WorldWideScience

Sample records for co2 isotopic analysis

  1. Isotopic characterisation of CO2 sources during regional pollution events using isotopic and radiocarbon analysis

    NARCIS (Netherlands)

    Zondervan, A; Meijer, HAJ

    1996-01-01

    At the station Kollumerwaard (The Netherlands), for monitoring tracers in the troposphere, air is sampled in 16 containers for off-line C-13, O-18 and C-14 isotopic analysis of CO2. The timing of the sampling is chosen such that CO2 variations correlating with pollutants like CO and CH4 are optimall

  2. Conditional CO2 flux analysis of a managed grassland with the aid of stable isotopes

    Directory of Open Access Journals (Sweden)

    N. Buchmann

    2009-04-01

    Full Text Available Short statured managed ecosystems, such as agricultural grasslands, exhibit high temporal changes in carbon dioxide assimilation and respiration fluxes for which measurements of the net CO2 flux, e.g. by using the eddy covariance (EC method, give only limited insight. We have therefore adopted a recently proposed concept for conditional EC flux analysis of forest to grasslands, in order to identify and quantify daytime sub-canopy respiration fluxes. To validate the concept, high frequency (≈5 Hz stable carbon isotope analyis of CO2 was used. We made eddy covariance measurements of CO2 and its isotopologues during four days in August 2007, using a novel quantum cascade laser absorption spectrometer, capable of high time resolution stable isotope analysis. The effects of a grass cut during the measurement period could be detected and resulted in a sub-canopy source conditional flux classification, for which the isotope composition of the CO2 could be confirmed to be of a respiration source. However, the conditional flux method did not work for an undisturbed grassland canopy. We attribute this to the flux measurement height that was chosen well above the roughness sublayer, where the natural isotopic tracer (δ13C of respiration was too well mixed with background air.

  3. Methods and limitations of 'clumped' CO2 isotope (Delta47) analysis by gas-source isotope ratio mass spectrometry.

    Science.gov (United States)

    Huntington, K W; Eiler, J M; Affek, H P; Guo, W; Bonifacie, M; Yeung, L Y; Thiagarajan, N; Passey, B; Tripati, A; Daëron, M; Came, R

    2009-09-01

    The geochemistry of multiply substituted isotopologues ('clumped-isotope' geochemistry) examines the abundances in natural materials of molecules, formula units or moieties that contain more than one rare isotope (e.g. (13)C(18)O(16)O, (18)O(18)O, (15)N(2), (13)C(18)O(16)O(2) (2-)). Such species form the basis of carbonate clumped-isotope thermometry and undergo distinctive fractionations during a variety of natural processes, but initial reports have provided few details of their analysis. In this study, we present detailed data and arguments regarding the theoretical and practical limits of precision, methods of standardization, instrument linearity and related issues for clumped-isotope analysis by dual-inlet gas-source isotope ratio mass spectrometry (IRMS). We demonstrate long-term stability and subtenth per mil precision in 47/44 ratios for counting systems consisting of a Faraday cup registered through a 10(12) ohm resistor on three Thermo-Finnigan 253 IRMS systems. Based on the analyses of heated CO(2) gases, which have a stochastic distribution of isotopes among possible isotopologues, we document and correct for (1) isotopic exchange among analyte CO(2) molecules and (2) subtle nonlinearity in the relationship between actual and measured 47/44 ratios. External precisions of approximately 0.01 per thousand are routinely achieved for measurements of the mass-47 anomaly (a measure mostly of the abundance anomaly of (13)C-(18)O bonds) and follow counting statistics. The present technical limit to precision intrinsic to our methods and instrumentation is approximately 5 parts per million (ppm), whereas precisions of measurements of heterogeneous natural materials are more typically approximately 10 ppm (both 1 s.e.). These correspond to errors in carbonate clumped-isotope thermometry of +/-1.2 degrees C and +/-2.4 degrees C, respectively.

  4. Stable isotope analysis of molecular oxygen from silicates and oxides using CO2 laser extraction

    Science.gov (United States)

    Perry, Eugene

    1996-01-01

    A laser-excited system for determination of the oxygen isotope composition of small quantities of silicate and oxide minerals was constructed and tested at JSC. This device is the first reported to use a commercially available helium cryostat to transfer and purify oxygen gas quantitatively within the system. The system uses oxygen gas instead of the conventional CO2 for mass spectrometer analyses. This modification of technique permits determination of all three stable oxygen isotopes, an essential requirement for oxygen isotope analysis of meteoritic material. Tests of the system included analysis of standard silicate materials NBS 28 and UWMG2 garnet, six SNC meteorites, and inclusions and chondrules from the Allende meteorite. Calibration with terrestrial standards was excellent. Meteorite values are close to published values and show no evidence of terrestrial oxygen contamination. The one limitation observed is that, in some runs on fine-grained SNC matrix material, sample results were affected by other samples in the sample holder within the reaction chamber. This reemphasizes the need for special precautions in dealing with fine-grained, reactive samples. Performance of the JSC instrument compares favorably with that of any other instrument currently producing published oxygen isotope data.

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

    Science.gov (United States)

    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

  6. Lasers utilizing CO2 isotopes

    Science.gov (United States)

    Pechenin, Iu. V.; Domanov, M. S.

    1980-08-01

    The emission spectra and power characteristics of CW (C-12)(O-16)2, (C-13)(O-16)2, (C-12)(O-16)(O-18)2 and (C-12)(O-18) lasers are investigated. Laser output power is found to depend equally on the proportion of carbon and oxygen isotopes in the active medium for all isotopes except the asymmetrical (C-12)(O-16)(O-18), in which maximum output power is four to five times less due to the doubling of emission lines and limited enrichment caused by recombination into (C-12)(O-16)2 and (C-12)(O-18)2 molecules during discharge. The unsaturated gain is observed to increase linearly with enrichment, with that of nonsymmetrical molecules half that of the symmetrical molecules, while the maximum power output is independent of enrichment.

  7. Carbon and oxygen isotope analysis of leaf biomass reveals contrasting photosynthetic responses to elevated CO2 near geologic vents in Yellowstone National Park

    Directory of Open Access Journals (Sweden)

    S. Sharma

    2008-09-01

    Full Text Available In this study we explore the use of natural CO2 emissions in Yellowstone National Park (YNP in Wyoming, USA to study responses of natural vegetation to elevated CO2 levels. Radiocarbon (14C analysis of leaf biomass from a conifer (Pinus contortus; lodgepole pine and an invasive, non-native herb (Linaria dalmatica; Dalmation toadflax was used to trace the inputs of vent CO2 and quantify assimilation-weighted CO2 concentrations experienced by individual plants near vents and in comparable locations with no geologic CO2 exposure. The carbon and oxygen isotopic composition and nitrogen percent of leaf biomass from the same plants was used to investigate photosynthetic responses of these plants to naturally elevated atmospheric CO2 concentrations. The coupled shifts in carbon and oxygen isotope values suggest that dalmation toadflax responded to elevated CO2 exposure by increasing stomatal conductance with no change in photosynthetic capacity and lodgepole pine apparently responded by decreasing stomatal conductance and photosynthetic capacity. Lodgepole pine saplings exposed to elevated levels of CO2 likewise had reduced leaf nitrogen concentrations compared to plants with no enhanced CO2 exposure, further suggesting that this widespread and dominant conifer down-regulated photosynthetic capacity under elevated CO2 levels near geologic vents.

  8. Carbon and oxygen isotope analysis of leaf biomass reveals contrasting photosynthetic responses to elevated CO2 near geologic vents in Yellowstone National Park

    Directory of Open Access Journals (Sweden)

    D. G. Williams

    2009-01-01

    Full Text Available In this study we explore the use of natural CO2 emissions in Yellowstone National Park (YNP in Wyoming, USA to study responses of natural vegetation to elevated CO2 levels. Radiocarbon (14C analysis of leaf biomass from a conifer (Pinus contortus; lodgepole pine and an invasive, non-native herb (Linaria dalmatica; Dalmation toadflax was used to trace the inputs of vent CO2 and quantify assimilation-weighted CO2 concentrations experienced by individual plants near vents and in comparable locations with no geologic CO2 exposure. The carbon and oxygen isotopic composition and nitrogen percent of leaf biomass from the same plants was used to investigate photosynthetic responses of these plants to naturally elevated atmospheric CO2 concentrations. The coupled shifts in carbon and oxygen isotope values suggest that dalmation toadflax responded to elevated CO2 exposure by increasing stomatal conductance with no change in photosynthetic capacity and lodgepole pine apparently responded by decreasing stomatal conductance and photosynthetic capacity. Lodgepole pine saplings exposed to elevated levels of CO2 likewise had reduced leaf nitrogen concentrations compared to plants with no enhanced CO2 exposure, further suggesting widespread and dominant conifer down-regulated photosynthetic capacity under elevated CO2 levels near geologic vents.

  9. An experimental set-up for carbon isotopic analysis of atmospheric CO2 and an example of ecosystem response during solar eclipse 2010

    Indian Academy of Sciences (India)

    Tania Guha; Prosenjit Ghosh

    2013-06-01

    We present here, an experimental set-up developed for the first time in India for the determination of mixing ratio and carbon isotopic ratio of air-CO2. The set-up includes traps for collection and extraction of CO2 from air samples using cryogenic procedures, followed by the measurement of CO2 mixing ratio using an MKS Baratron gauge and analysis of isotopic ratios using the dual inlet peripheral of a high sensitivity isotope ratio mass spectrometer (IRMS) MAT 253. The internal reproducibility (precision) for the 13C measurement is established based on repeat analyses of CO2 ± 0.03‰. The set-up is calibrated with international carbonate and air-CO2 standards. An in-house air-CO2 mixture, `OASIS AIRMIX' is prepared mixing CO2 from a high purity cylinder with O2 and N2 and an aliquot of this mixture is routinely analyzed together with the air samples. The external reproducibility for the measurement of the CO2 mixing ratio and carbon isotopic ratios are ± 7 ( = 169) mol·mol−1 and ± 0.05 ( = 169)‰ based on the mean of the difference between two aliquots of reference air mixture analyzed during daily operation carried out during November 2009–December 2011. The correction due to the isobaric interference of N2O on air-CO2 samples is determined separately by analyzing mixture of CO2 (of known isotopic composition) and N2O in varying proportions. A +0.2‰ correction in the 13C value for a N2O concentration of 329 ppb is determined. As an application, we present results from an experiment conducted during solar eclipse of 2010. The isotopic ratio in CO2 and the carbon dioxide mixing ratio in the air samples collected during the event are different from neighbouring samples, suggesting the role of atmospheric inversion in trapping the emitted CO2 from the urban atmosphere during the eclipse.

  10. Temperature and atmospheric CO2 concentration estimates through the PETM using triple oxygen isotope analysis of mammalian bioapatite

    Science.gov (United States)

    Gehler, Alexander; Gingerich, Philip D.; Pack, Andreas

    2016-07-01

    The Paleocene-Eocene Thermal Maximum (PETM) is a remarkable climatic and environmental event that occurred 56 Ma ago and has importance for understanding possible future climate change. The Paleocene-Eocene transition is marked by a rapid temperature rise contemporaneous with a large negative carbon isotope excursion (CIE). Both the temperature and the isotopic excursion are well-documented by terrestrial and marine proxies. The CIE was the result of a massive release of carbon into the atmosphere. However, the carbon source and quantities of CO2 and CH4 greenhouse gases that contributed to global warming are poorly constrained and highly debated. Here we combine an established oxygen isotope paleothermometer with a newly developed triple oxygen isotope paleo-CO2 barometer. We attempt to quantify the source of greenhouse gases released during the Paleocene-Eocene transition by analyzing bioapatite of terrestrial mammals. Our results are consistent with previous estimates of PETM temperature change and suggest that not only CO2 but also massive release of seabed methane was the driver for CIE and PETM.

  11. Long-term field performance of a tunable diode laser absorption spectrometer for analysis of carbon isotopes of CO2 in forest air

    Directory of Open Access Journals (Sweden)

    D. R. Bowling

    2008-09-01

    Full Text Available Tunable diode laser absorption spectrometry (TDLAS is gaining in popularity for measuring the mole fraction [CO2] and stable isotopic composition (δ13C of carbon dioxide (CO2 in air in studies of biosphere-atmosphere gas exchange. Here we present a detailed examination of the performance of a commercially-available TDLAS located in a high-altitude subalpine coniferous forest (the Niwot Ridge AmeriFlux site, providing the first multi-year analysis of TDLAS instrument performance for measuring CO2 isotopes in the field. Air was sampled from five to nine vertical locations in and above the forest canopy every ten minutes for 2.4 years. A variety of methods were used to assess instrument performance. Measurement of two compressed air cylinders that were in place over the entire study establish the long-term field precision of 0.2 μmol mol−1 for [CO2] and 0.35‰ for δ13C, but after fixing several problems the isotope precision improved to 0.2permil (over the last several months. The TDLAS provided detail on variability of δ13C of atmospheric CO2 that was not represented in weekly flask samples, as well as information regarding the influence of large-scale (regional seasonal cycle and local forest processes on [CO2] and δ13C of CO2. There were also clear growing season and winter differences in the relative contributions of photosynthesis and respiration on the [CO2] and δ13C of forest air.

  12. Long-term field performance of a tunable diode laser absorption spectrometer for analysis of carbon isotopes of CO2 in forest air

    Directory of Open Access Journals (Sweden)

    J. W. C. White

    2008-05-01

    Full Text Available Tunable diode laser absorption spectrometry (TDLAS is gaining in popularity for measuring the mole fraction [CO2] and stable isotopic composition (δ13C of carbon dioxide (CO2 in air in studies of biosphere-atmosphere gas exchange. Here we present a detailed examination of the performance of a commercially-available TDLAS located in a high-altitude subalpine coniferous forest (the Niwot Ridge AmeriFlux site, providing the first multi-year analysis of TDLAS instrument performance for measuring CO2 isotopes in the field. Air was sampled from five to nine vertical locations in and above the forest canopy every ten minutes for 2.4 years. A variety of methods were used to assess instrument performance. Measurement of two compressed air cylinders that were in place over the entire study establish the long-term field precision of 0.2 μmol mol−1 for [CO2] and 0.35‰ for δ13C, but after fixing several problems the isotope precision improved to 0.2‰ (over the last several months. The TDLAS provided detail on variability of δ13C of atmospheric CO2 that was not represented in weekly flask samples, as well as information regarding the influence of large-scale (regional seasonal cycle and local forest processes on [CO2] and δ13C of CO2. There were also clear growing season and winter differences in the relative contributions of photosynthesis and respiration on the [CO2] and δ13C of forest air.

  13. The carbon isotope composition of atmospheric CO 2 in Paris

    Science.gov (United States)

    Widory, David; Javoy, Marc

    2003-10-01

    One characteristic of air pollution in the urban environment is high CO 2 concentrations resulting from human activities. Determining the relative contributions of the different CO 2 sources can be addressed simply and elegantly by combining isotope and concentration measurements. Using this approach on atmospheric CO 2 samples collected in Paris, its suburbs and the open country provides fairly accurate conclusions. Our results show that air pollution within the first few metres above ground results basically from binary mixtures among which road traffic is the main contributor and, in particular, vehicles using unleaded gasoline (˜90% of the total). Heating sources, which account for 50% of the CO 2 input below the atmospheric inversion level, and vehicles using diesel contribute very little. Human respiration has a recognisable signature at street level under certain circumstances. The combined isotope and concentration analysis provides a sensitive tracer of local variations, even detecting the occasional prevalence of human respiration and the onset of actions in which natural gas is burnt. It also detects surprising inlets of 'clean air' (CO 2-wise) in the very centre of the city.

  14. Diode laser absorption spectrometry for (CO2)-C-13/(CO2)-C-12 isotope ratio analysis : Investigation on precision and accuracy levels

    NARCIS (Netherlands)

    Castrillo, A; Casa, G; Kerstel, E; Gianfrani, L

    2005-01-01

    Near-infrared laser spectroscopy is used to measure the C-13/C-12 isotope abundance ratio in gas phase carbon dioxide. The spectrometer, developed expressly for field applications, is based on a 2 mu m distributed feedback diode laser in combination with sensitive wavelength modulation detection. It

  15. Diode laser absorption spectrometry for (CO2)-C-13/(CO2)-C-12 isotope ratio analysis : Investigation on precision and accuracy levels

    NARCIS (Netherlands)

    Castrillo, A; Casa, G; Kerstel, E; Gianfrani, L

    2005-01-01

    Near-infrared laser spectroscopy is used to measure the C-13/C-12 isotope abundance ratio in gas phase carbon dioxide. The spectrometer, developed expressly for field applications, is based on a 2 mu m distributed feedback diode laser in combination with sensitive wavelength modulation detection. It

  16. Towards absolute laser spectroscopic CO2 isotope ratio measurements

    Science.gov (United States)

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

    2017-04-01

    Knowledge of isotope composition of carbon dioxide (CO2) in the atmosphere is necessary to identify sources and sinks of this key greenhouse gas. In the last years, laser spectroscopic techniques such as cavity ring-down spectroscopy (CRDS) and tunable diode laser absorption spectroscopy (TDLAS) have been shown to perform accurate isotope ratio measurements for CO2 and other gases like water vapour (H2O) [1,2]. Typically, isotope ratios are reported in literature referring to reference materials provided by e.g. the International Atomic Energy Agency (IAEA). However, there could be some benefit if field deployable absolute isotope ratio measurement methods were developed to address issues such as exhausted reference material like the Pee Dee Belemnite (PDB) standard. Absolute isotope ratio measurements would be particularly important for situations where reference materials do not even exist. Here, we present CRDS and TDLAS-based absolute isotope ratios (13C/12C ) in atmospheric CO2. We demonstrate the capabilities of the used methods by measuring CO2 isotope ratios in gas standards. We compare our results to values reported for the isotope certified gas standards. Guide to the expression of uncertainty in measurement (GUM) compliant uncertainty budgets on the CRDS and TDLAS absolute isotope ratio measurements are presented, and traceability is addressed. We outline the current impediments in realizing high accuracy absolute isotope ratio measurements using laser spectroscopic methods, propose solutions and the way forward. Acknowledgement Parts of this work have been carried out within the European Metrology Research Programme (EMRP) ENV52 project-HIGHGAS. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. References [1] B. Kühnreich, S. Wagner, J. C. Habig,·O. Möhler, H. Saathoff, V. Ebert, Appl. Phys. B 119:177-187 (2015). [2] E. Kerstel, L. Gianfrani, Appl. Phys. B 92, 439-449 (2008).

  17. Halloysite Nanotubes Capturing Isotope Selective Atmospheric CO2

    OpenAIRE

    Subhra Jana; Sankar Das; Chiranjit Ghosh; Abhijit Maity; Manik Pradhan

    2015-01-01

    With the aim to capture and subsequent selective trapping of CO2, a nanocomposite has been developed through selective modification of the outer surface of the halloysite nanotubes (HNTs) with an organosilane to make the nanocomposite a novel solid-phase adsorbent to adsorb CO2 from the atmosphere at standard ambient temperature and pressure. The preferential adsorption of three major abundant isotopes of CO2 (12C16O2, 13C16O2, and 12C16O18O) from the ambient air by amine functionalized HNTs ...

  18. Halloysite Nanotubes Capturing Isotope Selective Atmospheric CO2

    Science.gov (United States)

    Jana, Subhra; Das, Sankar; Ghosh, Chiranjit; Maity, Abhijit; Pradhan, Manik

    2015-01-01

    With the aim to capture and subsequent selective trapping of CO2, a nanocomposite has been developed through selective modification of the outer surface of the halloysite nanotubes (HNTs) with an organosilane to make the nanocomposite a novel solid-phase adsorbent to adsorb CO2 from the atmosphere at standard ambient temperature and pressure. The preferential adsorption of three major abundant isotopes of CO2 (12C16O2, 13C16O2, and 12C16O18O) from the ambient air by amine functionalized HNTs has been explored using an optical cavity-enhanced integrated cavity output spectroscopy. CO2 adsorption/desorption cycling measurements demonstrate that the adsorbent can be regenerated at relatively low temperature and thus, recycled repeatedly to capture atmospheric CO2. The amine grafted halloysite shows excellent stability even in oxidative environments and has high efficacy of CO2 capture, introducing a new route to the adsorption of isotope selective atmospheric CO2. PMID:25736700

  19. Oxygen isotopic signature of CO2 from combustion processes

    Directory of Open Access Journals (Sweden)

    W. A. Brand

    2011-02-01

    Full Text Available For a comprehensive understanding of the global carbon cycle precise knowledge of all processes is necessary. Stable isotope (13C and 18O abundances provide information for the qualification and the quantification of the diverse source and sink processes. This study focuses on the δ18O signature of CO2 from combustion processes, which are widely present both naturally (wild fires, and human induced (fossil fuel combustion, biomass burning in the carbon cycle. All these combustion processes use atmospheric oxygen, of which the isotopic signature is assumed to be constant with time throughout the whole atmosphere. The combustion is generally presumed to take place at high temperatures, thus minimizing isotopic fractionation. Therefore it is generally supposed that the 18O signature of the produced CO2 is equal to that of the atmospheric oxygen. This study, however, reveals that the situation is much more complicated and that important fractionation effects do occur. From laboratory studies fractionation effects on the order of up to 26%permil; became obvious in the derived CO2 from combustion of different kinds of material, a clear differentiation of about 7‰ was also found in car exhausts which were sampled directly under ambient atmospheric conditions. We investigated a wide range of materials (both different raw materials and similar materials with different inherent 18O signature, sample geometries (e.g. texture and surface-volume ratios and combustion circumstances. We found that the main factor influencing the specific isotopic signatures of the combustion-derived CO2 and of the concomitantly released oxygen-containing side products, is the case-specific rate of combustion. This points firmly into the direction of (diffusive transport of oxygen to the reaction zone as the cause of the isotope fractionation. The original total 18O signature of the material appeared to have little influence, however, a contribution of specific bio

  20. A new approach to quantifying internal diffusion resistances and CO2 isotope exchange in leaves

    Science.gov (United States)

    West, Jason; Ogée, Jérôme; Burlett, Régis; Gimeno, Teresa; Genty, Bernard; Jones, Samuel; Wohl, Steven; Bosc, Alexandre; Wingate, Lisa

    2016-04-01

    The oxygen isotopic composition (δ18O) of atmospheric CO2 can constrain the global CO2 budget at a range of scales, offering the potential to partition net CO2 exchanges into their component gross fluxes and provide insights to linkages between C and water cycles. However, there are significant limitations to utilizing the δ18O of CO2 to constrain C budgets because of uncertainties associated with the isotopic exchange of CO2 with terrestrial water pools. Leaf water in particular represents a critical pool with ongoing debates about its enrichment in heavy isotopes during transpiration and the hydration of CO2 and its oxygen isotope exchange with this pool. Isotopic heterogeneity of the leaf water, the spatial distribution and activity of carbonic anhydrase (CA) within leaves, and resistance to diffusion of CO2 from the substomatal cavity to chloroplasts are all key components with important uncertainties. Better constraints on these would significantly improve our ability to understand and model the global C budget as well as yield insights to fundamental aspects of leaf physiology. We report results using a new measurement system that permits the simultaneous measurement of the 13C and 18O composition of CO2 and the 18O isotopic composition of leaf transpiration. As this new approach permits rapid alteration of the isotopic composition of gases interacting with the leaf, key model parameters can be derived directly and simultaneously. Hence, our approach dos not rely on separate measurements shifted in time from the gas exchange measurements or that may not quantify the relevant scale of heterogeneity (e.g., CA enzyme assays or bulk leaf water extraction and analysis). In particular, this new method explicitly distinguishes the leaf mesophyll resistance to CO2 transport relevant for photosynthesis from the resistance required for interpreting the δ18O of CO2 and allows us to derive other relevant parameters directly. This new measurement system and modeling

  1. Determining CO2 storage potential during miscible CO2 enhanced oil recovery: Noble gas and stable isotope tracers

    Science.gov (United States)

    Shelton, Jenna L.; McIntosh, Jennifer C.; Hunt, Andrew; Beebe, Thomas L; Parker, Andrew D; Warwick, Peter; Drake, Ronald; McCray, John E.

    2016-01-01

    Rising atmospheric carbon dioxide (CO2) concentrations are fueling anthropogenic climate change. Geologic sequestration of anthropogenic CO2 in depleted oil reservoirs is one option for reducing CO2 emissions to the atmosphere while enhancing oil recovery. In order to evaluate the feasibility of using enhanced oil recovery (EOR) sites in the United States for permanent CO2 storage, an active multi-stage miscible CO2flooding project in the Permian Basin (North Ward Estes Field, near Wickett, Texas) was investigated. In addition, two major natural CO2 reservoirs in the southeastern Paradox Basin (McElmo Dome and Doe Canyon) were also investigated as they provide CO2 for EOR operations in the Permian Basin. Produced gas and water were collected from three different CO2 flooding phases (with different start dates) within the North Ward Estes Field to evaluate possible CO2 storage mechanisms and amounts of total CO2retention. McElmo Dome and Doe Canyon were sampled for produced gas to determine the noble gas and stable isotope signature of the original injected EOR gas and to confirm the source of this naturally-occurring CO2. As expected, the natural CO2produced from McElmo Dome and Doe Canyon is a mix of mantle and crustal sources. When comparing CO2 injection and production rates for the CO2 floods in the North Ward Estes Field, it appears that CO2 retention in the reservoir decreased over the course of the three injections, retaining 39%, 49% and 61% of the injected CO2 for the 2008, 2010, and 2013 projects, respectively, characteristic of maturing CO2 miscible flood projects. Noble gas isotopic composition of the injected and produced gas for the flood projects suggest no active fractionation, while δ13CCO2 values suggest no active CO2dissolution into formation water, or mineralization. CO2 volumes capable of dissolving in residual formation fluids were also estimated along with the potential to store pure-phase supercritical CO2. Using a combination

  2. Using a laser-based CO2 carbon isotope analyser to investigate gas transfer in geological media

    Science.gov (United States)

    Guillon, S.; Pili, E.; Agrinier, P.

    2012-05-01

    CO2 stable carbon isotopes are very attractive in environmental research to investigate both natural and anthropogenic carbon sources. Laser-based CO2 carbon isotope analysis provides continuous measurement at high temporal resolution and is a promising alternative to isotope ratio mass spectrometry (IRMS). We performed a thorough assessment of a commercially available CO2 Carbon Isotope Analyser (CCIA DLT-100, Los Gatos Research) that allows in situ measurement of δ 13C in CO2. Using a set of reference gases of known CO2 concentration and carbon isotopic composition, we evaluated the precision, long-term stability, temperature sensitivity and concentration dependence of the analyser. Despite good precision calculated from Allan variance (5.0 ppm for CO2 concentration, and 0.05 ‰ for δ 13C at 60 s averaging), real performances are altered by two main sources of error: temperature sensitivity and dependence of δ 13C on CO2 concentration. Data processing is required to correct for these errors. Following application of these corrections, we achieve an accuracy of 8.7 ppm for CO2 concentration and 1.3 ‰ for δ 13C, which is worse compared to mass spectrometry performance, but still allowing field applications. With this portable analyser we measured CO2 flux degassed from rock in an underground tunnel. The obtained carbon isotopic composition agrees with IRMS measurement, and can be used to identify the carbon source.

  3. Stable isotope ratios of atmospheric CO_{2} and CH_{4} over Siberia measured at ZOTTO

    Science.gov (United States)

    Timokhina, Anastasiya; Prokushkin, Anatily; Lavric, Jost; Heimann, Martin

    2016-04-01

    The boreal and arctic zones of Siberia housing the large amounts of carbon stored in the living biomass of forests and wetlands, as well as in soils and specifically permafrost, play a crucial role in earth's global carbon cycle. The long-term studies of greenhouse gases (GHG) concentrations are important instruments to analyze the response of these systems to climate warming. In parallel to GHG observations, the measurements of their stable isotopic composition can provide useful information for distinguishing contribution of individual GHG source to their atmospheric variations, since each source has its own isotopic signature. In this study we report first results of laboratory analyses of the CO2 and CH4 concentrations, the stable isotope ratio of δ13C-CO2, δ18O-CO2, δ13C-CH4, δD-CH4 measured in one-liter glass flasks which were obtained from 301 height of ZOTTO (Zotino Tall Tower Observatory, near 60° N, 90° E, about 20 km west of the Yenisei River) during 2008 - 2013 and 2010 - 2013 for stable isotope composition of CO2 and CH4. The magnitudes of δ13C-CO2 and δ18O-CO2 in a seasonal cycle are -1.4±0.1‰ (-7.6 - -9.0‰) and -2.2±0.2‰ (-0.1 - -2.3‰), respectively. The δ13C-CO2 seasonal pattern opposes the CO2 concentrations, with a gradual enrichment in heavy isotope occurring during May - July, reflecting its discrimination in photosynthesis, and further depletion in August - September as photosynthetic activity decreases comparatively to ecosystem respiration. Relationship between the CO2 concentrations and respective δ13C-CO2 (Keeling plot) reveals isotopic source signature for growing season (May - September) -27.3±1.4‰ and -30.4±2.5‰ for winter (January - March). The behavior of δ18O-CO2 associated with both high photosynthetic rate in the June (enrichment of atmospheric CO2 by 18O as consequence of CO2 equilibrium with "heavy" leaf water) and respiratory activity of forest floor in June - October (depletion of respired CO2 by 18O

  4. Near Surface CO2 Triple Oxygen Isotope Composition

    Directory of Open Access Journals (Sweden)

    Sasadhar Mahata

    2016-02-01

    Full Text Available The isotopic composition of carbon dioxide in the atmosphere is a powerful tool for constraining its sources and sinks. In particular, the 17O oxygen anomaly [Δ17O = 1000 × ln(1 + δ17O/1000 - 0.516 × 1000 × ln(1 + δ18O/1000], with a value > 0.5‰ produced in the middle atmosphere, provides an ideal tool for probing the exchange of carbon dioxide between the biosphere/hydrosphere and atmosphere. The biosphere/hydrosphere and anthropogenic emissions give values ≤ 0.3‰. Therefore, any anomaly in near surface CO2 would reflect the balance between stratospheric input and exchange with the aforementioned surface sources. We have analyzed Δ17O values of CO2 separated from air samples collected in Taipei, Taiwan, located in the western Pacific region. The obtained mean anomaly is 0.42 ± 0.14‰ (1-σ standard deviation, in good agreement with model prediction and a published decadal record. Apart from typically used δ13C and δ18O values, the Δ17O value could provide an additional tracer for constraining the carbon cycle.

  5. Identifying the Presence of AMD-Derived Soil CO2 in Field Investigations Using Isotope Ratios

    Directory of Open Access Journals (Sweden)

    Kwame Awuah-Offei

    2016-03-01

    Full Text Available Recent incidents of hazardous accumulations of CO2 in homes on or adjacent to reclaimed mine land have been shown to be linked to neutralization reactions between acidic mine drainage and carbonate material. An efficient and economic method is necessary to identify the presence of acid mine drainage- (AMD- derived CO2 on reclaimed mine land, prior to construction. One approach to identify the presence of AMD-derived CO2 is to characterize stable carbon isotope ratios of soil CO2. To do so, a viable method is necessary to acquire soil gas samples for isotope ratio analysis. This paper presents preliminary investigations of the effectiveness of two methods of acquiring gas samples (sampling during soil flux measurements and using slam bar for isotope analysis. The results indicate that direct soil gas sampling is cheaper and provides better results. Neither method is adequate without accounting for temporal effects due to changing gas transport mechanisms. These results have significant implications for safe post-mining land uses and future investigations of leakages from geologic carbon sequestration sites.

  6. High precision dual-inlet IRMS measurements of the stable isotopes of CO2 and the N2O/CO2 ratio from polar ice core samples

    Directory of Open Access Journals (Sweden)

    T. K. Bauska

    2014-07-01

    Full Text Available An important constraint on mechanisms of past carbon cycle variability is provided by the stable isotopic composition of carbon in atmospheric carbon dioxide (δ13C-CO2 trapped in polar ice cores, but obtaining very precise measurements has proven to be a significant analytical challenge. Here we describe a new technique to determine the δ13C of CO2 at exceptional precision, as well as measuring the CO2 and N2O mixing ratios. In this method, ancient air is extracted from relatively large ice samples (~ 400 grams with a dry-extraction "ice-grater" device. The liberated air is cryogenically purified to a CO2 and N2O mixture and analyzed with a micro-volume equipped dual-inlet IRMS (Thermo MAT 253. The reproducibility of the method, based on replicate analysis of ice core samples, is 0.02‰ for δ13C-CO2 and 2 ppm and 4 ppb for the CO2 and N2O mixing ratios, respectively (1-sigma pooled standard deviation. Our experiments show that minimizing water vapor pressure in the extraction vessel by housing the grating apparatus in a ultra-low temperature freezer (−60 °C improves the precision and decreases the experimental blank of the method. We describe techniques for accurate calibration of small samples and the application of a mass spectrometric method based on source fragmentation for reconstructing the N2O history of the atmosphere. The oxygen isotopic composition of CO2 is also investigated, confirming previous observations of oxygen exchange between gaseous CO2 and solid H2O within the ice archive. These data offer a possible constraint on oxygen isotopic fractionation during H2O and CO2 exchange below the H2O bulk melting temperature.

  7. Deep ocean ventilation, carbon isotopes, marine sedimentation and the deglacial CO2 rise

    Directory of Open Access Journals (Sweden)

    C. Heinze

    2011-07-01

    Full Text Available The link between the atmospheric CO2 level and the ventilation state of the deep ocean is an important building block of the key hypotheses put forth to explain glacial-interglacial CO2 fluctuations. In this study, we systematically examine the sensitivity of atmospheric CO2 and its carbon isotope composition to changes in deep ocean ventilation, the ocean carbon pumps, and sediment formation in a global 3-D ocean-sediment carbon cycle model. Our results provide support for the hypothesis that a break up of Southern Ocean stratification and invigorated deep ocean ventilation were the dominant drivers for the early deglacial CO2 rise of ~35 ppm between the Last Glacial Maximum and 14.6 ka BP. Another rise of 10 ppm until the end of the Holocene is attributed to carbonate compensation responding to the early deglacial change in ocean circulation. Our reasoning is based on a multi-proxy analysis which indicates that an acceleration of deep ocean ventilation during early deglaciation is not only consistent with recorded atmospheric CO2 but also with the reconstructed opal sedimentation peak in the Southern Ocean at around 16 ka BP, the record of atmospheric δ13CCO2, and the reconstructed changes in the Pacific CaCO3 saturation horizon.

  8. Carbon isotopic characterization of cider CO2 by isotope ratio mass spectrometry: a tool for quality and authenticity assessment.

    Science.gov (United States)

    Cabañero, Ana I; Rupérez, Mercedes

    2012-08-30

    The cider market is an important sector of the food industry in certain regions. Adulteration of cider can happen in several ways: for example, by the addition of sugar, or of exogenous CO(2) to certain types of cider. Because such practices are not allowed by either Spanish legislation or the legislation of other countries, it is essential to study possible methods to detect these unauthorized practices. For this purpose a procedure was required to study the stable carbon isotopic composition of CO(2) in cider. A liquid sample of cider was transferred to a vial and CO(2) from the headspace of the vial was analyzed using a peripheral device interfaced to an isotope ratio mass spectrometer. Separation of the CO(2) from water and ethanol was achieved using a gas chromatography column located in the peripheral device. The values for repeatability and reproducibility obtained indicated the robustness of the method, which is required for routine analysis. Ninety cider samples from various origins were analyzed, most of which showed a (13)C content consistent with the declared origin. The δ(13)C ranged from -24.80‰ to -20.89‰ for ciders with endogenous carbon dioxide (-22.74 ± 0.79‰) and -37.13‰ to -26.00‰ if industrial CO(2) was added. Several samples were also suspected of C4 sugar addition prior to the fermentation. A fast, accurate and simple method for cider adulteration detection was developed. The addition of exogenous CO(2) as well as C4 sugar addition prior to fermentation could be detected. The method showed advantages over existing methods in term of simplicity (no sample preparation and very long-term stability of the sample), speed (less than 10 min/sample) and precision ((r ≤0.32 and R ≤0.42). Copyright © 2012 John Wiley & Sons, Ltd.

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

    Science.gov (United States)

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

    2016-07-19

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

  10. Altered Carbon Isotope Discrimination of C3 Plants Under Very High pCO2 Levels

    Science.gov (United States)

    Panetta, R. J.; Schubert, B.; Jahren, H.

    2009-12-01

    . We speculate that this decreased variability may reflect fundamentally altered patterns of net carbon uptake, which then affect net isotopic fractionation. A.H. Jahren, N.C. Arens and S.A. Harbeson, 2008. Prediction of atmospheric δ13CO2 using fossil plant tissues. Reviews of Geophysics, 46/2006RG0002. H. Poorter and E. Garnier, 1996. Plant growth analysis: an evaluation of experimental design and computational methods. Journal of Experimental Botany, 47/1343-1351.

  11. Intracellular carbon isotope distributions of continuous-culture Allochromatium vinosum grown on acetate vs. CO2.

    Science.gov (United States)

    Tang, T.; Mohr, W.; Sattin, S.; Rogers, D.; Girguis, P. R.; Pearson, A.

    2016-02-01

    Sulfur oxidizing bacteria are commonly observed in various aquatic environments, which use reduced sulfur compounds as electron donors to complete the carbon metabolism. Their carbon isotope fractionations during biosynthesis can be preserved in the fossil records. Here we grew a model sulfur oxidizing bacterium, Allochromatium vinosum, in two mode of continuous culture. One of the A. vinosum culture was grown autotrophically with CO2 as the carbon source; while the other one was grown heterotrophically on acetate. A novel protein isotope fingerprinting analysis was applied combining proteomics and protein isotope analysis together, which indicates no isotope fractionation among individual proteins, whereas the bulk protein d13C relative to bulk biomass were substantially different between autotrophic and heterotrophic cells. The same trend was also observed in d13C values of bulk amino acids, fatty acids and nucleic acids. The observed difference in major classes of organic compounds may result from the difference in biosynthetic pathways of autotrophic and heterotrophic cells. A closer look into d13C value of individual amino acids and fatty acids provides us further evidence to identify isotopic response to key reactions of central carbon metabolism as revealed by proteomic analysis. Our work suggests that we can decipher diverse microbial carbon metabolisms by combining proteomics with compound specific analysis of major classes of organic compounds.

  12. Application of carbon isotope for discriminating sources of soil CO2 in karst area, Guizhou

    Institute of Scientific and Technical Information of China (English)

    黎廷宇; 王世杰

    2001-01-01

    Using carbon isotope of soil CO2 this paper discussed the sources of soil CO2 in karst area, Guizhou Province, China. Oxidation-decomposition of organic matter, respiration of plant root and activity of microbe are thought to be the major sources of soil CO2. However, in karst area, the contribution of dissolution of underlying carbonate rock to soil CO2 should be considered as in acidic environment. Atmospheric CO2 is the major composition of soil CO2 in surface layer of soil profiles and its proportion in soil CO2 decreases with increase of soil depth. CO2 produced by dissolution of carbonate rock contributes 34%-46% to soil CO2 below the depth of 10cm in the studied soil profiles covered by grass.

  13. CO2-water-mineral reactions during CO2 leakage into glauconitic sands: geochemical and isotopic monitoring of batch experiments

    Science.gov (United States)

    Humez, P.; Lions, J.; Lagneau, V.; Negrel, Ph.

    2012-04-01

    The assessment of environmental impacts of carbon dioxide geological storage requires the investigation of the potential CO2 leakages into fresh groundwater reserves. The Albian aquifer of the Paris Basin was chosen as a case of study because i) the Paris Basin contains deep saline Jurassic and Triassic aquifers identified as targets by the French national program of CO2 geological storage and ii) the Albian aquifer is a deep freshwater resource of strategic national importance, above the Jurassic and Triassic formations. An experimental and a geochemical modelling approach were carried out in order to better understand the rock-water-CO2 interactions with two main objectives: to assess the evolution of the chemistry of the formation water and of the mineralogy of the solid phase during the interaction and to design a monitoring program for freshwater resources. The main focus is to select and develop suitable indirect indicators of the presence of CO2 in the aquifer. We present here the experimental results, which combines both major and trace elements and isotopic tools, some of them new in the CCS field. Batch reactors with a liquid/solid ratio of 10 made of appropriate materials (PTFE, stainless steel) were equipped with simultaneous controls on several parameters (pH measurement, gas phase composition, pressure, tightness…) after CO2 injection (PCO2= 2 bar; room temperature). Ten reactors were run simultaneously, over pre-determined durations of CO2-water-rock interaction (1, 7, 15 and 30 days). During the batch experiment, we observed major changes in several chemical parameters due to the CO2 injection. A sharp drop in pH from 6.6 to 4.9 was noticeable, immediately after the injection, due to CO2 dissolution in the water phase. Alkalinity varies from 1.3 mmol.L-1 in the initial water to 2.0 mmol.L-1 at the end of the 1-month experiment. Four types of ion behaviors are observed: (1) calcium, silicon and magnesium concentrations increase during the 1-month

  14. Carbon stable isotopic composition of karst soil CO2 in central Guizhou, China

    Institute of Scientific and Technical Information of China (English)

    郑乐平

    1999-01-01

    The δ13 values of soil CO2 are less than that of atmosphere CO2 in the karst area. On the soil-air interface, the δ13 vlaues of soil CO2 decrease with the increase in soil depth; below the soil-air interface, the δ13C values of soil CO2 are invariable. The type of vegetation on the land surface has an influence on the δ13C values of soil CO2 Due to the activity of soil microbes, the δ13C values of soil CO2 are variable with seasonal change in grass. Isotopic tracer indicates that atmosphere CO2 has a great deal of contribution to soil CO2 at the lower parts of soil profile.

  15. Novel applications of carbon isotopes in atmospheric CO2: what can atmospheric measurements teach us about processes in the biosphere?

    Directory of Open Access Journals (Sweden)

    J. W. C. White

    2011-05-01

    Full Text Available Conventionally, measurements of carbon isotopes in atmospheric CO2 (δ13CO2 have been used to partition fluxes between terrestrial and ocean carbon pools. However, novel analytical approaches combined with an increase in the spatial extent and frequency of δ13CO2 measurements allow us to conduct a global analysis of δ13CO2 variability to infer the isotopic composition of source CO2 to the atmosphere (δs. This global analysis yields coherent seasonal patterns of isotopic enrichment. Our results indicate that seasonal values of δs are more highly correlated with vapor pressure deficit (r=0.404 than relative humidity (r=0.149. We then evaluate two widely used stomatal conductance models and determine that Leuning Model, which is primarily driven by vapor pressure deficit is more effective globally at predicting δs (RMSE = 1.7 ‰ than the Ball-Berry model, which is driven by relative humidity (RMSE = 2.8 ‰. Thus stomatal conductance on a global scale may be more sensitive to changes in vapor pressure deficit than relative humidity. This approach highlights a new application of using δ13CO2 measurements to test global models.

  16. CO2-dependent carbon isotope fractionation in dinoflagellates relates to their inorganic carbon fluxes

    NARCIS (Netherlands)

    Hoins, M.; Eberlein, T.; Van de Waal, D.B.; Sluijs, A.|info:eu-repo/dai/nl/311474748; Reichart, G.-J.|info:eu-repo/dai/nl/165599081; Rost, B.

    2016-01-01

    Carbon isotope fractionation (εp) between the inorganic carbon source and organic matter has been proposed to be a function of pCO2. To understand the CO2-dependency of εp and species-specific differences therein, inorganic carbon fluxes in the four dinoflagellate species Alexandrium fundyense, Scri

  17. Concentration and stable carbon isotopic composition of CO2 in cave air of Postojnska jama, Slovenia

    Directory of Open Access Journals (Sweden)

    Magda Mandic

    2013-09-01

    Full Text Available Partial pressure of CO2 (pCO2 and its isotopic composition (δ13CairCO2 were measured in Postojnska jama, Slovenia, at 10 locations inside the cave and outside the cave during a one-year period. At all interior locations the pCO2 was higher and δ13CairCO2 lower than in the outside atmosphere. Strong seasonal fluctuations in both parameters were observed at locations deeper in the cave, which are isolated from the cave air circulation. By using a binary mixing model of two sources of CO2, one of them being the atmospheric CO2, we show that the excess of CO2 in the cave air has a δ13C value of -23.3 ± 0.7 ‰, in reasonable agreement with the previously measured soil-CO2 δ13C values. The stable isotope data suggest that soil CO2 is brought to the cave by drip water.

  18. Partitioning CO2 production with stable carbon isotopes in a peatland ecosystem

    Science.gov (United States)

    Corbett, J.; Chanton, J.; tfaily, M. M.; Cooper, W. T.; Burdige, D. J.; Glaser, P. H.

    2011-12-01

    We developed an isotope mass-balance model to predict the percent of CO2 formed from either organic-matter fermentation or methanogenesis using pore water δ13C-CO2 and δ13C-CH4 in a peatland ecosystem. Our second objective was to determine percent CH4 loss using CO2 and CH4 concentrations and the predicted percent of CO2 from methanogenesis. The assumption that methanogenesis produces equimolar amounts of CH4 and CO2 and multiple field and incubation measurements that show higher concentrations of CO2 indicate that organic-matter fermentation is an important respiration pathway in these systems. Lower concentrations of CH4 could be accounted for by ebullition and vascular-plant transport. A closed system incubation study was done to determine if predicted CO2 and CH4 concentrations calculated using isotopes compared to measured concentration values. The average difference between the two approaches was 3.5%. Using the model to analyze field measurements, we found that a higher percent of CO2 was produced from methanogenesis than organic matter fermentation in both bog and fen environments. At depths, bogs had a slightly higher percent of CO2 from methanogenesis (100%) than did fens (90%). Surface depths shallower than 50cm produced a significantly larger (20%) amount of CO2 from organic-matter fermentation than deeper depths. Bogs and fens showed a similar amount of methane loss between 85-100% depending on depth.

  19. A STUDY ON CARBON ISOTOPE OF CO2 AND CH4 IN WESTERN DIENG PLATEU BY GAS CHROMATOGRAPHY- ISOTOPE RATIO MASS SPECTROMETER (GC-IRMS

    Directory of Open Access Journals (Sweden)

    Hanik Humaida

    2010-06-01

    Full Text Available The carbon isotope can be used to evaluate volcanism phenomenon of volcano. The study of carbon isotope of CO2 and CH4 was carried out in western Dieng Plateau by mass-spectrometer. Before analysis, sampel was separated by gas chromatography using a Porapak-Q column and a FID (Flame Ionization Detector detector. The gas was oxidized by copper oxide at 850oC before being ionized in mass-spectrometer for isotope analysis. The CO2 content in Candradimuka crater (-4.10 O/OO, indicated that the gas may be as volcanic gas. The other CO2 from Sumber and western Gua Jimat, had isotope value  of -10.05 and -12.07 O/OO, respectively, indicating contamination from crustal and subduction material. The carbon isotope of CH4 gas from Pancasan village was -63.42 O/OO, that may be categorized as biogenic gas.   Keywords: isotope, CO2, CH4, Dieng.

  20. N2O influence on isotopic measurements of atmospheric CO2

    NARCIS (Netherlands)

    Sirignano, C; Neubert, REM; Meijer, HAJ

    2004-01-01

    In spite of extensive efforts, even the most experienced laboratories dealing with isotopic measurements of atmospheric CO2 still suffer from poor inter-laboratory consistency. One of the complicating factors of these isotope measurements is the presence of N2O, giving rise to mass overlap in the is

  1. Oxygen isotope fractionation during spin-forbidden photolysis of CO2: Relevance to the atmosphere of Mars

    Science.gov (United States)

    Lyons, J. R.; Stark, G.; Pack, A.; de Oliveira, N.; Nahon, L.

    2015-12-01

    The oxygen isotope composition of the Martian atmosphere is of interest for comparison with recent MSL SAM results, and to understand the origin of oxygen isotope anomalies (i.e., mass-independent fractionation or MIF) in secondary minerals in SNC meteorites. Our focus here is on spin-forbidden photolysis of CO2, CO2 + hv (>167 nm) → CO(X1S) + O(3P). The spin-forbidden photolysis of CO2 is unusual in the Martian atmosphere because of its high reaction rate from the upper atmosphere (80 km) all the way to the ground. This range of altitudes spans 4 orders of magnitude in atmospheric pressure, and occurs because of the gradual decrease in the CO2 cross sections from 167 to ~200 nm. Previous laboratory photolysis experiments on CO2 in the spin-allowed and spin-forbidden regions have yielded a remarkably large MIF signature (17O excess ~ 100 permil) in O2 product for photolysis at 185 nm. Recent theoretical cross sections for CO2 isotopologues argue for a much smaller MIF signature from spin-forbidden photolysis. Here, we report the results of photolysis experiments on CO2 at the Soleil synchrotron DESIRS beamline. High purity, natural isotope abundance CO2 was placed in a 20 cm photocell with MgF2 windows. Experiments were performed at 3 wavelengths (7% FWHM): 160 nm (spin-allowed), and at 175 nm and 185 nm (spin-forbidden). After VUV exposure, aliquots of the photolyzed CO2 were sent to the Department of Isotope Geology at the University of Goettingen for O isotope analysis. The isotope results show that the spin-allowed photolysis yields normal, mass-dependent fractionation in agreement with earlier work. Photolysis at 175 nm, which is mostly spin-forbidden, yields a small positive (or zero) MIF signature. Photolysis at 185 nm, which is entirely spin-forbidden, yields O2 with a negative MIF signature (D17O ~ -8 to -10 permil). The results at 185 nm disagree in magnitude and sign with the very large positive MIF signature previously reported, and provides support

  2. The thermal desorption of CO2 from amine carbamate solutions for the 13C isotope enrichment

    Science.gov (United States)

    Dronca, S.; Varodi, C.; Gligan, M.; Stoia, V.; Baldea, A.; Hodor, I.

    2012-02-01

    The CO2 desorption from amine carbamate in non-aqueous solvents is of major importance for isotopic enrichment of 13C. A series of experiments were carried out in order to set up the conditions for the CO2 desorption. For this purpose, a laboratory- scale plant for 13C isotope separation by chemical exchange between CO2 and amine carbamate was designed and used. The decomposition of the carbamate solution was mostly produced in the desorber and completed in the boiler. Two different-length desorbers were used, at different temperatures and liquid flow rates of the amine-non-aqueous solvent solutions. The residual CO2 was determined by using volumetric and gaschromatographic methods. These results can be used for enrichment of 13C by chemical exchange between CO2 and amine carbamate in nonaqueous solvents.

  3. Geochemical features of the geothermal CO2-water-carbonate rock system and analysis on its CO2 sources--Examples from Huanglong Ravine and Kangding, Sichuan, and Xiage, Zhongdian, Yunnan

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Taking Huanglong Ravine and Kangding, Sichuan, and Xiage, Zhongdian, Yunnan, as examples, the authors summarize the hydrogeochemical and carbon stable isotopic features of the geothermal CO2-water-carbonate rock system and analyze the CO2 sources of the system. It was found that the hydrogeochemical and carbon stable isotopic features of such a system are different from those of shallow CO2-water-carbonate rock system, which is strongly influenced by biosphere. The former has higher CO2 partial pressure, and is rich in heavy carbon stable isotope. In addition, such a geothermal system is also different from that developed in igneous rock. The water in the latter system lacks Ca2+, and thus, there are few tufa deposits on ground surface, but it is rich in light carbon stable isotope. Further analysis shows that CO2 of the geothermal CO2-water-carbonate rock system is a mixture of metamorphic CO2 and magmatic CO2.

  4. Spatial and seasonal variabilities of the stable carbon isotope composition of soil CO2 concentration and flux in complex terrain

    Science.gov (United States)

    Liang, Liyin L.; Riveros-Iregui, Diego A.; Risk, David A.

    2016-09-01

    Biogeochemical processes driving the spatial variability of soil CO2 production and flux are well studied, but little is known about the variability in the spatial distribution of the stable carbon isotopes that make up soil CO2, particularly in complex terrain. Spatial differences in stable isotopes of soil CO2 could indicate fundamental differences in isotopic fractionation at the landscape level and may be useful to inform modeling of carbon cycling over large areas. We measured the spatial and seasonal variabilities of the δ13C of soil CO2 (δS) and the δ13C of soil CO2 flux (δP) in a subalpine forest ecosystem located in the Rocky Mountains of Montana. We found consistently more isotopically depleted values of δS and δP in low and wet areas of the landscape relative to steep and dry areas. Our results suggest that the spatial patterns of δS and δP are strongly mediated by soil water and soil respiration rate. More interestingly, our analysis revealed different temporal trends in δP across the landscape; in high landscape positions δP became more positive, whereas in low landscape positions δP became more negative with time. These trends might be the result of differential dynamics in the seasonality of soil moisture and its effects on soil CO2 production and flux. Our results suggest concomitant yet independent effects of water on physical (soil gas diffusivity) and biological (photosynthetic discrimination) processes that mediate δS and δP and are important when evaluating the δ13C of CO2 exchanged between soils and the atmosphere in complex terrain.

  5. Oxygen isotopes as a tool to quantify reservoir-scale CO2 pore-space saturation

    Science.gov (United States)

    Serno, Sascha; Flude, Stephanie; Johnson, Gareth; Mayer, Bernard; Boyce, Adrian; Karolyte, Ruta; Haszeldine, Stuart; Gilfillan, Stuart

    2017-04-01

    Structural and residual trapping of carbon dioxide (CO2) are two key mechanisms of secure CO2 storage, an essential component of Carbon Capture and Storage technology [1]. Estimating the amount of CO2 that is trapped by these two mechanisms is a vital requirement for accurately assessing the secure CO2 storage capacity of a formation, but remains a key challenge. Recent field [2,3] and laboratory experiment studies [4] have shown that simple and relatively inexpensive measurements of oxygen isotope ratios in both the injected CO2 and produced water can provide an assessment of the amount of CO2 that is stored by these processes. These oxygen isotope assessments on samples obtained from observation wells provide results which are comparable to other geophysical techniques. In this presentation, based on the first comprehensive review of oxygen isotope ratios measured in reservoir waters and CO2 from global CO2 injection projects, we will outline the advantages and potential limitations of using oxygen isotopes to quantify CO2 pore-space saturation. We will further summarise the currently available information on the oxygen isotope composition of captured CO2. Finally, we identify the potential issues in the use of the oxygen isotope shifts in the reservoir water from baseline conditions to estimate accurate saturations of the pore space with CO2, and suggest how these issues can be reduced or avoided to provide reliable CO2 pore-space saturations on a reservoir scale in future field experiments. References [1] Scott et al., (2013) Nature Climate Change, Vol. 3, 105-111 doi:10.1038/nclimate1695 [2] Johnson et al., (2011) Chemical Geology, Vol. 283, 185-193 http://dx.doi.org/10.1016/j.ijggc.2016.06.019 [3] Serno et al., (2016) IJGGC, Vol. 52, 73-83 http://dx.doi.org/10.1016/j.ijggc.2016.06.019 [4] Johnson et al., (2011) Applied Geochemistry, Vol. 26 (7) 1184-1191 http://dx.doi.org/10.1016/j.apgeochem.2011.04.007

  6. Mantle CO2 degassing through the Icelandic crust: Evidence from carbon isotopes in groundwater

    Science.gov (United States)

    Stefánsson, Andri; Sveinbjörnsdóttir, Árný E.; Heinemeier, Jan; Arnórsson, Stefán; Kjartansdóttir, Ríkey; Kristmannsdóttir, Hrefna

    2016-10-01

    Carbon isotopes of groundwater in Iceland were studied in order to determine the source and reactions of carbon at divergent plate boundaries not associated with active volcanic systems. All the waters were of meteoric origin, with temperatures of 1-130 °C, pH of ∼4.5-10.5 and dissolved inorganic carbon (∑CO2) between 1.8 and 4100 ppm. The measured range of δ13CO2 and 14CO2 in these waters was large, -27.4 to +2.0‰ and 0.6-118 pMC, respectively. The sources and reactions of dissolved inorganic carbon were studied by comparing the measured chemical and isotope composition with those simulated using isotope geochemical models. Three major sources of CO2 were identified: (1) dissolution of partially degassed basaltic rocks formed at the surface or shallow depths, (2) atmospheric CO2 through air-water exchange at surface, and (3) input of gas at depth into the groundwater systems that has similar carbon and isotope composition as the pre-erupted melt of the upper mantle and lower crust beneath Iceland. In the groundwater systems the CO2 chemistry and isotope content are modified due to carbonate mineral precipitation and changes in aqueous species distribution upon progressive water-rock interaction; these changes needed to be quantified in order to reveal the various CO2 sources. The CO2 flux of the Icelandic crust was estimated to be ∼5-10 · 1010 mol/yr with as high as 50% of the flux not associated with active volcanic centers but placed off-axis where a significant proportion of the CO2 may originate from the mantle. The mantle input of the groundwater off-axis corresponds to CO2 partial pressures of ∼10-6-1 bar and to a mantle CO2 flux of <5 · 105 mol/km2/yr for most areas and up to 125 · 105 and 1600 · 105 for the Southern Lowlands and Snæfellsnes Peninsula, respectively. The CO2 flux from active volcanic geothermal systems in Iceland was estimated to be ∼500-3000 · 105 mol CO2/km2/yr, considerably greater than the highest values observed off-axis.

  7. [Net CO2 exchange and carbon isotope flux in Acacia mangium plantation].

    Science.gov (United States)

    Zou, Lu-Liu; Sun, Gu-Chou; Zhao, Ping; Cai, Xi-An; Zeng, Xiao-Ping; Wang, Quan

    2009-11-01

    By using stable carbon isotope technique, the leaf-level 13C discrimination was integrated to canopy-scale photosynthetic discrimination (Deltacanopy) through weighted the net CO2 assimilation (Anet) of sunlit and shaded leaves and the stand leaf area index (L) in an A. mangium plantation, and the carbon isotope fluxes from photosynthesis and respiration as well as their net exchange flux were obtained. There was an obvious diurnal variation in Deltacanopy, being lower at dawn and at noon time (18.47 per thousand and 19.87 per thousand, respectively) and the highest (21.21 per thousand) at dusk. From the end of November to next May, the Deltacanopy had an increasing trend, with an annual average of (20.37 +/- 0.29) per thousand. The carbon isotope ratios of CO2 from autotrophic respiration (excluding daytime foliar respiration) and heterotrophic respiration were respectively (- 28.70 +/- 0.75) per thousand and (- 26.75 +/- 1.3) per thousand in average. The delta13 C of nighttime ecosystem-respired CO2 in May was the lowest (-30.14 per thousand), while that in November was the highest (-28.01 per thousand). The carbon isotope flux of CO2 between A. mangium forest and atmosphere showed a midday peak of 178.5 and 217 micromol x m(-2) x s(-1) x per thousand in May and July, with the daily average of 638.4 and 873.2 micromol x m(-2) x s(-1) x per thousand, respectively. The carbon isotope flux of CO2 absorbed by canopy leaves was 1.6-2.5 times higher than that of CO2 emitted from respiration, suggesting that a large sum of CO2 was absorbed by A. mangium, which decreased the atmospheric CO2 concentration and improved the environment.

  8. A deep-time CO2 barometer based on triple oxygen isotope compositions of dinosaurian eggshell carbonate

    Science.gov (United States)

    Hu, H.; Passey, B. H.; Montanari, S.; Levin, N.; Li, S.

    2013-12-01

    Photochemical reactions in the stratosphere lead to mass independent fractionation of oxygen isotopes: oxygen exchange among O2, O3, and CO2 produces 17O-enriched O3 and CO2, and 17O-depleted O2. This effect increases with increasing atmospheric CO2 concentration, and thus the 17O anomaly of O2, Δ17O (O2), is reflective of pCO2. Animals incorporate this signal into body water via respiration, and minerals such as bioapatite and eggshell calcite forming in equilibrium with body water can preserve the signal for millions of years. We contribute to the development of this new pCO2 barometer by developing analytical methods for high-precision triple oxygen isotope analysis of carbonates, by developing an ecophysiological model of body water triple oxygen isotopes, and by applying the method to eggshell from modern birds and late Cretaceous (Campanian and Maastrichtian) dinosaur eggshells. Our findings include the following: (1) If animal ecophysiology and climatic context are perfectly known, the sensitivity of Δ17O (body water) to atmospheric CO2 is on the order of 0.01 ‰ per 100 ppm CO2; our analytical precision is ~ 0.01 ‰, thus ultimately permitting sub -100 ppm - level pCO2 reconstructions. (2) However, the effect of ecophysiology and climate can lead to a range in Δ17O (body water) of about 0.15 ‰ for animals living under the same Δ17O (O2); this prediction, confirmed by analyses of eggshells and body water of modern birds, translates to an apparent pCO2 range of about 1500 ppm. (3) Animals that are highly dependent on unevaporated free surface water ('drinking water') and live in humid climates have Δ17O (body water) signals that mimic low pCO2, whereas animals that consume primarily evaporated water (e.g., leaf water) and living in arid environments have Δ17O (body water) signals that mimic high pCO2. (4) There is an upper limit to this 'evaporation / aridity' effect mimicking high pCO2, so Δ17O (fossil eggshell) can be modeled assuming such upper

  9. The effects of atmospheric [CO2] on carbon isotope fractionation and magnesium incorporation into biogenic marine calcite

    Science.gov (United States)

    Vieira, Veronica

    1997-01-01

    The influences of atmospheric carbon dioxide on the fractionation of carbon isotopes and the magnesium incorporation into biogenic marine calcite were investigated using samples of the calcareous alga Amphiroa and benthic foraminifer Sorites grown in the Biosphere 2 Ocean system under variable atmospheric CO2 concentrations (approximately 500 to 1200 ppm). Carbon isotope fractionation was studied in both the organic matter and the skeletal carbonate. Magnesium analysis was to be performed on the carbonate removed during decalcification. These data have not been collected due to technical problems. Carbon isotope data from Amphiroa yields a linear relation between [CO2] and Delta(sup 13)C(sub Corg)values suggesting that the fractionation of carbon isotopes during photosynthesis is positively correlated with atmospheric [CO2]. [CO2] and Delta(sup 13)C(sub Corg) values for Sorites produce a relation that is best described by a hyperbolic function where Delta(sup 13)C(sub Corg) values increase between 300 and 700 ppm and decrease from 700 to 1200 ppm. Further investigation of this relation and Sorites physiology is needed.

  10. The effect of atmospheric CO2 concentration on carbon isotope fractionation in C3 land plants

    Science.gov (United States)

    Schubert, Brian A.; Jahren, A. Hope

    2012-11-01

    Because atmospheric carbon dioxide is the ultimate source of all land-plant carbon, workers have suggested that pCO2 level may exert control over the amount of 13C incorporated into plant tissues. However, experiments growing plants under elevated pCO2 in both chamber and field settings, as well as meta-analyses of ecological and agricultural data, have yielded a wide range of estimates for the effect of pCO2 on the net isotopic discrimination (Δδ13Cp) between plant tissue (δ13Cp) and atmospheric CO2 (δ13CCO2). Because plant stomata respond sensitively to plant water status and simultaneously alter the concentration of pCO2 inside the plant (ci) relative to outside the plant (ca), any experiment that lacks environmental control over water availability across treatments could result in additional isotopic variation sufficient to mask or cancel the direct influence of pCO2 on Δδ13Cp. We present new data from plant growth chambers featuring enhanced dynamic stabilization of moisture availability and relative humidity, in addition to providing constant light, nutrient, δ13CCO2, and pCO2 level for up to four weeks of plant growth. Within these chambers, we grew a total of 191 C3 plants (128 Raphanus sativus plants and 63 Arabidopsis thaliana) across fifteen levels of pCO2 ranging from 370 to 4200 ppm. Three types of plant tissue were harvested and analyzed for carbon isotope value: above-ground tissues, below-ground tissues, and leaf-extracted nC31-alkanes. We observed strong hyperbolic correlations (R ⩾ 0.94) between the pCO2 level and Δδ13Cp for each type of plant tissue analyzed; furthermore the linear relationships previously suggested by experiments across small (10-350 ppm) changes in pCO2 (e.g., 300-310 ppm or 350-700 ppm) closely agree with the amount of fractionation per ppm increase in pCO2 calculated from our hyperbolic relationship. In this way, our work is consistent with, and provides a unifying relationship for, previous work on carbon isotopes

  11. CO2-dependent carbon isotope fractionation in the dinoflagellate Alexandrium tamarense

    Science.gov (United States)

    Wilkes, Elise B.; Carter, Susan J.; Pearson, Ann

    2017-09-01

    The carbon isotopic composition of marine sedimentary organic matter is used to resolve long-term histories of pCO2 based on studies indicating a CO2-dependence of photosynthetic carbon isotope fractionation (εP). It recently was proposed that the δ13C values of dinoflagellates, as recorded in fossil dinocysts, might be used as a proxy for pCO2. However, significant questions remain regarding carbon isotope fractionation in dinoflagellates and how such fractionation may impact sedimentary records throughout the Phanerozoic. Here we investigate εP as a function of CO2 concentration and growth rate in the dinoflagellate Alexandrium tamarense. Experiments were conducted in nitrate-limited chemostat cultures. Values of εP were measured on cells having growth rates (μ) of 0.14-0.35 d-1 and aqueous carbon dioxide concentrations of 10.2-63 μmol kg-1 and were found to correlate linearly with μ/[CO2(aq)] (r2 = 0.94) in accord with prior, analogous chemostat investigations with eukaryotic phytoplankton. A maximum fractionation (εf) value of 27‰ was characterized from the intercept of the experiments, representing the first value of εf determined for an algal species employing Form II RubisCO-a structurally and catalytically distinct form of the carbon-fixing enzyme. This value is larger than theoretical predictions for Form II RubisCO and not significantly different from the ∼25‰ εf values observed for taxa employing Form ID RubisCO. We also measured the carbon isotope contents of dinosterol, hexadecanoic acid, and phytol from each experiment, finding that each class of biomarker exhibits different isotopic behavior. The apparent CO2-dependence of εP values in our experiments strengthens the proposal to use dinocyst δ13C values as a pCO2 proxy. Moreover, the similarity between the εf value for A. tamarense and the consensus value of ∼25‰ indicates that the CO2-sensitivity of carbon isotope fractionation saturates at similar CO2 levels across all three

  12. Analysis of 13C and 18O isotope data of CO2 in CARIBIC aircraft samples as tracers of upper troposphere/lower stratosphere mixing and the global carbon cycle

    Directory of Open Access Journals (Sweden)

    C. A. M. Brenninkmeijer

    2010-09-01

    Full Text Available The project CARIBIC (http://caribic-atmospheric.com aims to study atmospheric chemistry and transport by regularly measuring many compounds in the free troposphere and the upper troposphere/lowermost stratosphere (UT/LMS by using passenger aircraft. Here we present CO2 concentrations and isotope results, and analyze the data together with supporting trace gas data. 509 CARIBIC-2 samples (highest precision and accuracy δ13C(CO2 and δ18O(CO2 data from June 2007 until March 2009, together with CARIBIC-1 samples (flights between November 1999 and April 2002, 350 samples in total, 270 for NH, mostly δ13C(CO2 data give a fairly extensive, unique data set for the NH free troposphere and the UT/LMS region. Total uncertainty of the data is the same as reported for the global monitoring program by NOAA-ESRL. To compare data from different years a de-trending is applied. In the UT/LMS region δ13C(CO2, δ18O(CO2 and CO2 are found to correlate well with stratospheric tracers, in particular N2O; δ18O(CO2 appears to be a useful, hitherto unused, tracer of atmospheric transport in the UT/LMS region and also inter-hemispheric mixing. By filtering out the LMS data (based on N2O distributions, the isotope variations for the free and upper troposphere are obtained. These variations have only small latitudinal gradients, if any, and are in good agreement with the data of selected NOAA stations in NH tropics. Correlations between δ13C(CO2 and CO2 are observed both within single flight(s covering long distances and during certain seasons. The overall variability in de-trended δ13C(CO2 and CO2 for CARIBIC-1 and CARIBIC-2 are similar and are generally in agreement, which underscores agreement between high and low resolution sampling. Based on all correlations, we infer that the CO2 distribution in the NH troposphere along CARIBIC flight routes is chiefly regulated by uplift and pole-wards transport of tropical air up to approximately 50° N. The main reason for

  13. H2S interference on CO2 isotopic measurements using a Picarro G1101-i cavity ring-down spectrometer

    Directory of Open Access Journals (Sweden)

    K. Malowany

    2015-06-01

    Full Text Available Cavity ring-down spectrometers (CRDS have the capacity to make isotopic measurements of CO2 where concentrations range from atmospheric (~ 400 ppm to 6000 ppm. Following field trials, it has come to light that the spectrographic lines used for CO2 have an interference with elevated (higher than ambient amounts of hydrogen sulfide (H2S, which causes significant depletions in the δ13C measurement by the CRDS. In order to deploy this instrument in environments with elevated H2S concentrations (i.e., active volcanoes, we require a robust method for eliminating this interference. Controlled experiments using a Picarro G1101-i optical spectrometer were done to characterize the H2S interference at varying CO2 and H2S concentrations. The addition of H2S to a CO2 standard gas reveals an increase in the 12CO2 concentration and a more significant decrease in the 13CO2 concentration, resulting in a depleted δ13C value. Reacting gas samples containing H2S with copper prior to analysis can eliminate this effect. However, experiments also revealed that the addition of H2S to CO2 results in the formation of carbonyl sulfide (OCS and carbon disulfide (CS2, causing a decrease in the overall CO2 concentration without affecting the δ13C value. It is important for future work with CRDS, particularly in volcanic regions where H2S is abundant, to be aware of the H2S interference on the CO2 spectroscopic lines and to remove all H2S prior to analysis. We suggest employing a scrub composed of copper to remove H2S from all gas samples that have concentrations in excess of 1 ppb.

