WorldWideScience

Sample records for models co2 concentration

  1. Simulation of CO2 concentrations at Tsukuba tall tower using WRF-CO2 tracer transport model

    Indian Academy of Sciences (India)

    Srabanti Ballav; Prabir K Patra; Yousuke Sawa; Hidekazu Matsueda; Ahoro Adachi; Shigeru Onogi; Masayuki Takigawa; Utpal K De

    2016-02-01

    Simulation of carbon dioxide (CO2) at hourly/weekly intervals and fine vertical resolution at the continental or coastal sites is challenging because of coarse horizontal resolution of global transport models. Here the regional Weather Research and Forecasting (WRF) model coupled with atmospheric chemistry is adopted for simulating atmospheric CO2 (hereinafter WRF-CO2) in nonreactive chemical tracer mode. Model results at horizontal resolution of 27 × 27 km and 31 vertical levels are compared with hourly CO2 measurements from Tsukuba, Japan (36.05°N, 140.13°E) at tower heights of 25 and 200 m for the entire year 2002. Using the wind rose analysis, we find that the fossil fuel emission signal from the megacity Tokyo dominates the diurnal, synoptic and seasonal variations observed at Tsukuba. Contribution of terrestrial biosphere fluxes is of secondary importance for CO2 concentration variability. The phase of synoptic scale variability in CO2 at both heights are remarkably well simulated the observed data (correlation coefficient >0.70) for the entire year. The simulations of monthly mean diurnal cycles are in better agreement with the measurements at lower height compared to that at the upper height. The modelled vertical CO2 gradients are generally greater than the observed vertical gradient. Sensitivity studies show that the simulation of observed vertical gradient can be improved by increasing the number of vertical levels from 31 in the model WRF to 37 (4 below 200 m) and using the Mellor–Yamada–Janjic planetary boundary scheme. These results have large implications for improving transport model simulation of CO2 over the continental sites.

  2. Modeling atmospheric CO2 concentration profiles and fluxes above sloping terrain at a boreal site

    Directory of Open Access Journals (Sweden)

    T. Aalto

    2006-01-01

    Full Text Available CO2 fluxes and concentrations were simulated in the planetary boundary layer above subarctic hilly terrain using a three dimensional model. The model solves the transport equations in the local scale and includes a vegetation sub-model. A WMO/GAW background concentration measurement site and an ecosystem flux measurement site are located inside the modeled region at a hilltop and above a mixed boreal forest, respectively. According to model results, the concentration measurement at the hill site was representative for continental background. However, this was not the case for the whole model domain. Concentration at few meters above active vegetation represented mainly local variation. Local variation became inseparable from the regional signal at about 60-100 m above ground. Flow over hills changed profiles of environmental variables and height of inversion layer, however CO2 profiles were more affected by upwind land use than topography. The hill site was above boundary layer during night and inside boundary layer during daytime. The CO2 input from model lateral boundaries dominated in both cases. Daily variation in the CO2 assimilation rate was clearly seen in the CO2 profiles. Concentration difference between the hill site and the forest site was about 5ppm during afternoon according to both model and measurements. The average modeled flux to the whole model region was about 40% of measured and modeled local flux at the forest site.

  3. 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...

  4. Experimental and modeling study of NO emission under high CO2 concentration

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    An experimental and numerical study of the NOx formation and reduction process in a designed coal combustion furnace under both traditional air atmosphere and O2/CO2 atmosphere was conducted, in an attempt to explore the chemistry mechanism of the experimentally observed NOx suppression under high CO2 concentration atmospheres. A simplified ‘chemically oriented’ approach, computational fluid dynamics (CFD)-chemical kinetics modeling method, was validated and used to model the experimental process. The high CO2 concentration’s chemical effect on NO reduction has been studied, and the differences in NOx reaction behaviors between O2/CO2 atmosphere and air atmosphere were analyzed by detailed chemical kinetic model. On the basis of investigations through elementary chemical reactions, it can be concluded that high CO2 concentration plays an important role on NOx conversion process during oxy-fuel combustion. Moreover, the dominant reaction steps and the most important reactions for NO conversion under different atmospheres were discussed. Under O2/CO2 atmosphere, the main active sequence for NO reaction includes: NO→N→N2, and the main active path for NO reaction under air atmosphere is through N2→N→NO.

  5. Quantification and modelling of on-road CO2 emissions and its impacts on ambient CO2 concentrations in an Indian coastal city

    Science.gov (United States)

    Madhipatla, K. K.

    2015-12-01

    This paper presents the results of CO2 emission inventory, monitoring of CO2 concentrations and modelling of on road CO2 emissions in an Indian coastal city. Bottom up approach was adopted for quantifying the grid wise on road CO2 emissions of Chennai city at a finer resolution of 1Km x 1Km using the real time traffic data of 56 major roads. In addition, monitoring of ground level CO2 concentrations and vehicular traffic were carried out at a residential site in Chennai to understand the impact of vehicular emissions on the ambient CO2 levels. Further, AERMOD, a US EPA regulatory model, was deployed to find the spatial variation of CO2 concentrations due to the emissions from 38 major corridors of Chennai. Results indicated that a total emission of 0.65 Tg/year of CO2 was emitted by the vehicular traffic from the major roads of Chennai. Cars were identified as the larger emitters of CO2 with a contribution of 25% of the total emissions followed by three wheelers (21%), trucks (16%), buses (15%), two wheelers (13%) and Light Commercial Vehicles (9%). Ground level CO2 concentrations at the study area were in the range 391.52 to 666.37 ppm, with a mean hourly concentration of 448 ± 33.45 ppm. It was observed that the CO2 concentrations were high during the morning and evening peak hours and low during the afternoons and further vehicular emissions were found to have a significant effect on the ambient CO2 concentrations during the morning peak hours (R2=0.78) and afternoons (R2=0.50). But, contrastingly, a weak correlation was observed between the vehicular emissions and CO2 concentrations during the evening peak hours (R2=0.02). In addition, night time CO2 concentrations were observed higher in the weekends corresponding to high vehicular traffic during the late evenings. From the modelling results, it was found that the considered 38 major corridors contribute 0.12 ppm of CO2 per year to the ambient atmosphere.

  6. Modeling concentrations and fluxes of atmospheric CO2 in the North East Atlantic region

    DEFF Research Database (Denmark)

    Geels, C.; Christensen, J.H.; Hansen, A.W.

    2001-01-01

    As part of the Danish NEAREX project a three-dimensional Eulerian hemispheric air pollution model is used to study the transport and concentrations of atmospheric CO2 in the North East Atlantic region. The model domain covers the major part of the Northern Hemisphere and currently the model...... source types. Here the model setup and the used parameterizations will be described. The model is validated by comparing the results with atmospheric measurements from four monitoring stations in or close to the northern part of the North Atlantic. Some preliminary model results will be shown and shortly...... includes simple parameterizations of the main sinks and sources for atmospheric CO2. One of the objectives of the project is to study and maybe quantify the relative importance of the various sinks and source types and areas for this region. In order to do so the model has been run with differentiated...

  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. A model intercomparison of changes in the Atlantic thermohaline circulation in response to increasing atmospheric CO2 concentration

    OpenAIRE

    Gregory, J; Dixon, K; Stouffer, R.; Weaver, A.; E. Driesschaert; Eby, M.; Fichefet, T.; Hasumi, H.; Hu, A.; J. Jungclaus; Kamenkovich, I.; A. Levermann; Montoya, M.; Murakami, S.; Nawrath , S.

    2005-01-01

    As part of the Coupled Model Intercomparison Project, integrations with a common design have been undertaken with eleven different climate models to compare the response of the Atlantic thermohaline circulation ( THC) to time-dependent climate change caused by increasing atmospheric CO2 concentration. Over 140 years, during which the CO2 concentration quadruples, the circulation strength declines gradually in all models, by between 10 and 50%. No model shows a rapid or complete collapse, desp...

  9. A reduced order model to analytically infer atmospheric CO2 concentration from stomatal and climate data

    Science.gov (United States)

    Konrad, Wilfried; Katul, Gabriel; Roth-Nebelsick, Anita; Grein, Michaela

    2017-06-01

    To address questions related to the acceleration or deceleration of the global hydrological cycle or links between the carbon and water cycles over land, reliable data for past climatic conditions based on proxies are required. In particular, the reconstruction of palaeoatmospheric CO2 content (Ca) is needed to assist the separation of natural from anthropogenic Ca variability and to explore phase relations between Ca and air temperature Ta time series. Both Ta and Ca are needed to fingerprint anthropogenic signatures in vapor pressure deficit, a major driver used to explain acceleration or deceleration phases in the global hydrological cycle. Current approaches to Ca reconstruction rely on a robust inverse correlation between measured stomatal density in leaves (ν) of many plant taxa and Ca. There are two methods that exploit this correlation: The first uses calibration curves obtained from extant species assumed to represent the fossil taxa, thereby restricting the suitable taxa to those existing today. The second is a hybrid eco-hydrological/physiological approach that determines Ca with the aid of systems of equations based on quasi-instantaneous leaf-gas exchange theories and fossil stomatal data collected along with other measured leaf anatomical traits and parameters. In this contribution, a reduced order model (ROM) is proposed that derives Ca from a single equation incorporating the aforementioned stomatal data, basic climate (e.g. temperature), estimated biochemical parameters of assimilation and isotope data. The usage of the ROM is then illustrated by applying it to isotopic and anatomical measurements from three extant species. The ROM derivation is based on a balance between the biochemical demand and atmospheric supply of CO2 that leads to an explicit expression linking stomatal conductance to internal CO2 concentration (Ci) and Ca. The resulting expression of stomatal conductance from the carbon economy of the leaf is then equated to another

  10. Atmospheric CO2 concentration impacts on maize yield performance under dry conditions: do crop model simulate it right ?

    Science.gov (United States)

    Durand, Jean-Louis; Delusca, Kénel; Boote, Ken; Lizaso, Jon; Manderscheid, Remy; Jochaim Weigel, Hans; Ruane, Alex C.; Rosenzweig, Cynthia; Jones, Jim; Ahuja, Laj; Anapalli, Saseendran; Basso, Bruno; Baron, Christian; Bertuzzi, Patrick; Biernath, Christian; Deryng, Delphine; Ewert, Frank; Gaiser, Thomas; Gayler, Sebastian; Heinlein, Florian; Kersebaum, Kurt Christian; Kim, Soo-Hyung; Müller, Christoph; Nendel, Claas; Olioso, Albert; Priesack, Eckhart; Ramirez-Villegas, Julian; Ripoche, Dominique; Rötter, Reimund; Seidel, Sabine; Srivastava, Amit; Tao, Fulu; Timlin, Dennis; Twine, Tracy; Wang, Enli; Webber, Heidi; Zhao, Shigan

    2017-04-01

    In most regions of the world, maize yields are at risk of be reduced due to rising temperatures and reduced water availability. Rising temperature tends to reduce the length of the growth cycle and the amount of intercepted solar energy. Water deficits reduce the leaf area expansion, photosynthesis and sometimes, with an even more pronounced impact, severely reduce the efficiency of kernel set. In maize, the major consequence of atmospheric CO2 concentration ([CO2]) is the stomatal closure-induced reduction of leaf transpiration rate, which tends to mitigate those negative impacts. Indeed FACE studies report significant positive responses to CO2 of maize yields (and other C4 crops) under dry conditions only. Given the projections by climatologists (typically doubling of [CO2] by the end of this century) projected impacts must take that climate variable into account. However, several studies show a large incertitude in estimating the impact of increasing [CO2] on maize remains using the main crop models. The aim of this work was to compare the simulations of different models using input data from a FACE experiment conducted in Braunschweig during 2 years under limiting and non-limiting water conditions. Twenty modelling groups using different maize models were given the same instructions and input data. Following calibration of cultivar parameters under non-limiting water conditions and under ambient [CO2] treatments of both years, simulations were undertaken for the other treatments: High [ CO2 ] (550 ppm) 2007 and 2008 in both irrigation regimes, and DRY AMBIENT 2007 and 2008. Only under severe water deficits did models simulate an increase in yield for CO2 enrichment, which was associated with higher harvest index and, for those models which simulated it, higher grain number. However, the CO2 enhancement under water deficit simulated by the 20 models was 20 % at most and 10 % on average only, i.e. twice less than observed in that experiment. As in the experiment

  11. Key knowledge and data gaps in modelling the influence of CO2 concentration on the terrestrial carbon sink.

    Science.gov (United States)

    Pugh, T A M; Müller, C; Arneth, A; Haverd, V; Smith, B

    2016-09-20

    Primary productivity of terrestrial vegetation is expected to increase under the influence of increasing atmospheric carbon dioxide concentrations ([CO2]). Depending on the fate of such additionally fixed carbon, this could lead to an increase in terrestrial carbon storage, and thus a net terrestrial sink of atmospheric carbon. Such a mechanism is generally believed to be the primary global driver behind the observed large net uptake of anthropogenic CO2 emissions by the biosphere. Mechanisms driving CO2 uptake in the Terrestrial Biosphere Models (TBMs) used to attribute and project terrestrial carbon sinks, including that from increased [CO2], remain in large parts unchanged since those models were conceived two decades ago. However, there exists a large body of new data and understanding providing an opportunity to update these models, and directing towards important topics for further research. In this review we highlight recent developments in understanding of the effects of elevated [CO2] on photosynthesis, and in particular on the fate of additionally fixed carbon within the plant with its implications for carbon turnover rates, on the regulation of photosynthesis in response to environmental limitations on in-plant carbon sinks, and on emergent ecosystem responses. We recommend possible avenues for model improvement and identify requirements for better data on core processes relevant to the understanding and modelling of the effect of increasing [CO2] on the global terrestrial carbon sink. Copyright © 2016 The Authors. Published by Elsevier GmbH.. All rights reserved.

  12. Modeling and optimization of a concentrated solar supercritical CO2 power plant

    Science.gov (United States)

    Osorio, Julian D.

    Renewable energy sources are fundamental alternatives to supply the rising energy demand in the world and to reduce or replace fossil fuel technologies. In order to make renewable-based technologies suitable for commercial and industrial applications, two main challenges need to be solved: the design and manufacture of highly efficient devices and reliable systems to operate under intermittent energy supply conditions. In particular, power generation technologies based on solar energy are one of the most promising alternatives to supply the world energy demand and reduce the dependence on fossil fuel technologies. In this dissertation, the dynamic behavior of a Concentrated Solar Power (CSP) supercritical CO2 cycle is studied under different seasonal conditions. The system analyzed is composed of a central receiver, hot and cold thermal energy storage units, a heat exchanger, a recuperator, and multi-stage compression-expansion subsystems with intercoolers and reheaters between compressors and turbines respectively. The effects of operating and design parameters on the system performance are analyzed. Some of these parameters are the mass flow rate, intermediate pressures, number of compression-expansion stages, heat exchangers' effectiveness, multi-tank thermal energy storage, overall heat transfer coefficient between the solar receiver and the environment and the effective area of the recuperator. Energy and exergy models for each component of the system are developed to optimize operating parameters in order to lead to maximum efficiency. From the exergy analysis, the components with high contribution to exergy destruction were identified. These components, which represent an important potential of improvement, are the recuperator, the hot thermal energy storage tank and the solar receiver. Two complementary alternatives to improve the efficiency of concentrated solar thermal systems are proposed in this dissertation: the optimization of the system's operating

  13. Sensitivity of simulated CO2 concentration to regridding of global fossil fuel CO2 emissions

    Directory of Open Access Journals (Sweden)

    X. Zhang

    2014-06-01

    Full Text Available Errors in the specification or utilization of fossil fuel CO2 emissions within carbon budget or atmospheric CO2 inverse studies can alias the estimation of biospheric and oceanic carbon exchange. A key component in the simulation of CO2 concentrations arising from fossil fuel emissions is the spatial distribution of the emission near coastlines. Finite grid resolution can give rise to mismatches between the emissions and simulated atmospheric dynamics which differ over land or water. We test these mismatches by examining simulated global atmospheric CO2 concentration driven by two different approaches to regridding fossil fuel CO2 emissions. The two approaches are: (1 a commonly-used method that allocates emissions to gridcells with no attempt to ensure dynamical consistency with atmospheric transport; (2 an improved method that reallocates emissions to gridcells to ensure dynamically consistent results. Results show large spatial and temporal differences in the simulated CO2 concentration when comparing these two approaches. The emissions difference ranges from −30.3 Tg C gridcell−1 yr−1 (−3.39 kg C m−2 yr−1 to +30.0 Tg C gridcell−1 yr−1 (+2.6 kg C m−2 yr−1 along coastal margins. Maximum simulated annual mean CO2 concentration differences at the surface exceed ±6 ppm at various locations and times. Examination of the current CO2 monitoring locations during the local afternoon, consistent with inversion modeling system sampling and measurement protocols, finds maximum hourly differences at 38 stations exceed ±0.10 ppm with individual station differences exceeding −32 ppm. The differences implied by not accounting for this dynamical consistency problem are largest at monitoring sites proximal to large coastal urban areas and point sources. These results suggest that studies comparing simulated to observed atmospheric CO2 concentration, such as atmospheric CO2 inversions, must take measures to correct for this potential

  14. Estimation of background CO2 concentrations at the high alpine station Schneefernerhaus by atmospheric observations and inverse modelling

    Science.gov (United States)

    Giemsa, Esther; Jacobeit, Jucundus; Ries, Ludwig; Frank, Gabriele; Hachinger, Stephan; Meyer-Arnek, Julian

    2016-04-01

    In order to estimate the influence of Central European CO2 emissions, a new method to retrieve background concentrations based on statistics of radon-222 and backward trajectories is developed and applied to the CO2 observations at the alpine high-altitude research station Schneefernerhaus (2670 m a.s.l.). The reliable identification of baseline conditions is important for perceiving changes in time as well as in the sources and sinks of greenhouse gases and thereby assessing the efficiency of existing mitigation strategies. In the particular case of Central Europe, the analysis of background concentrations could add further insights on the question why background CO2 concentrations increased in the last few decades, despite a significant decrease in the reported emissions. Ongoing effort to define the baseline conditions has led to a variety of data selection techniques. In this diversity of data filtering concepts, a relatively recent data selection method effectively appropriates observations of radon-222 to reliably and unambiguously identify baseline air masses. Owing to its relatively constant emission rate from the ice-free land surface and its half-life of 3.8 days that is solely achieved through radioactive decay, the tropospheric background concentration of the inert radioactive gas is low and temporal variations caused by changes in atmospheric transport are precisely detectable. For defining the baseline air masses reaching the high alpine research station Schneefernerhaus, an objective analysis approach is applied to the two-hourly radon records. The CO2 values of days by the radon method associated with prevailing atmospheric background conditions result in the CO2 concentrations representing the least land influenced air masses. Additionally, three-dimensional back-trajectories were retrieved using the Lagrangian Particle Dispersion Model (LPDM) FLEXPART driven by analysis fields of the Global Forecast System (GFS) produced by the National Centers

  15. Responses to atmospheric CO2 concentrations in crop simulation models: a review of current simple and semicomplex representations and options for model development.

    Science.gov (United States)

    Vanuytrecht, Eline; Thorburn, Peter J

    2017-01-30

    Elevated atmospheric CO2 concentrations ([CO2 ]) cause direct changes in crop physiological processes (e.g. photosynthesis and stomatal conductance). To represent these CO2 responses, commonly used crop simulation models have been amended, using simple and semicomplex representations of the processes involved. Yet, there is no standard approach to and often poor documentation of these developments. This study used a bottom-up approach (starting with the APSIM framework as case study) to evaluate modelled responses in a consortium of commonly used crop models and illuminate whether variation in responses reflects true uncertainty in our understanding compared to arbitrary choices of model developers. Diversity in simulated CO2 responses and limited validation were common among models, both within the APSIM framework and more generally. Whereas production responses show some consistency up to moderately high [CO2 ] (around 700 ppm), transpiration and stomatal responses vary more widely in nature and magnitude (e.g. a decrease in stomatal conductance varying between 35% and 90% among models was found for [CO2 ] doubling to 700 ppm). Most notably, nitrogen responses were found to be included in few crop models despite being commonly observed and critical for the simulation of photosynthetic acclimation, crop nutritional quality and carbon allocation. We suggest harmonization and consideration of more mechanistic concepts in particular subroutines, for example, for the simulation of N dynamics, as a way to improve our predictive understanding of CO2 responses and capture secondary processes. Intercomparison studies could assist in this aim, provided that they go beyond simple output comparison and explicitly identify the representations and assumptions that are causal for intermodel differences. Additionally, validation and proper documentation of the representation of CO2 responses within models should be prioritized.

  16. An Analytical Model for the Distribution of CO2 Sources and Sinks, Fluxes, and Mean Concentration Within the Roughness Sub-Layer

    Science.gov (United States)

    Siqueira, Mario B.; Katul, Gabriel G.

    2010-04-01

    A one-dimensional analytical model that predicts foliage CO2 uptake rates, turbulent fluxes, and mean concentration throughout the roughness sub-layer (RSL), a layer that extends from the ground surface up to 5 h, where h is canopy height, is proposed. The model combines the mean continuity equation for CO2 with first-order closure principles for turbulent fluxes and simplified physiological and radiative transfer schemes for foliage uptake. This combination results in a second-order ordinary differential equation in which soil respiration ( R) and CO2 concentration well above the RSL are imposed as lower and upper boundary conditions, respectively. An inverse version of the model was tested against datasets from two contrasting ecosystems: a tropical forest ( h = 40m) and a managed irrigated rice canopy ( h = 0.7m), with good agreement noted between modelled and measured mean CO2 concentration profiles within the entire RSL. Sensitivity analysis on the model parameters revealed a plausible scaling regime between them and a dimensionless parameter defined by the ratio between external ( R) and internal (stomatal conductance) characteristics controlling the CO2 exchange process. The model can be used to infer the thickness of the RSL for CO2 exchange, the inequality in zero-plane displacement between CO2 and momentum, and its consequences on modelled CO2 fluxes. A simplified version of the solution is well suited for being incorporated into large-scale climate models. Furthermore, the model framework here can be used to a priori estimate relative contributions from the soil surface and the atmosphere to canopy-air CO2 concentration, thereby making it synergetic to stable isotopes studies.

  17. Improving ecophysiological simulation models to predict the impact of elevated atmospheric CO2 concentration on crop productivity

    NARCIS (Netherlands)

    Yin, X.

    2013-01-01

    Background - Process-based ecophysiological crop models are pivotal in assessing responses of crop productivity and designing strategies of adaptation to climate change. Most existing crop models generally over-estimate the effect of elevated atmospheric [CO2], despite decades of experimental resear

  18. How accurately do maize crop models simulate the interactions of atmospheric CO2 concentration levels with limited water supply on water use and yield?

    Science.gov (United States)

    This study assesses the ability of 21 crop models to capture the impact of elevated CO2 concentration ([CO218 ]) on maize yield and water use as measured in a 2-year Free Air Carbon dioxide Enrichment experiment conducted at the Thünen Institute in Braunschweig, Germany (Manderscheid et al. 2014). D...

  19. A wellbore flow model of CO2 separate injection with concentric dual tubes and its affecting factors%同心双管分注CO2井筒流动模型及影响因素

    Institute of Scientific and Technical Information of China (English)

    吴晗; 吴晓东; 王庆; 朱明; 方越

    2011-01-01

    In view of issues of the low efficiency and poor effect in the process of commingled CO2 injection, a CO2 separate injection with concentric dual tubes was proposed. On the basis of the heat transfer principle and fluid flow theory, a mathematical model considering CO2 phase change as flowing along the wellbore of concentric dual tubes and heat transfer was established, with which temperature and pressure distributions of CO2 along the annulus between inner and outer tubes and in the inner tubing string were calculated. Moreover, effects brought about by various factors, such as injection rate, injection temperature, injection pressure, assemblage of inner and outer tubes, interval of injection layers etc. , on the pressure and temperature of CO2 flowing both in the annulus between inner and outer tubes and in the inner tubing string were investigated as well. The results indicate that on condition that wellhead injection parameters of inner and outer tubes are the same, the bigger the diameter of the outer tube, the higher the temperature of the annulus between inner and outer tubes. If the diameter of the outer tube keeps constant, the pressure of the annulus will increase with decreasing the diameter of the inner tube that has a small influence on the temperature of the annulus. When inner and outer tubes have definite diameters, the wellhead injection rate, injection temperature and intervals of injection layers may all have significant effects on temperature and pressure distributions of the annulus and the inner tube, while the wellhead injection pressure affects them a little.%针对CO2笼统注入过程中效率低、效果差等问题,提出了同心双管分注CO2技术.根据热量传递原理和流体流动理论,建立了考虑CO2相态变化的同心双管井筒流动与传热的数学模型,利用该模型研究了CO2沿内外管环空和内油管的温度和压力分布规律,分析了井口注入量、注入温度、注入压力、内外管组合、注入层间距对CO

  20. Using an optimality model to understand medium and long-term responses of vegetation water use to elevated atmospheric CO2 concentrations

    Science.gov (United States)

    Schymanski, Stanislaus J.; Roderick, Michael L.; Sivapalan, Murugesu

    2015-01-01

    Vegetation has different adjustable properties for adaptation to its environment. Examples include stomatal conductance at short time scale (minutes), leaf area index and fine root distributions at longer time scales (days–months) and species composition and dominant growth forms at very long time scales (years–decades–centuries). As a result, the overall response of evapotranspiration to changes in environmental forcing may also change at different time scales. The vegetation optimality model simulates optimal adaptation to environmental conditions, based on the assumption that different vegetation properties are optimized to maximize the long-term net carbon profit, allowing for separation of different scales of adaptation, without the need for parametrization with observed responses. This paper discusses model simulations of vegetation responses to today's elevated atmospheric CO2 concentrations (eCO2) at different temporal scales and puts them in context with experimental evidence from free-air CO2 enrichment (FACE) experiments. Without any model tuning or calibration, the model reproduced general trends deduced from FACE experiments, but, contrary to the widespread expectation that eCO2 would generally decrease water use due to its leaf-scale effect on stomatal conductance, our results suggest that eCO2 may lead to unchanged or even increased vegetation water use in water-limited climates, accompanied by an increase in perennial vegetation cover. PMID:26019228

  1. Using an optimality model to understand medium and long-term responses of vegetation water use to elevated atmospheric CO2 concentrations.

