable which cannot be determined but is requiredmore » by continuum models, is investigated in detail. Mass transport coefficient or efficient dissolution rate is also evaluated. The pore-scale results show strong non-equilibrium characteristics during solubility trapping due to non-uniform distributions of multiphase as well as slow mass transport process. Complicated coupling mechanisms between multiphase flow, mass transport and chemical reactions are also revealed. Lastly, effects of wettability are also studied. The pore-scale studies provide deep understanding of non-linear non-equilibrium multiple physicochemical processes during CO 2 solubility trapping processes, and also allow to quantitatively predict some important empirical relationships, such as saturation-interfacial surface area, for continuum models.« less

  5. Effects of Impurities in CO2 Spreading Model Development for Field Experiments in the Framework of the CO2QUEST Project

    NASA Astrophysics Data System (ADS)

    Rebscher, D.; Wolf, J. L.; Jung, B.; Bensabat, J.; Segev, R.; Niemi, A. P.

    2014-12-01

    The aim of the CO2QUEST project (Impact of the Quality of CO2 on Storage and Transport) is to investigate the effect of typical impurities in the CO2 stream captured from fossil fuel power plants on its safe and economic transportation and deep geologic storage. An important part of this EU funded project is to enhance the understanding of typical impurity effects in a CO2 stream regarding the performance of the storage. Based on the experimental site Heletz in Israel, where injection tests of water as well as of super-critical pure and impure CO2 will be conducted, numerical simulations are performed. These studies illustrate flow and transport of CO2 and brine as well as impurities induced chemical reactions in relation to changes in the reservoir, e.g. porosity, permeability, pH-value, and mineral composition. Using different THC codes (TOUGH2-ECO2N, TOUGHREACT, PFLOTRAN), the spatial distribution of CO2 and impurities, both in the supercritical and aqueous phases, are calculated. The equation of state (EOS) of above numerical codes are properly modified to deal with binary/tertiary gas mixtures (e.g. CO2-N2 or CO2-SO2). In addition, simulations for a push-pull test of about 10 days duration are performed, which will be validated against experimental field data. Preliminary results are as follows: (a) As expected, the injection of SO2 leads to a strong decrease in pH-value, hence, the total dissolution of carbonate minerals could be observed. (b) Due to the acidic attack on clay minerals , which is enhanced compared to a pure CO2 dissolution, a higher amount of metal ions are released, in particular Fe2+ and Mg2+ by a factor of 25 and 10, respectively. Whereas secondary precipitation occurs only for sulphur minerals, namely anhydrite and pyrite. (c) The co-injection of CO2 with N2 changes physical properties of the gas mixture. Increasing N2 contents induces density decrease of the gas mixture, resulting in faster and wider plume migration compared to the pure

  6. Using hyperspectral plant signatures for CO2 leak detection during the 2008 ZERT CO2 sequestration field experiment in Bozeman, Montana

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

    Male, E.J.; Pickles, W.L.; Silver, E.A.

    2009-11-01

    Hyperspectral plant signatures can be used as a short-term, as well as long-term (100-yr timescale) monitoring technique to verify that CO2 sequestration fields have not been compromised. An influx of CO2 gas into the soil can stress vegetation, which causes changes in the visible to nearinfrared reflectance spectral signature of the vegetation. For 29 days, beginning on July 9th, 2008, pure carbon dioxide gas was released through a 100-meter long horizontal injection well, at a flow rate of 300 kg/day. Spectral signatures were recorded almost daily from an unmown patch of plants over the injection with a ''FieldSpec Pro'' spectrometermore » by Analytical Spectral Devices, Inc. Measurements were taken both inside and outside of the CO2 leak zone to normalize observations for other environmental factors affecting the plants.« less

  7. Identification and expression of C2H2 transcription factor genes in Carica papaya under abiotic and biotic stresses.

    PubMed

    Jiang, Ling; Pan, Lin-jie

    2012-06-01

    C2H2 proteins belong to a group of transcription factors (TFs) existing as a superfamily that plays important roles in defense responses and various other physiological processes in plants. The present study aimed to screen for and identify C2H2 proteins associated with defense responses to abiotic and biotic stresses in Carica papaya L. Data were collected for 47,483 papaya-expressed sequence tags (ESTs). The full-length cDNA nucleotide sequences of 87 C2H2 proteins were predicated by BioEdit. All 91 C2H2 proteins were aligned, and a phylogenetic tree was constructed using DNAman. The expression levels of 42 C2H2 were analyzed under conditions of salt stress by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). Methyl jasmonate treatment rapidly upregulated ZF(23.4) and ZF(30,912.1) by 18.6- and 21.7-fold, respectively. ZF(1.3), ZF(138.44), ZF(94.49), ZF(29.160), and ZF(20.206) were found to be downregulated after low temperature treatment at very significant levels (p < 0.01). ZF(23.4), ZF(161.1), and ZF(30,912.1) were upregulated while ZF1.3, ZF(158.1), ZF(249.5), ZF(138.44), ZF(94.49), ZF(29.160), and ZF(20.206) were significantly downregulated by Spermine treatment. ZF(23.4) was upregulated while ZF(1.3), ZF(249.5), ZF(94.94), ZF(29.160), ZF(138.44), and ZF(20.206) were significantly repressed after SA treatment. ZF(23.4) and ZF(30,912.1) were significantly upregulated after sap inoculation with papaya ringspot virus pathogen. ZF(30,912.1) was subcellularly localized in the nucleus by a transgenic fusion of pBS-ZF(30,912.1)-GFP into the protoplast of papaya. The results of the present study showed that ZF(30,912.1) could be an important TF that mediates responses to abiotic and biotic stresses in papaya.

  8. Phytoplankton responses to temperature increases are constrained by abiotic conditions and community composition.

    PubMed

    Striebel, Maren; Schabhüttl, Stefanie; Hodapp, Dorothee; Hingsamer, Peter; Hillebrand, Helmut

    2016-11-01

    Effects of temperature changes on phytoplankton communities seem to be highly context-specific, but few studies have analyzed whether this context specificity depends on differences in the abiotic conditions or in species composition between studies. We present an experiment that allows disentangling the contribution of abiotic and biotic differences in shaping the response to two aspects of temperature change: permanent increase of mean temperature versus pulse disturbance in form of a heat wave. We used natural communities from six different sites of a floodplain system as well as artificially mixed communities from laboratory cultures and grew both, artificial and natural communities, in water from the six different floodplain lakes (sites). All 12 contexts (2 communities × 6 sites) were first exposed to three different temperature levels (12, 18, 24 °C, respectively) and afterward to temperature pulses (4 °C increase for 7 h day(-1)). Temperature-dependent changes in biomass and community composition depended on the initial composition of phytoplankton communities. Abiotic conditions had a major effect on biomass of phytoplankton communities exposed to different temperature conditions, however, the effect of biotic and abiotic conditions together was even more pronounced. Additionally, phytoplankton community responses to pulse temperature effects depended on the warming history. By disentangling abiotic and biotic effects, our study shows that temperature-dependent effects on phytoplankton communities depend on both, biotic and abiotic constraints.

  9. A finite element code for modelling tracer transport in a non-isothermal two-phase flow system for CO2 geological storage characterization

    NASA Astrophysics Data System (ADS)

    Tong, F.; Niemi, A. P.; Yang, Z.; Fagerlund, F.; Licha, T.; Sauter, M.

    2011-12-01

    This paper presents a new finite element method (FEM) code for modeling tracer transport in a non-isothermal two-phase flow system. The main intended application is simulation of the movement of so-called novel tracers for the purpose of characterization of geologically stored CO2 and its phase partitioning and migration in deep saline formations. The governing equations are based on the conservation of mass and energy. Among the phenomena accounted for are liquid-phase flow, gas flow, heat transport and the movement of the novel tracers. The movement of tracers includes diffusion and the advection associated with the gas and liquid flow. The temperature, gas pressure, suction, concentration of tracer in liquid phase and concentration of tracer in gas phase are chosen as the five primary variables. Parameters such as the density, viscosity, thermal expansion coefficient are expressed in terms of the primary variables. The governing equations are discretized in space using the Galerkin finite element formulation, and are discretized in time by one-dimensional finite difference scheme. This leads to an ill-conditioned FEM equation that has many small entries along the diagonal of the non-symmetric coefficient matrix. In order to deal with the problem of non-symmetric ill-conditioned matrix equation, special techniques are introduced . Firstly, only nonzero elements of the matrix need to be stored. Secondly, it is avoided to directly solve the whole large matrix. Thirdly, a strategy has been used to keep the diversity of solution methods in the calculation process. Additionally, an efficient adaptive mesh technique is included in the code in order to track the wetting front. The code has been validated against several classical analytical solutions, and will be applied for simulating the CO2 injection experiment to be carried out at the Heletz site, Israel, as part of the EU FP7 project MUSTANG.

  10. Abiotic and Biotic Mechanisms Controlling In Situ Remediation of NDMA

    DTIC Science & Technology

    2009-05-01

    FINAL REPORT Abiotic and Biotic Mechanisms Controlling In Situ Remediation of NDMA SERDP Project ER-1421 MAY 2009 James E. Szecsody...00-2009 4. TITLE AND SUBTITLE Abiotic and Biotic Mechanisms Controlling In Situ Remediation of NDMA 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c...investigate whether in situ coupled abiotic/biotic degradation of N-nitrosodimethylamine ( NDMA , an emerging contaminant) could be used as a permeable

  11. Investigation of CO 2 capture using solid sorbents in a fluidized bed reactor: Cold flow hydrodynamics

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

    Li, Tingwen; Dietiker, Jean -Francois; Rogers, William

    2016-07-29

    Both experimental tests and numerical simulations were conducted to investigate the fluidization behavior of a solid CO 2 sorbent with a mean diameter of 100 μm and density of about 480 kg/m, which belongs to Geldart's Group A powder. A carefully designed fluidized bed facility was used to perform a series of experimental tests to study the flow hydrodynamics. Numerical simulations using the two-fluid model indicated that the grid resolution has a significant impact on the bed expansion and bubbling flow behavior. Due to the limited computational resource, no good grid independent results were achieved using the standard models asmore » far as the bed expansion is concerned. In addition, all simulations tended to under-predict the bubble size substantially. Effects of various model settings including both numerical and physical parameters have been investigated with no significant improvement observed. The latest filtered sub-grid drag model was then tested in the numerical simulations. Compared to the standard drag model, the filtered drag model with two markers not only predicted reasonable bed expansion but also yielded realistic bubbling behavior. As a result, a grid sensitivity study was conducted for the filtered sub-grid model and its applicability and limitation were discussed.« less

  12. Rechargeable Al-CO2 Batteries for Reversible Utilization of CO2.

    PubMed

    Ma, Wenqing; Liu, Xizheng; Li, Chao; Yin, Huiming; Xi, Wei; Liu, Ruirui; He, Guang; Zhao, Xian; Luo, Jun; Ding, Yi

    2018-05-21

    The excessive emission of CO 2 and the energy crisis are two major issues facing humanity. Thus, the electrochemical reduction of CO 2 and its utilization in metal-CO 2 batteries have attracted wide attention because the batteries can simultaneously accelerate CO 2 fixation/utilization and energy storage/release. Here, rechargeable Al-CO 2 batteries are proposed and realized, which use chemically stable Al as the anode. The batteries display small discharge/charge voltage gaps down to 0.091 V and high energy efficiencies up to 87.7%, indicating an efficient battery performance. Their chemical reaction mechanism to produce the performance is revealed to be 4Al + 9CO 22Al 2 (CO 3 ) 3 + 3C, by which CO 2 is reversibly utilized. These batteries are envisaged to effectively and safely serve as a potential CO 2 fixation/utilization strategy with stable Al. © 2018 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Formation of CO2, H2 and condensed carbon from siderite dissolution in the 200-300 °C range and at 50 MPa

    NASA Astrophysics Data System (ADS)

    Milesi, Vincent; Guyot, François; Brunet, Fabrice; Richard, Laurent; Recham, Nadir; Benedetti, Marc; Dairou, Julien; Prinzhofer, Alain

    2015-04-01

    Laboratory experiments were conducted to investigate the chemical processes governing the carbon speciation associated to hydrothermal decomposition of siderite. Experiments were carried out in sealed gold capsules using synthetic siderite and deionised water. The samples were reacted at 200 and 300 °C, under a pressure of 50 MPa. Siderite dissolved to reach the 3FeCO3 + H2O = Fe3O4 + 3CO2 + H2 equilibrium and magnetite, Fe3O4, was produced accordingly. The gas phase was dominated by CO2, H2 and CH4, the latter being in strong thermodynamic disequilibrium with CO2. Contrary to the other gas products, H2 concentration was found to decrease with run duration. TEM observations showed the occurrence of condensed carbon phases at the surfaces of magnetite and residual siderite grains. Thermodynamic calculations predict the formation of condensed carbon in the experiments according to the reaction: CO2 + 2H2 ⇒ C + 2H2O, which accounted for the observed H2 concentration decrease up to the point where H2 and CO2 activities were buffered by the graphite-siderite-magnetite assemblage. The well-organized structure of the carbon coating around magnetite emphasizes the high catalytic potential of magnetite surface for carbon reduction and polymerization. The formation of such C-rich phases may represent a potential source of CH4 by hydrogenation. On the other hand, the catalysis of Fischer-Tropsch type reactions may be poisoned by the presence of carbon coating on mineral surfaces. In any case, this study also demonstrates that abiotic H2 generation by water reduction, widely studied in recent years in ultrabasic contexts, can also occur in sedimentary contexts where siderite is present. We show that, in the latter case, natural H2 concentration will be buffered by a condensed carbon phase associated with magnetite.

  14. Bacterial populations growth under co- and counter-flow condition

    NASA Astrophysics Data System (ADS)

    Tesser, Francesca; Zeegers, Jos C. H.; Clercx, Herman J. H.; Toschi, Federico

    2014-11-01

    For organisms living in a liquid ecosystem, flow and flow gradients play a major role on the population level: the flow has a dual role as it transports the nutrient while dispersing the individuals. In absence of flow and under homogeneous conditions, the growth of a population towards an empty region is usually described by a reaction diffusion equation. The solution predicts the expansion as a wave front (Fisher wave) proceeding at constant speed, till the carrying capacity is reached everywhere. The effect of fluid flow, however, is not well understood and the interplay between transport of individuals and nutrient opens a wide scenario of possible behaviors. In this work, we experimentally observe non-motile E. coli bacteria spreading inside rectangular channels in a PDMS microfluidic device. By use of a fluorescent microscope we analyze the dynamics of the population density subjected to different co- and counter-flow conditions and shear rates.

  15. Rates of CO2 Mineralization in Geological Carbon Storage.

    PubMed

    Zhang, Shuo; DePaolo, Donald J

    2017-09-19

    Geologic carbon storage (GCS) involves capture and purification of CO 2 at industrial emission sources, compression into a supercritical state, and subsequent injection into geologic formations. This process reverses the flow of carbon to the atmosphere with the intention of returning the carbon to long-term geologic storage. Models suggest that most of the injected CO 2 will be "trapped" in the subsurface by physical means, but the most risk-free and permanent form of carbon storage is as carbonate minerals (Ca,Mg,Fe)CO 3 . The transformation of CO 2 to carbonate minerals requires supply of the necessary divalent cations by dissolution of silicate minerals. Available data suggest that rates of transformation are highly uncertain and difficult to predict by standard approaches. Here we show that the chemical kinetic observations and experimental results, when they can be reduced to a single cation-release time scale that describes the fractional rate at which cations are released to solution by mineral dissolution, show sufficiently systematic behavior as a function of pH, fluid flow rate, and time that the rates of mineralization can be estimated with reasonable certainty. The rate of mineralization depends on both the abundance (determined by the reservoir rock mineralogy) and the rate at which cations are released from silicate minerals by dissolution into pore fluid that has been acidified with dissolved CO 2 . Laboratory-measured rates and field observations give values spanning 8 to 10 orders of magnitude, but when they are evaluated in the context of a reservoir-scale reactive transport simulation, this range becomes much smaller. The reservoir scale simulations provide limits on the applicable conditions under which silicate mineral dissolution and subsequent carbonate mineral precipitation are likely to occur (pH 4.5 to 6, fluid flow velocity less than 5 m/year, and 50-100 years or more after the start of injection). These constraints lead to estimates of

  16. Surface modification of a low cost bentonite for post-combustion CO2 capture

    NASA Astrophysics Data System (ADS)

    Chen, Chao; Park, Dong-Wha; Ahn, Wha-Seung

    2013-10-01

    A low cost bentonite was modified with PEI (polyethylenimine) through a physical impregnation method. Bentonite in its natural state and after amine modification were characterized by scanning electron microscopy-energy dispersive X-ray spectroscopy, X-ray diffraction, N2 adsorption-desorption isotherms, and investigated for CO2 capture using a thermogravimetric analysis unit connected to a flow panel. The effect of adsorption temperature, PEI loading and CO2 partial pressure on the CO2 capture performance of the PEI-modified bentonite was examined. A cyclic CO2 adsorption-desorption test was also carried out to assess the stability of PEI-modified bentonite as a CO2 adsorbent. Bentonite in its natural state showed negligible CO2 uptake. After amine modification, the CO2 uptake increased significantly due to CO2 capture by amine species introduced via chemisorption. The PEI-modified bentonites showed high CO2 capture selectivity over N2, and exhibited excellent stability in cyclic CO2 adsorption-desorption runs.

