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Sample records for natural co2 gradient

  1. Decline in coccolithophore diversity and impact on coccolith morphogenesis along a natural CO2 gradient.

    PubMed

    Ziveri, Patrizia; Passaro, Marcello; Incarbona, Alessandro; Milazzo, Marco; Rodolfo-Metalpa, Riccardo; Hall-Spencer, Jason M

    2014-06-01

    A natural pH gradient caused by marine CO2 seeps off Vulcano Island (Italy) was used to assess the effects of ocean acidification on coccolithophores, which are abundant planktonic unicellular calcifiers. Such seeps are used as natural laboratories to study the effects of ocean acidification on marine ecosystems, since they cause long-term changes in seawater carbonate chemistry and pH, exposing the organisms to elevated CO2 concentrations and therefore mimicking future scenarios. Previous work at CO2 seeps has focused exclusively on benthic organisms. Here we show progressive depletion of 27 coccolithophore species, in terms of cell concentrations and diversity, along a calcite saturation gradient from Ωcalcite 6.4 to <1. Water collected close to the main CO2 seeps had the highest concentrations of malformed Emiliania huxleyi. These observations add to a growing body of evidence that ocean acidification may benefit some algae but will likely cause marine biodiversity loss, especially by impacting calcifying species, which are affected as carbonate saturation falls.

  2. Changes in microbial communities in coastal sediments along natural CO2 gradients at a volcanic vent in Papua New Guinea.

    PubMed

    Raulf, Felix F; Fabricius, Katharina; Uthicke, Sven; de Beer, Dirk; Abed, Raeid M M; Ramette, Alban

    2015-10-01

    Natural CO2 venting systems can mimic conditions that resemble intermediate to high pCO2 levels as predicted for our future oceans. They represent ideal sites to investigate potential long-term effects of ocean acidification on marine life. To test whether microbes are affected by prolonged exposure to pCO2 levels, we examined the composition and diversity of microbial communities in oxic sandy sediments along a natural CO2 gradient. Increasing pCO2 was accompanied by higher bacterial richness and by a strong increase in rare members in both bacterial and archaeal communities. Microbial communities from sites with CO2 concentrations close to today's conditions had different structures than those of sites with elevated CO2 levels. We also observed increasing sequence abundance of several organic matter degrading types of Flavobacteriaceae and Rhodobacteraceae, which paralleled concurrent shifts in benthic cover and enhanced primary productivity. With increasing pCO2 , sequences related to bacterial nitrifying organisms such as Nitrosococcus and Nitrospirales decreased, and sequences affiliated to the archaeal ammonia-oxidizing Thaumarchaeota Nitrosopumilus maritimus increased. Our study suggests that microbial community structure and diversity, and likely key ecosystem functions, may be altered in coastal sediments by long-term CO2 exposure to levels predicted for the end of the century.

  3. Effects of ocean acidification on embryonic respiration and development of a temperate wrasse living along a natural CO2 gradient

    PubMed Central

    Cattano, Carlo; Giomi, Folco; Milazzo, Marco

    2016-01-01

    Volcanic CO2 seeps provide opportunities to investigate the effects of ocean acidification on organisms in the wild. To understand the influence of increasing CO2 concentrations on the metabolic rate (oxygen consumption) and the development of ocellated wrasse early life stages, we ran two field experiments, collecting embryos from nesting sites with different partial pressures of CO2 [pCO2; ambient (∼400 µatm) and high (800–1000 µatm)] and reciprocally transplanting embryos from ambient- to high-CO2 sites for 30 h. Ocellated wrasse offspring brooded in different CO2 conditions had similar responses, but after transplanting portions of nests to the high-CO2 site, embryos from parents that spawned in ambient conditions had higher metabolic rates. Although metabolic phenotypic plasticity may show a positive response to high CO2, it often comes at a cost, in this case as a smaller size at hatching. This can have adverse effects because smaller larvae often exhibit a lower survival in the wild. However, the adverse effects of increased CO2 on metabolism and development did not occur when embryos from the high-CO2 nesting site were exposed to ambient conditions, suggesting that offspring from the high-CO2 nesting site could be resilient to a wider range of pCO2 values than those belonging to the site with present-day pCO2 levels. Our study identifies a crucial need to increase the number of studies dealing with these processes under global change trajectories and to expand these to naturally high-CO2 environments, in order to assess further the adaptive plasticity mechanism that encompasses non-genetic inheritance (epigenetics) through parental exposure and other downstream consequences, such as survival of larvae. PMID:27293752

  4. Effects of ocean acidification on embryonic respiration and development of a temperate wrasse living along a natural CO2 gradient.

    PubMed

    Cattano, Carlo; Giomi, Folco; Milazzo, Marco

    2016-01-01

    Volcanic CO2 seeps provide opportunities to investigate the effects of ocean acidification on organisms in the wild. To understand the influence of increasing CO2 concentrations on the metabolic rate (oxygen consumption) and the development of ocellated wrasse early life stages, we ran two field experiments, collecting embryos from nesting sites with different partial pressures of CO2 [pCO2; ambient (∼400 µatm) and high (800-1000 µatm)] and reciprocally transplanting embryos from ambient- to high-CO2 sites for 30 h. Ocellated wrasse offspring brooded in different CO2 conditions had similar responses, but after transplanting portions of nests to the high-CO2 site, embryos from parents that spawned in ambient conditions had higher metabolic rates. Although metabolic phenotypic plasticity may show a positive response to high CO2, it often comes at a cost, in this case as a smaller size at hatching. This can have adverse effects because smaller larvae often exhibit a lower survival in the wild. However, the adverse effects of increased CO2 on metabolism and development did not occur when embryos from the high-CO2 nesting site were exposed to ambient conditions, suggesting that offspring from the high-CO2 nesting site could be resilient to a wider range of pCO2 values than those belonging to the site with present-day pCO2 levels. Our study identifies a crucial need to increase the number of studies dealing with these processes under global change trajectories and to expand these to naturally high-CO2 environments, in order to assess further the adaptive plasticity mechanism that encompasses non-genetic inheritance (epigenetics) through parental exposure and other downstream consequences, such as survival of larvae.

  5. Sensitivity to ocean acidification parallels natural pCO2 gradients experienced by Arctic copepods under winter sea ice.

    PubMed

    Lewis, Ceri N; Brown, Kristina A; Edwards, Laura A; Cooper, Glenn; Findlay, Helen S

    2013-12-17

    The Arctic Ocean already experiences areas of low pH and high CO2, and it is expected to be most rapidly affected by future ocean acidification (OA). Copepods comprise the dominant Arctic zooplankton; hence, their responses to OA have important implications for Arctic ecosystems, yet there is little data on their current under-ice winter ecology on which to base future monitoring or make predictions about climate-induced change. Here, we report results from Arctic under-ice investigations of copepod natural distributions associated with late-winter carbonate chemistry environmental data and their response to manipulated pCO2 conditions (OA exposures). Our data reveal that species and life stage sensitivities to manipulated OA conditions were correlated with their vertical migration behavior and with their natural exposures to different pCO2 ranges. Vertically migrating adult Calanus spp. crossed a pCO2 range of >140 μatm daily and showed only minor responses to manipulated high CO2. Oithona similis, which remained in the surface waters and experienced a pCO2 range of <75 μatm, showed significantly reduced adult and nauplii survival in high CO2 experiments. These results support the relatively untested hypothesis that the natural range of pCO2 experienced by an organism determines its sensitivity to future OA and highlight that the globally important copepod species, Oithona spp., may be more sensitive to future high pCO2 conditions compared with the more widely studied larger copepods.

  6. Sensitivity to ocean acidification parallels natural pCO2 gradients experienced by Arctic copepods under winter sea ice

    PubMed Central

    Lewis, Ceri N.; Brown, Kristina A.; Edwards, Laura A.; Cooper, Glenn; Findlay, Helen S.

    2013-01-01

    The Arctic Ocean already experiences areas of low pH and high CO2, and it is expected to be most rapidly affected by future ocean acidification (OA). Copepods comprise the dominant Arctic zooplankton; hence, their responses to OA have important implications for Arctic ecosystems, yet there is little data on their current under-ice winter ecology on which to base future monitoring or make predictions about climate-induced change. Here, we report results from Arctic under-ice investigations of copepod natural distributions associated with late-winter carbonate chemistry environmental data and their response to manipulated pCO2 conditions (OA exposures). Our data reveal that species and life stage sensitivities to manipulated OA conditions were correlated with their vertical migration behavior and with their natural exposures to different pCO2 ranges. Vertically migrating adult Calanus spp. crossed a pCO2 range of >140 μatm daily and showed only minor responses to manipulated high CO2. Oithona similis, which remained in the surface waters and experienced a pCO2 range of <75 μatm, showed significantly reduced adult and nauplii survival in high CO2 experiments. These results support the relatively untested hypothesis that the natural range of pCO2 experienced by an organism determines its sensitivity to future OA and highlight that the globally important copepod species, Oithona spp., may be more sensitive to future high pCO2 conditions compared with the more widely studied larger copepods. PMID:24297880

  7. The natural latitudinal distribution of atmospheric CO 2

    NASA Astrophysics Data System (ADS)

    Taylor, John A.; Orr, James C.

    2000-12-01

    Although poorly understood, the north-south distribution of the natural component of atmospheric CO 2 offers information essential to improving our understanding of the exchange of CO 2 between the atmosphere, oceans, and biosphere. The natural or unperturbed component is equivalent to that part of the atmospheric CO 2 distribution which is controlled by non-anthropogenic CO 2 fluxes from the ocean and terrestrial biosphere. Models should be able to reproduce the true north-south gradient in CO 2 due to the natural component before they can reliably estimate present-day CO 2 sources and sinks and predict future atmospheric CO 2. We have estimated the natural latitudinal distribution of atmospheric CO 2, relative to the South Pole, using measurements of atmospheric CO 2 during 1959-1991 and corresponding estimates of anthropogenic CO 2 emissions to the atmosphere. Key features of the natural latitudinal distribution include: (1) CO 2 concentrations in the northern hemisphere that are lower than those in the southern hemisphere; (2) CO 2 concentration differences that are higher in the tropics (associated with outgassing of the oceans) than those currently measured; and (3) CO 2 concentrations over the southern ocean that are relatively uniform. This natural latitudinal distribution and its sensitivity to increasing fossil fuel emissions both indicate that near-surface concentrations of atmospheric CO 2 in the northern hemisphere are naturally lower than those in the southern hemisphere. Models that find the contrary will also mismatch present-day CO 2 in the northern hemisphere and incorrectly ascribe that region as a large sink of anthropogenic CO 2.

  8. How secure is subsurface CO2 storage? Controls on leakage in natural CO2 reservoirs

    NASA Astrophysics Data System (ADS)

    Miocic, Johannes; Gilfillan, Stuart; McDermott, Christopher; Haszeldine, Stuart

    2014-05-01

    Carbon Capture and Storage (CCS) is the only industrial scale technology available to directly reduce carbon dioxide (CO2) emissions from fossil fuelled power plants and large industrial point sources to the atmosphere. The technology includes the capture of CO2 at the source and transport to subsurface storage sites, such as depleted hydrocarbon reservoirs or saline aquifers, where it is injected and stored for long periods of time. To have an impact on the greenhouse gas emissions it is crucial that there is no or only a very low amount of leakage of CO2 from the storage sites to shallow aquifers or the surface. CO2 occurs naturally in reservoirs in the subsurface and has often been stored for millions of years without any leakage incidents. However, in some cases CO2 migrates from the reservoir to the surface. Both leaking and non-leaking natural CO2 reservoirs offer insights into the long-term behaviour of CO2 in the subsurface and on the mechanisms that lead to either leakage or retention of CO2. Here we present the results of a study on leakage mechanisms of natural CO2 reservoirs worldwide. We compiled a global dataset of 49 well described natural CO2 reservoirs of which six are leaking CO2 to the surface, 40 retain CO2 in the subsurface and for three reservoirs the evidence is inconclusive. Likelihood of leakage of CO2 from a reservoir to the surface is governed by the state of CO2 (supercritical vs. gaseous) and the pressure in the reservoir and the direct overburden. Reservoirs with gaseous CO2 is more prone to leak CO2 than reservoirs with dense supercritical CO2. If the reservoir pressure is close to or higher than the least principal stress leakage is likely to occur while reservoirs with pressures close to hydrostatic pressure and below 1200 m depth do not leak. Additionally, a positive pressure gradient from the reservoir into the caprock averts leakage of CO2 into the caprock. Leakage of CO2 occurs in all cases along a fault zone, indicating that

  9. Vertical CO2 gradient as an indicator of stratospheric circulation

    NASA Astrophysics Data System (ADS)

    Sugawara, S.; Aoki, S.; Morimoto, S.; Nakazawa, T.; Ishidoya, S.; Toyoda, S.; Honda, H.

    2013-12-01

    It is expected that a possible long-term change of the Brewer-Dobson (BD) circulation is detectable from the change of mean age evaluated from the stratospheric CO2 and SF6 concentrations. However, the result obtained from balloon experiments does not agree with recent model predictions of an accelerating BD circulation with an enhanced mass flux from the tropical troposphere into the stratosphere. This discrepancy between observations and models can be resolved if the poleward transport in the lower stratosphere is enhanced and compensate for increased tropical upwelling. If the poleward transports in the lower and upper layers have been differently changed, there is a possibility that we can detect it as a change of the vertical CO2 gradient. Therefore, the long-term trend of the vertical gradient was examined by using our balloon data. Systematic collections of stratospheric air samples have been carried out over Japan since 1985, using a balloon-borne cryogenic sampler. The stratospheric air samples have been collected almost once a year or two years at 11 assigned heights, ranging from the tropopause to 30 - 35 km. The air samples collected were analyzed for the CO2 and SF6 concentrations and various gases. We used CO2 data observed by 17 balloon experiments during the last 25 years. The average vertical gradients, calculated by applying a least-squares method to the vertical CO2 distributions in the mid-stratosphere, are varying within -0.14 ~ +0.12 ppmv/km with a clear decreasing trend. The average change rate of the vertical CO2 gradient was calculated to be -0.08×0.02 ppmv/km/decade. By applying a statistical testing, it was concluded that the decreasing trend of the vertical CO2 gradient above 20-25 km in the past 25 years is significant with 80 % confidence level. We also calculated CO2-age by comparing CO2 concentration with the convolutions of the age spectrum and the reference function of tropospheric CO2 variation. As a result, we found that the

  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. A CO2 concentration gradient facility for testing CO2 enrichment and soil effects on grassland ecosystem function

    USDA-ARS?s Scientific Manuscript database

    Continuing increases in atmospheric CO2 concentrations mandate techniques for examining impacts on terrestrial ecosystems. Most experiments examine only two or a few levels of CO2 concentration and a single soil type, but if CO2 can be varied as a gradient from subambient to superambient concentra...

  12. Natural Analog for Geologic Storage of CO2: CO2 accumulation in China

    NASA Astrophysics Data System (ADS)

    Liu, L.; Xu, T.; Liu, N.; Zhou, B.

    2012-12-01

    Natural accumulations of CO2 are potential analogues of CO2 geological storage that can provide useful information on the behaviour of supercritical CO2 in reservoirs. Natural CO2 accumulations are common across Northeast China, and, although they occur in a wide variety of geological settings, their distribution is principally controlled by the Mesozoic-Cenozoic rift basins and associated Quaternary volcanism. High CO2 concentrations (>60 CO2%) in natural gas reservoirs are usually related to volcanism and magmatism, and possesses mantle-genetic origin. CO2 reservoirs consist of sandstone, volcanic rocks and carbonate rocks with the buried depth from 2000-3000 m. Dawsonite is recognized in almost all of the CO2-bearing basin, which has been proved to share the same carbon source with CO2 in the reservoirs in Songliao basin, Hailaer basin and Donghai basin. Petrographic data show that dawsonite is abundant in feldspar- rich sandstone, volcanic rock fragment-rich sandstones and tuff. In some cases, high percentage of dawsonite cement constitutes a diagenetic seal, which occurs in the reservoir-mudstone caprock and prevents upward leakage of CO2. Besides dawsonite, mantle-genetic CO2 flux leads to the formation of calcite, ankerite and siderite. The statistics of porosity and permeability measured from the dawsonite-bearing sandstone and dawsonite-absent sandstone with the almost same burial depth in Songliao basin show that the mantle-genetic CO2 flux result in lower reservoir quality, suggesting that mineral trapping for CO2 is significant. Chemical analyses of formation water in Songliao basin and Hailaer basin indicate that the concentrations of TDS, HCO3-,CO32-, Mg2+,Ca2+ and Na+ + K+ in dawsonite-bearing sandstone are higher than that in dawsonite-absent sandstone. Distribution of CO2 and dawsonite is constrainted by the regional caprocks in the Songliao basin. The charging time of the mantle-genetic CO2 in China dates from 50 to 25 Ma.

  13. How much CO2 is trapped in carbonate minerals of a natural CO2 occurrence?

    NASA Astrophysics Data System (ADS)

    Király, Csilla; Szabó, Zsuzsanna; Szamosfalvi, Ágnes; Cseresznyés, Dóra; Király, Edit; Szabó, Csaba; Falus, György

    2017-04-01

    Carbon Capture and Storage (CCS) is a transitional technology to decrease CO2 emissions from human fossil fuel usage and, therefore, to mitigate climate change. The most important criteria of a CO2 geological storage reservoir is that it must hold the injected CO2 for geological time scales without its significant seepage. The injected CO2 undergoes physical and chemical reactions in the reservoir rocks such as structural-stratigraphic, residual, dissolution or mineral trapping mechanisms. Among these, the safest is the mineral trapping, when carbonate minerals such as calcite, ankerite, siderite, dolomite and dawsonite build the CO2 into their crystal structures. The study of natural CO2 occurrences may help to understand the processes in CO2 reservoirs on geological time scales. This is the reason why the selected, the Mihályi-Répcelak natural CO2 occurrence as our research area, which is able to provide particular and highly significant information for the future of CO2 storage. The area is one of the best known CO2 fields in Central Europe. The main aim of this study is to estimate the amount of CO2 trapped in the mineral phase at Mihályi-Répcelak CO2 reservoirs. For gaining the suitable data, we apply petrographic, major and trace element (microprobe and LA-ICP-MS) and stable isotope analysis (mass spectrometry) and thermodynamic and kinetic geochemical models coded in PHREEQC. Rock and pore water compositions of the same formation, representing the pre-CO2 flooding stages of the Mihályi-Répcelak natural CO2 reservoirs are used in the models. Kinetic rate parameters are derived from the USGS report of Palandri and Kharaka (2004). The results of petrographic analysis show that a significant amount of dawsonite (NaAlCO3(OH)2, max. 16 m/m%) precipitated in the rock due to its reactions with CO2 which flooded the reservoir. This carbonate mineral alone traps about 10-30 kg/m3 of the reservoir rock from the CO2 at Mihályi-Répcelak area, which is an

  14. CO2 laser cutting of natural granite

    NASA Astrophysics Data System (ADS)

    Riveiro, A.; Mejías, A.; Soto, R.; Quintero, F.; del Val, J.; Boutinguiza, M.; Lusquiños, F.; Pardo, J.; Pou, J.

    2016-01-01

    Commercial black granite boards (trade name: "Zimbabwe black granite") 10 mm thick, were successfully cut by a 3.5 kW CO2 laser source. Cutting quality, in terms of kerf width and roughness of the cut wall, was assessed by means of statistically planned experiments. No chemical modification of the material in the cutting walls was detected by the laser beam action. Costs associated to the process were calculated, and the main factors affecting them were identified. Results reported here demonstrate that cutting granite boards could be a new application of CO2 laser cutting machines provided a supersonic nozzle is used.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  16. Nonlinear Grassland Dynamics Along a CO2 Gradient

    USDA-ARS?s Scientific Manuscript database

    Plant photosynthesis and transpiration respond nonlinearly to atmospheric CO2 concentration and vapor pressure deficit, depending on plant water status and thus soil moisture. Modeling vegetation and soil responses to different values of CO2, is critical to predict ecosystem functioning under enrich...

  17. Effective Use of Natural CO2-RICH Systems for Stakeholder Communication: CO2FACTS.ORG

    NASA Astrophysics Data System (ADS)

    Olson, H. C.; Romanak, K.; Osborne, V.; Hovorka, S. D.; Clift, S.; Castner, A.

    2011-12-01

    The impact of using natural analogues as an avenue for communicating about CO2 injection and storage technology with stakeholders has been addressed by previous researchers, e.g., Romanak et al (2011), Dixon et al (2011). Analogies between natural CO2-rich systems and engineered CO2 storage are not necessarily straightforward, and stakeholder opinion is often based on factors other than technical accuracy of information (e.g., lack of trust, confidence, and fear). In order to enhance this communication pathway, STORE (Sequestration Training, Outreach, Research and Education), the outreach arm of the Gulf Coast Carbon Center at The University of Texas at Austin, has created an online resource (www.co2facts.org) to help stakeholders better understand the injection and storage of CO2 underground. The online resource includes frequently asked questions (FAQs) for a variety of CO2-storage-related issues, including those related to natural analogues, and uses examples of natural systems of CO2 release for communication. The content targets various levels of technical education and understanding. A unique feature of the online resource is its approach to verification of information. Each FAQ and example is "fact-checked" by an actual expert in the field. Part of this verification process is to provide an online link to background, credentials, scientific research and images of actual experts in the field at natural release sites. This approach helps put a face to, and potentially builds a relationship of trust with, the scientist behind the technical information. Videos of experts discussing natural systems and their similarities and differences with CO2 injection and storage sites are also part of the resource. Stakeholders commonly draw incorrect parallels between natural disasters that gain attention in the media (e.g., Lake Nyos) and CO2 injection and storage technology. The video images available at www.co2facts.org are a useful tool for assuaging environmental fears

  18. Natural CO2 Releases Providing Messages For Stakeholders

    NASA Astrophysics Data System (ADS)

    Dixon, T.; Romanak, K.; Camps, A. P.

    2011-12-01

    Stakeholder viewpoints and beliefs about geologic carbon storage are not always accurate, yet they may affect the future of carbon capture and storage (CCS). Gaps in stakeholder understanding and perspectives must be addressed, and natural systems that release CO2 can be valuable tools for communicating difficult scientific concepts because they provide tangible examples of geologic principles at work. Stakeholder perceptions commonly involve a misunderstanding of geologic scale and mechanisms, and can be charged with emotions fueled by media coverage of natural disasters. One example of an event widely cited by stakeholders is the CO2 release at Lake Nyos in Cameroon in August 1986 that killed 1700 people. This event is commonly thought by stakeholders to be an analogue for a release from a CO2 storage site; however, this release occurred under a rare combination of circumstances (a 208-m-deep volcanic crater lake) not analogous to an engineered CO2 storage site. Stakeholders therefore gravitate towards natural systems to form concepts and opinions of how CO2 might behave in a geological environment, but they often choose systems that are not true analogues but that gain attention through the media because they are associated with a disaster. When chosen correctly, natural releases of CO2 may create a level of clarity for stakeholders by providing tangible concrete examples that explain difficult scientific principles and provide familiar reference points to adapt different viewpoints. We present suggestions and examples presented by scientists at an IEAGHG Workshop Natural Releases of CO2: Building Knowledge for CO2 Storage Environmental Impact Assessments', held at Maria Laach, Germany, November 2010 which brought together researchers from the EU, North America, Japan, and Australia. It also included field observations of natural CO2 releases around the Laacher See caldera lake, CO2 springs, and the Wallenborn CO2 geyser. New information from international

  19. Natural CO2 Analogs for Carbon Sequestration

    SciTech Connect

    Scott H. Stevens; B. Scott Tye

    2005-07-31

    The report summarizes research conducted at three naturally occurring geologic CO{sub 2} fields in the US. The fields are natural analogs useful for the design of engineered long-term storage of anthropogenic CO{sub 2} in geologic formations. Geologic, engineering, and operational databases were developed for McElmo Dome in Colorado; St. Johns Dome in Arizona and New Mexico; and Jackson Dome in Mississippi. The three study sites stored a total of 2.4 billion t (46 Tcf) of CO{sub 2} equivalent to 1.5 years of power plant emissions in the US and comparable in size with the largest proposed sequestration projects. The three CO{sub 2} fields offer a scientifically useful range of contrasting geologic settings (carbonate vs. sandstone reservoir; supercritical vs. free gas state; normally pressured vs. overpressured), as well as different stages of commercial development (mostly undeveloped to mature). The current study relied mainly on existing data provided by the CO{sub 2} field operator partners, augmented with new geochemical data. Additional study at these unique natural CO{sub 2} accumulations could further help guide the development of safe and cost-effective design and operation methods for engineered CO{sub 2} storage sites.

  20. The Werkendam natural CO2 accumulation: An analogue for CO2 storage in depleted oil reservoirs

    NASA Astrophysics Data System (ADS)

    Bertier, Pieter; Busch, Andreas; Hangx, Suzanne; Kampman, Niko; Nover, Georg; Stanjek, Helge; Weniger, Philipp

    2015-04-01

    The Werkendam natural CO2 accumulation is hosted in the Röt (Early Triassic) sandstone of the West Netherlands Basin, at a depth of 2.8 km, about 20 km south-east of Rotterdam (NL). This reservoir, in a fault-bound structure, was oil-filled prior to charging with magmatic CO2 in the early Cretaceous. It therefore offers a unique opportunity to study long-term CO2-water-rock interactions in the presence of oil. This contribution will present the results of a detailed mineralogical and geochemical characterisation of core sections from the Werkendam CO2 reservoir and an adjacent, stratigraphically equivalent aquifer. X-ray diffraction combined with X-ray fluorescence spectrometry revealed that the reservoir samples contain substantially more feldspar and more barite and siderite than those from the aquifer, while the latter have higher hematite contents. These differences are attributed to the effects hydrocarbons and related fluids on diagenesis in the closed system of the CO2 reservoir versus the open-system of the aquifer. Petrophysical analyses yielded overall higher and more anisotropic permeability for the reservoir samples, while the porosity is overall not significantly different from that of their aquifer equivalents. The differences are most pronounced in coarse-grained sandstones. These have low anhydrite contents and contain traces of calcite, while all other analyzed samples contain abundant anhydrite, dolomite/ankerite and siderite, but no calcite. Detailed petrography revealed mm-sized zones of excessive primary porosity. These are attributed to CO2-induced dissolution of precompactional, grain-replacive anhydrite cement. Diagenetic dolomite/ankerite crystals are covered by anhedral, epitaxial ankerite, separated from the crystals by bitumen coats. Since these carbonates were oil-wet before CO2-charging, the overgrowths are interpreted to have grown after CO2-charging. Their anhedral habit suggests growth in a 2-phase water-CO2 system. Isotopic

  1. Distribution and nature of CO2 on Enceladus

    NASA Astrophysics Data System (ADS)

    Combe, J. P.; McCord, T. B.; Matson, D.; Johnson, T. V.; Scipioni, F.; Tosi, F.

    2015-12-01

    We present the first global mapping and analysis of CO2 on the surface of Enceladus, and we report the largest concentrations of free CO2 on the southern polar region using the Visual and Infrared Mapping Spectrometer (VIMS) on Cassini. Free CO2 ice and complexed CO2 were already reported near the South Pole (Brown et al., Science, 2006; Hansen, LPSC, 2010). Our work focuses on determining the amount, location and molecular state of CO2 on Enceladus, which could help identify and model geophysical processes that currently occur in the interior. One hypothesis for bringing heat and chemicals to the surface is a warm subsurface ocean containing dissolved gases, mostly CO2 (Postberg F. et al., Nature, 2009). Therefore, our observations are consistent with erupted and condensed materials onto Enceladus' surface (Matson et al., Icarus, 2012; Matson et al. AGU Fall meeting 2015). Free CO2 ice absorbs at 4.268 µm (Sandford and Allamandola, 1990) and CO2 complexed with other molecules absorbs at 4.247 μm (Chaban et al., Icarus, 2007). The Enceladus case is complicated because both free and complexed CO2 are present, and the absorption band of interest is shallow and close to the instrument detection limit. Many of the few Enceladus VIMS data sets have significant and sometimes unusual noise, which we attempted to avoid or remove. We utilized all VIMS data sets available that were collected over ten years of the Cassini mission as a way to improve the detection statistics and signal to noise. We also used wavelengths near 2.7 μm where CO2 has a narrow absorption as a filter to help identify CO2-rich areas. Finally, we selected observations that have spatial resolution better than 100 km in order to create a map that can be compared with the largest fractures, known as Tiger Stripes, in the southern polar region.

  2. Soil type interacts with soil respiration in prairie exposed to a gradient CO2

    USDA-ARS?s Scientific Manuscript database

    Changes in soil respiration due to rising atmospheric CO2 have large implications for land-atmosphere carbon balance and consequently the greenhouse effect. Here we report results from prairie exposed to a gradient of CO2 spanning from preindustrial (250ppm) levels to levels expected mid-century ...

  3. Tracing the CO2 source and migration in natural analogues from different geological contexts

    NASA Astrophysics Data System (ADS)

    Battani, A.; Jean Luc, F.; Philippe, S.; Nadine, E.; Olivier, V.; Elodie, J.

    2009-12-01

    Naturally occurring CO2 fields allow studying long-term fluid-rock interactions, and the processes of CO2 migration, useful for the prediction of CO2 behavior in industrial storage sites. Two different provinces showing both leaking systems (hydrothermal areas) and well confined systems (stable sedimentary basins) have been studied. The first province concerns the French CO2 province of Massif Central (volcanic events, seismic activity, high geothermal gradient) and the stable Valence basin. The other study was devoted to the Basin and Range province, USA, with hydrothermal, high seismic and volcanic activity, a high geothermal gradient (Soda Springs; Idaho, Sevier basin), and the non-hydrothermal stable area of the Colorado plateau (Green River, San Rafael anticline and Springerville). The aim is to link the CO2 sources and its subsurface migration to the geological context. In hydrothermal areas, the mesured helium isotopic ratio (R/Ra) is high (close to the mantle ratio), while the CO2/3He ratios move dramatically towards crustal values. In this context, isotopic and elemental noble gas data show that the gas migrates very fast from depth. In more confined areas (natural CO2 fields), the CO2 shows a more important proportion of radiogenic gases (4He) (crustal helium isotopic ratios) and the associated CO2/3He ratios are in the MORB range, or “mantle derived”. We try to explain the apparent discrepancy between the CO2/3He and the R/Ra values in both areas. As a primary assumption, the source of CO2 could be localized in the extensional zones of high geothermal gradient with important seismicity. We suggest that the pseudotachylites formed by frictional melting associated with each seismic event supply an instantaneous crustal CO2.amount to the initial magmatic CO2. This justifies the coeval increase of the CO2/3He ratios without any significant modification in the helium isotopic ratios (instantaneous, no time for 4He production). Moreover, the contact

  4. Calibrating Laser Gas Measurements by Use of Natural CO2

    NASA Technical Reports Server (NTRS)

    Webster, Chris

    2003-01-01

    An improved method of calibration has been devised for instruments that utilize tunable lasers to measure the absorption spectra of atmospheric gases in order to determine the relative abundances of the gases. In this method, CO2 in the atmosphere is used as a natural calibration standard. Unlike in one prior calibration method, it is not necessary to perform calibration measurements in advance of use of the instrument and to risk deterioration of accuracy with time during use. Unlike in another prior calibration method, it is not necessary to include a calibration gas standard (and the attendant additional hardware) in the instrument and to interrupt the acquisition of atmospheric data to perform calibration measurements. In the operation of an instrument of this type, the beam from a tunable diode laser or a tunable quantum-cascade laser is directed along a path through the atmosphere, the laser is made to scan in wavelength over an infrared spectral region that contains one or two absorption spectral lines of a gas of interest, and the transmission (and, thereby, the absorption) of the beam is measured. The concentration of the gas of interest can then be calculated from the observed depth of the absorption line(s), given the temperature, pressure, and path length. CO2 is nearly ideal as a natural calibration gas for the following reasons: CO2 has numerous rotation/vibration infrared spectral lines, many of which are near absorption lines of other gases. The concentration of CO2 relative to the concentrations of the major constituents of the atmosphere is well known and varies slowly and by a small enough amount to be considered constant for calibration in the present context. Hence, absorption-spectral measurements of the concentrations of gases of interest can be normalized to the concentrations of CO2. Because at least one CO2 calibration line is present in every spectral scan of the laser during absorption measurements, the atmospheric CO2 serves

  5. Mixed venous-arterial CO2 tension gradient after cardiopulmonary bypass.

    PubMed

    Takami, Yoshiyuki; Masumoto, Hiroshi

    2005-09-01

    Significant venous hypercarbia has been reported in septic shock and circulatory failure. Cardiopulmonary bypass also impairs systemic and pulmonary blood perfusion. The objective of this study was to determine the clinical significance of the increased venous-arterial CO2 tension gradient resulting from venous hypercarbia after cardiopulmonary bypass. On arrival in the intensive care unit, venous and arterial CO2 tensions were measured in the radial and pulmonary arteries in 140 consecutive patients who had undergone coronary (n = 79), valve (n = 34), aortic (n = 20), and other (n = 7) surgery under cardiopulmonary bypass. The mean venous-arterial CO2 tension gradient was 5.0 +/- 3.3 mm Hg (range, 7.7 to 15.7 mm Hg). By linear regression analysis, the factors that significantly correlated with venous-arterial CO2 tension gradient were bypass duration, aortic crossclamp time, initial arterial lactate level, transpulmonary arteriovenous lactate difference, arterial bicarbonate level, base excess, cardiac index, mixed venous O2 saturation, O2 delivery, O2 consumption, and the peak value of creatine kinase. The venous-arterial CO2 tension gradient may reflect impaired perfusion and anaerobic metabolism induced by cardiopulmonary bypass and could be a simple and useful indicator for patient management after surgery under cardiopulmonary bypass.

  6. Host Plant Physiology and Mycorrhizal Functioning Shift across a Glacial through Future [CO2] Gradient.

    PubMed

    Becklin, Katie M; Mullinix, George W R; Ward, Joy K

    2016-10-01

    Rising atmospheric carbon dioxide concentration ([CO2]) may modulate the functioning of mycorrhizal associations by altering the relative degree of nutrient and carbohydrate limitations in plants. To test this, we grew Taraxacum ceratophorum and Taraxacum officinale (native and exotic dandelions) with and without mycorrhizal fungi across a broad [CO2] gradient (180-1,000 µL L(-1)). Differential plant growth rates and vegetative plasticity were hypothesized to drive species-specific responses to [CO2] and arbuscular mycorrhizal fungi. To evaluate [CO2] effects on mycorrhizal functioning, we calculated response ratios based on the relative biomass of mycorrhizal (MBio) and nonmycorrhizal (NMBio) plants (RBio = [MBio - NMBio]/NMBio). We then assessed linkages between RBio and host physiology, fungal growth, and biomass allocation using structural equation modeling. For T. officinale, RBio increased with rising [CO2], shifting from negative to positive values at 700 µL L(-1) [CO2] and mycorrhizal effects on photosynthesis and leaf growth rates drove shifts in RBio in this species. For T. ceratophorum, RBio increased from 180 to 390 µL L(-1) and further increases in [CO2] caused RBio to shift from positive to negative values. [CO2] and fungal effects on plant growth and carbon sink strength were correlated with shifts in RBio in this species. Overall, we show that rising [CO2] significantly altered the functioning of mycorrhizal associations. These symbioses became more beneficial with rising [CO2], but nonlinear effects may limit plant responses to mycorrhizal fungi under future [CO2]. The magnitude and mechanisms driving mycorrhizal-CO2 responses reflected species-specific differences in growth rate and vegetative plasticity, indicating that these traits may provide a framework for predicting mycorrhizal responses to global change. © 2016 American Society of Plant Biologists. All Rights Reserved.

  7. CO2 gradient affects on deep subsurface microbial ecology during carbon sequestration

    NASA Astrophysics Data System (ADS)

    Gulliver, D.; Gregory, K.

    2011-12-01

    Geological carbon sequestration is likely to be part of a comprehensive strategy to minimize the release of greenhouse gasses into the atmosphere. Reservoir storage capacities and long-term security of these deposits will be dependent on the trapping mechanisms and mineral transformation in the deep subsurface. Therefore, a critical need exists to understand the evolution of microbial populations that may influence the biogeochemistry in the reservoirs. As the CO2 front moves through the storage aquifer, microbial communities may preside in residual brine left behind in cracks, dead flow zones, and upstream to the front; this brine will have a gradient of dissolved CO2 in which microbial interaction may behave differently, depending on the distance from the CO2 front. The evolution of microbial ecology along this CO2 gradient was investigated using fluid-slurry samples obtained from the prospective carbon sequestration site, the Arbuckle saline aquifer at the Wellington oil field, KS. The native species of these samples were investigated with a series of batch reactors under constant temperature of 40 °C, constant total pressure of 2,000 psi, and varying CO2 partial pressures of 0 psi, 20 psi, 200 psi, and 2,000 psi. After 1 day, 7 days, and 56 days of exposure in the batch reactors, fluid samples were centrifuged and the resulting pellet was biologically analyzed. Clone libraries and quantitative PCR determined that the bacterial diversity and population of the native microbial community was dependant on both the duration of exposure and the CO2 partial pressure. For example, the microbial community of 0 psi CO2 and 20 psi CO2 was predominantly related to the families halomonadaceae and marinilabiaceae while at 2,000 psi CO2 the community was predominantly in the family psychromonadaceae. The population size at 2,000 psi CO2 was also found to decrease by 3 orders of magnitude after only 7 days of CO2 exposure. Although these experiments were relatively short

  8. Natural analogue study of CO2 storage monitoring using probability statistics of CO2-rich groundwater chemistry

    NASA Astrophysics Data System (ADS)

    Kim, K. K.; Hamm, S. Y.; Kim, S. O.; Yun, S. T.

    2016-12-01

    For confronting global climate change, carbon capture and storage (CCS) is one of several very useful strategies as using capture of greenhouse gases like CO2 spewed from stacks and then isolation of the gases in underground geologic storage. CO2-rich groundwater could be produced by CO2 dissolution into fresh groundwater around a CO2 storage site. As consequence, natural analogue studies related to geologic storage provide insights into future geologic CO2 storage sites as well as can provide crucial information on the safety and security of geologic sequestration, the long-term impact of CO2 storage on the environment, and field operation and monitoring that could be implemented for geologic sequestration. In this study, we developed CO2 leakage monitoring method using probability density function (PDF) by characterizing naturally occurring CO2-rich groundwater. For the study, we used existing data of CO2-rich groundwaters in different geological regions (Gangwondo, Gyeongsangdo, and Choongchungdo provinces) in South Korea. Using PDF method and QI (quantitative index), we executed qualitative and quantitative comparisons among local areas and chemical constituents. Geochemical properties of groundwater with/without CO2 as the PDF forms proved that pH, EC, TDS, HCO3-, Ca2+, Mg2+, and SiO2 were effective monitoring parameters for carbonated groundwater in the case of CO2leakage from an underground storage site. KEY WORDS: CO2-rich groundwater, CO2 storage site, monitoring parameter, natural analogue, probability density function (PDF), QI_quantitative index Acknowledgement This study was supported by the "Basic Science Research Program through the National Research Foundation of Korea (NRF), which is funded by the Ministry of Education (NRF-2013R1A1A2058186)" and the "R&D Project on Environmental Management of Geologic CO2 Storage" from KEITI (Project number: 2014001810003).

  9. Adaptation by macrophytes to inorganic carbon down a river with naturally variable concentrations of CO2.

    PubMed

    Maberly, S C; Berthelot, S A; Stott, A W; Gontero, B

    2015-01-01

    The productivity and ecological distribution of freshwater plants can be controlled by the availability of inorganic carbon in water despite the existence of different mechanisms to ameliorate this, such as the ability to use bicarbonate. Here we took advantage of a short, natural gradient of CO2 concentration, against a background of very high and relatively constant concentration of bicarbonate, in a spring-fed river, to study the effect of variable concentration of CO2 on the ability of freshwater plants to use bicarbonate. Plants close to the source, where the concentration of CO2 was up to 24 times air equilibrium, were dominated by Berula erecta. pH-drift results and discrimination against (13)C were consistent with this and the other species being restricted to CO2 and unable to use the high concentration of bicarbonate. There was some indication from stable (13)C data that B. erecta may have had access to atmospheric CO2 at low water levels. In contrast, species downstream, where concentrations of CO2 were only about 5 times air-equilibrium were almost exclusively able to use bicarbonate, based on pH-drift results. Discrimination against (13)C was also consistent with bicarbonate being the main source of inorganic carbon for photosynthesis in these species. There was, therefore, a transect downstream from the source of increasing ability to use bicarbonate that closely matched the decreasing concentration of CO2. This was produced largely by altered species composition, but partly by phenotypic changes in individual species.

  10. Seagrass biofilm communities at a naturally CO2 -rich vent.

    PubMed

    Hassenrück, Christiane; Hofmann, Laurie C; Bischof, Kai; Ramette, Alban

    2015-06-01

    Seagrass meadows are a crucial component of tropical marine reef ecosystems. Seagrass plants are colonized by a multitude of epiphytic organisms that contribute to broadening the ecological role of seagrasses. To better understand how environmental changes like ocean acidification might affect epiphytic assemblages, the microbial community composition of the epiphytic biofilm of Enhalus acroides was investigated at a natural CO2 vent in Papua New Guinea using molecular fingerprinting and next-generation sequencing of 16S and 18S rRNA genes. Both bacterial and eukaryotic epiphytes formed distinct communities at the CO2 -impacted site compared with the control site. This site-related CO2 effect was also visible in the succession pattern of microbial epiphytes. We further found an increased relative sequence abundance of bacterial types associated with coral diseases at the CO2 -impacted site (Fusobacteria, Thalassomonas), whereas eukaryotes such as certain crustose coralline algae commonly related to healthy reefs were less diverse. These trends in the epiphytic community of E. acroides suggest a potential role of seagrasses as vectors of coral pathogens and may support previous predictions of a decrease in reef health and prevalence of diseases under future ocean acidification scenarios. © 2015 The Authors. Environmental Microbiology Reports published by Society for Applied Microbiology and John Wiley & Sons Ltd.

  11. Summertime Atmospheric Boundary Layer Gradients of O2 and CO2 Over the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Morgan, E. J.; Stephens, B. B.; Bent, J.; Long, M. C.; Sweeney, C.; McKain, K.; Keeling, R. F.

    2016-12-01

    The variability of oxygen and carbon dioxide in the troposphere are closely linked by surface fluxes from processes such as photosynthesis, respiration, and air-sea gas exchange. Airborne measurements of (O2/N2) and CO2 taken during the O2/N2 Ratio and CO2 Airborne Southern Ocean (ORCAS) study over the Drake Passage and Antarctic Peninsula in austral summer 2016 allowed for the study of the covariation of these two gases in detail. The vertical distribution from the mid-troposphere to the surface of (O2/N2) and CO2 during the campaign was dominated by a large-scale enhancement of oxygen and depletion of CO2 in the lower troposphere, a result of summertime marine net productivity in the Southern Ocean. The strength of the vertical gradient in both species varied from flight to flight, but converged on the regional scale to a molar ratio of -2.8 ± 0.3. As the exact molar ratio and vertical gradient of CO2 and O2 in the troposphere is a result of the influence of many biogeochemical processes, this airborne dataset provided an opportunity to rigorously test simulations from a coupled earth system model. First results implied that the model overestimated both the marine CO2 sink and the oxygen source.

  12. [The arterio-alveolar CO2 gradient. Physiopathological and clinical significance].

    PubMed

    Foscale, M; Giacone, A; Cardellino, G; Garbagni, R

    1978-05-09

    The arterio-alveolar CO(2) gradient was examined in 20 patients with various ventilation diseases. It increased or became negative in obstruction. The tendency to increase was attributable to distribution disturbances, particularly the marked increase in the "dead space" effect. The same picture, though to a lesser degree, owing to a smaller dead space increase, was even more frequent in restriction cases. The appearance of a gradient in healthy subjects is referable to uneven air and blood distribution in the alveoli under physiological conditions. The physiopathological significance of negative gradients is discussed in the light of the results and the findings of other workers.

  13. The importance of internal CO2 gradients in tree roots for assessing belowground carbon allocation

    NASA Astrophysics Data System (ADS)

    Bloemen, Jasper; De Bel, Bryan; Wittocx, Jonas; Anné, Thomas; McGuire, Mary Anne; Teskey, Robert O.; Steppe, Kathy

    2015-04-01

    In trees, it is known that allocation of recent assimilates belowground fuels metabolic processes like root respiration. Nonetheless, the fraction of carbon allocated belowground remains poorly quantified as the energetic costs of tree root metabolism remain largely unknown. Current estimates of root respiration are calculated from measurements of CO2 efflux from roots or soil. However, a substantial portion of CO2 released by root respiration might remain within the tree root system rather than diffusing into the soil environment, indicating that root respiration consumes substantially more carbohydrates than previously recognized. We measured internal CO2 concentration ([CO2]) and sap flow in three longitudinal sections of two large roots of American beech (Fagus grandifolia) and yellow poplar (Liriodendron tulipifera) trees (n=4 trees per species), while simultaneously measuring [CO2] in neighboring soil. We hypothesized that [CO2] would be lowest in soil and increase from the root tip to the base of the stem. We observed substantially higher [CO2] in tree roots (on average 8.5 ± 2.0 and 5.2 ± 1.9 Vol% for American beech and yellow poplar, respectively) compared with the soil environment (1.0 ± 0.4 and 1.3 ± 1.3 Vol% around American beech and yellow poplar, respectively), indicating that root tissues exert substantial barriers to outward diffusion of respired CO2. Moreover, we observed an internal [CO2] gradient from root tip to stem base which suggests that progressively more respired CO2 dissolved in flowing xylem sap as it moved from the soil through the root xylem. These results confirm that a fraction of root-respired CO2 concentrates in the xylem sap of the root system and fluxes upward within the tree. This CO2 that is removed from the site of respiration cannot be accounted for with measurements of CO2 efflux from roots or soil, indicating that efflux-based techniques underestimate the energetic costs of tree root metabolism and therefore the amount

  14. Application research of CO2 laser cutting natural stone plates

    NASA Astrophysics Data System (ADS)

    Ma, Lixiu; Song, Jijiang

    2009-08-01

    Now, the processing of natural stone plates is the high performance sawing machine primarily,many researchers deeply studied the processing characters in the sawing process and the strength characters during the processing. In order to realize the profiled-processing and pattern- carving of the natural stone, It lays a solid foundation for the laser cutting and the pattern-carving technology of natural stone plate. The working principle, type and characteristics of laser cutting are briefly described. The paper selects 6 kinds stone plates of natural taken as experimental sample,the experimental sample was China Shanxi Black, Old Spain Golden Yellow, New Spain Golden Yellow, Jazz White, Maple Leaf Red, Cream White respectively. Use high power CO2 laser cutting system,the stone plates cutting experiment of 6 kinds different hardness, the best working speed are obtained,The experimental results indicate that: The laser cutting speed has no correlation with the ingredient content of stone plate.

  15. Primary productivity and water balance of grassland vegetation on three soils in a continuous CO2 gradient: initial results from the lysimeter CO2 gradient experiment

    USDA-ARS?s Scientific Manuscript database

    Field studies of atmospheric CO2 effects on ecosystem processes usually include only a few levels of CO2 and a single soil type, making it difficult to ascertain the shape of ecosystem responses to increasing CO2 or to generalize CO2 effects across ecosystems on varying soil types. The Lysimeter CO2...

  16. Does leaf photosynthesis adapt to CO2-enriched environments? An experiment on plants originating from three natural CO2 springs.

    PubMed

    Onoda, Yusuke; Hirose, Tadaki; Hikosaka, Kouki

    2009-01-01

    Atmospheric CO2 elevation may act as a selective agent, which consequently may alter plant traits in the future. We investigated the adaptation to high CO2 using transplant experiments with plants originating from natural CO2 springs and from respective control sites. We tested three hypotheses for adaptation to high-CO2 conditions: a higher photosynthetic nitrogen use efficiency (PNUE); a higher photosynthetic water use efficiency (WUE); and a higher capacity for carbohydrate transport from leaves. Although elevated growth CO2 enhanced both PNUE and WUE, there was no genotypic improvement in PNUE. However, some spring plants had a higher WUE, as a result of a significant reduction in stomatal conductance, and also a lower starch concentration. Higher natural variation (assessed by the coefficient of variation) within populations in WUE and starch concentration, compared with PNUE, might be responsible for the observed population differentiation. These results support the concept that atmospheric CO2 elevation can act as a selective agent on some plant traits in natural plant communities. Reduced stomatal conductance and reduced starch accumulation are highlighted for possible adaptation to high CO2.

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

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

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

  18. Lessons from Natural CO2 Leakage Analogue Site Studies and their Application to Secure CO2 Storage and Monitoring

    NASA Astrophysics Data System (ADS)

    Han, W.; McPherson, B. J.; Kim, K.; Chae, G.; Yum, B.

    2011-12-01

    At CO2 injection sites, CO2 leakage from the storage formation could be catastrophic. CO2 is a highly compressible fluid, typically injected at high pressure and temperature conditions. If this compressed CO2 reaches highly permeable conduits such as faults and fractures, CO2 could leak unabated to other formations (e.g. fresh water aquifers) and/or to the surface. Assuming a fast-flow path to the surface, CO2 escaping from the storage formation instantaneously reaches the surface while experiencing adiabatic expansion, which results in Joule-Thomson cooling. The addressed eruptive mechanisms are analogues to natural CO2 eruption mechanisms, which are found in CO2-driven cold-water geysers around the world. A notable example of a CO2-driven cold-water geyser is the Crystal Geyser in central Utah. The fluid mechanics of this regularly erupting geyser was investigated by instrumenting its conduit with pressure, temperature, pH, EC, and dissolved oxygen sensors, measuring every 1 minute during and between eruptions. Results of these measurements suggest that the time-scale of a single-eruption cycle is composed of four successive eruption types with two recharge periods ranging from 30 to 40 hours. Current eruption patterns exhibit a bimodal distribution although previous measurements and anecdotal evidence suggests that this pattern was different prior to recent seismic activity. This cold geyser's eruptions are regular and predictable, and reflect pressure, temperature, EC, pH, and dissolved oxygen changes resulting from Joule-Thomson cooling, endothermic CO2 exsolution, and exothermic CO2 dissolution. Specifically, the perturbation of pressure and temperature data observed at the Crystal Geyser suggested the possibility of using temperature sensing technology within the observation well at the engineered CO2 sequestration site. With the lessons learned from the Crystal Geyser studies, we established the theoretical framework of temperature changes caused by CO2

  19. Vegetative biomass predicts inflorescence production along a CO2 concentration gradient in mesic grassland

    NASA Astrophysics Data System (ADS)

    Fay, P. A.; Collins, H.; Polley, W.

    2016-12-01

    Atmospheric CO2 concentration will likely exceed 500 µL L-1 by 2050, often increasing plant community productivity in part by increasing abundance of species favored by increased CA . Whether increased abundance translates to increased inflorescence production is poorly understood, and is important because it indicates the potential effects of CO2 enrichment on genetic variability and the potential for evolutionary change in future generations. We examined whether the responses of inflorescence production to CO2 enrichment in four C4 grasses and a C3 forb were predicted their vegetative biomass, and by soil moisture, soil nitrogen, or light availability. Inflorescence production was studied in a long-term CO2 concentration gradient spanning pre-industrial to anticipated mid-21st century values (250 - 500 µL L-1) maintained on clay, silty clay and sandy loam soils common in the U.S. Southern Plains. We expected that CO2 enrichment would increase inflorescence production, and more so with higher water, nitrogen, or light availability. However, structural equation modeling revealed that vegetative biomass was the single consistent direct predictor of flowering for all species (p < 0.001). Vegetative biomass increased, decreased, or did not respond to CO2 enrichment depending on the species. For the increasing species Sorghastrum nutans (C4 grass) and Solidago canadensis (C3 forb), direct CO2 effects on flowering were only weakly mediated by indirect effects of soil water content and soil NO3-N availability. For the decreasing species (Bouteloua curtipendula, C4 grass), the negative CO2-flowering relationship was cancelled (p = 0.39) by indirect effects of increased SWC and NO3-N on clay and silty clay soils. For the species with no CO2 response, inflorescence production was predicted only by direct water content (p < 0.0001, Schizachyrium scoparius, C4 grass) or vegetative biomass (p = 0.0009, Tridens albescens, C4 grass) effects. Light availability was unrelated to

  20. Natural high pCO2 increases autotrophy in Anemonia viridis (Anthozoa) as revealed from stable isotope (C, N) analysis

    PubMed Central

    Horwitz, Rael; Borell, Esther M.; Yam, Ruth; Shemesh, Aldo; Fine, Maoz

    2015-01-01

    Contemporary cnidarian-algae symbioses are challenged by increasing CO2 concentrations (ocean warming and acidification) affecting organisms' biological performance. We examined the natural variability of carbon and nitrogen isotopes in the symbiotic sea anemone Anemonia viridis to investigate dietary shifts (autotrophy/heterotrophy) along a natural pCO2 gradient at the island of Vulcano, Italy. δ13C values for both algal symbionts (Symbiodinium) and host tissue of A. viridis became significantly lighter with increasing seawater pCO2. Together with a decrease in the difference between δ13C values of both fractions at the higher pCO2 sites, these results indicate there is a greater net autotrophic input to the A. viridis carbon budget under high pCO2 conditions. δ15N values and C/N ratios did not change in Symbiodinium and host tissue along the pCO2 gradient. Additional physiological parameters revealed anemone protein and Symbiodinium chlorophyll a remained unaltered among sites. Symbiodinium density was similar among sites yet their mitotic index increased in anemones under elevated pCO2. Overall, our findings show that A. viridis is characterized by a higher autotrophic/heterotrophic ratio as pCO2 increases. The unique trophic flexibility of this species may give it a competitive advantage and enable its potential acclimation and ecological success in the future under increased ocean acidification. PMID:25739995

  1. Natural high pCO2 increases autotrophy in Anemonia viridis (Anthozoa) as revealed from stable isotope (C, N) analysis.

    PubMed

    Horwitz, Rael; Borell, Esther M; Yam, Ruth; Shemesh, Aldo; Fine, Maoz

    2015-03-05

    Contemporary cnidarian-algae symbioses are challenged by increasing CO2 concentrations (ocean warming and acidification) affecting organisms' biological performance. We examined the natural variability of carbon and nitrogen isotopes in the symbiotic sea anemone Anemonia viridis to investigate dietary shifts (autotrophy/heterotrophy) along a natural pCO2 gradient at the island of Vulcano, Italy. δ(13)C values for both algal symbionts (Symbiodinium) and host tissue of A. viridis became significantly lighter with increasing seawater pCO2. Together with a decrease in the difference between δ(13)C values of both fractions at the higher pCO2 sites, these results indicate there is a greater net autotrophic input to the A. viridis carbon budget under high pCO2 conditions. δ(15)N values and C/N ratios did not change in Symbiodinium and host tissue along the pCO2 gradient. Additional physiological parameters revealed anemone protein and Symbiodinium chlorophyll a remained unaltered among sites. Symbiodinium density was similar among sites yet their mitotic index increased in anemones under elevated pCO2. Overall, our findings show that A. viridis is characterized by a higher autotrophic/heterotrophic ratio as pCO2 increases. The unique trophic flexibility of this species may give it a competitive advantage and enable its potential acclimation and ecological success in the future under increased ocean acidification.

  2. The CO2 concentrating mechanism and photosynthetic carbon assimilation in limiting CO2 : how Chlamydomonas works against the gradient.

    PubMed

    Wang, Yingjun; Stessman, Dan J; Spalding, Martin H

    2015-05-01

    The CO2 concentrating mechanism (CCM) represents an effective strategy for carbon acquisition that enables microalgae to survive and proliferate when the CO2 concentration limits photosynthesis. The CCM improves photosynthetic performance by raising the CO2 concentration at the site of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), simultaneously enhancing carbon fixation and suppressing photorespiration. Active inorganic carbon (Ci) uptake, Rubisco sequestration and interconversion between different Ci species catalyzed by carbonic anhydrases (CAs) are key components in the CCM, and an array of molecular regulatory elements is present to facilitate the sensing of CO2 availability, to regulate the expression of the CCM and to coordinate interplay between photosynthetic carbon metabolism and other metabolic processes in response to limiting CO2 conditions. This review intends to integrate our current understanding of the eukaryotic algal CCM and its interaction with carbon assimilation, based largely on Chlamydomonas as a model, and to illustrate how Chlamydomonas acclimates to limiting CO2 conditions and how its CCM is regulated. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

  3. Sulfur Isotope Analysis of Minerals and Fluids in a Natural CO2 Reservoir, Green River, Utah

    NASA Astrophysics Data System (ADS)

    Chen, F.; Kampman, N.; Bickle, M. J.; Busch, A.; Turchyn, A. V.

    2013-12-01

    Predicting the security of geological CO2 storage sites requires an understanding of the geochemical behavior of the stored CO2, especially of fluid-rock reactions in reservoirs, caprocks and fault zones. Factors that may influence geochemical behavior include co-injection of sulfur gases along with the CO2, either in acid-gas disposal or as contaminants in CO2 storage sites, and microbial activity, such as bacterial sulfate reduction. The latter may play an important role in buffering the redox chemistry of subsurface fluids, which could affect toxic trace metal mobilization and transport in acidic CO2-rich fluids. These processes involving sulfur are poorly understood. Natural CO2-reservoirs provide natural laboratories, where the flow and reactions of the CO2-charged fluids and the activity of microbial communities are integrated over sufficient time-scales to aid prediction of long-term CO2 storage. This study reports on sulfur isotope analyses of sulfate and sulfide minerals in rock core and in CO2-charged fluids collected from a stacked sequence of natural CO2 reservoirs at Green River, Utah. Scientific drilling adjacent to a CO2-degassing normal fault to a depth of 325m retrieved core and fluid samples from two CO2 reservoirs in the Entrada and Navajo Sandstones and from the intervening Carmel Formation caprock. Fluid samples were collected from CO2-charged springs that discharge through the faults. Sulfur exists as sulfate in the fluids, as sedimentary gypsum beds in the Carmel Formation, as remobilized gypsum veins within a fault damage zone in the Carmel Fm. and in the Entrada Sandstone, and as disseminated pyrite and pyrite-mineralized open fractures throughout the cored interval. We use the stable sulfur (δ34S) and oxygen (δ18OSO4) isotopes of the sulfate, gypsum, and pyrite to understand the source of sulfur in the reservoir as well as the timing of gypsum vein and pyrite formation. The hydration water of the gypsum is also reported to explore the

  4. Estimating alveolar dead space from the arterial to end-tidal CO(2) gradient: a modeling analysis.

    PubMed

    Hardman, Jonathan G; Aitkenhead, Alan R

    2003-12-01

    Using an original, validated, high-fidelity model of pulmonary physiology, we compared the arterial to end-tidal CO(2) gradient divided by the arterial CO(2) tension (Pa-E'CO(2)/PaCO(2)) with alveolar dead space expressed as a fraction of alveolar tidal volume, calculated in the conventional manner using Fowler's technique and the Bohr equation: (VDalv/VTalv)(Bohr-Fowler). We examined the variability of Pa-E'CO(2)/PaCO(2) and of (VDalv/VTalv)(Bohr-Fowler) in the presence of three ventilation-perfusion defects while varying CO(2) production (Vdot;CO(2)), venous admixture, and anatomical dead space fraction (VDanat). Pa-E'CO(2)/PaCO(2) was approximately 59.5% of (VDalv/VTalv)(Bohr-Fowler). During constant alveolar configuration, the factors examined (Vdot;CO(2), pulmonary shunt fraction, and VDanat) each caused variation in (VDalv/VTalv)(Bohr-Fowler) and in Pa-E'CO(2)/PaCO(2). Induced variation was slightly larger for Pa-E'CO(2)/PaCO(2) during changes in VDanat, but was similar during variation of venous admixture and Vdot;CO(2). Pa-E'CO(2)/PaCO(2) may be a useful serial measurement in the critically ill patient because all the necessary data are easily obtained and calculation is significantly simpler than for (VDalv/VTalv)(Bohr-Fowler). Using an original, validated, high-fidelity model of pulmonary physiology, we have demonstrated that the arterial to end-tidal carbon dioxide pressure gradient may be used to robustly and accurately quantify alveolar dead space. After clinical validation, its use could replace that of conventionally calculated alveolar dead space fraction, particularly in the critically ill.

  5. Spectral nature of CO2 adsorption onto meteorites

    NASA Astrophysics Data System (ADS)

    Berlanga, Genesis; Hibbitts, Charles A.; Takir, Driss; Dyar, M. Darby; Sklute, Elizabeth

    2016-12-01

    Previous studies have identified carbon dioxide (CO2) on the surfaces of jovian and Galilean satellites in regions of non-ice material that are too warm for CO2 ice to exist. CO2 ice would quickly sublimate if not retained by a less-volatile material. To ascertain what non-ice species may be responsible for stabilizing this CO2, we performed CO2 gas adsorption experiments on thirteen powdered CM, CI, and CV carbonaceous chondrite meteorites. Reflectance spectra of the ν3 feature associated with adsorbed CO2 near 4.27 μm were recorded. Results show that many meteorites adsorbed some amount of CO2, as evidenced by an absorption feature that was stable over several hours at ultra-high vacuum (UHV) and high vacuum, (1.0 × 10-8 and 1.0 × 10-7Torr, respectively). Ivuna, the only CI chondrite studied, adsorbed significantly more CO2 than the others. We found that CO2 abundance did not vary with 'water' abundance, organics, or carbonates as inferred from the area of the 3-μm band, the 3.2-3.4 μm C-H feature, and the ∼3.8-μm band respectively, but did correlate with hydrous/anhydrous phyllosilicate ratios. Furthermore, we did not observe CO2 ice because the position of the CO2 feature was generally shifted 3-10 nm from that of the 4.27 μm absorption characteristic of ice. The strongest compositional relationship observed was a possible affinity of CO2 for total FeO abundance and complex clay minerals, which make up the bulk of the CI chondrite matrix. This finding implies that the most primitive refractory materials in the Solar System may also act as reservoirs of CO2, and possibly other volatiles, delivering them to parts of the Solar System where their ices would not be stable.

  6. Aqueous Carbonation of Natural Brucite for CO2 Sequestration

    NASA Astrophysics Data System (ADS)

    Zhao, L.; Sang, L.; Chen, J.; Ji, J.; Teng, H.

    2009-12-01

    Experimental study is carried out at conditions of room temperature and moderate CO2 pressure to examine the carbonation reaction of natural brucite in aqueous environment. Two sets of initial conditions are examined, one is brucite in pure water, and the other is in 1% HCl. Time-dependent XRD analysis shows that carbon fixation process begins within 30 min of the experiments irrespective of the original makeup of the slurry. Ensuing measurements by XRD and FT-IR reveal that nesquehonite (> 78%) is by far the dominant C-bearing species in the carbonate mineral product assembly. Minor product components observed in water are basic magnesium carbonate hydromagnesite and dypingite; when HCl is added in the starting slurry, chloride-bearing artinite replaces hydromagnesite. However, thermodynamic calculation suggests that the assembly of such composition is most likely a kinetically favored product at the experimental conditions which are more strongly saturated with respect to hydromagnesite and magnesite than to nesquehonite. A pseudo first-order rate law is found to best describe the time-dependent measurements for both water and HCl experiments. Moreover, fitting the rate expression to the experimental data yields a higher rate constant for the experiments performed in HCl solutions. The faster kinetics relative to that in water implies that the carbonation reaction may be a multi-stepped process, involving first the dissolution of brucite and CO2 to generate Mg2+ and CO32-, followed by precipitation of magnesium carbonate phases from aqueous solutions. This leads to our proposition that direct heterogeneous reaction between hydrated CO2 and solid phase of Mg(OH)2 is probably not the pathway for the overall carbonation process. Assuming the upper limit of carbon content Cmax = 8.7% (based upon that of nesquehonite), measured total carbon in the product Ctot show a carbonation rate of 83.9% and 94.3% for brucite in HCl and DDW at the end of 2.5 hr experiments

  7. Atmospheric CO2 and soil extracellular enzyme activity: A meta-analysis and CO2 gradient experiment

    USDA-ARS?s Scientific Manuscript database

    Rising atmospheric CO2 concentrations may alter carbon and nutrient cycling and microbial processes in terrestrial ecosystems. One of the primary ways that microbes interact with soil organic matter is through the production of extracellular enzymes, which break down large, complex organic molecules...

  8. Transient nature of CO2 fertilization in arctic tundra

    Treesearch

    Walter C. Oechel; Sid Cowles; Nancy Grulke; Steven J. Hastings; Bill Lawrence; Tom Prudhomme; George Riechers; Boyd Strain; David Tissue; George. Vourlitis

    1994-01-01

    There has been much debate about the effect of increased atmospheric CO2 concentrations on plant net primary production1,3 and on net ecosystem CO2 flux3–10. Apparently conflicting experimental findings could be the result of differences in genetic potential11–15...

  9. Reactive fluid transport in CO2 reservoir caprocks: constraints from scientific drilling of a natural CO2 reservoir

    NASA Astrophysics Data System (ADS)

    Kampman, N.; Bickle, M. J.; Bertier, P.; Busch, A.; Chapman, H.; Evans, J. P.; Graham, C.; Harrington, J.; Maskell, A.

    2013-12-01

    The long-term performance of reservoir caprocks in geological CO2 storage sites remains uncertain due to the poorly constrained nature of field-scale fluid-mineral reaction kinetics and CO2 transport processes in low permeability rocks. Predicting the nature, rates and impacts of CO2 penetration into the caprocks from numerical modelling studies maybe undermined by their reliance on laboratory derived reaction kinetics from short-term experiments, and the complexity of the coupled reactive transport processes at the nano- and micro-scale. We report here on the early results from scientific drilling and laboratory analysis of the caprocks of a stacked sequence of natural CO2 reservoir at Green River, Utah. In summer 2012, diamond drilling to a depth of 325m, adjacent to a CO2 degassing normal fault recovered core from two major CO2 reservoirs in the Entrada and Navajo Sandstones and from the intervening Carmel Formation regional caprock. In-situ pH, CO2 concentrations and fluid element and isotope geochemistry were determined from wireline downhole sampling of pressurized fluids from the reservoirs. The fluid geochemistry provides important constraints on reservoir filling by flow of CO2-charged brines through the fault damage zone, macro-scale fluid flow in the reservoirs and the state of fluid-mineral thermodynamic disequilibrium from which the nature of the fluid-mineral reactions can be interpreted. Mineralogical, geochemical and petrophysical profiles through portions of the caprocks in contact with the CO2-charged reservoirs have been used to constrain the nature and penetration depths of the CO2-promoted fluid-mineral reaction fronts. The major reactions are the dissolution of diagenetic dolomite cements and hematite grain coatings which generate porosity in the caprocks. Analysis of the generated pore structure from a variety of analytical techniques will be discussed. Stable C- and O-isotopic shifts in the composition of the carbonate cements record their

  10. Spectral nature of CO2 adsorption onto meteorites

    USGS Publications Warehouse

    Berlanga, Genesis; Hibbitts, Charles A; Takir, Driss; Dyar, Draby M; Elizabeth Sklute,

    2016-01-01

    Previous studies have identified carbon dioxide (CO2) on the surfaces of Jovian and Galilean satellites in regions of non-ice material that are too warm for CO2 ice to exist. CO2 ice would quickly sublimate if not retained by a less-volatile material. To ascertain what non-ice species may be responsible for stabilizing this CO2, we performed CO2 gas adsorption experiments on thirteen powdered CM, CI, and CV carbonaceous chondrite meteorites. Reflectance spectra of the ν3 feature associated with adsorbed CO2 near 4.27 μm were recorded. Results show that many meteorites adsorbed some amount of CO2, as evidenced by an absorption feature that was stable over several hours at ultra-high vacuum (UHV) and high vacuum, (1.0×10−8 and 1.0×10−7 Torr, respectively). Ivuna, the only CI chondrite studied, adsorbed significantly more CO2 than the others. We found that CO2 abundance did not vary with ‘water’ abundance, organics, or carbonates as inferred from the area of the 3-μm band, the 3.2-3.4 μm C-H feature, and the ∼3.8-μm band respectively, but did correlate with hydrous/anhydrous phyllosilicate ratios. Furthermore, we did not observe CO2 ice because the position of the CO2 feature was generally shifted 3-10 nm from that of the 4.27 μm absorption characteristic of ice. The strongest compositional relationship observed was a possible affinity of CO2 for total FeO abundance and complex clay minerals, which make up the bulk of the CI chondrite matrix. This finding implies that the most primitive refractory materials in the Solar System may also act as reservoirs of CO2, and possibly other volatiles, delivering them to parts of the Solar System where their ices would not be stable.

  11. Viability and adaptation potential of indigenous microorganisms from natural gas field fluids in high pressure incubations with supercritical CO2.