  14. Interannual variability in the oxygen isotopes of atmospheric CO2 driven by El Nino

    NARCIS (Netherlands)

    Welp, Lisa R.; Keeling, Ralph F.; Meijer, Harro A. J.; Bollenbacher, Alane F.; Piper, Stephen C.; Yoshimura, Kei; Francey, Roger J.; Allison, Colin E.; Wahlen, Martin

    2011-01-01

    The stable isotope ratios of atmospheric CO2 (O-18/O-16 and C-13/C-12) have been monitored since 1977 to improve our understanding of the global carbon cycle, because biosphere-atmosphere exchange fluxes affect the different atomic masses in a measurable way(1). Interpreting the O-18/O-16 variabilit

  15. Phytoplankton-bacteria coupling under elevated CO2 levels: a stable isotope labelling study

    Directory of Open Access Journals (Sweden)

    J. J. Middelburg

    2010-11-01

    Full Text Available The potential impact of rising carbon dioxide (CO2 on carbon transfer from phytoplankton to bacteria was investigated during the 2005 PeECE III mesocosm study in Bergen, Norway. Sets of mesocosms, in which a phytoplankton bloom was induced by nutrient addition, were incubated under 1× (~350 μatm, 2× (~700 μatm, and 3× present day CO2 (~1050 μatm initial seawater and sustained atmospheric CO2 levels for 3 weeks. 13C labelled bicarbonate was added to all mesocosms to follow the transfer of carbon from dissolved inorganic carbon (DIC into phytoplankton and subsequently heterotrophic bacteria, and settling particles. Isotope ratios of polar-lipid-derived 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, whilst it took another 3 days before bacteria showed substantial enrichment. Group-specific primary production measurements revealed that coccolithophores showed higher primary production 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 during the bloom. There was no indication of CO2 effects on enhanced settling based on isotope mixing models during the phytoplankton bloom, but this could not be determined in the post-bloom phase. Our results suggest that CO2 effects are most pronounced in the post-bloom phase, under nutrient limitation.

  16. CO2-dependent carbon isotope fractionation in dinoflagellates relates to their inorganic carbon fluxes.

    Science.gov (United States)

    Hoins, Mirja; Eberlein, Tim; Van de Waal, Dedmer B; Sluijs, Appy; Reichart, Gert-Jan; Rost, Björn

    2016-08-01

    Carbon isotope fractionation (εp) between the inorganic carbon source and organic matter has been proposed to be a function of pCO2. To understand the CO2-dependency of εp and species-specific differences therein, inorganic carbon fluxes in the four dinoflagellate species Alexandrium fundyense, Scrippsiella trochoidea, Gonyaulax spinifera and Protoceratium reticulatum have been measured by means of membrane-inlet mass spectrometry. In-vivo assays were carried out at different CO2 concentrations, representing a range of pCO2 from 180 to 1200 μatm. The relative bicarbonate contribution (i.e. the ratio of bicarbonate uptake to total inorganic carbon uptake) and leakage (i.e. the ratio of CO2 efflux to total inorganic carbon uptake) varied from 0.2 to 0.5 and 0.4 to 0.7, respectively, and differed significantly between species. These ratios were fed into a single-compartment model, and εp values were calculated and compared to carbon isotope fractionation measured under the same conditions. For all investigated species, modeled and measured εp values were comparable (A. fundyense, S. trochoidea, P. reticulatum) and/or showed similar trends with pCO2 (A. fundyense, G. spinifera, P. reticulatum). Offsets are attributed to biases in inorganic flux measurements, an overestimated fractionation factor for the CO2-fixing enzyme RubisCO, or the fact that intracellular inorganic carbon fluxes were not taken into account in the model. This study demonstrates that CO2-dependency in εp can largely be explained by the inorganic carbon fluxes of the individual dinoflagellates.

  17. Experimental oxygen isotope fractionation between siderite-water and phosphoric acid liberated CO2-siderite

    Science.gov (United States)

    Carothers, W.W.; Adami, L.H.; Rosenbauer, R.J.

    1988-01-01

    The equilibrium fractionation of O isotopes between synthetic siderite and water has been measured at temperatures ranging from 33?? to 197??C. The fractionation between siderite and water over this temperature range can be represented by the equation: 103 ln ?? = 3.13 ?? 106T-2 - 3.50. Comparison between the experimental and theoretical fractionations is favorable only at approximately 200??C; at lower temperatures, they generally differ by up to 2 permil. Siderite was prepared by the slow addition of ferrous chloride solutions to sodium bicarbonate solutions at the experimental temperatures. It was also used to determine the O isotope fractionation factors between phosphoric acid liberated CO2 and siderite. The fractionation factors for this pair at 25?? and 50??C are 1.01175 and 1.01075, respectively. Preliminary results of the measured C isotope fractionation between siderite and Co2 also indicate C isotopic equilibrium during precipitation of siderite. The measured distribution of 13C between siderite and CO2 coincides with the theoretical values only at about 120??C. Experimental and theoretical C fractionations differ up to 3 permil at higher and lower temperatures. ?? 1988.

  18. Atmospheric pCO2 control on speleothem stable carbon isotope compositions

    Science.gov (United States)

    Breecker, Daniel O.

    2017-01-01

    The stable carbon isotope compositions of C3 plants are controlled by the carbon isotope composition of atmospheric CO2 (δ13Ca) and by the stomatal response to water stress. These relationships permit the reconstruction of ancient environments and assessment of the water use efficiency of forests. It is currently debated whether the δ13C values of C3 plants are also controlled by atmospheric pCO2. Here I show that globally-averaged speleothem δ13C values closely track atmospheric pCO2 over the past 90 kyr. After accounting for other possible effects, this coupling is best explained by a C3 plant δ13C sensitivity of - 1.6 ± 0.3 ‰ / 100 ppmV CO2 during the Quaternary. This is consistent with 20th century European forest tree ring δ13C records, providing confidence in the result and suggesting that the modest pCO2-driven increase in water use efficiency determined for those ecosystems and simulated by land surface models accurately approximates the global average response. The δ13C signal from C3 plants is transferred to speleothems relatively rapidly. Thus, the effect of atmospheric pCO2 should be subtracted from new and existing speleothem δ13C records so that residual δ13C shifts can be interpreted in light of the other factors known to control spleleothem δ13C values. Furthermore, global average speleothem δ13C shifts may be used to develop a continuous radiometric chronology for Pleistocene atmospheric pCO2 fluctuations and, by correlation, ice core climate records.

  19. Vehicle emissions of greenhouse gases and related tracers from a tunnel study: : CO: CO2, N2O: CO2, CH4: CO2, O2: CO2 ratios, and the stable isotopes 13C and 18O in CO2 and CO

    NARCIS (Netherlands)

    Popa, Maria Elena; Vollmer, M. K.; Jordan, A.; Brand, W. A.; Pathirana, S. L.|info:eu-repo/dai/nl/330541242; Rothe, M.; Röckmann, T.|info:eu-repo/dai/nl/304838233

    2014-01-01

    Measurements of CO2, CO, N2O and CH4 mole fractions, O2/N2 ratios and the stable isotopes 13C and 18O in CO2 and CO have been performed in air samples from the Islisberg highway tunnel (Switzerland). The molar CO : CO2 ratios, with an average of (4.15 ± 0.34) ppb:ppm, are lower than reported in prev

  20. Vehicle emissions of greenhouse gases and related tracers from a tunnel study: : CO: CO2, N2O: CO2, CH4: CO2, O2: CO2 ratios, and the stable isotopes 13C and 18O in CO2 and CO

    NARCIS (Netherlands)

    Popa, Maria Elena; Vollmer, M. K.; Jordan, A.; Brand, W. A.; Pathirana, S. L.; Rothe, M.; Röckmann, T.

    2014-01-01

    Measurements of CO2, CO, N2O and CH4 mole fractions, O2/N2 ratios and the stable isotopes 13C and 18O in CO2 and CO have been performed in air samples from the Islisberg highway tunnel (Switzerland). The molar CO : CO2 ratios, with an average of (4.15 ± 0.34) ppb:ppm, are lower than reported in prev

  1. Vehicle emissions of greenhouse gases and related tracers from a tunnel study: : CO: CO2, N2O: CO2, CH4: CO2, O2: CO2 ratios, and the stable isotopes 13C and 18O in CO2 and CO

    National Research Council Canada - National Science Library

    Popa, Maria Elena; Vollmer, M. K; Jordan, A; Brand, W. A; Pathirana, S. L; Rothe, M; Röckmann, T

    2014-01-01

    Measurements of CO2, CO, N2O and CH4 mole fractions, O2/N2 ratios and the stable isotopes 13C and 18O in CO2 and CO have been performed in air samples from the Islisberg highway tunnel (Switzerland). The molar CO...

  2. High Precision 2.0 μm Photoacoustic Spectrometer for Determination of the ^{13}CO_{2}/^{12}CO_{2} Isotope Ratio

    Science.gov (United States)

    Reed, Zachary; Hodges, Joseph T.

    2017-06-01

    We have developed a portable photoacoustic spectrometer for high precision measurements of the ^{13}CO_{2}/^{12}CO_{2} isotope ratio and the absolute molar concentration of each isotope. The spectrometer extends on our previous work at 1.57 μm [1], and now employs two separate intensity modulated distributed feedback lasers and a fiber amplifier, operating in the 2.0 μm wavelength region. Each DFB is selected to probe individual spectrally isolated ro-vibrational transitions for ^{12}CO_{2} and ^{13}CO_{2}. The spectrometer is actively temperature controlled, mitigating variations in the two spectral line intensities and the temperature dependent system response. For measurements of ambient concentrations of carbon dioxide at nominally natural abundance in dry air, we demonstrate a measurement precision of 140 ppb for ^{12}CO_{2} with a 1 s averaging time and 10 ppb for ^{13}CO_{2} with a 60 s averaging time. Precision in δ13C of better than 0.1 permil is demonstrated. The analyzer response is calibrated in terms of certified gas mixtures and compared to characterization by cavity ringdown spectroscopy. We also investigate how water vapor affects the photoacoustic signals by promoting collisional relaxation for each isotope. [1] Z.D. Reed, B. Sperling, et al. App. Phys. B. 117, 645-657, 2014

  3. CO2 isotope analyses using large air samples collected on intercontinental flights by the CARIBIC Boeing 767.

    Science.gov (United States)

    Assonov, S S; Brenninkmeijer, C A M; Koeppel, C; Röckmann, T

    2009-03-01

    Analytical details for 13C and 18O isotope analyses of atmospheric CO2 in large air samples are given. The large air samples of nominally 300 L were collected during the passenger aircraft-based atmospheric chemistry research project CARIBIC and analyzed for a large number of trace gases and isotopic composition. In the laboratory, an ultra-pure and high efficiency extraction system and high-quality isotope ratio mass spectrometry were used. Because direct comparison with other laboratories was practically impossible, the extraction and measurement procedures were tested in considerable detail. Extracted CO2 was measured twice vs. two different working reference CO2 gases of different isotopic composition. The two data sets agree well and their distributions can be used to evaluate analytical errors due to isotope measurement, ion corrections, internal calibration consistency, etc. The calibration itself is based on NBS-19 and also verified using isotope analyses on pure CO2 gases (NIST Reference Materials (RMs) and NARCIS CO2 gases). The major problem encountered could be attributed to CO2-water exchange in the air sampling cylinders. This exchange decreased over the years. To exclude artefacts due to such isotopic exchange, the data were filtered to reject negative delta18O(CO2) values. Examples of the results are given.

  4. Carbon-13 isotope composition of the mean CO2 source in the urban atmosphere of Krakow, southern Poland

    Science.gov (United States)

    Zimnoch, Miroslaw; Jasek, Alina; Rozanski, Kazimierz

    2014-05-01

    Quantification of carbon emissions in urbanized areas constitutes an important part of the current research on the global carbon cycle. As the carbon isotopic composition of atmospheric carbon dioxide can serve as a fingerprint of its origin, systematic observations of δ13CO2 and/or Δ14CO2, combined with atmospheric CO2mixing ratio measurements can be used to better constrain the urban sources of this gas. Nowadays, high precision optical analysers based on absorption of laser radiation in the cavity allow a real-time monitoring of atmospheric CO2 concentration and its 13CO2/12CO2 ratio, thus enabling better quantification of the contribution of different anthropogenic and natural sources of this gas to the local atmospheric CO2load. Here we present results of a 2-year study aimed at quantifying carbon isotopic signature of the mean CO2 source and its seasonal variability in the urban atmosphere of Krakow, southern Poland. The Picarro G2101-i CRDS isotopic analyser system for CO2and 13CO2/12CO2 mixing ratio measurements has been installed at the AGH University of Science and Technology campus in July 2011. Air inlet was located at the top of a 20m tower mounted on the roof of the faculty building (ca. 42m a.g.l.), close to the city centre. While temporal resolution of the analyser is equal 1s, a 2-minute moving average was used for calculations of δ13CO2 and CO2 mixing ratio to reduce measurement uncertainty. The measurements were calibrated against 2 NOAA (National Oceanic and Atmospheric Administration) primary standard tanks for CO2 mixing ratio and 1 JRAC (Jena Reference Air Cylinder) isotope primary standard for δ13C. A Keeling approach based on two-component mass and isotope balance was used to derive daily mean isotopic signatures of local CO2 from individual measurements of δ13CO2 and CO2 mixing ratios. The record covers a 2-year period, from July 2011 to July 2013. It shows a clear seasonal pattern, with less negative and less variable δ13CO2 values

  5. Mechanisms linking metabolism of Helicobacter pylori to (18)O and (13)C-isotopes of human breath CO2.

    Science.gov (United States)

    Som, Suman; De, Anulekha; Banik, Gourab Dutta; Maity, Abhijit; Ghosh, Chiranjit; Pal, Mithun; Daschakraborty, Sunil B; Chaudhuri, Sujit; Jana, Subhra; Pradhan, Manik

    2015-06-03

    The gastric pathogen Helicobacter pylori utilize glucose during metabolism, but the underlying mechanisms linking to oxygen-18 ((18)O) and carbon-13 ((13)C)-isotopic fractionations of breath CO2 during glucose metabolism are poorly understood. Using the excretion dynamics of (18)O/(16)O and (13)C/(12)C-isotope ratios of breath CO2, we found that individuals with Helicobacter pylori infections exhibited significantly higher isotopic enrichments of (18)O in breath CO2 during the 2h-glucose metabolism regardless of the isotopic nature of the substrate, while no significant enrichments of (18)O in breath CO2 were manifested in individuals without the infections. In contrast, the (13)C-isotopic enrichments of breath CO2 were significantly higher in individuals with Helicobacter pylori compared to individuals without infections in response to (13)C-enriched glucose uptake, whereas a distinguishable change of breath (13)C/(12)C-isotope ratios was also evident when Helicobacter pylori utilize natural glucose. Moreover, monitoring the (18)O and (13)C-isotopic exchange in breath CO2 successfully diagnosed the eradications of Helicobacter pylori infections following a standard therapy. Our findings suggest that breath (12)C(18)O(16)O and (13)C(16)O(16)O can be used as potential molecular biomarkers to distinctively track the pathogenesis of Helicobacter pylori and also for eradication purposes and thus may open new perspectives into the pathogen's physiology along with isotope-specific non-invasive diagnosis of the infection.

  6. CO2 uptake of a mature Acacia mangium plantation estimated from sap flow measurements and stable carbon isotope discrimination

    Science.gov (United States)

    Wang, H.; Zhao, P.; Zou, L. L.; McCarthy, H. R.; Zeng, X. P.; Ni, G. Y.; Rao, X. Q.

    2014-03-01

    A simple, nondestructive method for the estimation of canopy CO2 uptake is important for understanding the CO2 exchange between forest and atmosphere. Canopy CO2 uptake (FCO2) of a subtropical mature A. mangium plantation was estimated by combining sap flow measurements and stable carbon isotope discrimination (Δ) in Southern China from 2004 to 2007. The mechanistic relationship linking FCO2, Δ in leaf sap, and sap flow-based canopy stomatal conductance (Gs) was applied in our study. No significant seasonal variations were observed in Δ or in the ratio of the intercellular and ambient CO2 concentrations (Ci/Ca), although diurnal Ci/Ca varied between sunlit and shaded leaves. A sensitivity analysis showed that estimates of FCO2 were more sensitive to dynamics in Gs than in Ca and Δ. By using seasonally and canopy averaged Ci/Ca values, we obtained an acceptable estimate of FCO2 compared to other estimates. FCO2 exhibited similar diurnal variation to that of Gs. Large seasonal variation in FCO2 was attributed to the responsiveness of Gs to vapor pressure deficit, photosynthetically active radiation, and soil moisture deficit. Our estimate of FCO2 for a mature A. mangium plantation (2.13 ± 0.40 gC m-2 d-1) approached the lower range of values for subtropical mixed forests, probably due to lower mean canopy stomatal conductance, higher Ci/Ca, and greater tree height than other measured forests. Our estimate was also lower than values determined by satellite-based modeling or carbon allocation studies, suggesting the necessity of stand level flux data for verification. Qualitatively, the sap flux/stable isotope results compared well with gas exchange results. Differences in results between the two approaches likely reflected variability due to leaf position and age, which should be reduced for the combined sap flux and isotope technique, as it uses canopy average values of Gs and Ci/Ca.

  7. Carbonyl Sulfide: is it AN Isotope of CO2 on Steroids?

    Science.gov (United States)

    Berry, J. A.; Campbell, J. E.; Baker, I. T.; Whelan, M.; Hilton, T. W.

    2015-12-01

    The behavior of OCS in the atmosphere is very similar to that of CO2 and reminiscent of an isotopologue. It is stable, has a turnover time of a couple of years (similar to that of 18O in CO2). It can be measured with adequate accuracy - despite the fact that its abundance is one millionth that of CO2, but there is one dramatic difference. The seasonal variation in the concentration of OCS relative to its background concentration can be 6-10 fold larger than the corresponding variation in CO2 concentration. Furthermore there are large spatial gradients in atmospheric OCS, with the concentrations being generally lower over the continents than the ocean, and lower in the atmospheric boundary layer over vegetated surfaces than in the free troposphere. These gradients have been clearly resolved by flask sampling from aircraft and recently by satellite measurements. The dynamics of OCS are larger than any other conserved atmospheric gas and certainly dwarf isotopic gradients. There are strong differences in the kinetics of CO2 and OCS exchange with leaves (similar to an isotopic fractionation), but these are not responsible for the large atmospheric signals. The major driver of these gradients is a large spatial separation between the major sources of OCS (the tropical ocean) and the major sink (the terrestrial biosphere). This talk will review the biogeochemical cycle of OCS; the kinetics of its exchange with leaves and soils; the distribution of sources and sinks, and the local and large scale gradients of OCS concentration in the atmosphere.

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

    Science.gov (United States)

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

    2015-12-01

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

  9. Fate of injected CO2 in the Wilcox Group, Louisiana, Gulf Coast Basin: Chemical and isotopic tracers of microbial-brine-rock-CO2 interactions

    Science.gov (United States)

    Shelton, Jenna L.; McIntosh, Jennifer C.; Warwick, Peter D.; Lee Zhi Yi, Amelia

    2016-01-01

    The “2800’ sandstone” of the Olla oil field is an oil and gas-producing reservoir in a coal-bearing interval of the Paleocene–Eocene Wilcox Group in north-central Louisiana, USA. In the 1980s, this producing unit was flooded with CO2 in an enhanced oil recovery (EOR) project, leaving ∼30% of the injected CO2 in the 2800’ sandstone post-injection. This study utilizes isotopic and geochemical tracers from co-produced natural gas, oil and brine to determine the fate of the injected CO2, including the possibility of enhanced microbial conversion of CO2 to CH4 via methanogenesis. Stable carbon isotopes of CO2, CH4 and DIC, together with mol% CO2 show that 4 out of 17 wells sampled in the 2800’ sandstone are still producing injected CO2. The dominant fate of the injected CO2appears to be dissolution in formation fluids and gas-phase trapping. There is some isotopic and geochemical evidence for enhanced microbial methanogenesis in 2 samples; however, the CO2 spread unevenly throughout the reservoir, and thus cannot explain the elevated indicators for methanogenesis observed across the entire field. Vertical migration out of the target 2800’ sandstone reservoir is also apparent in 3 samples located stratigraphically above the target sand. Reservoirs comparable to the 2800’ sandstone, located along a 90-km transect, were also sampled to investigate regional trends in gas composition, brine chemistry and microbial activity. Microbial methane, likely sourced from biodegradation of organic substrates within the formation, was found in all oil fields sampled, while indicators of methanogenesis (e.g. high alkalinity, δ13C-CO2 and δ13C-DIC values) and oxidation of propane were greatest in the Olla Field, likely due to its more ideal environmental conditions (i.e. suitable range of pH, temperature, salinity, sulfate and iron concentrations).

  10. CO2 and 12C:13C Isotopic Ratios on Phoebe and Iapetus

    Science.gov (United States)

    Clark, R. N.; Brown, R. H.; Cruikshank, D. P.

    2016-12-01

    Cassini VIMS has obtained spatially resolved 0.35 to 5.1 micron reflectance spectra of Saturn's satellites beginning with the Phoebe fly-by in 2004 and a close fly-by of Iapetus in 2007. Both surfaces contain relatively abundant CO2. The new (2016 RC19) calibration of VIMS has provided a significant increase in the data quality, such that isotopic absorption bands in CO2 are now well defined. CO2 on Saturn's icy satellites is trapped (Cruikshank et al., 2010, Icarus v206 p561; Pinilla-Alonso et al. 2011, Icarus v211, p75i), predominantly in the dark material (Clark et al. 2012, Icarus v218 p831). Clark et al. modeled the CO2 abundance as 2.8% on Iapetus and 3.7% on Phoebe. The main 12CO2 band in VIMS spectra on Iapetus occurs at 4.253 microns and Phoebe at 4.266 microns. The 13CO2 absorption is strong on Phoebe at 4.367 microns and weak on Iapetus at 4.387 microns. Converting the Phoebe, Iapetus, and a lab reflectance spectrum (of trace H2O-CO2 mixture on a diffuse substrate), we derive preliminary values for the ratio of the equivalent widths of the 12C and 13C absorptions as 19±2 on Phoebe, 82±8 on Iapetus, and 98±10 for the laboratory spectrum. These ratios are related to the 12C/13C ratio, but there may be effects due to intra-molecular and inter-molecular coupling that will contribute to systematic errors in the isotopic abundances derived using equivalent-width measurements that we've yet to quantify. We Believe the effects are small, and will be attempting to quantify them in the future. For comparison, the terrestrial value of the 12C/13C ratio is 90.17, and vibrational coupling may explain the slightly high lab mixture result. The local interstellar medium is 69±15 (Boogert et al., 2000, A&A). Because the CO2 bands on Phoebe and Iapetus dark material have different positions, and because the observed 13C absorption strengths are so different, the surface evolutions must be different. The large enrichment in 13C on Phoebe argues for significant

  11. Using Subsurface CO2 Concentrations and Isotopologues to Identify CO2 Seepage from CCS/CO2-EOR Projects: A Signal-to-Noise Based Analysis

    Science.gov (United States)

    Nickerson, N. R.; Risk, D. A.

    2012-12-01

    In order to fulfill a role in demonstrating containment, surface monitoring for Carbon Capture and Geologic Storage (CCS) sites must be able to clearly discriminate between natural, and leakage-source CO2. The CCS community lacks a clear metric for quantifying the degree of discrimination, for successful inter-comparison of monitoring approaches. This study illustrates the utility of Signal-to-Noise Ratio (SNR) to compare the relative performance of three commonly used soil gas monitoring approaches, including bulk CO2, δ13CO2, and Δ14CO2. For inter-comparisons, we used a simulated northern temperate landscape similar to that of Weyburn, Saskatchewan (home of the IEAGHG Weyburn-Midale CO2 Monitoring and Storage Project), in which realistic spatial and temporal CO2 and isotopic variation is simulated for periods of one year or more. Results indicate, that, for this particular ecosystem, Δ14C signatures have the best overall SNR at all simulated seepage rates, and for all points across the synthetic landscape. We then apply this same SNR based approach to data collected during a 6-month sampling campaign at three locations on the Weyburn oil field. This study emphasizes both the importance of developing clear metrics for monitoring performance, and the benefit of modeling for decision support in CCS monitoring design.

  12. Stable carbon isotopes to monitor the CO2 source mix in the urban environment

    Science.gov (United States)

    Vogel, F. R.; Wu, L.; Ramonet, M.; Broquet, G.; Worthy, D. E. J.

    2014-12-01

    Urban areas are said to be responsible for approximately 71% of fossil fuel CO2 emissions while comprising only two percent of the land area [IEA, 2008]. This limited spatial expansion could facility a monitoring of anthropogenic GHGs from atmospheric observations. As major sources of emissions, cities also have a huge potential to drive emissions reductions. To effectively manage emissions, cities must however, first establish techniques to validate their reported emission statistics. A pilot study which includes continues 13CO2 data from calibrated cavity ring-down spectrometers [Vogel et al. 2013] of two "sister sites" in the vicinity of Toronto, Canada is contrasted to recent observations of 13CO2 observations in Paris during significant pollution events. Using Miller-Tans plots [Miller and Tans, 2003] for our multi-season observations reveals significant changes of the source signatures of night time CO2 emissions which reflect the importance of natural gas burning in Megacities (up to 80% of fossil fuel sources) and show-case the potential of future isotope studies to determine source sectors. Especially the winter data this approach seems suitable to determine the source contribution of different fuel types (natural gas, liquid fuels and coal) which can inform the interpretation of other Greenhouse Gases and air pollution levels.

  13. Photodissociation spectroscopy of the Mg + -CO2 complex and its isotopic analogs

    Science.gov (United States)

    Yeh, C. S.; Willey, K. F.; Robbins, D. L.; Pilgrim, J. S.; Duncan, M. A.

    1993-02-01

    Mg+-CO2 ion-molecule cluster complexes are produced by laser vaporization in a pulsed nozzle cluster source. The vibronic spectroscopy in these complexes is studied with mass-selected photodissociation spectroscopy in a reflectron time-of-flight mass spectrometer. Two excited electronic states are observed (2) 2Σ+ and 2Π. The 2Π state has a vibrational progression in the metal-CO2 stretching mode (ωe'=381.8 cm-1). The complexes are linear (Mg+-OCO) and are bound by the charge-quadrupole interaction. The dissociation energy (D0`) is 14.7 kcal/mol. Corresponding spectra are measured for each of the 24, 25, and 26 isotopes of magnesium. These results are compared to theoretical predictions made by Bauschlicher and co-workers.

  14. A multi-layer, closed-loop system for continuous measurement of soil CO2 concentrations and its isotopic signature applied in a beech and a pine forest

    Science.gov (United States)

    Jochheim, Hubert; Wirth, Stephan

    2016-04-01

    We present a setup of measurement devices that allows the application of the soil CO2 gradient approach for CO2 efflux calculation in combination with the analysis of isotopic signature (δ13C). Vertical profiles of CO2 concentrations in air-filled pores of soil were measured using miniature NDIR sensors within a 16-channel closed-loop system where equilibrium with soil air can be achieved using hydrophobic, gas-permeable porous polypropylene tubes circulating gas using peristaltic pumps. A 16-position multiplexer allows the connection to an isotopic CO2 analyser. This setup was applied at two ICP Forest intensive monitoring sites, a beech and a pine forest on sandy soils located in Brandenburg, Germany. CO2 concentrations in air-filled pores of soils were measured on top of soil surface, below the humus layer, and in 10cm, 20cm, 30cm and 100 cm depths every 30 min. At both sites, soil moisture and temperature were measured continuously in the respective soil depths in identical time intervals. Isotopic signatures of soil CO2 was detected by measurement campaigns. After three years of measurements, our results provided evidence for distinct seasonal dynamics and vertical gradients of soil CO2 concentration and δ13C values. Varying impacts of soil temperature and moisture on CO2 concentration were revealed, highlighting its impact on soil physical and soil biological controls. Higher levels of CO2 concentration and a more distinct seasonal dynamics were detected at the beech site compared to the pine site. The collected data provide a suitable database for calculation of CO2 efflux and modelling of soil respiration.

  15. Triple oxygen isotope evidence for elevated CO2 levels after a Neoproterozoic glaciation.

    Science.gov (United States)

    Bao, Huiming; Lyons, J R; Zhou, Chuanming

    2008-05-22

    Understanding the composition of the atmosphere over geological time is critical to understanding the history of the Earth system, as the atmosphere is closely linked to the lithosphere, hydrosphere and biosphere. Although much of the history of the lithosphere and hydrosphere is contained in rock and mineral records, corresponding information about the atmosphere is scarce and elusive owing to the lack of direct records. Geologists have used sedimentary minerals, fossils and geochemical models to place constraints on the concentrations of carbon dioxide, oxygen or methane in the past. Here we show that the triple oxygen isotope composition of sulphate from ancient evaporites and barites shows variable negative oxygen-17 isotope anomalies over the past 750 million years. We propose that these anomalies track those of atmospheric oxygen and in turn reflect the partial pressure of carbon dioxide (P(CO2)) in the past through a photochemical reaction network linking stratospheric ozone to carbon dioxide and to oxygen. Our results suggest that P(CO2) was much higher in the early Cambrian than in younger eras, agreeing with previous modelling results. We also find that the (17)O isotope anomalies of barites from Marinoan (approximately 635 million years ago) cap carbonates display a distinct negative spike (around -0.70 per thousand), suggesting that by the time barite was precipitating in the immediate aftermath of a Neoproterozoic global glaciation, the P(CO2) was at its highest level in the past 750 million years. Our finding is consistent with the 'snowball Earth' hypothesis and/or a massive methane release after the Marinoan glaciation.

  16. Stable carbon isotope fractionation of organic cyst-forming dinoflagellates : Evaluating the potential for a CO2 proxy

    NARCIS (Netherlands)

    Hoins, Mirja; Van de Waal, Dedmer B.; Eberlein, Tim; Reichart, Gert Jan; Rost, Björn; Sluijs, Appy

    2015-01-01

    Over the past decades, significant progress has been made regarding the quantification and mechanistic understanding of stable carbon isotope fractionation (13C fractionation) in photosynthetic unicellular organisms in response to changes in the partial pressure of atmospheric CO2 (pCO2). However, h

  17. Stable carbon isotope fractionation of organic cyst-forming dinoflagellates: evaluating the potential for a CO2 proxy

    NARCIS (Netherlands)

    Hoins, Mirja; Van de Waal, Dedmer B.; Eberlein, Tim; Reichart, Gert-Jan; Rost, Björn; Sluijs, Appy

    2015-01-01

    Over the past decades, significant progress has been made regarding the quantification and mechanistic understanding of stable carbon isotope fractionation (13C fractionation) in photosynthetic unicellular organisms in response to changes in the partial pressure of atmospheric CO2 (pCO2). However, h

  18. 13CO2/12CO2 ratio analysis in exhaled air by lead-salt tunable diode lasers for noninvasive diagnostics in gastroenterology

    Science.gov (United States)

    Stepanov, Eugene V.; Zyrianov, Pavel V.; Miliaev, Valerii A.; Selivanov, Yurii G.; Chizhevskii, Eugene G.; Os'kina, Svetlana; Ivashkin, Vladimir T.; Nikitina, Elena I.

    1999-07-01

    An analyzer of 13CO2/12CO2 ratio in exhaled air based on lead-salt tunable diode lasers is presented. High accuracy of the carbon isotope ratio detection in exhaled carbon dioxide was achieved with help of very simple optical schematics. It was based on the use of MBE laser diodes operating in pulse mode and on recording the resonance CO2 absorption at 4.2 micrometers . Special fast acquisition electronics and software were applied for spectral data collection and processing. Developed laser system was tested in a clinical train aimed to assessment eradication efficiency in therapy of gastritis associated with Helicobacter pylori infection. Data on the 13C-urea breath test used for P.pylori detection and obtained with tunable diode lasers in the course of the trail was compared with the results of Mass-Spectroscopy analysis and histology observations. The analyzer can be used also for 13CO2/12CO2 ratio detection in exhalation to perform gastroenterology breath test based on using other compounds labeled with stable isotopes.

  19. Isotope ratios of H, C, and O in CO2 and H2O of the martian atmosphere.

    Science.gov (United States)

    Webster, Chris R; Mahaffy, Paul R; Flesch, Gregory J; Niles, Paul B; Jones, John H; Leshin, Laurie A; Atreya, Sushil K; Stern, Jennifer C; Christensen, Lance E; Owen, Tobias; Franz, Heather; Pepin, Robert O; Steele, Andrew; Achilles, Cherie; Agard, Christophe; Alves Verdasca, José Alexandre; Anderson, Robert; Anderson, Ryan; Archer, Doug; Armiens-Aparicio, Carlos; Arvidson, Ray; Atlaskin, Evgeny; Aubrey, Andrew; Baker, Burt; Baker, Michael; Balic-Zunic, Tonci; Baratoux, David; Baroukh, Julien; Barraclough, Bruce; Bean, Keri; Beegle, Luther; Behar, Alberto; Bell, James; Bender, Steve; Benna, Mehdi; Bentz, Jennifer; Berger, Gilles; Berger, Jeff; Berman, Daniel; Bish, David; Blake, David F; Blanco Avalos, Juan J; Blaney, Diana; Blank, Jen; Blau, Hannah; Bleacher, Lora; Boehm, Eckart; Botta, Oliver; Böttcher, Stephan; Boucher, Thomas; Bower, Hannah; Boyd, Nick; Boynton, Bill; Breves, Elly; Bridges, John; Bridges, Nathan; Brinckerhoff, William; Brinza, David; Bristow, Thomas; Brunet, Claude; Brunner, Anna; Brunner, Will; Buch, Arnaud; Bullock, Mark; Burmeister, Sönke; Cabane, Michel; Calef, Fred; Cameron, James; Campbell, John; Cantor, Bruce; Caplinger, Michael; Caride Rodríguez, Javier; Carmosino, Marco; Carrasco Blázquez, Isaías; Charpentier, Antoine; Chipera, Steve; Choi, David; Clark, Benton; Clegg, Sam; Cleghorn, Timothy; Cloutis, Ed; Cody, George; Coll, Patrice; Conrad, Pamela; Coscia, David; Cousin, Agnès; Cremers, David; Crisp, Joy; Cros, Alain; Cucinotta, Frank; d'Uston, Claude; Davis, Scott; Day, Mackenzie; de la Torre Juarez, Manuel; DeFlores, Lauren; DeLapp, Dorothea; DeMarines, Julia; DesMarais, David; Dietrich, William; Dingler, Robert; Donny, Christophe; Downs, Bob; Drake, Darrell; Dromart, Gilles; Dupont, Audrey; Duston, Brian; Dworkin, Jason; Dyar, M Darby; Edgar, Lauren; Edgett, Kenneth; Edwards, Christopher; Edwards, Laurence; Ehlmann, Bethany; Ehresmann, Bent; Eigenbrode, Jen; Elliott, Beverley; Elliott, Harvey; Ewing, Ryan; Fabre, Cécile; Fairén, Alberto; Farley, Ken; Farmer, Jack; Fassett, Caleb; Favot, Laurent; Fay, Donald; Fedosov, Fedor; Feldman, Jason; Feldman, Sabrina; Fisk, Marty; Fitzgibbon, Mike; Floyd, Melissa; Flückiger, Lorenzo; Forni, Olivier; Fraeman, Abby; Francis, Raymond; François, Pascaline; Freissinet, Caroline; French, Katherine Louise; Frydenvang, Jens; Gaboriaud, Alain; Gailhanou, Marc; Garvin, James; Gasnault, Olivier; Geffroy, Claude; Gellert, Ralf; Genzer, Maria; Glavin, Daniel; Godber, Austin; Goesmann, Fred; Goetz, Walter; Golovin, Dmitry; Gómez Gómez, Felipe; Gómez-Elvira, Javier; Gondet, Brigitte; Gordon, Suzanne; Gorevan, Stephen; Grant, John; Griffes, Jennifer; Grinspoon, David; Grotzinger, John; Guillemot, Philippe; Guo, Jingnan; Gupta, Sanjeev; Guzewich, Scott; Haberle, Robert; Halleaux, Douglas; Hallet, Bernard; Hamilton, Vicky; Hardgrove, Craig; Harker, David; Harpold, Daniel; Harri, Ari-Matti; Harshman, Karl; Hassler, Donald; Haukka, Harri; Hayes, Alex; Herkenhoff, Ken; Herrera, Paul; Hettrich, Sebastian; Heydari, Ezat; Hipkin, Victoria; Hoehler, Tori; Hollingsworth, Jeff; Hudgins, Judy; Huntress, Wesley; Hurowitz, Joel; Hviid, Stubbe; Iagnemma, Karl; Indyk, Steve; Israël, Guy; Jackson, Ryan; Jacob, Samantha; Jakosky, Bruce; Jensen, Elsa; Jensen, Jaqueline Kløvgaard; Johnson, Jeffrey; Johnson, Micah; Johnstone, Steve; Jones, Andrea; Joseph, Jonathan; Jun, Insoo; Kah, Linda; Kahanpää, Henrik; Kahre, Melinda; Karpushkina, Natalya; Kasprzak, Wayne; Kauhanen, Janne; Keely, Leslie; Kemppinen, Osku; Keymeulen, Didier; Kim, Myung-Hee; Kinch, Kjartan; King, Penny; Kirkland, Laurel; Kocurek, Gary; Koefoed, Asmus; Köhler, Jan; Kortmann, Onno; Kozyrev, Alexander; Krezoski, Jill; Krysak, Daniel; Kuzmin, Ruslan; Lacour, Jean Luc; Lafaille, Vivian; Langevin, Yves; Lanza, Nina; Lasue, Jeremie; Le Mouélic, Stéphane; Lee, Ella Mae; Lee, Qiu-Mei; Lees, David; Lefavor, Matthew; Lemmon, Mark; Lepinette Malvitte, Alain; Léveillé, Richard; Lewin-Carpintier, Éric; Lewis, Kevin; Li, Shuai; Lipkaman, Leslie; Little, Cynthia; Litvak, Maxim; Lorigny, Eric; Lugmair, Guenter; Lundberg, Angela; Lyness, Eric; Madsen, Morten; Maki, Justin; Malakhov, Alexey; Malespin, Charles; Malin, Michael; Mangold, Nicolas; Manhes, Gérard; Manning, Heidi; Marchand, Geneviève; Marín Jiménez, Mercedes; Martín García, César; Martin, Dave; Martin, Mildred; Martínez-Frías, Jesús; Martín-Soler, Javier; Martín-Torres, F Javier; Mauchien, Patrick; Maurice, Sylvestre; McAdam, Amy; McCartney, Elaina; McConnochie, Timothy; McCullough, Emily; McEwan, Ian; McKay, Christopher; McLennan, Scott; McNair, Sean; Melikechi, Noureddine; Meslin, Pierre-Yves; Meyer, Michael; Mezzacappa, Alissa; Miller, Hayden; Miller, Kristen; Milliken, Ralph; Ming, Douglas; Minitti, Michelle; Mischna, Michael; Mitrofanov, Igor; Moersch, Jeff; Mokrousov, Maxim; Molina Jurado, Antonio; Moores, John; Mora-Sotomayor, Luis; Morookian, John Michael; Morris, Richard; Morrison, Shaunna; Mueller-Mellin, Reinhold; Muller, Jan-Peter; Muñoz Caro, Guillermo; Nachon, Marion; Navarro López, Sara; Navarro-González, Rafael; Nealson, Kenneth; Nefian, Ara; Nelson, Tony; Newcombe, Megan; Newman, Claire; Newsom, Horton; Nikiforov, Sergey; Nixon, Brian; Noe Dobrea, Eldar; Nolan, Thomas; Oehler, Dorothy; Ollila, Ann; Olson, Timothy; de Pablo Hernández, Miguel Ángel; Paillet, Alexis; Pallier, Etienne; Palucis, Marisa; Parker, Timothy; Parot, Yann; Patel, Kiran; Paton, Mark; Paulsen, Gale; Pavlov, Alex; Pavri, Betina; Peinado-González, Verónica; Peret, Laurent; Perez, Rene; Perrett, Glynis; Peterson, Joe; Pilorget, Cedric; Pinet, Patrick; Pla-García, Jorge; Plante, Ianik; Poitrasson, Franck; Polkko, Jouni; Popa, Radu; Posiolova, Liliya; Posner, Arik; Pradler, Irina; Prats, Benito; Prokhorov, Vasily; Purdy, Sharon Wilson; Raaen, Eric; Radziemski, Leon; Rafkin, Scot; Ramos, Miguel; Rampe, Elizabeth; Raulin, François; Ravine, Michael; Reitz, Günther; Rennó, Nilton; Rice, Melissa; Richardson, Mark; Robert, François; Robertson, Kevin; Rodriguez Manfredi, José Antonio; Romeral-Planelló, Julio J; Rowland, Scott; Rubin, David; Saccoccio, Muriel; Salamon, Andrew; Sandoval, Jennifer; Sanin, Anton; Sans Fuentes, Sara Alejandra; Saper, Lee; Sarrazin, Philippe; Sautter, Violaine; Savijärvi, Hannu; Schieber, Juergen; Schmidt, Mariek; Schmidt, Walter; Scholes, Daniel; Schoppers, Marcel; Schröder, Susanne; Schwenzer, Susanne; Sebastian Martinez, Eduardo; Sengstacken, Aaron; Shterts, Ruslan; Siebach, Kirsten; Siili, Tero; Simmonds, Jeff; Sirven, Jean-Baptiste; Slavney, Susie; Sletten, Ronald; Smith, Michael; Sobrón Sánchez, Pablo; Spanovich, Nicole; Spray, John; Squyres, Steven; Stack, Katie; Stalport, Fabien; Stein, Thomas; Stewart, Noel; Stipp, Susan Louise Svane; Stoiber, Kevin; Stolper, Ed; Sucharski, Bob; Sullivan, Rob; Summons, Roger; Sumner, Dawn; Sun, Vivian; Supulver, Kimberley; Sutter, Brad; Szopa, Cyril; Tan, Florence; Tate, Christopher; Teinturier, Samuel; ten Kate, Inge; Thomas, Peter; Thompson, Lucy; Tokar, Robert; Toplis, Mike; Torres Redondo, Josefina; Trainer, Melissa; Treiman, Allan; Tretyakov, Vladislav; Urqui-O'Callaghan, Roser; Van Beek, Jason; Van Beek, Tessa; VanBommel, Scott; Vaniman, David; Varenikov, Alexey; Vasavada, Ashwin; Vasconcelos, Paulo; Vicenzi, Edward; Vostrukhin, Andrey; Voytek, Mary; Wadhwa, Meenakshi; Ward, Jennifer; Weigle, Eddie; Wellington, Danika; Westall, Frances; Wiens, Roger Craig; Wilhelm, Mary Beth; Williams, Amy; Williams, Joshua; Williams, Rebecca; Williams, Richard B; Wilson, Mike; Wimmer-Schweingruber, Robert; Wolff, Mike; Wong, Mike; Wray, James; Wu, Megan; Yana, Charles; Yen, Albert; Yingst, Aileen; Zeitlin, Cary; Zimdar, Robert; Zorzano Mier, María-Paz

    2013-07-19

    Stable isotope ratios of H, C, and O are powerful indicators of a wide variety of planetary geophysical processes, and for Mars they reveal the record of loss of its atmosphere and subsequent interactions with its surface such as carbonate formation. We report in situ measurements of the isotopic ratios of D/H and (18)O/(16)O in water and (13)C/(12)C, (18)O/(16)O, (17)O/(16)O, and (13)C(18)O/(12)C(16)O in carbon dioxide, made in the martian atmosphere at Gale Crater from the Curiosity rover using the Sample Analysis at Mars (SAM)'s tunable laser spectrometer (TLS). Comparison between our measurements in the modern atmosphere and those of martian meteorites such as ALH 84001 implies that the martian reservoirs of CO2 and H2O were largely established ~4 billion years ago, but that atmospheric loss or surface interaction may be still ongoing.

  20. Is there a stable isotope evidence for the CO2 fertiliser effect

    Indian Academy of Sciences (India)

    R V Krishnamurthy; M Machavaram

    2000-03-01

    It has been suggested that part of the so-called ``missing sink" of carbon dioxide introduced into the atmosphere by anthropogenic activities, that is the imbalance between estimated anthropogenic carbon dioxide emissions and oceanic uptake, may be stored in the vegetation in midlatitudes. Precise mecha- nisms of abstraction of additional carbon dioxide by vegetation, also known as the ``fertilization effect", are poorly understood. Stable carbon and hydrogen isotope ratios of cellulose extracted from annual growth rings (covering the time period 1980-1993) in an oak tree from Kalamazoo, SW Michigan provide a basis to investigate at a physiological level how the fertilization effect may operate. The carbon isotope ratios show that the intercellular concentration of carbon dioxide increased due to an increase in stomatal opening. Although increased intercellular concentration of carbon dioxide translated to increased Water Use Efficiency and assimilation rates, it also resulted in increased transpiration rate as shown by higher D/H of the fixed carbon. The two-fold significance of the isotope data are: first, they provide the first field evidence based on isotope studies for excess CO2 induced biomass production and second, they suggest that this mechanism is likely to operate only in limited environments. Vegetation in regions where mois- ture availability is not restricted so that there can be a gain in water use efficiency despite increased leaf evaporation are best suited to sequester excess carbon from the atmosphere.

  1. European interlaboratory comparison of breath (CO2)-C-13 analysis

    NARCIS (Netherlands)

    Stellaard, F; Geypens, B

    1998-01-01

    The BIOMED I programme Stable Isotopes in Gastroenterology and Nutrition (SIGN) has focused upon evaluation and standardisation of stable isotope breath tests using C-13 labelled substrates. The programme dealt with comparison of C-13 substrates, test meats, test conditions, analysis techniques, and

  2. Tracking isotopic signatures of CO2 at Jungfraujoch with laser spectroscopy: analytical improvements and exemplary results

    Directory of Open Access Journals (Sweden)

    L. Emmenegger

    2013-01-01

    Full Text Available We present the continuous data record of atmospheric CO2 isotopes measured by laser absorption spectroscopy for an almost four year period at the High Altitude Research Station Jungfraujoch (3580 m a.s.l., Switzerland. The mean annual cycles derived from data of December 2008 to September 2012 exhibit peak-to-peak amplitudes of 11.0 μmol mol−1 for CO2, 0.60‰ for δ13C and 0.81‰ for δ18O. The high temporal resolution of the measurements also allow to capture variations on hourly and diurnal time scales. For CO2 the mean diurnal peak-to-peak amplitude is about 1 μmol mol−1 in spring, autumn and winter and about 2 μmol mol−1 in summer. The mean diurnal variability in the isotope ratios is largest during the summer months too, with an amplitude of about 0.1‰ both in the δ13C and δ18O, and a smaller or no discernible diurnal cycle during the other seasons. The day-to-day variability, however, is much larger and depends on the origin of the air masses arriving at Jungfraujoch. Backward Lagrangian particle dispersion model simulations revealed a close link between air composition and prevailing transport regimes and could be used to explain part of the observed variability in terms of transport history and influence region. A footprint clustering showed significantly different wintertime CO2, δ13C and δ18O values depending on the origin and surface residence times of the air masses. Based on the experiences gained from our measurements, several major updates on the instrument and the calibration procedures were performed in order to further improve the data quality. We describe the new measurement and calibration setup in detail and demonstrate the enhanced performance of the analyser. A precision of about 0.02‰ for both isotope ratios has been obtained for an averaging time of 10 min.

  3. Multikilowatt TEA-CO2 laser system for molecular laser isotope separation

    Science.gov (United States)

    Ronander, Einar; Rohwer, Erich G.

    1993-05-01

    Laser-induced chemistry has received much attention in the past few years. The economics of such applications are dominated by the costs of photons and the quantum yield of the specific reaction. For a typical multiple-IR-photon process the quantum yield can be as low as 10-4 which emphasizes the importance of reducing the cost of laser photons. Based on 1982 technology, CO2 TEA laser operating costs were approximately $100/watt per year for a laser with an electrical efficiency of 6% and an average power of more than 100 kW. Capital costs dominated the energy cost as well as the maintenance and labor costs. At the South African Atomic Energy Corp. we have been involved in the development of high pulse frequency, high average power TEA-CO2 lasers for the application in the field of laser-induced chemistry. Much of the attention, however, has been focused on the application to separate the isotopes of uranium via a multiwavelength infrared irradiation scheme. The progress that has been made towards the establishment of CO2-lasers and laser chains for industrial use has been quite outstanding.

  4. Clumped isotopes in near-surface atmospheric CO2 over land, coast and ocean in Taiwan and its vicinity

    Science.gov (United States)

    Hussain Laskar, Amzad; Liang, Mao-Chang

    2016-09-01

    Molecules containing two rare isotopes (e.g., 13C18O16O in CO2), called clumped isotopes, in atmospheric CO2 are powerful tools to provide an alternative way to independently constrain the sources of CO2 in the atmosphere because of their unique physical and chemical properties. We presented clumped isotope data (Δ47) in near-surface atmospheric CO2 from urban, suburban, ocean, coast, high mountain ( ˜ 3.2 km a.s.l.) and forest in Taiwan and its vicinity. The primary goal of the study was to use the unique Δ47 signature in atmospheric CO2 to show the extents of its deviations from thermodynamic equilibrium due to different processes such as photosynthesis, respiration and local anthropogenic emissions, which the commonly used tracers such as δ13C and δ18O cannot provide. We also explored the potential of Δ47 to identify/quantify the contribution of CO2 from various sources. Atmospheric CO2 over ocean was found to be in thermodynamic equilibrium with the surrounding surface sea water. Respired CO2 was also in close thermodynamic equilibrium at ambient air temperature. In contrast, photosynthetic activity result in significant deviation in Δ47 values from that expected thermodynamically. The disequilibrium could be a consequence of kinetic effects associated with the diffusion of CO2 in and out of the leaf stomata. We observed that δ18O and Δ47 do not vary similarly when photosynthesis was involved unlike simple water-CO2 exchange. Additionally we obtained Δ47 values of car exhaust CO2 that were significantly lower than the atmospheric CO2 but higher than that expected at the combustion temperature. In urban and suburban regions, the Δ47 values were found to be lower than the thermodynamic equilibrium values at the ambient temperature, suggesting contributions from local combustion emission.

  5. Re-examining the reliability of tree-ring isotope ratio as a his- torical CO2 proxy

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    To examine the reliability of using tree ring d 13C and the modelof isotopic fractionation in reconstructing atmospheric CO2 levels, we studied the variations of some important parameters of several subtropical species under natural field conditions. It was found that, different from other researchers' results, leaf conductance to CO2 transfer, g, did not change in proportion to the change in rate of CO2 assimilation, A, with the result that intercellular concen- tration of CO2, Ci, could not keep constant. Thus, we con-clude that the use of tree-ring isotope ratios in the recon-struction of atmospheric CO2 variation based on the presup-position that Ci keeps constant during assimilation is not reliable under current circumstances.

  6. CO2 efflux from a calcareous Mojave Desert soil: isotopic results from a laboratory and field study

    Science.gov (United States)

    Verburg, P.; Stevenson, B.

    2011-12-01

    Soil inorganic carbon (SIC) represents a substantial C pool in arid ecosystems. The contribution of the SIC pool to net ecosystem C flux is poorly understood but has gained attention because there have been reports of anomalous C fluxes in some arid environments. In the context of climate change, altered precipitation patterns and changes in soil pCO2 values (from changes in vegetation density, plant water use efficiency, and belowground respiration) could potentially affect SIC storage in some ecosystems. The stable carbon isotope values of organic and inorganic carbon (e.g. carbonates) can differ substantially and may be useful in determining whether PIC influences C fluxes. However, variable rates of heterotrophic and root respiration and diffusion of atmospheric CO2 into the soil as well as the variation and complexity of the CaCO3-CO2-H2O system at different soil depths can complicate interpretation of isotopic data. We monitored soil CO2 concentrations and CO2 efflux from irrigated and non-irrigated plots in a calcareous soil at the Mojave Global Change Facility (MGCF). The site is on the northern part of the Mojave Desert with a mean annual precipitation of 71 mm and vegetation characterized by a Larrea tridentata, Lycium spp., Ambrosia dumosa plant community. We used a Keeling plot approach to determine source δ13C values from effluxed CO2-13C in a laboratory incubation experiment and from direct field measurements of soil CO2-13C. Data from the laboratory incubation experiment suggested that there was a contribution of PIC on effluxed CO2-13C in a closed system, but results from the field measurements were much more difficult to interpret and did not support a large contribution of SIC to CO2 fluxes in these soils. We discuss the usefulness of isotopic measure of CO2 on CO2 efflux in the context of the MGCF experiment.

  7. The carbon and oxygen isotope records of reef-dwelling foraminifers subjected to five varied pCO2 seawater

    Science.gov (United States)

    Hikami, M.; Ishimura, T.; Suzuki, A.; Nojiri, Y.; Kawahata, H.

    2013-12-01

    Ocean acidification (OA) in response to rising atmospheric pCO2 is generally expected to reduce rates of calcification by reef calcifying organisms, with potentially severe implications for coral reef ecosystems. Reef dwelling foraminifera is one of the most important primary and carbonate producers in coral reef environments. Their shells are composed of high-Mg calcite and they are host to algal endosymbionts. In our previous culture experiment with two algal reef dwelling foraminifers, Amphisorus kudakajimensis and Calcarina gaudichaudii in the seawater of five different pCO2 conditions, net calcification of A. kudakajimensis was reduced under higher pCO2, whereas net calcification of C. gaudichaudii showed continued increasing trend with pCO2. These contrasting responses between the two species are possibly due to differences in calcification mechanisms and to links between calcification by the foraminifers and photosynthesis by the algal endosymbionts. But the factors affecting these calcification mechanisms are poorly understood. In this study, to get a better understanding of the effect of OA on their calcification, we cultured three reef dwelling foraminifers: Amphisorus hemprichii, belong to imperforate species, Baculogypsina sphaerulata, and C. gaudichaudii belong to perforate species, in the seawater of five different pCO2 conditions and we address the response of carbon and oxygen isotopes of the carbonate shells of foraminifers. The oxygen isotope ratio of cultured foraminiferal tests under five varied pCO2 seawater indicated no significant correlation to pCO2 values. On the other hand, the carbon isotope ratio of foraminiferal tests indicated heavy trend with rising pCO2 in all species. Alteration of carbonate chemistry result from ocean acidification may be effect strongly on carbon isotope composition relate to metabolic system (i.e. photosynthesis and respiration). In perforate species, both of oxygen and carbon isotope ratio were lighter than that

  8. CO2 production by impact in carbonates? An ATEM and stable isotope (C,O) study

    Science.gov (United States)

    Martinez, I.; Agrinier, P.; Guyot, F.; Ildefonse, PH.; Javoy, M.; Schaerer, U.; Hornemann, U.; Deutsch, A.

    1993-01-01

    Carbonates may have been a common target for large impacts on the Earth and possible related CO2 outgassing would have important consequences for the composition of the atmosphere. To estimate volatile release during such impacts, isotopic ratios (C-13/C-12 and O-18/O-16) were determined on highly shocked carbonate samples in combination with SEM and analytical transmission electron microscopy (ATEM) investigations. The study was performed on both naturally and experimentally shocked rocks, i.e. 50-60 GPa shocked limestone-dolomite fragments from the Haughton impact crater (Canada), and carbonates shocked in shock recovery experiments. For the experiments, unshocked carbonates consisting of mixture of dolomite and calcite from the Haughton area were used. Naturally shocked samples were collected in the polymict breccia near the center of the Haughton crater.

  9. Methane Production Pathways in a California Rice Paddy: Isotopic Evidence for Substantial CO2 Reduction as Cause for Isotopically Light Emitted CH4 Carbon

    Science.gov (United States)

    Tyler, S. C.; McMillan, A. M.; Bearden, K.; Chidthaisong, A.; Macalady, J.

    2003-12-01

    We report measurements of δ 13C of emitted CH4 and sediment CH4 and CO2 during the 1999 rice-growing season near Maxwell, CA. Two treatments, one with rice straw incorporated from the previous season and one without rice straw were studied. The δ 13C value of emitted CH4 was consistently lighter isotopically (-67‰ to -83‰ throughout the season) in both straw incorporated and straw removed (burned) plots than in fields we have studied in Texas, Kenya, and Japan. Measured isotopic values of the production zone CH4 were compared to a two-point mixing curve representative of isotopic CH4 produced from either pure methyl-group fermentation or CO2 reduction pathways to partition the production pathways and to track seasonal changes in the production processes. Our sediment CH4 and CO2 isotope data indicate that fermentation was rarely the dominant methanogenic pathway - on the contrary CO2 reduction with H2 was more prevalent than fermentation methanogenesis throughout most of the season. The relatively isotopically light CH4 emitted by the paddy fields is also a product of oxidation and stem-transport processes which have isotopic effects of their own. These effects are discussed in context with the methanogenic isotope effects to provide a complete picture of the paddy field CH4 carbon isotope system.

  10. New constraints on kinetic isotope effects during CO2(aq) hydration and hydroxylation: Revisiting theoretical and experimental data

    Science.gov (United States)

    Sade, Ziv; Halevy, Itay

    2017-10-01

    CO2 (de)hydration (i.e., CO2 hydration/HCO3- dehydration) and (de)hydroxylation (i.e., CO2 hydroxylation/HCO3- dehydroxylation) are key reactions in the dissolved inorganic carbon (DIC) system. Kinetic isotope effects (KIEs) during these reactions are likely to be expressed in the DIC and recorded in carbonate minerals formed during CO2 degassing or dissolution of gaseous CO2. Thus, a better understanding of KIEs during CO2 (de)hydration and (de)hydroxylation would improve interpretations of disequilibrium compositions in carbonate minerals. To date, the literature lacks direct experimental constraints on most of the oxygen KIEs associated with these reactions. In addition, theoretical estimates describe oxygen KIEs during separate individual reactions. The KIEs of the related reverse reactions were neither derived directly nor calculated from a link to the equilibrium fractionation. Consequently, KIE estimates of experimental and theoretical studies have been difficult to compare. Here we revisit experimental and theoretical data to provide new constraints on oxygen KIEs during CO2 (de)hydration and (de)hydroxylation. For this purpose, we provide a clearer definition of the KIEs and relate them both to isotopic rate constants and equilibrium fractionations. Such relations are well founded in studies of single isotope source/sink reactions, but they have not been established for reactions that involve dual isotopic sources/sinks, such as CO2 (de)hydration and (de)hydroxylation. We apply the new quantitative constraints on the KIEs to investigate fractionations during simultaneous CaCO3 precipitation and HCO3- dehydration far from equilibrium.

  11. Correction for the 17O interference in δ(13C) measurements when analyzing CO2 with stable isotope mass spectrometry

    Science.gov (United States)

    Coplen, Tyler B.; Brand, Willi A.; Assonov, Sergey S.

    2010-01-01

    Measurements of δ(13C) determined on CO2 with an isotope-ratio mass spectrometer (IRMS) must be corrected for the amount of 17O in the CO2. For data consistency, this must be done using identical methods by different laboratories. This report aims at unifying data treatment for CO2 IRMS by proposing (i) a unified set of numerical values, and (ii) a unified correction algorithm, based on a simple, linear approximation formula. Because the oxygen of natural CO2 is derived mostly from the global water pool, it is recommended that a value of 0.528 be employed for the factor λ, which relates differences in 17O and 18O abundances. With the currently accepted N(13C)/N(12C) of 0.011 180(28) in VPDB (Vienna Peedee belemnite) reevaluation of data yields a value of 0.000 393(1) for the oxygen isotope ratio N(17O)/N(16O) of the evolved CO2. The ratio of these quantities, a ratio of isotope ratios, is essential for the 17O abundance correction: [N(17O)/N(16O)]/[N(13C)/N(12C)] = 0.035 16(8). The equation [δ(13C) ≈ 45δVPDB-CO2 + 2 17R/13R (45δVPDB-CO2 – λ46δVPDB-CO2)] closely approximates δ(13C) values with less than 0.010 ‰ deviation for normal oxygen-bearing materials and no more than 0.026 ‰ in extreme cases. Other materials containing oxygen of non-mass-dependent isotope composition require a more specific data treatment. A similar linear approximation is also suggested for δ(18O). The linear approximations are easy to implement in a data spreadsheet, and also help in generating a simplified uncertainty budget.

  12. Stable carbon isotope fractionation of organic cyst-forming dinoflagellates: Evaluating the potential for a CO2 proxy

    Science.gov (United States)

    Hoins, Mirja; Van de Waal, Dedmer B.; Eberlein, Tim; Reichart, Gert-Jan; Rost, Björn; Sluijs, Appy

    2015-07-01

    Over the past decades, significant progress has been made regarding the quantification and mechanistic understanding of stable carbon isotope fractionation (13C fractionation) in photosynthetic unicellular organisms in response to changes in the partial pressure of atmospheric CO2 (pCO2). However, hardly any data is available for organic cyst-forming dinoflagellates while this is an ecologically important group with a unique fossil record. We performed dilute batch experiments with four harmful dinoflagellate species known for their ability to form organic cysts: Alexandrium tamarense, Scrippsiella trochoidea, Gonyaulax spinifera and Protoceratium reticulatum. Cells were grown at a range of dissolved CO2 concentrations characterizing past, modern and projected future values (∼5-50 μmol L-1), representing atmospheric pCO2 of 180, 380, 800 and 1200 μatm. In all tested species, 13C fractionation depends on CO2 with a slope of up to 0.17‰ (μmol L)-1. Even more consistent correlations were found between 13C fractionation and the combined effects of particulate organic carbon quota (POC quota; pg C cell-1) and CO2. Carbon isotope fractionation as well as its response to CO2 is species-specific. These results may be interpreted as a first step towards a proxy for past pCO2 based on carbon isotope ratios of fossil organic dinoflagellate cysts. However, additional culture experiments focusing on environmental variables other than pCO2, physiological underpinning of the recorded response, testing for possible offsets in 13C values between cells and cysts, as well as field calibration studies are required to establish a reliable proxy.

  13. Explaining Dutch emissions of CO2; a decomposition analysis

    OpenAIRE

    Alex Hoen; Machiel Mulder

    2003-01-01

    Decomposition of CO2 data of the Netherlands shows that much progress has been made with reduction of CO2 emissions by changing to less CO2 intensive technologies. Moreover, demand shifted to products that are produced with less CO2 emission. Further, shifts in the inputs needed in the production process also managed to decrease the CO2 emissions. These effects, however, were more than compensated by increased CO2 emission due to economic growth. Especially growth in exports led to substantia...

  14. The 13C/12C isotopic signal of day-respired CO2 in variegated leaves of Pelargonium × hortorum.

    Science.gov (United States)

    Tcherkez, Guillaume; Mauve, Caroline; Lamothe, Marlene; Le Bras, Camille; Grapin, Agnes

    2011-02-01

    In leaves, although it is accepted that CO(2) evolved by dark respiration after illumination is naturally (13) C-enriched compared to organic matter or substrate sucrose, much uncertainty remains on whether day respiration produces (13) C-depleted or (13) C-enriched CO(2). Here, we applied equations described previously for mesocosm CO(2) exchange to investigate the carbon isotope composition of CO(2) respired by autotrophic and heterotrophic tissues of Pelargonium × hortorum leaves, taking advantage of leaf variegation. Day-respired CO(2) was slightly (13) C-depleted compared to organic matter both under 21% O(2) and 2% O(2). Furthermore, most, if not all CO(2) molecules evolved in the light came from carbon atoms that had been fixed previously before the experiments, in both variegated and green leaves. We conclude that the usual definition of day respiratory fractionation, that assumes carbon fixed by current net photosynthesis is the respiratory substrate, is not valid in Pelargonium leaves under our conditions. In variegated leaves, total organic matter was slightly (13) C-depleted in white areas and so were most primary metabolites. This small isotopic difference between white and green areas probably came from the small contribution of photosynthetic CO(2) refixation and the specific nitrogen metabolism in white leaf areas.

  15. Isotopic fractionation during carbon acquisition in dinoflagellates : a new proxy for pCO2?

    NARCIS (Netherlands)

    Hoins, M.

    2016-01-01

    Atmospheric CO2 concentrations (pCO2) have markedly changed over geological timescales, thereby considerably influencing Earth’s climate and ecosystems. Reconstructing pCO2 is therefore one of the major challenges for the scientific community today. This thesis aims at investigating if past pCO2 can

  16. Maintaining consistent traceability in high precision isotope measurements of CO2: verifying atmospheric trends of δ13C

    Directory of Open Access Journals (Sweden)

    Y.-S. Lee

    2012-06-01

    Full Text Available Maintaining consistent traceability of high precision measurements of CO2 isotopes is critical in being able to observe accurate atmospheric trends of δ13C (CO2. Although a number of laboratories/organizations around the world have been involved in baseline measurements of atmospheric CO2 isotopes for several decades, the reports on their traceability measures are rare. In this paper, a principle and an approach for the traceability maintenance of high precision isotope measurements (δ13C and δ18O in atmospheric CO2 is described. The uncertainties of the traceability have been estimated based on the history of annual calibrations over the last 10 yr. The overall uncertainties of CO2 isotope measurements for individual ambient samples carried out by our program at Environment Canada are estimated (excluding the uncertainty associated with the sampling. The values are 0.02‰ and 0.05‰ in δ13C and δ18O, respectively, close to the WMO targets for data compatibility. The annual rate of change in δ13C of the primary anchor used in our program (which is the laboratory standard linking ambient measurements back to the primary VPDB scale is close to zero (−0.0016 ± 0.0012‰ per year over the period of 10 yr (2001–2011. The average annual decreasing rate of δ13C in air CO2 measurements at Alert over the period from 1999 to 2010 has been confirmed and verified, which is −0.025 ± 0.003‰ per year. The total change of δ13C in the annual mean value during this period is ∼−0.27‰. The concept of "Big Delta" is introduced and its role in maintaining traceability of the isotope measurements is described and discussed extensively. Finally, the challenges and a strategy for maintaining traceability are also discussed and suggested.

  17. CO2 Leakage Identification in Geosequestration Based on Real Time Correlation Analysis Between Atmospheric O2 and CO2

    Institute of Scientific and Technical Information of China (English)

    马登龙; 邓建强; 张早校

    2014-01-01

    The paper describes a method for monitoring CO2 leakage in geological carbon dioxide sequestration. A real time monitoring parameter, apparent leakage flux (ALF), is presented to monitor abnormal CO2 leakage, which can be calculated by atmospheric CO2 and O2 data. The computation shows that all ALF values are close to zero-line without the leakage. With a step change or linear perturbation of concentration to the initial CO2 concen-tration data with no leakage, ALF will deviate from background line. Perturbation tests prove that ALF method is sensitive to linear perturbation but insensitive to step change of concentration. An improved method is proposed based on real time analysis of surplus CO2 concentration in least square regression process, called apparent leakage flux from surplus analysis (ALFs), which is sensitive to both step perturbation and linear perturbations of concen-tration. ALF is capable of detecting concentration increase when the leakage occurs while ALFs is useful in all pe-riods of leakage. Both ALF and ALFs are potential approaches to monitor CO2 leakage in geosequestration project.