  17. Shaft sealing issue in CO2 storage sites

    NASA Astrophysics Data System (ADS)

    Dieudonné, A.-C.; Charlier, R.; Collin, F.

    2012-04-01

    Carbon capture and storage is an innovating approach to tackle climate changes through the reduction of greenhouse gas emissions. Deep saline aquifers, depleted oil and gas reservoirs and unmineable coal seams are among the most studied reservoirs. However other types of reservoir, such as abandonned coal mines, could also be used for the storage of carbon dioxide. In this case, the problem of shaft sealing appears to be particularly critical regarding to the economic, ecologic and health aspects of geological storage. The purpose of the work is to study shaft sealing in the framework of CO2 storage projects in abandoned coal mines. The problem of gas transfers around a sealing system is studied numerically using the finite elements code LAGAMINE, which has been developped for 30 years at the University of Liege. A coupled hydro-mechanical model of unsaturated geomaterials is used for the analyses. The response of the two-phase flow model is first studied through a simple synthetic problem consisting in the injection of gas in a concrete-made column. It stands out of this first modeling that the advection of the gas phase represents the main transfer mechanism of CO2 in highly unsaturated materials. Furthermore the setting of a bentonite barrier seal limits considerably the gas influx into the biosphere. A 2D axisymetric hydromechanical modeling of the Anderlues natural gas storage site is then performed. The geological and hydrogeological contexts of the site are used to define the problem, for the initial and boundary conditions, as well as the material properties. In order to reproduce stress and water saturation states in the shale before CO2 injection in the mine, different phases corresponding to the shaft sinking, the mining and the set up of the sealing system are simulated. The system efficiency is then evaluated by simulating the CO2 injection with the imposed pressure at the shaft wall. According to the modeling, the low water saturation of concrete and

  18. 40 CFR Appendix G to Part 75 - Determination of CO2 Emissions

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... following procedures to estimate daily CO2 mass emissions from the combustion of fossil fuels. The optional... tons/day) from the combustion of fossil fuels. Where fuel flow is measured in a common pipe header (i.e... discharged to the atmosphere (in tons/day) as the sum of CO2 emissions from combustion and, if applicable...

  19. 40 CFR Appendix G to Part 75 - Determination of CO2 Emissions

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... following procedures to estimate daily CO2 mass emissions from the combustion of fossil fuels. The optional... tons/day) from the combustion of fossil fuels. Where fuel flow is measured in a common pipe header (i.e... discharged to the atmosphere (in tons/day) as the sum of CO2 emissions from combustion and, if applicable...

  20. 40 CFR Appendix G to Part 75 - Determination of CO2 Emissions

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... following procedures to estimate daily CO2 mass emissions from the combustion of fossil fuels. The optional... tons/day) from the combustion of fossil fuels. Where fuel flow is measured in a common pipe header (i.e... discharged to the atmosphere (in tons/day) as the sum of CO2 emissions from combustion and, if applicable...

  1. 40 CFR Appendix G to Part 75 - Determination of CO2 Emissions

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... following procedures to estimate daily CO2 mass emissions from the combustion of fossil fuels. The optional... tons/day) from the combustion of fossil fuels. Where fuel flow is measured in a common pipe header (i.e... discharged to the atmosphere (in tons/day) as the sum of CO2 emissions from combustion and, if applicable...

  2. Feasibility Study for The Setting Up of a Safety System for Monitoring CO2 Storage at Prinos Field, Greece

    NASA Astrophysics Data System (ADS)

    Koukouzas, Nikolaos; Lymperopoulos, Panagiotis; Tasianas, Alexandros; Shariatipour, Seyed

    2016-10-01

    Geological storage of CO2 in subsurface geological structures can mitigate global warming. A comprehensive safety and monitoring system for CO2 storage has been undertaken for the Prinos hydrocarbon field, offshore northern Greece; a system which can prevent any possible leakage of CO2. This paper presents various monitoring strategies of CO2 subsurface movement in the Prinos reservoir, the results of a simulation of a CO2 leak through a well, an environmental risk assessment study related to the potential leakage of CO2 from the seafloor and an overall economic insight of the system. The results of the simulation of the CO2 leak have shown that CO2 reaches the seabed in the form of gas approximately 13.7 years, from the beginning of injection. From that point onwards the amount of CO2 reaching the seabed increases until it reaches a peak at around 32.9 years. During the injection period, the CO2 plume develops only within the reservoir. During the post-injection period, the CO2 reaches the seabed and develops side branches. These correspond to preferential lateral flow pathways of the CO2 and are more extensive for the dissolved CO2 than for the saturated CO2 gas. For the environmental risk assessment, we set up a model, using ArcGIS software, based on the use of data regarding the speeds of the winds and currents encountered in the region. We also made assumptions related to the flow rate of CO2. Results show that after a period of 10 days from the start of CO2 leakage the CO2 has reached halfway to the continental shores where the “Natura” protected areas are located. CO2 leakage modelling results show CO2 to be initially flowing along a preferential flow direction, which is towards the NE. However, 5 days after the start of leakage of CO2, the CO2 is also flowing towards the ENE. The consequences of a potential CO2 leak are considered spatially limited and the ecosystem is itself capable of recovering. We have tried to determine the costs necessary for the

  3. The CO 2 permeability and mixed gas CO 2/H 2 selectivity of membranes composed of CO 2-philic polymers

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

    Barillas, Mary Katharine; Enick, Robert M.; O’Brien, Michael

    2011-04-01

    The objective of this work was to design polymeric membranes that have very high CO 2 permeability and high mixed gas selectivity toward CO 2 rather than hydrogen. Therefore the membranes were based on "CO 2-philic" polymers that exhibit thermodynamically favorable Lewis acid:Lewis base and hydrogen bonding interactions with CO 2. CO 2-philic polymers that are solid at ambient temperature include polyfluoroacrylate (PFA); polyvinyl acetate (PVAc); and amorphous polylactic acid (PLA). Literature CO 2 permeability values for PVAc and PLA are disappointingly low. The cast PFA membranes from this study had low permeabilities (45 barrers at 25º C) and verymore » low CO 2/H 2 selectivity of 1.4. CO 2-philic polymers that are liquid at ambient conditions include polyethylene glycol (PEG), polypropylene glycol (PPG), polybutylene glycol with a linear -((CH 2) 4O)-repeat unit (i.e., polytetramethylene ether glycol (PTMEG)), polybutylene glycol (PBG) with a branched repeat unit, perfluoropolyether (PFPE), poly(dimethyl siloxane) (PDMS), and polyacetoxy oxetane (PAO). A small compound, glycerol triacetate (GTA) was also considered because it is similar in chemical structure to a trimer of PVAc. These liquids were tested as supported liquid membranes (SLM) and also (with the exception of PAD and GTA) as rubbery, crosslinked materials. Mixed gas permeability was measured using equimolar mixtures of CO 2 and H 2 feed streams at one atmosphere total pressure in steady-state flux experiments over the 298-423 K temperature range. The most promising SLMs were those composed of PEG, PTMEG, GTA, and PDMS. For example, at 37º C the PEG-, PTMEG-, GTA- and PDMS-based SLMs exhibited CO 2/H 2 selectivity values of ~11, 9, 9, and 3.5, respectively, and CO 2 permeability values of ~800, 900, 1900, and 2000 barrers, respectively. Crosslinked versions of the PEG, PTMEG and PDMS membranes at 37º C exhibited selectivity values of ~5, 6, and 3.5, respectively, and CO 2 permeability values of

  4. Increased resin flow in mature pine trees growing under elevated CO2 and moderate soil fertility

    Treesearch

    K.A. Novick; G.G. Katul; H.R. McCarthy; R. Oren

    2012-01-01

    Warmer climates induced by elevated atmospheric CO2 (eCO2) are expected to increase damaging bark beetle activity in pine forests, yet the effect of eCO2 on resin production—the tree’s primary defense against beetle attack—remains largely unknown. Following growth-differentiation balance theory, if extra carbohydrates produced under eCO2 are not consumed by respiration...

  5. Mathematical Analysis of High-Temperature Co-electrolysis of CO2 and O2 Production in a Closed-Loop Atmosphere Revitalization System

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

    Michael G. McKellar; Manohar S. Sohal; Lila Mulloth

    2010-03-01

    NASA has been evaluating two closed-loop atmosphere revitalization architectures based on Sabatier and Bosch carbon dioxide, CO2, reduction technologies. The CO2 and steam, H2O, co-electrolysis process is another option that NASA has investigated. Utilizing recent advances in the fuel cell technology sector, the Idaho National Laboratory, INL, has developed a CO2 and H2O co-electrolysis process to produce oxygen and syngas (carbon monoxide, CO and hydrogen, H2 mixture) for terrestrial (energy production) application. The technology is a combined process that involves steam electrolysis, CO2 electrolysis, and the reverse water gas shift (RWGS) reaction. A number of process models have been developedmore » and analyzed to determine the theoretical power required to recover oxygen, O2, in each case. These models include the current Sabatier and Bosch technologies and combinations of those processes with high-temperature co-electrolysis. The cases of constant CO2 supply and constant O2 production were evaluated. In addition, a process model of the hydrogenation process with co-electrolysis was developed and compared. Sabatier processes require the least amount of energy input per kg of oxygen produced. If co-electrolysis replaces solid polymer electrolyte (SPE) electrolysis within the Sabatier architecture, the power requirement is reduced by over 10%, but only if heat recuperation is used. Sabatier processes, however, require external water to achieve the lower power results. Under conditions of constant incoming carbon dioxide flow, the Sabatier architectures require more power than the other architectures. The Bosch, Boudouard with co-electrolysis, and the hydrogenation with co-electrolysis processes require little or no external water. The Bosch and hydrogenation processes produce water within their reactors, which aids in reducing the power requirement for electrolysis. The Boudouard with co-electrolysis process has a higher electrolysis power requirement

  6. Flow testing of the Newberry 2 research drillhole, Newberry volcano, Oregon

    USGS Publications Warehouse

    Ingebritsen, S.E.; Carothers, W.W.; Mariner, R.H.; Gudmundsson, J.S.; Sammel, E.A.

    1986-01-01

    A 20 hour flow test of the Newberry 2 research drillhole at Newberry Volcano produced about 33,000 kilograms of fluid. The flow rate declined from about 0.8 kilograms per sec to less than 0.3 kilograms per sec during the course of the test. The mass ratio of liquid water to vapor was about 3:2 at the separator and stayed fairly constant throughout the test. The vapor phase was about half steam and half CO2 by weight. The average enthalpy of the steam/water mixture at the separator was about 1 ,200 kilojoules per kilogram. Because of the low flow rate and the large temperature gradient into the surrounding rocks, heat loss from the wellbore was high; a simple conductive model gives overall losses of about 1,200 kilojoules per kilogram of H2O produced. The actual heat loss may have been even higher due to convective effects, and it is likely that the fluid entering the bottom of the wellbore was largely or entirely steam and CO2. (Author 's abstract)

  7. N2 and CO2 capillary breakthrough experiments on Opalinus Clay

    NASA Astrophysics Data System (ADS)

    Amann, Alexandra; Busch, Andreas; Krooss, Bernhard M.

    2013-04-01

    The aim of this project was to identify the critical capillary pressures on the drainage and the imbibition path for clay-rich rocks, at a burial depth of 1500 m (30 MPa confining pressure, 45°C). The experiments were performed on fully water-saturated sample plugs of 38 mm diameter and 5 to 20 mm length. The capillary breakthrough pressure was determined by step-wise increase of the differential pressure (drainage), the capillary snap-off pressure was determined from the final pressure difference at the end of a spontaneous imbibition phase. The confining pressure was kept constant throughout the experiment, which resulted in a continuous change of effective stress. The measurements were performed in a closed system and the pressure response was interpreted in terms of different flow mechanisms (diffusion-controlled vs. viscous flow). In total, four breakthrough experiments with N2 and five experiments with CO2 were conducted. Because of very low flow rates and high critical capillary pressures the experiments took rather long. In some cases the experiments were allowed to run for half a year (drainage experiments). Substantial differences were observed between gas breakthrough (drainage) and snap-off (imbibition) pressures. As expected, breakthrough pressures were always higher than the snap-off pressures. For three samples a pbreakthrough/psnap-off ratio of 1.6 to 1.9 was observed, for one sample a ratio of 4. A clear permeability-capillary pressure relationship could not be identified. Based on (omnidirectional) Hg-injection porosimetry results, and assuming perfectly water wet mineral surfaces, gas breakthrough pressures were predicted to occur at approximately 16 MPa for N2 and 5.7 MPa for CO2. The gas breakthrough experiments, however, produced different results. Even though a relatively homogeneous sample set was chosen, with permeability coefficients ranging between 1E-21 and 6E-21 m², the critical capillary breakthrough pressures for nitrogen ranged

  8. Reciprocal modulation of O2 and CO2 cardiorespiratory chemoreflexes in the tambaqui.

    PubMed

    Reid, Stephen G; Perry, Steve F; Gilmour, Kathleen M; Milsom, William K; Rantin, F Tadeu

    2005-04-15

    This study examined the effect of acute hypoxic and hypercapnic cardiorespiratory stimuli, superimposed on existing cardiorespiratory disturbances in tambaqui. In their natural habitat, these fish often encounter periods of hypoxic hypercapnia that can be acutely exacerbated by water turnover. Tambaqui were exposed to periods of normoxia, hypoxia, hyperoxia and hypercapnia during which, externally oriented O2 and CO2 chemoreceptors were further stimulated, by administration into the inspired water of sodium cyanide and CO2-equilibrated water, respectively. Hyperoxic water increased the sensitivity of the NaCN-evoked increase in breathing frequency (f(R)) and decrease in heart rate. Hypoxia and hypercapnia attenuated the increase in f(R) but, aside from blood pressure, did not influence the magnitude of NaCN-evoked cardiovascular changes. Water PO2 influenced the magnitude of the CO2-evoked cardiorespiratory changes and the sensitivity of CO2-evoked changes in heart rate and blood flow. The results indicate that existing respiratory disturbances modulate cardiorespiratory responses to further respiratory challenges reflecting both changes in chemosensitivity and the capacity for further change.

  9. One-dimensional model for the intracranial pulse morphological analysis during hyperventilation and CO2 inhalation tests

    NASA Astrophysics Data System (ADS)

    Ryu, Jaiyoung; Hu, Xiao; Shadden, Shawn C.

    2015-11-01

    The brain's CO2 reactivity mechanism is coupled with cerebral autoregulation and other unique features of cerebral hemodynamics. We developed a one-dimensional nonlinear model of blood flow in the cerebral arteries coupled to lumped parameter (LP) networks. The LP networks incorporate cerebral autoregulation, CO2 reactivity, intracranial pressure, cerebrospinal fluid, and cortical collateral blood flow models. The model was used to evaluate hemodynamic variables (arterial deformation, blood velocity and pressure) in the cerebral vasculature during hyperventilation and CO2 inhalation test. Tests were performed for various arterial blood pressure (ABP) representing normal and hypotensive conditions. The increase of the cerebral blood flow rates agreed well with the published measurements for various ABP measurements taken during clinical CO2 reactivity tests. The changes in distal vasculature affected the reflected pulse wave energy, which caused the waveform morphological changes at the middle cerebral, common and internal carotid arteries. The pulse morphological analysis demonstrated agreement with previous clinical measurements for cerebral vasoconstriction and vasodilation.