    PubMed

    Frerichs, Janin; Rakoczy, Jana; Ostertag-Henning, Christian; Krüger, Martin

    2014-01-21

    Carbon Capture and Storage (CCS) is currently under debate as large-scale solution to globally reduce emissions of the greenhouse gas CO2. Depleted gas or oil reservoirs and saline aquifers are considered as suitable reservoirs providing sufficient storage capacity. We investigated the influence of high CO2 concentrations on the indigenous bacterial population in the saline formation fluids of a natural gas field. Bacterial community changes were closely examined at elevated CO2 concentrations under near in situ pressures and temperatures. Conditions in the high pressure reactor systems simulated reservoir fluids i) close to the CO2 injection point, i.e. saturated with CO2, and ii) at the outer boundaries of the CO2 dissolution gradient. During the incubations with CO2, total cell numbers remained relatively stable, but no microbial sulfate reduction activity was detected. After CO2 release and subsequent transfer of the fluids, an actively sulfate-respiring community was re-established. The predominance of spore-forming Clostridiales provided evidence for the resilience of this taxon against the bactericidal effects of supercritical (sc)CO2. To ensure the long-term safety and injectivity, the viability of fermentative and sulfate-reducing bacteria has to be considered in the selection, design, and operation of CCS sites.

  12. 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 CO2 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 CO2 dissolves porous media homogeneously, leading to large breakthrough porosity. In contrast, solutions without CO2 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 CO2 increases the reactive subvolume of porous media and reduces the amount of solid residual before reactive fluid can be fully channelized. Consequently, dissolved CO2 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.

  13. Interfacial properties of water/CO2: a comprehensive description through a Gradient Theory-SAFT-VR Mie approach.

    PubMed

    Lafitte, Thomas; Mendiboure, Bruno; Piñeiro, Manuel M; Bessières, David; Miqueu, Christelle

    2010-09-02

    The Gradient Theory of fluid interfaces is for the first time combined with the SAFT-VR Mie EOS to model the interfacial properties of the water/CO(2) mixture. As a preliminary test of the performance of the coupling between both theories, liquid-vapor interfacial properties of pure water have been determined. The complex temperature dependence of the surface tension of water can be accurately reproduced, and the interfacial thickness is in good agreement with experimental data and simulation results. The water/CO(2) mixture presents several types of interfaces as the liquid water may be in contact with gaseous, liquid, or supercritical CO(2). Here, the interfacial tension of the water/CO(2) mixture is modeled accurately by the gradient theory with a unique value of the crossed influence parameter over a broad range of thermodynamic conditions. The interfacial density profiles show a systematic adsorption of CO(2) in the interface. Moreover, when approaching the saturation pressure of CO(2), a prewetting transition is highlighted. The adsorption isotherm of CO(2) is computed as well in the case of a gas/liquid interface and compared with experimental data. The good agreement obtained is an indirect proof of the consistency of interfacial density profiles computed with the gradient theory for this mixture and confirms that the gradient theory is suitable and reliable to describe the microstructure of complex fluid interfaces.

  14. Natural CO2 accumulations in the western Williston Basin: A mineralogical analog for CO2 injection at the Weyburn site

    DOE PAGES

    Ryerson, F. J.; Lake, John; Whittaker, Steven; ...

    2013-01-17

    The Devonian carbonates of the Duperow Formation on the western flank of the Williston Basin in southwest Saskatchewan contain natural accumulations of CO2, and may have done so for as long as 50 million years. These carbonate sediments are characterized by a succession of carbonate cycles capped by anhydrite-rich evaporites that are thought to act as seals to fluid migration. The Weyburn CO2 injection site lies 400 km to the east in a series of Mississippian carbonates that were deposited in a similar depositional environment. That long-term isolation of natural CO2 can be accomplished within carbonate strata has motivated themore » investigation of the Duperow rocks as a potential natural analog for storage of anthropogenic CO2 in carbonate lithologies. For the Duperow strata to represent a legitimate analog for Midale injection and storage, the similarity in lithofacies, whole rock compositions, mineral compositions and porosity with the Midale Beds must be established. Here we compare lithofacies, whole rock compositions, mineralogy and mineral compositions from both locales. The major mineral phases at both locales are calcite, dolomite and anhydrite. In addition, accessory pyrite, fluorite, quartz and celestine (strontium sulfate) are also observed. Dawsonite, a potential CO2-trapping mineral, is not observed within the CO2-bearing horizons of the Duperow Formation, however. The distribution of porosity in the Midale Vuggy units is similar to that of the Duperow Formation, but the Marly units of the Midale have significantly higher porosity. The Duperow Formation is topped by the Dinesmore evaporite that is rich in anhydrite, and often contains authigenic K-feldspar. The chemistry of dolomite and calcite from the two localities also overlaps. Silicate minerals are in low abundance (<3%) within the analyzed Duperow samples, with quartz and K-feldspar the only silicates observed petrographically or in X-ray diffraction patterns. The Midale Beds contain

  15. The doubled CO2 climate - Impact of the sea surface temperature gradient

    NASA Technical Reports Server (NTRS)

    Rind, David

    1987-01-01

    The Goddard Institute for Space Studies (GISS) GCM of Hansen et al. (1983) was run, with 4 deg x 5 deg resolution, with doubled CO2 and two sets of sea surface temperature gradient distributions. One set was derived from the equilibrium doubled CO2 run of the 8 deg x 10 deg GISS GCM, with minimal high latitude amplification. The other set resembled closely the GFDL model results, with greater amplification. Both experiments had the same global mean surface air temperature change. The two experiments were often found to produce substantially different climate characteristics. With reduced high latitude amplification (set one), and thus, more equatorial warming, there was a greater increase in specific humidity and the greenhouse capacity of the atmosphere, resulting in a warmer atmosphere in general. Features such as the low-latitude precipitation, Hadley cell intensity, jet stream magnitude, and atmospheric energy transports all increased in comparison with the control run. In contrast, these features all decreased in the experiment with greater high latitude amplification (set two).

  16. The doubled CO2 climate - Impact of the sea surface temperature gradient

    NASA Technical Reports Server (NTRS)

    Rind, David

    1987-01-01

    The Goddard Institute for Space Studies (GISS) GCM of Hansen et al. (1983) was run, with 4 deg x 5 deg resolution, with doubled CO2 and two sets of sea surface temperature gradient distributions. One set was derived from the equilibrium doubled CO2 run of the 8 deg x 10 deg GISS GCM, with minimal high latitude amplification. The other set resembled closely the GFDL model results, with greater amplification. Both experiments had the same global mean surface air temperature change. The two experiments were often found to produce substantially different climate characteristics. With reduced high latitude amplification (set one), and thus, more equatorial warming, there was a greater increase in specific humidity and the greenhouse capacity of the atmosphere, resulting in a warmer atmosphere in general. Features such as the low-latitude precipitation, Hadley cell intensity, jet stream magnitude, and atmospheric energy transports all increased in comparison with the control run. In contrast, these features all decreased in the experiment with greater high latitude amplification (set two).

  17. Both experimental study and numerical modelling of the effect of temperature gradient on CO2 injection

    NASA Astrophysics Data System (ADS)

    Corvisier, J.; Lagneau, V.; Jobard, E.; Sterpenich, J.; Pironon, J.

    2010-12-01

    to a more important carbonates dissolution, thus to increases of CO2 fugacity and consequently of the global pressure. Furthermore, the calcium content tends to be greater in this cold-dissolution zone then Ca diffuses towards the hotter zone locally and it implies calcite precipitation. As evidence of this phenomenon, plugs, related to massive calcite precipitation, are observed in these regions and newly crystallized calcite can be seen on SEM images. In order to clearly understand the reasons of the observed behaviour, numerical computations performed with the reaction-transport code HYTEC have to be run. Several scenarios can thus be simulated to check various assumptions. Firstly, different initial repartitions of the CO2 can be tested: in some kind of reservoir in the cold/injection zone or everywhere in the autoclave (due to high initial pressure gradient). Secondly, the competition between the implied processes, their respective kinetics and their temperature dependance can be assessed too: thermodynamics and/or kinetics of chemical reactions and transport kinetics (diffusion). Modeling becomes then of great help to interpret the experimental results and even to better design the evolution of the experimental set-up.

  18. The nature of the CO2- radical anion in water

    NASA Astrophysics Data System (ADS)

    Janik, Ireneusz; Tripathi, G. N. R.

    2016-04-01

    The reductive conversion of CO2 into industrial products (e.g., oxalic acid, formic acid, methanol) can occur via aqueous CO2- as a transient intermediate. While the formation, structure, and reaction pathways of this radical anion have been modelled for decades using various spectroscopic and theoretical approaches, we present here, for the first time, a vibrational spectroscopic investigation in liquid water, using pulse radiolysis time-resolved resonance Raman spectroscopy for its preparation and observation. Excitation of the radical in resonance with its 235 nm absorption displays a transient Raman band at 1298 cm-1, attributed to the symmetric CO stretch, which is at ˜45 cm-1 higher frequency than in inert matrices. Isotopic substitution at C (13CO2-) shifts the frequency downwards by 22 cm-1, which confirms its origin and the assignment. A Raman band of moderate intensity compared to the stronger 1298 cm-1 band also appears at 742 cm-1 and is assignable to the OCO bending mode. A reasonable resonance enhancement of this mode is possible only in a bent CO2-(C2v/Cs) geometry. These resonance Raman features suggest a strong solute-solvent interaction, the water molecules acting as constituents of the radical structure, rather than exerting a minor solvent perturbation. However, there is no evidence of the non-equivalence (Cs) of the two CO bonds. A surprising resonance Raman feature is the lack of overtones of the symmetric CO stretch, which we interpret due to the detachment of the electron from the CO2- moiety towards the solvation shell. Electron detachment occurs at the energies of 0.28 ± 0.03 eV or higher with respect to the zero point energy of the ground electronic state. The issue of acid-base equilibrium of the radical, which has been in contention for decades, as reflected in a wide variation in the reported pKa (-0.2 to 3.9), has been resolved. A value of 3.4 ± 0.2 measured in this work is consistent with the vibrational properties, bond structure

  19. Deep microbial life in the Altmark natural gas reservoir: baseline characterization prior CO2 injection

    NASA Astrophysics Data System (ADS)

    Morozova, Daria; Shaheed, Mina; Vieth, Andrea; Krüger, Martin; Kock, Dagmar; Würdemann, Hilke

    2010-05-01

    Within the framework of the CLEAN project (CO2 Largescale Enhanced gas recovery in the Altmark Natural gas field) technical basics with special emphasis on process monitoring are explored by injecting CO2 into a gas reservoir. Our study focuses on the investigation of the in-situ microbial community of the Rotliegend natural gas reservoir in the Altmark, located south of the city Salzwedel, Germany. In order to characterize the microbial life in the extreme habitat we aim to localize and identify microbes including their metabolism influencing the creation and dissolution of minerals. The ability of microorganisms to speed up dissolution and formation of minerals might result in changes of the local permeability and the long-term safety of CO2 storage. However, geology, structure and chemistry of the reservoir rock and the cap rock as well as interaction with saline formation water and natural gases and the injected CO2 affect the microbial community composition and activity. The reservoir located at the depth of about 3500m, is characterised by high salinity fluid and temperatures up to 127° C. It represents an extreme environment for microbial life and therefore the main focus is on hyperthermophilic, halophilic anaerobic microorganisms. In consequence of the injection of large amounts of CO2 in the course of a commercial EGR (Enhanced Gas Recovery) the environmental conditions (e.g. pH, temperature, pressure and solubility of minerals) for the autochthonous microorganisms will change. Genetic profiling of amplified 16S rRNA genes are applied for detecting structural changes in the community by using PCR- SSCP (PCR-Single-Strand-Conformation Polymorphism) and DGGE (Denaturing Gradient Gel Electrophoresis). First results of the baseline survey indicate the presence of microorganisms similar to representatives from other saline, hot, anoxic, deep environments. However, due to the hypersaline and hyperthermophilic reservoir conditions, cell numbers are low, so that

  20. Altered brain ion gradients following compensation for elevated CO2 are linked to behavioural alterations in a coral reef fish.

    PubMed

    Heuer, R M; Welch, M J; Rummer, J L; Munday, P L; Grosell, M

    2016-09-13

    Neurosensory and behavioural disruptions are some of the most consistently reported responses upon exposure to ocean acidification-relevant CO2 levels, especially in coral reef fishes. The underlying cause of these disruptions is thought to be altered current across the GABAA receptor in neuronal cells due to changes in ion gradients (HCO3(-) and/or Cl(-)) that occur in the body following compensation for elevated ambient CO2. Despite these widely-documented behavioural disruptions, the present study is the first to pair a behavioural assay with measurements of relevant intracellular and extracellular acid-base parameters in a coral reef fish exposed to elevated CO2. Spiny damselfish (Acanthochromis polyacanthus) exposed to 1900 μatm CO2 for 4 days exhibited significantly increased intracellular and extracellular HCO3(-) concentrations and elevated brain pHi compared to control fish, providing evidence of CO2 compensation. As expected, high CO2 exposed damselfish spent significantly more time in a chemical alarm cue (CAC) than control fish, supporting a potential link between behavioural disruption and CO2 compensation. Using HCO3(-) measurements from the damselfish, the reversal potential for GABAA (EGABA) was calculated, illustrating that biophysical properties of the brain during CO2 compensation could change GABAA receptor function and account for the behavioural disturbances noted during exposure to elevated CO2.

  1. Altered brain ion gradients following compensation for elevated CO2 are linked to behavioural alterations in a coral reef fish

    PubMed Central

    Heuer, R. M.; Welch, M. J.; Rummer, J. L.; Munday, P. L.; Grosell, M.

    2016-01-01

    Neurosensory and behavioural disruptions are some of the most consistently reported responses upon exposure to ocean acidification-relevant CO2 levels, especially in coral reef fishes. The underlying cause of these disruptions is thought to be altered current across the GABAA receptor in neuronal cells due to changes in ion gradients (HCO3− and/or Cl−) that occur in the body following compensation for elevated ambient CO2. Despite these widely-documented behavioural disruptions, the present study is the first to pair a behavioural assay with measurements of relevant intracellular and extracellular acid-base parameters in a coral reef fish exposed to elevated CO2. Spiny damselfish (Acanthochromis polyacanthus) exposed to 1900 μatm CO2 for 4 days exhibited significantly increased intracellular and extracellular HCO3− concentrations and elevated brain pHi compared to control fish, providing evidence of CO2 compensation. As expected, high CO2 exposed damselfish spent significantly more time in a chemical alarm cue (CAC) than control fish, supporting a potential link between behavioural disruption and CO2 compensation. Using HCO3− measurements from the damselfish, the reversal potential for GABAA (EGABA) was calculated, illustrating that biophysical properties of the brain during CO2 compensation could change GABAA receptor function and account for the behavioural disturbances noted during exposure to elevated CO2. PMID:27620837

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

    PubMed

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

    2015-05-01

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

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

    PubMed Central

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

    2015-01-01

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

  4. CO2 adsorption and separation from natural gason phosphorene surface: Combining DFT and GCMC calculations

    NASA Astrophysics Data System (ADS)

    Zhang, Yayun; Liu, Chao; Hao, Feng; Xiao, Hang; Zhang, Shiwei; Chen, Xi

    2017-03-01

    We have examined the performance of phosphorene-based material, phosphorene slit pores (PSP), in CO2 adsorption and separation from natural gas by using Density Function Theory (DFT) calculation and Grand Canonical Monte Carlo (GCMC) simulations. First, the adsorption of CH4 and CO2molecules on phosphorene sheet were conducted by DFT study. Then, adsorption performances of natural gas components as well as their binary CO2/CH4 gas mixture were investigated at 300 K with the pressure up to 3.0 MPa. The effects of slit pore width, H, and mole ratio of CO2/CH4in the gas phase on the separation of CO2 from mixtures of CO2/CH4 were also investigated. Our DFT calculation results show that the CO2 moleculehas higher adsorption energy than that of CH4, which implies that it can be easily adsorbed to the phosphorene surface than CH4. Detailed GCMC simulations reveal that the phosphorene slit pore has a high performance in separating CO2fromnature gas and achieves the highest gas selectivity at H = 1.0 nm at pressures lower than 0.1 MPa. Moreover, the selectivity of CO2 overCO2/CH4gas mixture increases with increasing the mole ratio of CO2/CH4due to the enhanced adsorbate-adsorbent interactions for the favorable component. Therefore, it is suggested that the phosphorene is a promising candidate for natural gas purification and possessing practical potential applications in gas adsorption.

  5. The soil microbiome at the Gi-FACE experiment responds to a moisture gradient but not to CO2 enrichment.

    PubMed

    de Menezes, Alexandre B; Müller, Christoph; Clipson, Nicholas; Doyle, Evelyn

    2016-09-01

    The soil bacterial community at the Giessen free-air CO2 enrichment (Gi-FACE) experiment was analysed by tag sequencing of the 16S rRNA gene. No substantial effects of CO2 levels on bacterial community composition were detected. However, the soil moisture gradient at Gi-FACE had a significant effect on bacterial community composition. Different groups within the Acidobacteria and Verrucomicrobia phyla were affected differently by soil moisture content. These results suggest that modest increases in atmospheric CO2 may cause only minor changes in soil bacterial community composition and indicate that the functional responses of the soil community to CO2 enrichment previously reported at Gi-FACE are due to factors other than changes in bacterial community composition. The effects of the moisture gradient revealed new information about the relationships between poorly known Acidobacteria and Verrucomicrobia and soil moisture content. This study contrasts with the relatively small number of other temperate grassland free-air CO2 enrichment microbiome studies in the use of moderate CO2 enrichment and the resulting minor changes in the soil microbiome. Thus, it will facilitate the development of further climate change mitigation studies. In addition, the moisture gradient found at Gi-FACE contributes new knowledge in soil microbial ecology, particularly regarding the abundance and moisture relationships of the soil Verrucomicrobia.

  6. Solubility trapping in formation water as dominant CO(2) sink in natural gas fields.

    PubMed

    Gilfillan, Stuart M V; Lollar, Barbara Sherwood; Holland, Greg; Blagburn, Dave; Stevens, Scott; Schoell, Martin; Cassidy, Martin; Ding, Zhenju; Zhou, Zheng; Lacrampe-Couloume, Georges; Ballentine, Chris J

    2009-04-02

    Injecting CO(2) into deep geological strata is proposed as a safe and economically favourable means of storing CO(2) captured from industrial point sources. It is difficult, however, to assess the long-term consequences of CO(2) flooding in the subsurface from decadal observations of existing disposal sites. Both the site design and long-term safety modelling critically depend on how and where CO(2) will be stored in the site over its lifetime. Within a geological storage site, the injected CO(2) can dissolve in solution or precipitate as carbonate minerals. Here we identify and quantify the principal mechanism of CO(2) fluid phase removal in nine natural gas fields in North America, China and Europe, using noble gas and carbon isotope tracers. The natural gas fields investigated in our study are dominated by a CO(2) phase and provide a natural analogue for assessing the geological storage of anthropogenic CO(2) over millennial timescales. We find that in seven gas fields with siliciclastic or carbonate-dominated reservoir lithologies, dissolution in formation water at a pH of 5-5.8 is the sole major sink for CO(2). In two fields with siliciclastic reservoir lithologies, some CO(2) loss through precipitation as carbonate minerals cannot be ruled out, but can account for a maximum of 18 per cent of the loss of emplaced CO(2). In view of our findings that geological mineral fixation is a minor CO(2) trapping mechanism in natural gas fields, we suggest that long-term anthropogenic CO(2) storage models in similar geological systems should focus on the potential mobility of CO(2) dissolved in water.

  7. Host Plant Physiology and Mycorrhizal Functioning Shift across a Glacial through Future [CO2] Gradient1[OPEN

    PubMed Central

    Mullinix, George W.R.; Ward, Joy K.

    2016-01-01

    Rising atmospheric carbon dioxide concentration ([CO2]) may modulate the functioning of mycorrhizal associations by altering the relative degree of nutrient and carbohydrate limitations in plants. To test this, we grew Taraxacum ceratophorum and Taraxacum officinale (native and exotic dandelions) with and without mycorrhizal fungi across a broad [CO2] gradient (180–1,000 µL L−1). Differential plant growth rates and vegetative plasticity were hypothesized to drive species-specific responses to [CO2] and arbuscular mycorrhizal fungi. To evaluate [CO2] effects on mycorrhizal functioning, we calculated response ratios based on the relative biomass of mycorrhizal (MBio) and nonmycorrhizal (NMBio) plants (RBio = [MBio − NMBio]/NMBio). We then assessed linkages between RBio and host physiology, fungal growth, and biomass allocation using structural equation modeling. For T. officinale, RBio increased with rising [CO2], shifting from negative to positive values at 700 µL L−1. [CO2] and mycorrhizal effects on photosynthesis and leaf growth rates drove shifts in RBio in this species. For T. ceratophorum, RBio increased from 180 to 390 µL L−1 and further increases in [CO2] caused RBio to shift from positive to negative values. [CO2] and fungal effects on plant growth and carbon sink strength were correlated with shifts in RBio in this species. Overall, we show that rising [CO2] significantly altered the functioning of mycorrhizal associations. These symbioses became more beneficial with rising [CO2], but nonlinear effects may limit plant responses to mycorrhizal fungi under future [CO2]. The magnitude and mechanisms driving mycorrhizal-CO2 responses reflected species-specific differences in growth rate and vegetative plasticity, indicating that these traits may provide a framework for predicting mycorrhizal responses to global change. PMID:27573369

  8. Assessing the health risks of natural CO2 seeps in Italy.

    PubMed

    Roberts, Jennifer J; Wood, Rachel A; Haszeldine, R Stuart

    2011-10-04

    Industrialized societies which continue to use fossil fuel energy sources are considering adoption of Carbon Capture and Storage (CCS) technology to meet carbon emission reduction targets. Deep geological storage of CO(2) onshore faces opposition regarding potential health effects of CO(2) leakage from storage sites. There is no experience of commercial scale CCS with which to verify predicted risks of engineered storage failure. Studying risk from natural CO(2) seeps can guide assessment of potential health risks from leaking onshore CO(2) stores. Italy and Sicily are regions of intense natural CO(2) degassing from surface seeps. These seeps exhibit a variety of expressions, characteristics (e.g., temperature/flux), and location environments. Here we quantify historical fatalities from CO(2) poisoning using a database of 286 natural CO(2) seeps in Italy and Sicily. We find that risk of human death is strongly influenced by seep surface expression, local conditions (e.g., topography and wind speed), CO(2) flux, and human behavior. Risk of accidental human death from these CO(2) seeps is calculated to be 10-8 year-1 to the exposed population. This value is significantly lower than that of many socially accepted risks. Seepage from future storage sites is modeled to be less that Italian natural flux rates. With appropriate hazard management, health risks from unplanned seepage at onshore storage sites can be adequately minimized.

  9. Assessing the health risks of natural CO2 seeps in Italy

    PubMed Central

    Roberts, Jennifer J.; Wood, Rachel A.; Haszeldine, R. Stuart

    2011-01-01

    Industrialized societies which continue to use fossil fuel energy sources are considering adoption of Carbon Capture and Storage (CCS) technology to meet carbon emission reduction targets. Deep geological storage of CO2 onshore faces opposition regarding potential health effects of CO2 leakage from storage sites. There is no experience of commercial scale CCS with which to verify predicted risks of engineered storage failure. Studying risk from natural CO2 seeps can guide assessment of potential health risks from leaking onshore CO2 stores. Italy and Sicily are regions of intense natural CO2 degassing from surface seeps. These seeps exhibit a variety of expressions, characteristics (e.g., temperature/flux), and location environments. Here we quantify historical fatalities from CO2 poisoning using a database of 286 natural CO2 seeps in Italy and Sicily. We find that risk of human death is strongly influenced by seep surface expression, local conditions (e.g., topography and wind speed), CO2 flux, and human behavior. Risk of accidental human death from these CO2 seeps is calculated to be 10-8 year-1 to the exposed population. This value is significantly lower than that of many socially accepted risks. Seepage from future storage sites is modeled to be less that Italian natural flux rates. With appropriate hazard management, health risks from unplanned seepage at onshore storage sites can be adequately minimized. PMID:21911398

  10. Assessing the health risks of natural CO2 seeps in Italy

    SciTech Connect

    Roberts, J.J.; Wood, R.A.; Haszeldine, R.S.

    2011-10-04

    Industrialized societies which continue to use fossil fuel energy sources are considering adoption of Carbon Capture and Storage (CCS) technology to meet carbon emission reduction targets. Deep geological storage of CO2 onshore faces opposition regarding potential health effects of CO2 leakage from storage sites. There is no experience of commercial scale CCS with which to verify predicted risks of engineered storage failure. Studying risk from natural CO2 seeps can guide assessment of potential health risks from leaking onshore CO2 stores. Italy and Sicily are regions of intense natural CO2 degassing from surface seeps. These seeps exhibit a variety of expressions, characteristics (e.g., temperature/ flux), and location environments. Here we quantify historical fatalities from CO2 poisoning using a database of 286 natural CO2 seeps in Italy and Sicily. We find that risk of human death is strongly influenced by seep surface expression, local conditions (e.g., topography and wind speed), CO2 flux, and human behavior. Risk of accidental human death from these CO2 seeps is calculated to be 10-8 year-1 to the exposed population. This value is significantly lower than that of many socially accepted risks. Seepage from future storage sites is modeled to be less than Italian natural flux rates. With appropriate hazard management, health risks from unplanned seepage at onshore storage sites can be adequately minimized.

  11. Assessing the health risks of natural CO2 seeps in Italy

    NASA Astrophysics Data System (ADS)

    Roberts, Jennifer J.; Wood, Rachel A.; Haszeldine, R. Stuart

    2011-10-01

    Industrialized societies which continue to use fossil fuel energy sources are considering adoption of Carbon Capture and Storage (CCS) technology to meet carbon emission reduction targets. Deep geological storage of CO2 onshore faces opposition regarding potential health effects of CO2 leakage from storage sites. There is no experience of commercial scale CCS with which to verify predicted risks of engineered storage failure. Studying risk from natural CO2 seeps can guide assessment of potential health risks from leaking onshore CO2 stores. Italy and Sicily are regions of intense natural CO2 degassing from surface seeps. These seeps exhibit a variety of expressions, characteristics (e.g., temperature/flux), and location environments. Here we quantify historical fatalities from CO2 poisoning using a database of 286 natural CO2 seeps in Italy and Sicily. We find that risk of human death is strongly influenced by seep surface expression, local conditions (e.g., topography and wind speed), CO2 flux, and human behavior. Risk of accidental human death from these CO2 seeps is calculated to be 10-8 year-1 to the exposed population. This value is significantly lower than that of many socially accepted risks. Seepage from future storage sites is modeled to be less that Italian natural flux rates. With appropriate hazard management, health risks from unplanned seepage at onshore storage sites can be adequately minimized.

  12. Constraints on the magnitude and rate of CO2 dissolution at Bravo Dome natural gas field

    DOE PAGES

    Sathaye, Kiran J.; Hesse, Marc A.; Cassidy, M.; ...

    2014-10-13

    The injection of carbon dioxide (CO2) captured at large point sources into deep saline aquifers can significantly reduce anthropogenic CO2 emissions from fossil fuels. Dissolution of the injected CO2 into the formation brine is a trapping mechanism that helps to ensure the long-term security of geological CO2 storage. We use thermochronology to estimate the timing of CO2 emplacement at Bravo Dome, a large natural CO2 field at a depth of 700 m in New Mexico. Together with estimates of the total mass loss from the field we present, to our knowledge, the first constraints on the magnitude, mechanisms, and ratesmore » of CO2 dissolution on millennial timescales. Apatite (U-Th)/He thermochronology records heating of the Bravo Dome reservoir due to the emplacement of hot volcanic gases 1.2–1.5 Ma. The CO2 accumulation is therefore significantly older than previous estimates of 10 ka, which demonstrates that safe long-term geological CO2 storage is possible. Here, integrating geophysical and geochemical data, we estimate that 1.3 Gt CO2 are currently stored at Bravo Dome, but that only 22% of the emplaced CO2 has dissolved into the brine over 1.2 My. Roughly 40% of the dissolution occurred during the emplacement. The CO2 dissolved after emplacement exceeds the amount expected from diffusion and provides field evidence for convective dissolution with a rate of 0.1 g/(m2y). Finally, the similarity between Bravo Dome and major US saline aquifers suggests that significant amounts of CO2 are likely to dissolve during injection at US storage sites, but that convective dissolution is unlikely to trap all injected CO2 on the 10-ky timescale typically considered for storage projects.« less

  13. Constraints on the magnitude and rate of CO2 dissolution at Bravo Dome natural gas field.

    PubMed

    Sathaye, Kiran J; Hesse, Marc A; Cassidy, Martin; Stockli, Daniel F

    2014-10-28

    The injection of carbon dioxide (CO2) captured at large point sources into deep saline aquifers can significantly reduce anthropogenic CO2 emissions from fossil fuels. Dissolution of the injected CO2 into the formation brine is a trapping mechanism that helps to ensure the long-term security of geological CO2 storage. We use thermochronology to estimate the timing of CO2 emplacement at Bravo Dome, a large natural CO2 field at a depth of 700 m in New Mexico. Together with estimates of the total mass loss from the field we present, to our knowledge, the first constraints on the magnitude, mechanisms, and rates of CO2 dissolution on millennial timescales. Apatite (U-Th)/He thermochronology records heating of the Bravo Dome reservoir due to the emplacement of hot volcanic gases 1.2-1.5 Ma. The CO2 accumulation is therefore significantly older than previous estimates of 10 ka, which demonstrates that safe long-term geological CO2 storage is possible. Integrating geophysical and geochemical data, we estimate that 1.3 Gt CO2 are currently stored at Bravo Dome, but that only 22% of the emplaced CO2 has dissolved into the brine over 1.2 My. Roughly 40% of the dissolution occurred during the emplacement. The CO2 dissolved after emplacement exceeds the amount expected from diffusion and provides field evidence for convective dissolution with a rate of 0.1 g/(m(2)y). The similarity between Bravo Dome and major US saline aquifers suggests that significant amounts of CO2 are likely to dissolve during injection at US storage sites, but that convective dissolution is unlikely to trap all injected CO2 on the 10-ky timescale typically considered for storage projects.

  14. Future ocean hypercapnia driven by anthropogenic amplification of the natural CO2 cycle.

    PubMed

    McNeil, Ben I; Sasse, Tristan P

    2016-01-21

    High carbon dioxide (CO2) concentrations in sea-water (ocean hypercapnia) can induce neurological, physiological and behavioural deficiencies in marine animals. Prediction of the onset and evolution of hypercapnia in the ocean requires a good understanding of annual variations in oceanic CO2 concentration, but there is a lack of relevant global observational data. Here we identify global ocean patterns of monthly variability in carbon concentration using observations that allow us to examine the evolution of surface-ocean CO2 levels over the entire annual cycle under increasing atmospheric CO2 concentrations. We predict that the present-day amplitude of the natural oscillations in oceanic CO2 concentration will be amplified by up to tenfold in some regions by 2100, if atmospheric CO2 concentrations continue to rise throughout this century (according to the RCP8.5 scenario of the Intergovernmental Panel on Climate Change). The findings from our data are broadly consistent with projections from Earth system climate models. Our predicted amplification of the annual CO2 cycle displays distinct global patterns that may expose major fisheries in the Southern, Pacific and North Atlantic oceans to hypercapnia many decades earlier than is expected from average atmospheric CO2 concentrations. We suggest that these ocean 'CO2 hotspots' evolve as a combination of the strong seasonal dynamics of CO2 concentration and the long-term effective storage of anthropogenic CO2 in the oceans that lowers the buffer capacity in these regions, causing a nonlinear amplification of CO2 concentration over the annual cycle. The onset of ocean hypercapnia (when the partial pressure of CO2 in sea-water exceeds 1,000 micro-atmospheres) is forecast for atmospheric CO2 concentrations that exceed 650 parts per million, with hypercapnia expected in up to half the surface ocean by 2100, assuming a high-emissions scenario (RCP8.5). Such extensive ocean hypercapnia has detrimental implications for

  15. Constraints on the magnitude and rate of CO2 dissolution at Bravo Dome natural gas field

    PubMed Central

    Sathaye, Kiran J.; Hesse, Marc A.; Cassidy, Martin; Stockli, Daniel F.

    2014-01-01

    The injection of carbon dioxide (CO2) captured at large point sources into deep saline aquifers can significantly reduce anthropogenic CO2 emissions from fossil fuels. Dissolution of the injected CO2 into the formation brine is a trapping mechanism that helps to ensure the long-term security of geological CO2 storage. We use thermochronology to estimate the timing of CO2 emplacement at Bravo Dome, a large natural CO2 field at a depth of 700 m in New Mexico. Together with estimates of the total mass loss from the field we present, to our knowledge, the first constraints on the magnitude, mechanisms, and rates of CO2 dissolution on millennial timescales. Apatite (U-Th)/He thermochronology records heating of the Bravo Dome reservoir due to the emplacement of hot volcanic gases 1.2–1.5 Ma. The CO2 accumulation is therefore significantly older than previous estimates of 10 ka, which demonstrates that safe long-term geological CO2 storage is possible. Integrating geophysical and geochemical data, we estimate that 1.3 Gt CO2 are currently stored at Bravo Dome, but that only 22% of the emplaced CO2 has dissolved into the brine over 1.2 My. Roughly 40% of the dissolution occurred during the emplacement. The CO2 dissolved after emplacement exceeds the amount expected from diffusion and provides field evidence for convective dissolution with a rate of 0.1 g/(m2y). The similarity between Bravo Dome and major US saline aquifers suggests that significant amounts of CO2 are likely to dissolve during injection at US storage sites, but that convective dissolution is unlikely to trap all injected CO2 on the 10-ky timescale typically considered for storage projects. PMID:25313084

  16. Future ocean hypercapnia driven by anthropogenic amplification of the natural CO2 cycle

    NASA Astrophysics Data System (ADS)

    McNeil, Ben I.; Sasse, Tristan P.

    2016-01-01

    High carbon dioxide (CO2) concentrations in sea-water (ocean hypercapnia) can induce neurological, physiological and behavioural deficiencies in marine animals. Prediction of the onset and evolution of hypercapnia in the ocean requires a good understanding of annual variations in oceanic CO2 concentration, but there is a lack of relevant global observational data. Here we identify global ocean patterns of monthly variability in carbon concentration using observations that allow us to examine the evolution of surface-ocean CO2 levels over the entire annual cycle under increasing atmospheric CO2 concentrations. We predict that the present-day amplitude of the natural oscillations in oceanic CO2 concentration will be amplified by up to tenfold in some regions by 2100, if atmospheric CO2 concentrations continue to rise throughout this century (according to the RCP8.5 scenario of the Intergovernmental Panel on Climate Change). The findings from our data are broadly consistent with projections from Earth system climate models. Our predicted amplification of the annual CO2 cycle displays distinct global patterns that may expose major fisheries in the Southern, Pacific and North Atlantic oceans to hypercapnia many decades earlier than is expected from average atmospheric CO2 concentrations. We suggest that these ocean ‘CO2 hotspots’ evolve as a combination of the strong seasonal dynamics of CO2 concentration and the long-term effective storage of anthropogenic CO2 in the oceans that lowers the buffer capacity in these regions, causing a nonlinear amplification of CO2 concentration over the annual cycle. The onset of ocean hypercapnia (when the partial pressure of CO2 in sea-water exceeds 1,000 micro-atmospheres) is forecast for atmospheric CO2 concentrations that exceed 650 parts per million, with hypercapnia expected in up to half the surface ocean by 2100, assuming a high-emissions scenario (RCP8.5). Such extensive ocean hypercapnia has detrimental implications for

  17. Efficient electrochemical refrigeration power plant using natural gas with ∼100% CO2 capture

    NASA Astrophysics Data System (ADS)

    Al-musleh, Easa I.; Mallapragada, Dharik S.; Agrawal, Rakesh

    2015-01-01

    We propose an efficient Natural Gas (NG) based Solid Oxide Fuel Cell (SOFC) power plant equipped with ∼100% CO2 capture. The power plant uses a unique refrigeration based process to capture and liquefy CO2 from the SOFC exhaust. The capture of CO2 is carried out via condensation and purification using two rectifying columns operating at different pressures. The uncondensed gas mixture, comprising of relatively high purity unconverted fuel, is recycled to the SOFC and found to boost the power generation of the SOFC by 22%, when compared to a stand alone SOFC. If Liquefied Natural Gas (LNG) is available at the plant gate, then the refrigeration available from its evaporation is used for CO2 Capture and Liquefaction (CO2CL). If NG is utilized, then a Mixed Refrigerant (MR) vapor compression cycle is utilized for CO2CL. Alternatively, the necessary refrigeration can be supplied by evaporating the captured liquid CO2 at a lower pressure, which is then compressed to supercritical pressures for pipeline transportation. From rigorous simulations, the power generation efficiency of the proposed processes is found to be 70-76% based on lower heating value (LHV). The benefit of the proposed processes is evident when the efficiency of 73% for a conventional SOFC-Gas turbine power plant without CO2 capture is compared with an equivalent efficiency of 71.2% for the proposed process with CO2CL.

  18. Dominant plant taxa predict plant productivity responses to CO2 enrichment across precipitation and soil gradients

    USDA-ARS?s Scientific Manuscript database

    The responses of water-limited ecosystems to rising atmospheric CO2 concentration (eCO2) depend on the supply and availability of soil moisture and on change in abundance of dominant plant taxa. Soil moisture supply and availability depends primarily on precipitation amount and soil texture. Respo...

  19. Modeling plant-atmosphere carbon and water fluxes along a CO2 gradient

    USDA-ARS?s Scientific Manuscript database

    At short time scales (hourly to daily), plant photosynthesis and transpiration respond nonlinearly to atmospheric CO2 concentration and vapor pressure deficit, depending on plant water status and thus soil moisture. Modeling vegetation and soil responses to different values of CO2 at multiple time s...

  20. The CO2 Vadose Project - Buffering capacity of a carbonate vadose zone on induced CO2 leakage. Part 1: monitoring in a natural pilot experimental field

    NASA Astrophysics Data System (ADS)

    Cohen, Grégory; Loisy, Corinne; Le Roux, Olivier; Garcia, Bruno; Rouchon, Virgile; Delaplace, Philippe; Cerepi, Adrian

    2013-04-01

    The Intergovernmental Panel on Climate Change Special Report on Carbon Capture and Storage identified various knowledge gaps that need to be resolved before the large-scale implementation of CO2 geological storage to become possible. One of them is to determine what would be the impact of a CO2 leakage from a geological storage on vadose zone and near surface environment. The CO2-Vadose project aims at i) understanding the behavior of CO2 in the near surface carbonate environment during an induced CO2 leakage, ii) assessing numerical simulations associated with CO2 release experiments and iii) developing integrated field methodologies to detect and quantify a potential CO2 leakage. A gas mixture of CO2 and tracers (He and Kr) was released in a cavity (9 m3, 7 m deep) located in an abandoned limestone quarry in Gironde (France). More than forty gas probes were set up (in the near surface and all around the cavity in limestone) for following CO2 concentrations before, during and after injection thanks to micro-GC and Li-Cor analyzers. The meteorological parameters were recorded at the site surface as well as around the injection room. Experimental observations of variations of electrical resistivity were also carried out in order to investigate the evolution of limestone geophysical property in response to possible leakages of geologically sequestered CO2. The dynamic evolution of electrical resistivity was measured thanks to time-lapse electrical resistivity tomography. Natural ground and limestone CO2 concentrations were monitored during a year before CO2 injection. Natural CO2 concentrations variations were observed in order to plot a natural baseline and so to determine the best period for the injection and to distinguish biogenic from injected CO2. These concentrations varied between about 400 ppm to more than 20,000 ppm, following cycles of about six weeks. Initial electrical resistivity tomography was also carried out just before the injection in order to have

  1. Effects of atmospheric CO2 concentration, irradiance, and soil nitrogen availability on leaf photosynthetic traits of Polygonum sachalinense around natural CO2 springs in northern Japan.

    PubMed

    Osada, Noriyuki; Onoda, Yusuke; Hikosaka, Kouki

    2010-09-01

    Long-term exposure to elevated CO2 concentration will affect the traits of wild plants in association with other environmental factors. We investigated multiple effects of atmospheric CO2 concentration, irradiance, and soil N availability on the leaf photosynthetic traits of a herbaceous species, Polygonum sachalinense, growing around natural CO2 springs in northern Japan. Atmospheric CO2 concentration and its interaction with irradiance and soil N availability affected several leaf traits. Leaf mass per unit area increased and N per mass decreased with increasing CO2 and irradiance. Leaf N per area increased with increasing soil N availability at higher CO2 concentrations. The photosynthetic rate under growth CO2 conditions increased with increasing irradiance and CO2, and with increasing soil N at higher CO2 concentrations. The maximal velocity of ribulose 1,5-bisphosphate carboxylation (V (cmax)) was affected by the interaction of CO2 and soil N, suggesting that down-regulation of photosynthesis at elevated CO2 was more evident at lower soil N availability. The ratio of the maximum rate of electron transport to V (cmax) (J (max)/V (cmax)) increased with increasing CO2, suggesting that the plants used N efficiently for photosynthesis at high CO2 concentrations by changes in N partitioning. To what extent elevated CO2 influenced plant traits depended on other environmental factors. As wild plants are subject to a wide range of light and nutrient availability, our results highlight the importance of these environmental factors when the effects of elevated CO2 on plants are evaluated.

  2. Natural analogues for CO2 storage sites - analysis of a global dataset

    NASA Astrophysics Data System (ADS)

    Miocic, Johannes; Gilfillan, Stuart; McDermott, Christopher; Haszeldine, R. Stuart

    2013-04-01

    Carbon Capture and Storage is the only industrial scale technology currently available to reduce CO2 emissions from fossil-fuelled power plants and large industrial source to the atmosphere and thus mitigate climate change. CO2 is captured at the source and transported to subsurface storage sites, such as depleted oil and gas fields or saline aquifers. In order to have an effect on emissions and to be considered safe it is crucial that the amount of CO2 leaking from storage sites to shallow aquifers or the surface remains very low (<1% over 1000 years). Some process that influence the safety of a reservoir, such as CO2-rock-brine interactions, can be studied using experiments on both laboratory and field-scale. However, long-term processes such as the development of leakage pathways can only be understood by either predictive modelling or by studying natural CO2 reservoirs as analogues for long term CO2 storage sites. Natural CO2 reservoirs have similar geological trapping mechanisms as anticipated for CO2 storage sites and often have held CO2 for a geological period of time (millions of years) without any indication for leakage. Yet, migration of CO2 from reservoirs to the surface is also common and evidenced by gas seeps such as springs and soil degassing. We have compiled and analysed a dataset comprising of more than 50 natural CO2 reservoirs from different settings all around the globe to provide an overview of the factors that are important for the retention of CO2 in the subsurface and what processes lead to leakage of CO2 from the reservoir. Initial results indicate that if the reservoir is found to be leaking, CO2 migration is along faults and not through caprock layers. This indicates that faults act as fluid pathways and play an important role when characterizing a storage site. Additionally, it appears that overpressure of the overburden and the state of CO2 in the reservoir influence the likelihood of migration and hence the safety of a reservoir.

  3. Natural analogs of geologic CO2 sequestration: Some general implications for engineered sequestration

    NASA Astrophysics Data System (ADS)

    Fessenden, Julianna E.; Stauffer, Philip H.; Viswanathan, Hari S.

    Carbon dioxide emissions from geologic systems occur primarily from geothermal release of carbon in rock or subsurface biologic reservoirs. These systems can be very useful natural analogs for evaluating the impact of carbon dioxide leaks from engineered geologic storage reservoirs used to sequester CO2. We describe three natural analog sites that illustrate very different leak scenarios that could occur at such engineered repositories. The Mammoth Mountain site, located in California, provides an example of diffuse CO2 seepage. Crystal Geyser, Utah, is an example of a highly focused, episodic leakage geyser. Bravo Dome, NM, is an example of a CO2 reservoir where no leakage has been observed. We discuss monitoring techniques, technology placement, and modeling approaches that can be used at these natural analog sites to gain further insight into the viability of geologic CO2 sequestration.

  4. Effects of Natural Osmolytes on the Protein Structure in Supercritical CO2: Molecular Level Evidence.

    PubMed

    Monhemi, Hassan; Housaindokht, Mohammad Reza; Nakhaei Pour, Ali

    2015-08-20

    Protein instability in supercritical CO2 limits the application of this green solvent in enzyme-catalyzed reactions. CO2 molecules act as a protein denaturant at high pressure under supercritical conditions. Here, for the first time, we show that natural osmolytes could stabilize protein conformation in supercritical CO2. Molecular dynamics simulation is used to monitor the effects of adding different natural osmolytes on the conformation and dynamics of chymotrypsin inhibitor 2 (CI2) in supercritical CO2. Simulations showed that CI2 is denatured at 200 bar in supercritical CO2, which is in agreement with experimental observations. Interestingly, the protein conformation remains native after addition of ∼1 M amino acid- and sugar-based osmolyte models. These molecules stabilize protein through the formation of supramolecular self-assemblies resulting from macromolecule-osmolyte hydrogen bonds. Nevertheless, trimethylamine N-oxide, which is known as a potent osmolyte for protein stabilization in aqueous solutions, amplifies protein denaturation in supercritical CO2. On the basis of our structural analysis, we introduce a new mechanism for the osmolyte effect in supercritical CO2, an "inclusion mechanism". To the best of our knowledge, this is the first study that introduces the application of natural osmolytes in a supercritical fluid and describes mechanistic insights into osmolyte action in nonaqueous media.

  5. Dominant plant taxa predict plant productivity responses to CO2 enrichment across precipitation and soil gradients

    DOE PAGES

    Fay, Philip A.; Newingham, Beth A.; Polley, H. Wayne; ...

    2015-03-30

    The Earth’s atmosphere will continue to be enriched with carbon dioxide (CO2) over the coming century. Carbon dioxide enrichment often reduces leaf transpiration, which in water-limited ecosystems may increase soil water content, change species abundances and increase the productivity of plant communities. The effect of increased soil water on community productivity and community change may be greater in ecosystems with lower precipitation, or on coarser-textured soils, but responses are likely absent in deserts. We tested correlations among yearly increases in soil water content, community change and community plant productivity responses to CO2 enrichment in experiments in a mesic grassland withmore » fine- to coarse-textured soils, a semi-arid grassland and a xeric shrubland. We found no correlation between CO2-caused changes in soil water content and changes in biomass of dominant plant taxa or total community aboveground biomass in either grassland type or on any soil in the mesic grassland (P > 0.60). Instead, increases in dominant taxa biomass explained up to 85% of the increases in total community biomass under CO2 enrichment. The effect of community change on community productivity was stronger in the semi-arid grassland than in the mesic grassland,where community biomass change on one soil was not correlated with the change in either the soil water content or the dominant taxa. No sustained increases in soil water content or community productivity and no change in dominant plant taxa occurred in the xeric shrubland. Thus, community change was a crucial driver of community productivity responses to CO2 enrichment in the grasslands, but effects of soil water change on productivity were not evident in yearly responses to CO2 enrichment. In conclusion, future research is necessary to isolate and clarify the mechanisms controlling the temporal and spatial variations in the linkages among soil water, community change and plant productivity responses to CO2

  6. Dominant plant taxa predict plant productivity responses to CO2 enrichment across precipitation and soil gradients

    PubMed Central

    Fay, Philip A.; Newingham, Beth A.; Polley, H. Wayne; Morgan, Jack A.; LeCain, Daniel R.; Nowak, Robert S.; Smith, Stanley D.

    2015-01-01

    The Earth's atmosphere will continue to be enriched with carbon dioxide (CO2) over the coming century. Carbon dioxide enrichment often reduces leaf transpiration, which in water-limited ecosystems may increase soil water content, change species abundances and increase the productivity of plant communities. The effect of increased soil water on community productivity and community change may be greater in ecosystems with lower precipitation, or on coarser-textured soils, but responses are likely absent in deserts. We tested correlations among yearly increases in soil water content, community change and community plant productivity responses to CO2 enrichment in experiments in a mesic grassland with fine- to coarse-textured soils, a semi-arid grassland and a xeric shrubland. We found no correlation between CO2-caused changes in soil water content and changes in biomass of dominant plant taxa or total community aboveground biomass in either grassland type or on any soil in the mesic grassland (P > 0.60). Instead, increases in dominant taxa biomass explained up to 85 % of the increases in total community biomass under CO2 enrichment. The effect of community change on community productivity was stronger in the semi-arid grassland than in the mesic grassland, where community biomass change on one soil was not correlated with the change in either the soil water content or the dominant taxa. No sustained increases in soil water content or community productivity and no change in dominant plant taxa occurred in the xeric shrubland. Thus, community change was a crucial driver of community productivity responses to CO2 enrichment in the grasslands, but effects of soil water change on productivity were not evident in yearly responses to CO2 enrichment. Future research is necessary to isolate and clarify the mechanisms controlling the temporal and spatial variations in the linkages among soil water, community change and plant productivity responses to CO2 enrichment. PMID

  7. Characterization of an urban-rural CO 2 /temperature gradient and associated changes in initial plant productivity during secondary succession

    SciTech Connect

    Ziska, L. H.; Bunce, J. A.; Goins, E. W.

    2004-05-01

    To examine the impact of climate change on vegetative productivity, we exposed fallow agricultural soil to an in situ temperature and CO2 gradient between urban, suburban and rural areas in 2002. Along the gradient, average daytime CO2 concentration increased by 21% and maximum (daytime) and minimum (nighttime) daily temperatures increased by 1.6 and 3.3°C, respectively in an urban relative to a rural location. Consistent location differences in soil temperature were also ascertained. No other consistent differences in meteorological variables (e.g. wind speed, humidity, PAR, tropospheric ozone) as a function of urbanization were documented. The urban-induced environmental changes that were observed were consistent with most short-term (~50 year) global change scenarios regarding CO2 concentration and air temperature. Productivity, determined as final above-ground biomass, and maximum plant height were positively affected by daytime and soil temperatures as well as enhanced [CO2], increasing 60 and 115% for the suburban and urban sites, respectively, relative to the rural site. While long-term data are needed, these initial results suggest that urban environments may act as a reasonable surrogate for investigating future climatic change in vegetative communities.

  8. Plant-plant interactions mediate the plastic and genotypic response of Plantago asiatica to CO2: an experiment with plant populations from naturally high CO2 areas.

    PubMed

    van Loon, Marloes P; Rietkerk, Max; Dekker, Stefan C; Hikosaka, Kouki; Ueda, Miki U; Anten, Niels P R

    2016-06-01

    The rising atmospheric CO2 concentration ([CO2]) is a ubiquitous selective force that may strongly impact species distribution and vegetation functioning. Plant-plant interactions could mediate the trajectory of vegetation responses to elevated [CO2], because some plants may benefit more from [CO2] elevation than others. The relative contribution of plastic (within the plant's lifetime) and genotypic (over several generations) responses to elevated [CO2] on plant performance was investigated and how these patterns are modified by plant-plant interactions was analysed. Plantago asiatica seeds originating from natural CO2 springs and from ambient [CO2] sites were grown in mono stands of each one of the two origins as well as mixtures of both origins. In total, 1944 plants were grown in [CO2]-controlled walk-in climate rooms, under a [CO2] of 270, 450 and 750 ppm. A model was used for upscaling from leaf to whole-plant photosynthesis and for quantifying the influence of plastic and genotypic responses. It was shown that changes in canopy photosynthesis, specific leaf area (SLA) and stomatal conductance in response to changes in growth [CO2] were mainly determined by plastic and not by genotypic responses. We further found that plants originating from high [CO2] habitats performed better in terms of whole-plant photosynthesis, biomass and leaf area, than those from ambient [CO2] habitats at elevated [CO2] only when both genotypes competed. Similarly, plants from ambient [CO2] habitats performed better at low [CO2], also only when both genotypes competed. No difference in performance was found in mono stands. The results indicate that natural selection under increasing [CO2] will be mainly driven by competitive interactions. This supports the notion that plant-plant interactions have an important influence on future vegetation functioning and species distribution. Furthermore, plant performance was mainly driven by plastic and not by genotypic responses to changes in

  9. Plant–plant interactions mediate the plastic and genotypic response of Plantago asiatica to CO2: an experiment with plant populations from naturally high CO2 areas

    PubMed Central

    van Loon, Marloes P.; Rietkerk, Max; Dekker, Stefan C.; Hikosaka, Kouki; Ueda, Miki U.; Anten, Niels P. R.

    2016-01-01

    Background and Aims The rising atmospheric CO2 concentration ([CO2]) is a ubiquitous selective force that may strongly impact species distribution and vegetation functioning. Plant–plant interactions could mediate the trajectory of vegetation responses to elevated [CO2], because some plants may benefit more from [CO2] elevation than others. The relative contribution of plastic (within the plant’s lifetime) and genotypic (over several generations) responses to elevated [CO2] on plant performance was investigated and how these patterns are modified by plant–plant interactions was analysed. Methods Plantago asiatica seeds originating from natural CO2 springs and from ambient [CO2] sites were grown in mono stands of each one of the two origins as well as mixtures of both origins. In total, 1944 plants were grown in [CO2]-controlled walk-in climate rooms, under a [CO2] of 270, 450 and 750 ppm. A model was used for upscaling from leaf to whole-plant photosynthesis and for quantifying the influence of plastic and genotypic responses. Key Results It was shown that changes in canopy photosynthesis, specific leaf area (SLA) and stomatal conductance in response to changes in growth [CO2] were mainly determined by plastic and not by genotypic responses. We further found that plants originating from high [CO2] habitats performed better in terms of whole-plant photosynthesis, biomass and leaf area, than those from ambient [CO2] habitats at elevated [CO2] only when both genotypes competed. Similarly, plants from ambient [CO2] habitats performed better at low [CO2], also only when both genotypes competed. No difference in performance was found in mono stands. Conclusion The results indicate that natural selection under increasing [CO2] will be mainly driven by competitive interactions. This supports the notion that plant–plant interactions have an important influence on future vegetation functioning and species distribution. Furthermore, plant performance was mainly

  10. Tracing carbon uptake from a natural CO2 spring into tree rings: an isotope approach.

    PubMed

    Saurer, Matthias; Cherubini, Paolo; Bonani, Georges; Siegwolf, Rolf

    2003-10-01

    We analyzed 14C, 13C and 18O isotope variations over a 50-year period in tree rings of Quercus ilex L. trees growing at a natural CO2 spring in a Mediterranean ecosystem. We compared trees from two sites, one with high and one with low exposure to CO2 from the spring. The spring CO2 is free of 14C. Thus, this carbon can be traced in the wood, and the amount originating from the spring calculated. The amount decreased over time, from about 40% in 1950 to 15% at present for the site near the spring, indicating a potential difficulty in the use of natural CO2 springs for elevated CO2 research. The reason for the decrease may be decreasing emission from the spring or changes in stand structure, e.g., growth of the canopy into regions with lower concentrations. We used the 14C-calculated CO2 concentration in the canopy to determine the 13C discrimination of the plants growing under elevated CO2 by calculating the effective canopy air 13C/12C isotopic composition. The trees near the spring showed a 2.5 per thousand larger 13C discrimination than the more distant trees at the beginning of the investigated period, i.e., for the young trees, but this difference gradually disappeared. Higher discrimination under elevated CO2 indicated reduced photosynthetic capacity or increased stomatal conductance. The latter assumption is unlikely as inferred from the 18O data, which were insensitive to CO2 concentration. In conclusion, we found evidence for a downward adjustment of photosynthesis under elevated CO2 in Q. ilex in this dry, nutrient-poor environment.

  11. Comparative Reactivity Study of Natural Silicate Minerals in Wet Supercritical CO2 By In Situ Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Thompson, C.; Schaef, T.; Miller, Q. R.; Loring, J. S.; Wang, Z.; Johnson, K. T.; McGrail, P.

    2012-12-01

    Long-term storage of CO2 in deep geologic reservoirs is one of the strategies being developed and implemented for reducing anthropogenic emissions of CO2 into the atmosphere. Reservoirs containing basalt or peridotite have the potential to permanently entrap the CO2 as silicate minerals react with the CO2 and formation waters to form stable carbonate minerals. Although the relevant reactions have been well studied in the aqueous phase, comparatively little work has focused on silicate mineral reactivity in the CO2-rich fluid containing dissolved water at conditions relevant to geologic carbon sequestration. In this study, we used in situ infrared spectroscopy to investigate the carbonation of naturally occurring samples of San Carlos olivine (Mg2SiO4), Bramble enstatite (MgSiO3), and a Hawaiian picritic basalt rich in olivine. To enhance reactivity, subsamples were micronized to obtain higher surface area materials, in the range of 14 to 23 m2g-1. Experiments were carried out at 50 °C and 91 bar by circulating a stream of dry or wet supercritical CO2 (scCO2) past a sample overlayer deposited on the window of a high-pressure infrared flow cell. Water concentrations ranged from 0% to 135% relative to saturation, and transmission-mode absorbance spectra were recorded as a function of time for 24 hours. In experiments with excess water, a controlled temperature gradient was used to intentionally condense a film of liquid water on the overlayers' surfaces. No discernible reaction was detected when the samples were exposed to dry scCO2. When water was added to the scCO2, a thin film of liquid-like water formed on the surfaces of each sample, followed by spectral evidence of carbonation. The extents of reaction were dependent on both the thickness of the water films and the materials being tested. The thinnest water film was associated with the Bramble enstatite, which also appeared minimally reactive. The Hawaiian picritic basalt was slightly more reactive but contained

  12. Measurements of CO2 Carbon Stable Isotopes at Artificial and Natural Analog Sites

    NASA Astrophysics Data System (ADS)

    Humphries, S. D.; Clegg, S. M.; Rahn, T.; Fessenden, J. E.; Dobeck, L.; Spangler, L.; McLing, T. L.

    2010-12-01

    Carbon storage in geologic formations is one method to prevent carbon dioxide (CO2), produced by fossil fuel combustion, from entering the Earth's atmosphere. The monitoring, verification and accounting (MVA) of geologically sequestered CO2 is critical to the operation of a geologic storage site. Surface MVA techniques need to identify seepage from the sequestration reservoir at or below ambient CO2 concentrations. The CO2 carbon stable isotope ratio of is a sensitive diagnostic signature that can distinguish between anthropogenic and natural sources of CO2. Frequency Modulated spectroscopy (FMS) is an ultra-sensitive version of absorption spectroscopy that is capable of detecting the CO2 carbon stable isotope ratios. The technique involves phase modulation of the laser such that two side bands, spaced wider than the absorption feature of interest (in this case +/-2 GHz) are created. The signal is mixed with the local oscillator yielding a signal proportional to the species concentration. This FMS signature is recorded at multiple wavelengths to obtain the CO2 carbon isotope ratio.Two instruments using the FMS technique have been built and tested at LANL. One instrument draws ambient air into a multi-pass cell for a measurement, point source measurements. The other instrument uses an open-air path, tested up to 160 m (round trip), to measure the CO2 carbon isotopic ratio along the beam path, column average measurements. In this paper, results from multiple field deployments of one or both of the instruments will be presented. The Zero Emissions Research & Technology (ZERT) group at Montana State University established a field test site where controlled amounts of CO2 are released to test the performance of CO2 detection instruments and measurement techniques. The field site allows a controlled flow rate of CO2 to be released into the near surface through a 100 m long horizontal pipe. In July of 2009, a release was conducted, with a uniform flow rate of 0.2 tons per

  13. The noble gas geochemistry of natural CO 2 gas reservoirs from the Colorado Plateau and Rocky Mountain provinces, USA

    NASA Astrophysics Data System (ADS)

    Gilfillan, Stuart M. V.; Ballentine, Chris J.; Holland, Greg; Blagburn, Dave; Lollar, Barbara Sherwood; Stevens, Scott; Schoell, Martin; Cassidy, Martin

    2008-02-01

    Identification of the source of CO 2 in natural reservoirs and development of physical models to account for the migration and interaction of this CO 2 with the groundwater is essential for developing a quantitative understanding of the long term storage potential of CO 2 in the subsurface. We present the results of 57 noble gas determinations in CO 2 rich fields (>82%) from three natural reservoirs to the east of the Colorado Plateau uplift province, USA (Bravo Dome, NM., Sheep Mountain, CO. and McCallum Dome, CO.), and from two reservoirs from within the uplift area (St. John's Dome, AZ., and McElmo Dome, CO.). We demonstrate that all fields have CO 2/ 3He ratios consistent with a dominantly magmatic source. The most recent volcanics in the province date from 8 to 10 ka and are associated with the Bravo Dome field. The oldest magmatic activity dates from 42 to 70 Ma and is associated with the McElmo Dome field, located in the tectonically stable centre of the Colorado Plateau: CO 2 can be stored within the subsurface on a millennia timescale. The manner and extent of contact of the CO 2 phase with the groundwater system is a critical parameter in using these systems as natural analogues for geological storage of anthropogenic CO 2. We show that coherent fractionation of groundwater 20Ne/ 36Ar with crustal radiogenic noble gases ( 4He, 21Ne, 40Ar) is explained by a two stage re-dissolution model: Stage 1: Magmatic CO 2 injection into the groundwater system strips dissolved air-derived noble gases (ASW) and accumulated crustal/radiogenic noble gas by CO 2/water phase partitioning. The CO 2 containing the groundwater stripped gases provides the first reservoir fluid charge. Subsequent charges of CO 2 provide no more ASW or crustal noble gases, and serve only to dilute the original ASW and crustal noble gas rich CO 2. Reservoir scale preservation of concentration gradients in ASW-derived noble gases thus provide CO 2 filling direction. This is seen in the Bravo Dome

  14. [Effects of elevated atmospheric CO2 on plant, herbivorous insect, and its natural enemy: a review].

    PubMed

    Xie, Hai-Cui; Wang, Zhen-Ying; He, Kang-Lai

    2013-12-01

    Since the industrial revolution, the huge consumption of fossil fuels and unduly destruction of natural habitats by human activities have led to the ever-increasing concentration of atmospheric CO2. To study the adaptation mechanisms of plant, herbivorous insect, and its natural enemy within agricultural ecosystems to the elevated atmospheric CO2 concentration is of significance in deciphering the damage pattern of agricultural pest occurrence and controlling the pest occurrence and in mitigating the CO2 emission from agricultural ecosystems. This paper reviewed the research progress on the effects of elevated atmospheric CO2 on the host plant, herbivorous insect, and its natural enemy in agro-ecosystem, with the focuses on the improvement of related research methods, the variation patterns of host plant primary and secondary metabolites induced by elevated atmospheric CO2, the effects of the elevated CO2 on the growth and development, population density, and behaviors of herbivorous insect, and the biology and predation and/or parasitism rates of natural enemy. The future research frontiers in this research area were also discussed.

  15. Mechanisms influencing surface soil CO2 efflux in respect to elevation and vegetation gradients in a complex watershed

    NASA Astrophysics Data System (ADS)

    Atkins, J. W.; Epstein, H. E.; Welsch, D. L.

    2011-12-01

    Topographically complex watersheds exert spatial and temporal variations in the distribution of soil water due to horizontal flows. The redistribution of soil water has profound effects on biogeochemical cycles. Of keen interest is the impact this lateral redistribution has on carbon cycling and surface soil carbon efflux. We are currently employing a plot based study across an elevation gradient (950-1150 m) in the Weimer Run watershed located near Davis, West Virginia to evaluate carbon and water cycling dynamics. At each of three different elevation levels (high, middle, low) are three sites. At each site are three 4 m2 plots, each underneath a different vegetation cover type (open, closed tree canopy, shrub canopy), for a total of 27 plots across all elevations. At each plot, surface CO2 efflux, soil temperature, PAR, air temperature and volumetric soil water content at 0-12 cm are measured weekly during the growing season. Measurements of Leaf Area Index (LAI) and soil nutrient concentrations (NH4+, NO3-) have also been conducted for each plot. Each plot also has gas wells at both 5 and 20 cm to measure CO2 concentrations below the soil surface. Data collected from June through October, 2010, indicate a stronger control on soil CO2 efflux exerted by vegetation cover type than by elevation gradient. The impact of vegetation cover type on soil CO2 efflux increases with elevation. Based on data collected weekly from June through October, 2010, there is no significant relationship between surface soil CO2 efflux and the three elevation levels within our gradient (p = 0.47). However, a significant statistical relationship between surface soil CO2 efflux and vegetation type (p = < 0.001) exists, regardless of seasonality. Soil moisture shows an expected decline with increasing elevation. Soil temperatures across vegetation types are nearly identical. Nutrient availability appears to be strongly correlated with vegetation type, but uncorrelated with elevation level

  16. The impact of elevated CO2 concentrations on soil microbial community, soil organic matter storage and nutrient cycling at a natural CO2 vent in NW Bohemia

    NASA Astrophysics Data System (ADS)

    Nowak, Martin; Beulig, Felix; von Fischer, Joe; Muhr, Jan; Kuesel, Kirsten; Trumbore, Susan

    2014-05-01

    Natural CO2 vents or 'mofettes' are diffusive or advective exhalations of geogenic CO2 from soils. These structures occur at several places worldwide and in most cases they are linked to volcanic activity. Characteristic for mofette soils are high CO2 concentrations of up to more than 90% as well as a lack of oxygen, low pH values and reducing conditions. Mofette soils usually are considered to be sites of carbon accumulation, which is not only due to the absence of oxygen, but might also result from lower plant litter quality due to CO2 fertilization of CO2 influenced plants and reduced availability of N and P for the decomposer community. Furthermore, fermentation processes and the formation of reduced elements by anoxic decomposition might fuel chemo-lithoautotrophic or mixotrophic microbial CO2 uptake, a process which might have important ecological functions by closing internal element cycles, formation of trace gasses as well as by re-cycling and storing of carbon. Several studies of microbial community structure revealed a shift towards CO2 utilizing prokaryotes in moffete soils compared to a reference site. Here, we use combined stable and radiocarbon isotope data from mofette soils in NW Bohemia to quantify the contribution of geogenic CO2 to soil organic carbon formation within mofette soils, either resulting from plant litter or from microbial CO2 uptake. This is possible because the geogenic CO2 has a distinct isotopic signature (δ13C = -2 o Δ14C = -1000 ) that is very different from the isotopic signature of atmospheric CO2. First results show that mofette soils have a high Corg content (20 to 40 %) compared to a reference site (2 to 20 %) and soil organic matter is enriched in 13C as well as depleted in 14C. This indicates that geogenic CO2 is re-fixed and stored as SOM. In order to quantify microbial contribution to CO2 fixation and SOM storage, microbial CO2 uptake rates were determined by incubating mofette soils with 13CO2 labelled gas. The

  17. Using the Bongwana natural CO2 release to understand leakage processes and develop monitoring

    NASA Astrophysics Data System (ADS)

    Jones, David; Johnson, Gareth; Hicks, Nigel; Bond, Clare; Gilfillan, Stuart; Kremer, Yannick; Lister, Bob; Nkwane, Mzikayise; Maupa, Thulani; Munyangane, Portia; Robey, Kate; Saunders, Ian; Shipton, Zoe; Pearce, Jonathan; Haszeldine, Stuart

    2016-04-01

    Natural CO2 leakage along the Bongwana Fault in South Africa is being studied to help understand processes of CO2 leakage and develop monitoring protocols. The Bongwana Fault crops out over approximately 80 km in KwaZulu-Natal province, South Africa. In outcrop the fault is expressed as a broad fracture corridor in Dwyka Tillite, with fractures oriented approximately N-S. Natural emissions of CO2 occur at various points along the fault, manifest as travertine cones and terraces, bubbling in the rivers and as gas fluxes through soil. Exposed rock outcrop shows evidence for Fe-staining around fractures and is locally extensively kaolinitised. The gas has also been released through a shallow water well, and was exploited commercially in the past. Preliminary studies have been carried out to better document the surface emissions using near surface gas monitoring, understand the origin of the gas through major gas composition and stable and noble gas isotopes and improve understanding of the structural controls on gas leakage through mapping. In addition the impact of the leaking CO2 on local water sources (surface and ground) is being investigated, along with the seismic activity of the fault. The investigation will help to build technical capacity in South Africa and to develop monitoring techniques and plans for a future CO2 storage pilot there. Early results suggest that CO2 leakage is confined to a relatively small number of spatially-restricted locations along the weakly seismically active fault. Fracture permeability appears to be the main method by which the CO2 migrates to the surface. The bulk of the CO2 is of deep origin with a minor contribution from near surface biogenic processes as determined by major gas composition. Water chemistry, including pH, DO and TDS is notably different between CO2-rich and CO2-poor sites. Soil gas content and flux effectively delineates the fault trace in active leakage sites. The fault provides an effective testing ground for

  18. Soil type modifies response of soil carbon pools to an atmospheric CO2 gradient

    USDA-ARS?s Scientific Manuscript database

    Literature suggests that as atmospheric CO2 rises, soil carbon will cycle more rapidly as plants input greater amounts of labile carbon into the soil. This labile carbon may stimulate the decomposition of more slowly-cycling soil organic matter through microbial priming. We test these hypotheses i...