  18. Measurements of CO2, its stable isotopes, O2/N2, and 222Rn at Bern, Switzerland

    Directory of Open Access Journals (Sweden)

    P. Sturm

    2006-01-01

    Full Text Available A one-year time series of atmospheric CO2 measurements from Bern, Switzerland, is presented. O2/N2 and Ar/N2 ratios as well as stable carbon and oxygen isotopes of CO2 and δ29N2, δ34O2 and δ36Ar were measured periodically during a one year period. Additionally, the 222Rn activity was measured during three months in the winter 2004. Using the correlation from short-term fluctuations of CO2 and 222Rn we estimated a mean CO2 flux density between February 2004 and April 2004 in the region of Bern of 95±39 tC km–2month–1. The continuous observations of carbon dioxide and associated tracers shed light on diurnal and seasonal patterns of the carbon cycle in an urban atmosphere. There is considerable variance in nighttime δ13C and δ18O of source CO2 throughout the year, however, with generally lower values in winter compared to summertime. The O2:CO2 oxidation ratio during the nighttime build-up of CO2 varies between –0.96 and –1.69 mol O2/mol CO2. Furthermore, Ar/N2 measurements showed that artifacts like thermal fractionation at the air intake are relevant for high precision measurements of atmospheric O2.

  19. THERMODYNAMIC ANALYSIS OF CO2 DIRECT HYDROGENATION REACTIONS

    Institute of Scientific and Technical Information of China (English)

    Cao Fahai; Liu Dianhua; Hou Qiushi; Fang Dingye

    2001-01-01

    CO2 hydrogenation is one of important routes for the activation and effective utilization of CO2. In this paper, eighteen CO2 direct hydrogenation reactions are listed and their reaction heats and equilibrium constants are calculated. On the assumption that the reactions of CO2 and H2 are in stoichiometric ratio and the amount of whole reactants is one mole, the equilibrium conversions of CO2 are obtained.

  20. Methane emission from rice: Stable isotopes, diurnal variations, and CO2 exchange

    Science.gov (United States)

    Chanton, J. P.; Whiting, G. J.; Blair, N. E.; Lindau, C. W.; Bollich, P. K.

    1997-03-01

    The importance of vegetation in supporting methane production and emission within flooded rice fields was demonstrated. Methane emission from Lousiana, United States, rice fields was correlated to the quantity of live aboveground biomass and the rate of CO2 exchange. The quantity of belowground methane was greater in vegetated plots relative to plots maintained free of vegetation. The diurnal maximum in the rate of methane emission was coincident with the release of the most 13C-enriched methane and a maximum in transpiration rate rather than stomatal conductance, suggesting that diurnal variations in methane emission rate are linked with transpiration, in addition to temperature. Results of isotopic measurements of belowground, lacunal, and emitted methane indicate that methane is transported from rice predominantly via molecular diffusion with a small component due to transpiration-induced bulk flow. Samples of methane collected from air-filled internal spaces within the rice culm were 13C-enriched (-53.1 ± 0.3‰) relative to emitted (-64.5 ± 1.0‰) and belowground methane (-59 ± 1.0‰) . Reproduction of these observed 13C values with a numerical model required isotopic fractionation effects associated with transport of methane into and from rice plants. The model could not conclusively confirm rhizospheric methane oxidation. However, 13C-enriched methane was observed in the floodwater overlying the flooded soil (-44.4 ± 2.2‰), consistent with the oxidation of substantial quantities of methane as it diffused across the soil-water interface.

  1. CO2 isotope analyses using large air samples collected on intercontinental flights by the CARIBIC Boeing 767

    NARCIS (Netherlands)

    Assonov, S.S.; Brenninkmeijer, C.A.M.; Koeppel, C.; Röckmann, T.

    2009-01-01

    Analytical details for 13C and 18O isotope analyses of atmospheric CO2 in large air samples are given. The large air samples of nominally 300 L were collected during the passenger aircraft-based atmospheric chemistry research project CARIBIC and analyzed for a large number of trace gases and

  2. High-Precision Instrumentation for CO2 Isotope Ratio Measurements Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Knowing atmospheric 13CO2/12CO2 ratios precisely is important to understanding biogenic and anthroprogenic sources and sinks for carbon. Currently available field...

  3. Sampling Soil CO2 for Isotopic Flux Partitioning: Non Steady State Effects and Methodological Biases

    Science.gov (United States)

    Snell, H. S. K.; Robinson, D.; Midwood, A. J.

    2014-12-01

    Measurements of δ13C of soil CO2 are used to partition the surface flux into autotrophic and heterotrophic components. Models predict that the δ13CO2 of the soil efflux is perturbed by non-steady state (NSS) diffusive conditions. These could be large enough to render δ13CO2 unsuitable for accurate flux partitioning. Field studies sometimes find correlations between efflux δ13CO2 and flux or temperature, or that efflux δ13CO2 is not correlated as expected with biological drivers. We tested whether NSS effects in semi-natural soil were comparable with those predicted. We compared chamber designs and their sensitivity to changes in efflux δ13CO2. In a natural soil mesocosm, we controlled temperature to generate NSS conditions of CO2 production. We measured the δ13C of soil CO2 using in situ probes to sample the subsurface, and dynamic and forced-diffusion chambers to sample the surface efflux. Over eight hours we raised soil temperature by 4.5 OC to increase microbial respiration. Subsurface CO2 concentration doubled, surface efflux became 13C-depleted by 1 ‰ and subsurface CO2 became 13C-enriched by around 2 ‰. Opposite changes occurred when temperature was lowered and CO2 production was decreasing. Different chamber designs had inherent biases but all detected similar changes in efflux δ13CO2, which were comparable to those predicted. Measurements using dynamic chambers were more 13C-enriched than expected, probably due to advection of CO2 into the chamber. In the mesocosm soil, δ13CO2 of both efflux and subsurface was determined by physical processes of CO2 production and diffusion. Steady state conditions are unlikely to prevail in the field, so spot measurements of δ13CO2 and assumptions based on the theoretical 4.4 ‰ diffusive fractionation will not be accurate for estimating source δ13CO2. Continuous measurements could be integrated over a period suitable to reduce the influence of transient NSS conditions. It will be difficult to disentangle

  4. Graphite-bearing CO 2-fluid inclusions in granulites: Insights on graphite precipitation and carbon isotope evolution

    Science.gov (United States)

    Satish-Kumar, Madhusoodhan

    2005-08-01

    Graphite in deep crustal enderbitic (orthopyroxene + garnet + plagioclase + quartz) granulites (740°C, 8.9 kb) of Nilgiri hills, southern India were investigated for their spectroscopic and isotopic characteristics. Four types of graphite crystals were identified. The first type (Gr I), which is interstitial to other mineral grains, can be grouped into two subtypes, Gr IA and Gr IB. Gr IA is either irregular in shape or deformed, and rough textured with average δ 13C values of -12.7 ± 0.4‰ ( n = 3). A later generation of interstitial graphite (Gr IB) shows polygonal crystal shapes and highly reflecting smooth surface features. These graphite grains are more common and have δ 13C values of -11.9 ± 0.3‰ ( n = 14). Both subtypes show well-defined Raman shifts suggesting a highly crystalline nature. Cores of interstitial graphite grains have, on average, lower δ 13C values by ˜0.5‰ compared to that of the rim. The second type of graphite (Gr II) occurs as solid inclusions in silicate minerals, commonly forming regular hexagonal crystals with a slightly disordered structure. The third type of graphite (Gr III) is associated with solid inclusions (up to 100 μm) that have decrepitation halos of numerous small (pure CO 2 with varying density (1.105 to 0.75 g/cm 3). The fourth type of graphite (Gr IV) is found as daughter crystals within primary type CO 2-fluid inclusions in garnet and quartz. These fluid inclusions have a range of densities (1.05 to 0.90 g/cm 3), but in general are significantly less dense than graphite-free primary, pure CO 2 fluid inclusions (1.12 g/cm 3). Raman spectral characteristics of graphite inside fluid inclusions suggest graphite crystallization at low temperature (˜ 500°C). The precipitation of graphite probably occurred during the isobaric cooling of CO 2-rich peak metamorphic fluid as a result of oxyexsolution of oxide phases. The oxyexsolution process is evidenced by the magnetite-ilmenite granular exsolution textures and the

  5. Carbon isotope systematics and CO2 sources in The Geysers-Clear Lake region, northern California, USA

    Science.gov (United States)

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

    2001-01-01

    Carbon isotope analyses of calcite veins, organic carbon, CO2 and CH4 from 96 rock and 46 gas samples show that metamorphic calcite veins and disseminated, organically-derived carbon from Franciscan Complex and Great Valley Sequence rocks have provided a primary carbon source for geothermal fluids during past and present hydrothermal activity across The Geysers-Clear Lake region. The stable isotope compositions of calcite veins vary widely on a regional scale, but overall they document the presence of 13C-poor fluids in early subduction-related vein-precipitating events. ??13C values of calcite veins from the SB-15-D corehole within The Geysers steam field indicate that carbon-bearing fluids in the recent geothermal system have caused the original diverse ??13C values of the veins to be reset. Across The Geysers-Clear Lake region the carbon isotope composition of CO2 gas associated with individual geothermal reservoirs shows a general increasing trend in ??13C values from west to east. In contrast, ??13C values of CH4 do not exhibit any spatial trends. The results from this study indicate that regional variations in ??13C-CO2 values result from differences in the underlying lithologies. Regional CO2 contains significant amounts of carbon related to degradation of organic carbon and dissolution of calcite veins and is not related to equilibrium reactions involving CH4. CO2 from degassing of underlying magma chambers is not recognizable in this region. Published by Elsevier Science Ltd on behalf of CNR.

  6. Dual stable isotopes of CH4 from Yellowstone hot-springs suggest hydrothermal processes involving magmatic CO2

    Science.gov (United States)

    Moran, James J.; Whitmore, Laura M.; Jay, Zackary J.; Jennings, Ryan deM.; Beam, Jacob P.; Kreuzer, Helen W.; Inskeep, William P.

    2017-07-01

    Volcanism and post-magmatism contribute significant annual methane (CH4) fluxes to the atmosphere (on par with other natural sources such as forest fire and wild animal emissions) and have been implicated in past climate-change events. The Yellowstone hot spot is one of the largest volcanic systems on Earth and is known to emit CH4 (as well as carbon dioxide (CO2) and other gases), but the ultimate sources of this CH4 flux have not been elucidated. Here we use dual stable isotope analysis (δ2H and δ13C) of CH4 sampled from ten high-temperature geothermal pools in Yellowstone National Park along with other isotopic and gas analyses to evaluate potential sources of methane. The average δ13C and δ2H values of CH4 emitted from hot springs (26.7 (± 2.4) and - 236.9 (± 12.0) ‰, respectively) are inconsistent with microbial methanogenesis but do not allow distinction between thermogenic and abiotic sources. Correlation between δ13CCH4 and δ13C of dissolved inorganic C (DIC) is consistent with DIC as the parent C source for the observed CH4, or with equilibration of CH4 and DIC. Methane formation temperatures estimated by isotopic geothermometry based on δ13CCH4 and δ13CCO2 ranged from 250-350 °C, which is just below previous temperature estimates for the hydrothermal reservoir. Further, the δ2HH2O of the thermal springs and the measured δ2HCH4 values are consistent with equilibration between the source water and the CH4 at the formation temperatures. Though the ultimate origin of the CH4 could be attributed to either abiotic of themorgenic processes with subsequent isotopic equilibration, the C1/C2 + composition of the gases is more consistent with abiotic origins for most of the samples. Thus, our data support the hypothesis that subsurface rock-water interactions are responsible for at least a significant fraction of the CH4 flux from the Yellowstone National Park volcanic system.

  7. Estimation of the efficiency of hydrocarbon mineralization in soil by measuring CO2-emission and variations in the isotope composition of carbon dioxide

    Science.gov (United States)

    Dubrovskaya, Ekaterina; Turkovskaya, Olga

    2010-05-01

    soil microbiota. The plants and microorganisms used had the isotopic signatures similar to that of the soil, whereas the δ13C of HD was -47.9‰. The HD mineralization level was assessed by determining the difference between the isotopic compositions of soil CO2 immediately after pollution and during remediation. In the unvegetated soil, about 13% of initially added HD was mineralized, the phytoremediation increased the total decomposition of the contaminant to 19%, and an additional plant inoculation with strain SR80 raised it to 33%. The GC analysis of soil demonstrated that contaminant loss in the plant treatments and in the inoculated plant treatment was 71 and 72%, respectively, whereas in the nonvegetated treatments, it was 64 and 66%, respectively. Thus, the elimination of the contaminant resulted from its total mineralization (CO2 emission) and partial chemical transformation.

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

    Science.gov (United States)

    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

  9. Performance analysis of CO2 laser polished angled ribbon fiber

    Science.gov (United States)

    Sohn, Ik-Bu; Choi, Hun-Kook; Noh, Young-Chul; Lee, Man-Seop; Oh, Jin-Kyoung; Kim, Seong-min; Ahsan, Md. Shamim

    2017-01-01

    This paper demonstrates CO2 laser assisted simultaneous polishing of angled ribbon fibers consisting eight set of optical fibers. The ribbon fibers were rotated vertically at an angle of 12° and polished by repetitive irradiation of CO2 laser beam at the end faces of the fibers. Compared to mechanically polished sharp edged angled fibers, CO2 laser polishing forms curve edged angled fibers. Increase in the curvature of the end faces of the ribbon fibers causes the increase of the fibers' strength, which in turn represents great robustness against fiber connections with other devices. The CO2 laser polished angled fibers have great smoothness throughout the polished area. The smoothness of the fiber end faces have been controlled by varying the number of laser irradiation. After CO2 laser polishing, the average value of the fiber angle of the ribbon fibers is ∼8.28°. The laser polished ribbon fibers show low insertion and return losses when connecting with commercial optical communication devices. The proposed technique of polishing the angled ribbon fibers is highly replicable and reliable and thus suitable for commercial applications.

  10. Changes in atmospheric CO2 levels recorded by the isotopic signature of n-alkanes from plants

    Science.gov (United States)

    Machado, Karina Scurupa; Froehner, Sandro

    2017-01-01

    The isotopic signature of sedimentary organic matter acts as a tracer for past changes in the terrestrial and aquatic carbon cycles. The temporal variation in δ13C values of n-alkanes from plants was assigned as resulting from changes in atmospheric composition in the study area, due to both global and local influences. Two rises in atmospheric CO2 concentration were assigned from the variation in n-alkane δ13C values for the periods between 1600 and 1880 and from 1930 to the present. In the first period, the sources of excess CO2 were predominantly natural, mainly volcanism, while in the second period local anthropogenic emissions were the major reason.

  11. Phytoplankton-bacteria coupling under elevated CO2 levels: a stable isotope labelling study

    NARCIS (Netherlands)

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

    2010-01-01

    The potential impact of rising carbon dioxide (CO2) on carbon transfer from phytoplankton to bacteria was investigated during the 2005 PeECE III mesocosm study in Bergen, Norway. Sets of mesocosms, in which a phytoplankton bloom was induced by nutrient addition, were incubated under 1× (~350 μatm),

  12. Studying biosphere-atmosphere exchange of CO2 through Carbon-13 stable isotopes

    NARCIS (Netherlands)

    Velde, van der I.R.

    2015-01-01

    Summary Thesis ‘Studying biosphere-atmosphere exchange of CO2 through carbon-13 stable isotopes’ Ivar van der Velde Making predictions of future climate is difficult, mainly due to large uncertainties in the carbon cycle. The rate at which carbon is stored in the oceans and terrestrial

  13. Wellbore integrity analysis of a natural CO2 producer

    KAUST Repository

    Crow, Walter

    2010-03-01

    Long-term integrity of existing wells in a CO2-rich environment is essential for ensuring that geological sequestration of CO2 will be an effective technology for mitigating greenhouse gas-induced climate change. The potential for wellbore leakage depends in part on the quality of the original construction as well as geochemical and geomechanical stresses that occur over its life-cycle. Field data are essential for assessing the integrated effect of these factors and their impact on wellbore integrity, defined as the maintenance of isolation between subsurface intervals. In this report, we investigate a 30-year-old well from a natural CO2 production reservoir using a suite of downhole and laboratory tests to characterize isolation performance. These tests included mineralogical and hydrological characterization of 10 core samples of casing/cement/formation, wireline surveys to evaluate well conditions, fluid samples and an in situ permeability test. We find evidence for CO2 migration in the occurrence of carbonated cement and calculate that the effective permeability of an 11′-region of the wellbore barrier system was between 0.5 and 1 milliDarcy. Despite these observations, we find that the amount of fluid migration along the wellbore was probably small because of several factors: the amount of carbonation decreased with distance from the reservoir, cement permeability was low (0.3-30 microDarcy), the cement-casing and cement-formation interfaces were tight, the casing was not corroded, fluid samples lacked CO2, and the pressure gradient between reservoir and caprock was maintained. We conclude that the barrier system has ultimately performed well over the last 3 decades. These results will be used as part of a broader effort to develop a long-term predictive simulation tool to assess wellbore integrity performance in CO2 storage sites. © 2009 Elsevier Ltd. All rights reserved.

  14. A 10-year record of geochemical and isotopic monitoring at the IEA Weyburn-Midale CO2 Monitoring and Storage Project (Saskatchewan, Canada)

    Science.gov (United States)

    Mayer, Bernhard; Shevalier, Maurice; Nightingale, Michael; Kwon, Jang-Soon; Hutcheon, Ian

    2013-04-01

    Carbon capture and storage is a promising technology to reduce CO2 emissions into the atmosphere. Monitoring of CO2 storage sites is required by many of the emerging regulations with specific interest in verification of injected CO2 in various target reservoirs. The objective of this study was to use geochemical and isotopic techniques to trace the fate of CO2 injected over a 10-year period at the IEA Weyburn-Midale CO2 Monitoring and Storage Project (Saskatchewan, Canada). Geochemical monitoring measures changes in chemical and isotopic parameters of fluid and gas samples in a storage reservoir due to brine-mineral-CO2 reactions resulting from CO2 injection. Seventeen sampling events were conducted over a 10-year period, including one pre-injection (baseline in the year 2000) and 16 post-injection surveys between 2001 and 2010. Fluid and gas samples were obtained from circa 50 observation wells per sampling event followed by chemical and isotope analyses. Carbon isotope ratios (δ13C) of injected CO2 were constant at -20.4 ‰ throughout the 10-year study period and were markedly different from baseline δ13C values of dissolved CO2 in the reservoir brines. Therefore, carbon isotope ratio measurements constitute an elegant tool for tracing the movement and the geochemical fate of injected CO2 in the reservoir. Gas samples obtained from the observation wells at baseline had a median CO2 concentration of 4 mole%. After 7 to 10 years of CO2 injection, a significant increase in the median CO2 concentration was observed yielding values ranging from 64 to 75 mole%. This increase in CO2 concentrations was accompanied by a decrease in the δ13C values of CO2 from a median value of -12.7 ‰ at baseline in the year 2000 to values near -18 ‰ between 2008 and 2010. This is evidence that elevated CO2 concentrations are caused by injected CO2 arriving at numerous observation wells. Analyses of fluid samples revealed that the median total alkalinity increased from ~400 mg

  15. Developing Model Constraints on Northern Extra-Tropical Carbon Cycling Based on measurements of the Abundance and Isotopic Composition of Atmospheric CO2

    Energy Technology Data Exchange (ETDEWEB)

    Keeling, Ralph [UCSD-SIO

    2014-12-12

    The objective of this project was to perform CO2 data syntheses and modeling activities to address two central questions: 1) how much has the seasonal cycle in atmospheric CO2 at northern high latitudes changed since the 1960s, and 2) how well do prognostic biospheric models represent these changes. This project also supported the continuation of the Scripps time series of CO2 isotopes and concentration at ten baseline stations distributed globally.

  16. Continuous monitoring of the C isotope composition of CO_{2}-rich subsurface degassing at Tenerife, Canary Islands

    Science.gov (United States)

    Melián, Gladys; Asensio-Ramos, María; Padrón, Eleazar; Barrancos, José; Hernández, Pedro A.; Pérez, Nemesio M.

    2017-04-01

    Tenerife is the largest island of the Canarian archipelago and several volcanic eruptions have occurred in the last 500 years, the last one in 1909. The main volcano-tectonic features of Tenerife Island are three main volcano-tectonic rifts trending N-E, N-W and N-S where, at the interception center is located Las Cañadas caldera and the stratovolcano Teide-Pico Viejo. Due to the approximately 1,500 wells and water galleries (1650 km) drilled during the last 150 years tapping the island's volcanic aquifer at different depths, Tenerife is a unique natural-scale laboratory for hydrological studies in oceanic volcanic islands. Ground waters are mainly Na+-HCO3- water type, mainly due to the continuous volcanic CO2 supply from the volcanic-hydrothermal system. A signi?cant number of these galleries show a CO2-rich inner atmosphere, and gas bubbling has also been detected inside some galleries. Since 2002, an automatic geochemical station installed at the entrance of the horizontal drilling "Fuente del Valle" (TFE02 station), Arona, Tenerife, measures the activities of 222Rn and 220Rn in the gas discharged from a CO2-rich gas bubbling spot located at 2.850 m depth. Interesting variations were recorded in the 222Rn/220Rn ratio after the period of 2004 anomalous seismicity and it has been demonstrated that this is a good control spot for volcanic surveillance (Pérez et al., 2007). Thus, in November 2016, a new type of laser based isotopic analyzer, a DeltaRayTM (Thermo Fisher Scientific) was installed in the TFE02 station to measure δ13C(CO2) directly in the gas discharged from the water. The gas, collected by means of an inverted funnel, is pumped (3 L min-1) towards the gallery entrance, where the instrumentation is located, through a polyamide pipe. During the study period the recorded data show a range of δ13C(CO2) from -6.2 to -4.2‰ vs. VPDB, with an average value of -5.1‰Ṫhese values are comparable to those ones measured in the gas sampled directly at the

  17. High-pressure continuously tunable CO2 lasers and molecular laser isotope separation

    Indian Academy of Sciences (India)

    E Ronander; H J Strydom; L R Botha

    2014-01-01

    The acronym MLIS (molecular laser isotope separation) defines the laser process whereby the isotopes of uranium can be separated by mid-infrared laser/s when the molecule employed is UF6. The theoretical and spectroscopical data to configure and enable experiments and demonstrations in the laboratory is adequate. However, the engineering and commercial aspects require innovative technology solutions that are not presently available in the literature on these topics. This paper is an overview of the most salient features of MLIS and its potential utility at an industrial level.

  18. Stable isotope and modelling evidence for CO2 as a driver of glacial–interglacial vegetation shifts in southern Africa

    Directory of Open Access Journals (Sweden)

    F. J. Bragg

    2013-03-01

    Full Text Available Atmospheric CO2 concentration is hypothesized to influence vegetation distribution via tree–grass competition, with higher CO2 concentrations favouring trees. The stable carbon isotope (δ13C signature of vegetation is influenced by the relative importance of C4 plants (including most tropical grasses and C3 plants (including nearly all trees, and the degree of stomatal closure – a response to aridity – in C3 plants. Compound-specific δ13C analyses of leaf-wax biomarkers in sediment cores of an offshore South Atlantic transect are used here as a record of vegetation changes in subequatorial Africa. These data suggest a large increase in C3 relative to C4 plant dominance after the Last Glacial Maximum. Using a process-based biogeography model that explicitly simulates 13C discrimination, it is shown that precipitation and temperature changes cannot explain the observed shift in δ13C values. The physiological effect of increasing CO2 concentration is decisive, altering the C3/C4 balance and bringing the simulated and observed δ13C values into line. It is concluded that CO2 concentration itself was a key agent of vegetation change in tropical southern Africa during the last glacial–interglacial transition. Two additional inferences follow. First, long-term variations in terrestrial δ13Cvalues are not simply a proxy for regional rainfall, as has sometimes been assumed. Although precipitation and temperature changes have had major effects on vegetation in many regions of the world during the period between the Last Glacial Maximum and recent times, CO2 effects must also be taken into account, especially when reconstructing changes in climate between glacial and interglacial states. Second, rising CO2 concentration today is likely to be influencing tree–grass competition in a similar way, and thus contributing to the "woody thickening" observed in savannas worldwide. This second inference points to the importance of experiments to

  19. Mechanistic and microkinetic analysis of CO2 hydrogenation on ceria.

    Science.gov (United States)

    Cheng, Zhuo; Lo, Cynthia S

    2016-03-21

    We use density functional theory (DFT) calculations to investigate the mechanism of CO2 hydrogenation to methanol on a reduced ceria (110) catalyst, which has previously been shown to activate CO2. Two reaction channels to methanol are identified: (1) COOH pathway via a carboxyl intermediate and (2) HCOO pathway via a formate intermediate. While formaldehyde (H2CO) appears to be the key intermediate for methanol synthesis, other intermediates, including carbine diol, formic acid and methanol, are not feasible due to their high formation energies. Furthermore, direct formyl hydrogenation to formaldehyde is not feasible due to its high activation barrier. Instead, we find that conversion of H-formalin (H2COOH*) to formaldehyde is kinetically more favorable. The formaldehyde is then converted to methoxy (H3CO*), and finally hydrogenated to form methanol. Microkinetic analyses reveal the rate-limiting steps in the reaction network and establish that the HCOO route is the dominant pathway for methanol formation on this catalyst.

  20. Tracking isotopic signatures of CO2 at the high altitude site Jungfraujoch with laser spectroscopy: analytical improvements and representative results

    Directory of Open Access Journals (Sweden)

    P. Sturm

    2013-07-01

    Full Text Available We present the continuous data record of atmospheric CO2 isotopes measured by laser absorption spectroscopy for an almost four year period at the High Altitude Research Station Jungfraujoch (3580 m a.s.l., Switzerland. The mean annual cycles derived from data of December 2008 to September 2012 exhibit peak-to-peak amplitudes of 11.0 μmol mol−1 for CO2, 0.60‰ for δ13C and 0.81‰ for δ18O. The high temporal resolution of the measurements also allow us to capture variations on hourly and diurnal timescales. For CO2 the mean diurnal peak-to-peak amplitude is about 1 μmol mol−1 in spring, autumn and winter and about 2 μmol mol−1 in summer. The mean diurnal variability in the isotope ratios is largest during the summer months too, with an amplitude of about 0.1‰ both in the δ13C and δ18O, and a smaller or no discernible diurnal cycle during the other seasons. The day-to-day variability, however, is much larger and depends on the origin of the air masses arriving at Jungfraujoch. Backward Lagrangian particle dispersion model simulations revealed a close link between air composition and prevailing transport regimes and could be used to explain part of the observed variability in terms of transport history and influence region. A footprint clustering showed significantly different wintertime CO2, δ13C and δ18O values depending on the origin and surface residence times of the air masses. Several major updates on the instrument and the calibration procedures were performed in order to further improve the data quality. We describe the new measurement and calibration setup in detail and demonstrate the enhanced performance of the analyzer. A measurement precision of about 0.02‰ for both isotope ratios has been obtained for an averaging time of 10 min, while the accuracy was estimated to be 0.1‰, including the uncertainty of the calibration gases.

  1. Precipitation of smithsonite under controlled pCO2 between 25 and 60° C - Fractionation of oxygen isotopes

    Science.gov (United States)

    Füger, Anja; Mavromatis, Vasileios; Leis, Albrecht; Dietzel, Martin

    2016-04-01

    Owing to the large fractionation (i.e. Δ18Osolid-diss. ˜30) between carbonate minerals and aqueous fluids with respect to their 18O/16O composition, the oxygen isotope composition of carbonates has been a fundamental tool for the estimation of mineral formation temperature by the geoscience community. Indeed the last 6 decades, a wide number of experimental studies investigated the temperature relation of Δ18Osolid-diss. between divalent metal carbonates and aqueous fluids. To date however no experimental data exist for the temperature dependence of Δ18Osolid-diss. between smithsonite (ZnCO3) and fluid. This lack of data likely stems from a kinetic barrier effect, that of the dehydration of aqueous Zn2+ and the formation of hydrozincite (Zn5(CO3)2(OH)6). Smithsonite is a secondary zinc mineral that is one of the components of zinc ore bodies. It is formed through oxidation of primary zinc ores by the reaction with a carbonate source or by precipitation of zinc salt solutions with a CO2-saturated and bicarbonate-rich solution. In this study we hydrothermally synthesized smithsonite at the temperature range between 25 and 60 ° C and report the temperature dependence of oxygen isotope distribution between smithsonite and aqueous fluid. In order to avoid the formation of hydrozincite our experiments were conducted in titanium batch reactors using Teflon-inlets where the CO2 pressure was adjusted to 10 bars. The low pH conditions provoked by the elevated pCO2 applied, lead to the dissolution of hydrozincite, which is initially formed by mixing of Na2HCO3 (0.1 M) and Zn(NO3)2.4 H2O (0.02 M) solutions, to yield - under the prevailing conditions - the thermodynamically stable mineral smithsonite.

  2. Determining Carbon and Oxygen Stable Isotope Systematics in Brines at Elevated p/T Conditions to Enhance Monitoring of CO2 Induced Processes in Carbon Storage Reservoirs

    Science.gov (United States)

    Becker, V.; Myrttinen, A.; Mayer, B.; Barth, J. A.

    2012-12-01

    Stable carbon isotope ratios (δ13C) are a powerful tool for inferring carbon sources and mixing ratios of injected and baseline CO2 in storage reservoirs. Furthermore, CO2 releasing and consuming processes can be deduced if the isotopic compositions of end-members are known. At low CO2 pressures (pCO2), oxygen isotope ratios (δ18O) of CO2 usually assume the δ18O of the water plus a temperature-dependent isotope fractionation factor. However, at very high CO2 pressures as they occur in CO2 storage reservoirs, the δ18O of the injected CO2 may in fact change the δ18O of the reservoir brine. Hence, changing δ18O of brine constitutes an additional tracer for reservoir-internal carbon dynamics and allows the determination of the amount of free phase CO2 present in the reservoir (Johnson et al. 2011). Further systematic research to quantify carbon and oxygen isotope fractionation between the involved inorganic carbon species (CO2, H2CO3, HCO3-, CO32-, carbonate minerals) and kinetic and equilibrium isotope effects during gas-water-rock interactions is necessary because p/T conditions and salinities in CO2 storage reservoirs may exceed the boundary conditions of typical environmental isotope applications, thereby limiting the accuracy of stable isotope monitoring approaches in deep saline formations (Becker et al. 2011). In doing so, it is crucial to compare isotopic patterns observed in laboratory experiments with artificial brines to similar experiments with original fluids from representative field sites to account for reactions of dissolved inorganic carbon (DIC) with minor brine components. In the CO2ISO-LABEL project, funded by the German Ministry for Education and Research, multiple series of laboratory experiments are conducted to determine the influence of pressure, temperature and brine composition on the δ13C of DIC and the δ18O of brines in water-CO2-rock reactions with special focus placed on kinetics and stable oxygen and carbon isotope fractionation

  3. Energy analysis of the cryogenic CO2 capture process based on Stirling coolers

    OpenAIRE

    Song, Chunfeng; Kitamura, Yutaka; Li, Shuhong

    2014-01-01

    In the existing coal-fired power plants, the energy penalty associated with CO2 capture process is an important challenge. For this reason, energy analysis has been widely used as a powerful tool to optimize the capture efficiency and reduce energy consumption. In our previous work, a Stirling cooler based cryogenic CO2 capture system was outlined. Process simulation and energy analysis of the system were undertaken in this research. The whole CO2 capture process is composed of three sections...

  4. Comparison and Analysis of CO2 Emissions Data for China

    Institute of Scientific and Technical Information of China (English)

    ZHU Song-Li

    2014-01-01

    This paper reviews the CO2 emissions data for China provided by various international organizations and databases (namely IEA, BP, EDGAR/PBL/JRC, CDIAC, EIA and CAIT) and compares them with China’s official data and estimation. The difference among these data is due to different scopes, methods and underlying data, and particularly the difference in fossil fuel consumption. Compared with data from other databases, IEA and CAIT data have the best comparability with China’s official data. The paper recommends that China enhance its coal statistics, raise the frequency of official data publication and improve the inventory completeness.

  5. Isotopic and nutritional evidence for species- and site-specific responses to N deposition and elevated CO2 in temperate forests

    Science.gov (United States)

    Silva, Lucas C. R.; Gómez-Guerrero, Armando; Doane, Timothy A.; Horwath, William R.

    2015-06-01

    In this study we show that the effect of rising atmospheric CO2 levels on forest productivity is influenced by changes in nutrient availability caused by nitrogen (N) deposition. We used a dual-isotope approach (δ15N and δ13C), combined with dendrochronological and nutritional analyses, to evaluate the response of two dominant tree species in natural forest ecosystems near Mexico City (Pinus hartwegii—pine; Abies religiosa—fir). Our analysis focuses on changes that occurred over the past 50 years at two sites, one under high and one under low N deposition rates. Analyses of carbon isotope composition indicate increasing water-use efficiency in response to rising CO2 levels for both species and sites but this effect did not lead to improved tree growth. The magnitude and direction of shifts in 13C discrimination indicate a process of acclimation that varied with the rate of N deposition and species traits. Since the 1960s, strong negative responses to N deposition have been observed in fir trees, which showed altered foliar nutrition and growth decline, while the negative impacts of N deposition on pine trees remained undetectable until the 1990s. In recent years, both species have shown significant growth decline under high N deposition despite increasing atmospheric CO2. Multivariate analysis of leaf nutrients indicates that growth decline was prompted by depleted soil macronutrient (P, K, and Ca) and micronutrient (Cu, Fe, Zn, and Mn) availability. At both sites, fir trees were a better indicator of N deposition due to differences in canopy rainfall interception.

  6. Autotrophic fixation of geogenic CO2 by microorganisms contributes to soil organic matter formation and alters isotope signatures in a wetland mofette

    Directory of Open Access Journals (Sweden)

    M. E. Nowak

    2015-09-01

    Full Text Available To quantify the contribution of autotrophic microorganisms to organic matter formation (OM in soils, we investigated natural CO2 vents (mofettes situated in a wetland in NW Bohemia (Czech Republic. Mofette soils had higher SOM concentrations than reference soils due to restricted decomposition under high CO2 levels. We used radiocarbon (Δ14C and stable carbon isotope ratios (δ13C to characterize SOM and its sources in two moffetes and compared it with respective reference soils, which were not influenced by geogenic CO2. The geogenic CO2 emitted at these sites is free of radiocarbon and enriched in δ13C compared to atmospheric CO2. Together, these isotopic signals allow us to distinguish C fixed by plants from C fixed by autotrophic microorganisms using their differences in δ13C discrimination. We can then estimate that up to 27 % of soil organic matter in the 0–10 cm layer of these soils was derived from microbially assimilated CO2. Isotope values of bulk SOM were shifted towards more positive δ13C and more negative Δ14C values in mofettes compared to reference soils, suggesting that geogenic CO2 emitted from the soil atmosphere is incorporated into SOM. To distinguish whether geogenic CO2 was fixed by plants or by CO2 assimilating microorganisms, we first used the proportional differences in radiocarbon and δ13C values to indicate the magnitude of discrimination of the stable isotopes in living plants. Deviation from this relationship was taken to indicate the presence of microbial CO2 fixation, as microbial discrimination should differ from that of plants. 13CO2-labelling experiments confirmed high activity of CO2 assimilating microbes in the top 10 cm, where δ13C values of SOM were shifted up to 2 ‰ towards more negative values. Uptake rates of microbial CO2 fixation ranged up to 1.59 ± 0.16 μg gdw−1 d−1. We inferred that the negative δ13C shift was caused by the activity of chemo-lithoautotrophic microorganisms, as

  7. Operation and analysis of a supercritical CO2 Brayton cycle.

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Steven Alan; Radel, Ross F.; Vernon, Milton E.; Pickard, Paul S.; Rochau, Gary Eugene

    2010-09-01

    Sandia National Laboratories is investigating advanced Brayton cycles using supercritical working fluids for use with solar, nuclear or fossil heat sources. The focus of this work has been on the supercritical CO{sub 2} cycle (S-CO2) which has the potential for high efficiency in the temperature range of interest for these heat sources, and is also very compact, with the potential for lower capital costs. The first step in the development of these advanced cycles was the construction of a small scale Brayton cycle loop, funded by the Laboratory Directed Research & Development program, to study the key issue of compression near the critical point of CO{sub 2}. This document outlines the design of the small scale loop, describes the major components, presents models of system performance, including losses, leakage, windage, compressor performance, and flow map predictions, and finally describes the experimental results that have been generated.

  8. STABLE CARBON ISOTOPES OF HCO//3 IN THE AQUIA AQUIFER, MARYLAND: EVIDENCE FOR AN ISOTOPICALLY HEAVY SOURCE OF CO//2.

    Science.gov (United States)

    Chapelle, Francis H.; Knobel, LeRoy L.

    1985-01-01

    Identifying sources and sinks of dissolved inorganic carbon species is an important step in understanding the geochemistry of ground-water systems. This is particularly important for Atlantic Coastal Plain aquifers because bicarbonate (HCO//3** minus ) is frequently the major dissolved anion. The purpose of this paper is to document the stable carbon isotope composition of dissolved inorganic carbon in the Aquia aquifer, Maryland, and to use this data to help identify sources and sinks of dissolved HCO//3** minus . Subjects covered include hydrogeology, ground-water chemistry, sources and sinks, and others. Refs.

  9. Does photosynthesis affect grassland soil-respired CO2 and its carbon isotope composition on a diurnal timescale?

    Science.gov (United States)

    Bahn, Michael; Schmitt, Michael; Siegwolf, Rolf; Richter, Andreas; Brüggemann, Nicolas

    2009-01-01

    Soil respiration is the largest flux of carbon (C) from terrestrial ecosystems to the atmosphere. Here, we tested the hypothesis that photosynthesis affects the diurnal pattern of grassland soil-respired CO(2) and its C isotope composition (delta(13)C(SR)). A combined shading and pulse-labelling experiment was carried out in a mountain grassland. delta(13)C(SR) was monitored at a high time resolution with a tunable diode laser absorption spectrometer. In unlabelled plots a diurnal pattern of delta(13)C(SR) was observed, which was not explained by soil temperature, moisture or flux rates and contained a component that was also independent of assimilate supply. In labelled plots delta(13)C(SR) reflected a rapid transfer and respiratory use of freshly plant-assimilated C and a diurnal shift in the predominant respiratory C source from recent (i.e. at least 1 d old) to fresh (i.e. photoassimilates produced on the same day). We conclude that in grasslands the plant-derived substrates used for soil respiratory processes vary during the day, and that photosynthesis provides an important and immediate C source. These findings indicate a tight coupling in the plant-soil system and the importance of plant metabolism for soil CO(2) fluxes.

  10. Analysis of a New Liquefaction Combined with Desublimation System for CO2 Separation Based on N2/CO2 Phase Equilibrium

    Directory of Open Access Journals (Sweden)

    Wenchao Yang

    2015-09-01

    Full Text Available Cryogenic CO2 capture is considered as a promising CO2 capture method due to its energy saving and environmental friendliness. The phase equilibrium analysis of CO2-mixtures at low temperature is crucial for the design and operation of a cryogenic system because it plays an important role in analysis of recovery and purity of the captured CO2. After removal of water and toxic gas, the main components in typical boiler gases are N2/CO2. Therefore, this paper evaluates the reliabilities of different cubic equations of state (EOS and mixing rules for N2/CO2. The results show that Peng-Robinson (PR and Soave-Redlich-Kwong (SRK fit the experimental data well, PR combined with the van der Waals (vdW mixing rule is more accurate than the other models. With temperature decrease, the accuracy of the model improves and the deviation of the N2 vapor fraction is 0.43% at 220 K. Based on the selected calculation model, the thermodynamic properties of N2/CO2 at low temperature are analyzed. According to the results, a new liquefaction combined with a desublimation system is proposed. The total recovery and purity of CO2 production of the new system are satisfactory enough for engineering applications. Additionally, the total energy required by the new system to capture the CO2 is about 3.108 MJ·kg−1 CO2, which appears to be at least 9% lower than desublimation separation when the initial concentration of CO2 is 40%.

  11. An inverse analysis reveals limitations of the soil-CO2 profile method to calculate CO2 production and efflux for well-structured soils

    Directory of Open Access Journals (Sweden)

    M. D. Corre

    2010-08-01

    Full Text Available Soil respiration is the second largest flux in the global carbon cycle, yet the underlying below-ground process, carbon dioxide (CO2 production, is not well understood because it can not be measured in the field. CO2 production has frequently been calculated from the vertical CO2 diffusive flux divergence, known as "soil-CO2 profile method". This relatively simple model requires knowledge of soil CO2 concentration profiles and soil diffusive properties. Application of the method for a tropical lowland forest soil in Panama gave inconsistent results when using diffusion coefficients (D calculated based on relationships with soil porosity and moisture ("physically modeled" D. Our objective was to investigate whether these inconsistencies were related to (1 the applied interpolation and solution methods and/or (2 uncertainties in the physically modeled profile of D. First, we show that the calculated CO2 production strongly depends on the function used to interpolate between measured CO2 concentrations. Secondly, using an inverse analysis of the soil-CO2 profile method, we deduce which D would be required to explain the observed CO2 concentrations, assuming the model perception is valid. In the top soil, this inversely modeled D closely resembled the physically modeled D. In the deep soil, however, the inversely modeled D increased sharply while the physically modeled D did not. When imposing a constraint during the fit parameter optimization, a solution could be found where this deviation between the physically and inversely modeled D disappeared. A radon (Rn mass balance model, in which diffusion was calculated based on the physically modeled or constrained inversely modeled D, simulated observed Rn profiles reasonably well. However, the CO2 concentrations which corresponded to the constrained inversely modeled D were too small compared to the measurements. We suggest that, in well-structured soils, a missing description of steady state CO2

  12. Incorporating temporal variability to improve geostatistical analysis of satellite-observed CO2 in China

    Institute of Scientific and Technical Information of China (English)

    ZENG ZhaoCheng; LEI LiPing; GUO LiJie; ZHANG Li; ZHANG Bing

    2013-01-01

    Observations of atmospheric carbon dioxide (CO2) from satellites offer new data sources to understand global carbon cycling.The correlation structure of satellite-observed CO2 can be analyzed and modeled by geostatistical methods,and CO2 values at unsampled locations can be predicted with a correlation model.Conventional geostatistical analysis only investigates the spatial correlation of CO2,and does not consider temporal variation in the satellite-observed CO2 data.In this paper,a spatiotemporal geostatistical method that incorporates temporal variability is implemented and assessed for analyzing the spatiotemporal correlation structure and prediction of monthly CO2 in China.The spatiotemporal correlation is estimated and modeled by a product-sum variogram model with a global nugget component.The variogram result indicates a significant degree of temporal correlation within satellite-observed CO2 data sets in China.Prediction of monthly CO2 using the spatiotemporal variogram model and spacetime kriging procedure is implemented.The prediction is compared with a spatial-only geostatistical prediction approach using a cross-validation technique.The spatiotemporal approach gives better results,with higher correlation coefficient (r2),and less mean absolute prediction error and root mean square error.Moreover,the monthly mapping result generated from the spatiotemporal approach has less prediction uncertainty and more detailed spatial variation of CO2 than those from the spatial-only approach.

  13. Economic and energetic analysis of capturing CO2 from ambient air

    Science.gov (United States)

    House, Kurt Zenz; Baclig, Antonio C.; Ranjan, Manya; van Nierop, Ernst A.; Wilcox, Jennifer; Herzog, Howard J.

    2011-01-01

    Capturing carbon dioxide from the atmosphere (“air capture”) in an industrial process has been proposed as an option for stabilizing global CO2 concentrations. Published analyses suggest these air capture systems may cost a few hundred dollars per tonne of CO2, making it cost competitive with mainstream CO2 mitigation options like renewable energy, nuclear power, and carbon dioxide capture and storage from large CO2 emitting point sources. We investigate the thermodynamic efficiencies of commercial separation systems as well as trace gas removal systems to better understand and constrain the energy requirements and costs of these air capture systems. Our empirical analyses of operating commercial processes suggest that the energetic and financial costs of capturing CO2 from the air are likely to have been underestimated. Specifically, our analysis of existing gas separation systems suggests that, unless air capture significantly outperforms these systems, it is likely to require more than 400 kJ of work per mole of CO2, requiring it to be powered by CO2-neutral power sources in order to be CO2 negative. We estimate that total system costs of an air capture system will be on the order of $1,000 per tonne of CO2, based on experience with as-built large-scale trace gas removal systems. PMID:22143760

  14. Catalytic recombination of dissociation products with Pt/SnO2 for rare and common isotope long-life, closed-cycle CO2 lasers

    Science.gov (United States)

    Brown, Kenneth G.; Sidney, B. D.; Schryer, D. R.; Upchurch, B. T.; Miller, I. M.

    1986-01-01

    This paper reports results on recombination of pulsed CO2 laser dissociation products with Pt/SnO2 catalysts, and supporting studies in a surrogate laboratory catalyst reactor. The closed-cycle, pulsed CO2 laser has been continuously operated for one million pulses with an overall power degradation of less than 5 percent by flowing the laser gas mixture through a 2-percent Pt/SnO2 catalyst bed. In the surrogate laboratory reactor, experiments have been conducted to determine isotopic exchange with the catalyst when using rare-isotope gases. The effects of catalyst pretreatment, sample weight, composition, and temperature on catalyst efficiency have also been determined.

  15. Declining Atmospheric pCO2 During the Late Miocene and Early Pliocene: New Insights from Paired Alkenone and Coccolith Stable Isotope Barometry

    Science.gov (United States)

    Phelps, S. R.; Polissar, P. J.; deMenocal, P. B.; Swann, J. P.; Guo, M. Y.; Stoll, H. M.

    2015-12-01

    The relationship between atmospheric CO2 concentrations and climate is broadly understood for the Cenozoic era: warmer periods are associated with higher atmospheric carbon dioxide. This understanding is supported by atmospheric samples of the past 800,000 years from ice cores, which suggest CO2 levels play a key role in regulating global climate on glacial interglacial timescales as well. In this context, the late Miocene poses a challenge: sea-surface temperatures indicate substantial global warmth, though existing data suggest atmospheric CO2 concentrations were lower than pre-industrial values. Recent work using the stable carbon and oxygen isotopic composition of coccolith calcite has demonstrated these organisms began actively diverting inorganic carbon away from calcification and to the site of photosynthesis during the late Miocene. This process occurs in culture experiments in response to low aqueous CO2 concentrations, and suggests decreasing atmospheric pCO2 values during the late Miocene. Here we present new data from ODP Site 806 in the western equatorial Pacific Ocean that supports declining atmospheric CO2 across the late Miocene. Carbon isotope values of coccolith calcite from Site 806 demonstrate carbon limitation and re-allocation of inorganic carbon to photosynthesis starting between ~8 and 6 Ma. The timing of this limitation at Site 806 precedes shifts at other ODP sites, reflecting the higher mixed layer temperature and resultant lower CO2 solubility at Site 806. New measurements of carbon isotope values from alkenones at Site 806 show an increase in photosynthetic carbon fractionation (ɛp) accompanied the carbon limitation evident from coccolith calcite stable isotope data. While higher ɛp is typically interpreted as higher CO2 concentrations, at Site 806, our data suggest it reflects enhancement of chloroplast CO2 from active carbon transport by the coccolithophore algae in response to lower CO2 concentrations. Our new data from ODP Site

  16. Factors Affecting Transportation Sector CO2 Emissions Growth in China: An LMDI Decomposition Analysis

    Directory of Open Access Journals (Sweden)

    Yi Liang

    2017-09-01

    Full Text Available China has now become the largest country in carbon emissions all over the world. Furthermore, with transportation accounting for an increasing proportion of CO2 emissions year by year, the transportation sector has turned out to be one of the main sectors which possesses a high growth speed in CO2 emissions. To accurately analyze potentially influencing factors which accelerate the process of CO2 emissions of transportation sector in China, based on carbon accounting by the checklists method of Intergovernmental Panel on Climate Change’s (IPCC, in this paper, we propose a decomposition model using Logarithmic Mean Divisia Index (LMDI decomposition analysis technology and modified fixed growth rate method. Then effects of six influencing factors including energy structure, energy efficiency, transport form, transportation development, economic development and population size from 2001 to 2014 were quantitatively analyzed. Consequently, the results indicate that: (1 economic development accounts most for driving CO2 emissions growth of the transportation sector, while energy efficiency accounts most for suppressing CO2 emissions growth; (2 the pulling effects of natural gas, electricity and other clean energy consumption on CO2 emissions growth offset the inhibitory effects of traditional fossil fuels, making energy structure play a significant role in promoting CO2 emissions growth; (3 the inhibitory effects of railways and highways lead to inhibitory effects of transport form on CO2 emissions growth; (4 transportation development plays an obvious role in promoting CO2 emissions, while the effects of population size is relatively weaker compared with those of transportation development. Furthermore, the decomposition model of CO2 emissions factors in transport industry constructed in this paper can also be applied to other countries so as to provide guidance and reference for CO2 emissions analysis of transportation industry.

  17. Understanding the interaction of injected CO2 and reservoir fluids in the Cranfield enhanced oil recovery (EOR) field (MS, USA) by non-radiogenic noble gas isotopes

    Science.gov (United States)

    Gyore, Domokos; Stuart, Finlay; Gilfillan, Stuart

    2016-04-01

    Identifying the mechanism by which the injected CO2 is stored in underground reservoirs is a key challenge for carbon sequestration. Developing tracing tools that are universally deployable will increase confidence that CO2 remains safely stored. CO2 has been injected into the Cranfield enhanced oil recovery (EOR) field (MS, USA) since 2008 and significant amount of CO2 has remained (stored) in the reservoir. Noble gases (He, Ne, Ar, Kr, Xe) are present as minor natural components in the injected CO2. He, Ne and Ar previously have been shown to be powerful tracers of the CO2 injected in the field (Györe et al., 2015). It also has been implied that interaction with the formation water might have been responsible for the observed CO2 loss. Here we will present work, which examines the role of reservoir fluids as a CO2 sink by examining non-radiogenic noble gas isotopes (20Ne, 36Ar, 84Kr, 132Xe). Gas samples from injection and production wells were taken 18 and 45 months after the start of injection. We will show that the fractionation of noble gases relative to Ar is consistent with the different degrees of CO2 - fluid interaction in the individual samples. The early injection samples indicate that the CO2 injected is in contact with the formation water. The spatial distribution of the data reveal significant heterogeneity in the reservoir with some wells exhibiting a relatively free flow path, where little formation water is contacted. Significantly, in the samples, where CO2 loss has been previously identified show active and ongoing contact. Data from the later stage of the injection shows that the CO2 - oil interaction has became more important than the CO2 - formation water interaction in controlling the noble gas fingerprint. This potentially provides a means to estimate the oil displacement efficiency. This dataset is a demonstration that noble gases can resolve CO2 storage mechanisms and its interaction with the reservoir fluids with high resolution

  18. Has the impact of rising CO2 on plants been exaggerated by meta-analysis of free air CO2 enrichment studies?

    Directory of Open Access Journals (Sweden)

    Matthew Haworth

    2016-08-01

    Full Text Available Meta-analysis is extensively used to synthesise the results of free air CO2 enrichment (FACE studies to produce an average effect size, which is then used to model likely plant response to rising [CO2]. The efficacy of meta-analysis is reliant upon the use of data that characterises the range of responses to a given factor. Previous meta-analyses of the effect of FACE on plants have not incorporated the potential impact of reporting bias in skewing data. By replicating the methodology of these meta-analytic studies, we demonstrate that meta-analysis of FACE has likely exaggerated the effect size of elevated [CO2] on plants by 20 to 40%; having significant implications for predictions of food security and vegetation response to climate change. Incorporation of the impact of reporting bias did not affect the significance or the direction of the [CO2] effect.

  19. Has the Impact of Rising CO2 on Plants been Exaggerated by Meta-Analysis of Free Air CO2 Enrichment Studies?

    Science.gov (United States)

    Haworth, Matthew; Hoshika, Yasutomo; Killi, Dilek

    2016-01-01

    Meta-analysis is extensively used to synthesize the results of free air CO2 enrichment (FACE) studies to produce an average effect size, which is then used to model likely plant response to rising [CO2]. The efficacy of meta-analysis is reliant upon the use of data that characterizes the range of responses to a given factor. Previous meta-analyses of the effect of FACE on plants have not incorporated the potential impact of reporting bias in skewing data. By replicating the methodology of these meta-analytic studies, we demonstrate that meta-analysis of FACE has likely exaggerated the effect size of elevated [CO2] on plants by 20 to 40%; having significant implications for predictions of food security and vegetation response to climate change. Incorporation of the impact of reporting bias did not affect the significance or the direction of the [CO2] effect.

  20. Analysis of CO2 Separation from Flue Gas, Pipeline Transportation, and Sequestration in Coal

    Energy Technology Data Exchange (ETDEWEB)

    Eric P. Robertson

    2007-09-01

    This report was written to satisfy a milestone of the Enhanced Coal Bed Methane Recovery and CO2 Sequestration task of the Big Sky Carbon Sequestration project. The report begins to assess the costs associated with separating the CO2 from flue gas and then injecting it into an unminable coal seam. The technical challenges and costs associated with CO2 separation from flue gas and transportation of the separated CO2 from the point source to an appropriate sequestration target was analyzed. The report includes the selection of a specific coal-fired power plant for the application of CO2 separation technology. An appropriate CO2 separation technology was identified from existing commercial technologies. The report also includes a process design for the chosen technology tailored to the selected power plant that used to obtain accurate costs of separating the CO2 from the flue gas. In addition, an analysis of the costs for compression and transportation of the CO2 from the point-source to an appropriate coal bed sequestration site was included in the report.

  1. Thermodynamic Analysis and Comparison on Low Temperature CO2-NH3 Cascade Refrigeration Cycle

    Institute of Scientific and Technical Information of China (English)

    查世彤; 马一太; 申江; 李敏霞

    2003-01-01

    This paper is focused on the cascade refrigeration cycle using natural refrigerant CO2-NH3. The properties of refrigerants CO2 and NH3 are introduced and analyzed.CO2 has the advantage in low stage of cascade refrigeration cycle due to its good characteristics and properties. The thermodynamic analysis results of the CO2-NH3 cascade refrigeration cycle demonstrates that the cycle has an optimum condensation temperature of low stage and also has an optimum flow rate ratio.By comparing with the R13-R22 and NH3-NH3 cascade refrigeration cycles, the mass flow rate ratio of CO2-NH3 is larger than those of R13-R22 and NH3-NH3, the theoretical COP of CO2-NH3 cascade refrigeration cycle is larger than that of the R13-R22 cascade cycle and smaller than that of the NH3-NH3 cascade cycle. But the real COP of CO2-NH3 cascade cycle will be higher than those of R13-R22 and NH3-NH3 because the specific volume of CO2 at low temperature does not change much and its dynamic viscosity is also small.

  2. Evaluating the climate benefits of CO2-enhanced oil recovery using life cycle analysis.

    Science.gov (United States)

    Cooney, Gregory; Littlefield, James; Marriott, Joe; Skone, Timothy J

    2015-06-16

    This study uses life cycle analysis (LCA) to evaluate the greenhouse gas (GHG) performance of carbon dioxide (CO2) enhanced oil recovery (EOR) systems. A detailed gate-to-gate LCA model of EOR was developed and incorporated into a cradle-to-grave boundary with a functional unit of 1 MJ of combusted gasoline. The cradle-to-grave model includes two sources of CO2: natural domes and anthropogenic (fossil power equipped with carbon capture). A critical parameter is the crude recovery ratio, which describes how much crude is recovered for a fixed amount of purchased CO2. When CO2 is sourced from a natural dome, increasing the crude recovery ratio decreases emissions, the opposite is true for anthropogenic CO2. When the CO2 is sourced from a power plant, the electricity coproduct is assumed to displace existing power. With anthropogenic CO2, increasing the crude recovery ratio reduces the amount of CO2 required, thereby reducing the amount of power displaced and the corresponding credit. Only the anthropogenic EOR cases result in emissions lower than conventionally produced crude. This is not specific to EOR, rather the fact that carbon-intensive electricity is being displaced with captured electricity, and the fuel produced from that system receives a credit for this displacement.

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

    Science.gov (United States)

    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...

  4. Assessing the determinism of the seasonal variations of trunk CO2 efflux by combining field-isotopic composition monitoring and process-based modeling

    Science.gov (United States)

    Ngao, J.; Berveiller, D.; Eglin, T.; Bazot, S.; Pontailler, J.; Damesin, C.

    2008-12-01

    Trunk CO2 efflux is a major component of total CO2 forest ecosystem efflux but its determinism is still poorly understood. This CO2 flux could originate from different carbon sources (respiration of newly assimilates or reserves; xylem sap flow dissolved CO2). These potential CO2 sources of the ecosystem vary at a diurnal and seasonal time scale. They follow distinct metabolic pathways within the tree and could potentially differ in terms of stable C isotopes composition (δ13C). During this last decade, new techniques such as tunable diode laser absorption spectroscopy (TDLAS) has enabled to track both the δ13C and rate of CO2 fluxes at a high temporal frequency compared to conventional isotope ratio mass spectroscopy and chamber-based techniques. In this context, our objective is to examine the diurnal and day-to-day variations of δ13C trunk CO2 efflux and to test if they are driven by climate, xylem sap flow and photosynthetic activity. A TDLAS (TGA100A, Campbell Sci., UT) was installed in early July 2008 in a mature oak (Quercus petraea, L.) stand of the Barbeau forest (France, Carboeurope site). It has been connected to three opened trunk chambers placed at breast height. Before each chamber measurement, which occurred every six minutes, the analyzer was calibrated with four calibration gas bottles with known CO2 concentration (in air) and δ13C values. Concurrently to trunk CO2 efflux rate and δ13C, xylem sap flow rate, air and trunk temperatures, and vapor pressure deficit above canopy were recorded. Data for the summer and fall seasons will be presented and discussed. Preliminary results showed that in summer both trunk CO2 efflux rate and CO2 followed the time evolution but at a different level among trees. The mean hourly averages of CO2 of trunk CO2 efflux values ranged from -29.6‰ to - 23.2‰, and hourly means of CO2 efflux were positively and linearly linked to trunk temperature. The diurnal variations of δ13C of CO2 efflux are less obvious that

  5. In situ measurement of CO2 and water vapour isotopic compositions at a forest site using mid-infrared laser absorption spectroscopy.

    Science.gov (United States)

    Wada, Ryuichi; Matsumi, Yutaka; Takanashi, Satoru; Nakai, Yuichiro; Nakayama, Tomoki; Ouchi, Mai; Hiyama, Tetsuya; Fujiyoshi, Yasushi; Nakano, Takashi; Kurita, Naoyuki; Muramoto, Kenichiro; Kodama, Naomi

    2016-12-01

    We conducted continuous, high time-resolution measurements of CO2 and water vapour isotopologues ((16)O(12)C(16)O, (16)O(13)C(16)O and (18)O(12)C(16)O for CO2, and H2(18)O for water vapour) in a red pine forest at the foot of Mt. Fuji for 9 days from the end of July 2010 using in situ absorption laser spectroscopy. The δ(18)O values in water vapour were estimated using the δ(2)H-δ(18)O relationship. At a scale of several days, the temporal variations in δ(18)O-CO2 and δ(18)O-H2O are similar. The orders of the daily Keeling plots are almost identical. A possible reason for the similar behaviour of δ(18)O-CO2 and δ(18)O-H2O is considered to be that the air masses with different water vapour isotopic ratios moved into the forest, and changed the atmosphere of the forest. A significant correlation was observed between δ(18)O-CO2 and δ(13)C-CO2 values at nighttime (r(2)≈0.9) due to mixing between soil (and/or leaf) respiration and tropospheric CO2. The ratios of the discrimination coefficients (Δa/Δ) for oxygen (Δa) and carbon (Δ) isotopes during photosynthesis were estimated in the range of 0.7-1.2 from the daytime correlations between δ(18)O-CO2 and δ(13)C-CO2 values.

  6. Growth decline and divergent tree ring isotopic composition (δ(13) C and δ(18) O) contradict predictions of CO2 stimulation in high altitudinal forests.

    Science.gov (United States)

    Gómez-Guerrero, Armando; Silva, Lucas C R; Barrera-Reyes, Miguel; Kishchuk, Barbara; Velázquez-Martínez, Alejandro; Martínez-Trinidad, Tomás; Plascencia-Escalante, Francisca Ofelia; Horwath, William R

    2013-06-01

    Human-induced changes in atmospheric composition are expected to affect primary productivity across terrestrial biomes. Recent changes in productivity have been observed in many forest ecosystems, but low-latitude upper tree line forests remain to be investigated. Here, we use dendrochronological methods and isotopic analysis to examine changes in productivity, and their physiological basis, in Abies religiosa (Ar) and Pinus hartwegii (Ph) trees growing in high-elevation forests of central Mexico. Six sites were selected across a longitudinal transect (Transverse Volcanic Axis), from the Pacific Ocean toward the Gulf of Mexico, where mature dominant trees were sampled at altitudes ranging from 3200 to 4000 m asl. A total of 60 Ar and 84 Ph trees were analyzed to describe changes in growth (annual-resolution) and isotopic composition (decadal-resolution) since the early 1900s. Our results show an initial widespread increase in basal area increment (BAI) during the first half of the past century. However, BAI has decreased significantly since the 1950s with accentuated decline after the 1980s in both species and across sites. We found a consistent reduction in atmosphere to wood (13) C discrimination, resulting from increasing water use efficiency (20-60%), coinciding with rising atmospheric CO2 . Changes in (13) C discrimination were not followed, however, by shifts in tree ring δ(18) O, indicating site- and species-specific differences in water source or uptake strategy. Our results indicate that CO2 stimulation has not been enough to counteract warming-induced drought stress, but other stressors, such as progressive nutrient limitation, could also have contributed to growth decline. Future studies should explore the distinct role of resource limitation (water vs. nutrients) in modulating the response of high-elevation ecosystems to atmospheric change.

  7. Reconstructing CO2 concentrations in basaltic melt inclusions using Raman analysis of vapor bubbles

    Science.gov (United States)

    Aster, Ellen M.; Wallace, Paul J.; Moore, Lowell R.; Watkins, James; Gazel, Esteban; Bodnar, Robert J.

    2016-09-01

    Melt inclusions record valuable information about pre-eruptive volatile concentrations of melts. However, a vapor bubble commonly forms in inclusions after trapping, and this decreases the dissolved CO2 concentration in the melt (glass) phase in the inclusion. To quantify CO2 loss to vapor bubbles, Raman spectroscopic analysis was used to determine the density of CO2 in bubbles in melt inclusions from two Cascade cinder cones near Mt. Lassen and two Mexican cinder cones (Jorullo, Parícutin). Using analyses of dissolved CO2 and H2O in the glass in the inclusions, the measured CO2 vapor densities were used to reconstruct the original dissolved CO2 contents of the melt inclusions at the time of trapping. Our results show that 30-90% of the CO2 in a melt inclusion is contained in the vapor bubble, values similar to those found in other recent studies. We developed a model for vapor bubble growth to show how post-entrapment bubbles form in melt inclusions as a result of cooling, crystallization, and eruptive quenching. The model allows us to predict the bubble volume fraction as a function of ΔT (the difference between the trapping temperature and eruptive temperature) and the amount of CO2 lost to a bubble. Comparison of the Raman and modeling methods shows highly variable agreement. For 10 of 17 inclusions, the two methods are within ± 550 ppm CO2 (avg. difference 290 ppm), equivalent to ±~300 bars uncertainty in estimated trapping pressure for restored inclusions. Discrepancies between the two methods occur for inclusions that have been strongly affected by post-entrapment diffusive H+ loss, because this process enhances bubble formation. For our dataset, restoring the CO2 lost to vapor bubbles increases inferred trapping pressures of the inclusions by 600 to as much as 4000 bars, highlighting the importance of accounting for vapor bubble formation in melt inclusion studies.

  8. Genes responsive to elevated CO2 concentrations in triploid white poplar and integrated gene network analysis.

    Directory of Open Access Journals (Sweden)

    Juanjuan Liu

    Full Text Available BACKGROUND: The atmospheric CO2 concentration increases every year. While the effects of elevated CO2 on plant growth, physiology and metabolism have been studied, there is now a pressing need to understand the molecular mechanisms of how plants will respond to future increases in CO2 concentration using genomic techniques. PRINCIPAL FINDINGS: Gene expression in triploid white poplar ((Populus tomentosa ×P. bolleana ×P. tomentosa leaves was investigated using the Affymetrix poplar genome gene chip, after three months of growth in controlled environment chambers under three CO2 concentrations. Our physiological findings showed the growth, assessed as stem diameter, was significantly increased, and the net photosynthetic rate was decreased in elevated CO2 concentrations. The concentrations of four major endogenous hormones appeared to actively promote plant development. Leaf tissues under elevated CO2 concentrations had 5,127 genes with different expression patterns in comparison to leaves under the ambient CO2 concentration. Among these, 8 genes were finally selected for further investigation by using randomized variance model corrective ANOVA analysis, dynamic gene expression profiling, gene network construction, and quantitative real-time PCR validation. Among the 8 genes in the network, aldehyde dehydrogenase and pyruvate kinase were situated in the core and had interconnections with other genes. CONCLUSIONS: Under elevated CO2 concentrations, 8 significantly changed key genes involved in metabolism and responding to stimulus of external environment were identified. These genes play crucial roles in the signal transduction network and show strong correlations with elevated CO2 exposure. This study provides several target genes, further investigation of which could provide an initial step for better understanding the molecular mechanisms of plant acclimation and evolution in future rising CO2 concentrations.

  9. Impact of decade-long warming, nutrient addition and shading on emission and carbon isotopic composition of CO2 from two subarctic dwarf shrub heaths

    DEFF Research Database (Denmark)

    Ravn, Nynne R.; Ambus, Per Lennart; Michelsen, Anders

    2017-01-01

    This study investigated ecosystem respiration, soil respiration and carbon isotopic composition in CO2 emitted from two subarctic shrub heaths with contrasting moisture regimes. The reported measurements were conducted 22 years (mesic heath) and 12 years (wet heath) upon initiation of in situ...... climate change related manipulations of temperature, nutrient availability and light. The aim was to quantify expected climatic change effects on soil and ecosystem respiration, and to investigate whether the emitted CO2 originates from old carbon stores in the soil or from newly fixed carbon. Ecosystem...... increased ecosystem respiration by 99% and soil respiration by 58%. Litter addition, short time warming and shading generally did not change ecosystem- and soil respiration. The carbon isotope compositions of the sources to CO2 were not significantly altered by any of the treatments at the two heaths across...

  10. Study of the Role of Terrestrial Processes in the Carbon Cycle Based on Measurements of the Abundance and Isotopic Composition of Atmospheric CO2

    Energy Technology Data Exchange (ETDEWEB)

    Piper, Stephen C; Keeling, Ralph F

    2012-01-03

    The main objective of this project was to continue research to develop carbon cycle relationships related to the land biosphere based on remote measurements of atmospheric CO2 concentration and its isotopic ratios 13C/12C, 18O/16O, and 14C/12C. The project continued time-series observations of atmospheric carbon dioxide and isotopic composition begun by Charles D. Keeling at remote sites, including Mauna Loa, the South Pole, and eight other sites. Using models of varying complexity, the concentration and isotopic measurements were used to study long-term change in the interhemispheric gradients in CO2 and 13C/12C to assess the magnitude and evolution of the northern terrestrial carbon sink, to study the increase in amplitude of the seasonal cycle of CO2, to use isotopic data to refine constraints on large scale changes in isotopic fractionation which may be related to changes in stomatal conductance, and to motivate improvements in terrestrial carbon cycle models. The original proposal called for a continuation of the new time series of 14C measurements but subsequent descoping to meet budgetary constraints required termination of measurements in 2007.