  10. Roles of melatonin in abiotic stress resistance in plants.

    PubMed

    Zhang, Na; Sun, Qianqian; Zhang, Haijun; Cao, Yunyun; Weeda, Sarah; Ren, Shuxin; Guo, Yang-Dong

    2015-02-01

    In recent years melatonin has emerged as a research highlight in plant studies. Melatonin has different functions in many aspects of plant growth and development. The most frequently mentioned functions of melatonin are related to abiotic stresses such as drought, radiation, extreme temperature, and chemical stresses. This review mainly focuses on the regulatory effects of melatonin when plants face harsh environmental conditions. Evidence indicates that environmental stress can increase the level of endogenous melatonin in plants. Overexpression of the melatonin biosynthetic genes elevates melatonin levels in transgenic plants. The transgenic plants show enhanced tolerance to abiotic stresses. Exogenously applied melatonin can also improve the ability of plants to tolerate abiotic stresses. The mechanisms by which melatonin alleviates abiotic stresses are discussed. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  11. Abiotic Supramolecular Systems

    DTIC Science & Technology

    2011-05-02

    REPORT Abiotic Supramolecular Systems 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: The goal of this research project was to develop new concepts for the...decision, unless so designated by other documentation. 12. DISTRIBUTION AVAILIBILITY STATEMENT Approved for Public Release; Distribution Unlimited UU...9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 6. AUTHORS 7. PERFORMING ORGANIZATION NAMES AND ADDRESSES U.S. Army Research Office P.O

  12. Stressed out symbiotes: hypotheses for the influence of abiotic stress on arbuscular mycorrhizal fungi.

    PubMed

    Millar, Niall S; Bennett, Alison E

    2016-11-01

    Abiotic stress is a widespread threat to both plant and soil communities. Arbuscular mycorrhizal (AM) fungi can alleviate effects of abiotic stress by improving host plant stress tolerance, but the direct effects of abiotic stress on AM fungi are less well understood. We propose two hypotheses predicting how AM fungi will respond to abiotic stress. The stress exclusion hypothesis predicts that AM fungal abundance and diversity will decrease with persistent abiotic stress. The mycorrhizal stress adaptation hypothesis predicts that AM fungi will evolve in response to abiotic stress to maintain their fitness. We conclude that abiotic stress can have effects on AM fungi independent of the effects on the host plant. AM fungal communities will change in composition in response to abiotic stress, which may mean the loss of important individual species. This could alter feedbacks to the plant community and beyond. AM fungi will adapt to abiotic stress independent of their host plant. The adaptation of AM fungi to abiotic stress should allow the maintenance of the plant-AM fungal mutualism in the face of changing climates.

  13. Measurement of Momentum Transfer Coefficients for H2, N2, CO, and CO2 Incident Upon Spacecraft Surfaces

    NASA Technical Reports Server (NTRS)

    Cook, Steven R.; Hoffbauer, Mark A.

    1997-01-01

    Measurements of momentum transfer coefficients were made for gas-surface interactions between the Space Shuttle reaction control jet plume gases and the solar panel array materials to be used on the International Space Station. Actual conditions were simulated using a supersonic nozzle source to produce beams of the gases with approximately the same average velocities as the gases have in the Shuttle plumes. Samples of the actual solar panel materials were mounted on a torsion balance that was used to measure the force exerted on the surfaces by the molecular beams. Measurements were made with H2, N2, CO, and CO2 incident upon the solar array material, Kapton, SiO2-coated Kapton, and Z93-coated Al. The measurements showed that molecules scatter from the surfaces more specularly as the angle of incidence increases and that the scattering behavior has a strong dependence upon both the incident gas and velocity. These results show that for some technical surfaces the simple assumption of diffuse scattering with complete thermal accommodation is entirely inadequate. It is clear that additional measurements are required to produce models that more accurately describe the gas-surface interactions encountered in rarefied flow regimes.

  14. Rise of nano effects in electrode during electrocatalytic CO2 conversion.

    PubMed

    Yang, Ki Dong; Lee, Chan Woo; Jang, Jun Ho; Ha, Tak Rae; Nam, Ki Tae

    2017-09-01

    The electrocatalytic conversion of CO 2 into value-added fuels has received increasing attention as a promising way to mitigate the atmospheric CO 2 concentration and close the broken carbon-cycle. Early studies, focused on polycrystalline metal electrodes, outlined in detail the overall trends in the catalytic activity and product selectivity of pure metals; however, several inherent limitations were found, such as low current density and high overpotential, which hindered electrocatalytic CO 2 reduction from practical application. Fortunately, the recent development of precisely synthesized nanocatalysts has led to several breakthroughs in catalytic CO 2 conversion. By carefully controlling the thermodynamic adsorption energies and flow dynamics of reaction intermediates, nanosized electrocatalysts afford more versatile and energetically efficient routes to convert CO 2 into desired chemicals. In this article, we review the state-of-the-art nanocatalysts applied for CO 2 conversion and discuss newly found phenomena at the local environment near the catalyst surface. The mechanistic understanding of these findings can provide insight into the future design of catalysts for the efficient and selective reduction of CO 2 .

  15. Forest Floor CO2 Flux From Two Contrasting Ecosystems in the Southern Appalachians

    Treesearch

    James M. Vose; Barton D. Clinton; Verl Emrick

    1995-01-01

    We measured forest floor CO2 flux in two contrasting ecosystems (white pine plantation and northern hardwood ecosystems at low and high elevations, respectively) in May and September 1993 to quantify differences and determine factors regulating CO2 fluxes. An automated IRGA based, flow through system was used with chambers...

  16. Assessment of CO2 Storage Potential in Naturally Fractured Reservoirs With Dual-Porosity Models

    NASA Astrophysics Data System (ADS)

    March, Rafael; Doster, Florian; Geiger, Sebastian

    2018-03-01

    Naturally Fractured Reservoirs (NFR's) have received little attention as potential CO2 storage sites. Two main facts deter from storage projects in fractured reservoirs: (1) CO2 tends to be nonwetting in target formations and capillary forces will keep CO2 in the fractures, which typically have low pore volume; and (2) the high conductivity of the fractures may lead to increased spatial spreading of the CO2 plume. Numerical simulations are a powerful tool to understand the physics behind brine-CO2 flow in NFR's. Dual-porosity models are typically used to simulate multiphase flow in fractured formations. However, existing dual-porosity models are based on crude approximations of the matrix-fracture fluid transfer processes and often fail to capture the dynamics of fluid exchange accurately. Therefore, more accurate transfer functions are needed in order to evaluate the CO2 transfer to the matrix. This work presents an assessment of CO2 storage potential in NFR's using dual-porosity models. We investigate the impact of a system of fractures on storage in a saline aquifer, by analyzing the time scales of brine drainage by CO2 in the matrix blocks and the maximum CO2 that can be stored in the rock matrix. A new model to estimate drainage time scales is developed and used in a transfer function for dual-porosity simulations. We then analyze how injection rates should be limited in order to avoid early spill of CO2 (lost control of the plume) on a conceptual anticline model. Numerical simulations on the anticline show that naturally fractured reservoirs may be used to store CO2.

  17. Comparative study of biogenic and abiotic iron-containing materials

    NASA Astrophysics Data System (ADS)

    Cherkezova-Zheleva, Z.; Shopska, M.; Paneva, D.; Kovacheva, D.; Kadinov, G.; Mitov, I.

    2016-12-01

    Series of iron-based biogenic materials prepared by cultivation of Leptothrix group of bacteria in different feeding media ( Sphaerotilus-Leptothrix group of bacteria isolation medium, Adler, Lieske and silicon-iron-glucose-peptone) were studied. Control samples were obtained in the same conditions and procedures but the nutrition media were not infected with bacteria, i.e. they were sterile. Room and low temperature Mössbauer spectroscopy, powder X-ray diffraction (XRD), and infrared spectroscopy (IRS) were used to reveal the composition and physicochemical properties of biomass and respective control samples. Comparative analysis showed differences in their composition and dispersity of present phases. Sample composition included different ratio of nanodimensional iron oxyhydroxide and oxide phases. Relaxation phenomena such as superparamagnetism or collective magnetic excitation behaviour were registered for some of them. The experimental data showed that the biogenic materials were enriched in oxyhydroxides of high dispersion. Catalytic behaviour of a selected biomass and abiotic material were studied in the reaction of CO oxidation. In situ diffuse-reflectance (DR) IRS was used to monitor the phase transformations in the biomass and CO conversion.

  18. Abiotic gene transfer: rare or rampant?

    PubMed Central

    Kotnik, Tadej; Weaver, James C.

    2016-01-01

    Phylogenetic studies reveal that horizontal gene transfer (HGT) plays a prominent role in evolution and genetic variability of life. Five biotic mechanisms of HGT among prokaryotic organisms have been extensively characterized: conjugation, competence, transduction, gene-transfer-agent (GTA) particles, and transitory fusion with recombination, but it is not known whether they can account for all natural HGT. It is even less clear how HGT could have occurred before any of these mechanisms had developed. Here, we consider contemporary conditions and experiments on microorganisms to estimate possible roles of abiotic HGT – currently and throughout evolution. Candidate mechanisms include freeze-and-thaw, microbeads-agitation, and electroporation-based transformation, and we posit that these laboratory techniques have analogues in nature acting as mechanisms of abiotic HGT: freeze-and-thaw cycles in polar waters, sand-agitation at foreshores and riverbeds, and lightning-triggered electroporation in near-surface aqueous habitats. We derive conservative order-of-magnitude estimates for rates of microorganisms subjected to freeze-and-thaw cycles, sand-agitation, and lightning-triggered electroporation, at 1024, 1019, and 1017 per year, respectively. Considering the yield of viable transformants, which is by far the highest in electroporation, we argue this may still favor lightning-triggered transformation over the other two mechanisms. Electroporation-based gene transfer also appears to be the most general of these abiotic candidates, and perhaps even of all known HGT mechanisms. Future studies should provide improved estimates of gene transfer rates and cell viability, currently and in the past, but to assess the importance of abiotic HGT in nature, will likely require substantial progress – also in knowledge of biotic HGT. PMID:27067073

  19. Designing cooperatively folded abiotic uni- and multimolecular helix bundles

    NASA Astrophysics Data System (ADS)

    de, Soumen; Chi, Bo; Granier, Thierry; Qi, Ting; Maurizot, Victor; Huc, Ivan

    2018-01-01

    Abiotic foldamers, that is foldamers that have backbones chemically remote from peptidic and nucleotidic skeletons, may give access to shapes and functions different to those of peptides and nucleotides. However, design methodologies towards abiotic tertiary and quaternary structures are yet to be developed. Here we report rationally designed interactional patterns to guide the folding and assembly of abiotic helix bundles. Computational design facilitated the introduction of hydrogen-bonding functionalities at defined locations on the aromatic amide backbones that promote cooperative folding into helix-turn-helix motifs in organic solvents. The hydrogen-bond-directed aggregation of helices not linked by a turn unit produced several thermodynamically and kinetically stable homochiral dimeric and trimeric bundles with structures that are distinct from the designed helix-turn-helix. Relative helix orientation within the bundles may be changed from parallel to tilted on subtle solvent variations. Altogether, these results prefigure the richness and uniqueness of abiotic tertiary structure behaviour.

  20. Systems biology approach in plant abiotic stresses.

    PubMed

    Mohanta, Tapan Kumar; Bashir, Tufail; Hashem, Abeer; Abd Allah, Elsayed Fathi

    2017-12-01

    Plant abiotic stresses are the major constraint on plant growth and development, causing enormous crop losses across the world. Plants have unique features to defend themselves against these challenging adverse stress conditions. They modulate their phenotypes upon changes in physiological, biochemical, molecular and genetic information, thus making them tolerant against abiotic stresses. It is of paramount importance to determine the stress-tolerant traits of a diverse range of genotypes of plant species and integrate those traits for crop improvement. Stress-tolerant traits can be identified by conducting genome-wide analysis of stress-tolerant genotypes through the highly advanced structural and functional genomics approach. Specifically, whole-genome sequencing, development of molecular markers, genome-wide association studies and comparative analysis of interaction networks between tolerant and susceptible crop varieties grown under stress conditions can greatly facilitate discovery of novel agronomic traits that protect plants against abiotic stresses. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  1. CO2 Acquisition Membrane (CAM)

    NASA Technical Reports Server (NTRS)

    Mason, Larry W.; Way, J. Douglas; Vlasse, Marcus

    2003-01-01

    The objective of CAM is to develop, test, and analyze thin film membrane materials for separation and purification of carbon dioxide (CO2) from mixtures of gases, such as those found in the Martian atmosphere. The membranes are targeted toward In Situ Resource Utilization (ISRU) applications that will operate in extraterrestrial environments and support future unmanned and human space missions. A primary application is the Sabatier Electrolysis process that uses Mars atmosphere CO2 as raw material for producing water, oxygen, and methane for rocket fuel and habitat support. Other applications include use as an inlet filter to collect and concentrate Mars atmospheric argon and nitrogen gases for habitat pressurization, and to remove CO2 from breathing gases in Closed Environment Life Support Systems (CELSS). CAM membrane materials include crystalline faujasite (FAU) zeolite and rubbery polymers such as silicone rubber (PDMS) that have been shown in the literature and via molecular simulation to favor adsorption and permeation of CO2 over nitrogen and argon. Pure gas permeation tests using commercial PDMS membranes have shown that both CO2 permeance and the separation factor relative to other gases increase as the temperature decreases, and low (Delta)P(Sub CO2) favors higher separation factors. The ideal CO2/N2 separation factor increases from 7.5 to 17.5 as temperature decreases from 22 C to -30 C. For gas mixtures containing CO2, N2, and Ar, plasticization decreased the separation factors from 4.5 to 6 over the same temperature range. We currently synthesize and test our own Na(+) FAU zeolite membranes using standard formulations and secondary growth methods on porous alumina. Preliminary tests with a Na(+) FAU membrane at 22 C show a He/SF6 ideal separation factor of 62, exceeding the Knudsen diffusion selectivity by an order of magnitude. This shows that the membrane is relatively free from large defects and associated non-selective (viscous flow) transport

  2. 2. CATCH BASIN, INFLOW PIPES AT CENTER, COLD FLOW LABORATORY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. CATCH BASIN, INFLOW PIPES AT CENTER, COLD FLOW LABORATORY AT LEFT, VIEW TOWARDS NORTHWEST. - Glenn L. Martin Company, Titan Missile Test Facilities, Catch Basin, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

  3. Abscisic Acid and abiotic stress signaling.

    PubMed

    Tuteja, Narendra

    2007-05-01

    Abiotic stress is severe environmental stress, which impairs crop production on irrigated land worldwide. Overall, the susceptibility or tolerance to the stress in plants is a coordinated action of multiple stress responsive genes, which also cross-talk with other components of stress signal transduction pathways. Plant responses to abiotic stress can be determined by the severity of the stress and by the metabolic status of the plant. Abscisic acid (ABA) is a phytohormone critical for plant growth and development and plays an important role in integrating various stress signals and controlling downstream stress responses. Plants have to adjust ABA levels constantly in responce to changing physiological and environmental conditions. To date, the mechanisms for fine-tuning of ABA levels remain elusive. The mechanisms by which plants respond to stress include both ABA-dependent and ABA-independent processes. Various transcription factors such as DREB2A/2B, AREB1, RD22BP1 and MYC/MYB are known to regulate the ABA-responsive gene expression through interacting with their corrosponding cis-acting elements such as DRE/CRT, ABRE and MYCRS/MYBRS, respectively. Understanding these mechanisms is important to improve stress tolerance in crops plants. This article first describes the general pathway for plant stress response followed by roles of ABA and transcription factors in stress tolerance including the regulation of ABA biosynthesis.