  19. Vegetative biomass predicts inflorescence production along a CO2 concentration gradient in mesic grassland

    USDA-ARS?s Scientific Manuscript database

    Atmospheric CO2 concentration will likely exceed 500 uL L-1 by 2050, often increasing plant community productivity in part by increasing abundance of species favored by increased CA. Whether increased abundance translates to increased inflorescence production is poorly understood, and is important ...

  20. Soil microbial responses to a subambient to elevated gradient of atmospheric CO2

    USDA-ARS?s Scientific Manuscript database

    Increasing atmospheric CO2 has been shown to significantly affect terrestrial ecosystems through increased primary production. This response is thought to be mitigated by changes to the soil microbial community, which can alter nutrient availability in these systems. In this study we examine the e...

  1. Proton acceleration using doped Argon plasma density gradient interacting with relativistic CO2 -laser pulse

    NASA Astrophysics Data System (ADS)

    Sahai, Aakash; Ettlinger, Oliver; Hicks, George; Ditter, Emma-Jane; Najmudin, Zulfikar

    2016-10-01

    We investigate proton and light-ion acceleration driven by the interaction of relativistic CO2 laser pulses with overdense Argon or other heavy-ion gas targets doped with lighter-ion species. Optically shaping the gas targets allows tuning of the pre-plasma scale-length from a few to several laser wavelengths, allowing the laser to efficiently drive a propagating snowplow through the bunching in the electron density. Preliminary PIC-based modeling shows that the lighter-ion species is accelerated even without any significant motion of the heavier ions which is a signature of the Relativistically Induced Transparency Acceleration mechanism. Some outlines of possible experiments at the TW CO2 laser at the Accelerator Test Facility at Brookhaven National Laboratory are presented.

  2. Electron Donor-Acceptor Nature of the Ethanol-CO2 Dimer.

    PubMed

    McGuire, Brett A; Martin-Drumel, Marie-Aline; McCarthy, Michael C

    2017-08-24

    Supercritical CO2 is an appealing nontoxic, environmentally friendly solvent for the industrial extraction of many classes of compounds, from caffeine to natural product drug precursors to petrochemical impurities. Apolar in isolation, the ability of supercritical CO2 to dissolve polar species has been empirically shown to be greatly enhanced by the addition of a small molar percentage of a polar cosolvent, often ethanol. Computational work predicts that the isolated ethanol-CO2 complex can exist either in an electron-donor configuration or through a hydrogen-bonding one; yet, neither has been previously experimentally observed. Here, we demonstrate by rotational spectroscopy that the isolated, gas-phase ethanol-CO2 dimer is an electron donor-acceptor complex.

  3. Electron Donor-Acceptor Nature of the Ethanol-CO2 Dimer

    NASA Astrophysics Data System (ADS)

    McGuire, Brett A.; Martin-Drumel, Marie-Aline; McCarthy, Michael A.

    2017-08-01

    Supercritical CO2 is an appealing nontoxic, environmentally friendly solvent for the industrial extraction of many classes of compounds, from caffeine to natural product drug precursors to petrochemical impurities. Apolar in isolation, the ability of supercritical CO2 to dissolve polar species has been empirically shown to be greatly enhanced by the addition of a small molar percentage of a polar cosolvent, often ethanol. Computational work predicts that the isolated ethanol-CO2 complex can exist either in an electron-donor configuration or through a hydrogen-bonding one; yet, neither has been previously experimentally observed. Here, we demonstrate by rotational spectroscopy that the isolated, gas-phase ethanol-CO2 dimer is an electron donor-acceptor complex.

  4. Matsushiro Earthquake Swarm (1965-1967) as a Natural Analogue of CO2 Storage and Leakage

    NASA Astrophysics Data System (ADS)

    Yamamoto, K.; Koide, H.; Tosha, T.; Todaka, N.; Nakanishi, S.; Aoyagi, R.; Benson, S.; Rutqvist, J.; Lewicki, J.

    2006-12-01

    The Matsushiro basin, Nagano city, Central Japan, is a unique natural analogue site of the CO2 storage and leakage through fault. From May 1966 to February 1967, ten million tons of CO2-bearing water discharged through surface ruptures and springs midst an earthquake swarm. The swarm began in August 1965 and the active period lasted two years followed by three-year relatively silent term. The location of water and CO2 discharge was concentrated in a narrow strip along the main focal fault. Weak seismic activities, CO2 bearing hot spa, and bubbles in rice paddy are observed, so the low intensity activities seem to continue. The fault is a left-lateral strike-slip fault striking NW-SE. Surface upheaval up to 90 cm and lateral motion corresponding to the strike-slip fault were observed. Based on this and additional geophysical evidence, some past studies adopted the idea that the upward water migration in the fault played a major role in the occurrence of the earthquake through the dilatancy mechanism. In this model, the earthquakes are assumed to follow the preceding hydrological and hydraulic phenomena such as water migration to the fractures in rock mass, reducing effective stress, and shear failures with increasing permeability. The authors anticipate that also CO2 played some vital roles in the phenomena observed at Matsushiro, and we could learn the CO2 behaviour in the underground condition. We assume that the fault and CO2 bearing water interacted through chemo-physical (precipitation/dissolution of carbonate and phase change) and mechanical (CO2 pressure induced stress and permeability change in the fault) processes, and affected the flow characters, seismicity, and the initiation and termination of the activities. For the investigation, geochemical surveys were carried out in the area to characterize present day surface CO2 flux. Geochemical and geomechanical modelling are being conducted for the quantitative understanding of the mechanisms. Also, water

  5. New York City's Urban Dome: Past and Present CO2 Concentration Patterns from an Urban to Rural Gradient

    NASA Astrophysics Data System (ADS)

    Hsueh, D.; Griffin, K.; McGillis, W. R.

    2010-12-01

    Urban centers may act as an important but often un-quantified point source for carbon dioxide (CO2) release and are a nexus between population growth, air quality and climate change. In addition, elucidating the effects of urbanization on plant physiology and function is critically important to understand how our natural ecosystems will respond to anthropogenic change. Tree ring 14C isotope composition can provide a localized historical record of an area’s fossil fuel-derived CO2 levels making it is possible to reconstruct an area’s anthropogenic CO2 history. Data from meteorological stations set up in and around New York City were utilized for the analysis of current CO2 levels. The focus here will be on the past 150 year record of CO2 concentrations in 10-year segments from an urban to rural transect in the greater New York City greater area. Furthermore, a 60 year record in 5-year increments were obtained from Commodore Barry Park, a highly industrialized, concrete-heavy area downwind from Manhattan, and the other in Forest Park, a densely vegetated park in Queens. Contemporary daily and seasonal variations of CO2 at a high temporal scale were measured as well. Variations in daily temperature ranges (DTR) will also be considered. Over the past century, the tree core data show that Central Park was approximately on average 15 ppm higher than the “clean” record of Mauna Loa and the Siple Ice Core. At a finer temporal scale, the current meteorological data show a similar overall trend, however, differences are much more variable and there are instances where urban CO2 can be as low as rural CO2, depending on the season and meteorological conditions of the region. Differences between an urban (Harlem) to rural (LDEO) site, for example, can vary 30.6 ppm in the winter and 13.7 in the summer, with similar seasonal trends at our other sites. The maximum average nighttime temperature difference between an urban (Harlem) and a rural (BRF) site reached 5.95

  6. A natural analogue for CO2 leakage: The release and fate of CO2 at the Jan Mayen vent fields (AMOR)

    NASA Astrophysics Data System (ADS)

    Baumberger, T.; Lilley, M. D.; Pedersen, R. B.; Thorseth, I. H.

    2013-12-01

    Carbon dioxide capture and storage (CCS) is seen as a new possible technique for reducing the emission of industrial CO2 to the atmosphere. To evaluate the risks of sub-seabed CO2 storage, the European Commission is supporting the international and multi-disciplinary ECO2 project. Among other objectives, this project is dealing with evaluating the likelihood of leakage and the resulting possible impacts on marine ecosystems. In the framework of the ECO2 project, the release and dispersal of CO2 have been studied at several natural seep sites. In this study, we present geochemical data collected at the natural CO2 leakage analogue, Jan Mayen vent fields (JMVF). The basalt-hosted JMVF are located at 71° N on the southern end of the ultra-slow spreading Mohns Ridge, which is part of the Arctic Mid-Ocean Ridge (AMOR) system. The JMVF are composed of several venting sites, spread over a large area. These venting areas include focused high-temperature venting and diffuse low-temperature fluid flow vents as well as areas where free gas bubbles are released. Over the past few years, we have repeatedly visited and extensively sampled these vent fields to study the release and fate of CO2 in this natural seep area. One of our main objectives was to constrain the CO2 content of the widely emitted gas and to study its dispersion and fate in the water column. We have also investigated hydrate formation, which is observed at various locations. The venting fluids are chemically characterized by CO2 concentrations of up to 110 mmol/kg, having an associated isotopic composition representing a mantle carbon source. Thus, the CO2 concentrations measured at the JMVF represent the high-end compared to the concentration range of most other basalt-hosted hydrothermal mid-ocean ridge systems. Even though the concentrations of the emitted CO2 vary over time and with the type of venting (focused flow, diffuse flow or bubbles), the overall release is continuously high. The dispersion of the

  7. Chemical-mechanical coupling observed for depleted oil reservoirs subjected to long-term CO2-exposure - A case study of the Werkendam natural CO2 analogue field

    NASA Astrophysics Data System (ADS)

    Hangx, Suzanne; Bakker, Elisenda; Bertier, Pieter; Nover, Georg; Busch, Andreas

    2015-10-01

    Geological storage of CO2 is one of the most promising technologies to rapidly reduce anthropogenic emissions of carbon dioxide. In order to ensure storage integrity, it is important to understand the effect of long-term CO2/brine/rock interactions on the mechanical behaviour of a storage complex. As most of these reactions are too slow to reproduce on laboratory timescales, we studied a natural CO2 analogue reservoir (the Röt Fringe Sandstone, Werkendam field, the Netherlands; 125-135 Ma of CO2-exposure) and its unreacted counterpart. We focused on CO2-induced mineralogical and porosity-permeability changes, and their effect on mechanical behaviour of both intact rock and simulated fault gouge. Overall, CO2-exposure did not lead to drastic mineralogical changes. The CO2-exposed material shows a stronger dependence of permeability on porosity, which is attributed to differences in diagenesis (closed-system diagenesis and hydrocarbon emplacement) taking place before CO2 charging. The limited extent of reaction was in part the result of bitumen coatings protecting specific mineral phases from reaction. In local, mm-sized zones displaying significant anhydrite cement dissolution, enhanced porosity was observed. For most of the reservoir the long-term mechanical behaviour after CO2-exposure could be described by the behaviour of the unreacted sandstone, while these more 'porous' zones had a lower rock strength. In addition, CO2-exposure did not affect the fault friction behaviour, and slip is expected to result in stable sliding. Simple stress path calculations predict that reservoir failure due to depletion and injection is unlikely, even for the 'porous' zones, nor will fault reactivation occur for realistic injection scenarios.

  8. Modeling of occupant-generated CO2 dynamics in naturally ventilated classrooms.

    PubMed

    Bartlett, Karen H; Martinez, Mark; Bert, Joel

    2004-03-01

    A numerical method is presented to estimate the concentration of occupant-generated CO(2) for the (time-varying) occupancy typically found in nonforced ventilated elementary school classrooms. Here, the governing mass balance was solved numerically and compared to experimental measurements in order to estimate the respiration and (time-varying) infiltration rates. For the cases studied, we estimate an average CO(2) generation rate per child as 404 mg/min(-1). This is similar to estimates found in the literature for the age and activity level of elementary students, the classroom occupants. The average estimated infiltration rates were found to be larger than those measured from the decay of the tracer gas SF(6) under closed-door static conditions. The in-use infiltration rates were increased by additional air exchange due to people entering and leaving the room. In addition, we show that the difference (or error) between the instantaneous concentration of CO(2) and the time-averaged value recorded by a data-logging CO(2) monitor varies depending on the infiltration rate and sampling time. Therefore, the time interval selected for averaging may increase the overall error of the apparent CO(2) concentration. We conclude that the methods used to measure air exchange rates in naturally ventilated rooms underestimate the actual ventilation rate of a room under "in-use" conditions. However, even with the addition of uncontrolled outdoor air, the concentration of CO(2) in the classrooms studied was higher than recommended to meet air quality objectives.

  9. Recovery of methane from gas hydrates intercalated within natural sediments using CO(2) and a CO(2)/N(2) gas mixture.

    PubMed

    Koh, Dong-Yeun; Kang, Hyery; Kim, Dae-Ok; Park, Juwoon; Cha, Minjun; Lee, Huen

    2012-08-01

    The direct recovery of methane from massive methane hydrates (MHs), artificial MH-bearing clays, and natural MH-bearing sediments is demonstrated, using either CO(2) or a CO(2)/N(2) gas mixture (20 mol % of CO(2) and 80 mol % of N(2), reproducing flue gas from a power plant) for methane replacement in complex marine systems. Natural gas hydrates (NGHs) can be converted into CO(2) hydrate by a swapping mechanism. The overall process serves a dual purpose: it is a means of sustainable energy-source exploitation and greenhouse-gas sequestration. In particular, scant attention has been paid to the natural sediment clay portion in deep-sea gas hydrates, which is capable of storing a tremendous amount of NGH. The clay interlayer provides a unique chemical-physical environment for gas hydrates. Herein, for the first time, we pull out methane from intercalated methane hydrates in a clay interlayer using CO(2) and a CO(2)/N(2) gas mixture. The results of this study are expected to provide an essential physicochemical background required for large-scale NGH production under the seabed.

  10. CO2-rich geothermal areas in Iceland as natural analogues for geologic carbon sequestration

    NASA Astrophysics Data System (ADS)

    Thomas, D.; Maher, K.; Bird, D. K.; Brown, G. E.; Arnorsson, S.

    2013-12-01

    Geologic CO2 sequestration into mafic rocks via silicate mineral dissolution and carbonate precipitation has been suggested as a way to mitigate industrial CO2 emissions by storing CO2 in a stable form. Experimental observations of irreversible reaction of basalt with supercritical or gaseous and aqueous CO2 have resulted in carbonate precipitation, but there are no universal trends linking the extent of mineralization and type of reaction products to the bulk rock composition, glass percentage or mineralogy of the starting material. Additionally, concern exists that CO2 leakage from injection sites and migration through the subsurface may induce mineral dissolution and desorption of trace elements, potentially contaminating groundwater. This study investigates low-temperature (≤180°C) basaltic geothermal areas in Iceland with an anomalously high input of magmatic CO2 as natural analogues of the geochemical processes associated with the injection of CO2 into mafic rocks and possible leakage. Fluids that contain >4 mmol/kg total CO2 are common along the divergent Snæfellsnes Volcanic Zone in western Iceland and within the South Iceland Seismic Zone in southwest Iceland. The meteorically derived waters contain up to 80 mmol/kg dissolved inorganic carbonate (DIC). The aqueous concentration of major cations and trace elements is greater than that in Icelandic surface and groundwater and increases with DIC and decreasing pH. Concentrations of As and Ni in some samples are several times the World Health Organization (WHO) guidelines for safe drinking water. Thermodynamic modeling indicates that waters approach saturation with respect to calcite and/or aragonite, kaolinite and amorphous silica, and are undersaturated with respect to plagioclase feldspar, clinozoisite and Ca-zeolites. Petrographic study of drill cuttings from wells that intersect the CO2-rich areas indicates that the sites have undergone at least two stages of hydrothermal alteration: initial high

  11. Leaking And Non-leaking Systems: Study Of Natural CO2 Accumulations For Geological Sequestration

    NASA Astrophysics Data System (ADS)

    Voltattorni, N.; Cantucci, B.; Cinti, D.

    2008-12-01

    The potential risks of geological CO2 storage must be understood and geologists are required to predict how CO2 may behave once stored underground. As natural geological accumulations of carbon dioxide occur in many basins in Italy and volcanic and seismically active areas allow CO2 rich fluids to migrate to the near surface, many of these areas have been investigated in order to study long-term geochemical processes that may occur following geological storage of anthropogenic CO2. A study representing an example of "leaking" system is the Solfatara crater (Campi Flegrei, Southern Italy) characterised by the presence of both CO2 rich-waters and fumarole. Soil gas flux measurements show that the entire area discharges between 1200 and 1500 tons of CO2 a day. Most part of analysed waters is the effect of a mixing between a shallow meteoric water and a deep thermal Na-Cl end-member and/or seawater, resulting in sodium-chloride waters. A high dissolved CO2 content (max value 566.28 cc/l) is also present. Furthermore, the Campi Flegrei frequently undergo bradyseism related to the elastic response of the shallow crust to increasing pressure within a shallow magma chamber. The study of this phenomenon could be useful to detect ground deformation linked to geomechanical changes in a geological CO2 reservoir. In contrast, an example of "non-leaking" system is the Pisticci oil and gas Field (Southern Italy) where a great variety of hydrocarbons traps are formed by horst and tilted blocks in the Mesozoic carbonate substratum covered by an almost continuous sequence of Lower Pliocene marls and Middle Pliocene-Pleistocene marly blue clays. Soil gas surveys were performed after a MD 4.5 earthquake and two years later to test the permanence of the gas distribution pattern. CO2 distribution in soil gas seems not to be affected by changes in stress, as suggested by the average values of both surveys. The principal aim of our research has been to evaluate and mitigate risks for

  12. Mechanisms for Arsenic Release at the CO2 Sequestration Natural Analog Site in Chimayo, New Mexico

    NASA Astrophysics Data System (ADS)

    Viswanathan, H. S.; Dai, Z.; Keating, E. H.; Hakala, A.; Lopano, C. L.; Carey, J. W.; Zheng, L.; Pawar, R.

    2011-12-01

    Migration of CO2 from deep storage formations into shallow drinking water aquifers is a possible risk factor related to geologic CO2 sequestration. A CO2 leak may cause mineral precipitation/dissolution reactions, changes in aqueous speciation, and changes in pH and redox conditions, possibly causing trace metal levels to rise above EPA Primary Drinking Water Standard levels. We sampled shallow wells at a natural analog site in Chimayo, New Mexico where CO2 from natural sources is upwelling from depth. We measured major ion and trace element chemistry from the site. For this study, we focused on arsenic since a few wells have high arsenic concentrations. We use a combination of sequential extraction experiments, laboratory batch and column experiments, and geochemical modeling to determine the cause of high arsenic concentrations at the site. Co-transportation of brine rather than increases in CO2 levels seems to result in high arsenic concentrations. The majority of the site is under oxidizing conditions. Arsenic transport is not strongly controlled by mineral reactions at this site. However, sorption to clays seems to play a major role in transport.

  13. Microbial diversity and hydrogeochemical characteristics of natural CO2-rich springs in Korea

    NASA Astrophysics Data System (ADS)

    Ko, D.; Do, H. K.; Yun, S. T.; Chung, H.

    2016-12-01

    Natural CO2-rich springs are unique ecosystems where microbial communities are adapted to extreme conditions including low pH. We analyzed bacterial and archaeal community composition and hydrogeochemical features in two different natural CO2-rich springs located in the south-eastern part of Korea. Analyses of hydrogeochemical characteristics and 16S rRNA gene pyrosequencing of bacteria and archaea showed remarkable distinction between the two CO2-rich springs, Hansil (HS) and Chosukol (CS). Both springs were weakly acidic (pH 5.1 to 6.2), but the electrical conductivity and the concentration of major ions such as Ca2+, Mg2+, Na+, K+, Fe+ and HCO3- were significantly higher in HS spring than in CS spring. Among the bacterial communities, the family of Gallionellaceae (ferro-oxidant), a member of the order Gallionellales was predominant in HS spring, occupying 72% of the total abundance. On the other hand, in CS spring, Oxalobacteraceae (chemolithotrophs) and Comamonadaceae (chemoorganotrophs), the families of the order Burkholderiales were predominant and their relative abundance was 65 and 21%, respectively. Among the archaeal communities, the phylum Thaumarchaeota was predominant in CS spring, its relative abundance being 72%. In HS spring, the phyla Thaumarchaeota, Euryarchaeota and Crenarchaeota were relatively evenly distributed. Our results suggest that the significant differences in bacterial and archaeal communities of each CO2-rich spring are closely related to hydrogeochemical characteristics, and also those were in accordance with the geological formation process of CO2-rich springs.

  14. Mofettes - Investigation of Natural CO2 Springs - Insights and Methods applied

    NASA Astrophysics Data System (ADS)

    Lübben, A.; Leven, C.

    2014-12-01

    The quantification of carbon dioxide concentrations and fluxes leaking from the subsurface into the atmosphere is highly relevant in several research fields such as climate change, CCS, volcanic activity, or earthquake monitoring. Many of the areas with elevated carbon dioxide degassing pose the problem that under the given situation a systematic investigation of the relevant processes is only possible to a limited extent (e.g. in terms of spatial extent, accessibility, hazardous conditions). The upper Neckar valley in Southwest Germany is a region of enhanced natural subsurface CO2 concentrations and mass fluxes of Tertiary volcanic origin. At the beginning of the twentieth century several companies started industrial mining of CO2. The decreasing productivity of the CO2 springs led to the complete shutdown of the industry in 1995 and the existing boreholes were sealed. However, there are evidences that the reservoir, located in the deposits of the Lower Triassic, started to refill during the last 20 years. The CO2 springs replenished and a variety of different phenomena (e.g. mofettes and perished flora and fauna) indicate the active process of large scale CO2 exhalation. This easy-to-access site serves as a perfect example for a natural analog to a leaky CCS site, including abandoned boreholes and a suitable porous rock reservoir in the subsurface. During extensive field campaigns we applied several monitoring techniques like measurements of soil gas concentrations, mass fluxes, electrical resistivity, as well as soil and atmospheric parameters. The aim was to investigate and quantify mass fluxes and the effect of variations in e.g. temperature, soil moisture on the mass flux intensity. Furthermore, we investigated the effect of the vicinity to a mofette on soil parameters like electrical conductivity and soil CO2 concentrations. In times of a changing climate due to greenhouse gases, regions featuring natural CO2 springs demand to be intensively investigated

  15. Piezo-tolerant natural gas-producing microbes under accumulating pCO2.

    PubMed

    Lindeboom, Ralph E F; Shin, Seung Gu; Weijma, Jan; van Lier, Jules B; Plugge, Caroline M

    2016-01-01

    It is known that a part of natural gas is produced by biogenic degradation of organic matter, but the microbial pathways resulting in the formation of pressurized gas fields remain unknown. Autogeneration of biogas pressure of up to 20 bar has been shown to improve the quality of biogas to the level of biogenic natural gas as the fraction of CO2 decreased. Still, the pCO2 is higher compared to atmospheric digestion and this may affect the process in several ways. In this work, we investigated the effect of elevated pCO2 of up to 0.5 MPa on Gibbs free energy, microbial community composition and substrate utilization kinetics in autogenerative high-pressure digestion. In this study, biogas pressure (up to 2.0 MPa) was batch-wise autogenerated for 268 days at 303 K in an 8-L bioreactor, resulting in a population dominated by archaeal Methanosaeta concilii, Methanobacterium formicicum and Mtb. beijingense and bacterial Kosmotoga-like (31% of total bacterial species), Propioniferax-like (25%) and Treponema-like (12%) species. Related microorganisms have also been detected in gas, oil and abandoned coal-bed reservoirs, where elevated pressure prevails. After 107 days autogeneration of biogas pressure up to 0.50 MPa of pCO2, propionate accumulated whilst CH4 formation declined. Alongside the Propioniferax-like organism, a putative propionate producer, increased in relative abundance in the period of propionate accumulation. Complementary experiments showed that specific propionate conversion rates decreased linearly from 30.3 mg g(-1) VSadded day(-1) by more than 90% to 2.2 mg g(-1) VSadded day(-1) after elevating pCO2 from 0.10 to 0.50 MPa. Neither thermodynamic limitations, especially due to elevated pH2, nor pH inhibition could sufficiently explain this phenomenon. The reduced propionate conversion could therefore be attributed to reversible CO2-toxicity. The results of this study suggest a generic role of the detected bacterial and archaeal species in

  16. Potential CO2 Sequestration in Oil Field Reservoirs: Baseline Mineralogy and Natural Diagenesis, Kern County, California

    NASA Astrophysics Data System (ADS)

    Horton, R. A.; Kaess, A. B.; Nguyen, D. T.; Caffee, S. E.; Olabise, O. E.

    2015-12-01

    Depleted oil fields have been suggested as potential sites for sequestration of CO2 generated from the burning of hydrocarbons. However, to be effective for removing CO2 from the atmosphere, the injected CO2 must remain within the reservoir. The role of atmospheric CO2 in rock weathering is well known and a growing body of experimental work indicates that under reservoir conditions supercritical CO2 also reacts with sedimentary rocks. In order to predict the behavior of injected CO2 in a given reservoir, detailed knowledge of the mineralogy is required. In addition, post-injection monitoring may include analyzing core samples to examine interactions between reservoir rocks and the CO2. Thus, documentation of the natural diagenetic processes within the reservoir is necessary so that changes caused by reactions with CO2 can be recognized. Kern County, California has been a major petroleum producing area for over a century and has three oil fields that have been identified as potential sites for CO2 sequestration. Two of these, Rio Bravo-Greeley and McKittrick, have no previously published mineralogic studies. Samples from these (and nearby Wasco) oil fields were studied using transmitted-light petrography and scanning electron microscopy. At Rio Bravo-Greeley-Wasco, Kreyenhagen (Eocene) and Vedder (Oligocene) sandstones are mainly arkosic arenites with only small amounts of volcanic rock fragments. Detrital feldspars exhibit wide compositional ranges (up to Or75Ab25 & Ab50An50). Diagenesis has greatly altered the rocks. There are significant amounts of relatively pure authigenic K-feldspar and albite. Small amounts of authigenic quartz, calcite, dolomite, ankerite, kaolinite, illite/smectite, chlorite, zeolite, and pyrite are present. Plagioclase has been preferentially dissolved, with andesine more susceptible than oligoclase. Al3+ has been exported from the sandstones. At McKittrick, Temblor sandstones (Oligocene-Miocene) contain up to 33% volcanic rock fragments

  17. High CO2 fluxes from grassland on histic Gleysol along soil carbon and drainage gradients

    NASA Astrophysics Data System (ADS)

    Leiber-Sauheitl, K.; Fuß, R.; Voigt, C.; Freibauer, A.

    2014-02-01

    Drained organic soils are anthropogenic emission hotspots of greenhouse gases (GHGs). Most studies have focused on deep peat soils and on peats with high organic carbon content. In contrast, histic Gleysols are characterized by shallow peat layers, which are left over from peat cutting activities or by peat mixed with mineral soil. It is unknown whether they emit less GHGs than deep Histosols when drained. We present the annual carbon and GHG balance of grasslands for six sites on nutrient-poor histic Gleysols with a shallow (30 cm) histic horizon or mixed with mineral soil in Northern Germany (soil organic carbon concentration (Corg) from 9 to 52%). The net GHG balance, corrected for carbon export by harvest, was around 4 t CO2-C-eq ha-1 yr-1 on soils with peat layer and little drainage (mean annual water table < 20 cm below surface). The net GHG balance reached 7-9 t CO2-C-eq ha-1 yr-1 on soils with sand mixed into the peat layer and water tables between 14 cm and 39 cm below surface. GHG emissions from drained histic Gleysols (i) were as high as those from deep Histosols, (ii) increase linearly from shallow to deeper drainage, (iii) but are not affected by Corg content of the histic horizon. Ecosystem respiration (Reco) was linearly correlated with water table level even if it was below the histic horizon. The Reco/GPP ratio was 1.5 at all sites, so that we ruled out a major influence of the inter-site variability in vegetation composition on annual net ecosystem exchange (NEE). The IPCC definition of organic soils includes shallow histic topsoil, unlike most national and international definitions of Histosols. Our study confirms that this broader definition is appropriate considering anthropogenic GHG emissions from drained organic soils. Countries currently apply soil maps in national GHG inventories which are likely not to include histic Gleysols. The land area with GHG emission hotspots due to drainage is likely to be much higher than anticipated. Deeply

  18. Carbon fluxes in natural plankton communities under elevated CO2 levels: a stable isotope labeling study

    NASA Astrophysics Data System (ADS)

    de Kluijver, A.; Soetaert, K.; Schulz, K. G.; Riebesell, U.; Bellerby, R. G. J.; Middelburg, J. J.

    2010-05-01

    The potential impact of rising carbon dioxide (CO2) on carbon fluxes in natural plankton communities was investigated during the 2005 PeECE III mesocosm study in Bergen, Norway. Triplicate mesocosms, in which a phytoplankton bloom was induced by nutrient addition, were incubated with 1×(~350 μatm), 2×(~700 μatm), and 3× present day CO2(~1050 μatm) levels for 3 weeks. 13C labeled bicarbonate was added to all mesocosms to follow the transfer of carbon from dissolved inorganic carbon (DIC) into phytoplankton and subsequently heterotrophic bacteria, zooplankton, and settling particles. Isotope ratios of polar lipid fatty acids (PLFA) were used to infer the biomass and production of phytoplankton and bacteria. Phytoplankton PLFA were enriched within one day after label addition, while it took another 3 days before bacteria showed substantial enrichment. Group-specific primary production measurements revealed that coccolithophores grew faster than green algae and diatoms. Elevated CO2 had a significant positive effect on post-bloom biomass of green algae, diatoms, and bacteria. A simple model based on measured isotope ratios of phytoplankton and bacteria revealed that CO2 had no significant effect on the carbon transfer efficiency from phytoplankton to bacteria. There was no indication of enhanced settling based on isotope mixing models during the phytoplankton bloom. Our results suggest that CO2 effects are most pronounced in the post-bloom phase, under nutrient limitation.

  19. Pontellid copepods, Labidocera spp., affected by ocean acidification: A field study at natural CO2 seeps.

    PubMed

    Smith, Joy N; Richter, Claudio; Fabricius, Katharina E; Cornils, Astrid

    2017-01-01

    CO2 seeps in coral reefs were used as natural laboratories to study the impacts of ocean acidification on the pontellid copepod, Labidocera spp. Pontellid abundances were reduced by ∼70% under high-CO2 conditions. Biological parameters and substratum preferences of the copepods were explored to determine the underlying causes of such reduced abundances. Stage- and sex-specific copepod lengths, feeding ability, and egg development were unaffected by ocean acidification, thus changes in these physiological parameters were not the driving factor for reduced abundances under high-CO2 exposure. Labidocera spp. are demersal copepods, hence they live amongst reef substrata during the day and emerge into the water column at night. Deployments of emergence traps showed that their preferred reef substrata at control sites were coral rubble, macro algae, and turf algae. However, under high-CO2 conditions they no longer had an association with any specific substrata. Results from this study indicate that even though the biology of a copepod might be unaffected by high-CO2, Labidocera spp. are highly vulnerable to ocean acidification.

  20. The Himalayas of Nepal, a natural laboratory for the search and measurement of CO2 discharge

    NASA Astrophysics Data System (ADS)

    Girault, Frédéric; Koirala, Bharat P.; Bhattarai, Mukunda; Rajaure, Sudhir; Richon, Patrick; Perrier, Frédéric

    2010-05-01

    : the presence of a hot spring with high δ13C, of H2S smell, of hot spots in thermal images, of a geological contact, of self-potential anomalies (Byrdina et al., Journal of Geophysical Research, 2009) or of large radon-222 flux. Preliminary results about the failures or successes of the various methods will be given in the Trisuli and Langtang valleys (Central Nepal), in the Kali Gandaki valley (Western Nepal) and in the Thuli Bheri valley (Lower Dolpo, Far Western Nepal). These various sites also offer an opportunity to test the optimal estimation of total CO2 flux, using the least amount of experimental measurements. Preliminary results complemented by simulations will also be given on the total CO2 flux. In parallel, monitoring methods are being studied in the Syabru-Bensi pilot site. First, CO2 flux has been studied as a function of time using repeated measurements. Furthermore, the high radon content of the geological CO2 allows cost-effective monitoring using BARASOL probes. More than two years of data are already available and give hints on the use of radon to follow CO2 discharge as a function of time. These first results show how experimental studies carried out in natural discharge zones provide a rich laboratory to test the methodological approaches useful for CO2 leakage and monitoring.

  1. CO2, CH4 and N2O dynamics in Belgian rivers across a gradient of anthropogenic disturbance

    NASA Astrophysics Data System (ADS)

    Borges, Alberto V.; Darchambeau, François; Beulen, Aurore

    2014-05-01

    Two rivers and two streams close to the city of Liège in Belgium (Meuse, Ourthe, Geer and Blanc Gravier) were sampled to describe the dynamics of CO2, CH4 and N2O (for the first time in Belgium for freshwaters). The four systems were chosen to cover a gradient of size (stream to river) and of human influence (mainly forested to mainly agricultural watersheds). The study covers the period from February 2011 to March 2013 with weekly sampling in surface waters. The variables were very contrasted in the four systems, the Geer showing a strong enrichment in nitrogen NH4+ et NO2-) and phosphorous in relation to the other three systems. The O2 concentrations were much lower, and the concentration of CH4, N2O and pCO2 were much higher in the Geer than in other three systems. The concentrations in CH4, N2O and pCO2 were higher in the Ourthe than in the Meuse and than in the Blanc Gravier. Marked seasonal variations were observed in the 4 systems. In general the concentration of CH4, N2O and pCO2 were higher in summer than in winter. This is related on one hand to the increase of temperature in summer that stimulates bacterial activity. Also in summer, the availability of organic matter for bacterial activity is higher after the spring phytoplankton blooms and also from allochthnous inputs from the watersheds. The increase of temperature and bacterial consumption of O2 in the water column leads to a lesser O2 penetration in the sediments that could stimulate benthic anaerobic processes among which methanogenesis and denitrification, leading to an increase of CH4 and N2O in the water column. Also, the production of N2O by denitrification strongly increases at low O2. During low water, the increase of residence time of the water mass and the decrease of current (decrease of degasing) allow an accumulation of CO2, CH4 and N2O in the water column. On the contrary during high water, dilution and increase of current (increase of degasing) lead to a decrease of concentrations

  2. Joule-Thomson Cooling Due to CO2 Injection into Natural GasReservoirs

    SciTech Connect

    Oldenburg, Curtis M.

    2006-04-21

    Depleted natural gas reservoirs are a promising target for Carbon Sequestration with Enhanced Gas Recovery (CSEGR). The focus of this study is on evaluating the importance of Joule-Thomson cooling during CO2 injection into depleted natural gas reservoirs. Joule-Thomson cooling is the adiabatic cooling that accompanies the expansion of a real gas. If Joule-Thomson cooling were extreme, injectivity and formation permeability could be altered by the freezing of residual water,formation of hydrates, and fracturing due to thermal stresses. The TOUGH2/EOS7C module for CO2-CH4-H2O mixtures is used as the simulation analysis tool. For verification of EOS7C, the classic Joule-Thomson expansion experiment is modeled for pure CO2 resulting in Joule-Thomson coefficients in agreement with standard references to within 5-7 percent. For demonstration purposes, CO2 injection at constant pressure and with a large pressure drop ({approx}50 bars) is presented in order to show that cooling by more than 20 C can occur by this effect. Two more-realistic constant-rate injection cases show that for typical systems in the Sacramento Valley, California, the Joule-Thomson cooling effect is minimal. This simulation study shows that for constant-rate injections into high-permeability reservoirs, the Joule-Thomson cooling effect is not expected to create significant problems for CSEGR.

  3. Mineral Carbonation Potential of CO2 from Natural and Industrial-based Alkalinity Sources

    NASA Astrophysics Data System (ADS)

    Wilcox, J.; Kirchofer, A.

    2014-12-01

    Mineral carbonation is a Carbon Capture and Storage (CSS) technology where gaseous CO2 is reacted with alkaline materials (such as silicate minerals and alkaline industrial wastes) and converted into stable and environmentally benign carbonate minerals (Metz et al., 2005). Here, we present a holistic, transparent life cycle assessment model of aqueous mineral carbonation built using a hybrid process model and economic input-output life cycle assessment approach. We compared the energy efficiency and the net CO2 storage potential of various mineral carbonation processes based on different feedstock material and process schemes on a consistent basis by determining the energy and material balance of each implementation (Kirchofer et al., 2011). In particular, we evaluated the net CO2 storage potential of aqueous mineral carbonation for serpentine, olivine, cement kiln dust, fly ash, and steel slag across a range of reaction conditions and process parameters. A preliminary systematic investigation of the tradeoffs inherent in mineral carbonation processes was conducted and guidelines for the optimization of the life-cycle energy efficiency are provided. The life-cycle assessment of aqueous mineral carbonation suggests that a variety of alkalinity sources and process configurations are capable of net CO2 reductions. The maximum carbonation efficiency, defined as mass percent of CO2 mitigated per CO2 input, was 83% for CKD at ambient temperature and pressure conditions. In order of decreasing efficiency, the maximum carbonation efficiencies for the other alkalinity sources investigated were: olivine, 66%; SS, 64%; FA, 36%; and serpentine, 13%. For natural alkalinity sources, availability is estimated based on U.S. production rates of a) lime (18 Mt/yr) or b) sand and gravel (760 Mt/yr) (USGS, 2011). The low estimate assumes the maximum sequestration efficiency of the alkalinity source obtained in the current work and the high estimate assumes a sequestration efficiency

  4. Equilibrium CO2 adsorption on zeolite 13X prepared from natural clays

    NASA Astrophysics Data System (ADS)

    Garshasbi, Vahid; Jahangiri, Mansour; Anbia, Mansoor

    2017-01-01

    Zeolite 13X was successfully synthesized by hydrothermal treatment using natural clays extracted from Iranian resources. The preliminary natural materials and the final zeolite 13X samples were characterized by X-ray Diffraction (XRD), Fourier-Transfer Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM) and N2 adsorption-desorption isotherm. The effects of various factors such as NaOH addition amount and aging time on the crystalline products were studied during the synthesis process. The optimum conditions related to the synthesis of zeolite 13X were set. Accordingly, NaOH concentration was equal to 4 M. It was further crystallized at 65 °C for 72 h after its homogenization by agitation at room temperature for 120 h. In this study, the zeolite 13X prepared from natural kaolin (13X-K) showed a high BET surface area of 591 m2/g with higher micropore volume (0.250 cm3/g) than other materials. Adsorption equilibrium isotherms of CO2 were investigated using a static, volumetric method. In addition, pressures for the pure component data extended up to 20 bar. The adsorption equilibrium data of CO2 was fitted to Langmuir, Freundlich, Lamgmuir-Freundlich, Toth and BET isotherm models. It was found that the Langmuir-Freundlich model was more suitable than other models for CO2 description. The results showed that the synthetic zeolite has higher equilibrium selectivity for CO2. Also, the CO2 uptake by zeolite 13X-K was equal to 6.9 mmol/g.

  5. Soil microbial respiration (CO2) of natural and anthropogenically-transformed ecosystems in Moscow region, Russia

    NASA Astrophysics Data System (ADS)

    Ivashchenko, Kristina; Ananyeva, Nadezhda; Rogovaya, Sofia; Vasenev, Viacheslav

    2016-04-01

    The CO2 concentration in modern atmosphere is increasing and one of the most reasons of it is land use changing. It is related not only with soil plowing, but also with growing urbanization and, thereby, forming the urban ecosystems. Such conversion of soil cover might be affected by efflux CO2 from soil into atmosphere. The soil CO2 efflux mainly supplies by soil microorganisms respiration (contribution around 70-90%) and plant roots respiration. Soil microbial respiration (MR) is determined in the field (in situ) and laboratory (in vitro) conditions. The measurement of soil MR in situ is labour-consuming, and for district, region and country areas it is difficult carried. We suggest to define the MR of the upper highest active 10 cm mineral soil layer (in vitro) followed by the accounting of area for different ecosystems in large region of Russia. Soils were sampled (autumn, 2011) in natural (forest, meadow) and anthropogenically-transformed (arable, urban) ecosystems of Sergiev-Posad, Taldom, Voskresenk, Shatura, Serpukhov and Serbryanye Prudy districts in Moscow region. In soil samples (total 156) the soil MR (24 h, 22°C, 60% WHC) were measured after preincubation procedure (7 d., 22°C, 55% WHC). The soil MR ranged from 0.13 (urban) to 5.41 μg CO2-C g-1 h-1 (meadow), the difference between these values was 42 times. Then, the soil MR values (per unit soil weight) were calculated per unit soil area (1 m2), the layer thickness of which was 0.1 m (soil volume weight was equaled 1 g cm-3). The high MR values were noted for forests soil (832-1410 g CO2-C m-2 yr-1) of studied districts, and the low MR values were for arable and urban soils (by 1.6-3.2 and 1.3-2.7 times less compared to forests, respectively). The MR rate of urban soil in Voskresenk district was comparable to that of corresponding meadows and it was even higher (in average by 2.3 times) in Serpukhov district. The soil MR rate of studied cities was higher by 20%, than in corresponding arable soils

  6. Long-term responses of the green-algal lichen Parmelia caperata to natural CO2 enrichment.

    PubMed

    Balaguer, L; Manrique, E; de Los Rios, A; Ascaso, C; Palmqvist, K; Fordham, M; Barnes, J D

    1999-05-01

    Acclimation to elevated CO2 was investigated in Parmelia caperata originating from the vicinity of a natural CO2 spring, where the average daytime CO2 concentration was 729 ± 39 μmol mol(-1) dry air. Thalli showed no evidence of a down-regulation in photosynthetic capacity following long-term exposure to CO2 enrichment in the field; carboxylation efficiency, total Ribulose bisphosphate carboxylase/oxygenase (Rubisco) content, apparent quantum yield of CO2 assimilation, and the light-saturated rate of CO2 assimilation (measured under ambient and saturating CO2 concentrations) were similar in thalli from the naturally CO2 enriched site and an adjacent control site where the average long-term CO2 concentration was about 355 μmol mol(-1). Thalli from both CO2 environments exhibited low CO2 compensation points and early saturation of CO2 uptake kinetics in response to increasing external CO2 concentrations, suggesting the presence of an active carbon-concentrating mechanism. Consistent with the lack of significant effects on photosynthetic metabolism, no changes were found in the nitrogen content of thalli following prolonged exposure to elevated CO2. Detailed intrathalline analysis revealed a decreased investment of nitrogen in Rubisco in the pyrenoid of algae located in the elongation zone of thalli originating from elevated CO2, an effect associated with a reduction in the percentage of the cell volume occupied by lipid bodies and starch grains. Although these differences did not affect the photosynthetic capacity of thalli, there was evidence of enhanced limitations to CO2 assimilation in lichens originating from the CO2-enriched site. The light-saturated rate of CO2 assimilation measured at the average growth CO2 concentration was found to be significantly lower in thalli originating from a CO2-enriched atmosphere compared with that of thalli originating and measured at ambient CO2. At lower photosynthetic photon flux densities, the light

  7. Elevated CO2 can modify the response to a water status gradient in a steppe grass: from cell organelles to photosynthetic capacity to plant growth.

    PubMed

    Jiang, Yanling; Xu, Zhenzhu; Zhou, Guangsheng; Liu, Tao

    2016-07-12

    The atmospheric CO2 concentration is rising continuously, and abnormal precipitation may occur more frequently in the future. Although the effects of elevated CO2 and drought on plants have been well reported individually, little is known about their interaction, particularly over a water status gradient. Here, we aimed to characterize the effects of elevated CO2 and a water status gradient on the growth, photosynthetic capacity, and mesophyll cell ultrastructure of a dominant grass from a degraded grassland. Elevated CO2 stimulated plant biomass to a greater extent under moderate changes in water status than under either extreme drought or over-watering conditions. Photosynthetic capacity and stomatal conductance were also enhanced by elevated CO2 under moderate drought, but inhibited with over-watering. Severe drought distorted mesophyll cell organelles, but CO2 enrichment partly alleviated this effect. Intrinsic water use efficiency (WUEi) and total biomass water use efficiency (WUEt) were increased by elevated CO2, regardless of water status. Plant structural traits were also found to be tightly associated with photosynthetic potentials. The results indicated that CO2 enrichment alleviated severe and moderate drought stress, and highlighted that CO2 fertilization's dependency on water status should be considered when projecting key species' responses to climate change in dry ecosystems.

  8. An ensemble approach to simulate CO2 emissions from natural fires

    NASA Astrophysics Data System (ADS)

    Eliseev, A. V.; Mokhov, I. I.; Chernokulsky, A. V.

    2014-06-01

    This paper presents ensemble simulations with the global climate model developed at the A. M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS CM). These simulations are forced by historical reconstructions of concentrations of well-mixed greenhouse gases (CO2, CH4, and N2O), sulfate aerosols (both in the troposphere and stratosphere), extent of crops and pastures, and total solar irradiance for AD 850-2005 (hereafter all years are taken as being AD) and by the Representative Concentration Pathway (RCP) scenarios for the same forcing agents until the year 2300. Our model implements GlobFIRM (Global FIRe Model) as a scheme for calculating characteristics of natural fires. Comparing to the original GlobFIRM model, in our implementation, the scheme is extended by a module accounting for CO2 release from soil during fires. The novel approach of our paper is to simulate natural fires in an ensemble fashion. Different ensemble members in the present paper are constructed by varying the values of parameters of the natural fires module. These members are constrained by the GFED-3.1 data set for the burnt area and CO2 release from fires and further subjected to Bayesian averaging. Our simulations are the first coupled model assessment of future changes in gross characteristics of natural fires. In our model, the present-day (1998-2011) global area burnt due to natural fires is (2.1 ± 0.4) × 106 km2 yr-1 (ensemble mean and intra-ensemble standard deviation are presented), and the respective CO2 emissions to the atmosphere are (1.4 ± 0.2) Pg C yr-1. The latter value is in agreement with the corresponding GFED estimates. The area burnt by natural fires is generally larger than the GFED estimates except in boreal Eurasia, where it is realistic, and in Australia, where it is smaller than these estimates. Regionally, the modelled CO2 emissions are larger (smaller) than the GFED estimates in Europe (in the tropics and north-eastern Eurasia). From

  9. Influence of natural and anthropogenic factors on the dynamics of CO2 emissions from chernozems soil

    NASA Astrophysics Data System (ADS)

    Syabruk, Olesia

    2017-04-01

    Twentieth century marked a significant expansion of agricultural production. Soil erosion caused by human activity, conversion of forests and grasslands to cropland, desertification, burning nutrient residues, drainage, excessive cultivation led to intense oxidation of soil carbon to the atmosphere and allocation of additional amounts of CO2. According to the UN Intergovernmental Panel on Climate Change, agriculture is one of the main sources of greenhouse gases emissions to the atmosphere. The thesis reveals main patterns of the impact of natural and anthropogenic factors on CO2 emissions in the chernozems typical and podzolized in a Left-bank Forest-Steppe of Ukraine, seasonal and annual dynamics. New provisions for conducting monitoring CO2 emissions from soil were developed by combining observations in natural and controlled conditions, which allows isolating the impact of hydrological, thermal and trophic factors. During the research, the methods for operational monitoring of emission of carbon losses were improved, using a portable infrared gas analyzer, which allows receiving information directly in the field. It was determined that the volumes of emission losses of carbon chernozems typical and podzolized Left-bank Forest-Steppe of Ukraine during the growing season are 480-910 kg/ha and can vary depending on the soil treatment ±( 4,0 - 6,0) % and fertilizer systems ± (3,8 - 7,1) %. The significant impact of long application of various fertilizer systems and soil treatment on the intensity of carbon dioxide emissions was investigated. It was found that most emission occurs in organic- mineral fertilizers systems with direct seeding. The seasonal dynamics of the potential capacity of the soil to produce CO2 were researched. Under identical conditions of humidity and temperature it has maximum in June and July and the gradual extinction of the autumn. It was determined that the intensity of the CO2 emission from the surface of chernozem fluctuates daily from

  10. Assessment of CO2 discharge in a spring using time-variant stable carbon isotope data as a natural analogue study of CO2 leakage

    NASA Astrophysics Data System (ADS)

    Yu, Soonyoung; Chae, Gitak; Jo, Minki; Kim, Jeong-Chan; Yun, Seong-Taek

    2015-04-01

    CO2-rich springs have been studied as a natural analogue of CO2 leakage through shallow subsurface environment, as they provide information on the behaviors of CO2 during the leakage from geologic CO2 storage sites. For this study, we monitored the δ13C values as well as temperature, pH, EC, DO, and alkalinity for a CO2-rich spring for 48 hours. The water samples (N=47) were collected every hour in stopper bottles without headspace to avoid the interaction with air and the CO2 degassing. The δ13C values of total dissolved inorganic carbon (TDIC) in the water samples were analyzed using a cavity ring-down spectroscopy (CRDS) system (Picarro). The values of δ13CTDIC, temperature, pH, EC, DO, and alkalinity were in the range of -9.43 ~ -8.91 o 12.3 ~ 13.2oC, 4.86 ~ 5.02, 186 ~ 189 μS/cm, 1.8 ~ 3.4 mg/L, and 0.74 ~ 0.95 meq/L, respectively. The concentrations of TDIC calculated using pH and alkalinity values were between 22.5 and 34.8 mmol/L. The δ13CTDIC data imply that dissolved carbon in the spring was derived from a deep-seated source (i.e., magmatic) that was slightly intermixed with soil CO2. Careful examination of the time-series variation of measured parameters shows the following characteristics: 1) the δ13CTDIC values are negatively correlated with pH (r = -0.59) and positively correlated with TDIC (r = 0.58), and 2) delay times of the change of pH and alkalinity following the change of δ13CTDIC values are 0 and -3 hours, respectively; the pH change occurs simultaneously with the change of δ13CTDIC, while the alkalinity change happens before 3 hours. Our results indicate that the studied CO2-rich spring is influenced by the intermittent supply of deep-seated CO2. [Acknowledgment] This work was financially supported by the fundamental research project of KIGAM and partially by the "Geo-Advanced Innovative Action (GAIA) Project (2014000530003)" from Korea Ministry of Environment (MOE).

  11. Hydrological and geomorphological control on CO2 outgassing from low-gradient large rivers: An example of the Yangtze River system

    NASA Astrophysics Data System (ADS)

    Liu, Shaoda; Lu, Xi Xi; Xia, Xinghui; Yang, Xiankun; Ran, Lishan

    2017-07-01

    Although CO2 emission from river surfaces is largely hydrology-related, the hydrological impact on riverine CO2 emission is rarely characterized in previous studies. Relying on daily hydrology and monthly-resolved partial pressure of water dissolved CO2 (pCO2), this study characterized the influence of spatiotemporal hydraulic variability on CO2 emission from confined low-gradient rivers of the Yangtze. Results indicate that unit-width-discharge (Q/w) explained well along-mainstem, inter-tributary and intra-annual (monthly) variations of key hydraulic characteristics (e.g., current velocity and water depth). CO2 flux normalized to unit water surface area (FCO2) varied closely with channel hydraulics (especially current velocity), which explained 48.9-67.9% and 68.2-72.0% of the spatial and temporal FCO2 variations, respectively, larger than the parts explained by pCO2 (32.1-51.1% and 28.0-31.8%). Despite high sensitivity of FCO2 to river hydraulics, CO2 flux normalized to unit channel length (FlCO2) depended primarily on channel discharge, which determines ultimately the amount of CO2 exported from the catchment and emitted to the atmosphere, regardless of the complex interplays among channel hydraulic characteristics. Limited variances under different k600-v parameterizations indicate reliability of the major conclusions in this paper.

  12. Stable isotope analysis of carbonates from the W-Hungarian natural CO2 occurrence

    NASA Astrophysics Data System (ADS)

    Cseresznyés, Dóra; Czuppon, György; Szabó, Zsuzsanna; Király, Csilla; Szabó, Csaba; Falus, György

    2017-04-01

    Carbone capture and storage is becoming more vital in the last years because the concentration of carbon-dioxide is constantly increasing in the atmosphere in relation with anthropogenic emissions. To reach the long-term safety of CO2 geological storage, it is needed to be aware of the geological environment, its behavior, and the influence of the complex physical and chemical reactions on the investigated system. The study of natural CO2 occurrences can help us to understand and predict what processes are likely to occur in CO2 geological storage reservoirs in geological time scales. In the presented work we provide a detailed insight into the stable isotope composition of different carbonate minerals of a natural CO2 reservoir from the Mihályi Répcelak area, W-Hungary. The study of stable isotope systems provides important information on the time of CO2 flooding and the origin of CO2. We measured the C and O isotope composition of different carbonate minerals, ankerite, dawsonite and siderite, as well as the H isotopes in dawsonite. The measurements both on separated mineral grains and whole rock sample were carried out. The analyses of C and O stable isotopes in separated carbonates was performed with Thermo Finnigan Delta Plus XP mass spectrometer. H stable isotope measurement was conducted on whole rocks applying LWIA-24d type laser analyser. Using the obtained isotopic values the δ13C values of CO2 in equilibrium with dawsonite and the δ18O values of water in equilibrium with carbonate minerals were calculated. The results of C and O isotopes are the following: δ 13CPDB values on average are ankerite: 1.86 ‰, dawsonite: 1.53 ‰ to 1.56 ‰, siderite: 2.07 ‰ and δ 18OSMOW values ankerite: 22.15 ‰, dawsonite: 19.46 ‰ to 19.54 ‰, siderite: 22.99 ‰. Values of δDSMOW for dawsonite vary between -73.14 ‰ and -74.31 ‰. The calculated value of δ13C of CO2 in equilibrium with dawsonite ranges between -4.55 and 2.58 ‰. These values indicate

  13. Fault-controlled CO2 leakage from natural reservoirs in the Colorado Plateau, East-Central Utah

    NASA Astrophysics Data System (ADS)

    Jung, Na-Hyun; Han, Weon Shik; Watson, Z. T.; Graham, Jack P.; Kim, Kue-Young

    2014-10-01

    The study investigated a natural analogue for soil CO2 fluxes where CO2 has naturally leaked on the Colorado Plateau, East-Central Utah in order to identify various factors that control CO2 leakage and to understand regional-scale CO2 leakage processes in fault systems. The total 332 and 140 measurements of soil CO2 flux were made at 287 and 129 sites in the Little Grand Wash (LGW) and Salt Wash (SW) fault zones, respectively. Measurement sites for CO2 flux involved not only conspicuous CO2 degassing features (e.g., CO2-driven springs/geysers) but also linear features (e.g., joints/fractures and areas of diffusive leakage around a fault damage zone). CO2 flux anomalies were mostly observed along the fault traces. Specifically, CO2 flux anomalies were focused in the northern footwall of the both LGW and SW faults, supporting the existence of north-plunging anticlinal CO2 trap against south-dipping faults as well as higher probability of the north major fault traces as conduits. Anomalous CO2 fluxes also appeared in active travertines adjacent to CO2-driven cold springs and geysers (e.g., 36,259 g m-2 d-1 at Crystal Geyser), ancient travertines (e.g., 5,917 g m-2 d-1), joint zones in sandstone (e.g., 120 g m-2 d-1), and brine discharge zones (e.g., 5,515 g m-2 d-1). These observations indicate that CO2 has escaped through those pathways and that CO2 leakage from these fault zones does not correspond to point source leakage. The magnitude of CO2 flux is progressively reduced from north (i.e. the LGW fault zone, ∼36,259 g m-2 d-1) to south (i.e. the SW fault zone, ∼1,428 g m-2 d-1) despite new inputs of CO2 and CO2-saturated brine to the northerly SW fault from depth. This discrepancy in CO2 flux is most likely resulting from the differences in fault zone architecture and associated permeability structure. CO2-rich fluids from the LGW fault zone may become depleted with respect to CO2 during lateral transport, resulting in an additional decrease in CO2 fluxes

  14. An ensemble approach to simulate CO2 emissions from natural fires

    NASA Astrophysics Data System (ADS)

    Eliseev, A. V.; Mokhov, I. I.; Chernokulsky, A. V.

    2014-01-01

    This paper presents ensemble simulations with the global climate model developed at the A. M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS CM). These simulations were forced by historical reconstruction of external forcings for 850-2005 AD and by the Representative Concentration Pathways (RCP) scenarios till year 2300. Different ensemble members were constructed by varying the governing parameters of the IAP RAS CM module to simulate natural fires. These members are constrained by the GFED-3.1 observational data set and further subjected to Bayesian averaging. This approach allows to select only changes in fire characteristics which are robust within the constrained ensemble. In our simulations, the present-day (1998-2011 AD) global area burnt due to natural fires is (2.1 ± 0.4) × 106 km2 yr-1 (ensemble means and intra-ensemble standard deviations are presented), and the respective CO2 emissions in the atmosphere are (1.4 ± 0.2) PgC yr-1. The latter value is in agreement with the corresponding observational estimates. Regionally, the model underestimates CO2 emissions in the tropics; in the extra-tropics, it underestimates these emissions in north-east Eurasia and overestimates them in Europe. In the 21st century, the ensemble mean global burnt area is increased by 13% (28%, 36%, 51%) under scenario RCP 2.6 (RCP 4.5, RCP 6.0, RCP 8.5). The corresponding global emissions increase is 14% (29%, 37%, 42%). In the 22nd-23rd centuries, under the mitigation scenario RCP 2.6 the ensemble mean global burnt area and respective CO2 emissions slightly decrease, both by 5% relative to their values in year 2100. Under other RCP scenarios, these variables continue to increase. Under scenario RCP 8.5 (RCP 6.0, RCP 4.5) the ensemble mean burnt area in year 2300 is higher by 83% (44%, 15%) than its value in year 2100, and the ensemble mean CO2 emissions are correspondingly higher by 31% (19%, 9%). All changes of natural fire characteristics in

  15. Long-term effects of CO2 on the mechanical behaviour of faults - a study of samples from a natural CO2 analogue (Entrada Sandstone, Utah, USA)

    NASA Astrophysics Data System (ADS)

    Hangx, S. J. T.; Bakker, E.; Spiers, C. J.

    2012-04-01

    In an attempt to reduce CO2 emissions, CO2 capture and storage in depleted oil and gas reservoirs is seen as one of the most important mitigation strategies. However, in order to achieve safe storage on geological timescales, it is key to maintain integrity of the caprock and any faults penetrating the seal. One of the largest uncertainties lies in the prediction of the effects of fluid-rock interaction on the mechanical integrity and sealing capacity of the reservoir-seal system in the very long term, i.e. on timescales of the order of 103 or 104 years. As chemical interactions in the rock/CO2/brine system are slow, their long-term effects on rock composition, microstructure, mechanical properties and transport properties cannot be properly reproduced in laboratory experiments. One way of addressing this issue is to conduct experiments on reservoir, caprock and fault rock samples taken from natural CO2 reservoir-seal systems, which can serve as natural analogues for CO2 storage fields. The transport and mechanical properties of these rock samples, which have reacted with CO2 over geological timescales, can then be compared with data obtained for laterally equivalent materials that are unaffected by CO2. The observed changes in rock properties can subsequently be used as input for numerical models aimed at assessing the long-term effects of CO2 on reservoir compaction, caprock damage, fault reactivation and fault permeability. We assessed the mechanical behaviour and transport properties of fault rocks. To this end, we performed triaxial direct shear experiments at room temperature under nominally dry conditions, at normal stresses up to 90 MPa and shear velocities of 0.22 -10.9 μm/s. Simulated fault rocks were prepared by crushing material obtained from surface outcrops of the Entrada Sandstone, one of the CO2-bearing formations from an analogue field under the Colorado Plateau, Utah, USA. Three types of starting material were obtained: 1) red-coloured samples

  16. Abundance and diversity of CO2-fixing bacteria in grassland soils close to natural carbon dioxide springs.

    PubMed

    Videmsek, Urska; Hagn, Alexandra; Suhadolc, Marjetka; Radl, Viviane; Knicker, Heike; Schloter, Michael; Vodnik, Dominik

    2009-07-01

    Gaseous conditions at natural CO2 springs (mofettes) affect many processes in these unique ecosystems. While the response of plants to extreme and fluctuating CO2 concentrations ([CO2]) is relatively well documented, little is known on microbial life in mofette soil. Therefore, it was the aim of this study to investigate the abundance and diversity of CO2-fixing bacteria in grassland soils in different distances to a natural carbon dioxide spring. Samples of the same soil type were collected from the Stavesinci mofette, a natural CO2 spring which is known for very pure CO2 emissions, at different distances from the CO2 releasing vents, at locations that clearly differed in soil CO2 efflux (from 12.5 to over 200 micromol CO2 m(-2) s(-1) yearly average). Bulk and rhizospheric soil samples were included into analyses. The microbial response was followed by a molecular analysis of cbbL genes, encoding for the large subunit of RubisCO, a carboxylase which is of crucial importance for C assimilation in chemolitoautotrophic microbes. In all samples analyzed, the "red-like" type of cbbL genes could be detected. In contrast, the "green-like" type of cbbL could not be measured by the applied technique. Surprisingly, a reduction of "red-like" cbbL genes copies was observed in bulk soil and rhizosphere samples from the sites with the highest CO2 concentrations. Furthermore, the diversity pattern of "red-like" cbbL genes changed depending on the CO(2) regime. This indicates that only a part of the autotrophic CO2-fixing microbes could adapt to the very high CO2 concentrations and adverse life conditions that are governed by mofette gaseous regime.

  17. Natural and industrial analogues for leakage of CO2 from storagereservoirs: identification of features, events, and processes and lessonslearned

    SciTech Connect

    Lewicki, Jennifer L.; Birkholzer, Jens; Tsang, Chin-Fu

    2006-02-28

    The injection and storage of anthropogenic CO2 in deepgeologic formations is a potentially feasible strategy to reduce CO2emissions and atmospheric concentrations. While the purpose of geologiccarbon storage is to trap CO2 underground, CO2 could migrate away fromthe storage site into the shallow subsurface and atmosphere if permeablepathways such as well bores or faults are present. Large-magnitudereleases of CO2 have occurred naturally from geologic reservoirs innumerous volcanic, geothermal, and sedimentary basin settings. Carbondioxide and natural gas have also been released from geologic CO2reservoirs and natural gas storage facilities, respectively, due toinfluences such as well defects and injection/withdrawal processes. Thesesystems serve as natural and industrial analogues for the potentialrelease of CO2 from geologic storage reservoirs and provide importantinformation about the key features, events, and processes (FEPs) that areassociated with releases, as well as the health, safety, andenvironmental consequences of releases and mitigation efforts that can beapplied. We describe a range of natural releases of CO2 and industrialreleases of CO2 and natural gas in the context of these characteristics.Based on this analysis, several key conclusions can be drawn, and lessonscan be learned for geologic carbon storage. First, CO2 can bothaccumulate beneath, and be released from, primary and secondaryreservoirs with capping units located at a wide range of depths. Bothprimary and secondary reservoir entrapments for CO2 should therefore bewell characterized at storage sites. Second, many natural releases of CO2have been correlated with a specific event that triggered the release,such as magmatic fluid intrusion or seismic activity. The potential forprocesses that could cause geomechanical damage to sealing cap rocks andtrigger the release of CO2 from a storage reservoir should be evaluated.Third, unsealed fault and fracture zones may act as fast and directconduits

  18. Anthropogenic changes to seawater buffer capacity combined with natural reef metabolism induce extreme future coral reef CO2 conditions.

    PubMed

    Shaw, Emily C; McNeil, Ben I; Tilbrook, Bronte; Matear, Richard; Bates, Michael L

    2013-05-01

    Ocean acidification, via an anthropogenic increase in seawater carbon dioxide (CO2 ), is potentially a major threat to coral reefs and other marine ecosystems. However, our understanding of how natural short-term diurnal CO2 variability in coral reefs influences longer term anthropogenic ocean acidification remains unclear. Here, we combine observed natural carbonate chemistry variability with future carbonate chemistry predictions for a coral reef flat in the Great Barrier Reef based on the RCP8.5 CO2 emissions scenario. Rather than observing a linear increase in reef flat partial pressure of CO2 (pCO2 ) in concert with rising atmospheric concentrations, the inclusion of in situ diurnal variability results in a highly nonlinear threefold amplification of the pCO2 signal by the end of the century. This significant nonlinear amplification of diurnal pCO2 variability occurs as a result of combining natural diurnal biological CO2 metabolism with long-term decreases in seawater buffer capacity, which occurs via increasing anthropogenic CO2 absorption by the ocean. Under the same benthic community composition, the amplification in the variability in pCO2 is likely to lead to exposure to mean maximum daily pCO2 levels of ca. 2100 μatm, with corrosive conditions with respect to aragonite by end-century at our study site. Minimum pCO2 levels will become lower relative to the mean offshore value (ca. threefold increase in the difference between offshore and minimum reef flat pCO2 ) by end-century, leading to a further increase in the pCO2 range that organisms are exposed to. The biological consequences of short-term exposure to these extreme CO2 conditions, coupled with elevated long-term mean CO2 conditions are currently unknown and future laboratory experiments will need to incorporate natural variability to test this. The amplification of pCO2 that we describe here is not unique to our study location, but will occur in all shallow coastal environments where high

  19. Dissolved CO2 stabilizes dissolution front migration and increases breakthrough porosity for natural porous materials

    NASA Astrophysics Data System (ADS)

    Yang, Y.; Bruns, S.; Stipp, S.; Sørensen, H.

    2016-12-01

    Reactive infiltration instability induces complex microstructural development in rocks where mineral dissolution is coupled with a pressure driven flow field. The morphing of pore structures controls the evolution of petrophysical parameters such as porosity, permeability and Young's modulus. An example is in geologic carbon storage (GCS), where the injection of CO2 incurs ongoing dissolution of minerals and the precipitation of secondary phases, which constantly evolves the microstructure of the rock formation. We show that morphological development in such processes is strongly affected by the migration of the dissolution front, defined as the interface between reactive and unreactive surface areas. We combined high resolution, in situ, X-ray imaging on natural chalk samples with a grey scale probability based reactor network model to demonstrate that the presence of dissolved CO2 can 1) greatly expand the reactive subvolume within a porous medium during percolation, by increasing the apparent mineral solubility and 2) stabilize the dissolution front, i.e. making it less sensitive to spatial perturbations, by reducing the extent of coupling between dissolution rate and chemical conversion. Overall, compared with a solution with identical pH, the presence of dissolved CO2 induces two apparently contradictory effects: it decreases the number of pore volumes of fluid required for breakthrough while it increases the critical porosity at which the breakthrough takes place. Our results suggest that CO2 storage capacity in reservoirs can be evaluated dynamically and that the evolution of cap rock fracture can be predicted based on a good characterization of the initial geometry.

  20. NATURAL CO2 FLOW FROM THE LOIHI VENT: IMPACT ON MICROBIAL PRODUCTION AND FATE OF THE CO2

    SciTech Connect

    Richard B. Coffin; Thomas J. Boyd; David L. Knies; Kenneth S. Grabowski; John W. Pohlman; Clark S. Mitchell

    2004-02-27

    The program for International Collaboration on CO{sub 2} Ocean Sequestration was initiated December 1997. Preliminary steps involved surveying a suite of biogeochemical parameters off the coast of Kona on the Big Island of Hawaii. The preliminary survey was conducted twice, in 1999 and 2000, to obtain a thorough data set including measurements of pH, current profiles, CO{sub 2} concentrations, microbial activities, and water and sediment chemistries. These data were collected in order to interpret a planned CO{sub 2} injection experiment. After these preliminary surveys were completed, local environment regulation forced moving the project to the coast north east of Bergen, Norway. The preliminary survey along the Norwegian Coast was conducted during 2002. However, Norwegian government revoked a permit, approved by the Norwegian State Pollution Control Authority, for policy reasons regarding the CO{sub 2} injection experiment. As a result the research team decided to monitor the natural CO{sub 2} flow off the southern coast of the Big Island. From December 3rd-13th 2002 scientists from four countries representing the Technical Committee of the International Carbon Dioxide Sequestration Experiment examined the hydrothermal venting at Loihi Seamount (Hawaiian Islands, USA). Work focused on tracing the venting gases, the impacts of the vent fluids on marine organisms, and CO{sub 2} influence on biogeochemical cycles. The cruise on the R/V Ka'imikai-O-Kanaloa (KOK) included 8 dives by the PISCES V submarine, 6 at Loihi and 2 at a nearby site in the lee of the Big Island. Data for this final report is from the last 2 dives on Loihi.

  1. Seasonal Variations in CO2 Efflux, Vadose Zone Gas Concentrations, and Natural Attenuation Rates at a Crude Oil Spill Site

    NASA Astrophysics Data System (ADS)

    Trost, J.; Sihota, N.; Delin, G. N.; Warren, E.