  11. Effects of reduced carbonic anhydrase activity on CO2 assimilation rates in Setaria viridis: a transgenic analysis.

    Science.gov (United States)

    Osborn, Hannah L; Alonso-Cantabrana, Hugo; Sharwood, Robert E; Covshoff, Sarah; Evans, John R; Furbank, Robert T; von Caemmerer, Susanne

    2017-01-01

    In C4 species, the major β-carbonic anhydrase (β-CA) localized in the mesophyll cytosol catalyses the hydration of CO2 to HCO3(-), which phosphoenolpyruvate carboxylase uses in the first step of C4 photosynthesis. To address the role of CA in C4 photosynthesis, we generated transgenic Setaria viridis depleted in β-CA. Independent lines were identified with as little as 13% of wild-type CA. No photosynthetic defect was observed in the transformed lines at ambient CO2 partial pressure (pCO2). At low pCO2, a strong correlation between CO2 assimilation rates and CA hydration rates was observed. C(18)O(16)O isotope discrimination was used to estimate the mesophyll conductance to CO2 diffusion from the intercellular air space to the mesophyll cytosol (gm) in control plants, which allowed us to calculate CA activities in the mesophyll cytosol (Cm). This revealed a strong relationship between the initial slope of the response of the CO2 assimilation rate to cytosolic pCO2 (ACm) and cytosolic CA activity. However, the relationship between the initial slope of the response of CO2 assimilation to intercellular pCO2 (ACi) and cytosolic CA activity was curvilinear. This indicated that in S. viridis, mesophyll conductance may be a contributing limiting factor alongside CA activity to CO2 assimilation rates at low pCO2.

  12. Tracing the sources of gaseous components (222Rn, CO2 and its carbon isotopes) in soil air under a cool-deciduous stand in Sapporo, Japan.

    Science.gov (United States)

    Fujiyoshi, Ryoko; Haraki, Yukihide; Sumiyoshi, Takashi; Amano, Hikaru; Kobal, Ivan; Vaupotic, Janja

    2010-02-01

    Radon ((222)Rn) and carbon dioxide were monitored simultaneously in soil air under a cool-temperate deciduous stand on the campus of Hokkaido University, Sapporo, Japan. Both (222)Rn and CO(2) concentrations in soil air varied with atmospheric (soil) temperature in three seasons, except for winter when the temperature in soil air remained constant at 2-3 degrees C at depth of 80 cm. In winter, the gaseous components were influenced by low-pressure region passing through the observation site when the ground surface was covered with snow of ~1 m thickness. Carbon isotopic analyses of CO(2) suggested that CO(2) in soil air may result from mixing of atmospheric air and soil components of different origins, i.e. CO(2) from contemporary soil organic matter and old carbon from deeper source, to varying degrees, depending on seasonal meteorological and thus biological conditions.

  13. Analysis of CO2 emission in traffic flow and numerical tests

    Science.gov (United States)

    Zhu, Wen-Xing

    2013-10-01

    We investigated the carbon dioxide emission rate in traffic flow analytically and numerically. The emission model was derived based on Bando’s optimal velocity model with a consideration of slope. Simulations were conducted to examine the relationship between the CO2 emission rate of vehicles and slope of road, traffic density, and road length. Analysis of the results shows that some original laws of CO2 emission in traffic flow with congestion were exhibited.

  14. Maintaining consistent traceability in high-precision isotope measurements of CO2: a way to verify atmospheric trends of δ13C and δ18O

    Directory of Open Access Journals (Sweden)

    L. Huang

    2013-07-01

    Full Text Available Maintaining consistent traceability of high-precision measurements of CO2 isotopes is critical in order to obtain accurate atmospheric trends of δ13C and δ18O (in CO2. Although a number of laboratories/organizations around the world have been conducting baseline measurements of atmospheric CO2 isotopes for several decades, reports on the traceability and maintenance are rare. In this paper, a principle and an approach for maintaining consistent traceability in high-precision isotope measurements (δ13C and δ18O of atmospheric CO2 are described. The concept of Big Delta is introduced and its role in maintaining traceability of the isotope measurements is described and discussed extensively. The uncertainties of the traceability have been estimated based on annual calibration records over the last 10 yr. The overall uncertainties of CO2 isotope measurements for individual ambient samples analyzed by the program at Environment Canada have been estimated (excluding these associated with the sampling. The values are 0.02 and 0.05‰ in δ13C and δ18O, respectively, which are close to the World Meteorological Organization (WMO targets for data compatibility. The annual rates of change in δ13C and δ18O of the primary anchor (which links the flask measurements back to the VPDB-CO2 scale are close to zero (−0.0016 ± 0.0012‰, and −0.006 ± 0.003‰ per year, respectively over a period of 10 yr (2001–2011. The average annual changes of δ13C and δ18O in air CO2 at Alert GAW station over the period from 1999 to 2010 have been evaluated and confirmed; they are −0.025 ± 0.003‰ and 0.000 ± 0.010‰, respectively. The results are consistent with a continuous contribution of fossil fuel CO2 to the atmosphere, having a trend toward more negative in δ13C, whereas the lack of change in δ18O likely reflects the influence from the global hydrologic cycle. The total change of δ13C and δ18O during this period is ~0.27‰ and ~0.00

  15. Biological CO2 fixation using Chlorella vulgaris and its thermal characteristics through thermogravimetric analysis.

    Science.gov (United States)

    Razzak, Shaikh A; Ali, Saad Aldin M; Hossain, Mohammad M; Mouanda, Alexis Nzila

    2016-11-01

    The present research is focused on cultivation of microalgae strain Chlorella vulgaris for bio-fixation of CO2 coupled with biomass production. In this regard, a single semi-batch vertical tubular photobioreactor and four similar photobioreactors in series have been employed. The concentration of CO2 in the feed stream was varied from 2 to 12 % (v/v) by adjusting CO2 to air ratio. The amount of CO2 capture and algae growth were monitored by measuring decrease of CO2 concentration in the gas phase, microalgal cell density, and algal biomass production rate. The results show that 4 % CO2 gives maximum amount of biomass (0.9 g L(-1)) and productivity (0.118 g L(-1) day(-1)) of C. vulgaris in a single reactor. In series reactors, average productivity per reactor found to be 0.078 g L(-1) day(-1). The maximum CO2 uptake for single reactor also found with 4 % CO2, and it is around 0.2 g L(-1) day(-1). In series reactors, average CO2 uptake is 0.13 g L(-1) day(-1) per reactor. TOC analysis shows that the carbon content of the produced biomass is around 40.67 % of total weight. The thermochemical characteristics of the cultivated C. vulgaris samples were analyzed in the presence of air. All samples burn above 200 °C and the combustion rate become faster at around 600 °C. Almost 98 wt% of the produced biomass is combustible in this range.

  16. Sensitivity analysis and quantification of uncertainty for isotopic mixing relationships in carbon cycle research

    Science.gov (United States)

    Zobitz, J. M.; Keener, J. P.; Bowling, D. R.

    2004-12-01

    Quantifying and understanding the uncertainty in isotopic mixing relationships is critical to isotopic applications in carbon cycle studies at all spatial and temporal scales. Studies associated with the North American Carbon Program will depend on stable isotope approaches and quantification of isotopic uncertainty. An important application of isotopic mixing relationships is determination of the isotopic content of large-scale respiration (δ 13CR) via an inverse relationship (a Keeling plot) between atmospheric CO2 concentrations ([CO2]) and carbon isotope ratios of CO2 (δ 13C). Alternatively, a linear relationship between [CO2] and the product of [CO2] and δ 13C (a Miller/Tans plot) can also be applied. We used an extensive dataset from the Niwot Ridge Ameriflux Site of [CO2] and δ 13C in forest air to examine contrasting approaches to determine δ 13CR and its uncertainty. These included Keeling plots, Miller/Tans plots, Model I, and Model II regressions Our analysis confirms previous observations that increasing the range of measurements ([CO2] range) reduces the uncertainty associated with δ 13CR. For carbon isotope studies, uncertainty in the isotopic measurements has a greater effect on the uncertainty of δ 13CR than the uncertainty in [CO2]. Reducing the uncertainty of isotopic measurements reduces the uncertainty of δ 13CR even when the [CO2] range of samples is small (13CR. We also find for carbon isotope studies no inherent advantage to using either a Keeling or a Miller/Tans approach to determine δ 13CR.

  17. End-tidal CO2 analysis in sleep apnea syndrome. Conditions for use.

    Science.gov (United States)

    Magnan, A; Philip-Joet, F; Rey, M; Reynaud, M; Porri, F; Arnaud, A

    1993-01-01

    The diagnosis of sleep apnea syndrome (SAS) requires expensive and complex instrumentation. The purpose of the present study was to determine the value of end-tidal CO2 (EtCO2) in screening for sleep apneas. Thirty-nine patients referred to our sleep laboratory because of suspected SAS and ten normal subjects were studied. The EtCO2 was measured using an infrared spectrometer (POET) designed for simultaneous measurement of CO2 and pulse oximetry. In 29 subjects, expired gas was sampled with a nasobuccal mask (Respiron) with lateral orifices. In the other 20 subjects, sampling was done with nasobuccal prongs (Criticare) comprising a four-channel plastic tube to the mouth and the nostrils. Data from an 8-h night were transferred the following day to a microcomputer (Apple Macintosh) for processing. Apnea was defined as an absence of detection of CO2 for more than 10 s. Conventional polysomnography was performed (Respisomnographe). The number of apneas in 8 h and the apnea index (number of apneas in 1 h) were calculated after visual analysis on the screen of the polysomnograph and also with EtCO2 analysis. For recordings made with a nasobuccal mask, the regression curve between the apnea indices computed with EtCO2 and polysomnography was an order 2 polynomial curve (r = 0.76; p < 0.001), with an inflection point at 39 apneas per hour. For recordings with nasobuccal prongs, the correlation was very significant (r = 0.95; p < 0.0001), and the regression curve was linear. The EtCO2 with nasobuccal prongs appears to be a simple and reliable method for screening for SAS.

  18. Temporal Variations of the Atmospheric CO2 Concentration and Its Carbon Isotope Ratio at Ny-Ålesund, Svalbard and Estimation of Global Carbon Budget

    Science.gov (United States)

    Goto, D.; Morimoto, S.; Ishidoya, S.; Aoki, S.; Nakazawa, T.

    2016-12-01

    Long-term measurements of the atmospheric CO2 concentration and its carbon isotope ratio (δ13C) are useful for partitioning anthropogenic CO2 into the terrestrial biosphere and the ocean, if the carbon isotopic disequilibrium flux (so-called isoflux), combining terrestrial and oceanic contributions, is quantified. For a better understanding of the global carbon cycle, we have carried out the systematic observation of the atmospheric CO2 concentration and δ13C at Ny-Ålesund, Svalbard (78.93°N, 11.83°E) since 1991. Air samples were collected into stainless-steel flasks at the Japanese observatory in Ny-Ålesund, once a week and sent to NIPR every two months. CO2 concentrations of the air samples were determined by using a NDIR analyzer, and CO2 samples extracted cryogenically from the remaining air in the flasks were analyzed for δ13C using a mass spectrometer. Analytical precisions for CO2 and δ13C were 0.01 ppm and 0.02 ‰, respectively. The CO2 concentration shows a clear seasonal cycle with peak-to-peak amplitude of about 17 ppm, which reaches a maximum in late April to early May and a minimum in late August, superimposed on a secular increase with an average rate of 2.0 ppm/yr for the period of 1996-2013. On the other hand, the δ13C decreases secularly at an average rate of -0.018 ‰/yr, and varies seasonally in opposite phase with the CO2 concentration. By analyzing the CO2 concentration and δ13C using the isoflux calculated with a box-diffusion model, the terrestrial biospheric and oceanic CO2 sinks are estimated to be 1.5 ± 0.3 and 2.4 ± 0.4 GtC/yr, respectively, for the 13-year period (2001-2013). On the other hand, the secular trends of the atmospheric δ(O2/N2) and CO2 concentration at Ny-Ålesund (Ishidoya et al., 2012) yield the respective sink values of 1.7 ± 0.8 and 2.2 ± 0.7 GtC/yr for the same period. The estimates from the two methods are in good agreement with each other.

  19. CFD analysis of supercritical CO2 used as HTF in a solar tower receiver

    Science.gov (United States)

    Roldán, M. I.; Fernández-Reche, J.

    2016-05-01

    The relative cost of a solar receiver can be minimized by the selection of an appropriate heat transfer fluid capable of achieving high receiver efficiencies. In a conventional central receiver system, the concentrated solar energy is transferred from the receiver tube walls to the heat transfer fluid (HTF), which passes through a heat exchanger to generate steam for a Rankine cycle. Thus, higher working fluid temperature is associated with greater efficiency in receiver and power cycle. Emerging receiver designs that can enable higher efficiencies using advanced power cycles, such as supercritical CO2 (s-CO2) closed-loop Brayton cycles, include direct heating of s-CO2 in tubular receiver designs capable of withstanding high internal fluid pressures (around 20 MPa) and temperatures (900 K). Due to the high pressures required and the presence of moving components installed in pipelines (ball-joints and/or flexible connections), the use of s-CO2 presents many technical challenges due to the compatibility of seal materials and fluid leakages of the moving connections. These problems are solved in solar tower systems because the receiver is fixed. In this regard, a preliminary analysis of a tubular receiver with s-CO2 as HTF has been developed using the design of a molten-salt receiver which was previously tested at Plataforma Solar de Almería (PSA). Therefore, a simplified CFD model has been carried out in this study in order to analyze the feasibility of s-CO2 as HTF in solar towers. Simulation results showed that the heat gained by s-CO2 was around 75% greater than the one captured by molten salts (fluid inlet temperature of 715 K), but at a pressure range of 7.5-9.7 MPa. Thus, the use of s-CO2 as HTF in solar tower receivers appears to be a promising alternative, taking into account both the operating conditions required and their maintenance cost.

  20. Factor Decomposition Analysis of Energy-Related CO2 Emissions in Tianjin, China

    Directory of Open Access Journals (Sweden)

    Zhe Wang

    2015-07-01

    Full Text Available Tianjin is the largest coastal city in northern China with rapid economic development and urbanization. Energy-related CO2 emissions from Tianjin’s production and household sectors during 1995–2012 were calculated according to the default carbon-emission coefficients provided by the Intergovernmental Panel on Climate Change. We decomposed the changes in CO2 emissions resulting from 12 causal factors based on the method of Logarithmic Mean Divisia Index. The examined factors were divided into four types of effects: energy intensity effect, structure effect, activity intensity effect, scale effect and the various influencing factors imposed differential impacts on CO2 emissions. The decomposition outcomes indicate that per capita GDP and population scale are the dominant positive driving factors behind the growth in CO2 emissions for all sectors, while the energy intensity of the production sector is the main contributor to dampen the CO2 emissions increment, and the contributions from industry structure and energy structure need further enhancement. The analysis results reveal the reasons for CO2 emission changes in Tianjin and provide a solid basis upon which policy makers may propose emission reduction measures and approaches for the implementation of sustainable development strategies.

  1. Optical Transcutaneous pCO2 Sensor using Soft Lithography Method for Arterial Blood Gas Analysis

    Science.gov (United States)

    Kang, Byoung-Ho; Kim, Do-Eok; Leem, Myoung-Kun; Kwon, Dae-Hyuk; Lee, Kwang-Man; Kang, Shin-Won

    2008-10-01

    In this study, we carried out development of non-invasive optical transcutaneous partial pressure of carbon dioxide, pCO2, monitoring system. The purpose of this system is to detect CO2 from outer skin, not from the arterial blood-gathering method. There are advantages about a reduction of analysis time and real-time monitoring that this system might be available. The measurement system is composed of the IR lamp, the pyroelectric sensor including a 4.26 μm optical filter, the optical gas reaction chamber and the signal processing circuit. The optical reaction length of chamber was reduced by 1 mm using the soft-lithography method which CO2 is exhausted in human body as we considered. The fabricated pCO2 monitoring system showed linear result of 6.50×10-6 absorbance/ppm sensitivity for CO2 concentration from 0 ˜5,000 ppm by MFC and about 2 seconds of fast response time. The proposed system can be used in the optical biosensor field for the medical diagnosis such as pCO2 monitoring system and environment monitoring systems.

  2. Life Comparative Analysis of Energy Consumption and CO2 Emissions of Different Building Structural Frame Types

    Directory of Open Access Journals (Sweden)

    Sangyong Kim

    2013-01-01

    Full Text Available The objective of this research is to quantitatively measure and compare the environmental load and construction cost of different structural frame types. Construction cost also accounts for the costs of CO2 emissions of input materials. The choice of structural frame type is a major consideration in construction, as this element represents about 33% of total building construction costs. In this research, four constructed buildings were analyzed, with these having either reinforced concrete (RC or steel (S structures. An input-output framework analysis was used to measure energy consumption and CO2 emissions of input materials for each structural frame type. In addition, the CO2 emissions cost was measured using the trading price of CO2 emissions on the International Commodity Exchange. This research revealed that both energy consumption and CO2 emissions were, on average, 26% lower with the RC structure than with the S structure, and the construction costs (including the CO2 emissions cost of the RC structure were about 9.8% lower, compared to the S structure. This research provides insights through which the construction industry will be able to respond to the carbon market, which is expected to continue to grow in the future.

  3. A meta-analysis of plant physiological and growth responses to temperature and elevated CO(2).

    Science.gov (United States)

    Wang, Dan; Heckathorn, Scott A; Wang, Xianzhong; Philpott, Stacy M

    2012-05-01

    Atmospheric carbon dioxide (CO(2)) and global mean temperature are expected to be significantly higher by the end of the 21st century. Elevated CO(2) (eCO(2)) and higher temperature each affect plant physiology and growth, but their interactive effects have not been reviewed statistically with respect to higher chronic mean temperatures and abrupt heat stress. In this meta-analysis, we examined the effect of CO(2) on the physiology and growth of plants subjected to different temperature treatments. The CO(2) treatments were categorized into ambient (560 ppm) levels, while temperature treatments were categorized into ambient temperature (AT), elevated temperature (ET; AT + 1.4-6°C), or heat stress (HS; AT + >8°C). Plant species were grouped according to photosynthetic pathways (C(3), C(4)), functional types (legumes, non-legumes), growth forms (herbaceous, woody), and economic purposes (crop, non-crop). eCO(2) enhanced net photosynthesis at AT, ET, and HS in C(3) species (especially at the HS level), but in C(4) species, it had no effect at AT, a positive effect at ET, and a negative effect at HS. The positive effect of eCO(2) on net photosynthesis was greater for legumes than for non-legumes at HS, for non-crops than crops at ET, and for woody than herbaceous species at ET and HS. Total (W (T)) and above- (W (AG)) and below-ground (W (BG)) biomass were increased by eCO(2) for most species groups at all temperatures, except for C(4) species and W (BG) of legumes at HS. Hence, eCO(2) × heat effects on growth were often not explained by effects on net photosynthesis. Overall, the results show that eCO(2) effects on plant physiology and growth vary under different temperature regimes, among functional groups and photosynthetic pathways, and among response variables. These findings have important implications for biomass accumulation and ecosystem functioning in the future when the CO(2) level is higher and climate extremes, such as heat waves, become more frequent.

  4. Autotrophic fixation of geogenic CO2 by microorganisms contributes to soil organic matter formation and alters isotope signatures in a wetland mofette

    DEFF Research Database (Denmark)

    Beulig, Felix

    2015-01-01

    To quantify the contribution of autotrophic microorganisms to organic matter (OM) formation in soils, we investigated natural CO2 vents (mofettes) situated in a wetland in northwest Bohemia (Czech Republic). Mofette soils had higher soil organic matter (SOM) concentrations than reference soils due...... of radiocarbon and enriched in 13C compared to atmospheric CO2. Together, these isotopic signals allow us to distinguish C fixed by plants from C fixed by autotrophic microorganisms using their differences in 13C discrimination. We can then estimate that up to 27 % of soil organic matter in the 0–10 cm layer...... (qPCR) and by acetogenic and methanogenic microorganisms, shown present in the mofettes by previous studies. Combined Δ14C and δ13C isotope mass balances indicated that microbially derived carbon accounted for 8–27 % of bulk SOM in this soil layer. The findings imply that autotrophic microorganisms...

  5. Application of the CO2-PENS risk analysis tool to the Rock Springs Uplift, Wyoming

    Science.gov (United States)

    Stauffer, P.H.; Pawar, R.J.; Surdam, R.C.; Jiao, Z.; Deng, H.; Lettelier, B.C.; Viswanathan, H.S.; Sanzo, D.L.; Keating, G.N.

    2011-01-01

    We describe preliminary application of the CO2-PENS performance and risk analysis tool to a planned geologic CO2 sequestration demonstration project in the Rock Springs Uplift (RSU), located in south western Wyoming. We use data from the RSU to populate CO2-PENS, an evolving system-level modeling tool developed at Los Alamos National Laboratory. This tool has been designed to generate performance and risk assessment calculations for the geologic sequestration of carbon dioxide. Our approach follows Systems Analysis logic and includes estimates of uncertainty in model parameters and Monte-Carlo simulations that lead to probabilistic results. Probabilistic results provide decision makers with a range in the likelihood of different outcomes. Herein we present results from a newly implemented approach in CO 2-PENS that captures site-specific spatially coherent details such as topography on the reservoir/cap-rock interface, changes in saturation and pressure during injection, and dip on overlying aquifers that may be impacted by leakage upward through wellbores and faults. We present simulations of CO 2 injection under different uncertainty distributions for hypothetical leaking wells and faults. Although results are preliminary and to be used only for demonstration of the approach, future results of the risk analysis will form the basis for a discussion on methods to reduce uncertainty in the risk calculations. Additionally, we present ideas on using the model to help locate monitoring equipment to detect potential leaks. By maintaining site-specific details in the CO2-PENS analysis we provide a tool that allows more logical presentations to stakeholders in the region. ?? 2011 Published by Elsevier Ltd.

  6. [Differences and sources of CO2 concentration, carbon and oxygen stable isotope composition between inside and outside of a green space system and influencing factors in an urban area].

    Science.gov (United States)

    Sun, Shou-jia; Meng, Ping; Zhang, Jin-song; Shu, Jian-hua; Zheng, Ning

    2015-10-01

    The off-axis integrated cavity output spectroscopy technique was used to measure air CO2 concentration, stable carbon (δ13C) and oxygen (δ18C) isotope ratios on the Fourth Ring Road (FRR) and in the green space system of Beijing Institute of Landscape Architecture (BILA) in summer and winter seasons. The variations of CO2 concentration, δ13C value, δ18C value and the differences of them between the FRR and the BILA, which were correlated with traffic volume and meteorological factors, were analyzed at half-hour timescale. The results showed that traffic volume on the FRR was large both in summer and winter with obvious morning and evening rush hours, and more than 150 thousands vehicles were observed everyday during the observation periods. Diurnal variation of the CO2 concentration showed a two-peak curve both on the FRR and in the green space system of the BILA. In contrast, diurnal variation of δ13C value was a two-trough curve while diurnal variation of δ18O value was a single-trough curve. The differences of CO2 concentration, δ13C value and δ18O value between the FRR and the green space system of BILA in summer were greater than those in winter. The carbon isotope partitioning results showed that in summer vehicle exhaust contributed 64.9% to total atmospheric CO2 of the FRR during measurement time, while heterotrophic respiration contributed 56.3% to total atmospheric CO2 of the green space system in BILA. However, in winter atmospheric CO2 from both the FRR and green space system mostly came from vehicle exhaust. Stepwise regression analysis indicated that differences of CO2 concentration between the FRR and green space system were significantly related to vehicle volume and solar radiation at half-hour timescale, while solar radiation and relative humidity were the main meteorological factors causing δ13 and δ18O differences between the FRR and green space system. Plants in the green space system strongly assimilated CO2 from fossil fuel burning

  7. C4 plant isotopic composition (delta13C) evidence for urban CO2 pollution in the city of Cotonou, Benin (West Africa).

    Science.gov (United States)

    Kèlomé, Nelly C; Lévêque, Jean; Andreux, Francis; Milloux, Marie-Jeanne; Oyédé, Lucien-Marc

    2006-08-01

    The carbon isotopic composition (delta13C) of plants can reveal the isotopic carbon content of the atmosphere in which they develop. The delta13C values of air and plants depend on the amount of atmospheric fossil fuel CO2, which is chiefly emitted in urban areas. A new indicator of CO2 pollution is tested using the delta13C variation in a C4 grass: Eleusine indica. A range of about 4 per thousand delta units was observed at different sites in Cotonou, the largest city in the Republic of Benin. The highest delta13C values, from -12 per thousand to -14 per thousand, were found in low traffic zones; low delta13C values, from -14 per thousand to -16 per thousand, were found in high traffic zones. The amount of fossil fuel carbon assimilated by plants represented about 20% of the total plant carbon content. An overall decrease in plant delta13C values was observed over a four-year monitoring period. This decrease was correlated with increasing vehicle traffic. The delta13C dataset and the corresponding geographical database were used to map and define zones of high and low 13C-depleted CO2 emissions in urban and sub-urban areas. The spatial distribution follows dominant wind directions, with the lowest emission zones found in the southwest of Cotonou. High CO2 emissions occurred in the north, the east and the center, providing evidence of intense anthropogenic activity related to industry and transportation.

  8. The CO2 consumption potential during gray shale weathering: Insights from the evolution of carbon isotopes in the Susquehanna Shale Hills critical zone observatory

    Science.gov (United States)

    Jin, Lixin; Ogrinc, Nives; Yesavage, Tiffany; Hasenmueller, Elizabeth A.; Ma, Lin; Sullivan, Pamela L.; Kaye, Jason; Duffy, Christopher; Brantley, Susan L.

    2014-10-01

    Shale covers about 25% of the land surface, and is therefore an important rock type that consumes CO2 during weathering. We evaluated the potential of gray shale to take up CO2 from the atmosphere by investigating the evolution of dissolved inorganic carbon (DIC) concentrations and its carbon isotopic ratio (δ13CDIC) along water flow paths in a well-characterized critical zone observatory (Susquehanna Shale Hills catchment). In this catchment, chemical weathering in shallow soils is dominated by clay transformation as no carbonates are present, and soil pore waters are characterized by low DIC and pH. In shallow soil porewaters, the DIC, dominated by dissolved CO2, is in chemical and isotopic equilibrium with CO2 in the soil atmosphere where pCO2 varies seasonally to as high as 40 times that of the atmosphere. The degradation of ancient organic matter is negligible in contributing to soil CO2. The chemistry of groundwater varies along different flowpaths as soil pore water recharges to the water table and then dissolves ankerite or secondary calcite under the valley floor. Weathering of carbonate leads to much higher concentrations of DIC (∼2500 μmol/L) and divalent cations (Ca2+ and Mg2+) in groundwaters than soil waters. The depth to the ankerite weathering front is hypothesized to be roughly coincident with the water table but it varies due to heterogeneities in the protolith composition. Groundwater chemistry therefore shows different saturation indices with respect to ankerite depending upon location along the valley. The δ13CDIC values of these groundwaters document mixing between the ankerite and soil CO2. The major element concentrations, DIC, and δ13CDIC in the first-order stream incising the valley of the catchment are derived from groundwater and soil waters in proportions that vary both spatially and temporally. The CO2 degassed slightly in the stream but little evidence of C isotopic equilibration with the atmosphere is observed, due to the short

  9. Performance analysis of a zeotropic mixture (R290/CO2) for trans-critical power cycle☆

    Institute of Scientific and Technical Information of China (English)

    Lisheng Pan; Xiaolin Wei; Weixiu Shi

    2015-01-01

    Low critical temperature limits the application of CO2 trans-critical power cycle. The binary mixture of R290/CO2 has higher critical temperature. Using mixture fluid may solve the problem that subcritical CO2 is hardly con-densed by conventional cooling water. In this article, theoretical analysis is executed to study the performance of the zeotropic mixture for trans-critical power cycle using low-grade liquid heat source with temperature of 200 °C. The results indicated that the problem that CO2 can't be condensed in power cycle by conventional cooling water can be solved by mixing R290 to CO2. Variation trend of outlet temperature of thermal oil in super-critical heater with heating pressure is determined by the composition of the mixture fluid. Gliding temperature causes the maximum outlet temperature of cooling water with the increase of mass fraction of R290. There are the maximum values for cycle thermal efficiency and net power output with the increase of supercritical heating pressure.

  10. Analysis of Transport Policy Effect on CO2 Emissions Based on System Dynamics

    Directory of Open Access Journals (Sweden)

    Shuang Liu

    2015-01-01

    Full Text Available CO2 emission from the transport sector attracts the attention of both transport and climate change policymakers because of its share in total green house gas emissions and the forecast of continuous growth reported in many countries. This paper takes the urban transport in Beijing as a case and builds a system dynamics model for analysis of the motorization trend and the assessment of CO2 emissions mitigation policy. It is found that the urban transport condition and CO2 emissions would be more serious with the growth of vehicle ownership and travel demand. Compared with the baseline do-nothing scenario, the CO2 emissions could be reduced from 3.8% to 24.3% in 2020 by various transport policies. And the policy of controlling the number of passenger cars which has been carried out in Beijing and followed by some cities could achieve good results, which may help to increase the proportion of public transit to 55.6% and reduce the CO2 emission by 18.3% compared with the baseline scenario in 2020.

  11. Changing Urban Form and Transport CO2 Emissions: An Empirical Analysis of Beijing, China

    Directory of Open Access Journals (Sweden)

    Yunjing Wang

    2014-07-01

    Full Text Available Decentralization development and changing urban form will increase the mobility and contribute to global CO2 emissions, in particular for developing countries which are experiencing rapid economic growth and urban expansion. In this paper, an integrated analytical framework, which can quantify the impact of changing urban form on commuting CO2 emissions, is presented. This framework simultaneously considers two emission dependent factors, commuting demand and modal share based on the concept of excess commuting and accessibility analysis, and ensures its applicability to other cities where the detailed individual travel data is not available. A case study of Beijing from 2000 to 2009 is used to illustrate this framework. The findings suggest that changing urban form in Beijing did have a significant impact on commuting CO2 emission increase. Changing to a more decentralized urban form in Beijing had a larger impact on commuting distance and increased usage of cars, which resulted in a significant rise in CO2 emissions. There is a larger space and an urgent need for commuting CO2 emission reduction, in 2009 in Beijing, by planning and by strategic measures in order to promote sustainable transport.

  12. Controllability and flexibility analysis of CO2 post-combustion capture using piperazine and MEA

    DEFF Research Database (Denmark)

    Gaspar, Jozsef; Ricardez-Sandoval, Luis; Jørgensen, John Bagterp

    2016-01-01

    In this study, we developed a decentralized control scheme and investigate the performance of the piperazine (PZ) and monoethanolamine (MEA) CO2 capture process for industrially-relevant operation scenarios. The base for the design of the control schemes is Relative Gain Array (RGA) analysis...... a critical operational bottleneck, especially when PZ is being used. The MEA plant controllers drive the system towards drying out/flooding while the CO2 capture rate performance of the PZ plant reduces drastically in the presence of constraints in the availability of steam. These findings suggest the need...

  13. The Decomposition Analysis of CO2 Emission and Economic Growth in Pakistan India and China

    OpenAIRE

    Muhammad Irfan Javaid Attari; Sumayya Nasim Attaria

    2011-01-01

    The conflict between economic growth and keeping greenhouse gases (GHG) at controllable levels is one of the ultimate challenges of this century. The aim of Kyoto Protocol is to keep the level of carbon dioxide (CO2) below a certain threshold level. The purpose of this paper is to study the effect of CO2 emission on economic growth by conducting the regional analysis of PIC nations i.e. Pakistan, India and China. The study also provides the detail information regarding the atmospheric emissio...

  14. Increasing Ambient CO2 Concentrations are Reflected in the Stable C and O Isotopes from Tree Rings along a Siberian North South Transect in the Last 150 Years

    Science.gov (United States)

    Siegwolf, R. T.; Sidorova, O. V.; Saurer, M.; Knorre, A.; Kirdyanov, A.

    2010-12-01

    The ongoing industrialization in the last 150 years left its fingerprints with an increase in atmospheric CO2 (ca) from ca. 260 to 385 ppm due to the growing use of fossil fuels. Elevated CO2 affects the vegetation, as plants respond instantaneously with an increased photosynthetic rate, and a reduction in stomatal conductance. This results in a lower ci/ca ratio (ci leaf intercellular CO2 concentration), causing a reduced 13C fractionation during photosynthesis. This is reflected in the intrinsic water use efficiency (WUEi), although plants acclimatize, i.e. down regulate the maximum photosynthetic capacity (Amax) as a consequence of elevated CO2 for the last 150 years. The degree of the long-term response to changes in CO2 varies largely between plants growing under different growth conditions, i.e. water availability, temperature, nutrient supply and between different species. Along with an increasing CO2 concentration a rise in the mean annual temperature is observed at the Northern timberline. An increasing temperature might stimulate tree growth, yet it also increases the Air to Leaf Vapor Pressure Difference (ALVPD), resulting in an increase of drought stress, as the precipitation in the Siberian regions is rather low. This will induce a reduction in stomatal conductance and a diminished productivity, reflected in tree ring width. We present C and O isotope values from tree rings for the last 150 years. The data reflect changes in the carbon water relations (WUEi) from central Siberia (Russia) along a north south transect of ca. 2400 km from the northern timberline to the forest steppe. Changes in the environment either increase or reduce the effect of elevated CO2 on trees, growing in the highly sensitive Siberian ecosystem. The combination of the C and O isotope values in a conceptual model (Scheidegger et al., 2000; Saurer and Siegwolf, 2007) allows the link between tree response reflected in δ13C and δ18O data and gas exchange patterns providing a

  15. Uncertainty analysis of CO2 flux components in subtropical evergreen coniferous plantation

    Institute of Scientific and Technical Information of China (English)

    LIU Min; HE HongLin; YU GuiRui; LUO YiQi; SUN XiaoMin; WANG HuiMin

    2009-01-01

    We present an uncertainty analysis of ecological process parameters and CO2 flux components (Reco, NEE and gross ecosystem exchange (GEE)) derived from 3 years continuous eddy covariance meas-urements of CO2 fluxes at subtropical evergreen coniferous plantation, Qianyanzhou of ChinaFlux. Daily-differencing approach was used to analyze the random error of CO2 fluxes measurements and bootstrapping method was used to quantify the uncertainties of three CO2 flux components. In addition, we evaluated different models and optimization methods in influencing estimation of key parameters and CO2 flux components. The results show that: (1) Random flux error more closely follows a dou-ble-exponential (Laplace), rather than a normal (Gaussian) distribution. (2) Different optimization meth-ods result in different estimates of model parameters. Uncertainties of parameters estimated by the maximum likelihood estimation (MLE) are lower than those derived from ordinary least square method (OLS). (3) The differences between simulated Rrco, NEE and GEE derived from MLE and those derived for a given parameter optimization method, e temperature-dependent model (T_model) and the models methods are more important than the ecological models in influencing uncertainty in estimated carbon fluxes. (4) The relative uncertainty of CO2 flux derived from OLS is higher than that from MLE, and the uncertainty is related to timescale, that is, the larger the timescale, the smaller the uncertainty. The relative uncertainties of Reco, NEE and GEE are 4%-8%, 7%-22% and 2%-4% respectively at annual timescale.

  16. In vacuo reduction of silver orthophosphate with graphite for high-precision oxygen isotope analysis.

    Science.gov (United States)

    Pelc, Andrzej; Halas, Stanislaw

    2010-10-15

    The reduction of silver phosphate with graphite under vacuum conditions was studied at final reaction temperatures varying from 430 to 915°C to determine: (i) the CO(2) extraction yield, and (ii) the oxygen isotopic composition of CO(2). The CO(2) yield and oxygen isotopic composition were determined on a calibrated dual inlet and triple collector isotope ratio mass spectrometer. We observed the following three stages of the reduction process. (1) At temperatures below 590°C only CO(2) is formed, while silver orthophosphate decays to pyrophosphate. (2) At higher temperatures, 590-830°C, predominantly CO is formed from silver pyrophosphate which decays to metaphosphate; this CO was always converted into CO(2) by the glow discharge method. (3) At temperatures above 830°C the noticeable sublimation of silver orthophosphate occurs. This observation was accompanied by the oxygen isotope analysis of the obtained CO(2). The measured δ(18)O value varied from -11.93‰ (at the lowest temperature) to -20.32‰ (at the highest temperature). The optimum reduction temperature range was found to be 780-830°C. In this temperature range the oxygen isotopic composition of CO(2) is nearly constant and the reaction efficiency is relatively high. The determined difference between the δ(18)O value of oxygen in silver phosphate and that in CO(2) extracted from this phosphate is +0.70‰. Copyright © 2010 John Wiley & Sons, Ltd.

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

    Energy Technology Data Exchange (ETDEWEB)

    Moran, James J.; Whitmore, Laura M.; Jay, Zackary J.; Jennings, Ryan deM.; Beam, Jacob P.; Kreuzer, Helen W.; Inskeep, William P.

    2017-07-01

    Volcanism and post-magmatism contribute both significant annual CH4 fluxes to the atmosphere (on par with other natural sources such as forest fire and wild animal emissions) and have been implicated in past climate-change events. The Yellowstone hot spot is one of the largest volcanic systems on Earth and is known to emit methane in addition to other greenhouse gases (e.g. carbon dioxide) but the ultimate source of this methane flux has not been elucidated. Here we use dual stable isotope analysis2H and δ13C) of CH4(g) sampled from ten high-temperature geothermal pools in Yellowstone National Park to show that the predominant flux of CH4(g) is abiotic. The average δ13C and δ2H values of CH4(g) emitted from hot springs (-26.7 (±2.4) and -236.9 (±12.0) ‰, respectively) are not consistent with biotic (microbial or thermogenic) methane sources, but are within previously reported ranges for abiotic methane production. Correlation between δ13CCH4 and δ13C-dissolved inorganic C (DIC) also suggests that CO2 is a parent C source for the observed CH4(g). Moreover, CH4-CO2 isotopic geothermometry was used to estimate CH4(g) formation temperatures ranging from ~ 250 - 350°C, which is just below the temperature estimated for the hydrothermal reservoir and consistent with the hypothesis that subsurface, rock-water interactions are responsible for large methane fluxes from this volcanic system. An understanding of conditions leading to the abiotic production of methane and associated isotopic signatures are central to understanding the evolutionary history of deep carbon sources on Earth.

  18. A dynamic leaf gas-exchange strategy is conserved in woody plants under changing ambient CO2: evidence from carbon isotope discrimination in paleo and CO2 enrichment studies

    Science.gov (United States)

    Voelker, Steven L.; Brooks, J. Renée; Meinzer, Frederick C.; Anderson, Rebecca D.; Bader, Martin K.-F.; Battipaglia, Giovanna; Becklin, Katie M.; Beerling, David; Bert, Didier; Betancourt, Julio L.; Dawson, Todd E.; Domec, Jean-Christophe; Guyette, Richard P.; Körner, Christian; Leavitt, Steven W.; Linder, Sune; Marshall, John D.; Mildner, Manuel; Ogée, Jérôme; Panyushkina, Irina P.; Plumpton, Heather J.; Pregitzer, Kurt S.; Saurer, Matthias; Smith, Andrew R.; Siegwolf, Rolf T.W.; Stambaugh, Michael C.; Talhelm, Alan F.; Tardif, Jacques C.; Van De Water, Peter K.; Ward, Joy K.; Wingate, Lisa

    2016-01-01

    Rising atmospheric [CO2], ca, is expected to affect stomatal regulation of leaf gas-exchange of woody plants, thus influencing energy fluxes as well as carbon (C), water, and nutrient cycling of forests. Researchers have proposed various strategies for stomatal regulation of leaf gas-exchange that include maintaining a constant leaf internal [CO2], ci, a constant drawdown in CO2(ca − ci), and a constant ci/ca. These strategies can result in drastically different consequences for leaf gas-exchange. The accuracy of Earth systems models depends in part on assumptions about generalizable patterns in leaf gas-exchange responses to varying ca. The concept of optimal stomatal behavior, exemplified by woody plants shifting along a continuum of these strategies, provides a unifying framework for understanding leaf gas-exchange responses to ca. To assess leaf gas-exchange regulation strategies, we analyzed patterns in ci inferred from studies reporting C stable isotope ratios (δ13C) or photosynthetic discrimination (∆) in woody angiosperms and gymnosperms that grew across a range of ca spanning at least 100 ppm. Our results suggest that much of the ca-induced changes in ci/ca occurred across ca spanning 200 to 400 ppm. These patterns imply that ca − ci will eventually approach a constant level at high ca because assimilation rates will reach a maximum and stomatal conductance of each species should be constrained to some minimum level. These analyses are not consistent with canalization toward any single strategy, particularly maintaining a constant ci. Rather, the results are consistent with the existence of a broadly conserved pattern of stomatal optimization in woody angiosperms and gymnosperms. This results in trees being profligate water users at low ca, when additional water loss is small for each unit of C gain, and increasingly water-conservative at high ca, when photosystems are saturated and water loss is large for each unit C gain.

  19. Advanced exergy analysis of transcritical CO2 heat pump system based on experimental data

    Indian Academy of Sciences (India)

    JAHAR SARKAR; DNYANESH JOSHI

    2016-11-01

    Conventional exergy analysis identifies component exergy destruction, however, does not give clear picture whether occurs because of component itself or due to remaining components and then the advanced exergy analysis is emphasized. The main purpose of this study is to apply advanced exergy analysis to the transcritical CO2 vapor compression heat pump system for simultaneous water cooling and heating, along withthe conventional exergy analysis. The novelty of the present study is the advanced exergy analysis (with modified methodology) of transcritical superheat cycle based on experimental data. Endogenous, exogenous, avoidable and unavoidable exergy destructions are determined for each component of this system. Results showthat compressor is having highest exergy destruction among the CO2system components and also its major partis avoidable endogenous exergy destruction. According to conventional exergy analysis, the sequence for improvement seems to be compressor, gas cooler, expansion valve and evaporator; however, the in-depthanalysis (advanced exergy analysis) shows compressor is the first component followed by evaporator, gas cooler and expansion valve to be considered for improvisation. Thus it is concluded that compressor provides highest opportunity for improvement and new design of the same will improve overall transcritical CO2 system performance.

  20. Isotope ratios of H, C, and O in CO2 and H2O of the martian atmosphere

    NARCIS (Netherlands)

    Webster, C.R.; Mahaffy, P.R.; Flesch, G.J.; Niles, P.B.; Jones, J.H.; Leshin, L.A.; Atreya, S.K.; Stern, J.C.; Christensen, L.E.; Owen, T.; Franz, H.; Pepin, R.O.; Steele, A.; MSL Science Team, the

    2013-01-01

    Stable isotope ratios of H, C, and O are powerful indicators of a wide variety of planetary geophysical processes, and for Mars they reveal the record of loss of its atmosphere and subsequent interactions with its surface such as carbonate formation. We report in situ measurements of the isotopic ra

  1. Analysis of Pacific oyster larval proteome and its response to high-CO2

    KAUST Repository

    Dineshram, R.

    2012-10-01

    Most calcifying organisms show depressed metabolic, growth and calcification rates as symptoms to high-CO2 due to ocean acidification (OA) process. Analysis of the global expression pattern of proteins (proteome analysis) represents a powerful tool to examine these physiological symptoms at molecular level, but its applications are inadequate. To address this knowledge gap, 2-DE coupled with mass spectrophotometer was used to compare the global protein expression pattern of oyster larvae exposed to ambient and to high-CO2. Exposure to OA resulted in marked reduction of global protein expression with a decrease or loss of 71 proteins (18% of the expressed proteins in control), indicating a wide-spread depression of metabolic genes expression in larvae reared under OA. This is, to our knowledge, the first proteome analysis that provides insights into the link between physiological suppression and protein down-regulation under OA in oyster larvae. © 2012 Elsevier Ltd.

  2. Comment on "Changes in atmospheric CO2 levels recorded by the isotopic signature of n-alkanes from plants" from K.S. Machado and S. Froehner

    Science.gov (United States)

    Köhler, Peter; Nehrbass-Ahles, Christoph; Schmitt, Jochen; Stocker, Thomas F.; Fischer, Hubertus

    2017-09-01

    The recently published invited research article by Machado and Froehner (2017) is presenting δ13C values from sedimentary organic matter (n-alkane), measured on samples collected in the Barigui watershed (Brazil) covering the last 400 years. The derived δ13C time series based on C27n-alkane, beginning approximately in the calendar year 1600 (or 1600 CE; with CE for Common Era) until recent times is subsequently - in their Fig. 3 - compared with a record, which is believed to be a representative reconstruction of atmospheric CO2 concentrations covering approximately the last 650 years (with respect to the year 2005 CE). The final conclusion of this article, as reflected in its title, is that changes in atmospheric CO2 levels are recorded in isotopic signatures on n-alkane from plants. We argue, that this conclusion can not be drawn from the study of Machado and Froehner (2017), since what is shown in their Fig. 3 is not a time series of atmospheric CO2 concentration of the last 650 years. The authors show reconstructions of atmospheric CO2 concentrations based on Antarctic ice cores over the past 650,000 years and use them for the past 650 years by ignoring the fact that the time scale in IPCC (2007), from which, according to the caption of their Fig. 3, they took this CO2 time series, is in kyr (1 kyr = 1 kilo year = 1000 years). This is wrong and any conclusion based on this comparison is incorrect. Instead they should have used for a correct CO2 time series for the comparison with their measurements.

  3. Probabilistic modeling and global sensitivity analysis for CO 2 storage in geological formations: a spectral approach

    KAUST Repository

    Saad, Bilal M.

    2017-09-18

    This work focuses on the simulation of CO2 storage in deep underground formations under uncertainty and seeks to understand the impact of uncertainties in reservoir properties on CO2 leakage. To simulate the process, a non-isothermal two-phase two-component flow system with equilibrium phase exchange is used. Since model evaluations are computationally intensive, instead of traditional Monte Carlo methods, we rely on polynomial chaos (PC) expansions for representation of the stochastic model response. A non-intrusive approach is used to determine the PC coefficients. We establish the accuracy of the PC representations within a reasonable error threshold through systematic convergence studies. In addition to characterizing the distributions of model observables, we compute probabilities of excess CO2 leakage. Moreover, we consider the injection rate as a design parameter and compute an optimum injection rate that ensures that the risk of excess pressure buildup at the leaky well remains below acceptable levels. We also provide a comprehensive analysis of sensitivities of CO2 leakage, where we compute the contributions of the random parameters, and their interactions, to the variance by computing first, second, and total order Sobol’ indices.

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

    Science.gov (United States)

    Ghorbani, Ramin; Schmidt, Florian M.

    2017-05-01

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

  5. Thermodynamic Analysis and Experimental Study on Reaction of CO2 Gas with Hot Metal

    Institute of Scientific and Technical Information of China (English)

    Guo WEI; Zhi-tao LI; Zi-liang LI; Qiang-jian GAO; Feng-man SHEN

    2016-01-01

    The reaction of CO2 gas with hot metal was investigated based on the thermodynamic analysis and experi-mental results.It shows that both silicon and carbon in hot metal can be oxidized by CO2 gas in the temperature range of 1 300-1 500 ℃.When using graphite crucible,temperature has little influence on final mass percent of car-bon w[C] because of the carburization effect.Decarburization degree rises significantly with increasing gas inj ection rate and w[C] can be reduced to 3�2% at most when using MgO crucible.Lower temperature or higher gas inj ection rate is propitious to promote desilication reaction,but only 5%-10% of desilication ratio could be obtained in 20 min. The final mass percent of silicon w[Si] when using MgO crucible is lower than that when using graphite crucible.Ex-perimental results also demonstrate that CO2 injection has no effect on the concentration of manganese,sulfur and phosphorus in hot metal.In view of the weak oxidation ability and temperature drop of hot metal,CO2 gas is sugges-ted to be used as carrier gas in desilication process rather than oxidizing agent.

  6. Radiocarbon analysis of stratospheric CO2 retrieved from AirCore sampling

    Science.gov (United States)

    Paul, Dipayan; Chen, Huilin; Been, Henk A.; Kivi, Rigel; Meijer, Harro A. J.

    2016-10-01

    Radiocarbon (14C) is an important atmospheric tracer and one of the many used in the understanding of the global carbon budget, which includes the greenhouse gases CO2 and CH4. Measurement of radiocarbon in atmospheric CO2 generally requires the collection of large air samples (a few liters) from which CO2 is extracted and then the concentration of radiocarbon is determined using accelerator mass spectrometry (AMS). However, the regular collection of air samples from the stratosphere, for example using aircraft and balloons, is prohibitively expensive. Here we describe radiocarbon measurements in stratospheric CO2 collected by the AirCore sampling method. AirCore is an innovative atmospheric sampling system, which comprises a long tube descending from a high altitude with one end open and the other closed, and it has been demonstrated to be a reliable, cost-effective sampling system for high-altitude profile (up to ≈ 30 km) measurements of CH4 and CO2. In Europe, AirCore measurements have been being performed on a regular basis near Sodankylä (northern Finland) since September 2013. Here we describe the analysis of samples from two such AirCore flights made there in July 2014, for determining the radiocarbon concentration in stratospheric CO2. The two AirCore profiles were collected on consecutive days. The stratospheric part of the AirCore was divided into six sections, each containing ≈ 35 µg CO2 ( ≈ 9.6 µgC), and stored in a stratospheric air subsampler constructed from 1/4 in. coiled stainless steel tubing ( ≈ 3 m). A small-volume extraction system was constructed that enabled > 99.5 % CO2 extraction from the stratospheric air samples. Additionally, a new small-volume high-efficiency graphitization system was constructed for graphitization of these extracted CO2 samples, which were measured at the Groningen AMS facility. Since the stratospheric samples were very similar in mass, reference samples were also prepared in the same mass range for

  7. CO2 laser modeling

    Science.gov (United States)

    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.

  8. Unusual isotopic composition of C-CO2 from sterilized soil microcosms: a new way to separate intracellular from extracellular respiratory metabolisms.

    Science.gov (United States)

    Kéraval, Benoit; Alvarez, Gaël; Lehours, Anne Catherine; Amblard, Christian; Fontaine, Sebastien

    2015-04-01

    intact cells were observed by microscopy. These "ghost" cells were completely destroyed by the irradiation-autoclaving combination releasing large amount of soluble C. The soil respiration (O2 consumption and CO2 production) was reduced by irradiation and autoclaving but not stopped, suggesting the presence of an EXOMET. The delta 13C of CO2 released in the irradiated-autoclaved soil was strongly depleted (-70‰) indicating that this extracellular metabolism induced a substantial isotopic fractionation. Our findings suggest that two main oxidative metabolisms co-occur in soils: cell respiration and EXOMET. The isotopic fractionation induced by the EXOMET open perspectives for its quantification in non-sterilized living soils.

  9. Combined and isolated effects of pCO2 and soil water content on carbon isotope discrimination during C3 photosynthesis

    Science.gov (United States)

    Schubert, B.; Jahren, A. H.

    2016-12-01

    Biomass produced via C3 photosynthesis dominates the terrestrial organic matter (TOM) found within the geologic record. Our previous work revealed an increase in net discrimination (Δ13C) ≈ +4‰ across an increase in pCO2 level from ambient to RCO2 = 6x within the model C3 plant Arabidopsis thaliana, grown to maturity under constant conditions of light, moisture, and nutrient availability (Schubert and Jahren, 2012, GCA), leading us to suggest that changes in ancient pCO2 level can be reconstructed from Δ13C within terrestrial sediments. Others have observed an average change in Δ13C ≈ +4‰ when comparing the δ13C value of herbarium samples collected from cool-cold forests to tropical environments against the MAP recorded (Diefendorf et al., 2010, PNAS), leading those authors to suggest that changes in the Δ13C value of TOM recovered from the geological record can be interpreted as changes in precipitation level and/or water availability. Because decreasing moisture availability and increasing pCO2 level exert control over Δ13C through distinctly different mechanisms (i.e., decreased stomatal conductance vs. inhibition of photorespiration, respectively), a simultaneous change in both pCO2 level and moisture availability could combine to influence carbon isotope fractionation. Here we present experiments in which we grew 230 A. thaliana plants at each of 5 levels of pCO2: 390, 685, 1075, 1585, and 2175 ppmv. Within each growth chamber, soil moisture content (θm) was maintained at 1.50 g g-1 for 11 days following germination. Afterwards, we allowed 170 of the plants to dry to θm = 0.83, 0.44, and 0.38 g g-1. After 3 weeks of total growth, tissues were analyzed for δ13C value. We compare the isolated and combined effects of pCO2 and soil moisture upon carbon isotope fractionation across the total range of pCO2 levels reconstructed for the last 350 million years and across moisture levels associated with a 4.5x change in plant biomass.

  10. Maximization of yield of C-13 isotope by multiphoton dissociation of Freon-22 using high average power TEA CO2 laser

    Indian Academy of Sciences (India)

    Manoj Kumar; Anant Deshpande; Chintan Gupta; A K Biswas; A K Nath

    2002-12-01

    Selective multi-photon dissociation (MPD) of Freon-22 (CF2HCl) molecules has been carried out using a TEA CO2 laser at various CO2 laser lines (9(20)-9(26)) in order to maximize the yield of C-13 isotope in the product (C2F4) at an enrichment factor of 100. The effects of laser pulse tail due to the presence of N2 in the laser mixture on the enrichment factor and yield of C-13 are investigated. It is found that the addition of a small amount of N2 is possible in the laser mixture without a significant drop in the yield at desired enrichment factor. Addition of a small amount of N2 improves the laser efficiency considerably. At a given pulse energy, a slight change in the near field intensity distribution of a laser severely affects the selectivity of C-13 isotope. The computed far-field intensity distributions of the measured near-field intensities show marked spatial variation in the focal spots that leads to a drop in selectivity. For macroscopic production of C-13 isotope a simple and novel multi-pass cavity has been designed and tested to focus the energy repeatedly keeping the optimum fluence constant at each focal spot.

  11. Pore-scale Analysis on Physics Property Changes of CO2 Bleached Sandstone, Entrada Fromation, Utah

    Science.gov (United States)

    Han, J.; Keehm, Y.

    2012-12-01

    Since carbon dioxide injected into geological formations can cause a variety of physical and chemical reaction with minerals, it is important to evaluate the characteristics and aspects of these effects in CO2 geological sequestration. For the analog of the phenomena, we conducted pore-scale analysis on porosity and permeability changes and their characteristics for CO2-bleached Entrada formation, Utah due to natural leakage of CO2. From thin section analysis, we observed mineralogical and pore-shape changes: precipitation of carbonate minerals. Then, we estimated porosity and permeability from thin section, using a computational rock physics technique. The estimated porosity of unbleached sample is approximately 13% and that of bleached sample is around 10%, which implies the precipitation of carbonate minerals. The estimated permeability showed a little differences between two samples. This observations seems to imply that the precipitation would occur where permeability is not significantly affected: grain contacts. For more systematic analysis, we obtained 3D pore microstructures by X-ray microtomography technique. The preliminary analysis using the 3D pore microstructures showed similar results to what we found in the thin-section analysis. And a set of simulations for porosity and permeability are now being conducted. The final result will help understand how injected CO2 changes pore structures and physical properties such as porosity and permeability, and will also help accurate monitoring of geological storage sites. Acknowledgement: This work was supported by the Energy Resources R&D program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy (No. 2010201020001A).

  12. Analysis of the PKT correction for direct CO2 flux measurements over the ocean

    Directory of Open Access Journals (Sweden)

    S. Landwehr

    2013-10-01

    Full Text Available Eddy covariance measurements of air–sea CO2 fluxes can be affected by cross-sensitivities of the CO2 measurement to water vapour, resulting in order-of-magnitude biases. Well established causes for these biases are (i cross-sensitivity of the broadband non-dispersive infrared sensors due to band-broadening and spectral overlap (commercial sensors typically correct for this and (ii the effect of air density fluctuations (removed by determining the CO2 mixing ratio respective to dry air. However, another bias related to water vapour fluctuations has recently been observed with open-path sensors, and was attributed to sea salt build-up and water films on sensor optics. Two very different approaches have been used to deal with these water vapour-related biases. Miller et al. (2010 employed a membrane drier to physically eliminate 97% of the water vapour fluctuations in the sample air before it enters the gas analyser. Prytherch et al. (2010a on the other hand, employed the empirical (Peter K. Taylor, PKT post-processing correction to correct open-path sensor data. In this paper, we test these methods side by side using data from the Surface Ocean Aerosol Production (SOAP experiment in the Southern Ocean. The air–sea CO2 flux was directly measured with four closed-path analysers, two of which were positioned down-stream of a membrane dryer. The CO2 fluxes from the two dried gas analysers matched each other and were in general agreement with common parametrisations. The flux estimates from the un-dried sensors agreed with the dried sensors only during periods with low latent heat flux (≤ 7 W m−2. When latent heat flux was higher, CO2 flux estimates from the un-dried sensors exhibited large scatter and an order-of magnitude bias. We applied the PKT correction to the flux data from the un-dried analysers and found that it did not remove the bias when compared to the data from the dried gas analyser. Our detailed analysis of the correction

  13. Analysis of energy-related CO2 emissions and driving factors in five major energy consumption sectors in China.

    Science.gov (United States)

    Cui, Erqian; Ren, Lijun; Sun, Haoyu

    2016-10-01

    Continual growth of energy-related CO2 emissions in China has received great attention, both domestically and internationally. In this paper, we evaluated the CO2 emissions in five major energy consumption sectors which were evaluated from 1991 to 2012. In order to analyze the driving factors of CO2 emission change in different sectors, the Kaya identity was extended by adding several variables based on specific industrial characteristics and a decomposition analysis model was established according to the LMDI method. The results demonstrated that economic factor was the leading force explaining emission increase in each sector while energy intensity and sector contribution were major contributors to emission mitigation. Meanwhile, CO2 emission intensity had no significant influence on CO2 emission in the short term, and energy consumption structure had a small but growing negative impact on the increase of CO2 emissions. In addition, the future CO2 emissions of industry from 2013 to 2020 under three scenarios were estimated, and the reduction potential of CO2 emissions in industry are 335 Mt in 2020 under lower-emission scenario while the CO2 emission difference between higher-emission scenario and lower-emission scenario is nearly 725 Mt. This paper can offer complementary perspectives on determinants of energy-related CO2 emission change in different sectors and help to formulate mitigation strategies for CO2 emissions.

  14. Thermal decomposition of dolomite under CO2: insights from TGA and in situ XRD analysis.

    Science.gov (United States)

    Valverde, Jose Manuel; Perejon, Antonio; Medina, Santiago; Perez-Maqueda, Luis A

    2015-11-28

    Thermal decomposition of dolomite in the presence of CO2 in a calcination environment is investigated by means of in situ X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The in situ XRD results suggest that dolomite decomposes directly at a temperature around 700 °C into MgO and CaO. Immediate carbonation of nascent CaO crystals leads to the formation of calcite as an intermediate product of decomposition. Subsequently, decarbonation of this poorly crystalline calcite occurs when the reaction is thermodynamically favorable and sufficiently fast at a temperature depending on the CO2 partial pressure in the calcination atmosphere. Decarbonation of this dolomitic calcite occurs at a lower temperature than limestone decarbonation due to the relatively low crystallinity of the former. Full decomposition of dolomite leads also to a relatively low crystalline CaO, which exhibits a high reactivity as compared to limestone derived CaO. Under CO2 capture conditions in the Calcium-Looping (CaL) process, MgO grains remain inert yet favor the carbonation reactivity of dolomitic CaO especially in the solid-state diffusion controlled phase. The fundamental mechanism that drives the crystallographic transformation of dolomite in the presence of CO2 is thus responsible for its fast calcination kinetics and the high carbonation reactivity of dolomitic CaO, which makes natural dolomite a potentially advantageous alternative to limestone for CO2 capture in the CaL technology as well as SO2in situ removal in oxy-combustion fluidized bed reactors.

  15. Monte-Carlo based Uncertainty Analysis For CO2 Laser Microchanneling Model

    Science.gov (United States)

    Prakash, Shashi; Kumar, Nitish; Kumar, Subrata

    2016-09-01

    CO2 laser microchanneling has emerged as a potential technique for the fabrication of microfluidic devices on PMMA (Poly-methyl-meth-acrylate). PMMA directly vaporizes when subjected to high intensity focused CO2 laser beam. This process results in clean cut and acceptable surface finish on microchannel walls. Overall, CO2 laser microchanneling process is cost effective and easy to implement. While fabricating microchannels on PMMA using a CO2 laser, the maximum depth of the fabricated microchannel is the key feature. There are few analytical models available to predict the maximum depth of the microchannels and cut channel profile on PMMA substrate using a CO2 laser. These models depend upon the values of thermophysical properties of PMMA and laser beam parameters. There are a number of variants of transparent PMMA available in the market with different values of thermophysical properties. Therefore, for applying such analytical models, the values of these thermophysical properties are required to be known exactly. Although, the values of laser beam parameters are readily available, extensive experiments are required to be conducted to determine the value of thermophysical properties of PMMA. The unavailability of exact values of these property parameters restrict the proper control over the microchannel dimension for given power and scanning speed of the laser beam. In order to have dimensional control over the maximum depth of fabricated microchannels, it is necessary to have an idea of uncertainty associated with the predicted microchannel depth. In this research work, the uncertainty associated with the maximum depth dimension has been determined using Monte Carlo method (MCM). The propagation of uncertainty with different power and scanning speed has been predicted. The relative impact of each thermophysical property has been determined using sensitivity analysis.

  16. The Decomposition Analysis of CO2 Emission and Economic Growth in Pakistan India and China

    Directory of Open Access Journals (Sweden)

    Muhammad Irfan Javaid Attari

    2011-12-01

    Full Text Available The conflict between economic growth and keeping greenhouse gases (GHG at controllable levels is one of the ultimate challenges of this century. The aim of Kyoto Protocol is to keep the level of carbon dioxide (CO2 below a certain threshold level. The purpose of this paper is to study the effect of CO2 emission on economic growth by conducting the regional analysis of PIC nations i.e. Pakistan, India and China. The study also provides the detail information regarding the atmospheric emission by applying decomposition analysis. It is suggested that environmental policies need more attention in the region by keeping the differences aside. So, the emission trading is considered to be the new concept. The approach should be introduced to tackle down the global warming in the region. Now it is time to respond because the low Carbon Economy is the reality.

  17. Impact of CO2 and pH on the distribution and stable carbon isotopic composition of microbial biomarker lipids

    NARCIS (Netherlands)

    Schoon, P.L.

    2013-01-01

    In addition to the more acknowledged consequences of climate change, such as global warming, the current human-induced increase of CO2 into the atmosphere is also responsible for a change in the chemical composition of seawater. Since 1750, the initiation of the industrial revolution, approximately

  18. Impact of CO2 and pH on the distribution and stable carbon isotopic composition of microbial biomarker lipids

    NARCIS (Netherlands)

    Schoon, P.L.

    2013-01-01

    In addition to the more acknowledged consequences of climate change, such as global warming, the current human-induced increase of CO2 into the atmosphere is also responsible for a change in the chemical composition of seawater. Since 1750, the initiation of the industrial revolution, approximately

  19. Analysis of Required Supporting Systems for the Supercritical CO(2) Power Conversion System

    Science.gov (United States)

    2007-09-01

    Environmental Protection Agency EPDM Ethylene-Propylene Diene Monomer EPMA Electron Probe Micro-Analysis ETGBR Existing Technology Gas Breeder Reactor FID...second stabilization period before starting the CO2 transfer to see if the initial density would stabilize closer to the values provided by NIST...closed valve at all. Valve sizing methods can be found in Ouderkirk, 2002. Neoprene, nylon, ethylene-propylene diene monomer ( EPDM ), and

  20. A Geochemical Approach for Monitoring a CO2 Pilot Site: Rousse, France. A Major gases, CO2-Carbon Isotopes and Noble Gases Combined Approach Une méthode géochimique pour la surveillance d’un site pilote de stockage de CO2 : Rousse, France. Approche combinant les gaz majeurs, l’isotopie du carbone du CO2 et les gaz rares

    Directory of Open Access Journals (Sweden)

    Garcia B.

    2012-02-01

    Full Text Available This paper presents the geochemical characterization of various gas end-members involved in a depleted gas field CO2 storage pilot (Rousse, France. In this pilot, CO2 is produced by oxycombustion from natural gas transformed into fuel gas at the Lacq plant, and transported in a pipeline 30 km away to the depleted gas reservoir of Rousse. Gases produced at Rousse before CO2 injection, the Lacq fuel gas and the CO2 resulting from the oxy-fuel combustion were sampled, together with gases from a –45 m monitoring well and from soils in the vicinity of the Rousse structure. For all samples, the bulk gas composition, the carbon isotopic compositions and the abundance and isotopic signatures of the noble gases were determined. The bulk gas compositions of the Rousse natural gas are comparable to the Lacq fuel gas with methane as the main compound with residual C2-C5 and CO2. Soil gases are typical mixtures of air with biogenic CO2 (up to 9-10%, while the monitoring well gases display typical air compositions with no excess CO2 The Rousse gas and the Lacq fuel gas have δ13CCH4 values of –41.0‰ and –43.0‰ respectively. The injected CO2 out of the oxycombustion chamber has a δ13CCO2 of –40.0‰, whereas δ13CCO2 value for soils samples is comprised between –15 and –25‰. The Rousse natural gas and the Lacq fuel gas are both characterized by a high He enrichment, and depletion in Ne, Ar and Kr compared to the air values. The oxyfuel combustion process provides a CO2 with the He enrichment of the Lacq fuel gas, and a Ne, Ar and Kr composition reflecting that of the oxygen produced at the Air Separation Unit (ASU. Indeed, Ne is depleted relatively to the air, while Kr is enriched up to tenfold, which results from the cryogenic separation of the air noble gases within the ASU. Soil samples noble gas compositions are equivalent to that of the air. In the light of these results, the compositions of the various end-members involved in this CO2

  1. Monitoring the bio-stimulation of hydrocarbon-contaminated soils by measurements of soil electrical properties, and CO2 content and its 13C/12C isotopic signature

    Science.gov (United States)

    Noel, C.; Gourry, J.; Ignatiadis, I.; Colombano, S.; Dictor, M.; Guimbaud, C.; Chartier, M.; Dumestre, A.; Dehez, S.; Naudet, V.

    2013-12-01

    Hydrocarbon contaminated soils represent an environmental issue as it impacts on ecosystems and aquifers. Where significant subsurface heterogeneity exists, conventional intrusive investigations and groundwater sampling can be insufficient to obtain a robust monitoring of hydrocarbon contaminants, as the information they provide is restricted to vertical profiles at discrete locations, with no information between sampling points. In order to obtain wider information in space volume on subsurface modifications, complementary methods can be used like geophysics. Among geophysical methods, geoelectrical techniques such as electrical resistivity (ER) and induced polarization (IP) seem the more promising, especially to study the effects of biodegradation processes. Laboratory and field geoelectrical experiments to characterize soils contaminated by oil products have shown that mature hydrocarbon-contaminated soils are characterized by enhanced electrical conductivity although hydrocarbons are electrically resistive. This high bulk conductivity is due to bacterial impacts on geological media, resulting in changes in the chemical and physical properties and thus, to the geophysical properties of the ground. Moreover, microbial activity induced CO2 production and isotopic deviation of carbon. Indeed, produced CO2 will reflect the pollutant isotopic signature. Thus, the ratio δ13C(CO2) will come closer to δ13C(hydrocarbon). BIOPHY, project supported by the French National Research Agency (ANR), proposes to use electrical methods and gas analyses to develop an operational and non-destructive method for monitoring in situ biodegradation of hydrocarbons in order to optimize soil treatment. Demonstration field is located in the South of Paris (France), where liquid fuels (gasoline and diesel) leaked from some tanks in 1997. In order to stimulate biodegradation, a trench has been dug to supply oxygen to the water table and thus stimulate aerobic metabolic bioprocesses. ER and

  2. On-site isotopic analysis of dissolved inorganic carbon using an isotope ratio infrared spectrometer

    Science.gov (United States)

    Stoltmann, Tim; Mandic, Magda; Stöbener, Nils; Wapelhorst, Eric; Aepfler, Rebecca; Hinrichs, Kai-Uwe; Taubner, Heidi; Jost, Hj; Elvert, Marcus

    2016-04-01

    An Isotope Ratio Infrared Spectrometer (IRIS) has been adapted to perform measurements of δ13C of dissolved inorganic carbon (DIC) in marine pore waters. The resulting prototype allowed highly automated analysis of δ13C isotopic ratios and CO2 concentration. We achieved a throughput of up to 70 samples per day with DIC contents as low as 1.7 μmol C. We achieved an internal precision of 0.066 ‰ and an external precision of 0.16 ‰, which is comparable to values given for Isotope Ratio Mass Spectrometers (IRMS). The prototype instrument is field deployable, suitable for shipboard analysis of deep sea core pore waters. However, the validation of the prototype was centered around a field campaign in Eckernförde Bay, NW- Baltic Sea. As a proof of concept, a shallow site within an area of submarine groundwater discharge (SGD) and a site outside this area was investigated. We present profiles of δ13C of DIC over 50 cm exhibiting well understood methane turnover processes (anaerobic oxidation of methane). At the lowest point below the seafloor, microbial reduction of CO2 to CH4 dominates. 12CO2 is reduced preferentially over 13CO2, leading to more positive δ13C values in the remaining DIC pool; in layers closer to the surface, the oxidation of CH4 to CO2 becomes more prominent. Since the CH4 pool is enriched in 12C a shift to more negative δ13C can be observed in the DIC pool. In the upper 15 cm, the pore water DIC mixes with the sea water DIC, increasing δ13C again. Finally, we will present recent developments to further improve performance and future plans for deployments on research cruises.