  4. Abscisic Acid and Abiotic Stress Signaling

    PubMed Central

    2007-01-01

    Abiotic stress is severe environmental stress, which impairs crop production on irrigated land worldwide. Overall, the susceptibility or tolerance to the stress in plants is a coordinated action of multiple stress responsive genes, which also cross-talk with other components of stress signal transduction pathways. Plant responses to abiotic stress can be determined by the severity of the stress and by the metabolic status of the plant. Abscisic acid (ABA) is a phytohormone critical for plant growth and development and plays an important role in integrating various stress signals and controlling downstream stress responses. Plants have to adjust ABA levels constantly in responce to changing physiological and environmental conditions. To date, the mechanisms for fine-tuning of ABA levels remain elusive. The mechanisms by which plants respond to stress include both ABA-dependent and ABA-independent processes. Various transcription factors such as DREB2A/2B, AREB1, RD22BP1 and MYC/MYB are known to regulate the ABA-responsive gene expression through interacting with their corrosponding cis-acting elements such as DRE/CRT, ABRE and MYCRS/MYBRS, respectively. Understanding these mechanisms is important to improve stress tolerance in crops plants. This article first describes the general pathway for plant stress response followed by roles of ABA and transcription factors in stress tolerance including the regulation of ABA biosynthesis. PMID:19516981

  5. The FP7 ULTimateCO2 project: a study of the long term fate of CO2

    NASA Astrophysics Data System (ADS)

    Audigane, Pascal; Waldmann, Svenja; Pearce, Jonathan; Dimier, Alain; Le Gallo, Yann; Frykman, Peter; Maurand, Nicolas; Gherardi, Fabrizio; Yalamas, Thierry; Cremer, Holger; Spiers, Chris; Nussbaum, Christophe

    2014-05-01

    The objectives of the European FP7 ULTimateCO2 project are to study specific processes that could influence the long-term fate of geologically stored CO2, mainly: the trapping mechanisms occurring in the storage reservoir, the influence of fluid-rock interactions on mechanical integrity of caprock and well vicinity, and also the modifications induced at the regional scale (brine displacement, fault reactivation, hydrogeology changes...). A comprehensive approach combining laboratory experiments, numerical modeling and natural analogue studies is developed to assess all the processes mentioned above. A collection of data has been generated from natural and industrial (oil industry) analogues on the fluid flow and mechanical properties, structure, and mineralogy of faults and fractures that could affect the long-term storage capacity of underground CO2 storage sites. To address geochemical trapping at reservoir scale, an experimental approach is developed using sandstone core materials in batch reactive mode with CO2 and impurities at reservoir pressure and temperature conditions. Three inter-related lines of laboratory experiments investigate the long-term evolution of the mechanical properties and sealing integrity of fractured and faulted caprocks using Opalinus clay of Mont Terri Gallery (Switzerland), an analogue for caprock well investigated in the past for nuclear waste disposal purpose. To evaluate the interactions between CO2 (and formation fluid) and the well environment (formation, cement, casing) and to assess the consequences of these interactions on the transport properties of well materials, a 1 to 1 scale experiment has been set in the Mont Terri Gallery Opalinus clay to reproduce classical well objects (cemented annulus, casing and cement plug) perforating caprock formations. An extensive program of numerical modeling is also developed to calibrate, to reproduce and to extrapolate the experimental results at longer time scales including uncertainty

  6. Geologic Sequestration of CO2: Potential Permeability Changes in Host Formations of the San Juan Basin, New Mexico

    NASA Astrophysics Data System (ADS)

    Abel, A. P.; McPherson, B.; Lichtner, P.; Bond, G.; Stringer, J.; Grigg, R.

    2002-12-01

    Terrestrial sequestration through injection into geologic formations is one proposed method for the isolation of anthropogenic CO2 from the atmosphere. A variety of physical and chemical processes are known to occur both during and after geologic CO2 injection, including diagenetic chemical reactions and associated permeability changes. Although it is commonly assumed that CO2 sequestered in this way will ultimately become mineralized, the rates of these changes, including CO2 hydration in brines, are known to be relatively slow. Bond and others (this volume) have developed a biomimetic approach to CO2 sequestration, in which the rate of CO2 hydration is accelerated by the use of a biological catalyst. Together with the hydrated CO2, cations from produced brines may be used to form solid-state carbonate minerals at the earth's surface, or this bicarbonate solution may be reinjected for geologic sequestration. Chemical composition of produced brines will affect both the diagenetic reactions that occur within the host formation, and the precipitation reactions that will occur above ground. In a specific case study of the San Juan Basin, New Mexico, we are cataloging different brines present in that basin. We are using this information to facilitate evaluation of potential applications of the biomimetic process and geologic sequestration. In a separate collaborative study by Grigg and others (this volume), laboratory experiments have been conducted on multiphase CO2 and brine injection and flow through saturated rock cores. We are extending from that study to our specific case study of the San Juan basin, to examine and characterize potential permeability changes associated with accelerated diagenesis due to the presence of high concentrations of CO2 or bicarbonate solutions in situ. We are developing and conducting new laboratory experiments to evaluate relative permeability (to CO2 and brine) of selected strata from the Fruitland Formation and Pictured Cliffs

  7. Poly(ethylenimine)-Functionalized Monolithic Alumina Honeycomb Adsorbents for CO2 Capture from Air.

    PubMed

    Sakwa-Novak, Miles A; Yoo, Chun-Jae; Tan, Shuai; Rashidi, Fereshteh; Jones, Christopher W

    2016-07-21

    The development of practical and effective gas-solid contactors is an important area in the development of CO2 capture technologies. Target CO2 capture applications, such as postcombustion carbon capture and sequestration (CCS) from power plant flue gases or CO2 extraction directly from ambient air (DAC), require high flow rates of gas to be processed at low cost. Extruded monolithic honeycomb structures, such as those employed in the catalytic converters of automobiles, have excellent potential as structured contactors for CO2 adsorption applications because of the low pressure drop imposed on fluid moving through the straight channels of such structures. Here, we report the impregnation of poly(ethylenimine) (PEI), an effective aminopolymer reported commonly for CO2 separation, into extruded monolithic alumina to form structured CO2 sorbents. These structured sorbents are first prepared on a small scale, characterized thoroughly, and compared with powder sorbents with a similar composition. Despite consistent differences observed in the filling of mesopores with PEI between the monolithic and powder sorbents, their performance in CO2 adsorption is similar across a range of PEI contents. A larger monolithic cylinder (1 inch diameter, 4 inch length) is evaluated under conditions closer to those that might be used in large-scale applications and shows a similar performance to the smaller monoliths and powders tested initially. This larger structure is evaluated over five cycles of CO2 adsorption and steam desorption and demonstrates a volumetric capacity of 350 molCO2  m-3monolith and an equilibration time of 350 min under a 0.4 m s(-1) linear flow velocity through the monolith channels using 400 ppm CO2 in N2 as the adsorption gas at 30 °C. This volumetric capacity surpasses that of a similar technology considered previously, which suggested that CO2 could be removed from air at an operating cost as low as $100 per ton. © 2016 WILEY-VCH Verlag

  8. The Effect of Increased CO2 Mixing Ratio on Water Use Efficiency, Evapo-transpiration, Soil Moisture Content and Stem Flow in two Long-term Field Experiments

    NASA Astrophysics Data System (ADS)

    Drake, B.; Powell, T.; Li, J.; Hinkle, R.; Rasse, D.

    2007-12-01

    Stomatal opening in plant leaves control carbon and water exchange between vegetation and the atmosphere. Closure of these water-gates in response to increased atmospheric CO2 mixing ratio's, reduces transpiration under most laboratory and short term experimental conditions. Does this imply however, as atmospheric CO2 rises, and plant canopies expand, that evapo-transpiration (ETR), soil moisture content (SMC), and ecosystem water use efficiency (WUE) will increase? To test this question, field experiments have been and still are conducted using open top chambers. We have exposed native species in Florida Scrub to a carbon dioxide mixing ratio of nearly 700 ppmv CO2 for the past ten years and in Chesapeake Bay wetlands for 21 years. As a result of this treatment, in both ecosystems there was an increase in net ecosystem CO2 exchange and leaf area but a reduction of stomatal conductance, stem flow, transpiration, and ETR. For Florida scrub oak, these changes were also accompanied by an increase in soil moisture content as well.

  9. Salicylic acid-induced abiotic stress tolerance and underlying mechanisms in plants

    PubMed Central

    Khan, M. Iqbal R.; Fatma, Mehar; Per, Tasir S.; Anjum, Naser A.; Khan, Nafees A.

    2015-01-01

    Abiotic stresses (such as metals/metalloids, salinity, ozone, UV-B radiation, extreme temperatures, and drought) are among the most challenging threats to agricultural system and economic yield of crop plants. These stresses (in isolation and/or combination) induce numerous adverse effects in plants, impair biochemical/physiological and molecular processes, and eventually cause severe reductions in plant growth, development and overall productivity. Phytohormones have been recognized as a strong tool for sustainably alleviating adverse effects of abiotic stresses in crop plants. In particular, the significance of salicylic acid (SA) has been increasingly recognized in improved plant abiotic stress-tolerance via SA-mediated control of major plant-metabolic processes. However, the basic biochemical/physiological and molecular mechanisms that potentially underpin SA-induced plant-tolerance to major abiotic stresses remain least discussed. Based on recent reports, this paper: (a) overviews historical background and biosynthesis of SA under both optimal and stressful environments in plants; (b) critically appraises the role of SA in plants exposed to major abiotic stresses; (c) cross-talks potential mechanisms potentially governing SA-induced plant abiotic stress-tolerance; and finally (d) briefly highlights major aspects so far unexplored in the current context. PMID:26175738

  10. On the losses of dissolved CO(2) during champagne serving.

    PubMed

    Liger-Belair, Gérard; Bourget, Marielle; Villaume, Sandra; Jeandet, Philippe; Pron, Hervé; Polidori, Guillaume

    2010-08-11

    Pouring champagne into a glass is far from being consequenceless with regard to its dissolved CO(2) concentration. Measurements of losses of dissolved CO(2) during champagne serving were done from a bottled Champagne wine initially holding 11.4 +/- 0.1 g L(-1) of dissolved CO(2). Measurements were done at three champagne temperatures (i.e., 4, 12, and 18 degrees C) and for two different ways of serving (i.e., a champagne-like and a beer-like way of serving). The beer-like way of serving champagne was found to impact its concentration of dissolved CO(2) significantly less. Moreover, the higher the champagne temperature is, the higher its loss of dissolved CO(2) during the pouring process, which finally constitutes the first analytical proof that low temperatures prolong the drink's chill and helps it to retain its effervescence during the pouring process. The diffusion coefficient of CO(2) molecules in champagne and champagne viscosity (both strongly temperature-dependent) are suspected to be the two main parameters responsible for such differences. Besides, a recently developed dynamic-tracking technique using IR thermography was also used in order to visualize the cloud of gaseous CO(2) which flows down from champagne during the pouring process, thus visually confirming the strong influence of champagne temperature on its loss of dissolved CO(2).

  11. BIOTIC AND ABIOTIC CONTRIBUTIONS TO REDUCTIVE TRANSFORMATION OF ORGANIC POLLUTANTS

    EPA Science Inventory

    The relative contributions of biotic and abiotic reductive transformation reactions were probed in two anoxic freshwater sediments by following the transformation of nitrobenzene, and 2,4 dichlorophenol (compounds with different one electron reduction potentials). The sediments d...

  12. Interaction Between CO2-Rich Sulfate Solutions and Carbonate Reservoir Rocks from Atmospheric to Supercritical CO2 Conditions: Experiments and Modeling

    NASA Astrophysics Data System (ADS)

    Cama, J.; Garcia-Rios, M.; Luquot, L.; Soler Matamala, J. M.

    2014-12-01

    A test site for CO2 geological storage is situated in Hontomín (Spain) with a reservoir rock that is mainly composed of limestone. During and after CO2 injection, the resulting CO2-rich acid brine gives rise to the dissolution of carbonate minerals (calcite and dolomite) and gypsum (or anhydrite at depth) may precipitate since the reservoir brine contains sulfate. Experiments using columns filled with crushed limestone or dolostone were conducted under different P-pCO2 conditions (atmospheric: 1-10-3.5 bar; subcritical: 10-10 bar; and supercritical: 150-34 bar), T (25, 40 and 60 ºC) and input solution compositions (gypsum-undersaturated and gypsum-equilibrated solutions). We evaluated the effect of these parameters on the coupled reactions of calcite/dolomite dissolution and gypsum/anhydrite precipitation. The CrunchFlow and PhreeqC (v.3) numerical codes were used to perform reactive transport simulations of the experiments. Under the P-pCO2-T conditions, the volume of precipitated gypsum was smaller than the volume of dissolved carbonate minerals, yielding an increase in porosity (Δporosity up to ≈ 4%). A decrease in T favored limestone dissolution regardless of pCO2 owing to increasing undersaturation with decreasing temperature. However, gypsum precipitation was favored at high T and under atmospheric pCO2 conditions but not at high T and under 10 bar of pCO2 conditions. The increase in limestone dissolution with pCO2 was directly attributed to pH, which was more acidic at higher pCO2. Increasing pCO2, carbonate dissolution occurred along the column whereas it was localized in the very inlet under atmospheric conditions. This was due to the buffer capacity of the carbonic acid, which maintains pH at around 5 and keeps the solution undersaturated with respect to calcite and dolomite along the column. 1D reactive transport simulations reproduced the experimental data (carbonate dissolution and gypsum precipitation for different P-pCO2-T conditions). Drawing

  13. CO2 Permeability of Biological Membranes and Role of CO2 Channels

    PubMed Central

    Endeward, Volker; Arias-Hidalgo, Mariela; Al-Samir, Samer; Gros, Gerolf

    2017-01-01

    We summarize here, mainly for mammalian systems, the present knowledge of (a) the membrane CO2 permeabilities in various tissues; (b) the physiological significance of the value of the CO2 permeability; (c) the mechanisms by which membrane CO2 permeability is modulated; (d) the role of the intracellular diffusivity of CO2 for the quantitative significance of cell membrane CO2 permeability; (e) the available evidence for the existence of CO2 channels in mammalian and artificial systems, with a brief view on CO2 channels in fishes and plants; and, (f) the possible significance of CO2 channels in mammalian systems. PMID:29064458

  14. Veno-venous extracorporeal CO2 removal for the treatment of severe respiratory acidosis: pathophysiological and technical considerations.

    PubMed

    Karagiannidis, Christian; Kampe, Kristin Aufm; Sipmann, Fernando Suarez; Larsson, Anders; Hedenstierna, Goran; Windisch, Wolfram; Mueller, Thomas

    2014-06-17

    While non-invasive ventilation aimed at avoiding intubation has become the modality of choice to treat mild to moderate acute respiratory acidosis, many severely acidotic patients (pH <7.20) still need intubation. Extracorporeal veno-venous CO2 removal (ECCO2R) could prove to be an alternative. The present animal study tested in a systematic fashion technical requirements for successful ECCO2R in terms of cannula size, blood and sweep gas flow. ECCO2R with a 0.98 m(2) surface oxygenator was performed in six acidotic (pH <7.20) pigs using either a 14.5 French (Fr) or a 19Fr catheter, with sweep gas flow rates of 8 and 16 L/minute, respectively. During each experiment the blood flow was incrementally increased to a maximum of 400 mL/minute (14.5Fr catheter) and 1000 mL/minute (19Fr catheter). Amelioration of severe respiratory acidosis was only feasible when blood flow rates of 750 to 1000 mL/minute (19Fr catheter) were used. Maximal CO2-elimination was 146.1 ± 22.6 mL/minute, while pH increased from 7.13 ± 0.08 to 7.41 ± 0.07 (blood flow of 1000 mL/minute; sweep gas flow 16 L/minute). Accordingly, a sweep gas flow of 8 L/minute resulted in a maximal CO2-elimination rate of 138.0 ± 16.9 mL/minute. The 14.5Fr catheter allowed a maximum CO2 elimination rate of 77.9 mL/minute, which did not result in the normalization of pH. Veno-venous ECCO2R may serve as a treatment option for severe respiratory acidosis. In this porcine model, ECCO2R was most effective when using blood flow rates ranging between 750 and 1000 mL/minute, while an increase in sweep gas flow from 8 to 16 L/minute had less impact on ECCO2R in this setting.

  15. Investigation of CO2 emission reduction strategy from in-use gasoline vehicle

    NASA Astrophysics Data System (ADS)

    Choudhary, Arti; Gokhale, Sharad

    2016-04-01

    On road transport emissions is kicking off in Indian cities due to high levels of urbanization and economic growth during the last decade in Indian subcontinent. In 1951, about 17% of India's population were living in urban areas that increased to 32% in 2011. Currently, India is fourth largest Green House Gas (GHG) emitter in the world, with its transport sector being the second largest contributor of CO2 emissions. For achieving prospective carbon reduction targets, substantial opportunity among in-use vehicle is necessary to quantify. Since, urban traffic flow and operating condition has significant impact on exhaust emission (Choudhary and Gokhale, 2016). This study examined the influence of vehicular operating kinetics on CO2 emission from predominant private transportation vehicles of Indian metropolitan city, Guwahati. On-board instantaneous data were used to quantify the impact of CO2 emission on different mileage passenger cars and auto-rickshaws at different times of the day. Further study investigates CO2 emission reduction strategies by using International Vehicle Emission (IVE) model to improve co-benefit in private transportation by integrated effort such as gradual phase-out of inefficient vehicle and low carbon fuel. The analysis suggests that fuel type, vehicles maintenance and traffic flow management have potential for reduction of urban sector GHG emissions. Keywords: private transportation, CO2, instantaneous emission, IVE model Reference Choudhary, A., Gokhale, S. (2016). Urban real-world driving traffic emissions during interruption and congestion. Transportation Research Part D: Transport and Environment 43: 59-70.