    Science.gov (United States)

    Schymanski, Stanislaus J; Roderick, Michael L; Sivapalan, Murugesu

    2015-05-27

    Vegetation has different adjustable properties for adaptation to its environment. Examples include stomatal conductance at short time scale (minutes), leaf area index and fine root distributions at longer time scales (days-months) and species composition and dominant growth forms at very long time scales (years-decades-centuries). As a result, the overall response of evapotranspiration to changes in environmental forcing may also change at different time scales. The vegetation optimality model simulates optimal adaptation to environmental conditions, based on the assumption that different vegetation properties are optimized to maximize the long-term net carbon profit, allowing for separation of different scales of adaptation, without the need for parametrization with observed responses. This paper discusses model simulations of vegetation responses to today's elevated atmospheric CO2 concentrations (eCO2) at different temporal scales and puts them in context with experimental evidence from free-air CO2 enrichment (FACE) experiments. Without any model tuning or calibration, the model reproduced general trends deduced from FACE experiments, but, contrary to the widespread expectation that eCO2 would generally decrease water use due to its leaf-scale effect on stomatal conductance, our results suggest that eCO2 may lead to unchanged or even increased vegetation water use in water-limited climates, accompanied by an increase in perennial vegetation cover.

  2. Estimates of CO2 traffic emissions from mobile concentration measurements

    Science.gov (United States)

    Maness, H. L.; Thurlow, M. E.; McDonald, B. C.; Harley, R. A.

    2015-03-01

    We present data from a new mobile system intended to aid in the design of upcoming urban CO2-monitoring networks. Our collected data include GPS probe data, video-derived traffic density, and accurate CO2 concentration measurements. The method described here is economical, scalable, and self-contained, allowing for potential future deployment in locations without existing traffic infrastructure or vehicle fleet information. Using a test data set collected on California Highway 24 over a 2 week period, we observe that on-road CO2 concentrations are elevated by a factor of 2 in congestion compared to free-flow conditions. This result is found to be consistent with a model including vehicle-induced turbulence and standard engine physics. In contrast to surface concentrations, surface emissions are found to be relatively insensitive to congestion. We next use our model for CO2 concentration together with our data to independently derive vehicle emission rate parameters. Parameters scaling the leading four emission rate terms are found to be within 25% of those expected for a typical passenger car fleet, enabling us to derive instantaneous emission rates directly from our data that compare generally favorably to predictive models presented in the literature. The present results highlight the importance of high spatial and temporal resolution traffic data for interpreting on- and near-road concentration measurements. Future work will focus on transport and the integration of mobile platforms into existing stationary network designs.

  3. Investigation into optimal CO2 concentration for CO2 capture from aluminium production

    OpenAIRE

    Mathisen, Anette; Sørensen, Henriette; Melaaen, Morten Christian; Müller, Gunn-Iren

    2013-01-01

    Capture of CO2 from aluminum production has been simulated using Aspen Plus and Aspen Hysys. The technology used for aluminum production is the Hall-Héroult and the current cell design necessitates that large amounts of false air is supplied to the cells. This results in a CO2 concentration in the process gas at around 1 vol%, which is considered uneconomical for CO2 capture. Therefore, the aim of this investigation is to evaluate the CO2 capture from aluminum production when the process g...

  4. Sensitivity of simulated CO2 concentration to sub-annual variations in fossil fuel CO2 emissions

    Science.gov (United States)

    Zhang, X.; Gurney, K. R.; Rayner, P. J.; Baker, D. F.; Liu, Y.; Asefi-Najafabady, S.

    2014-12-01

    This study presents a sensitivity analysis of the impact of sub-annual fossil fuel CO2 emissions on simulated CO2 concentration using a global tracer transport model. Four sensitivity experiments were conducted to investigate the impact of three cyclic components (diurnal, weekly and monthly) and a complete cyclic component (the combination of the three) by comparing with a temporally "flat" fossil fuel CO2 emissions inventory. A complete exploration of these impacts is quantified at annual, seasonal, weekly and diurnal time scales of the CO2concentration for the surface, vertical profile and column-integral structure. Result shows an annual mean surface concentration difference varying from -1.35 ppm to 0.13 ppm at grid scale for the complete cyclic fossil fuel emissions, which is mainly driven by a large negative diurnal rectification and less positive seasonal rectification. The negative diurnal rectification is up to 1.45 ppm at grid scale and primarily due to the covariation of diurnal fossil fuel CO2 emissions and diurnal variations of vertical mixing. The positive seasonal rectification is up to 0.23 ppm at grid scale which is mainly driven by the monthly fossil fuel CO2emissions coupling with atmospheric transport. Both the diurnal and seasonal rectifier effects are indicated at local-to-regional scales with center at large source regions and extend to neighboring regions in mainly Northern Hemisphere. The diurnal fossil fuel CO2 emissions is found to significantly affect the simulated diurnal CO2 amplitude (up to 9.12 ppm at grid scale), which is primarily contributed by the minima concentration differences around local sunset time. Similarly, large impact on the seasonal CO2 amplitude (up to 6.11 ppm) is found at regional scale for the monthly fossil fuel emissions. An impact of diurnal fossil fuel CO2 emissions on simulated afternoon CO2 concentration is also identified by up to 1.13 ppm at local scales. The study demonstrates a large cyclic fossil fuel

  5. Global high-resolution simulations of CO2 and CH4 using a NIES transport model to produce a priori concentrations for use in satellite data retrievals

    Directory of Open Access Journals (Sweden)

    S. Maksyutov

    2013-01-01

    Full Text Available The Greenhouse gases Observing SATellite (GOSAT measures column-averaged dry air mole fractions of carbon dioxide and methane (XCO2 and XCH4, respectively. Since the launch of GOSAT, model-simulated three-dimensional concentrations from a National Institute for Environmental Studies offline tracer Transport Model (NIES TM have been used as a priori concentration data for operational near real-time retrievals of XCO2 and XCH4 from GOSAT short-wavelength infrared spectra at NIES. Although the choice of a priori profile has only a minor effect on retrieved XCO2 or XCH4, a realistic simulation with minimal deviation from observed data is desirable. In this paper, we describe the newly developed version of NIES TM that has been adapted to provide global and near real-time concentrations of CO2 and CH4 using a high-resolution meteorological dataset, the Grid Point Value (GPV prepared by the Japan Meteorological Agency. The spatial resolution of the NIES TM is set to 0.5° × 0.5° in the horizontal in order to utilise GPV data, which have a resolution of 0.5° × 0.5°, 21 pressure levels and a time interval of 3 h. GPV data are provided to the GOSAT processing system with a delay of several hours, and the near real-time model simulation produces a priori concentrations driven by diurnally varying meteorology. A priori variance–covariance matrices of CO2 and CH4 are also derived from the simulation outputs and observation-based reference data for each month of the year at a resolution of 0.5° × 0.5° and 21 pressure levels. Model performance is assessed by comparing simulation results with the GLOBALVIEW dataset and other observational data. The overall root-mean-square differences between model predictions and GLOBALVIEW analysis are estimated to be 1.45 ppm and 12.52 ppb for CO2 and CH4, respectively, and the seasonal correlation coefficients are 0.87 for CO2 and 0.53 for CH4. The model showed good performance particularly at oceanic and free

  6. CO2 dispersion modelling over Paris region within the CO2-MEGAPARIS project

    Directory of Open Access Journals (Sweden)

    L. Ammoura

    2012-10-01

    Full Text Available Accurate simulation of the spatial and temporal variability of tracer mixing ratios over urban areas is challenging, but essential in order to utilize CO2 measurements in an atmospheric inverse framework to better estimate regional CO2 fluxes. This study investigates the ability of a high-resolution model to simulate meteorological and CO2 fields around Paris agglomeration, during the March field campaign of the CO2-MEGAPARIS project. The mesoscale atmospheric model Meso-NH, running at 2 km horizontal resolution, is coupled with the Town-Energy Balance (TEB urban canopy scheme and with the Interactions between Soil, Biosphere and Atmosphere CO2-reactive (ISBA-A-gs surface scheme, allowing a full interaction of CO2 between the surface and the atmosphere. Statistical scores show a good representation of the Urban Heat Island (UHI and urban-rural contrasts. Boundary layer heights (BLH at urban, sub-urban and rural sites are well captured, especially the onset time of the BLH increase and its growth rate in the morning, that are essential for tall tower CO2 observatories. Only nocturnal BLH at sub-urban sites are slightly underestimated a few nights, with a bias less than 50 m. At Eiffel tower, the observed spikes of CO2 maxima occur every morning exactly at the time at which the Atmospheric Boundary Layer (ABL growth reaches the measurement height. The timing of the CO2 cycle is well captured by the model, with only small biases on CO2 concentrations, mainly linked to the misrepresentation of anthropogenic emissions, as the Eiffel site is at the heart of trafic emission sources. At sub-urban ground stations, CO2 measurements exhibit maxima at the beginning and at the end of each night, when the ABL is fully contracted, with a very strong spatio-temporal variability. The CO2 cycle at these sites is generally well reproduced by the model, even if some biases on the nocturnal maxima appear in the Paris plume parly due to small errors on the vertical

  7. CO2 dispersion modelling over Paris region within the CO2-MEGAPARIS project

    Science.gov (United States)

    Lac, C.; Donnelly, R. P.; Masson, V.; Pal, S.; Donier, S.; Queguiner, S.; Tanguy, G.; Ammoura, L.; Xueref-Remy, I.

    2012-10-01

    Accurate simulation of the spatial and temporal variability of tracer mixing ratios over urban areas is challenging, but essential in order to utilize CO2 measurements in an atmospheric inverse framework to better estimate regional CO2 fluxes. This study investigates the ability of a high-resolution model to simulate meteorological and CO2 fields around Paris agglomeration, during the March field campaign of the CO2-MEGAPARIS project. The mesoscale atmospheric model Meso-NH, running at 2 km horizontal resolution, is coupled with the Town-Energy Balance (TEB) urban canopy scheme and with the Interactions between Soil, Biosphere and Atmosphere CO2-reactive (ISBA-A-gs) surface scheme, allowing a full interaction of CO2 between the surface and the atmosphere. Statistical scores show a good representation of the Urban Heat Island (UHI) and urban-rural contrasts. Boundary layer heights (BLH) at urban, sub-urban and rural sites are well captured, especially the onset time of the BLH increase and its growth rate in the morning, that are essential for tall tower CO2 observatories. Only nocturnal BLH at sub-urban sites are slightly underestimated a few nights, with a bias less than 50 m. At Eiffel tower, the observed spikes of CO2 maxima occur every morning exactly at the time at which the Atmospheric Boundary Layer (ABL) growth reaches the measurement height. The timing of the CO2 cycle is well captured by the model, with only small biases on CO2 concentrations, mainly linked to the misrepresentation of anthropogenic emissions, as the Eiffel site is at the heart of trafic emission sources. At sub-urban ground stations, CO2 measurements exhibit maxima at the beginning and at the end of each night, when the ABL is fully contracted, with a very strong spatio-temporal variability. The CO2 cycle at these sites is generally well reproduced by the model, even if some biases on the nocturnal maxima appear in the Paris plume parly due to small errors on the vertical transport, or in

  8. Hazardous indoor CO2 concentrations in volcanic environments.

    Science.gov (United States)

    Viveiros, Fátima; Gaspar, João L; Ferreira, Teresa; Silva, Catarina

    2016-07-01

    Carbon dioxide is one of the main soil gases released silently and permanently in diffuse degassing areas, both in volcanic and non-volcanic zones. In the volcanic islands of the Azores (Portugal) several villages are located over diffuse degassing areas. Lethal indoor CO2 concentrations (higher than 10 vol %) were measured in a shelter located at Furnas village, inside the caldera of the quiescent Furnas Volcano (S. Miguel Island). Hazardous CO2 concentrations were detected not only underground, but also at the ground floor level. Multivariate regression analysis was applied to the CO2 and environmental time series recorded between April 2008 and March 2010 at Furnas village. The results show that about 30% of the indoor CO2 variation is explained by environmental variables, namely barometric pressure, soil water content and wind speed. The highest indoor CO2 concentrations were recorded during bad weather conditions, characterized by low barometric pressure together with rainfall periods and high wind speed. In addition to the spike-like changes observed on the CO2 time series, long-term oscillations were also identified and appeared to represent seasonal variations. In fact, indoor CO2 concentrations were higher during winter period when compared to the dry summer months. Considering the permanent emission of CO2 in various volcanic regions of the world, CO2 hazard maps are crucial and need to be accounted by the land-use planners and authorities.

  9. CO2 dispersion modelling over Paris region within the CO2-MEGAPARIS project

    Directory of Open Access Journals (Sweden)

    C. Lac

    2013-05-01

    sensitivity test without urban parameterisation removes the UHI and underpredicts nighttime BLH over urban and suburban sites, leading to large overestimation of nocturnal CO2 mixing ratio at the suburban sites (bias of +17 ppm. The agreement between observation and prediction for BLH and CO2 concentrations and urban–rural increments, both day and night, demonstrates the potential of using the urban mesoscale system in the context of inverse modelling

  10. CO2 dispersion modelling over Paris region within the CO2-MEGAPARIS project

    Science.gov (United States)

    Lac, C.; Donnelly, R. P.; Masson, V.; Pal, S.; Riette, S.; Donier, S.; Queguiner, S.; Tanguy, G.; Ammoura, L.; Xueref-Remy, I.

    2013-05-01

    urban parameterisation removes the UHI and underpredicts nighttime BLH over urban and suburban sites, leading to large overestimation of nocturnal CO2 mixing ratio at the suburban sites (bias of +17 ppm). The agreement between observation and prediction for BLH and CO2 concentrations and urban-rural increments, both day and night, demonstrates the potential of using the urban mesoscale system in the context of inverse modelling

  11. A simple model of the anthropogenically forced CO2 cycle

    Directory of Open Access Journals (Sweden)

    W. Weber

    2015-10-01

    Full Text Available From basic physical assumptions we derive a simple linear model of the global CO2 cycle without free parameters. It yields excellent agreement with the observations reported by the carbon dioxide information analysis center (CDIAC as time series of atmospheric CO2 growth, of sinks in the ocean and of absorption by the biosphere. The agreement extends from the year 1850 until present (2013. Based on anthropogenic CO2 emission scenarios until 2150, future atmospheric CO2 concentrations are calculated. As the model shows, and depending on the emission scenario, the airborne fraction of CO2 begins to decrease in the year ~ 2050 and becomes negative at the latest in ~ 2130. At the same time the concentration of the atmospheric CO2 will reach a maximum between ~ 500 and ~ 900 ppm. As a consequence, increasing anthropogenic CO2 emissions will make the ocean and the biosphere the main reservoirs of anthropogenic CO2 in the long run. Latest in about 150 years, anthropogenic CO2 emission will no longer increase the CO2 content of the atmosphere.

  12. A simple model of the anthropogenically forced CO2 cycle

    Science.gov (United States)

    Weber, W.; Lüdecke, H.-J.; Weiss, C. O.

    2015-10-01

    From basic physical assumptions we derive a simple linear model of the global CO2 cycle without free parameters. It yields excellent agreement with the observations reported by the carbon dioxide information analysis center (CDIAC) as time series of atmospheric CO2 growth, of sinks in the ocean and of absorption by the biosphere. The agreement extends from the year 1850 until present (2013). Based on anthropogenic CO2 emission scenarios until 2150, future atmospheric CO2 concentrations are calculated. As the model shows, and depending on the emission scenario, the airborne fraction of CO2 begins to decrease in the year ~ 2050 and becomes negative at the latest in ~ 2130. At the same time the concentration of the atmospheric CO2 will reach a maximum between ~ 500 and ~ 900 ppm. As a consequence, increasing anthropogenic CO2 emissions will make the ocean and the biosphere the main reservoirs of anthropogenic CO2 in the long run. Latest in about 150 years, anthropogenic CO2 emission will no longer increase the CO2 content of the atmosphere.

  13. Detection of CO2 leakage by the surface-soil CO2-concentration monitoring (SCM) system in a small scale CO2 release test

    Science.gov (United States)

    Chae, Gitak; Yu, Soonyoung; Sung, Ki-Sung; Choi, Byoung-Young; Park, Jinyoung; Han, Raehee; Kim, Jeong-Chan; Park, Kwon Gyu

    2015-04-01

    Monitoring of CO2 release through the ground surface is essential to testify the safety of CO2 storage projects. We conducted a feasibility study of the multi-channel surface-soil CO2-concentration monitoring (SCM) system as a soil CO2 monitoring tool with a small scale injection. In the system, chambers are attached onto the ground surface, and NDIR sensors installed in each chamber detect CO2 in soil gas released through the soil surface. Before injection, the background CO2 concentrations were measured. They showed the distinct diurnal variation, and were positively related with relative humidity, but negatively with temperature. The negative relation of CO2 measurements with temperature and the low CO2 concentrations during the day imply that CO2 depends on respiration. The daily variation of CO2 concentrations was damped with precipitation, which can be explained by dissolution of CO2 and gas release out of pores through the ground surface with recharge. For the injection test, 4.2 kg of CO2 was injected 1 m below the ground for about 30 minutes. In result, CO2 concentrations increased in all five chambers, which were located less than 2.5 m of distance from an injection point. The Chamber 1, which is closest to the injection point, showed the largest increase of CO2 concentrations; while Chamber 2, 3, and 4 showed the peak which is 2 times higher than the average of background CO2. The CO2 concentrations increased back after decreasing from the peak around 4 hours after the injection ended in Chamber 2, 4, and 5, which indicated that CO2 concentrations seem to be recovered to the background around 4 hours after the injection ended. To determine the leakage, the data in Chamber 2 and 5, which had low increase rates in the CO2 injection test, were used for statistical analysis. The result shows that the coefficient of variation (CV) of CO2 measurements for 30 minutes is efficient to determine a leakage signal, with reflecting the abnormal change in CO2

  14. [CO2-Concentrating Mechanism and Its Traits in Haloalkaliphilic Cyanobacteria].

    Science.gov (United States)

    Kupriyanova, E V; Samylina, O S

    2015-01-01

    Cyanobacteria are a group of oxygenic phototrophs existing for at least 3.5 Ga. Photosynthetic CO2 assimilation by cyanobacteria occurs via the Calvin cycle, with RuBisCO, its key enzyme, having very low affinity to CO2. This is due to the fact that atmospheric CO2 concentration in Archaean, when the photosynthetic apparatus evolved, was several orders higher than now. Later, in the epoch of Precambrian microbial communities, CO2 content in the atmosphere decreased drastically. Thus, present-day phototrophs, including cyanobacteria, require adaptive mechanisms for efficient photosynthesis. In cyanobacterial cells, this function is performed by the CO2-concentrating mechanism (CCM), which creates elevated CO2 concentrations in the vicinity of RuBisCO active centers, thus significantly increasing the rate of CO2 fixation in the Calvin cycle. CCM has been previously studied only for freshwater and marine cyanobacteria. We were the first to investigate CCM in haloalkaliphilic cyanobacteria from soda lakes. Extremophilic haloalkaliphilic cyanobacteria were shown to possess a well-developed CCM with the structure and functional principles similar to those of freshwater and marine strains. Analysis of available data suggests that regulation of the amount of inorganic carbon transported into the cell is probably the general CCM function under these conditions.

  15. Deep Sea Memory of High Atmospheric CO2 Concentration

    Science.gov (United States)

    Mathesius, Sabine; Hofmann, Matthias; Caldeira, Ken; Schellnhuber, Hans Joachim

    2015-04-01

    Carbon dioxide removal (CDR) from the atmosphere has been proposed as a powerful measure to mitigate global warming and ocean acidification. Planetary-scale interventions of that kind are often portrayed as "last-resort strategies", which need to weigh in if humankind keeps on enhancing the climate-system stock of CO2. Yet even if CDR could restore atmospheric CO2 to substantially lower concentrations, would it really qualify to undo the critical impacts of past emissions? In the study presented here, we employed an Earth System Model of Intermediate Complexity (EMIC) to investigate how CDR might erase the emissions legacy in the marine environment, focusing on pH, temperature and dissolved oxygen. Against a background of a world following the RCP8.5 emissions path ("business-as-usual") for centuries, we simulated the effects of two massive CDR interventions with CO2 extraction rates of 5 GtC yr-1 and 25 GtC yr-1, respectively, starting in 2250. We found that the 5 GtC yr-1 scheme would have only minor ameliorative influence on the oceans, even after several centuries of application. By way of contrast, the extreme 25 GtC yr-1 scheme eventually leads to tangible improvements. However, even with such an aggressive measure, past CO2 emissions leave a substantial legacy in the marine environment within the simulated period (i.e., until 2700). In summary, our study demonstrates that anthropogenic alterations of the oceans, caused by continued business-as-usual emissions, may not be reversed on a multi-centennial time scale by the most aspirational geoengineering measures. We also found that a transition from the RCP8.5 state to the state of a strong mitigation scenario (RCP2.6) is not possible, even under the assumption of extreme extraction rates (25 GtC yr-1). This is explicitly demonstrated by simulating additional scenarios, starting CDR already in 2150 and operating until the atmospheric CO2 concentration reaches 280 ppm and 180 ppm, respectively. The simulated

  16. Rising CO2 concentrations affect settlement behaviour of larval damselfishes

    Science.gov (United States)

    Devine, B. M.; Munday, P. L.; Jones, G. P.

    2012-03-01

    Reef fish larvae actively select preferred benthic habitat, relying on olfactory, visual and acoustic cues to discriminate between microhabitats at settlement. Recent studies show exposure to elevated carbon dioxide (CO2) impairs olfactory cue recognition in larval reef fishes. However, whether this alters the behaviour of settling fish or disrupts habitat selection is unknown. Here, the effect of elevated CO2 on larval behaviour and habitat selection at settlement was tested in three species of damselfishes (family Pomacentridae) that differ in their pattern of habitat use: Pomacentrus amboinensis (a habitat generalist), Pomacentrus chrysurus (a rubble specialist) and Pomacentrus moluccensis (a live coral specialist). Settlement-stage larvae were exposed to current-day CO2 levels or CO2 concentrations that could occur by 2100 (700 and 850 ppm) based on IPCC emission scenarios. First, pair-wise choice tests were performed using a two-channel flume chamber to test olfactory discrimination between hard coral, soft coral and coral rubble habitats. The habitat selected by settling fish was then compared among treatments using a multi-choice settlement experiment conducted overnight. Finally, settlement timing between treatments was compared across two lunar cycles for one of the species, P. chrysurus. Exposure to elevated CO2 disrupted the ability of larvae to discriminate between habitat odours in olfactory trials. However, this had no effect on the habitats selected at settlement when all sensory cues were available. The timing of settlement was dramatically altered by CO2 exposure, with control fish exhibiting peak settlement around the new moon, whereas fish exposed to 850 ppm CO2 displaying highest settlement rates around the full moon. These results suggest larvae can rely on other sensory information, such as visual cues, to compensate for impaired olfactory ability when selecting settlement habitat at small spatial scales. However, rising CO2 could cause larvae

  17. Decarbonization rate and the timing and magnitude of the CO2 concentration peak

    Science.gov (United States)

    Seshadri, Ashwin K.

    2016-11-01

    Carbon-dioxide (CO2) is the main contributor to anthropogenic global warming, and the timing of its peak concentration in the atmosphere is likely to be the major factor in the timing of maximum radiative forcing. Other forcers such as aerosols and non-CO2 greenhouse gases may also influence the timing of maximum radiative forcing. This paper approximates solutions to a linear model of atmospheric CO2 dynamics with four time-constants to identify factors governing the timing of its concentration peak. The most important emissions-related factor is the ratio between average rates at which emissions increase and decrease, which in turn is related to the rate at which the emissions intensity of CO2 is reduced. Rapid decarbonization of CO2 can not only limit global warming but also achieve an early CO2 concentration peak. The most important carbon cycle parameters are the long multi-century time-constant of atmospheric CO2, and the ratio of contributions to the impulse response function of atmospheric CO2 from the infinitely long lived and the multi-century contributions respectively. Reducing uncertainties in these parameters can reduce uncertainty in forecasts of the radiative forcing peak. A simple approximation for peak CO2 concentration, valid especially if decarbonization is slow, is developed. Peak concentration is approximated as a function of cumulative emissions and emissions at the time of the concentration peak. Furthermore peak concentration is directly proportional to cumulative CO2 emissions for a wide range of emissions scenarios. Therefore, limiting the peak CO2 concentration is equivalent to limiting cumulative emissions. These relationships need to be verified using more complex models of Earth system's carbon cycle.