  3. Carbon-isotopic analysis of dissolved acetate.

    Science.gov (United States)

    Gelwicks, J T; Hayes, J M

    1990-01-01

    Heating of dried, acetate-containing solids together with oxalic acid dihydrate conveniently releases acetic acid for purification by gas chromatography. For determination of the carbon-isotopic composition of total acetate, the acetate-containing zone of the chromatographic effluent can be routed directly to a combustion furnace coupled to a vacuum system allowing recovery, purification, and packaging of CO2 for mass-spectrometric analysis. For analysis of methyl carbon, acetic acid can be cryogenically trapped from the chromatographic effluent, then transferred to a tube containing excess NaOH. The tube is evacuated, sealed, and heated to 500 degrees C to produce methane by pyrolysis of sodium acetate. Subsequent combustion of the methane allows determination of the 13C content at the methyl position in the parent acetate. With typical blanks, the standard deviation of single analyses is less than 0.4% for acetate samples larger than 5 micromoles. A full treatment of uncertainties is outlined.

  4. A multiyear, global gridded fossil fuel CO2 emission data product: Evaluation and analysis of results

    Science.gov (United States)

    Asefi-Najafabady, S.; Rayner, P. J.; Gurney, K. R.; McRobert, A.; Song, Y.; Coltin, K.; Huang, J.; Elvidge, C.; Baugh, K.

    2014-09-01

    High-resolution, global quantification of fossil fuel CO2 emissions is emerging as a critical need in carbon cycle science and climate policy. We build upon a previously developed fossil fuel data assimilation system (FFDAS) for estimating global high-resolution fossil fuel CO2 emissions. We have improved the underlying observationally based data sources, expanded the approach through treatment of separate emitting sectors including a new pointwise database of global power plants, and extended the results to cover a 1997 to 2010 time series at a spatial resolution of 0.1°. Long-term trend analysis of the resulting global emissions shows subnational spatial structure in large active economies such as the United States, China, and India. These three countries, in particular, show different long-term trends and exploration of the trends in nighttime lights, and population reveal a decoupling of population and emissions at the subnational level. Analysis of shorter-term variations reveals the impact of the 2008-2009 global financial crisis with widespread negative emission anomalies across the U.S. and Europe. We have used a center of mass (CM) calculation as a compact metric to express the time evolution of spatial patterns in fossil fuel CO2 emissions. The global emission CM has moved toward the east and somewhat south between 1997 and 2010, driven by the increase in emissions in China and South Asia over this time period. Analysis at the level of individual countries reveals per capita CO2 emission migration in both Russia and India. The per capita emission CM holds potential as a way to succinctly analyze subnational shifts in carbon intensity over time. Uncertainties are generally lower than the previous version of FFDAS due mainly to an improved nightlight data set.

  5. DETECTION AND ANALYSIS OF WELD POOL SHAPE FOR CO2 SHORT CIRCUITING ARC WELDING

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A general industrial CCD(ICCD) camera is redesigned to detect the weld pool without arc at the period of short circuiting,so that the interference of arc and spatter during CO2 short circuiting arc welding is eliminated. Through the analysis of weld pool image, both size parameters (such as weld pool area A, weld pool length L1, L2 and weld pool breadth b) and contour parameters (bi which describe the curves of weld pool boundany) ,which could indicate the shape features of weld pool, had been defined to express weld pool information quantitatively. The investigation of the relationships between weld pool shape parameters and welding process parameters may be beneficial to the quality control of CO2 welding.

  6. Optical Image Analysis Applied to Pore Network Quantification of Sandstones Under Experimental CO2 Injection

    Science.gov (United States)

    Berrezueta, E.; González, L.; Ordóñez, B.; Luquot, L.; Quintana, L.; Gallastegui, G.; Martínez, R.; Olaya, P.; Breitner, D.

    2015-12-01

    This research aims to propose a protocol for pore network quantification in sandstones applying the Optical Image Analysis (OIA) procedure, which guarantees the measurement reproducibility and its reliability. Two geological formations of sandstone, located in Spain and potentially suitable for CO2 sequestration, were selected for this study: a) the Cretaceous Utrillas unit, at the base of the Cenozoic Duero Basin and b) a Triassic unit at the base of the Cenozoic Guadalquivir Basin. Sandstone samples were studied before and after the CO2 experimental injection using Optical and scanning electronic microscopy (SEM), while the quantification of petrographic changes was done with OIA. The first phase of the rersearch consisted on a detailed mineralogical and petrographic study of the sandstones (before and after CO2-injection), for which we observed thin sections. Later, the methodological and experimental processes of the investigation were focused on i) adjustment and calibration of OIA tools; ii) data acquisition protocol based on image capture with different polarization conditions (synchronized movement of polarizers), using 7 images of the same mineral scene (6 in crossed polarizer and 1 in parallel polarizer); and iii) automated identification and segmentation of pore in 2D mineral images, generating applications by executable macros. Finally, once the procedure protocols had been, the compiled data was interpreted through an automated approach and the qualitative petrography was carried out. The quantification of changes in the pore network through OIA (porosity increase ≈ 2.5%) has allowed corroborate the descriptions obtained by SEM and microscopic techniques, which consisted in an increase in the porosity when CO2 treatment occurs. Automated-image identification and quantification of minerals, pores and textures together with petrographic analysis can be applied to improve pore system characterization in sedimentary rocks. This research offers numerical

  7. Carbon Isotopic Studies of Assimilated and Ecosystem Respired CO2 in a Southeastern Pine Forest. Final Report and Conference Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Conte, Maureen H

    2008-04-10

    Carbon dioxide is the major “greenhouse” gas responsible for global warming. Southeastern pine forests appear to be among the largest terrestrial sinks of carbon dioxide in the US. This collaborative study specifically addressed the isotopic signatures of the large fluxes of carbon taken up by photosynthesis and given off by respiration in this ecosystem. By measuring these isotopic signatures at the ecosystem level, we have provided data that will help to more accurately quantify the magnitude of carbon fluxes on the regional scale and how these fluxes vary in response to climatic parameters such as rainfall and air temperature. The focus of the MBL subcontract was to evaluate how processes operating at the physiological and ecosystem scales affects the resultant isotopic signature of plant waxes that are emitted as aerosols into the convective boundary layer. These wax aerosols provide a large-spatial scale integrative signal of isotopic discrimination of atmospheric carbon dioxide by terrestrial photosynthesis (Conte and Weber 2002). The ecosystem studies have greatly expanded of knowledge of wax biosynthetic controls on their isootpic signature The wax aerosol data products produced under this grant are directly applicable as input for global carbon modeling studies that use variations in the concentration and carbon isotopic composition of atmospheric carbon dioxide to quantify the magnitude and spatial and temporal patterns of carbon uptake on the global scale.

  8. Uncertainty analysis of CO2 flux components in subtropical evergreen coniferous plantation

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    We present an uncertainty analysis of ecological process parameters and CO2 flux components (Reco, NEE and gross ecosystem exchange (GEE)) derived from 3 years’ continuous eddy covariance meas-urements of CO2 fluxes at subtropical evergreen coniferous plantation, Qianyanzhou of ChinaFlux. Daily-differencing approach was used to analyze the random error of CO2 fluxes measurements and bootstrapping method was used to quantify the uncertainties of three CO2 flux components. In addition, we evaluated different models and optimization methods in influencing estimation of key parameters and CO2 flux components. The results show that: (1) Random flux error more closely follows a dou-ble-exponential (Laplace), rather than a normal (Gaussian) distribution. (2) Different optimization meth-ods result in different estimates of model parameters. Uncertainties of parameters estimated by the maximum likelihood estimation (MLE) are lower than those derived from ordinary least square method (OLS). (3) The differences between simulated Reco, NEE and GEE derived from MLE and those derived from OLS are 12.18% (176 g C·m-2·a-1), 34.33% (79 g C·m-2·a-1) and 5.4% (92 g C·m-2·a-1). However, for a given parameter optimization method, a temperature-dependent model (T_model) and the models derived from a temperature and water-dependent model (TW_model) are 1.31% (17.8 g C·m-2·a-1), 2.1% (5.7 g C·m-2·a-1), and 0.26% (4.3 g C·m-2·a-1), respectively, which suggested that the optimization methods are more important than the ecological models in influencing uncertainty in estimated carbon fluxes. (4) The relative uncertainty of CO2 flux derived from OLS is higher than that from MLE, and the uncertainty is related to timescale, that is, the larger the timescale, the smaller the uncertainty. The relative uncertainties of Reco, NEE and GEE are 4%-8%, 7%-22% and 2%-4% respectively at annual timescale.

  9. Performance analysis of CO(2) emissions and energy efficiency of metal industries in China.

    Science.gov (United States)

    Shao, Chaofeng; Guan, Yang; Wan, Zheng; Chu, Chunli; Ju, Meiting

    2014-02-15

    Nonferrous metal industries play an important role in China's national economy and are some of the country's largest energy consumers. To better understand the nature of CO(2) emissions from these industries and to further move towards low-carbon development in this industry sector, this study investigates the CO(2) emissions of 12 nonferrous metal industries from 2003 to 2010 based on their life-cycle assessments. It then classifies these industries into four "emission-efficiency" types through cluster analysis. The results show that (1) the industrial economy and energy consumption of China's nonferrous metal industries have grown rapidly, although their recent energy consumption rate shows a declining trend. (2) The copper, aluminum, zinc, lead, and magnesium industries, classified as high-emission industries, are the main contributors of CO(2) emissions. The results have implications for policy decisions that aim to enhance energy efficiency, particularly for promoting the transformation of low-efficiency industries to high-efficiency ones. The study also highlights the important role of policy development in technological innovations, optimization, and upgrades, the reduction of coal proportion in energy consumption, and the advancement of new energy sources.

  10. Thermodynamic Comparison Analysis on CO 2 Transcritical Reverse Cycles with IHX or Expander

    Institute of Scientific and Technical Information of China (English)

    GUAN Haiqing; MA Yitai; YANG Junlan; LI Minxia

    2005-01-01

    To improve the coefficient of performance (COP) of CO 2 transcritical reverse cycle and determine the most efficient cycle, comparison analysis on single- and two-stage CO 2 transcritical cycles with internal heat exchanger (IHX) or expander is presented adopting the principle of thermodynamics. Results indicate that the COP of four cycles,namely single-stage compression with IHX (SI), single-stage compression with expander (SE), two-stage compression with IHX (TI) and two-stage compression with expander (TE), can be ranged as TE>SE>TI>SI. It presents that adopting an expander to recover expansion power is the primary method to improve the COP of CO 2 transcritical reverse cycle if the efficiency of the expander is up to a certain value. Under supposed operating condition, where the outlet temperature of gas cooler is 35 ℃ and the evaporating temperature is 5 ℃, the COP of TE cycle is about 42% higher than that of SI cycle when the expander efficiency is 0.6 and the degree of superheat of IHX is 15 ℃. Therefore TE cycle is the most recommendatory one and it is better to adopt TE in those high-cooling capacity systems because its technology cost will be higher.

  11. Spatial analysis on China's regional air pollutants and CO2 emissions: emission pattern and regional disparity

    Science.gov (United States)

    Dong, Liang; Liang, Hanwei

    2014-08-01

    China has suffered from serious air pollution and CO2 emission. Challenges of emission reduction policy not only come from technology advancement, but also generate from the fact that, China has pronounced disparity between regions, in geographical and socioeconomic. How to deal with regional disparity is important to achieve the reduction target effectively and efficiently. This research conducts a spatial analysis on the emission patterns of three air pollutants named SO2, NOx and PM2.5, and CO2, in China's 30 provinces, applied with spatial auto-correlation and multi regression modeling. We further analyze the regional disparity and inequity issues with the approach of Lorenz curve and Gini coefficient. Results highlight that: there is evident cluster effect for the regional air pollutants and CO2 emissions. While emission amount increases from western regions to eastern regions, the emission per GDP is in inverse trend. The Lorenz curve shows an even larger unequal distribution of GDP/emissions than GDP/capita in 30 regions. Certain middle and western regions suffers from a higher emission with lower GDP, which reveal the critical issue of emission leakage. Future policy making to address such regional disparity is critical so as to promote the emission control policy under the “equity and efficiency” principle.

  12. Carbon financial markets: A time-frequency analysis of CO2 prices

    Science.gov (United States)

    Sousa, Rita; Aguiar-Conraria, Luís; Soares, Maria Joana

    2014-11-01

    We characterize the interrelation of CO2 prices with energy prices (electricity, gas and coal), and with economic activity. Previous studies have relied on time-domain techniques, such as Vector Auto-Regressions. In this study, we use multivariate wavelet analysis, which operates in the time-frequency domain. Wavelet analysis provides convenient tools to distinguish relations at particular frequencies and at particular time horizons. Our empirical approach has the potential to identify relations getting stronger and then disappearing over specific time intervals and frequencies. We are able to examine the coherency of these variables and lead-lag relations at different frequencies for the time periods in focus.

  13. A comprehensive carbon dioxide analysis system for estimating CO2 emissions

    Science.gov (United States)

    Denning, A.; Parazoo, N.; Lokupitiya, R. S.; Baker, D. F.

    2010-12-01

    Greenhouse gas emissions due to combustion of fossil fuel can be estimated from observations of variations in atmospheric trace gases in time and space. Quantitative interpretation of these variations requires accounting for stronger changes due to other processes such as ecosystem metabolism, biomass burning, and air-sea gas exchange that operate on global scales. We have developed and tested an analysis system for assimilation of CO2 variations measured by a combination of sampling, in-situ, and remotely-sensed observations. The system combines existing models of CO2 exchanges due to hourly photosynthesis and respiration, daily air-sea gas exchange, biomass burning, fossil fuel emissions, and atmospheric transport. This comprehensive system allows direct comparison to the observed record of both in-situ and remotely sensed atmospheric CO2 at hourly timescales. By design, we decompose surface fluxes of CO2 into the atmosphere into “fast processes” that are well-understood and modeled using mechanistic algorithms, and more slowly-varying fluxes due to land use change, incorrect specification of decomposing carbon pools, and other persistent biases in the forward component models. These slowly varying components are then estimated from atmospheric obervations by the Maximum Likelihood Ensembe Filter, a data assimilation framework. The system is operated on a 0.5° x 0.67° grid, providing global mesoscale coverage, and has good skill at replicating diurnal, synoptic, and seasonal variations over vegetated land surfaces. It is driven by meteorological output from the NASA Goddard EOS Data Assimilation System. Surface weather from the system drives calculations of terrestrial ecosystem metabolism (radiation, precipitation, humidity, temperature) and air-sea gas exchange (wind), with other input data coming from satellite data products.

  14. Interactive effects of elevated CO2 and nitrogen deposition on fatty acid molecular and isotope composition of above- and belowground tree biomass and forest soil fractions.

    Science.gov (United States)

    Griepentrog, Marco; Eglinton, Timothy I; Hagedorn, Frank; Schmidt, Michael W I; Wiesenberg, Guido L B

    2015-01-01

    Atmospheric carbon dioxide (CO2) and reactive nitrogen (N) concentrations have been increasing due to human activities and impact the global carbon (C) cycle by affecting plant photosynthesis and decomposition processes in soil. Large amounts of C are stored in plants and soils, but the mechanisms behind the stabilization of plant- and microbial-derived organic matter (OM) in soils are still under debate and it is not clear how N deposition affects soil OM dynamics. Here, we studied the effects of 4 years of elevated (13C-depleted) CO2 and N deposition in forest ecosystems established in open-top chambers on composition and turnover of fatty acids (FAs) in plants and soils. FAs served as biomarkers for plant- and microbial-derived OM in soil density fractions. We analyzed above- and belowground plant biomass of beech and spruce trees as well as soil density fractions for the total organic C and FA molecular and isotope (δ13C) composition. FAs did not accumulate relative to total organic C in fine mineral fractions, showing that FAs are not effectively stabilized by association with soil minerals. The δ13C values of FAs in plant biomass increased under high N deposition. However, the N effect was only apparent under elevated CO2 suggesting a N limitation of the system. In soil fractions, only isotope compositions of short-chain FAs (C16+18) were affected. Fractions of 'new' (experimental-derived) FAs were calculated using isotope depletion in elevated CO2 plots and decreased from free light to fine mineral fractions. 'New' FAs were higher in short-chain compared to long-chain FAs (C20-30), indicating a faster turnover of short-chain compared to long-chain FAs. Increased N deposition did not significantly affect the quantity of 'new' FAs in soil fractions, but showed a tendency of increased amounts of 'old' (pre-experimental) C suggesting that decomposition of 'old' C is retarded by high N inputs.

  15. Dissolved organic carbon, CO2, and CH4 concentrations and their stable isotope ratios in thermokarst lakes on the Qinghai-Tibetan Plateau

    Directory of Open Access Journals (Sweden)

    Cuicui Mu

    2016-01-01

    Full Text Available Thermokarst lakes are widely distributed on the Qinghai-Tibetan Plateau (QTP, which accounts for 8% of the global permafrost area. These lakes probably promote organic matter biodegradation and thus accelerate the emission of carbon-based greenhouse gases. However, little is known about greenhouse gas concentrations and their stable isotopes characteristics of these lakes. In this study, we measured the concentrations of dissolved organic carbon (DOC, dissolved CO2 and CH4, as well as the distribution of δ13CCO2, δ13CCH4, and δ13COM (organic matter of lake sediments in thermokarst lakes on the QTP. Results showed that the OM of the lake sediments was highly decomposed. The concentrations of DOC, CO2 and CH4 in the lake water on the QTP were 1.2–49.6 mg L–1, 3.6–45.0 μmol L–1 and 0.28–3.0 μmol L–1, respectively. The highest CO2 and CH4 concentrations were recorded in July while the lowest values in September, which suggested that temperature had an effect on greenhouse gas production, although this pattern may also relate to thermal stratification of the water column. The results implied that thermokast lakes should be paid more attention to regarding carbon cycle and greenhouse gas emissions on the QTP.

  16. Isotopic (18O) signature of CO2-H2O vapor exchange in the vadose air of Nerja cave (Malaga, Spain)

    Science.gov (United States)

    Vadillo, Iñaki; Ojeda, Lucía; Benavente, José; Liñán, Cristina; del Rosal, Yolanda; Carrasco, Francisco

    2017-04-01

    In caves, carbon dioxide contents and its δ13C signature have been widely studied to provide information about the ventilation regime and the source of carbon dioxide. However, less has been researched about δ18O signature in vadose air. We analysed cave-air samples for the CO2 concentration and oxygen isotopic composition from a monthly sampling campaigns for two years within different halls in Nerja cave. In general terms, ventilation controls the variation of CO2 content seasonally, showing two distinct modes with the highest values in summer. The δ18O values range from -8.74 to +0.47 ‰ being maximum in January and minimum in September, coinciding with the lowest and highest humidity values within the cave respectively. We found that a gas exchange between δ18O-CO2 and δ18O-H2O vapor is carried out and pattern is repeated every season, showing the importance that water has in karst environment.

  17. Diurnal and seasonal variation in the carbon isotope composition of leaf dark-respired CO(2) in velvet mesquite (Prosopis velutina).

    Science.gov (United States)

    Sun, Wei; Resco, Víctor; Williams, David G

    2009-10-01

    We evaluated diurnal and seasonal patterns of carbon isotope composition of leaf dark-respired CO(2) (delta(13)C(l)) in the C(3) perennial shrub velvet mesquite (Prosopis velutina) across flood plain and upland savanna ecosystems in the south-western USA. delta(13)C(l) of darkened leaves increased to maximum values late during daytime periods and declined gradually over night-time periods to minimum values at pre-dawn. The magnitude of the diurnal shift in delta(13)C(l) was strongly influenced by seasonal and habitat-related differences in soil water availability and leaf surface vapour pressure deficit. delta(13)C(l) and the cumulative flux-weighted delta(13)C value of photosynthates were positively correlated, suggesting that progressive (13)C enrichment of the CO(2) evolved by darkened leaves during the daytime mainly resulted from short-term changes in photosynthetic (13)C discrimination and associated shifts in the delta(13)C signature of primary respiratory substrates. The (13)C enrichment of dark-respired CO(2) relative to photosynthates across habitats and seasons was 4 to 6 per thousand at the end of the daytime period (1800 h), but progressively declined to 0 per thousand by pre-dawn (0300 h). The origin of night-time and daytime variations in delta(13)C(l) is discussed in terms of the carbon source(s) feeding respiration and the drought-induced changes in carbon metabolism.

  18. Application of Pressure Pulse Test Analysis in CO2 Leakage Detection and Monitoring

    Science.gov (United States)

    Shakiba, M.; Hosseini, S. A.

    2015-12-01

    Over the past decade, numerous research and industrial projects have been devoted to investigate the feasibility and efficiency of carbon dioxide capture, storage, and utilization. Besides the studies over the characteristics of candidate formations for CO2 injection, much attention has been paid to answer the environmental concerns regarding the CO2 leak to overlying formations. To first detect and then track a possible CO2 leak, different techniques have been proposed in the literature; however, most of them examine only a small portion of the formation and have a low resolution for early leak detection. To further increase the extent of the investigation zone and to monitor a large section of the formation in more detail, multi-well testing techniques have received a significant attention. Pressure pulse testing is a multi-well test technique in which a pressure signal generated by periods of injection and shut-in from a pulser well is propagated inside the formation, and the corresponding response is recorded at the observer wells. The recorded pressure response is then analyzed to measure the rock and fluid properties and to monitor the possible changes over the time. In this research study, we have applied frequency methods as well as superposition principle to interpret the pressure pulse test data and monitor the changes in transmissibility and storativity of the formation between the well pairs. We have used synthetic reservoir models and numerical reservoir simulations to produce the pressure pulse test data. The analysis of the simulation results indicated that even a small amount of CO2 leak in the investigation zone can have a measurable effect on the calculated storativity and transmissibility factors. This can be of a great importance when an early leak detection is of interest. Moreover, when multiple wells are available in the formation, the distribution of the calculated parameters can visualize the extent of CO2 leak, which has a great

  19. Intraspecific variation in juvenile tree growth under elevated CO2 alone and with O3: a meta-analysis.

    Science.gov (United States)

    Resco de Dios, Víctor; Mereed, Tessema E; Ferrio, Juan Pedro; Tissue, David T; Voltas, Jordi

    2016-06-01

    Atmospheric carbon dioxide (CO2) concentrations are expected to increase throughout this century, potentially fostering tree growth. A wealth of studies have examined the variation in CO2 responses across tree species, but the extent of intraspecific variation in response to elevated CO2 (eCO2) has, so far, been examined in individual studies and syntheses of published work are currently lacking. We conducted a meta-analysis on the effects of eCO2 on tree growth (height, stem biomass and stem volume) and photosynthesis across genotypes to examine whether there is genetic variation in growth responses to eCO2 and to understand their dependence on photosynthesis. We additionally examined the interaction between the responses to eCO2 and ozone (O3), another global change agent. Most of the published studies so far have been conducted in juveniles and in Populus spp., although the patterns observed were not species dependent. All but one study reported significant genetic variation in stem biomass, and the magnitude of intraspecific variation in response to eCO2 was similar in magnitude to previous analyses on interspecific variation. Growth at eCO2 was predictable from growth at ambient CO2 (R(2) = 0.60), and relative rankings of genotype performance were preserved across CO2 levels, indicating no significant interaction between genotypic and environmental effects. The growth response to eCO2 was not correlated with the response of photosynthesis (P > 0.1), and while we observed 57.7% average increases in leaf photosynthesis, stem biomass and volume increased by 36 and 38.5%, respectively, and height only increased by 9.5%, suggesting a predominant role for carbon allocation in ultimately driving the response to eCO2 Finally, best-performing genotypes under eCO2 also responded better under eCO2 and elevated O3 Further research needs include widening the study of intraspecific variation beyond the genus Populus and examining the interaction between eCO2 and

  20. Research on Flow Characteristics of Supercritical CO2 Axial Compressor Blades by CFD Analysis

    Science.gov (United States)

    Takagi, Kazuhisa; Muto, Yasushi; Ishizuka, Takao; Kikura, Hiroshige; Aritomi, Masanori

    A supercritical CO2 gas turbine of 20MPa is suitable to couple with the Na-cooled fast reactor since Na - CO2 reaction is mild at the outlet temperature of 800K, the cycle thermal efficiency is relatively high and the size of CO2 gas turbine is very compact. In this gas turbine cycle, a compressor operates near the critical point. The property of CO2 and then the behavior of compressible flow near the critical point changes very sharply. So far, such a behavior is not examined sufficiently. Then, it is important to clarify compressible flow near the critical point. In this paper, an aerodynamic design of the axial supercritical CO2 compressor for this system has been carried out based on the existing aerodynamic design method of Cohen1). The cycle design point was selected to achieve the maximum cycle thermal efficiency of 43.8%. For this point, the compressor design conditions were determined. They are a mass flow rate of 2035kg/s, an inlet temperature of 308K, an inlet static pressure of 8.26MPa, an outlet static pressure of 20.6MPa and a rotational speed of 3600rpm. The mean radius was constant through axial direction. The design point was determined so as to keep the diffusion factor and blade stress within the allowable limits. Number of stages and an expected adiabatic efficiency was 14 and 87%, respectively. CFD analyses by FLUENT have been done for this compressor blade. The blade model consists of one set of a guide vane, a rotor blade and a stator blade. The analyses were conducted under the assumption both of the real gas properties and also of the modified ideal gas properties. Using the real gas properties, analysis was conducted for the 14th blade, whose condition is remote from the critical point and the possibility of divergence is very small. Then, the analyses were conducted for the blade whose conditions are nearer to the critical point. Gradually, divergence of calculation was encountered. Convergence was relatively easy for the modified ideal

  1. Fabrication quality analysis of a fiber optic refractive index sensor created by CO2 laser machining.

    Science.gov (United States)

    Chen, Chien-Hsing; Yeh, Bo-Kuan; Tang, Jaw-Luen; Wu, Wei-Te

    2013-03-26

    This study investigates the CO2 laser-stripped partial cladding of silica-based optic fibers with a core diameter of 400 μm, which enables them to sense the refractive index of the surrounding environment. However, inappropriate treatments during the machining process can generate a number of defects in the optic fiber sensors. Therefore, the quality of optic fiber sensors fabricated using CO2 laser machining must be analyzed. The results show that analysis of the fiber core size after machining can provide preliminary defect detection, and qualitative analysis of the optical transmission defects can be used to identify imperfections that are difficult to observe through size analysis. To more precisely and quantitatively detect fabrication defects, we included a tensile test and numerical aperture measurements in this study. After a series of quality inspections, we proposed improvements to the existing CO2 laser machining parameters, namely, a vertical scanning pathway, 4 W of power, and a feed rate of 9.45 cm/s. Using these improved parameters, we created optical fiber sensors with a core diameter of approximately 400 μm, no obvious optical transmission defects, a numerical aperture of 0.52 ± 0.019, a 0.886 Weibull modulus, and a 1.186 Weibull-shaped parameter. Finally, we used the optical fiber sensor fabricated using the improved parameters to measure the refractive indices of various solutions. The results show that a refractive-index resolution of 1.8 × 10(-4) RIU (linear fitting R2 = 0.954) was achieved for sucrose solutions with refractive indices ranging between 1.333 and 1.383. We also adopted the particle plasmon resonance sensing scheme using the fabricated optical fibers. The results provided additional information, specifically, a superior sensor resolution of 5.73 × 10(-5) RIU, and greater linearity at R2 = 0.999.

  2. Ground test results and analysis advancements for the AFRL airborne CO2 DIAL system

    Science.gov (United States)

    Senft, Daniel C.; Fox, Marsha J.; Hamilton, Carla M.; Richter, Dale A.; Higdon, N. S.; Kelly, Brian T.; Babnick, Robert D.; Pierrottet, Diego F.

    1999-10-01

    The Air Force Research Laboratory (AFRL) Active Remote Sensing Branch has developed the Laser Airborne Remote Sensing (LARS) system for chemical detection using the differential absorption lidar technique. The system is based on a high-power CO2 laser which can use either the standard 12C16O2 or the 13C16O2 carbon dioxide isotopes as the lasing medium, and has output energies of up to 5 J on the stronger laser transitions. The lidar system is mounted on a flight-qualified optical breadboard designed for installation into the AFRL Argus C- 135E optical testbed aircraft. The Phase I ground tests were conducted at Kirtland AFB in 1997, prior to the LARS flight tests performed in September 1997 at Kirtland AFB and the Idaho National Engineering and Environmental Laboratory. The Phase II ground tests were conducted in 1998 to determine the optimum performance of the LARS systems, after the incorporation of modifications and improvements suggested by the flight test results. This paper will present some of the chemical detection and radiometric results obtained during the Phase II ground tests. Following the presentation of the direct detection results, a summary of current work on a heterodyne DIAL system is given.

  3. 钢铁生产CO2过程排放分析%Analysis of CO2 emissions of iron and steel making process

    Institute of Scientific and Technical Information of China (English)

    卢鑫; 白皓; 赵立华; 李宁; 李洪福

    2012-01-01

    钢铁生产成为大气中温室气体CO2的一大来源,准确测算钢铁生产CO2过程排放量是评估企业或行业减排的保障.建立基于CO2排放模块的CO2排放模型,选定国内典型钢铁生产企业进行分析,发现炼铁工序的CO2排放占总流程的60%左右,同时进一步分析了整体CO2排放强度与吨钢能耗的关系及工序CO2排放强度的分布.%The iron and steel making process has become one of the main sources of greenhouse gas CO2 in atmosphere, and the accurate calculation of CO2 emission in iron and steel making process will be the foundation to evaluate the emission reduction of specific enterprise and industry. With the CO2 emission model based on the CO2 emission module and the data from the selective typical iron and steel making plants in China, it was found that the CO2 emission of iron making process account for about 60% of total emission. Further, the relationship between total CO2 emission intensity and energy consumption intensity and the distribution of different process CO2 emission were analyzed.

  4. IGCC系统减排CO2的性能比较和分析%PERFORMANCE COMPARISON AND ANALYSIS OF IGCC WITH CO2 EMISSION REDUCTION

    Institute of Scientific and Technical Information of China (English)

    范江; 刘姝玮; 马素霞

    2012-01-01

    Gas producing ratio and energy consumption rate were computed respectively in the IGCC system, the IGCC system with pre-combustion CO2 capturing and that with oxy-combustion CO2 recycling. It was showed from the computed results that when coal and the gasification were in the same condition, the steam and gas turbine's work declined and the IGCC system thermal efficiency reduced by 5. 851%, which was due to the capturing of CO2 gas. When CO2 reduction rate was 86. 55% , the thermal efficiency was 42% and conducive to the operating of IGCC efficiently and cleanly. If adopting the CO2 recycling combustion technology, the system thermal efficiency was lower than that of the pre-combustion CO2 capturing system, but in which zero CO2 emission could be achieved.%分别对IGCC系统、IGCC燃烧前捕捉CO2系统以及CO2循环利用的纯氧燃烧系统的产气率和能耗进行了计算.结果表明,当煤种和气化条件不变时,燃烧前捕捉CO2会使IGCC系统的燃气轮机和蒸汽轮机做功量减少,热效率降低5.851%.当减排86.55%的CO2时,系统热效率为42%,有利于IGCC清洁高效运行.若采用CO2循环的纯氧燃烧技术,其系统热效率比未循环CO2的燃烧前捕捉系统低,但可以实现CO2的零排放.

  5. Reconstructing CO2 concentrations in basaltic melt inclusions from Cascade cinder cones using Raman analysis of vapor bubbles

    Science.gov (United States)

    Aster, E. M.; Wallace, P. J.; Moore, L.; Gazel, E.; Bodnar, R. J.

    2014-12-01

    Because melt inclusions (MIs) trap melt prior to eruptive degassing, they are useful probes of melt volatile concentrations. However, during post-entrapment cooling and crystallization, the melt in the inclusion contracts more than the mineral host, causing depressurization and nucleation of a vapor bubble. This causes pressure-soluble volatiles, particularly CO2, to exsolve from the melt into the bubble. To explore the extent of CO2 loss, CO2 densities in bubbles were estimated using data from Raman analysis of olivine-hosted melt inclusions from two cinder cones in the southern Cascade Arc (Basalt of Round Valley Butte [BRVB]; Basalt of Old Railroad Grade [BORG]). In BRVB, bubble vol. % (bubble vol./MI vol.) and measured CO2 densities ranged from 0.9 - 6.7 vol. % and 0.05- 0.24 g/cm3, respectively. In BORG, bubble vol. % and CO2 densities ranged from 1.4 - 9.2 vol. % and 0.07 - 0.29 g/cm3, respectively. To eliminate MI containing bubbles that were co-entrapped with the melt, we used a model from Riker (2005) to predict bubble vol. % as a function of the difference between eruption and formation temperatures. This suggested that bubbles larger than ~3.3 vol. % should be eliminated from CO2 reconstructions. Using average values of MI H2O and CO2 measured by FTIR, we added CO2 from the bubbles back into the MIs to obtain estimates of dissolved CO2 at the time of trapping. Analyzed concentrations were 933 ppm CO2 and 2.8 wt. % H2O for BORG (2.7 kbar, or ~9 km depth), with a reconstructed CO2 concentration of 1860 ± 612 (2s) ppm. Analyzed concentrations for BRVB were 426 ppm CO2 and 1.6 wt. % H2O (1.1 kbar, or ~3.7 km depth), with a reconstructed CO2 concentration of 2320 ± 1688 (2s) ppm. Using the reconstructed CO2 concentrations, VolatileCalc estimates place both BORG and BRVB MI entrapment at 4.3 kbar, or ~14 km depth. Thus, adding the CO2 in bubbles back to the CO2 in the glass of MIs is essential for determining accurate depths of magma crystallization.

  6. CO2 Radiocarbon Analysis to Quantify Organic Contaminant Degradation, MNA, and Engineered Remediation Approaches

    Science.gov (United States)

    2014-12-18

    environmental cleanup in the United States. One must understand the interplay between contaminants and natural compounds in complex biogeochemical ...carbon through natural biogeochemical cycles. Only recently has commercially available accelerator mass spectrometry (AMS) allowed routine 14CO2...Soil gas CO2 was assayed for radiocarbon content and CO2 concentration (Fig. 3). Background wells ( circled area) had a CO2 age from ~15 to 25 pMC. This

  7. A projected turning point in China's CO2 emissions - an Environmental Kuznets Curve analysis

    OpenAIRE

    Xu, Bo; Wennersten, Ronald; Brandt, Nils; Sun, Qie

    2012-01-01

    This paper examines the possible existence fan Environmental Kuznets Curve (EKC) relationship between China's carbon dioxide (CO2) emissions per capita (CO2/capita) and GDP per capita (GDP/capita) during the period 1980-2008. The timing of the turning point in China's CO2/capita can be further estimated if an EKC relationship exists. In regression results, a natural logarithm-quadratic relationship was found between CO2/capita and GDP/capita, which supports the EKC hypothesis. However, China'...

  8. Analysis of CO2 Separation by Selexol Based on Aspen Plus%基于Aspen Plus对Selexol分离CO2流程的分析

    Institute of Scientific and Technical Information of China (English)

    邱朋华; 李丹丹; 徐宝龙; 呼姚; 杜昌帅; 吴少华

    2014-01-01

    整体煤气化联合循环发电系统可采取燃烧前捕集CO2的方法,处理的合成气量少,能耗低,且能够实现 CO2的近零排放,在 CO2脱除方面具有很大的优势。文中基于Aspen Plus 对 CO2/H2S 联合脱除和分别脱除流程建立了模型,对2流程的能耗、CO2及H2S的脱除效率以及Selexol溶液的再生性能进行了分析。得出:在出口 CO2纯度相同的情况下,CO2/H2S联合脱除流程的能耗仅占CO2/H2S分别脱除的21%左右,CO2脱除效率高于分别脱除流程,2流程Selexol溶液的再生性能相差不大,且H2S脱除效率也可达到95%以上,因此CO2/H2S联合脱除流程更经济。%Integrated gasification combined cycle (IGCC)power generation system can adopt pre-combustion CO2 capture methods, handling with less syngas and have low energy consumption, which can achieve near-zero emissions of CO2, resulting in great advantages in terms of CO2 removal. Based on Aspen Plus, combined removal of CO2/H2S (CRCH) and separate removal of CO2/H2S (SRCH) were modeled . Energy consumption, capture efficiency of CO2 and H2S, as well as the regeneration performance of Selexol were analyzed by the two models. The results indicate that:while keeping the same CO2 purity in outlet stream, the energy consumption of CRCH accounts for only 21% of SRCH; the CO2 capture efficiency is higher than that of SRCH, the regeneration performance of Selexol is almost the same for the two processes, and the capture efficiency of H2S in the two processes can be higher than 95%. All those prove that CRCH is more economic than SRCH.

  9. [On the analysis of CO2-exchange in bryophyllum : II. Inhibition of starch loss during the night in an atmosphere free from CO2].

    Science.gov (United States)

    Kluge, M

    1969-06-01

    Starch consumption during the dark period in detached phyllodia of Bryophyllum tubiflorum is inhibited, when the phyllodia are held in an atmosphere free from carbon dioxide during the night. This is true also in other succulent plants with Crassulacean acid metabolism=CAM (examined were Bryophyllum calycinum and Sedum morganianum). This effect seems to indicate that the role of starch in CAM is production of CO2 acceptors rather than production of carbon dioxide by respiration. If the CO2 acceptors are not used, starch consumption comes to an end.This hypothesis could also explain results of experiments in which phyllodia were held at different temperatures during the dark period, and net CO2 fixation, starch loss and malate gain were determined. At 10° CO2 uptake was at a maximum (the necessary supply of CO2 acceptors must have therefore been at a maximum, too). Under these conditions there was the greatest amount of starch consumption. At 23° C, CO2 uptake was clearly lowered, and this was also true for starch consumption. At 35° C net CO2 uptake was balanced by net CO2, output (no CO2 acceptors were needed in CO2 dark fixation). At this temperature no starch loss could be measured.

  10. Testing the root-priming of soil organic matter decomposition using the isotopic signature of fossil fuel CO2

    Science.gov (United States)

    Bradley, Robert; Paterson, Eric; Chapman, Steve; Thornton, Barry; Sim, Allan

    2013-04-01

    Plant roots provide various forms of soil labile carbon (i.e., rhizodeposition), which stimulate the growth of heterotrophic bacteria in the rhizosphere. This, in turn, provides a food source for phagotrophic protozoa and other bacterivores, whose carbon:nutrient ratios are generally higher than those of their food source. In order to maintain their stoichiometric composition, bacterivores release their extra nutrients into the rhizosphere, where they may be absorbed by plant roots. Thus, rhizodeposition should reduce carbon limitation, but increase nutrient demand, of the soil microbial biomass. We hypothesized that this shift towards nutrient deficiency would stimulate the production of microbial enzymes that depolymerise soil organic matter into microbial available forms. In other words, roots should stimulate the decomposition of soil organic matter. We report on experiment where we tested such a "root-priming" effect using 3 contrasting plant species (Achillea millefolium, Lolium perenne, Trifolium repens). An agricultural soil, with a delta-13C value of approximately -14 ‰ , was transferred into 30 pots and planted with seeds of each species. A ring was inserted in the middle of each pot, and no seeds were planted within the ring. Plants were grown in a growth chamber designed to deliver 13C-depleted air. The resulting plant biomass had a delta-13C value of approximately -52 ‰ . On 7 occasions during the growth trial, pots were sampled for the flux and delta-13C value of soil CO2. Using similar data from control pots without plants, we compared the expected vs. observed contributions of CO2 from roots and soil organic matter. Results from this study revealed a negative root-priming effect for all three species. We discuss the experimental conditions that could have led to this observation, as well as the novelty and potential of our experimental protocol.

  11. Assessing the effects of nitrogen deposition and climate on carbon isotope discrimination and intrinsic water-use efficiency of angiosperm and conifer trees under rising CO2 conditions.

    Science.gov (United States)

    Leonardi, Stefano; Gentilesca, Tiziana; Guerrieri, Rossella; Ripullone, Francesco; Magnani, Federico; Mencuccini, Maurizio; Noije, Twan V; Borghetti, Marco

    2012-09-01

    The objective of this study is to globally assess the effects of atmospheric nitrogen deposition and climate, associated with rising levels of atmospheric CO2 , on the variability of carbon isotope discrimination (Δ(13) C), and intrinsic water-use efficiency (iWUE) of angiosperm and conifer tree species. Eighty-nine long-term isotope tree-ring chronologies, representing 23 conifer and 13 angiosperm species for 53 sites worldwide, were extracted from the literature, and used to obtain long-term time series of Δ(13) C and iWUE. Δ(13) C and iWUE were related to the increasing concentration of atmospheric CO2 over the industrial period (1850-2000) and to the variation of simulated atmospheric nitrogen deposition and climatic variables over the period 1950-2000. We applied generalized additive models and linear mixed-effects models to predict the effects of climatic variables and nitrogen deposition on Δ(13) C and iWUE. Results showed a declining Δ(13) C trend in the angiosperm and conifer species over the industrial period and a 16.1% increase of iWUE between 1850 and 2000, with no evidence that the increased rate was reduced at higher ambient CO2 values. The temporal variation in Δ(13) C supported the hypothesis of an active plant mechanism that maintains a constant ratio between intercellular and ambient CO2 concentrations. We defined linear mixed-effects models that were effective to describe the variation of Δ(13) C and iWUE as a function of a set of environmental predictors, alternatively including annual rate (Nrate ) and long-term cumulative (Ncum ) nitrogen deposition. No single climatic or atmospheric variable had a clearly predominant effect, however, Δ(13) C and iWUE showed complex dependent interactions between different covariates. A significant association of Nrate with iWUE and Δ(13) C was observed in conifers and in the angiosperms, and Ncum was the only independent term with a significant positive association with iWUE, although a multi

  12. Exergetic analysis of the transcritical cycle of an bottle cooler operating with CO2

    Directory of Open Access Journals (Sweden)

    Igor Marcel Gomes Almeida

    2009-10-01

    Full Text Available The second law of thermodynamics deals with the quality of energy. More specifically, it is concerned with the degradation of energy during a process, the entropy generation, and the lost opportunities to do work; and it offers plenty of room for improvement. This paper aims to identify key factors that affect refrigeration system performance with CO2. Due to the impact of global warming of CFC´s and HFC's, the use of natural refrigerants has received worldwide attention. The natural refrigerant, carbon dioxide (CO2/R744 is promising for use in cooling systems, especially in the transcritical cycle. An exergetic analysis through the cycle of a bottle cooller (exposer adapted for commercial use with carbon dioxide was carried out so that the effectiveness of the system components can be estimated and classified, allowing direct efforts to improve performance of components to the transcritical cycle. The analysis revealed that the compressor and expansion valve are the largest sources of losses in the system, and therefore, efforts should focus on improving these components.

  13. CO2 insufflation versus air insufflation for endoscopic submucosal dissection: A meta-analysis of randomized controlled trials.

    Science.gov (United States)

    Li, Xuan; Dong, Hao; Zhang, Yifeng; Zhang, Guoxin

    2017-01-01

    Carbon dioxide (CO2) insufflation is increasingly used for endoscopic submucosal dissection (ESD) owing to the faster absorption of CO2 as compared to that of air. Studies comparing CO2 insufflation and air insufflation have reported conflicting results. This meta-analysis is aimed to assess the efficacy and safety of use of CO2 insufflation for ESD. Clinical trials of CO2 insufflation versus air insufflation for ESD were searched in PubMed, Embase, the Cochrane Library and Chinese Biomedical Literature Database. We performed a meta-analysis of all randomized controlled trials (RCTs). Eleven studies which compared the use of CO2 insufflation and air insufflation, with a combined study population of 1026 patients, were included in the meta-analysis (n = 506 for CO2 insufflation; n = 522 for air insufflation). Abdominal pain and VAS scores at 6h and 24h post-procedure in the CO2 insufflation group were significantly lower than those in the air insufflation group, but not at 1h and 3h after ESD. The percentage of patients who experienced pain 1h and 24h post-procedure was obviously decreased. Use of CO2 insufflation was associated with lower VAS scores for abdominal distention at 1h after ESD, but not at 24h after ESD. However, no significant differences were observed with respect to postoperative transcutaneous partial pressure carbon dioxide (PtcCO2), arterial blood carbon dioxide partial pressure (PaCO2), oxygen saturation (SpO2%), abdominal circumference, hospital stay, white blood cell (WBC) counts, C-Reactive protein (CRP) level, dosage of sedatives used, incidence of dysphagia and other complications. Use of CO2 insufflation for ESD was safe and effective with regard to abdominal discomfort, procedure time, and the residual gas volume. However, there appeared no significant differences with respect to other parameters namely, PtcCO2, PaCO2, SpO2%, abdominal circumference, hospital stay, sedation dosage, complications, WBC, CRP, and dysphagia.

  14. Central Russia agroecosystem monitoring with CO2 fluxes analysis by eddy covariance method

    Directory of Open Access Journals (Sweden)

    Joulia Meshalkina

    2015-07-01

    GPP patterns. Cumulative assimilation of CO2 at the end of the growing season was about 150 g C m−2 for both sites. So the difference in NEE was the consequence of essentially higher respiration rates in case of vetch and oats (about 350 g C m−2 comparing to barley (250 g C m−2 that needs additional research. The results have shown high daily and seasonal dynamic of CO2 emission too as a result of different and contrasted conditions: crop type, crop development stage, soil moisture and air temperature. Obtained unique for Russian agriculture data are useful for land-use practices environmental assessment, for soil organic carbon dynamics analysis and agroecological evaluation.

  15. Analysis of Zero CO2 Emission SOFC Hybrid Power System%CO2零排放的SOFC复合动力系统分析

    Institute of Scientific and Technical Information of China (English)

    张潇元; 段立强

    2011-01-01

    Based on the Aspen-plus soft, SOFC stack model is established. The SOFC hybrid power system without CO2 capture is designed. Then, the zero CO2 emission SOFC hybrid power system is proposed. The performances of these two systems are compared and analyzed. With the mode of pure oxygen combustion, the outlet gas of zero CO2 emission SOFC hybrid power system is composed of only CO2 and steam, so it is easy to get CO2 with higher concentration by means of condensation. Compared with the conventional power system with CO2 capture, the energy consumption of CO2 capture in the new system decreases a lot. This paper also analyzes the effects of the main parameters on the performance of the hybrid power system. Above research achievements will provide the useful guide for further study on zero CO2 emission SOFC hybrid power system.%基于Aspen-Plus软件建立了SOFC电池堆的模型,设计了不回收CO2的SOFC复合动力系统,针对系统特点,提出了CO2零排放的SOFC复合动力系统,对这两种系统的性能进行了详细的比较和分析.CO2零排放系统利用纯氧燃烧方式得到的燃烧产物只有CO2和水蒸气,通过冷凝得到高浓度的CO2.与带CO2脱除的常规电厂相比,极大地降低了回收CO2的能耗.通过对主要参数(燃料利用率、蒸汽/碳比、运行压力等)进行优化,详细分析了各主要参数对系统性能的影响.本文研究成果将为进一步研究高效的CO2零排放SOFC复合动力系统提供有益的参考.

  16. Technology Analysis of CO2 Capture and Storage in Firing Power Plant%火电厂CO2 CCS技术分析

    Institute of Scientific and Technical Information of China (English)

    胡月红

    2012-01-01

    After introducing the CO2 emission characteristics from firing power plant,this paper discussed two parts in both CO2 capture and storage,and put forward four main technological lines for CO2 capture in firing power plants.The paper also analyzed and compared the features and appliances of every capture measures,and pointed out some problems needed to be solved for using the existing capture methods to firing power plant in China.Finally it analyzed and summarized CO2 storage technology and comprehensive utilization.%介绍了火电厂CO2排放特点,将CO2减排技术分为捕集与封存两个部分进行讨论,提出了火电厂CO2捕集的4种主要技术路线;比较分析了几种主要捕集方法的技术特点和火力发电适用性,CO2应用于我国火电厂需解决的问题;综述了CO2的封存技术和综合利用。

  17. Paired carbon stable-isotope records for the Cenomanian Stage (100.5 -93.9 Ma): correlation tool and Late Cretaceous pCO2 record?

    Science.gov (United States)

    Jarvis, Ian; Gröcke, Darren; Laurin, Jiří; Selby, David; Roest-Ellis, Sascha; Miles, Andrew; Lignum, John; Gale, Andrew; Kennedy, Jim

    2016-04-01

    - and long-term trends. Potential causes of the similarities and differences are examined, and it is concluded that major deviations of the paired isotope trends offer insights into long-term atmospheric pCO2 variation. The osmium 187Os/188Os isotope stratigraphy of the MCEI and OAE2 intervals provides evidence of varying volcanic CO2 input, in-part driving climate change. Spectral analyses of the δ13Corg time series reveals a strong ~100 kyr short eccentricity signal throughout the Cenomanian, with well-expressed ~40 kyr obliquity and ~20 kyr precession cycles in some intervals. A 400 kyr long eccentricity cycle is recorded in sedimentation rate changes and amplitude modulation of the 100 kyr cycle. The relative spacing of events, and comparison with the latest orbital solution La2011, further suggest that MCE I and OAE2 coincided with nodes in the ~2.2-Myr eccentricity modulation.

  18. Kinetic analysis of an anion exchange absorbent for CO2 capture from ambient air.

    Science.gov (United States)

    Shi, Xiaoyang; Li, Qibin; Wang, Tao; Lackner, Klaus S

    2017-01-01

    This study reports a preparation method of a new moisture swing sorbent for CO2 capture from air. The new sorbent components include ion exchange resin (IER) and polyvinyl chloride (PVC) as a binder. The IER can absorb CO2 when surrounding is dry and release CO2 when surrounding is wet. The manuscript presents the studies of membrane structure, kinetic model of absorption process, performance of desorption process and the diffusivity of water molecules in the CO2 absorbent. It has been proved that the kinetic performance of CO2 absorption/desorption can be improved by using thin binder and hot water treatment. The fast kinetics of P-100-90C absorbent is due to the thin PVC binder, and high diffusion rate of H2O molecules in the sample. The impressive is this new CO2 absorbent has the fastest CO2 absorption rate among all absorbents which have been reported by other up-to-date literatures.

  19. Non-Linear Responses to Precipitation and Shrub Encroachment in Semi-Arid Grassland: Isotopes and CO2 Fluxes Reveal Soil Microsite Alteration as Explanation

    Science.gov (United States)

    Cable, J. M.; Sun, W.; Ogle, K.; Williams, D. G.; Potts, D. L.; Scott, R. L.; Huxman, T. E.

    2006-12-01

    Responses of net ecosystem production (NEP) to growing season rainfall amount is non-linear over a gradient of woody-plant encroachment in semi-arid riparian grassland. NEP is positively correlated with growing season precipitation amount in the grassland, but is negatively correlated with precipitation amount in a former C4 grassland now occupied by large mesquite (Prosopis) individuals. NEP at sites with intermediate stages of mesquite encroachment have a complex, threshold response to precipitation amount. Mesquite encroachment creates patchy soil microsites and spatial variation in rooting depth and activity. We hypothesized that variation in soil microsite properties (e.g., temperature, labile carbon) and root activity affect soil CO2 efflux in such a way that explains the non-linearity in response of NEP to precipitation. We measured soil CO2 efflux during the dry pre-monsoon (early summer) and wet monsoon (mid summer) periods on old floodplain terraces along the San Pedro River in southeastern Arizona. We made intensive spatial and temporal measurements of soil CO2 flux in four microsites associated with woody-plant encroachment: inter-canopy space and beneath the canopies of grasses, medium mesquite, and large mesquite. We also measured the δ13C of soil-respired CO2, which provided insight into the contribution of different sources (e.g., roots vs. microbes) to soil CO2 efflux. Soil respiration was highest beneath large mesquite near the canopy center, and lowest beneath medium mesquite and in inter-canopy spaces. The δ13C data revealed that soil respiration was dominated by a C4 signal during the pre-monsoon, but it switched to being dominated by the C3 mesquite signal during the wet monsoon period. Respiration was most sensitive to precipitation inputs beneath the large mesquite, where labile carbon in the form of mesquite litter is readily available. Conversely, soil respiration was least sensitive to precipitation in the open, inter- canopy space

  20. Evaluation Analysis of the CO2 Emission and Absorption Life Cycle for Precast Concrete in Korea

    Directory of Open Access Journals (Sweden)

    Taehyoung Kim

    2016-07-01

    Full Text Available To comply with recent international trends and initiatives, and in order to help achieve sustainable development, Korea has established a greenhouse gas (GHG emission reduction target of 37% (851 million tons of the business as usual (BAU rate by 2030. Regarding environmentally-oriented standards such as the IGCC (International Green Construction Code, there are also rising demands for the assessment on CO2 emissions during the life cycle in accordance with ISO (International Standardization Organization’s Standard 14040. At present, precast concrete (PC engineering-related studies primarily cover structural and construction aspects, including improvement of structural performance in the joint, introduction of pre-stressed concrete and development of half PC. In the manufacture of PC, steam curing is mostly used for the early-strength development of concrete. In steam curing, a large amount of CO2 is produced, causing an environmental problem. Therefore, this study proposes a method to assess CO2 emissions (including absorption throughout the PC life cycle by using a life cycle assessment (LCA method. Using the proposed assessment method, CO2 emissions during the life cycle of a precast concrete girder (PCG were assessed. In addition, CO2 absorption was assessed against a PCG using conventional carbonation and CO2 absorption-related models. As a result, the CO2 emissions throughout the life cycle of the PCG were 1365.6 (kg-CO2/1 PCG. The CO2 emissions during the production of raw materials among the CO2 emissions throughout the life cycle of the PCG were 1390 (kg-CO2/1 PCG, accounting for a high portion to total CO2 emissions (nearly 90%. In contrast, the transportation and manufacture stages were 1% and 10%, respectively, having little effect on total CO2 emissions. Among the use of the PCG, CO2 absorption was mostly decided by the CO2 diffusion coefficient and the amount of CO2 absorption by cement paste. The CO2 absorption by carbonation

  1. Diel variations in the carbon isotope composition of respired CO2 and associated carbon sources: a review of dynamics and mechanisms

    Directory of Open Access Journals (Sweden)

    C. Werner

    2011-09-01

    Full Text Available Recent advances have improved our methodological approaches and theoretical understanding of post-photosynthetic carbon isotope fractionation processes. Nevertheless we still lack a clear picture of the origin of short-term variability in δ13C of respired CO2 (δ13Cres and organic carbon fractions on a diel basis. Closing this knowledge gap is essential for the application of stable isotope approaches for partitioning ecosystem respiration, tracing carbon flow through plants and ecosystems and disentangling key physiological processes in carbon metabolism of plants. In this review we examine the short-term dynamics in δ13Cres and putative substrate pools at the plant, soil and ecosystem scales and discuss mechanisms, which might drive diel δ13Cres dynamics at each scale. Maximum reported variation in diel δ13Cres is 4.0, 5.4 and 14.8 ‰ in trunks, roots and leaves of different species and 12.5 and 8.1 ‰ at the soil and ecosystem scale in different biomes. Temporal variation in post-photosynthetic isotope fractionation related to changes in carbon allocation to different metabolic pathways is the most plausible mechanistic explanation for observed diel dynamics in δ13Cres. In addition, mixing of component fluxes with different temporal dynamics and isotopic compositions add to the δ13Cres variation on the soil and ecosystem level. Understanding short-term variations in δ13Cres is particularly important for ecosystem studies, since δ13Cres contains information on the fate of respiratory substrates, and may, therefore, provide a non-intrusive way to identify changes in carbon allocation patterns.

  2. CO, NOx and 13CO2 as tracers for fossil fuel CO2: results from a pilot study in Paris during winter 2010

    Science.gov (United States)

    Lopez, M.; Schmidt, M.; Delmotte, M.; Colomb, A.; Gros, V.; Janssen, C.; Lehman, S. J.; Mondelain, D.; Perrussel, O.; Ramonet, M.; Xueref-Remy, I.; Bousquet, P.

    2013-08-01

    Measurements of the mole fraction of the CO2 and its isotopes were performed in Paris during the MEGAPOLI winter campaign (January-February 2010). Radiocarbon (14CO2) measurements were used to identify the relative contributions of 77% CO2 from fossil fuel consumption (CO2ff from liquid and gas combustion) and 23% from biospheric CO2 (CO2 from the use of biofuels and from human and plant respiration: CO2bio). These percentages correspond to average mole fractions of 26.4 ppm and 8.2 ppm for CO2ff and CO2bio, respectively. The 13CO2 analysis indicated that gas and liquid fuel contributed 70% and 30%, respectively, of the CO2 emission from fossil fuel use. Continuous measurements of CO and NOx and the ratios CO/CO2ff and NOx/CO2ff derived from radiocarbon measurements during four days make it possible to estimate the fossil fuel CO2 contribution over the entire campaign. The ratios CO/CO2ff and NOx/CO2ff are functions of air mass origin and exhibited daily ranges of 7.9 to 14.5 ppb ppm-1 and 1.1 to 4.3 ppb ppm-1, respectively. These ratios are consistent with different emission inventories given the uncertainties of the different approaches. By using both tracers to derive the fossil fuel CO2, we observed similar diurnal cycles with two maxima during rush hour traffic.

  3. Isotopic analysis for degradation diagnosis of calcite matrix in mortar.

    Science.gov (United States)

    Dotsika, E; Psomiadis, D; Poutoukis, D; Raco, B; Gamaletsos, P

    2009-12-01

    Mortar that was used in building as well as in conservation and restoration works of wall paintings have been analysed isotopically (delta(13)C and delta(18)O) in order to evaluate the setting environments and secondary processes, to distinguish the structural components used and to determine the exact causes that incurred the degradation phenomena. The material undergoes weathering and decay on a large proportion of its surface and in depth, due to the infiltration of water through the structural blocks. Mineralogical analysis indicated signs of sulphation and dissolution/recrystallisation processes taking place on the material, whereas stable isotopes provided information relative to the origin of the CO(2) and water during calcite formation and degradation processes. Isotopic change of the initial delta(13)C and delta(18)O in carbonate matrix was caused by alteration of the primary source of CO(2) and H(2)O in mortar over time, particularly by recrystallisation of calcite with porewater, evaporated or re-condensed water, and CO(2) from various sources of atmospheric and biogenic origin. Human influence (surface treatment) and biological growth (e.g. fungus) are major exogenic processes which may alter delta(18)O and delta(13)C in lime mortar.

  4. Reinforced photocatalytic reduction of CO2 to CO by a ternary metal oxide NiCo2O4.

    Science.gov (United States)

    Wang, Zhaoyu; Jiang, Min; Qin, Jiani; Zhou, Han; Ding, Zhengxin

    2015-06-28

    The work reported herein was the facile preparation of uniform urchin-like NiCo2O4 microspheres, and their use as an efficient and stable cocatalyst for photocatalytic CO2 reduction catalysis. A combined solvothermal-calcination strategy was applied to synthesize the NiCo2O4 material that was systematically characterized by physical and chemical measurements (e.g. SEM, TEM, XRD, XPS, EDX, elemental mapping and N2 physisorption analysis). By cooperation with a visible light photosensitizer, the NiCo2O4 material effectively promoted the deoxygenative reduction of CO2 to CO by more than twenty times under mild reaction conditions. The carbon origin of CO evolution was validated by (13)CO2 isotope tracer experiments. Various reaction parameters were examined and optimized, and a possible reaction mechanism was proposed. Furthermore, the stability and reusability of NiCo2O4 cocatalysts were firmly confirmed.

  5. Decoupling economic growth from CO2 emissions: A decomposition analysis of China's household energy consumption

    Directory of Open Access Journals (Sweden)

    Xiao-Wei Ma

    2016-09-01

    Full Text Available This paper analyzes Chinese household CO2 emissions in 1994–2012 based on the Logarithmic Mean Divisia Index (LMDI structure decomposition model, and discusses the relationship between household CO2 emissions and economic growth based on a decoupling indicator. The results show that in 1994–2012, household CO2 emissions grew in general and displayed an accelerated growth trend during the early 21st century. Economic growth leading to an increase in energy consumption is the main driving factor of CO2 emission growth (an increase of 1.078 Gt CO2 with cumulative contribution rate of 55.92%, while the decline in energy intensity is the main cause of CO2 emission growth inhibition (0.723 Gt CO2 emission reduction with cumulative contribution rate of 38.27%. Meanwhile, household CO2 emissions are in a weak state of decoupling in general. The change in CO2 emissions caused by population and economic growth shows a weak decoupling and expansive decoupling state, respectively. The CO2 emission change caused by energy intensity is in a state of strong decoupling, and the change caused by energy consumption structure fluctuates between a weak and a strong decoupling state.

  6. A Review of CO2-Enhanced Oil Recovery with a Simulated Sensitivity Analysis

    Directory of Open Access Journals (Sweden)

    Mandadige Samintha Anne Perera

    2016-06-01

    Full Text Available This paper reports on a comprehensive study of the CO2-EOR (Enhanced oil recovery process, a detailed literature review and a numerical modelling study. According to past studies, CO2 injection can recover additional oil from reservoirs by reservoir pressure increment, oil swelling, the reduction of oil viscosity and density and the vaporization of oil hydrocarbons. Therefore, CO2-EOR can be used to enhance the two major oil recovery mechanisms in the field: miscible and immiscible oil recovery, which can be further increased by increasing the amount of CO2 injected, applying innovative flood design and well placement, improving the mobility ratio, extending miscibility, and controlling reservoir depth and temperature. A 3-D numerical model was developed using the CO2-Prophet simulator to examine the effective factors in the CO2-EOR process. According to that, in pure CO2 injection, oil production generally exhibits increasing trends with increasing CO2 injection rate and volume (in HCPV (Hydrocarbon pore volume and reservoir temperature. In the WAG (Water alternating gas process, oil production generally increases with increasing CO2 and water injection rates, the total amount of flood injected in HCPV and the distance between the injection wells, and reduces with WAG flood ratio and initial reservoir pressure. Compared to other factors, the water injection rate creates the minimum influence on oil production, and the CO2 injection rate, flood volume and distance between the flood wells have almost equally important influence on oil production.

  7. Analysis of optical and acoustic signals in CO_2 laser butt welding%CO_2激光拼焊的光与声信号分析

    Institute of Scientific and Technical Information of China (English)

    盂宣宣; 王春明; 胡席远

    2011-01-01

    The blueviolet radiation(400-440 nm),infrared radiation(1 200-1 700 nm) and audio sound(20-20 kHz) are used as signals detected by a multi-sensor real-time monitoring system in the process of CO2 laser butt welding.The signals can be collected and recorded online.The valuable information in the signals was found out by time-domain,frequency domain and time-frequency analysis.According to the signal features,it can be concluded that the high frequency part(higher than 7 000 Hz) of the optical and acoustic signals,especially the blueviolet optical radiation signal can reflect the stability of welding pool and keyhole well,and can be used to identify the weld seam defects caused by large gap joint.%采用自行研制的多传感器激光焊接实时监测系统,以CO2激光拼焊过程中的蓝紫光辐射(400~440 nm)、红外辐射(1 200~1 700 nm)以及可听声(20~20 kHz)等三种信号作为被检测参量,进行了信号的在线采集与记录,通过时域、频域以及时频分析,实现信号中有效信息的挖掘.结果表明,7 000 Hz以上的高频段光声信号成分,尤其是蓝紫光信号,较好地反映了熔池与小孔的稳定性,可以用于识别间隙过大造成的焊缝质量问题.

  8. Analysis of ΔO2/ΔCO2 ratios for the pollution events observed at Hateruma Island, Japan

    Directory of Open Access Journals (Sweden)

    S. Maksyutov

    2011-05-01

    Full Text Available In-situ observations of atmospheric CO2 and O2 concentrations at Hateruma Island (HAT, 24° N, 124° E often show synoptic scale pollution events when air masses are transported from East Asian source regions. We calculate the regression slopes (-ΔO2/ΔCO2 molar ratios of the correlation plots between O2 and CO2 for selected pollution events observed between October 2006 and December 2008. The observed -ΔO2/ΔCO2 ratios vary from 1.0 to 1.7. Categorizing the air mass origins for the pollution events by using back trajectory analysis, we find that there is a significant difference in the average -ΔO2/ΔCO2 ratios between events from China (1.14±0.12, n = 25 and Japan/Korea (1.37±0.15, n = 16. These values are comparable to the -O2:CO2 molar exchange ratios, which are estimated from the national fossil fuel inventories from CDIAC. Simulations using a particle dispersion model reveal that the pollution events at HAT are predominantly CO2 emissions from the combustion of fossil fuels in East Asian countries, which is consistent with the above observational results. Although the average value of the model-predicted -ΔO2/ΔCO2 ratios for Japan/Korea origin is underestimated in comparison with the observation, that for China origin agree well with the observation. The sensitivity experiment suggests that the -ΔO2/ΔCO2 ratio at HAT reflects about 90% of the change in the -O2:CO2 exchange ratio for the fossil carbon emissions from China.

  9. Analysis of ΔO2/ΔCO2 ratios for the pollution events observed at Hateruma Island, Japan

    Science.gov (United States)

    Minejima, C.; Kubo, M.; Tohjima, Y.; Yamagishi, H.; Koyama, Y.; Maksyutov, S.; Kita, K.; Mukai, H.

    2011-05-01

    In-situ observations of atmospheric CO2 and O2 concentrations at Hateruma Island (HAT, 24° N, 124° E) often show synoptic scale pollution events when air masses are transported from East Asian source regions. We calculate the regression slopes (-ΔO2/ΔCO2 molar ratios) of the correlation plots between O2 and CO2 for selected pollution events observed between October 2006 and December 2008. The observed -ΔO2/ΔCO2 ratios vary from 1.0 to 1.7. Categorizing the air mass origins for the pollution events by using back trajectory analysis, we find that there is a significant difference in the average -ΔO2/ΔCO2 ratios between events from China (1.14±0.12, n = 25) and Japan/Korea (1.37±0.15, n = 16). These values are comparable to the -O2:CO2 molar exchange ratios, which are estimated from the national fossil fuel inventories from CDIAC. Simulations using a particle dispersion model reveal that the pollution events at HAT are predominantly CO2 emissions from the combustion of fossil fuels in East Asian countries, which is consistent with the above observational results. Although the average value of the model-predicted -ΔO2/ΔCO2 ratios for Japan/Korea origin is underestimated in comparison with the observation, that for China origin agree well with the observation. The sensitivity experiment suggests that the -ΔO2/ΔCO2 ratio at HAT reflects about 90% of the change in the -O2:CO2 exchange ratio for the fossil carbon emissions from China.

  10. Empirically Analysis of the CO2 Emissions Embodied in Exports of China%Empirically Analysis of the CO2 Emissions Embodied in Exports of China

    Institute of Scientific and Technical Information of China (English)

    Zhu Qirong

    2011-01-01

    In this paper, using the input-output model, the author first calculated the CO2 emissions embodied in exports of China in 2002 and 2007. Then, the author empirically analyzed problems existing in the composition of exported products and analyzed its possible reasons. The research results of this paper are as follows: Since China's entry into WTO, the CO2 emissions embodied in exports of China have been increasing rapidly; the value of exported products of high-carbon emissions industries accounts for a relatively higher proportion to China's total exports value because China's carbon intensive products have a certain competitive advantage. Additionally, this paper has put forward relevant suggestions based on these results.