  16. Elevated-CO2 Response of Stomata and Its Dependence on Environmental Factors

    PubMed Central

    Xu, Zhenzhu; Jiang, Yanling; Jia, Bingrui; Zhou, Guangsheng

    2016-01-01

    Stomata control the flow of gases between plants and the atmosphere. This review is centered on stomatal responses to elevated CO2 concentration and considers other key environmental factors and underlying mechanisms at multiple levels. First, an outline of general responses in stomatal conductance under elevated CO2 is presented. Second, stomatal density response, its development, and the trade-off with leaf growth under elevated CO2 conditions are depicted. Third, the molecular mechanism regulating guard cell movement at elevated CO2 is suggested. Finally, the interactive effects of elevated CO2 with other factors critical to stomatal behavior are reviewed. It may be useful to better understand how stomata respond to elevated CO2 levels while considering other key environmental factors and mechanisms, including molecular mechanism, biochemical processes, and ecophysiological regulation. This understanding may provide profound new insights into how plants cope with climate change. PMID:27242858

  17. Soil respiration in the cold desert environment of the Colorado Plateau (USA): Abiotic regulators and thresholds

    USGS Publications Warehouse

    Fernandez, D.P.; Neff, J.C.; Belnap, J.; Reynolds, R.L.

    2006-01-01

    Decomposition is central to understanding ecosystem carbon exchange and nutrient-release processes. Unlike mesic ecosystems, which have been extensively studied, xeric landscapes have received little attention; as a result, abiotic soil-respiration regulatory processes are poorly understood in xeric environments. To provide a more complete and quantitative understanding about how abiotic factors influence soil respiration in xeric ecosystems, we conducted soil- respiration and decomposition-cloth measurements in the cold desert of southeast Utah. Our study evaluated when and to what extent soil texture, moisture, temperature, organic carbon, and nitrogen influence soil respiration and examined whether the inverse-texture hypothesis applies to decomposition. Within our study site, the effect of texture on moisture, as described by the inverse texture hypothesis, was evident, but its effect on decomposition was not. Our results show temperature and moisture to be the dominant abiotic controls of soil respiration. Specifically, temporal offsets in temperature and moisture conditions appear to have a strong control on soil respiration, with the highest fluxes occurring in spring when temperature and moisture were favorable. These temporal offsets resulted in decomposition rates that were controlled by soil moisture and temperature thresholds. The highest fluxes of CO2 occurred when soil temperature was between 10 and 16??C and volumetric soil moisture was greater than 10%. Decomposition-cloth results, which integrate decomposition processes across several months, support the soil-respiration results and further illustrate the seasonal patterns of high respiration rates during spring and low rates during summer and fall. Results from this study suggest that the parameters used to predict soil respiration in mesic ecosystems likely do not apply in cold-desert environments. ?? Springer 2006.

  18. Generation of RNA in abiotic conditions.

    NASA Astrophysics Data System (ADS)

    di Mauro, Ernesto

    Generation of RNA in abiotic conditions. Ernesto Di Mauro Dipartimento di Genetica Bi-ologia Molecolare, Universit` "Sapienza" Roma, Italy. a At least four conditions must be satisfied for the spontaneous generation of (pre)-genetic poly-mers: 1) availability of precursors that are activated enough to spontaneously polymerize. Preliminary studies showed that (a) nucleic bases and acyclonucleosides can be synthesized from formamide H2NCOH by simply heating with prebiotically available mineral catalysts [last reviewed in (1)], and that b) nucleic bases can be phosphorylated in every possible posi-tion [2'; 3'; 5'; cyclic 2',3'; cyclic 3',5' (2)]. The higher stability of the cyclic forms allows their accumulation. 2) A polymerization mechanism. A reaction showing the formation of RNA polymers starting from prebiotically plausible precursors (3',5' cyclic GMP and 3', 5'cyclic AMP) was recently reported (3). Polymerization in these conditions is thermodynamically up-hill and an equilibrium is attained that limits the maximum length of the polymer produced to about 40 nucleotides for polyG and 100 nucleotides for polyA. 3) Ligation of the synthesized oligomers. If this type of reaction could occur according to a terminal-joining mechanism and could generate canonical 3',5' phosphodiester bonds, exponential growth would be obtained of the generated oligomers. This type of reaction has been reported (4) , limited to homogeneous polyA sequences and leading to the production of polyA dimers and tetramers. What is still missing are: 4) mechanisms that provide the proof of principle for the generation of sequence complexity. We will show evidence for two mechanisms providing this proof of principle for simple complementary sequences. Namely: abiotic sequence complementary-driven terminal ligation and sequence-complementary terminal growth. In conclusion: all the steps leading to the generation of RNA in abiotic conditions are satisfied. (1) R Saladino, C Crestini, F

  19. REDUCING UNCERTAINTIES IN MODEL PREDICTIONS VIA HISTORY MATCHING OF CO2 MIGRATION AND REACTIVE TRANSPORT MODELING OF CO2 FATE AT THE SLEIPNER PROJECT

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

    Zhu, Chen

    2015-03-31

    An important question for the Carbon Capture, Storage, and Utility program is “can we adequately predict the CO2 plume migration?” For tracking CO2 plume development, the Sleipner project in the Norwegian North Sea provides more time-lapse seismic monitoring data than any other sites, but significant uncertainties still exist for some of the reservoir parameters. In Part I, we assessed model uncertainties by applying two multi-phase compositional simulators to the Sleipner Benchmark model for the uppermost layer (Layer 9) of the Utsira Sand and calibrated our model against the time-lapsed seismic monitoring data for the site from 1999 to 2010. Approximatemore » match with the observed plume was achieved by introducing lateral permeability anisotropy, adding CH4 into the CO2 stream, and adjusting the reservoir temperatures. Model-predicted gas saturation, CO2 accumulation thickness, and CO2 solubility in brine—none were used as calibration metrics—were all comparable with the interpretations of the seismic data in the literature. In Part II & III, we evaluated the uncertainties of predicted long-term CO2 fate up to 10,000 years, due to uncertain reaction kinetics. Under four scenarios of the kinetic rate laws, the temporal and spatial evolution of CO2 partitioning into the four trapping mechanisms (hydrodynamic/structural, solubility, residual/capillary, and mineral) was simulated with ToughReact, taking into account the CO2-brine-rock reactions and the multi-phase reactive flow and mass transport. Modeling results show that different rate laws for mineral dissolution and precipitation reactions resulted in different predicted amounts of trapped CO2 by carbonate minerals, with scenarios of the conventional linear rate law for feldspar dissolution having twice as much mineral trapping (21% of the injected CO2) as scenarios with a Burch-type or Alekseyev et al.–type rate law for feldspar dissolution (11%). So far, most reactive transport modeling (RTM

  20. Constraining the effects of permeability uncertainty for geologic CO2 sequestration in a basalt reservoir

    NASA Astrophysics Data System (ADS)

    Jayne, R., Jr.; Pollyea, R.

    2016-12-01

    Carbon capture and sequestration (CCS) in geologic reservoirs is one strategy for reducing anthropogenic CO2 emissions from large-scale point-source emitters. Recent developments at the CarbFix CCS pilot in Iceland have shown that basalt reservoirs are highly effective for permanent mineral trapping on the basis of CO2-water-rock interactions, which result in the formation of carbonates minerals. In order to advance our understanding of basalt sequestration in large igneous provinces, this research uses numerical simulation to evaluate the feasibility of industrial-scale CO2 injections in the Columbia River Basalt Group (CRBG). Although bulk reservoir properties are well constrained on the basis of field and laboratory testing from the Wallula Basalt Sequestration Pilot Project, there remains significant uncertainty in the spatial distribution of permeability at the scale of individual basalt flows. Geostatistical analysis of hydrologic data from 540 wells illustrates that CRBG reservoirs are reasonably modeled as layered heterogeneous systems on the basis of basalt flow morphology; however, the regional dataset is insufficient to constrain permeability variability at the scale of an individual basalt flow. As a result, permeability distribution for this modeling study is established by centering the lognormal permeability distribution in the regional dataset over the bulk permeability measured at Wallula site, which results in a spatially random permeability distribution within the target reservoir. In order to quantify the effects of this permeability uncertainty, CO2 injections are simulated within 50 equally probable synthetic reservoir domains. Each model domain comprises three-dimensional geometry with 530,000 grid blocks, and fracture-matrix interaction is simulated as interacting continua for the two low permeability layers (flow interiors) bounding the injection zone. Results from this research illustrate that permeability uncertainty at the scale of

  1. Basin-Scale Hydrologic Impacts of CO2 Storage: Regulatory and Capacity Implications

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

    Birkholzer, J.T.; Zhou, Q.

    Industrial-scale injection of CO{sub 2} into saline sedimentary basins will cause large-scale fluid pressurization and migration of native brines, which may affect valuable groundwater resources overlying the deep sequestration reservoirs. In this paper, we discuss how such basin-scale hydrologic impacts can (1) affect regulation of CO{sub 2} storage projects and (2) may reduce current storage capacity estimates. Our assessment arises from a hypothetical future carbon sequestration scenario in the Illinois Basin, which involves twenty individual CO{sub 2} storage projects in a core injection area suitable for long-term storage. Each project is assumed to inject five million tonnes of CO{sub 2}more » per year for 50 years. A regional-scale three-dimensional simulation model was developed for the Illinois Basin that captures both the local-scale CO{sub 2}-brine flow processes and the large-scale groundwater flow patterns in response to CO{sub 2} storage. The far-field pressure buildup predicted for this selected sequestration scenario suggests that (1) the area that needs to be characterized in a permitting process may comprise a very large region within the basin if reservoir pressurization is considered, and (2) permits cannot be granted on a single-site basis alone because the near- and far-field hydrologic response may be affected by interference between individual sites. Our results also support recent studies in that environmental concerns related to near-field and far-field pressure buildup may be a limiting factor on CO{sub 2} storage capacity. In other words, estimates of storage capacity, if solely based on the effective pore volume available for safe trapping of CO{sub 2}, may have to be revised based on assessments of pressure perturbations and their potential impact on caprock integrity and groundwater resources, respectively. We finally discuss some of the challenges in making reliable predictions of large-scale hydrologic impacts related to CO{sub 2

  2. Effect of the greenhouse gases (CO2, H2O, SO2) on Martian paleoclimate

    NASA Technical Reports Server (NTRS)

    Postawko, S. E.; Kuhn, W. R.

    1986-01-01

    There is general agreement that certain surface features on Mars are indicative of the presence of liquid water at various times in the geologic past. In particular, the valley networks are difficult to explain by a mechanism other than the flow of liquid water. It has been suggested in several studies that a thick CO2 atmosphere on Mars early in its history could have provided a greenhouse warming that would have allowed the flow of water either on the surface or just below the surface. However, this effect was examined with a detailed radiation model, and it was found that if reduced solar luminosity early in the history of the solar system is taken into account, even three bars of CO2 will not provide sufficient greeenhouse warming. The addition of water vapor and sulflur dioxide (both plausible gases that may have been emitted by Martian volcanoes) to the atmosphere also fail to warm the surface above 273 K for reduced solar luminosity conditions. The increase in temperature may be large enough, however, for the formation of these features by brines.

  3. Combining CO 2 reduction with propane oxidative dehydrogenation over bimetallic catalysts

    DOE PAGES

    Gomez, Elaine; Kattel, Shyam; Yan, Binhang; ...

    2018-04-11

    In this paper, the inherent variability and insufficiencies in the co-production of propylene from steam crackers has raised concerns regarding the global propylene production gap and has directed industry to develop more on-purpose propylene technologies. The oxidative dehydrogenation of propane by CO 2 (CO 2-ODHP) can potentially fill this gap while consuming a greenhouse gas. Non-precious FeNi and precious NiPt catalysts supported on CeO 2 have been identified as promising catalysts for CO 2-ODHP and dry reforming, respectively, in flow reactor studies conducted at 823 K. In-situ X-ray absorption spectroscopy measurements revealed the oxidation states of metals under reaction conditionsmore » and density functional theory calculations were utilized to identify the most favorable reaction pathways over the two types of catalysts.« less

  4. Injection of Super-Critical CO2 in Brine Saturated Sandstone:

    NASA Astrophysics Data System (ADS)

    Ott, Holger; de Kloe, Kees; Taberner, Conxita; Marcelis, Fons; Makurat, Axel

    2010-05-01

    Presently, large-scale geological sequestration of CO2, originating from sources like fossil-fueled power plants and contaminated gas production, is seen as an option to reduce anthropogenic emission of greenhouse gases to the atmosphere. Deep saline aquifers and depleted oil and gas fields are potential subsurface deposits for CO2. Injected CO2, however, interacts physically and chemically with the formation leading to uncertainties for CCS projects. One of these uncertainties is related to a dry-out zone that is likely to form around the well bore owing to the injection of dry CO2. Precipitation of salt (mainly halite) that is associated with that drying out of a saline formation has the potential to impair injectivity, and could even lead to the loss of a well. If dry (or under-saturated), super-critical (SC) CO2 is injected into water-bearing geological formations like saline aquifers, water is removed by either advection of the aqueous phase or by evaporation of water and subsequent advection in the injected CO2-rich phase. Both mechanisms act in parallel, however while advection of the aqueous phase decreases with increasing CO2 saturation (diminished mobility), evaporation becomes increasingly important as the aqueous phase becomes immobile. Below residual water saturation, only evaporation takes place and the formation dries out if no additional source of water is available. If water evaporates, the salts originally present in the water are left behind. In case of highly saline formations, the amount of salt that potentially precipitates per unit volume can be quite substantial. It depends on salinity, the solubility limit of water in the CO2 rich phase, and on the ratio of advection and evaporation rates. Since saturations and flow rates cover a large range as functions of space and time close to the well bore, there is no easy answer to the questions whether, where and how salt precipitation impacts injectivity. The present paper presents results of core

  5. High CO2 triggers preferential root growth of Arabidopsis thaliana via two distinct systems under low pH and low N stresses.

    PubMed

    Hachiya, Takushi; Sugiura, Daisuke; Kojima, Mikiko; Sato, Shigeru; Yanagisawa, Shuichi; Sakakibara, Hitoshi; Terashima, Ichiro; Noguchi, Ko

    2014-02-01

    Biomass allocation between shoots and roots is an important strategy used by plants to optimize growth in various environments. Root to shoot mass ratios typically increase in response to high CO2, a trend particularly evident under abiotic stress. We investigated this preferential root growth (PRG) in Arabidopsis thaliana plants cultivated under low pH/high CO2 or low nitrogen (N)/high CO2 conditions. Previous studies have suggested that changes in plant hormone, carbon (C) and N status may be related to PRG. We therefore examined the mechanisms underlying PRG by genetically modifying cytokinin (CK) levels, C and N status, and sugar signaling, performing sugar application experiments and determining primary metabolites, plant hormones and expression of related genes. Both low pH/high CO2 and low N/high CO2 stresses induced increases in lateral root (LR) number and led to high C/N ratios; however, under low pH/high CO2 conditions, large quantities of C were accumulated, whereas under low N/high CO2 conditions, N was severely depleted. Analyses of a CK-deficient mutant and a starchless mutant, in conjunction with sugar application experiments, revealed that these stresses induce PRG via different mechanisms. Metabolite and hormone profile analysis indicated that under low pH/high CO2 conditions, excess C accumulation may enhance LR number through the dual actions of increased auxin and decreased CKs.