  18. Numerical Simulation Study on the Impacts of Tropospheric O3 and CO2 Concentration Changes on Winter Wheat.Part Ⅰ: Model Description

    Institute of Scientific and Technical Information of China (English)

    ZHENG Changling; WANG Chunyi

    2006-01-01

    Ozone is well documented as the air pollutant most damaging to agricultural crops and other plants.It is reported that tropospheric O3 concentration increases rapidly in recent 20 years.Evaluating and predicting impacts of ozone concentration changes on crops are drawing great attention in the scientific community. In China, main study method about this filed is controlled experiments, for example, Open Top Chambers. But numerical simulation study about impacts of ozone on crops with crop model was developed slowly, what is more, the study about combined impacts of ozone and carbon dioxide has not been reported.The improved agroecosystem model is presented to evaluate simultaneously impacts of tropospheric O3and CO2 concentration changes on crops in the paper by integrating algorithms about impacts of ozone on photosynthesis with an existing agroecosystem biogeochemical model (named as DNDC). The main physiological processes of crop growth (phenology, leaf area index, photosynthesis, respiration, assimilated allocation and so on) in the former DNDC are kept. The algorithms about impacts of ozone on photosynthesis and winter wheat leaf are added in the modified DNDC model in order to reveal impacts of ozone and carbon dioxide on growth, development, and yield formation of winter wheat by coupling the simulation about impacts of carbon dioxide on photosynthesis of winter wheat which exists in the former DNDC. In the paper, firstly assimilate allocation algorithms and some genetic parameters (such as daily thermal time of every development stage) were modified in order that DNDC can be applicable in North China. Secondly impacts of ozone on crops were simulated with two different methods- one was impacts of ozone on light use efficiency, and the other was direct effects of ozone on leaves photosynthesis. The latter simulated results are closer to experiment measurements through comparing their simulating results. At last the method of direct impacts of ozone on leaf

  19. Transient modeling of electrochemically assisted CO2 capture and release

    DEFF Research Database (Denmark)

    Singh, Shobhana; Stechel, Ellen B.; Buttry, Daniel A.

    2017-01-01

    The present work aims to develop a model of a new electrochemical CO2 separation and release technology. We present a one-dimensional transient model of an electrochemical cell for point source CO2 capture and release, which mainly focuses on the simultaneous mass transport and complex chemical...... reactions associated with the separation process. For concreteness, we use an ionic liquid (IL) with 2 M thiolate anion (RS−) in 1 M disulfide (RSSR) as an electrolyte in the electrochemical cell to capture, transport and release CO2 under standard operating conditions. We computationally solved the model...... to analyze the time-dependent behavior of CO2 capture and electro-migration transport across the cell length. Given high nonlinearity of the system, we used a finite element method (FEM) to numerically solve the coupled mass transport equations. The model describes the concentration profiles by taking...

  20. Dynamics of global atmospheric CO2 concentration from 1850 to 2010: a linear approximation

    Science.gov (United States)

    Wang, W.; Nemani, R.

    2014-09-01

    The increase in anthropogenic CO2 emissions largely followed an exponential path between 1850 and 2010, and the corresponding increases in atmospheric CO2 concentration were almost constantly proportional to the emissions by the so-called "airborne fraction". These observations suggest that the dynamics of atmospheric CO2 concentration through this time period may be properly approximated as a linear system. We demonstrate this hypothesis by deriving a linear box-model to describe carbon exchanges between the atmosphere and the surface reservoirs under the influence of disturbances such as anthropogenic CO2 emissions and global temperature changes. We show that the box model accurately simulates the observed atmospheric CO2 concentrations and growth rates across interannual to multi-decadal time scales. The model also allows us to analytically examine the dynamics of such changes/variations, linking its characteristic disturbance-response functions to bio-geophysically meaningful parameters. In particular, our results suggest that the elevated atmospheric CO2 concentrations have significantly promoted the gross carbon uptake by the terrestrial biosphere. However, such "fertilization" effects are partially offset by enhanced carbon release from surface reservoirs promoted by warmer temperatures. The result of these interactions appears to be a decline in net efficiency in sequestering atmospheric CO2 by ∼30% since 1960s. We believe that the linear modeling framework outlined in this paper provides a convenient tool to diagnose the observed atmospheric CO2 dynamics and monitor their future changes.

  1. Online monitoring of dissolved CO2 and MEA concentrations: effect of solvent degradation on predictive accuracy

    NARCIS (Netherlands)

    Ham, L.V. van der; Eckeveld, A.C. van; Goetheer, E.L.V.

    2014-01-01

    Concentrations of dissolved CO2 and mono-ethanolamine (MEA) are two essential properties of common CO2 absorption processes. They can be predicted accurately and continuously using a combination of inline measurements and a multivariate model, also in the presence of various solvent degradation prod

  2. Use of high-scale traffic modeling to estimate road vehicle emissions of CO2 and impact on the atmospheric concentration in São Paulo, Brazil.

    Science.gov (United States)

    Miranda, R. M.; Perez-Martinez, P.; Andrade, M. D. F.

    2015-12-01

    Adequate estimations of motor vehicle CO2 emission inventories at high spatial and temporal urban scales are needed to establish transport policy measures aim to reduce climate change impacts from global cities. The Metropolitan Region of São Paulo (MRSP) is impacted by the emission of 7 million vehicles (97% light-duty gasoline vehicles LDVs and 3% heavy-duty diesel vehicles HDVs) and several environmental programs were implemented to reduce the emissions. Inventories match site measurements and remote sensing and help to assess the real impact of road vehicle emissions on city's air quality. In this paper we presented a high-resolution vehicle-based inventory of motor CO2 emissions mapped at a scale of 100 m and 1 hour. We used origin and destination (O/D) transport area zone trips from the mobility survey of the São Paulo Transport Metropolitan Company (Metro), a road network of the region and traffic datasets from the São Paulo Transport Engineering Company (CET). The inventory was done individually for LDVs and HDVs for the years 2008 and 2013 and was complemented with air quality datasets from the State Environmental Company (CETESB), together with census data from the Brazilian Institute of Geography and Statistics (IBGE). Our inventory showed partial disagreement with the São Paulo State's GHG inventory, caused by the different approach used - bottom vs. top down - and characteristic spatial and temporal biases of the population inputs used (different emission factors). Higher concentrations became apparent near the road-network at the spatial scale used. The total emissions were estimated in 20,781 million tons per year of CO2eq (83.7% by LDVs and 16.3% HDVs). Temporal profiles - diurnal, weekly and monthly - in vehicle emission distributions were calculated using CET's traffic counts and surrogates of congestion. These profiles were compared with average road-site measurements of CO2 for the year 2013. Measurements showed two peaks associated to the

  3. Strong Relationships in Acid-Base Chemistry – Modeling Protons Based on Predictable Concentrations of Strong Ions, Total Weak Acid Concentrations, and pCO2

    Science.gov (United States)

    Kellum, John A.

    2016-01-01

    Understanding acid-base regulation is often reduced to pigeonholing clinical states into categories of disorders based on arterial blood sampling. An earlier ambition to quantitatively explain disorders by measuring production and elimination of acid has not become standard clinical practice. Seeking back to classical physical chemistry we propose that in any compartment, the requirement of electroneutrality leads to a strong relationship between charged moieties. This relationship is derived in the form of a general equation stating charge balance, making it possible to calculate [H+] and pH based on all other charged moieties. Therefore, to validate this construct we investigated a large number of blood samples from intensive care patients, where both data and pathology is plentiful, by comparing the measured pH to the modeled pH. We were able to predict both the mean pattern and the individual fluctuation in pH based on all other measured charges with a correlation of approximately 90% in individual patient series. However, there was a shift in pH so that fitted pH in general is overestimated (95% confidence interval -0.072–0.210) and we examine some explanations for this shift. Having confirmed the relationship between charged species we then examine some of the classical and recent literature concerning the importance of charge balance. We conclude that focusing on the charges which are predictable such as strong ions and total concentrations of weak acids leads to new insights with important implications for medicine and physiology. Importantly this construct should pave the way for quantitative acid-base models looking into the underlying mechanisms of disorders rather than just classifying them. PMID:27631369

  4. Thermodynamic modeling of CO2 mixtures

    DEFF Research Database (Denmark)

    Bjørner, Martin Gamel

    performed satisfactorily and predicted the general behavior of the systems, but qCPA used fewer adjustable parameters to achieve similar predictions. It has been demonstrated that qCPA is a promising model which, compared to CPA, systematically improves the predictions of the experimentally determined phase......, accurate predictions of the thermodynamic properties and phase equilibria of mixtures containing CO2 are challenging with classical models such as the Soave-Redlich-Kwong (SRK) equation of state (EoS). This is believed to be due to the fact, that CO2 has a large quadrupole moment which the classical models...... do not explicitly account for. In this thesis, in an attempt to obtain a physically more consistent model, the cubicplus association (CPA) EoS is extended to include quadrupolar interactions. The new quadrupolar CPA (qCPA) can be used with the experimental value of the quadrupolemoment...

  5. 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.

  6. Comment on 'improving ecophysiological simulation models to predict the impact of elevated CO(2) concentration on crop productivity' by X. Yin.

    Science.gov (United States)

    Kimball, B A

    2013-08-01

    The recent publication by Yin (2013; Annals of Botany 112: 465-475) referred to in the title above provides an excellent review of modelling approaches to predict the impact of elevated CO2 on crop productivity, as well as on the controversy regarding whether yield responses observed in free-air CO2 enrichment (FACE) experiments are indeed lower than those from chamber-based experiments. However, the wheat experiments in the example of fig. 1 in Yin's paper had a flaw as the control plots lacked blowers that were in the FACE plots, which warmed the FACE plots at night and hastened plant development. This Viewpoint seeks to highlight this fact, and to comment on the relative merits of FACE and enclosure experiments.

  7. Transcriptional response of the extremophile red alga Cyanidioschyzon merolae to changes in CO2 concentrations.

    Science.gov (United States)

    Rademacher, Nadine; Wrobel, Thomas J; Rossoni, Alessandro W; Kurz, Samantha; Bräutigam, Andrea; Weber, Andreas P M; Eisenhut, Marion

    2017-10-01

    Cyanidioschyzon merolae (C. merolae) is an acidophilic red alga growing in a naturally low carbon dioxide (CO2) environment. Although it uses a ribulose 1,5-bisphosphate carboxylase/oxygenase with high affinity for CO2, the survival of C. merolae relies on functional photorespiratory metabolism. In this study, we quantified the transcriptomic response of C. merolae to changes in CO2 conditions. We found distinct changes upon shifts between CO2 conditions, such as a concerted up-regulation of photorespiratory genes and responses to carbon starvation. We used the transcriptome data set to explore a hypothetical CO2 concentrating mechanism in C. merolae, based on the assumption that photorespiratory genes and possible candidate genes involved in a CO2 concentrating mechanism are co-expressed. A putative bicarbonate transport protein and two α-carbonic anhydrases were identified, which showed enhanced transcript levels under reduced CO2 conditions. Genes encoding enzymes of a PEPCK-type C4 pathway were co-regulated with the photorespiratory gene cluster. We propose a model of a hypothetical low CO2 compensation mechanism in C. merolae integrating these low CO2-inducible components. Copyright © 2017 Elsevier GmbH. All rights reserved.

  8. Modeling Atmospheric CO2 Processes to Constrain the Missing Sink

    Science.gov (United States)

    Kawa, S. R.; Denning, A. S.; Erickson, D. J.; Collatz, J. C.; Pawson, S.

    2005-01-01

    We report on a NASA supported modeling effort to reduce uncertainty in carbon cycle processes that create the so-called missing sink of atmospheric CO2. Our overall objective is to improve characterization of CO2 source/sink processes globally with improved formulations for atmospheric transport, terrestrial uptake and release, biomass and fossil fuel burning, and observational data analysis. The motivation for this study follows from the perspective that progress in determining CO2 sources and sinks beyond the current state of the art will rely on utilization of more extensive and intensive CO2 and related observations including those from satellite remote sensing. The major components of this effort are: 1) Continued development of the chemistry and transport model using analyzed meteorological fields from the Goddard Global Modeling and Assimilation Office, with comparison to real time data in both forward and inverse modes; 2) An advanced biosphere model, constrained by remote sensing data, coupled to the global transport model to produce distributions of CO2 fluxes and concentrations that are consistent with actual meteorological variability; 3) Improved remote sensing estimates for biomass burning emission fluxes to better characterize interannual variability in the atmospheric CO2 budget and to better constrain the land use change source; 4) Evaluating the impact of temporally resolved fossil fuel emission distributions on atmospheric CO2 gradients and variability. 5) Testing the impact of existing and planned remote sensing data sources (e.g., AIRS, MODIS, OCO) on inference of CO2 sources and sinks, and use the model to help establish measurement requirements for future remote sensing instruments. The results will help to prepare for the use of OCO and other satellite data in a multi-disciplinary carbon data assimilation system for analysis and prediction of carbon cycle changes and carbodclimate interactions.

  9. Strong Relationships in Acid-Base Chemistry - Modeling Protons Based on Predictable Concentrations of Strong Ions, Total Weak Acid Concentrations, and pCO2

    DEFF Research Database (Denmark)

    Ring, Troels; Kellum, John A

    2016-01-01

    confirmed the relationship between charged species we then examine some of the classical and recent literature concerning the importance of charge balance. We conclude that focusing on the charges which are predictable such as strong ions and total concentrations of weak acids leads to new insights......Understanding acid-base regulation is often reduced to pigeonholing clinical states into categories of disorders based on arterial blood sampling. An earlier ambition to quantitatively explain disorders by measuring production and elimination of acid has not become standard clinical practice....... Seeking back to classical physical chemistry we propose that in any compartment, the requirement of electroneutrality leads to a strong relationship between charged moieties. This relationship is derived in the form of a general equation stating charge balance, making it possible to calculate [H+] and p...

  10. Impacts of CO2 concentration on growth, lipid accumulation, and carbon-concentrating-mechanism-related gene expression in oleaginous Chlorella.

    Science.gov (United States)

    Fan, Jianhua; Xu, Hui; Luo, Yuanchan; Wan, Minxi; Huang, Jianke; Wang, Weiliang; Li, Yuanguang

    2015-03-01

    Biodiesel production by microalgae with photosynthetic CO2 biofixation is thought to be a feasible way in the field of bioenergy and carbon emission reduction. Knowledge of the carbon-concentrating mechanism plays an important role in improving microalgae carbon fixation efficiency. However, little information is available regarding the dramatic changes of cells suffered upon different environmental factors, such as CO2 concentration. The aim of this study was to investigate the growth, lipid accumulation, carbon fixation rate, and carbon metabolism gene expression under different CO2 concentrations in oleaginous Chlorella. It was found that Chlorella pyrenoidosa grew well under CO2 concentrations ranging from 1 to 20 %. The highest biomass and lipid productivity were 4.3 g/L and 107 mg/L/day under 5 % CO2 condition. Switch from high (5 %) to low (0.03 %, air) CO2 concentration showed significant inhibitory effect on growth and CO2 fixation rate. The amount of the saturated fatty acids was increased obviously along with the transition. Low CO2 concentration (0.03 %) was suitable for the accumulation of saturated fatty acids. Reducing the CO2 concentration could significantly decrease the polyunsaturated degree in fatty acids. Moreover, the carbon-concentrating mechanism-related gene expression revealed that most of them, especially CAH2, LCIB, and HLA3, had remarkable change after 1, 4, and 24 h of the transition, which suggests that Chlorella has similar carbon-concentrating mechanism with Chlamydomonas reinhardtii. The findings of the present study revealed that C. pyrenoidosa is an ideal candidate for mitigating CO2 and biodiesel production and is appropriate as a model for mechanism research of carbon sequestration.

  11. Advances in Pulsed Lidar Measurements of CO2 Column Concentrations from Aircraft and for Space

    Science.gov (United States)

    Abshire, J. B.; Ramanathan, A. K.; Allan, G. R.; Hasselbrack, W. E.; Riris, H.; Numata, K.; Mao, J.; Sun, X.

    2016-12-01

    We have demonstrated an improved pulsed, multiple-wavelength integrated path differential absorption lidar for measuring the tropospheric CO2 concentrations. The lidar measures the range resolved shape of the 1572.33 nm CO2 absorption line to scattering surfaces, including the ground and the tops of clouds. Airborne measurements have used both 30 and 15 fixed wavelength samples distributed across the line. Analysis estimates the lidar range and pulse energies at each wavelength 10 times per second. The retrievals solve for the CO2 absorption line shape and the column average CO2 concentrations by using radiative transfer calculations, the aircraft altitude and range to the scattering surface, and the atmospheric conditions. We compare these to CO2 concentrations from in-situ sensors. In recent campaigns the lidar used a step-locked laser diode source, and a new HgCdTe APD detector in the receiver. During August and September 2014 the ASCENDS campaign flew over the California Central Valley, a coastal redwood forest, desert areas, and above growing crops in Iowa. Analyses show the retrievals of lidar range and CO2 column absorption, and mixing ratio worked well when measuring over variable topography and through thin clouds and aerosols. The retrievals clearly show the decrease in CO2 concentration over growing cropland. Airborne lidar measurements of horizontal gradients of CO2 concentrations across Nevada, Colorado and Nebraska showed good agreement with those from a model of CO2 flux and transport (PCTM). In several flights the agreement of the lidar with the column average concentration was ppm, with standard deviation of 0.9 ppm. Two additional flights were made in February 2016 using a larger laser spot size and an optimized receiver. These improved the sensitivity x3, and the retrievals show 0.7 ppm precision over the desert in 1 second averaging time. A summary of these results will be presented, along with on-going developments for a space version.

  12. 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.

  13. Response of export production and dissolved oxygen concentrations in oxygen minimum zones to pCO2 and temperature stabilization scenarios in the biogeochemical model HAMOCC 2.0

    Science.gov (United States)

    Beaty, Teresa; Heinze, Christoph; Hughlett, Taylor; Winguth, Arne M. E.

    2017-02-01

    Dissolved oxygen (DO) concentration in the ocean is an important component of marine biogeochemical cycles and will be greatly altered as climate change persists. In this study a global oceanic carbon cycle model (HAMOCC 2.0) is used to address how mechanisms of oxygen minimum zone (OMZ) expansion respond to changes in CO2 radiative forcing. Atmospheric pCO2 is increased at a rate of 1 % annually and the model is stabilized at 2 ×, 4 ×, 6 ×, and 8 × preindustrial pCO2 levels. With an increase in CO2 radiative forcing, the OMZ in the Pacific Ocean is controlled largely by changes in particulate organic carbon (POC) export, resulting in increased remineralization and thus expanding the OMZs within the tropical Pacific Ocean. A potential decline in primary producers in the future as a result of environmental stress due to ocean warming and acidification could lead to a substantial reduction in POC export production, vertical POC flux, and thus increased DO concentration particularly in the Pacific Ocean at a depth of 600-800 m. In contrast, the vertical expansion of the OMZs within the Atlantic is linked to increases POC flux as well as changes in oxygen solubility with increasing seawater temperature. Changes in total organic carbon and increase sea surface temperature (SST) also lead to the formation of a new OMZ in the western subtropical Pacific Ocean. The development of the new OMZ results in dissolved oxygen concentration of ≤ 50 µmol kg-1 throughout the equatorial Pacific Ocean at 4 times preindustrial pCO2. Total ocean volume with dissolved oxygen concentrations of ≤ 50 µmol kg-1 increases by 2.4, 5.0, and 10.5 % for the 2 ×, 4 ×, and 8 × CO2 simulations, respectively.

  14. Quantification of the advected CO2 concentration due to upstream surface fluxes in aircraft vertical profiles

    Science.gov (United States)

    Font, A.; Morguí, J.-A.; Curcoll, R.; Rodó, X.

    2009-04-01

    A model framework which couples the Lagrangian Particle Dispersion Model FLEXPART (LPDM) with the new global surface flux inversion CarbonTracker from NOAA-ESRL (2007B release) is used to quantify the advected CO2 concentration from outbound surface fluxes to measured vertical profiles carried out during different seasons in 2006 at La Muela site in Spain (LMU; 41.60°N, 1.1°W). The Lagrangian Particle Dispersion Model FLEXPART (LPDM) calculates the influence of surface CO2 fluxes upwind of the study area, allowing us to identify those sources or sink areas that strongly modify the CO2 content of air masses that arrives at different altitudes of measured profiles. CarbonTracker is a new assimilation system that informs of global carbon fluxes at 1°x1° at 3 hours resolution. Coupling LPDM results with surface fluxes allows assessing the net CO2 contribution of identified areas to measured concentrations along the profiles above a reference or background concentration. Furthermore, it allows the quantification of the percentage of each component flux (biospheric, anthropogenic and oceanic) to each vertical layer. At LMU, biospheric fluxes account ~70% of total CO2 advection; fossil fuel ~25%; and ~5% is attributed to the oceanic ones. By far, late spring and summer profiles are largely influence by the biospheric component (~90%). Finally, the CO2 concentration above the background value of profiles measured on 22nd February, 13th October and 30th November 2006 are well explained by the advection of upstream surface fluxes. In other profiles examined, the variation of CO2 along the profile is partially explained by the advection of CO2 outbound fluxes.

  15. A cross-association model for CO2-methanol and CO2-ethanol mixtures

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A cross-association model was proposed for CO2-alcohol mixtures based on the statistical associating fluid theory (SAFT).CO2 was treated as a pseudo-associating molecule and both the self-association between alcohol hydroxyls and the cross-association between CO2 and alcohol hydroxyls were considered.The equilibrium properties from low temperature-pressure to high temperature-pressure were investigated using this model.The calculated p-x and p-p diagrams of CO2-methanol and CO2-ethanol mixtures agreed with the experimental data.The results showed that when the cross-association was taken into account for Helmholtz free energy,the calculated equilibrium properties could be significantly improved,and the error prediction of the three phase equilibria and triple points in low temperature regions could be avoided.

  16. High indoor CO2 concentrations in an office environment increases the transcutaneous CO2 level and sleepiness during cognitive work.

    Science.gov (United States)

    Vehviläinen, Tommi; Lindholm, Harri; Rintamäki, Hannu; Pääkkönen, Rauno; Hirvonen, Ari; Niemi, Olli; Vinha, Juha

    2016-01-01

    The purpose of this study is to perform a multiparametric analysis on the environmental factors, the physiological stress reactions in the body, the measured alertness, and the subjective symptoms during simulated office work. Volunteer male subjects were monitored during three 4-hr work meetings in an office room, both in a ventilated and a non-ventilated environment. The environmental parameters measured included CO(2), temperature, and relative humidity. The physiological test battery consisted of measuring autonomic nervous system functions, salivary stress hormones, blood's CO(2)- content and oxygen saturation, skin temperatures, thermal sensations, vigilance, and sleepiness. The study shows that we can see physiological changes caused by high CO(2) concentration. The findings support the view that low or moderate level increases in concentration of CO(2) in indoor air might cause elevation in the blood's transcutaneously assessed CO(2). The observed findings are higher CO(2) concentrations in tissues, changes in heart rate variation, and an increase of peripheral blood circulation during exposure to elevated CO(2) concentration. The subjective parameters and symptoms support the physiological findings. This study shows that a high concentration of CO(2) in indoor air seem to be one parameter causing physiological effects, which can decrease the facility user's functional ability. The correct amount of ventilation with relation to the number of people using the facility, functional air distribution, and regular breaks can counteract the decrease in functional ability. The findings of the study suggest that merely increasing ventilation is not necessarily a rational solution from a technical-economical viewpoint. Instead or in addition, more comprehensive, anthropocentric planning of space is needed as well as instructions and new kinds of reference values for the design and realization of office environments.

  17. Seasonal dynamics of soil CO2 efflux and soil profile CO2 concentrations in arboretum of Moscow botanical garden

    Science.gov (United States)

    Goncharova, Olga; Udovenko, Maria; Matyshak, Georgy

    2016-04-01

    To analyse and predict recent and future climate change on a global scale exchange processes of greenhouse gases - primarily carbon dioxide - over various ecosystems are of rising interest. In order to upscale land-use dependent sources and sinks of CO2, knowledge of the local variability of carbon fluxes is needed. Among terrestrial ecosystems, urban areas play an important role because most of anthropogenic emissions of carbon dioxide originate from these areas. On the other hand, urban soils have the potential to store large amounts of soil organic carbon and, thus, contribute to mitigating increases in atmospheric CO2 concentrations. Research objectives: 1) estimate the seasonal dynamics of carbon dioxide production (emission - closed chamber technique and profile concentration - soil air sampling tubes method) by soils of Moscow State University Botanical Garden Arboretum planted with Picea obovata and Pinus sylvestris, 1) identification the factors that control CO2 production. The study was conducted with 1-2 weeks intervals between October 2013 and November 2015 at two sites. Carbon dioxide soil surface efflux during the year ranged from 0 to 800 mgCO2/(m2hr). Efflux values above 0 mgCO2/(m2hr) was observed during the all cold period except for only 3 weeks. Soil CO2 concentration ranged from 1600-3000 ppm in upper 10-cm layer to 10000-40000 ppm at a depth of 60 cm. The maximum concentrations of CO2 were recorded in late winter and late summer. We associate it with high biological activity (both heterotrophic and autotrophic) during the summer, and with physical gas jamming in the winter. The high value of annual CO2 production of the studied soils is caused by high organic matter content, slightly alkaline reaction, good structure and texture of urban soils. Differences in soil CO2 production by spruce and pine urban forest soils (in the pine forest 1.5-2.0 times higher) are caused by urban soil profiles construction, but not temperature regimes. Seasonal

  18. Effects of Temperature Rise and Increase in CO2 Concentration on Simulated Wheat Yields in Europe

    NARCIS (Netherlands)

    Nonhebel, Sanderine

    1996-01-01

    A crop-growth-simulation model based on SUCROS87 was used to study effects of temperature rise and increase of atmospheric CO2 concentration on wheat yields in several regions in Europe. The model simulated potential and water-limited crop production (growth with ample supply of nutrients and in the

  19. Comparison of CO2 fluxes estimated using atmospheric and oceanic inversions, and role of fluxes and their interannual variability in simulating atmospheric CO2 concentrations

    Science.gov (United States)

    Patra, P. K.; Mikaloff Fletcher, S. E.; Ishijima, K.; Maksyutov, S.; Nakazawa, T.