    2014-12-01

    Accurate estimates of hydrocarbon source zone natural attenuation (SZNA) rates are important for managing contaminated sites but are difficult to measure. Moreover, SZNA rates may vary seasonally in response to climatic conditions. Previous research at a crude oil spill site near Bemidji, Minnesota, USA showed that SZNA rates in the summer can be estimated by subtracting background soil CO2 efflux from the total soil CO2 efflux above the contaminated source. In this study, seasonal variations in surficial CO2 efflux were evaluated with measurements of gas concentrations (including 14CO2), temperature, and volumetric water content in the vadose zone at the site during a 2-year period. Soil CO2 effluxes in the source zone were consistently greater than background CO2 effluxes, and the magnitude and areal extent of the increased efflux varied seasonally. In the source zone, the 14CO2 and the CO2 efflux data showed a larger proportion of soil CO2 was derived from SZNA in fall and winter (October - February) compared to the summer (June - August). Surficial CO2 effluxes and vadose zone CO2 and CH4 concentrations in the source (2 - 7 meters below land surface) were positively correlated with soil temperature, indicating seasonal variability in SZNA rates. However, peak surficial CO2 effluxes did not correspond with periods of highest CO2 or CH4 concentrations at the 2 - 7 meter depth, demonstrating the effects of physical attributes (such as soil depth, frost, and volumetric water content) on gas transport. Overall, results showed that SZNA rates, background soil respiration rates, and gas transport varied seasonally, and that biological and physical factors are important to consider for accurately estimating SZNA rates.

  2. Soil microbial community changes as a result of long-term exposure to a natural CO 2 vent

    NASA Astrophysics Data System (ADS)

    Oppermann, B. I.; Michaelis, W.; Blumenberg, M.; Frerichs, J.; Schulz, H. M.; Schippers, A.; Beaubien, S. E.; Krüger, M.

    2010-05-01

    The capture and geological storage of CO 2 can be used to reduce anthropogenic greenhouse gas emissions. To assess the environmental impact of potential CO 2 leakage from deep storage reservoirs on the abundance and functional diversity of microorganisms in near-surface terrestrial environments, a natural CO 2 vent (>90% CO 2 in the soil gas) was studied as an analogue. The microbial communities were investigated using lipid biomarkers combined with compound-specific stable carbon isotope analyses, the determination of microbial activities, and the use of quantitative polymerase chain reactions (Q-PCR). With this complementary set of methods, significant differences between the CO 2-rich vent and a reference site with a normal CO 2 concentration were detected. The δ 13C values of the plant and microbial lipids within the CO 2 vent demonstrate that substantial amounts of geothermal CO 2 were incorporated into the microbial, plant, and soil carbon pools. Moreover, the numbers of Archaea and Bacteria were highest at the reference site and substantially lower at the CO 2 vent. Lipid biomarker analyses, Q-PCR, and the determination of microbial activities showed the presence of CO 2-utilising methanogenic Archaea, Geobacteraceae, and sulphate-reducing Bacteria (SRB) mainly at the CO 2 vent, only minor quantities were found at the reference site. Stable carbon isotopic analyses revealed that the methanogenic Archaea and SRB utilised the vent-derived CO 2 for assimilatory biosynthesis. Our results show a shift in the microbial community towards anaerobic and acidophilic microorganisms as a consequence of the long-term exposure of the soil environment to high CO 2 concentrations.

  3. Natural gas consumption, income, urbanization, and CO2 emissions in China and India.

    PubMed

    Solarin, Sakiru Adebola; Lean, Hooi Hooi

    2016-09-01

    The objective of this study is to examine the impact of natural gas consumption, output, and urbanization on CO2 emission in China and India for the period, 1965-2013. A cointegraton test, which provides for endogenously determined structural breaks, has been applied to examine the long-run relationship and to investigate the presence of environmental Kuznets curve (EKC) in the two countries. The presence of causal relationship between the variables is also investigated. The findings show that there is a long-run relationship in the variables and natural gas, real GDP, and urbanization have long-run positive impact on emission in both countries. There is no evidence for EKC in China and India. The findings further suggest that there is a long-run feedback relationship between the variables. The policy inferences of these findings are discussed.

  4. A flux-gradient system for simultaneous measurement of the CH4, CO2, and H2O fluxes at a lake-air interface.

    PubMed

    Xiao, Wei; Liu, Shoudong; Li, Hanchao; Xiao, Qitao; Wang, Wei; Hu, Zhenghua; Hu, Cheng; Gao, Yunqiu; Shen, Jing; Zhao, Xiaoyan; Zhang, Mi; Lee, Xuhui

    2014-12-16

    Inland lakes play important roles in water and greenhouse gas cycling in the environment. This study aims to test the performance of a flux-gradient system for simultaneous measurement of the fluxes of water vapor, CO2, and CH4 at a lake-air interface. The concentration gradients over the water surface were measured with an analyzer based on the wavelength-scanned cavity ring-down spectroscopy technology, and the eddy diffusivity was measured with a sonic anemometer. Results of a zero-gradient test indicate a flux measurement precision of 4.8 W m(-2) for water vapor, 0.010 mg m(-2) s(-1) for CO2, and 0.029 μg m(-2) s(-1) for CH4. During the 620 day measurement period, 97%, 69%, and 67% of H2O, CO2, and CH4 hourly fluxes were higher in magnitude than the measurement precision, which confirms that the flux-gradient system had adequate precision for the measurement of the lake-air exchanges. This study illustrates four strengths of the flux-gradient method: (1) the ability to simultaneously measure the flux of H2O, CO2, and CH4; (2) negligibly small density corrections; (3) the ability to resolve small CH4 gradient and flux; and (4) continuous and noninvasive operation. The annual mean CH4 flux (1.8 g CH4 m(-2) year(-1)) at this hypereutrophic lake was close to the median value for inland lakes in the world (1.6 g CH4 m(-2) year(-1)). The system has adequate precision for CH4 flux for broad applications but requires further improvement to resolve small CO2 flux in many lakes.

  5. Mechanochemical dissociation of calcium carbonate: laboratory data and relation to natural emissions of CO 2

    NASA Astrophysics Data System (ADS)

    Martinelli, Giovanni; Plescia, Paolo

    2004-05-01

    This paper investigates the possible role of mechanochemical CO 2 production due to stimulation from the action of friction on calcite. This experimentation has two objectives: firstly, to obtain information on the effect of the mechanical disassociation of carbon dioxide from the carbonates and, secondly, to simulate the conditions that may arise during a tectonic action. The action of disassociation has been observed on pure calcium carbonate from analyses ground at different times in a ring-roller mill. The ring-roller mill is a grinding system that mainly works through friction and, to a lesser extent, by non-hydrostatic compression. It has been observed that the grinding action determines an abundant release of carbon dioxide, with a non-linear trend that emulates the trend in the decrease in crystallinity. This indicates a close connection between crystallinity and the dissociation of carbonate. The Authors hypothesize a carbon dioxide release mechanism linked to the factures induced by the friction and the increase in the structural disorder induced in the lattice by the plastic sliding. This mechanism could play an important role in the natural release of CO 2, along with the other carbon dioxide sources that are already known of.

  6. Leaching of Natural Gravel and Concrete by CO2 - Experimental Design, Leaching Behaviour and Dissolution Rates

    NASA Astrophysics Data System (ADS)

    Fuchs, Rita; Leis, Albrecht; Mittermayr, Florian; Harer, Gerhard; Wagner, Hanns; Reichl, Peter; Dietzel, Martin

    2015-04-01

    The durability of building material in aggressive aqueous environments is a key factor for evaluating the product quality and application as well as of high economic interest. Therefore, aspects of durability have been frequently investigated with different approaches such as monitoring, modelling and experimental work. In the present study an experimental approach based on leaching behaviour of natural calcite-containing siliceous gravel used as backfill material in tunnelling and sprayed concrete by CO2 was developed. CO2 was introduced to form carbonic acid, which is known as an important agent to induce chemical attack. The goals of this study were (i) to develop a proper experimental design to survey the leaching of building materials on-line, (ii) to decipher individual reaction mechanisms and kinetics and (iii) to estimate time-resolved chemical resistance of the used material throughout leaching. A combined flow through reactor unit was successfully installed, where both open and closed system conditions can be easily simulated by changing flow directions and rates. The chemical compositions of the experimental solutions were adjusted by CO2 addition at pHstat conditions and monitored in-situ by pH/SpC electrodes and by analysing the chemical composition of samples throughout an experimental run. From the obtained data e.g. dissolution rates with respect to calcite were obtained for the gravel material, which were dependent on the individual calcite content of the leached material. The rates were found to reflect the flow rate conditions, and the kinetic data lay within the range expected from dissolution experiments in the CaCO3-CO2-H2O system. In case of concrete the reactions throughout the leaching experiment were complex. Coupled dissolution and precipitation phenomena (e.g. portlandite dissolution, calcite formation) occurred. The coupled reactions can be followed by the evolution of the solution chemistry. The overall rates of elemental removal from

  7. Heterophylly in the yellow waterlily, Nuphar variegata (Nymphaeaceae): effects of [CO2], natural sediment type, and water depth.

    PubMed

    Titus, J E; Gary Sullivan, P

    2001-08-01

    We transplanted Nuphar variegata with submersed leaves only into natural lake sediments in pH-, [CO(2)]-, depth-, and temperature-controlled greenhouse tanks to test the hypotheses that more fertile sediment, lower free [CO(2)], and shallower depth would all stimulate the development of floating leaves. Sediment higher in porewater [NH(4)(+)] favored floating leaf development. Low CO(2)-grown plants initiated floating leaf development significantly earlier than high CO(2)-grown plants, which produced significantly more submersed leaves and fewer floating leaves. Mean floating leaf biomass was significantly greater than mean submersed leaf biomass but was not influenced by CO(2) enrichment, whereas mean submersed leaf biomass increased 88% at high [CO(2)]. At the shallower depth (35 cm), floating leaves required 50% less biomass investment per leaf than at 70 cm, and a significantly greater proportion of plants had floating leaves (70 vs. 23-43% at 35 vs. 70 cm, respectively) for the last three of the eight leaf censuses. Sediment type, water depth, and especially free [CO(2)] all can influence leaf morphogenesis in Nuphar variegata, and the development of more and larger submersed leaves with CO(2) enrichment favors the exploitation of high [CO(2)] when it is present in the water column.

  8. Calcifying invertebrates succeed in a naturally CO2-rich coastal habitat but are threatened by high levels of future acidification

    NASA Astrophysics Data System (ADS)

    Thomsen, J.; Gutowska, M. A.; Saphörster, J.; Heinemann, A.; Trübenbach, K.; Fietzke, J.; Hiebenthal, C.; Eisenhauer, A.; Körtzinger, A.; Wahl, M.; Melzner, F.

    2010-11-01

    CO2 emissions are leading to an acidification of the oceans. Predicting marine community vulnerability towards acidification is difficult, as adaptation processes cannot be accounted for in most experimental studies. Naturally CO2 enriched sites thus can serve as valuable proxies for future changes in community structure. Here we describe a natural analogue site in the Western Baltic Sea. Seawater pCO2 in Kiel Fjord is elevated for large parts of the year due to upwelling of CO2 rich waters. Peak pCO2 values of >230 Pa (>2300 μatm) and pHNBS values of <7.5 are encountered during summer and autumn, average pCO2 values are ~70 Pa (~700 μatm). In contrast to previously described naturally CO2 enriched sites that have suggested a progressive displacement of calcifying auto- and heterotrophic species, the macrobenthic community in Kiel Fjord is dominated by calcifying invertebrates. We show that blue mussels from Kiel Fjord can maintain control rates of somatic and shell growth at a pCO2 of 142 Pa (1400 μatm, pHNBS = 7.7). Juvenile mussel recruitment peaks during the summer months, when high water pCO2 values of ~100 Pa (~1000 μatm) prevail. Our findings indicate that calcifying keystone species may be able to cope with surface ocean pHNBS values projected for the end of this century when food supply is sufficient. However, owing to non-linear synergistic effects of future acidification and upwelling of corrosive water, peak seawater pCO2 in Kiel Fjord and many other productive estuarine habitats could increase to values >400 Pa (>4000 μatm). These changes will most likely affect calcification and recruitment, and increase external shell dissolution.

  9. Calcifying invertebrates succeed in a naturally CO2 enriched coastal habitat but are threatened by high levels of future acidification

    NASA Astrophysics Data System (ADS)

    Thomsen, J.; Gutowska, M. A.; Saphörster, J.; Heinemann, A.; Trübenbach, K.; Fietzke, J.; Hiebenthal, C.; Eisenhauer, A.; Körtzinger, A.; Wahl, M.; Melzner, F.

    2010-07-01

    CO2 emissions are leading to an acidification of the oceans. Predicting marine community vulnerability towards acidification is difficult, as adaptation processes cannot be accounted for in most experimental studies. Naturally CO2 enriched sites thus can serve as valuable proxies for future changes in community structure. Here we describe a natural analogue site in the Western Baltic Sea. Seawater pCO2 in Kiel Fjord is elevated for large parts of the year due to upwelling of CO2 rich waters. Peak pCO2 values of >230 Pa (>2300 μatm) and pH values of <7.5 are encountered during summer and autumn, average pCO2 values are ~70 Pa (~700 μatm). In contrast to previously described naturally CO2 enriched sites that have suggested a progressive displacement of calcifying auto- and heterotrophic species, the macrobenthic community in Kiel Fjord is dominated by calcifying invertebrates. We show that blue mussels from Kiel Fjord can maintain control rates of somatic and shell growth at a pCO2 of 142 Pa (1400 μatm, pH=7.7). Juvenile mussel recruitment peaks during the summer months, when high water pCO2 values of ~100 Pa (~1000 μatm) prevail. Our findings indicate that calcifying keystone species may be able to cope with surface ocean pH values projected for the end of this century. However, owing to non-linear synergistic effects of future acidification and upwelling of corrosive water, peak seawater pCO2 in Kiel Fjord and many other productive estuarine habitats could increase to values >400 Pa (>4000 μatm). These changes will most likely affect calcification and recruitment, and increase external shell dissolution.

  10. Radiometric Calibration of an Airborne CO2 Pulsed Doppler Lidar Using a Natural Earth Surface

    NASA Technical Reports Server (NTRS)

    Cutten, Dean R.; Rothermel, Jeffry; Jarzembski, Maurice A.; Hardesty, R. Michael; Howell, James N.; Tratt, David M.; Srivastava, Vandana; Arnold, James E. (Technical Monitor)

    2001-01-01

    Radiometric calibration of an airborne CO2 pulsed Doppler lidar has been accomplished using surface retro-reflection signals from the White Sands National Monument, New Mexico, USA. Two circular passes were made at altitudes of 6.26 and 9.26 km. The computed calibration factors for both altitudes are in excellent agreement with the value derived from standard ground-based measurements involving a fixed sandpaper target of known reflectance. This finding corroborates a previous study that successfully calibrated an airborne continuous-wave Doppler lidar using a variety of natural Earth surfaces. The present results indicate that relatively uniform Earth-surface targets can be used for in-flight calibration of pulsed airborne, and, in principal, spaceborne lidars.

  11. A Mesocosm Experiment in an Inland Sea HNLC Region with Naturally High pCO2

    NASA Astrophysics Data System (ADS)

    Murray, J. W.; Canade, E.; Chong, M.; Peterson, A.; Reash, S.; Schaut, T.; Tonge, A.; Wang, A.; Bantam, C.; Foy, M. S.; Lessard, E. J.; Paul, B.; Fay, A.

    2012-12-01

    The University of Washington has constructed a new Ocean Acidification Experimental Lab (OAEL) facility at the Friday Harbor Laboratories (FHL). This facility consists of a small-scale indoor lab experimental facility, a large-scale in-water mesocosm facility and a fully equipped carbonate system analytical laboratory. A mesocosm experiment (nine 5m in water mesocosms with volumes of ~3500 l each) was conducted in April 2012 as part of a FHL Research Apprenticeship course. PCO2 levels in the mesocosms were adjusted initially to be ambient (3 at 650 μatm l-1) and two levels of enhancement (3 at 950 μatm l-1 and 3 at 1250 μatm l-1). The mesocosms were filled with seawater from the FHL dock and a time series over the previous nine months provided a historical context. Surface seawater at the FHL dock had concentrations of NO3 ranging from 15 to 30 μmol l-1 and values of PCO2 (calculated from DIC and Alkalinity) greater than 650 μatm l-1 over this period. The rich biological community of the San Juan Islands appear to sit in an ocean environment equivalent to an acidified ocean of the future 100 years and this is due to natural processes. The source for this high NO3 and CO2 water is upwelling along the Washington coast from the California Undercurrent that flows north from the oxygen minimum zone off Mexico along the west coast of the US. Meanwhile chlorophyll at the FHL dock is low (~1 mg l-1) so the waters around FHL qualify as a high nitrate low chlorophyll (HNLC) ocean region. Open ocean HNLC regions are thought to result from iron limitation, which influences food web structure. At FHL they are due to mixing with deeper water in the straits (mixed layer is deeper than the euphotic zone). Within two days of when the mesocosms a bloom developed. NO3 was reduced to 0 by day 6 and chlorophyll increased to 45 mg l-1. The experiment was continued for 6 days with NO3 = 0, then nutrients were added back to the initial values and a second bloom was followed with time

  12. Amine-bearing mesoporous silica for CO(2) and H(2)S removal from natural gas and biogas.

    PubMed

    Belmabkhout, Youssef; De Weireld, Guy; Sayari, Abdelhamid

    2009-12-01

    Triamine-grafted pore-expanded mesoporous silica (TRI-PE-MCM-41) exhibited high CO(2) and H(2)S adsorption capacity as well as high selectivity toward acid gases versus CH(4). Unlike physical adsorbents such as zeolites and activated carbons, the presence of moisture in the feed enhanced the CO(2) removal capability of TRI-PE-MCM-41 without altering its H(2)S adsorption capacity. Thus, depending on the feed composition, CO(2) and H(2)S may be removed over TRI-PE-MCM-41 simultaneously or sequentially. These findings are suitable for acid gas separation from CH(4)-containing mixtures such as natural gas and biogas.

  13. The nature of the CO2 -concentrating mechanisms in a marine diatom, Thalassiosira pseudonana.

    PubMed

    Clement, Romain; Dimnet, Laura; Maberly, Stephen C; Gontero, Brigitte

    2016-03-01

    Diatoms are widespread in aquatic ecosystems where they may be limited by the supply of inorganic carbon. Their carbon dioxide-concentrating mechanisms (CCMs) involving transporters and carbonic anhydrases (CAs) are well known, but the contribution of a biochemical CCM involving C4 metabolism is contentious. The CCM(s) present in the marine-centric diatom, Thalassiosira pseudonana, were studied in cells exposed to high or low concentrations of CO2 , using a range of approaches. At low CO2 , cells possessed a CCM based on active uptake of CO2 (70% contribution) and bicarbonate, while at high CO2 , cells were restricted to CO2 . CA was highly and rapidly activated on transfer to low CO2 and played a key role because inhibition of external CA produced uptake kinetics similar to cells grown at high CO2 . The activities of phosphoenolpyruvate (PEP) carboxylase (PEPC) and the PEP-regenerating enzyme, pyruvate phosphate dikinase (PPDK), were lower in cells grown at low than at high CO2 . The ratios of PEPC and PPDK to ribulose bisphosphate carboxylase were substantially lower than 1, even at low CO2 . Our data suggest that the kinetic properties of this species results from a biophysical CCM and not from C4 type metabolism.

  14. Predicting the ultimate potential of natural gas SOFC power cycles with CO2 capture - Part B: Applications

    NASA Astrophysics Data System (ADS)

    Campanari, Stefano; Mastropasqua, Luca; Gazzani, Matteo; Chiesa, Paolo; Romano, Matteo C.

    2016-09-01

    An important advantage of solid oxide fuel cells (SOFC) as future systems for large scale power generation is the possibility of being efficiently integrated with processes for CO2 capture. Focusing on natural gas power generation, Part A of this work assessed the performances of advanced pressurised and atmospheric plant configurations (SOFC + GT and SOFC + ST, with fuel cell integration within a gas turbine or a steam turbine cycle) without CO2 separation. This Part B paper investigates such kind of power cycles when applied to CO2 capture, proposing two ultra-high efficiency plant configurations based on advanced intermediate-temperature SOFCs with internal reforming and low temperature CO2 separation process. The power plants are simulated at the 100 MW scale with a set of realistic assumptions about FC performances, main components and auxiliaries, and show the capability of exceeding 70% LHV efficiency with high CO2 capture (above 80%) and a low specific primary energy consumption for the CO2 avoided (1.1-2.4 MJ kg-1). Detailed results are presented in terms of energy and material balances, and a sensitivity analysis of plant performance is developed vs. FC voltage and fuel utilisation to investigate possible long-term improvements. Options for further improvement of the CO2 capture efficiency are also addressed.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  16. Characterizing Microbial Diversity and Function in Natural Subsurface CO2 Reservoir Systems for Applied Use in Geologic Carbon Sequestration Environments

    NASA Astrophysics Data System (ADS)

    Freedman, A. J.; Thompson, J. R.

    2012-12-01

    The injection of CO2 into geological formations at quantities necessary to significantly reduce CO2 emissions will represent an environmental perturbation on a continental scale. The extent to which biological processes may play a role in the fate and transport of CO2 injected into geological formations has remained an open question due to the fact that at temperatures and pressures associated with reservoirs targeted for sequestration CO2 exists as a supercritical fluid (scCO2), which has generally been regarded as a sterilizing agent. Natural subsurface accumulations of CO2 serve as an excellent analogue for studying the long-term effects, implications and benefits of CO2 capture and storage (CCS). While several geologic formations bearing significant volumes of nearly pure scCO2 phases have been identified in the western United States, no study has attempted to characterize the microbial community present in these systems. Because the CO2 in the region is thought to have first accumulated millions of years ago, it is reasonable to assume that native microbial populations have undergone extensive and unique physiological and behavioral adaptations to adjust to the exceedingly high scCO2 content. Our study focuses on the microbial communities associated with the dolomite limestone McElmo Dome scCO2 Field in the Colorado Plateau region, approximately 1,000 m below the surface. Fluid samples were collected from 10 wells at an industrial CO2 production facility outside Cortez, CO. Subsamples preserved on site in 3.7% formaldehyde were treated in the lab with Syto 9 green-fluorescent nucleic acid stain, revealing 3.2E6 to 1.4E8 microbial cells per liter of produced fluid and 8.0E9 cells per liter of local pond water used in well drilling fluids. Extracted DNAs from sterivex 0.22 um filters containing 20 L of sample biomass were used as templates for PCR targeting the 16S rRNA gene. 16S rRNA amplicons from these samples were cloned, sequenced and subjected to microbial

  17. Measuring the human ventilatory and cerebral blood flow response to CO2: a technical consideration for the end-tidal-to-arterial gas gradient.

    PubMed

    Tymko, Michael M; Hoiland, Ryan L; Kuca, Tomas; Boulet, Lindsey M; Tremblay, Joshua C; Pinske, Bryenna K; Williams, Alexandra M; Foster, Glen E

    2016-01-15

    Our aim was to quantify the end-tidal-to-arterial gas gradients for O2 (PET-PaO2) and CO2 (Pa-PETCO2) during a CO2 reactivity test to determine their influence on the cerebrovascular (CVR) and ventilatory (HCVR) response in subjects with (PFO+, n = 8) and without (PFO-, n = 7) a patent foramen ovale (PFO). We hypothesized that 1) the Pa-PETCO2 would be greater in hypoxia compared with normoxia, 2) the Pa-PETCO2 would be similar, whereas the PET-PaO2 gradient would be greater in those with a PFO, 3) the HCVR and CVR would be underestimated when plotted against PETCO2 compared with PaCO2, and 4) previously derived prediction algorithms will accurately target PaCO2. PETCO2 was controlled by dynamic end-tidal forcing in steady-state steps of -8, -4, 0, +4, and +8 mmHg from baseline in normoxia and hypoxia. Minute ventilation (V̇E), internal carotid artery blood flow (Q̇ICA), middle cerebral artery blood velocity (MCAv), and temperature corrected end-tidal and arterial blood gases were measured throughout experimentation. HCVR and CVR were calculated using linear regression analysis by indexing V̇E and relative changes in Q̇ICA, and MCAv against PETCO2, predicted PaCO2, and measured PaCO2. The Pa-PETCO2 was similar between hypoxia and normoxia and PFO+ and PFO-. The PET-PaO2 was greater in PFO+ by 2.1 mmHg during normoxia (P = 0.003). HCVR and CVR plotted against PETCO2 underestimated HCVR and CVR indexed against PaCO2 in normoxia and hypoxia. Our PaCO2 prediction equation modestly improved estimates of HCVR and CVR. In summary, care must be taken when indexing reactivity measures to PETCO2 compared with PaCO2. Copyright © 2016 the American Physiological Society.

  18. A characterization study of some aspects of the adsorption of aqueous Co2+ ions on a natural bentonite clay.

    PubMed

    Shahwan, T; Erten, H N; Unugur, S

    2006-08-15

    The natural bentonite used in this study contained montmorillonite in addition to low cristobalite. The uptake of aqueous Co(2+) ions was investigated as a function of time, concentration, and temperature. In addition, the change in the interlayer space of montmorillonite was analyzed using XRPD, and the distribution of fixed Co(2+) ions on the heterogeneous clay surface was recorded using EDS mapping. The sorbed amount of Co(2+) appeared to closely follow Freundlich isotherm, with the sorption process showing apparent endothermic behavior. The relevance of the apparent DeltaH(o) values is briefly discussed. Analysis of the Co-sorbed bentonite samples using SEM/EDS showed that the montmorillonite fraction in the mineral was more effective in Co(2+) fixation than the cristobalite fraction. XRPD analysis demonstrated that the interlayer space of montmorillonite was slightly modified at the end of sorption.

  19. Response of bacterioplankton community structure to an artificial gradient of pCO2 in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Zhang, R.; Xia, X.; Lau, S. C. K.; Motegi, C.; Weinbauer, M. G.; Jiao, N.

    2012-08-01

    The influences of ocean acidification on bacterial diversity were investigated using DNA fingerprinting and clone library analysis of bacterioplankton samples collected from the largest CO2 manipulation mesocosm study that had been performed thus far. Terminal restriction fragment length polymorphism analysis of the PCR amplicons of the 16S rRNA genes revealed that bacterial diversity, species richness and community structure varied with the time of incubation but not the degree of ocean acidification. The phylogenetic composition of the major bacterial assemblage after a 30-day incubation under various pCO2 concentrations did not show clear effects of pCO2 levels. However, the maximum apparent diversity and species richness which occurred during incubation differed in the high and low pCO2 treatments, in which different bacterial community structure harbored. In addition, total alkalinity was one of the contributing factors for the temporal variations in bacterial community structure observed during incubation. A negative relationship between the relative abundance of Bacteroidetes and pCO2 levels was observed for samples at the end of the experiment. Our study suggested that ocean acidification affected the development of bacterial assemblages and potentially impacts the ecological function of the bacterioplankton in the marine ecosystem.

  20. Gradient domestication of Haematococcus pluvialis mutant with 15% CO2 to promote biomass growth and astaxanthin yield.

    PubMed

    Cheng, Jun; Li, Ke; Yang, Zongbo; Lu, Hongxiang; Zhou, Junhu; Cen, Kefa

    2016-09-01

    In order to increase biomass yield and reduce culture cost of Haematococcus pluvialis with flue gas from coal-fired power plants, a screened mutant by nuclear irradiation was gradually domesticated with 15% CO2 to promote biomass dry weight and astaxanthin yield. The biomass yield of mutant after 10 generations of 15% CO2 domestication increased to 1.3 times as that with air. With the optimization of nitrogen and phosphorus concentration, the biomass dry weight was further increased by 62%. The astaxanthin yield induced with 15% CO2 and high light of 135 μmol photons m(-2) s(-1) increased to 87.4mg/L, which was 6 times higher than that induced with high light in air.

  1. Effect of high pressure CO2 and mild heat processing on natural microorganisms in apple juice.

    PubMed

    Liao, Hongmei; Zhang, Liyun; Hu, Xiaosong; Liao, Xiaojun

    2010-01-31

    Apple juice was pasteurized by high pressure carbon dioxide (HPCD) at 20MPa with CO(2) concentration of 4.5-5.3% and mild heat (MH) at atmospheric pressure. Microbial inactivation and stability of natural microorganisms in apple juice were investigated. The temperatures were 37, 42, 47, 52, 57 and 62 degrees C, treatment time was 30min, and storage temperatures of pasteurized apple juice were 2 and 28 degrees C. The aerobic bacteria (AB) treated by MH at 62 degrees C and by HPCD at > or =52 degrees C were almost totally inactivated, the microbial counts were<10CFU/mL. The yeasts and moulds (Y&M) treated by MH at > or =57 degrees C and by HPCD at > or =42 degrees C were totally inactivated. HPCD increased the susceptibility of these natural microorganisms to temperature and enhanced their microbial inactivation. The AB in apple juice treated by HPCD at > or =52 degrees C and the Y&M treated by HPCD at > or =57 degrees C, the AB and the Y&M treated by MH at 62 degrees C showed a better stability during storage at 2 and 28 degrees C, but apple juice treated by HPCD at < or =47 degrees C was characterized with high microbial counts of the AB> or =2.75x10(3)CFU/ml. A viable but non-culturable (VBNC) state of the Y&M treated by MH at 57 degrees C and by HPCD at 42, 47 and 52 degrees C was observed during storage at 28 degrees C. Apparently the proper temperature of HPCD treatment of apple juice at 20MPa and stored at 2 and 28 degrees C was greater than or equal to 52 degrees C, while for MH treatment the proper temperature increased to 62 degrees C in this study. Copyright 2009 Elsevier B.V. All rights reserved.

  2. pH controls over anaerobic carbon mineralization to CO2 and CH4 in peatlands across a hydrogeomorphic landscape gradient

    NASA Astrophysics Data System (ADS)

    Ye, R.; Jin, Q.; Bohannan, B.; Bridgham, S. D.

    2011-12-01

    The efficiency of methane (CH4) production under anaerobic conditions varies greatly in peatlands across an ombrotrophic-minerotrophic gradient, but the underlying mechanisms that explain this variation are poorly known. The objectives of this experiment were to determine to what extent differences in soil pH along this gradient control (i) total CH4 and carbon dioxide (CO2) production rates and (ii) the efficiency of CH4 production versus CO2 production. We adjusted the pH of peat slurries from an ombrotrophic bog, two poor fens, an intermediate fen, and two rich fens from northern Michigan, USA to 4 levels (3.5, 4.5, 5.5, and 6.5), followed by anaerobic incubation for 43 days. Increased pH caused a significant increase in CO2 production in all sites. Regardless of site, time, and pH level, reduction of inorganic electron acceptors contributed <5% of total CO2 production. Higher pH caused acetate pooling by day 7, but this effect was greater in the more ombrotrophic sites and lasted throughout the incubation, whereas acetate was almost entirely consumed as a substrate for acetoclastic methanogenesis by day 43 in the minerotrophic sites. The proportion of acetoclastic vs. hydrogenotrophic methanogenesis increased at low pH, but this effect was only observed in the ombrotrophic sites. Increased pH greatly enhanced the efficiency of CH4 vs. CO2 production by up to 334%. However, CH4 production accounted for < 24% of the total gaseous C productions. Fermentation and/or reduction of humic compounds appeared to be the main pathway for anaerobic C mineralization. Our results indicate that higher pH increased the fermentative production of acetate and CO2, but the corresponding increase in acetoclastic methanogenesis in the ombrotrophic sites was insufficient to consume the acetate, suggesting limitation of acetoclastic methanogenesis by some factor in addition to pH in these sites. pH is an important environmental factor controlling the C mineralization to CO2 and CH4 in

  3. Soil carbon content and CO2 flux along a hydrologic gradient in a High-Arctic tundra lake basin, Northwest Greenland

    NASA Astrophysics Data System (ADS)

    McKnight, J.; Klein, E. S.; Welker, J. M.; Schaeffer, S. M.; Franklin, M.

    2015-12-01

    High Arctic landscapes are composed of watershed basins that vary in size and ecohydrology, but typically have a plant community complex that ranges from dry tundra to moist tundra to wet sedge systems along water body shorelines. The spatial extent of these plant communities reflects mean annual soil moisture and temperature, and is vulnerable to changes in climate conditions. Soil moisture and temperature significantly influence organic matter microbial activity and decomposition, and can affect the fate of soil carbon in tundra soils. Consequently, due to the unique soil carbon differences between tundra plant communities, shifts in their spatial extent may drive future High Arctic biosphere-atmosphere interactions. Understanding this terrestrial-atmosphere trace gas feedback, however, requires quantification of the rates and patterns of CO2 exchange along soil moisture gradients and the associated soil properties. In summer of 2015, soil CO2 flux rate, soil moisture and temperature were measured along a soil moisture gradient spanning three vegetation zones (dry tundra, wet tundra, and wet grassland) in a snow melt-fed lake basin near Thule Greenland. Mean soil temperature during the 2015 growing season was greater in dry tundra than in wet tundra and wet grassland (13.0 ± 1.2, 7.8 ± 0.8, and 5.5 ± 0.9°C, respectively). Mean volumetric soil moisture differed among all three vegetation zones where the soil moisture gradient ranged from 9 % (dry tundra) to 34 % (wet tundra) to 51 % (wet grassland). Mean soil CO2 flux was significantly greater in the wet grassland (1.7 ± 0.1 μmol m-2 s-1) compared to wet tundra (0.9 ± 0.2 μmol m-2 s-1) and dry tundra (1.2 ± 0.2 μmol m-2 s-1). Soil CO2 flux increased and decreased with seasonal warming and cooling of soil temperature. Although soil temperature was an important seasonal driver of soil CO2 flux rates, differences in mean seasonal soil CO2 flux rates among vegetation zones appeared to be a function of the

  4. Timing and nature of AMOC recovery across Termination 2 and magnitude of deglacial CO2 change

    NASA Astrophysics Data System (ADS)

    Deaney, Emily L.; Barker, Stephen; van de Flierdt, Tina

    2017-02-01

    Large amplitude variations in atmospheric CO2 were associated with glacial terminations of the Late Pleistocene. Here we provide multiple lines of evidence suggesting that the ~20 p.p.m.v. overshoot in CO2 at the end of Termination 2 (T2) ~129 ka was associated with an abrupt (<=400 year) deepening of Atlantic Meridional Overturning Circulation (AMOC). In contrast to Termination 1 (T1), which was interrupted by the Bølling-Allerød (B-A), AMOC recovery did not occur until the very end of T2, and was characterized by pronounced formation of deep waters in the NW Atlantic. Considering the variable influences of ocean circulation change on atmospheric CO2, we suggest that the net change in CO2 across the last 2 terminations was approximately equal if the transient effects of deglacial oscillations in ocean circulation are taken into account.

  5. Timing and nature of AMOC recovery across Termination 2 and magnitude of deglacial CO2 change

    PubMed Central

    Deaney, Emily L.; Barker, Stephen; van de Flierdt, Tina

    2017-01-01

    Large amplitude variations in atmospheric CO2 were associated with glacial terminations of the Late Pleistocene. Here we provide multiple lines of evidence suggesting that the ∼20 p.p.m.v. overshoot in CO2 at the end of Termination 2 (T2) ∼129 ka was associated with an abrupt (≤400 year) deepening of Atlantic Meridional Overturning Circulation (AMOC). In contrast to Termination 1 (T1), which was interrupted by the Bølling-Allerød (B-A), AMOC recovery did not occur until the very end of T2, and was characterized by pronounced formation of deep waters in the NW Atlantic. Considering the variable influences of ocean circulation change on atmospheric CO2, we suggest that the net change in CO2 across the last 2 terminations was approximately equal if the transient effects of deglacial oscillations in ocean circulation are taken into account. PMID:28239149

  6. Timing and nature of AMOC recovery across Termination 2 and magnitude of deglacial CO2 change.

    PubMed

    Deaney, Emily L; Barker, Stephen; van de Flierdt, Tina

    2017-02-27

    Large amplitude variations in atmospheric CO2 were associated with glacial terminations of the Late Pleistocene. Here we provide multiple lines of evidence suggesting that the ∼20 p.p.m.v. overshoot in CO2 at the end of Termination 2 (T2) ∼129 ka was associated with an abrupt (≤400 year) deepening of Atlantic Meridional Overturning Circulation (AMOC). In contrast to Termination 1 (T1), which was interrupted by the Bølling-Allerød (B-A), AMOC recovery did not occur until the very end of T2, and was characterized by pronounced formation of deep waters in the NW Atlantic. Considering the variable influences of ocean circulation change on atmospheric CO2, we suggest that the net change in CO2 across the last 2 terminations was approximately equal if the transient effects of deglacial oscillations in ocean circulation are taken into account.

  7. Testing surface gas monitoring methods at sites of natural and man-made CO2 seepage in Europe

    NASA Astrophysics Data System (ADS)

    Jones, D.; Lister, R.; Barkwith, A.; Barlow, T.; Shaw, R.; Strutt, M.; Lombardi, S.; Beaubien, S.; Annunziatellis, A.; Graziani, S.

    2011-12-01

    Useful lessons for monitoring techniques and strategies can be learned at natural CO2 seepage sites. Existing methods and new developments can be tested at such sites to assess how useful they would be at geological CO2 storage sites. Such testing is not possible at actual storage sites where there is no leakage. Experience has been gained at the natural CO2 seepage sites near Latera in Italy, the Laacher See in Germany and Florina in Greece. Studies have also been carried out at experimental CO2 injection sites in the UK and Norway and at landfill sites in the UK. The sites have been used as a testing ground for existing and new techniques including open path lasers, eddy covariance, CO2 monitoring stations, flux chambers and in situ and laboratory soil gas analysis. Natural CO2 seepage at the sites tends to occur at gas vents of restricted surface extent. Typically such vents have a diameter of metres to tens of metres. Whilst the vents may align along faults or fractures they occur at small discrete points on such features where permeability is higher. These appear commonly to be associated with fracture intersections. Venting therefore occurs over only a small fraction of the total area of the sites. By analogy this suggests that a surface monitoring strategy for a CO2 storage site needs to include cost effective screening methods that can cover large areas quickly but which are capable of finding small leakage targets. Soil gas concentrations and fluxes vary with time in response to factors such as temperature, pressure, wind speed and soil moisture. This gives rise to diurnal, seasonal and weather system related cycles. Seepage of CO2 can therefore vary over time and this implies the need for continuous monitoring techniques to avoid missing transient releases. Developing legislation for CO2 storage sites (such as the European Union Storage Directive) also requires the quantification of any detected CO2 leakage and this will require an understanding of

  8. CO2 adsorption properties of ion-exchanged zeolite Y prepared from natural clays

    NASA Astrophysics Data System (ADS)

    Djeffal, Nadjiba; Benbouzid, Mohammed; Boukoussa, Bouhadjar; Sekkiou, Housseyn; Bengueddach, Abdelkader

    2017-03-01

    Ordered microporous Y zeolite was successfully synthesized by hydrothermal treatment using metakaolin and Ludox (40% SiO2) as an aluminum and silica source respectively. The metakaolin was obtained by thermal treatment of Algerian kaolin. The obtained Y zeolite was exchanged by different cations such as Cu2+, Ni2+, Ca2+, Na+ and used for the CO2 adsorption at 0 °C. The structural features of the materials were determined by various physico-chemical techniques such as x-ray diffraction, nitrogen sorption at 77 K, Fourier transform infrared spectroscopy and scanning electronic microscopy. The CO2 adsorption at 0 °C was carried using a volumetric method. The adsorption isotherms of CO2 exhibit nonlinear concave curves and showed a high adsorption capacity for CO2 from the M-Y zeolites. The equilibrium CO2 adsorption capacity increase in the following order of Cu2+  <  Ni2+  <  Ca2+  <  Na+. The experimental isotherm data of the CO2 adsorption was best described by the Langmuir model giving a maximum adsorbed amount q m  =  77.57 cm3 · g-1 STP for Na-Y zeolite.

  9. Root Responses Along a Subambient to Elevated CO2 Gradient in a C3-C4 Grassland

    USDA-ARS?s Scientific Manuscript database

    Atmospheric CO2 (Ca) concentration has increased significantly during last 20,000 years, and is projected to double this century. Despite the importance of belowground processes in the global carbon cycle, community-level and single species root responses to rising Ca are poorly understood. We measu...

  10. Variations in Belowground Carbon Storage and Soil CO2 Flux Rates along a Wet Tropical Climate Gradient

    Treesearch

    Megan McGroddy; Whendee L. Silver

    2000-01-01

    We used a humid tropical elevation gradient to examine the relationships among climate, edaphic conditions, belowground carbon storage, and soil respiration rates. We also compared open and closed canopy sites to increase the range of microclimate conditions sampled along the gradient, and determine the effects of canopy openings on C and P storage, and C dynamics....

  11. Formation of submicron magnesite during reaction of natural forsterite in H2O-saturated supercritical CO2

    NASA Astrophysics Data System (ADS)

    Qafoku, Odeta; Hu, Jianzhi; Hess, Nancy J.; Hu, Mary Y.; Ilton, Eugene S.; Feng, Ju; Arey, Bruce W.; Felmy, Andrew R.

    2014-06-01

    Natural forsterite was reacted in bulk liquid water saturated with supercritical CO2 (scCO2) and scCO2 saturated with water at 35-80 °C and 90 atm. The solid reaction products were analyzed with nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), and confocal Raman spectroscopy. Two carbonate phases, nesquehonite (MgCO3·3H2O) and magnesite (MgCO3), were identified with the proportions of the two phases depending on experimental conditions. In liquid water saturated with scCO2, nesquehonite was the dominant carbonate phase at 35-80 °C with only a limited number of large, micron size magnesite particles forming at the highest temperature, 80 °C. In contrast, in scCO2 saturated with H2O magnesite formation was identified at all three temperatures: 35, 50, and 80 °C. Magnesite was the dominant carbonation reaction product at 50 and 80 °C, but nesquehonite was dominant at 35 °C. The magnesite particles formed under scCO2 saturated with H2O conditions exhibited an extremely uniform submicron grain-size and nearly identical rhombohedral morphologies at all temperatures. The distribution and form of the particles were not consistent with nucleation and growth on the forsterite surface.

  12. Formation of Submicron Magnesite during Reaction of Natural Forsterite in H2O-Saturated Supercritical CO2

    SciTech Connect

    Qafoku, Odeta; Hu, Jian Z.; Hess, Nancy J.; Hu, Mary Y.; Ilton, Eugene S.; Feng, Ju; Arey, Bruce W.; Felmy, Andrew R.

    2014-06-01

    Natural forsterite was reacted in a) liquid water saturated with supercritical CO2 (scCO2) and in b) H2O-saturated scCO2 at 35-80 °C and 90 atm. The solid reaction products were analyzed with nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), and confocal Raman spectroscopy. Two carbonate phases, nesquehonite (MgCO3.3H2O) and magnesite (MgCO3), were identified with the proportions of the two phases depending on experimental conditions. In water saturated with scCO2, nesquehonite was the dominant carbonate phase at 35-80 °C with only a limited number of large, micron size magnesite particles forming at the highest temperature, 80 °C. In contrast, in H2O-saturated scCO2 magnesite formation was identified at all three temperatures: 35 °, 50 °, and 80 °C. Magnesite was the dominant carbonation reaction product at 50 ° and 80 °C; but nesquehonite was dominant at 35 °C. The magnesite particles formed under H2O-saturated scCO2 conditions exhibited an extremely uniform submicron grain-size and nearly identical rhombohedral morphologies at all temperatures. The distribution and form of the particles were not consistent with epitaxial nucleation and growth on the forsterite surface.

  13. Natural volcanic CO2 seeps reveal future trajectories for host–microbial associations in corals and sponges

    PubMed Central

    Morrow, Kathleen M; Bourne, David G; Humphrey, Craig; Botté, Emmanuelle S; Laffy, Patrick; Zaneveld, Jesse; Uthicke, Sven; Fabricius, Katharina E; Webster, Nicole S

    2015-01-01

    Atmospheric carbon dioxide (CO2) levels are rapidly rising causing an increase in the partial pressure of CO2 (pCO2) in the ocean and a reduction in pH known as ocean acidification (OA). Natural volcanic seeps in Papua New Guinea expel 99% pure CO2 and thereby offer a unique opportunity to explore the effects of OA in situ. The corals Acropora millepora and Porites cylindrica were less abundant and hosted significantly different microbial communities at the CO2 seep than at nearby control sites <500 m away. A primary driver of microbial differences in A. millepora was a 50% reduction of symbiotic Endozoicomonas. This loss of symbiotic taxa from corals at the CO2 seep highlights a potential hurdle for corals to overcome if they are to adapt to and survive OA. In contrast, the two sponges Coelocarteria singaporensis and Cinachyra sp. were ∼40-fold more abundant at the seep and hosted a significantly higher relative abundance of Synechococcus than sponges at control sites. The increase in photosynthetic microbes at the seep potentially provides these species with a nutritional benefit and enhanced scope for growth under future climate scenarios (thus, flexibility in symbiosis may lead to a larger niche breadth). The microbial community in the apparently pCO2-sensitive sponge species S. massa was not significantly different between sites. These data show that responses to elevated pCO2 are species-specific and that the stability and flexibility of microbial partnerships may have an important role in shaping and contributing to the fitness and success of some hosts. PMID:25325380

  14. Natural volcanic CO2 seeps reveal future trajectories for host-microbial associations in corals and sponges.

    PubMed

    Morrow, Kathleen M; Bourne, David G; Humphrey, Craig; Botté, Emmanuelle S; Laffy, Patrick; Zaneveld, Jesse; Uthicke, Sven; Fabricius, Katharina E; Webster, Nicole S

    2015-03-17

    Atmospheric carbon dioxide (CO2) levels are rapidly rising causing an increase in the partial pressure of CO2 (pCO2) in the ocean and a reduction in pH known as ocean acidification (OA). Natural volcanic seeps in Papua New Guinea expel 99% pure CO2 and thereby offer a unique opportunity to explore the effects of OA in situ. The corals Acropora millepora and Porites cylindrica were less abundant and hosted significantly different microbial communities at the CO2 seep than at nearby control sites <500 m away. A primary driver of microbial differences in A. millepora was a 50% reduction of symbiotic Endozoicomonas. This loss of symbiotic taxa from corals at the CO2 seep highlights a potential hurdle for corals to overcome if they are to adapt to and survive OA. In contrast, the two sponges Coelocarteria singaporensis and Cinachyra sp. were ∼ 40-fold more abundant at the seep and hosted a significantly higher relative abundance of Synechococcus than sponges at control sites. The increase in photosynthetic microbes at the seep potentially provides these species with a nutritional benefit and enhanced scope for growth under future climate scenarios (thus, flexibility in symbiosis may lead to a larger niche breadth). The microbial community in the apparently pCO2-sensitive sponge species S. massa was not significantly different between sites. These data show that responses to elevated pCO2 are species-specific and that the stability and flexibility of microbial partnerships may have an important role in shaping and contributing to the fitness and success of some hosts.

  15. Hydroquinone and Quinone-Grafted Porous Carbons for Highly Selective CO2 Capture from Flue Gases and Natural Gas Upgrading.

    PubMed

    Wang, Jun; Krishna, Rajamani; Yang, Jiangfeng; Deng, Shuguang

    2015-08-04

    Hydroquinone and quinone functional groups were grafted onto a hierarchical porous carbon framework via the Friedel-Crafts reaction to develop more efficient adsorbents for the selective capture and removal of carbon dioxide from flue gases and natural gas. The oxygen-doped porous carbons were characterized with scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. CO2, CH4, and N2 adsorption isotherms were measured and correlated with the Langmuir model. An ideal adsorbed solution theory (IAST) selectivity for the CO2/N2 separation of 26.5 (298 K, 1 atm) was obtained on the hydroquinone-grafted carbon, which is 58.7% higher than that of the pristine porous carbon, and a CO2/CH4 selectivity value of 4.6 (298 K, 1 atm) was obtained on the quinone-grafted carbon (OAC-2), which represents a 28.4% improvement over the pristine porous carbon. The highest CO2 adsorption capacity on the oxygen-doped carbon adsorbents is 3.46 mmol g(-1) at 298 K and 1 atm. In addition, transient breakthrough simulations for CO2/CH4/N2 mixture separation were conducted to demonstrate the good separation performance of the oxygen-doped carbons in fixed bed adsorbers. Combining excellent adsorption separation properties and low heats of adsorption, the oxygen-doped carbons developed in this work appear to be very promising for flue gas treatment and natural gas upgrading.

  16. Gas Hazard from Natural CO2 Emissions in Central and Southern Italy.

    NASA Astrophysics Data System (ADS)

    Cardellini, C.; Chiodini, G.; Costa, A.; Avino, R.; Baldini, A.; Caliro, S.; Frondini, F.; Granieri, D.; Minopoli, C.; Morgantini, N.

    2006-12-01

    Recent studies at regional scale showed that the central and southern Italy are affected by an active and intense process of CO2 Earth degassing. Considering the deeply derived carbon dissolved in the groundwater of large regional aquifers, Chiodini et al. (2004) elaborated a regional map of CO2 Earth degassing, pointing out the presence of two large CO2 degassing structures (62000 km2) a northern one, the tuscan roman degassing structure (TRDS) and a southern one, the campanian degassing structure (CDS). The deeply derived CO2 released by these two structures was estimated in ~ 9.2 Mt/y (Chiodini et al., 2004). This amount, which is globally relevant being ~ 10% of the present-day total CO2 discharge from subaerial volcanoes of the Earth, is of low magnitude with respect to the amount of CO2 that is estimated to be injected in the storage sites. TRDS and CDS are characterized by the presence of many vents of cold CO2 rich gases and areas of anomalous soil diffuse degassing of CO2. The gas manifestations are generally fed by buried carbonate reservoirs, covered by low permeability formations, where the gas produced at depth accumulates before the expulsion at the surface. More than 100 gas emissions are located in the Italian territory and represent a serious hazard for humans and animals. Gas flow rates are very high. For example, the biggest gas emissions daily release into atmosphere hundreds of tons of CO2, amounts similar to those released by diffuse degassing from active volcanoes (CO2 fluxes from 6 t/d to 2800 t/d, mean of 430 t/d, Morner and Etiope, 2002). Under stable atmospheric conditions and/or in presence of topographic depressions, CO2 air concentration can reach high values resulting in lethal effects to humans or animals. The last lethal accident occurred in 2003 in Tuscany, at Mt. Amiata. However, the most dangerous gas emission is Mefite d'Ansanto, located in the Southern Apennine, where three persons were killed during 1990's and historical

  17. Elevated CO2: impact on diurnal patterns of photosynthesis in natural microbial ecosystems.

    PubMed

    Rothschild, L J

    1994-01-01

    Algae, including blue-green algae (cyanobacteria), are the major source of fixed carbon in many aquatic ecosystems. Previous work has shown that photosynthetic carbon fixation is often enhanced in the presence of additional carbon dioxide (CO2). This study was undertaken to determine if this CO2 fertilization effect extended to microbial mats, and, if so, at what times during the day might the addition of CO2 affect carbon fixation. Four microbial mats from diverse environments were selected, including mats from a hypersaline pond (area 5, Exportadora de Sal, Mexico), the marine intertidal (Lyngbya, Laguna Ojo de Liebre, Mexico), an acidic hotspring (Cyanidium, Nymph Creek, Yellowstone National Park), and an acidic stream at ambient temperature (Zygogonium, Yellowstone National Park). Carbon fixation in the absence of additional CO2 essentially followed the rising and falling sunlight levels, except that during the middle of the day there was a short dip in carbon fixation rates. The addition of CO2 profoundly enhanced carbon fixation rates during the daylight hours, including during the midday dip. Therefore, it is unlikely that the midday dip was due to photoinhibition. Surprisingly, enhancement of carbon fixation was often greatest in the early morning or late afternoon, times when carbon fixation would be most likely to be light limited.

  18. Elevated CO2: Impact on diurnal patterns of photosynthesis in natural microbial ecosystems

    NASA Technical Reports Server (NTRS)

    Rothschild, L. J.

    1994-01-01

    Algae, including blue-green algae (cyanobacteria), are the major source of fixed carbon in many aquatic ecosystems. Previous work has shown that photosynthetic carbon fixation is often enhanced in the presence of additional carbon dioxide (CO2). This study was undertaken to determine if this CO2 fertilization effect extended to microbial mats, and, if so, at what times during the day might the addition of CO2 affect carbon fixation. Four microbial mats from diverse environments were selected, including mats from a hypersaline pond (area 5, Exportadora de Sal, Mexico), the marine intertidal (Lyngbya, Laguna Ojo de Liebre, Mexico), an acidic hotspring (Cyanidium, Nymph Creek, Yellowstone National Park), and an acidic stream at ambient temperature (Zygogonium, Yellowstone National Park). Carbon fixation in the absence of additional CO2 essentially followed the rising and falling sunlight levels, except that during the middle of the day there was a short dip in carbon fixation rates. The addition of CO2 profoundly enhanced carbon fixation rates during the daylight hours, including during the midday dip. Therefore, it is unlikely that the midday dip was due to photoinhibition. Surprisingly, enhancement of carbon fixation was often greatest in the early morning or late afternoon, times when carbon fixation would be most likely to be light limited.

  19. Elevated CO2: Impact on diurnal patterns of photosynthesis in natural microbial ecosystems

    NASA Astrophysics Data System (ADS)

    Rothschild, L. J.

    1994-11-01

    Algae, including blue-green algae (cyanobacteria), are the major source of fixed carbon in many aquatic ecosystems. Previous work has shown that photosynthetic carbon fixation is often enhanced in the presence of additional carbon dioxide (CO2). This study was undertaken to determine if this CO2 fertilization effect extended to microbial mats, and, if so, at what times during the day might the addition of CO2 affect carbon fixation. Four microbial mats from diverse environments were selected, including mats from a hypersaline pond (area 5, Exportadora de Sal, Mexico), the marine intertidal (Lyngbya, Laguna Ojo de Liebre, Mexico), an acidic hotspring (Cyanidium, Nymph Creek, Yellowstone National Park), and an acidic stream at ambient temperature (Zygogonium, Yellowstone National Park). Carbon fixation in the absence of additional CO2 essentially followed the rising and failing sunlight levels, except that during the middle of the day there was a short dip in carbon fixation rates. The addition of CO2 profoundly enhanced carbon fixation rates during the daylight hours, including during the midday dip. Therefore, it is unlikely that the midday dip was due to photoinhibition. Surprisingly, enhancement of carbon fixation was often greatest in the early morning or late afternoon, times when carbon fixation would be most likely to be light limited.

  20. Elevated CO2: Impact on diurnal patterns of photosynthesis in natural microbial ecosystems

    NASA Technical Reports Server (NTRS)

    Rothschild, L. J.

    1994-01-01

    Algae, including blue-green algae (cyanobacteria), are the major source of fixed carbon in many aquatic ecosystems. Previous work has shown that photosynthetic carbon fixation is often enhanced in the presence of additional carbon dioxide (CO2). This study was undertaken to determine if this CO2 fertilization effect extended to microbial mats, and, if so, at what times during the day might the addition of CO2 affect carbon fixation. Four microbial mats from diverse environments were selected, including mats from a hypersaline pond (area 5, Exportadora de Sal, Mexico), the marine intertidal (Lyngbya, Laguna Ojo de Liebre, Mexico), an acidic hotspring (Cyanidium, Nymph Creek, Yellowstone National Park), and an acidic stream at ambient temperature (Zygogonium, Yellowstone National Park). Carbon fixation in the absence of additional CO2 essentially followed the rising and falling sunlight levels, except that during the middle of the day there was a short dip in carbon fixation rates. The addition of CO2 profoundly enhanced carbon fixation rates during the daylight hours, including during the midday dip. Therefore, it is unlikely that the midday dip was due to photoinhibition. Surprisingly, enhancement of carbon fixation was often greatest in the early morning or late afternoon, times when carbon fixation would be most likely to be light limited.

  1. Efficiency enhancement for natural gas liquefaction with CO2 capture and sequestration through cycles innovation and process optimization

    NASA Astrophysics Data System (ADS)

    Alabdulkarem, Abdullah

    Liquefied natural gas (LNG) plants are energy intensive. As a result, the power plants operating these LNG plants emit high amounts of CO2 . To mitigate global warming that is caused by the increase in atmospheric CO2, CO2 capture and sequestration (CCS) using amine absorption is proposed. However, the major challenge of implementing this CCS system is the associated power requirement, increasing power consumption by about 15--25%. Therefore, the main scope of this work is to tackle this challenge by minimizing CCS power consumption as well as that of the entire LNG plant though system integration and rigorous optimization. The power consumption of the LNG plant was reduced through improving the process of liquefaction itself. In this work, a genetic algorithm (GA) was used to optimize a propane pre-cooled mixed-refrigerant (C3-MR) LNG plant modeled using HYSYS software. An optimization platform coupling Matlab with HYSYS was developed. New refrigerant mixtures were found, with savings in power consumption as high as 13%. LNG plants optimization with variable natural gas feed compositions was addressed and the solution was proposed through applying robust optimization techniques, resulting in a robust refrigerant which can liquefy a range of natural gas feeds. The second approach for reducing the power consumption is through process integration and waste heat utilization in the integrated CCS system. Four waste heat sources and six potential uses were uncovered and evaluated using HYSYS software. The developed models were verified against experimental data from the literature with good agreement. Net available power enhancement in one of the proposed CCS configuration is 16% more than the conventional CCS configuration. To reduce the CO2 pressurization power into a well for enhanced oil recovery (EOR) applications, five CO2 pressurization methods were explored. New CO2 liquefaction cycles were developed and modeled using HYSYS software. One of the developed

  2. Response of bacterioplankton community structure to an artificial gradient of pCO2 in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Zhang, R.; Xia, X.; Lau, S. C. K.; Motegi, C.; Weinbauer, M. G.; Jiao, N.

    2013-06-01

    In order to test the influences of ocean acidification on the ocean pelagic ecosystem, so far the largest CO2 manipulation mesocosm study (European Project on Ocean Acidification, EPOCA) was performed in Kings Bay (Kongsfjorden), Spitsbergen. During a 30 day incubation, bacterial diversity was investigated using DNA fingerprinting and clone library analysis of bacterioplankton samples. Terminal restriction fragment length polymorphism (T-RFLP) analysis of the PCR amplicons of the 16S rRNA genes revealed that general bacterial diversity, taxonomic richness and community structure were influenced by the variation of productivity during the time of incubation, but not the degree of ocean acidification. A BIOENV analysis suggested a complex control of bacterial community structure by various biological and chemical environmental parameters. The maximum apparent diversity of bacterioplankton (i.e., the number of T-RFs) in high and low pCO2 treatments differed significantly. A negative relationship between the relative abundance of Bacteroidetes and pCO2 levels was observed for samples at the end of the experiment by the combination of T-RFLP and clone library analysis. Our study suggests that ocean acidification affects the development of bacterial assemblages and potentially impacts the ecological function of the bacterioplankton in the marine ecosystem.

  3. The response of coastal surface ocean pH to naturally changing atmospheric pCO2

    NASA Astrophysics Data System (ADS)

    Chrystal, A.; Zimdahl, N.; Paytan, A.

    2013-12-01

    Average global surface ocean pH is rapidly decreasing in response to increasing atmospheric pCO2 concentrations. The rate of acidification may be elevated in regions of strong coastal upwelling due to the combined impacts of atmospheric pCO2 and upwelling of deep water with a respired carbon signature. Since coastal upwelling regions support economically important fisheries, it is important that we understand the significance of these changes. Of essence is an understanding of the scale of regional pH change associated with natural atmospheric pCO2 oscillations at multiple time scales. Reconstructions of past pH variations from boron isotopes (δ11B) of planktonic foraminifera or other carbonate secreting organisms will provide valuable insight into the natural variability in pH regime in the ecologically and economically important California margin region, and facilitate predictions of pH response in this and other coastal upwelling systems. In this study, we will analyze δ11B in the tests of surface-dwelling planktic foraminifera (G. bulloides) to reconstruct surface water pH. We will compare surface water pH with ice-core atmospheric pCO2 records from the last several glacial cycles to better understand the natural pH response to changing atmospheric pCO2 in a coastal upwelling system. We will present a comparison between glacial and interglacial samples from site 1012 (East Cortez Basin). We hope to produce a record of high enough time resolution that the rate of pH change associated with atmospheric pCO2 changes can also be assessed, but in some sections of the core low foraminiferal abundances may force a reduction in record resolution.

  4. Advanced Reservoir Characterization and Evaluation of CO2 Gravity Drainage in the Naturally Fractured Spraberry Trend Area, Class III

    SciTech Connect

    Knight, Bill; Schechter, David S.

    2002-07-26

    The goal of this project was to assess the economic feasibility of CO2 flooding the naturally fractured Spraberry Trend Area in west Texas. This objective was accomplished through research in four areas: (1) extensive characterization of the reservoirs, (2) experimental studies of crude oil/brine/rock (COBR) interactions in the reservoirs, (3) reservoir performance analysis, and (4) experimental investigations on CO2 gravity drainage in Spraberry whole cores. This provides results of the final year of the six-year project for each of the four areas.

  5. Advanced Reservoir Characterization and Evaluation of CO2 Gravity Drainage in the Naturally Fractured Spraberry Trend Area

    SciTech Connect

    McDonald, Paul; Schechter, David S.

    1999-11-01

    The overall goal of this project was to assess the economic feasibility of CO2 flooding the naturally fractured Spraberry Trend Area in West Texas. This objective was accomplished by conducting research in four areas: (1) extensive characterization of the reservoirs, (2) experimental studies of crude oil/brine/rock (COBR) interaction in the reservoirs, (3) analytical and numerical simulation of Spraberry reservoirs, and, (4) experimental investigations on CO2 gravity drainage in Spraberry whole cores. Additionally, a ten (10) acre field demonstration pilot project is part of this project. This report discusses the activity, during the third calendar quarter (July through September) of 1998 (fourth quarter of the projects fiscal year).

  6. Characterizing Microbial Diversity and Function in Natural Subsurface CO2 Reservoir Systems for Applied Use in Geologic Carbon Sequestration Environments

    NASA Astrophysics Data System (ADS)

    Freedman, A.; Thompson, J. R.

    2013-12-01

    The injection of CO2 into geological formations at quantities necessary to significantly reduce CO2 emissions will represent an environmental perturbation on a continental scale. The extent to which biological processes may play a role in the fate and transport of CO2 injected into geological formations has remained an open question due to the fact that at temperatures and pressures associated with reservoirs targeted for sequestration CO2 exists as a supercritical fluid (scCO2), which has generally been regarded as a sterilizing agent. Natural subsurface accumulations of CO2 serve as an excellent analogue for studying the long-term effects, implications and benefits of CO2 capture and storage (CCS). While several geologic formations bearing significant volumes of nearly pure scCO2 phases have been identified in the western United States, no study has attempted to characterize the microbial community present in these systems. Because the CO2 in the region is thought to have first accumulated millions of years ago, it is reasonable to assume that native microbial populations have undergone extensive and unique physiological and behavioral adaptations to adjust to the exceedingly high scCO2 content. Our study focuses on the microbial communities associated with the dolomite limestone McElmo Dome scCO2 Field in the Colorado Plateau region, approximately 1,000 m below the surface. Fluid samples were collected from 10 wells at an industrial CO2 production facility outside Cortez, CO. Subsamples preserved on site in 3.7% formaldehyde were treated in the lab with Syto 9 green-fluorescent nucleic acid stain, revealing 3.2E6 to 1.4E8 microbial cells per liter of produced fluid and 8.0E9 cells per liter of local pond water used in well drilling fluids. Extracted DNAs from sterivex 0.22 um filters containing 20 L of sample biomass were used as templates for PCR targeting the 16S rRNA gene. 16S rRNA amplicons from these samples were cloned, sequenced and subjected to microbial

  7. Insights into the ecological effects of deep ocean CO2 enrichment: The impacts of natural CO2 venting at Loihi seamount on deep sea scavengers

    NASA Astrophysics Data System (ADS)

    Vetter, Eric W.; Smith, Craig R.

    2005-09-01

    Hydrothermal vents on Loihi seamount near Hawaii emit 5000-100,000 t/yr of CO2 at water depths of 1200-1300 m, yielding CO2 concentrations as high as 418 mol/m3. Because CO2 is the dominant toxic component of these vent fluids, Loihi provides an extraordinary setting in which to explore the effects of sustained CO2 enrichment on deep sea organisms and ecological processes. We used the Pisces IV submersible to manipulate baited traps and bait parcels in Loihi's plume to explore the effects of elevated CO2 on the feeding and behavior of typical deep sea scavengers. Necrophagous lysianassid amphipods (Eurythenes cf. obesus) and synaphobranchid eels were unusually abundant in the vicinity of Loihi's vents, suggesting that the CO2-rich plumes rising above Loihi may enhance the flux of carrion to the deep sea floor. Amphipods exposed to diluted vent waters with a mean pH of 6.3 (minimum 5.7) and temperature of 5.0°C became very active within seconds and then became narcotized over timescales of 2-15 min. Following 60 min of plume exposure, all amphipods revived within 30 min of removal from the plume and remained active until warmed to 10°C during submersible ascent into ocean surface waters. Open bait parcels placed in similar CO2 plumes were avoided by amphipods and fish, suggesting that they could detect either the elevated CO2 concentrations or other environmental parameters (e.g., temperature). Our results suggest that at least some scavenging deep sea amphipods may be able to escape relatively concentrated CO2 plumes (i.e., they do not become narcotized for several minutes) and that they may revive following 1 hour exposure to an oscillating CO2 plume (e.g., one meandering in a tidal current). In addition, our results suggest that scavenging amphipods and synaphobranchid eels may be able to detect and avoid intoxicating levels of CO2 resulting from deep ocean injection of CO2 and that specialized components of the deep sea fauna (e.g., some hydrothermal vent

  8. Laboratory investigations of weathering of soils from Mammoth Mountain, CA, a naturally CO2-impacted field site.

    PubMed

    Sanchez, Helen; Menezes, Gustavo; Ellis, Andre; Espinosa-Villegas, Claudia; Khachikian, Crist

    2014-10-21

    The potential impacts of CO2 leakage from a natural subsurface reservoir on soil and water quality were studied. Field measurements of soil pore CO2 concentrations and visual inspection of plants at Mammoth Mountain, CA, allowed the demarcation of tree-kill and non-tree-kill zones, with CO2 concentrations >100,000 ppm and ∼ 1,000 ppm, respectively. Soils collected from six sites along a transect stretching from the center of the tree-kill zone to an equidistant point into the non-tree-kill zone were analyzed for surface area and organic carbon content. Batch and column leaching tests were conducted to determine the extent of weathering induced by the presence of CO2 in the aqueous solution. Soils deep into the tree-kill area exhibited significantly higher surface areas (10.67 m(2)/g vs 2.53 m(2)/g) and lower organic carbon content (9,550 mg/kg vs 35,550 mg/kg). Batch results indicated that lower pH values (∼ 2) released higher concentrations of Mg, Si, Fe, and As, while, for soils in the tree-kill zone, longer-term batch results indicated higher releases at the higher pH of 5.5. Column experiments were used to compare the effects of pH adjusted using HCl vs CO2. For pore volumes (PV) < 100, CO2 enhanced trace element release. For 100 < PV < 10,000 concentrations of elements in the two systems were equivalent and steady. At PV > 10,000, after a drop in pH in the CO2 system, larger amounts of Fe and As were released, suggesting a CO2-induced dissolution of Fe-silicates/clays and/or reductive dissolution of Fe(3+) that releases Fe-bound arsenic. The specific role of pore water-dissolved CO2 on the release of trace elements is hitherto unknown. However, interactions of pore-water CO2 and the minerals in the Mammoth Mountain soils can cause the release of environmental pollutants.

  9. Higher fungal diversity is correlated with lower CO2 emissions from dead wood in a natural forest

    PubMed Central

    Yang, Chunyan; Schaefer, Douglas A.; Liu, Weijie; Popescu, Viorel D.; Yang, Chenxue; Wang, Xiaoyang; Wu, Chunying; Yu, Douglas W.