  6. High CO2 Triggers Preferential Root Growth of Arabidopsis thaliana Via Two Distinct Systems Under Low pH and Low N Stresses

    PubMed Central

    Hachiya, Takushi; Sugiura, Daisuke; Kojima, Mikiko; Sato, Shigeru; Yanagisawa, Shuichi; Sakakibara, Hitoshi; Terashima, Ichiro; Noguchi, Ko

    2014-01-01

    Biomass allocation between shoots and roots is an important strategy used by plants to optimize growth in various environments. Root to shoot mass ratios typically increase in response to high CO2, a trend particularly evident under abiotic stress. We investigated this preferential root growth (PRG) in Arabidopsis thaliana plants cultivated under low pH/high CO2 or low nitrogen (N)/high CO2 conditions. Previous studies have suggested that changes in plant hormone, carbon (C) and N status may be related to PRG. We therefore examined the mechanisms underlying PRG by genetically modifying cytokinin (CK) levels, C and N status, and sugar signaling, performing sugar application experiments and determining primary metabolites, plant hormones and expression of related genes. Both low pH/high CO2 and low N/high CO2 stresses induced increases in lateral root (LR) number and led to high C/N ratios; however, under low pH/high CO2 conditions, large quantities of C were accumulated, whereas under low N/high CO2 conditions, N was severely depleted. Analyses of a CK-deficient mutant and a starchless mutant, in conjunction with sugar application experiments, revealed that these stresses induce PRG via different mechanisms. Metabolite and hormone profile analysis indicated that under low pH/high CO2 conditions, excess C accumulation may enhance LR number through the dual actions of increased auxin and decreased CKs. PMID:24401956

  7. Preparation of zein nanoparticles by using solution-enhanced dispersion with supercritical CO2 and elucidation with computational fluid dynamics

    PubMed Central

    Li, Sining; Zhao, Yaping

    2017-01-01

    Nanoparticles have attracted more and more attention in the medicinal field. Zein is a biomacromolecule and can be used as a carrier for delivering active ingredients to prepare controlled release drugs. In this article, we presented the preparation of zein nanoparticles by solution-enhanced dispersion by supercritical CO2 (SEDS) approach. Scanning electron microscopy and transmission electron microscopy were applied to characterize the size and morphology of the obtained particles. The nozzle structure and the CO2 flow rate greatly affected the morphology and the size of the particles. The size of zein was able to be reduced to 50–350 nm according to the different conditions. The morphologies of the resultant zein were either sphere or the filament network consisted of nanoparticles. The influence of the nozzle structure and the CO2 flow rate on the velocity field was elucidated by using computational fluid dynamics. The nozzle structure and the CO2 flow rate greatly affected the distribution of the velocity field. However, a similar velocity field could also be obtained when the nozzle structure or the CO2 flow rate, or both were different. Therefore, the influence of the nozzle structure and the CO2 flow rate on the size and morphology of the particles, can boil down to the velocity field. The results demonstrated that the velocity field can be a potential criterion for producing nanoparticles with controllable morphology and size, which is useful to scale-up the SEDS process. PMID:28496324

  8. Preparation of zein nanoparticles by using solution-enhanced dispersion with supercritical CO2 and elucidation with computational fluid dynamics.

    PubMed

    Li, Sining; Zhao, Yaping

    2017-01-01

    Nanoparticles have attracted more and more attention in the medicinal field. Zein is a biomacromolecule and can be used as a carrier for delivering active ingredients to prepare controlled release drugs. In this article, we presented the preparation of zein nanoparticles by solution-enhanced dispersion by supercritical CO 2 (SEDS) approach. Scanning electron microscopy and transmission electron microscopy were applied to characterize the size and morphology of the obtained particles. The nozzle structure and the CO 2 flow rate greatly affected the morphology and the size of the particles. The size of zein was able to be reduced to 50-350 nm according to the different conditions. The morphologies of the resultant zein were either sphere or the filament network consisted of nanoparticles. The influence of the nozzle structure and the CO 2 flow rate on the velocity field was elucidated by using computational fluid dynamics. The nozzle structure and the CO 2 flow rate greatly affected the distribution of the velocity field. However, a similar velocity field could also be obtained when the nozzle structure or the CO 2 flow rate, or both were different. Therefore, the influence of the nozzle structure and the CO 2 flow rate on the size and morphology of the particles, can boil down to the velocity field. The results demonstrated that the velocity field can be a potential criterion for producing nanoparticles with controllable morphology and size, which is useful to scale-up the SEDS process.

  9. Recovery Act: Web-based CO{sub 2} Subsurface Modeling

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

    Paolini, Christopher; Castillo, Jose

    2012-11-30

    The Web-based CO{sub 2} Subsurface Modeling project focused primarily on extending an existing text-only, command-line driven, isothermal and isobaric, geochemical reaction-transport simulation code, developed and donated by Sienna Geodynamics, into an easier-to-use Web-based application for simulating long-term storage of CO{sub 2} in geologic reservoirs. The Web-based interface developed through this project, publically accessible via URL http://symc.sdsu.edu/, enables rapid prototyping of CO{sub 2} injection scenarios and allows students without advanced knowledge of geochemistry to setup a typical sequestration scenario, invoke a simulation, analyze results, and then vary one or more problem parameters and quickly re-run a simulation to answer what-if questions.more » symc.sdsu.edu has 2x12 core AMD Opteron™ 6174 2.20GHz processors and 16GB RAM. The Web-based application was used to develop a new computational science course at San Diego State University, COMP 670: Numerical Simulation of CO{sub 2} Sequestration, which was taught during the fall semester of 2012. The purpose of the class was to introduce graduate students to Carbon Capture, Use and Storage (CCUS) through numerical modeling and simulation, and to teach students how to interpret simulation results to make predictions about long-term CO{sub 2} storage capacity in deep brine reservoirs. In addition to the training and education component of the project, significant software development efforts took place. Two computational science doctoral and one geological science masters student, under the direction of the PIs, extended the original code developed by Sienna Geodynamics, named Sym.8. New capabilities were added to Sym.8 to simulate non-isothermal and non-isobaric flows of charged aqueous solutes in porous media, in addition to incorporating HPC support into the code for execution on many-core XSEDE clusters. A successful outcome of this project was the funding and training of three new

  10. Transcriptomic Profiling of the Maize (Zea mays L.) Leaf Response to Abiotic Stresses at the Seedling Stage.

    PubMed

    Li, Pengcheng; Cao, Wei; Fang, Huimin; Xu, Shuhui; Yin, Shuangyi; Zhang, Yingying; Lin, Dezhou; Wang, Jianan; Chen, Yufei; Xu, Chenwu; Yang, Zefeng

    2017-01-01

    Abiotic stresses, including drought, salinity, heat, and cold, negatively affect maize ( Zea mays L.) development and productivity. To elucidate the molecular mechanisms of resistance to abiotic stresses in maize, RNA-seq was used for global transcriptome profiling of B73 seedling leaves exposed to drought, salinity, heat, and cold stress. A total of 5,330 differentially expressed genes (DEGs) were detected in differential comparisons between the control and each stressed sample, with 1,661, 2,019, 2,346, and 1,841 DEGs being identified in comparisons of the control with salinity, drought, heat, and cold stress, respectively. Functional annotations of DEGs suggested that the stress response was mediated by pathways involving hormone metabolism and signaling, transcription factors (TFs), very-long-chain fatty acid biosynthesis and lipid signaling, among others. Of the obtained DEGs (5,330), 167 genes are common to these four abiotic stresses, including 10 up-regulated TFs (five ERFs, two NACs, one ARF, one MYB, and one HD-ZIP) and two down-regulated TFs (one b-ZIP and one MYB-related), which suggested that common mechanisms may be initiated in response to different abiotic stresses in maize. This study contributes to a better understanding of the molecular mechanisms of maize leaf responses to abiotic stresses and could be useful for developing maize cultivars resistant to abiotic stresses.

  11. Polyamines and abiotic stress in plants: a complex relationship1

    PubMed Central

    Minocha, Rakesh; Majumdar, Rajtilak; Minocha, Subhash C.

    2014-01-01

    The physiological relationship between abiotic stress in plants and polyamines was reported more than 40 years ago. Ever since there has been a debate as to whether increased polyamines protect plants against abiotic stress (e.g., due to their ability to deal with oxidative radicals) or cause damage to them (perhaps due to hydrogen peroxide produced by their catabolism). The observation that cellular polyamines are typically elevated in plants under both short-term as well as long-term abiotic stress conditions is consistent with the possibility of their dual effects, i.e., being protectors from as well as perpetrators of stress damage to the cells. The observed increase in tolerance of plants to abiotic stress when their cellular contents are elevated by either exogenous treatment with polyamines or through genetic engineering with genes encoding polyamine biosynthetic enzymes is indicative of a protective role for them. However, through their catabolic production of hydrogen peroxide and acrolein, both strong oxidizers, they can potentially be the cause of cellular harm during stress. In fact, somewhat enigmatic but strong positive relationship between abiotic stress and foliar polyamines has been proposed as a potential biochemical marker of persistent environmental stress in forest trees in which phenotypic symptoms of stress are not yet visible. Such markers may help forewarn forest managers to undertake amelioration strategies before the appearance of visual symptoms of stress and damage at which stage it is often too late for implementing strategies for stress remediation and reversal of damage. This review provides a comprehensive and critical evaluation of the published literature on interactions between abiotic stress and polyamines in plants, and examines the experimental strategies used to understand the functional significance of this relationship with the aim of improving plant productivity, especially under conditions of abiotic stress. PMID:24847338

  12. Oxidation behaviour of ferritic stainless steel grade Crofer 22 APU at 700 °C in flowing Ar-75%CO2-12%H2O

    NASA Astrophysics Data System (ADS)

    Shariff, Nurul Atikah; Othman, Norinsan Kamil; Jalar, Azman

    2013-11-01

    The oxidation of Ferritic Stainless Steel (FSS) grade Crofer 22 APU has been investigated. FSS alloys were exposed to isothermal conditions in a horizontal tube furnace at a 700 °C in flowing Ar-75%CO2-12%H2O at a pressure of approximately 1 atm. The results showed that the growth of non protective Fe2O3 and spinel was observed after 50 h exposure in the presence of 12% H2O. The weight was increased significantly with time of exposure. The formation of different oxides is presented on the interface of the specimen such as MnCr2O4, Fe3O4 and Fe2O3 were revealed by X-ray diffraction and supported by EDAX analysis. FSS did not form a protective Cr2O3 layer due to water vapour accelerates the kinetics oxidation. Data of microstructure observation is presented and discussed in this paper in term of water vapour effects.

  13. [Removal of CO2 from simulated flue gas of power plants by membrane-based gas absorption processes].

    PubMed

    Yang, Ming-Fen; Fang, Meng-Xiang; Zhang, Wei-Feng; Wang, Shu-Yuan; Xu, Zhi-Kang; Luo, Zhong-Yang; Cen, Ke-Fa

    2005-07-01

    Three typical absorbents such as aqueous of aminoacetic acid potassium (AAAP), monoethanolamine (MEA) and methyldiethanolamine(MDEA) are selected to investigate the performance of CO2 separation from flue gas via membrane contactors made of hydrophobic hollow fiber polypropylene porous membrane. Impacts of absorbents, concentrations and flow rates of feeding gas and absorbent solution, cyclic loading of CO2 on the removal rate and the mass transfer velocity of CO2 are discussed. The results demonstrate that the mass transfer velocity was 7.1 mol x (m2 x s)(-1) for 1 mol x L(-1) MEA with flow rate of 0.1 m x s(-1) and flue gas with that of 0.211 m x s(-1). For 1 mol L(-1) AAAP with flow rate of 0.05 m x s(-1) and flue gas of 0.211 m x s(-1), CO2 removal rate (eta) was 93.2 % and eta was 98% for 4 mol x L(-1) AAAP under the same conditions. AAAP being absorbent, eta was higher than 90% in a wider range of concentrations of CO2. It indicates that membrane-based absorption process is a widely-applied and promising way of CO2 removal from flue gas of power plants, which not only appropriates for CO2 removal of flue gas of widely-used PF and NGCC, but also for that of flue gas of IGCC can be utilized widely in future.

  14. Abiotic regulation: a common way for proteins to modulate their functions.

    PubMed

    Zou, Zhi; Fu, Xinmiao

    2015-01-01

    Modulation of protein intrinsic activity in cells is generally carried out via a combination of four common ways, i.e., allosteric regulation, covalent modification, proteolytic cleavage and association of other regulatory proteins. Accumulated evidence indicate that changes of certain abiotic factors (e.g., temperature, pH, light and mechanical force) within or outside the cells directly influence protein structure and thus profoundly modulate the functions of a wide range of proteins, termed as abiotic regulatory proteins (e.g., heat shock factor, small heat shock protein, hemoglobin, zymogen, integrin, rhodopsin). Such abiotic regulation apparently differs from the four classic ways in perceiving and response to the signals. Importantly, it enables cells to directly and also immediately response to extracellular stimuli, thus facilitating the ability of organisms to resist against and adapt to the abiotic stress and thereby playing crucial roles in life evolution. Altogether, abiotic regulation may be considered as a common way for proteins to modulate their functions.

  15. Role of CO2 in the cerebral hyperemic response to incremental normoxic and hyperoxic exercise

    PubMed Central

    Wildfong, K. W.; Hoiland, R. L.; Harper, M.; Lewis, N. C.; Pool, A.; Smith, S. L.; Kuca, T.; Ainslie, P. N.

    2016-01-01

    Cerebral blood flow (CBF) is temporally related to exercise-induced changes in partial pressure of end-tidal carbon dioxide (PetCO2); hyperoxia is known to enhance this relationship. We examined the hypothesis that preventing PetCO2 from rising (isocapnia) during submaximal exercise with and without hyperoxia [end-tidal Po2 (PetO2) = 300 mmHg] would attenuate the increases in CBF. Additionally, we aimed to identify the magnitude that breathing, per se, influences the CBF response to normoxic and hyperoxic exercise. In 14 participants, CBF (intra- and extracranial) measurements were measured during exercise [20, 40, 60, and 80% of maximum workload (Wmax)] and during rest while ventilation (V̇e) was volitionally increased to mimic volumes achieved during exercise (isocapnic hyperpnea). While V̇e was uncontrolled during poikilocapnic exercise, during isocapnic exercise and isocapnic hyperpnea, V̇e was increased to prevent PetCO2 from rising above resting values (∼40 mmHg). Although PetCO2 differed by 2 ± 3 mmHg during normoxic poikilocapnic and isocapnic exercise, except for a greater poikilocapnic compared with isocapnic increase in blood velocity in the posterior cerebral artery at 60% Wmax, the between condition increases in intracranial (∼12-15%) and extracranial (15–20%) blood flow were similar at each workload. The poikilocapnic hyperoxic increases in both intra- and extracranial blood-flow (∼17–29%) were greater compared with poikilocapnic normoxia (∼8–20%) at intensities >40% Wmax (P < 0.01). During both normoxic and hyperoxic conditions, isocapnia normalized both the intracranial and extracranial blood-flow differences. Isocapnic hyperpnea did not alter CBF. Our findings demonstrate a differential effect of PetCO2 on CBF during exercise influenced by the prevailing PetO2. PMID:26769951

  16. Recent Molecular Advances on Downstream Plant Responses to Abiotic Stress

    PubMed Central

    dos Reis, Sávio Pinho; Lima, Aline Medeiros; de Souza, Cláudia Regina Batista

    2012-01-01

    Abiotic stresses such as extremes of temperature and pH, high salinity and drought, comprise some of the major factors causing extensive losses to crop production worldwide. Understanding how plants respond and adapt at cellular and molecular levels to continuous environmental changes is a pre-requisite for the generation of resistant or tolerant plants to abiotic stresses. In this review we aimed to present the recent advances on mechanisms of downstream plant responses to abiotic stresses and the use of stress-related genes in the development of genetically engineered crops. PMID:22942725

  17. Reducing energy-related CO2 emissions using accelerated weathering of limestone

    USGS Publications Warehouse

    Rau, Greg H.; Knauss, Kevin G.; Langer, William H.; Caldeira, Ken

    2007-01-01

    The use and impacts of accelerated weathering of limestone (AWL; reaction: CO2+H2O+CaCO3→Ca2++2(HCO3-) is explored as a CO2 capture and sequestration method. It is shown that significant limestone resources are relatively close to a majority of CO2-emitting power plants along the coastal US, a favored siting location for AWL. Waste fines, representing more than 20% of current US crushed limestone production (>109 tonnes/yr), could provide an inexpensive or free source of AWL carbonate. With limestone transportation then as the dominant cost variable, CO2 mitigation costs of $3-$4/tonne appear to be possible in certain locations. Perhaps 10–20% of US point–source CO2 emissions could be mitigated in this fashion. It is experimentally shown that CO2 sequestration rates of 10-6 to 10-5 moles/sec per m2 of limestone surface area are achievable, with reaction densities on the order of 10-2 tonnes CO2 m-3day-1, highly dependent on limestone particle size, solution turbulence and flow, and CO2 concentration. Modeling shows that AWL would allow carbon storage in the ocean with significantly reduced impacts to seawater pH relative to direct CO2 disposal into the atmosphere or sea. The addition of AWL-derived alkalinity to the ocean may itself be beneficial for marine biota.