    2006-07-01

    We use a time-dependent inverse (TDI) model to estimate regional sources and sinks of atmospheric CO2 from 64 and then 22 regions based on atmospheric CO2 observations at 87 stations. The air-sea fluxes from the 64-region atmospheric-CO2 inversion are compared with fluxes from an analogous ocean inversion that uses ocean interior observations of dissolved inorganic carbon (DIC) and other tracers and an ocean general circulation model (OGCM). We find that, unlike previous atmospheric inversions, our flux estimates in the southern hemisphere are generally in good agreement with the results from the ocean inversion, which gives us added confidence in our flux estimates. In addition, a forward tracer transport model (TTM) is used to simulate the observed CO2 concentrations using (1) estimates of fossil fuel emissions and a priori estimates of the terrestrial and oceanic fluxes of CO2, and (2) two sets of TDI model corrected fluxes. The TTM simulations of TDI model corrected fluxes show improvements in fitting the observed interannual variability in growth rates and seasonal cycles in atmospheric CO2. Our analysis suggests that the use of interannually varying (IAV) meteorology and a larger observational network have helped to capture the regional representation and interannual variabilities in CO2 fluxes realistically.

  20. Regional disparities in the beneficial effects of rising CO2 concentrations on crop water productivity

    Science.gov (United States)

    Deryng, Delphine; Elliott, Joshua; Folberth, Christian; Müller, Christoph; Pugh, Thomas A. M.; Boote, Kenneth J.; Conway, Declan; Ruane, Alex C.; Gerten, Dieter; Jones, James W.; Khabarov, Nikolay; Olin, Stefan; Schaphoff, Sibyll; Schmid, Erwin; Yang, Hong; Rosenzweig, Cynthia

    2016-08-01

    Rising atmospheric CO2 concentrations ([CO2]) are expected to enhance photosynthesis and reduce crop water use. However, there is high uncertainty about the global implications of these effects for future crop production and agricultural water requirements under climate change. Here we combine results from networks of field experiments and global crop models to present a spatially explicit global perspective on crop water productivity (CWP, the ratio of crop yield to evapotranspiration) for wheat, maize, rice and soybean under elevated [CO2] and associated climate change projected for a high-end greenhouse gas emissions scenario. We find CO2 effects increase global CWP by 10[047]%-27[737]% (median[interquartile range] across the model ensemble) by the 2080s depending on crop types, with particularly large increases in arid regions (by up to 48[25;56]% for rainfed wheat). If realized in the fields, the effects of elevated [CO2] could considerably mitigate global yield losses whilst reducing agricultural consumptive water use (4-17%). We identify regional disparities driven by differences in growing conditions across agro-ecosystems that could have implications for increasing food production without compromising water security. Finally, our results demonstrate the need to expand field experiments and encourage greater consistency in modelling the effects of rising [CO2] across crop and hydrological modelling communities.

  1. Modeling of CO2 absorber using an AMP solution

    DEFF Research Database (Denmark)

    Gabrielsen, Jostein; Michelsen, Michael Locht; Stenby, Erling Halfdan

    2006-01-01

    Abstract: An explicit model for carbon dioxide (CO2) solubility in an aqueous solution of 2-amino-2-methyl-1-propanol (AMP) has been proposed and an expression for the heat of absorption of CO2 has been developed as a function of loading and temperature. A rate-based steady-state model for CO2 ab...

  2. Energy from CO2 using capacitive electrodes – A model for energy extraction cycles

    NARCIS (Netherlands)

    Paz-García, J.M.; Dykstra, J.E.; Biesheuvel, P.M.; Hamelers, H.V.M.

    2015-01-01

    A model is presented for the process of harvesting electrical energy from CO2 emissions using capacitive cells. The principle consists of controlling the mixing process of a concentrated CO2 gas stream with a dilute CO2 gas stream (as, for example, exhaust gas and air), thereby converting part of th

  3. Energy from CO2 using capacitive electrodes – A model for energy extraction cycles

    NARCIS (Netherlands)

    Paz-García, J.M.; Dykstra, J.E.; Biesheuvel, P.M.; Hamelers, H.V.M.

    2015-01-01

    A model is presented for the process of harvesting electrical energy from CO2 emissions using capacitive cells. The principle consists of controlling the mixing process of a concentrated CO2 gas stream with a dilute CO2 gas stream (as, for example, exhaust gas and air), thereby converting part of

  4. Stomatal response of Pinus sylvestriformis to elevated CO2 concentrations during the four years of exposure

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yu-mei; HAN Shi-jie; LIU Ying; JIA Xia

    2005-01-01

    Four-year-old Pinus sylvestriformis were exposed for four growing seasons in open top chambers to ambient CO2 concentration (approx. 350 μmol·mol-1) and high CO2 concentrations (500 and 700 μmol·mol-1) at Research Station of Changbai Mountain Forest Ecosystems, Chinese Academy of Sciences at Antu Town, Jilin Province, China (42oN, 128oE). Stomatal response to elevated CO2 concentrations was examined by stomatal conductance (gs), ratio of intercellular to ambient CO2 concentration (ci/ca) and stomatal number. Reciprocal transfer experiments of stomatal conductance showed that stomatal conductance in high-[CO2]-grown plants increased in comparison with ambient-[CO2]-grown plants when measured at their respective growth CO2 concentration and at the same measurement CO2 concentration (except a reduction in 700 μmol·mol-1 CO2 grown plants compared with plants on unchambered field when measured at growth CO2 concentration and 350 μmol·mol-1CO2). High-[CO2]-grown plants exhibited lower ci/ca ratios than ambient-[CO2]-grown plants when measured at their respective growth CO2 concentration. However, ci/ca ratios increased for plants grown in high CO2 concentrations compared with control plants when measured at the same CO2 concentration. There was no significant difference in stomatal number per unit long needle between elevated and ambient CO2. However, elevated CO2 concentrations reduced the total stomatal number of whole needle by the decline of stomatal line and changed the allocation pattern of stomata between upper and lower surface of needle.

  5. Soil CO2 concentration does not affect growth or root respiration in bean or citrus

    NARCIS (Netherlands)

    Bouma, T.J.; Nielsen, K.F.; Eissenstat, D.M.; Lynch, J.P.

    1997-01-01

    Contrasting effects of soil CO2 concentration on root respiration rates during short-term CO2 exposure, and on plant growth during long-term CO2 exposure, have been reported, Here we examine the effects of both short-and long-term exposure to soil CO2 on the root respiration of intact plants and on

  6. Intra-seasonal variability of atmospheric CO2 concentrations over India during summer monsoons

    Science.gov (United States)

    Ravi Kumar, K.; Valsala, Vinu; Tiwari, Yogesh K.; Revadekar, J. V.; Pillai, Prasanth; Chakraborty, Supriyo; Murtugudde, Raghu

    2016-10-01

    In a study based on a data assimilation product of the terrestrial biospheric fluxes of CO2 over India, the subcontinent was hypothesized to be an anomalous source (sink) of CO2 during the active (break) spells of rain in the summer monsoon from June to September (Valsala et al., 2013). We test this hypothesis here by investigating intraseasonal variability in the atmospheric CO2 concentrations over India by utilizing a combination of ground-based and satellite observations and model outputs. The results show that the atmospheric CO2 concentration also varies in synchrony with the active and break spells of rainfall with amplitude of ±2 ppm which is above the instrumental uncertainty of the present day techniques of atmospheric CO2 measurements. The result is also consistent with the signs of the Net Ecosystem Exchange (NEE) flux anomalies estimated in our earlier work. The study thus offers the first observational affirmation of the above hypothesis although the data gap in the satellite measurements during monsoon season and the limited ground-based stations over India still leaves some uncertainty in the robust assertion of the hypothesis. The study highlights the need to capture these subtle variabilities and their responses to climate variability and change since it has implications for inverse estimates of terrestrial CO2 fluxes.

  7. Regulation of CO2 Concentrating Mechanism in Cyanobacteria

    Directory of Open Access Journals (Sweden)

    Robert L. Burnap

    2015-01-01

    Full Text Available In this chapter, we mainly focus on the acclimation of cyanobacteria to the changing ambient CO2 and discuss mechanisms of inorganic carbon (Ci uptake, photorespiration, and the regulation among the metabolic fluxes involved in photoautotrophic, photomixotrophic and heterotrophic growth. The structural components for several of the transport and uptake mechanisms are described and the progress towards elucidating their regulation is discussed in the context of studies, which have documented metabolomic changes in response to changes in Ci availability. Genes for several of the transport and uptake mechanisms are regulated by transcriptional regulators that are in the LysR-transcriptional regulator family and are known to act in concert with small molecule effectors, which appear to be well-known metabolites. Signals that trigger changes in gene expression and enzyme activity correspond to specific “regulatory metabolites” whose concentrations depend on the ambient Ci availability. Finally, emerging evidence for an additional layer of regulatory complexity involving small non-coding RNAs is discussed.

  8. Autotrophic and heterotrophic soil respiration determined with trenching, soil CO2 fluxes and 13CO2/12CO2 concentration gradients in a boreal forest ecosystem

    Science.gov (United States)

    Pumpanen, Jukka; Shurpali, Narasinha; Kulmala, Liisa; Kolari, Pasi; Heinonsalo, Jussi

    2017-04-01

    Soil CO2 efflux forms a substantial part of the ecosystem carbon balance, and it can contribute more than half of the annual ecosystem respiration. Recently assimilated carbon which has been fixed in photosynthesis during the previous days plays an important role in soil CO2 efflux, and its contribution is seasonally variable. Moreover, the recently assimilated C has been shown to stimulate the decomposition of recalcitrant C in soil and increase the mineralization of nitrogen, the most important macronutrient limiting gross primary productivity (GPP) in boreal ecosystems. Podzolic soils, typical in boreal zone, have distinctive layers with different biological and chemical properties. The biological activity in different soil layers has large seasonal variation due to vertical gradient in temperature, soil organic matter and root biomass. Thus, the source of CO2 and its components have a vertical gradient which is seasonally variable. The contribution of recently assimilated C and its seasonal as well as spatial variation in soil are difficult to assess without disturbing the system. The most common method of partitioning soil respiration into its components is trenching which entails the roots being cut or girdling where the flow of carbohydrates from the canopy to roots has been isolated by cutting of the phloem. Other methods for determining the contribution of autotrophic (Ra) and heterotrophic (Rh) respiration components in soil CO2 efflux are pulse labelling with 13CO2 or 14CO2 or the natural abundance of 13C and/or 14C isotopes. Also differences in seasonal and short-term temperature response of soil respiration have been used to separate Ra and Rh. We compared the seasonal variation in Ra and Rh using the trenching method and differences between seasonal and short-term temperature responses of soil respiration. I addition, we estimated the vertical variation in soil biological activity using soil CO2 concentration and the natural abundance of 13C and 12C

  9. Future atmospheric CO2 concentration and environmental consequences for the feed market: a consequential LCA

    DEFF Research Database (Denmark)

    Saxe, Henrik; Hamelin, Lorie; Hinrichsen, Torben

    2014-01-01

    With the rising atmospheric carbon dioxide concentration [CO2], crops will assimilate more carbon. This will increase yields in terms of carbohydrates but dilute the content of protein and minerals in crops. This consequential life cycle assessment study modelled the environmental consequences...

  10. Future Atmospheric CO2 Concentration and Environmental Consequences for the Feed Market: a Consequential LCA

    DEFF Research Database (Denmark)

    Saxe, Henrik; Hamelin, Lorie; Hinrichsen, Torben

    2014-01-01

    With the rising atmospheric carbon dioxide concentration [CO2], crops will assimilate more carbon. This will increase yields in terms of carbohydrates but dilute the content of protein and minerals in crops. This consequential life cycle assessment study modelled the environmental consequences...

  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. CO2 background concentra-tion in the atmosphere over the Chinese mainland

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on the long-term monitoring data on CO2 concentration, variation trend and characteristics of CO2 background concentration in the atmosphere over the Chinese mainland are analyzed. Results show that the increasing trend of CO2 background concentration in the atmosphere over the Chinese mainland has appeared during the period of 1991-2000. The average annual CO2 growth increment is 1.59 μL/L, and the average annual CO2 growth rate is 0.44%. Distinct seasonal variations of CO2 background concentration are observed, and the averaged amplitude of CO2 seasonal variations is 10.35 μL/L. Regional variation characteristics of CO2 background concentration in the atmosphere and possible impact of human activities on these variations over the Chinese mainland are discussed as well.

  13. Impact of oceanic circulation changes on the CO2 concentration during past interglacials

    Science.gov (United States)

    Bouttes, Nathaelle; Swingedouw, Didier; Crosta, Xavier; Fernanda Sanchez Goñi, Maria; Roche, Didier

    2016-04-01

    Interglacials before the Mid-Bruhnes Event (around 430 kyrs BP) were characterized by colder temperature in Antarctica, lower sea level and lower atmospheric CO2 compared to the more recent interglacials. Recent climate simulations have shown that the climate of the interglacials before and after the MBE can only be reproduced when taking into account changes in orbital parameters and atmospheric CO2 concentrations (Yin and Berger, 2010; Yin and Berger, 2012). Indeed, interglacial atmospheric CO2 concentrations were ~250 ppm and ~280 ppm prior and after the MBE, respectively. Yet, the cause for this change in atmospheric CO2 remains mainly unknown. climate simulations suggest that oceanic circulation was different during the interglacials due to the different climate states (Yin, 2013). The changes of oceanic circulation could have modified the carbon cycle: a more sluggish circulation would lead to greater carbon sequestration in the deep ocean and, subsequently, a decrease of atmospheric CO2. However, the impact of oceanic circulation changes on the carbon cycle during the interglacials of the last 800 kyrs has never been tested in coupled carbon-climate models. Here, we evaluate the role of ocean circulation changes on the carbon cycle during interglacials by using the intermediate complexity model iLOVECLIM (Goosse et al., 2010 ; Bouttes et al., 2015). This model includes a carbon cycle module on land and in the ocean and simulates carbon isotopes. The interglacial simulations are forced with orbital parameters, ice sheets and CO2 concentrations from data reconstructions. The model computes carbon fluxes between the reservoirs and an atmospheric CO2 that is distinct from the one used as a forcing. We will present simulations from this climate model for different interglacial periods of the last 800 000 years and use model-data comparison to analyse and evaluate the changes in the carbon cycle, including CO2. References Bouttes, N. et al. (2015), Geosci. Model

  14. Low concentration CO2 capture using physical adsorbents: Are Metal-Organic Frameworks becoming the new benchmark materials?

    KAUST Repository

    Belmabkhout, Youssef

    2016-03-30

    The capture and separation of traces and concentrated CO2 from important commodities such as CH4, H2, O2 and N2, is becoming important in many areas related to energy security and environmental sustainability. While trace CO2 concentration removal applications have been modestly studied for decades, the spike in interest in the capture of concentrated CO2 was motivated by the need for new energy vectors to replace highly concentrated carbon fuels and the necessity to reduce emissions from fossil fuel-fired power plants. CO2 capture from various gas streams, at different concentrations, using physical adsorbents, such as activated carbon, zeolites, and metal-organic frameworks (MOFs), is attractive. However, the adsorbents must be designed with consideration of many parameters including CO2 affinity, kinetics, energetics, stability, capture mechanism, in addition to cost. Here, we perform a systematic analysis regarding the key technical parameters that are required for the best CO2 capture performance using physical adsorbents. We also experimentally demonstrate a suitable material model of Metal Organic Framework as advanced adsorbents with unprecedented properties for CO2 capture in a wide range of CO2 concentration. These recently developed class of MOF adsorbents represent a breakthrough finding in the removal of traces CO2 using physical adsorption. This platform shows colossal tuning potential for more efficient separation agents.

  15. Salt concentrations during water production resulting from CO2 storage

    DEFF Research Database (Denmark)

    Walter, Lena; Class, Holger; Binning, Philip John

    2014-01-01

    present in the saline aquifer. The brine can be displaced over large areas and can reach shallower groundwater resources. High salt concentrations could lead to a degradation of groundwater quality. For water suppliers the most important information is whether and how much salt is produced at a water...... production well. In this approach the salt concentrations at water production wells depending on different parameters are determined for the assumption of a 2D model domain accounting for groundwater flow. Recognized ignorance resulting from grid resolution is qualitatively studied and statistical...... polynomial chaos expansion (aPC) [1]. The aPC is applied in this work to provide probabilities and risk values for salt concentrations at the water production well. Mixing in the aquifer has a key influence on the salt concentration at the well. Dispersion and diffusion are the relevant processes for mixing...

  16. The behavior and concentration of CO2 in the suboceanic mantle: Inferences from undegassed ocean ridge and ocean island basalts

    Science.gov (United States)

    Michael, Peter J.; Graham, David W.

    2015-11-01

    ppm, while primary NMORB magmas (> 500 km from ocean island hotspots) have 1840 ppm CO2. The annual flux of CO2 from mid-ocean ridges is 1.25 ± 0.16 × 1014 g/yr, with possible values as low as 0.93 and as high as 1.61 × 1014 g/yr. This amount is equivalent to approximately 0.3% of the anthropogenic addition of CO2 to Earth's atmosphere. NMORB mantle has 183 ppm CO2 (50 ppm C) based on simple melting models and 13% melting. More realistic estimates of incompatible element concentrations in the depleted mantle that are consistent with complex melting models yield much lower estimates for CO2 in the depleted mantle: around 60-130 ppm CO2, with large uncertainties that are more related to melting models than to CO2/Ba. CO2/Ba is not correlated with isotopic or trace element ratios, but there may be systematic regional mantle variations. Iceland melt inclusions and Gakkel Ridge MORBs have lower CO2/Ba ratios, showing that these regional high Ba anomalies are not accompanied by correspondingly high CO2 concentrations.

  17. A possible CO2 conducting and concentrating mechanism in plant stomata SLAC1 channel.

    Directory of Open Access Journals (Sweden)

    Qi-Shi Du

    Full Text Available BACKGROUND: The plant SLAC1 is a slow anion channel in the membrane of stomatal guard cells, which controls the turgor pressure in the aperture-defining guard cells, thereby regulating the exchange of water vapour and photosynthetic gases in response to environmental signals such as drought, high levels of carbon dioxide, and bacterial invasion. Recent study demonstrated that bicarbonate is a small-molecule activator of SLAC1. Higher CO(2 and HCO(3(- concentration activates S-type anion channel currents in wild-type Arabidopsis guard cells. Based on the SLAC1 structure a theoretical model is derived to illustrate the activation of bicarbonate to SLAC1 channel. Meanwhile a possible CO(2 conducting and concentrating mechanism of the SLAC1 is proposed. METHODOLOGY: The homology structure of Arabidopsis thaliana SLAC1 (AtSLAC1 provides the structural basis for study of the conducting and concentrating mechanism of carbon dioxide in SLAC1 channels. The pK(a values of ionizable amino acid side chains in AtSLAC1 are calculated using software PROPKA3.0, and the concentration of CO(2 and anion HCO(3(- are computed based on the chemical equilibrium theory. CONCLUSIONS: The AtSLAC1 is modeled as a five-region channel with different pH values. The top and bottom layers of channel are the alkaline residue-dominated regions, and in the middle of channel there is the acidic region surrounding acidic residues His332. The CO(2 concentration is enhanced around 10(4 times by the pH difference between these regions, and CO(2 is stored in the hydrophobic region, which is a CO(2 pool. The pH driven CO(2 conduction from outside to inside balances the back electromotive force and maintain the influx of anions (e.g. Cl(- and NO(3(- from inside to outside. SLAC1 may be a pathway providing CO(2 for photosynthesis in the guard cells.

  18. Atmospheric CO2 concentration effects on rice water use and biomass production.

    Science.gov (United States)

    Kumar, Uttam; Quick, William Paul; Barrios, Marilou; Sta Cruz, Pompe C; Dingkuhn, Michael

    2017-01-01

    Numerous studies have addressed effects of rising atmospheric CO2 concentration on rice biomass production and yield but effects on crop water use are less well understood. Irrigated rice evapotranspiration (ET) is composed of floodwater evaporation and canopy transpiration. Crop coefficient Kc (ET over potential ET, or ETo) is crop specific according to FAO, but may decrease as CO2 concentration rises. A sunlit growth chamber experiment was conducted in the Philippines, exposing 1.44-m2 canopies of IR72 rice to four constant CO2 levels (195, 390, 780 and 1560 ppmv). Crop geometry and management emulated field conditions. In two wet (WS) and two dry (DS) seasons, final aboveground dry weight (agdw) was measured. At 390 ppmv [CO2] (current ambient level), agdw averaged 1744 g m-2, similar to field although solar radiation was only 61% of ambient. Reduction to 195 ppmv [CO2] reduced agdw to 56±5% (SE), increase to 780 ppmv increased agdw to 128±8%, and 1560 ppmv increased agdw to 142±5%. In 2013WS, crop ET was measured by weighing the water extracted daily from the chambers by the air conditioners controlling air humidity. Chamber ETo was calculated according to FAO and empirically corrected via observed pan evaporation in chamber vs. field. For 390 ppmv [CO2], Kc was about 1 during crop establishment but increased to about 3 at flowering. 195 ppmv CO2 reduced Kc, 780 ppmv increased it, but at 1560 ppmv it declined. Whole-season crop water use was 564 mm (195 ppmv), 719 mm (390 ppmv), 928 mm (780 ppmv) and 803 mm (1560 ppmv). With increasing [CO2], crop water use efficiency (WUE) gradually increased from 1.59 g kg-1 (195 ppmv) to 2.88 g kg-1 (1560 ppmv). Transpiration efficiency (TE) measured on flag leaves responded more strongly to [CO2] than WUE. Responses of some morphological traits are also reported. In conclusion, increased CO2 promotes biomass more than water use of irrigated rice, causing increased WUE, but it does not help saving water. Comparability

  19. Atmospheric CO2 concentration effects on rice water use and biomass production

    Science.gov (United States)

    Kumar, Uttam; Quick, William Paul; Barrios, Marilou; Sta Cruz, Pompe C.; Dingkuhn, Michael

    2017-01-01

    Numerous studies have addressed effects of rising atmospheric CO2 concentration on rice biomass production and yield but effects on crop water use are less well understood. Irrigated rice evapotranspiration (ET) is composed of floodwater evaporation and canopy transpiration. Crop coefficient Kc (ET over potential ET, or ETo) is crop specific according to FAO, but may decrease as CO2 concentration rises. A sunlit growth chamber experiment was conducted in the Philippines, exposing 1.44-m2 canopies of IR72 rice to four constant CO2 levels (195, 390, 780 and 1560 ppmv). Crop geometry and management emulated field conditions. In two wet (WS) and two dry (DS) seasons, final aboveground dry weight (agdw) was measured. At 390 ppmv [CO2] (current ambient level), agdw averaged 1744 g m-2, similar to field although solar radiation was only 61% of ambient. Reduction to 195 ppmv [CO2] reduced agdw to 56±5% (SE), increase to 780 ppmv increased agdw to 128±8%, and 1560 ppmv increased agdw to 142±5%. In 2013WS, crop ET was measured by weighing the water extracted daily from the chambers by the air conditioners controlling air humidity. Chamber ETo was calculated according to FAO and empirically corrected via observed pan evaporation in chamber vs. field. For 390 ppmv [CO2], Kc was about 1 during crop establishment but increased to about 3 at flowering. 195 ppmv CO2 reduced Kc, 780 ppmv increased it, but at 1560 ppmv it declined. Whole-season crop water use was 564 mm (195 ppmv), 719 mm (390 ppmv), 928 mm (780 ppmv) and 803 mm (1560 ppmv). With increasing [CO2], crop water use efficiency (WUE) gradually increased from 1.59 g kg-1 (195 ppmv) to 2.88 g kg-1 (1560 ppmv). Transpiration efficiency (TE) measured on flag leaves responded more strongly to [CO2] than WUE. Responses of some morphological traits are also reported. In conclusion, increased CO2 promotes biomass more than water use of irrigated rice, causing increased WUE, but it does not help saving water. Comparability

  20. System-level modeling for geological storage of CO2

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yingqi; Oldenburg, Curtis M.; Finsterle, Stefan; Bodvarsson, Gudmundur S.

    2006-04-24

    One way to reduce the effects of anthropogenic greenhousegases on climate is to inject carbon dioxide (CO2) from industrialsources into deep geological formations such as brine formations ordepleted oil or gas reservoirs. Research has and is being conducted toimprove understanding of factors affecting particular aspects ofgeological CO2 storage, such as performance, capacity, and health, safetyand environmental (HSE) issues, as well as to lower the cost of CO2capture and related processes. However, there has been less emphasis todate on system-level analyses of geological CO2 storage that considergeological, economic, and environmental issues by linking detailedrepresentations of engineering components and associated economic models.The objective of this study is to develop a system-level model forgeological CO2 storage, including CO2 capture and separation,compression, pipeline transportation to the storage site, and CO2injection. Within our system model we are incorporating detailedreservoir simulations of CO2 injection and potential leakage withassociated HSE effects. The platform of the system-level modelingisGoldSim [GoldSim, 2006]. The application of the system model is focusedon evaluating the feasibility of carbon sequestration with enhanced gasrecovery (CSEGR) in the Rio Vista region of California. The reservoirsimulations are performed using a special module of the TOUGH2 simulator,EOS7C, for multicomponent gas mixtures of methane and CO2 or methane andnitrogen. Using this approach, the economic benefits of enhanced gasrecovery can be directly weighed against the costs, risks, and benefitsof CO2 injection.