  11. Anions Analysis in Ground and Tap Waters by Sequential Chemical and CO2-Suppressed Ion Chromatography

    Directory of Open Access Journals (Sweden)

    Glen Andrew D. De Vera

    2011-06-01

    Full Text Available An ion chromatographic method using conductivity detection with sequential chemical and CO2 suppression was optimized for the simultaneous determination of fluoride, chloride, bromide, nitrate,phosphate and sulfate in ground and tap water. The separation was done using an anion exchange column with an eluent of 3.2 mM Na2CO3 and 3.2 mM NaHCO3 mixture. The method was linear in the concentration range of 5 to 300 μg/L with correlation coefficients greater than 0.99 for the six inorganic anions. The method was also shown to be applicable in trace anions analysis as given by the low method detection limits (MDL. The MDL was 1μg/L for both fluoride and chloride. Bromide, nitrate, phosphate and sulfate had MDLs of 7 μg/L, 10 μg/L, 9 μg/L and 2 μg/L, respectively. Good precision was obtained as shown in the relative standard deviation of 0.1 to 12% for peak area and 0.1 to 0.3% for retention time. The sensitivity of the method improved with the addition of CO2 suppressor to chemical suppression as shown in the lower background conductivity and detection limits. The recoveries of the anions spiked in water at 300 μg/L level ranged from 100 to 104%. The method was demonstrated to be sensitive, accurate and precise for trace analysis of the six anions and was applied in the anions analysis in ground and tap waters in Malolos, Bulacan. The water samples were found to contain high concentrations of chloride of up to 476 mg/L followed by sulfate (38 mg/L, bromide (1 mg/L, phosphate (0.4 mg/L, fluoride (0.2 mg/L and nitrate (0.1 mg/L.

  12. Linking carbon isotope signatures of nighttime leaf-respiratory and daytime assimilatory CO2 fluxes observed with laser spectrometry under field conditions

    Science.gov (United States)

    Gentsch, Lydia; Ogée, Jérôme; Wingate, Lisa; Sturm, Patrick; Siegwolf, Rolf; Werner, Roland A.; Buchmann, Nina; Knohl, Alexander

    2015-04-01

    The 13C/12C ratio (δ13C) of atmospheric CO2 is a valuable tool for constraining the impact of the terrestrial biosphere on atmospheric CO2 dynamics. Alterations of the 13C signal of terrestrial net CO2 fluxes are generally attributed to variations in photosynthetic 13C discrimination. Yet, over the past decade, evidence has emerged that plant metabolism and respiration modify the initial δ13C signature of recent photosynthetic assimilates. Such postphotosynthetic δ13C modifications were reported for all plant organs, but leaf respiratory metabolism may play a central role as it impacts carbon turnover in other plant tissues. Leaf-respired CO2 is frequently 13C enriched with respect to leaf organic matter. Mechanisms potentially explaining this enrichment include the differential use of carbon sources, metabolite fragmentation or the expression of kinetic isotope effects of respiratory enzymes. For global and ecosystem-scale applications of δ13C, it is now important to study, under field conditions, the variability of δ13C in leaf-respired CO2 (δ13CRES) and the deviation of the latter from δ13C of recent assimilates (δ13CAS). Here, we present 74 days of hourly δ13C measurements for daytime assimilatory and nighttime respiratory CO2 fluxes on leafy branches of three mature Fagus sylvatica trees in a temperate forest. Measurements were conducted with a laser spectrometer (QCLAS-ISO, Aerodyne Research Inc.) measuring CO2 isotopologue mixing ratios in ambient and sampling air from photosynthetic gas exchange chambers. We used daytime measurements of photosynthetic 13C discrimination for diurnally flux-weighted estimates of δ13CAS, and found that flux-weighted δ13CRES roughly tracked previous-day shifts in δ13CAS. Deviations between flux-weighted δ13CAS and δ13CRES were further robustly predicted by previous-day assimilation, with δ13CRES displaying 13C enrichment on low and 13C depletion on high assimilation days. On the hourly timescale, δ13CRES either

  13. Simplified Data Envelopment Analysis: What Country Won the Olympics, and How about our CO2 Emissions?

    Directory of Open Access Journals (Sweden)

    Alexander Vaninsky

    2013-07-01

    Full Text Available This paper introduces a simplified version of Data Envelopment Analysis - a conventional approach to evaluating the performance and ranking of competitive objects characterized by two groups of factors acting in opposite directions: inputs and outputs. Examples of DEA applications discussed in this paper include the London 2012 Olympic Games and the dynamics of the United States’ environmental performance. In the first example, we find a team winner and rank the teams; in the second, we analyze the dynamics of CO2 emissions adjusted to the gross domestic product, population, and energy consumption. Adding a virtual Perfect Object – one having the greatest outputs and smallest inputs - we greatly simplify the DEA computational procedure by eliminating the Linear Programming algorithm. Simplicity of computations makes the suggested approach attractive for educational purposes, in particular, for use in Quantitative Reasoning courses.

  14. Life cycle energy and CO2 analysis of microalgae-to-biodiesel: preliminary results and comparisons.

    Science.gov (United States)

    Khoo, H H; Sharratt, P N; Das, P; Balasubramanian, R K; Naraharisetti, P K; Shaik, S

    2011-05-01

    Despite claims that microalgal biofuels are environmentally friendlier alternatives to conventional fuels, debate surrounding its ecological benefits or drawbacks still exists. LCA is used to analyze various biofuel production technologies from 'cradle to gate'. Energy and CO(2) balances are carried out for a hypothetical integrated PBR-raceway microalgae-to-biodiesel production in Singapore. Based on a functional unit of 1 MJ biofuel, the total energy demands are 4.44 MJ with 13% from biomass production, 85% from lipid extraction, and 2% from biodiesel production. Sensitivity analysis was carried out for adjustments in energy requirements, percentage lipid contents, and lower/higher heating product value. An 'Optimistic Case' was projected with estimates of: 45% lipid content; reduced energy needs for lipid extraction (1.3 MJ per MJ biodiesel); and heating value of biodiesel (42 MJ/kg). The life cycle energy requirements dropped significantly by about 60%. The results are compared with other published case studies from other countries.

  15. Influencing Factors of Energy-Related CO2 Emissions in China: A Decomposition Analysis

    Directory of Open Access Journals (Sweden)

    Guokui Wang

    2015-10-01

    Full Text Available China is the largest CO2 emitter in the world and is still reliant on energy consumption for economic growth. Research has focused on effective approaches of reducing and mitigating CO2 emissions. This paper undertakes a decomposition study of energy-related CO2 emissions from the industrial and household sectors during the period 1996–2012, with the objectives of investigating trends of the changes in energy-related CO2 emissions, the driving forces of these changes, and approaches of mitigating CO2 emission. Results show the following: (1 the expansion of economic activity is the dominant stimulatory factor of the increase of CO2 emissions in China and that a sustained increase in CO2 emissions can be expected; (2 the decline in energy intensity and the adjustment of energy mix and industrial structure effectively mitigate CO2 emissions; and (3 the government should give more attention to enhancing the energy utility efficiency and reducing CO2 emissions in rural households.

  16. On Guangxi's CO_2 Abatement by Using Catastrophe Progression Method and Scenario Analysis Method%基于突变级数法与情景分析法的广西CO_2减排研究

    Institute of Scientific and Technical Information of China (English)

    蒙瑞海

    2012-01-01

    Based on related indices from the year 1978 to 2009,using catastrophe progression method,Guangxi's CO2 emissions are analyzed and evaluated.By using scenario analysis method,the impact of different scenarios on Guangxi's CO2 emissions is analyzed,and Guangxi's CO2 emissions of year 2015 are forecasted under different scenarios,in order to make reasonable suggestions for Guangxi's CO2 abatement.%依据广西1978—2009年CO2排放的相关指标数据,采用突变级数法对广西1978—2009年CO2减排作出了相关分析评价.在此基础上,运用情景分析法预测不同情景下广西2015年CO2排放,分析不同情景选择对广西CO2排放的影响,以期为广西开展CO2减排提出合理化建议.

  17. Data fusion of CO2 retrieved from GOSAT and AIRS using regression analysis and fixed rank kriging

    Science.gov (United States)

    Zhou, Cong; Shi, Runhe; Gao, Wei

    2015-09-01

    This paper proposes an improved statistical method for fusing carbon dioxide (CO2) data retrieved from two major instruments, the Greenhouse gases Observing SATellite (GOSAT) and the Atmospheric Infrared Sounder (AIRS). These two datasets were fused to obtain CO2 concentrations near the surface, which is a region that is especially important for studies on carbon sources and sinks. Overall, the CO2 monthly average values from GOSAT are all lower than those from AIRS from 2010 to 2012. The datasets show the similar seasonal cycles of carbon dioxide and show an increasing trend with a determination coefficient of 0.45. A strong correlation was determined by adding the climatic factors as independent variables for regression analysis. The correlation coefficients between the CO2 values from AIRS and GOSAT significantly increased in response. The true CO2 data processes were then predicted using the fixed rank kriging method. This showed that the data-fusion CO2 product provides more reasonable information and that the corresponding mean squared prediction errors are smaller than those from the single GOSAT CO2 dataset.

  18. Driving Forces of CO2 Emissions in Emerging Countries: LMDI Decomposition Analysis on China and India’s Residential Sector

    Directory of Open Access Journals (Sweden)

    Yeongjun Yeo

    2015-12-01

    Full Text Available The main objective of this paper is to identify and analyze the key drivers behind changes of CO2 emissions in the residential sectors of the emerging economies, China and India. For the analysis, we investigate to what extent changes in residential emissions are due to changes in energy emissions coefficients, energy consumption structure, energy intensity, household income, and population size. We decompose the changes in residential CO2 emissions in China and India into these five contributing factors from 1990 to 2011 by applying the Logarithmic Mean Divisia Index (LMDI method. Our results show that the increase in per capita income level was the biggest contributor to the increase of residential CO2 emissions, while the energy intensity effect had the largest effect on CO2 emissions reduction in residential sectors in both countries. This implies that investments for energy savings, technological improvements, and energy efficiency policies were effective in mitigating CO2 emissions. Our results also depict that the change in CO2 emission coefficients for fuels which include both direct and indirect emission coefficients slowed down the increase of residential emissions. Finally, our results demonstrate that changes in the population and energy consumption structure drove the increase in CO2 emissions.

  19. Oxygen isotope systematics in the aragonite-CO2-H2O-NaCl system up to 0.7 mol/kg ionic strength at 25 °C

    Science.gov (United States)

    Kim, Sang-Tae; Gebbinck, Christa Klein; Mucci, Alfonso; Coplen, Tyler B.

    2014-01-01

    To investigate the oxygen isotope systematics in the aragonite-CO2-H2O-NaCl system, witherite (BaCO3) was precipitated quasi-instantaneously and quantitatively from Na-Cl-Ba-CO2 solutions of seawater-like ionic strength (I = 0.7 mol/kg) at two pH values (~7.9 and ~10.6) at 25 °C. The oxygen isotope composition of the witherite and the dissolved inorganic carbon speciation in the starting solution were used to estimate the oxygen isotope fractionations between HCO3¯ and H2O as well as between CO3 2 and H2O. Given the analytical error on the oxygen isotope composition of the witherite and uncertainties of the parent solution pH and speciation, oxygen isotope fractionation between NaHCO3° and HCO3¯, as well as between NaCO3¯ and CO3 2, is negligible under the experimental conditions investigated. The influence of dissolved NaCl concentration on the oxygen isotope fractionation in the aragonite-CO2-H2O-NaCl system also was investigated at 25 °C. Aragonite was precipitated from Na-Cl-Ca-Mg-(B)-CO2 solutions of seawater-like ionic strength using passive CO2 degassing or constant addition methods. Based upon our new experimental observations and published experimental data from lower ionic strength solutions by Kim et al. (2007b), the equilibrium aragonite-water oxygen isotope fractionation factor is independent of the ionic strength of the parent solution up to 0.7 mol/kg. Hence, our study also suggests that the aragonite precipitation mechanism is not affected by the presence of sodium and chloride ions in the parent solution over the range of concentrations investigated.

  20. Second Generation CO2 FEP Analysis: CASSIF - Carbon Storage Scenario Identification Framework

    NARCIS (Netherlands)

    Yavuz, F.; Tilburg, T. van; David, P.; Spruijt, M.; Wildenborg, T.

    2009-01-01

    Carbon dioxide Capture and Storage (CCS) is a promising contribution to reduce further increase of atmospheric CO2 emissions from fossil fuels. The CCS concept anticipates that large amounts of CO2 are going to be stored in the subsurface for the long term. Since CCS is a rather new technology, unce

  1. Comprehensive Exergy Analysis of Three IGCC Power Plant Configurations with CO2 Capture

    Directory of Open Access Journals (Sweden)

    Nicholas S. Siefert

    2016-08-01

    Full Text Available We have conducted comprehensive exergy analyses of three integrated gasification combined cycle with carbon capture and storage (IGCC-CCS power plant configurations: (1 a baseline model using Selexol™ for H2S/CO2 removal; (2 a modified version that adds a H2-selective membrane before the Selexol™ acid gas removal system; and (3 a modified baseline version that uses a CO2-selective membrane before the Selexol™ acid gas removal system. While holding the coal input flow rate and the CO2 captured flow rates constant, it was determined that the H2-selective membrane case had a higher net power output (584 MW compared to the baseline (564 MW and compared to the CO2-selective membrane case (550 MW. Interestingly, the CO2-selective membrane case destroyed the least amount of exergy within the power plant (967 MW, compared with the Baseline case (999 MW and the H2-membrane case (972 MW. The main problem with the CO2-selective membrane case was the large amount of H2 (48 MW worth of H2 chemical exergy remaining within the supercritical CO2 that exits the power plant. Regardless of the CO2 capture process used, the majority of the exergy destruction occurred in the gasifier (305 MW and gas turbine (~380 MW subsystems, suggesting that these two areas should be key areas of focus of future improvements.

  2. Analysis of process configurations for CO2 capture by precipitating amino acid solvents

    NARCIS (Netherlands)

    Sanchez Fernandez, E.; Heffernan, K.; Ham, L.V. van der; Linders, M.J.G.; Brilman, D.W.F.; Goetheer, E.L.V.; Vlugt, T.J.H.

    2014-01-01

    Precipitating amino acid solvents are an alternative to conventional amine scrubbing for CO2 capture from flue gas. Process operation with these solvents leads to the formation of precipitates during absorption that need to be re-dissolved prior to desorption of CO2. The process configuration is cru

  3. Radiocarbon analysis of stratospheric CO2 retrieved from AirCore sampling

    NARCIS (Netherlands)

    Paul, Dipayan; Chen, Huilin; Been, Henk A.; Kivi, Rigel; Meijer, Harro A. J.

    2016-01-01

    Radiocarbon (C-14) is an important atmospheric tracer and one of the many used in the understanding of the global carbon budget, which includes the greenhouse gases CO2 and CH4. Measurement of radiocarbon in atmospheric CO2 generally requires the collection of large air samples (a few liters) from

  4. Radiocarbon analysis of stratospheric CO2 retrieved from AirCore sampling

    NARCIS (Netherlands)

    Paul, Dipayan; Chen, Huilin; Been, Henk A.; Kivi, Rigel; Meijer, Harro A. J.

    2016-01-01

    Radiocarbon (C-14) is an important atmospheric tracer and one of the many used in the understanding of the global carbon budget, which includes the greenhouse gases CO2 and CH4. Measurement of radiocarbon in atmospheric CO2 generally requires the collection of large air samples (a few liters) from w

  5. CO2 Emisyonu ve Ekonomik Büyüme: Panel Veri Analizi(CO2 Emission and Economic Growth: A Panel Data Analysis

    Directory of Open Access Journals (Sweden)

    Ayşe ARI

    2011-01-01

    Full Text Available The aim of this paper is to test Environmental Kuznets Curve (EKC hypothesis by investigating the relationship between per capita income and carbon dioxide (CO2 emission. In accordance with this aim, The Mediterranian Countries have been analysed with the panel data method over the period 2000-2005. The empirical results displayed an N-shaped relationship between per capita GDP and CO2 emission. Thereby, it has seen that CO2 emission can also increase at the high levels of per capita income. Furthermore, the effects of the population density and energy consumption on the environmental pollution have also been searched in this study. The obtained empirical results indicated that the population density and energy consumption effect CO2 emission positively.

  6. Design of experiment analysis of CO2 dielectric barrier discharge conditions on CO production

    Science.gov (United States)

    Becker, Markus; Ponduri, Srinath; Engeln, Richard; van de Sanden, Richard; Loffhagen, Detlef

    2016-09-01

    Dielectric barrier discharges (DBD) are frequently used for the generation of CO from CO2 which is of particular interest for syngas production. It has been found by means of fluid modelling in that the CO2 conversion frequency in a CO2 DBD depends linearly on the specific energy input (SEI) while the energy efficiency of CO production is only weakly dependent on the SEI. Here, the same numerical model as in is applied to study systematically the influence of gas pressure, applied voltage amplitude and frequency on the CO2 conversion frequency and the energy efficiency of CO production based on a 2-level 3-factor full factorial experimental design. It is found that the operating conditions of the CO2 DBD for CO production can be chosen to either have an optimal throughput or a better energy efficiency. This work was partly supported by the German Research Foundation within the Collaborative Research Centre Transregio 24.

  7. Controlling factors analysis of pCO2 distribution in the Western Arctic Ocean in summertime

    Science.gov (United States)

    Song, Xuelian; Bai, Yan; Hao, Zengzhou; Zhun, Qiankun; Chen, Jianyu; Gong, Fang

    2015-10-01

    The uptake of carbon dioxide (CO2) by the Arctic Ocean has been changing because of the rapid sea-ice retreat with global warming. The Chukchi Sea is the only gateway of the warm and nutrient-rich Pacific Ocean water flowing into the North Pole, and the high productivity-water had great impact on the CO2 uptake by the Arctic Ocean. We used the in situ underway data of aquatic partial pressure of CO2 (pCO2), temperature and salinity, as well as the remote sensing data of sea ice concentration, chlorophyll concentration, sea surface temperature in August in 2008, 2011 and 2012 to analyze the major controlling factors of aquatic pCO2 in the Western Arctic Ocean. We analyzed the pCO2 variation under the effects of thermodynamic process (temperature), mixing of water mass (salinity), biological drawdown (chlorophyll), and sea ice concentration. The aquatic pCO2 was generally unsaturation relative to the atmospheric CO2 in most of the Western Arctic Ocean. According to different controlling mechanisms, the study area was divided into three parts: the area affected by the Pacific Ocean water (mainly in the Chukchi Sea), the area where sea ice mostly melted with weak biological production (the southern Canada Basin and the Western Beaufort Sea), and the area mostly covered by sea ice (the Northern Canada Basin). The aquatic pCO2 was low in the Chukchi Sea with the influence of the Pacific Ocean water. While, pCO2 in the area where sea ice melted was up to 360-380 μatm because of warming, CO2 invasion from the atmosphere, and a low biological production. For the Canada Basin, it was controlled by temperature change and sea ice cover. The remote sensing data in large spatial-temporal scale can help to understand the pCO2 variation and its response to global change; and it needs to develop satellite algorithm of pCO2 based on the quantification of controlling processes.

  8. Thermal Analysis of Compressible CO2 Flow for PFE TeSS Nozzle of Fire Detection System

    Science.gov (United States)

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

    2002-01-01

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

  9. Thermal Analysis of Compressible CO2 Flow for PFE TeSS Nozzle of Fire Detection System

    Science.gov (United States)

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

    2002-01-01

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

  10. Calcium Isotope Analysis by Mass Spectrometry

    Science.gov (United States)

    Boulyga, S.; Richter, S.

    2010-12-01

    The variations in the isotopic composition of calcium caused by fractionation in heterogeneous systems and by nuclear reactions can provide insight into numerous biological, geological, and cosmic processes, and therefore isotopic analysis finds a wide spectrum of applications in cosmo- and geochemistry, paleoclimatic, nutritional, and biomedical studies. The measurement of calcium isotopic abundances in natural samples has challenged the analysts for more than three decades. Practically all Ca isotopes suffer from significant isobaric interferences, whereas low-abundant isotopes can be particularly affected by neighboring major isotopes. The extent of natural variations of stable isotopes appears to be relatively limited, and highly precise techniques are required to resolve isotopic effects. Isotope fractionation during sample preparation and measurements and instrumental mass bias can significantly exceed small isotope abundance variations in samples, which have to be investigated. Not surprisingly, a TIMS procedure developed by Russell et al. (Russell et al., 1978. Geochim Cosmochim Acta 42: 1075-1090) for Ca isotope measurements was considered as revolutionary for isotopic measurements in general, and that approach is used nowadays (with small modifications) for practically all isotopic systems and with different mass spectrometric techniques. Nevertheless, despite several decades of calcium research and corresponding development of mass spectrometers, the available precision and accuracy is still not always sufficient to achieve the challenging goals. This presentation discusses figures of merits of presently used analytical methods and instrumentation, and attempts to critically assess their limitations. Additionally, the availability of Ca isotope reference materials will be discussed.

  11. Diurnal and Seasonal Variation in the Carbon Isotope Composition of Leaf- and Root- respired CO2 in C3 and C4 Species

    Science.gov (United States)

    Sun, W.; Resco, V.; Chen, S.; Williams, D. G.

    2008-12-01

    The carbon isotope signature of leaf (δ13Cl) and root (δ13Cr) dark- respired CO2 records and integrates short-term metabolic changes. Plants with C3 and C4 photosynthetic metabolism are expected to differ in diurnal and seasonal patterns in δ13Cl and δ13Cr because of differences in photorespiration, isotopic fractionation at metabolic branch points and allocation patterns. A thorough understanding of the environmental and metabolic controls on δ13Cl and δ13Cr is necessary to interpret the δ13C of ecosystem respired CO2 and partition the CO2 efflux into autotrophic and heterotrophic respiration sources. We measured δ13Cl in two C3 tree species (Prosopis velutina and Celtis reticulata), a C3 herb (Viguiera dentata) and a C4 grass (Sporobolus wrightii), and δ13Cr in P. velutina and S. wrightii in a semiarid savanna in southeastern Arizona, USA. δ13Cl during the dry pre-monsoon period was relatively enriched in 13C during daytime periods and became depleted in 13C at night relative to daytime values for all species with the exception of S. wrightii, the C4 grass. δ13Cl in S. wrightii was strongly influenced by seasonal differences in water availability with a larger diurnal amplitude in δ13Cl (8.2 +/- 0.6‰) during the wet monsoon period compared to that in the dry pre-monsoon period (4.4 +/- 0.4‰). The δ13C values of starch and lipid fractions remained constant over diurnal periods within the pre-monsoon and monsoon seasons. For C3 species, δ13Cl and δ13C of the cumulative, flux-weighted photosynthate pool estimated from gas exchange were strongly positively correlated, suggesting that progressive 13C-enrichment of leaf-respired CO2 during the daytime period resulted from changes in the δ13C signature of respiratory substrates associated with short-term changes in photosynthetic 13C discrimination. Rapid decreases in δ13Cl following the daytime period was likely caused by decreases in the ratio of PDH:acetyl-CoA oxidation rather than by a shift in

  12. CO 2池沸腾换热关联式理论分析%Theoretical Analysis on Correlation of CO2 Pool Boiling Heat Transfer

    Institute of Scientific and Technical Information of China (English)

    刘圣春; 刘江彬; 宁静红

    2013-01-01

    The common heat transfer correlations of pool boiling is summarized,and a correlation of CO2 heat transfer is at-tained after analyzing heat transfer performance.The deviation within 16% of CO2 fitting formula value compared to prediction values of theoretical pool boiling correlation of conventional refrigerants and experimental fitting correlation of CO2 is obtained, which shows that it is of universal.The effects on pool boiling heat transfer and the variation law are pointed out by analyzing the process of CO2 pool boiling heat transfer,and the common methods,using to enhance pool boiling heat transfer,are summarized in the paper.%总结了常见的池沸腾换热关联式。通过对池沸腾换热过程分析得出CO2在小热流密度和大热流密度范围下的一种分段的换热关联式。将新的拟合公式值和预测关联式值进行比较,得出CO2的拟合公式值与理论关联式及实验拟合关联式的预测值的偏差在±16%之内,具有一定的通用性。通过对CO2池沸腾换热过程的分析,得出池沸腾换热的影响因素及其变化规律,并总结了常用的强化池沸腾换热方法。

  13. Analysis of CO2 Fluxes: Inclusion of Wall Conductance (Gw on the Estimation of Rubisco Activity, Vcmax of Soybean Leaves

    Directory of Open Access Journals (Sweden)

    TANIA JUNE

    2011-03-01

    Full Text Available In global change research, where modelling of CO2 fluxes from plants is an important component in determining vegetation capacity to protect the climate, mechanistic-based modelling is needed when projection of future CO2 absorption dynamics need to be estimated more accurately. Rubisco is the world’s most abundant protein in plants and has the job of uniquely preparing CO2 for chemical reduction. Rubisco activity in the leaf, described by Vcmax, can be estimated from gas exchange measurements of the initial slope of the response of CO2 assimilation rate, A, to intercellular [CO2]. This technique of estimation is favourable because it can avoid the uncertainties and difficulties when Vcmax is obtained directly by extraction and biochemical assay in artificial media. Rate of assimilation of soybean plants grown at different temperature (20/15, 25/20, and 32/27 oC day/night temperature and [CO2] (350 and 700 mol mol-1, were measured using gas exchange. The effect of wall conductance (gw on the parameterization of assimilations rate was observed. The temperature dependence of Vcmax depends strongly on wall conductance, where the shape of the curve would change significantly if finite wall conductance were included in the analysis. The implication is that it changes the values and interpretation of the temperature response of assimilation rate.

  14. Economic Growth, Foreign Direct Investment and CO2 Emissions in China: A Panel Granger Causality Analysis

    Directory of Open Access Journals (Sweden)

    Hongfeng Peng

    2016-03-01

    Full Text Available Using a sample of province-level panel data, this paper investigates the Granger causality associations among economic growth (GDP, foreign direct investment (FDI and CO2 emissions in China. By applying the bootstrap Granger panel causality approach (Kónya, 2006, we consider both cross-sectional dependence and homogeneity of different regions in China. The empirical results support that the causality direction not only works in a single direction either from GDP to FDI (in Yunnan or from FDI to GDP (in Beijing, Neimenggu, Jilin, Shanxi and Gansu, but it also works in both directions (in Henan. Moreover, we document that GDP is Granger-causing CO2 emissions in Neimenggu, Hubei, Guangxi and Gansu while there is bidirectional causality between these two variables in Shanxi. In the end, we identify the unidirectional causality from FDI to CO2 emissions in Beijing, Henan, Guizhou and Shanxi, and the bidirectional causality between FDI and CO2 emissions in Neimenggu.

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

    Science.gov (United States)

    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 (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.

  16. Geochemical effects of CO2 injection on produced water chemistry at an enhanced oil recovery site in the Permian Basin of northwest Texas, USA: Preliminary geochemical and Li isotope results

    Science.gov (United States)

    Pfister, S.; Gardiner, J.; Phan, T. T.; Macpherson, G. L.; Diehl, J. R.; Lopano, C. L.; Stewart, B. W.; Capo, R. C.

    2014-12-01

    Injection of supercritical CO2 for enhanced oil recovery (EOR) presents an opportunity to evaluate the effects of CO2 on reservoir properties and formation waters during geologic carbon sequestration. Produced water from oil wells tapping a carbonate-hosted reservoir at an active EOR site in the Permian Basin of Texas both before and after injection were sampled to evaluate geochemical and isotopic changes associated with water-rock-CO2 interaction. Produced waters from the carbonate reservoir rock are Na-Cl brines with TDS levels of 16.5-34 g/L and detectable H2S. These brines are potentially diluted with shallow groundwater from earlier EOR water flooding. Initial lithium isotope data (δ7Li) from pre-injection produced water in the EOR field fall within the range of Gulf of Mexico Coastal sedimentary basin and Appalachian basin values (Macpherson et al., 2014, Geofluids, doi: 10.1111/gfl.12084). Pre-injection produced water 87Sr/86Sr ratios (0.70788-0.70795) are consistent with mid-late Permian seawater/carbonate. CO2 injection took place in October 2013, and four of the wells sampled in May 2014 showed CO2 breakthrough. Preliminary comparison of pre- and post-injection produced waters indicates no significant changes in the major inorganic constituents following breakthrough, other than a possible drop in K concentration. Trace element and isotope data from pre- and post-breakthrough wells are currently being evaluated and will be presented.

  17. Parametric analysis of a novel cryogenic CO2 capture system based on Stirling coolers.

    Science.gov (United States)

    Song, Chun Feng; Kitamura, Yutaka; Li, Shu Hong; Jiang, Wei Zhong

    2012-11-20

    CO(2) capture and storage (CCS) is an important alternative to control greenhouse gas (GHG) effects. In previous work, a novel desublimation CO(2) capture process has been exploited making use of three free piston Stirling coolers (namely, SC-1, SC-2, and SC-3, respectively). Based on the developed system, moisture and CO(2) in the flue gas can condense and desublimate in the prefreezing and main-freezing towers, respectively. Meanwhile, the storage column is chilled by SC-3 to preserve the frosted CO(2), and permanent gas (such as N(2)) passes through the system without phase change. The whole process can be implemented at atmospheric pressure and reduce the energy penalty (e.g., solvent regeneration and pressure drop) in other technologies. In this work, the influence of process parameters has been investigated in detail. The optimal conditions for the system are as follows: idle operating time is 240 min, flow rate is 5 L/min, vacuum degree of the interlayer is 2.2 × 10(3) Pa, and temperatures of SC-1, -2, and -3 are -30, -120, and -120 °C, respectively. Under these conditions, the energy consumption of the system is around 0.5 MJ(electrical)/kg CO(2) with above 90% CO(2) recovery.

  18. Stable Isotopic Characteristics of CO2 Emitted by Gasoline Vehicles%汽油车尾气排放CO2的稳定同位素特征

    Institute of Scientific and Technical Information of China (English)

    肖瑶; 胡敏; 李梦仁; 秦艳红; 彭剑飞; 张文彬; 郑竞; 杜卓菲; 邓磊

    2016-01-01

    温室气体CO2浓度增长引起的气候变化问题受到全球广泛关注.CO2的稳定碳同位素特征可为其源汇机制研究提供有力支持,但需要各类污染源排放的碳同位素特征值,尤其是局地或区域特征作为数据基础.CO2浓度的增长主要来自化石燃料燃烧,机动车排放是一个重要来源.研究应用基于激光的同位素比红外光谱仪(IRIS),对我国汽油车尾气排放CO2的稳定碳同位素组成(δ13C)进行了初步的研究,测定结果为(-28.0±0.5)‰.汽油车尾气排放CO2出现碳同位素分馏现象,其δ13C特征受冷热起动方式影响不大,但与汽油成分、发动机燃烧模式等相关;汽油车尾气排放CO2的δ18O特征变化较大,同位素分馏更为复杂.化石燃料燃烧产生CO2的δ13C特征对化石燃料具有较好的指示作用.本研究为碳排放研究提供了重要的数据支持.

  19. Analysis of the heat affected zone in CO2 laser cutting of stainless steel

    Directory of Open Access Journals (Sweden)

    Madić Miloš J.

    2012-01-01

    Full Text Available This paper presents an investigation into the effect of the laser cutting parameters on the heat affected zone in CO2 laser cutting of AISI 304 stainless steel. The mathematical model for the heat affected zone was expressed as a function of the laser cutting parameters such as the laser power, cutting speed, assist gas pressure and focus position using the artificial neural network. To obtain experimental database for the artificial neural network training, laser cutting experiment was planned as per Taguchi’s L27 orthogonal array with three levels for each of the cutting parameter. Using the 27 experimental data sets, the artificial neural network was trained with gradient descent with momentum algorithm and the average absolute percentage error was 2.33%. The testing accuracy was then verified with 6 extra experimental data sets and the average predicting error was 6.46%. Statistically assessed as adequate, the artificial neural network model was then used to investigate the effect of the laser cutting parameters on the heat affected zone. To analyze the main and interaction effect of the laser cutting parameters on the heat affected zone, 2-D and 3-D plots were generated. The analysis revealed that the cutting speed had maximum influence on the heat affected zone followed by the laser power, focus position and assist gas pressure. Finally, using the Monte Carlo method the optimal laser cutting parameter values that minimize the heat affected zone were identified.

  20. Characteristics Analysis of CO2 and Heat Flux in Winter Wheat Fields%麦田CO2通量、热通量特征分析

    Institute of Scientific and Technical Information of China (English)

    彭记永; 胡继超; 刘荣花; 马青荣; 杨光仙

    2012-01-01

    为了评价麦田生态系统CO2通量和热通量变化特征以及CO2的收支状况,利用郑州农业气象试验站2009年10月 2010年6月冬小麦生育期内涡度观测数据,分析了麦田CO2通量、热通量变化特征.结果表明:净辐射、潜热通量、显热通量和土壤热通量日变化表现为明显的单峰特征,最大值一般出现在正午前后.其中,净辐射通量、显热通量和土壤热通量的季节变化特征较为一致,均为苗期<中期<后期;潜热通量受到叶面积指数(LAI)的影响,季节变化特征为苗期<后期<中期;CO2的季节变化特征受到LAI、热通量和下垫面特征的共同影响,形成1个CO2吸收高峰的U型曲线,季节变化特征为前期<后期<中期.冬小麦农田CO2、热通量具有明显的日变化和季节变化特征,麦田生态系统总体表现为CO2的汇.%By using the eddy covariance system data of the winter wheat growth stage from Octo-ber 2009 to June 2010 at agro-meteorological experimental station of Zhengzhou,the variations of heat and CO2 flux in winter wheat fields were analyzed. The results indicated that diurnal varia-tions of net radiation, latent heat, sensible heat and soil heat flux showed a uni-peak model, and the maximum values appeared around noon in general. The seasonal variation characteristics of net radiation, sensible heat and soil heat flux were comparatively consistent, minimum in seedling stage,next at metaphase and maximum at anaphase. Latent heat flux was affected obviously by leaf area index (LAI) , which in seeding stage was minimum,next at anaphase but maximum at meta-phase. CO2 flux was influenced by LAI, heat flux and the underlying surface, and its characteristics showed a U-shaped curve with an absorption peak. CO2 flux was minimum at prophase,next at anaphase but maximum at metaphase. The CO2 and heat flux in winter wheat fields had significant diurnal and sea-sonal variations, and overall, the ecosystem was a

  1. Histological and SEM analysis of root cementum following irradiation with Er:YAG and CO2 lasers.

    Science.gov (United States)

    Almehdi, Aslam; Aoki, Akira; Ichinose, Shizuko; Taniguchi, Yoichi; Sasaki, Katia M; Ejiri, Kenichiro; Sawabe, Masanori; Chui, Chanthoeun; Katagiri, Sayaka; Izumi, Yuichi

    2013-01-01

    Recently, the Er:YAG and CO(2) lasers have been applied in periodontal therapy. However, the characteristics of laser-irradiated root cementum have not been fully analyzed. The aim of this study was to precisely analyze the alterations of root cementum treated with the Er:YAG and the CO(2) lasers, using non-decalcified thin histological sections. Eleven cementum plates were prepared from extracted human teeth. Pulsed Er:YAG laser contact irradiation was performed in a line at 40 mJ/pulse (14.2 J/cm(2)/pulse) and 25 Hz (1.0 W) under water spray. Continuous CO(2) laser irradiation was performed in non-contact mode at 1.0 W, and ultrasonic instrumentation was performed as a control. The treated samples were subjected to stereomicroscopy, scanning electron microscopy (SEM), light microscopy and SEM energy dispersive X-ray spectroscopy (SEM-EDS). The Er:YAG laser-treated cementum showed minimal alteration with a whitish, slightly ablated surface, whereas CO(2) laser treatment resulted in distinct carbonization. SEM analysis revealed characteristic micro-irregularities of the Er:YAG-lased surface and the melted, resolidified appearance surrounded by major and microcracks of the CO(2)-lased surface. Histological analysis revealed minimal thermal alteration and structural degradation of the Er:YAG laser-irradiated cementum with an affected layer of approximately 20-μm thickness, which partially consisted of two distinct affected layers. The CO(2)-lased cementum revealed multiple affected layers showing different structures/staining with approximately 140 μm thickness. Er:YAG laser irradiation used with water cooling resulted in minimal cementum ablation and thermal changes with a characteristic microstructure of the superficial layer. In contrast, CO(2) laser irradiation produced severely affected distinct multiple layers accompanied by melting and carbonization.

  2. U.S. onroad transportation CO2 emissions analysis comparing highly resolved CO2 emissions and a national average approach : mitigation options and uncertainty reductions

    Science.gov (United States)

    Mendoza, D. L.; Gurney, K. R.

    2011-12-01

    The transportation sector is the second largest CO2 emitting economic sector in the United States, accounting for 32.3% of the total U.S. emissions in 2002. Within the transportation sector, the largest component (80%) is made up of onroad emissions. In order to accurately quantify future emissions and evaluate emissions regulation strategies, analysis must account for spatially-explicit fleet distribution, driving patterns, and mitigation strategies. Studies to date, however, have either focused on one of these three components, have been only completed at the national scale, or have not explicitly represented CO2 emissions instead relying on the use of vehicle miles traveled (VMT) as an emissions proxy. We compare a high resolution onroad emissions data product (Vulcan) to a national averaging of the Vulcan result. This comparison is performed in four groupings: light duty (LD) and heavy duty (HD) vehicle classes, and rural and urban road classes. Two different bias metrics are studied: 1) the state-specific, group-specific bias and 2) the same bias when weighted by the state share of the national group-specific emissions. In the first metric, we find a spread of positive and negative biases for the LD and HD vehicle groupings and these biases are driven by states having a greater/lesser proportion of LD/HD vehicles within their total state fleet than found from a national average. The standard deviation of these biases is 2.01% and 0.75% for the LD and HD groupings, respectively. These biases correlate with the road type present in a state, so that biases found in the urban and LD groups are both positive or both negative, with a similar relationship found between biases of the rural and HD groups. Additionally, the road group bias is driven by the distribution of VMT on individual road classes within the road groupings. When normalized by national totals, the state-level group-specific biases reflect states with large amounts of onroad travel that deviate

  3. An analysis of China's CO2 emission peaking target and pathways

    Directory of Open Access Journals (Sweden)

    Jian-Kun He

    2014-12-01

    Full Text Available China has set the goal for its CO2 emissions to peak around 2030, which is not only a strategic decision coordinating domestic sustainable development and global climate change mitigation but also an overarching target and a key point of action for China's resource conservation, environmental protection, shift in economic development patterns, and CO2 emission reduction to avoid climate change. The development stage where China maps out the CO2 emission peak target is earlier than that of the developed countries. It is a necessity that the non-fossil energy supplies be able to meet all the increased energy demand for achieving CO2 emission peaking. Given that China's potential GDP annual increasing rate will be more than 4%, and China's total energy demand will continue to increase by approximately 1.0%–1.5% annually around 2030, new and renewable energies will need to increase by 6%–8% annually to meet the desired CO2 emission peak. The share of new and renewable energies in China's total primary energy supply will be approximately 20% by 2030. At that time, the energy consumption elasticity will decrease to around 0.3, and the annual decrease in the rate of CO2 intensity will also be higher than 4% to ensure the sustained growth of GDP. To achieve the CO2 emission peaking target and substantially promote the low-carbon development transformation, China needs to actively promote an energy production and consumption revolution, the innovation of advanced energy technologies, the reform of the energy regulatory system and pricing mechanism, and especially the construction of a national carbon emission cap and trade system.

  4. Contrasting ecosystem CO2 fluxes of inland and coastal wetlands: a meta-analysis of eddy covariance data.

    Science.gov (United States)

    Lu, Weizhi; Xiao, Jingfeng; Liu, Fang; Zhang, Yue; Liu, Chang'an; Lin, Guanghui

    2017-03-01

    Wetlands play an important role in regulating the atmospheric carbon dioxide (CO2 ) concentrations and thus affecting the climate. However, there is still lack of quantitative evaluation of such a role across different wetland types, especially at the global scale. Here, we conducted a meta-analysis to compare ecosystem CO2 fluxes among various types of wetlands using a global database compiled from the literature. This database consists of 143 site-years of eddy covariance data from 22 inland wetland and 21 coastal wetland sites across the globe. Coastal wetlands had higher annual gross primary productivity (GPP), ecosystem respiration (Re ), and net ecosystem productivity (NEP) than inland wetlands. On a per unit area basis, coastal wetlands provided large CO2 sinks, while inland wetlands provided small CO2 sinks or were nearly CO2 neutral. The annual CO2 sink strength was 93.15 and 208.37 g C m(-2) for inland and coastal wetlands, respectively. Annual CO2 fluxes were mainly regulated by mean annual temperature (MAT) and mean annual precipitation (MAP). For coastal and inland wetlands combined, MAT and MAP explained 71%, 54%, and 57% of the variations in GPP, Re , and NEP, respectively. The CO2 fluxes of wetlands were also related to leaf area index (LAI). The CO2 fluxes also varied with water table depth (WTD), although the effects of WTD were not statistically significant. NEP was jointly determined by GPP and Re for both inland and coastal wetlands. However, the NEP/Re and NEP/GPP ratios exhibited little variability for inland wetlands and decreased for coastal wetlands with increasing latitude. The contrasting of CO2 fluxes between inland and coastal wetlands globally can improve our understanding of the roles of wetlands in the global C cycle. Our results also have implications for informing wetland management and climate change policymaking, for example, the efforts being made by international organizations and enterprises to restore coastal wetlands for

  5. Calcium isotope analysis by mass spectrometry.

    Science.gov (United States)

    Boulyga, Sergei F

    2010-01-01

    The variations in the isotopic composition of calcium caused by fractionation in heterogeneous systems and by nuclear reactions can provide insight into numerous biological, geological, and cosmic processes, and therefore isotopic analysis finds a wide spectrum of applications in cosmo- and geochemistry, paleoclimatic, nutritional, and biomedical studies. The measurement of calcium isotopic abundances in natural samples has challenged the analysts for more than three decades. Practically all Ca isotopes suffer from significant isobaric interferences, whereas low-abundant isotopes can be particularly affected by neighboring major isotopes. The extent of natural variations of stable isotopes appears to be relatively limited, and highly precise techniques are required to resolve isotopic effects. Isotope fractionation during sample preparation and measurements and instrumental mass bias can significantly exceed small isotope abundance variations in samples, which have to be investigated. Not surprisingly, a TIMS procedure developed by Russell et al. (Russell et al., 1978. Geochim Cosmochim Acta 42: 1075-1090) for Ca isotope measurements was considered as revolutionary for isotopic measurements in general, and that approach is used nowadays (with small modifications) for practically all isotopic systems and with different mass spectrometric techniques. Nevertheless, despite several decades of calcium research and corresponding development of mass spectrometers, the available precision and accuracy is still not always sufficient to achieve the challenging goals. The present article discusses figures of merits of presently used analytical methods and instrumentation, and attempts to critically assess their limitations. In Sections 2 and 3, mass spectrometric methods applied to precise stable isotope analysis and to the determination of (41)Ca are described. Section 4 contains a short summary of selected applications, and includes tracer experiments and the potential use

  6. [Supercritical CO2 extraction and component analysis of Aesculus wilsonii seed oil].

    Science.gov (United States)

    Chen, Guang-Yu; Shi, Zhao-Hua; Li, Hai-Chi; Ge, Fa-Huan; Zhan, Hua-Shu

    2013-03-01

    To research the optimal extraction process of supercritical CO2 extraction and analyze the component of the oil extracted from Aesculus wilsonii seed. Using the yield of Aesculus wilsonii seed oil as the index, optimized supercritical CO2 extraction parameter by orthogonal experiment methodology and analysed the compounds of Aesculus wilsonii seed oil by GC-MS. The optimal parameters of the supercritical CO2 extraction of the oil extracted from Aesculus wilsoniit seed were determined: the extraction pressure was 28 MPa and the temperature was 38 degrees C, the separation I pressure was 12 MPa and the temperature was 40 degrees C, the separation II pressure was 5 MPa and the temperature was 40 degrees C, the extraction time was 110 min. The average extraction rate of Aesculus wilsonii seed oil was 1.264%. 26 kinds of compounds were identified by GC-MS in Aesculus wilsonii seed oil extracted by supercritical CO2. The main components were fatty acids. Comparing with the petroleum ether extraction, the supercritical CO2 extraction has higher extraction rate, shorter extraction time, more clarity oil. The kinds of fatty acids with high amounts in Aesculus wilsonii seed oil is identical in general, the kinds of fatty acids with low amounts in Aesculus wilsonii seed oil have differences.

  7. A statistical analysis of three ensembles of crop model responses totemperature and CO2concentration

    DEFF Research Database (Denmark)

    Makowski, D; Asseng, S; Ewert, F.

    2015-01-01

    levels, and can thus be used to calculate temperature and [CO2] thresholds leading to yield loss or yield gain, without re-running the original complex crop models. Our approach is illustrated with three yield datasets simulated by 19 maize models, 26 wheat models, and 13 rice models. Several statistical......Ensembles of process-based crop models are increasingly used to simulate crop growth for scenarios of temperature and/or precipitation changes corresponding to different projections of atmospheric CO2 concentrations. This approach generates large datasets with thousands of simulated crop yield data...... in the simulation protocols. Here we demonstrate that statistical models based on random-coefficient regressions are able to emulate ensembles of process-based crop models. An important advantage of the proposed statistical models is that they can interpolate between temperature levels and between CO2 concentration...

  8. Numerical Simulation and Analysis of CO2 Removal in a Polypropylene Hollow Fiber Membrane Contactor

    Directory of Open Access Journals (Sweden)

    Zhien Zhang

    2014-01-01

    Full Text Available This present study shows a comprehensive 2D numerical model for removal of CO2 in a polypropylene (PP hollow fiber membrane contactor (HFMC using the computational fluid dynamics (CFD method. Monoethanolamine (MEA solution was used as the liquid absorbent in a nonwetting mode. The simulation results represented that higher liquid velocity and concentration and lower gas velocity and concentration led to higher percent of CO2 removal. The most proper parameters for CO2 removal were less than 1 mol m−3 gas concentration and 0.2 m s−1 gas flow rate, and for MEA the values were above 8 mol m−3 concentration and approximately 1 m s−1 liquid velocity. Furthermore, the model was validated with the experiment results. Therefore, the modeling results provided references to the selection of absorbents and operation parameters in the experimental study and pilot-scale applications.

  9. Analysis of Pulsed Airborne Lidar Measurements of Atmospheric CO2 Column Absorption from 3-13 km Altitudes

    Science.gov (United States)

    Abshire, James B.; Weaver, Clark J.; Riris, Haris; Mao, Jianping; Sun, Xiaoli; Allan, Graham R.; Hasselbrack, William; Browell, Edward V.

    2011-01-01

    through thin clouds. The Oklahoma and east coast flights were coordinated with a LaRC/ITT CO2 lidar on the LaRC UC-12 aircraft, and in-situ measurements were made using its CO2 sensor and radiosondes. We have conducted an analysis of the ranging and IPDA lidar measurements from these four flights. Most flights had 5-6 altitude steps with 200-300 seconds of recorded measurements per step. We used a cross-correlation approach to process the laser echo records. This was used to estimate the range to the scattering surface, to define the edges of the laser pulses and to determine echo pulse energy at each wavelength. We used a minimum mean square approach to fit an instrument response function and to solve for the best-fit CO2 absorption line shape. We then calculated the differential optical depth (DOD) of the fitted CO2 line. We computed its statistics at the various altitude steps, and compare them to the DODs calculated from spectroscopy based on HITRAN 2008 and the column conditions calculated from the airborne in-situ readings. The results show the lidar and in-situ measurements have very similar DOD change with altitude and greater than 10 segments per flight where the scatter in the lidar measurements are less than or equal to 1ppm. We also present the results from subsequent CO2 column absorption measurements, which were made with stronger detected signals during three flights on the NASA DC-8 over the southwestern US in during July 2010.

  10. A dynamic leaf gas-exchange strategy is conserved in woody plants under changing ambient CO2: evidence from carbon isotope discrimination in paleo and CO2 enrichment studies

    Science.gov (United States)

    Rising atmospheric [CO2], ca, is expected to affect stomatal regulation of leaf gas-exchange of woody plants, thus influencing energy fluxes as well as carbon (C), water and nutrient cycling of forests. Researchers have reported that stomata regulate leaf gas-exchange around &ldq...

  11. Analysis of a Complex Faulted CO 2 Reservoir Using a Three-dimensional Hydro-geochemical-Mechanical Approach

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Ba Nghiep; Hou, Zhangshuan; Bacon, Diana H.; Last, George V.; White, Mark D.

    2017-07-01

    This work applies a three-dimensional (3D) multiscale approach recently developed by Nguyen et al. (Int. J. Greenhouse Gas Control, 2016, 46:100-115; Greenhouse Gases: Sci. & Technol., DOI: 10.1002/ghg.1616) to analyze a complex CO2 faulted reservoir that includes some key geological features of the San Andreas and nearby faults. The approach couples the STOMP-CO2-R code for flow and reactive transport modeling to the ABAQUS® finite element package for geomechanical analysis. The objective is to examine the coupled hydro-geochemical-mechanical impact on the risk of hydraulic fracture and fault slip in a complex and representative CO2 reservoir that contains two nearly parallel faults. STOMP-CO2-R/ABAQUS® coupled analyses of this reservoir are performed assuming extensional and compressional stress regimes to predict evolutions of fluid pressure, stress and strain distributions as well as potential fault failure and leakage of CO2 along the fault damage zones. The tendency for the faults to slip and pressure margin to fracture are examined in terms of stress regime, mineral composition, crack distributions in the fault damage zones and geomechanical properties. This model in combination with a detailed description of the faults helps assess the coupled hydro-geochemical-mechanical effect.

  12. Exergy Analysis of a Syngas-Fueled Combined Cycle with Chemical-Looping Combustion and CO2 Sequestration

    Directory of Open Access Journals (Sweden)

    Álvaro Urdiales Montesino

    2016-08-01

    Full Text Available Fossil fuels are still widely used for power generation. Nevertheless, it is possible to attain a short- and medium-term substantial reduction of greenhouse gas emissions to the atmosphere through a sequestration of the CO2 produced in fuels’ oxidation. The chemical-looping combustion (CLC technique is based on a chemical intermediate agent, which gets oxidized in an air reactor and is then conducted to a separated fuel reactor, where it oxidizes the fuel in turn. Thus, the oxidation products CO2 and H2O are obtained in an output flow in which the only non-condensable gas is CO2, allowing the subsequent sequestration of CO2 without an energy penalty. Furthermore, with shrewd configurations, a lower exergy destruction in the combustion chemical transformation can be achieved. This paper focus on a second law analysis of a CLC combined cycle power plant with CO2 sequestration using syngas from coal and biomass gasification as fuel. The key thermodynamic parameters are optimized via the exergy method. The proposed power plant configuration is compared with a similar gas turbine system with a conventional combustion, finding a notable increase of the power plant efficiency. Furthermore, the influence of syngas composition on the results is investigated by considering different H2-content fuels.

  13. [Optimization for supercritical CO2 extraction with response surface methodology and component analysis of Sapindus mukorossi oil].

    Science.gov (United States)

    Wu, Yan; Xiao, Xin-yu; Ge, Fa-huan

    2012-02-01

    To study the extraction conditions of Sapindus mukorossi oil by Supercritical CO2 Extraction and identify its components. Optimized SFE-CO2 Extraction by response surface methodology and used GC-MS to analysie Sapindus mukorossi oil compounds. Established the model of an equation for the extraction rate of Sapindus mukorossi oil by Supercritical CO2 Extraction, and the optimal parameters for the Supercritical CO2 Extraction determined by the equation were: the extraction pressure was 30 MPa, temperature was 40 degrees C; The separation I pressure was 14 MPa, temperature was 45 degrees C; The separation II pressure was 6 MPa, temperature was 40 degrees C; The extraction time was 60 min and the extraction rate of Sapindus mukorossi oil of 17.58%. 22 main compounds of Sapindus mukorossi oil extracted by supercritical CO2 were identified by GC-MS, unsaturated fatty acids were 86.59%. This process is reliable, safe and with simple operation, and can be used for the extraction of Sapindus mukorossi oil.

  14. Improving uncertainty evaluation of process models by using pedigree analysis. A case study on CO2 capture with monoethanolamine

    NARCIS (Netherlands)

    van der Spek, Mijndert; Ramirez, Andrea|info:eu-repo/dai/nl/284852414; Faaij, André

    2016-01-01

    This article aims to improve uncertainty evaluation of process models by combining a quantitative uncertainty evaluation method (data validation) with a qualitative uncertainty evaluation method (pedigree analysis). The approach is tested on a case study of monoethanolamine based postcombustion CO2

  15. Accelerating CO2-Emission Reductions via Corporate Programmes; Analysis of an Existing Corporate Programme

    NARCIS (Netherlands)

    Manser, J.; Handgraaf, M.J.J.; Schubert, R.; Gsottbauer, E.; Cornielje, M.; Lede, E.

    2013-01-01

    This working paper analyzes and assesses the COYou2 Program of the company Swiss Re. This corporate program allows employees to claim subsidies for the realization of various activities reducing their energy consumption and CO2-emissions at home. Examples of such activities are the purchase of a hyb

  16. Accelerating CO2-Emission Reductions via Corporate Programmes; Analysis of an Existing Corporate Programme

    NARCIS (Netherlands)

    Manser, J.; Handgraaf, M.J.J.; Schubert, R.; Gsottbauer, E.; Cornielje, M.; Lede, E.

    2013-01-01

    This working paper analyzes and assesses the COYou2 Program of the company Swiss Re. This corporate program allows employees to claim subsidies for the realization of various activities reducing their energy consumption and CO2-emissions at home. Examples of such activities are the purchase of a

  17. Metabolomics analysis of the effect of elevated co2 on wheat resistance to Fusarium head blight

    Science.gov (United States)

    Climate change is expected to intensify Fusarium head blight (FHB) contamination of wheat and increase the associated risk of mycotoxin contamination in food and feed. Rising CO2 levels are part of climate change with still unknown effects on natural wheat resistance mechanisms against Fusarium gram...

  18. Thermodynamic analysis of framework deformation in Na,Cs-RHO zeolite upon CO2 adsorption.

    Science.gov (United States)

    Pera-Titus, M; Palomino, M; Valencia, S; Rey, F

    2014-11-28

    Fully dehydrated and partially sodium-cesium containing RHO zeolite (Na,Cs-RHO) shows a genuine inflection in the CO2 isotherms in the temperature range 293-333 K that can be attributed to a sorbate-induced framework deformation from an acentric (A) to a centric (C) phase due to a partial cation rearrangement. This peculiar sorption pattern can be captured by the formulation of thermodynamic isotherms, providing a direct enthalpic and entropic signature of the CO2 adsorption-desorption process during deformation. Using this formulation, the energy barrier between the acentric and centric phases for CO2 adsorption-desorption was estimated in the range 4.7-9.6 J g(-1) of solid (15-32 kJ mol(-1)), reflecting a higher CO2 affinity for the acentric phase, whereas the elastic energy involved during framework distortion was estimated in the range 6-12 J g(-1) of solid (19-39 kJ mol(-1)) with a relative maximum at 303 K and showing a dominant entropic contribution.

  19. Macroeconomic effects of CO2 emission limits : A computable general equilibrium analysis for China

    NARCIS (Netherlands)

    Zhang, ZX

    1998-01-01

    The study analyzes the macroeconomic effects of limiting China's CO2 emissions by using a time-recursive dynamic computable general equilibrium (CGE) model of the Chinese economy. The baseline scenario for the Chinese economy over the period to 2010 is first developed under a set of assumptions abou

  20. Analysis of GHG Emission Reduction in South Korea Using a CO2 Transportation Network Optimization Model

    Directory of Open Access Journals (Sweden)

    Suk Ho Jin

    2017-07-01

    Full Text Available Korea’s national carbon capture and storage (CCS master plan aims to commercialize CCS projects by 2030. Furthermore, the Korean government is forced to reduce emissions from various sectors, including industries and power generation, by 219 million tons by 2030. This study analyzes a few scenarios of Korean CCS projects with a CO2 pipeline transportation network optimization model for minimizing the total facility cost and pipeline cost. Our scenarios are based on the “2030 asic roadmap for reducing greenhouse gases” established by the government. The results for each scenario demonstrate that the effective design and implementation of CO2 pipeline network enables the lowering of CO2 units cost. These suggest that CO2 transportation networks, which connect the capture and sequestration parts, will be more important in the future and can be used to substitute and supplement the emission reduction target in case the execution of other reduction options faces uncertainty. Our mathematical model and scenario designs will be helpful for various countries which plan to introduce CCS technology.

  1. Interactions between plant growth and soil nutrient cycling under elevated CO2: a meta-analysis

    NARCIS (Netherlands)

    Graaff, de M.A.; Groenigen, van K.J.; Six, J.; Hungate, B.; Kessel, van C.

    2006-01-01

    free air carbon dioxide enrichment (FACE) and open top chamber (OTC) studies are valuable tools for evaluating the impact of elevated atmospheric CO2 on nutrient cycling in terrestrial ecosystems. Using meta-analytic techniques, we summarized the results of 117 studies on plant biomass production, s

  2. Value chain analysis of CO2 storage by using the Ecco tool: Storage economics

    NARCIS (Netherlands)

    Loeve, D.; Bos, C.; Chitu, A.; Loveseth, S.; Wahl, P.E.; Coussy, P.; Eickhoff, C.

    2013-01-01

    The ECCO Tool [1, 2] has been developed in the “ECCO – European value chain for CO2” project [3]. ECCO was a collaborating project under the 7th framework programme for research of the EU. The ECCO Tool is a software program designed to evaluate quantitatively the post-tax economics of Carbon

  3. A comparative analysis of simulated and observed photosynthetic CO2 uptake in two coniferous forest canopies

    DEFF Research Database (Denmark)

    Ibrom, A.; Jarvis, P.G.; Clement, R.

    2006-01-01

    Gross canopy photosynthesis (Pg) can be simulated with canopy models or retrieved from turbulent carbon dioxide (CO2) flux measurements above the forest canopy. We compare the two estimates and illustrate our findings with two case studies. We used the three-dimensional canopy model MAESTRA to si...

  4. Bayesian Information-Gap Decision Analysis Applied to a CO2 Leakage Problem

    Science.gov (United States)

    O'Malley, D.; Vesselinov, V. V.

    2014-12-01

    We describe a decision analysis in the presence of uncertainty that combines a non-probabilistic approach (information-gap decision theory) with a probabilistic approach (Bayes' theorem). Bayes' theorem is one of the most popular techniques for probabilistic uncertainty quantification (UQ). It is effective in many situations, because it updates our understanding of the uncertainties by conditioning on real data using a mathematically rigorous technique. However, the application of Bayes' theorem in science and engineering is not always rigorous. There are two reasons for this: (1) We can enumerate the possible outcomes of dice-rolling, but not the possible outcomes of real-world contamination remediation; (2) We can precisely determine conditional probabilities for coin-tossing, but substantial uncertainty surrounds the conditional probabilities for real-world contamination remediation. Of course, Bayes' theorem is rigorously applicable beyond dice-rolling and coin-tossing, but even in cases that are constructed to be simple with ostensibly good probabilistic models, applying Bayes' theorem to the real world may not work as well as one might expect. Bayes' theorem is rigorously applicable only if all possible events can be described, and their conditional probabilities can be derived rigorously. Outside of this domain, it may still be useful, but its use lacks at least some rigor. The information-gap approach allows us to circumvent some of the highlighted shortcomings of Bayes' theorem. In particular, it provides a way to account for possibilities beyond those described by our models, and a way to deal with uncertainty in the conditional distribution that forms the core of Bayesian analysis. We have developed a three-tiered technique enables one to make scientifically defensible decisions in the face of severe uncertainty such as is found in many geologic problems. To demonstrate the applicability, we apply the technique to a CO2 leakage problem. The goal is to

  5. Pembina Cardium CO2-EOR monitoring project: Integrated surface seismic and VSP time-lapse seismic analysis

    Science.gov (United States)

    Alshuhail, A. A.

    2009-12-01

    In the Pembina field in west-central Alberta, Canada, approximately 40,000 tons of supercritical CO2 was injected into the 1650 m deep, 20 m thick upper-Cretaceous Cardium Fm. between March 2005 and 2007. A time-lapse seismic program was designed and incorporated into the overall measurement, monitoring and verification program. The objectives were to track the CO2 plume within the reservoir, and to evaluate the integrity of storage. Fluid replacement modeling predicts a decrease in the P-wave velocity and bulk density in the reservoir by about 4% and 1%, respectively. Synthetic seismograms show subtle reflectivity changes at the Cardium Fm. and a traveltime delay at the later high-amplitude Viking event of less than 1 ms. The time-lapse datasets, however, show no significant anomalies in the P-wave seismic data that can be attributed to supercritical CO2 injected into the Cardium Fm. (Figure 1). The converted-wave (P-S) data, on the other hand, showed small traveltime anomalies. The most coherent results were those obtained by the fixed-array VSP dataset (Figure 2) due to higher frequency bandwidth and high signal to noise ratio. The amplitude and traveltime changes observed in the VSP dataset are small but are consistent in magnitude with those predicted from rock physics modeling. The analysis suggests that the inability to clearly detect the CO2 plume in surface seismic data is likely due to the CO2 being contained in thin permeable sandstone members of the Cardium Formation. The seismic signature of the Cardium Fm. in this area may also be degraded by multiples and strong attenuation involving the shallow Ardley coals. However, the lack of a 4D seismic changes above the reservoir indicates that the injected CO2 is not migrating through the caprock into shallower formations.

  6. CO2驱油井产能及影响因素敏感性分析%CO2 Flooding Well Productivity and Its Impacting Factor Sensitivity Analysis

    Institute of Scientific and Technical Information of China (English)

    尚庆华; 吴晓东; 韩国庆; 安永生; 王庆; 王旭东

    2011-01-01

    In order to determine the impacting factors of CO2 flooding well productivity and to establish the productivity prediction equation, the impacting factors sensitivity analysis were conducted based on reservoir numerical simulation and orthogonal analysis with consideration of impact of reservoir and fluid property on well productivity. The productivity equation for CO2 flooding was established based on the orthogonal normalized results. Sensitivity analysis show that the influence degree of each factor in decreasing order is relative permeability,CO2 content, crude oil composition, permeability, drainage radius, skin factor and reservoir pressure. The most significant influencing parameters are relative permeability and CO2 content. Well productivity equation becomes more nonlinear with the increase of CO2 content. In the early stage of field development, well productivity increases with the increase of CO2 content,while the increase of CO2 content damages well productivity if the reservoir is depleted. The established productivity equations in this paper can provide guidance for oilfield development. The productivity prediction equation regression coefficient is high and its application is convenient which can provide reference and guidance for similar reservoir field development and adjustment program.%为了明确CO2驱油井产能影响因素,基于油藏数值模拟和正交试验设计与分析方法,考虑不同油藏和流体物性对油井产能的影响,对CO2驱油井产能影响因素进行了敏感性分析,并在正交试验结果归一化处理的基础上,初步建立了CO2驱油井产能方程.敏感性分析结果表明,各因素影响程度从大到小依次为相渗曲线、CO2物质的量分数、原油组成、渗透率、泄油半径、表皮因子和地层压力,其中影响最为显著的是相渗曲线和CO2物质的量分数,且随CO2物质的量分数的增大,油井产能方程的非线性增强.在油田开采初期,油井产能随CO2

  7. Systems and economic analysis of microalgae ponds for conversion of CO2 to biomass

    Science.gov (United States)

    Benemann, J. R.; Oswald, W. J.

    1994-05-01

    In the section entitled 'Photobioreactors for Mic roalgae Production of Fuels and Chemicals' the authors consider the current and potential commercial products that can be derived from microalgae during a process of CO2 utilization, alternative photobioreactor designs, and the fundamental biological and bioengineering issues in microalgae production. They emphasize the long term potential of microalgae production of low value commodities, specifically alternative fuels, which would have the greatest potential for large-scale CO2 utilization. Section 2 discusses the development of low cost technologies for macro algae harvesting. First a brief review of the current experience in algae harvesting in large-scale commercial operations is presented. This is followed by a general discussion of various algae harvesting processes, followed by a comparative evaluation of the various processes and discussion of future prospects.

  8. Data Analysis of a Pulsed 2-micron Coherent Differential Absorption Lidar For Atmospheric CO2 Measurements

    Science.gov (United States)

    Lu, J.; Yu, J.

    2013-12-01

    The study of climate change requires precise measurement of the production, migration, and sinking of greenhouse gases. Carbon Dioxide (CO2) is one of the principal greenhouse gases. NASA Langley Research Center (LARC) has developed a pulsed 2-micron coherent differential absorption lidar (DiAL) for CO2 measurement, operating on the R30 absorption line. On April 5, 2010, the lidar instrument transmitted alternating On-line and Off-line pulses from LARC into a residential area in Poquoson, Virginia; while a passive in-situ sensor measured the local CO2 concentration. This paper outlines a procedure to estimate CO2 concentration from atmospheric lidar return signal using the DiAL method; our calculation produced results in line with the in-situ measurement and matched the current state of DiAL instrument accuracy. Data from April 5 is part of a series of experiments validating the measurement accuracy and precision of this lidar. After a summative verification, a packaged lidar may be installed on research aircraft to perform CO2 studies at a great range of latitudes throughout the year, and to discover sources, sinks, and migration trends for this key greenhouse gas. The following procedure is used to estimate CO2 concentration from atmospheric lidar return using the DiAL method. First, MATLAB software developed at LARC sorts the lidar return into On-only and Off-only files containing pulses of only that type. The sorted pulses are reexamined for quality based on the center frequency, energy, and power - unsatisfactory pulses are removed. A 512-point Fast Fourier Transform (FFT) with 256-point shift is performed on each pulse to discretize the atmospheric return signal according to 63 distance 'bins'. Next, comparing decay rates of the On-line and Off-line atmospheric return intensity with distance yields the Differential Absorption Optical Slope (DAOD), which is proportional to the concentration of the desired gas. Then, in-situ meteorological data - pressure

  9. In Situ Raman Analysis of CO2—Assisted Drying of Fruit-Slices

    Directory of Open Access Journals (Sweden)

    Andreas Siegfried Braeuer

    2017-05-01

    Full Text Available This work explores the feasibility of applying in situ Raman spectroscopy for the online monitoring of the supercritical carbon dioxide (SC-CO2 drying of fruits. Specifically, we investigate two types of fruits: mango and persimmon. The drying experiments were carried out inside an optical accessible vessel at 10 MPa and 313 K. The Raman spectra reveal: (i the reduction of the water from the fruit slice and (ii the change of the fruit matrix structure during the drying process. Two different Raman excitation wavelengths were compared: 532 nm and 785 nm. With respect to the quality of the obtained spectra, the 532 nm excitation wavelength was superior due to a higher signal-to-noise ratio and due to a resonant excitation scheme of the carotenoid molecules. It was found that the absorption of CO2 into the fruit matrix enhances the extraction of water, which was expressed by the obtained drying kinetic curve.