  18. Slow plastic strain rate compressive flow in binary CoAl intermetallics

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. D.

    1985-01-01

    Constant-velocity elevated temperature compression tests have been conducted on a series of binary CoAl intermetallics produced by hot extrusion of blended prealloyed powders. The as-extruded materials were polycrystalline, and they retained their nominal 10-micron grain size after being tested between 1100 and 1400 K at strain rates ranging from 2 x 10 to the -4th to 2 x 10 to the -7th per sec. Significant plastic flow was obtained in all cases; while cracking was observed, much of this could be due to failure at matrix-oxide interfaces along extrusion stringers rather than to solely intergranular fracture. A maximum in flow strength occurs at an aluminum-to-cobalt ratio of 0.975, and the stress exponent appears to be constant for aluminum-to-cobalt ratios of 0.85 or more. It is likely that very aluminum-deficient materials deform by a different mechanism than do other compositions.

  19. A 2.5-kW industrial CO2 laser

    NASA Astrophysics Data System (ADS)

    Golov, V. K.; Ivanchenko, A. I.; Krasheninnikov, V. V.; Ponomarenko, A. G.; Shepelenko, A. A.

    1986-06-01

    A fast-flow laser is reported in which the active medium is excited by a self-sustained dc discharge produced by an electric-discharge device with nonsectioned electrodes. In the laser, two discharge gaps are formed by a flat anode and two cathodes, one on each side of the anode. A gas mixture is driven through the gasdynamic channel by a centrifugal fan rotating at 6000 rpm/min. With a mixture of CO2:N2:He = 2.5:7.5:5 mm Hg, the rated power is 2.5 kW; the maximum power is 4 kW with the mixture 2.5:7.5:10 mm Hg. The general design of the laser is described, and its principal performance characteristics are given.

  20. Low pCO2 Air-Polarized CO2 Concentrator Development

    NASA Technical Reports Server (NTRS)

    Schubert, Franz H.

    1997-01-01

    Life Systems completed a Ground-based Space Station Experiment Development Study Program which verifies through testing the performance and applicability of the electrochemical Air-Polarized Carbon Dioxide Concentrator (APC) process technology for space missions requiring low (i.e., less than 3 mm Hg) CO2 partial pressure (pCO2) in the cabin atmosphere. Required test hardware was developed and testing was accomplished at an approximate one-person capacity CO2 removal level. Initially, two five-cell electrochemical modules using flight-like 0.5 sq ft cell hardware were tested individually, following by their testing at the integrated APC system level. Testing verified previously projected performance and established a database for sizing of APC systems. A four person capacity APC system was sized and compared with four candidate CO2 removal systems. At its weight of 252 lb, a volume of 7 cu ft and a power consumption of 566 W while operating at 2.2 mm Hg pCO2, the APC was surpassed only by an Electrochemical Depolarized CO2 Concentrator (EDC) (operating with H2), when compared on a total equivalent basis.

  1. Transition Delay in a Hypervelocity Boundary Layer using Nonequilibrium CO2 Injection

    DTIC Science & Technology

    2008-10-28

    flows than for either air or N2 flows. The explanation for this phenomenon lies in the fact that when CO2 is in vibrational and chemical ... chemical non-equilibrium, these relax- ation processes absorb energy from acoustic disturbances whose growth is responsible for transition in high...atmosphere at hypersonic speeds, they must somehow provide for, avoid, or otherwise accommodate the enormous heat-transfer rates to the vehicle engen

  2. Wheat EST resources for functional genomics of abiotic stress

    PubMed Central

    Houde, Mario; Belcaid, Mahdi; Ouellet, François; Danyluk, Jean; Monroy, Antonio F; Dryanova, Ani; Gulick, Patrick; Bergeron, Anne; Laroche, André; Links, Matthew G; MacCarthy, Luke; Crosby, William L; Sarhan, Fathey

    2006-01-01

    Background Wheat is an excellent species to study freezing tolerance and other abiotic stresses. However, the sequence of the wheat genome has not been completely characterized due to its complexity and large size. To circumvent this obstacle and identify genes involved in cold acclimation and associated stresses, a large scale EST sequencing approach was undertaken by the Functional Genomics of Abiotic Stress (FGAS) project. Results We generated 73,521 quality-filtered ESTs from eleven cDNA libraries constructed from wheat plants exposed to various abiotic stresses and at different developmental stages. In addition, 196,041 ESTs for which tracefiles were available from the National Science Foundation wheat EST sequencing program and DuPont were also quality-filtered and used in the analysis. Clustering of the combined ESTs with d2_cluster and TGICL yielded a few large clusters containing several thousand ESTs that were refractory to routine clustering techniques. To resolve this problem, the sequence proximity and "bridges" were identified by an e-value distance graph to manually break clusters into smaller groups. Assembly of the resolved ESTs generated a 75,488 unique sequence set (31,580 contigs and 43,908 singletons/singlets). Digital expression analyses indicated that the FGAS dataset is enriched in stress-regulated genes compared to the other public datasets. Over 43% of the unique sequence set was annotated and classified into functional categories according to Gene Ontology. Conclusion We have annotated 29,556 different sequences, an almost 5-fold increase in annotated sequences compared to the available wheat public databases. Digital expression analysis combined with gene annotation helped in the identification of several pathways associated with abiotic stress. The genomic resources and knowledge developed by this project will contribute to a better understanding of the different mechanisms that govern stress tolerance in wheat and other cereals. PMID

  3. Predicting possible effects of H2S impurity on CO2 transportation and geological storage.

    PubMed

    Ji, Xiaoyan; Zhu, Chen

    2013-01-02

    For CO(2) geological storage, permitting impurities, such as H(2)S, in CO(2) streams can lead to a great potential for capital and energy savings for CO(2) capture and separation, but it also increases costs and risk management for transportation and storage. To evaluate the cost-benefits, using a recently developed model (Ji, X.; Zhu, C. Geochim. Cosmochim. Acta 2012, 91, 40-59), this study predicts phase equilibria and thermodynamic properties of the system H(2)S-CO(2)-H(2)O-NaCl under transportation and storage conditions and discusses potential effects of H(2)S on transportation and storage. The prediction shows that inclusion of H(2)S in CO(2) streams may lead to two-phase flow. For H(2)S-CO(2) mixtures, at a given temperature, the bubble and dew pressures decrease with increasing H(2)S content, while the mass density increases at low pressures and decreases at high pressures. For the CO(2)-H(2)S-H(2)O system, the total gas solubility increases while the mass density of the aqueous solution with dissolved gas decreases. For the CO(2)-H(2)S-H(2)O-NaCl system, at a given temperature, pressure and NaCl concentration, the solubility of the gas mixture in aqueous phase increases with increasing H(2)S content and then decreases, while the mass density of aqueous solution decreases and may be lower than the mass density of the solution without gas dissolution.

  4. Application of Notched Long-Period Fiber Grating Based Sensor for CO2 Gas Sensing

    NASA Astrophysics Data System (ADS)

    Wu, Chao-Wei; Chiang, Chia-Chin

    2016-01-01

    An inductively coupled plasma etching process to fabricate notched long-period fiber gratings for CO2 gas sensing is proposed in this article. In the gas sensing test, the 15% mixed CO2 gas was used for characterization of CO2 adsorption by the amine-modified nanoporous silica foams of the notched long-period fiber grating sensor. The results shows the spectra were changed with the CO2 gas flow within 13 min. During the absorption process, the transmission of the resonant dip was decreased by 2.884 dB. Therefore, the proposed notched long-period fiber grating gas sensor shows good performance and is suitable as a gas sensor for monitoring the CO2 adsorption process.

  5. Stability of Buoyancy-Driven Gas Flow: Visualization of Coherent and Incoherent Gas Flow Patterns and Capillary Trapping

    NASA Astrophysics Data System (ADS)

    Geistlinger, H. W.; Samani, S.; Pohlert, M.; Jia, R.; Lazik, D.

    2009-12-01

    There are several mechanisms by which the CO2 can be stored: (1) In hydrodynamic trapping, the buoyant CO2 remains as a mobile fluid but is prevented from flowing back to the surface by an impermeable cap rock. (2) In solution trapping, CO2 dissolves into the brine, possibly enhanced by gravity instabilities due to the larger density of the brine-CO2 liquid mixture. (3) In mineral trapping, geochemical binding to the rock due to mineral precipitation. (4) In capillary trapping, the CO2 phase is disconnected into a coherent, mobile phase and an incoherent, immobile (trapped) phase. Recent analytical and numerical investigations [Juanes et al., 2006, 2009; Hesse et al., 2007 ] of buoyant-driven CO2-plume along a sloped aquifer are based on the following conceptual process model: (1) During the injection period, the less wetting CO2 displaces the more wetting brine in a drainage-like process. It is assumed that no capillary trapping occurs and that the CO2-network is coherent and driven both by the injection pressure and the buoyant pressure. Because of this coherence assumption a generalized Darcy-law can be used for the dynamics of the mobile, gaseous CO2-phase. (2) After injection the buoyant CO2 migrates laterally and upward, and water displaces CO2 at the trailing edge of the plume in an imbibition-like process. During this process, there are several physical mechanisms by which the water can displace the CO2 [Lenormand et al., 1983]. In addition to piston-type displacement, core-annular flow (also called: cooperative pore-body filling) may occur, i.e. the wetting phase moves along the walls and under certain conditions the CO2-core flow becomes unstable (snap-off). For water wet rocks, snap-off is the dominant mechanism [Al-Futaisi and Patzek, 2003; Valvatne and Blunt, 2004]. There seems to be consensus that the capillary trapping mechanism has a huge impact on the migration and distribution of CO2 which, in turn, affects the effectiveness of the other

  6. On the causal structure between CO2 and global temperature

    PubMed Central

    Stips, Adolf; Macias, Diego; Coughlan, Clare; Garcia-Gorriz, Elisa; Liang, X. San

    2016-01-01

    We use a newly developed technique that is based on the information flow concept to investigate the causal structure between the global radiative forcing and the annual global mean surface temperature anomalies (GMTA) since 1850. Our study unambiguously shows one-way causality between the total Greenhouse Gases and GMTA. Specifically, it is confirmed that the former, especially CO2, are the main causal drivers of the recent warming. A significant but smaller information flow comes from aerosol direct and indirect forcing, and on short time periods, volcanic forcings. In contrast the causality contribution from natural forcings (solar irradiance and volcanic forcing) to the long term trend is not significant. The spatial explicit analysis reveals that the anthropogenic forcing fingerprint is significantly regionally varying in both hemispheres. On paleoclimate time scales, however, the cause-effect direction is reversed: temperature changes cause subsequent CO2/CH4 changes. PMID:26900086

  7. Effective Wettability Measurements of CO2-Brine-Sandstone System at Different Reservoir Conditions

    NASA Astrophysics Data System (ADS)

    Al-Menhali, Ali; Krevor, Samuel

    2014-05-01

    The wetting properties of CO2-brine-rock systems will have a major impact on the management of CO2 injection processes. The wettability of a system controls the flow and trapping efficiency during the storage of CO2 in geological formations as well as the efficiency of enhanced oil recovery operations. Despite its utility in EOR and the continued development of CCS, little is currently known about the wetting properties of the CO2-brine system on reservoir rocks, and no investigations have been performed assessing the impact of these properties on CO2 flooding for CO2 storage or EOR. The wetting properties of multiphase fluid systems in porous media have major impacts on the multiphase flow properties such as the capillary pressure and relative permeability. While recent studies have shown CO2 to generally act as a non-wetting phase in siliciclastic rocks, some observations report that the contact angle varies with pressure, temperature and water salinity. Additionally, there is a wide range of reported contact angles for this system, from strongly to weakly water-wet. In the case of some minerals, intermediate wet contact angles have been observed. Uncertainty with regard to the wetting properties of CO2-brine systems is currently one of the remaining major unresolved issues with regards to reservoir management of CO2 storage. In this study, we make semi-dynamic capillary pressure measurements of supercritical CO2 and brine at reservoir conditions to observe shifts in the wetting properties. We utilize a novel core analysis technique recently developed by Pini et al in 2012 to evaluate a core-scale effective contact angle. Carbon dioxide is injected at constant flow rate into a core that is initially fully saturated with water, while maintaining a constant outlet pressure. In this scenario, the pressure drop across the core corresponds to the capillary pressure at the inlet face of the core. When compared with mercury intrusion capillary pressure measurements

  8. Abiotic synthesis of organic compounds from carbon disulfide under hydrothermal conditions.

    PubMed

    Rushdi, Ahmed I; Simoneit, Bernd R T

    2005-12-01

    Abiotic formation of organic compounds under hydrothermal conditions is of interest to bio, geo-, and cosmochemists. Oceanic sulfur-rich hydrothermal systems have been proposed as settings for the abiotic synthesis of organic compounds. Carbon disulfide is a common component of magmatic and hot spring gases, and is present in marine and terrestrial hydrothermal systems. Thus, its reactivity should be considered as another carbon source in addition to carbon dioxide in reductive aqueous thermosynthesis. We have examined the formation of organic compounds in aqueous solutions of carbon disulfide and oxalic acid at 175 degrees C for 5 and 72 h. The synthesis products from carbon disulfide in acidic aqueous solutions yielded a series of organic sulfur compounds. The major compounds after 5 h of reaction included dimethyl polysulfides (54.5%), methyl perthioacetate (27.6%), dimethyl trithiocarbonate (6.8%), trithianes (2.7%), hexathiepane (1.4%), trithiolanes (0.8%), and trithiacycloheptanes (0.3%). The main compounds after 72 h of reaction consisted of trithiacycloheptanes (39.4%), pentathiepane (11.6%), tetrathiocyclooctanes (11.5%), trithiolanes (10.6%), tetrathianes (4.4%), trithianes (1.2%), dimethyl trisulfide (1.1%), and numerous minor compounds. It is concluded that the abiotic formation of aliphatic straight-chain and cyclic polysulfides is possible under hydrothermal conditions and warrants further studies.

  9. Microbial Electrolytic Capture, Separation and Regeneration of CO2 for Biogas Upgrading.

    PubMed

    Jin, Xiangdan; Zhang, Yifeng; Li, Xiaohu; Zhao, Nannan; Angelidaki, Irini

    2017-08-15

    Biogas upgrading to natural gas quality is essential for the efficient use of biogas in various applications. Carbon dioxide (CO 2 ) which constitutes a major part of the biogas is generally removed by physicochemical methods. However, most of the methods are expensive and often present environmental challenges. In this study, an innovative microbial electrolytic system was developed to capture, separate and regenerate CO 2 for biogas upgrading without external supply of chemicals, and potentially to treat wastewater. The new system was operated at varied biogas flow rates and external applied voltages. CO 2 was effectively separated from the raw biogas and the CH 4 content in the outlet reached as high as 97.0 ± 0.2% at the external voltage of 1.2 V and gas flow rate of 19.6 mL/h. Regeneration of CO 2 was also achieved in the regeneration chamber with low pH (1.34 ± 0.04). The relatively low electric energy consumption (≤0.15 kWh/m 3 biogas) along with the H 2 production which can contribute to the energy input makes the overall energy need of the system low, and thereby makes the technology promising. This work provides the first attempt for development of a sustainable biogas upgrading technology and potentially expands the application of microbial electrochemical technologies.

  10. Bioelectrochemical conversion of CO2 to chemicals: CO2 as a next generation feedstock for electricity-driven bioproduction in batch and continuous modes.