  1. An attempt at estimating Paris area CO2 emissions from atmospheric concentration measurements

    Science.gov (United States)

    Bréon, F. M.; Broquet, G.; Puygrenier, V.; Chevallier, F.; Xueref-Remy, I.; Ramonet, M.; Dieudonné, E.; Lopez, M.; Schmidt, M.; Perrussel, O.; Ciais, P.

    2015-02-01

    Atmospheric concentration measurements are used to adjust the daily to monthly budget of fossil fuel CO2 emissions of the Paris urban area from the prior estimates established by the Airparif local air quality agency. Five atmospheric monitoring sites are available, including one at the top of the Eiffel Tower. The atmospheric inversion is based on a Bayesian approach, and relies on an atmospheric transport model with a spatial resolution of 2 km with boundary conditions from a global coarse grid transport model. The inversion adjusts prior knowledge about the anthropogenic and biogenic CO2 fluxes from the Airparif inventory and an ecosystem model, respectively, with corrections at a temporal resolution of 6 h, while keeping the spatial distribution from the emission inventory. These corrections are based on assumptions regarding the temporal autocorrelation of prior emissions uncertainties within the daily cycle, and from day to day. The comparison of the measurements against the atmospheric transport simulation driven by the a priori CO2 surface fluxes shows significant differences upwind of the Paris urban area, which suggests a large and uncertain contribution from distant sources and sinks to the CO2 concentration variability. This contribution advocates that the inversion should aim at minimising model-data misfits in upwind-downwind gradients rather than misfits in mole fractions at individual sites. Another conclusion of the direct model-measurement comparison is that the CO2 variability at the top of the Eiffel Tower is large and poorly represented by the model for most wind speeds and directions. The model's inability to reproduce the CO2 variability at the heart of the city makes such measurements ill-suited for the inversion. This and the need to constrain the budgets for the whole city suggests the assimilation of upwind-downwind mole fraction gradients between sites at the edge of the urban area only. The inversion significantly improves the agreement

  2. 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.

  3. Effect of CO2 concentrations on the activity of photosynthetic CO2 fixation and extracelluar carbonic anhydrase in the marine diatom Skeletonema costatum

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiongwen; GAO Kunshan

    2003-01-01

    The growth and activity of photosynthetic CO2 uptake and extracellular carbonic anhydrase (Caext) of the marine diatom Skeletonema costatum were investigated while cultured at different levels of CO2 in order to see its physiological response to different CO2 concentrations under either a low (30 μmol·m-2·s-1) or high (210 μmol·m-2·s-1) irradiance. The changes in CO2 concentrations (4-31 μmol/L) affected the growth and net photosynthesis to a greater extent under the low than under the high light regime. Caext was detected in the cells grown at 4 μmol/L CO2 but not at 31 and 12 μmol/L CO2, with its activity being about 2.5-fold higher at the high than at the low irradiance. Photo- synthetic CO2 affinity (1/ K1/2(CO2)) of the cells decreased with increased CO2 concentrations in culture. The cells cultured under the high-light show significantly higher photosynthetic CO2 affinity than those grown at the low-light level. It is concluded that the regulations of Caext activity and photosynthetic CO2 affinity are dependent not only on CO2 concentration but also on light availability, and that the development of higher Caext activity and CO2 affinity under higher light level could sufficiently support the photosynthetic demand for CO2 even at low level of CO2.

  4. 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.

  5. Carbon dioxide consumption of the microalga Scenedesmus obtusiusculus under transient inlet CO2 concentration variations.

    Science.gov (United States)

    Cabello, Juan; Morales, Marcia; Revah, Sergio

    2017-04-15

    The extensive microalgae diversity offers considerable versatility for a wide range of biotechnological applications in environmental and production processes. Microalgal cultivation is based on CO2 fixation via photosynthesis and, consequently, it is necessary to evaluate, in a short time and reliable way, the effect of the CO2 gas concentration on the consumption rate and establish the tolerance range of different strains and the amount of inorganic carbon that can be incorporated into biomass in order to establish the potential for industrial scale application. Dynamic experiments allow calculating the short-term microalgal photosynthetic activity of strains in photobioreactors. In this paper, the effect of step-changes in CO2 concentration fed to a 20L bubble column photobioreactor on the CO2 consumption rate of Scenedesmus obtusiusculus was evaluated at different operation times. The highest apparent CO2 consumption rate (336μmolm(-2)s(-1) and 5.6% of CO2) was 6530mgCO2gb(-1)d(-1) and it decreased to 222mgCO2gb(-1)d(-1) when biomass concentration increased of 0.5 to 3.1gbL(-1) and 5.6% of CO2 was fed. For low CO2 concentrations (<3.8%) the pH remained close to the optimal value (7.5 and 8). The CO2 consumption rates show that S. obtusiusculus was not limited by CO2 availability for concentrations above of 3.8%. The CO2 mass balance showed that 90% of the C-CO2 transferred was used for S. obtusiusculus growth. Copyright © 2017. Published by Elsevier B.V.

  6. Development of new measuring technique using sound velocity for CO2 concentration in Cameroonian volcanic lakes

    Science.gov (United States)

    Sanemasa, M.; Saiki, K.; Kaneko, K.; Ohba, T.; Kusakabe, M.; Tanyileke, G.; Hell, J.

    2012-12-01

    1. Introduction Limnic eruptions at Lakes Monoun and Nyos in Cameroon, which are sudden degassing of magmatic CO2 dissolved in the lake water, occurred in 1984 and 1986, respectively. The disasters killed about 1800 people around the lakes. Because of ongoing CO2 accumulation in the bottom water of the lakes, tragedy of limnic eruptions will possibly occur again. To prevent from further disasters, artificial degassing of CO2 from the lake waters has been undergoing. Additionally, CO2 monitoring of the lake waters is needed. Nevertheless, CO2 measurement is done only once or twice a year because current methods of CO2 measurement, which require chemical analysis of water samples, are not suitable for frequent measurement. In engineering field, on the other hand, a method to measure salt concentration using sound velocity has been proposed (Kleis and Sanchez, 1990). This method allows us to evaluate solute concentration fast. We applied the method to dissolved CO2 and examined the correlation between sound velocity and CO2 concentration in laboratory experiment. Furthermore, using the obtained correlation, we tried to estimate the CO2 concentration of waters in the Cameroonian lakes. 2. Laboratory experiment We examined the correlation between sound velocity and CO2 concentration. A profiler (Minos X, made by AML oceanography) and pure water were packed in cylindrical stainless vessel and high-pressure CO2 gas was injected to produce carbonated water. The profiler recorded temperature, pressure and sound velocity. Change of sound velocity was defined as difference of sound velocity between carbonated water and pure water under the same temperature and pressure conditions. CO2 concentration was calculated by Henry's law. The result indicated that the change of sound velocity [m s-1] is proportional to CO2 concentration [mmol kg-1], and the coefficient is 0.021 [m kg s-1 mmol-1]. 3. Field application Depth profiles of sound velocity, pressure, and temperature of Lakes

  7. MODEL SIMULASI EMISI DAN PENYERAPAN CO2 DI KOTA BOGOR

    Directory of Open Access Journals (Sweden)

    Rizka Permatayakti Rasyidta Nur

    2015-04-01

    Full Text Available Most of the urban pollution is the result of carbon dioxide (CO2 emission from human activities. This research identified CO2 emission and absorption in Bogor, and also the alternatives to solve the emission problem by system model and simulation. CO2 emission and absorption system model was created using software Stella 9.0.2 based on loss-gain emission concept for 30 years prediction. Human activities that contribute to CO2 emission are transportation, industries, energy consumption such as fuel or electricity, house hold waste, and farms, while the decrease factor is green open spaces as CO2 sequester. The alternatives to solve emission problem in Bogor is created based on green city concept by including the environmental aspects in every urban activity. The result of this research, the CO2 emission of Bogor reached 20.027.878 tons and the absorption reached 93.843 tons in 2042. Combined mitigation alternatives in several sectors could reduce CO2 emission by 2.797.667 tons in 2042 and CO2 emission could be neutralized by reforestation in 2036.

  8. Mesoscale modelling of atmospheric CO2 across Denmark

    DEFF Research Database (Denmark)

    Lansø, Anne Sofie

    2016-01-01

    of the simulated atmospheric CO2 across Denmark was, in particular, affected by the Danish terrestrial surface exchanges and its temporal variability. This study urges all future modelling studies of air–sea CO2 to include short-term variability in pCO2. To capture the full heterogeneity of the surface exchanges......It is scientifically well-established that the increase of atmospheric CO2 affects the entire globe and will lead to higher surface temperatures. Although anthropogenic CO2is emitted straight into the atmosphere, it does not all contribute to the existing atmospheric CO2 reservoir. Approximately 29......% is taken up by the global oceans, due to under-saturation of CO2 in the surface waters, while another 33 % is taken up by the terrestrial biosphere, via photosynthesis. In order to estimate the effects of increasing anthropogenic emissions of CO2 more accurately in the future, it is essential to understand...

  9. Impact of elevated CO2 concentration under three soil water levels on growth of Cinnamomum camphora

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Forest plays very important roles in global system with about 35% land area producing about 70% of total land net production. It is important to consider both elevated CO2 concentrations and different soil moisture when the possible effects of elevated CO2 concentration on trees are assessed. In this study, we grew Cinnamomum camphora seedlings under two CO2 concentrations (350 μmol/mol and 500 μmol/mol) and three soil moisture levels [80%, 60% and 40% FWC (field water capacity)] to focus on the effects of exposure of trees to elevated CO2 on underground and aboveground plant growth, and its dependence on soil moisture. The results indicated that high CO2 concentration has no significant effects on shoot height but significantly impacts shoot weight and ratio of shoot weight to height under three soil moisture levels. The response of root growth to CO2 enrichment is just reversed, there are obvious effects on root length growth, but no effects on root weight growth and ratio of root weight to length. The CO2 enrichment decreased 20.42%, 32.78%, 20.59% of weight ratio of root to shoot under 40%, 60% and 80% FWC soil water conditions, respectively. And elevated CO2 concentration significantly increased the water content in aboveground and underground parts. Then we concluded that high CO2 concentration favours more tree aboveground biomass growth than underground biomass growth under favorable soil water conditions. And CO2 enrichment enhanced lateral growth of shoot and vertical growth of root. The responses of plants to elevated CO2 depend on soil water availability, and plants may benefit more from CO2 enrichment with sufficient water supply.

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

    Science.gov (United States)

    Osada, Noriyuki; Onoda, Yusuke; Hikosaka, Kouki

    2010-09-01

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

  11. Increasing atmospheric humidity and CO2 concentration alleviate forest hydraulic failure risk

    Science.gov (United States)

    Liu, Y.; Parolari, A.; Kumar, M.; Porporato, A. M.; Katul, G. G.

    2016-12-01

    Climate-induced forest mortality is being observed throughout the globe and has the potential to alter ecosystem services provided by forests. Recent studies suggest that forest mortality is expected to be exacerbated under climate change due to intensified water and heat stress. While few dispute the claim that the compound effect of reduced soil water and increased heat stress increases the probability of forest mortality, impacts of other aspects of climate change have not been explored. Specifically, the impacts of concurrent changes in atmospheric humidity and atmospheric CO2 concentration, which may influence stomatal kinetics in ways that allow plants to operate despite reduced plant hydraulic capacity, remain unaddressed. Here, the risk of hydraulic failure (HFR), one of the key factors contributing to forest mortality is investigated by setting up a dynamic soil-plant-atmospheric model. The coupled and isolated responses of HFR to changes in precipitation amount and seasonality, air temperature, atmospheric humidity, and atmospheric CO2 concentration are analyzed. By incorporating CMIP5 climate projections, the synthetic future responses of HFR for 13 forest biomes across the globe are examined. The results indicate that while HFR is predicted to increase under shifting precipitation patterns and elevated air temperature, the increasing risks may be partly compensated by increases in atmospheric humidity and CO2 concentration. The alleviating effects are likely to be more significant for broadleaf forests than those for needleleaf forests. Our findings suggest that contributions of atmospheric humidity and CO2 concentration on HFR, independently of other effects such as seed production, germination, spread, disease outbreak, and resource competition at the community level, may lead to lower risks of forest mortality than previously thought.

  12. An attempt at estimating Paris area CO2 emissions from atmospheric concentration measurements

    Directory of Open Access Journals (Sweden)

    F. M. Bréon

    2014-04-01

    Full Text Available Atmospheric concentration measurements are used to adjust the daily to monthly budget of CO2 emissions from the AirParif inventory of the Paris agglomeration. We use 5 atmospheric monitoring sites including one at the top of the Eiffel tower. The atmospheric inversion is based on a Bayesian approach, and relies on an atmospheric transport model with a spatial resolution of 2 km with boundary conditions from a global coarse grid transport model. The inversion tool adjusts the CO2 fluxes (anthropogenic and biogenic with a temporal resolution of 6 h, assuming temporal correlation of emissions uncertainties within the daily cycle and from day to day, while keeping the a priori spatial distribution from the emission inventory. The inversion significantly improves the agreement between measured and modelled concentrations. However, the amplitude of the atmospheric transport errors is often large compared to the CO2 gradients between the sites that are used to estimate the fluxes, in particular for the Eiffel tower station. In addition, we sometime observe large model-measurement differences upwind from the Paris agglomeration, which confirms the large and poorly constrained contribution from distant sources and sinks included in the prescribed CO2 boundary conditions These results suggest that (i the Eiffel measurements at 300 m above ground cannot be used with the current system and (ii the inversion shall rely on the measured upwind-downwind gradients rather than the raw mole fraction measurements. With such setup, realistic emissions are retrieved for two 30 day periods. Similar inversions over longer periods are necessary for a proper evaluation of the results.

  13. A framework for comparing remotely sensed and in-situ CO2 concentrations

    Directory of Open Access Journals (Sweden)

    R. Ahmadov

    2008-05-01

    Full Text Available A framework has been developed that allows validating CO2 column averaged volume mixing ratios (VMRs retrieved from ground-based solar absorption measurements using Fourier transform infrared spectrometry (FTS against measurements made in-situ (such as from aircrafts and tall towers. Since in-situ measurements are done frequently and at high accuracy on the global calibration scale, linking this scale with FTS total column retrievals ultimately provides a calibration scale for remote sensing. FTS, tower and aircraft data were analyzed from measurements during the CarboEurope Regional Experiment Strategy (CERES from May to June 2005 in Biscarrosse, France. Carbon dioxide VMRs from the MetAir Dimona aircraft, the TM3 global transport model and Observations of the Middle Stratosphere (OMS balloon based experiments were combined and integrated to compare with the FTS measurements. The comparison allows for calibrating the retrieved carbon dioxide VMRs from the FTS. The Stochastic Time Inverted Lagrangian Transport (STILT model was then utilized to identify differences in surface influence regions or footprints between the FTS and the aircraft CO2 concentrations. Additionally, the STILT model was used to compare carbon dioxide concentrations from a tall tower situated in close proximity to the FTS station. The STILT model was then modified to produce column concentrations of CO2 to facilitate comparison with the FTS data. These comparisons were additionally verified by using the Weather Research and Forecasting – Vegetation Photosynthesis and Respiration Model (WRF-VPRM. The differences between the model-tower and the model-FTS were then used to calculate an effective bias of approximately −2.5 ppm between the FTS and the tower. This bias is attributed to the scaling factor used in the FTS CO2 data, which was to a large extent derived from the aircraft measurements made within a 50 km distance from the FTS station: spatial heterogeneity of carbon

  14. Growth under elevated atmospheric CO(2) concentration accelerates leaf senescence in sunflower (Helianthus annuus L.) plants.

    Science.gov (United States)

    de la Mata, Lourdes; Cabello, Purificación; de la Haba, Purificación; Agüera, Eloísa

    2012-09-15

    Some morphogenetic and metabolic processes were sensitive to a high atmospheric CO(2) concentration during sunflower primary leaf ontogeny. Young leaves of sunflower plants growing under elevated CO(2) concentration exhibited increased growth, as reflected by the high specific leaf mass referred to as dry weight in young leaves (16 days). The content of photosynthetic pigments decreased with leaf development, especially in plants grown under elevated CO(2) concentrations, suggesting that high CO(2) accelerates chlorophyll degradation, and also possibly leaf senescence. Elevated CO(2) concentration increased the oxidative stress in sunflower plants by increasing H(2)O(2) levels and decreasing activity of antioxidant enzymes such as catalase and ascorbate peroxidase. The loss of plant defenses probably increases the concentration of reactive oxygen species in the chloroplast, decreasing the photosynthetic pigment content as a result. Elevated CO(2) concentration was found to boost photosynthetic CO(2) fixation, especially in young leaves. High CO(2) also increased the starch and soluble sugar contents (glucose and fructose) and the C/N ratio during sunflower primary leaf development. At the beginning of senescence, we observed a strong increase in the hexoses to sucrose ratio that was especially marked at high CO(2) concentration. These results indicate that elevated CO(2) concentration could promote leaf senescence in sunflower plants by affecting the soluble sugar levels, the C/N ratio and the oxidative status during leaf ontogeny. It is likely that systemic signals produced in plants grown with elevated CO(2), lead to early senescence and a higher oxidation state of the cells of these plant leaves.

  15. Effect of elevated ambient CO2 concentration on water use efficiency of Pinus sylvestriformis

    Institute of Scientific and Technical Information of China (English)

    Han Shijie; Zhang Junhui; Wang Chenrui; Zou Chunjing; Zhou Yumei; Wang Xiaochun

    1999-01-01

    Pinus sylvestriformis is an important species as an indicator of global climate changes in Changbai Mountain, China. The water use efficiency (WUE) of this species ( 11-year old ) was studied on response to elevated CO2 concentration at 500± 100 μL· L-1 by directly injecting CO2 into the canopy under natural condition in 1998-1999. The results showed that the elevated CO2 concentration reduced averagely stomatal opening, stomatal conductance and stomatal density to 78%, 80% and 87% respectively, as compared to normal ambient. The elevated CO2 reduced the transpiration and enhances the water use efficiency (WUE) of plant.

  16. Modeling global atmospheric CO2 with improved emission inventories and CO2 production from the oxidation of other carbon species

    Energy Technology Data Exchange (ETDEWEB)

    Nassar, Ray [University of Toronto; Jones, DBA [University of Toronto; Suntharalingam, P [University of East Anglia, Norwich, United Kingdom; Chen, j. [University of Toronto; Andres, Robert Joseph [ORNL; Wecht, K. J. [Harvard University; Yantosca, R. M. [Harvard University; Kulawik, SS [Jet Propulsion Laboratory, Pasadena, CA; Bowman, K [Jet Propulsion Laboratory, Pasadena, CA; Worden, JR [Jet Propulsion Laboratory, Pasadena, CA; Machida, T [National Institute for Environmental Studies, Japan; Matsueda, H [Meteorological Research Institute, Japan

    2010-01-01

    The use of global three-dimensional (3-D) models with satellite observations of CO2 in inverse modeling studies is an area of growing importance for understanding Earth s carbon cycle. Here we use the GEOS-Chem model (version 8-02-01) CO2 mode with multiple modifications in order to assess their impact on CO2 forward simulations. Modifications include CO2 surface emissions from shipping (0.19 PgC yr 1), 3-D spatially-distributed emissions from aviation (0.16 PgC yr 1), and 3-D chemical production of CO2 (1.05 PgC yr 1). Although CO2 chemical production from the oxidation of CO, CH4 and other carbon gases is recognized as an important contribution to global CO2, it is typically accounted for by conversion from its precursors at the surface rather than in the free troposphere. We base our model 3-D spatial distribution of CO2 chemical production on monthly-averaged loss rates of CO (a key precursor and intermediate in the oxidation of organic carbon) and apply an associated surface correction for inventories that have counted emissions of CO2 precursors as CO2. We also explore the benefit of assimilating satellite observations of CO into GEOS-Chem to obtain an observation-based estimate of the CO2 chemical source. The CO assimilation corrects for an underestimate of atmospheric CO abundances in the model, resulting in increases of as much as 24% in the chemical source during May June 2006, and increasing the global annual estimate of CO2 chemical production from 1.05 to 1.18 Pg C. Comparisons of model CO2 with measurements are carried out in order to investigate the spatial and temporal distributions that result when these new sources are added. Inclusion of CO2 emissions from shipping and aviation are shown to increase the global CO2 latitudinal gradient by just over 0.10 ppm (3%), while the inclusion of CO2 chemical production (and the surface correction) is shown to decrease the latitudinal gradient by about 0.40 ppm (10%) with a complex spatial structure

  17. Modeling global atmospheric CO2 with improved emission inventories and CO2 production from the oxidation of other carbon species

    Directory of Open Access Journals (Sweden)

    K. W. Bowman

    2010-12-01

    Full Text Available The use of global three-dimensional (3-D models with satellite observations of CO2 in inverse modeling studies is an area of growing importance for understanding Earth's carbon cycle. Here we use the GEOS-Chem model (version 8-02-01 CO2 mode with multiple modifications in order to assess their impact on CO2 forward simulations. Modifications include CO2 surface emissions from shipping (~0.19 Pg C yr−1, 3-D spatially-distributed emissions from aviation (~0.16 Pg C yr−1, and 3-D chemical production of CO2 (~1.05 Pg C yr−1. Although CO2 chemical production from the oxidation of CO, CH4 and other carbon gases is recognized as an important contribution to global CO2, it is typically accounted for by conversion from its precursors at the surface rather than in the free troposphere. We base our model 3-D spatial distribution of CO2 chemical production on monthly-averaged loss rates of CO (a key precursor and intermediate in the oxidation of organic carbon and apply an associated surface correction for inventories that have counted emissions of CO2 precursors as CO2. We also explore the benefit of assimilating satellite observations of CO into GEOS-Chem to obtain an observation-based estimate of the CO2 chemical source. The CO assimilation corrects for an underestimate of atmospheric CO abundances in the model, resulting in increases of as much as 24% in the chemical source during May–June 2006, and increasing the global annual estimate of CO2 chemical production from 1.05 to 1.18 Pg C. Comparisons of model CO2 with measurements are carried out in order to investigate the spatial and temporal distributions that result when these new sources are added. Inclusion of CO2 emissions from shipping and aviation are shown to increase the global CO2 latitudinal gradient by just over 0.10 ppm (~3%, while the inclusion of CO2 chemical production (and the surface correction is shown to decrease the latitudinal gradient by about 0.40 ppm (~10% with a complex

  18. Variations of anthropogenic CO2 in urban area deduced by radiocarbon concentration in modern tree rings.

    Science.gov (United States)

    Rakowski, Andrzej Z; Nakamura, Toshio; Pazdur, Anna

    2008-10-01

    Radiocarbon concentration in the atmosphere is significantly lower in areas where man-made emissions of carbon dioxide occur. This phenomenon is known as Suess effect, and is caused by the contamination of clean air with non-radioactive carbon from fossil fuel combustion. The effect is more strongly observed in industrial and densely populated urban areas. Measurements of carbon isotope concentrations in a study area can be compared to those from areas of clear air in order to estimate the amount of carbon dioxide emission from fossil fuel combustion by using a simple mathematical model. This can be calculated using the simple mathematical model. The result of the mathematical model followed in this study suggests that the use of annual rings of trees to obtain the secular variations of 14C concentration of atmospheric CO2 can be useful and efficient for environmental monitoring and modeling of the carbon distribution in local scale.

  19. Measurement of CO2 concentration at high-temperature based on tunable diode laser absorption spectroscopy

    Science.gov (United States)

    Chen, Jiuying; Li, Chuanrong; Zhou, Mei; Liu, Jianguo; Kan, Ruifeng; Xu, Zhenyu

    2017-01-01

    A diode laser sensor based on absorption spectroscopy has been developed for sensitive measurement of CO2 concentration at high-temperature. Measurement of CO2 can provide information about the extent of combustion and mix in a combustor that may be used to improve fuel efficiency. Most methods of in-situ combustion measurement of CO2 use the spectroscopic parameters taken from database like HITEMP which is mainly derived from the theoretical calculation and remains a high degree of uncertainty in the spectroscopic parameters. A fiber-coupled diode laser system for measurement of CO2 in combustion environment by use of the high-temperature spectroscopic parameters which are obtained by experiment was proposed. Survey spectra of the R(50) line of CO2 at 5007.787 cm-1 were recorded at high-temperature and various pressures to determine line intensities. The line intensities form the theoretical foundation for future applications of this diode laser sensor system. Survey spectra of four test gas mixtures containing 5.01%CO2, 10.01%CO2, 20.08%CO2, and 49.82%CO2 were measured to verify the accuracy of the diode laser sensor system. The measured results indicate that this sensor can measure CO2 concentration with 2% uncertainty in high temperatures.

  20. Forsterite Carbonation in Wet-scCO2: Dependence on Adsorbed Water Concentration

    Science.gov (United States)

    Loring, J.; Benezeth, P.; Qafoku, O.; Thompson, C.; Schaef, T.; Bonneville, A.; McGrail, P.; Felmy, A.; Rosso, K.

    2013-12-01

    showed no change with time, and the spectra indicated only the presence of a highly structured water and bicarbonate film. From our cumulative experiments, we conclude that the reactivity of forsterite with wet-scCO2 can be divided into three adsorbed water concentration threshold regimes: (1) Up to ~2 monolayers, only a highly structured and low mobility chemisorbed water and bicarbonate film is present. (2) Between ~2 to ~5 monolayers, limited carbonation occurs then nearly stops. (3) Above ~5 monolayers, continuous carbonation occurs, and magnesite is the dominant product. The results of these studies provide important insights into metal silicate carbonation mechanisms in low water scCO2 environments. They reinforced the concept of a water threshold for carbonation to occur, which has also been demonstrated for steel corrosion in the presence of wet scCO2. These results will also constrain thermodynamic models and molecular dynamic simulations used to predict mineral trapping extent in basaltic host rocks.