    2016-01-01

    Wood decomposition releases almost as much CO2 to the atmosphere as does fossil-fuel combustion, so the factors regulating wood decomposition can affect global carbon cycling. We used metabarcoding to estimate the fungal species diversities of naturally colonized decomposing wood in subtropical China and, for the first time, compared them to concurrent measures of CO2 emissions. Wood hosting more diverse fungal communities emitted less CO2, with Shannon diversity explaining 26 to 44% of emissions variation. Community analysis supports a ‘pure diversity’ effect of fungi on decomposition rates and thus suggests that interference competition is an underlying mechanism. Our findings extend the results of published experiments using low-diversity, laboratory-inoculated wood to a high-diversity, natural system. We hypothesize that high levels of saprotrophic fungal biodiversity could be providing globally important ecosystem services by maintaining dead-wood habitats and by slowing the atmospheric contribution of CO2 from the world’s stock of decomposing wood. However, large-scale surveys and controlled experimental tests in natural settings will be needed to test this hypothesis. PMID:27553882

  10. About how to capture and exploit the CO2 surplus that nature, per se, is not capable of fixing.

    PubMed

    Godoy, Manuel S; Mongili, Beatrice; Fino, Debora; Prieto, M Auxiliadora

    2017-09-01

    Human activity has been altering many ecological cycles for decades, disturbing the natural mechanisms which are responsible for re-establishing the normal environmental balances. Probably, the most disrupted of these cycles is the cycle of carbon. In this context, many technologies have been developed for an efficient CO2 removal from the atmosphere. Once captured, it could be stored in large geological formations and other reservoirs like oceans. This strategy could present some environmental and economic problems. Alternately, CO2 can be transformed into carbonates or different added-value products, such as biofuels and bioplastics, recycling CO2 from fossil fuel. Currently different methods are being studied in this field. We classified them into biological, inorganic and hybrid systems for CO2 transformation. To be environmentally compatible, they should be powered by renewable energy sources. Although hybrid systems are still incipient technologies, they have made great advances in the recent years. In this scenario, biotechnology is the spearhead of ambitious strategies to capture CO2 and reduce global warming. © 2017 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  11. Dynamics of CO2- radiation defects in natural calcite studied by ESR, electron spin echo and electron spin relaxation

    NASA Astrophysics Data System (ADS)

    Wencka, M.; Lijewski, S.; Hoffmann, S. K.

    2008-06-01

    ESR spectra were recorded in the X-band (9.6 GHz) and in the W-band (94 GHz) and electron spin relaxation was measured by electron spin echo (ESE) in the temperature range 4.2-300 K for radicals in natural calcite samples obtained from a cave stalactite and a dripstone layer. Four types of carbonate radical spectra and two sulfate radical spectra were identified and high accuracy g-factors were derived. Time and temperature behaviour of the spectra show that the dominating CO2- radicals are rigidly bonded or undergo free reorientations, whereas CO3-, SO2- and SO3- only undergo free reorientations. Below 200 K the free reorientations of CO2- are suppressed and a hindered rotation around single local axis appears. The ESE detected spectrum proves that the lines of free rotating radicals are homogeneously broadened, thus they cannot participate in electron spin echo formation. Spin-lattice relaxation data show that CO2- radicals are decoupled from lattice phonons and relax via local mode tunnelling motion between inequivalent oxygen positions of CO2- molecules. The tunnelling appears in two excited vibrational states of energy 71 and 138 cm-1. Librational motions of CO2- molecules were detected by electron spin echo decay (phase relaxation) with energy 153 cm-1. Two kinds of impurity hydrogen atoms were distinguished from ESEEM: in-water inclusions and water coordinated to the calcium ions.

  12. Trace element profiles of the sea anemone Anemonia viridis living nearby a natural CO2 vent

    PubMed Central

    Borell, Esther M.; Fine, Maoz; Shaked, Yeala

    2014-01-01

    Ocean acidification (OA) is not an isolated threat, but acts in concert with other impacts on ecosystems and species. Coastal marine invertebrates will have to face the synergistic interactions of OA with other global and local stressors. One local factor, common in coastal environments, is trace element contamination. CO2 vent sites are extensively studied in the context of OA and are often considered analogous to the oceans in the next few decades. The CO2 vent found at Levante Bay (Vulcano, NE Sicily, Italy) also releases high concentrations of trace elements to its surrounding seawater, and is therefore a unique site to examine the effects of long-term exposure of nearby organisms to high pCO2 and trace element enrichment in situ. The sea anemone Anemonia viridis is prevalent next to the Vulcano vent and does not show signs of trace element poisoning/stress. The aim of our study was to compare A. viridis trace element profiles and compartmentalization between high pCO2 and control environments. Rather than examining whole anemone tissue, we analyzed two different body compartments—the pedal disc and the tentacles, and also examined the distribution of trace elements in the tentacles between the animal and the symbiotic algae. We found dramatic changes in trace element tissue concentrations between the high pCO2/high trace element and control sites, with strong accumulation of iron, lead, copper and cobalt, but decreased concentrations of cadmium, zinc and arsenic proximate to the vent. The pedal disc contained substantially more trace elements than the anemone’s tentacles, suggesting the pedal disc may serve as a detoxification/storage site for excess trace elements. Within the tentacles, the various trace elements displayed different partitioning patterns between animal tissue and algal symbionts. At both sites iron was found primarily in the algae, whereas cadmium, zinc and arsenic were primarily found in the animal tissue. Our data suggests that A

  13. Trace element profiles of the sea anemone Anemonia viridis living nearby a natural CO2 vent.

    PubMed

    Horwitz, Rael; Borell, Esther M; Fine, Maoz; Shaked, Yeala

    2014-01-01

    Ocean acidification (OA) is not an isolated threat, but acts in concert with other impacts on ecosystems and species. Coastal marine invertebrates will have to face the synergistic interactions of OA with other global and local stressors. One local factor, common in coastal environments, is trace element contamination. CO2 vent sites are extensively studied in the context of OA and are often considered analogous to the oceans in the next few decades. The CO2 vent found at Levante Bay (Vulcano, NE Sicily, Italy) also releases high concentrations of trace elements to its surrounding seawater, and is therefore a unique site to examine the effects of long-term exposure of nearby organisms to high pCO2 and trace element enrichment in situ. The sea anemone Anemonia viridis is prevalent next to the Vulcano vent and does not show signs of trace element poisoning/stress. The aim of our study was to compare A. viridis trace element profiles and compartmentalization between high pCO2 and control environments. Rather than examining whole anemone tissue, we analyzed two different body compartments-the pedal disc and the tentacles, and also examined the distribution of trace elements in the tentacles between the animal and the symbiotic algae. We found dramatic changes in trace element tissue concentrations between the high pCO2/high trace element and control sites, with strong accumulation of iron, lead, copper and cobalt, but decreased concentrations of cadmium, zinc and arsenic proximate to the vent. The pedal disc contained substantially more trace elements than the anemone's tentacles, suggesting the pedal disc may serve as a detoxification/storage site for excess trace elements. Within the tentacles, the various trace elements displayed different partitioning patterns between animal tissue and algal symbionts. At both sites iron was found primarily in the algae, whereas cadmium, zinc and arsenic were primarily found in the animal tissue. Our data suggests that A. viridis

  14. CO2-efflux measurements for evaluating source zone natural attenuation rates in a petroleum hydrocarbon contaminated aquifer.

    PubMed

    Sihota, Natasha J; Singurindy, Olga; Mayer, K Ulrich

    2011-01-15

    In order to gain regulatory approval for source zone natural attenuation (SZNA) at hydrocarbon-contaminated sites, knowledge regarding the extent of the contamination, its tendency to spread, and its longevity is required. However, reliable quantification of biodegradation rates, an important component of SZNA, remains a challenge. If the rate of CO(2) gas generation associated with contaminant degradation can be determined, it may be used as a proxy for the overall rate of subsurface biodegradation. Here, the CO(2)-efflux at the ground surface is measured using a dynamic closed chamber (DCC) method to evaluate whether this technique can be used to assess the areal extent of the contaminant source zone and the depth-integrated rate of contaminant mineralization. To this end, a field test was conducted at the Bemidji, MN, crude oil spill site. Results indicate that at the Bemidji site the CO(2)-efflux method is able to both delineate the source zone and distinguish between the rates of natural soil respiration and contaminant mineralization. The average CO(2)-efflux associated with contaminant degradation in the source zone is estimated at 2.6 μmol m(-2) s(-1), corresponding to a total petroleum hydrocarbon mineralization rate (expressed as C(10)H(22)) of 3.3 g m(-2) day(-1).

  15. Radial growth rate increases in naturally occurring ponderosa pine trees: a late-20th century CO2 fertilization effect?

    PubMed

    Soulé, Peter T; Knapp, Paul A

    2006-01-01

    The primary objective of this study was to determine if gradually increasing levels of atmospheric CO2, as opposed to 'step' increases commonly employed in controlled studies, have a positive impact on radial growth rates of ponderosa pine (Pinus ponderosa) in natural environments, and to determine the spatial extent and variability of this growth enhancement. We developed a series of tree-ring chronologies from minimally disturbed sites across a spectrum of environmental conditions. A series of difference of means tests were used to compare radial growth post-1950, when the impacts of rising atmospheric CO2 are best expressed, with that pre-1950. Spearman's correlation was used to relate site stress to growth-rate changes. Significant increases in radial growth rates occurred post-1950, especially during drought years, with the greatest increases generally found at the most water-limited sites. Site harshness is positively related to enhanced radial growth rates. Atmospheric CO2 fertilization is probably operative, having a positive effect on radial growth rates of ponderosa pine through increasing water-use efficiency. A CO2-driven growth enhancement may affect ponderosa pine growing under both natural and controlled conditions.

  16. Aboveground net primary productivity and rainfall use efficiency of grassland on three soils after two years of exposure to a subambient to superambient CO2 gradient.

    NASA Astrophysics Data System (ADS)

    Fay, P. A.; Polley, H. W.; Jin, V. L.

    2008-12-01

    Atmospheric CO2 concentrations (CA) have increased by about 100 μL L-1 over the last 250 years to ~ 380 μL L-1, the highest values in the last half-million years, and CA is expected to continue to increase to greater than 500 μL L-1 by 2100. CO2 enrichment has been shown to affect many ecosystem processes, but experiments typically examine only two or a few levels of CA, and are typically constrained to one soil type. However, soil hydrologic properties differ across the landscape. Therefore, variation in the impacts of increasing CA on ecosystem function on different soil types must be understood to model and forecast ecosystem function under future CA and climate scenarios. Here we evaluate the aboveground net primary productivity (ANPP) of grassland plots receiving equal rainfall inputs (from irrigation) and exposed to a continuous gradient (250 to 500 μL L-1) of CA in the Lysimeter CO2 Gradient Experiment in central Texas, USA. Sixty intact soil monoliths (1 m2 x 1.5 m deep) taken from three soil types (Austin silty clay, Bastrop sandy loam, Houston clay) and planted to seven native tallgrass prairie grasses and forbs were exposed to the CA gradient beginning in 2006. Aboveground net primary productivity was assessed by end of season (November) harvest of each species in each monolith. Total ANPP of all species was 35 to 50% greater on Bastrop and Houston soils compared to Austin soils in both years (p < 0.0001), suggesting greater rainfall use efficiency on these soils despite lower water holding capacity of the Bastrop soils. On the Austin soil, grasses produced 2.7 fold more biomass than forbs, compared to only 30% more grass biomass on the Houston soil (p = 0.002), suggesting that grass dominance of community and ecosystem processes differed strongly among the soils. Total ANPP was strongly responsive to the CO2 gradient, with mean ANPP increasing from 260 g m- 2 at 250 μL L-1 CA to 455 g m-2 at 500 μL L-1 (p< 0.0001), suggesting greater overall

  17. Investigation of Efficiency Improvements During CO2 Injection in Hydraulically and Naturally Fractured Reservoirs

    SciTech Connect

    Schechter, David S.; Vance, Harold

    2003-03-10

    The objective of this project was to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in less efficient CO2 flooding in heterogeneous or fracture-dominated reservoirs. This report provided results of the second semi-annual technical progress report that consists of three different topics.

  18. 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

  19. A degassing instrument for analysing CO2 dissolved in natural water

    NASA Astrophysics Data System (ADS)

    Durham, Brian; Pfrang, Christian

    2017-04-01

    Arising from our EGU 2017 presentation (http://meetingorganizer.copernicus.org/EGU2016/posters/20564, X2 352), interest has been expressed in its application to the analysis of the hydrocarbonate ion [HCO3-] in atmospheric water. Arising from the historic difficulty in analysing the aqueous [HCO3-] ion ('it is in all our reagents', pers. comm. UK laboratory) the classic determination has been to measure a suite of other anions and cations including [H+] via pH, and to treat the balance of negative charge as a measure of [HCO3-]. From this balance, dissolved CO2 can be inferred via the dissociation constant as published for pure water. CO2 + H2O ⇓♢[HCO3-] + [H+] K1 = 4.2 x 10-7 Our EGU 2016 presentation sought to determine how the ionic environment in 263 UK rain samples can influence the above equilibrium, which is work in progress. In the mean time we have received the following expression of interest from an atmospheric science advisory group. …….. is very interested in the role of H-carbonate in the ion balance of precipitation. They have had some discussions recently about the best approach to infer H-carbonate currently discussing the possibility of sending you samples from other locations for analysis. We have duly offered to use our degassing instrument to corroborate current analyses in a batch of 'blind' samples, and to provide a design for a basic degasser that water quality laboratories could evaluate in house. This paper therefore presents a circuit for degassing CO2 from water samples irrespective of whether in atmospheric equilibrium or supersaturated, including a prototype 4-way distribution and collection valve which it is hoped will make the analysis intuitive and therefore open to automation.

  20. Rapid, Long-term Monitoring of CO2 Concentration and δ13CO2 at CCUS Sites Allows Discrimination of Leakage Patterns from Natural Background Values

    NASA Astrophysics Data System (ADS)

    Galfond, B.; Riemer, D. D.; Swart, P. K.

    2014-12-01

    In order for Carbon Capture Utilization and Storage (CCUS) to gain wide acceptance as a method for mitigating atmospheric CO2 concentrations, schemes must be devised to ensure that potential leakage is detected. New regulations from the US Environmental Protection Agency require monitoring and accounting for Class VI injection wells, which will remain a barrier to wide scale CCUS deployment until effective and efficient monitoring techniques have been developed and proven. Monitoring near-surface CO2 at injection sites to ensure safety and operational success requires high temporal resolution CO2 concentration and carbon isotopic (δ13C) measurements. The only technologies currently capable of this rapid measurement of δ13C are optical techniques such as Cavity Ringdown Spectroscopy (CRDS). We have developed a comprehensive remote monitoring approach using CRDS and a custom manifold system to obtain accurate rapid measurements from a large sample area over an extended study period. Our modified Picarro G1101-i CRDS allows for automated rapid and continuous field measurement of δ13CO2 and concentrations of relevant gas species. At our field site, where preparations have been underway for Enhanced Oil Recovery (EOR) operations, we have been able to measure biogenic effects on a diurnal scale, as well as variation due to precipitation and seasonality. Taking these background trends into account, our statistical treatment of real data has been used to improve signal-to-noise ratios by an order of magnitude over published models. Our system has proven field readiness for the monitoring of sites with even modest CO2 fluxes.

  1. Photosynthetic Water Use Efficiency in it Sorghastrum nutans (C4) and it Solidago canadensis (C3) in Three Soils Along a CO2 Concentration Gradient

    NASA Astrophysics Data System (ADS)

    Fay, P. A.; Hui, D.; Procter, A.; Johnson, H. B.; Polley, H. W.; Jackson, R. B.

    2006-12-01

    The water use efficiency (WUE) of leaf photosynthetic carbon uptake is a key regulator of ecosystem carbon cycles and is strongly sensitive to atmospheric carbon dioxide concentrations [CO2]. However WUE responses to [CO2] typically differ between C3 and C4 species and may differ on varying soil types because of differences in soil moisture retention and plant uptake efficiency. We measured leaf-level photosynthesis (ACO2), stomatal conductance (gS), and transpiration (E) with an infrared gas analyzer to estimate WUE for the C4 grass Sorghastrum nutans and the C3 forb Solidago canadensis in constructed grassland species assemblages growing in three soils arrayed along a 200 560 ppm [CO2] gradient in the LYCOG Experiment, in central Texas, USA. LYCOG consists of eighty intact soil monoliths (1 m X 1 m X 1.5 m) representing 3 soil series, Austin (Udorthentic Haplustolls, a mollisol), Bastrop (Udic Paleustalfs, a sandy loam alfisol) and Houston Black (Udic Haplusterts, a vertisol). The monoliths were vegetated by transplanting 8 native perennial prairie species (5 grasses and 3 forbs), including S. nutans and S. canadensis. Both are abundant and widespread; S. nutans is a dominant species throughout much of North American tallgrass prairie, and S. canadensis is one of the most abundant and widespread forbs in North America. ACO2, gS, and E were measured three times during the growing season. Dark-adapted chlorophyll fluorescence (FvFm) was measured concurrently to assess photosynthetic capacity, and leaf water potential (Ψ leaf) and soil water content were measured to assess plant water status and soil moisture availability. WUE increased strongly (p< 0.0001) at higher [CO2], due to a combination of decreasing E due to decreased gS (p ≤ 0.0005) and increasing ACO2 (p = 0.0055). This pattern was the same in both species (species x [CO2] ns). There was a corresponding increase in Ψ leaf (p = 0.01) at higher [CO2], but no [CO2] effect on FvFm. E and gS were lower on

  2. Biosphere-atmosphere exchange of CO2, water and energy in natural savannah in Burkina Faso (W Africa)

    NASA Astrophysics Data System (ADS)

    Falk, U.; Bruemmer, C.; Oltchev, A.; Brueggemann, N.; Szarzynski, J.; Papen, H.

    2007-12-01

    Tropical savannahs cover an area of 17 x 106 km2 worldwide. Their role in the global greenhouse gas budget still remains uncertain. In the past large parts of the former native African savannahs have been converted to agricultural land. To contribute to evaluating greenhouse gas exchange of tropical savannah ecosystems, especially in sub- Saharan Africa, biosphere-atmosphere exchange of N2O, CH4 and CO2 was quantified in natural savannah and in rainfed agricultural land in Burkina Faso by means of eddy covariance (EC) and chamber measurements. An EC tower was established in a nature reserve to determine the net ecosystem exchange of CO2 (NEEC) and energy fluxes from November 2004 to October 2006. A Soil-Vegetation-Atmosphere-Transport (SVAT) model MixFor-SVAT (Oltchev et al., 2002) was used to compute the heat exchange between canopy and atmosphere, to conduct a plausibility test to the measured fluxes, and to investigate the component fluxes. MixFor-SVAT is a multi- layer model that describes the vertical distribution of radiation, momentum, energy and matter fluxes within and above mono- or multi-specific tree stands at 30-min resolution. Water fluxes in the plants are computed using a non-steady-state approach (HUNT et al., 1991). The EC measurements revealed that the natural savannah acted as a small C source in the dry period, whereas large amounts of CO2-C were bound during the rainy seasons, particularly from June to September. The balance of the first year of our observations indicated a C uptake of 373 g m-2 of the ecosystem, which is comparable to deciduous forests in Europe. The CO2 fluxes showed clear diurnal patterns with the highest uptake rates at noon (up to 1 mg m-2 s-1 in July and August) and a permanent slight release to the atmosphere during night-time.

  3. Nature and Dynamics of Carbon Accrued in a Forest Soil During Five Years of Atmospheric CO2 Enrichment

    NASA Astrophysics Data System (ADS)

    Jastrow, J. D.; O'Brien, S. L.; Dria, K. J.; Moran, K. K.; Filley, T. R.; Boutton, T. W.

    2004-12-01

    The potential for enhanced soil C storage to partially offset rising atmospheric CO2 concentrations is being evaluated by long-term field CO2 enrichment experiments. Although plant productivity is often stimulated in such experiments, the fate of increased detrital inputs to soil has yet to be definitively resolved, in part because detecting changes in soil C against the relatively large, spatially heterogeneous pool of existing soil organic matter has proven difficult. Even when significant changes in whole soil C are evident, predictions of the potential for long-term sequestration will require detailed studies of C dynamics and stability in functionally meaningful soil organic matter pools. In our studies at the free-air CO2 enrichment (FACE) experiment on a sweetgum (Liquidambar styraciflua L.) forest plantation in Oak Ridge, Tennessee, we are using (1) repeated sampling over time, (2) the isotopic tracer provided by the highly depleted 13C signature of the CO2 source used for fumigation, and (3) physical and chemical fractionation procedures to determine the fate and dynamics of FACE-derived C inputs to soil organic matter. After five years of CO2 enrichment, soil C accumulated at a linear rate in both unprotected and aggregate-protected pools, suggesting that additional C inputs were being processed and cycled in much the same manner as under ambient conditions. However, selective analysis of the biopolymer composition (lignin, suberin, and cutin) and oxidation state of the organic matter in physically and chemically isolated soil fractions will be used to assess the source, nature and potential stability of the C accrued in protected and unprotected pools.

  4. Multi-isotope tracing of CO2 leakage and water-rock interaction in a natural CCS analogue.

    NASA Astrophysics Data System (ADS)

    Kloppmann, Wolfram; Gemeni, Vasiliki; Lions, Julie; Koukouzas, Nikolaos; Humez, Pauline; Vasilatos, Charalampos; Millot, Romain; Pauwels, Hélène

    2015-04-01

    Natural analogues of CO2 accumulation and, potentially, leakage, provide a highly valuable opportunity to study (1) geochemical processes within a CO2-reservoir and the overlying aquifers or aquicludes, i.e. gas-water-rock interactions, (2) geology and tightness of reservoirs over geological timescales, (3) potential or real leakage pathways, (3) impact of leakage on shallow groundwater resources quality, and (4) direct and indirect geochemical indicators of gas leakage (Lions et al., 2014, Humez et al., 2014). The Florina Basin in NW Macedonia, Greece, contains a deep CO2-rich aquifer within a graben structure. The graben filling consists of highly heterogeneous Neogene clastic sediments constituted by components from the adjacent massifs including carbonates, schists, gneiss as well as some ultramafic volcanic rocks. Clay layers are observed that isolate hydraulically the deep, partly artesian aquifer. Organic matter, in form of lignite accumulations, is abundant in the Neogene series. The underlying bedrocks are metamorphic carbonates and silicate rocks. The origin of the CO2 accumulation is controversial (deep, partially mantle-derived D'Allessandro et al., 2008 or resulting from thermal decomposition of carbonates, Hatziyannis and Arvanitis, 2011). Groundwaters have been sampled from springs and borewells over 3 years at different depths. First results on major, minor and trace elements give evidence of water-rock interaction, mainly with carbonates but also with ultramafic components but do not indicate that CO2-seepage is the principal driver of those processes (Gemeni et al., submitted). Here we present isotope data on a selection of groundwaters (δ2H , δ18O, δ13CTDIC, 87Sr/86Sr, δ11B, δ7Li). Stable isotopes of water indicate paleo-recharge for some of the groundwaters, limited exchange with gaseous CO2 and, in one case, possibly thermal exchange processes with silicates. Sr isotope ratios vary between marine ratios and radiogenic values indicating

  5. ­­Vertically-integrated dual-continuum models for CO2 sequestration in naturally fractured aquifers

    NASA Astrophysics Data System (ADS)

    Guo, B.; Tao, Y.; Bandilla, K.; Celia, M. A.

    2016-12-01

    CO2 injection into saline aquifers can be modeled as a two-phase (CO2 and brine) flow system. One type of simplified model for this system can be developed by integrating the three-dimensional two-phase flow equations in the vertical dimension; this leads to a class of so-called vertically integrated models. Conventional vertically integrated models are based on the vertical equilibrium (VE) assumption, which assumes that CO2 and brine segregate rapidly due to strong buoyancy and are always in pressure equilibrium in the vertical direction. Recently, Guo et al. (2014) introduced the concept of dynamic reconstruction for the CO2-brine system for vertically integrated models. That dynamic reconstruction is a more advanced vertically integrated approach that includes vertical two-phase flow dynamics of both CO2 and brine as one-dimensional fine-scale problems within the vertically integrated framework. This approach relaxes the VE assumption while maintaining much of the computational efficiencies of the vertically integrated formulation. In this presentation, we apply these concepts associated with vertically integrated models to CO2 injection in naturally fractured aquifers. We treat the fractured aquifer as a dual-continuum domain, using both dual-porosity and dual-permeability formulations, and we develop a hybrid vertically integrated model using different vertically integrated approaches in the fracture and the matrix domains. The fracture domain has a high permeability and is likely to have rapid segregation of CO2 and brine; as such, the VE model is appropriate for the fractures. For the dual-porosity approach, flow in the matrix is represented only in the effective exchange term, but in dual-permeability approaches, flow in the matrix needs to be modeled explicitly. Because flow in the matrix is typically slow, the VE assumption is unlikely to be valid. Therefore, in the matrix domain we apply a dynamic reconstruction for which vertical equilibrium is not

  6. Numerical analysis of wellbore integrity: results from a field study of a natural CO2 reservoir production well

    NASA Astrophysics Data System (ADS)

    Crow, W.; Gasda, S. E.; Williams, D. B.; Celia, M. A.; Carey, J. W.

    2008-12-01

    An important aspect of the risk associated with geological CO2 sequestration is the integrity of existing wellbores that penetrate geological layers targeted for CO2 injection. CO2 leakage may occur through multiple pathways along a wellbore, including through micro-fractures and micro-annuli within the "disturbed zone" surrounding the well casing. The effective permeability of this zone is a key parameter of wellbore integrity required for validation of numerical models. This parameter depends on a number of complex factors, including long-term attack by aggressive fluids, poor well completion and actions related to production of fluids through the wellbore. Recent studies have sought to replicate downhole conditions in the laboratory to identify the mechanisms and rates at which cement deterioration occurs. However, field tests are essential to understanding the in situ leakage properties of the millions of wells that exist in the mature sedimentary basins in North America. In this study, we present results from a field study of a 30-year-old production well from a natural CO2 reservoir. The wellbore was potentially exposed to a 96% CO2 fluid from the time of cement placement, and therefore cement degradation may be a significant factor leading to leakage pathways along this wellbore. A series of downhole tests was performed, including bond logs and extraction of sidewall cores. The cores were analyzed in the laboratory for mineralogical and hydrologic properties. A pressure test was conducted over an 11-ft section of well to determine the extent of hydraulic communication along the exterior of the well casing. Through analysis of this pressure test data, we are able estimate the effective permeability of the disturbed zone along the exterior of wellbore over this 11-ft section. We find the estimated range of effective permeability from the field test is consistent with laboratory analysis and bond log data. The cement interfaces with casing and/or formation are

  7. Predicting the ultimate potential of natural gas SOFC power cycles with CO2 capture - Part A: Methodology and reference cases

    NASA Astrophysics Data System (ADS)

    Campanari, Stefano; Mastropasqua, Luca; Gazzani, Matteo; Chiesa, Paolo; Romano, Matteo C.

    2016-08-01

    Driven by the search for the highest theoretical efficiency, in the latest years several studies investigated the integration of high temperature fuel cells in natural gas fired power plants, where fuel cells are integrated with simple or modified Brayton cycles and/or with additional bottoming cycles, and CO2 can be separated via chemical or physical separation, oxy-combustion and cryogenic methods. Focusing on Solid Oxide Fuel Cells (SOFC) and following a comprehensive review and analysis of possible plant configurations, this work investigates their theoretical potential efficiency and proposes two ultra-high efficiency plant configurations based on advanced intermediate-temperature SOFCs integrated with a steam turbine or gas turbine cycle. The SOFC works at atmospheric or pressurized conditions and the resulting power plant exceeds 78% LHV efficiency without CO2 capture (as discussed in part A of the work) and 70% LHV efficiency with substantial CO2 capture (part B). The power plants are simulated at the 100 MW scale with a complete set of realistic assumptions about fuel cell (FC) performance, plant components and auxiliaries, presenting detailed energy and material balances together with a second law analysis.

  8. Functional genomic analysis of corals from natural CO2 -seeps reveals core molecular responses involved in acclimatization to ocean acidification.

    PubMed

    Kenkel, Carly D; Moya, Aurelie; Strahl, Julia; Humphrey, Craig; Bay, Line K

    2017-07-20

    Little is known about the potential for acclimatization or adaptation of corals to ocean acidification and even less about the molecular mechanisms underpinning these processes. Here, we examine global gene expression patterns in corals and their intracellular algal symbionts from two replicate population pairs in Papua New Guinea that have undergone long-term acclimatization to natural variation in pCO2 . In the coral host, only 61 genes were differentially expressed in response to pCO2 environment, but the pattern of change was highly consistent between replicate populations, likely reflecting the core expression homeostasis response to ocean acidification. Functional annotations highlight lipid metabolism and a change in the stress response capacity of corals as key parts of this process. Specifically, constitutive downregulation of molecular chaperones was observed, which may impact response to combined climate change-related stressors. Elevated CO2 has been hypothesized to benefit photosynthetic organisms but expression changes of in hospite Symbiodinium in response to acidification were greater and less consistent among reef populations. This population-specific response suggests hosts may need to adapt not only to an acidified environment, but also to changes in their Symbiodinium populations that may not be consistent among environments, adding another challenging dimension to the physiological process of coping with climate change. Commonwealth of Australia. Global Change Biology © 2017 John Wiley & Sons Ltd.

  9. Discovery of natural gain amplification in the 10 muon m CO2 laser bands on Mars: The first definite natural laser

    NASA Technical Reports Server (NTRS)

    Mumma, M.; Buhl, D.; Chin, G.; Deming, D.; Espenak, F.; Kostiuk, T.; Zipoy, D.

    1980-01-01

    Fully resolved intensity profiles of various lines in the CO2 bands at 9.4 micrometers and 10.4 micrometers were measured on Mars using an infrared heterodyne spectrometer. Analysis of the line shapes shows that the Mars atmosphere exhibits positive gain on these lines, providing the first definite detection of natural optical gain amplification and enabling identification of these lines as the first definite natural laser ever discovered.

  10. Natural gas and CO2 price variation: impact on the relative cost-efficiency of LNG and pipelines.

    PubMed

    Ulvestad, Marte; Overland, Indra

    2012-06-01

    THIS ARTICLE DEVELOPS A FORMAL MODEL FOR COMPARING THE COST STRUCTURE OF THE TWO MAIN TRANSPORT OPTIONS FOR NATURAL GAS: liquefied natural gas (LNG) and pipelines. In particular, it evaluates how variations in the prices of natural gas and greenhouse gas emissions affect the relative cost-efficiency of these two options. Natural gas is often promoted as the most environmentally friendly of all fossil fuels, and LNG as a modern and efficient way of transporting it. Some research has been carried out into the local environmental impact of LNG facilities, but almost none into aspects related to climate change. This paper concludes that at current price levels for natural gas and CO2 emissions the distance from field to consumer and the volume of natural gas transported are the main determinants of transport costs. The pricing of natural gas and greenhouse emissions influence the relative cost-efficiency of LNG and pipeline transport, but only to a limited degree at current price levels. Because more energy is required for the LNG process (especially for fuelling the liquefaction process) than for pipelines at distances below 9100 km, LNG is more exposed to variability in the price of natural gas and greenhouse gas emissions up to this distance. If the prices of natural gas and/or greenhouse gas emission rise dramatically in the future, this will affect the choice between pipelines and LNG. Such a price increase will be favourable for pipelines relative to LNG.

  11. Natural gas and CO2 price variation: impact on the relative cost-efficiency of LNG and pipelines

    PubMed Central

    Ulvestad, Marte; Overland, Indra

    2012-01-01

    This article develops a formal model for comparing the cost structure of the two main transport options for natural gas: liquefied natural gas (LNG) and pipelines. In particular, it evaluates how variations in the prices of natural gas and greenhouse gas emissions affect the relative cost-efficiency of these two options. Natural gas is often promoted as the most environmentally friendly of all fossil fuels, and LNG as a modern and efficient way of transporting it. Some research has been carried out into the local environmental impact of LNG facilities, but almost none into aspects related to climate change. This paper concludes that at current price levels for natural gas and CO2 emissions the distance from field to consumer and the volume of natural gas transported are the main determinants of transport costs. The pricing of natural gas and greenhouse emissions influence the relative cost-efficiency of LNG and pipeline transport, but only to a limited degree at current price levels. Because more energy is required for the LNG process (especially for fuelling the liquefaction process) than for pipelines at distances below 9100 km, LNG is more exposed to variability in the price of natural gas and greenhouse gas emissions up to this distance. If the prices of natural gas and/or greenhouse gas emission rise dramatically in the future, this will affect the choice between pipelines and LNG. Such a price increase will be favourable for pipelines relative to LNG. PMID:24683269

  12. Natural wax constituents of a supercritical fluid CO(2) extract from quince (Cydonia oblonga Mill.) pomace.

    PubMed

    Lorenz, Peter; Berger, Melanie; Bertrams, Julia; Wende, Kristian; Wenzel, Kristin; Lindequist, Ulrike; Meyer, Ulrich; Stintzing, Florian C

    2008-05-01

    The chemical constituents of a lipophilic extract from quince (Cydonia oblonga Mill.), obtained by supercritical fluid CO(2) extraction of the dried fruit pomace were investigated. Solvent partition of quince wax with n-hexane or acetone yielded an insoluble (crystalline) and a soluble (oily) fraction. Both fractions were analyzed separately using gas chromatography/mass spectrometry (GC/MS). The insoluble fraction consisted of saturated n-aldehydes, n-alcohols and free n-alkanoic acids of carbon chain lengths between 22 and 32, with carbon chain lengths of 26 and 28 dominating. Also odd-numbered unbranched hydrocarbons, mainly C27, C29 and C31, were detected particularly in the acetone-insoluble fraction (total, 15.8%). By means of vacuum liquid chromatography, triterpenoic acids were separated from the hexane-insoluble matter and identified as a mixture of ursolic, oleanolic and betulinic acids. The major constituents of the hexane-soluble fraction were glycerides of linoleic [Δ(9,12), 18:2] and oleic [Δ(9), 18:1] acids, accompanied by free linoleic, oleic and palmitic acids (C16). Moreover β-sitosterol, Δ(5)-avenasterol as well as trace amounts of other sterols were assigned. Finally the carotenoids phytoene and phytofluene were identified and quantified by UV/vis and high-performance liquid chromatography/MS techniques, yielding 1.0 and 0.3% of the quince wax, respectively. It is anticipated that the complex of lipid constituents from quince wax may exert interesting biological activities, the elucidation of which awaits further studies.

  13. Radon in underground waters as a natural analogue to study the escape of CO2 in geological repositories.

    PubMed

    Martín Sánchez, A; Ruano Sánchez, A B; de la Torre Pérez, J; Jurado Vargas, M

    2015-11-01

    Activity concentrations of dissolved (222)Rn and (226)Ra were measured in several underground aquifers, which are candidates for repositories or for the study of analogue natural escapes of CO2. The concentration of both radionuclides in water was determined using liquid scintillation counting. The values obtained for the (222)Rn concentrations varied from 0 to 150 Bq l(-1), while the levels of (226)Ra were in general very low. This indicates that (222)Rn is coming from the decay of the undissolved (226)Ra existing in the rocks and deep layers of the aquifers, being later transported by diffusion in water.

  14. A combined methodology using electrical resistivity tomography, ordinary kriging and porosimetry for quantifying total C trapped in carbonate formations associated with natural analogues for CO2 leakage

    NASA Astrophysics Data System (ADS)

    Prado-Pérez, A. J.; Aracil, E.; Pérez del Villar, L.

    2014-06-01

    Currently, carbon deep geological storage is one of the most accepted methods for CO2 sequestration, being the long-term behaviour assessment of these artificial systems absolutely essential to guarantee the safety of the CO2 storage. In this sense, hydrogeochemical modelling is being used for evaluating any artificial CO2 deep geological storage as a potential CO2 sinkhole and to assess the leakage processes that are usually associated with these engineered systems. Carbonate precipitation, as travertines or speleothems, is a common feature in the CO2 leakage scenarios and, therefore, is of the utmost importance to quantify the total C content trapped as a stable mineral phase in these carbonate formations. A methodology combining three classical techniques such as: electrical resistivity tomography, geostatistical analysis and mercury porosimetry is described in this work, which was developed for calculating the total amount of C trapped as CaCO3 associated with the CO2 leakages in Alicún de las Torres natural analogue (Granada, Spain). The proposed methodology has allowed estimating the amount of C trapped as calcite, as more than 1.7 Mt. This last parameter, focussed on an artificial CO2 deep geological storage, is essential for hydrogeochemical modellers when evaluating whether CO2 storages constitute or not CO2 sinkholes. This finding is extremely important when assessing the long-term behaviour and safety of any artificial CO2 deep geological storage.

  15. Reactive Transport Modeling of Cap Rock Integrity During Natural and Engineered CO2 Storage

    SciTech Connect

    Johnson, J W; Nitao, J J; Morris, J P

    2004-05-26

    Long-term cap rock integrity represents the single most important constraint on the long-term isolation performance of natural and engineered CO{sub 2} storage sites. CO{sub 2} influx that forms natural accumulations and CO{sub 2} injection for EOR/sequestration or saline-aquifer disposal both lead to concomitant geochemical alteration and geomechanical deformation of the cap rock, enhancing or degrading its seal integrity depending on the relative effectiveness of these interdependent processes. Using our reactive transport simulator (NUFT), supporting geochemical databases and software (GEMBOCHS, SUPCRT92), and distinct-element geomechanical model (LDEC), we have shown that influx-triggered mineral dissolution/precipitation reactions within typical shale cap rocks continuously reduce microfracture apertures, while pressure and effective-stress evolution first rapidly increase then slowly constrict them. For a given shale composition, the extent of geochemical enhancement is nearly independent of key reservoir properties (permeability and lateral continuity) that distinguish EOR/sequestration and saline-aquifer settings and CO{sub 2} influx parameters (rate, focality, and duration) that distinguish engineered disposal sites and natural accumulations, because these characteristics and parameters have negligible (indirect) impact on mineral dissolution/precipitation rates. In contrast, the extent of geomechanical degradation is highly dependent on these reservoir properties and influx parameters because they effectively dictate magnitude of the pressure perturbation; specifically, initial geomechanical degradation has been shown inversely proportional to reservoir permeability and lateral continuity and proportional to influx rate. Hence, while the extent of geochemical alteration is nearly independent of filling mode, that of geomechanical deformation is significantly more pronounced during engineered injection. This distinction limits the extent to which naturally

  16. Modeling the Long-Term Isolation Performance of Natural and Engineered Geologic CO2 Storage Sites

    SciTech Connect

    Johnson, J W; Nitao, J J; Morris, J P

    2004-07-26

    Long-term cap rock integrity represents the single most important constraint on the long-term isolation performance of natural and engineered geologic CO{sub 2} storage sites. CO{sub 2} influx that forms natural accumulations and CO{sub 2} injection for EOR/sequestration or saline-aquifer disposal both lead to concomitant geochemical alteration and geomechanical deformation of the cap rock, enhancing or degrading its seal integrity depending on the relative effectiveness of these interdependent processes. This evolution of cap-rock permeability can be assessed through reactive transport modeling, an advanced computational method based on mathematical models of the coupled physical and chemical processes catalyzed by the influx event. Using our reactive transport simulator (NUFT), supporting geochemical databases and software (SUPCRT92), and distinct-element geomechanical model (LDEC), we have shown that influx-triggered mineral dissolution/precipitation reactions within typical shale cap rocks continuously reduce microfrac apertures, while pressure and effective-stress evolution first rapidly increase then slowly constrict them. For a given shale composition, the extent of geochemical enhancement is nearly independent of key reservoir properties (permeability and lateral continuity) that distinguish saline aquifer and EOR/sequestration settings and CO{sub 2} influx parameters (rate, focality, and duration) that distinguish engineered disposal sites and natural accumulations, because these characteristics and parameters have negligible impact on mineral reaction rates. In contrast, the extent of geomechanical degradation is highly dependent on these reservoir properties and influx parameters, because they effectively dictate magnitude of the pressure perturbation. Specifically, initial geomechanical degradation has been shown inversely proportional to reservoir permeability and lateral continuity and proportional to influx rate. As a result, while the extent of

  17. INVESTIGATION OF EFFICIENCY IMPROVEMENTS DURING CO2 INJECTION IN HYDRAULICALLY AND NATURALLY FRACTURED RESERVOIRS

    SciTech Connect

    David S. Schechter

    2005-04-27

    This report describes the work performed during the fourth year of the project, ''Investigating of Efficiency Improvements during CO{sub 2} Injection in Hydraulically and Naturally Fractured Reservoirs.'' The objective of this project is to perform unique laboratory experiments with artificially fractured cores (AFCs) and X-ray CT scanner to examine the physical mechanisms of bypassing in hydraulically fractured reservoirs (HFR) and naturally fractured reservoirs (NFR) that eventually result in more efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. In Chapter 1, we worked with DOE-RMOTC to investigate fracture properties in the Tensleep Formation at Teapot Dome Naval Reserve as part of their CO{sub 2} sequestration project. In Chapter 2, we continue our investigation to determine the primary oil recovery mechanism in a short vertically fractured core. Finally in Chapter 3, we report our numerical modeling efforts to develop compositional simulator with irregular grid blocks.

  18. Study on Solidification of CO2 by using Cold Energy of Liquefied Natural Gas

    NASA Astrophysics Data System (ADS)

    Takeuchi, Yoshiyuki; Fujiwara, Atsushi

    In conventional natural gas combustion power plants, vaporization heat of liquefied natural gas (LNG) has been supplied by sea water and/or air. In the plants, cold vaporization energy has been lost without any effective utilization. An advanced technology has been developed in which carbon dioxide in the flue gas is solidified and separated as dry-ice. Carbon dioxide in the flue gas of a LNG combined cycle is cooled and solidified by the evaporation of LNG. Fundamental studies on fluidized bed heat exchanger were carried out to analyze heat transfer phenomena at low temperature. And the fluidized bed type heat exchanger was confirmed that they had high efficiency by striping off frost solidified on the surface of heat exchanger tube. The heat transfer coefficient at -135°C was calculated about 330-370 (W/m2•K) at the condition where C02 gas was solidified.

  19. Coastal Microbial Mat Diversity along a Natural Salinity Gradient

    PubMed Central

    Bolhuis, Henk; Fillinger, Lucas; Stal, Lucas J.

    2013-01-01

    The North Sea coast of the Dutch barrier island of Schiermonnikoog is covered by microbial mats that initiate a succession of plant communities that eventually results in the development of a densely vegetated salt marsh. The North Sea beach has a natural elevation running from the low water mark to the dunes resulting in gradients of environmental factors perpendicular to the beach. These gradients are due to the input of seawater at the low water mark and of freshwater from upwelling groundwater at the dunes and rainfall. The result is a natural and dynamic salinity gradient depending on the tide, rainfall and wind. We studied the microbial community composition in thirty three samples taken every ten meters along this natural salinity gradient by using denaturing gradient gel electrophoresis (DGGE) of rRNA gene fragments. We looked at representatives from each Domain of life (Bacteria, Archaea and Eukarya) and with a particular emphasis on Cyanobacteria. Analysis of the DGGE fingerprints together with pigment composition revealed three distinct microbial mat communities, a marine community dominated by diatoms as primary producers, an intermediate brackish community dominated by Cyanobacteria as primary producers and a freshwater community with Cyanobacteria and freshwater green algae. PMID:23704895

  20. Coastal microbial mat diversity along a natural salinity gradient.

    PubMed

    Bolhuis, Henk; Fillinger, Lucas; Stal, Lucas J

    2013-01-01

    The North Sea coast of the Dutch barrier island of Schiermonnikoog is covered by microbial mats that initiate a succession of plant communities that eventually results in the development of a densely vegetated salt marsh. The North Sea beach has a natural elevation running from the low water mark to the dunes resulting in gradients of environmental factors perpendicular to the beach. These gradients are due to the input of seawater at the low water mark and of freshwater from upwelling groundwater at the dunes and rainfall. The result is a natural and dynamic salinity gradient depending on the tide, rainfall and wind. We studied the microbial community composition in thirty three samples taken every ten meters along this natural salinity gradient by using denaturing gradient gel electrophoresis (DGGE) of rRNA gene fragments. We looked at representatives from each Domain of life (Bacteria, Archaea and Eukarya) and with a particular emphasis on Cyanobacteria. Analysis of the DGGE fingerprints together with pigment composition revealed three distinct microbial mat communities, a marine community dominated by diatoms as primary producers, an intermediate brackish community dominated by Cyanobacteria as primary producers and a freshwater community with Cyanobacteria and freshwater green algae.

  1. Generating Aromatics From CO2 on Mars or Natural Gas on Earth

    NASA Technical Reports Server (NTRS)

    Muscatello, Anthony C.; Zubrin, Robert; Berggren, Mark

    2006-01-01

    Methane to aromatics on Mars ( METAMARS ) is the name of a process originally intended as a means of converting Martian atmospheric carbon dioxide to aromatic hydrocarbons and oxygen, which would be used as propellants for spacecraft to return to Earth. The process has been demonstrated on Earth on a laboratory scale. A truncated version of the process could be used on Earth to convert natural gas to aromatic hydrocarbon liquids. The greater (relative to natural gas) density of aromatic hydrocarbon liquids makes it more economically feasible to ship them to distant markets. Hence, this process makes it feasible to exploit some reserves of natural gas that, heretofore, have been considered as being "stranded" too far from markets to be of economic value. In the full version of METAMARS, carbon dioxide is frozen out of the atmosphere and fed to a Sabatier reactor along with hydrogen (which, on Mars, would have been brought from Earth). In the Sabatier reactor, these feedstocks are converted to methane and water. The water is condensed and electrolyzed to oxygen (which is liquefied) and hydrogen (which is recycled to the Sabatier reactor). The methane is sent to an aromatization reactor, wherein, over a molybdenum-on-zeolite catalyst at a temperature 700 C, it is partially converted into aromatic hydrocarbons (specifically, benzene, toluene, and naphthalene) along with hydrogen. The aromatics are collected by freezing, while unreacted methane and hydrogen are separated by a membrane. Most of the hydrogen is recycled to the Sabatier reactor, while the methane and a small portion of the hydrogen are recycled to the aromatization reactor. The partial recycle of hydrogen to the aromatization reactor greatly increases the catalyst lifetime and eases its regeneration by preventing the formation of graphitic carbon, which could damage the catalyst. (Moreover, if graphitic carbon were allowed to form, it would be necessary to use oxygen to remove it.) Because the aromatics

  2. INVESTIGATION OF EFFICIENCY IMPROVEMENTS DURING CO2 INJECTION IN HYDRAULICALLY AND NATURALLY FRACTURED RESERVOIRS

    SciTech Connect

    David S. Schechter

    2004-10-10

    This report describes the work performed during the third year of the project, ''Investigating of Efficiency Improvements during CO{sub 2} Injection in Hydraulically and Naturally Fractured Reservoirs.'' The objective of this project is to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in more efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. To achieve this objective, in this period we concentrated our effort on modeling fluid flow through rough fractures and investigating the grid orientation effect in rectangular grid blocks particularly at high mobility ratio as our precursor to use a compositional simulator. We are developing a robust simulator using Voronoi grids to accurately represent natural and induced fractures. We are also verifying the accuracy of the simulation using scaled laboratory experiments to provide a benchmark for our simulation technique. No such simulator currently exists so this capability will represent a major breakthrough in simulation of gas injection in fractured systems. The following sections outline the results that appear in this report.

  3. INVESTIGATION OF EFFICIENCY IMPROVEMENTS DURING CO2 INJECTION IN HYDRAULICALLY AND NATURALLY FRACTURED RESERVOIRS

    SciTech Connect

    David S. Schechter

    2003-10-01

    This report describes the work performed during the second year of the project, ''Investigating of Efficiency Improvements during CO{sub 2} Injection in Hydraulically and Naturally Fractured Reservoirs.'' The objective of this project is to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in less efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. To achieve this objective, in this period we concentrated our effort on modeling the fluid flow in fracture surface, examining the fluid transfer mechanisms and describing the fracture aperture distribution under different overburden pressure using X-ray CT scanner.

  4. INVESTIGATION OF EFFICIENCY IMPROVEMENTS DURING CO2 INJECTION IN HYDRAULICALLY AND NATURALLY FRACTURED RESERVOIRS

    SciTech Connect

    David S. Schechter

    2004-04-26

    This report describes the work performed during the second year of the project, ''Investigating of Efficiency Improvements during CO{sub 2} Injection in Hydraulically and Naturally Fractured Reservoirs.'' The objective of this project is to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in less efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. To achieve this objective, in this period we concentrated our effort on investigating the effect of CO{sub 2} injection rates in homogeneous and fractured cores on oil recovery and a strategy to mitigate CO{sub 2} bypassing in a fractured core.

  5. Gradients in the carbon isotopic composition of Ordovician shallow water carbonates: A potential pitfall in estimates of ancient CO2 and O2

    NASA Astrophysics Data System (ADS)

    Saltzman, Matthew R.; Edwards, Cole T.

    2017-04-01

    The carbon isotopic composition of the global dissolved inorganic carbon (DIC) reservoir is best estimated from open ocean pelagic carbonate sediments (δ13Ccarb). However, this is not practical for most of geologic time because seafloor subduction has removed the pre-Jurassic record and these time periods may have lacked planktonic calcifying organisms, and therefore shallow water carbonate platform or periplatform sediments are utilized. Shallow water deposits are susceptible to a wide range of post-depositional alteration processes and syn-depositional controls on δ13Ccarb that include carbonate mineralogy, water mass restriction, and a host of related variables (e.g., pH, temperature, organic decomposition, evaporation and CO2 solubility) that can produce local gradients in DIC. The degree to which shallow water δ13C curves diverge from open marine deposits may be critical to understanding how well global carbon cycle isotope mass balance models can predict organic carbon burial rates, but documentation of such divergence is often hindered by factors that limit chronostratigraphic correlation in restricted water masses (e.g., endemic faunas). Here we integrate strontium isotope (87Sr/86Sr) stratigraphy and biostratigraphy to compare δ13C curves in a case study along a depth transect in Middle-Late Ordovician carbonate platform settings. The restricted tidal flat and more open marine deposits are offset by a maximum of ∼2‰ during sea level drop and ∼0‰ during highstand flooding of the platform. Global carbon cycle models such as GEOCARBSULF use published δ13Ccarb curves to drive organic carbon burial rates under the assumption that δ13Ccarb reflects a global seawater signal. We show here the potential pitfalls of using a published δ13Ccarb curve that violates this global assumption. For the 460 million year Middle-Late Ordovician time bin in GEOCARBSULF, improper usage of our locally depleted δ13C curve to drive global organic carbon burial would

  6. Implications of the recent reductions in natural gas prices for emissions of CO2 from the US power sector.

    PubMed

    Lu, Xi; Salovaara, Jackson; McElroy, Michael B

    2012-03-06

    CO(2) emissions from the US power sector decreased by 8.76% in 2009 relative to 2008 contributing to a decrease over this period of 6.59% in overall US emissions of greenhouse gases. An econometric model, tuned to data reported for regional generation of US electricity, is used to diagnose factors responsible for the 2009 decrease. More than half of the reduction is attributed to a shift from generation of power using coal to gas driven by a recent decrease in gas prices in response to the increase in production from shale. An important result of the model is that, when the cost differential for generation using gas rather than coal falls below 2-3 cents/kWh, less efficient coal fired plants are displaced by more efficient natural gas combined cycle (NGCC) generation alternatives. Costs for generation using NGCC decreased by close to 4 cents/kWh in 2009 relative to 2008 ensuring that generation of electricity using gas was competitive with coal in 2009 in contrast to the situation in 2008 when gas prices were much higher. A modest price on carbon could contribute to additional switching from coal to gas with further savings in CO(2) emissions.

  7. The impact of CO2 on shallow groundwater chemistry: observations at a natural analog site and implications for carbon sequestration

    SciTech Connect

    Keating, Elizabeth; Fessenden, Julianna; Kanjorski, Nancy; Koning, Dan; Pawar, Rajesh

    2008-01-01

    In a natural analog study of risks associated with carbon sequestration, impacts of CO{sub 2} on shallow groundwater quality have been measured in a sandstone aquifer in New Mexico, USA. Despite relatively high levels of dissolved CO{sub 2}, originating from depth and producing geysering at one well, pH depression and consequent trace element mobility are relatively minor effects due to the buffering capacity of the aquifer. However, local contamination due to influx of saline waters in a subset of wells is significant. Geochemical modeling of major ion concentrations suggests that high alkalinity and carbonate mineral dissolution buffers pH changes due to CO{sub 2} influx. Analysis oftrends in dissolved trace elements, chloride, and CO2 reveal no evidence of in-situ trace element mobilization. There is clear evidence, however, that As, U, and Pb are locally co-transported into the aquifer with CO{sub 2}-rich saline water. This study illustrates the role that local geochemical conditions will play in determining the effectiveness of monitoring strategies for CO{sub 2} leakage. For example, if buffering is significant, pH monitoring may not effectively detect CO2 leakage. This study also highlights potential complications that CO{sub 2}carrier fluids, such as saline waters, pose in monitoring impacts ofgeologic sequestration.

  8. Fault-controlled advective, diffusive, and eruptive CO 2 leakage from natural reservoirs in the Colorado Plateau, East-Central Utah

    NASA Astrophysics Data System (ADS)

    Jung, Na-Hyun

    This study investigated a natural analogue for CO2 leakage near Green River, Utah, aiming to understand the influence of various factors on CO2 leakage and to reliably predict underground CO2 behavior after injection for geologic CO2 sequestration. Advective, diffusive, and eruptive characteristics of CO2 leakage were assessed via a soil CO2 flux survey and numerical modeling. The field results show anomalous CO2 fluxes (> 10 g m-2 d-1 ) along the faults, particularly adjacent to CO2-driven cold springs and geysers (e.g., 36,259 g m-2 d-1 at Crystal Geyser), ancient travertines (e.g., 5,917 g m-2 d-1), joint zones in sandstone (e.g., 120 g m-2 d-1), and brine discharge zones (e.g., 5,515 g m-2 d-1). Combined with similar isotopic ratios of gas and progressive evolution of brine chemistry at springs and geysers, a gradual decrease of soil CO2 flux from the Little Grand Wash (LGW; ~36,259 g m -2 d-1) to Salt Wash (SW; ~1,428 g m-2 d-1) fault zones reveals the same CO2 origin and potential southward transport of CO2 over 10-20 km. The numerical simulations exhibit lateral transport of free CO2 and CO2-rich brine from the LGW to SW fault zones through the regional aquifers (e.g., Entrada, Navajo, Kayenta, Wingate, White Rim). CO2 travels predominantly as an aqueous phase (XCO2=~0.045) as previously suggested, giving rise to the convective instability that further accelerates CO2 dissolution. While the buoyant free CO2 always tends to ascend, a fraction of dense CO2-rich brine flows laterally into the aquifer and mixes with the formation fluids during upward migration along the fault. The fault always enhances advective CO2 transport regardless of its permeability (k). However, only low-k fault prevents unconditional upright migration of CO2 and induces fault-parallel movement, feeding the northern aquifers with more CO2. Low-k fault also impedes lateral southward fluid flow from the northern aquifers, developing anticlinal CO2 traps at shallow depths (<300 m). The

  9. INVESTIGATION OF EFFICIENCY IMPROVEMENTS DURING CO2 INJECTION IN HYDRAULICALLY AND NATURALLY FRACTURED RESERVOIRS

    SciTech Connect

    David S. Schechter

    2003-04-01

    The objective of this project is to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in less efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. This report provides results of the third semi-annual technical progress report that consists of application of X-Ray Tomography results to validate our numerical modeling of flow in fractures. Spontaneous imbibition plays a very important role in the displacement mechanism of non-wetting fluid in naturally fractured reservoirs. To quantify this spontaneous imbibition process, we developed a 2D two-phase numerical model. This numerical model was developed because an available commercial simulator cannot be used to model small-scale experiments with different boundary conditions. In building the numerical model, we started with the basic equation of fluid flow and developed a numerical approach of solving the non-linear diffusion saturation equation. We compared our numerical model with the analytical solution of this equation to ascertain the limitations of the assumptions used to arrive at that solution. The unique aspect of this paper is that we validated our model with X-ray computerized tomography (CT) experimental data from a different spontaneous imbibition experiment, where two simultaneously varying parameters of weight gain and CT water saturation were used. This requires us to undertake extensive sensitivity studies on key parameters before a successful match could be obtained. We also successfully captured our own X-ray computerized tomography (CT) laboratory experiment on a fractured core.

  10. Improving the inter-hemispheric gradient of total column atmospheric CO2 and CH4 in simulations with the ECMWF semi-Lagrangian atmospheric global model

    NASA Astrophysics Data System (ADS)

    Agusti-Panareda, Anna; Diamantakis, Michail; Bayona, Victor; Klappenbach, Friedrich; Butz, Andre

    2017-01-01

    It is a widely established fact that standard semi-Lagrangian advection schemes are highly efficient numerical techniques for simulating the transport of atmospheric tracers. However, as they are not formally mass conserving, it is essential to use some method for restoring mass conservation in long time range forecasts. A common approach is to use global mass fixers. This is the case of the semi-Lagrangian advection scheme in the Integrated Forecasting System (IFS) model used by the Copernicus Atmosphere Monitoring Service (CAMS) at the European Centre for Medium-Range Weather Forecasts (ECMWF).Mass fixers are algorithms with substantial differences in complexity and sophistication but in general of low computational cost. This paper shows the positive impact mass fixers have on the inter-hemispheric gradient of total atmospheric column-averaged CO2 and CH4, a crucial feature of their spatial distribution. Two algorithms are compared: the simple "proportional" and the more complex Bermejo-Conde schemes. The former is widely used by several Earth system climate models as well the CAMS global forecasts and analysis of atmospheric composition, while the latter has been recently implemented in IFS. Comparisons against total column observations demonstrate that the proportional mass fixer is shown to be suitable for the low-resolution simulations, but for the high-resolution simulations the Bermejo-Conde scheme clearly gives better results. These results have potential repercussions for climate Earth system models using proportional mass fixers as their resolution increases. It also emphasises the importance of benchmarking the tracer mass fixers with the inter-hemispheric gradient of long-lived greenhouse gases using observations.

  11. INVESTIGATION OF EFFICIENCY IMPROVEMENTS DURING CO2 INJECTION IN HYDRAULICALLY AND NATURALLY FRACTURED RESERVOIRS

    SciTech Connect

    David S. Schechter

    2005-09-28

    even in a short matrix block. This results are contrary with the previous believes that gravity drainage has always been associated with tall matrix blocks. In order to reduce oil bypassed, we injected water that has been viscosified with a polymer into the fracture to divert CO{sub 2} flow into matrix and delay CO{sub 2} breakthrough. Although the breakthrough time reduced considerably, water ''leak off'' into the matrix was very high. A cross-linked gel was used in the fracture to avoid this problem. The gel was found to overcome ''leak off'' problems and effectively divert CO{sub 2} flow into the matrix. As part of our technology transfer activity, we investigated the natural fracture aperture distribution of Tensleep formation cores. We found that the measured apertures distributions follow log normal distribution as expected. The second chapter deals with analysis and modeling the laboratory experiments and fluid flow through fractured networks. We derived a new equation to determine the average fracture aperture and the amount of each flow through fracture and matrix system. The results of this study were used as the observed data and for validating the simulation model. The idea behind this study is to validate the use of a set of smooth parallel plates that is common in modeling fracture system. The results suggest that fracture apertures need to be distributed to accurately model the experimental results. In order to study the imbibition process in details, we developed imbibition simulator. We validated our model with X-ray CT experimental data from different imbibition experiments. We found that the proper simulation model requires matching both weight gain and CT water saturation simultaneously as oppose to common practices in matching imbibition process with weight gain only because of lack information from CT scan. The work was continued by developing dual porosity simulation using empirical transfer function (ETF) derived from imbibition experiments

  12. Carbon assimilation and nitrogen in needles of fertilized and unfertilized field-grown Scots pine at natural and elevated concentrations of CO2.

    PubMed

    Laitinen, K; Luomala, E M; Kellomäki, S; Vapaavuori, E

    2000-07-01

    Effects of elevated CO2 concentration ([CO2]) on carbon assimilation and needle biochemistry of fertilized and unfertilized 25-30-year-old Scots pine (Pinus sylvestris L.) trees were studied in a branch bag experiment set up in a naturally regenerated stand. In each tree, one branch was enclosed in a bag supplied with ambient [CO2] (360 micromol mol(-1)), a second branch was enclosed in a bag supplied with elevated [CO2] (680 micromol(-1)) and a control branch was left unbagged. The CO2 treatments were applied from April 15 to September 15, starting in 1993 for unfertilized trees and in 1994 for fertilized trees, which were treated with N in June 1994. Net photosynthesis, amount and activity of Rubisco, N, starch, C:N ratio and SLA of needles were measured during the growing season of 1995. Light-saturated net photosynthetic rates of 1-year-old and current-year shoots measured at ambient [CO2] were not affected by growth [CO2] or N fertilization. Elevated [CO2] reduced the amount and activity of Rubisco, and the relative proportion of Rubisco to soluble proteins and N in needles of unfertilized trees. Elevated [CO2] also reduced the chlorophyll concentration (fresh weight basis) of needles of unfertilized trees. Soluble protein concentration of needles was not affected by growth [CO2]. Elevated [CO2] decreased the Rubisco:chlorophyll ratio in unfertilized and fertilized trees. Starch concentration was significantly increased at elevated [CO2] only in 1-year-old needles of fertilized trees. Elevated [CO2] reduced needle N concentration on a dry weight or structural basis (dry weight minus starch) in unfertilized trees, resulting in an increase in needle C:N ratio. Fertilization had no effect on soluble protein, chlorophyll, Rubisco or N concentration of needles. The decrease in the relative proportions of Rubisco and N concentration in needles of unfertilized trees at elevated [CO2] indicates reallocation of N resources away from Rubisco to nonphotosynthetic

  13. Hynol: An economic process for methanol production from biomass and natural gas with reduced CO2 emission

    NASA Astrophysics Data System (ADS)

    Steinberg, M.; Dong, Yuanji

    1993-10-01

    The Hynol process is proposed to meet the demand for an economical process for methanol production with reduced CO2 emission. This new process consists of three reaction steps: (1) hydrogasification of biomass, (2) steam reforming of the produced gas with additional natural gas feedstock, and (3) methanol synthesis of the hydrogen and carbon monoxide produced during the previous two steps. The H2-rich gas remaining after methanol synthesis is recycled to gasify the biomass in an energy neutral reactor so that there is no need for an expensive oxygen plant as required by commercial steam gasifiers. Recycling gas allows the methanol synthesis reactor to perform at a relatively lower pressure than conventional while the plant still maintains high methanol yield. Energy recovery designed into the process minimizes heat loss and increases the process thermal efficiency. If the Hynol methanol is used as an alternative and more efficient automotive fuel, an overall 41% reduction in CO2 emission can be achieved compared to the use of conventional gasoline fuel. A preliminary economic estimate shows that the total capital investment for a Hynol plant is 40% lower than that for a conventional biomass gasification plant. The methanol production cost is $0.43/gal for a 1085 million gal/yr Hynol plant which is competitive with current U.S. methanol and equivalent gasoline prices. Process flowsheet and simulation data using biomass and natural gas as cofeedstocks are presented. The Hynol process can convert any condensed carbonaceous material, especially municipal solid waste (MSW), to produce methanol.

  14. Antioxidant capacity of polychaetes occurring at a natural CO2 vent system: Results of an in situ reciprocal transplant experiment.

    PubMed

    Ricevuto, E; Benedetti, M; Regoli, F; Spicer, J I; Gambi, M C

    2015-12-01

    Ocean acidification (OA) is occurring at a fast rate, resulting in changes of carbonate chemistry in the oceans and in lowering of the pH. Previous studies have documented significant changes in the antioxidant defenses of marine species in response to OA. Here, selected polychaete species, Platynereis dumerilii, Polyophthalmus pictus and Syllis prolifera, were sampled from a natural CO2 vent system (pH = 7.3) and from a non-venting 'control' site (pH = 8.1), and reciprocally transplanted in these areas for 30 days. Total antioxidant capacity toward different forms of oxyradicals was compared in native and transplanted polychaetes: the aim was to assess whether the environmental conditions at the vent site would act as a prooxidant stressor, and the capability of polychaetes to modulate their antioxidant capacity to counteract a varied oxyradicals formation. None of the investigated species enhanced the antioxidant potential during the experiment. A significant reduction of the capability to neutralize different forms of oxyradicals was observed in P. pictus and, partially, in S. prolifera when transplanted from control to naturally-acidified conditions. On the other hand, populations of P. dumerilii originating from the vent and of S. prolifera from both control and acidified sites, showed higher constitutive antioxidant efficiency toward peroxyl radicals and peroxynitrite, which may allow them to cope with short-term and chronic exposure to higher oxidative pressure without further enhancement of antioxidant defenses. Since low pH - high pCO2 is the greatest environmental difference between the control and the vent sites, we suggest that the pro-oxidant challenge due to such peculiarities may have different biological consequences in different polychaete species. Some appear more susceptible to oxidative effects, while others acquire a long term acclimatization to vent conditions through the enhancement of their basal antioxidant protection.

  15. Effect of H2O, and combined effects of H2O + F, H2O + CO2, and H2O + F + CO2 on the viscosity of a natural basalt from Fuego volcano, Guatemala

    NASA Astrophysics Data System (ADS)

    Robert, G.; Whittington, A. G.; Knipping, J.; Scherbarth, S.; Stechern, A.; Behrens, H.

    2012-12-01

    We measured the viscosity of 5 series of remelted natural basalt from Fuego volcano, Guatemala. These series include single and multiple volatile species: H2O, F, H2O-F, H2O-CO2, and H2O-CO2-F. The hydrous glasses were synthesized at 3 kbar and 1250°C in Internally Heated Pressure Vessels. The multiple volatile series were synthesized at 5 kbar and 1250°C. CO2 was added as Ag2C2O4, F as AlF3, and H2O as distilled water. The anhydrous, F-bearing series was synthesized at 1 atm by simply remelting the Fuego basalt and adding F as CaF2.The natural, dry, remelted Fuego basalt has an NBO/T of 0.64. The following comparisons are based on parallel-plate viscosity measurements in the range ~108 to 1012 Pa s. The temperature at which the viscosity is 1012 Pa s (T12) is taken to be the viscosimetric glass transition temperature (Tg). The addition of 2 wt.% H2O results in a decrease of T12 of ~150°C for basalt. Fluorine on its own has a measurable, but much smaller effect, than the equivalent amount of water. Indeed, ~2 wt.% F results in a T12 depression of only ~30°C. When H2O and F are both present, their effects are approximately additive. For example, the viscosity of a basalt with 1.44 wt.% H2O is very similar to the viscosity of a basalt with ~1 wt.% H2O and ~1.25 wt.% F, and the viscosities of a basalt with 2.29 wt.% H2O and a basalt with ~1.65 wt.% H2O and ~1.3 wt.% F are also very similar. The effect of CO2 is somewhat ambiguous. The viscosity of a basalt with ~1.7 wt.% H2O, ~1.3 wt.% F and ~0.2 wt.% CO2 is essentially the same as the viscosity of a basalt with 2.29 wt.% H2O, so CO2 seems to have a negligible or even viscosity-increasing effect when F and H2O are also present. However, a basalt with ~0.84 wt.% H2O and ~0.09 wt.% CO2 has about the same viscosity as a basalt with 1.34 wt.% H2O, which could suggest a strong (viscosity-decreasing) effect of very small amounts of CO2. These results suggest that the effects on viscosity of F in basaltic systems are

  16. Long-term elevated atmospheric CO2 enhances forest productivity

    NASA Astrophysics Data System (ADS)

    Loecke, T. D.; Groffman, P. M.; Treseder, K. K.; LaDeau, S.

    2011-12-01

    Global atmospheric CO2 concentrations are increasing at historically unprecedented but ecologically gradual rates. The implications of this perturbation for carbon sequestration and feedback on global climate change are difficult to predict due in part to its gradual and largely uniform nature. We used long-term (>40 years) spatial gradients in atmospheric CO2 concentration, produced by spatially heterogeneous fossil fuel combustion along a rural to urban transect, to test the hypotheses that 1) rural to urban CO2 spatial gradients are useful analogs for gradual climate change and 2) higher atmospheric CO2 concentration promotes tree growth and C sequestration. Fossil fuel derived CO2 imparts a distinctive 14C isotopic signature on atmospheric CO2; as this CO2 is fixed into annual tree rings, a proxy for fossil fuel derived CO2 is preserved. Ten four-year tree ring segments were analyzed for α-cellulose 14C content by AMS from trees within 10 closed canopy forested sites in the Baltimore Maryland metropolitan area. Tree growth parameters were assessed by measuring the annual ring width change of 224 trees across the 10 sites. A hierarchical Bayesian model was constructed to determine the influence of CO2 concentration and other site and environmental factors on tree growth. Our proxy for historical CO2 concentrations indicates a detectable but diminishing spatial CO2 gradient across the rural to urban transect that ranged from a 5.6% gradient during the 1970s to a 1.4% gradient in recent years (2000-2008). This observation is consistent with urban deindustrialization and concurrent expansion of suburban development. As an analog for future atmospheric conditions, this spatial gradient is equivalent to a temporal gradient of ca. 15, 7.2, 9.8, 2.6 years of atmospheric CO2 rise during the past four decades. The CO2 spatial gradient had an overall positive effect on tree size adjusted ring width growth. Modeled air surface temperature differences among sites indicate

  17. Implications of Sub-Hydrostatic Pressures in the Bravo Dome Natural CO2 Reservoir for the Long-Term Security of Geological Carbon Dioxide Storage

    NASA Astrophysics Data System (ADS)

    Akhbari, D.; Hesse, M. A.; Larson, T.