    PubMed

    Bajracharya, Suman; Vanbroekhoven, Karolien; Buisman, Cees J N; Strik, David P B T B; Pant, Deepak

    2017-09-21

    The recent concept of microbial electrosynthesis (MES) has evolved as an electricity-driven production technology for chemicals from low-value carbon dioxide (CO 2 ) using micro-organisms as biocatalysts. MES from CO 2 comprises bioelectrochemical reduction of CO 2 to multi-carbon organic compounds using the reducing equivalents produced at the electrically-polarized cathode. The use of CO 2 as a feedstock for chemicals is gaining much attention, since CO 2 is abundantly available and its use is independent of the food supply chain. MES based on CO 2 reduction produces acetate as a primary product. In order to elucidate the performance of the bioelectrochemical CO 2 reduction process using different operation modes (batch vs. continuous), an investigation was carried out using a MES system with a flow-through biocathode supplied with 20 : 80 (v/v) or 80 : 20 (v/v) CO 2  : N 2 gas. The highest acetate production rate of 149 mg L -1 d -1 was observed with a 3.1 V applied cell-voltage under batch mode. While running in continuous mode, high acetate production was achieved with a maximum rate of 100 mg L -1 d -1 . In the continuous mode, the acetate production was not sustained over long-term operation, likely due to insufficient microbial biocatalyst retention within the biocathode compartment (i.e. suspended micro-organisms were washed out of the system). Restarting batch mode operations resulted in a renewed production of acetate. This showed an apparent domination of suspended biocatalysts over the attached (biofilm forming) biocatalysts. Long term CO 2 reduction at the biocathode resulted in the accumulation of acetate, and more reduced compounds like ethanol and butyrate were also formed. Improvements in the production rate and different biomass retention strategies (e.g. selecting for biofilm forming micro-organisms) should be investigated to enable continuous biochemical production from CO 2 using MES. Certainly, other process optimizations will be

  11. [Studies on technology of supercritical-CO2 fluid extraction for volatile oils and saikosaponins in Bupleurum chinense DC].

    PubMed

    Ge, F H; Li, Y; Xie, J M; Li, Q; Ma, G J; Chen, Y H; Lin, Y C; Li, X F

    2000-03-01

    To study the technology of supercritical-CO2 fluid extraction (SFE-CO2) for the volatile oils and saikosaponins in Bupleurum chinense. Exploring the effects of pressure, temperature, extraction time, flow rate of CO2 and entrainers on the yield of the oils and saikosaponin-contained extracts; determining the optimum conditions for SFE-CO2; analyzing the oils by GC/MS and comparing the technology of SFE-CO2 with that of traditional steam distillation. The optimum extraction conditions turned out to be--for volatile oils: pressure (EP) = 20 MPa, temperature (ET) = 30 degrees C, isolator I pressure (1P-I) = 12 MPa, temperature(1T-I) = 65 degrees C, isolator II pressure (1P-II) = 6 MPa, temperature (1T-II) = 40 degrees C, extraction time = 4 hours, and CO2 flow rate = 10-20 kg.(h.kg)-1 crude drug; for saikosaponins: EP = 30 MPa, ET = 65 degrees C, 1P I = 12 MPa, 1T I = 55 degrees C, 1P II = 6 MPa, 1T II = 43 degrees C, extraction time = 3 hours, entrainer = 60% ethanol, and CO2 flow rate = 20-25 kg.(h.kg)-1 crude drug. SFE-CO2 excels the traditional steam distillation in raising yield and reducing extraction time. The oils are composed of 22 constituents including caproaldehyde, and the saikosaponins can only be extracted with the help of entrainers under higher pressure and temperature.

  12. Systematic biology analysis on photosynthetic carbon metabolism of maize leaf following sudden heat shock under elevated CO2.

    PubMed

    Qu, Mingnan; Chen, Genyun; Bunce, James A; Zhu, Xiaocen; Sicher, Richard C

    2018-05-18

    Plants would experience more complex environments, such as sudden heat shock (SHS) stress combined with elevated CO 2 in the future, and might adapt to this stressful condition by optimizing photosynthetic carbon metabolism (PCM). It is interesting to understand whether this acclimation process would be altered in different genotypes of maize under elevated CO 2 , and which metabolites represent key indicators reflecting the photosynthetic rates (P N ) following SHS. Although B76 had greater reduction in P N during SHS treatment, our results indicated that P N in genotype B76, displayed faster recovery after SHS treatment under elevated CO 2 than in genotype B106. Furthermore, we employed a stepwise feature extraction approach by partial linear regression model. Our findings demonstrated that 9 key metabolites over the total (35 metabolites) can largely explain the variance of P N during recovery from SHS across two maize genotypes and two CO 2 grown conditions. Of these key metabolites, malate, valine, isoleucine, glucose and starch are positively correlated with recovery pattern of P N . Malate metabolites responses to SHS were further discussed by incorporating with the activities and gene expression of three C 4 photosynthesis-related key enzymes. We highlighted the importance of malate metabolism during photosynthesis recovery from short-term SHS, and data integration analysis to better comprehend the regulatory framework of PCM in response to abiotic stress.

  13. Electrokinetic instability in microchannel ferrofluid/water co-flows

    PubMed Central

    Song, Le; Yu, Liandong; Zhou, Yilong; Antao, Asher Reginald; Prabhakaran, Rama Aravind; Xuan, Xiangchun

    2017-01-01

    Electrokinetic instability refers to unstable electric field-driven disturbance to fluid flows, which can be harnessed to promote mixing for various electrokinetic microfluidic applications. This work presents a combined numerical and experimental study of electrokinetic ferrofluid/water co-flows in microchannels of various depths. Instability waves are observed at the ferrofluid and water interface when the applied DC electric field is beyond a threshold value. They are generated by the electric body force that acts on the free charge induced by the mismatch of ferrofluid and water electric conductivities. A nonlinear depth-averaged numerical model is developed to understand and simulate the interfacial electrokinetic behaviors. It considers the top and bottom channel walls’ stabilizing effects on electrokinetic flow through the depth averaging of three-dimensional transport equations in a second-order asymptotic analysis. This model is found accurate to predict both the observed electrokinetic instability patterns and the measured threshold electric fields for ferrofluids of different concentrations in shallow microchannels. PMID:28406228

  14. CO2 conversion in non-thermal plasma and plasma/g-C3N4 catalyst hybrid processes

    NASA Astrophysics Data System (ADS)

    Lu, Na; Sun, Danfeng; Zhang, Chuke; Jiang, Nan; Shang, Kefeng; Bao, Xiaoding; Li, Jie; Wu, Yan

    2018-03-01

    Carbon dioxide conversion at atmosphere pressure and low temperature has been studied in a cylindrical dielectric barrier discharge (DBD) reactor. Pure CO2 feed flows to the discharge zone and typical filamentary discharges were obtained in each half-cycle of the applied voltage. The gas temperature increased with discharge time and discharge power, which was found to affect the CO2 decomposition deeply. As the DBD reactor was cooled to ambient temperature, both the conversion of CO2 and the CO yield were enhanced. Especially the energy efficiencies changed slightly with the increase of discharge power and were much higher in cooling condition comparing to those without cooling. At a discharge power of 40 W, the energy efficiency under cooling condition was approximately six times more than that without cooling. Gas flow rate was observed to affect CO2 conversion and 0.1 L min-1 was obtained as optimum gas flow rate under cooling condition. In addition, the CO2 conversion rate in plasma/g-C3N4 catalyst hybrid system was twice times as that in plasma-alone system. In case of cooling, the existence of g-C3N4 catalyst contributed to a 47% increase of CO2 conversion compared to the sole plasma process. The maximum energy-efficiency with g-C3N4 was 0.26 mmol kJ-1 at 20 W, which increased by 157% compared to that without g-C3N4. The synergistic effect of DBD plasma with g-C3N4 on pure CO2 conversion was verified.

  15. Predictive modelling of Ketzin - CO2 arrival in the observation well

    NASA Astrophysics Data System (ADS)

    Kühn, M.; Class, H.; Frykman, P.; Kopp, A.; Nielsen, C. M.; Probst, P.

    2009-04-01

    The design of the Ketzin CO2 storage site allows testing of different modelling approaches, ranging from analytical approaches to finite element modelling. As three wells are drilled in an L-shape configuration, 3D geophysical observations (electrical resistivity, seismic imaging - for details see further presentations at EGU2009) allow to determine the 4D evolvement of the CO2 plume within the reservoir. Further information is available through smart casing technologies (DTS, ERT), conventional fluid, and permanent gas sampling. As input parameters for the models, a high resolution 3D seismic as well as detailed analysed core samples from all three wells at Ketzin were available. Logging data and laboratory experiments on rock samples act as further boundary conditions for the geological model. Hydraulic testing of all three wells gave further information about the complex hydraulic situation of the highly heterogeneous reservoir. Before CO2 injection started at the Ketzin site on the 30th of June 2008 any member of the CO2SINK project was asked to place a bet in a competition and predict when the CO2 arrival in the observation well - 50 m away from the injection site - is to be expected. This allows for a double blind study, the approval of different modelling strategies, and to improve modelling tools and strategies. The discussed estimates are based on three different numerical models. Eclipse100, Eclipse300 (CO2STORE) and MUFTE-UG were applied for predictive modelling. The geological models are based on all available geophysical and geological information. We present the results of this modelling exercise and discuss the differences of all the models and assess the capability of numerical simulation to estimate processes occurring during CO2 storage. The role of grid size on the precision of the modelled two phase fluid flow in a layered reservoir is demonstrated, as a high resolution model of the two phase flow explains the observed arrival of the CO2 very

  16. Chemical Method to Improve CO{sub 2} Flooding Sweep Efficiency for Oil Recovery Using SPI-CO{sub 2} Gels

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

    Burns, Lyle D.

    2009-04-14

    The problem in CO{sub 2} flooding lies with its higher mobility causing low conformance or sweep efficiency. This is an issue in oilfield applications where an injected fluid or gas used to mobilize and produce the oil in a marginal field has substantially higher mobility (function of viscosity and density and relative permeability) relative to the crude oil promoting fingering and early breakthrough. Conformance is particularly critical in CO{sub 2} oilfield floods where the end result is less oil recovered and substantially higher costs related to the CO{sub 2}. The SPI-CO{sub 2} (here after called “SPI”) gel system is amore » unique silicate based gel system that offers a technically effective solution to the conformance problem with CO{sub 2} floods. This SPI gel system remains a low viscosity fluid until an external initiator (CO{sub 2}) triggers gelation. This is a clear improvement over current technologies where the gels set up as a function of time, regardless of where it is placed in the reservoir. In those current systems, the internal initiator is included in the injected fluid for water shut off applications. In this new research effort, the CO{sub 2} is an external initiator contacted after SPI gel solution placement. This concept ensures in the proper water wet reservoir environment that the SPI gel sets up in the precise high permeability path followed by the CO{sub 2}, therefore improving sweep efficiency to a greater degree than conventional systems. In addition, the final SPI product in commercial quantities is expected to be low cost over the competing systems. This Phase I research effort provided “proof of concept” that SPI gels possess strength and may be formed in a sand pack reducing the permeability to brine and CO{sub 2} flow. This SPI technology is a natural extension of prior R & D and the Phase I effort that together show a high potential for success in a Phase II follow-on project. Carbon dioxide (CO{sub 2}) is a major by

  17. Interactive effects of MnO2, organic matter and pH on abiotic formation of N2O from hydroxylamine in artificial soil mixtures.

    PubMed

    Liu, Shurong; Berns, Anne E; Vereecken, Harry; Wu, Di; Brüggemann, Nicolas

    2017-02-01

    Abiotic conversion of the reactive nitrification intermediate hydroxylamine (NH 2 OH) to nitrous oxide (N 2 O) is a possible mechanism of N 2 O formation during nitrification. Previous research has demonstrated that manganese dioxide (MnO 2 ) and organic matter (OM) content of soil as well as soil pH are important control variables of N 2 O formation in the soil. But until now, their combined effect on abiotic N 2 O formation from NH 2 OH has not been quantified. Here, we present results from a full-factorial experiment with artificial soil mixtures at five different levels of pH, MnO 2 and OM, respectively, and quantified the interactive effects of the three variables on the NH 2 OH-to-N 2 O conversion ratio (R NH2OH-to-N2O ). Furthermore, the effect of OM quality on R NH2OH-to-N2O was determined by the addition of four different organic materials with different C/N ratios to the artificial soil mixtures. The experiments revealed a strong interactive effect of soil pH, MnO 2 and OM on R NH2OH-to-N2O . In general, increasing MnO 2 and decreasing pH increased R NH2OH-to-N2O , while increasing OM content was associated with a decrease in R NH2OH-to-N2O . Organic matter quality also affected R NH2OH-to-N2O . However, this effect was not a function of C/N ratio, but was rather related to differences in the dominating functional groups between the different organic materials.

  18. Interactive effects of MnO2, organic matter and pH on abiotic formation of N2O from hydroxylamine in artificial soil mixtures

    NASA Astrophysics Data System (ADS)

    Liu, Shurong; Berns, Anne E.; Vereecken, Harry; Wu, Di; Brüggemann, Nicolas

    2017-02-01

    Abiotic conversion of the reactive nitrification intermediate hydroxylamine (NH2OH) to nitrous oxide (N2O) is a possible mechanism of N2O formation during nitrification. Previous research has demonstrated that manganese dioxide (MnO2) and organic matter (OM) content of soil as well as soil pH are important control variables of N2O formation in the soil. But until now, their combined effect on abiotic N2O formation from NH2OH has not been quantified. Here, we present results from a full-factorial experiment with artificial soil mixtures at five different levels of pH, MnO2 and OM, respectively, and quantified the interactive effects of the three variables on the NH2OH-to-N2O conversion ratio (RNH2OH-to-N2O). Furthermore, the effect of OM quality on RNH2OH-to-N2O was determined by the addition of four different organic materials with different C/N ratios to the artificial soil mixtures. The experiments revealed a strong interactive effect of soil pH, MnO2 and OM on RNH2OH-to-N2O. In general, increasing MnO2 and decreasing pH increased RNH2OH-to-N2O, while increasing OM content was associated with a decrease in RNH2OH-to-N2O. Organic matter quality also affected RNH2OH-to-N2O. However, this effect was not a function of C/N ratio, but was rather related to differences in the dominating functional groups between the different organic materials.

  19. Flow Cytometry Sorting to Separate Viable Giant Viruses from Amoeba Co-culture Supernatants

    PubMed Central

    Khalil, Jacques Y. B.; Langlois, Thierry; Andreani, Julien; Sorraing, Jean-Marc; Raoult, Didier; Camoin, Laurence; La Scola, Bernard

    2017-01-01

    Flow cytometry has contributed to virology but has faced many drawbacks concerning detection limits, due to the small size of viral particles. Nonetheless, giant viruses changed many concepts in the world of viruses, as a result of their size and hence opened up the possibility of using flow cytometry to study them. Recently, we developed a high throughput isolation of viruses using flow cytometry and protozoa co-culture. Consequently, isolating a viral mixture in the same sample became more common. Nevertheless, when one virus multiplies faster than others in the mixture, it is impossible to obtain a pure culture of the minority population. Here, we describe a robust sorting system, which can separate viable giant virus mixtures from supernatants. We tested three flow cytometry sorters by sorting artificial mixtures. Purity control was assessed by electron microscopy and molecular biology. As proof of concept, we applied the sorting system to a co-culture supernatant taken from a sample containing a viral mixture that we couldn't separate using end point dilution. In addition to isolating the quick-growing Mimivirus, we sorted and re-cultured a new, slow-growing virus, which we named “Cedratvirus.” The sorting assay presented in this paper is a powerful and versatile tool for separating viral populations from amoeba co-cultures and adding value to the new field of flow virometry. PMID:28111619

  20. Flow Cytometry Sorting to Separate Viable Giant Viruses from Amoeba Co-culture Supernatants.

    PubMed

    Khalil, Jacques Y B; Langlois, Thierry; Andreani, Julien; Sorraing, Jean-Marc; Raoult, Didier; Camoin, Laurence; La Scola, Bernard

    2016-01-01

    Flow cytometry has contributed to virology but has faced many drawbacks concerning detection limits, due to the small size of viral particles. Nonetheless, giant viruses changed many concepts in the world of viruses, as a result of their size and hence opened up the possibility of using flow cytometry to study them. Recently, we developed a high throughput isolation of viruses using flow cytometry and protozoa co-culture. Consequently, isolating a viral mixture in the same sample became more common. Nevertheless, when one virus multiplies faster than others in the mixture, it is impossible to obtain a pure culture of the minority population. Here, we describe a robust sorting system, which can separate viable giant virus mixtures from supernatants. We tested three flow cytometry sorters by sorting artificial mixtures. Purity control was assessed by electron microscopy and molecular biology. As proof of concept, we applied the sorting system to a co-culture supernatant taken from a sample containing a viral mixture that we couldn't separate using end point dilution. In addition to isolating the quick-growing Mimivirus , we sorted and re-cultured a new, slow-growing virus, which we named "Cedratvirus." The sorting assay presented in this paper is a powerful and versatile tool for separating viral populations from amoeba co-cultures and adding value to the new field of flow virometry.