  1. Effect of elevated CO2 concentration on microalgal communities in Antarctic pack ice

    Science.gov (United States)

    Coad, Thomas; McMinn, Andrew; Nomura, Daiki; Martin, Andrew

    2016-09-01

    Increased anthropogenic CO2 emissions are causing changes to oceanic pH and CO2 concentrations that will impact many marine organisms, including microalgae. Phytoplankton taxa have shown mixed responses to these changes with some doing well while others have been adversely affected. Here, the photosynthetic response of sea-ice algal communities from Antarctic pack ice (brine and infiltration microbial communities) to a range of CO2 concentrations (400 ppm to 11,000 ppm in brine algae experiments, 400 ppm to 20,000 ppm in the infiltration ice algae experiment) was investigated. Incubations were conducted as part of the Sea-Ice Physics and Ecosystem Experiment II (SIPEX-2) voyage, in the austral spring (September-November), 2012. In the brine incubations, maximum quantum yield (Fv/Fm) and relative electron transfer rate (rETRmax) were highest at ambient and 0.049% (experiment 1) and 0.19% (experiment 2) CO2 concentrations, although, Fv/Fm was consistently between 0.53±0.10-0.68±0.01 across all treatments in both experiments. Highest rETRmax was exhibited by brine cultures exposed to ambient CO2 concentrations (60.15). In a third experiment infiltration ice algal communities were allowed to melt into seawater modified to simulate the changed pH and CO2 concentrations of future springtime ice-edge conditions. Ambient and 0.1% CO2 treatments had the highest growth rates and Fv/Fm values but only the highest CO2 concentration produced a significantly lower rETRmax. These experiments, conducted on natural Antarctic sea-ice algal communities, indicate a strong level of tolerance to elevated CO2 concentrations and suggest that these communities might not be adversely affected by predicted changes in CO2 concentration over the next century.

  2. Characteristics of ground level CO2 concentrations over contrasting land uses in a tropical urban environment

    Science.gov (United States)

    Kishore Kumar, M.; Shiva Nagendra, S. M.

    2015-08-01

    Indian cities feature high human population density, heterogeneous traffic, mixed land-use patterns and mostly tropical meteorological conditions. Characteristics of ambient CO2 concentrations under these distinctive features are very specific and the related studies are limited. This paper presents the characteristics of ground level CO2 concentrations at three contrasting land uses (residential, commercial and industrial) in a tropical urban area of India. The CO2 concentrations were monitored in Chennai city for 31 days at each land use during June-September, 2013. Emissions of CO2 from all the major anthropogenic sources present at the three study sites were also quantified. Results indicated that the daily average CO2 concentrations were high at commercial (467 ± 35.15 ppm) and industrial (464 ± 31.68 ppm) sites than at residential site (448 ± 33.45 ppm). The quantified CO2 emissions were also showed high levels at commercial (1190 tons/day) and industrial sites (8886 tons/day) than at residential site (90 tons/day). On a diurnal scale, CO2 concentrations were low during afternoons and high during the late evenings and early morning hours at all the three types of land use sites. At the urban residential site, the domestic sector had a strong impact on the day time CO2 concentrations, while soil and plant respiration phenomena had a greater control over the night time CO2 concentrations. Further, the CO2 concentrations were high during the stagnation and stable meteorological conditions than the ventilation and unstable conditions.

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

    Science.gov (United States)

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

    2014-12-01

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

  4. Effects of elevated CO2 concentrations on soil microbial respiration and root/rhizosphere respiration in-forest soils

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The two main components of soil respiration,i.e.,root/rhizosphere and microbial respiration,respond differently to elevated atmospheric CO2 concentrations both in mechanism and sensitivity because they have different substrates derived from plant and soil organic matter,respectively.To model the carbon cycle and predict the carbon source/sink of forest ecosystems,we must first understand the relative contributions of root/rhizosphere and microbial respiration to total soil respiration under elevated CO2 concentrations.Root/rhizosphere and soil microbial respiration have been shown to increase,decrease and remain unchanged under elevated CO2 concentrations.A significantly positive relationship between root biomass and root/rhizosphere respiration has been found.Fine roots respond more strongly to elevated CO2 concentrations than coarse roots.Evidence suggests that soil microbial respiration is highly variable and uncertain under elevated CO2 concentrations.Microbial biomass and activity are related or unrelated to rates of microbial respiration.Because substrate availability drives microbial metabolism in soils,it is likely that much of the variability in microbial respiration results from differences in the response of root growth to elevated CO2 concentrations and subsequent changes in substrate production.Biotic and abiotic factors affecting soil respiration were found to affect both root/rhizosphere and microbial respiration.

  5. [Effects of elevated rhizosphere CO2 concentration on the photosynthetic characteristics, yield, and quality of muskmelon].

    Science.gov (United States)

    Liu, Yi-Ling; Sun, Zhou-Ping; Li, Tian-Lai; Gu, Feng-Ying; He, Yu

    2013-10-01

    By using aeroponics culture system, this paper studied the effects of elevated rhizosphere CO2 concentration on the leaf photosynthesis and the fruit yield and quality of muskmelon during its anthesis-fruiting period. In the fruit development period of muskmelon, as compared with those in the control (350 microL CO2 x L (-1)), the leaf chlorophyll content, net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), and the maximal photochemical efficiency of PS II (Fv/Fm) in treatments 2500 and 5000 microL CO2 x L(-1) decreased to some extents, but the stomatal limitation value (Ls) increased significantly, and the variation amplitudes were larger in treatment 5000 microL CO2 x L(-1) than in treatment 2500 microL CO2 x L(-1). Under the effects of elevated rhizosphere CO2 concentration, the fruit yield per plant and the Vc and soluble sugar contents in fruits decreased markedly, while the fruit organic acid content was in adverse. It was suggested that when the rhizosphere CO2 concentration of muskmelon during its anthesis-fruiting period reached to 2500 microL x L(-1), the leaf photosynthesis and fruit development of muskmelon would be depressed obviously, which would result in the decrease of fruit yield and quality of muskmelon.

  6. Photorespiration and carbon concentrating mechanisms: two adaptations to high O2, low CO2 conditions.

    Science.gov (United States)

    Moroney, James V; Jungnick, Nadine; Dimario, Robert J; Longstreth, David J

    2013-11-01

    This review presents an overview of the two ways that cyanobacteria, algae, and plants have adapted to high O2 and low CO2 concentrations in the environment. First, the process of photorespiration enables photosynthetic organisms to recycle phosphoglycolate formed by the oxygenase reaction catalyzed by ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Second, there are a number of carbon concentrating mechanisms that increase the CO2 concentration around Rubisco which increases the carboxylase reaction enhancing CO2 fixation. This review also presents possibilities for the beneficial modification of these processes with the goal of improving future crop yields.

  7. Stomatal proxy record of CO2 concentrations during the Last Termination demonstrates dynamic climate behaviour and an important role for CO2.

    Science.gov (United States)

    Steinthorsdottir, Margret; Wohlfarth, Barbara; Kylander, Malin E.; Blaauw, Maarten; Reimer, Paula J.

    2013-04-01

    We present a new stomatal proxy-based record of CO2 concentrations spanning Greenland Interstadial 1 (Allerød pollen zone, GI-1a to 1c), Greenland Stadial 1 (Younger Dryas pollen zone, GS-1) and the first part of the Holocene (Preboreal pollen zone). The calibrated atmospheric CO2 concentrations are based on Betula nana (dwarf birch) leaves from a fossil lake sedimentary sequence in south-eastern Sweden. The stomatal proxy method relies on the inverse relationship between stomatal density on plant leaves and atmospheric CO2 concentrations to reconstruct variations in past CO2 concentrations. The record presented here demonstrates that the overall pattern of CO2 evolution during this period was dynamic, with significant abrupt fluctuations in CO2 concentration when the climate moved from interstadial to stadial state and vice versa. The cooling at the GI-1/GS-1 transition was preceded by an abrupt warming, and the warming at the GS-1/Holocene transition was preceded by an abrupt cooling. This scenario is in contrast to CO2 records reconstructed from air bubbles trapped in ice, which indicate a gradual increase in concentrations, but largely in alignment with previously published stomatal proxy-based CO2 records. A new loss-on-ignition chemical record (used here as a proxy for temperature), from the same locality, lends independent support to the CO2 record.

  8. Modeling and Simulation of Nanoparticle Transport in Multiphase Flows in Porous Media: CO2 Sequestration

    KAUST Repository

    El-Amin, Mohamed

    2012-09-03

    Geological storage of anthropogenic CO2 emissions in deep saline aquifers has recently received tremendous attention in the scientific literature. Injected CO2 plume buoyantly accumulates at the top part of the deep aquifer under a sealing cap rock, and some concern that the high-pressure CO2 could breach the seal rock. However, CO2 will diffuse into the brine underneath and generate a slightly denser fluid that may induce instability and convective mixing. Onset times of instability and convective mixing performance depend on the physical properties of the rock and fluids, such as permeability and density contrast. The novel idea is to adding nanoparticles to the injected CO2 to increase density contrast between the CO2-rich brine and the underlying resident brine and, consequently, decrease onset time of instability and increase convective mixing. As far as it goes, only few works address the issues related to mathematical and numerical modeling aspects of the nanoparticles transport phenomena in CO2 storages. In the current work, we will present mathematical models to describe the nanoparticles transport carried by injected CO2 in porous media. Buoyancy and capillary forces as well as Brownian diffusion are important to be considered in the model. IMplicit Pressure Explicit Saturation-Concentration (IMPESC) scheme is used and a numerical simulator is developed to simulate the nanoparticles transport in CO2 storages.

  9. Absorber Model for CO2 Capture by Monoethanolamine

    DEFF Research Database (Denmark)

    Faramarzi, Leila; Kontogeorgis, Georgios; Michelsen, Michael Locht

    2010-01-01

    The rate-based steady-state model proposed by Gabrielsen et al. (Gabrielsen, J.; Michelsen, M. L.; Kontogeorgis, G. M.; Stenby, E. H. AIChE J. 2006, 52, 10, 3443-3451) for the design of the CO2-2-amino-2-methylpropanol absorbers is adopted and improved for the design of the CO2-monoethanolamine...... absorber. The influence of the application of different mass transfer correlations on the model's performance is investigated. Analytical expressions for the calculation of the enhancement factor for the second order as well as the pseudo-first-order reaction regime are integrated in the model......, and their impact on the model's prediction is compared. The model has been successfully applied to CO2 absorber packed columns and validated against pilot plant data with good agreement....

  10. Elevated CO2 concentration impacts cell wall polysaccharide composition of green microalgae of the genus Chlorella.

    Science.gov (United States)

    Cheng, Y-S; Labavitch, J M; VanderGheynst, J S

    2015-01-01

    The effect of CO2 concentration on the relative content of starch, lipid and cell wall carbohydrates in microalgal biomass was investigated for the four following Chlorella strains: C. vulgaris (UTEX 259), C. sorokiniana (UTEX 2805), C. minutissima (UTEX 2341) and C. variabilis (NC64A). Each strain had a different response to CO2 concentration. The starch content was higher in UTEX259 and NC64A cultured with 2% CO2 in the air supply than in cells cultured with ca. 0·04% CO2 (ambient air), while starch content was not affected for UTEX 2805 and UTEX 2341. The lipid content was higher in Chlorella minutissima UTEX 2341 cultured in 2% CO2 than in cells cultured in ambient air, but was unchanged for the other three strains. All four Chlorella strains tended to have a higher percentage of uronic acids and lower percentage of neutral sugars in their cell wall polysaccharide complement when grown with 2% CO2 supply. Although the percentage of neutral sugars in the cell walls varied with CO2 concentration, the relative proportions of different neutral sugar constituents remained constant for both CO2 conditions. The results demonstrate the importance of considering the effects of CO2 on the cell wall carbohydrate composition of microalgae. Microalgae have the potential to produce products that will reduce society's reliance on fossil fuels and address challenges related to food and feed production. An overlooked yet industrially relevant component of microalgae are their cell walls. Cell wall composition affects cell flocculation and the recovery of intracellular products. In this study, we show that increasing CO2 level results in greater cell wall polysaccharide and uronic acid content in the cell walls of three strains of microalgae. The results have implications on the management of systems for the capture of CO2 and production of fuels, chemicals and food from microalgae. © 2014 The Society for Applied Microbiology.

  11. Airborne Measurements of CO2 Column Concentration and Range Using a Pulsed Direct-Detection IPDA Lidar

    Science.gov (United States)

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

    2013-01-01

    We have previously demonstrated a pulsed direct detection IPDA lidar to measure range and the column concentration of atmospheric CO2. The lidar measures the atmospheric backscatter profiles and samples the shape of the 1,572.33 nm CO2 absorption line. We participated in the ASCENDS science flights on the NASA DC-8 aircraft during August 2011 and report here lidar measurements made on four flights over a variety of surface and cloud conditions near the US. These included over a stratus cloud deck over the Pacific Ocean, to a dry lake bed surrounded by mountains in Nevada, to a desert area with a coal-fired power plant, and from the Rocky Mountains to Iowa, with segments with both cumulus and cirrus clouds. Most flights were to altitudes >12 km and had 5-6 altitude steps. Analyses show the retrievals of lidar range, CO2 column absorption, and CO2 mixing ratio worked well when measuring over topography with rapidly changing height and reflectivity, through thin clouds, between cumulus clouds, and to stratus cloud tops. The retrievals shows the decrease in column CO2 due to growing vegetation when flying over Iowa cropland as well as a sudden increase in CO2 concentration near a coal-fired power plant. For regions where the CO2 concentration was relatively constant, the measured CO2 absorption lineshape (averaged for 50 s) matched the predicted shapes to better than 1% RMS error. For 10 s averaging, the scatter in the retrievals was typically 2-3 ppm and was limited by the received signal photon count. Retrievals were made using atmospheric parameters from both an atmospheric model and from in situ temperature and pressure from the aircraft. The retrievals had no free parameters and did not use empirical adjustments, and >70% of the measurements passed screening and were used in analysis. The differences between the lidar-measured retrievals and in situ measured average CO2 column concentrations were 6 km.

  12. Trace and low concentration co2 removal methods and apparatus utilizing metal organic frameworks

    KAUST Repository

    Eddaoudi, Mohamed

    2016-03-10

    In general, this disclosure describes techniques for removing trace and low concentration CO2 from fluids using SIFSIX-n-M MOFs, wherein n is at least two and M is a metal. In some embodiments, the metal is zinc or copper. Embodiments include devices comprising SIFSIX-n-M MOFs for removing CO2 from fluids. In particular, embodiments relate to devices and methods utilizing SIFSIX-n-M MOFs for removing CO2 from fluids, wherein CO2 concentration is trace. Methods utilizing SIFSIX-n-M MOFs for removing CO2 from fluids can occur in confined spaces. SIFSIX-n-M MOFs can comprise bidentate organic ligands. In a specific embodiment, SIFSIX-n-M MOFs comprise pyrazine or dipryidilacetylene ligands.

  13. Stability of a NDIR analyser for CO2 at atmospheric concentration.

    Science.gov (United States)

    Sega, Michela; Amico Di Meane, Elena; Plassa, Margherita

    2002-09-01

    Carbon dioxide monitoring is significant in the environmental field since this gas plays an important role in the greenhouse effect. In order to determine CO2 concentration and to develop simulation models, it is necessary to carry out measurements which are accurate and comparable in time and space, i.e. SI-traceable. Non-dispersive infrared (NDIR) analysers are employed for CO2 measurements, as they are precise and stable. In order to achieve traceability, such instruments have to be characterized and calibrated. At the Istituto di Metrologia "G. Colonnetti"--CNR, a procedure for calibrating NDIR analysers for CO2 at atmospheric level was developed, which enables to calculate a correction for the analyser output. In addition, a complete uncertainty analysis was carried out and a correct traceability chain was established. The goal of the present work is the study of the stability of a NDIR analyser by repeating calibrations during three years and comparing the correction curves obtained to identify a proper re-calibration interval for such analysers. The investigated instrument has good repeatability and reproducibility, hence satisfactory stability during time, as shown by the short-term and long-term compatibility of calibration curves.

  14. 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.

  15. Global Modeling of CO2 Discharges with Aerospace Applications

    Directory of Open Access Journals (Sweden)

    Chloe Berenguer

    2014-01-01

    Full Text Available We developed a global model aiming to study discharges in CO2 under various conditions, pertaining to a large spectrum of pressure, absorbed energy, and feeding values. Various physical conditions and form factors have been investigated. The model was applied to a case of radiofrequency discharge and to helicon type devices functioning in low and high feed conditions. In general, main charged species were found to be CO2+ for sufficiently low pressure cases and O− for higher pressure ones, followed by CO2+, CO+, and O2+ in the latter case. Dominant reaction is dissociation of CO2 resulting into CO production. Electronegativity, important for radiofrequency discharges, increases with pressure, arriving up to 3 for high flow rates for absorbed power of 250 W, and diminishes with increasing absorbed power. Model results pertaining to radiofrequency type plasma discharges are found in satisfactory agreement with those available from an existing experiment. Application to low and high flow rates feedings cases of helicon thruster allowed for evaluation of thruster functioning conditions pertaining to absorbed powers from 50 W to 1.8 kW. The model allows for a detailed evaluation of the CO2 potential to be used as propellant in electric propulsion devices.

  16. COUPLING NORSOK CO2 CORROSION PREDICTION MODEL WITH PIPELINES THERMAL/HYDRAULIC MODELS TO SIMULATE CO2 CORROSION ALONG PIPELINES

    Directory of Open Access Journals (Sweden)

    MOKHTAR CHE ISMAIL

    2011-12-01

    Full Text Available Pipelines transporting oil and gas are vulnerable to internal corrosion when water forms a part of the transported fluids. The presence of carbon dioxide (CO2 in the fluid accelerates the corrosion rate due to its reaction with water which results in forming carbonic acid, and hence, water pH is reduced. The corrosion rate prediction is an important task needed to manage and control the corrosion. The prediction can be carried on by selecting one of many empirical and mechanistic models that developed for corrosion rate prediction. One of these models is NORSOK model, an empirical model developed by NORSOK Norwegian standard for CO2 corrosion prediction in straight pipes. In this paper NORSOK model has been coupled to thermal and hydraulic models to predict CO2 corrosion rate along pipelines.

  17. pH determines the energetic efficiency of the cyanobacterial CO2 concentrating mechanism.

    Science.gov (United States)

    Mangan, Niall M; Flamholz, Avi; Hood, Rachel D; Milo, Ron; Savage, David F

    2016-09-06

    Many carbon-fixing bacteria rely on a CO2 concentrating mechanism (CCM) to elevate the CO2 concentration around the carboxylating enzyme ribulose bisphosphate carboxylase/oxygenase (RuBisCO). The CCM is postulated to simultaneously enhance the rate of carboxylation and minimize oxygenation, a competitive reaction with O2 also catalyzed by RuBisCO. To achieve this effect, the CCM combines two features: active transport of inorganic carbon into the cell and colocalization of carbonic anhydrase and RuBisCO inside proteinaceous microcompartments called carboxysomes. Understanding the significance of the various CCM components requires reconciling biochemical intuition with a quantitative description of the system. To this end, we have developed a mathematical model of the CCM to analyze its energetic costs and the inherent intertwining of physiology and pH. We find that intracellular pH greatly affects the cost of inorganic carbon accumulation. At low pH the inorganic carbon pool contains more of the highly cell-permeable H2CO3, necessitating a substantial expenditure of energy on transport to maintain internal inorganic carbon levels. An intracellular pH ≈8 reduces leakage, making the CCM significantly more energetically efficient. This pH prediction coincides well with our measurement of intracellular pH in a model cyanobacterium. We also demonstrate that CO2 retention in the carboxysome is necessary, whereas selective uptake of HCO3 (-) into the carboxysome would not appreciably enhance energetic efficiency. Altogether, integration of pH produces a model that is quantitatively consistent with cyanobacterial physiology, emphasizing that pH cannot be neglected when describing biological systems interacting with inorganic carbon pools.

  18. Stomatal density and stomatal index as indicators of paleoatmospheric CO(2) concentration.

    Science.gov (United States)

    Royer, D L.

    2001-03-01

    A growing number of studies use the plant species-specific inverse relationship between atmospheric CO(2) concentration and stomatal density (SD) or stomatal index (SI) as a proxy for paleo-CO(2) levels. A total of 285 previously published SD and 145 SI responses to variable CO(2) concentrations from a pool of 176 C(3) plant species are analyzed here to test the reliability of this method. The percentage of responses inversely responding to CO(2) rises from 40 and 36% (for SD and SI, respectively) in experimental studies to 88 and 94% (for SD and SI, respectively) in fossil studies. The inconsistent experimental responses verify previous concerns involving this method, however the high percentage of fossil responses showing an inverse relationship clearly validates the method when applied over time scales of similar length. Furthermore, for all groups of observations, a positive relationship between CO(2) and SD/SI is found in only CO(2) appears to inversely affect stomatal initiation, although the mechanism may involve genetic adaptation and therefore is often not clearly expressed under short CO(2) exposure times.Experimental responses of SD and SI based on open-top chambers (OTCs) inversely relate to CO(2) less often than greenhouse-based responses (P<0.01 for both SD and SI), and should be avoided when experimental responses are required for CO(2) reconstructions. In the combined data set, hypostomatous species follow the inverse relationship more often than amphistomatous species (56 vs. 44% for SD; 69 vs. 32% for SI; P<0.03 for both comparisons). Both the SD and SI of fossil responses are equally likely to inversely relate to CO(2) when exposed to elevated versus subambient CO(2) concentrations (relative to today). This result casts doubt on previous claims that stomata cannot respond to CO(2) concentrations above present-day levels. Although the proportion of SD and SI responses inversely relating to CO(2) are similar, SD is more

  19. 低浓度 CO2捕集的吸收率测算%Absorption rate measurement and calculation of low-concentration CO2 capture technical

    Institute of Scientific and Technical Information of China (English)

    马超援

    2016-01-01

    The paper introduces low-concentration CO2 absorbinf methods,describes the measurement and calculation methods of low-concentra-tion CO2 capture technical and explores the elements of determininf absorbinf afent,which has certain meaninf for control indoor CO2 concentration.%介绍了常用的低浓度 CO2气体吸收方法,就低浓度 CO2捕集吸收率的测算方法进行了阐述,并探讨了确定吸收剂的要素,对室内 CO2浓度的控制有一定的意义。

  20. Influence of CO2 Concentration on Adsorption Behavior of 99Tc in Clay Under Hypoxic Conditions

    Institute of Scientific and Technical Information of China (English)

    SONG; Zhi-xin; BAO; Liang-jin; JIANG; Tao; CHEN; Xi

    2013-01-01

    Under hypoxic conditions,using the Beishan groundwater the influence of the CO2 concentration on the adsorption behavior of 99Tc in the Longdong clay was studied by batch method.Meanwhile,the buffering effect of clay rocks on the pH value of aqueous solution at different CO2 concentrations was discussed.The adsorption behavior of 99Tc on clay at different initial pH values was also researched.

  1. Contrasting CO2 concentration discharge dynamics in headwater streams: A multi-catchment comparison

    Science.gov (United States)

    Dinsmore, K. J.; Wallin, M. B.; Johnson, M. S.; Billett, M. F.; Bishop, K.; Pumpanen, J.; Ojala, A.

    2013-06-01

    CO2 concentrations are highly variable and strongly linked to discharge, but until recently, measurements have been largely restricted to low-frequency manual sampling. Using new in situ CO2 sensors, we present concurrent, high-frequency (data collected from five catchments across Canada, UK, and Fennoscandinavia to explore concentration-discharge dynamics; we also consider the relative importance of high flows to lateral aquatic CO2 export. The catchments encompassed a wide range of mean CO2 concentrations (0.73-3.05 mg C L-1) and hydrological flow regimes from flashy peatland streams to muted outflows within a Finnish lake system. In three of the catchments, CO2 concentrations displayed clear bimodal distributions indicating distinct CO2 sources. Concentration-discharge relationships were not consistent across sites with three of the catchments displaying a negative relationship and two catchments displaying a positive relationship. When individual high flow events were considered, we found a strong correlation between both the average magnitude of the hydrological and CO2 response peaks, and the average response lag times. An analysis of lateral CO2 export showed that in three of the catchments, the top 30% of flow (i.e., flow that was exceeded only 30% of the time) had the greatest influence on total annual load. This indicates that an increase in precipitation extremes (greater high-flow contributions) may have a greater influence on the flushing of CO2 from soils to surface waters than a long-term increase in mean annual precipitation, assuming source limitation does not occur.

  2. CO2 Absorption in a Lab-Scale Fixed Solid Bed Reactor: Modelling and Experimental Tests

    Directory of Open Access Journals (Sweden)

    Roberto Gabbrielli

    2004-09-01

    Full Text Available The CO2 absorption in a lab-scale fixed solid bed reactor filled with different solid sorbents has been studied under different operative conditions regarding temperature (20-200°C and input gas composition (N2, O2, CO2, H2O at 1bar pressure. The gas leaving the reactor has been analysed to measure the CO2 and O2 concentrations and, consequently, to evaluate the overall CO2 removal efficiency. In order to study the influence of solid sorbent type (i.e. CaO, coal bottom ash, limestone and blast furnace slag and of mass and heat transfer processes on CO2 removal efficiency, a one-dimensional time dependent mathematical model of the reactor, which may be considered a Plug Flow Reactor, has been developed. The quality of the model has been confirmed using the experimental results.