  10. 利用多年冻土区湖相沉积物中埋藏植物稳定 碳同位素组成重建大气CO2浓度%The Records of Atmospheric CO2 Derived from the Stable Carbon Isotopic Composition of Buried Plant Tissues in Perennial Frozen Lacustrine Sediments

    Institute of Scientific and Technical Information of China (English)

    林清; 王绍令; 赵林

    2001-01-01

    The stable carbon isotopic fractionation in submerged plant is dependent upon the concentration of dissolved inorganic carbon (DIC) which equilibrates with atmosphere CO2 by water-gas exchange and indirectly provides an approach to rebuild the past atmospheric CO2 concentration. The Ngoring Lake is the largest outflow freshwater lake in the source region of the Yellow River and has well-developed aquatic vegetation of submersed plants. Due to low air temperature (-4.5 ℃ in average), the lacustrine sediments are perennial frozen below the depth of 1.05 m, at which the temperature is -0.5 C. The plant tissues in the sediments are well preserved and can be separated. In this study, the well-preserved plant tissues were separated from 2 m thick perennial frozen lacustrine sediments which consist of fine-silty clays. These tissues were apparently formed under relatively uniform water condition and mainly came from the same species of submerged plant-Potamnogeton pectinatus by identification. The stable carbon isotope composition (δ13C) is calculated from stable carbon isotope ratio measured from a carbon dioxide by FINNIGAN MAT251 mass-spectrometer. The carbon dioxide is produced by combustion of an aliquot of plant tissues with a little pre-cleaned cupric oxide and platinum filament in an evacuated fine quartz tube at 800C for 2 h. The study shows that the relationship betweenδ13C of Potamogeton pectinatus and the concentration of dissolved CO2 [CO2e] can be described as Equation (5). The concentration of dissolved CO2 [CO2e] is calculated as [CO2e ] = a × Pco , where Pco2 is at-mospheric CO2 concentration and a is the solubility parameter which can be induced by the absolute temperature of water from ln a = (58. 0931 +90. 5069× (100/T) -+- 22. 294 × ln(T/100). δco. can be calculated using the equilibrium isotope fractionation and mixing model among the inorganic-carbon species as a function of temperature, carbon isotope composition and ratio of

  11. Developing a GIS for CO2 analysis using lightweight, open source components

    Science.gov (United States)

    Verma, R.; Goodale, C. E.; Hart, A. F.; Kulawik, S. S.; Law, E.; Osterman, G. B.; Braverman, A.; Nguyen, H. M.; Mattmann, C. A.; Crichton, D. J.; Eldering, A.; Castano, R.; Gunson, M. R.

    2012-12-01

    There are advantages to approaching the realm of geographic information systems (GIS) using lightweight, open source components in place of a more traditional web map service (WMS) solution. Rapid prototyping, schema-less data storage, the flexible interchange of components, and open source community support are just some of the benefits. In our effort to develop an application supporting the geospatial and temporal rendering of remote sensing carbon-dioxide (CO2) data for the CO2 Virtual Science Data Environment project, we have connected heterogeneous open source components together to form a GIS. Utilizing widely popular open source components including the schema-less database MongoDB, Leaflet interactive maps, the HighCharts JavaScript graphing library, and Python Bottle web-services, we have constructed a system for rapidly visualizing CO2 data with reduced up-front development costs. These components can be aggregated together, resulting in a configurable stack capable of replicating features provided by more standard GIS technologies. The approach we have taken is not meant to replace the more established GIS solutions, but to instead offer a rapid way to provide GIS features early in the development of an application and to offer a path towards utilizing more capable GIS technology in the future.

  12. Analysis of influence of atmosphere extinction to Raman lidar monitoring CO2 concentration profile

    Institute of Scientific and Technical Information of China (English)

    Zhao Pei-Tao; Zhang Yin-Chao; Wang Lian; Zhao Yue-Feng; Su Jia; Fang Xin; Cao Kai-Fa; Xie Jun; Du Xiao-Yong

    2007-01-01

    Lidar (Light detection and ranging) system monitoring of the atmosphere is a novel and powerful technique tool. The Raman lidar is well established today as a leading research tool in the study of numerous important areas in the atmospheric sciences. In this paper, the principle of Raman lidar technique measurement CO2 concentration profile is presented and the errors caused by molecular and aerosol extinction for CO2 concentration profile measurement with Raman lidar are also presented. The standard atmosphere extinction profile and 'real-time' Hefei area extinction profile are used to conduct correction and the corresponding results are yielded. Simulation results with standard atmosphere mode correction indicate that the errors caused by molecule and aerosol extinction should be counted for the reason that they could reach about 8 ppm and 5 ppm respectively. The relative error caused by Hefei area extinction correction could reach about 6%. The errors caused by the two components extinction influence could produce significant changes for CO2 concentration profile and need to be counted in data processing which could improve the measurement accuracies.

  13. CO and CO2 analysis in the diving gas of the fishermen of the Yucatan Peninsula.

    Science.gov (United States)

    Chin, Walter; Huchim, Oswaldo; Wegrzyn, Grace H; Sprau, Susan E; Salas, Silvia; Markovitz, Gerald H

    2015-01-01

    It is reported that more than 75% of 400 artisanal fisherman divers working off the Yucatan Peninsula experience decompression sickness (DCS) each year, making DCS an epidemic in this region. These divers use primitive hookah diving support systems (HDSS). Breathing air is supplied from inadequately filtered and poorly maintained gasoline-powered air compressors. We hypothesized that air supplies could be contaminated. Air contamination could produce symptoms consistent with some presentations of DCS. This could confound and falsely elevate the true incidence of DCS. A cross-sectional study was undertaken in a fishing community. Ten fishermen from a single cohort participated. Fishermen were instructed not to drain volume tanks following their last dive of the day before their diving air was sampled. Dräger carbon monoxide (CO) 5/a-P and carbon dioxide (CO2) 100/a Short-term Tubes were used to measure 1.0 liters (L) of gas through a Visi-Float flow meter at 0.2 L/minute. Average CO value was 42 ppm (8-150 ppm). Average CO2 was 663 ppm (600-800). Measurements exceeded recommended diving norms for CO of 20 ppm. CO2 exceeded one diving organization recommendation of 500 ppm. Separation of engine exhaust from compressor intake could decrease CO values in HDSS to acceptable standards thus eliminating one possible confounder from this DCS epidemic.

  14. Analysis of CO2 Emission Characteristics of Concrete Used at Construction Sites

    Directory of Open Access Journals (Sweden)

    Tae Hyoung Kim

    2016-04-01

    Full Text Available As the greenhouse gas reduction goal of 37% below business-as-usual (BAU by 2030, the construction industry is recognized as an anti-environment industry for mass consumption/mass waste; thus, members of the industry are requested to make efforts to transform it into an environment-friendly industry. Concrete, a common construction material, is known to emit large amounts of environmentally hazardous waste during the processes related to its production, construction, maintenance, and demolition. The amount of greenhouse gas (GHG emissions by the product is specified in a ready-mixed concrete report whenever concrete is sold commercially. Hence, there have been many studies addressing the quantitative evaluation and reduction of the environmental effects of concrete. This study aims to introduce a method for assessing the amount of carbon dioxide emission from the processes of producing concrete. Moreover, we measured the quantities of CO2 emission of about 10 under-construction projects, including office buildings, apartment buildings, and high-rise residential buildings in South Korea. Using the assessment result, we analyzed the CO2 reduction performance of an office building in South Korea and drew conclusions about measures for reducing CO2 emission.

  15. Experimental and theoretical analysis of defocused CO2 laser microchanneling on PMMA for enhanced surface finish

    Science.gov (United States)

    Prakash, Shashi; Kumar, Subrata

    2017-02-01

    The poor surface finish of CO2 laser-micromachined microchannel walls is a major limitation of its utilization despite several key advantages, like low fabrication cost and low time consumption. Defocused CO2 laser beam machining is an effective solution for fabricating smooth microchannel walls on polymer and glass substrates. In this research work, the CO2 laser microchanneling process on PMMA has been analyzed at different beam defocus positions. Defocused processing has been investigated both theoretically and experimentally, and the depth of focus and beam diameter have been determined experimentally. The effect of beam defocusing on the microchannel width, depth, surface roughness, heat affected zone and microchannel profile were examined. A previously developed analytical model for microchannel depth prediction has been improved by incorporating the threshold energy density factor. A semi-analytical model for predicting the microchannel width at different defocus positions has been developed. A semi-empirical model has also been developed for predicting microchannel widths at different defocusing conditions for lower depth values. The developed models were compared and verified by performing actual experiments. Multi-objective optimization was performed to select the best optimum set of input parameters for achieving the desired surface roughness.

  16. [Supercritical CO2 fluid extraction and component analysis of leaves oil from Taxus chinensis var. mairei].

    Science.gov (United States)

    Tang, Bin; Zhang, Feng-su; Li, Xiang; Chen, Jian-wei; Yao, Xiao

    2013-12-01

    To research the optimal extraction process of supercritical CO2 extraction and analyze the component of the oil extracted from leaves of Taxus chinensis var. mairei. Using the yield of leaves oil from Taxus chinensis var. mairei as the index, investigated the effect of the extraction pressure, extraction temperature and extraction time on the extracting-rate of leaves oil. The chemical composition of the extracted leaves oil was analyzed by derivatized GC-MS. The optimal parameters of the supercritical CO2 extraction of the oil extracted from leaves of Taxus chinensis var. mairei were determined: CO2 compressor pump frequency was 10 Hz, the extraction pressure was 25 MPa and the temperature of extraction was 45 degrees C, the extraction time was 120 min, the isolator I pressure was 8.0 MPa and the temperature of extraction was 40 degrees C, the isolator II pressure was 5.0 MPa and the temperature of extraction was 35 degrees C. The extracted leaves oil was derivatized with boron trifluoride-methanol complex. Thirty-three kinds of fatty acids were identified by GC-MS. The yield of leaves oils are different from Taxus chinensis var. mairei from 3 habitats. The yield of leaves oil from Donggang, Wuxi city is the highest, about 2.61%. The kinds of fatty acids with high amounts in leaves oil from Taxus chinensis var. mairei is identical in general, the kinds of fatty acids with low amounts in leaves oil from Taxus chinensis var. mairei have differences.

  17. Exergy Analysis of Trans- critical CO2 Cycle%跨临界CO2制冷循环(火用)分析

    Institute of Scientific and Technical Information of China (English)

    司春强; 刘小朋; 林楚桂; 肖杨

    2012-01-01

    The loss exergy and its exergy efficiency of trans - critical CO2 cycle were analyzed based on thermodynamic secondly principle. The results showed that the loss exery was maximum during throttling and exergy efficiency of cycle was only 25% . Increasing evaporation temperature and decreasing the end temperature of cooling were effective ways to improve the exergy efficiency of cycle. Rising cooling pressure can lowering exergy loss of throttling, but had little effect on the exergy efficiency of cycle.%基于热力学第二定律,对跨临界CO2制冷循环过程的损失及(火用)效率进行理论分析,发现节流过程(火用)损失最大,循环(火用)效率为25%.提高蒸发温度和降低冷却终了温度是提高循环(火用)效率的有效途径;升高冷却压力,可以降低节流过程(火用)损失,但是对循环(火用)效率影响不大.

  18. Analysis of the impact path on factors of China's energy-related CO2 emissions: a path analysis with latent variables.

    Science.gov (United States)

    Chen, Wenhui; Lei, Yalin

    2017-02-01

    Identifying the impact path on factors of CO2 emissions is crucial for the government to take effective measures to reduce carbon emissions. The most existing research focuses on the total influence of factors on CO2 emissions without differentiating between the direct and indirect influence. Moreover, scholars have addressed the relationships among energy consumption, economic growth, and CO2 emissions rather than estimating all the causal relationships simultaneously. To fill this research gaps and explore overall driving factors' influence mechanism on CO2 emissions, this paper utilizes a path analysis model with latent variables (PA-LV) to estimate the direct and indirect effect of factors on China's energy-related carbon emissions and to investigate the causal relationships among variables. Three key findings emanate from the analysis: (1) The change in the economic growth pattern inhibits the growth rate of CO2 emissions by reducing the energy intensity; (2) adjustment of industrial structure contributes to energy conservation and CO2 emission reduction by raising the proportion of the tertiary industry; and (3) the growth of CO2 emissions impacts energy consumption and energy intensity negatively, which results in a negative impact indirectly on itself. To further control CO2 emissions, the Chinese government should (1) adjust the industrial structure and actively develop its tertiary industry to improve energy efficiency and develop low-carbon economy, (2) optimize population shifts to avoid excessive population growth and reduce energy consumption, and (3) promote urbanization steadily to avoid high energy consumption and low energy efficiency.

  19. Variability and budget of CO2 in Europe: analysis of the CAATER airborne campaigns – Part 1: Observed variability

    Directory of Open Access Journals (Sweden)

    P. Ciais

    2010-02-01

    Full Text Available Atmospheric airborne measurements of CO2 are very well-suited to estimate the time varying distribution of carbon sources and sinks at the regional scale. We present here an analysis of two cross-European airborne campaigns that have been carried out on 23–26 May 2001 (CAATER 1 and 2–3 October 2002 (CAATER 2 over Western Europe. The area covered during CAATER 1 (respectively CAATER 2 was comprised between longitude 4° W to 14° E and latitude 44° N to 52° N (respectively longitude 1° E to 17° E and latitude 46° N to 52° N. High precision in-situ CO2, CO and Radon 222 measurements have been recorded. Flasks samples have been collected during both campaigns to cross-validate the in-situ data. During CAATER 1 (respectively CAATER 2, the mean CO2 concentration was 370.1±4 ppm (respectively 371.7±5 ppm. A HYSPLIT backtrajectories analysis shows that during CAATER 1, dominant winds were blowing from the north-west. In the planetary boundary layer (PBL airmasses got contaminated over Benelux and Western Germany by pollution from these high urbanized areas, reaching about 380 ppm. Air masses passing over rural areas are depleted in CO2 because of the photosynthesis activity of the land cover vegetation, as low as 355 ppm. During CAATER 2, the backtrajectory analysis shows that airmasses were distributed among the 4 sectors. Airmasses got enriched in CO2 and CO when passing above polluted spots in Germany but also in Poland, as these countries are known to hold part of the most polluting plants based on coal consumption, the so-called "dirty thirty" from WWF. Simultaneous measurements of in-situ CO2 and CO combined to backtrajectories helped us to discriminate the role of fossil fuel emissions from over CO2 sources. The ΔCO/ΔCO2 ratios (R2=0.33 to 0.88, slopes=2.42 to 10.37, calculated for polluted airmasses originating from different countries/regions, matched quite well national inventories, showing that the airborne measurements can

  20. Structural and electronic analysis of Li/Al layered double hydroxides and their adsorption for CO2

    Science.gov (United States)

    Hou, Xin-Juan; Li, Huiquan; He, Peng; Sun, Zhenhua; Li, Shaopeng

    2017-09-01

    The most stable structures and electronic properties of different Li/Al layered double hydroxides models (i.e., Li/Al-X, X = F-, Cl-, Br-, OH-, NO3-, CO32-, SO42-) and their hydrates, the adsorption of CO2 on Li/Al-X (X = Cl-, NO3-, CO32-) were ascertained by means of density functional theory. Results revealed that the planes of NO3- and CO32- are parallel with the layers in dehydrated state, although the plane of NO3- becomes vertical with the layers upon the introduction of water molecules. Electronic density analysis suggested that SO42- and CO32- significantly strengthens the reducibility of the Li/Al layered double hydroxides. The distribution of the frontier orbitals indicated the high reactivity of the anions and hydroxyl groups of the layers. The orders of the predicted stability are F- > Cl- > Br- > NO3- for the monovalent anions and SO42- > CO32- for the divalent anions. The calculated adsorption energies of CO2 in Li/Al-X (X = Cl-, NO3-, CO3-) supported the experimental observation that Li/Al-CO3 exhibits higher CO2 capture capacity than Li/Al-NO3 and Li/Al-Cl. Non-covalent interaction analysis indicated that the interactions among mineral surfaces, anions, water and CO2 are dominated by H-bonds, electrostatic interactions, and van der Waals forces. In addition, radial distribution functions were applied to provide insight for the interaction of water or CO2 with carbonate ion and hydroxyl layers.

  1. The Relative Performance of NDIR-based Sensors in the Near Real-time Analysis of CO2 in Air

    Directory of Open Access Journals (Sweden)

    Ki-Hyun Kim

    2007-09-01

    Full Text Available In this study, the reliability of NDIR-based sensors was explored by evaluatingthe comparability between measurement systems in the near real-time analysis of CO2. Forthis purpose, replicate analyses were performed using sensors of two different model types(H-550 and B-530, ELT Company, Korea. Three replicate data of each sensor typecollected continuously by side-by-side analysis in three second intervals (a duration of 304hour were evaluated for the relative performance of NDIR sensors. The reproducibility ofsensors, when assessed by relative standard error (RSE % values of all sensor units,showed moderate changes with time with the overall mean of 2.33%. When CO2measurements from all NDIR sensor units were evaluated by correlation analysis, theresults showed strong comparability, regardless of the model type. The overall results ofthis study suggest that NDIR sensors are reliable enough to produce highly comparabledata at least in a relative sense.

  2. Seasonal variation analysis of atmospheric CH4,N2O and CO2 in Tianjin offshore area

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The concentrations of CH4, N2O and CO2 at the sea level were observed from November 2007 to August 2008 in order to study the greenhouse gases in the Tianjin offshore area of Bohai Sea. CH4 concentrations varied from 1.87 to 2.61 ppm with the highest value appearing in summer and the lowest in winter. The concentration range of N2O was 319.3 to 347.7 ppb, with the maximal value appearing in winter. CO2 was higher in the heating season than in non-heating season in this area. Concentrations of the three greenhouse gases in the study area exceeded the 2005 global background values. Backward trajectory model was used to analyze the sources. All three gases were influenced evidently by continental sources in the inshore area during the sampling periods. Every gas was compared with each other by correlation analysis, showing that the correlation of CO2 and N2O was more significant than to CH4 and their relationship with meteorological factors was consistent. It can be concluded these three greenhouse gases may be influenced by some similar sources, especially for CO2 and N2O.

  3. CO2跨临界喷射制冷循环计算分析%Calculation and analysis on transcritical ejector refrigeration cycle with CO2

    Institute of Scientific and Technical Information of China (English)

    王菲; 杨勇; 沈胜强

    2013-01-01

    The research on transcritical ejector refrigeration cycle with CO2 is rarely reported.In this study,a thermodynamic model for a transcritical ejector refrigeration cycle is established.The changes of ejector entrainment ratio,the cycle performance coefficient (COP) and effective performance coefficient (COPm) with cooler pressure,cooler outlet temperature,heater pressure,heater outlet temperature and evaporation temperature are presented.As the cooler pressure increases,the entrainment ratio of ejector decrease,the cycle COP and COPm first increase and then decrease,with optimum values at some cooler pressures.As the outlet temperature of cooler increases,both values of COP and COPm decrease.With the increase of heater pressure,heater outlet temperature and evaporation temperature,the ejector entrainment ratio,the cycle COP and COPm are improved,while the cycle COP decreases with the increase of heater outlet temperature.%目前还很少有关于CO2跨临界喷射式制冷循环的研究.本文对CO2跨临界喷射制冷循环建立了热力学模型,计算了在不同的冷却压力、冷却器出口温度、加热器压力、加热器出口温度及蒸发温度下,喷射器的喷射系数、跨临界喷射制冷循环性能系数(COP)和有效性能系数(COPm)的变化趋势.结果表明:随着冷却器压力的升高,喷射器的喷射系数减小,循环的COP和COPm值先增大后减小,在某个冷却压力下存在最优值;提高冷却器的出口温度,循环的COP和COPm值均降低;提高加热器压力、加热器出口温度及蒸发温度均能增大喷射器的喷射系数和循环的COPm值.

  4. Variability and budget of CO2 in Europe: analysis of the CAATER airborne campaigns – Part 1: Observed variability

    Directory of Open Access Journals (Sweden)

    J. D. Paris

    2011-06-01

    Full Text Available Atmospheric airborne measurements of CO2 are very well suited for estimating the time-varying distribution of carbon sources and sinks at the regional scale due to the large geographical area covered over a short time. We present here an analysis of two cross-European airborne campaigns carried out on 23–26 May 2001 (CAATER-1 and 2–3 October 2002 (CAATER-2 over Western Europe. The area covered during CAATER-1 and CAATER-2 was 4° W to 14° E long; 44° N to 52° N lat and 1° E to 17° E long; 46° N to 52° N lat respectively. High precision in situ CO2, CO and Radon 222 measurements were recorded. Flask samples were collected during both campaigns to cross-validate the in situ data. During CAATER-1 and CAATER-2, the mean CO2 concentration was 370.1 ± 4.0 (1-σ standard deviation ppm and 371.7 ± 5.0 (1-σ ppm respectively. A HYSPLIT back-trajectories analysis shows that during CAATER 1, northwesterly winds prevailed. In the planetary boundary layer (PBL air masses became contaminated over Benelux and Western Germany by emissions from these highly urbanized areas, reaching about 380 ppm. Air masses passing over rural areas were depleted in CO2 because of the photosynthesis activity of the vegetation, with observations as low as 355 ppm. During CAATER-2, the back-trajectory analysis showed that air masses were distributed among the 4 sectors. Air masses were enriched in CO2 and CO over anthropogenic emission spots in Germany but also in Poland, as these countries have part of the most CO2-emitting coal-based plants in Europe. Simultaneous measurements of in situ CO2 and CO combined with back-trajectories helped us to distinguish between fossil fuel emissions and other CO2 sources. The ΔCO/ΔCO2 ratios (R2 = 0.33 to 0.88, slopes = 2.42 to 10.37, calculated for anthropogenic-influenced air masses over different countries/regions matched national inventories quite well, showing that airborne measurements can help to identify the origin of

  5. Failure Mode and Effects Analysis of CO2 Gas Shield Welding%CO2气保焊的故障模式与影响分析

    Institute of Scientific and Technical Information of China (English)

    王余海

    2012-01-01

    Welding is a main operating process in the manufacturing of pressure vessels for commercial air- conditions. During processing, CO2 gas shield welding is mainly used, especially for fabrication of evaporators and condensers. In the actual production process, leakage faults caused by welding seriously affect the quality of prod- ucts, so it needs to optimize the welding parameters by experimental design method. However, there are. many fac- tors that affect the welds quality, so it is necessary to analyze the failure modes by FMEA before parameters de- sign to make the factors selection more accurate and effective, and pick out the key factors.%焊接是商用空调设备压力容器制造过程中的主要操作工序。CO2气体保护焊主要在蒸发器、冷凝器的装配过程中被使用。在实际生产过程中,焊接造成的故障泄漏严重影响产品质量,需要使用试验设计方法对焊接参数进行优化.但影响焊缝质量的因素众多,在进行参数设计之前,为使因素选择更准确、有效,使用FMEA(failure mode effects analysis)方法对气保焊故障模式进行分析,从中选择出关键因素。

  6. Analysis of alternative push-pull-test-designs for determining in-situ trapping of CO2

    Science.gov (United States)

    Rasmusson, M.; Rasmusson, K.; Fagerlund, F.; Niemi, A.; Bensabat, J.; Shtivelman, V.

    2012-04-01

    Modeling results of different single-well push-pull (injection-withdrawal) test designs have been analyzed for their ability to determine residual and dissolution trapping of CO2 in-situ. The modeling aims to improve the design of a CO2 push-pull test that will be part of the field experiment conducted at the Heletz site, Israel, within the EU FP7 MUSTANG project. The injection will take place in a saline formation, where the target layer, an about 10 m thick sandstone layer composed of three layers, is located at a depth of 1600 m. Single-well experiments complement two-well injection-monitoring tests in that they offer a way of reducing heterogeneity effects on CO2 transport in comparison to two-well tests. The test scenarios simulated combine thermal, hydraulic and tracer tests in line with the work by Zhang et al (2011), where the test sequences have three main stages divided into (i) reference tests, (ii) creation of a zone of residual gas saturation and (iii) testing during residual gas saturation conditions. One of the main interests is to compare different ways of creating the residual zone, the two principal approaches being to push the mobile CO2 away by injecting CO2 saturated water, thus leaving the residual zone behind or by pumping the mobile CO2 back. Implications of the different designs on optimal use of tracers are also analyzed. Inverse modeling with the iTOUGH2/EOS17 and EOS7c simulators is used to analyze the ability of the competing test designs to accurately determine parameters of main interest during CO2 sequestration, in particular the residual gas saturation and dissolution. The inverse modeling approach uses results from e.g. sensitivity analysis and uncertainty propagation analysis to make design decisions leading to improvements in the test scenarios, choosing the optimum pumping and injection rates, heating effects, amount of CO2 used, tracer and method to create the zone of residual CO2 trapping, leading to a test design that will

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

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vinod

    2013-07-13

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

  8. 3D seismic analysis of the Collyhurst Sandstone: implications for CO2 sequestration in the East Irish Sea Basin

    Science.gov (United States)

    Gamboa, Davide; Williams, John; Kirk, Karen; Gent, Christopher; Bentham, Michelle; Fellgett, Mark; Schofield, David

    2016-04-01

    Carbon Capture and Storage (CCS) is a vital technology towards low-carbon energy resources and the mitigation of global warming trends induced by rising CO2 levels in the atmosphere. The East Irish Sea Basin (EISB) is a key area for CCS in the western UK, having high CO2 storage potentials in explored hydrocarbon fields and in saline aquifers within the Permo-Triassic Sherwood Sandstone Formation. However, the theoretical storage potential of the EISB could be poorly estimated as the reservoir-prone Lower Permian formations are not considered in detail by current estimations. This work aims to fill this gap, focusing on the characterisation of the Lower Permian Collyhurst Sandstone Formation as a viable storage unit. The potential for CO2 storage is estimated as the total volume/area of suitable closures that are isolated by structural traps, occurring at depths suitable for CO2 injection and containment (>800m). Detailed structural and stratigraphic interpretations were made using 3D seismic data to assess the storage potential of the Collyhurst Sandstone Formation in the southern EISB. The basin strata is compartmentalised by numerous N-S trending faults. A higher degree of compartmentalisation occurs within regional anticlines where elongated tilted blocks are observed, bound by predominantly west-dipping faults that induce a variable offset of the Collyhurst Sandstone strata. Contrastingly, higher lateral continuity of this formation is observed within graben basins were faults are less frequent and with minor offset, thus potentially creating larger storage closures. Fault dip orientation in the grabens is variable, with west and east dipping faults occurring as a function of large east-dipping listric faults. This study was complemented by the stress modelling of the interpreted faults in order to assess the risk of CO2 leakage. Analysis of borehole breakouts observed in four approximately vertical wells in the EISB suggest a maximum horizontal stress

  9. A contribution to risk analysis for leakage through abandoned wells in geological CO2 storage

    DEFF Research Database (Denmark)

    Kopp, Andreas; Binning, Philip John; Johannsen, K.;

    2010-01-01

    reservoir database, holding data from over 1200 reservoirs An analytical risk equation is given, allowing the calculation of average risk due to multiple leaky wells with varying distance in the surrounding of the injection well. The reservoir parameters most affecting risk are identified. Using...... these results, the placement of an injection well can be optimized with respect to risk and uncertainty of leakage The risk and uncertainty assessment can be used to determine whether a site, compared to others, should be considered for further investigations or rejected for CO2 storage...

  10. [A comparative analysis of tonsillectomy and ablation of the palatine tonsils with CO2 laser].

    Science.gov (United States)

    Zbyshko, Ia B

    2007-01-01

    Efficacy and toletance of two methods were compared: ablation of the palatine tonsils with CO2 laser and tonsillectomy. 270 case histories (118 after tonsillectomy and 152 after laser ablation of the palatine tonsils) have been analysed and 50 patients from each group have been examined. The comparison of the methods leads to conclusion that laser ablation of the palatine tonsils prevents intraoperative and postoperative complications; makes postoperative hemostatic therapy unnecessary; allows conduction of the operations in outpatient clinics or day hospitals; causes minimal pain in the postoperative period; shortens duration of disability.

  11. Energetic, Exergetic and Exergoeconomic Analysis of CO2 Refrigeration Systems Operating in Hot Climates

    DEFF Research Database (Denmark)

    Gullo, Paride; Elmegaard, Brian; Cortella, Giovanni

    2015-01-01

    of the product of a R744 refrigeration solution with auxiliary compressor with those of a R744 conventional system, both of them operating in transcritical conditions. The results pointed out that the adoption of an auxiliary compressor resulted in an increase of the COP by approximately 18.7% over...... conditions. CO2 refrigeration system with parallel compression represents one of the solutions which have been proposed in the last few years in order to enhance the performance of a single-stage refrigeration system. The main target of this study is to compare the thermodynamic efficiency and the final cost...

  12. Enantioselective stable isotope analysis (ESIA) of polar Herbicides

    Science.gov (United States)

    Maier, Michael; Qiu, Shiran; Elsner, Martin

    2013-04-01

    The complexity of aquatic systems makes it challenging to assess the environmental fate of chiral micropolutants. As an example, chiral herbicides are frequently detected in the environment (Buser and Muller, 1998); however, hydrological data is needed to determine their degradability from concentration measurements. Otherwise declining concentrations cannot unequivocally be attributed to degradation, but could also be caused by dilution effects. In contrast, isotope ratios or enantiomeric ratios are elegant alternatives that are independent of dilution and can even deliver insights into reaction mechanisms. To combine the advantages of both approaches we developed an enatioselective stable isotope analysis (ESIA) method to investigate the fate of the chiral herbicides 4-CPP ((RS)-2-(4-chlorophenoxy)-propionic acid), mecoprop (2-(4-Chloro-2-methylphenoxy)-propionic acid) and dichlorprop (2-(2,4-Dichlorophenoxy)-propionic acid). After testing the applicable concentration range of the method, enantioselective isotope fractionation was investigated by microbial degradation using dichlorprop as a model compound. The method uses enantioselective gas-chromatography (GC) to separate enantiomers. Subsequently samples are combusted online to CO2 and carbon isotope ratios are determined for each enantiomer by isotope-ratio-mass-spectrometry (IRMS). Because the analytes contain a polar carboxyl-group, samples were derivatised prior to GC-IRMS analysis with methanolic BF3 solution. Precise carbon isotope analysis (2σ ≤0.5‰) was achieved with a high sensitivity of ≥ 7 ng C that is needed on column for one analysis. Microbial degradation of the model compound dichlorprop was conducted with Delftia acidovorans MC1 and pronounced enantiomer fractionation, but no isotope fractionation was detected. The absence of isotope fractionation can be explained by two scenarios: either the degrading enzyme has no isotopic preference, or another step in the reaction without an isotopic

  13. Analysis of the Damage Mechanism Related to CO2 Laser Cochleostomy on Guinea Pig Cochlea

    Directory of Open Access Journals (Sweden)

    Xiang Liu

    2016-01-01

    Full Text Available Different types of lasers have been used in inner ear surgery. Therefore, it is of the utmost importance to avoid damage to the inner ear (e.g., hyperthermia and acoustic effects caused by the use of such lasers. The aim of this study was to use a high powered fibre-enabled CO2 laser (10 W, 606 J/cm2 to perform cochleostomies on guinea pig cochlea and to investigate the possible laser-induced damage mechanisms. The temperature changes in the round window membrane, auditory evoked brainstem response, and morphological of the hair cells were measured and recorded before and after laser application. All of the outcomes differed in comparison with the control group. A rise in temperature and subsequent increased hearing loss were observed in animals that underwent surgery with a 10 W CO2 laser. These findings correlated with increased injury to the cochlear ultrastructure and a higher positive expression of E-cadherin and β-catenin in the damaged organ of Corti. We assume that enhanced cell-cell adhesion and the activated β-catenin-related canonical Wnt-signalling pathway may play a role in the protection of the cochlea to prevent further damage.

  14. Analysis of the Global Warming Potential of Biogenic CO2 Emission in Life Cycle Assessments

    Science.gov (United States)

    Liu, Weiguo; Zhang, Zhonghui; Xie, Xinfeng; Yu, Zhen; von Gadow, Klaus; Xu, Junming; Zhao, Shanshan; Yang, Yuchun

    2017-01-01

    Biomass is generally believed to be carbon neutral. However, recent studies have challenged the carbon neutrality hypothesis by introducing metric indicators to assess the global warming potential of biogenic CO2 (GWPbio). In this study we calculated the GWPbio factors using a forest growth model and radiative forcing effects with a time horizon of 100 years and applied the factors to five life cycle assessment (LCA) case studies of bioproducts. The forest carbon change was also accounted for in the LCA studies. GWPbio factors ranged from 0.13–0.32, indicating that biomass could be an attractive energy resource when compared with fossil fuels. As expected, short rotation and fast-growing biomass plantations produced low GWPbio. Long-lived wood products also allowed more regrowth of biomass to be accounted as absorption of the CO2 emission from biomass combustion. The LCA case studies showed that the total life cycle GHG emissions were closely related to GWPbio and energy conversion efficiency. By considering the GWPbio factors and the forest carbon change, the production of ethanol and bio-power appeared to have higher GHG emissions than petroleum-derived diesel at the highest GWPbio. PMID:28045111

  15. Analysis of the Global Warming Potential of Biogenic CO2 Emission in Life Cycle Assessments

    Science.gov (United States)

    Liu, Weiguo; Zhang, Zhonghui; Xie, Xinfeng; Yu, Zhen; von Gadow, Klaus; Xu, Junming; Zhao, Shanshan; Yang, Yuchun

    2017-01-01

    Biomass is generally believed to be carbon neutral. However, recent studies have challenged the carbon neutrality hypothesis by introducing metric indicators to assess the global warming potential of biogenic CO2 (GWPbio). In this study we calculated the GWPbio factors using a forest growth model and radiative forcing effects with a time horizon of 100 years and applied the factors to five life cycle assessment (LCA) case studies of bioproducts. The forest carbon change was also accounted for in the LCA studies. GWPbio factors ranged from 0.13–0.32, indicating that biomass could be an attractive energy resource when compared with fossil fuels. As expected, short rotation and fast-growing biomass plantations produced low GWPbio. Long-lived wood products also allowed more regrowth of biomass to be accounted as absorption of the CO2 emission from biomass combustion. The LCA case studies showed that the total life cycle GHG emissions were closely related to GWPbio and energy conversion efficiency. By considering the GWPbio factors and the forest carbon change, the production of ethanol and bio-power appeared to have higher GHG emissions than petroleum-derived diesel at the highest GWPbio.

  16. Analysis of the Global Warming Potential of Biogenic CO2 Emission in Life Cycle Assessments.

    Science.gov (United States)

    Liu, Weiguo; Zhang, Zhonghui; Xie, Xinfeng; Yu, Zhen; von Gadow, Klaus; Xu, Junming; Zhao, Shanshan; Yang, Yuchun

    2017-01-03

    Biomass is generally believed to be carbon neutral. However, recent studies have challenged the carbon neutrality hypothesis by introducing metric indicators to assess the global warming potential of biogenic CO2 (GWPbio). In this study we calculated the GWPbio factors using a forest growth model and radiative forcing effects with a time horizon of 100 years and applied the factors to five life cycle assessment (LCA) case studies of bioproducts. The forest carbon change was also accounted for in the LCA studies. GWPbio factors ranged from 0.13-0.32, indicating that biomass could be an attractive energy resource when compared with fossil fuels. As expected, short rotation and fast-growing biomass plantations produced low GWPbio. Long-lived wood products also allowed more regrowth of biomass to be accounted as absorption of the CO2 emission from biomass combustion. The LCA case studies showed that the total life cycle GHG emissions were closely related to GWPbio and energy conversion efficiency. By considering the GWPbio factors and the forest carbon change, the production of ethanol and bio-power appeared to have higher GHG emissions than petroleum-derived diesel at the highest GWPbio.

  17. The Analysis of CO2 Emissions and Reduction Potential in China’s Transport Sector

    Directory of Open Access Journals (Sweden)

    Wei Li

    2016-01-01

    Full Text Available China’s transport sector is responsible for approximately 10% of national CO2 emissions. In the process of industrialization and urbanization of China, emissions from transport sector would continuously increase. In order to investigate the emissions and reduction potential and provide the policy guidance for policymakers in China’s transport sector, this study decomposed the CO2 emissions using the Kaya identity, calculated the contribution based on the Logarithmic Mean Divisia Index (LMDI method to explore the underlying determinants of emissions change, and then constructed different scenarios to predict the emissions and estimate the potential of emission reduction in the future. Results indicated that carbon emissions in China’s transport sector have increased from 123.14 Mt in 1995 to 670.76 Mt in 2012. Income effect is the dominant factor that results in the increase of emissions while energy intensity effect is the main driving force to lower carbon emissions. The transportation modal shifting, transportation intensity change, and population growth have the positive but relatively minor impact on emissions. The accumulated emission reduction is expected to be 1825.97 Mt, which is 3 times more than the emissions in 2010. Policy recommendations are thus put forward for future emission reduction.

  18. Metal-Assisted Laser-Induced Gas Plasma for the Direct Analysis of Powder Using Pulse CO2 Laser

    Science.gov (United States)

    Khumaeni, A.; Lie, Z. S.; Kurniawan, K. H.; Kagawa, K.

    2017-01-01

    Analysis of powder samples available in small quantities has been carried out using metal-assisted gas plasma by utilizing a transversely excited atmospheric (TEA) CO2 laser. The powder was homogeneously mixed with Si grease, and the mixed powder was painted on a metal subtarget. When a TEA CO2 laser was directly focused on the metal subtarget at atmospheric pressure of He gas, a high-temperature He gas plasma was induced. It is assumed that the powder particles were vaporized to be effectively atomized and excited in the gas plasma region. This method has been employed in the rapid analyses of elements in organic and inorganic powder samples present in small quantities. Detection of trace elements of Cr and Pb has been successfully made by using the supplement powder and loam soil, respectively. The detection limits of Pb in loam soil were approximately 20 mg/kg.

  19. Analysis of energy use and CO2 emissions in the U.S. refining sector, with projections for 2025.

    Science.gov (United States)

    Hirshfeld, David S; Kolb, Jeffrey A

    2012-04-03

    This analysis uses linear programming modeling of the U.S. refining sector to estimate total annual energy consumption and CO(2) emissions in 2025, for four projected U.S. crude oil slates. The baseline is similar to the current U.S. crude slate; the other three contain larger proportions of higher density, higher sulfur crudes than the current or any previous U.S. crude slates. The latter cases reflect aggressive assumptions regarding the volumes of Canadian crudes in the U.S. crude slate in 2025. The analysis projects U.S. refinery energy use 3.7%-6.3% (≈ 0.13-0.22 quads/year) higher and refinery CO(2) emissions 5.4%-9.3% (≈ 0.014-0.024 gigatons/year) higher in the study cases than in the baseline. Refining heavier crude slates would require significant investments in new refinery processing capability, especially coking and hydrotreating units. These findings differ substantially from a recent estimate asserting that processing heavy oil or bitumen blends could increase industry CO(2) emissions by 1.6-3.7 gigatons/year.

  20. Thermodynamic analysis of gas – steam combined cycle with carbon dioxide (CO2 emissions saving

    Directory of Open Access Journals (Sweden)

    Alka Gupta, Om Prakash, S.K. Shukla

    2011-03-01

    Full Text Available In this paper, cogeneration or combined heat and power (CHP cycle has been analyzed in order to improve the efficiency of the gas – steam combined cycle and utilization of waste heat. The efficiency of the combined cycle is improved by decreasing the compressor inlet temperature (CIT and increasing the turbine inlet temperature (TIT. It is observed that the cycle offers the advantage of making efficient use of the energy available in the fuel and in turn, eliminate some portion of pollution associated with the power generation. The study also reveals that if this cycle is being employed for cogeneration, there is a significant saving (11.60% in the amount of Carbon dioxide (CO2 emitted by the coal-fired thermal power plants.

  1. Renewable Energies and CO2 Cost Analysis, Environmental Impacts and Technological Trends- 2012 Edition

    CERN Document Server

    Guerrero-Lemus, Ricardo

    2013-01-01

    Providing up-to-date numerical data across a range of topics related to renewable energy technologies, Renewable Energies and CO2 offers a one-stop source of key information to engineers, economists and all other professionals working in the energy and climate change sectors. The most relevant up-to-date numerical data are exposed in 201 tables and graphs, integrated in terms of units and methodology, and covering topics such as energy system capacities and lifetimes, production costs, energy payback ratios, carbon emissions, external costs, patents and literature statistics. The data are first presented and then analyzed to project potential future grid, heat and fuel parity scenarios, as well as future technology tendencies in different energy technological areas. Innovative highlights and descriptions of preproduction energy systems and components from the past four years have been gathered from selected journals and international energy departments from G20 countries. As the field develops, readers are in...

  2. Rock Physics Analysis for the Characterization of the Geological CO2 Storage Prospect in Southwestern Ulleung Basin, Korea

    Science.gov (United States)

    Min, G.; Han, J.; Lee, M.; Keehm, Y.

    2014-12-01

    We performed rock physical analysis for the characterization of the CO2 storage site in Ulleung basin, Korea. We obtained the characteristics of target formation from the previous work, which contains comprehensive analyses on key horizons and stratigraphy. After verifying the previous work with well-log data, we performed rock physics modeling to obtain the interrelations between reservoir properties and seismic property for key units, such as shale volume-impedance and porosity-impedance relations. We applied the relations to inverted acoustic impedance from 3D seismic data, and obtained 3D distribution maps for shale volume and porosity. We found around 10-meter-thick cap rock unit (Unit 2-3) and two reservoir units (Unit 3-1 & 3-2) with thickness of a few hundred meters. Unit 2-3 has consistently high shale volume throughout the study area, which implies that it can be a good cap rock. Unit 3-1 and 3-2 seem to be good reservoir layers and their average sand thicknesses are 60 m and 150 m, respectively. From this preliminary analysis, the pore volume of the sand intervals of two reservoirs units is estimated to be 20 billion cubic meters. If we assume that one percent of sand pore volume can be replaced by injected CO2, the injectable amount of CO2 would be 136 million metric tonne. Acknowledgements: This work was supported by "Development of Technology for CO2 Marine Geological Storage" funded by the Ministry of Oceans and Fisheries, Korea (No. 20052004), and "Energy Efficiency & Resources of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant" funded by the Ministry of Trade, Industry & energy (No. 20132010201760).

  3. Development of high through-put Sr isotope analysis for monitoring reservoir integrity for CO{sub 2} storage.

    Energy Technology Data Exchange (ETDEWEB)

    Wall, Andy; Jain, Jinesh; Stewart, Brian; Capo, Rosemary; Hakala, Alexandra J.; Hammack, Richard; Guthrie, George

    2012-01-01

    Recent innovations in multi-collector ICP-mass spectrometry (MC-ICP-MS) have allowed for rapid and precise measurements of isotope ratios in geological samples. Naturally occurring Sr isotopes has the potential for use in Monitoring, Verification, and Accounting (MVA) associated with geologic CO2 storage. Sr isotopes can be useful for: Sensitive tracking of brine migration; Determining seal rock leakage; Studying fluid/rock reactions. We have optimized separation chemistry procedures that will allow operators to prepare samples for Sr isotope analysis off site using rapid, low cost methods.

  4. Evidence of the chemical reaction of (18)O-labelled nitrite with CO2 in aqueous buffer of neutral pH and the formation of (18)OCO by isotope ratio mass spectrometry.

    Science.gov (United States)

    Tsikas, Dimitrios; Böhmer, Anke; Gros, Gerolf; Endeward, Volker

    2016-05-01

    Inorganic nitrite (NO2(-), ON-O(-) ←→ (-)O-NO) is the autoxidation product of nitric oxide (NO). Nitrite can also be formed from inorganic nitrate (ONO2(-)), the major oxidation product of NO in erythrocytes, by the catalytic action of bacterial nitrate reductase in gut and oral microflora. Nitrite can be reduced to NO by certain cellular proteins and enzymes, as well as in the gastric juice under acidic conditions. Hemoglobin, xanthine oxidoreductase and carbonic anhydrase (CA) have been reported to convert nitrite to NO. Renal CA isoforms are involved in the reabsorption of nitrite and may, therefore, play an important role in NO homeostasis. Yet, the mechanisms underlying the action of CA on nitrite are incompletely understood. The nitrate/nitrite system is regarded as a reservoir of NO. We have recently shown that nitrite reacts chemically with carbon dioxide (CO2), the regular substrate of CA. The present communication reports a stable isotope ratio mass spectrometry (IRMS) study on the reaction of NO2(-) and CO2 performed in 50 mM HEPES buffer of pH 7.4 at 37 °C. By using (18)O-labelled nitrite ((18)ON-O(-)/(-18)O-NO) and CO2 we observed formation of (18)O-labelled CO2. This finding is an unequivocal evidence of the chemical reaction of (18)ON-O(-)/(-18)O-NO with CO2. The reaction is rapid and involves nucleophilic attack of the negatively charged nitrite via one of its oxygen atoms on the partially positively charged CO2 molecule to form the putative intermediate (18)ON-O-CO2(-)/(-)O2C-(18)O-NO. The by far largest fraction of this intermediate decomposes back to (18)ON-O(-)/(-18)O-NO and CO2. A very small fraction of the intermediate, however, rearranges and finally decomposes to form (18)OCO and nitrite. This reaction is slower in the presence of an isolated erythrocytic CA isoform II. In summary, NO2(-), CO2 and CA are ubiquitous. The chemical reaction of NO2(-) with CO2 and its modulation by CA isoforms may play important roles in the transport of

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

    Science.gov (United States)

    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.

  6. Online CO2 and H2 O oxygen isotope fractionation allows estimation of mesophyll conductance in C4 plants, and reveals that mesophyll conductance decreases as leaves age in both C4 and C3 plants.

    Science.gov (United States)

    Barbour, Margaret M; Evans, John R; Simonin, Kevin A; von Caemmerer, Susanne

    2016-05-01

    Mesophyll conductance significantly, and variably, limits photosynthesis but we currently have no reliable method of measurement for C4 plants. An online oxygen isotope technique was developed to allow quantification of mesophyll conductance in C4 plants and to provide an alternative estimate in C3 plants. The technique is compared to an established carbon isotope method in three C3 species. Mesophyll conductance of C4 species was similar to that in the C3 species measured, and declined in both C4 and C3 species as leaves aged from fully expanded to senescing. In cotton leaves, simultaneous measurement of carbon and oxygen isotope discrimination allowed the partitioning of total conductance to the chloroplasts into cell wall and plasma membrane versus chloroplast membrane components, if CO2 was assumed to be isotopically equilibrated with cytosolic water, and the partitioning remained stable with leaf age. The oxygen isotope technique allowed estimation of mesophyll conductance in C4 plants and, when combined with well-established carbon isotope techniques, may provide additional information on mesophyll conductance in C3 plants.

  7. Economic analysis and effectiveness evaluation on China's CO2 emission mitigation target%我国CO2减排目标的经济学分析与效果评价

    Institute of Scientific and Technical Information of China (English)

    何建坤

    2011-01-01

    The paper derives and calculates the mutual relations among the CO2 emissions mitigation factors, such as the reduction rate of GDP CO2 emissions intensity, the reduction rate of GDP energy intensity, the reduction rate of C02 intensity of energy consumption,and the increase rate of non - fossil energy share in primary energy consumption, and then analyzes the factors of Chinas GDP energy intensity reduction from 1990 to 2005. it shows that the contribution rate of technical energy saving was about 56% , while the contribution rate of structural energy saving was about 44%. The scenario analysis from 2005 to 2020 illustrate that the contribution rate of technical energy saving and structural energy saving will be 43% and 37% respectively, while the contribution rate of energy supply structure change will be 20% , and the renewable energy and advanced nuclear power technology development can play an increasingly important role in the reduction of GDP C02 intensity.%就GDP的CO2排放强度下降率、GDP能源强度下降率、能源消费的CO2排放因子下降率、非化石能源在能源品种构成中增长率等影响减缓CO2排放的因素间的相互关系进行了数学推导和计算,进而测算了我国从1990-2005年GDP能源强度下降的影响因素中,技术节能的贡献率约为56%,而结构节能的贡献率44%.2005~2020年情景分析方案中,对促进GDP的CO2强度下降的贡献因素中,技术节能约为43%,结构节能约为37%,而能源结构改善的贡献率也可达20%,可再生能源和先进核能技术的发展对未来减缓CO2排放将起越来越重要的作用.同时文中还分析了CO2排放实现零增长和负增长目标时各项相关指标需达到的条件.

  8. Analysis of ΔO2/ΔCO2 ratios for the pollution events observed at Hateruma Island, Japan

    Directory of Open Access Journals (Sweden)

    S. Maksyutov

    2012-03-01

    Full Text Available Pollution events extracted from the in situ observations of atmospheric CO2 and O2 mixing ratios at Hateruma Island (HAT, 24° N, 124° E during the period from October 2006 and December 2008 are examined. The air mass origins for the pollution events are categorized by using back trajectory analysis, and the oxidative ratios (OR = −O2:CO2 molar exchange ratio for selected pollution events are calculated. We find that there is a significant difference in the average oxidative ratios between events from China (OR = 1.14 ± 0.12, n = 25 and Japan/Korea (OR = 1.37 ± 0.15, n = 16. These values are in a good agreement with the national average oxidative ratios for the emissions from fossil fuel burning and cement production (FFBC in China (ORFFBC = 1.11 ± 0.03 and Korea/Japan (ORFFBC = 1.36 ± 0.02. Compared with the observation, simulations of the atmospheric O2 and CO2 mixing ratios using Lagrangian particle dispersion models do a good job in reconstructing the average oxidative ratio of the pollution events originating in China but tend to underestimate for events originating in Japan/Korea. A sensitivity test suggests that the simulated atmospheric oxidative ratios at HAT are especially sensitive to changes in Chinese fuel mix.

  9. Harmonic scalpel versus flexible CO2 laser for tongue resection: A histopathological analysis of thermal damage in human cadavers

    Directory of Open Access Journals (Sweden)

    Wolf Tamir

    2011-08-01

    Full Text Available Abstract Background Monopolar cautery is the most commonly used surgical cutting and hemostatic tool for head and neck surgery. There are newer technologies that are being utilized with the goal of precise cutting, decreasing blood loss, reducing thermal damage, and allowing faster wound healing. Our study compares thermal damage caused by Harmonic scalpel and CO2 laser to cadaveric tongue. Methods Two fresh human cadaver heads were enrolled for the study. Oral tongue was exposed and incisions were made in the tongue akin to a tongue tumor resection using the harmonic scalpel and flexible C02 laser fiber at various settings recommended for surgery. The margins of resection were sampled, labeled, and sent for pathological analysis to assess depth of thermal damage calculated in millimeters. The pathologist was blinded to the surgical tool used. Control tongue tissue was also sent for comparison as a baseline for comparison. Results Three tongue samples were studied to assess depth of thermal damage by harmonic scalpel. The mean depth of thermal damage was 0.69 (range, 0.51 - 0.82. Five tongue samples were studied to assess depth of thermal damage by CO2 laser. The mean depth of thermal damage was 0.3 (range, 0.22 to 0.43. As expected, control samples showed 0 mm of thermal damage. There was a statistically significant difference between the depth of thermal injury to tongue resection margins by harmonic scalpel as compared to CO2 laser, (p = 0.003. Conclusion In a cadaveric model, flexible CO2 laser fiber causes less depth of thermal damage when compared with harmonic scalpel at settings utilized in our study. However, the relevance of this information in terms of wound healing, hemostasis, safety, cost-effectiveness, and surgical outcomes needs to be further studied in clinical settings.

  10. Stability analysis of the martensitic phase transformation in Co2NiGa Heusler alloy

    Science.gov (United States)

    Talapatra, Anjana; Arróyave, Raymundo; Entel, Peter; Valencia-Jaime, I.; Romero, Aldo H.

    2015-08-01

    Phase competition and the subsequent phase selection are important characteristics of alloy systems exhibiting numerous states of distinct symmetry but comparable energy. The stoichiometric Co2NiGa Heusler alloy exhibits a martensitic transformation with concomitant reduction in symmetry from an austenitic L 21 phase (cubic) to a martensitic L 10 phase (tetragonal). A structural search was carried out for this alloy and it showed the existence of a number of structures with monoclinic and orthorhombic symmetry with ground state energies comparable to and even less than that of the L 10 structure, usually reported as the ground state at low temperatures. We describe these structures and focus in particular on the structural transition path from the L 21 to tetragonal and orthorhombic structures for this material. Calculations were carried out to study the Bain (L 21-L 10 ) and Burgers (L 21-hcp ) transformations. The barrierless Burgers path yielded a stable martensitic phase with orthorhombic symmetry (O ) with energy much lower—beyond the expected uncertainty of the calculation methods—than the known tetragonal L 10 martensitic structure. This low-energy structure (O ) has yet to be observed experimentally and it is thus of scientific interest to discern the cause for the apparent discrepancy between experiments and calculations. It is postulated that the Co2NiGa Heusler system exhibits a classic case of the phase selection problem: although the unexpected O phase may be relatively more stable than the L 10 phase, the energy barrier for the (L 21-O ) transformation may be much higher than the barrier to the (L 21-L 10 ) transformation. To validate this hypothesis, the stability of this structure was investigated by considering the contributions of elastic and vibrational effects, configurational disorder, magnetic disorder, and atomic disorder. The calculations simulating the effect of magnetic disorder/high temperature as well as the atomic disorder

  11. Coupled Multi-physics analysis of Caprock Integrity and Fault Reactivation during CO2 Sequestration*

    Science.gov (United States)

    Newell, P.; Martinez, M. J.; Bishop, J.

    2012-12-01

    Structural/stratigraphic trapping beneath a low-permeable caprock layer is the primary trapping mechanism for long-term subsurface sequestration of CO2. Pre-existing fracture networks, injection induced fractures, and faults are of concern for possible CO2 leakage both during and after injection. In this work we model the effects of both caprock jointing and a fault on the caprock sealing integrity during various injection scenarios. The modeling effort uses a three-dimensional finite-element based coupled multiphase flow and geomechanics simulator. The joints within the caprock are idealized as equally spaced and parallel. Both the mechanical and flow behavior of the joint network are treated within an effective continuum formulation. The mechanical behavior of the joint network is linear elastic in shear and nonlinear elastic in the normal direction. The flow behavior of the joint network is treated using the classical cubic-law relating flow rate and aperture. The flow behavior is then upscaled to obtain an effective permeability. The fault is modeled as a finite-thickness layer with multiple joint sets. The joint sets within the fault region are modeled following the same mechanical and flow formulation as the joints within the caprock. Various injection schedules as well as fault and caprock jointing configurations within a proto-typical sequestration site have been investigated. The resulting leakage rates through the caprock and fault are compared to those assuming intact material. The predicted leakage rates are a strong nonlinear function of the injection rate. *This material is based upon work supported as part of the Center for Frontiers of Subsurface Energy Security, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001114. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of

  12. Flow regime analysis for fluid injection into a confined aquifer: implications for CO2 sequestration

    Science.gov (United States)

    Guo, B.; Zheng, Z.; Celia, M. A.; Stone, H.

    2015-12-01

    Carbon dioxide injection into a confined saline aquifer may be modeled as an axisymmetric two-phase flow problem. Assuming the two fluids segregate in the vertical direction due to strong buoyancy, and neglecting capillary pressure and miscibility, the lubrication approximation leads to a nonlinear advection-diffusion equation that describes the evolution of the sharp fluid-fluid interface. The flow behaviors in the system are controlled by two dimensionless groups: M, the viscosity ratio of the displaced fluid relative to injected fluid, and Γ , the gravity number, which represents the relative importance of buoyancy and fluid injection. Four different analytical solutions can be derived as the asymptotic approximations, representing specific values of the parameter pairs. The four solutions correspond to: (1) Γ 1; and (4) Γ >> 1, any M values. The first two of these solutions are new, while the third corresponds to the solution of Nordbotten and Celia (2006) for confined injections and the fourth corresponds to the solution of (Lyle et al., 2005) for gravity currents in an unconfined aquifer. Overall, the various axisymmetric flows can be summarized in a Γ-M regime diagram with five distinct dynamic behaviors including the four asymptotic regimes and an intermediate regime (Fig. 1). Data from a number of CO2 injection sites around the world can be used to compute the two dimensionless groups Γ and M associated with each injection. When plotted on the regime diagram, these values show the flow behavior for each injection and how the values vary from site to site. For all the CO2 injections, M is always larger than 1, while Γ can range from 0.01 up to 100. The pairs of (Γ, M) with lower Γ values correspond to solution (3), while the ones with higher Γ values can move up to the intermediate regime and the flow regime for solution (4). The higher values of Γ correspond to pilot-scale injections with low injection rates; most industrial-scale injection

  13. Effect of CO2 Poison on the Surface Phase and the Hydrogen Isotope Permeation Capacity of Pd Membrane%CO2毒化对Pd膜表面状态与氢同位素渗透性能的影响

    Institute of Scientific and Technical Information of China (English)

    冯成; 刘颖; 连利仙; 彭丽霞; 李军; 饶永初

    2011-01-01

    The poison of Pd membrane in CO2 at different temperatures and the hydrogenization of the poisoned membrane were carried out in a silica tubular furnace and the hydrogen isotope permeation capacity was tested. The variation of Pd membrane phase and morphology was analyzed and observed by XPS and SEM. The cause and the mechanism of the variation were discussed. The results show that the molecule CO2 will dissociate to C=O, C-O and O on Pd membrane surface. The adsorptive capacity of C-O and O increases and that of C=O decreases with increasing of the temperature. PdO and micropores can be detected apparently when the poison temperature reaches 500 °C, and C-O will be adsorbed on Pd membrane surface firmly. After hydrogenization, the PdO, C-O and free O on the Pd surface vanish while C=O reappear. After the Pd membrane is poisoned by CO2, the hydrogen isotope permeation capacity of Pd membrane decreases because the atom O and C-O occupy H site and react with atom H easily.%在不同温度的CO2气氛中对Pd膜进行了毒化,将毒化后的Pd膜与氢气反应并测试其氢同位素渗透性能.采用XPS、SEM等检测了CO2在不同温度下对Pd膜毒化后的表面成分与形貌,并对比分析了吸氢前、后的Pd膜表面状态的变化,得出了CO2对Pd膜表面状态的影响规律,探讨了CO2气体的毒化机理.结果表明,CO2分子在Pd表面会解离成为C=O,C-O与O原子,随着温度升高,C=O减少,而C-O与O原子含量增加.当CO2毒化温度达到500℃时,Pd表面会生成PdO并伴有微孔出现,而C-O随温度升高能够稳定吸附于Pd表面.毒化后的试样在常温下进行吸氢反应后表面PdO消失,吸附O含量减少,多孔形貌得到改变.CO2毒化后,由于C-O与O原子在Pd表面吸附并占据了Pd膜表面的氢解离位,从而导致Pd膜透氘能力下降.

  14. 1.6 μm DIAL Measurement and Back Trajectory Analysis of CO2 Concentration Profiles in the Lower-Atmosphere

    Science.gov (United States)

    Shibata, Y.; Nagasawa, C.; Abo, M.

    2016-12-01

    Carbon dioxide (CO2) is the primary greenhouse gas emitted through human activities. In addition to the ground level CO2 network, vertical CO2 concentration profiles also play an important role for the estimation of the carbon budget and global warming in the inversion method. Especially, for the detailed analysis of forest carbon dynamics and CO2 fluxes of urban area, vertical CO2 concentration profiles with high spatial and temporal resolution in the lower atmosphere have been conducted by a differential absorption lidar (DIAL). We have observed several vertical profiles of CO2 concentrations for nighttime and daytime from 0.25 to 2.5 km altitude with range resolution of 300 m and integration time of 1 hour. In order to extract information on the origin of the CO2 masses, one day back trajectories were calculated by using a three dimensional (3-D) atmospheric transport model. In many cases, CO2 low concentration layers of over 1.5km altitude were flown by westerly winds from the forest. In another case, high concentration layers of CO2 were flown from the urban areas. As the spectra of absorption lines of any molecules are influenced basically by the temperature in the atmosphere, laser beams of three wavelengths around a CO2 absorption spectrum are transmitted alternately to the atmosphere for simultaneous measurements of CO2 concentration and temperature profiles. Moreover, a few processing algorithms of CO2-DIAL are also performed for improvement of measurement accuracy. For computation of trajectories and drawing their figures, the JRA-25 data provided by the cooperative research project for the JRA-25 long-term reanalysis of the Japan Meteorological Agency (JMA) and the Central Research Institute of Electric Power Industry (CRIEPI) and the NIPR trajectory model (Tomikawa and Sato, 2005; http://firp-nitram.nipr.ac.jp) were used. This work was financially supported by the System Development Program for Advanced Measurement and Analysis of the Japan Science and

  15. A Parametric Analysis of CO2 Laser Heat Absorption Profile of 5083 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    JOSEPH .I. ACHEBO

    2010-06-01

    Full Text Available Aluminum alloys are amongst the most difficult everyday metals that can be welded using the laser welding process. For this reason, high power density lasers are needed to weld these alloys because they require higher thermal diffusivity to form a key hole than would be needed for other metals such as steel. This means that more heat wouldhave to be applied while welding aluminum alloys than would be needed to weld steel to achieve a satisfactory coupling effect. The heat input generated from laser welding is affected by the absorptivity coefficient, the welding speed and the time spent. Once the optimum heat input is attained, it is expected to create less heat distortion, its energy is more concentrated within the weld area and deep weld penetration is achieved. Determining optimum values of welding parameters would lead to acceptable weld quality. In this study, the heat absorption profile of a CO2 laser welding of 5083 aluminum alloy was investigated using the models proposed by Bramson in 1968 and Okon et al in 2002. The 4mm thick aluminum alloy investigated was as received from the vendors. The calculated laser beam absorptivity coefficient, irradiance and boiling temperature were 0.12, 2.3 x 106 Wcm-2 and 2482oC respectively. These calculated values compared well with reported values in other literature.

  16. Thermodynamic Analysis of Double-Stage Compression Transcritical CO2 Refrigeration Cycles with an Expander

    Directory of Open Access Journals (Sweden)

    Zhenying Zhang

    2015-04-01

    Full Text Available Four different double-compression CO2 transcritical refrigeration cycles are studied: double-compression external intercooler cycle (DCEI, double-compression external intercooler cycle with an expander (DCEIE, double-compression flash intercooler cycle (DCFI, double-compression flash intercooler cycle with an expander (DCFIE. The results showed that the optimum gas cooler pressure and optimum intermediate pressure of the flash intercooler cycles are lower than that of the external intercooler cycle. The use of an expander in the DCEI cycle leads to a decrease of the optimum gas cooler pressure and little variation of the optimum intermediate pressure. However, the replacement of the throttle valve with an expander in the DCFI cycle results in little variation of the optimal gas cooler pressure and an increase of the optimum intermediate pressure. The DCFI cycle outperforms the DCEI cycle under all the chosen operating conditions. The DCEIE cycle outperforms the DCFIE cycle when the evaporating temperature exceeds 0 °C or the gas cooler outlet temperature surpasses 35 °C. When the gas cooler exit temperature varies from 32 °C to 48 °C, the DCEI cycle, DCEIE cycle, DCFI cycle and DCFIE cycle yield averaged 4.6%, 29.2%, 12.9% and 22.3% COP improvement, respectively, over the basic cycle.

  17. Is CO2 emission a side effect of financial development? An empirical analysis for China.

    Science.gov (United States)

    Hao, Yu; Zhang, Zong-Yong; Liao, Hua; Wei, Yi-Ming; Wang, Shuo

    2016-10-01

    Based on panel data for 29 Chinese provinces from 1995 to 2012, this paper explores the relationship between financial development and environmental quality in China. A comprehensive framework is utilized to estimate both the direct and indirect effects of financial development on CO2 emissions in China using a carefully designed two-stage regression model. The first-difference and orthogonal-deviation Generalized Method of Moments (GMM) methods are used to control for potential endogeneity and introduce dynamics. To ensure the robustness of the estimations, two indicators measuring financial development-financial depth and financial efficiency-are used. The empirical results indicate that the direct effects of financial depth and financial efficiency on environmental quality are positive and negative, respectively. The indirect effects of both indicators are U shaped and dominate the shape of the total effects. These findings suggest that the influences of the financial development on environment depend on the level of economic development. At the early stage of economic growth, financial development is environmentally friendly. When the economy is highly developed, a higher level of financial development is harmful to the environmental quality.

  18. Thermal transport in CO2 laser irradiated fused silica: In situ measurements and analysis

    Science.gov (United States)

    Yang, Steven T.; Matthews, Manyalibo J.; Elhadj, Selim; Draggoo, Vaughn G.; Bisson, Scott E.

    2009-11-01

    In situ spatial and temporal temperature measurements of pristine fused silica surfaces heated with a 10.6 μm CO2 laser were obtained using an infrared radiation thermometer based on a mercury cadmium telluride camera. Laser spot sizes ranged from 250 to 1000 μm diameter with peak axial irradiance levels of 0.13-16 kW/cm2. For temperatures below 2800 K, the measured steady-state surface temperature is observed to rise linearly with both increasing beam size and incident laser irradiance. The effective thermal conductivity estimated over this range was approximately 2 W/m-K, in good agreement with classical calculations based on phonon heat capacities. Similarly, time-dependent temperature measurements up to 2000 K yielded thermal diffusivity values which were close to reported values of 7×10-7 m2/s. Above ˜2800 K, the fused silica surface temperature asymptotically approaches 3100 K as laser power is further increased, consistent with the onset of evaporative heat losses near the silica boiling point. These results show that in the laser heating regime studied here, the T3 temperature dependent thermal conductivity due to radiation transport can be neglected, but at temperatures above 2800 K heat transport due to evaporation must also be considered. The thermal transport in fused silica up to 2800 K, over a range of conditions, can then be adequately described by a linear diffusive heat equation assuming constant thermal properties.

  19. 2020年我国水泥行业CO2排放趋势与减排路径分析%Analysis on CO2 Emission Trend and Emission Reduction Path of China's Cement Industry in 2020

    Institute of Scientific and Technical Information of China (English)

    蒋小谦; 康艳兵; 刘强; 赵盟

    2012-01-01

    我国水泥行业的CO2排放仅次于电力行业,约占全国排放总量的15%.分析水泥行业的CO2排放趋势和减排路径对实现我国温室气体排放控制目标有着重要的现实意义.本文从影响水泥行业排放的主要影响因素着手,分析了水泥产量和单耗的现状及未来发展趋势,计算了水泥行业的历史排放、发展趋势以及减排潜力,指出了实现减排潜力面临的挑战和障碍,以及相应的措施建议.%CO2 emission from China's cement industry is only second to power industry, accounted for 15% of total national emissions. Analysis on CO2 emission trend and emission reduction path of cement industry is significant to the realization of GHG emissions control target in China. From the perspective of major influencing factors, this paper analyzes the status and future trend of cement production and energy consumption per unit of product, calculates history and future emissions as well as emission reduction potentials, also analyzes challenges and obstacles, and proposes appropriate measures recommendations.

  20. Compound specific isotope analysis of organophosphorus pesticides.

    Science.gov (United States)

    Wu, Langping; Yao, Jun; Trebse, Polonca; Zhang, Ning; Richnow, Hans H

    2014-09-01

    Compound-specific isotope analysis (CSIA) has been established as a tool to study the environmental fate of a wide range of contaminants. In this study, CSIA was developed to analyse the stable carbon isotope signatures of the widely used organophosphorus pesticides: dichlorvos, omethoate and dimethoate. The linearity of the GC-C-IRMS system was tested for target pesticides and led to an acceptable isotope composition within the uncertainty of the instrument. In order to assess the accuracy of the developed method, the effect of the evaporation procedure on measured carbon isotope composition (δ(13)C) values was studied and showed that concentration by evaporation of solvents had no significant isotope effect. The CSIA was then applied to investigate isotope fractionation of the hydrolysis and photolysis of selected pesticides. The carbon isotope fractionation of tested pesticides was quantified by the Rayleigh model, which revealed a bulk enrichment factor (ε) of -0.2±0.1‰ for hydrolysis of dichlorvos, -1.0±0.1‰ and -3.7±1.1‰ for hydrolysis and photolysis of dimethoate respectively. This study is a first step towards the application of CSIA to trace the transport and degradation of organophosphorus pesticides in the environment.

  1. Thermodynamics of the CO2–Absorption/Desorption Section in the Integrated Gasifying Combined cycle — II. Analysis

    Directory of Open Access Journals (Sweden)

    Jaroslav KOZACZKA

    2012-06-01

    Full Text Available The thermodynamic analysis of the absorption/desorption section of the ICGC–cycle has been presented using the Second Law with special emphasis on the thermodynamic effectivity concept and usability for complex systems investigations. Essential problems have been discussed based on the classical bibliographical items on the subject. Numerical calculations have been accomplished using results obtained in the first part, which contained absorption and desorption modeling approach oriented onto thermodynamic analyzes. Additionally the special properties of dilute solutions, especially the CO2/water system, have been presented and the problem of the solute chemical concentration exergy change suggested.