    2014-12-01

    The Bravo Dome field in northeast New Mexico is one of the largest gas accumulations worldwide and the largest natural CO2 accumulation in North America. The field is only 580-900 m deep and located in the Permian Tubb sandstone that unconformably overlies the granitic basement. Sathaye et al. (2014) estimated that 1.3 Gt of CO2 is stored at the reservoir. A major increase in the pore pressure relative to the hydrostatic pressure is expected due to the large amount of CO2 injected into the reservoir. However, the pre-production gas pressures indicate that most parts of the reservoir are approximately 5 MPa below hydrostatic pressure. Three processes could explain the under pressure in the Bravo Dome reservoir; 1) erosional unloading, 2) CO2 dissolution into the ambient brine, 3) cooling of CO2after injection. Analytical solutions suggest that an erosion rate of 180 m/Ma is required to reduce the pore pressures to the values observed at Bravo Dome. Given that the current erosion rate is only 5 m/Ma (Nereson et al. 2013); the sub-hydrostatic pressures at Bravo Dome are likely due to CO2dissolution and cooling. To investigate the impact of CO2 dissolution on the pore pressure we have developed new analytical solutions and conducted laboratory experiments. We assume that gaseous CO2 was confined to sandstones during emplacement due to the high entry pressure of the siltstones. After emplacement the CO2 dissolves in to the brine contained in the siltstones and the pressure in the sandstones declines. Assuming the sandstone-siltstone system is closed, the pressure decline due to CO2 dissolution is controlled by a single dimensionless number, η = KHRTVw /Vg. Herein, KH is Henry's constant, R is ideal gas constant, T is temperature, Vw is water volume, and Vg is CO2 volume. The pressure drop is controlled by the ratio of water volume to CO2 volume and η varies between 0.1 to 8 at Bravo Dome. This corresponds to pressure drops between 0.8-7.5 MPa and can therefore account

  18. δ 13C of ecosystem-respired CO2 along a gradient of C3 woody-plant encroachment into C4 grassland

    NASA Astrophysics Data System (ADS)

    Sun, W.; Scott, R. L.; Resco, V.; Cable, J. M.; Huxman, T. E.; Williams, D. G.

    2006-12-01

    Woody plant encroachment into grassland has the potential to affect net primary production, in part by changing the sensitivities of photosynthesis and respiration to precipitation. Encroachment of mesquite (Prosopis) into floodplain sacaton (Sporobolus) grassland along the San Pedro River in southeastern Arizona has altered the magnitude and seasonal pattern of net ecosystem carbon exchange and ecosystem respiration. We hypothesized that because mesquite accesses ground water in these floodplain environments, its advancement and dominance in former grassland reduces the sensitivities of photosynthesis and autotrophic respiration to inputs of growing season precipitation. The observed elevated rates of ecosystem respiration following rainfall inputs are likely to result from microbial decomposition of labile organic matter derived from the highly productive mesquite trees. We used the Keeling plot method to monitor carbon-13 composition of nocturnal ecosystem-respired CO2 (δ 13CR) during the growing seasons of 2005 and 2006 at three sites spanning a gradient of mesquite invasion: C4 sacaton grassland, mixed mesquite/grass shrubland and C3 mesquite woodland. δ 13CR in the C4 grassland increased from -18.8‰ during the dry premonsoon period to -16.7‰ after the onset of summer rains, whereas δ 13CR in the mixed shrub/grass and woodland ecosystems declined from -20.9‰ to - 24‰ and from -20.8‰ to -24.7‰, respectively, following the onset of summer rains. The δ 13CR of respired CO2 was collected separately from soil, roots, leaves and surface litter to evaluate the contribution of each of these components to ecosystem respiration. Partitioning of ecosystem respiration using these isotope end-members and responses to short-term (days) changes in shallow (0-5cm) soil moisture content suggest that in former grassland now occupied by mesquite woodland, rainfall inputs primarily stimulate microbial decomposition and have little effect on autotrophic respiration

  19. Noble gases preserve history of retentive continental crust in the Bravo Dome natural CO2 field, New Mexico

    NASA Astrophysics Data System (ADS)

    Sathaye, Kiran J.; Smye, Andrew J.; Jordan, Jacob S.; Hesse, Marc A.

    2016-06-01

    Budgets of 4He and 40Ar provide constraints on the chemical evolution of the solid Earth and atmosphere. Although continental crust accounts for the majority of 4He and 40Ar degassed from the Earth, degassing mechanisms are subject to scholarly debate. Here we provide a constraint on crustal degassing by comparing the noble gases accumulated in the Bravo Dome natural CO2 reservoir, New Mexico USA, with the radiogenic production in the underlying crust. A detailed geological model of the reservoir is used to provide absolute abundances and geostatistical uncertainty of 4He, 40Ar, 21Ne, 20Ne, 36Ar, and 84Kr. The present-day production rate of crustal radiogenic 4He and 40Ar, henceforth referred to as 4He* and 40Ar*, is estimated using the basement composition, surface and mantle heat flow, and seismic estimates of crustal density. After subtracting mantle and atmospheric contributions, the reservoir contains less than 0.02% of the radiogenic production in the underlying crust. This shows unequivocally that radiogenic noble gases are effectively retained in cratonic continental crust over millennial timescales. This also requires that approximately 1.5 Gt of mantle derived CO2 migrated through the crust without mobilizing the crustally accumulated gases. This observation suggests transport along a localized fracture network. Therefore, the retention of noble gases in stable crystalline continental crust allows shallow accumulations of radiogenic gases to record tectonic history. At Bravo Dome, the crustal 4He*/40Ar* ratio is one fifth of the expected crustal production ratio, recording the preferential release of 4He during the Ancestral Rocky Mountain orogeny, 300 Ma.

  20. Geological and geophysical properties of cap rock in a natural CO2 occurrence, Mihályi-Répcelak area, Western Hungary

    NASA Astrophysics Data System (ADS)

    Király, Csilla; Szamosfalvi, Ágnes; Sendula, Eszter; Páles, Mariann; Kovács, István; Kónya, Péter; Falus, György; Szabó, Csaba

    2015-04-01

    The physical and geochemical consistency of the cap rock is primarily important for safe geological storage of CO2.. As a consequence of CO2 injection reactions took place between the minerals of the reservoir, the cap rock and CO2 saturated pore water. These reactions may change the mineral composition and petrophysical properties of the storage reservoir as well as the cap rock that provides the only physical barrier that retains carbon dioxide in the target reservoir formation. Study of the natural CO2 occurrences delivers information to understand which properties of a cap rock provide the sustainable closure and retainment. Knowledge of the long term effect of CO2 on the behavior of the cap rock is an important input in the selection procedure of a potential CO2 injection site. Yet, very few data exist on geochemical properties and reactivity of the cap rocks. During normal commercial operations the reservoir is typically cored, but not the cap rock. This study may enhance our knowledge about possible mineralogical reactions, which can occur in clayey-aleuritic cap rocks. The Mihályi-Répcelak natural CO2 occurrence is believed to be leakage safe. There is no known seepage on the surface. It is suggested that the aleuritic clay rich cap rock occurring at the natural reservoir can stop CO2 migration into other reservoirs or to the surface. The most important characteristics of cap rocks that they have low permeability (<0.1 mD) and porosity (eff.por. = 4%) and high clayeyness (approx. 80%). However, we demonstrate that in addition to these parameters the geochemical properties of cap rock is also important. In order to characterize the natural CO2 occurrence, we applied the following analysis, like XRD, FTIR, SEM. The petrophysical properties are determined from the interpretation of geophysical well-logs and grain size distribution. The most important result of this study that adequate petrophysical properties do not completely define the suitability of a cap

  1. Atmospheric N deposition and feedbacks on net ecosystem CO2 exchange at a semi-natural peatland site

    NASA Astrophysics Data System (ADS)

    Hurkuck, Miriam; Brümmer, Christian; Spott, Oliver; Flessa, Heinz; Kutsch, Werner L.

    2013-04-01

    Large areas of Northern Germany have been converted from natural peat bogs to arable land and were subjected to draining and peat cutting in the past. The few protected peatland areas remaining are affected by high nitrogen (N) deposition. This is the case at our study site - a semi-natural raised bog - which although located in a natural park, is surrounded by highly fertilized agricultural land and highly emitting animal husbandry farms. In this study, we use a combined approach of two independent methods to quantify atmospheric N deposition. We further investigate possible feedbacks of seasonal variation in N deposition on net ecosystem CO2 exchange (NEE). Fluxes of ammonia (NH3) and its atmospheric reactants are measured by a KAPS-denuder system. Additionally, total N input from the atmosphere into a soil-plant model ecosystem is investigated by a 15N dilution method called 'Integrated Total Nitrogen Input' (ITNI). With this approach, we allocate atmospheric N after its uptake by the ecosystem into its different fractions and investigate both plant-species effects (Lolium multiflorum, Eriophorum vaginatum) and influences of the plant biomass production induced by different amounts of fertilizer addition. Continuous eddy-covariance measurements are carried out to measure NEE. Maximum NH3 depositions of 0.41 ± 0.04 kg ha-1 week-1 were found in spring 2012. The proportion of fluxes of other N compounds such as HNO3, aerosol NH4 and NO3 was usually around 20 % of total dry N measured by KAPS denuders. In total, dry N deposition was 11.2 ± 0.9 kg N ha-1 yr-1 over the first year of experiments. Complemented with wet N measurements using bulk samplers, total N depositions of about 25.0 kg ha-1 yr-1 were found. The mean atmospheric N uptake determined with the ITNI system was 3.99 ± 0.82 mg N g-1 dry weight from July to October 2011. About two third of total deposited airborne N was allocated in above-ground plant biomass and roots. Upscaling of data based on pot

  2. The effect of Mg concentration in silicate glasses on CO2 solubility and solution mechanism: Implication for natural magmatic systems

    NASA Astrophysics Data System (ADS)

    Morizet, Yann; Paris, Michael; Sifré, David; Di Carlo, Ida; Gaillard, Fabrice

    2017-02-01

    Following an experimental approach conducted between 0.5 and 1.5 GPa, we investigated the change in CO2 solubility as a function of the XMg (MgO/(MgO + CaO)) for a range of silicate glasses. The synthesised CO2-bearing glasses have XMg up to 0.72, stoichiometric NBO/T (degree of polymerization) up to 2.6 corresponding to highly depolymerized compositions analogues to kimberlites. Several samples were synthesised with 17O enrichment to investigate the CO2 dissolution mechanism via the change in O species environments by NMR spectroscopy. The experimental results show that CO2 solubility increases with NBO/T in agreement with previous works. In addition, increasing XMg strongly decreases CO2 solubility: from 18 to 7 wt.% CO2 as XMg ranges from 0 to 0.6 (1.5 GPa and NBO/T ∼2). 17O NMR results demonstrate that CO2 molecules dissolve as CO32- groups showing a signal at +146 ppm for which the intensity is linearly correlated to the wt.% CO2 determined by Raman. The analysis of the oxygen environments as a function of CO2 content for Mg ONBO (+62 ppm) and Ca ONBO (+103 ppm) show that CO2 dissolves preferentially in the vicinity of Ca2+ atoms. The difference in CO2 solubility is explained by the ability for Mg2+ cations to act as a weak network former and to be present in fourfold coordination or by the stronger affinity of CO2 molecules for Ca2+ rather than for Mg2+. We show that the CO2 solubility is negatively correlated to the Melt Ionic Field Strength which reflects the variation in the affinity of CO2 molecules for one cation or another. Strongly depolymerized mantle melts, such as kimberlites, melilitites, nephelinites and basanites will exhibit lower CO2 solubility than currently assumed due to their high MgO content which must imply degassing at greater depth, potentially in the sub-lithospheric mantle.

  3. The effects of elevated CO2 on cereal crop natural defenses and the potential implications for mycotoxin risk

    USDA-ARS?s Scientific Manuscript database

    Wheat and corn are an essential part of the world’s grain supply, but climate change has the potential to increase grain susceptibility to toxin producing fungal pathogens. While rising atmospheric [CO2] is a driving force of climate change, our understanding of how elevated [CO2] will effect grain ...

  4. Comparison of shallow aquifer and soil gas monitoring approaches for detecting CO2 leakage at a natural analogue site in France

    NASA Astrophysics Data System (ADS)

    Widory, D.; Gal, F.; Proust, E.; Mayer, B.

    2011-12-01

    Natural analogue sites where geologic CO2 is leaking to the surface provide excellent opportunities to test approaches suitable for monitoring for potential CO2 leakage at carbon capture and storage sites. We tested isotope monitoring approaches for CO2 detection in shallow aquifers and the overlying soil zone at a CO2 analogue site near Sainte-Marguerite in the Massif Central (France). The Sainte-Marguerite area is located in the southern part of the Limagne graben (French Massif Central). The basement, composed of highly fractured granite, outcrops toward the west of the study area, notably around the Saladis spring. An intercalated arkosic permeable interval between fractured granite and Oligocene marls and limestones acts as a stratiform drain for fluid migration while the overlying thick Oligocene interval is impermeable and acts as a seal. The Allier river bed is located near the contact between the basement and the sedimentary rocks. Deep CO2-ladden fluids migrate through the arkose interval toward the Sainte-Marguerite area and sustain a number of local springs. The Sainte-Marguerite area is known for the travertine deposits associated with the CO2-rich natural springs. We collected water samples and effervescent gases at the springs as well as soil gases for chemical and isotopic analyses. The analytical parameters included major anions and cations, δ13C & δ18O of CO2, δD & δ18O of H2O and δ13C of dissolved inorganic carbon (DIC). Preliminary results revealed that δ13C values of CO2 in most groundwater and soil samples were similar. Oxygen isotope measurements revealed equilibrium between CO2 and H2O-oxygen in most samples, but except for a limited number of samples, δ18O values of water did not deviate significantly from the local meteoric water line. Our preliminary results suggest that both the groundwater and the soil sampling approaches should be capable of detecting leakage of CO2 provided that the leaking gas has a distinct isotopic

  5. 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

  6. Ancient and modern sites of natural CO2 leakage: Geochemistry and geochronology of Quaternary and modern travertine deposits on the Colorado Plateau, USA, and implications for CO2 sequestration

    NASA Astrophysics Data System (ADS)

    Priewisch, A.; Crossey, L. J.; Karlstrom, K. E.; McPherson, B. J.; Mozley, P.

    2013-12-01

    Travertine-precipitating springs and travertine deposits of the Colorado Plateau serve as natural analogues for evaluating potential leakage associated with geologic sequestration of carbon dioxide (CO2). Extensive Quaternary and modern travertine deposits occur along the Jemez lineament and Rio Grande rift in New Mexico and Arizona, and in the Paradox Basin in Utah, along the Little Grand Wash Fault and the Salt Wash Graben. These groundwater discharge deposits are interpreted to be sites of persistent and significant CO2 degassing along faults and above magmatic systems. Analysis of the geochemical and isotopic composition of U-series dated travertine deposits and modern travertine-precipitating waters allows evaluation of the flow paths of CO2-charged waters. Initial results from New Mexico and Arizona travertine deposits show characteristic rare earth element (REE) signatures for individual travertine deposits and yet generally overlap in concentrations of other trace elements such as Al, As, B, Ba, K, and Si. We report stable oxygen and carbon isotopes of the travertines in New Mexico, Arizona, and Utah. Different travertine deposits have different carbon-oxygen isotope variation patterns suggesting that these stable isotopes are tracers that have the ability to identify distinctive groundwater sources within and between spring groups based on the travertine record. Stable isotope analyses of travertine deposits in New Mexico and Arizona overlap substantially between deposits and cluster around -10‰ to -6‰ for δ18O and around 3.5‰ to 6.5‰ for δ13C. Travertine deposits in Utah show a distinctly different range of stable isotope values: δ18O values cluster around -14‰ to -10.5‰ and δ13C around 4.5‰ to 6.5‰. U-series dating of travertine deposits shows episodic travertine formation in New Mexico and Arizona over the last 700,000 years, and travertine accumulation over the last 400,000 years in Utah. We use U-series dating and volumetric

  7. Investigation of Transient, Turbulent Natural Convection in Vertical Tubes for Thermal Energy Storage in Supercritical CO2

    NASA Astrophysics Data System (ADS)

    Baghaei Lakeh, Reza; Lavine, Adrienne S.; Kavehpour, H. Pirouz; Wirz, Richard E.

    2013-11-01

    Heat transfer can be a limiting factor in the operation of thermal energy storage, including sensible heat and latent heat storage systems. Poor heat transfer between the energy storage medium and the container walls impairs the functionality of the thermal storage unit by requiring excessively long times to charge or discharge the system. In this study, the effect of turbulent, unsteady buoyancy-driven flow on heat transfer in vertical storage tubes containing supercritical CO2 as the storage medium is investigated computationally. The heat transfer from a constant-temperature wall to the storage fluid is studied during the charge cycle. The results of this study show that turbulent natural convection dominates the heat transfer mechanism and significantly reduces the required time for charging compared to pure conduction. Changing the L/D ratio of the storage tube has a major impact on the charge time. The charge time shows a decreasing trend with RaL. The non-dimensional model of the problem shows that Nusselt number and non-dimensional mean temperature of the storage fluid in different configurations of the tube is a function Buoyancy-Fourier number defined as of FoL * RaLm* L/D. This study was supported by award No. DE-AR0000140 granted by U.S. Department of Energy under Advanced Research Projects Agency - Energy (ARPA-E) and by award No. 5660021607 granted by Southern California Gas Company.

  8. Tunable Diode Laser Absorption Spectroscopy Sensor for Calibration Free Humidity Measurements in Pure Methane and Low CO2 Natural Gas.

    PubMed

    Nwaboh, Javis Anyangwe; Pratzler, Sonja; Werhahn, Olav; Ebert, Volker

    2017-05-01

    We report a new direct tunable diode laser absorption spectroscopy (dTDLAS) sensor for absolute measurements of H2O in methane, ethane, propane, and low CO2 natural gas. The sensor is operated with a 2.7 µm DFB laser, equipped with a high pressure single pass gas cell, and used to measure H2O amount of substance fractions in the range of 0.31-25 000 µmol/mol. Operating total gas pressures are up to 5000 hPa. The sensor has been characterized, addressing the traceability of the spectrometric results to the SI and the evaluation of the combined uncertainty, following the guide to the expression of uncertainty in measurement (GUM). The relative reproducibility of H2O amount of substance fraction measurements at 87 µmol/mol is 0.26% (0.23 µmol/mol). The maximum precision of the sensor was determined using a H2O in methane mixture, and found to be 40 nmol/mol for a time resolution of 100 s. This corresponds to a normalized detection limit of 330 nmol mol(-1)·m Hz(-1/2). The relative combined uncertainty of H2O amount fraction measurements delivered by the sensor is 1.2%.

  9. Preliminary evidences of CCM operation and its down regulation in relation to increasing CO2 levels in natural phytoplankton assemblages from the coastal waters of Bay of Bengal

    NASA Astrophysics Data System (ADS)

    Biswas, Haimanti; Rahman Shaik, Aziz Ur; Bandyopadhyay, Debasmita

    2014-05-01

    Bay of Bengal (BoB), a low productive part of the North Indian Ocean, often possesses low CO2 levels in its surface water and diatoms dominate the phytoplankton communities. Virtually no studies are available from this area reporting how this diatom dominated phytoplankton community would respond any increase in dissolved CO2 levels either naturally or anthopogenically. In most of the marine phytoplankton, the inefficiency of the sole carbon fixing enzyme Rubisco necessitates the need of concentrating dissolved inorganic carbon (DIC) (mostly as HCO3) inside the cell in excess of the ambient water concentrations in order to maintain high rate of photosynthesis under low CO2 levels through an energy consuming carbon concentration mechanisms (CCMs). The ubiquitous enzyme carbonic anhydrase (CA) plays a vital role in CCMs by converting HCO3- to CO2 and usually utilizes the trace metal zinc (Zn) as a cofactor. However, it is evident in many marine phytoplankton species that with increasing external CO2 levels, CCMs can be down-regulated leading to energetic savings which can be reallocated to growth; although exceptions occur. Hence, in order to predict their responses to the projected changes, it is imperative to understand their carbon metabolism patterns. We have conducted a series of incubation experiments in microcosms with natural phytoplankton communities from the coastal waters of BoB under different CO2 levels. Our results revealed that the rate of net photosynthetic oxygen evolution and biomass build-up increased in response to increasing CO2 levels. The depletion in δ13CPOM values were more in the high CO2 treatments relative to the low CO2 treated cells (control), indicating that dissolved CO2 uptake was higher when CO2 levels were increased. When additional Zn was added to the low CO2 treated cells, net photosynthetic oxygen evolution rate was increased significantly than that of the untreated control. It is likely that upon the supply of Zn under low CO2

  10. Macrofaunal Biodiversity Response to Natural Gradients of Multiple Stressors on Continental Margins

    NASA Astrophysics Data System (ADS)

    Sperling, E. A.; Frieder, C.; Levin, L. A.

    2015-12-01

    Sharp increases in atmospheric CO2 are resulting in ocean warming, acidification and deoxygenation. Rates of change are unprecedented, raising questions about whether (and how) communities will adapt and if responses will reflect synergistic interactions among multiple stressors. Changes to benthic biodiversity on continental margins have important implications for carbon cycle processes and other ecosystem services. One strategy to interpret adaptation potential and predict future faunal change is to examine ecological shifts along natural gradients in the modern ocean. Here, we assess the explanatory power of major climate stressors for macrofaunal diversity and evenness along continental margins using variance partitioning techniques. Sharp drops in diversity are seen as O2 levels decline through the 0.5 - 0.15 ml/l (~22 - 6 μM; ~21 - 5 matm) range, and as temperature increases through the 7-10°C range. pCO2 shows a strong effect in the Arabian Sea but very little effect in the Eastern Pacific Ocean. In contrast, very little variation in evenness is explained by these three global change variables. The identification of sharp thresholds in ecological response are used here to predict seafloor areas most at risk to future marine global change, although the existence of clear regional differences cautions against applying global thresholds.

  11. Biodiversity response to natural gradients of multiple stressors on continental margins.

    PubMed

    Sperling, Erik A; Frieder, Christina A; Levin, Lisa A

    2016-04-27

    Sharp increases in atmospheric CO2 are resulting in ocean warming, acidification and deoxygenation that threaten marine organisms on continental margins and their ecological functions and resulting ecosystem services. The relative influence of these stressors on biodiversity remains unclear, as well as the threshold levels for change and when secondary stressors become important. One strategy to interpret adaptation potential and predict future faunal change is to examine ecological shifts along natural gradients in the modern ocean. Here, we assess the explanatory power of temperature, oxygen and the carbonate system for macrofaunal diversity and evenness along continental upwelling margins using variance partitioning techniques. Oxygen levels have the strongest explanatory capacity for variation in species diversity. Sharp drops in diversity are seen as O2 levels decline through the 0.5-0.15 ml l(-1) (approx. 22-6 µM; approx. 21-5 matm) range, and as temperature increases through the 7-10°C range. pCO2 is the best explanatory variable in the Arabian Sea, but explains little of the variance in diversity in the eastern Pacific Ocean. By contrast, very little variation in evenness is explained by these three global change variables. The identification of sharp thresholds in ecological response are used here to predict areas of the seafloor where diversity is most at risk to future marine global change, noting that the existence of clear regional differences cautions against applying global thresholds.

  12. Biodiversity Response to Natural Gradients of Multiple Stressors on Continental Margins

    NASA Astrophysics Data System (ADS)

    Sperling, E. A.; Frieder, C.; Levin, L. A.

    2016-02-01

    Sharp increases in atmospheric CO2 are resulting in ocean warming, acidification and deoxygenation that threaten marine organisms. Resulting changes to benthic biodiversity on continental margins can alter carbon cycle processes and other ecosystem services. The relative importance of these stressors for biodiversity remains unclear though, as well as the threshold levels for change and when secondary stressors become important. One strategy to interpret adaptation potential and predict future faunal change is to examine ecological shifts along natural gradients in the modern ocean. Here, we assess the explanatory power of major climate stressors for macrofaunal diversity and evenness along continental margins using variance partitioning techniques. Sharp drops in diversity are seen as O2 levels decline through the 0.5 - 0.15 ml/l ( 22 - 6 μM; 21 - 5 matm) range, and as temperature increases through the 7-10°C range. pCO2 shows a strong effect in the Arabian Sea but very little effect in the Eastern Pacific Ocean. In contrast, very little variation in evenness is explained by these three global change variables. The identification of sharp thresholds in ecological response are used here to predict seafloor areas most at risk to future marine global change, although the existence of clear regional differences cautions against applying global thresholds.

  13. Biodiversity response to natural gradients of multiple stressors on continental margins

    PubMed Central

    Sperling, Erik A.; Frieder, Christina A.; Levin, Lisa A.

    2016-01-01

    Sharp increases in atmospheric CO2 are resulting in ocean warming, acidification and deoxygenation that threaten marine organisms on continental margins and their ecological functions and resulting ecosystem services. The relative influence of these stressors on biodiversity remains unclear, as well as the threshold levels for change and when secondary stressors become important. One strategy to interpret adaptation potential and predict future faunal change is to examine ecological shifts along natural gradients in the modern ocean. Here, we assess the explanatory power of temperature, oxygen and the carbonate system for macrofaunal diversity and evenness along continental upwelling margins using variance partitioning techniques. Oxygen levels have the strongest explanatory capacity for variation in species diversity. Sharp drops in diversity are seen as O2 levels decline through the 0.5–0.15 ml l−1 (approx. 22–6 µM; approx. 21–5 matm) range, and as temperature increases through the 7–10°C range. pCO2 is the best explanatory variable in the Arabian Sea, but explains little of the variance in diversity in the eastern Pacific Ocean. By contrast, very little variation in evenness is explained by these three global change variables. The identification of sharp thresholds in ecological response are used here to predict areas of the seafloor where diversity is most at risk to future marine global change, noting that the existence of clear regional differences cautions against applying global thresholds. PMID:27122565

  14. Natural Variation in Arabidopsis Cvi-0 Accession Reveals an Important Role of MPK12 in Guard Cell CO2 Signaling.

    PubMed

    Jakobson, Liina; Vaahtera, Lauri; Tõldsepp, Kadri; Nuhkat, Maris; Wang, Cun; Wang, Yuh-Shuh; Hõrak, Hanna; Valk, Ervin; Pechter, Priit; Sindarovska, Yana; Tang, Jing; Xiao, Chuanlei; Xu, Yang; Gerst Talas, Ulvi; García-Sosa, Alfonso T; Kangasjärvi, Saijaliisa; Maran, Uko; Remm, Maido; Roelfsema, M Rob G; Hu, Honghong; Kangasjärvi, Jaakko; Loog, Mart; Schroeder, Julian I; Kollist, Hannes; Brosché, Mikael

    2016-12-01

    Plant gas exchange is regulated by guard cells that form stomatal pores. Stomatal adjustments are crucial for plant survival; they regulate uptake of CO2 for photosynthesis, loss of water, and entrance of air pollutants such as ozone. We mapped ozone hypersensitivity, more open stomata, and stomatal CO2-insensitivity phenotypes of the Arabidopsis thaliana accession Cvi-0 to a single amino acid substitution in MITOGEN-ACTIVATED PROTEIN (MAP) KINASE 12 (MPK12). In parallel, we showed that stomatal CO2-insensitivity phenotypes of a mutant cis (CO2-insensitive) were caused by a deletion of MPK12. Lack of MPK12 impaired bicarbonate-induced activation of S-type anion channels. We demonstrated that MPK12 interacted with the protein kinase HIGH LEAF TEMPERATURE 1 (HT1)-a central node in guard cell CO2 signaling-and that MPK12 functions as an inhibitor of HT1. These data provide a new function for plant MPKs as protein kinase inhibitors and suggest a mechanism through which guard cell CO2 signaling controls plant water management.

  15. Natural Variation in Arabidopsis Cvi-0 Accession Reveals an Important Role of MPK12 in Guard Cell CO2 Signaling

    PubMed Central

    Nuhkat, Maris; Wang, Cun; Wang, Yuh-Shuh; Hõrak, Hanna; Valk, Ervin; Pechter, Priit; Sindarovska, Yana; Tang, Jing; Xiao, Chuanlei; Xu, Yang; Gerst Talas, Ulvi; García-Sosa, Alfonso T.; Kangasjärvi, Saijaliisa; Maran, Uko; Remm, Maido; Roelfsema, M. Rob G.; Hu, Honghong; Kangasjärvi, Jaakko; Loog, Mart; Schroeder, Julian I.; Kollist, Hannes; Brosché, Mikael

    2016-01-01

    Plant gas exchange is regulated by guard cells that form stomatal pores. Stomatal adjustments are crucial for plant survival; they regulate uptake of CO2 for photosynthesis, loss of water, and entrance of air pollutants such as ozone. We mapped ozone hypersensitivity, more open stomata, and stomatal CO2-insensitivity phenotypes of the Arabidopsis thaliana accession Cvi-0 to a single amino acid substitution in MITOGEN-ACTIVATED PROTEIN (MAP) KINASE 12 (MPK12). In parallel, we showed that stomatal CO2-insensitivity phenotypes of a mutant cis (CO2-insensitive) were caused by a deletion of MPK12. Lack of MPK12 impaired bicarbonate-induced activation of S-type anion channels. We demonstrated that MPK12 interacted with the protein kinase HIGH LEAF TEMPERATURE 1 (HT1)—a central node in guard cell CO2 signaling—and that MPK12 functions as an inhibitor of HT1. These data provide a new function for plant MPKs as protein kinase inhibitors and suggest a mechanism through which guard cell CO2 signaling controls plant water management. PMID:27923039

  16. Aboveground net primary productivity and rainfall use efficiency of grassland on three soils after two years of exposure to a subambient to superambient CO2 gradient

    USDA-ARS?s Scientific Manuscript database

    Atmospheric CO2 concentrations (CA) have increased by about 100 µL L-1 over the last 250 years to ~ 380 µL L-1, the highest values in the last half-million years, and CA is expected to continue to increase to greater than 500 µL L-1 by 2100. CO2 enrichment has been shown to affect many ecosystem pr...

  17. Comparison of natural aquifer geochemical variability with uncertainty from model-predicted CO2 induced geochemical changes: How detectable is leakage from carbon sequestration sites?

    NASA Astrophysics Data System (ADS)

    Navarre-Sitchler, A. K.; Moore, J.

    2012-12-01

    Leakage of CO2 from underground formations poses risk to the storage permanence goal of 99% of injected CO2 remaining sequestered from the atmosphere, which is needed to mitigate potential global climate change. Additionally, leaked CO2 that invades overlying shallow aquifers may cause deleterious changes to groundwater quality and pose risks to environmental and human health. For these reasons, technologies for monitoring, measurement and accounting of injected CO2 are necessary for regulation and permitting of CO2 sequestration operations. Changes in groundwater geochemistry induced by CO2 leakage offer a potential diagnostic tool for identifying leakage into shallow aquifers. In order to confidently use geochemical parameters as indicators of leakage, however, natural variability in geochemical concentrations and uncertainty in predicted geochemical changes induced by CO2 leakage must be quantitatively evaluated. For leakage monitoring, spatial variability of geochemical parameters such as alkalinity, pH, and specific conductivity is less relevant than temporal variability of these parameters within a given well. We used geochemical data from the Ohio Environmental Protection Agency, Ambient Ground Water Monitoring Network to characterize geochemical variability within individual wells. We selected wells from limestone, sandstone, and unconsolidated aquifers with ≥15 samples (typically annual) and statistically analyzed variability in alkalinity, pH, and specific conductance using median and interquartile range (IQR) to avoid influence by outliers and non-gaussian distributions. Neither the medians nor the IQRs showed correlation with well depth, sampling month, or number of samples. Our results indicate that variability in alkalinity and pH (4 - 12%) within individual wells is lower than specific conductance (28 - 32%), and thus, alkalinity and pH potentially provide more robust indicators. Uncertainty in predicted alkalinity and pH changes due to uncertainty

  18. In Situ 13C and 23Na Magic Angle Spinning NMR Investigation of Supercritical CO2 Incorporation in Smectite-Natural Organic Matter Composites

    SciTech Connect

    Bowers, Geoffrey M.; Hoyt, David W.; Burton, Sarah D.; Ferguson, Brennan O.; Varga, Tamas; Kirkpatrick, Robert J.

    2014-01-29

    This paper presents an in situ NMR study of clay-natural organic polymer systems (a hectoritehumic acid [HA] composite) under CO2 storage reservoir conditions (90 bars CO2 pressure, 50°C). The 13C and 23Na NMR data show that supercritical CO2 interacts more strongly with the composite than with the base clay and does not react to form other C-containing species over several days at elevated CO2. With and without organic matter, the data suggest that CO2 enters the interlayer space of Na-hectorite equilibrated at 43% relative humidity. The presence of supercritical CO2 also leads to increased 23Na signal intensity, reduced line width at half height, increased basal width, more rapid 23Na T1 relaxation rates, and a shift to more positive resonance frequencies. Larger changes are observed for the hectorite-HA composite than for the base clay. In light of recently reported MD simulations of other polymer-Na-smectite composites, we interpret the observed changes as an increase in the rate of Na+ site hopping in the presence of supercritical CO2, the presence of potential new Na+ sorption sites when the humic acid is present, and perhaps an accompanying increase in the number of Na+ ions actively involved in site hopping. The results suggest that the presence of organic material either in clay interlayers or on external particle surfaces can significantly affect the behavior of supercritical CO2 and the mobility of metal ions in reservoir rocks.

  19. A Global Synthesis Inversion Analysis of Recent Variability in Natural CO2 Fluxes Using Gosat and in Situ Observations

    NASA Astrophysics Data System (ADS)

    Wang, J. S.; Kawa, S. R.; Collatz, G. J.

    2014-12-01

    About one-half of the CO2 emissions from fossil fuel combustion and deforestation accumulates in the atmosphere, where it contributes to global warming. The rest is taken up by vegetation and the ocean. The precise contribution of the two, and the location and year-to-year variability of the CO2 sinks are, however, not well understood. We use a batch Bayesian inversion approach to deduce the global spatiotemporal distributions of CO2 fluxes during 2009-2010. For prior constraints, we utilize fluxes from the CASA-GFED model of the terrestrial biosphere and biomass burning driven by satellite observations and interannually varying meteorology. We also use measurement-based ocean flux estimates, and fixed fossil CO2 emissions. Here, we present results from our inversions that incorporate column CO2 measurements from the GOSAT satellite (ACOS retrieval, filtered and bias-corrected) and in situ observations (individual flask and afternoon-average continuous observations) to estimate fluxes in 108 regions over 8-day intervals. Relationships between fluxes and atmospheric concentrations are derived using the PCTM atmospheric transport model run at 2° x 2.5° (latitude/longitude) resolution driven by meteorology from the MERRA reanalysis. We evaluate the posterior CO2 concentrations using independent aircraft and other data sets. The optimized fluxes generally resemble those from other inversion systems using different techniques, for example indicating a net terrestrial biospheric CO2 sink, and a shift in the sink from tropics to northern high latitudes when going from an in-situ-only inversion to a GOSAT inversion. We show that in this inversion framework, GOSAT provides better flux estimates in most regions with its greater spatial coverage, but we also discuss impacts of possible remaining biases in the data.

  20. In Situ Natural Abundance (17)O and (25)Mg NMR Investigation of Aqueous Mg(OH)2 Dissolution in the Presence of Supercritical CO2.

    PubMed

    Hu, Mary Y; Deng, Xuchu; Thanthiriwatte, K Sahan; Jackson, Virgil E; Wan, Chuan; Qafoku, Odeta; Dixon, David A; Felmy, Andrew R; Rosso, Kevin M; Hu, Jian Zhi

    2016-11-15

    We report an in situ high-pressure NMR capability that permits natural abundance (17)O and (25)Mg NMR characterization of dissolved species in aqueous solution and in the presence of supercritical CO2 fluid (scCO2). The dissolution of Mg(OH)2 (brucite) in a multiphase water/scCO2 fluid at 90 atm pressure and 50 °C was studied in situ, with relevance to geological carbon sequestration. (17)O NMR spectra allowed identification and distinction of various fluid species including dissolved CO2 in the H2O-rich phase, scCO2, aqueous H2O, and HCO3(-). The widely separated spectral peaks for various species can all be observed both dynamically and quantitatively at concentrations as low as 20 mM. Measurement of the concentrations of these individual species also allows an in situ estimate of the hydrogen ion concentration, or pCH(+) values, of the reacting solutions. The concentration of Mg(2+) can be observed by natural abundance (25)Mg NMR at a concentration as low as 10 mM. Quantum chemistry calculations of the NMR chemical shifts on cluster models aided in the interpretation of the experimental results. Evidence for the formation of polymeric Mg(2+) clusters at high concentrations in the H2O-rich phase, a possible critical step needed for magnesium carbonate formation, was found.

  1. Coupling of Multiphase Flow and Geomechanics in Fractured Porous Media: Application to CO2 Leakages from Natural and Stimulated Fractures

    NASA Astrophysics Data System (ADS)

    Ezzedine, S. M.

    2015-12-01

    Leakage to the atmosphere of a significant fraction of injected CO2 would constitute a failure of a geological CO2 storage project from a greenhouse gas mitigation perspective. We present a numerical model that simulates flow and transport of CO2 into heterogeneous subsurface systems. The model, StoTran, is a flexible numerical environment that uses state-of-the-art finite element and finite volume methods and unstructured adaptive mesh refinement scheme implemented using MPI and OpenMP protocols. Multiphase flow equations and the geomechanical equations are implicitly solved and either fully or sequentially coupled. StoTran can address inverse and forward problems under deterministic or stochastic conditions. For the current study, StoTran has been used to simulate several scenarios spanning from a homogeneous single layered reservoir to heterogeneous multi-layered systems, which including cap-rock with embedded fractures, have been simulated under different operations of CO2 injection and CO2 leakages conditions. Results show the impact of the injection and leakage rates on the time evolution of the spread of the CO2 plume, its interception of the fractured cap-rock and the risk associated with the contamination of the overlaying aquifer. Spatial and temporal moments have been calculated for different, deterministic of stochastic, subsurface physical and chemical properties. Spatial moments enable assessing the extent of the region of investigation under conditions of uncertainty. Furthermore, several leakage scenarios show the intermittence behavior and development of the CO2 plume in the subsurface; its first interception with the fractures located further far from the injection well then, at a second stage, its interception with the fracture within the immediate vicinity of the injection well. We will present a remedy to CO2 leakages from the reservoir in order to enhance a long term containment of the injected CO2. This work performed under the auspices of

  2. Contributions to accelerating atmospheric CO2 growth from economic activity, carbon intensity, and efficiency of natural sinks

    PubMed Central

    Canadell, Josep G.; Le Quéré, Corinne; Raupach, Michael R.; Field, Christopher B.; Buitenhuis, Erik T.; Ciais, Philippe; Conway, Thomas J.; Gillett, Nathan P.; Houghton, R. A.; Marland, Gregg

    2007-01-01

    The growth rate of atmospheric carbon dioxide (CO2), the largest human contributor to human-induced climate change, is increasing rapidly. Three processes contribute to this rapid increase. Two of these processes concern emissions. Recent growth of the world economy combined with an increase in its carbon intensity have led to rapid growth in fossil fuel CO2 emissions since 2000: comparing the 1990s with 2000–2006, the emissions growth rate increased from 1.3% to 3.3% y−1. The third process is indicated by increasing evidence (P = 0.89) for a long-term (50-year) increase in the airborne fraction (AF) of CO2 emissions, implying a decline in the efficiency of CO2 sinks on land and oceans in absorbing anthropogenic emissions. Since 2000, the contributions of these three factors to the increase in the atmospheric CO2 growth rate have been ≈65 ± 16% from increasing global economic activity, 17 ± 6% from the increasing carbon intensity of the global economy, and 18 ± 15% from the increase in AF. An increasing AF is consistent with results of climate–carbon cycle models, but the magnitude of the observed signal appears larger than that estimated by models. All of these changes characterize a carbon cycle that is generating stronger-than-expected and sooner-than-expected climate forcing. PMID:17962418

  3. A natural experiment on plant acclimation: lifetime stomatal frequency response of an individual tree to annual atmospheric CO2 increase.

    PubMed

    Wagner, F; Below, R; Klerk, P D; Dilcher, D L; Joosten, H; Kürschner, W M; Visscher, H

    1996-10-15

    Carbon dioxide (CO2) has been increasing in atmospheric concentration since the Industrial Revolution. A decreasing number of stomata on leaves of land plants still provides the only morphological evidence that this man-made increase has already affected the biosphere. The current rate of CO2 responsiveness in individual long-lived species cannot be accurately determined from field studies or by controlled-environment experiments. However, the required long-term data sets can be obtained from continuous records of buried leaves from living trees in wetland ecosystems. Fine-resolution analysis of the lifetime leaf record of an individual birch (Betula pendula) indicates a gradual reduction of stomatal frequency as a phenotypic acclimation to CO2 increase. During the past four decades, CO2 increments of 1 part per million by volume resulted in a stomatal density decline of approximately 0.6%. It may be hypothesized that this plastic stomatal frequency response of deciduous tree species has evolved in conjunction with the overall Cenozoic reduction of atmospheric CO2 concentrations.

  4. Adaptive fine root foraging patterns in climate experiments and natural gradients

    NASA Astrophysics Data System (ADS)

    Ostonen, Ivika; Truu, Marika; Parts, Kaarin; Truu, Jaak

    2017-04-01

    Site based manipulative experiments and studies along climatic gradients have long been keystones of ecological research. We aimed to compare the response of ectomycorrhizal (EcM) and fine roots in manipulative studies and along climate gradient to describe the universal trends in root traits and to raise hypotheses about general mechanisms in fine root system adaptation of forest trees in global change. The root traits from two climate manipulation experiments - Bangor FACE and FAHM in Estonia, manipulated by CO2 concentration and relative air humidity in silver birch forest ecosystems, respectively and the data for three most ubiquitous tree species - Norway spruce (Picea abies), Scots pine (Pinus sylvestris) and silver birch (Betula pendula) stands along natural gradient encompassing different climate and forest zones in Northern Europe were analysed. There are two main strategies in response of fine root system of trees: A) an extensive increase in absorptive root biomass, surface area and length, or B) a greater reliance on root-associated EcM fungi and bacterial communities with a smaller investment to absorptive root biomass. Trees in all studies tended to increase the EcM root biomass and the proportion of EcM root biomass of total fine root biomass towards harsh (northern boreal forests) or changed conditions (stress created by the increase in CO2 concentration or relative air humidity). We envisage a role of trilateral relation between the morphological traits of absorptive fine roots, exploration types of colonising EcM fungi and rhizosphere and bulk soil bacterial community structure. A significant change in EcM absorptive fine root biomass in all experiments and for all studied tree species coincided with changes in absorptive root morphology, being longer and thinner root tips with higher root tissue density in poor/treated sites. These changes were associated with significant shifts in community structure of dominating EcM fungi as well as soil and

  5. CO2 leakage impacts on shallow groundwater. Field-scale reactive-transport simulations informed by observations at a natural analog site

    DOE PAGES

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

    2013-03-01

    It is challenging to predict the degree to which shallow groundwater might be affected by leaks from a CO2 sequestration reservoir, particularly over long time scales and large spatial scales. In this study observations at a CO2 enriched shallow aquifer natural analog were used to develop a predictive model which is then used to simulate leakage scenarios. This natural analog provides the opportunity to make direct field observations of groundwater chemistry in the presence of elevated CO2, to collect aquifer samples and expose them to CO2 under controlled conditions in the laboratory, and to test the ability of multiphase reactivemore » transport models to reproduce measured geochemical trends at the field-scale. The field observations suggest that brackish water entrained with the upwelling CO2 are a more significant source of trace metals than in situ mobilization of metals due to exposure to CO2. The study focuses on a single trace metal of concern at this site: U. Experimental results indicate that cation exchange/adsorption and dissolution/precipitation of calcite containing trace amounts of U are important reactions controlling U in groundwater at this site, and that the amount of U associated with calcite is fairly well constrained. Simulations incorporating these results into a 3-D multi-phase reactive transport model are able to reproduce the measured ranges and trends between pH, pCO2, Ca, total C, U and Cl-at the field site. Although the true fluxes at the natural analog site are unknown, the cumulative CO2 flux inferred from these simulations are approximately equivalent to 37.8E-3 MT, approximately corresponding to a .001% leak rate for injection at a large (750 MW) power plant. The leakage scenario simulations suggest that if the leak only persists for a short time the volume of aquifer contaminated by CO2-induced mobilization of U will be relatively small, yet persistent over 100 a.« less

  6. Combined effects of CO2 enrichment, changes in diurnal light level and water stress on foliar metabolites of potato plants grown in naturally sunlit controlled environment chambers

    USDA-ARS?s Scientific Manuscript database

    Potato plants (Solanum tuberosum L. cv Kennebec) were grown in outdoor, naturally sunlit, soil-plant-atmosphere research (SPAR) chambers. Drought treatments were imposed at post-tuber initiation stage to assess water stress effects on leaf metabolites, and interactions with enriched CO2 concentrati...

  7. A Global Perspective of Atmospheric CO2 Concentrations

    NASA Technical Reports Server (NTRS)

    Putman, William M.; Ott, Lesley; Darmenov, Anton; daSilva, Arlindo

    2016-01-01

    Carbon dioxide (CO2) is the most important greenhouse gas affected by human activity. About half of the CO2 emitted from fossil fuel combustion remains in the atmosphere, contributing to rising temperatures, while the other half is absorbed by natural land and ocean carbon reservoirs. Despite the importance of CO2, many questions remain regarding the processes that control these fluxes and how they may change in response to a changing climate. The Orbiting Carbon Observatory-2 (OCO-2), launched on July 2, 2014, is NASA's first satellite mission designed to provide the global view of atmospheric CO2 needed to better understand both human emissions and natural fluxes. This visualization shows how column CO2 mixing ratio, the quantity observed by OCO-2, varies throughout the year. By observing spatial and temporal gradients in CO2 like those shown, OCO-2 data will improve our understanding of carbon flux estimates. But, CO2 observations can't do that alone. This visualization also shows that column CO2 mixing ratios are strongly affected by large-scale weather systems. In order to fully understand carbon flux processes, OCO-2 observations and atmospheric models will work closely together to determine when and where observed CO2 came from. Together, the combination of high-resolution data and models will guide climate models towards more reliable predictions of future conditions.

  8. Geochemistry of Springs in a Region Impacted by Natural Leakage of CO2 , Around Mammoth Mountain, Mammoth Lakes, Ca

    NASA Astrophysics Data System (ADS)

    Raskin, S.; Ellis, A. S.; Khachikian, C.; Luna, J.

    2012-12-01

    Carbon sequestration—the practice of injecting CO2 into geologic reservoirs—is a potentially effective but inadequately understood greenhouse gas mitigation method. Little is known about the impacts of CO2 on surrounding environments should reservoir leakage occur. Magma chambers beneath Mammoth Mountain, Ca, release large volumes of CO2 into the mountain's soil and water, simulating a leaking CO2 reservoir. This study examines the chemistry of springs at Mammoth Mountain in order to provide insights into the impact of elevated CO2 on water chemistry. Evans (2002) confirmed the presence of dissolved CO2 in Mammoth springs at concentrations ranging from 13.8 to 27.8 mmol/L. We hypothesize that waters will be moderately acidified by the CO2+H2O > H2CO3 reaction. Acidified waters may weather the native geology more efficiently than non-acidified waters. We analyzed and collected in-situ data and water samples from Mammoth Mountain springs on four trips during the summers of 2011 and 2012. These high elevations springs feature water temperatures ranging from 3.6 to 15.0 oC, pH values ranging from 5.36-8.26, and conductivities from 9.5-441 (μS/cm). Water emitted at low conductivity, dilute springs is likely sourced from recent snowmelt and has a smaller groundwater component. Low pH value springs are clustered on Mammoth Mountain's southwest flank. Water isotopes and major ions were analyzed to gain further insight into processes influencing these springs. Hydrogen and oxygen isotopes in spring waters conform to the global meteoric water line with δ18O ranging from -14.7 to -16.0‰ and δD ranging from -119.5 to -107.2‰. Isotopic signatures of springs farther east are progressively lighter, suggesting that springs are fed by local precipitation. Major ion analysis shows that spring's water chemistries generally fit along mixing lines between the major rhyolite, andesite, and basalt species that compose Mammoth. Springs on Mammoth's western flank, near the

  9. Natural Air-Sea Flux of CO2 in Simulations of the NASA-GISS Climate Model: Sensitivity to the Physical Ocean Model Formulation

    NASA Technical Reports Server (NTRS)

    Romanou, A.; Gregg, Watson W.; Romanski, J.; Kelley, M.; Bleck, R.; Healy, R.; Nazarenko, L.; Russell, G.; Schmidt, G. A.; Sun, S.; hide

    2013-01-01

    Results from twin control simulations of the preindustrial CO2 gas exchange (natural flux of CO2) between the ocean and the atmosphere are presented here using the NASA-GISS climate model, in which the same atmospheric component (modelE2) is coupled to two different ocean models, the Russell ocean model and HYCOM. Both incarnations of the GISS climate model are also coupled to the same ocean biogeochemistry module (NOBM) which estimates prognostic distributions for biotic and abiotic fields that influence the air-sea flux of CO2. Model intercomparison is carried out at equilibrium conditions and model differences are contrasted with biases from present day climatologies. Although the models agree on the spatial patterns of the air-sea flux of CO2, they disagree on the strength of the North Atlantic and Southern Ocean sinks mainly because of kinematic (winds) and chemistry (pCO2) differences rather than thermodynamic (SST) ones. Biology/chemistry dissimilarities in the models stem from the different parameterizations of advective and diffusive processes, such as overturning, mixing and horizontal tracer advection and to a lesser degree from parameterizations of biogeochemical processes such as gravitational settling and sinking. The global meridional overturning circulation illustrates much of the different behavior of the biological pump in the two models, together with differences in mixed layer depth which are responsible for different SST, DIC and nutrient distributions in the two models and consequently different atmospheric feedbacks (in the wind, net heat and freshwater fluxes into the ocean).

  10. Reduced emissions of CO2, NOx, and SO2 from U.S. power plants owing to switch from coal to natural gas with combined cycle technology

    NASA Astrophysics Data System (ADS)

    de Gouw, J. A.; Parrish, D. D.; Frost, G. J.; Trainer, M.

    2014-02-01

    Since 1997, an increasing fraction of electric power has been generated from natural gas in the United States. Here we use data from continuous emission monitoring systems (CEMS), which measure emissions at the stack of most U.S. electric power generation units, to investigate how this switch affected the emissions of CO2, NOx, and SO2. Per unit of energy produced, natural gas power plants equipped with combined cycle technology emit on an average 44% of the CO2 compared with coal power plants. As a result of the increased use of natural gas, CO2 emissions from U.S. fossil-fuel power plants were 23% lower in 2012 than they would have been if coal had continued to provide the same fraction of electric power as in 1997. In addition, natural gas power plants with combined cycle technology emit less NOx and far less SO2 per unit of energy produced than coal power plants. Therefore, the increased use of natural gas has led to emission reductions of NOx (40%) and SO2 (44%), in addition to those obtained from the implementation of emission control systems on coal power plants. These benefits to air quality and climate should be weighed against the increase in emissions of methane, volatile organic compounds, and other trace gases that are associated with the production, processing, storage, and transport of natural gas.

  11. A Global Synthesis Inversion Analysis of Recent Variability in Natural CO2 Fluxes Using GOSAT and In Situ Observations

    NASA Astrophysics Data System (ADS)

    Wang, J. S.; Kawa, S. R.; Collatz, G. J.

    2013-12-01

    Around one-half of the CO2 emissions from fossil fuel combustion and deforestation accumulates in the atmosphere, where it contributes to global warming. The rest is taken up by vegetation and the ocean. The precise contribution of the two, and the location and year-to-year variability of the CO2 sinks are not well understood though. We use a batch Bayesian inversion approach to deduce the global spatiotemporal distributions of CO2 fluxes during 2009-2010. For prior constraints, we utilize fluxes from the CASA-GFED v.3 model of the terrestrial biosphere and biomass burning driven by satellite observations and interannually varying meteorology. We also use measurement-based ocean flux estimates from Takahashi et al. [2009], and fixed fossil CO2 emissions from the CDIAC dataset. Here, we present preliminary results from our inversions that incorporate column CO2 measurements from the GOSAT satellite, ground-based observations (individual flask and afternoon-average continuous observations), and aircraft observations to estimate fluxes in 108 regions over 8-day intervals. Relationships between fluxes and atmospheric concentrations are derived using the PCTM atmospheric transport model run at 2° x 2.5° (latitude/longitude) resolution driven by meteorology from the MERRA reanalysis. We obtain spatiotemporal distributions of fluxes resembling those from other inversions, including NOAA's CarbonTracker. We compare the a posteriori fluxes obtained with and without the addition of GOSAT observations to the in situ network, and discuss possible impacts of biases in the GOSAT data.

  12. Elevated CO2 and O3 effects on ectomycorrhizal fungal root tip communities in consideration of a post-agricultural soil nutrient gradient legacy

    Treesearch

    Carrie Andrew; Erik A. Lilleskov

    2014-01-01

    Despite the critical role of EMF in nutrient and carbon (C) dynamics, combined effects of global atmospheric pollutants on ectomycorrhizal fungi (EMF) are unclear. Here, we present research on EMF root-level community responses to elevated CO2 and O3. We discovered that belowground EMF community richness and similarity were...

  13. Solubility and Speciation of CO2 in Natural Rhyolitic Melts at 1.5-3.0 GPa - Implications for Carbon Flux in Subduction Zones via Sediment Partial Melts

    NASA Astrophysics Data System (ADS)

    Duncan, M. S.; Dasgupta, R.

    2012-12-01

    and may be as high as 1.4-1.7 wt.% CO2 [1, 2]. If 0.3 wt.% CO2 in primary arc basalts derives from 15-30% melting [3, 4] of the mantle wedge, a mantle concentration of 450-900 ppm is required. Assuming that the pre-subduction modification mantle wedge contains 37-246 ppm CO2 [5-9], addition of sediment melt amounting ~2-9% of the mantle and containing 1 wt.% CO2 is sufficient to elevate the mantle budget to the required level. If the sediment partial melts are more hydrous, the flux of the melt to deliver the required CO2 budget would be even lower. Therefore, our CO2 solubility data suggest that hydrous sediment melt could be the agent of CO2 delivery from slab to arc source mantle wedge. [1] Blundy et al. (2010) EPSL, 290, 289-301; [2] Wallace (2005) JVGR, 140, 217-240; [3] Grove et al. (2002) CMP, 142, 375-396; [4] Stolper and Newman (1994) EPSL, 121, 293-325; [5] Cartigny et al. (2008) EPSL, 265, 672-685; [6] Dasgupta and Hirschmann (2010) EPSL, 298, 1-13; [7] Hirschmann and Dasgupta (2009) CG, 262, 4-16; [8] Marty (2012) EPSL, 313, 56-66; [9] Saal et al. (2002) Nature, 419, 451-455.

  14. Soil respiration rates and δ13C(CO2) in natural beech forest (Fagus sylvatica L.) in relation to stand structure.

    PubMed

    Cater, Matjaz; Ogrinc, Nives

    2011-06-01

    Soil respiration rates were studied as a function of soil type, texture and light intensity at five selected natural beech forest stands with contrasting geology: stands on silicate bedrock at Kladje and Bricka in Pohorje, a stand on quartz sandstone at Vrhovo and two stands on a carbonate bedrock in the Karstic-Dinaric area in Kocevski Rog, Snezna jama and Rajhenav, Slovenia, during the growing season in 2005-2006. Soil respiration exhibited pronounced seasonal and spatial variations in the studied forest ecosystem plots. The CO(2) flux rates ranged from minimum averages of 2.3 μmol CO(2) m(-2) s(-1) (winter) to maximum averages of about 7 μmol CO(2) m(-2) s(-1) (summer) at all the investigated locations. An empirical model describing the relationship between soil respiration and soil temperature predicted seasonal variations in soil respiration reasonably well during 2006. Nevertheless, there were also some indications that soil moisture in relation to soil texture could influence the soil CO(2) efflux rates in both sampling seasons. It was shown that spatial variability of mean soil respiration at the investigated sites was high and strongly related to root biomass. Based on the [image omitted]  data, it was shown that new photoassimilates could account for a major part of the total soil respiration under canopy conditions in forest ecosystems where no carbonate rocks are present, indicating that microbial respiration could not always dominate bulk soil CO(2) fluxes. At Snezna jama and Rajhenav, the abiotic CO(2) derived from carbonate dissolution had a pronounced influence on CO(2) efflux accounting, on average, to ∼17%. Further spatial heterogeneity of soil respiration was clearly affected by management practice. Higher respiration rates as well as higher variability in respiration rates were observed in the virgin forest (Rajhenav) than in the management forest (Snezna jama) and could be related to a higher amount of detritus and consequently to less

  15. Types and distribution of obligate thermophilic bacteria in man-made and natural thermal gradients.

    PubMed

    Ramaley, R F; Bitzinger, K

    1975-07-01

    The types and distribution of obligate thermophilic bacteria were found to be similar in a thermal gradient resulting from man-made thermal pollution and the thermal gradients of two natural hot springs located in Colorado.

  16. Natural variability of pCO2 and pH in the Atlantic and Pacific coastal margins of the U.S

    NASA Astrophysics Data System (ADS)

    Sutton, A. J.; Sabine, C. L.; Feely, R. A.; Newton, J.; Salisbury, J.; Vandemark, D. C.; Musielewicz, S. B.; Maenner-Jones, S.; Bott, R.; Lawrence-Slavas, N.

    2011-12-01

    The discovery that seawater chemistry is changing as a result of carbon dioxide (CO2) emissions, referred to as "ocean acidification", has prompted a large effort to understand how this changing chemistry will impact marine life. Changes in carbon chemistry have been documented in the open ocean; however, in dynamic coastal systems where many marine species live, ocean acidification and the natural biogeochemical variability that organisms are currently exposed to are poorly quantified. In 2010 we began equipping coastal moorings currently measuring pCO2 with pH and other biogeochemical sensors to measure ocean acidification parameters at 3 hour intervals in the surface water. Here we present the magnitude and diurnal to seasonal variability of pCO2 and pH during the first year of observations at 2 sites in the Atlantic and Pacific coastal margins of the U.S.: the Gulf of Maine and outer coast of Washington state. Both the magnitude and range of pCO2 and pH values were much greater at the coastal moorings compared to the open ocean mooring at Ocean Station Papa in the North Pacific and also varied between the two coastal mooring sites. We observed maximum pCO2 values in coastal waters exceeding predicted values for the open ocean at 2x pre-industrial CO2 levels. The range of pCO2 and pH values during this time series was approximately 4 times the range observed at open ocean mooring Papa (2007-2011 time series). In many cases, large variance was observed at short time scales, with values fluctuating more than 200 μatm pCO2 and 0.2 pH between 3-hour cycles. These types of observations are critical for understanding how ocean acidification will manifest in naturally dynamic coastal systems and for informing the experimental design of species response studies that aim to mimic carbon chemistry experienced by coastal marine organisms.

  17. Increased Use of Natural Gas for Power Generation in the U.S. and the Resulting Reductions in Emissions of CO2, NOx and SO2

    NASA Astrophysics Data System (ADS)

    De Gouw, J. A.; Parrish, D. D.; Trainer, M.

    2013-12-01

    Over the past decades, natural gas has increasingly replaced coal as a fuel for electrical power generation in the U.S. As a result, there have been significant reductions in the emissions of carbon dioxide (CO2), nitrogen oxides (NOx) and sulfur dioxide (SO2). Power plant emissions are continuously measured at the stack using continuous emissions monitoring systems (CEMS) required by the EPA. Previous studies using airborne measurements have shown these CEMS measurements to be accurate. Here, we use annual emissions since 1995 from all point sources included in the CEMS database to quantify the changes in CO2, NOx and SO2 emissions that have resulted from the changing use of fuels and technologies for power generation. In 1997, 83% of electrical power in the CEMS database was generated from coal-fired power plants. In 2012, the contribution from coal had decreased to 59%, and natural gas contributed 34% of the electrical power. Natural gas-fired power plants, in particular those equipped with combined cycle technology, emit less than 50% of CO2 per kWh produced compared to coal-fired plants. As a result of the increased use of natural gas, total CO2 emissions from U.S. power plants have decreased since 2008. In addition, natural gas-fired power plants emit less NOx and far less SO2 per kWh produced than coal-fired power plants. The increased use of natural gas has therefore led to significant emissions reductions of NOx and SO2 in addition to those obtained from the implementation of emissions control systems on coal-fired power plants. The increased use of natural gas for power generation has led to significant reductions in CO2 emissions as well as improvements in U.S. air quality. We will illustrate these points with examples from airborne measurements made using the NOAA WP-3D aircraft in the Southeastern U.S. in 2013 as part of the NOAA Southeast Nexus (SENEX) study. The emissions reductions from U.S. power plants due to the increased use of natural gas will

  18. Coral Calcification Across a Natural Gradient in Ocean Acidification

    NASA Astrophysics Data System (ADS)

    Cohen, A. L.; Brainard, R. E.; Young, C.; Shamberger, K. E.; McCorkle, D. C.; Feely, R. A.; Mcleod, E.; Cantin, N.; Rose, K.; Lohmann, G. P.

    2011-12-01

    Much of our understanding of the impact of ocean acidification on coral calcification comes from laboratory manipulation experiments in which corals are reared under a range of seawater pH and aragonite saturation states (μar) equivalent to those projected for the next hundred years. In general, experiments show a consistently negative impact of acidification on coral calcification, leading to predictions of mass coral reef extinctions by dissolution as natural rates of carbonate erosion exceed the rates at which corals and other reef calcifiers can replace it. The tropical oceans provide a natural laboratory within which to test hypotheses about the longer term impact and adaptive potential of corals to acidification of the reef environment. Here we report results of a study in which 3-D CT scan and imaging techniques were used to quantify annual rates of calcification by conspecifics at 12 reefs sites spanning a natural gradient in ocean acidification. In situ μar calculated from alkalinity and DIC measurements of reef seawater ranged from less than 2.7 on an eastern Pacific Reef to greater than 4.0 in the central Red Sea. No correlation between μar and calcification was observed across this range. Corals living on low μar reefs appear to be calcifying as fast, sometimes faster than conspecifics living on high μar reefs. We used total lipid and tissue thickness to index the energetic status of colonies collected at each of our study sites. Our results support the hypothesis that energetics plays a key role in the coral calcification response to ocean acidification. Indeed, the true impact of acidification on coral reefs will likely be felt as temperatures rise and the ocean becomes more stratified, depleting coral energetic reserves through bleaching and reduced nutrient delivery to oceanic reefs.

  19. An Inversion Analysis of Recent Variability in Natural CO2 Fluxes Using GOSAT and In Situ Observations

    NASA Technical Reports Server (NTRS)

    Wang, James S.; Kawa, S. Randolph; Collatz, G. James; Baker, David F.; Ott, Lesley

    2015-01-01

    About one-half of the global CO2 emissions from fossil fuel combustion and deforestation accumulates in the atmosphere, where it contributes to global warming. The rest is taken up by vegetation and the ocean. The precise contribution of the two sinks, and their location and year-to-year variability are, however, not well understood. We use two different approaches, batch Bayesian synthesis inversion and variational data assimilation, to deduce the global spatiotemporal distributions of CO2 fluxes during 2009-2010. One of our objectives is to assess different sources of uncertainties in inferred fluxes, including uncertainties in prior flux estimates and observations, and differences in inversion techniques. For prior constraints, we utilize fluxes and uncertainties from the CASA-GFED model of the terrestrial biosphere and biomass burning driven by satellite observations and interannually varying meteorology. We also use measurement-based ocean flux estimates and two sets of fixed fossil CO2 emissions. Here, our inversions incorporate column CO2 measurements from the GOSAT satellite (ACOS retrieval, filtered and bias-corrected) and in situ observations (individual flask and afternoon-average continuous observations) to estimate fluxes in 108 regions over 8-day intervals for the batch inversion and at 3 x 3.75 weekly for the variational system. Relationships between fluxes and atmospheric concentrations are derived consistently for the two inversion systems using the PCTM atmospheric transport model driven by meteorology from the MERRA reanalysis. We compare the posterior fluxes and uncertainties derived using different data sets and the two inversion approaches, and evaluate the posterior atmospheric concentrations against independent data including aircraft measurements. The optimized fluxes generally resemble those from other studies. For example, the results indicate that the terrestrial biosphere is a net CO2 sink, and a GOSAT-only inversion suggests a shift in

  20. An Inversion Analysis of Recent Variability in Natural CO2 Fluxes Using GOSAT and In Situ Observations

    NASA Astrophysics Data System (ADS)

    Wang, J. S.; Kawa, S. R.; Baker, D. F.; Collatz, G. J.; Ott, L. E.

    2015-12-01

    About one-half of the global CO2 emissions from fossil fuel combustion and deforestation accumulates in the atmosphere, where it contributes to global warming. The rest is taken up by vegetation and the ocean. The precise contribution of the two sinks, and their location and year-to-year variability are, however, not well understood. We use two different approaches, batch Bayesian synthesis inversion and variational data assimilation, to deduce the global spatiotemporal distributions of CO2 fluxes during 2009-2010. One of our objectives is to assess different sources of uncertainties in inferred fluxes, including uncertainties in prior flux estimates and observations, and differences in inversion techniques. For prior constraints, we utilize fluxes and uncertainties from the CASA-GFED model of the terrestrial biosphere and biomass burning driven by satellite observations and interannually varying meteorology. We also use measurement-based ocean flux estimates and two sets of fixed fossil CO2 emissions. Here, our inversions incorporate column CO2 measurements from the GOSAT satellite (ACOS retrieval, filtered and bias-corrected) and in situ observations (individual flask and afternoon-average continuous observations) to estimate fluxes in 108 regions over 8-day intervals for the batch inversion and at 3° x 3.75° weekly for the variational system. Relationships between fluxes and atmospheric concentrations are derived consistently for the two inversion systems using the PCTM atmospheric transport model driven by meteorology from the MERRA reanalysis. We compare the posterior fluxes and uncertainties derived using different data sets and the two inversion approaches, and evaluate the posterior atmospheric concentrations against independent data including aircraft measurements. The optimized fluxes generally resemble those from other studies. For example, the results indicate that the terrestrial biosphere is a net CO2 sink, and a GOSAT-only inversion suggests a

  1. Micro-CT imaging of reservoir condition CO2 during multi-phase flow in natural rock

    NASA Astrophysics Data System (ADS)

    Andrew, M. G.; Bijeljic, B.; Menke, H. P.; Blunt, M. J.

    2014-12-01

    Micron-resolution X-ray microtomography has allowed researchers to examine the processes controlling fluid flow behaviour at the pore scale, offering the promise of a transformation in our understanding of flow and transport in porous media. Until recently wettability has only been directly accessible in extremely simplified systems. A new method is presented for the measurement of the contact angle and capillary pressure of multiple immiscible fluids at the pore scale at reservoir conditions in the scCO2-brine-carbonate system. Contact angle is found by resampling the micro-CT data onto planes orthogonal to the contact lines, allowing for vectors to be traced along the grain surface and the scCO2 - brine interface. A distribution of contact angles ranging from 35o to 55o is observed. This distribution can be understood as the result of contact angle hysteresis and surface heterogeneity on a range of length scales. Ganglion capillary pressure for each ganglion was found by measuring the curvature of the CO2-brine interface, while the pore structure was parameterised using distance maps of the pore-space. The formation of the residual clusters by snap-off was examined by comparing the ganglion capillary pressure to local pore topography. The capillary pressure was found to be inversely proportional to the radius of the largest restriction (throat) surrounding the ganglion, which validates the imbibition mechanisms used in pore-network modelling. The potential mobilization of residual ganglia was assessed using a new formulation of both the capillary and Bond numbers, rigorously based on a balance of pore-scale forces, with the majority of ganglia remobilized at Ncmacro around 1. By the use of synchrotron tomography it is possible to create high quality 4D images of dynamic processes involving the flow of multiple fluid phases. We show how the drainage process take place as a series of discreet Haines jumps. Two different types of Haines jumps were seen, one where CO

  2. Comparison of CO2 capture by ex-situ accelerated carbonation and in in-situ naturally weathered coal fly ash.

    PubMed

    Muriithi, Grace N; Petrik, Leslie F; Fatoba, Olanrewaju; Gitari, Wilson M; Doucet, Frédéric J; Nel, Jaco; Nyale, Sammy M; Chuks, Paul E

    2013-09-30

    Natural weathering at coal power plants ash dams occurs via processes such as carbonation, dissolution, co-precipitation and fluid transport mechanisms which are responsible for the long-term chemical, physical and geochemical changes in the ash. Very little information is available on the natural carbon capture potential of wet or dry ash dams. This study investigated the extent of carbon capture in a wet-dumped ash dam and the mineralogical changes promoting CO2 capture, comparing this natural phenomenon with accelerated ex-situ mineral carbonation of fresh fly ash (FA). Significant levels of trace elements of Sr, Ba and Zr were present in both fresh and weathered ash. However Nb, Y, Sr, Th and Ba were found to be enriched in weathered ash compared to fresh ash. Mineralogically, fresh ash is made up of quartz, mullite, hematite, magnetite and lime while weathered and carbonated ashes contained additional phases such as calcite and aragonite. Up to 6.5 wt % CO2 was captured by the fresh FA with a 60% conversion of calcium to CaCO3 via accelerated carbonation (carried out at 2 h, 4Mpa, 90 °C, bulk ash and a S/L ratio of 1). On the other hand 6.8 wt % CO2 was found to have been captured by natural carbonation over a period of 20 years of wet disposed ash. Thus natural carbonation in the ash dumps is significant and may be effective in capturing CO2. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Dynamic Response of Southwest Juniper to Shifting Climate and Natural and Anthropogenic Changes in Atmospheric pCO2

    NASA Astrophysics Data System (ADS)

    Zinniker, D. A.; Holmgren, C. A.; Pagani, M.