  3. A cell-based model for the photoacclimation and CO(2)-acclimation of the photosynthetic apparatus.

    Science.gov (United States)

    Papadakis, I A; Kotzabasis, K; Lika, K

    2005-06-30

    We have developed a mathematical model based on the underlying mechanisms concerning the responses of the photosynthetic apparatus of a microalga cell which grows under constant incident light intensity and ambient CO(2) concentration. Photosynthesis involves light and carbon-fixation reactions which are mutually dependent and affect each other, but existing models for photosynthesis don't account for both reactions at once. Our modeling approach allows us to derive distinct equations for the rates of oxygen production, NADPH production, carbon dioxide fixation, carbohydrate production, and rejected energy, which are generally different. The production rates of the photosynthesis products are hyperbolic functions of light and CO(2) concentration. The model predicts that in the absence of photoinhibition, CO(2)-inhibition, photorespiration, and chlororespiration, a cell acclimated to high light and/or CO(2) concentration has higher photosynthetic capacity and lower photosynthetic efficiency than does a cell acclimated to low conditions. This results in crossing between the two curves which represent the oxygen production rates and carbon fixation rates in low and high conditions. Finally, in the absence of photoinhibition and CO(2)-inhibition, the model predicts the carbohydrate production rate in terms of both light intensity and CO(2) concentration.

  4. Effect of urban parks on CO2 concentrations in Toluca, Mexico

    Science.gov (United States)

    Vieyra Gómez, J. A.; González Sosa, E.; Mastachi-Loza, C. A.; Cervantes, M.; Martínez Valdéz, H.

    2013-05-01

    Despite green areas are used for amusement, they have several benefits such as: microclimate regulation, groundwater recharge, noise abatement, oxygen production and CO2 capture. The last one has a notable importance, as CO2 is considered to be one of the most pollutant gases of the greenhouse effect. The city of Toluca, has a considerable urban growth. However, there are few studies aimed to assess the importance of the green areas in urban locations. About this, it is estimated than only 4m2/hab of vegetal coverage is found in big cities, which means a 50% deficit according to the international standards.The aim of this study was to assess the urban parks impact in Toluca, as regulators of CO2 means through measurements in autumn-winter seasonal period, 2012-2013.It was performed 20 measurements in 4 local parks (Urawa, Alameda, Municipal and Metropolitano), in order to evaluate the possible effect of urban parks on CO2 concentrations. Transects were made inside and outside the parks and the CO2 concentrations were registered by a portable quantifier (GMP343).The data analysis allowed the separation of the parks based on CO2 concentrations; however, it was perceived a decreasing of CO2 inside the parks (370ppm), between 10 and 40 ppm less than those areas with traffic and pedestrians (399 ppm).

  5. Using a Tree Ring δ13C Annual Series to Reconstruct Atmospheric CO2 Concentration over the Past 300 Years

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xing-Yun; QIAN Jun-Long; WANG Jian; HE Qing-Yan; WANG Zu-Liang; CHEN Cheng-Zhong

    2006-01-01

    The annual series of δ13C were measured in tree rings of three Cryptomeria fortunei disks (CF-1, CF-2, and CF 3) collected from West Tianmu Mountain, Zhejiang Province, China, according to cross-dating tree ring ages. There was no obvious decreasing trend of the δ13C annual time series of CF-2 before 1835. However, from 1835 to 1982 the three tree ring δ13C annual series exhibited similar decreasing trends that were significantly (P ≤ 0.001) correlated. The distribution characteristics of a scatter diagram between estimated δ13C series of CF-2 from modeling and the atmospheric CO2 concentration extracted from the Law Dome ice core from 1840 to 1978 were analyzed and a curvilinear regression equation for reconstructing atmospheric CO2 concentration was established with R2 = 0.98.Also, a test of independent samples indicated that between 1685 and 1839 the reconstructed atmospheric CO2 concentration .using the δ13C series of CF-2 had a close relationship with the Law Dome and Siple ice cores, with a standard deviation of 1.98.The general increasing trend of the reconstructed atmospheric CO2 concentration closely reflected the long-term variation of atmospheric CO2 concentration recorded both before and after the Industrial Revolution. Between 1685 and 1840 the evaluated atmospheric CO2 concentration was stable, but after 1840 it exhibited a rapid increase. Given a longer δ13C annual time series of tree rings, it was feasible to rebuild a representative time series to describe the atmospheric CO2 concentration for an earlier period and for years that were not in the ice core record.

  6. Dynamics of dimethylsulphoniopropionate and dimethylsulphide under different CO2 concentrations during a mesocosm experiment

    Directory of Open Access Journals (Sweden)

    C. LeQuéré

    2008-03-01

    Full Text Available The potential impact of seawater acidification on the concentrations of dimethylsulfide (DMS and dimethylsulfoniopropionate (DMSP, and the activity of the enzyme DMSP-lyase was investigated during a pelagic ecosystem CO2 enrichment experiment (PeECE III in spring 2005. Natural phytoplankton blooms were studied for 24 days under present, double and triple partial pressures of CO2 (pCO2; pH=8.3, 8.0, 7.8 in triplicate 25 m3 enclosures. The results indicate similar DMSP concentrations and DMSP-lyase activity (DLA patterns for all treatments. Hence, DMSP and DLA do not seem to have been affected by the CO2 treatment. In contrast, DMS concentrations showed small but statistically significant differences in the temporal development of the low versus the high CO2 treatments. The low pCO2 enclosures had higher DMS concentrations during the first 10 days, after which the levels decreased earlier and more rapidly than in the other treatments. Integrated over the whole study period, DMS concentrations were not significantly different from those of the double and triple pCO2 treatments. Pigment and flow-cytometric data indicate that phytoplanktonic populations were generally similar between the treatments, suggesting a certain resilience of the marine ecosystem under study to the induced pH changes, which is reflected in DMSP and DLA. However, there were significant differences in bacterial community structure and the abundance of one group of viruses infecting nanoeukaryotic algae. The amount of DMS accumulated per total DMSP or chlorophyll-a differed significantly between the present and future scenarios, suggesting that the pathways for DMS production or bacterial DMS consumption were affected by seawater pH. A comparison with previous work (PeECE II suggests that DMS concentrations do not respond consistently to pelagic ecosystem CO2 enrichment experiments.

  7. CMAQ simulation of atmospheric CO2 concentration in East Asia: Comparison with GOSAT observations and ground measurements

    Science.gov (United States)

    Li, Rong; Zhang, Meigen; Chen, Liangfu; Kou, Xingxia; Skorokhod, Andrei

    2017-07-01

    Satellite observations are widely used in global CO2 assimilations, but their quality for use in regional assimilation systems has not yet been thoroughly determined. Validation of satellite observations and model simulations of CO2 is crucial for carbon flux inversions. In this study, we focus on evaluating the uncertainties of model simulations and satellite observations. The atmospheric CO2 distribution in East Asia during 2012 was simulated using a regional chemical transport model (RAMS-CMAQ) and compared with both CO2 column density (XCO2) from the Gases Observing SATellite (GOSAT) and CO2 concentrations from the World Data Centre for Greenhouse Gases (WDCGG). The results indicate that simulated XCO2 is generally lower than GOSAT XCO2 by 1.19 ppm on average, and their monthly differences vary from 0.05 to 2.84 ppm, with the corresponding correlation coefficients ranging between 0.1 and 0.67. CMAQ simulations are good to capture the CO2 variation as ground-based observations, and their correlation coefficients are from 0.62 to 0.93, but the average value of CMAQ simulation is 2.4 ppm higher than ground-based observation. Thus, we inferred that the GOSAT retrievals may overestimate XCO2, which is consistent with the validation of GOSAT XCO2 using Total Carbon Column Observing Network measurements. The near-surface CO2 concentration was obviously overestimated in GOSAT XCO2. Compared with the relatively small difference between CMAQ and GOSAT XCO2, the large difference in CO2 near surface or their vertical profiles indicates more improvements are needed to reduce the uncertainties in both satellite observations and model simulations.

  8. Measurement of Concentration of CO2 in Atmosphere In Situ Based on TDLAS

    Science.gov (United States)

    Xin, Fengxin; Guo, Jinjia; Chen, Zhen; Liu, Zhishen

    2014-11-01

    As one of the main greenhouse gases in the atmosphere, CO2has a significant impact on global climate change and the ecological environment. Because of close relationship between human activities and the CO2 emissions, it is very meaningful of detecting atmospheric CO2accurately. Based on the technology of tunable diode laser absorption spectroscopy, the wavelength of distributed feedback laser is modulated, Fresnel lens is used as the receiving optical system, which receives the laser-beam reflected by corner reflector, and focuses the receiving laser-beam to the photoelectric detector. The second harmonic signal is received through lock-in amplifier and collected by AD data acquisition card, after that the system is built up.By choosing the infrared absorption line of CO2at 1.57μm, the system is calibrated by 100% CO2 gas cell. The atmospheric CO2 in situ is measured with long open-path way. Furthermore, the results show that CO2 concentration decreases along time in the morning of day. It is proved that TDLAS technology has many advantages, including fast response, high sensitivity and resolution. This research provides a technique for monitoring secular change of CO2 in atmosphere.

  9. Intra-aggregate CO2 enrichment: a modelling approach for aerobic soils

    Directory of Open Access Journals (Sweden)

    H. Schack-Kirchner

    2012-10-01

    Full Text Available CO2 concentration gradients inside soil aggregates, caused by the respiration of soil microorganisms and fungal hyphae, might lead to variations in the soil solution chemistry on a mm-scale, and to an underestimation of the CO2 storage. But, up to now, there seems to be no feasible method for measuring CO2 inside natural aggregates with sufficient spatial resolution. We combined a one-dimensional model for gas diffusion in the inter-aggregate pore-space with a cylinder diffusion model, simulating the consumption/production and diffusion of O2 and CO2 inside soil aggregates with air- and water-filled pores. Our model predicts that for aerobic respiration (respiratory quotient = 1 the intra-aggregate increase in the CO2 partial pressure can never be higher than 0.9 kPa for siliceous, and 0.08 kPa for calcaric aggregates, independent of the level of water-saturation. This suggests that only for siliceous aggregates CO2 produced by aerobic respiration might cause a high small-scale spatial variability in the soil solution chemistry. In calcaric aggregates, however, the contribution of carbonate species to the CO2 transport should lead to secondary carbonates on the aggregate surfaces. As regards the total CO2 storage in aerobic soils, both siliceous and calcaric, the effect of intra-aggregate CO2 gradients seems to be negligible. To assess the effect of anaerobic respiration on the intra-aggregate CO2 gradients, the development of a device for measuring CO2 on a mm-scale in soils is indispensable.

  10. Rainfall distribution is the main driver of runoff under future CO2-concentration in a temperate deciduous forest

    Science.gov (United States)

    Leuzinger, S.; Körner, C.

    2009-04-01

    Reduced stomatal conductance under elevated CO2 results in increased soil moisture, provided all other factors remain constant. Whether this results in increased runoff critically depends on the interaction of rainfall patterns, soil water storage capacity and plant responses. To test the sensitivity of runoff to these parameters under elevated CO2, we combine transpiration and soil moisture data from the Swiss Canopy Crane (SCC) FACE experiment with 104 years of daily precipitation data from an adjacent weather station to drive a three-layer bucket model (mean yearly precipitation 794 mm). The model adequately predicts the water budget of a temperate deciduous forest and runoff from a nearby gauging station. A simulation run over all 104 years based on sap flow responses resulted in only 5.5 mm (2.9 %) increased ecosystem runoff under elevated CO2. Out of the 37986 days (1.1.1901 to 31.12.2004), only 576 days produce higher runoff under in the elevated CO2 scenario. Only 1 out of 17 years produces a CO2-signal greater than 20 mma-1, which mostly depends on a few single days when runoff under elevated CO2 exceeds runoff under ambient conditions. The maximum signal for a double pre-industrial CO2-concentration under the past century daily rainfall regime is an additional runoff of 46 mm (year 1938). More than half of all years produce a signal of less than 5 mma-1, because trees consume the 'extra' moisture during prolonged dry weather. Increased runoff under elevated CO2 is 9 times more sensitive to variations in rain pattern than to the applied reduction in transpiration under elevated CO2. Thus the key driver of increased runoff under future CO2-concentration is the day by day rainfall pattern. We argue that increased runoff due to a first-order plant physiological CO2-effect will be very small (<3 %) in the landscape dominated by temperate deciduous forests, and will hardly increase flooding risk in forest catchments. It is likely that these results are equally

  11. The mechanisms of North Atlantic CO2 uptake in a large Earth System Model ensemble

    Directory of Open Access Journals (Sweden)

    P. R. Halloran

    2014-10-01

    vary rapidly. Given the importance of this sink and its apparent variability, it is critical that we understand the mechanisms behind its operation. Here we explore subpolar North Atlantic CO2 uptake across a large ensemble of Earth System Model simulations, and find that models show a peak in sink strength around the middle of the century after which CO2 uptake begins to decline. We identify different drivers of change on interannual and multidecadal timescales. Short-term variability appears to be driven by fluctuations in regional seawater temperature and alkalinity, whereas the longer-term evolution throughout the coming century is largely occurring through a counterintuitive response to rising atmospheric CO2 concentrations. At high atmospheric CO2 concentrations the contrasting Ravelle factors between the subtropical and subpolar gyres, combined with the transport of surface waters from the subtropical to subpolar gyre, means that the subpolar CO2 uptake capacity is largely satisfied from its southern boundary rather than through air–sea CO2 flux. Our findings indicate that: (i we can explain the mechanisms of subpolar North Atlantic CO2 uptake variability across a broad range of Earth System Models, (ii a focus on understanding the mechanisms behind contemporary variability may not directly tell us about how the sink will change in the future, (iii to identify long-term change in the North Atlantic CO2 sink we should focus observational resources on monitoring subtropical as well as the subpolar seawater CO2, (iv recent observations of a weakening subpolar North Atlantic CO2 sink suggests that the sink strength is already in long-term decline.

  12. Effect of elevated CO2 concentration on photosynthetic characteristics of hyperaccumulator Sedum alfredii under cadmium stress

    Institute of Scientific and Technical Information of China (English)

    Tingqiang Li; Qi Tao; Zhenzhen Di; Fan Lu; Xiaoe Yang

    2015-01-01

    The combined effects of elevated CO2 and cadmi-um (Cd) on photosynthetic rate, chlorophyl fluorescence and Cd accumulation in hyperaccumulator Sedum alfredi Hance were investigated to predict plant growth under Cd stress with rising atmospheric CO2 concentration. Both pot and hydroponic experiments were conducted and the plants were grown under ambient (350 mL L?1) or elevated (800 mL L?1) CO2. Elevated CO2 significantly (P<0.05) increased Pn (105%–149%), Pnmax (38.8%–63.0%) and AQY (20.0%–34.8%) of S. alfredii in al the Cd treatments, but reduced chlorophyl concentra-tion, dark respiration and photorespiration. After 10 days growth in medium with 50 mM Cd under elevated CO2, PSII activities were significantly enhanced (P<0.05) with Pm, Fv/Fm, F(II) and qP increased by 66.1%, 7.5%, 19.5% and 16.4%, respectively, as compared with ambient-grown plants. Total Cd uptake in shoot of S. alfredi grown under elevated CO2 was increased by 44.1%–48.5%, which was positively correlated with the increase in Pn. These results indicate that elevated CO2 promoted the growth of S. alfredi due to increased photosynthetic carbon uptake rate and photosynthetic light-use efficiency, and showed great potential to improve the phytoextraction of Cd by S. alfredi .

  13. Stomatal proxy record of CO2 concentrations from the last termination suggests an important role for CO2 at climate change transitions

    Science.gov (United States)

    Steinthorsdottir, Margret; Wohlfarth, Barbara; Kylander, Malin E.; Blaauw, Maarten; Reimer, Paula J.

    2013-05-01

    A new stomatal proxy-based record of CO2 concentrations ([CO2]), based on Betula nana (dwarf birch) leaves from the Hässeldala Port sedimentary sequence in south-eastern Sweden, is presented. The record is of high chronological resolution and spans most of Greenland Interstadial 1 (GI-1a to 1c, Allerød pollen zone), Greenland Stadial 1 (GS-1, Younger Dryas pollen zone) and the very beginning of the Holocene (Preboreal pollen zone). The record clearly demonstrates that i) [CO2] were significantly higher than usually reported for the Last Termination and ii) the overall pattern of CO2 evolution through the studied time period is fairly dynamic, with significant abrupt fluctuations in [CO2] when the climate moved from interstadial to stadial state and vice versa. A new loss-on-ignition chemical record (used here as a proxy for temperature) lends independent support to the Hässeldala Port [CO2] record. The large-amplitude fluctuations around the climate change transitions may indicate unstable climates and that “tipping-point” situations were involved in Last Termination climate evolution. The scenario presented here is in contrast to [CO2] records reconstructed from air bubbles trapped in ice, which indicate lower concentrations and a gradual, linear increase of [CO2] through time. The prevalent explanation for the main climate forcer during the Last Termination being ocean circulation patterns needs to re-examined, and a larger role for atmospheric [CO2] considered.

  14. Experimental versus modelled water use in mature Norway spruce (Picea abies exposed to elevated CO2

    Directory of Open Access Journals (Sweden)

    Sebastian eLeuzinger

    2012-10-01

    Full Text Available Rising levels of atmospheric CO2 have often been reported to reduce plant water use. Such behaviour is also predicted by standard equations relating photosynthesis, stomatal conductance, and atmospheric CO2 concentration, which form the core of global dynamic vegetation models (DGVMs. Here, we provide first results from a free air CO2 enrichment (FACE experiment with naturally growing, mature (35 m Picea abies (L. (Norway spruce and compare them to simulations by the DGVM LPJ-GUESS. We monitored sap flow, stem water deficit, stomatal conductance, leaf water potential and soil moisture in five 35-40 m tall CO2-treated (550 ppm trees over two seasons. Using LPJ-GUESS, we simulated this experiment using climate data from a nearby weather station. While the model predicted a stable reduction of transpiration of between 9 and 18 % (at concentrations of 550-700ppm atmospheric CO2, the combined evidence from various methods characterising water use in our experimental trees suggest no changes in response to future CO2 concentrations. The discrepancy between the modelled and the experimental results may be a scaling issue: while dynamic vegetation models correctly predict leaf-level responses, they may not sufficiently account for the processes involved at the canopy and ecosystem scale, which could mitigate the first-order stomatal response.

  15. Global Monthly CO2 Flux Inversion Based on Results of Terrestrial Ecosystem Modeling

    Science.gov (United States)

    Deng, F.; Chen, J.; Peters, W.; Krol, M.

    2008-12-01

    Most of our understanding of the sources and sinks of atmospheric CO2 has come from inverse studies of atmospheric CO2 concentration measurements. However, the number of currently available observation stations and our ability to simulate the diurnal planetary boundary layer evolution over continental regions essentially limit the number of regions that can be reliably inverted globally, especially over continental areas. In order to overcome these restrictions, a nested inverse modeling system was developed based on the Bayesian principle for estimating carbon fluxes of 30 regions in North America and 20 regions for the rest of the globe. Inverse modeling was conducted in monthly steps using CO2 concentration measurements of 5 years (2000 - 2005) with the following two models: (a) An atmospheric transport model (TM5) is used to generate the transport matrix where the diurnal variation n of atmospheric CO2 concentration is considered to enhance the use of the afternoon-hour average CO2 concentration measurements over the continental sites. (b) A process-based terrestrial ecosystem model (BEPS) is used to produce hourly step carbon fluxes, which could minimize the limitation due to our inability to solve the inverse problem in a high resolution, as the background of our inversion. We will present our recent results achieved through a combination of the bottom-up modeling with BEPS and the top-down modeling based on TM5 driven by offline meteorological fields generated by the European Centre for Medium Range Weather Forecast (ECMFW).

  16. Carbon assimilation in Eucalyptus urophylla grown under high atmospheric CO2 concentrations: A proteomics perspective.

    Science.gov (United States)

    Santos, Bruna Marques Dos; Balbuena, Tiago Santana

    2017-01-06

    Photosynthetic organisms may be drastically affected by the future climate projections of a considerable increase in CO2 concentrations. Growth under a high concentration of CO2 could stimulate carbon assimilation-especially in C3-type plants. We used a proteomics approach to test the hypothesis of an increase in the abundance of the enzymes involved in carbon assimilation in Eucalyptus urophylla plants grown under conditions of high atmospheric CO2. Our strategy allowed the profiling of all Calvin-Benson cycle enzymes and associated protein species. Among the 816 isolated proteins, those involved in carbon fixation were found to be the most abundant ones. An increase in the abundance of six key enzymes out of the eleven core enzymes involved in carbon fixation was detected in plants grown at a high CO2 concentration. Proteome changes were corroborated by the detection of a decrease in the stomatal aperture and in the vascular bundle area in Eucalyptus urophylla plantlets grown in an environment of high atmospheric CO2. Our proteomics approach indicates a positive metabolic response regarding carbon fixation in a CO2-enriched atmosphere. The slight but significant increase in the abundance of the Calvin enzymes suggests that stomatal closure did not prevent an increase in the carbon assimilation rates.

  17. Sensitive indicators of Stipa bungeana response to precipitation under ambient and elevated CO2 concentration

    Science.gov (United States)

    Shi, Yaohui; Zhou, Guangsheng; Jiang, Yanling; Wang, Hui; Xu, Zhenzhu

    2017-09-01

    Precipitation is a primary environmental factor in the semiarid grasslands of northern China. With increased concentrations of atmospheric greenhouse gases, precipitation regimes will change, and high-impact weather events may be more common. Currently, many ecophysiological indicators are known to reflect drought conditions, but these indicators vary greatly among species, and few studies focus on the applicability of these drought indicators under high CO2 conditions. In this study, five precipitation levels (- 30%, - 15%, control, + 15%, and + 30%) were used to simulate the effects of precipitation change on 18 ecophysiological characteristics in Stipa bungeana, including leaf area, plant height, leaf nitrogen (N), and chlorophyll content, among others. Two levels of CO2 concentration (ambient, 390 ppm; 550 ppm) were used to simulate the effects of elevated CO2 on these drought indicators. Using gray relational analysis and phenotypic plasticity analysis, we found that total leaf area or leaf number (morphology), leaf water potential or leaf water content (physiology), and aboveground biomass better reflected the water status of S. bungeana under ambient and elevated CO2 than the 13 other analyzed variables. The sensitivity of drought indicators changed under the elevated CO2 condition. By quantifying the relationship between precipitation and the five most sensitive indicators, we found that the thresholds of precipitation decreased under elevated CO2 concentration. These results will be useful for objective monitoring and assessment of the occurrence and development of drought events in S. bungeana grasslands.

  18. 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

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

    Science.gov (United States)

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

    2009-01-01

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

  20. Lethal and sub-lethal effects of elevated CO2 concentrations on marine benthic invertebrates and fish.

    Science.gov (United States)

    Lee, Changkeun; Hong, Seongjin; Kwon, Bong-Oh; Lee, Jung-Ho; Ryu, Jongseong; Park, Young-Gyu; Kang, Seong-Gil; Khim, Jong Seong

    2016-08-01

    Concern about leakage of carbon dioxide (CO2) from deep-sea storage in geological reservoirs is increasing because of its possible adverse effects on marine organisms locally or at nearby coastal areas both in sediment and water column. In the present study, we examined how elevated CO2 affects various intertidal epibenthic (benthic copepod), intertidal endobenthic (Manila clam and Venus clam), sub-tidal benthic (brittle starfish), and free-living (marine medaka) organisms in areas expected to be impacted by leakage. Acute lethal and sub-lethal effects were detected in the adult stage of all test organisms exposed to varying concentrations of CO2, due to the associated decline in pH (8.3 to 5.2) during 96-h exposure. However, intertidal organisms (such as benthic copepods and clams) showed remarkable resistance to elevated CO2, with the Venus clam being the most tolerant (LpH50 = 5.45). Sub-tidal species (such as brittle starfish [LpH50 = 6.16] and marine medaka [LpH50 = 5.91]) were more sensitive to elevated CO2 compared to intertidal species, possibly because they have fewer defensive capabilities. Of note, the exposure duration might regulate the degree of acute sub-lethal effects, as evidenced by the Venus clam, which showed a time-dependent effect to elevated CO2. Finally, copper was chosen as a model toxic element to find out the synergistic or antagonistic effects between ocean acidification and metal pollution. Combination of CO2 and Cu exposure enhances the adverse effects to organisms, generally supporting a synergistic effect scenario. Overall, the significant variation in the degree to which CO2 adversely affected organisms (viz., working range and strength) was clearly observed, supporting the general concept of species-dependent effects of elevated CO2.

  1. Conditional Methods in Modeling CO2 Capture from Coal Syngas

    Directory of Open Access Journals (Sweden)

    Dmitry N. Saulov

    2014-03-01

    Full Text Available Gasification of coal or biomass with in-situ CO2 capture is an emerging technology aiming to address the problem of climate change. Development of a CO2 sorbent with desirable properties and understanding the behavior of such a material in carbonation/calcination reactions is an important part of developing the technology. In this paper, we report experimental results describing the carbonation behavior of three synthetic CaO-based sorbents. We also present a physically-based model of the reactive transport processes in sorbent particles, which have complicated pore structures. This modeling is based on the conditional approach (i.e., conditional moment closure (CMC, which has proven to be successful in modeling reactive transport phenomena in porous media. The model predictions are in good agreement with the experimental data.