  2. Stable isotope dilution assays in mycotoxin analysis

    Energy Technology Data Exchange (ETDEWEB)

    Rychlik, Michael; Asam, Stefan [Universitaet Muenchen, Lehrstuhl fuer Lebensmittelchemie der Technischen, Garching (Germany)

    2008-01-15

    The principle and applications of stable isotope dilution assays (SIDAs) in mycotoxin analysis are critically reviewed. The general section includes historical aspects of SIDAs, the prerequisites and limitations of the use of stable isotopically labelled internal standards, and possible calibration procedures. In the application section actual SIDAs for the analysis of trichothecenes, zearalenone, fumonisins, patulin, and ochratoxin A are presented. The syntheses and availability of labelled mycotoxins for use as internal standards is reviewed and specific advances in food analysis and toxicology are demonstrated. The review indicates that LC-MS applications, in particular, require the use of stable isotopically labelled standards to compensate for losses during clean-up and for discrimination due to ion suppression. As the commercial availability of these compounds continues to increase, SIDAs can be expected to find expanding use in mycotoxin analysis. (orig.)

  3. Stable isotope dilution assays in mycotoxin analysis.

    Science.gov (United States)

    Rychlik, Michael; Asam, Stefan

    2008-01-01

    The principle and applications of stable isotope dilution assays (SIDAs) in mycotoxin analysis are critically reviewed. The general section includes historical aspects of SIDAs, the prerequisites and limitations of the use of stable isotopically labelled internal standards, and possible calibration procedures. In the application section actual SIDAs for the analysis of trichothecenes, zearalenone, fumonisins, patulin, and ochratoxin A are presented. The syntheses and availability of labelled mycotoxins for use as internal standards is reviewed and specific advances in food analysis and toxicology are demonstrated. The review indicates that LC-MS applications, in particular, require the use of stable isotopically labelled standards to compensate for losses during clean-up and for discrimination due to ion suppression. As the commercial availability of these compounds continues to increase, SIDAs can be expected to find expanding use in mycotoxin analysis.

  4. [Establishment and assessment of QA/QC method for sampling and analysis of atmosphere background CO2].

    Science.gov (United States)

    Liu, Li-xin; Zhou, Ling-xi; Xia, Ling-jun; Wang, Hong-yang; Fang, Shuang-xi

    2014-12-01

    To strengthen scientific management and sharing of greenhouse gas data obtained from atmospheric background stations in China, it is important to ensure the standardization of quality assurance and quality control method for background CO2 sampling and analysis. Based on the greenhouse gas sampling and observation experience of CMA, using portable sampling observation and WS-CRDS analysis technique as an example, the quality assurance measures for atmospheric CO,sampling and observation in the Waliguan station (Qinghai), the glass bottle quality assurance measures and the systematic quality control method during sample analysis, the correction method during data processing, as well as the data grading quality markers and data fitting interpolation method were systematically introduced. Finally, using this research method, the CO2 sampling and observation data at the atmospheric background stations in 3 typical regions were processed and the concentration variation characteristics were analyzed, indicating that this research method could well catch the influences of the regional and local environmental factors on the observation results, and reflect the characteristics of natural and human activities in an objective and accurate way.

  5. Isotopic gas analysis through Purcell cavity enhanced Raman scattering

    Science.gov (United States)

    Petrak, B.; Cooper, J.; Konthasinghe, K.; Peiris, M.; Djeu, N.; Hopkins, A. J.; Muller, A.

    2016-02-01

    Purcell enhanced Raman scattering (PERS) by means of a doubly resonant Fabry-Perot microcavity (mode volume ≈ 100 μm3 and finesse ≈ 30 000) has been investigated as a technique for isotopic ratio gas analysis. At the pump frequency, the resonant cavity supports a buildup of circulating power while simultaneously enabling Purcell spontaneous emission rate enhancement at the resonant Stokes frequency. The three most common isotopologues of CO2 gas were quantified, and a signal was obtained from 13C16O2 down to a partial pressure of 2 Torr. Due to its small size and low pump power needed (˜10 mW) PERS lends itself to miniaturization. Furthermore, since the cavity is resonant with the emission frequency, future improvements could allow it to serve as its own spectral analyzer and no separate spectroscopic device would be needed.

  6. Interaction of CO2 concentrations and water stress in semiarid plants causes diverging response in instantaneous water use efficiency and carbon isotope composition

    Science.gov (United States)

    Zhao, Na; Meng, Ping; He, Yabing; Yu, Xinxiao

    2017-07-01

    In the context of global warming attributable to the increasing levels of CO2, severe drought may be more frequent in areas that already experience chronic water shortages (semiarid areas). This necessitates research on the interactions between increased levels of CO2 and drought and their effect on plant photosynthesis. It is commonly reported that 13C fractionation occurs as CO2 gas diffuses from the atmosphere to the substomatal cavity. Few researchers have investigated 13C fractionation at the site of carboxylation to cytoplasm before sugars are exported outward from the leaf. This process typically progresses in response to variations in environmental conditions (i.e., CO2 concentrations and water stress), including in their interaction. Therefore, saplings of two typical plant species (Platycladus orientalis and Quercus variabilis) from semiarid areas of northern China were selected and cultivated in growth chambers with orthogonal treatments (four CO2 concentration ([CO2]) × five soil volumetric water content (SWC)). The δ13C of water-soluble compounds extracted from leaves of saplings was determined for an assessment of instantaneous water use efficiency (WUEcp) after cultivation. Instantaneous water use efficiency derived from gas-exchange measurements (WUEge) was integrated to estimate differences in δ13C signal variation before leaf-level translocation of primary assimilates. The WUEge values in P. orientalis and Q. variabilis both decreased with increased soil moisture at 35-80 % of field capacity (FC) and increased with elevated [CO2] by increasing photosynthetic capacity and reducing transpiration. Instantaneous water use efficiency (iWUE) according to environmental changes differed between the two species. The WUEge in P. orientalis was significantly greater than that in Q. variabilis, while an opposite tendency was observed when comparing WUEcp between the two species. Total 13C fractionation at the site of carboxylation to cytoplasm before sugar

  7. CO2-Neutral Fuels

    NARCIS (Netherlands)

    Goede, A.; van de Sanden, M. C. M.

    2016-01-01

    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

  8. CO2-Neutral Fuels

    Science.gov (United States)

    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.

  9. CO2-Neutral Fuels

    NARCIS (Netherlands)

    Goede, A.; van de Sanden, M. C. M.

    2016-01-01

    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

  10. Uncertainty Analysis using Experimental Design Methods for Assessing CO2 Sequestration and Coal Bed Methane Production Potential of Subbituminous Coals of the Nenana Basin, Interior Alaska

    Science.gov (United States)

    Dixit, N.; Ahmadi, M.; Hanks, C.; Awoleke, O.

    2016-12-01

    Naturally fractured, unmineable coal seam reservoirs are attractive targets for geological sequestration of CO2 because of their high CO2-adsorption capacities and possible cost offsets from enhanced coal bed methane production (ECBM). In this study, we have investigated CO2 sequestration and CH4 production potential of the subbituminous Healy Creek Formation coals through preliminary sensitivity analyses, experimental design methods and fluid flow simulations. Our primary sensitivity analyses indicated that the total cumulative volumes of CO2 sequestered and CH4 produced from the Healy Creek coals are mostly sensitive to bottomhole injection pressure, coal matrix porosity, fracture porosity and permeability, and coal volumetric strain. The results of Plackett-Burman experimental design were used to further constrain the most influential reservoir parameters and generate proxy models for probabilistic reservoir forecasts. Our probabilistic estimates for the mature, subbituminous Healy Creek coals in the entire Nenana basin indicate that it is possible to sequestrate between 0.87 TCF (P10) and 0.2 TCF (P90) of CO2 while producing between 0.29 TCF (P10) and 0.1 TCF (P90) of CH4 at the end of 20-year forecast. Our study demonstrated application of experimental design methods and Monte Carlo analysis in reducing these uncertainties in reservoir properties and quantifying their effect on reservoir performance. In addition, the results of fluid flow scenarios show that the CO2 sequestration through a primary reservoir depletion method is the most effective way to inject CO2 in the coals of the Nenana basin. Including a horizontal well instead of the vertical well resulted in relatively high average gas production rates and subsequent faster production decline. Our CO2 buoyancy scenario suggested that the effect of CO2 buoyancy and the nature of the caprock should be considered when identifying potential geologic sites for CO2 sequestration and in CO2 storage capacity

  11. Gravimetric analysis of CO2 adsorption on activated carbon at various pressures and temperatures using piezoelectric microcantilevers.

    Science.gov (United States)

    Jin, Yusung; Lee, Dongkyu; Lee, Sangkyu; Moon, Wonkyu; Jeon, Sangmin

    2011-09-15

    We investigated the adsorption and desorption of CO(2) on activated carbon using piezoelectric microcantilevers. After coating the free end of a cantilever with activated carbon, variations in the resonance frequency of the cantilever were measured as a function of CO(2) pressure, which is related to mass changes due to the adsorption or desorption of CO(2). The pressure-dependent viscous damping effects were compensated in the calculation of the CO(2) adsorption capacity of the activated carbon by comparing the frequency differences between the coated and uncoated cantilevers. The mass sensitivity of the piezoelectric cantilever was found to be better than 1 pg. The fractional coverage of CO(2) agreed with a Langmuir adsorption isotherm, indicating that a submonolayer of adsorbed CO(2) occurred on the surface of the activated carbon under the experimental conditions. The heat of adsorption was determined using the Clausius-Clapeyron relation and the fractional coverage of CO(2) at various temperatures and pressures.

  12. Consistent assimilation of MERIS FAPAR and atmospheric CO2 into a terrestrial vegetation model and interactive mission benefit analysis

    Directory of Open Access Journals (Sweden)

    P.-P. Mathieu

    2012-08-01

    Full Text Available The terrestrial biosphere is currently a strong sink for anthropogenic CO2 emissions. Through the radiative properties of CO2, the strength of this sink has a direct influence on the radiative budget of the global climate system. The accurate assessment of this sink and its evolution under a changing climate is, hence, paramount for any efficient management strategies of the terrestrial carbon sink to avoid dangerous climate change. Unfortunately, simulations of carbon and water fluxes with terrestrial biosphere models exhibit large uncertainties. A considerable fraction of this uncertainty reflects uncertainty in the parameter values of the process formulations within the models. This paper describes the systematic calibration of the process parameters of a terrestrial biosphere model against two observational data streams: remotely sensed FAPAR (fraction of absorbed photosynthetically active radiation provided by the MERIS (ESA's Medium Resolution Imaging Spectrometer sensor and in situ measurements of atmospheric CO2 provided by the GLOBALVIEW flask sampling network. We use the Carbon Cycle Data Assimilation System (CCDAS to systematically calibrate some 70 parameters of the terrestrial BETHY (Biosphere Energy Transfer Hydrology model. The simultaneous assimilation of all observations provides parameter estimates and uncertainty ranges that are consistent with the observational information. In a subsequent step these parameter uncertainties are propagated through the model to uncertainty ranges for predicted carbon fluxes. We demonstrate the consistent assimilation at global scale, where the global MERIS FAPAR product and atmospheric CO2 are used simultaneously. The assimilation improves the match to independent observations. We quantify how MERIS data improve the accuracy of the current and future (net and gross carbon flux estimates (within and beyond the assimilation period. We further demonstrate the use of an interactive mission benefit

  13. Consistent assimilation of MERIS FAPAR and atmospheric CO2 into a terrestrial vegetation model and interactive mission benefit analysis

    Directory of Open Access Journals (Sweden)

    P.-P. Mathieu

    2011-11-01

    Full Text Available The terrestrial biosphere is currently a strong sink for anthropogenic CO2 emissions. Through the radiative properties of CO2 the strength of this sink has a direct influence on the radiative budget of the global climate system. The accurate assessment of this sink and its evolution under a changing climate is, hence, paramount for any efficient management strategies of the terrestrial carbon sink to avoid dangerous climate change. Unfortunately, simulations of carbon and water fluxes with terrestrial biosphere models exhibit large uncertainties. A considerable fraction of this uncertainty is reflecting uncertainty in the parameter values of the process formulations within the models. This paper describes the systematic calibration of the process parameters of a terrestrial biosphere model against two observational data streams: remotely sensed FAPAR provided by the MERIS sensor and in situ measurements of atmospheric CO2 provided by the GLOBALVIEW flask sampling network. We use the Carbon Cycle Data Assimilation System (CCDAS to systematically calibrate some 70 parameters of the terrestrial biosphere model BETHY. The simultaneous assimilation of all observations provides parameter estimates and uncertainty ranges that are consistent with the observational information. In a subsequent step these parameter uncertainties are propagated through the model to uncertainty ranges for predicted carbon fluxes. We demonstrate the consistent assimilation for two different set-ups: first at site-scale, where MERIS FAPAR observations at a range of sites are used as simultaneous constraints, and second at global scale, where the global MERIS FAPAR product and atmospheric CO2 are used simultaneously. On both scales the assimilation improves the match to independent observations. We quantify how MERIS data improve the accuracy of the current and future (net and gross carbon flux estimates (within and beyond the assimilation period. We further demonstrate the

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

    Science.gov (United States)

    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

  15. Structural Path Analysis of Fossil Fuel Based CO2 Emissions: A Case Study for China

    OpenAIRE

    Zhiyong Yang; Wenjie Dong; Jinfeng Xiu; Rufeng Dai; Jieming Chou

    2015-01-01

    Environmentally extended input-output analysis (EEIOA) has long been used to quantify global and regional environmental impacts and to clarify emission transfers. Structural path analysis (SPA), a technique based on EEIOA, is especially useful for measuring significant flows in this environmental-economic system. This paper constructs an imports-adjusted single-region input-output (SRIO) model considering only domestic final use elements, and it uses the SPA technique to highlight crucial rou...

  16. Thermodynamic analysis of methanation of palm empty fruit bunch (PEFB pyrolysis oil with and without in situ CO2 sorption

    Directory of Open Access Journals (Sweden)

    Hafizah Abdul Halim Yun

    2015-11-01

    Full Text Available Thermodynamic equilibrium analysis for conversion of palm empty fruit bunch (PEFB bio-oil to methane using low-temperature steam reforming (LTSR process was conducted by assuming either isothermal or adiabatic condition, with and without sorption enhancement (SE-LTSR, with CaO(S or Ca(OH2(S as CO2 sorbent. Temperatures of 300-800 K, molar steam to carbon (S/C ratios of 0.3-7.0, pressures of 1-30 atm and molar calcium to carbon ratios (Ca:C of 0.3-1.0 were simulated. For reasons of process simplicity, the best conditions for CH4 production were observed for the adiabatic LTSR process without sorption at S/C between 2.5 and 3 (compared to the stoichiometric S/C of 0.375, inlet temperature above 450 K, resulting in reformer temperature of 582 K, where close to the theoretical maximum CH4 yield of 38 wt % of the simulated dry PEFB oil was obtained, resulting in a reformate consisting of 44.5 vol % CH4, 42.7 vol % CO2 and 12.7 vol % H2 and requiring only moderate heating mainly to partially preheat the reactants. Temperatures and S/C below these resulted in high risk of carbon by-product.

  17. An analytical system for stable isotope analysis on carbon monoxide using continuous-flow isotope-ratio mass spectrometry

    NARCIS (Netherlands)

    Pathirana, S. L.; Van Der Veen, C.; Popa, M. E.; Röckmann, T.

    2015-01-01

    A fully automated system for the determination of δ13C and δ18O in atmospheric CO has been developed. CO is extracted from an air sample and converted into carbon dioxide (CO2) using the Schütze reagent. The isotopic composition is determined with an isotope-ratio mass spectrometer (IRMS) technique.

  18. Experimental study on monitoring CO2 sequestration by conjoint analysis of the P-wave velocity and amplitude.

    Science.gov (United States)

    Chen, Hao; Yang, Shenglai; Huan, Kangning; Li, Fangfang; Huang, Wei; Zheng, Aiai; Zhang, Xing

    2013-09-03

    CO2 sequestration has been considered to be one of the most straightforward carbon management strategies for industrial CO2 emission. Monitoring of the CO2 injection process is one of the best ways to make sure the safety storage but is also a major challenge in CO2 geological sequestration. Previous field and laboratory researches have shown that seismic methods are among the most promising monitoring methods because of the obvious reduction in P-wave velocities caused by CO2 injection. However, as CO2 injection continues, the P-wave velocity becomes increasingly insensitive according to the pilot projects when CO2 saturation is higher than 20-40%. Therefore, the conventional seismic method needs improvement or replacement to solve its limitations. In this study, P-wave velocity and amplitude responses to supercritical CO2 injection in brine-saturated core samples from Jilin oilfield were tested using core displacement and an ultrasonic detection integrated system. Results showed that neither the P-wave velocity nor amplitude could simply be used to monitor the CO2 injection process because of the insensitive or nonmonotonous response. Consequently, a new index was established by synthetically considering these two parameters to invert and monitor the CO2 process, which can be thought of as a newer and more effective assessment criterion for the seismic method.

  19. The evolution of 13C and 18O isotope composition of DIC in a calcite depositing film of water with isotope exchange between the DIC and a CO2 containing atmosphere, and simultaneous evaporation of the water. Implication to climate proxies from stalagmites: A theoretical model

    Science.gov (United States)

    Dreybrodt, Wolfgang; Romanov, Douchko

    2016-12-01

    The most widely applied climate proxies in speleothems are the isotope compositions of carbon and oxygen expressed by δ13C and δ18O values. However, mechanisms, which are not related to climate changes, overlay the climate signal. One is the temporal increase of both, δ13C and δ18O values by kinetic processes during precipitation of calcite. Isotope exchange between DIC in the water and the CO2 in the surrounding cave atmosphere can also change isotope composition. Here we present a theoretical model of the temporal isotope evolution of DIC in a thin water layer during precipitation of calcite and simultaneous isotope exchange with the cave atmosphere, and simultaneous evaporation of water. The exchange of oxygen isotopes in the DIC with those in the water is also considered. For drip times for Tdrip calcite, the second stems from isotope exchange with the CO2 of the cave atmosphere, and the third results from isotope exchange between oxygen in the DIC and the oxygen in the water. λ, ε are kinetic parameters, τ is the time scale of precipitation, (δeqatm -δ0) and (δeqwater -δ0) are the differences between the corresponding initial δ-value δ0 and the value δeqatm,water if DIC were in isotope equilibrium with the atmosphere or in the case of oxygen with the water, respectively. τinatm and τwater are the time scales of approach to isotope equilibrium by the exchange reactions. Ceq is the concentration of DIC in chemical equilibrium with the CO2 in the cave atmosphere and C0 is the initial concentration, when the water drips to the stalagmite. Tev is the time needed for complete evaporation of the water layer. εW is the fractionation between water vapor and fluid water. For times Tdrip > 0.2τ we find a further increase of ΔDIC(Tdrip) until a maximum is passed and a final value is reached. If (δeqatm -δ0) and (δeqwater -δ0) are both zero, exchange has no influence on the isotope composition for drip times Tdrip < 0.2τB. For carbon it is likely

  20. Qualitative analysis of Cu2+, Co2+, and Ni2+ cations using thin-layer chromatography.

    Science.gov (United States)

    Ergül, Soner

    2004-03-01

    The M(DEDTC)2 (M = Cu, Co, or Ni) and M(PyDTC)2 (M = Cu or Co) complexes prepared by reactions of sodium diethyldithiocarbamate and ammonium pyrollidinedithiocarbamate with metal (II) nitrates are examined for qualitative analysis and separation using thin-layer chromatography systems. These complexes and their mixtures are spotted to the activated thin layers of silica gel 60GF254 (Si-60GF254) with a 250-microm thickness. Pure toluene and a toluene-cyclohexane mixture (3:1, v/v) are used as mobile phases for running of the complexes. These chromatographic systems are successfully used for qualitative analysis of corresponding metal cations and separation of components in both M(DEDTC)2 and M(PyDTC)2 complex mixtures.

  1. Compressor Modeling for Transient Analysis of Supercritical CO2 Brayton Cycle by using MARS code

    Energy Technology Data Exchange (ETDEWEB)

    Park, Joo Hyun; Park, Hyun Sun; Kim, Tae Ho; Kwon, Jin Gyu [POSTECH, Pohang (Korea, Republic of); Bae, Sung Won; Cha, Jae Eun [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    In this study, SCIEL (Supercritical CO{sub 2} Integral Experimental Loop) was chosen as a reference loop and the MARS code was as the transient cycle analysis code. As a result, the compressor homologous curve was developed from the SCIEL experimental data and MARS analysis was performed and presented in the paper. The advantages attract SCO{sub 2}BC as a promising next generation power cycles. The high thermal efficiency comes from the operation of compressor near the critical point where the properties of SCO{sub 2}. The approaches to those of liquid phase, leading drastically lower the compression work loss. However, the advantage requires precise and smooth operation of the cycle near the critical point. However, it is one of the key technical challenges. The experimental data was steady state at compressor rotating speed of 25,000 rpm. The time, 3133 second, was starting point of steady state. Numerical solutions were well matched with the experimental data. The mass flow rate from the MARS analysis of approximately 0.7 kg/s was close to the experimental result of 0.9 kg/s. It is expected that the difference come from the measurement error in the experiment. In this study, the compressor model was developed and implemented in MARS to study the transient analysis of SCO{sub 2}BC in SCIEL. We obtained the homologous curves for the SCIEL compressor using experimental data and performed nodalization of the compressor model using MARS code. In conclusions, it was found that numerical solutions from the MARS model were well matched with experimental data.

  2. On the pros and cons of the IRMS technique of data processing: uncertainty in results, a case study for determining carbon and oxygen isotopic abundance ratios as CO_2^+

    CERN Document Server

    Datta, B P

    2011-01-01

    The properties of different relationships, representing the basic evaluation as well as its inputs and outputs shaping processes in the CO_2^+ isotope ratio mass spectrometry (IRMS), are studied. It is thus shown that the input generation by using only one auxiliary reference CO2 gas (ARCG) is an accuracy enhancing process, and clarified how the input-by-measurement uncertainty-ratio(s) could be ensured to be tens of folds less than unity. However, the known relationship for using two ARCGs appears to be neither of a logistical base nor better by application. A mathematically correct means for involving two or more than two ARCGs is worked out. However, the same is observed to be worse by behavior, i.e. causes the scale converted data to be more inaccurate than the measured data. The basic evaluation requires solving a set of equations. Using a typical set, it is exemplified that, and explained why, the solutions (determined elemental isotopic abundance ratios (EIARs)) are generally as representative as the i...

  3. Tree-ring stable isotopes record the impact of a foliar fungal pathogen on CO(2) assimilation and growth in Douglas-fir.

    Science.gov (United States)

    Saffell, Brandy J; Meinzer, Frederick C; Voelker, Steven L; Shaw, David C; Brooks, J Renée; Lachenbruch, Barbara; McKay, Jennifer

    2014-07-01

    Swiss needle cast (SNC) is a fungal disease of Douglas-fir (Pseudotsuga menziesii) that has recently become prevalent in coastal areas of the Pacific Northwest. We used growth measurements and stable isotopes of carbon and oxygen in tree-rings of Douglas-fir and a non-susceptible reference species (western hemlock, Tsuga heterophylla) to evaluate their use as proxies for variation in past SNC infection, particularly in relation to potential explanatory climate factors. We sampled trees from an Oregon site where a fungicide trial took place from 1996 to 2000, which enabled the comparison of stable isotope values between trees with and without disease. Carbon stable isotope discrimination (Δ(13)C) of treated Douglas-fir tree-rings was greater than that of untreated Douglas-fir tree-rings during the fungicide treatment period. Both annual growth and tree-ring Δ(13)C increased with treatment such that treated Douglas-fir had values similar to co-occurring western hemlock during the treatment period. There was no difference in the tree-ring oxygen stable isotope ratio between treated and untreated Douglas-fir. Tree-ring Δ(13)C of diseased Douglas-fir was negatively correlated with relative humidity during the two previous summers, consistent with increased leaf colonization by SNC under high humidity conditions that leads to greater disease severity in following years.

  4. Tree-ring stable isotopes record the impact of a foliar fungal pathogen on CO2 assimilation and growth in Douglas-fir

    Science.gov (United States)

    Swiss needle cast (SNC) is a fungal disease of Douglas-fir (Pseudotsuga menziesii) that has recently become prevalent in coastal areas of the Pacific Northwest. We used growth measurements and stable isotopes of carbon and oxygen in tree-rings of Douglas-fir and a non-susceptible...

  5. Regional disparity analysis of Chinese freight transport CO2 emissions from 1990 to 2007

    DEFF Research Database (Denmark)

    Luo, Xiao; Dong, Liang; Dou, Yi

    2016-01-01

    , this research study aims to conduct a decomposition analysis and causal mechanism investigation study on urban transport sector, with comparative studies on two Asian mega cities named Tokyo , Japan and Shanghai, China. We illustrate the driving forces of urban transport sector and the causal mechanism of each...... factor, and provide critical policy insights through comparative studies. The outcomes of this study provide critical insights to the recent practice in Shanghai, as well as the practical guidance to low carbon urban planning in developing countries....

  6. Performance Analysis of Cold Energy Recovery from CO2 Injection in Ship-Based Carbon Capture and Storage (CCS

    Directory of Open Access Journals (Sweden)

    Hwalong You

    2014-11-01

    Full Text Available Carbon capture and storage (CCS technology is one of the practical solutions for mitigating the effects of global warming. When captured CO2 is injected into storage sites, the CO2 is subjected to a heating process. In a conventional CO2 injection system, CO2 cold energy is wasted during this heating process. This study proposes a new CO2 injection system that takes advantage of the cold energy using the Rankine cycle. The study compared the conventional system with the new CO2 injection system in terms of specific net power consumption, exergy efficiency, and life-cycle cost (LCC to estimate the economic effects. The results showed that the new system reduced specific net power consumption and yielded higher exergy efficiency. The LCC of the new system was more economical. Several cases were examined corresponding to different conditions, specifically, discharge pressure and seawater temperature. This information may affect decision-making when CCS projects are implemented.

  7. Modeling and Dynamic Analysis of CO2-Emission Free Power Processes in Modelica using the CombiPlant Library

    OpenAIRE

    Selimovic, Faruk; Eborn, Jonas; Sundén, Bengt

    2006-01-01

    The need to reduce CO2 emissions from fossil-fuel based power production creates the need for new power plant solutions where the CO2 is captured and stored or reused. Different concepts to capture CO2 fall into the three main categories: 1. Precombustion decarbonization 2. Oxy-fuel combustion 3. Post-combustion removal of carbon. In the first two types of processes Oxygen Transport Membrane (OTM) is the key component, as pure oxygen is usually required to proces...

  8. Structural Path Analysis of Fossil Fuel Based CO2 Emissions: A Case Study for China

    Science.gov (United States)

    Yang, Zhiyong; Dong, Wenjie; Xiu, Jinfeng; Dai, Rufeng; Chou, Jieming

    2015-01-01

    Environmentally extended input-output analysis (EEIOA) has long been used to quantify global and regional environmental impacts and to clarify emission transfers. Structural path analysis (SPA), a technique based on EEIOA, is especially useful for measuring significant flows in this environmental-economic system. This paper constructs an imports-adjusted single-region input-output (SRIO) model considering only domestic final use elements, and it uses the SPA technique to highlight crucial routes along the production chain in both final use and sectoral perspectives. The results indicate that future mitigation policies on household consumption should change direct energy use structures in rural areas, cut unreasonable demand for power and chemical products, and focus on urban areas due to their consistently higher magnitudes than rural areas in the structural routes. Impacts originating from government spending should be tackled by managing onsite energy use in 3 major service sectors and promoting cleaner fuels and energy-saving techniques in the transport sector. Policies on investment should concentrate on sectoral interrelationships along the production chain by setting up standards to regulate upstream industries, especially for the services, construction and equipment manufacturing sectors, which have high demand pulling effects. Apart from the similar methods above, mitigating policies in exports should also consider improving embodied technology and quality in manufactured products to achieve sustainable development. Additionally, detailed sectoral results in the coal extraction industry highlight the onsite energy use management in large domestic companies, emphasize energy structure rearrangement, and indicate resources and energy safety issues. Conclusions based on the construction and public administration sectors reveal that future mitigation in secondary and tertiary industries should be combined with upstream emission intensive industries in a

  9. Structural Path Analysis of Fossil Fuel Based CO2 Emissions: A Case Study for China.

    Science.gov (United States)

    Yang, Zhiyong; Dong, Wenjie; Xiu, Jinfeng; Dai, Rufeng; Chou, Jieming

    2015-01-01

    Environmentally extended input-output analysis (EEIOA) has long been used to quantify global and regional environmental impacts and to clarify emission transfers. Structural path analysis (SPA), a technique based on EEIOA, is especially useful for measuring significant flows in this environmental-economic system. This paper constructs an imports-adjusted single-region input-output (SRIO) model considering only domestic final use elements, and it uses the SPA technique to highlight crucial routes along the production chain in both final use and sectoral perspectives. The results indicate that future mitigation policies on household consumption should change direct energy use structures in rural areas, cut unreasonable demand for power and chemical products, and focus on urban areas due to their consistently higher magnitudes than rural areas in the structural routes. Impacts originating from government spending should be tackled by managing onsite energy use in 3 major service sectors and promoting cleaner fuels and energy-saving techniques in the transport sector. Policies on investment should concentrate on sectoral interrelationships along the production chain by setting up standards to regulate upstream industries, especially for the services, construction and equipment manufacturing sectors, which have high demand pulling effects. Apart from the similar methods above, mitigating policies in exports should also consider improving embodied technology and quality in manufactured products to achieve sustainable development. Additionally, detailed sectoral results in the coal extraction industry highlight the onsite energy use management in large domestic companies, emphasize energy structure rearrangement, and indicate resources and energy safety issues. Conclusions based on the construction and public administration sectors reveal that future mitigation in secondary and tertiary industries should be combined with upstream emission intensive industries in a

  10. Structural Path Analysis of Fossil Fuel Based CO2 Emissions: A Case Study for China.

    Directory of Open Access Journals (Sweden)

    Zhiyong Yang

    Full Text Available Environmentally extended input-output analysis (EEIOA has long been used to quantify global and regional environmental impacts and to clarify emission transfers. Structural path analysis (SPA, a technique based on EEIOA, is especially useful for measuring significant flows in this environmental-economic system. This paper constructs an imports-adjusted single-region input-output (SRIO model considering only domestic final use elements, and it uses the SPA technique to highlight crucial routes along the production chain in both final use and sectoral perspectives. The results indicate that future mitigation policies on household consumption should change direct energy use structures in rural areas, cut unreasonable demand for power and chemical products, and focus on urban areas due to their consistently higher magnitudes than rural areas in the structural routes. Impacts originating from government spending should be tackled by managing onsite energy use in 3 major service sectors and promoting cleaner fuels and energy-saving techniques in the transport sector. Policies on investment should concentrate on sectoral interrelationships along the production chain by setting up standards to regulate upstream industries, especially for the services, construction and equipment manufacturing sectors, which have high demand pulling effects. Apart from the similar methods above, mitigating policies in exports should also consider improving embodied technology and quality in manufactured products to achieve sustainable development. Additionally, detailed sectoral results in the coal extraction industry highlight the onsite energy use management in large domestic companies, emphasize energy structure rearrangement, and indicate resources and energy safety issues. Conclusions based on the construction and public administration sectors reveal that future mitigation in secondary and tertiary industries should be combined with upstream emission intensive

  11. Dynamic simulation and analysis of a pilot-scale CO2 post-combustion capture unit using piperazine and MEA

    DEFF Research Database (Denmark)

    Gaspar, Jozsef; Ricardez-Sandoval, Luis; Jørgensen, John Bagterp

    2016-01-01

    show the results for the baseline 30 wt% MEA and the low energy piperazine (PZ) solutions. This analysis reveals that the absorber reaches steady-state faster using MEA compared to PZ. This is related to the shift of the mass transfer zone due to changes in temperature. The transient operation...... in the regeneration unit is somewhat similar while using both solvents: an initial fast decrease of the lean loading is followed by a slow transient period as the system approaches steady-state conditions. We show the presence of inverse response in the stripper column when the rich loading decreases or the feed......Post-combustion capture is a promising technology-for developing CO2 neutral power plants. However, to make it economically and technically feasible, capture plants must follow the fast and large load changes of the power plants without decreasing the overall performance of the plant. Dynamic...

  12. [Analysis of the chemical constituents of volatile oil from the Folium Rhododendri Daurici by supercritical CO2 extraction].

    Science.gov (United States)

    Jiao, Shu-qing; Liu, Feng-hua

    2009-02-01

    To compare the chemical constituents of volatile oils from Folium Rhododendri Daurici between supercritical CO2 extraction (SCE-CO2) and steam distillation (SD). The chemical constituents of volatile oils obtained by two methods were analyzed by GC-MS. 52 compounds in the volatile oil extracted by SCE-CO2 and 48 compounds in the volatile oil extracted by SD were separated and identified separately. There were 45 same components. The chemical constituents obtained by SCE-CO2 and SD are approached.

  13. CO2 -Responsive polymers.

    Science.gov (United States)

    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.

  14. Design and package of a 14CO2 field analyzer: the Global Monitor Platform (GMP)

    Science.gov (United States)

    Marino, Bruno D. V.; Bright, Michelle; Gronniger, Glen

    2011-09-01

    Carbon Capture and Sequestration (CCS) is widely accepted as a means to reduce and eliminate the fossil fuel CO2 (ff- CO2) emissions from coal fired power plants. Success of CCS depends on near zero leakage rates over decadal time scales. Currently no commercial methods to determine leakage of ff-CO2 are available. The Global Monitor Platform (GMP) field analyzer provides high precision analysis of CO2 isotopes [12C (99%), 13C (GMP for field deployment. The system will conduct atmosphere monitoring then adapt to water and soil evaluations. Measuring 14CO2 in real time will provide quantitative concentration data for ff-CO2 in the atmosphere and CCS leakage detection. Initial results will be discussed along with design changes for improved detection sensitivity and manufacturability.

  15. Isotopic evidence for the infiltration of mantle and metamorphic CO2-H2O fluids from below in faulted rocks from the San Andreas Fault System

    Energy Technology Data Exchange (ETDEWEB)

    Pili, E.; Kennedy, B.M.; Conrad, M.E.; Gratier, J.-P.

    2010-12-15

    To characterize the origin of the fluids involved in the San Andreas Fault (SAF) system, we carried out an isotope study of exhumed faulted rocks from deformation zones, vein fillings and their hosts and the fluid inclusions associated with these materials. Samples were collected from segments along the SAF system selected to provide a depth profile from upper to lower crust. In all, 75 samples from various structures and lithologies from 13 localities were analyzed for noble gas, carbon, and oxygen isotope compositions. Fluid inclusions exhibit helium isotope ratios ({sup 3}He/{sup 4}He) of 0.1-2.5 times the ratio in air, indicating that past fluids percolating through the SAF system contained mantle helium contributions of at least 35%, similar to what has been measured in present-day ground waters associated with the fault (Kennedy et al., 1997). Calcite is the predominant vein mineral and is a common accessory mineral in deformation zones. A systematic variation of C- and O-isotope compositions of carbonates from veins, deformation zones and their hosts suggests percolation by external fluids of similar compositions and origin with the amount of fluid infiltration increasing from host rocks to vein to deformation zones. The isotopic trend observed for carbonates in veins and deformation zones follows that shown by carbonates in host limestones, marbles, and other host rocks, increasing with increasing contribution of deep metamorphic crustal volatiles. At each crustal level, the composition of the infiltrating fluids is thus buffered by deeper metamorphic sources. A negative correlation between calcite {delta}{sup 13}C and fluid inclusion {sup 3}He/{sup 4}He is consistent with a mantle origin for a fraction of the infiltrating CO{sub 2}. Noble gas and stable isotope systematics show consistent evidence for the involvement of mantle-derived fluids combined with infiltration of deep metamorphic H{sub 2}O and CO{sub 2} in faulting, supporting the involvement of

  16. Iron-Rich Carbonates as the Potential Source of Evolved CO2 Detected by the Sample Analysis at Mars (SAM) Instrument in Gale Crater

    Science.gov (United States)

    Sutter, B.; Heil, E.; Rampe, E. B.; Morris, R. V.; Ming, D. W.; Archer, P. D.; Eigenbrode, J. L.; Franz, H. B.; Glavin, D. P.; McAdam, A. C.; Navarro-Gonzalez, R.; Niles, P. B.; Mahaffy, P. R.; Stern, J. C.; Mertzman, S.

    2015-01-01

    The Sample Analysis at Mars (SAM) instrument detected at least 4 distinct CO2 release during the pyrolysis of a sample scooped from the Rocknest (RN) eolian deposit. The highest peak CO2 release temperature (478-502 C) has been attributed to either a Fe-rich carbonate or nano-phase Mg-carbonate. The objective of this experimental study was to evaluate the thermal evolved gas analysis (T/EGA) characteristics of a series of terrestrial Fe-rich carbonates under analog SAM operating conditions to compare with the RN CO2 releases. Natural Fe-rich carbonates (<53 microns) with varying Fe amounts (Fe(0.66)X(0.34)- to Fe(0.99)X(0.01)-CO3, where X refers to Mg and/or Mn) were selected for T/EGA. The carbonates were heated from 25 to 715 C (35 C/min) and evolved CO2 was measured as a function of temperature. The highest Fe containing carbonates (e.g., Fe(0.99)X(0.01)-CO3) yielded CO2 peak temperatures between 466-487 C, which is consistent with the high temperature RN CO2 release. The lower Fe-bearing carbonates (e.g., Fe(0.66)X(0.34)CO3) did not have peak CO2 release temperatures that matched the RN peak CO2 temperatures; however, their entire CO2 releases did occur within RN temperature range of the high temperature CO2 release. Results from this laboratory analog analysis demonstrate that the high temperature RN CO2 release is consistent with Fe-rich carbonate (approx.0.7 to 1 wt.% FeCO3). The similar RN geochemistry with other materials in Gale Crater and elsewhere on Mars (e.g., Gusev Crater, Meridiani) suggests that up to 1 wt. % Fe-rich carbonate may occur throughout the Gale Crater region and could be widespread on Mars. The Rocknest Fe-carbonate may have formed from the interaction of reduced Fe phases (e.g., Fe2+ bearing olivine) with atmospheric CO2 and transient water. Alternatively, the Rocknest Fe-carbonate could be derived by eolian processes that have eroded distally exposed deep crustal material that possesses Fe-carbonate that may have formed through

  17. Iron-rich Carbonates as the Potential Source of Evolved CO2 Detected by the Sample Analysis at Mars (SAM) instrument in Gale Crater.

    Science.gov (United States)

    Sutter, B.; Heil, E.; Rampe, E. B.; Morris, R. V.; Ming, D. W.; Archer, P. D., Jr.; Eigenbrode, J. L.; Franz, H. B.; Glavin, D. P.; McAdam, A.; Navarro-Gonzalez, R.; Mahaffy, P. R.; Stern, J. C.; Mertzman, S. A.

    2015-12-01

    The Sample Analysis at Mars (SAM) instrument detected at least 4 distinct CO2 release during the pyrolysis of a sample scooped from the Rocknest (RN) eolian deposit. The highest peak CO2 release temperature (478-502°C) has been attributed to either a Fe-rich carbonate or nano-phase Mg-carbonate. The objective of this experimental study was to evaluate the thermal evolved gas analysis (T/EGA) characteristics of a series of terrestrial Fe-rich carbonates under analog SAM operating conditions to compare with the RN CO2 releases. Natural Fe-rich carbonates (heated from 25 to 715°C (35°C min-1) and evolved CO2 was measured as a function of temperature. The highest Fe containing carbonates (e.g., Fe0.99X0.01-CO3) yielded CO2 peak temperatures between 466-487°C, which is consistent with the high temperature RN CO2 release. The lower Fe-bearing carbonates (e.g., Fe0.66X0.34CO3) did not have peak CO2 release temperatures that matched the RN peak CO2 temperatures; however, their entire CO2 releases did occur within RN temperature range of the high temperature CO2 release. Results from this laboratory analog analysis demonstrate that the high temperature RN CO2 release is consistent with Fe-rich carbonate (~0.7 to 1 wt.% FeCO3). The similar RN geochemistry with other materials in Gale Crater and elsewhere on Mars (e.g., Gusev Crater, Meridiani) suggests that up to 1 wt. % Fe-rich carbonate may occur throughout the Gale Crater region and could be widespread on Mars. The Rocknest Fe-carbonate may have formed from the interaction of reduced Fe phases (e.g., Fe2+ bearing olivine) with atmospheric CO2 and transient water. Alternatively, the Rocknest Fe-carbonate could be derived by eolian processes that have eroded distally exposed deep crustal material that possesses Fe-carbonate that may have formed through metamorphic and/or metasomatic processes.

  18. Coupled reservoir-geomechanical analysis of CO2 injection and ground deformations at In Salah, Algeria

    Energy Technology Data Exchange (ETDEWEB)

    Rutqvist, J.; Vasco, D.W.; Myer, L.

    2009-11-01

    In Salah Gas Project in Algeria has been injecting 0.5-1 million tonnes CO{sub 2} per year over the past five years into a water-filled strata at a depth of about 1,800 to 1,900 m. Unlike most CO{sub 2} storage sites, the permeability of the storage formation is relatively low and comparatively thin with a thickness of about 20 m. To ensure adequate CO{sub 2} flow-rates across the low-permeability sand-face, the In Salah Gas Project decided to use long-reach (about 1 to 1.5 km) horizontal injection wells. In an ongoing research project we use field data and coupled reservoir-geomechanical numerical modeling to assess the effectiveness of this approach and to investigate monitoring techniques to evaluate the performance of a CO{sub 2}-injection operation in relatively low permeability formations. Among the field data used are ground surface deformations evaluated from recently acquired satellite-based inferrometry (InSAR). The InSAR data shows a surface uplift on the order of 5 mm per year above active CO{sub 2} injection wells and the uplift pattern extends several km from the injection wells. In this paper we use the observed surface uplift to constrain our coupled reservoir-geomechanical model and conduct sensitivity studies to investigate potential causes and mechanisms of the observed uplift. The results of our analysis indicates that most of the observed uplift magnitude can be explained by pressure-induced, poro-elastic expansion of the 20 m thick injection zone, but there could also be a significant contribution from pressure-induced deformations within a 100 m thick zone of shaly sands immediately above the injection zone.

  19. No-tillage lessens soil CO2 emissions the most under arid and sandy soil conditions: results from a meta-analysis

    Science.gov (United States)

    Abdalla, Khatab; Chivenge, Pauline; Ciais, Philippe; Chaplot, Vincent

    2016-06-01

    The management of agroecosystems plays a crucial role in the global carbon cycle with soil tillage leading to known organic carbon redistributions within soils and changes in soil CO2 emissions. Yet, discrepancies exist on the impact of tillage on soil CO2 emissions and on the main soil and environmental controls. A meta-analysis was conducted using 46 peer-reviewed publications totaling 174 paired observations comparing CO2 emissions over entire seasons or years from tilled and untilled soils across different climates, crop types and soil conditions with the objective of quantifying tillage impact on CO2 emissions and assessing the main controls. On average, tilled soils emitted 21 % more CO2 than untilled soils, which corresponded to a significant difference at Ptillage had no impact on CO2 fluxes in clayey soils with high background SOCC (> 3 %). Finally, nitrogen fertilization and crop residue management had little effect on the CO2 responses of soils to no-tillage. These results suggest no-tillage is an effective mitigation measure of carbon dioxide losses from dry land soils. They emphasize the importance of including information on soil factors such as texture, aggregate stability and organic carbon content in global models of the carbon cycle.

  20. Geochemical signatures of the diffuse CO2 emission from Brava volcanic system, Cape Verde

    Science.gov (United States)

    Rodriguez, F.; Bandomo, Z.; Barros, I.; Dias Fonseca, J.; Fernandes, P.; Rodrigues, J.; Melian Rodriguez, G.; Padron, E.; Dionis, S.; Sonia, S.; Gonçalves, A.; Fernandes, A.; Hernandez Perez, P. A.; Perez, N.

    2010-12-01

    Brava (67 km2) the smallest of the populated Cape Verde islands, lies at the southwestern end of the archipelagic crescent. Brava volcanic system has no documented historical eruptions, but its youthful volcanic morphology and the fact that earthquake swarms still occur indicate the potential for future eruptions. A geochemical survey of diffuse gas emissions was carried out in Brava island during February and March 2010. For this survey 228 sampling sites were selected all over the island to perform soil CO2 efflux measurements, using a portable accumulation chamber and an IR sensor, and soil temperature measurements at a depth of 30-50 cm. Soil gas samples were collected at 40 cm depth for chemical (He, H2, N2, CO2, CH4, Ar and O2) and isotopic (δ13C-CO2) analysis in 32 selected sampling sites. CO2 efflux values ranged from non-detectable up to 1.343 g m-2 d-1. To quantify the total diffuse CO2 emission from Brava volcanic system, a CO2 efflux map was constructed using sequential Gaussian simulations (sGs). Most of the studied area showed background levels of CO2 efflux (˜2 g m-2 d-1), while peak levels (>1300 g m-2 d-1) were mainly identified at Vinagre and Baleia areas. The total diffuse CO2 output from Brava volcanic system was estimated about 41.6 t d-1. The analysis of the carbon isotopic signature of the CO2 in the soil atmosphere provides an insight for evaluating the origin of the diffuse CO2 emission. Observed δ13C-CO2 values ranged from -20.86 to -1.26 ‰. A binary plot of CO2 concentrations versus δ13C-CO2 values allows us to represent three major geochemical reservoirs (atmospheric air, volcanic gas, and biogenic gas) and their related mixing lines. The chemical and isotopic analysis of Brava soil gas samples suggest a mixing with deep-seated CO2 and biogenic gas for the diffuse CO2 emission from Brava volcanic system. The lack of visible volcanic gas emission in Brava highlights the importance of monitoring diffuse CO2 emission to improve its

  1. Sensitivity analysis of modelled responses of vegetation dynamics on the Tibetan Plateau to doubled CO2 and associated climate change

    Science.gov (United States)

    Qiu, Linjing; Liu, Xiaodong

    2016-04-01

    Increases in the atmospheric CO2 concentration affect both the global climate and plant metabolism, particularly for high-altitude ecosystems. Because of the limitations of field experiments, it is difficult to evaluate the responses of vegetation to CO2 increases and separate the effects of CO2 and associated climate change using direct observations at a regional scale. Here, we used the Community Earth System Model (CESM, version 1.0.4) to examine these effects. Initiated from bare ground, we simulated the vegetation composition and productivity under two CO2 concentrations (367 and 734 ppm) and associated climate conditions to separate the comparative contributions of doubled CO2 and CO2-induced climate change to the vegetation dynamics on the Tibetan Plateau (TP). The results revealed whether the individual effect of doubled CO2 and its induced climate change or their combined effects caused a decrease in the foliage projective cover (FPC) of C3 arctic grass on the TP. Both doubled CO2 and climate change had a positive effect on the FPC of the temperate and tropical tree plant functional types (PFTs) on the TP, but doubled CO2 led to FPC decreases of C4 grass and broadleaf deciduous shrubs, whereas the climate change resulted in FPC decrease in C3 non-arctic grass and boreal needleleaf evergreen trees. Although the combination of the doubled CO2 and associated climate change increased the area-averaged leaf area index (LAI), the effect of doubled CO2 on the LAI increase (95 %) was larger than the effect of CO2-induced climate change (5 %). Similarly, the simulated gross primary productivity (GPP) and net primary productivity (NPP) were primarily sensitive to the doubled CO2, compared with the CO2-induced climate change, which alone increased the regional GPP and NPP by 251.22 and 87.79 g C m-2 year-1, respectively. Regionally, the vegetation response was most noticeable in the south-eastern TP. Although both doubled CO2 and associated climate change had a

  2. Research Progress and Technical Analysis of High Temperature Solar Thermochemical CO2-splitting Cycle%太阳热化学循环反应分解CO2的研究进展与技术分析

    Institute of Scientific and Technical Information of China (English)

    陈伟; 张军

    2012-01-01

    在全球气候变化已成为国际性热点问题的大背景下,通过将CO2转化成高附加值的燃料,实现CO2的资源化利用是解决这一问题的可行途径之一,而将这一过程与太阳能利用相结合有助于解决因CO2化学惰性较强,其转化在热力学上不利带来能耗较高的挑战.在多种利用太阳能将CO2转化为能源载体的方法中,利用高温太阳热能进行两步热化学循环反应分解CO2以制取合成燃料是一个新兴研究方向.本文详细介绍了国外科研机构在这方面的发展现状及研究重点,并对该技术的原理和未来需要开展的基础研究工作进行了分析.未来的研究重点将集中在:(1)开展多相化学反应流辐射热传递的理论和试验基础研究;(2)设计直接受辐射的太阳能化学反应器,可直接吸收聚焦的太阳热能,辐射热传递效率较高;(3)开展高温太阳能化学反应器的材料研究.国内具有一定太阳能高温热(化学)利用工作基础的研究机构有必要开展这一领域的研究工作,为中国实现碳减排做出贡献.%In the context of the global climate change, as an international hot issue, the CO; utiliiation through its conversion into high value-added fuels is one of the possible ways to solve this problem. C02 is chemically inerl and it is difficult to convert it into other molecules thermodynamically, and these problems can be solved through the use of the solar energy. Among various approaches on converting CO2 into an energy carrier by the solar energy, a promising new method is developed for the production of the synthetic fuel from solar-driven two-step CO2-splitting thermo-chemieal cycles. In this paper, first review the research progress and research priorities in this field- We also analyzethe technical principle and the basic studies thai are required in the future. The furure research should focus on: (1) (he fundamental analysis of the radiation heat exchange coupled with the

  3. U.S. regional greenhouse gas emissions analysis comparing highly resolved vehicle miles traveled and CO2 emissions: mitigation implications and their effect on atmospheric measurements

    Science.gov (United States)

    Mendoza, D. L.; Gurney, K. R.

    2010-12-01

    Carbon dioxide (CO2) is the most abundant anthropogenic greenhouse gas and projections of fossil fuel energy demand show CO2 concentrations increasing indefinitely into the future. After electricity production, the transportation sector is the second largest CO2 emitting economic sector in the United States, accounting for 32.3% of the total U.S. emissions in 2002. Over 80% of the transport sector is composed of onroad emissions, with the remainder shared by the nonroad, aircraft, railroad, and commercial marine vessel transportation. In order to construct effective mitigation policy for the onroad transportation sector and more accurately predict CO2 emissions for use in transport models and atmospheric measurements, analysis must incorporate the three components that determine the CO2 onroad transport emissions: vehicle fleet composition, average speed of travel, and emissions regulation strategies. Studies to date, however, have either focused on one of these three components, have been only completed at the national scale, or have not explicitly represented CO2 emissions instead relying on the use of vehicle miles traveled (VMT) as an emissions proxy. National-level projections of VMT growth is not sufficient to highlight regional differences in CO2 emissions growth due to the heterogeneity of vehicle fleet and each state’s road network which determines the speed of travel of vehicles. We examine how an analysis based on direct CO2 emissions and an analysis based on VMT differ in terms of their emissions and mitigation implications highlighting potential biases introduced by the VMT-based approach. This analysis is performed at the US state level and results are disaggregated by road and vehicle classification. We utilize the results of the Vulcan fossil fuel CO2 emissions inventory which quantified emissions for the year 2002 across all economic sectors in the US at high resolution. We perform this comparison by fuel type,12 road types, and 12 vehicle types

  4. Field-based stable isotope analysis of carbon dioxide by mid-infrared laser spectroscopy for carbon capture and storage monitoring.

    Science.gov (United States)

    van Geldern, Robert; Nowak, Martin E; Zimmer, Martin; Szizybalski, Alexandra; Myrttinen, Anssi; Barth, Johannes A C; Jost, Hans-Jürg

    2014-12-16

    A newly developed isotope ratio laser spectrometer for CO2 analyses has been tested during a tracer experiment at the Ketzin pilot site (northern Germany) for CO2 storage. For the experiment, 500 tons of CO2 from a natural CO2 reservoir was injected in supercritical state into the reservoir. The carbon stable isotope value (δ(13)C) of injected CO2 was significantly different from background values. In order to observe the breakthrough of the isotope tracer continuously, the new instruments were connected to a stainless steel riser tube that was installed in an observation well. The laser instrument is based on tunable laser direct absorption in the mid-infrared. The instrument recorded a continuous 10 day carbon stable isotope data set with 30 min resolution directly on-site in a field-based laboratory container during a tracer experiment. To test the instruments performance and accuracy the monitoring campaign was accompanied by daily CO2 sampling for laboratory analyses with isotope ratio mass spectrometry (IRMS). The carbon stable isotope ratios measured by conventional IRMS technique and by the new mid-infrared laser spectrometer agree remarkably well within analytical precision. This proves the capability of the new mid-infrared direct absorption technique to measure high precision and accurate real-time stable isotope data directly in the field. The laser spectroscopy data revealed for the first time a prior to this experiment unknown, intensive dynamic with fast changing δ(13)C values. The arrival pattern of the tracer suggest that the observed fluctuations were probably caused by migration along separate and distinct preferential flow paths between injection well and observation well. The short-term variances as observed in this study might have been missed during previous works that applied laboratory-based IRMS analysis. The new technique could contribute to a better tracing of the migration of the underground CO2 plume and help to ensure the long

  5. CO2 Fluxes and Concentrations in a Residential Area in the Southern Hemisphere

    Science.gov (United States)

    Weissert, L. F.; Salmond, J. A.; Turnbull, J. C.; Schwendenmann, L.

    2014-12-01

    While cities are generally major sources of anthropogenic carbon dioxide (CO2) emissions, recent research has shown that parts of urban areas may also act as CO2 sinks due to CO2 uptake by vegetation. However, currently available results are related to a large degree of uncertainty due to the limitations of the applied methods and the limited number of studies available from urban areas, particularly from the southern hemisphere. In this study, we explore the potential of eddy covariance and tracer measurements (13C and 14C isotopes of CO2) to quantify and partition CO2 fluxes and concentrations in a residential urban area in Auckland, New Zealand. Based on preliminary results from autumn and winter (March to July 2014) the residential area is a small source of CO2 (0.11 mol CO2 m-2 day-1). CO2 fluxes and concentrations follow a distinct diurnal cycle with a morning peak between 7:00 and 9:00 (max: 0.25 mol CO2 m-2 day-1/412 ppm) and midday low with negative CO2 fluxes (min: -0.17 mol CO2 m-2 day-1/392 ppm) between 10:00 and 15:00 local time, likely due to photosynthetic CO2 uptake by local vegetation. Soil CO2 efflux may explain that CO2 concentrations increase and remain high (401 ppm) throughout the night. Mean diurnal winter δ13C values are in anti-phase with CO2 concentrations and vary between -9.0 - -9.7‰. The depletion of δ13C compared to clean atmospheric air (-8.2‰) is likely a result of local CO2 sources dominated by gasoline combustion (appr. 60%) during daytime. A sector analysis (based on prevailing wind) of CO2 fluxes and concentrations indicates lower CO2 fluxes and concentrations from the vegetation-dominated sector, further demonstrating the influence of vegetation on local CO2 concentrations. These results provide an insight into the temporal and spatial variability CO2 fluxes/concentrations and potential CO2 sinks and sources from a city in the southern hemisphere and add valuable information to the global database of urban CO2 fluxes.

  6. Modeled responses of terrestrial ecosystems to elevated atmospheric CO2: A comparison of simulations by the biogeochemistry models of the Vegetation/Ecosystem Modeling and Analysis Project (VEMAP)

    Science.gov (United States)

    Pan, Y.; Melillo, J.M.; McGuire, A.D.; Kicklighter, D.W.; Pitelka, L.F.; Hibbard, K.; Pierce, L.L.; Running, S.W.; Ojima, D.S.; Parton, W.J.; Schimel, D.S.; Borchers, J.; Neilson, R.; Fisher, H.H.; Kittel, T.G.F.; Rossenbloom, N.A.; Fox, S.; Haxeltine, A.; Prentice, I.C.; Sitch, S.; Janetos, A.; McKeown, R.; Nemani, R.; Painter, T.; Rizzo, B.; Smith, T.; Woodward, F.I.

    1998-01-01

    Although there is a great deal of information concerning responses to increases in atmospheric CO2 at the tissue and plant levels, there are substantially fewer studies that have investigated ecosystem-level responses in the context of integrated carbon, water, and nutrient cycles. Because our understanding of ecosystem responses to elevated CO2 is incomplete, modeling is a tool that can be used to investigate the role of plant and soil interactions in the response of terrestrial ecosystems to elevated CO2. In this study, we analyze the responses of net primary production (NPP) to doubled CO2 from 355 to 710 ppmv among three biogeochemistry models in the Vegetation/Ecosystem Modeling and Analysis Project (VEMAP): BIOME-BGC (BioGeochemical Cycles), Century, and the Terrestrial Ecosystem Model (TEM). For the conterminous United States, doubled atmospheric CO2 causes NPP to increase by 5% in Century, 8% in TEM, and 11% in BIOME-BGC. Multiple regression analyses between the NPP response to doubled CO2 and the mean annual temperature and annual precipitation of biomes or grid cells indicate that there are negative relationships between precipitation and the response of NPP to doubled CO2 for all three models. In contrast, there are different relationships between temperature and the response of NPP to doubled CO2 for the three models: there is a negative relationship in the responses of BIOME-BGC, no relationship in the responses of Century, and a positive relationship in the responses of TEM. In BIOME-BGC, the NPP response to doubled CO2 is controlled by the change in transpiration associated with reduced leaf conductance to water vapor. This change affects soil water, then leaf area development and, finally, NPP. In Century, the response of NPP to doubled CO2 is controlled by changes in decomposition rates associated with increased soil moisture that results from reduced evapotranspiration. This change affects nitrogen availability for plants, which influences NPP. In

  7. Radiocarbon-depleted CO2 evidence for fuel biodegradation at the Naval Air Station North Island (USA) fuel farm site.

    Science.gov (United States)

    Boyd, Thomas J; Pound, Michael J; Lohr, Daniel; Coffin, Richard B

    2013-05-01

    Dissolved CO(2) radiocarbon and stable carbon isotope ratios were measured in groundwater from a fuel contaminated site at the North Island Naval Air Station in San Diego, CA (USA). A background groundwater sampling well and 16 wells in the underground fuel contamination zone were evaluated. For each sample, a two end-member isotopic mixing model was used to determine the fraction of CO(2) derived from fossil fuel. The CO(2) fraction from fossil sources ranged from 8 to 93% at the fuel contaminated site, while stable carbon isotope values ranged from -14 to +5‰VPDB. Wells associated with highest historical and contemporary fuel contamination showed the highest fraction of CO(2) derived from petroleum (fossil) sources. Stable carbon isotope ratios indicated sub-regions on-site with recycled CO(2) (δ(13)CO(2) as high as +5‰VPDB) - most likely resulting from methanogenesis. Ancillary measurements (pH and cations) were used to determine that no fossil CaCO(3), for instance limestone, biased the analytical conclusions. Radiocarbon analysis is verified as a viable and definitive technique for confirming fossil hydrocarbon conversion to CO(2) (complete oxidation) at hydrocarbon-contaminated groundwater sites. The technique should also be very useful for assessing the efficacy of engineered remediation efforts and by using CO(2) production rates, contaminant mass conversion over time and per unit volume.

  8. Copper-catalyzed formic acid synthesis from CO2 with hydrosilanes and H2O.

    Science.gov (United States)

    Motokura, Ken; Kashiwame, Daiki; Miyaji, Akimitsu; Baba, Toshihide

    2012-05-18

    A copper-catalyzed formic acid synthesis from CO2 with hydrosilanes has been accomplished. The Cu(OAc)2·H2O-1,2-bis(diphenylphosphino)benzene system is highly effective for the formic acid synthesis under 1 atm of CO2. The TON value approached 8100 in 6 h. The reaction pathway was revealed by in situ NMR analysis and isotopic experiments.

  9. CO2 laser preionisation

    Science.gov (United States)

    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.

  10. 基于LCA的钢铁联合企业CO_2排放影响因素分析%Analysis of factors influencing CO_2 emissions in an integrated steel works based on Life Cycle Analysis (LCA)

    Institute of Scientific and Technical Information of China (English)

    黄志甲; 丁晓; 孙浩; 刘思玥; 刘颖昊; 刘涛

    2010-01-01

    钢铁企业是CO_2排放大户,减少吨钢CO_2排放是钢铁企业节约能源、保护环境、走可持续发展道路的必然要求.本研究旨在对钢铁企业产品生命周期清单研究的基础上,识别钢铁企业CO_2排放的主要影响因素,提出针对性的减排建议,以某钢铁联合企业的产品生命周期清单模型为平台,同时利用Tomado Chart工具,计算得到对企业CO_2排放影响较大的因素,然后提出了相应的减排措施.结果表明,转炉流程对于钢铁企业的影响要大于电炉流程;对该企业CO_2排放有重大影响和相关影响的因素有:高炉煤气(BFG)的CO_2排放系数、连铸坯的钢水单耗、热轧的板坯单耗、转炉的铁水比.减少钢铁联合企业CO_2排放的有效措施是采取捕集BFG中的CO_2、降低转炉的铁水比、加强副产煤气的回收以及优化企业的产品生产结构.

  11. Measurement of Swarm Parameters of c-C4F8/CO2 and Its Insulation Characteristics Analysis

    Institute of Scientific and Technical Information of China (English)

    ZHANG Liu-chun; XIAO Deng-ming; ZHANG Dong; WU Bian-tao

    2008-01-01

    In c-C4F8 and c-C4F8/CO2 mixtures, the swarm parameters including ionization coefficient, attachment coefficient and effective ionization coefficient were obtained at the ratio of the electric field strength to the gas density between 150-550 Td by the steady-state Townsend (SST) method. Static breakdown voltages at each ratio were also measured at the SST condition. The limiting field strengths were obtained by two methods:computing the density-normalized effective ionization coefficient as a function of the overall density-reduced electric field strength; and measuring static breakdown voltages as a function of the product of gas density and electrode separation. Good agreement was obtained by these two methods, which ensures the correctness of the former method. The limiting field strengths of c-C4F8 and c-C4F8/CO2 mixtures were compared with those ofpure SF6, SF6/CO2 mixtures and pure c-C4Fs. It is found that buffer gas CO2 does not reduce the limiting field strengths of c-C4F8 greatly, the limiting field strengths of c-C4F8/CO2 mixtures are higher than those of SF6/CO2 mixtures or even pure SF6, and so c-C4F8/CO2 mixtures are suggested to be possible substitutes for SF6.

  12. 东亚地区二氧化碳体积分数变化特征%Preliminary analysis of atmospheric CO2 variations in East Asia

    Institute of Scientific and Technical Information of China (English)

    党小晨; 张美根; 朱彬

    2012-01-01

    Based on observed atmospheric CO2 concentrations at 10 background stations in East Asia, temporal and spatial variations in atmospheric CO2 are analyzed, and impacts of the underlying surface, source and sink upon at-mospheric CO2 levels are also discussed. Analysis results reveal that the monthly averaged CO2 concentrations at the observation stations exhibit strong seasonal variations. The higher values appear in cold seasons such as winter and spring,while the lower values present from July to September,i. e. ,summer in northern hemisphere. Diurnal varia-tions in CO2 concentrations are approximately same at these stations. The concentration reaches its lowest at about 15 ;00 LST (Local Standard Time) ,and then goes up constantly during night and reaches its highest at 7:00 LST, and after that it decreases subsequently with the radiation strengthens. There are inverse relationships between the mean CO2 concentration and the vegetable amount of underlying surface, and between the range of the daily concen-tration variation and the vegetable amount, respectively. The annually averaged CO2 concentration rose constantly from 2004 to 2008 at Mt. Waliguan,one of global background stations,with an increase rate of 2. 28 x 10-6/a.%利用2004年以来东亚地区10个本底观测站大气φ(CO2)观测资料,分析了各站大气φ( CO2)的变化特征及其各站之间的差异,讨论了下垫面特征、源汇作用等对φ(CO2)变化的影响.结果表明:10个本底站大气月均φ(CO2)有明显的季节变化,高值多出现在冬春等寒冷季节,而低值则多出现在6-9月,属于北半球的夏季;大气φ(CO2)日变化趋势较为一致,15时(当地时间)前后达到全天最低,随后φ(CO2)升高,并在日落后继续积累,至清晨7时(当地时间)前后达到全天最高,之后φ(CO2)随着太阳辐射的增强而逐渐降低,且平均φ( CO2)水平与下垫面植被量成反比,φ(CO2)日变化的幅度与下垫面植被量成反比.作为全球基

  13. High-frequency analysis of the complex linkage between soil CO(2) fluxes, photosynthesis and environmental variables.

    Science.gov (United States)

    Martin, Jonathan G; Phillips, Claire L; Schmidt, Andres; Irvine, James; Law, Beverly E

    2012-01-01

    High-frequency soil CO(2) flux data are valuable for providing new insights into the processes of soil CO(2) production. A record of hourly soil CO(2) fluxes from a semi-arid ponderosa pine stand was spatially and temporally deconstructed in attempts to determine if variation could be explained by logical drivers using (i) CO(2) production depths, (ii) relationships and lags between fluxes and soil temperatures, or (iii) the role of canopy assimilation in soil CO(2) flux variation. Relationships between temperature and soil fluxes were difficult to establish at the hourly scale because diel cycles of soil fluxes varied seasonally, with the peak of flux rates occurring later in the day as soil water content decreased. Using a simple heat transport/gas diffusion model to estimate the time and depth of CO(2) flux production, we determined that the variation in diel soil CO(2) flux patterns could not be explained by changes in diffusion rates or production from deeper soil profiles. We tested for the effect of gross ecosystem productivity (GEP) by minimizing soil flux covariance with temperature and moisture using only data from discrete bins of environmental conditions (±1 °C soil temperature at multiple depths, precipitation-free periods and stable soil moisture). Gross ecosystem productivity was identified as a possible driver of variability at the hourly scale during the growing season, with multiple lags between ~5, 15 and 23 days. Additionally, the chamber-specific lags between GEP and soil CO(2) fluxes appeared to relate to combined path length for carbon flow (top of tree to chamber center). In this sparse and heterogeneous forested system, the potential link between CO(2) assimilation and soil CO(2) flux may be quite variable both temporally and spatially. For model applications, it is important to note that soil CO(2) fluxes are influenced by many biophysical factors, which may confound or obscure relationships with logical environmental drivers and act at

  14. Analysis of Sensitive CO2 Pathways and Genes Related to Carbon Uptake and Accumulation in Chlamydomonas reinhardtii through Genomic Scale Modeling and Experimental Validation

    Science.gov (United States)

    Winck, Flavia V.; Melo, David O. Páez; Riaño-Pachón, Diego M.; Martins, Marina C. M.; Caldana, Camila; Barrios, Andrés F. González

    2016-01-01

    The development of microalgae sustainable applications needs better understanding of microalgae biology. Moreover, how cells coordinate their metabolism toward biomass accumulation is not fully understood. In this present study, flux balance analysis (FBA) was performed to identify sensitive metabolic pathways of Chlamydomonas reinhardtii under varied CO2 inputs. The metabolic network model of Chlamydomonas was updated based on the genome annotation data and sensitivity analysis revealed CO2 sensitive reactions. Biological experiments were performed with cells cultivated at 0.04% (air), 2.5, 5, 8, and 10% CO2 concentration under controlled conditions and cell growth profiles and biomass content were measured. Pigments, lipids, proteins, and starch were further quantified for the reference low (0.04%) and high (10%) CO2 conditions. The expression level of candidate genes of sensitive reactions was measured and validated by quantitative real time PCR. The sensitive analysis revealed mitochondrial compartment as the major affected by changes on the CO2 concentrations and glycolysis/gluconeogenesis, glyoxylate, and dicarboxylate metabolism among the affected metabolic pathways. Genes coding for glycerate kinase (GLYK), glycine cleavage system, H-protein (GCSH), NAD-dependent malate dehydrogenase (MDH3), low-CO2 inducible protein A (LCIA), carbonic anhydrase 5 (CAH5), E1 component, alpha subunit (PDC3), dual function alcohol dehydrogenase/acetaldehyde dehydrogenase (ADH1), and phosphoglucomutase (GPM2), were defined, among other genes, as sensitive nodes in the metabolic network simulations. These genes were experimentally responsive to the changes in the carbon fluxes in the system. We performed metabolomics