    2008-12-01

    Fossil packrat middens in the southwestern US contribute critical details to our understanding of past climate change and floral migrations across geography and elevation. Our presentation discusses the development of a largely unexplored molecular organic archive preserved in packrat middens from the southwestern US: the stable isotopic analysis of diet-averaged taxon specific biomarkers in both modern middens from southern Arizona and New Mexico and ancient middens from the Peloncillo Mountains of SE Arizona. The stable carbon isotope values of taxon specific makers allow estimations of changing growing season intra-leaf CO2 concentrations, carbon assimilation rates, and water use efficiency. Hydrogen isotope values aid in estimating growing season relative humidity. This more specifically reflects the extent of dry season transpiration and associated deuterium enrichment and can be seen as a simplified proxy for growing season phenology in perennial desert shrubs and trees. For southwest juniper, the derived isotopic record of phenology and growth indicates a remarkable sensitivity to changes in hydrology, temperature, and pCO2. Juniper growth rates are interpreted to have increased 70% from the Last Glacial Maximum to Holocene in response to CO2 fertilization. However, a decrease in deuterium enrichment during the Bølling Allerod and Holocene indicates that elevated temperatures and limited access to soil moisture considerably shortened juniper growing seasons during these periods. Low midden preservation rates and rare juniper macrofossils in the Early and Mid Holocene provide additional evidence of overall drying and the seasonality of shallow groundwater during these periods. Increasing midden occurrence, juniper macrofossils, and deuterium enrichment in the Late Holocene suggest that afforestation during this time period was associated with lengthening juniper growing seasons. Carbon isotopic shifts between pre-industrial and modern middens suggest a 30

  4. Changes in microbial communities associated with the sea anemone Anemonia viridis in a natural pH gradient.

    PubMed

    Meron, Dalit; Buia, Maria-Cristina; Fine, Maoz; Banin, Ehud

    2013-02-01

    Ocean acidification, resulting from rising atmospheric carbon dioxide concentrations, is a pervasive stressor that can affect many marine organisms and their symbionts. Studies which examine the host physiology and microbial communities have shown a variety of responses to the ocean acidification process. Recently, several studies were conducted based on field experiments, which take place in natural CO(2) vents, exposing the host to natural environmental conditions of varying pH. This study examines the sea anemone Anemonia viridis which is found naturally along the pH gradient in Ischia, Italy, with an aim to characterize whether exposure to pH impacts the holobiont. The physiological parameters of A. viridis (Symbiodinium density, protein, and chlorophyll a+c concentration) and its microbial community were monitored. Although reduction in pH was seen to have had an impact on composition and diversity of associated microbial communities, no significant changes were observed in A. viridis physiology, and no microbial stress indicators (i.e., pathogens, antibacterial activity, etc.) were detected. In light of these results, it appears that elevated CO(2) does not have a negative influence on A. viridis that live naturally in the site. This suggests that natural long-term exposure and dynamic diverse microbial communities may contribute to the acclimation process of the host in a changing pH environment.

  5. Control in the Rate-Determining Step Provides a Promising Strategy To Develop New Catalysts for CO2 Hydrogenation: A Local Pair Natural Orbital Coupled Cluster Theory Study.

    PubMed

    Mondal, Bhaskar; Neese, Frank; Ye, Shengfa

    2015-08-03

    The development of efficient catalysts with base metals for CO2 hydrogenation has always been a major thrust of interest. A series of experimental and theoretical work has revealed that the catalytic cycle typically involves two key steps, namely, base-promoted heterolytic H2 splitting and hydride transfer to CO2, either of which can be the rate-determining step (RDS) of the entire reaction. To explore the determining factor for the nature of RDS, we present herein a comparative mechanistic investigation on CO2 hydrogenation mediated by [M(H)(η(2)-H2)(PP3(Ph))](n+) (M = Fe(II), Ru(II), and Co(III); PP3(Ph) = tris(2-(diphenylphosphino)phenyl)phosphine) type complexes. In order to construct reliable free energy profiles, we used highly correlated wave function based ab initio methods of the coupled cluster type alongside the standard density functional theory. Our calculations demonstrate that the hydricity of the metal-hydride intermediate generated by H2 splitting dictates the nature of the RDS for the Fe(II) and Co(III) systems, while the RDS for the Ru(II) catalyst appears to be ambiguous. CO2 hydrogenation catalyzed by the Fe(II) complex that possesses moderate hydricity traverses an H2-splitting RDS, whereas the RDS for the high-hydricity Co(III) species is found to be the hydride transfer. Thus, our findings suggest that hydricity can be used as a practical guide in future catalyst design. Enhancing the electron-accepting ability of low-hydricity catalysts is likely to improve their catalytic performance, while increasing the electron-donating ability of high-hydricity complexes may speed up CO2 conversion. Moreover, we also established the active roles of base NEt3 in directing the heterolytic H2 splitting and assisting product release through the formation of an acid-base complex.

  6. Natural heterogeneity and evolving geochemistry of Lower Tuscaloosa Formation brine in response to continuing CO2 injection at Cranfield EOR site, Mississippi, USA

    NASA Astrophysics Data System (ADS)

    Thordsen, J. J.; Kharaka, Y. K.; Thomas, B.; Abedini, A. A.; Conaway, C. H.; Manning, M. A.; Lu, J.

    2012-12-01

    Geochemical monitoring of Lower Tuscaloosa Formation (LTF) brine continues at the Cranfield CO2-enhanced oil recovery (EOR) and sequestration site to investigate the potential for the geologic storage of large volumes of CO2 in saline aquifers and depleted reservoirs. Cranfield oil field is a domal depleted oil and gas reservoir in the Mississippi Interior Salt Basin, with production in heterogeneous fluvial sandstones of the LTF (depth ~3000 m). CO2 flood began in July 2008. Brine samples were collected from selected production wells in March and December 2009, April 2010, and November 2011. Intensive sampling also was conducted for the first 18 days of a CO2 injection experiment below the oil-water contact (December 2009) at the Detailed Area of Study (DAS) 3-well array. The sampling objectives are to define the geochemical composition of the pre-injection brine, and to understand the geochemical changes resulting from interactions between the injected CO2, brine, and reservoir minerals. Results show that Tuscaloosa brine is Na-Ca-Cl type with total salinity ranging from ~140 to 160 g/L TDS (50 samples). Relatively large variations are observed in major divalent cations (Ca ~7,500-14,000 mg/L, Mg ~800-1,250 mg/L, Sr ~475-750 mg/L). Significant positive correlations are noted amongst Ca, Mg, Sr, Ba, and Br, whereas these solutes all trend negatively with Na and Cl. These results may be interpreted as possible binary mixing between two end-member waters: (1) high Na-Cl (51 and 97 g/L, respectively), low Ca, Mg, Sr, and Br (~7500, 800, 475, 280 mg/L, respectively); and (2) low Na-Cl (40 and 86 g/L), high Ca, Mg, Sr, and Br (~14,000, 1250, 750, 480 mg/L). This apparent binary mixing has no obvious correlation to CO2 injection, which suggests that observed variations are due to natural heterogeneities in LTF brine within the Cranfield dome. The variations may indicate vertical and/or lateral proximity to a halite source (i.e. salt dome), with the high Na-Cl, low Br

  7. Temperature effects on fish production across a natural thermal gradient.

    PubMed

    O'Gorman, Eoin J; Ólafsson, Ólafur P; Demars, Benoît O L; Friberg, Nikolai; Guðbergsson, Guðni; Hannesdóttir, Elísabet R; Jackson, Michelle C; Johansson, Liselotte S; McLaughlin, Órla B; Ólafsson, Jón S; Woodward, Guy; Gíslason, Gísli M

    2016-09-01

    Global warming is widely predicted to reduce the biomass production of top predators, or even result in species loss. Several exceptions to this expectation have been identified, however, and it is vital that we understand the underlying mechanisms if we are to improve our ability to predict future trends. Here, we used a natural warming experiment in Iceland and quantitative theoretical predictions to investigate the success of brown trout as top predators across a stream temperature gradient (4-25 °C). Brown trout are at the northern limit of their geographic distribution in this system, with ambient stream temperatures below their optimum for maximal growth, and above it in the warmest streams. A five-month mark-recapture study revealed that population abundance, biomass, growth rate, and production of trout all increased with stream temperature. We identified two mechanisms that contributed to these responses: (1) trout became more selective in their diet as stream temperature increased, feeding higher in the food web and increasing in trophic position; and (2) trophic transfer through the food web was more efficient in the warmer streams. We found little evidence to support a third potential mechanism: that external subsidies would play a more important role in the diet of trout with increasing stream temperature. Resource availability was also amplified through the trophic levels with warming, as predicted by metabolic theory in nutrient-replete systems. These results highlight circumstances in which top predators can thrive in warmer environments and contribute to our knowledge of warming impacts on natural communities and ecosystem functioning.

  8. The effects of CO2 on phytoplankton community structure in the Amazon River Plume

    NASA Astrophysics Data System (ADS)

    Chen, T. L.; Goes, J. I.; Gomes, H. R.; McKee, K. T.

    2013-12-01

    The Amazon River Plume results from an enormous discharge of freshwater and organic matter into the Atlantic Ocean. It is a unique environment with a natural pCO2 gradient in the surface waters of the plume that range from 130-950 μatm. The response of coastal marine phytoplankton to increased anthropogenic CO2 emission is still unknown, hence the Amazon River Plume gradient can serve as a natural laboratory to examine the potential influence of atmospheric CO2 increases and ocean acidification on phytoplankton community composition. A two pronged study was undertaken: the first in which shipboard samples from a 2010 cruise to the Amazon River Plume were analyzed to examine the distribution of 3 major phytoplankton groups (diatoms, diatom-diazotroph associations [DDAs], and the diazotroph Trichodesmium spp.) with respect to the natural pCO2 gradient; the second in which the growth response of Thalassiosira weisflogii, a representative diatom species, was examined under experimentally manipulated CO2 conditions. Cruise data analysis showed that diatoms were found with higher cell counts around 150 μatm; DDAs seemed to dominate waters within the narrow range of 350-400 μatm CO2; and the diazotroph Trichodesmium spp. grew in a wide range of pCO2 conditions, but with higher cell counts at upwards of 500 μatm. Phytoplankton group distributions along the CO2 gradient may be due to differences in their carbon-concentrating mechanism (CCMs) efficiencies. The CO2 manipulation apparatus was assembled such that the cells were grown under three different CO2 environments. Differential growth of T. weisflogii was observed at 150, 400, and 800 ppm CO2 treatment. T. weisflogii grew at all three CO2 concentrations, reflecting diatoms' physiological flexibility and efficient CCMs. Absorption spectra analysis of pigments and Fast Repetition Rate Fluorometer analysis indicate potential changes in photosynthetic machinery with different CO2 treatments. Future CO2 manipulation

  9. Intercomparing CO2 amounts from dispersion modeling, 1.6 μm differential absorption lidar and open path FTIR at a natural CO2 release at Caldara di Manziana, Italy

    NASA Astrophysics Data System (ADS)

    Queißer, M.; Granieri, D.; Burton, M.; La Spina, A.; Salerno, G.; Avino, R.; Fiorani, L.

    2015-04-01

    We intercompare results of three independent approaches to quantify a vented CO2 release at a strongly non-uniform CO2 Earth degassing at Caldara di Manziana, central Italy. An integrated path differential absorption lidar prototype and a commercial open path FTIR system were measuring column averaged CO2 concentrations in parallel at two different paths. An Eulerian gas dispersion model simulated 3-D CO2 concentration maps in the same area, using in situ CO2 flux input data acquired at 152 different points. Local processes the model does not account for, such as small-scale and short-lived wind eddies, govern CO2 concentrations in the instrument measurement paths. The model, on the other hand, also considers atmospheric effects that are out of the field of view of the instruments. Despite this we find satisfactory agreement between modeled and measured CO2 concentrations under certain meteorological conditions. Under these conditions the results suggest that an Eulerian dispersion model and optical remote sensing can be used as an integrated, complementary monitoring approach for CO2 hazard or leakage assessment. Furthermore, the modeling may assist in evaluating CO2 sensing surveys in the future. CO2 column amounts from differential absorption lidar are in line with those from FTIR for both paths with a mean residual of the time series of 44 and 34 ppm, respectively. This experiment is a fundamental step forward in the deployment of the differential absorption lidar prototype as a highly portable active remote sensing instrument probing vented CO2 emissions, including volcanoes.

  10. Large Amplitude Spatial and Temporal Gradients in Atmospheric Boundary Layer CO2 Mole Fractions Detected With a Tower-Based Network in the U.S. Upper Midwest

    SciTech Connect

    Miles, Natasha; Richardson, S. J.; Davis, Kenneth J.; Lauvaux, Thomas; Andrews, A.; West, Tristram O.; Bandaru, Varaprasad; Crosson, Eric R.

    2012-02-21

    This study presents observations of atmospheric CO{sub 2} mole fraction from a nine-tower, regional network deployed during the North American Carbon Program's Mid-Continent Intensive during 2007-2009. Within this network in a largely agricultural area, mean atmospheric CO{sub 2} gradients were strongly correlated with both ground-based inventory data and estimates from satellite remote sensing. The average seasonal drawdown for corn-dominated sites (35 ppm) is significantly larger than has been observed at other continental boundary layer sites. Observed growing-season median CO{sub 2} gradients are strongly dependent on local flux. The gradients between cross-vegetation site-pairs, for example, average 2.0 ppm/100 km, four times larger than the similar-vegetation site-pair average. Daily-timescale gradients are as large as 5.5 ppm/100 km, but dominated by advection rather than local flux. Flooding in 2008 led to a region-wide 23 week delay in growing-season minima. The observations show that regional-scale CO{sub 2} mole fraction networks yield large, coherent signals governed largely by regional sources and sinks of CO{sub 2}.

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

    NASA Astrophysics Data System (ADS)

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

    2017-05-01

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

  12. Microbial phosphorous mobilization strategies across a natural nutrient limitation gradient

    NASA Astrophysics Data System (ADS)

    Walker, R.; Wang, S.; Nico, P. S.; Fox, P. M.; Hao, Z.; Karaoz, U.; Torok, T.; Brodie, E.; Chakraborty, R.; Hao, Z.

    2016-12-01

    Phosphorus (P) is a critical nutrient and frequently limits primary productivity in terrestrial ecosystems. Microorganisms have evolved an array of strategies to mobilize occluded and insoluble P and may be important regulators of P availability to vegetation. Understanding the mechanisms of P mobilization, the breadth of microorganisms responsible, and the impact of these organisms on vegetation growth remains an important knowledge gap for both predicting ecosystem productivity and harnessing microbial functions to improve vegetation growth. To determine the relationship between soil development, phosphorus availability and P mobilizing microorganisms and their strategies we are studying a marine terrace chronosequence (Ecological Staircase, Mendocino County, CA) representing a fertility gradient culminating in P-limited pygmy forests that provide an ideal natural observatory to investigate how plant-microbe interactions co-evolve in response to P stress. Soil mineralogical analysis identified acidic soils bearing iron and aluminum phosphates and phytate as the dominant forms of occluded inorganic and organic P, respectively. Several diverse bacterial and fungal strains were isolated on media with AlPO4, FePO4, or phytate as the sole P source. Most microorganisms were able to utilize AlPO4 as a sole P source, with fewer subsisting on FePO4 or phytate. Terraces with a higher fraction of occluded and organic P harbored the greatest abundance of P-mobilizing microorganisms, with a significant proportion coming from the Burkholderia. Isolates that exhibited significant excess P mobilization were inoculated with Arabidopsis and Switchgrass plants grown with insoluble P forms had a positive impact on growth. These results indicate that rhizosphere microorganisms that have evolved under extreme nutrient limitation have an extended capacity for P solubilization, and could potentially be harnessed to alleviate P stress for plants. The detailed mechanisms for P

  13. Evaluation of Brine Migration Risks Due to CO2 Injection - an Integrated Natural and Social Science Modeling Approach

    NASA Astrophysics Data System (ADS)

    Noack, V.; Kissinger, A.; Class, H.; Knopf, S.; Konrad, W.; Scheer, D.

    2014-12-01

    Evaluation of possible risks for shallow groundwater systems caused by brine displacement due to CO2 injection requires an investigation of possible vertical pathways in regional-scale structural settings. The project CO2BRIM investigates this crucial issue in collaboration with external stakeholders to integrate expert feedback on migration scenarios. To evaluate possible brine displacement scenarios we construct a regional-scale 3D structural model based on data which represent a typical geological setting of the North German Basin. The model has a horizontal size of 39 km times 58 km and includes 11 geological layers from the Permian Zechstein salt up to the Quaternary. It comprises an anticlinal structure on top of a salt pillow and an elongated salt wall that dissect the overburden. For the risk scenarios we include discontinuities in the regionally important Rupelian aquitard (Tertiary) and a transition zone along the salt flank as such discontinuities are supposed to provide permeable pathways for brines which could reach shallow drinking water horizons. Based on this model we develop scenarios in which we vary for example hydro-geological parameters of the geological discontinuities, the injection rate and the initial state of the system in terms of the salinity distribution. Furthermore we compare different levels of model complexity with regard to the physical processes considered and their effects on our results. During the process of scenario development, external experts were invited to participate and share knowledge and concerns on both brine migration risks and possible migration paths and mechanisms. The results may help in site selection as they provide improved knowledge of pressure build-up in the reservoir and the overburden for such complex geological systems. Additionally, we want to identify the level of model complexity which is sufficient for this kind of setting with regard to the limited data availability at hand for the far field.

  14. Changes in coral microbial communities in response to a natural pH gradient

    PubMed Central

    Meron, Dalit; Rodolfo-Metalpa, Riccardo; Cunning, Ross; Baker, Andrew C; Fine, Maoz; Banin, Ehud

    2012-01-01

    Surface seawater pH is currently 0.1 units lower than pre-industrial values and is projected to decrease by up to 0.4 units by the end of the century. This acidification has the potential to cause significant perturbations to the physiology of ocean organisms, particularly those such as corals that build their skeletons/shells from calcium carbonate. Reduced ocean pH could also have an impact on the coral microbial community, and thus may affect coral physiology and health. Most of the studies to date have examined the impact of ocean acidification on corals and/or associated microbiota under controlled laboratory conditions. Here we report the first study that examines the changes in coral microbial communities in response to a natural pH gradient (mean pHT 7.3–8.1) caused by volcanic CO2 vents off Ischia, Gulf of Naples, Italy. Two Mediterranean coral species, Balanophyllia europaea and Cladocora caespitosa, were examined. The microbial community diversity and the physiological parameters of the endosymbiotic dinoflagellates (Symbiodinium spp.) were monitored. We found that pH did not have a significant impact on the composition of associated microbial communities in both coral species. In contrast to some earlier studies, we found that corals present at the lower pH sites exhibited only minor physiological changes and no microbial pathogens were detected. Together, these results provide new insights into the impact of ocean acidification on the coral holobiont. PMID:22437157

  15. Changes in coral microbial communities in response to a natural pH gradient.

    PubMed

    Meron, Dalit; Rodolfo-Metalpa, Riccardo; Cunning, Ross; Baker, Andrew C; Fine, Maoz; Banin, Ehud

    2012-09-01

    Surface seawater pH is currently 0.1 units lower than pre-industrial values and is projected to decrease by up to 0.4 units by the end of the century. This acidification has the potential to cause significant perturbations to the physiology of ocean organisms, particularly those such as corals that build their skeletons/shells from calcium carbonate. Reduced ocean pH could also have an impact on the coral microbial community, and thus may affect coral physiology and health. Most of the studies to date have examined the impact of ocean acidification on corals and/or associated microbiota under controlled laboratory conditions. Here we report the first study that examines the changes in coral microbial communities in response to a natural pH gradient (mean pH(T) 7.3-8.1) caused by volcanic CO(2) vents off Ischia, Gulf of Naples, Italy. Two Mediterranean coral species, Balanophyllia europaea and Cladocora caespitosa, were examined. The microbial community diversity and the physiological parameters of the endosymbiotic dinoflagellates (Symbiodinium spp.) were monitored. We found that pH did not have a significant impact on the composition of associated microbial communities in both coral species. In contrast to some earlier studies, we found that corals present at the lower pH sites exhibited only minor physiological changes and no microbial pathogens were detected. Together, these results provide new insights into the impact of ocean acidification on the coral holobiont.

  16. Development in a naturally acidified environment: Na+/H+-exchanger 3-based proton secretion leads to CO2 tolerance in cephalopod embryos

    PubMed Central

    2013-01-01

    Background Regulation of pH homeostasis is a central feature of all animals to cope with acid–base disturbances caused by respiratory CO2. Although a large body of knowledge is available for vertebrate and mammalian pH regulatory systems, the mechanisms of pH regulation in marine invertebrates remain largely unexplored. Results We used squid (Sepioteuthis lessoniana), which are known as powerful acid–base regulators to investigate the pH regulatory machinery with a special focus on proton secretion pathways during environmental hypercapnia. We cloned a Rhesus protein (slRhP), V-type H+-ATPase (slVHA) and the Na+/H+ exchanger 3 (slNHE3) from S. lessoniana, which are hypothesized to represent key players in proton secretion pathways among different animal taxa. Specifically designed antibodies for S. lessoniana demonstrated the sub-cellular localization of NKA, VHA (basolateral) and NHE3 (apical) in epidermal ionocytes of early life stages. Gene expression analyses demonstrated that slNHE3, slVHA and slRhP are up regulated in response to environmental hypercapnia (pH 7.31; 0.46 kPa pCO2) in body and yolk tissues compared to control conditions (pH 8.1; 0.045 kPa pCO2). This observation is supported by H+ selective electrode measurements, which detected increased proton gradients in CO2 treated embryos. This compensatory proton secretion is EIPA sensitive and thus confirms the central role of NHE based proton secretion in cephalopods. Conclusion The present work shows that in convergence to teleosts and mammalian pH regulatory systems, cephalopod early life stages have evolved a unique acid–base regulatory machinery located in epidermal ionocytes. Using cephalopod molluscs as an invertebrate model this work provides important insights regarding the unifying evolutionary principles of pH regulation in different animal taxa that enables them to cope with CO2 induced acid–base disturbances. PMID:23988184

  17. A flow injection analyser conductometric coupled system for the field analysis of free dissolved CO2 and total dissolved inorganic carbon in natural waters.

    PubMed

    Martinotti, Valter; Balordi, Marcella; Ciceri, Giovanni

    2012-05-01

    A flow injection analyser coupled with a gas diffusion membrane and a conductometric microdetector was adapted for the field analysis of natural concentrations of free dissolved CO2 and dissolved inorganic carbon in natural waters and used in a number of field campaigns for marine water monitoring. The dissolved gaseous CO2 presents naturally, or that generated by acidification of the sample, is separated by diffusion using a hydrophobic semipermeable gas porous membrane, and the permeating gas is incorporated into a stream of deionised water and measured by means of an electrical conductometric microdetector. In order to make the system suitable and easy to use for in-field measurements aboard oceanographic ships, the single components of the analyser were compacted into a robust and easy to use system. The calibration of the system is carried out by using standard solutions of potassium bicarbonate at two concentration ranges. Calibration and sample measurements are carried out inside a temperature-constant chamber at 25 °C and in an inert atmosphere (N2). The detection and quantification limits of the method, evaluated as 3 and 10 times the standard deviation of a series of measurements of the matrix solution were 2.9 and 9.6 μmol/kg of CO2, respectively. Data quality for dissolved inorganic carbon was checked with replicate measurements of a certified reference material (A. Dickson, Scripps Institution of Oceanography, University of California, San Diego), both accuracy and repeatability were -3.3% and 10%, respectively. Optimization, performance qualification of the system and its application in various natural water samples are reported and discussed. In the future, the calibration step will be operated automatically in order to improve the analytical performance and the applicability will be increased in the course of experimental surveys carried out both in marine and freshwater ecosystems. Considering the present stage of development of the method, it

  18. Improving generalization performance of natural gradient learning using optimized regularization by NIC.

    PubMed

    Park, Hyeyoung; Murata, Noboru; Amari, Shun-Ichi

    2004-02-01

    Natural gradient learning is known to be efficient in escaping plateau, which is a main cause of the slow learning speed of neural networks. The adaptive natural gradient learning method for practical implementation also has been developed, and its advantage in real-world problems has been confirmed. In this letter, we deal with the generalization performances of the natural gradient method. Since natural gradient learning makes parameters fit to training data quickly,the overfitting phenomenon may easily occur, which results in poor generalization performance. To solve the problem, we introduce the regularization term in natural gradient learning and propose an efficient optimizing method for the scale of regularization by using a generalized Akaike information criterion (network information criterion). We discuss the properties of the optimized regularization strength by NIC through theoretical analysis as well as computer simulations. We confirm the computational efficiency and generalization performance of the proposed method in real-world applications through computational experiments on benchmark problems.

  19. Comparison of Pore-Network and Lattice Boltzmann Models for Pore-Scale Modeling of Geological Storage of CO2 in Natural Reservoir Rocks

    NASA Astrophysics Data System (ADS)

    Kohanpur, A. H.; Chen, Y.; Valocchi, A. J.; Tudek, J.; Crandall, D.

    2016-12-01

    CO2-brine flow in deep natural rocks is the focus of attention in geological storage of CO2. Understanding rock/flow properties at pore-scale is a vital component in field-scale modeling and prediction of fate of injected CO2. There are many challenges in working at the pore scale, such as size and selection of representative elementary volume (REV), particularly for material with complex geometry and heterogeneity, and the high computational costs. These issues factor into trade-offs that need to be made in choosing and applying pore-scale models. On one hand, pore-network modeling (PNM) simplifies the geometry and flow equations but can provide characteristic curves on fairly large samples. On the other hand, the lattice Boltzmann method (LBM) solves Navier-Stokes equations on the real geometry but is limited to small samples due to its high computational costs. Thus, both methods have some advantages but also face some challenges, which warrants a more detailed comparison and evaluation. In this study, we used industrial and micro-CT scans of actual reservoir rock samples to characterize pore structure at different resolutions. We ran LBM models directly on the characterized geometry and PNM on the equivalent 3D extracted network to determine single/two-phase flow properties during drainage and imbibition processes. Specifically, connectivity, absolute permeability, relative permeability curve, capillary pressure curve, and interface location are compared between models. We also did simulations on several subsamples from different locations including different domain sizes and orientations to encompass analysis of heterogeneity and isotropy. This work is primarily supported as part of the Center for Geologic Storage of CO2, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science and partially supported by the International Institute for Carbon-Neutral Energy Research (WPI-I2CNER) based at Kyushu University, Japan.

  20. Natural bog pine ecosystem in southern Germany is a steady and robust sink of CO2 but a minor source of CH4

    NASA Astrophysics Data System (ADS)

    Hommeltenberg, Janina; Schmid, Hans Peter; Droesler, Matthias; Werle, Peter

    2013-04-01

    Natural peatland ecosystems sequester carbon dioxide. They do this slowly but steadily, but also emit methane in small rates. Thus peatlands have both positive and negative greenhouse gas balance impacts on the climate system due to their influence on atmospheric CO2 and CH4 concentration. We present data of net ecosystem CO2 exchange (NEE) of almost three years (July 2010 to March 2013) and of methane fluxes over a period of nine months (July 2012 to March 2013), measured by eddy covariance technique in the bog forest "Schechenfilz". The site (47°48' N; 11°19' E, 590 m a.s.l.) is an ICOS-ecosystems associate site, located in the pre-alpine region of southern Germany, where a natural Pinus mugo rotundata forest grows on an undisturbed, almost 6 m thick peat layer. The slow growing bog pines and their low rates of carbon sequestration, in combination with high water table and thus low availability of oxygen, lead to low carbon dioxide fluxes. Photosynthesis as well as soil respiration are considerably attenuated compared to upland sites. Additionally, the high soil water content is damping the impact of dry and hot periods on CO2 exchange. Thus the CO2 balance is very robust to changing environmental parameters. While the CO2 exchange is clearly related to soil temperature and photosynthetic active radiation, we have not yet identified a parameter that governs variations in methane exchange. Various environmental parameters appear to be related to methane emissions (including soil moisture, soil and air temperature and wind direction), but the scatter with respect to half hourly methane fluxes is too large to be useful for gap modeling. Analysis of daily averages reduces the scatter, but since methane exchange exhibits considerable daily variation, daily averages are not useful to fill data gaps of half hourly fluxes. In consequence, as the daily course is the summary result of all environmental parameters having influence on the methane exchange at the half

  1. Natural variations in snow cover do not affect the annual soil CO2 efflux from a mid-elevation temperate forest

    PubMed Central

    Schindlbacher, Andreas; Jandl, Robert; Schindlbacher, Sabine

    2014-01-01

    Climate change might alter annual snowfall patterns and modify the duration and magnitude of snow cover in temperate regions with resultant impacts on soil microclimate and soil CO2 efflux (Fsoil). We used a 5-year time series of Fsoil measurements from a mid-elevation forest to assess the effects of naturally changing snow cover. Snow cover varied considerably in duration (105–154 days) and depth (mean snow depth 19–59 cm). Periodically shallow snow cover (<10 cm) caused soil freezing or increased variation in soil temperature. This was mostly not reflected in Fsoil which tended to decrease gradually throughout winter. Progressively decreasing C substrate availability (identified by substrate induced respiration) likely over-rid the effects of slowly changing soil temperatures and determined the overall course of Fsoil. Cumulative CO2 efflux from beneath snow cover varied between 0.46 and 0.95 t C ha−1 yr−1 and amounted to between 6 and 12% of the annual efflux. When compared over a fixed interval (the longest period of snow cover during the 5 years), the cumulative CO2 efflux ranged between 0.77 and 1.18 t C ha−1 or between 11 and 15% of the annual soil CO2 efflux. The relative contribution (15%) was highest during the year with the shortest winter. Variations in snow cover were not reflected in the annual CO2 efflux (7.44–8.41 t C ha−1) which did not differ significantly between years and did not correlate with any snow parameter. Regional climate at our site was characterized by relatively high amounts of precipitation. Therefore, snow did not play a role in terms of water supply during the warm season and primarily affected cold season processes. The role of changing snow cover therefore seems rather marginal when compared to potential climate change effects on Fsoil during the warm season. PMID:23966344

  2. Natural variations in snow cover do not affect the annual soil CO2 efflux from a mid-elevation temperate forest.

    PubMed

    Schindlbacher, Andreas; Jandl, Robert; Schindlbacher, Sabine

    2014-02-01

    Climate change might alter annual snowfall patterns and modify the duration and magnitude of snow cover in temperate regions with resultant impacts on soil microclimate and soil CO2 efflux (Fsoil ). We used a 5-year time series of Fsoil measurements from a mid-elevation forest to assess the effects of naturally changing snow cover. Snow cover varied considerably in duration (105-154 days) and depth (mean snow depth 19-59 cm). Periodically shallow snow cover (<10 cm) caused soil freezing or increased variation in soil temperature. This was mostly not reflected in Fsoil which tended to decrease gradually throughout winter. Progressively decreasing C substrate availability (identified by substrate induced respiration) likely over-rid the effects of slowly changing soil temperatures and determined the overall course of Fsoil . Cumulative CO2 efflux from beneath snow cover varied between 0.46 and 0.95 t C ha(-1)  yr(-1) and amounted to between 6 and 12% of the annual efflux. When compared over a fixed interval (the longest period of snow cover during the 5 years), the cumulative CO2 efflux ranged between 0.77 and 1.18 t C ha(-1) or between 11 and 15% of the annual soil CO2 efflux. The relative contribution (15%) was highest during the year with the shortest winter. Variations in snow cover were not reflected in the annual CO2 efflux (7.44-8.41 t C ha(-1) ) which did not differ significantly between years and did not correlate with any snow parameter. Regional climate at our site was characterized by relatively high amounts of precipitation. Therefore, snow did not play a role in terms of water supply during the warm season and primarily affected cold season processes. The role of changing snow cover therefore seems rather marginal when compared to potential climate change effects on Fsoil during the warm season.

  3. Local Adaptation to Soil Hypoxia Determines the Structure of an Arbuscular Mycorrhizal Fungal Community in Roots from Natural CO2 Springs ▿ †

    PubMed Central

    Maček, Irena; Dumbrell, Alex J.; Nelson, Michaela; Fitter, Alastair H.; Vodnik, Dominik; Helgason, Thorunn

    2011-01-01

    The processes responsible for producing and maintaining the diversity of natural arbuscular mycorrhizal (AM) fungal communities remain largely unknown. We used natural CO2 springs (mofettes), which create hypoxic soil environments, to determine whether a long-term, directional, abiotic selection pressure could change AM fungal community structure and drive the selection of particular AM fungal phylotypes. We explored whether those phylotypes that appear exclusively in hypoxic soils are local specialists or widespread generalists able to tolerate a range of soil conditions. AM fungal community composition was characterized by cloning, restriction fragment length polymorphism typing, and the sequencing of small subunit rRNA genes from roots of four plant species growing at high (hypoxic) and low (control) geological CO2 exposure. We found significant levels of AM fungal community turnover (β diversity) between soil types and the numerical dominance of two AM fungal phylotypes in hypoxic soils. Our results strongly suggest that direct environmental selection acting on AM fungi is a major factor regulating AM fungal communities and their phylogeographic patterns. Consequently, some AM fungi are more strongly associated with local variations in the soil environment than with their host plant's distribution. PMID:21622777

  4. Natural and industrial analogues for release of CO2 from storagereservoirs: Identification of features, events, and processes and lessonslearned

    SciTech Connect

    Lewicki, Jennifer L.; Birkholzer, Jens; Tsang, Chin-Fu

    2006-03-03

    The injection and storage of anthropogenic CO{sub 2} in deep geologic formations is a potentially feasible strategy to reduce CO{sub 2} emissions and atmospheric concentrations. While the purpose of geologic carbon storage is to trap CO{sub 2} underground, CO{sub 2} could migrate away from the storage site into the shallow subsurface and atmosphere if permeable pathways such as well bores or faults are present. Large-magnitude releases of CO{sub 2} have occurred naturally from geologic reservoirs in numerous volcanic, geothermal, and sedimentary basin settings. Carbon dioxide and natural gas have also been released from geologic CO{sub 2} reservoirs and natural gas storage facilities, respectively, due to influences such as well defects and injection/withdrawal processes. These systems serve as natural and industrial analogues for the potential release of CO{sub 2} from geologic storage reservoirs and provide important information about the key features, events, and processes (FEPs) that are associated with releases, as well as the health, safety, and environmental consequences of releases and mitigation efforts that can be applied. We describe a range of natural releases of CO{sub 2} and industrial releases of CO{sub 2} and natural gas in the context of these characteristics. Based on this analysis, several key conclusions can be drawn, and lessons can be learned for geologic carbon storage. First, CO{sub 2} can both accumulate beneath, and be released from, primary and secondary reservoirs with capping units located at a wide range of depths. Both primary and secondary reservoir entrapments for CO{sub 2} should therefore be well characterized at storage sites. Second, many natural releases of CO{sub 2} have been correlated with a specific event that triggered the release, such as magmatic fluid intrusion or seismic activity. The potential for processes that could cause geomechanical damage to sealing cap rocks and trigger the release of CO{sub 2} from a storage

  5. Natural variability of CO2 and O2 fluxes: What can we learn from centuries-long climate models simulations?

    NASA Astrophysics Data System (ADS)

    Resplandy, L.; Séférian, R.; Bopp, L.

    2015-01-01

    carbon uptake and oxygen content estimates over the past decades suggest that the anthropogenic carbon sink has changed and that the oxygen concentration in the ocean interior has decreased. Although these detected changes appear consistent with those expected from anthropogenic forced climate change, large uncertainties remain in the contribution of natural variability. Using century-long simulations (500-1000 years) of unforced natural variability from six Earth System Models (ESMs), we examine the internally driven natural variability of carbon and oxygen fluxes from interannual to multidecadal time scales. The intensity of natural variability differs between the ESMs, in particular, decadal variability locally accounts for 10-50% of the total variance. Although the variability is higher in all regions with strong climate modes (North Atlantic, North Pacific, etc.), we find that only the Southern Ocean and the tropical Pacific significantly modulate the global fluxes. On (multi)decadal time scales, deep convective events along the Antarctic shelf drive the global fluxes variability by transporting deep carbon-rich/oxygen-depleted waters to the surface and by reducing the sea-ice coverage. On interannual time scales, the global flux is modulated by (1) variations of the upwelling of circumpolar deep waters associated with the southern annular mode in the subpolar Southern Ocean and (2) variations of the equatorial/costal upwelling combined with changes in the solubility-driven fluxes in response to El Niño Southern Oscillation (ENSO) in the tropical Pacific. We discuss the challenges of measuring and detecting long-term trends from a few decade-long records influenced by internal variability.

  6. CO2-Neutral Fuels

    NASA Astrophysics Data System (ADS)

    Goede, Adelbert; van de Sanden, Richard

    2016-06-01

    Mimicking the biogeochemical cycle of System Earth, synthetic hydrocarbon fuels are produced from recycled CO2 and H2O powered by renewable energy. Recapturing CO2 after use closes the carbon cycle, rendering the fuel cycle CO2 neutral. Non-equilibrium molecular CO2 vibrations are key to high energy efficiency.

  7. In situ developmental responses of tropical sea urchin larvae to ocean acidification conditions at naturally elevated pCO2 vent sites.

    PubMed

    Lamare, Miles D; Liddy, Michelle; Uthicke, Sven

    2016-11-30

    Laboratory experiments suggest that calcifying developmental stages of marine invertebrates may be the most ocean acidification (OA)-sensitive life-history stage and represent a life-history bottleneck. To better extrapolate laboratory findings to future OA conditions, developmental responses in sea urchin embryos/larvae were compared under ecologically relevant in situ exposures on vent-elevated pCO2 and ambient pCO2 coral reefs in Papua New Guinea. Echinometra embryos/larvae were reared in meshed chambers moored in arrays on either venting reefs or adjacent non-vent reefs. After 24 and 48 h, larval development and morphology were quantified. Compared with controls (mean pH(T) = 7.89-7.92), larvae developing in elevated pCO2 vent conditions (pH(T) = 7.50-7.72) displayed a significant reduction in size and increased abnormality, with a significant correlation of seawater pH with both larval size and larval asymmetry across all experiments. Reciprocal transplants (embryos from vent adults transplanted to control conditions, and vice versa) were also undertaken to identify if adult acclimatization can translate resilience to offspring (i.e. transgenerational processes). Embryos originating from vent adults were, however, no more tolerant to reduced pH. Sea temperature and chlorophyll-a concentrations (i.e. larval nutrition) did not contribute to difference in larval size, but abnormality was correlated with chlorophyll levels. This study is the first to examine the response of marine larvae to OA scenarios in the natural environment where, importantly, we found that stunted and abnormal development observed in situ are consistent with laboratory observations reported in sea urchins, in both the direction and magnitude of the response. © 2016 The Author(s).

  8. Nature-Inspired, Highly Durable CO2 Reduction System Consisting of a Binuclear Ruthenium(II) Complex and an Organic Semiconductor Using Visible Light.

    PubMed

    Kuriki, Ryo; Matsunaga, Hironori; Nakashima, Takuya; Wada, Keisuke; Yamakata, Akira; Ishitani, Osamu; Maeda, Kazuhiko

    2016-04-20

    A metal-free organic semiconductor of mesoporous graphitic carbon nitride (C3N4) coupled with a Ru(II) binuclear complex (RuRu') containing photosensitizer and catalytic units selectively reduced CO2 into HCOOH under visible light (λ > 400 nm) in the presence of a suitable electron donor with high durability, even in aqueous solution. Modification of C3N4 with Ag nanoparticles resulted in a RuRu'/Ag/C3N4 photocatalyst that exhibited a very high turnover number (>33000 with respect to the amount of RuRu'), while maintaining high selectivity for HCOOH production (87-99%). This turnover number was 30 times greater than that reported previously using C3N4 modified with a mononuclear Ru(II) complex, and by far the highest among the metal-complex/semiconductor hybrid systems reported to date. The results of photocatalytic reactions, emission decay measurements, and time-resolved infrared spectroscopy indicated that Ag nanoparticles on C3N4 collected electrons having lifetimes of several milliseconds from the conduction band of C3N4, which were transferred to the excited state of RuRu', thereby promoting photocatalytic CO2 reduction driven by two-step photoexcitation of C3N4 and RuRu'. This study also revealed that the RuRu'/Ag/C3N4 hybrid photocatalyst worked efficiently in water containing a proper electron donor, despite the intrinsic hydrophobic nature of C3N4 and low solubility of CO2 in an aqueous environment.

  9. Upgraded biogas from municipal solid waste for natural gas substitution and CO2 reduction--a case study of Austria, Italy, and Spain.

    PubMed

    Starr, Katherine; Villalba, Gara; Gabarrell, Xavier

    2015-04-01

    Biogas is rich in methane and can be further purified through biogas upgrading technologies, presenting a viable alternative to natural gas. Landfills and anaerobic digestors treating municipal solid waste are a large source of such biogas. They therefore offer an attractive opportunity to tap into this potential source of natural gas while at the same time minimizing the global warming impact resulting from methane emissions in waste management schemes (WMS) and fossil fuel consumption reduction. This study looks at the current municipal solid waste flows of Spain, Italy, and Austria over one year (2009), in order to determine how much biogas is generated. Then it examines how much natural gas could be substituted by using four different biogas upgrading technologies. Based on current waste generation rates, exploratory but realistic WMS were created for each country in order to maximize biogas production and potential for natural gas substitution. It was found that the potential substitution of natural gas by biogas resulting from the current WMS seems rather insignificant: 0.2% for Austria, 0.6% for Italy and 0.3% for Spain. However, if the WMS is redesigned to maximize biogas production, these figures can increase to 0.7% for Austria, 1% for Italy and 2% for Spain. Furthermore, the potential CO2 reduction as a consequence of capturing the biogas and replacing fossil fuel can result in up to a 93% reduction of the annual national waste greenhouse gas emissions of Spain and Italy. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Large Releases from CO2 Storage Reservoirs: A Discussion ofNatural Analogs, FEPS, and Modeling Needs

    SciTech Connect

    Birkholzer, J.; Pruess, K.; Lewicki, J.L.; Rutqvist, J.; Tsang,C-F.; Karimjee, A.

    2005-11-01

    While the purpose of geologic storage in deep saline formations is to trap greenhouse gases underground, the potential exists for CO{sub 2} to escape from the target reservoir, migrate upward along permeable pathways, and discharge at the land surface. In this paper, we evaluate the potential for such CO{sub 2} discharges based on the analysis of natural analogs, where large releases of gas have been observed. We are particularly interested in circumstances that could generate sudden, possibly self-enhancing release events. The probability for such events may be low, but the circumstances under which they occur and the potential consequences need to be evaluated in order to design appropriate site-selection and risk-management strategies. Numerical modeling of hypothetical test cases is suggested to determine critical conditions for large CO{sub 2} releases, to evaluate whether such conditions may be possible at designated storage sites, and, if applicable, to evaluate the potential impacts of such events as well as design appropriate mitigation strategies.

  11. Critical Considerations for Accurate Soil CO2 Flux Measurement

    NASA Astrophysics Data System (ADS)

    Xu, L.; Furtaw, M.; Madsen, R.; Welles, J.; Demetriades-Shah, T.; Anderson, D.; Garcia, R.; McDermitt, D.

    2005-12-01

    Soil respiration is a significant component of the carbon balance for an ecosystem, but the environmental (soil moisture, rain event, temperature etc.) and biological (photosynthesis, LAI etc.) factors that contribute to soil respiration remain poorly understood. This limits our ability to understand the carbon budget at the ecosystem level making it difficult to predict the impacts of climate change. Two important reasons for this poor understanding have been the difficulty in making accurate soil respiration measurements and the lack of continuous and long-term soil respiration data at sufficiently fine temporal and spatial scales. To meet these needs, we have developed a new automated multiplexing system, the LI-8100M, for obtaining reliable soil CO2 flux data at high spatial and temporal resolution. The system has the capability to continuously measure the soil CO2 flux at up to 16 locations. Soil CO2 flux is driven primarily by the CO2 diffusion gradient across the soil surface. Ideally, the flux measurement should be made without affecting the diffusion gradient and without having any chamber-induced pressure perturbation. In a closed-chamber system the slope of dCO2/dt is required to compute the flux. To obtain the slope of dCO2/dt, the chamber CO2 concentration must be allowed to rise. Consequently, soil CO2 flux will be affected because of the decreased CO2 diffusion gradient. To minimize the impact of decreased CO2 diffusion gradient on CO2 flux measurement in LI-8100M, the chamber CO2 concentration versus time is fitted with an exponential function. Soil CO2 flux is then estimated by calculating the initial slope from the exponential function at time zero when the chamber touches the soil, and that is when the chamber CO2 concentration is equal to the ambient. Our results show that the flux estimated from a linear function, the widely used method, could underestimate CO2 flux by more than 10% as compared with that from the exponential function. An

  12. Estimation of continuous anthropogenic CO2 using CO2, CO, δ13C(CO2) and Δ14C(CO2)

    NASA Astrophysics Data System (ADS)

    Vardag, S. N.; Gerbig, C.; Janssens-Maenhout, G.; Levin, I.

    2015-07-01

    We investigate different methods for estimating anthropogenic CO2 using modelled continuous atmospheric concentrations of CO2 alone, as well as CO2 in combination with the surrogate tracers CO, δ13C(CO2) and Δ14C(CO2). These methods are applied at three hypothetical stations representing rural, urban and polluted conditions. We find that independent of the tracer used, an observation-based estimate of continuous anthropogenic CO2 is not feasible at rural measurement sites due to the low signal to noise ratio of anthropogenic CO2 estimates at such settings. At urban and polluted sites, potential future continuous Δ14C(CO2) measurements with a precision of 5 ‰ or better are most promising for anthropogenic CO2 determination (precision ca. 10-20%), but the insensitivity against CO2 contributions from biofuel emissions may reduce its accuracy in the future. Other tracers, such as δ13C(CO2) and CO could provide an accurate and already available alternative if all CO2 sources in the catchment area are well characterized with respect to their isotopic signature and CO to anthropogenic CO2 ratio. We suggest a strategy for calibrating these source characteristics on an annual basis using precise Δ14C(CO2) measurements on grab samples. The precision of anthropogenic CO2 determination using δ13C(CO2) is largely determined by the measurement precision of δ13C(CO2) and CO2. The precision when using the CO-method is mainly limited by the variation of natural CO sources and CO sinks. At present, continuous anthropogenic CO2 could be determined using the tracers δ13C(CO2) and/or CO with a precision of about 30 %, a mean bias of about 10 % and without significant diurnal discrepancies. This allows significant improvement, validation and bias reduction of highly resolved emission inventories using atmospheric observation and regional modelling.

  13. Interhemispheric gradient of atmospheric radiocarbon reveals natural variability of Southern Ocean winds

    NASA Astrophysics Data System (ADS)

    Rodgers, K. B.; Fletcher, S. E. M.; Bianchi, D.; Beaulieu, C.; Galbraith, E. D.; Gnanadesikan, A.; Hogg, A. G.; Iudicone, D.; Lintner, B.; Naegler, T.; Reimer, P. J.; Sarmiento, J. L.; Slater, R. D.

    2011-01-01

    Tree ring Δ14C data (Reimer et al., 2004; McCormac et al., 2004) indicate that atmospheric Δ14C varied on multi-decadal to centennial timescales, in both hemispheres, over the pre-industrial period AD 950-1830. Although the Northern and Southern Hemispheric Δ14C records display similar variability, it is difficult from these data alone to distinguish between variations driven by 14CO2 production in the upper atmosphere (Stuiver, 1980) and exchanges between carbon reservoirs (Siegenthaler, 1980). Here we consider rather the Interhemispheric Gradient in atmospheric Δ14C as revealing of the background pre-bomb air-sea Disequilbrium Flux between 14CO2 and CO2. As the global maximum of the Disequilibrium Flux is squarely centered in the open ocean regions of the Southern Ocean, relatively modest perturbations to the winds over this region drive significant perturbations to the Interhemispheric Gradient. The analysis presented here implies that changes to Southern Ocean windspeeds are likely a main driver of the observed variability in the Interhemispheric Gradient over 950-1830, and further, that this variability may be larger than the Southern Ocean wind trends that have been reported for recent decades (notably 1980-2004). This interpretation also implies a significant weakening of the winds over the Southern Ocean within a few decades of AD 1375, associated with the transition between the Medieval Climate Anomaly and the Little Ice Age. The driving forces that could have produced such a shift in the winds remain unkown.

  14. CO2 -Responsive polymers.

    PubMed

    Lin, Shaojian; Theato, Patrick

    2013-07-25

    This Review focuses on the recent progress in the area of CO2 -responsive polymers and provides detailed descriptions of these existing examples. CO2 -responsive polymers can be categorized into three types based on their CO2 -responsive groups: amidine, amine, and carboxyl groups. Compared with traditional temperature, pH, or light stimuli-responsive polymers, CO2 -responsive polymers provide the advantage to use CO2 as a "green" trigger as well as to capture CO2 directly from air. In addition, the current challenges of CO2 -responsive polymers are discussed and the different solution methods are compared. Noteworthy, CO2 -responsive polymers are considered to have a prosperous future in various scientific areas.

  15. CO2 pulses

    NASA Astrophysics Data System (ADS)

    Bell, Peter M.

    Studies of the sources and the increases of carbon dioxide in the atmosphere have been both frustrating and alarming; frustrating because so little is known and alarming because the potential consequences could be so grave (Eos, November 15, 1983, p. 929). The nature of the complexities have recently been focused upon by studies of the carbon cycle at the earth's surface and its influence on the atmosphere. It turns out that most of the increases of atmospheric carbon dioxide are from two sources: (1) petroleum and coal use and (2) the clearing of major forested lands.It is generally acknowledged that fossil fuel use has declined sharply during the past several years and that the deforestation of large areas under development will end. A recent review of current thinking on the effects of global deforestation by G.M. Woodwell and others stated that, “appropriate action taken now might reduce or eliminate the problem. Stabilization of the rate of combustion of fossil fuels combined with a program of reforestation would contribute toward stabilizing the CO2 content of the atmosphere … we need not accept as inexorable a global warming due to the accumulation of CO2 in the atmosphere” (Science, 222, 1081-1086, 1983).

  16. CO2 laser modeling

    NASA Technical Reports Server (NTRS)

    Johnson, Barry

    1992-01-01

    The topics covered include the following: (1) CO2 laser kinetics modeling; (2) gas lifetimes in pulsed CO2 lasers; (3) frequency chirp and laser pulse spectral analysis; (4) LAWS A' Design Study; and (5) discharge circuit components for LAWS. The appendices include LAWS Memos, computer modeling of pulsed CO2 lasers for lidar applications, discharge circuit considerations for pulsed CO2 lidars, and presentation made at the Code RC Review.

  17. Sequestration of CO2 by halotolerant algae

    PubMed Central

    2014-01-01

    The potential of halotolerant algae isolated from natural resources was used to study CO2 fixation and algal lipid production. Biological fixation of CO2 in photobioreactor in presence of salinity is exploited. The CO2 concentration 1060 ppm gave the highest biomass yield (700 mg dry wt/l), the highest total lipid content (10.33%) with 80% of CO2 removal. PMID:24847439

  18. Method for tracing simulated CO2 leak in terrestrial environment with a 13CO2 tracer

    NASA Astrophysics Data System (ADS)

    Moni, Christophe; Rasse, Daniel

    2013-04-01

    Facilities for the geological storage of carbon dioxide (CO2) as part of carbon capture and storage (CCS) schemes will be designed to prevent any leakage from the defined 'storage complex'. However, developing regulations and guidance throughout the world (e.g. the EC Directive and the USEPA Vulnerability Evaluation Framework) recognize the importance of assessing the potential for environmental impacts from CO2 storage. RISCS, a European (FP7) project, aims to improve understanding of those impacts that could plausibly occur in the hypothetical case that unexpected leakage occurs. As part of the RISCS project the potential impacts that an unexpected CO2 leaks might have on a cropland ecosystems was investigated. A CO2 exposure field experiment based on CO2 injection at 85 cm depth under an oats culture was designed. To facilitate the characterization of the simulated leaking zone the gas used for injection was produced from natural gas and had a δ13C of -46‰. The aim of the present communication is to depict how the injected gas was traced within the soil-vegetation-atmosphere continuum using 13CO2 continuous cavity ring-down spectrometry (CRDS). Four subsurface experimental injection plots (6m x 3m) were set up. In order to test the effects of different intensity of leakage, the field experiment was designed as to create a longitudinal CO2 gradient for each plot. For this purpose gas supply pipes were inserted at one extremity of each plot at the base of a 45 cm thick layer of sand buried 40 cm below the surface under the clayey plough layer of Norwegian moraine soils. Soil CO2 concentration and isotopic signature were punctually recorded: 1) in the soil at 20 cm depth at 6 positions distributed on the central transect, 2) at the surface following a (50x50 cm) grid sampling pattern, and 3) in the canopy atmosphere at 10, 20, 30 cm along three longitudinal transects (seven sampling point per transect). Soil CO2 fluxes and isotopic signature were finally

  19. Forest succession at elevated CO2

    SciTech Connect

    Clark, James S.; Schlesinger, William H.

    2002-02-01

    We tested hypotheses concerning the response of forest succession to elevated CO2 in the FACTS-1 site at the Duke Forest. We quantified growth and survival of naturally recruited seedlings, tree saplings, vines, and shrubs under ambient and elevated CO2. We planted seeds and seedlings to augment sample sites. We augmented CO2 treatments with estimates of shade tolerance and nutrient limitation while controlling for soil and light effects to place CO2 treatments within the context of natural variability at the site. Results are now being analyzed and used to parameterize forest models of CO2 response.

  20. Imprints of natural selection along environmental gradients in phenology-related genes of Quercus petraea.

    PubMed

    Alberto, Florian J; Derory, Jérémy; Boury, Christophe; Frigerio, Jean-Marc; Zimmermann, Niklaus E; Kremer, Antoine

    2013-10-01

    We explored single nucleotide polymorphism (SNP) variation in candidate genes for bud burst from Quercus petraea populations sampled along gradients of latitude and altitude in Western Europe. SNP diversity was monitored for 106 candidate genes, in 758 individuals from 32 natural populations. We investigated whether SNP variation reflected the clinal pattern of bud burst observed in common garden experiments. We used different methods to detect imprints of natural selection (FST outlier, clinal variation at allelic frequencies, association tests) and compared the results obtained for the two gradients. FST outlier SNPs were found in 15 genes, 5 of which were common to both gradients. The type of selection differed between the two gradients (directional or balancing) for 3 of these 5. Clinal variations were observed for six SNPs, and one cline was conserved across both gradients. Association tests between the phenotypic or breeding values of trees and SNP genotypes identified 14 significant associations, involving 12 genes. The results of outlier detection on the basis of population differentiation or clinal variation were not very consistent with the results of association tests. The discrepancies between these approaches may reflect the different hierarchical levels of selection considered (inter- and intrapopulation selection). Finally, we obtained evidence for convergent selection (similar for gradients) and clinal variation for a few genes, suggesting that comparisons between parallel gradients could be used to screen for major candidate genes responding to natural selection in trees.

  1. Imprints of Natural Selection Along Environmental Gradients in Phenology-Related Genes of Quercus petraea

    PubMed Central

    Alberto, Florian J.; Derory, Jérémy; Boury, Christophe; Frigerio, Jean-Marc; Zimmermann, Niklaus E.; Kremer, Antoine

    2013-01-01

    We explored single nucleotide polymorphism (SNP) variation in candidate genes for bud burst from Quercus petraea populations sampled along gradients of latitude and altitude in Western Europe. SNP diversity was monitored for 106 candidate genes, in 758 individuals from 32 natural populations. We investigated whether SNP variation reflected the clinal pattern of bud burst observed in common garden experiments. We used different methods to detect imprints of natural selection (FST outlier, clinal variation at allelic frequencies, association tests) and compared the results obtained for the two gradients. FST outlier SNPs were found in 15 genes, 5 of which were common to both gradients. The type of selection differed between the two gradients (directional or balancing) for 3 of these 5. Clinal variations were observed for six SNPs, and one cline was conserved across both gradients. Association tests between the phenotypic or breeding values of trees and SNP genotypes identified 14 significant associations, involving 12 genes. The results of outlier detection on the basis of population differentiation or clinal variation were not very consistent with the results of association tests. The discrepancies between these approaches may reflect the different hierarchical levels of selection considered (inter- and intrapopulation selection). Finally, we obtained evidence for convergent selection (similar for gradients) and clinal variation for a few genes, suggesting that comparisons between parallel gradients could be used to screen for major candidate genes responding to natural selection in trees. PMID:23934884

  2. Selecting CO2 Sources for CO2 Utilization by Environmental-Merit-Order Curves.

    PubMed

    von der Assen, Niklas; Müller, Leonard J; Steingrube, Annette; Voll, Philip; Bardow, André

    2016-02-02

    Capture and utilization of CO2 as alternative carbon feedstock for fuels, chemicals, and materials aims at reducing greenhouse gas emissions and fossil resource use. For capture of CO2, a large variety of CO2 sources exists. Since they emit much more CO2 than the expected demand for CO2 utilization, the environmentally most favorable CO2 sources should be selected. For this purpose, we introduce the environmental-merit-order (EMO) curve to rank CO2 sources according to their environmental impacts over the available CO2 supply. To determine the environmental impacts of CO2 capture, compression and transport, we conducted a comprehensive literature study for the energy demands of CO2 supply, and constructed a database for CO2 sources in Europe. Mapping these CO2 sources reveals that CO2 transport distances are usually small. Thus, neglecting transport in a first step, we find that environmental impacts are minimized by capturing CO2 first from chemical plants and natural gas processing, then from paper mills, power plants, and iron and steel plants. In a second step, we computed regional EMO curves considering transport and country-specific impacts for energy supply. Building upon regional EMO curves, we identify favorable locations for CO2 utilization with lowest environmental impacts of CO2 supply, so-called CO2 oases.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  4. Trace elements in shells of common gastropods in the near vicinity of a natural CO2 vent: no evidence of pH-dependent contamination

    NASA Astrophysics Data System (ADS)

    McClintock, J. B.; Amsler, C. D.; Amsler, M. O.; Duquette, A.; Angus, R. A.; Hall-Spencer, J. M.; Milazzo, M.

    2014-04-01

    There is concern that the use of natural volcanic CO2 vents as analogs for studies of the impacts of ocean acidification on marine organisms are biased due to physiochemical influences other than seawater pH alone. One issue that has been raised is whether potentially harmful trace elements in sediments that are rendered more soluble and labile in low pH environments are made more bioavailable, and sequestered in the local flora and fauna at harmful levels. In order to evaluate this hypothesis, we analyzed the concentrations of trace elements in shells (an established proxy for tissues) of four species of gastropods (two limpets, a topshell and a whelk) collected from three sites in Levante Bay, Vulcano Island. Each sampling site increased in distance from the primary CO2 vent and thus represented low, moderate, and ambient seawater pH conditions. Concentrations of As, Cd, Co, Cr, Hg, Mo, Ni, Pb, and V measured in shells using ICP-OES were below detection thresholds for all four gastropod species at all three sites. However, there were measurable concentrations of Sr, Mn, and U in the shells of the limpets Patella caerulea, P. rustica, and the snail Osilinus turbinatus, and similarly, Sr, Mn, U, and also Zn in the shells of the whelk Hexaplex trunculus. Levels of these elements were within the ranges measured in gastropod shells in non-polluted environments, and with the exception of U in the shells of P. caerulea, where the concentration was significantly lower at the collecting site closest to the vent (low pH site), there were no site-specific spatial differences in concentrations for any of the trace elements in shells. Thus trace element enhancement in sediments in low-pH environments was not reflected in greater bioaccumulations of potentially harmful elements in the shells of common gastropods.

  5. Natural leaf senescence: probed by chlorophyll fluorescence, CO2 photosynthetic rate and antioxidant enzyme activities during grain filling in different rice cultivars.

    PubMed

    Panda, Debabrata; Sarkar, Ramani Kumar

    2013-01-01

    Natural leaf senescence was investigated in four rainfed lowland rice cultivars, FR 13A (tolerant to submergence), Sabita and Sarala (adapted to medium depth, 0-50 cm stagnant flooding) and Dengi (conventional farmers' cultivar). Changes in the levels of pigment content, CO2 photosynthetic rate, photosystem II photochemistry and anti-oxidant enzyme activities of flag leaves during grain-filling stage were investigated. Chlorophyll content, photochemical efficiency of photosystem II and CO2 photosynthetic rate decreased significantly with the progress of grain-filling. Likely, the activities of antioxidant enzymes namely, superoxide dismutase, catalase, guaiacol peroxidase and ascorbate peroxidase decreased with progress of grain-filling. A substantial difference was observed among the four cultivars for the sustainability index (SI) of different photosynthetic parameters and antioxidant enzyme activities; SIs of those parameters, in general, were lower in low yielding cultivar FR 13A compared to the other three cultivars. Among the four cultivars Sabita gave maximum grain yield. Yet, SI of Pn was greater in Sarala and Dengi compared to the Sabita. SIs of electron transport (ETo/CS), maximal photochemical efficiency (Fv/Fm), area above Fo and Fm, catalase and ascorbate peroxidase were also greater in Sarala and Dengi. The data showed that among the different Chl a fluorescence parameters, PI could be used with greater accuracy to distinguish slow and fast senescence rice cultivars during grain-filling period. It was concluded that maintaining the vitality of rice plants during grain-filling gave guarantee to synthesize carbohydrate, however greater yield could be realized provided superior yield attributing parameters are present.

  6. Modelling global nitrogen export to ground and surface water from natural ecosystems: impact of N deposition, climate, and CO2 concentration

    NASA Astrophysics Data System (ADS)

    Braakhekke, Maarten; Rebel, Karin; Dekker, Stefan; van Beek, Rens; Bierkens, Marc; Smith, Ben; Wassen, Martin

    2015-04-01

    For large regions in the world strong increases in atmospheric nitrogen (N) deposition are predicted as a result of emissions from fossil fuel combustion and food production. This will cause many previously N limited ecosystems to become N saturated, leading to increased export to ground and surface water and negative impacts on the environment and human health. However, precise N export fluxes are difficult to predict. Due to its strong link to carbon, N in vegetation and soil is also determined by productivity, as affected by rising atmospheric CO2 concentration and temperature, and denitrification. Furthermore, the N concentration of water delivered to streams depends strongly on local hydrological conditions. We aim to study how N delivery to ground and surface water is affected by changes in environmental factors. To this end we are developing a global dynamic modelling system that integrates representations of N cycling in vegetation and soil, and N delivery to ground and surface water. This will be achieved by coupling the dynamic global vegetation model LPJ-GUESS, which includes representations of N cycling, as well as croplands and pasture, to the global water balance model PCR-GLOBWB, which simulates surface runoff, interflow, groundwater recharge, and baseflow. This coupling will allow us to trace N across different systems and estimate the input of N into the riverine system which can be used as input for river biogeochemical models. We will present large scale estimates of N leaching and transport to ground and surface water for natural ecosystems in different biomes, based on a loose coupling of the two models. Furthermore, by means of a factorial model experiment we will explore how these fluxes are influenced by N deposition, temperature, and CO2 concentration.

  7. Gate-opening upon CO2 adsorption on a metal-organic framework that mimics a natural stimuli-response system.

    PubMed

    Tseng, T W; Lee, L W; Luo, T T; Chien, P H; Liu, Y H; Lee, S L; Wang, C M; Lu, K L

    2017-09-28

    A dynamic metal-organic framework that consists of d-champhorate-based homochiral protuberant-grid-type networks can successively participate in gate-opening and closing processes for many cycles, which were triggered by the stimuli of the adsorption and desorption of CO2 to highly and specifically recognize CO2 over N2 and H2 with a high CO2 uptake of 90 mg g(-1) under 35 bar at 298 K. It is highly thermally stable and the structure remains intact at least for ten reversible gate-opening and -closing processes. Thus, it is a potential candidate for industrial CO2 capture and facile release.

  8. Egg discrimination along a gradient of natural variation in eggshell coloration

    PubMed Central

    Grim, Tomáš; Igic, Branislav; Samaš, Peter; López, Analía V.; Shawkey, Matthew D.; Hauber, Mark E.

    2017-01-01

    Accurate recognition of salient cues is critical for adaptive responses, but the underlying sensory and cognitive processes are often poorly understood. For example, hosts of avian brood parasites have long been assumed to reject foreign eggs from their nests based on the total degree of dissimilarity in colour to their own eggs, regardless of the foreign eggs' colours. We tested hosts' responses to gradients of natural (blue-green to brown) and artificial (green to purple) egg colours, and demonstrate that hosts base rejection decisions on both the direction and degree of colour dissimilarity along the natural, but not artificial, gradient of egg colours. Hosts rejected brown eggs and accepted blue-green eggs along the natural egg colour gradient, irrespective of the total perceived dissimilarity from their own egg's colour. By contrast, their responses did not vary along the artificial colour gradient. Our results demonstrate that egg recognition is specifically tuned to the natural gradient of avian eggshell colour and suggest a novel decision rule. These results highlight the importance of considering sensory reception and decision rules when studying perception, and illustrate that our understanding of recognition processes benefits from examining natural variation in phenotypes. PMID:28179521

  9. Sea anemones may thrive in a high CO2 world.

    PubMed

    Suggett, David J; Hall-Spencer, Jason M; Rodolfo-Metalpa, Riccardo; Boatman, Toby G; Payton, Ross; Tye Pettay, D; Johnson, Vivienne R; Warner, Mark E; Lawson, Tracy

    2012-10-01

    Increased seawater pCO2 , and in turn 'ocean acidification' (OA), is predicted to profoundly impact marine ecosystem diversity and function this century. Much research has already focussed on calcifying reef-forming corals (Class: Anthozoa) that appear particularly susceptible to OA via reduced net calcification. However, here we show that OA-like conditions can simultaneously enhance the ecological success of non-calcifying anthozoans, which not only play key ecological and biogeochemical roles in present day benthic ecosystems but also represent a model organism should calcifying anthozoans exist as less calcified (soft-bodied) forms in future oceans. Increased growth (abundance and size) of the sea anemone (Anemonia viridis) population was observed along a natural CO2 gradient at Vulcano, Italy. Both gross photosynthesis (PG ) and respiration (R) increased with pCO2 indicating that the increased growth was, at least in part, fuelled by bottom up (CO2 stimulation) of metabolism. The increase of PG outweighed that of R and the genetic identity of the symbiotic microalgae (Symbiodinium spp.) remained unchanged (type A19) suggesting proximity to the vent site relieved CO2 limitation of the anemones' symbiotic microalgal population. Our observations of enhanced productivity with pCO2 , which are consistent with previous reports for some calcifying corals, convey an increase in fitness that may enable non-calcifying anthozoans to thrive in future environments, i.e. higher seawater pCO2 . Understanding how CO2 -enhanced productivity of non- (and less-) calcifying anthozoans applies more widely to tropical ecosystems is a priority where such organisms can dominate benthic ecosystems, in particular following localized anthropogenic stress. © 2012 Blackwell Publishing Ltd.

  10. Geographical and environmental drivers of regional differences in the lake pCO2 versus DOC relationship across northern landscapes

    NASA Astrophysics Data System (ADS)

    Lapierre, Jean-François; del Giorgio, Paul A.

    2012-09-01

    Several recent studies have identified dissolved organic carbon (DOC) as playing a key role in determining surface water partial pressure of CO2 (pCO2) in northern lakes and, in particular, in shaping the commonly observed patterns of CO2 supersaturation. The nature of this role is unclear, however, and appears to vary regionally, as evidenced by the contrasting strength and shape of the diverse pCO2 versus DOC (pCO2-DOC) relationships. Here we combine original data on lakepCO2 from six boreal and temperate regions of Québec (Canada) with 13 studies from northern temperate and boreal aquatic landscapes published in the past 15 years to explore the factors that explain the differences in regional pCO2 baselines (pCO2 at low DOC) and in the slopes of the pCO2-DOC relationships. Mean elevation was the best predictor of the regionalpCO2 baselines, suggesting that lake position in the landscape determines the contribution of terrestrially derived CO2 to lake pCO2. In contrast, the slope of the pCO2-DOC relationships was strongly negatively correlated to the mean regional TP:DOC ratio. The relationship between DOC and TP varied at the cross-regional scale, and there was a large increase in the TP:DOC ratio at TP > 20μg L-1, resulting in negative slopes of the pCO2-DOC relationships for regions situated in that part of the TP gradient. These results highlight the interplay that exists between geographical gradients, large-scale biogeochemical patterns in regional lake trophic status, and the associated metabolic balance in determiningpCO2 dynamics in northern lakes.

  11. Fluid-rock interactions in CO2-saturated, granite-hosted geothermal systems: Implications for natural and engineered systems from geochemical experiments and models

    NASA Astrophysics Data System (ADS)

    Lo Ré, Caroline; Kaszuba, John P.; Moore, Joseph N.; McPherson, Brian J.

    2014-09-01

    Hydrothermal experiments were conducted and geochemical models constructed to evaluate the geochemical and mineralogical response of fractured granite and granite + epidote in contact with thermal water, with and without supercritical CO2, at 250 °C and 25-45 MPa. Illite ± smectite ± zeolite(?) precipitate as secondary minerals at the expense of K-feldspar, oligoclase, and epidote. Illite precipitates in experiments reacting granite and granite + epidote with water; metastable smectite forms in the experiments injected with supercritical CO2. Waters are supersaturated with respect to quartz and saturated with respect to chalcedony in CO2-charged experiments, but neither mineral formed. Carbonate formation is predicted for experiments injected with supercritical CO2, but carbonate only formed during cooling and degassing of the granite + epidote + CO2 experiment. Experimental results provide insight into the buffering capacity of granites as well as the drivers of clay formation. Metastable smectite in the experiments is attributed to high water-rock ratios, high silica activities, and high CO2 and magnesium-iron concentrations. Smectite precipitation in supercritical CO2-bearing geothermal systems may affect reservoir permeability. Silicate formation may create or thicken caps within or on the edges of geothermal reservoirs. Carbonate formation, as desired for carbon sequestration projects coinciding with geothermal systems, may require extended periods of time; cooling and degassing of CO2-saturated waters leads to carbonate precipitation, potentially plugging near-surface production pathways.

  12. Large natural pH, CO2 and O2 fluctuations in a temperate tidal salt marsh on diel, seasonal, and interannual time scales

    USGS Publications Warehouse

    Baumann, Hannes; Wallace, Ryan; Tagliaferri, Tristen N.; Gobler, Christopher J.

    2014-01-01

    Coastal marine organisms experience dynamic pH and dissolved oxygen (DO) conditions in their natural habitats, which may impact their susceptibility to long-term anthropogenic changes. Robust characterizations of all temporal scales of natural pH and DO fluctuations in different marine habitats are needed; however, appropriate time series of pH and DO are still scarce. We used multiyear (2008–2012), high-frequency (6 min) monitoring data to quantify diel, seasonal, and interannual scales of pH and DO variability in a productive, temperate tidal salt marsh (Flax Pond, Long Island, US). pHNBS and DO showed strong and similar seasonal patterns, with average (minimum) conditions declining from 8.2 (8.1) and 12.5 (11.4) mg l−1 at the end of winter to 7.6 (7.2) and 6.3 (2.8) mg l−1 in late summer, respectively. Concomitantly, average diel fluctuations increased from 0.22 and 2.2 mg l−1 (February) to 0.74 and 6.5 mg l−1 (August), respectively. Diel patterns were modulated by tides and time of day, eliciting the most extreme minima when low tides aligned with the end of the night. Simultaneous in situ pCO2 measurements showed striking fluctuations between ∼330 and ∼1,200 (early May), ∼2,200 (mid June), and ∼4,000 μatm (end of July) within single tidal cycles. These patterns also indicate that the marsh’s strong net heterotrophy influences its adjacent estuary by ‘outwelling’ acidified and hypoxic water during ebb tides. Our analyses emphasize the coupled and fluctuating nature of pH and DO conditions in productive coastal and estuarine environments, which have yet to be adequately represented by experiments.

  13. 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.

  14. Fundamental study of CO2-H2O-mineral interactions for carbon sequestration, with emphasis on the nature of the supercritical fluid-mineral interface.

    SciTech Connect

    Bryan, Charles R.; Dewers, Thomas A.; Heath, Jason E.; Wang, Yifeng; Matteo, Edward N.; Meserole, Stephen P.; Tallant, David Robert

    2013-09-01

    In the supercritical CO2-water-mineral systems relevant to subsurface CO2 sequestration, interfacial processes at the supercritical fluid-mineral interface will strongly affect core- and reservoir-scale hydrologic properties. Experimental and theoretical studies have shown that water films will form on mineral surfaces in supercritical CO2, but will be thinner than those that form in vadose zone environments at any given matric potential. The theoretical model presented here allows assessment of water saturation as a function of matric potential, a critical step for evaluating relative permeabilities the CO2 sequestration environment. The experimental water adsorption studies, using Quartz Crystal Microbalance and Fourier Transform Infrared Spectroscopy methods, confirm the major conclusions of the adsorption/condensation model. Additional data provided by the FTIR study is that CO2 intercalation into clays, if it occurs, does not involve carbonate or bicarbonate formation, or significant restriction of CO2 mobility. We have shown that the water film that forms in supercritical CO2 is reactive with common rock-forming minerals, including albite, orthoclase, labradorite, and muscovite. The experimental data indicate that reactivity is a function of water film thickness; at an activity of water of 0.9, the greatest extent of reaction in scCO2 occurred in areas (step edges, surface pits) where capillary condensation thickened the water films. This suggests that dissolution/precipitation reactions may occur preferentially in small pores and pore throats, where it may have a disproportionately large effect on rock hydrologic properties. Finally, a theoretical model is presented here that describes the formation and movement of CO2 ganglia in porous media, allowing assessment of the effect of pore size and structural heterogeneity on capillary trapping efficiency. The model results also suggest possible engineering approaches for optimizing trapping capacity and for

  15. Spatially Differentiated Soil CO2 Emissions from Six Hillslopes

    NASA Astrophysics Data System (ADS)

    Hu, Y.; Wang, R.; Wang, Z.; Kuhn, N. J.; Guo, S.

    2016-12-01

    Erosion induced CO2 emissions have been extensively studied across different scales from plot units to watershed. While slope is the essential element to initiate soil erosion and sediment transport, the potential effects of slope gradients and slope positions to soil CO2emissions have not yet been systematically studied. In this study, six east-facing plots of 100 m2 (20 m × 5 m) with increasing slope gradients of 0.5o (S 0.5), 1o (S1), 3o (S3), 5o (S5), 10o (S10) and 20o (S20), with identical soil preparation and wheat, were established in an eroded gully of the semi-arid Loess Plateau, China. Soil temperature, moisture and CO2emissions were detected once every week for two years from October 2013 to September 2015. Runoff and sediment yield were collected after detectable natural rainfall events. Surface litter, fine root biomass and aboveground biomass and SOC content of surface soil were also measured once a year. Our results show that: 1) annual soil CO2 emission rates exponentially decreased with slope gradients, on average from 843.7 g C m-2 year-1 at S0.5 to 388.2 g m-2 at S20. This is partially because of increasing C loss through runoff and sediment discharge from slopes of greater gradients (0.075 m3 year-1 from S0.5 vs. 63.8 m3 year-1 from S20), and also in part attributed to limited fine root growth on steeper slopes. 2) On each slope, CO2 emission rates also differed among slope positions, with 61% greater CO2 emissions from upper slope than lower slope. This agrees well with the erosion-induced spatial redistribution of SOC and soil moisture along the slope. Overall, slope differentiated soil moisture content and redistribution, and in consequence the spatially different fine root biomass, crop yields and CO2 emissions within slopes, must be adequately accounted for to fully understand the environmental impacts of agricultural management to regional agro-ecosystem.

  16. CO2 blood test

    MedlinePlus

    Bicarbonate test; HCO3-; Carbon dioxide test; TCO2; Total CO2; CO2 test - serum ... Many medicines can interfere with blood test results. Your health care provider will tell you if you need to stop taking any medicines before you have this test. DO ...

  17. CO2 laser resurfacing.

    PubMed

    Fitzpatrick, R E

    2001-07-01

    The CO2 Laser offers a variety of unique features in resurfacing facial photodamage and acne scarring. These include hemostasis, efficient removal of the epidermis in a single pass, thermally induced tissue tightening, and safe, predictable tissue interaction. Knowledge of these mechanisms will result in the capability of using the CO2 laser effectively and safely whether the goal is superficial or deep treatment.

  18. CO2 Sequestration Crosswell Monitoring

    NASA Astrophysics Data System (ADS)

    Morency, C.; Luo, Y.; Tromp, J.

    2010-12-01

    Geologic sequestration of CO2, a green house gas, represents an effort to reduce the large amount of CO2 generated as a by-product of fossil fuels combustion and emitted into the atmosphere. This process of sequestration involves CO2 storage deep underground into highly permeable porous media sealed by caprock. "4D seismics" is a natural non-intrusive monitoring technique which involves 3D time-lapse seismic surveys. The success of monitoring CO2 movement relies upon a proper description of the physics of the problem. We realize time-lapse migrations comparing acoustic, elastic (with or without Gassmann's formulae), and poroelastic simulations of 4D seismic imaging. This approach highlights the influence of using different physical theories on interpreting seismic data, and, more importantly, on extracting the CO2 signature from the seismic wave field. We investigate various types of inversions using (1) P-wave traveltimes, (2) P- & S-wave traveltimes and (3) P- & S-wave traveltimes and amplitudes. Simulations are performed using a spectral-element method, and finite-frequency sensitivity kernels, used in the non-linear iterative inversions, are calculated based on an adjoint method. Biot's equations are implemented in the forward and adjoint simulations to account for poroelastic effects.

  19. The Galapagos archipelago: A natural laboratory to examine sharp hydroclimatic, geologic and anthropogenic gradients

    USGS Publications Warehouse

    Percy, Madelyn; Schmitt, Sarah; Riveros-Iregui, Diego; Mirus, Benjamin B.

    2016-01-01

    Poor understanding of the water cycle in tropical ecosystems has the potential to exacerbate water shortages and water crises in the region. We suggest that the Galápagos Islands provide an excellent proxy to regions across the tropics as a result of sharp hydroclimatic, anthropogenic, and pedohydrologic gradients across the archipelago. Hydroclimatic and pedohydrologic gradients are found across different elevations on single islands, as well as across the archipelago, whereas anthropogenic gradients reflect land use and land cover change across islands as population and growth in tourism have affected individual islands differently. This article highlights specific opportunities to further examine our understanding of the interactions between water and critical zone processes in tropical ecosystems, making connections between the Galápagos archipelago and much of the understudied tropics. The Galápagos archipelago offers a natural laboratory through which we can examine current threats to freshwater security as well as the dynamics of coupled natural and human systems.

  20. Amine scrubbing for CO2 capture.

    PubMed

    Rochelle, Gary T

    2009-09-25

    Amine scrubbing has been used to separate carbon dioxide (CO2) from natural gas and hydrogen since 1930. It is a robust technology and is ready to be tested and used on a larger scale for CO2 capture from coal-fired power plants. The minimum work requirement to separate CO2 from coal-fired flue gas and compress CO2 to 150 bar is 0.11 megawatt-hours per metric ton of CO2. Process and solvent improvements should reduce the energy consumption to 0.2 megawatt-hour per ton of CO2. Other advanced technologies will not provide energy-efficient or timely solutions to CO2 emission from conventional coal-fired power plants.

  1. Superhydrophobic Cones for Continuous Collection and Directional Transportation of CO2 Microbubbles in CO2 Supersaturated Solutions.

    PubMed

    Xue, Xiuzhan; Yu, Cunming; Wang, Jingming; Jiang, Lei

    2016-12-27

    Microbubbles are tiny bubbles with diameters below 50 μm. Because of their minute buoyant force, the microbubbles stagnate in aqueous media for a long time, and they sometimes cause serious damage. Most traditional methods chosen for elimination of gas bubbles utilize buoyancy forces including chemical methods and physical methods, and they only have a minor effect on microbubbles. Several approaches have been developed to collect and transport microbubbles in aqueous media. However, the realization of innovative strategies to directly collect and transport microbubbles in aqueous media remains a big challenge. In nature, both spider silk and cactus spines take advantage of their conical-shaped surface to yield the gradient of Laplace pressure and surface free energy for collecting fog droplets from the environment. Inspired by this, we introduce here the gradient of Laplace pressure and surface free energy to the interface of superhydrophobic copper cones (SCCs), which can continuously collect and directionally transport CO2 microbubbles (from tip side to base side) in CO2-supersaturated solution. A gas layer was formed when the microbubbles encounter the SCCs. This offers a channel for microbubble directional transportation. The efficiency of microbubble transport is significantly affected by the apex angle of SCCs and the carbon dioxide concentration. The former provides different gradients of Laplace pressure as the driving force. The latter represents the capacity, which offers the quantity of CO2 microbubbles for collection and transportation. We believe that this approach provides a simple and valid way to remove microbubbles.

  2. Nonnative invasive plants: Maintaining biotic and soceioeconomic integrity along the urban-rural-natural gradient

    Treesearch

    Cynthia D. Huebner; David J. Nowak; Richard V. Pouyat; Allison R. Bodine

    2012-01-01

    In this chapter, we evaluate nonnative invasive plant species of the urban-rural-natural area gradient in order to reduce negative impacts of invasive plants on native species and ecosystems. This evaluation includes addressing (i) the concept of urban areas as the primary source of invasive plant species and characteristics of urban nonnative plants, including their...

  3. 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.

  4. Different Influences on Tropical Pacific SST Gradient from Natural Forcing and Anthropogenic Forcing

    NASA Astrophysics Data System (ADS)

    Ning, L.; Liu, J.; Wang, Z.

    2015-12-01

    Several simulations under natural forcing, greenhouse gas forcing, and full forcing (both natural forcing and anthropogenic forcing) over the last 2000 years using the Community Earth System Model (CESM) were used to investigate the different changes of tropical Pacific sea surface temperature (SST) gradient and corresponding mechanisms. Under the full forcing, during the present warming period (PWP; 1901-1999), Pacific SST shows larger warming over the whole tropical Pacific region than the subtropical Pacific region. This pattern is composed by an El Niño-like SST gradient due to the greenhouse gas forcing and a La Niña-like SST gradient due to the natural forcing. Two sensitivity experiments, the PWP under greenhouse gas forcing and Medieval Warming Period (MWP; 751-1250) under natural forcing, were used to examine the mechanisms. The results showed that, under the greenhouse forcing, the larger warming over eastern tropical Pacific is induced by increased surface net heat flux mainly contributed by short-wave radiation and latent heat flux. Under the natural forcing, the larger warming over western tropical Pacific is induced by changes of vertical heat transportation caused by the surface wind anomalies.

  5. Quantification of Natural Gradient Flow Using Active Fiber Optic DTS in Sealed Boreholes

    NASA Astrophysics Data System (ADS)

    Coleman, T. I.; Parker, B. L.; Munn, J. D.; Chalari, A.; Mondanos, M.

    2014-12-01

    Temperature has been used for many years to characterize flow in fractured rock systems. Fiber-optic distributed temperature sensing (DTS) was adopted by the oil/gas industry over two decades ago for monitoring processes in deep fractured rock environments. Improvements in DTS system resolutions, methodology advancements, and improved data processing techniques have caused recent popularity for shallow fractured rock hydrogeologic applications. A powerful advance in DTS methodology is the use of response data collected during active cable heating. When applied to borehole applications active heating creates a thermal disequilibrium in the aquifer system that enhances the detection of groundwater flow. Active DTS has been applied to open borehole environments; however, characterization methods based on open borehole measurements are limited in that only the effects of unnatural flow (i.e. vertical cross-connection and redistribution of flow creating local, induced flows) can be observed. To characterize natural gradient flow processes borehole effects need to be minimized.The literature shows borehole sealing using flexible impervious fabric liners creates a static water column in the well that eliminates the negative effects of cross-connection. Measurements in this sealed environment have been shown by others to be representative of natural gradient flow conditions, rather than the conditions created by the borehole short circuiting units or fractures with varying hydraulic head. A new method for flow system characterization using active DTS in sealed boreholes has been developed with excellent prospects for quantitation of natural gradient groundwater fluxes and related hydraulic properties. This project demonstrates the utility of using an analytical solution for calculating apparent thermal conductivities and natural gradient groundwater fluxes at depth-discrete intervals observed continuously along a borehole using active DTS. Groundwater flux data can then be

  6. The CO2nnect activities

    NASA Astrophysics Data System (ADS)

    Eugenia, Marcu

    2014-05-01

    Climate change is one of the biggest challenges we face today. A first step is the understanding the problem, more exactly what is the challenge and the differences people can make. Pupils need a wide competencies to meet the challenges of sustainable development - including climate change. The CO2nnect activities are designed to support learning which can provide pupils the abilities, skills, attitudes and awareness as well as knowledge and understanding of the issues. The project "Together for a clean and healthy world" is part of "The Global Educational Campaign CO2nnect- CO2 on the way to school" and it was held in our school in the period between February and October 2009. It contained a variety of curricular and extra-curricular activities, adapted to students aged from 11 to 15. These activities aimed to develop in students the necessary skills to understanding man's active role in improving the quality of the environment, putting an end to its degrading process and to reducing the effects of climate changes caused by the human intervention in nature, including transport- a source of CO2 pollution. The activity which I propose can be easily adapted to a wide range of age groups and linked to the curricula of many subjects: - Investigate CO2 emissions from travel to school -Share the findings using an international database -Compare and discuss CO2 emissions -Submit questions to a climate- and transport expert -Partner with other schools -Meet with people in your community to discuss emissions from transport Intended learning outcomes for pupils who participate in the CO2nnect campaign are: Understanding of the interconnected mobility- and climate change issue climate change, its causes and consequences greenhouse-gas emissions from transport and mobility the interlinking of social, environmental, cultural and economic aspects of the local transport system how individual choices and participation can contribute to creating a more sustainable development

  7. Trend analysis of CO2 and CH4 recorded at a semi-natural site in the northern plateau of the Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Pérez, Isidro A.; Sánchez, M. Luisa; García, M. Ángeles; Pardo, Nuria

    2017-02-01

    CO2 and CH4 were recorded from October 2010 to February 2016 with a Picarro G1301 analyser at the centre of the upper plateau of the Iberian Peninsula. Large CO2 values were observed during the vegetation growing season, and were reinforced by the stable boundary layer during the night. Annual CH4 evolution may be explained by ecosystem activity and by the dispersion linked with the evolution of the boundary layer. Their trends were studied using an equation that considers one polynomial and one harmonic part. The polynomial part revealed an increasing trend from 0.8 to 2.3 ppm year-1 for CO2 and from 0.004 to 0.011 ppm year-1 for CH4. The harmonic part considered four harmonics whose amplitudes were noticeable for the first and second harmonics for CO2 and for the first harmonic for CH4. Long-term evolution was similar with alternative equations. Finally, seasonal study indicated summer minima for both gases, which may be explained by the lack of vegetation in this season. Harmonic analysis showed two maxima for CO2, one in spring linked with vegetation growth, which decreased with time, and another in autumn related with the onset of plant activity after the summer, which increased with time. CH4 presented only one maximum in winter and a short time with steady concentration in spring where the evolution of the boundary layer may play a noticeable role. The harmonic equation, which takes into account all the observations, revealed opposite behaviour between CO2, whose minima decreased, and CH4, whose maxima increased.

  8. CO2 flux from Javanese mud volcanism.

    PubMed

    Queißer, M; Burton, M R; Arzilli, F; Chiarugi, A; Marliyani, G I; Anggara, F; Harijoko, A

    2017-06-01

    Studying the quantity and origin of CO2 emitted by back-arc mud volcanoes is critical to correctly model fluid-dynamical, thermodynamical, and geochemical processes that drive their activity and to constrain their role in the global geochemical carbon cycle. We measured CO2 fluxes of the Bledug Kuwu mud volcano on the Kendeng Fold and thrust belt in the back arc of Central Java, Indonesia, using scanning remote sensing absorption spectroscopy. The data show that the expelled gas is rich in CO2 with a volume fraction of at least 16 vol %. A lower limit CO2 flux of 1.4 kg s(-1) (117 t d(-1)) was determined, in line with the CO2 flux from the Javanese mud volcano LUSI. Extrapolating these results to mud volcanism from the whole of Java suggests an order of magnitude total CO2 flux of 3 kt d(-1), comparable with the expected back-arc efflux of magmatic CO2. After discussing geochemical, geological, and geophysical evidence we conclude that the source of CO2 observed at Bledug Kuwu is likely a mixture of thermogenic, biogenic, and magmatic CO2, with faulting controlling potential pathways for magmatic fluids. This study further demonstrates the merit of man-portable active remote sensing instruments for probing natural gas releases, enabling bottom-up quantification of CO2 fluxes.

  9. CO2 flux from Javanese mud volcanism

    NASA Astrophysics Data System (ADS)

    Queißer, M.; Burton, M. R.; Arzilli, F.; Chiarugi, A.; Marliyani, G. I.; Anggara, F.; Harijoko, A.

    2017-06-01

    Studying the quantity and origin of CO2 emitted by back-arc mud volcanoes is critical to correctly model fluid-dynamical, thermodynamical, and geochemical processes that drive their activity and to constrain their role in the global geochemical carbon cycle. We measured CO2 fluxes of the Bledug Kuwu mud volcano on the Kendeng Fold and thrust belt in the back arc of Central Java, Indonesia, using scanning remote sensing absorption spectroscopy. The data show that the expelled gas is rich in CO2 with a volume fraction of at least 16 vol %. A lower limit CO2 flux of 1.4 kg s-1 (117 t d-1) was determined, in line with the CO2 flux from the Javanese mud volcano LUSI. Extrapolating these results to mud volcanism from the whole of Java suggests an order of magnitude total CO2 flux of 3 kt d-1, comparable with the expected back-arc efflux of magmatic CO2. After discussing geochemical, geological, and geophysical evidence we conclude that the source of CO2 observed at Bledug Kuwu is likely a mixture of thermogenic, biogenic, and magmatic CO2, with faulting controlling potential pathways for magmatic fluids. This study further demonstrates the merit of man-portable active remote sensing instruments for probing natural gas releases, enabling bottom-up quantification of CO2 fluxes.

  10. CO2 flux from Javanese mud volcanism

    PubMed Central

    Burton, M. R.; Arzilli, F.; Chiarugi, A.; Marliyani, G. I.; Anggara, F.; Harijoko, A.

    2017-01-01

    Abstract Studying the quantity and origin of CO2 emitted by back‐arc mud volcanoes is critical to correctly model fluid‐dynamical, thermodynamical, and geochemical processes that drive their activity and to constrain their role in the global geochemical carbon cycle. We measured CO2 fluxes of the Bledug Kuwu mud volcano on the Kendeng Fold and thrust belt in the back arc of Central Java, Indonesia, using scanning remote sensing absorption spectroscopy. The data show that the expelled gas is rich in CO2 with a volume fraction of at least 16 vol %. A lower limit CO2 flux of 1.4 kg s−1 (117 t d−1) was determined, in line with the CO2 flux from the Javanese mud volcano LUSI. Extrapolating these results to mud volcanism from the whole of Java suggests an order of magnitude total CO2 flux of 3 kt d−1, comparable with the expected back‐arc efflux of magmatic CO2. After discussing geochemical, geological, and geophysical evidence we conclude that the source of CO2 observed at Bledug Kuwu is likely a mixture of thermogenic, biogenic, and magmatic CO2, with faulting controlling potential pathways for magmatic fluids. This study further demonstrates the merit of man‐portable active remote sensing instruments for probing natural gas releases, enabling bottom‐up quantification of CO2 fluxes. PMID:28944134

  11. Synthetic biology for CO2 fixation.

    PubMed

    Gong, Fuyu; Cai, Zhen; Li, Yin

    2016-11-01

    Recycling of carbon dioxide (CO2) into fuels and chemicals is a potential approach to reduce CO2 emission and fossil-fuel consumption. Autotrophic microbes can utilize energy from light, hydrogen, or sulfur to assimilate atmospheric CO2 into organic compounds at ambient temperature and pressure. This provides a feasible way for biological production of fuels and chemicals from CO2 under normal conditions. Recently great progress has been made in this research area, and dozens of CO2-derived fuels and chemicals have been reported to be synthesized by autotrophic microbes. This is accompanied by investigations into natural CO2-fixation pathways and the rapid development of new technologies in synthetic biology. This review first summarizes the six natural CO2-fixation pathways reported to date, followed by an overview of recent progress in the design and engineering of CO2-fixation pathways as well as energy supply patterns using the concept and tools of synthetic biology. Finally, we will discuss future prospects in biological fixation of CO2.

  12. The heat capacity of a natural monticellite and phase equilibria in the system CaO-MgO-SiO2-CO2

    USGS Publications Warehouse

    Sharp, Z.D.; Essene, E.J.; Anovitz, Lawrence M.; Metz, G.W.; Westrum, E.F.; Hemingway, B.S.; Valley, J.W.

    1986-01-01

    The heat capacity of a natural monticellite (Ca1.00Mg.09Fe.91Mn.01Si0.99O3.99) measured between 9.6 and 343 K using intermittent-heating, adiabatic calorimetry yields Cp0(298) and S2980 of 123.64 ?? 0.18 and 109.44 ?? 0.16 J ?? mol-1 K-1 respectively. Extrapolation of this entropy value to end-member monticellite results in an S0298 = 108.1 ?? 0.2 J ?? mol-1 K-1. High-temperature heat-capacity data were measured between 340-1000 K with a differential scanning calorimeter. The high-temperature data were combined with the 290-350 K adiabatic values, extrapolated to 1700 K, and integrated to yield the following entropy equation for end-member monticellite (298-1700 K): ST0(J ?? mol-1 K-1) = S2980 + 164.79 In T + 15.337 ?? 10-3 T + 22.791 ?? 105 T-2 - 968.94. Phase equilibria in the CaO-MgO-SiO2 system were calculated from 973 to 1673 K and 0 to 12 kbar with these new data combined with existing data for akermanite (Ak), diopside (Di), forsterite (Fo), merwinite (Me) and wollastonite (Wo). The location of the calculated reactions involving the phases Mo and Fo is affected by their mutual solid solution. A best fit of the thermodynamically generated curves to all experiments is made when the S0298 of Me is 250.2 J ?? mol-1 K-1 less than the measured value of 253.2 J ?? mol-1 K-1. A best fit to the reversals for the solid-solid and decarbonation reactions in the CaO-MgO-SiO2-CO2 system was obtained with the ??G0298 (kJ ?? mole-1) for the phases Ak(-3667), Di(-3025), Fo(-2051), Me(-4317) and Mo(-2133). The two invariant points - Wo and -Fo for the solid-solid reactions are located at 1008 ?? 5 K and 6.3 ?? 0.1 kbar, and 1361 ?? 10 K and 10.2 ?? 0.2 kbar respectively. The location of the thermodynamically generated curves is in excellent agreement with most experimental data on decarbonation equilibria involving these phases. ?? 1986.

  13. Nepenthes pitchers are CO2-enriched cavities, emit CO2 to attract preys.

    PubMed

    Baby, Sabulal; Johnson, Anil John; Zachariah, Elavinamannil Jacob; Hussain, Abdul Azeez

    2017-09-12

    Carnivorous plants of the genus Nepenthes supplement their nutrient deficiency by capturing arthropods or by mutualistic interactions, through their leaf-evolved biological traps (pitchers). Though there are numerous studies on these traps, mostly on their prey capture mechanisms, the gas composition inside them remains unknown. Here we show that, Nepenthes unopened pitchers are CO2-enriched 'cavities', when open they emit CO2, and the CO2 gradient around open pitchers acts as a cue attracting preys towards them. CO2 contents in near mature, unopened Nepenthes pitchers were in the range 2500-5000 ppm. Gas collected from inside open N. khasiana pitchers showed CO2 at 476.75 ± 59.83 ppm. CO2-enriched air-streaming through N. khasiana pitchers (at 619.83 ± 4.53 ppm) attracted (captured) substantially higher number of aerial preys compared to air-streamed pitchers (CO2 at 412.76 ± 4.51 ppm). High levels of CO2 dissolved in acidic Nepenthes pitcher fluids were also detected. We demonstrate respiration as the source of elevated CO2 within Nepenthes pitchers. Most unique features of Nepenthes pitchers, viz., high growth rate, enhanced carbohydrate levels, declined protein levels, low photosynthetic capacity, high respiration rate and evolved stomata, are influenced by the CO2-enriched environment within them.

  14. Fourier Transform Microwave Spectra of CO{2}-ETHYLENE Sulfide, CO{2}-ETHYLENE Oxide and CO{2}-PROPYLENE Oxide Complexes

    NASA Astrophysics Data System (ADS)

    Orita, Yukari; Kawashima, Yoshiyuki; Hirota, Eizi

    2010-06-01

    We have previously examined the difference in roles of O and S in structure and dynamics of the CO-ethylene oxide (EO) and CO-ethylene sulfide (ES) complexes. We have extended the investigation to CO{2}-EO and CO{2}-ES for comparison. We have also observed the CO{2}-propylene oxide (PO) complex, which is an important intermediate in the reaction of PO with CO{2} leading to polycarbonate. Both a-type and b-type transitions were observed for the CO{2}-EO and CO{2}-ES, but no c-type transitions were observed at all. We also detected the {34}S and {13}C isotopic species in natural abundance and the species containing {18}OCO and C{18}O% {2}, which were synthesized by burning paper in an {18}O{2} and{% 16}O{2} mixture. By analyzing the observed spectra we concluded the CO{2} moiety of CO{2}-EO and CO{2}-ES located in a plane % prependicular to the three-membered ring and bisecting the COC or CSC angle of EO or ES, respectively, as in the case of CO-EO and CO-ES complexes. An % ab initio MO calculation at the level of MP2/6-311G(d, p) yielded an optimized structure in good agreement with the experimental result. We have derived from the observed spectra the distance, the stretching force constant, and the binding energy of the bonds between the constituents of the CO{2}-EO and CO{2}-ES complexes and have found that the distances of the two complexes were shorter by 0.2Å than those in CO-EO and CO-ES, respectively, and that the intermolecular bonds were two times stronger in the CO{2} complexes than in the corresponding CO complexes. We have concluded from the observed spectra that the CO{2} moiety in CO{2}-PO is located on the PO three-membered ring plane opposite to the methyl group. The constituents in CO{2}-PO were more weakly bound than those in CO{2}-EO and CO{2}-ES. S. Sato, Y. Kawashima, Y. Tatamitani, and E. Hirota, 63rd International Symposium on Molecular Spectroscopy, WF05 (2008).

  15. Quantifying the "chamber effect" in CO2 flux measurements

    NASA Astrophysics Data System (ADS)

    Vihermaa, Leena; Childs, Amy; Long, Hazel; Waldron, Susan

    2014-05-01

    The significance of aquatic CO2 emissions has received attention in recent years. For example annual aquatic emissions in the Amazon basin have been estimated as 500 Mt of carbon1. Methods for determining the flux rates include eddy covariance flux tower measurements, flux estimates calculated from partial pressure of CO2 (pCO2) in water and the use floating flux chambers connected to an infra-red gas analyser. The flux chamber method is often used because it is portable, cheaper and allows smaller scale measurements. It is also a direct method and hence avoids problems related to the estimation of the gas transfer coefficient that is required when fluxes are calculated from pCO2. However, the use of a floating chamber may influence the flux measurements obtained. The chamber shields the water underneath from effects of wind which could lead to lower flux estimates. Wind increases the flux rate by i) causing waves which increase the surface area for efflux, and ii) removing CO2 build up above the water surface, hence maintaining a higher concentration gradient. Many floating chambers have an underwater extension of the chamber below the float to ensure better seal to water surface and to prevent any ingress of atmospheric air when waves rock the chamber. This extension may cause additional turbulence in flowing water and hence lead to overestimation of flux rates. Some groups have also used a small fan in the chamber headspace to ensure thorough mixing of air in the chamber. This may create turbulence inside the chamber which could increase the flux rate. Here we present results on the effects of different chamber designs on the detected flux rates. 1Richey et al. 2002. Outgassing from Amazonian rivers and wetlands as a large tropical source of atmospheric CO2. Nature 416: 617-620.

  16. Carbon balance, partitioning and photosynthetic acclimation in fruit-bearing grapevine (Vitis vinifera L. cv. Tempranillo) grown under simulated climate change (elevated CO2, elevated temperature and moderate drought) scenarios in temperature gradient greenhouses.

    PubMed

    Salazar-Parra, Carolina; Aranjuelo, Iker; Pascual, Inmaculada; Erice, Gorka; Sanz-Sáez, Álvaro; Aguirreolea, Jone; Sánchez-Díaz, Manuel; Irigoyen, Juan José; Araus, José Luis; Morales, Fermín

    2015-02-01

    Although plant performance under elevated CO2 has been extensively studied in the past little is known about photosynthetic performance changing simultaneously CO2, water availability and temperature conditions. Moreover, despite of its relevancy in crop responsiveness to elevated CO2 conditions, plant level C balance is a topic that, comparatively, has received little attention. In order to test responsiveness of grapevine photosynthetic apparatus to predicted climate change conditions, grapevine (Vitis vinifera L. cv. Tempranillo) fruit-bearing cuttings were exposed to different CO2 (elevated, 700ppm vs. ambient, ca. 400ppm), temperature (ambient vs. elevated, ambient +4°C) and irrigation levels (partial vs. full irrigation). Carbon balance was followed monitoring net photosynthesis (AN, C gain), respiration (RD) and photorespiration (RL) (C losses). Modification of environment (13)C isotopic composition (δ(13)C) under elevated CO2 (from -10.30 to -24.93‰) enabled the further characterization of C partitioning into roots, cuttings, shoots, petioles, leaves, rachides and berries. Irrespective of irrigation level and temperature, exposure to elevated CO2 induced photosynthetic acclimation of plants. C/N imbalance reflected the inability of plants grown at 700ppm CO2 to develop strong C sinks. Partitioning of labeled C to storage organs (main stem and roots) did not avoid accumulation of labeled photoassimilates in leaves, affecting negatively Rubisco carboxylation activity. The study also revealed that, after 20 days of treatment, no oxidative damage to chlorophylls or carotenoids was observed, suggesting a protective role of CO2 either at current or elevated temperatures against the adverse effect of water stress. Copyright © 2014 Elsevier GmbH. All rights reserved.

  17. A note on the recent natural gradient tracer test at the Borden site

    USGS Publications Warehouse

    Naff, R.L.; Yeh, T.-C.J.; Kemblowski, M.W.

    1988-01-01

    The variance in particle position, a measure of dispersion, is reviewed in the context of certain models of flow in random porous media. Asymptotic results for a highly stratified medium and an isotropic medium are particularly highlighted. Results of the natural gradient tracer test at the Borden site are reviewed in light of these models. This review suggests that the moments obtained for the conservative tracers could as well be explained by a model that more explicitly represents the three-dimensional nature of the flow field. -Authors

  18. Explaining global increases in water use efficiency: why have we overestimated responses to rising atmospheric CO(2) in natural forest ecosystems?

    PubMed

    Silva, Lucas C R; Horwath, William R

    2013-01-01

    The analysis of tree-ring carbon isotope composition (δ(13)C) has been widely used to estimate spatio-temporal variations in intrinsic water use efficiency (iWUE) of tree species. Numerous studies have reported widespread increases in iWUE coinciding with rising atmospheric CO(2) over the past century. While this could represent a coherent global response, the fact that increases of similar magnitude were observed across biomes with no apparent effect on tree growth raises the question of whether iWUE calculations reflect actual physiological responses to elevated CO(2) levels. Here we use Monte Carlo simulations to test if an artifact of calculation could explain observed increases in iWUE. We show that highly significant positive relationships between iWUE and CO(2) occur even when simulated data (randomized δ(13)C values spanning the observed range) are used in place of actual tree-ring δ(13)C measurements. From simulated data sets we calculated non-physiological changes in iWUE from 1900 to present and across a 4000 m altitudinal range. This generated results strikingly similar to those reported in recent studies encompassing 22 species from tropical, subtropical, temperate, boreal and mediterranean ecosystems. Only 6 of 49 surveyed case studies showed increases in iWUE significantly higher than predicted from random values. Our results reveal that increases in iWUE estimated from tree-ring δ(13)C occur independently of changes in (13)C discrimination that characterize physiological responses to elevated CO(2). Due to a correlation with CO(2) concentration, which is used as an independent factor in the iWUE calculation, any tree-ring δ(13)C data set would inevitably generate increasing iWUE over time. Therefore, although consistent, previously reported trends in iWUE do not necessarily reflect a coherent global response to rising atmospheric CO(2). We discuss the significance of these findings and suggest ways to distinguish real from artificial responses

  19. Electrochemical energy generation from natural and synthetic salinity gradients using reverse electrodialysis and capacitive mixing

    NASA Astrophysics Data System (ADS)

    Hatzell, Marta C.

    Salinity gradient energy (SGE) technologies are emerging systems designed to recover energy from engineered and natural mixing processes. Two electricity producing SGE systems are reverse electrodialysis (RED) and capacitive mixing (CapMix). RED captures mixing energy using a series of ion exchange membranes that drive electrochemical reactions at redox electrodes. CapMix utilizes polarizable electrodes to store charge in the surfaces electric double layer (EDL). Energy generation can then occur when the EDL is expanded and compressed in different concentration solutions. The use of themolytic salt solutions (e.g. ammonium bicarbonate--AmB) within a RED system is promising, as AmB can be regenerated using low-grade waste--heat (e.g. 40--60°C). One disadvantage to using AmB is the potential for gas bubbles (CO2, NH3) to form within the stack. Accumulation of bubbles can impede ion migration, and reduce system performance. The management and minimization of gaseous bubbles in RED flow fields is an important operational issue, and has not previously been addressed within RED literature. Flow field design with and without spacers in a RED stack was analyzed to determine how fluid flow and geometry effected the accumulation and removal of bubbles. In addition, the performance changes, in terms of power and resistance were measured in the presence of bubbles. Gaseous bubble accumulation was minimized using short vertically aligned channels, which resulted in a reduction in the amount of the membrane area which was restricted due to bubbles from ~20% to 7%. The stack power density improved by 12% when all gaseous bubbles were removed from the cell. AmB-RED systems can potentially produce hydrogen or electrical energy through altering the cathodic reaction. With a kinetically favorable cathodic reaction (oxygen reduction reaction), the projected electrical energy generated by a single pass AmB--RED system approached 78 Wh per m--3 (low concentrate). However, when RED was

  20. India Co2 Emissions

    NASA Astrophysics Data System (ADS)

    Sharan, S.; Diffenbaugh, N. S.

    2010-12-01

    created a balance in between the “developed” and developing countries. If India was producing the same amounts of emissions per capita as the it would have a total of 20 billion metric tons of CO2 emissions annually.

  1. Effects of nutrient supply on intrinsic water-use efficiency of temperate semi-natural grassland under rising atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Koehler, I. H.; MacDonald, A.; Poulton, P.; Auerswald, K.; Schnyder, H.

    2010-12-01

    C3 plants generally increase photosynthesis (A) and decrease stomatal conductance (gs) under elevated CO2 [1]. However, nitrogen limitation has been shown to constrain the response of A [2] and could thus limit the increase in intrinsic water-use efficiency Wi. Stable carbon isotope studies on trees have shown that Wi increased in forests during the last century. Recently we showed that Wi has also increased in nutrient limited grassland ecosystems [3, 4]. We have now examined a 50 year-long record of Wi from community-level carbon isotope discrimination (13Δ) derived from archived hay and herbage samples (Park Grass Continuous Hay Experiment, Rothamsted, England [5]). We tested the hypothesis that plant responses to increasing atmospheric CO2 have resulted in a greater increase in Wi where plants received adequate nutrient inputs, because of the expected stronger increase in A with higher nutrient supply. We examined whether the response to rising CO2 was uniform across fertilizer treatments. Archived samples from five plots on Park Grass with different annual fertilizer applications (1. No N or PK; 2. 48 kg N ha-1, No PK; 3. No N +PK; 4. 48 kg N ha-1 +PK; 5. 96 kg N ha-1 +PK), covering the 1960 - 2009 period, were used. During the study period, atmospheric CO2 concentration increased by 22%. 13Δ was calculated from carbon isotope composition δ13C (= [(Rsample/Rstandard) - 1], with R the 13C/12C ratio in the sample or standard). 13Δ is a proxy of the leaf-level coupling of CO2 and transpiration fluxes, and a measure of Wi, with Wi = A/gs = ca (1 - ci / ca) / 1.6 and ci / ca = (13Δ - a) / (b - a), (a=4.4‰, b=27‰). Linear regression showed significant 13Δ increases: 0.1‰ per 10 ppm CO2 increase on the control (P<0.05), the PK treatment (P<0.001) and the low N, PK treatment (P<0.05). On the low N treatment, the increase was only significant at the 10% level. On the high N, PK treatment 13Δ increased by 0.04‰ per 10 ppm, but this was not significant (P

  2. Carboxylic acid derivatives via catalytic carboxylation of unsaturated hydrocarbons: whether the nature of a reductant may determine the mechanism of CO2 incorporation?†

    SciTech Connect

    Kirillov, E.; Carpentier, J.-F.; Bunel, Emilio E.

    2015-01-01

    Application of CO2 as a renewable feedstock and C1 building block for production of commodity and fine chemicals is a highly challenging but obvious industry-relevant task. Of particular interest is the catalytic coupling of CO(2)with inexpensive unsaturated hydrocarbons (olefins, dienes, styrenes, alkynes), providing direct access to carboxylic acids and their derivatives. Although not brand new for the scientific community, it is still a complete challenge, as no truly effective catalytic system has been reported to date. In this Perspective, we discuss the available experimental, theoretical and mechanistic data for such homogeneously catalyzed carboxylation processes. A special focus is placed on the understanding of the key elementary steps and of some thermodynamic and kinetic constraints.

  3. CO2-neutral fuels

    NASA Astrophysics Data System (ADS)

    Goede, A. P. H.

    2015-08-01

    The need for storage of renewable energy (RE) generated by photovoltaic, concentrated solar and wind arises from the fact that supply and demand are ill-matched both geographically and temporarily. This already causes problems of overcapacity and grid congestion in countries where the fraction of RE exceeds the 20% level. A system approach is needed, which focusses not only on the energy source, but includes conversion, storage, transport, distribution, use and, last but not least, the recycling of waste. Furthermore, there is a need for more flexibility in the energy system, rather than relying on electrification, integration with other energy systems, for example the gas network, would yield a system less vulnerable to failure and better adapted to requirements. For example, long-term large-scale storage of electrical energy is limited by capacity, yet needed to cover weekly to seasonal demand. This limitation can be overcome by coupling the electricity net to the gas system, considering the fact that the Dutch gas network alone has a storage capacity of 552 TWh, sufficient to cover the entire EU energy demand for over a month. This lecture explores energy storage in chemicals bonds. The focus is on chemicals other than hydrogen, taking advantage of the higher volumetric energy density of hydrocarbons, in this case methane, which has an approximate 3.5 times higher volumetric energy density. More importantly, it allows the ready use of existing gas infrastructure for energy storage, transport and distribution. Intermittent wind electricity generated is converted into synthetic methane, the Power to Gas (P2G) scheme, by splitting feedstock CO2 and H2O into synthesis gas, a mixture of CO and H2. Syngas plays a central role in the synthesis of a range of hydrocarbon products, including methane, diesel and dimethyl ether. The splitting is accomplished by innovative means; plasmolysis and high-temperature solid oxygen electrolysis. A CO2-neutral fuel cycle is

  4. Soil bacterial endemism and potential functional redundancy in natural broadleaf forest along a latitudinal gradient

    PubMed Central

    Zhang, Yuguang; Cong, Jing; Lu, Hui; Deng, Ye; Liu, Xiao; Zhou, Jizhong; Li, Diqiang

    2016-01-01

    Microorganisms play key roles in ecosystem processes and biogeochemical cycling, however, the relationship between soil microbial taxa diversity and their function in natural ecosystems is largely unknown. To determine how soil bacteria community and function are linked from the local to regional scale, we studied soil bacteria community composition, potential function and environmental conditions in natural and mature broadleaf forests along a latitudinal gradient in China, using the Illumina 16S rRNA sequencing and GeoChip technologies. The results showed strong biogeographic endemism pattern in soil bacteria were existed, and the spatial distance and climatic variables were the key controlling factors for this pattern. Therefore, dispersal limitation and environmental selection may represent two key processes in generating and maintaining the soil bacterial biogeographic pattern. By contrast, the soil bacterial potential function is highly convergent along the latitudinal gradient and there were highly differing bacterial community compositions, and the soil chemistry may include the main factors active in shaping the soil bacterial potential function. Therefore, the soil bacterial potential function may be affected by local gradients in resource availability, and predicting soil bacterial potential function requires knowledge of abiotic and biotic environmental factors. PMID:27357005

  5. Soil bacterial endemism and potential functional redundancy in natural broadleaf forest along a latitudinal gradient

    NASA Astrophysics Data System (ADS)

    Zhang, Yuguang; Cong, Jing; Lu, Hui; Deng, Ye; Liu, Xiao; Zhou, Jizhong; Li, Diqiang

    2016-06-01

    Microorganisms play key roles in ecosystem processes and biogeochemical cycling, however, the relationship between soil microbial taxa diversity and their function in natural ecosystems is largely unknown. To determine how soil bacteria community and function are linked from the local to regional scale, we studied soil bacteria community composition, potential function and environmental conditions in natural and mature broadleaf forests along a latitudinal gradient in China, using the Illumina 16S rRNA sequencing and GeoChip technologies. The results showed strong biogeographic endemism pattern in soil bacteria were existed, and the spatial distance and climatic variables were the key controlling factors for this pattern. Therefore, dispersal limitation and environmental selection may represent two key processes in generating and maintaining the soil bacterial biogeographic pattern. By contrast, the soil bacterial potential function is highly convergent along the latitudinal gradient and there were highly differing bacterial community compositions, and the soil chemistry may include the main factors active in shaping the soil bacterial potential function. Therefore, the soil bacterial potential function may be affected by local gradients in resource availability, and predicting soil bacterial potential function requires knowledge of abiotic and biotic environmental factors.

  6. Influence of natural organic matter fouling and osmotic backwash on pressure retarded osmosis energy production from natural salinity gradients.

    PubMed

    Yip, Ngai Yin; Elimelech, Menachem

    2013-01-01

    Pressure retarded osmosis (PRO) has the potential to produce clean, renewable energy from natural salinity gradients. However, membrane fouling can lead to diminished water flux productivity, thus reducing the extractable energy. This study investigates organic fouling and osmotic backwash cleaning in PRO and the resulting impact on projected power generation. Fabricated thin-film composite membranes were fouled with model river water containing natural organic matter. The water permeation carried foulants from the feed river water into the membrane porous support layer and caused severe water flux decline of ∼46%. Analysis of the water flux behavior revealed three phases in membrane support layer fouling. Initial foulants of the first fouling phase quickly adsorbed at the active-support layer interface and caused a significantly greater increase in hydraulic resistance than the subsequent second and third phase foulants. The water permeability of the fouled membranes was lowered by ∼39%, causing ∼26% decrease in projected power density. A brief, chemical-free osmotic backwash was demonstrated to be effective in removing foulants from the porous support layer, achieving ∼44% recovery in projected power density. The substantial performance recovery after cleaning was attributed to the partial restoration of the membrane water permeability. This study shows that membrane fouling detrimentally impacts energy production, and highlights the potential strategies to mitigate fouling in PRO power generation with natural salinity gradients.

  7. CarbonSat -Quantification of natural and man-made greenhouse gas surface fluxes from satellite observations of atmospheric CO2 and CH4 column amounts

    NASA Astrophysics Data System (ADS)

    Bovensmann, Heinrich; Buchwitz, M.; Burrows, J. P.; Notholt, J.; Bovensmann, H.; Reuter, M.; Trautmann, T.; Ehret, G.; Heimann, M.; Monks, P.; B&Ü, H.; Sch; Harding, R.; Quegan, S.; Rayner, P.; Breon, F. M.; Bergam-O Aschi, P.; Dittus, H. J.; Erzinger, J.; Crisp, D.

    Surprisingly and in spite of their exceptional driving role in climate change, our knowledge about the variable sources and sinks of the greenhouse gases CO2 and CH4 is currently inadequate. For example, the ability of the Earth-atmosphere system to buffer increasing anthropogenic emissions into the atmosphere has large uncertainties and emissions from many sources (geo-logic, anthropogenic, biogenic) are to a large degree uncertain. An adequate knowledge of the sources and sinks of CO2 and CH4 and their response to a changing climate is a pre-requisite for the accurate prediction of the regional variation of the climate of our planet. CarbonSat is a new mission concept to quantify and monitor CO2 and CH4 sources and sinks at the regional to local scale. The data will allow a better understanding of the processes that control the Carbon Cycle dynamics and an independent estimate of local greenhouse gas emissions (fossil fuel, geological CO2 and CH4, etc.). This will be achieved by a unique combination of high spatial resolution passive and active compact remote sensing with inverse modeling techniques. CarbonSat will accurately measure column-averaged mixing ratios of CO2 and CH4, i.e., XCO2 and XCH4, at a spatial resolution of 2 x 2 km2 (500 km continuous swath) with 0.5 percent goal (1 percent threshold) single measurement precision and global coverage within 3-6 days. Beside the quantification of sources and sinks on the regional scale, one key and innovative aim of the CarbonSat mission is to go a step forward towards quantifying local emission hot spots (fossil fuel emissions by power plants, gas/oil production, geological sources etc.). The core sensor will be a compact Imaging NIR/SWIR spectrometer (SCIAMACHY, OCO her-itage) whose measurements yield global data sets of XCO2 and XCH4 with at least one order of magnitude higher number of cloud free measurements than GOSAT and OCO and one order of magnitude better spatial coverage than OCO, due to Carbon

  8. CarbonSat - Quantification of natural and man-made greenhouse gas surface fluxes from satellite observations of atmospheric CO2 and CH4 column amounts

    NASA Astrophysics Data System (ADS)

    Bovensmann, Heinrich; Buchwitz, Michael

    2010-05-01

    Surprisingly and in spite of their exceptional driving role in climate change, our knowledge about the variable sources and sinks of the greenhouse gases CO2 and CH4 is currently inadequate. For example, the ability of the Earth-atmosphere system to buffer increasing anthropogenic emissions into the atmosphere has large uncertainties and emissions from many sources (geologic, anthropogenic, biogenic) are to a large degree uncertain. An adequate knowledge of the sources and sinks of CO2 and CH4 and their response to a changing climate is a pre-requisite for the accurate prediction of the regional variation of the climate of our planet. CarbonSat is a new mission concept to quantify and monitor CO2 and CH4 sources and sinks at the regional to local scale. The data will allow a better understanding of the processes that control the Carbon Cycle dynamics and an independent estimate of local greenhouse gas emissions (fossil fuel, geological CO2 and CH4, etc.). This will be achieved by a unique combination of high spatial resolution passive and active compact remote sensing with inverse modeling techniques. CarbonSat will accurately measure column-averaged mixing ratios of CO2 and CH4, i.e., XCO2 and XCH4, at a spatial resolution of 2 x 2 km2 (500 km continuous swath) with 0.5% goal (1%, threshold) single measurement precision and global coverage within 3-6 days. Beside the quantification of sources and sinks on the regional scale, one key and innovative aim of the CarbonSat mission is to go a step forward towards quantifying local emission hot spots (fossil fuel emissions by power plants, gas/oil production, geological sources etc.). The core sensor will be a compact Imaging NIR/SWIR spectrometer (SCIAMACHY, OCO heritage) whose measurements yield global data sets of XCO2 and XCH4 with at least one order of magnitude higher number of cloud free measurements than GOSAT and OCO and one order of magnitude better spatial coverage than OCO, due to CarbonSat's 500 km swath

  9. Natural convection in binary gases driven by combined horizontal thermal and vertical solutal gradients

    NASA Technical Reports Server (NTRS)

    Weaver, J. A.; Viskanta, Raymond

    1992-01-01

    An investigation of natural convection is presented to examine the influence of a horizontal temperature gradient and a concentration gradient occurring from the bottom to the cold wall in a cavity. As the solutal buoyancy force changes from augmenting to opposing the thermal buoyancy force, the fluid motion switches from unicellular to multicellular flow (fluid motion is up the cold wall and down the hot wall for the bottom counterrotating flow cell). Qualitatively, the agreement between predicted streamlines and smoke flow patterns is generally good. In contrast, agreement between measured and predicted temperature and concentration distributions ranges from fair to poor. Part of the discrepancy can be attributed to experimental error. However, there remains considerable discrepancy between data and predictions due to the idealizations of the mathematical model, which examines only first-order physical effects. An unsteady flow, variable thermophysical properties, conjugate effects, species interdiffusion, and radiation were not accounted for in the model.

  10. Widespread Low-Latitude Diurnal CO2 Frost on Mars

    NASA Astrophysics Data System (ADS)

    Piqueux, S.; Kleinböhl, A.; Hayne, P. O.; Heavens, N. G.; Kass, D. M.; McCleese, D. J.; Schofield, J. T.; Shirley, J. H.

    2016-09-01

    We map and characterize MCS nighttime surface temperature observations consistent with the occurrence of CO2 frost on Mars. Low-latitude nighttime CO2 frost is widespread, with potential implications for the physical nature of the surface layer.

  11. CO2 on Titan

    NASA Technical Reports Server (NTRS)

    Samuelson, R. E.; Maguire, W. C.; Hanel, R. A.; Kunde, V. G.; Jennings, D. E.; Yung, Y. L.; Aikin, A. C.

    1983-01-01

    A sharp stratospheric emission feature at 667/cm in the Voyager infrared spectra of Titan is associated with the nu2 Q branch of CO2. A coupling of photochemical and radiative-transfer theory yields an average mole fraction above the 110 mbar level of (1.5 + 1.5 or - 0.8) x 10 to the -9th, with most of the uncertainty being due to imprecise knowledge of the vertical distribution. CO2 is found to be in a steady state, with its abundance being regulated principally by the 72 K cold trap near the tropopause and secondarily by the rate at which water-bearing meteoritic material enters the top of the atmosphere. An influx of water about 0.4 times that at the top of the terrestrial atmosphere is consistent with a combination of the observed CO2 abundance and a steady-state CO mole fraction of 0.00011; the thoeretical value for CO is close to the value observed by Lutz et al. (1983), although there are large margins for error in both numbers. If steady-state conditions for CO prevail, little information is available regarding the evolution of Titan's atmosphere.

  12. Nature of Transport across Sheared Zonal Flows in Electrostatic Ion-Temperature-Gradient Gyrokinetic Plasma Turbulence

    SciTech Connect

    Sanchez, R.; Newman, D. E.; Leboeuf, J.-N.; Decyk, V. K.; Carreras, B. A.

    2008-11-14

    It is shown that the usual picture for the suppression of turbulent transport across a stable sheared flow based on a reduction of diffusive transport coefficients is, by itself, incomplete. By means of toroidal gyrokinetic simulations of electrostatic, collisionless ion-temperature-gradient turbulence, it is found that the nature of the transport is altered fundamentally, changing from diffusive to anticorrelated and subdiffusive. Additionally, whenever the flows are self-consistently driven by turbulence, the transport gains an additional non-Gaussian character. These results suggest that a description of transport across sheared flows using effective diffusivities is oversimplified.

  13. Natural convection in binary gases due to horizontal thermal and solutal gradients

    NASA Technical Reports Server (NTRS)

    Weaver, J. A.; Viskanta, R.

    1991-01-01

    The influence of augmenting and opposing thermal and solutal buoyancy forces on natural convection of binary gases due to horizontal temperature and concentration gradients is examined through comparison of smoke flow visualization and measured temperature and concentration distributions with numerical predictions. The observed flow at the cold wall was unsteady for opposing body forces. The same basic flow structure was observed, but the unsteady flow intensifies as the opposing solutal buoyancy force increases as compared to the thermal buoyancy force. Comparison of predicted and measured temperatures and concentrations is fair overall, but the steady-state analytical model fails to predict the unsteady flow and heat and mass transport for opposing body forces.

  14. CO2 Respiration/O2 Consumption in Response to Supplemental Organic Carbon: Implications for Natural DOC Composition in San Pedro Basin, CA

    NASA Astrophysics Data System (ADS)

    Berelson, W.; Fleming, J. C.; Aluwihare, L.; Hammond, D. E.

    2016-02-01

    Microbial community respiration plays an integral role in oxygen and carbon cycling in the world's oceans, but it is poorly constrained in most marine settings, especially in the mesopelagic. We set out to define respiration rates in San Pedro Basin, within the Southern California Bight, with specific focus on the 100 m depth zone in order to determine both how community respiration is influenced by carbon supply perturbations, and the impact of DOC utilization on oxygen and CO2. Evoking Michaelis-Menten kinetics, it is apparent that observed community respiration rates are always well-below their maximum potential, Vmax. Furthermore, the assumption that respiration proceeds with a respiratory quotient (RQ) of 1, i.e., 1 molecule of TCO2 (aka DIC) produced per molecule of O2 consumed, is not correct for this setting. A carbon addition experiment with 13C labeled glucose suggests that RQ-values for respiration at 100 m in San Pedro Basin are close to 2, indicating that the substrates used for respiration are likely highly-oxidized carbon compounds. Thus, any potential increases in biological O2 uptake may lead to increases in CO2 production of even greater magnitude, resulting in changes in ocean chemistry through a pathway that has not been fully considered. We propose that as POC produced in the surface ocean sinks and is oxidized, small organic acids are progressively produced that, by 100 m, constitute a significant portion of the DOC pool.

  15. No-reference image quality assessment based on natural scene statistics and gradient magnitude similarity

    NASA Astrophysics Data System (ADS)

    Jia, Huizhen; Sun, Quansen; Ji, Zexuan; Wang, Tonghan; Chen, Qiang

    2014-11-01

    The goal of no-reference/blind image quality assessment (NR-IQA) is to devise a perceptual model that can accurately predict the quality of a distorted image as human opinions, in which feature extraction is an important issue. However, the features used in the state-of-the-art "general purpose" NR-IQA algorithms are usually natural scene statistics (NSS) based or are perceptually relevant; therefore, the performance of these models is limited. To further improve the performance of NR-IQA, we propose a general purpose NR-IQA algorithm which combines NSS-based features with perceptually relevant features. The new method extracts features in both the spatial and gradient domains. In the spatial domain, we extract the point-wise statistics for single pixel values which are characterized by a generalized Gaussian distribution model to form the underlying features. In the gradient domain, statistical features based on neighboring gradient magnitude similarity are extracted. Then a mapping is learned to predict quality scores using a support vector regression. The experimental results on the benchmark image databases demonstrate that the proposed algorithm correlates highly with human judgments of quality and leads to significant performance improvements over state-of-the-art methods.

  16. Evaluation of longitudinal dispersivity estimates from simulated forced- and natural-gradient tracer tests in heterogeneous aquifers

    USGS Publications Warehouse

    Tiedeman, C.R.; Hsieh, P.A.

    2004-01-01

    We simulate three types of forced-gradient tracer tests (converging radial flow, unequal strength two well, and equal strength two well) and natural-gradient tracer tests in multiple realizations of heterogeneous two-dimensional aquifers with a hydraulic conductivity distribution characterized by a spherical variogram. We determine longitudinal dispersivities (??L) by analysis of forced-gradient test breakthrough curves at the pumped well and by spatial moment analysis of tracer concentrations during the natural-gradient tests. Results show that among the forced-gradient tests, a converging radial-flow test tends to yield the smallest ??L, an equal strength two-well test tends to yield the largest ??L, and an unequal strength two-well test tends to yield an intermediate value. This finding is qualitatively explained by considering the aquifer area sampled by a particular test. A converging radial-flow test samples a small area, and thus the tracer undergoes a low degree of spreading and mixing. An equal strength two-well test samples a much larger area, so the tracer is spread and mixed to a greater degree. Results also suggest that if the distance between the tracer source well and the pumped well is short relative to the lengths over which velocity is correlated, then the ??L estimate can be highly dependent on local heterogeneities in the vicinity of the wells. Finally, results indicate that ??L estimated from forced-gradient tracer tests can significantly underestimate the ??L needed to characterize solute dispersion under natural-gradient flow. Only a two-well tracer test with a large well separation in an aquifer with a low degree of heterogeneity can yield a value of ??L that characterizes natural-gradient tracer spreading. This suggests that a two-well test with a large well separation is the preferred forced-gradient test for characterizing solute dispersion under natural-gradient flow.

  17. The carbon cycle and atmospheric CO2: Natural variations archean to present; Proceedings of the Chapman Conference on Natural Variations in Carbon Dioxide and the Carbon Cycle, Tarpon Springs, FL, January 9-13, 1984

    NASA Astrophysics Data System (ADS)

    Sundquist, E. T.; Broecker, W. S.

    The present conference on the history of the relationship between atmospheric CO2 and the carbon cycle treats data obtained concerning the most recent deglaciation, the Pleistocene, the Zenozoic, and the Phanerozoic-Precambrian. Specific attention is given to the geophysical implications of the tropospheric methane cycle, transient response of the marine carbon cycle, factors regulating glacial to interglacial CO2 changes, the high latitude ocean as a control of atmospheric CO2, and the relationships among atmospheric CO2, orbital forcing, and climate. Also discussed are the distribution of major vegetation types during the Tertiary, a 'Strangelove' ocean in the earliest Tertiary, high atmospheric CO2 as a plausible mechanism for warm Cretaceous climates, and potential estimation errors in carbonate rock accumulation over geologic time.

  18. Studies on CO 2 laser marking

    NASA Astrophysics Data System (ADS)

    Ueda, Masahiro; Saitoh, Yoshikazu; Hachisuka, Hideki; Ishigaki, Hiroyuki; Gokoh, Yukihiro; Mantani, Hiroshi

    The nature of CO 2 laser marking was studied with a view to putting these lasers to practical use in the semiconductor industry. The marking is found to be due to surface spattering rather than burning, which is the main factor in YAG laser marking. The visibility greatly increases by the application of a surface treatment such as marker ink, varnish or poster color. The CO 2 laser may therefore be used in place of the YAG laser, now widely used for marking, with some merits: CO 2 laser marking is cheaper and faster, and in addition there is no danger of injury from irradiating laser light.

  19. Global integral gradient bounds for quasilinear equations below or near the natural exponent

    NASA Astrophysics Data System (ADS)

    Phuc, Nguyen Cong

    2014-10-01

    We obtain sharp integral potential bounds for gradients of solutions to a wide class of quasilinear elliptic equations with measure data. Our estimates are global over bounded domains that satisfy a mild exterior capacitary density condition. They are obtained in Lorentz spaces whose degrees of integrability lie below or near the natural exponent of the operator involved. As a consequence, nonlinear Calderón-Zygmund type estimates below the natural exponent are also obtained for -superharmonic functions in the whole space ℝ n . This answers a question raised in our earlier work (On Calderón-Zygmund theory for p- and -superharmonic functions, to appear in Calc. Var. Partial Differential Equations, DOI 10.1007/s00526-011-0478-8) and thus greatly improves the result there.

  20. In situ measurement of methane oxidation in groundwater by using natural-gradient tracer tests

    USGS Publications Warehouse

    Smith, R.L.; Howes, B.L.; Garabedian, S.P.

    1991-01-01

    Methane oxidation was measured in an unconfined sand and gravel aquifer (Cape Cod, Mass.) by using in situ natural-gradient tracer tests at both a pristine, oxygenated site and an anoxic, sewage-contaminated site. The tracer sites were equipped with multilevel sampling devices to create target grids of sampling points; the injectate was prepared with groundwater from the tracer site to maintain the same geochemical conditions. Methane oxidation was calculated from breakthrough curves of methane relative to halide and inert gas (hexafluoroethane) tracers and was confirmed by the appearance of 13C-enriched carbon dioxide in experiments in which 13C-enriched methane was used as the tracer. A V(max) for methane oxidation could be calculated when the methane concentration was sufficiently high to result in zero-order kinetics throughout the entire transport interval. Methane breakthrough curves could be simulated by modifying a one-dimensional advection-dispersion transport model to include a Michaelis-Menten-based consumption term for methane oxidation. The K(m) values for methane oxidation that gave the best match for the breakthrough curve peaks were 6.0 and 9.0 ??M for the uncontaminated and contaminated sites, respectively. Natural-gradient tracer tests are a promising approach for assessing microbial processes and for testing in situ bioremediation potential in groundwater systems.

  1. Similarity in the difference: changes in community functional features along natural and anthropogenic stress gradients.

    PubMed

    Gutiérrez-Cánovas, Cayetano; Sánchez-Fernández, David; Velasco, Josefa; Millan, Andrés; Bonada, Núria

    2015-09-01

    The effect of stressors on biodiversity can vary in relation to the degree to which biological communities have adapted over evolutionary time. We compared the responses of functional features of stream insect communities along chronic stress gradients with contrasting time persistence. Water salinity and land use intensification were used as examples of natural (long-term persistent) and anthropogenic (short-term persistent) stressors, respectively. A new trait-based approach was applied to quantify functional diversity components and functional redundancy within the same multidimensional space, using metrics at the taxon and community levels. We found similar functional responses along natural and anthropogenic stress gradients. In both cases, the mean taxon functional richness and functional similarity between taxa increased with stress, whereas community functional richness and functional redundancy decreased. Despite the differences in evolutionary persistence, both chronic stressors act as strong nonrandom environmental filters, producing convergent functional responses. These results can improve our ability to predict functional effects of novel stressors at ecoloiical and evolutionary scales.

  2. CO2 laser preionisation

    NASA Technical Reports Server (NTRS)

    Spiers, Gary D.

    1991-01-01

    The final report for work done during the reporting period of January 25, 1990 to January 24, 1991 is presented. A literature survey was conducted to identify the required parameters for effective preionization in TEA CO2 lasers and the methods and techniques for characterizing preionizers are reviewed. A numerical model of the LP-140 cavity was used to determine the cause of the transverse mode stability improvement obtained when the cavity was lengthened. The measurement of the voltage and current discharge pulses on the LP-140 were obtained and their subsequent analysis resulted in an explanation for the low efficiency of the laser. An assortment of items relating to the development of high-voltage power supplies is also provided. A program for analyzing the frequency chirp data files obtained with the HP time and frequency analyzer is included. A program to calculate the theoretical LIMP chirp is also included and a comparison between experiment and theory is made. A program for calculating the CO2 linewidth and its dependence on gas composition and pressure is presented. The program also calculates the number of axial modes under the FWHM of the line for a given resonator length. A graphical plot of the results is plotted.

  3. Membraneless water filtration using CO2

    NASA Astrophysics Data System (ADS)

    Shin, Sangwoo; Shardt, Orest; Warren, Patrick; Stone, Howard

    2016-11-01

    Water purification technologies such as 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, or so-called diffusiophoresis. Due to the large diffusion potential built up by the dissociation of carbonic acid, colloidal particles move either away from or towards the gas-liquid interface depending on their surface charge. Our findings suggest a means to separate particles without membranes or filters, thus reducing operating and maintenance costs. Using the directed motion of particles induced by exposure to CO2, we demonstrate a scalable, continuous flow, membraneless particle filtration process that exhibits very low pressure drop and is essentially free from fouling.

  4. 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.

  5. Web-FACE: a new canopy free-air CO2 enrichment system for tall trees in mature forests.

    PubMed

    Pepin, Steeve; Körner, Christian

    2002-09-01

    The long-term responses of forests to atmospheric CO2 enrichment have been difficult to determine experimentally given the large scale and complex structure of their canopy. We have developed a CO2 exposure system that uses the free-air CO2 enrichment (FACE) approach but was designed for tall canopy trees. The system consists of a CO2-release system installed within the crown of adult trees using a 45-m tower crane, a CO2 monitoring system and an automated regulation system. Pure CO2 gas is released from a network of small tubes woven into the forest canopy (web-FACE), and CO2 is emitted from small laser-punched holes. The set point CO2 concentration ([CO2]) of 500 µmol mol(-1) is controlled by a pulse-width modulation routine that adjusts the rate of CO2 injection as a function of measured [CO2] in the canopy. CO2 consumption for the enrichment of 14 tall canopy trees was about 2 tons per day over the whole growing season. The seasonal daytime mean CO2 concentration was 520 µmol mol(-1). One-minute averages of CO2 measurements conducted at canopy height in the center of the CO2-enriched zone were within ±20% and ±10% of the target concentration for 76% and 47% of the exposure time, respectively. Despite the size of the canopy and the windy site conditions, performance values correspond to about 75% of that reported for conventional forest FACE with the added advantage of a much