  2. Enhanced electrocatalytic CO2 reduction via field-induced reagent concentration

    Science.gov (United States)

    Liu, Min; Pang, Yuanjie; Zhang, Bo; de Luna, Phil; Voznyy, Oleksandr; Xu, Jixian; Zheng, Xueli; Dinh, Cao Thang; Fan, Fengjia; Cao, Changhong; de Arquer, F. Pelayo García; Safaei, Tina Saberi; Mepham, Adam; Klinkova, Anna; Kumacheva, Eugenia; Filleter, Tobin; Sinton, David; Kelley, Shana O.; Sargent, Edward H.

    2016-09-01

    Electrochemical reduction of carbon dioxide (CO2) to carbon monoxide (CO) is the first step in the synthesis of more complex carbon-based fuels and feedstocks using renewable electricity. Unfortunately, the reaction suffers from slow kinetics owing to the low local concentration of CO2 surrounding typical CO2 reduction reaction catalysts. Alkali metal cations are known to overcome this limitation through non-covalent interactions with adsorbed reagent species, but the effect is restricted by the solubility of relevant salts. Large applied electrode potentials can also enhance CO2 adsorption, but this comes at the cost of increased hydrogen (H2) evolution. Here we report that nanostructured electrodes produce, at low applied overpotentials, local high electric fields that concentrate electrolyte cations, which in turn leads to a high local concentration of CO2 close to the active CO2 reduction reaction surface. Simulations reveal tenfold higher electric fields associated with metallic nanometre-sized tips compared to quasi-planar electrode regions, and measurements using gold nanoneedles confirm a field-induced reagent concentration that enables the CO2 reduction reaction to proceed with a geometric current density for CO of 22 milliamperes per square centimetre at -0.35 volts (overpotential of 0.24 volts). This performance surpasses by an order of magnitude the performance of the best gold nanorods, nanoparticles and oxide-derived noble metal catalysts. Similarly designed palladium nanoneedle electrocatalysts produce formate with a Faradaic efficiency of more than 90 per cent and an unprecedented geometric current density for formate of 10 milliamperes per square centimetre at -0.2 volts, demonstrating the wider applicability of the field-induced reagent concentration concept.

  3. Enhanced electrocatalytic CO2 reduction via field-induced reagent concentration.

    Science.gov (United States)

    Liu, Min; Pang, Yuanjie; Zhang, Bo; De Luna, Phil; Voznyy, Oleksandr; Xu, Jixian; Zheng, Xueli; Dinh, Cao Thang; Fan, Fengjia; Cao, Changhong; de Arquer, F Pelayo García; Safaei, Tina Saberi; Mepham, Adam; Klinkova, Anna; Kumacheva, Eugenia; Filleter, Tobin; Sinton, David; Kelley, Shana O; Sargent, Edward H

    2016-09-15

    Electrochemical reduction of carbon dioxide (CO2) to carbon monoxide (CO) is the first step in the synthesis of more complex carbon-based fuels and feedstocks using renewable electricity. Unfortunately, the reaction suffers from slow kinetics owing to the low local concentration of CO2 surrounding typical CO2 reduction reaction catalysts. Alkali metal cations are known to overcome this limitation through non-covalent interactions with adsorbed reagent species, but the effect is restricted by the solubility of relevant salts. Large applied electrode potentials can also enhance CO2 adsorption, but this comes at the cost of increased hydrogen (H2) evolution. Here we report that nanostructured electrodes produce, at low applied overpotentials, local high electric fields that concentrate electrolyte cations, which in turn leads to a high local concentration of CO2 close to the active CO2 reduction reaction surface. Simulations reveal tenfold higher electric fields associated with metallic nanometre-sized tips compared to quasi-planar electrode regions, and measurements using gold nanoneedles confirm a field-induced reagent concentration that enables the CO2 reduction reaction to proceed with a geometric current density for CO of 22 milliamperes per square centimetre at -0.35 volts (overpotential of 0.24 volts). This performance surpasses by an order of magnitude the performance of the best gold nanorods, nanoparticles and oxide-derived noble metal catalysts. Similarly designed palladium nanoneedle electrocatalysts produce formate with a Faradaic efficiency of more than 90 per cent and an unprecedented geometric current density for formate of 10 milliamperes per square centimetre at -0.2 volts, demonstrating the wider applicability of the field-induced reagent concentration concept.

  4. Different responses of invasive and native species to elevated CO 2 concentration

    Science.gov (United States)

    Song, Liying; Wu, Jinrong; Li, Changhan; Li, Furong; Peng, Shaolin; Chen, Baoming

    2009-01-01

    Increasing atmospheric CO 2 concentration is regarded as an important factor facilitating invasion. However, the mechanisms by which invasive plants spread at the expense of existing native plants are poorly understood. In this study, three invasive species ( Mikania micrantha, Wedelia trilobata and Ipomoea cairica) and their indigenous co-occurring species or congeners ( Paederia scandens, Wedelia chinensis and Ipomoea pescaprae) in South China were exposed to elevated CO 2 concentration (700 μmol mol -1). The invasive species showed an average increase of 67.1% in photosynthetic rate, significantly different from the native species (24.8%). On average the increase of total biomass at elevated CO 2 was greater for invasive species (70.3%) than for the natives (30.5%). Elevated CO 2 also resulted in significant changes in biomass allocation and morphology of invasive M. micrantha and W. trilobata. These results indicate a substantial variation in response to elevated CO 2 between these invasive and native plant species, which might be a potential mechanism partially explaining the success of invasion with ongoing increase in atmospheric CO 2.

  5. Numerical and analogue modelling of the propagation and dissolution of CO2 into reservoir brines: implications for CO2 sequestration

    Science.gov (United States)

    Daniels, K.; Bickle, M.; Neufeld, J. A.; Waterton, P.; Kampman, N.; Maskell, A.; Chapman, H.

    2013-12-01

    The release of carbon dioxide (CO2) and other greenhouse gases into the atmosphere is recognised as the principal cause of the current changes observed in the Earth's climate. Carbon Capture and Storage (CCS) within reservoirs is seen as a solution to combat these changes through long-term and secure geological storage of CO2. The viability of long-term storage however, is reliant on an accurate knowledge of CO2 trapping mechanisms, as well as an understanding of the effect of the injected supercritical CO2 on the reservoir formations themselves. One prospective stable trapping mechanism is the dissolution of CO2 into ambient reservoir brine. Developing a greater understanding of the flow of CO2 through reservoir rocks and the associated reactions between the host rock formation and the fluid is therefore of great importance to understanding whether a CO2 storage site will succeed. This study examines the enhanced rates of dissolution found during injection into a layered, heterogeneous formation through analogue experiments and numerical modelling. The analogue experiments are designed to approximate an enhanced oil recovery (EOR) setting and show that during fluid propagation, pore-scale viscous fingers grow and retreat. This will provide an increased surface area between the flow and the ambient reservoir fluid which is likely to enhance the dissolution of CO2 in reservoir brines. The numerical simulations provide a useful comparison with the analogue experiments and give constraints on the timescales and magnitude of CO2 dissolution and the resultant fluid-mineral reactions in a heterogeneous reservoir. The study begins to address whether the dissolution of carbonate or silicate minerals can provide the CO2 with a leakage pathway through corroded caprocks and fault seals, or help with pathway sealing.

  6. MODELLING CO2 EMISSIONS IMPACTS ON CROATIAN POWER SYSTEM

    Directory of Open Access Journals (Sweden)

    Robert Pašičko

    2010-01-01

    Full Text Available Today's electrical energy landscape is characterized by new challenges such as deregulation, liberalization of energy markets, increased competition, growing demands on security of supply, price insecurities, and demand to cut CO2 emissions. All mentioned challenges are calling for consideration of various options (like nuclear, coal, gas or renewable scenarios and for better understanding of energy systems modelling in order to optimize proper energy mix. Existing models are not sufficient any more and planners will need to think differently in order to face these challenges. European emission trading scheme (EU ETS started in 2005 and it has great influence on power system short term and long term planning. Croatia is obliged to establish a national scheme for trading of greenhouse gas emission allowances from the year 2010, which will be focused on monitoring and reporting only until accession to EU when it will be linked with EU ETS. Thus, for Croatian power system it is very important to analyze possible impacts of CO2 emissions. Analysis presented in this paper was done by two different models: mathematical model, based on short run marginal costs (SRMC, relevant for fuel switch in existing power plant and merit order change and long run marginal costs (LRMC, relevant for new investment decisions; and electricity market simulation model PLEXOS, which was used for modelling Croatian power system during development of the Croatian energy strategy in 2008. Results of the analysis show important impacts that emission trading has on Croatian power system, such as influence of emission price rise on price of electricity and on emission quantity, and changes in power plants output that appear with emission price rise. Breakeven point after which gas power plant becomes more competitive than coal is 62 €/tCO2 for SRMC and 40 €/tCO2 for LRMC. With CO2 prices above 31 €/tCO2 wind is more competitive than gas or coal, which emphasizes

  7. Active measures for reducing the global climatic impacts of escalating CO 2 concentrations

    Science.gov (United States)

    Penner, S. S.; Schneider, A. M.; Kennedy, E. M.

    The buildup of CO 2 by fossil-fuel burning and associated climatic changes have become the subject of intensive investigations. Although the time scale on which significant climatic changes (e.g. mean temperature changes of several degrees, appreciable changes in global and regional rainfalls and winds, etc.) are expected to occur is long, it has been noted that the magnitude of the energy system is so vast that modifications in the primary resource mix should preferably be initiated within a decade or sooner. The notion that the most economical energy source will be replaced globally in response to longterm climate model predictions is probably false. Before policy matters of this type can be discussed reasonably, careful assessments must be made of alternative global measures that do not require curtailments of fossil-fuel applications. This study on active measures for reducing climate changes caused by escalating CO 2 concentrations deals with potentially important areas of research. We find: (a) reductions in the solar input to the Earth by reflecting sunlight directly are prohibitively costly; (b) desired changes in Earth albedo through judicious introduction of small particles can probably be accomplished at acceptable cost through the use of modified combustors on high-flying aircraft.

  8. Biases in atmospheric CO2 estimates from correlated meteorology modeling errors

    Science.gov (United States)

    Miller, S. M.; Hayek, M. N.; Andrews, A. E.; Fung, I.; Liu, J.

    2015-03-01

    Estimates of CO2 fluxes that are based on atmospheric measurements rely upon a meteorology model to simulate atmospheric transport. These models provide a quantitative link between the surface fluxes and CO2 measurements taken downwind. Errors in the meteorology can therefore cause errors in the estimated CO2 fluxes. Meteorology errors that correlate or covary across time and/or space are particularly worrisome; they can cause biases in modeled atmospheric CO2 that are easily confused with the CO2 signal from surface fluxes, and they are difficult to characterize. In this paper, we leverage an ensemble of global meteorology model outputs combined with a data assimilation system to estimate these biases in modeled atmospheric CO2. In one case study, we estimate the magnitude of month-long CO2 biases relative to CO2 boundary layer enhancements and quantify how that answer changes if we either include or remove error correlations or covariances. In a second case study, we investigate which meteorological conditions are associated with these CO2 biases. In the first case study, we estimate uncertainties of 0.5-7 ppm in monthly-averaged CO2 concentrations, depending upon location (95% confidence interval). These uncertainties correspond to 13-150% of the mean afternoon CO2 boundary layer enhancement at individual observation sites. When we remove error covariances, however, this range drops to 2-22%. Top-down studies that ignore these covariances could therefore underestimate the uncertainties and/or propagate transport errors into the flux estimate. In the second case study, we find that these month-long errors in atmospheric transport are anti-correlated with temperature and planetary boundary layer (PBL) height over terrestrial regions. In marine environments, by contrast, these errors are more strongly associated with weak zonal winds. Many errors, however, are not correlated with a single meteorological parameter, suggesting that a single meteorological proxy is

  9. Linking soil O2, CO2, and CH4 concentrations in a wetland soil

    DEFF Research Database (Denmark)

    Elberling, Bo; Jensen, Louise Askær; Jørgensen, Christian Juncher

    2011-01-01

    Oxygen (O2) availability and diffusivity in wetlands are controlling factors for the production and consumption of both carbon dioxide (CO2) and methane (CH4) in the subsoil and thereby potential emission of these greenhouse gases to the atmosphere. To examine the linkage between highresolution s...... plants tissue on soil gas dynamics and greenhouse gas emissions following marked changes in water level....... spatiotemporal trends in O2 availability and CH4/CO2 dynamics in situ, we compare high-resolution subsurface O2 concentrations, weekly measurements of subsurface CH4/CO2 concentrations and near continuous flux measurements of CO2 and CH4. Detailed 2-D distributions of O2 concentrations and depth-profiles of CO2...... and CH4 were measured in the laboratory during flooding of soil columns using a combination of planar O2 optodes and membrane inlet mass spectrometry. Microsensors were used to assess apparent diffusivity under both field and laboratory conditions. Gas concentration profiles were analyzed...

  10. Cyanobacterial carbon concentrating mechanisms facilitate sustained CO2 depletion in eutrophic lakes

    Directory of Open Access Journals (Sweden)

    A. M. Morales-Williams

    2017-06-01

    Full Text Available Phytoplankton blooms are increasing in frequency, intensity, and duration in aquatic ecosystems worldwide. In many eutrophic lakes, these high levels of primary productivity correspond to periods of CO2 depletion in surface waters. Cyanobacteria and other groups of phytoplankton have the ability to actively transport bicarbonate (HCO3− across their cell membrane when CO2 concentrations are limiting, possibly giving them a competitive advantage over algae not using carbon concentrating mechanisms (CCMs. To investigate whether CCMs can maintain phytoplankton bloom biomass under CO2 depletion, we measured the δ13C signatures of dissolved inorganic carbon (δ13CDIC and phytoplankton particulate organic carbon (δ13Cphyto in 16 mesotrophic to hypereutrophic lakes during the ice-free season of 2012. We used mass–balance relationships to determine the dominant inorganic carbon species used by phytoplankton under CO2 stress. We found a significant positive relationship between phytoplankton biomass and phytoplankton δ13C signatures as well as a significant nonlinear negative relationship between water column ρCO2 and isotopic composition of phytoplankton, indicating a shift from diffusive uptake to active uptake by phytoplankton of CO2 or HCO3− during blooms. Calculated photosynthetic fractionation factors indicated that this shift occurs specifically when surface water CO2 drops below atmospheric equilibrium. Our results indicate that active HCO3− uptake via CCMs may be an important mechanism in maintaining phytoplankton blooms when CO2 is depleted. Further increases in anthropogenic pressure, eutrophication, and cyanobacteria blooms are therefore expected to contribute to increased bicarbonate uptake to sustain primary production.

  11. Cyanobacterial carbon concentrating mechanisms facilitate sustained CO2 depletion in eutrophic lakes

    Science.gov (United States)

    Morales-Williams, Ana M.; Wanamaker, Alan D., Jr.; Downing, John A.

    2017-06-01

    Phytoplankton blooms are increasing in frequency, intensity, and duration in aquatic ecosystems worldwide. In many eutrophic lakes, these high levels of primary productivity correspond to periods of CO2 depletion in surface waters. Cyanobacteria and other groups of phytoplankton have the ability to actively transport bicarbonate (HCO3-) across their cell membrane when CO2 concentrations are limiting, possibly giving them a competitive advantage over algae not using carbon concentrating mechanisms (CCMs). To investigate whether CCMs can maintain phytoplankton bloom biomass under CO2 depletion, we measured the δ13C signatures of dissolved inorganic carbon (δ13CDIC) and phytoplankton particulate organic carbon (δ13Cphyto) in 16 mesotrophic to hypereutrophic lakes during the ice-free season of 2012. We used mass-balance relationships to determine the dominant inorganic carbon species used by phytoplankton under CO2 stress. We found a significant positive relationship between phytoplankton biomass and phytoplankton δ13C signatures as well as a significant nonlinear negative relationship between water column ρCO2 and isotopic composition of phytoplankton, indicating a shift from diffusive uptake to active uptake by phytoplankton of CO2 or HCO3- during blooms. Calculated photosynthetic fractionation factors indicated that this shift occurs specifically when surface water CO2 drops below atmospheric equilibrium. Our results indicate that active HCO3- uptake via CCMs may be an important mechanism in maintaining phytoplankton blooms when CO2 is depleted. Further increases in anthropogenic pressure, eutrophication, and cyanobacteria blooms are therefore expected to contribute to increased bicarbonate uptake to sustain primary production.

  12. CO2-3 concentration and pCO2 thresholds for calcification and dissolution on the Molokai reef flat, Hawaii

    Science.gov (United States)

    Yates, K. K.; Halley, R. B.

    2006-01-01

    The severity of the impact of elevated atmospheric pCO2 to coral reef ecosystems depends, in part, on how seawater pCO2 affects the balance between calcification and dissolution of carbonate sediments. Presently, there are insufficient published data that relate concentrations of pCO2 and CO32- to in situ rates of reef calcification in natural settings to accurately predict the impact of elevated atmospheric pCO2 on calcification and dissolution processes. Rates of net calcification and dissolution, CO32- concentrations, and pCO2 were measured, in situ, on patch reefs, bare sand, and coral rubble on the Molokai reef flat in Hawaii. Rates of calcification ranged from 0.003 to 0.23 g CaCO3 m-2 h-1 and dissolution ranged from -0.005 to -0.33 g CaCO3 m-2 h-1. Calcification and dissolution varied diurnally with net calcification primarily occurring during the day and net dissolution occurring at night. These data were used to calculate threshold values for pCO2 and CO32- at which rates of calcification and dissolution are equivalent. Results indicate that calcification and dissolution are linearly correlated with both CO32- and pCO2. Threshold pCO2 and CO32- values for individual substrate types showed considerable variation. The average pCO2 threshold value for all substrate types was 654±195 µatm and ranged from 467 to 1003 µatm. The average CO3-- threshold value was 152±24 µmol kg-1, ranging from 113 to 184 µmol kg-1. Ambient seawater measurements of pCO2 and CO32- indicate that CO32- and pCO2 threshold values for all substrate types were both exceeded, simultaneously, 13% of the time at present day atmospheric pCO2 concentrations. It is predicted that atmospheric pCO2 will exceed the average pCO2 threshold value for calcification and dissolution on the Molokai reef flat by the year 2100.

  13. CO2−3 concentration and pCO2 thresholds for calcification and dissolution on the Molokai reef flat, Hawaii

    Directory of Open Access Journals (Sweden)

    R. B. Halley

    2006-01-01

    Full Text Available The severity of the impact of elevated atmospheric pCO2 to coral reef ecosystems depends, in part, on how seawater pCO2 affects the balance between calcification and dissolution of carbonate sediments. Presently, there are insufficient published data that relate concentrations of pCO2 and CO32− to in situ rates of reef calcification in natural settings to accurately predict the impact of elevated atmospheric pCO2 on calcification and dissolution processes. Rates of net calcification and dissolution, CO32− concentrations, and pCO2 were measured, in situ, on patch reefs, bare sand, and coral rubble on the Molokai reef flat in Hawaii. Rates of calcification ranged from 0.003 to 0.23 g CaCO3 m−2 h−1 and dissolution ranged from −0.005 to −0.33 g CaCO3 m−2 h−1. Calcification and dissolution varied diurnally with net calcification primarily occurring during the day and net dissolution occurring at night. These data were used to calculate threshold values for pCO2 and CO32− at which rates of calcification and dissolution are equivalent. Results indicate that calcification and dissolution are linearly correlated with both CO32− and pCO2. Threshold pCO2 and CO32− values for individual substrate types showed considerable variation. The average pCO2 threshold value for all substrate types was 654±195 µatm and ranged from 467 to 1003 µatm. The average CO3−- threshold value was 152±24 µmol kg-1, ranging from 113 to 184 µmol kg−1. Ambient seawater measurements of pCO2 and CO32− indicate that CO32− and pCO2 threshold values for all substrate types were both exceeded, simultaneously, 13% of the time at present day atmospheric pCO2 concentrations. It is predicted that atmospheric pCO2 will exceed the average pCO2 threshold value for calcification and dissolution on the Molokai reef flat by the year 2100.

  14. Simulation and modeling CO2 absorption in biogas with DEA promoted K2CO3 solution in packed column

    Science.gov (United States)

    Nurkhamidah, Siti; Altway, Ali; Airlangga, Bramantyo; Emilia, Dwi Putri

    2017-05-01

    Absorption of carbon dioxide (CO2) using potassium carbonate (K2CO3) is one of biogas purification method. However, K2CO3 have slow mass transfer in liquid phase. So it is necessary to eliminate the disadvantage of CO2 absorption using K2CO3 by adding promotor (activator). Diethanol amine (DEA) is one of promotor which can increase its reaction rate. Simulation and modeling research of the CO2 absorption from biogas with DEA promoted K2CO3 solution has not been conducted. Thus, the main goal of this research is create model and simulation for the CO2 absorption from biogas with DEA promoted K2CO3 solution, then observe the influence of promoter concentration. DEA concentration varies between 1-5 %wt. From the simulation, we concluded that the CO2 removal rise with the increasing of promoter concentration. The highest CO2 removal is 54.5318 % at 5 % wt DEA concentration.

  15. A Microscale Model for Combined CO2 Diffusion and Photosynthesis in Leaves

    Science.gov (United States)

    Ho, Quang Tri; Verboven, Pieter; Yin, Xinyou; Struik, Paul C.; Nicolaï, Bart M.

    2012-01-01

    Transport of CO2 in leaves was investigated by combining a 2-D, microscale CO2 transport model with photosynthesis kinetics in wheat (Triticum aestivum L.) leaves. The biophysical microscale model for gas exchange featured an accurate geometric representation of the actual 2-D leaf tissue microstructure and accounted for diffusive mass exchange of CO2. The resulting gas transport equations were coupled to the biochemical Farquhar-von Caemmerer-Berry model for photosynthesis. The combined model was evaluated using gas exchange and chlorophyll fluorescence measurements on wheat leaves. In general a good agreement between model predictions and measurements was obtained, but a discrepancy was observed for the mesophyll conductance at high CO2 levels and low irradiance levels. This may indicate that some physiological processes related to photosynthesis are not incorporated in the model. The model provided detailed insight into the mechanisms of gas exchange and the effects of changes in ambient CO2 concentration or photon flux density on stomatal and mesophyll conductance. It represents an important step forward to study CO2 diffusion coupled to photosynthesis at the leaf tissue level, taking into account the leaf's actual microstructure. PMID:23144870

  16. Elevated CO2 concentration increase the mobility of Cd and Zn in the rhizosphere of hyperaccumulator Sedum alfredii.

    Science.gov (United States)

    Li, Tingqiang; Tao, Qi; Liang, Chengfeng; Yang, Xiaoe

    2014-05-01

    The effects of elevated CO2 on metal species and mobility in the rhizosphere of hyperaccumulator are not well understood. We report an experiment designed to compare the effects of elevated CO2 on Cd/Zn speciation and mobility in the rhizosphere of hyperaccumulating ecotype (HE) and a non-hyperaccumulating ecotype (NHE) of Sedum alfredii grown under ambient (350 μl l(-1)) or elevated (800 μl l(-1)) CO2 conditions. No difference in solution pH of NHE was observed between ambient and elevated CO2 treatments. For HE, however, elevated CO2 reduced soil solution pH by 0.22 unit, as compared to ambient CO2 conditions. Elevated CO2 increased dissolved organic carbon (DOC) and organic acid levels in soil solution of both ecotypes, but the increase in HE solution was much greater than in NHE solution. After the growth of HE, the concentrations of Cd and Zn in soil solution decreased significantly regardless of CO2 level. The visual MINTEQ speciation model predicted that Cd/Zn-DOM complexes were the dominant species in soil solutions, followed by free Cd(2+) and Zn(2+) species for both ecotypes. However, Cd/Zn-DOM complexes fraction in soil solution of HE was increased by the elevated CO2 treatment (by 8.01 % for Cd and 8.47 % for Zn, respectively). Resin equilibration experiment results indicated that DOM derived from the rhizosphere of HE under elevated CO2 (HE-DOM-E) (90 % for Cd and 73 % for Zn, respectively) showed greater ability to form complexes with Cd and Zn than those under ambient CO2 (HE-DOM-A) (82 % for Cd and 61 % for Zn, respectively) in the undiluted sample. HE-DOM-E showed greater ability to extract Cd and Zn from soil than HE-DOM-A. It was concluded that elevated CO2 could increase the mobility of Cd and Zn due to the enhanced formation of DOM-metal complexes in the rhizosphere of HE S. alfredii.

  17. 大气CO_2变化与气候%Variations of Atmospheric CO2 Concentration and Global Climate

    Institute of Scientific and Technical Information of China (English)

    刘植; 刘秀铭; 李平原; 吕镔; 陈家胜; 陈渠; 郭雪莲

    2012-01-01

    在地质历史时期,地球的气候不断在变化,全球大气CO2浓度也在变化,二者之间是否存在一种响应—反馈作用,目前存在争议较大.本研究从地质时间尺度、千年以来和现代气候变化3个角度进行介绍,认为全球气候变化是多重时间尺度变化规律的叠加,从长时间尺度来看,全球平均温度和大气CO2水平均表现出整体降低的趋势.地质历史时期存在多次大气CO2浓度升高的时期,有时甚至可达现在大气CO2水平的十几倍.气候变化与大气CO2的关系非常复杂,高CO2时期并不全部对应于高温时期.千年以来的气候变化在全球各大洲均有温暖时期的出现,并且很多地方的重建结果表明中世纪暖期的全球平均温度要比现代的全球平均温度还高.但这一区间的温度变化和大气CO2水平在1850年之前没有明显的相关性.近百年的气候观测资料表明全球平均温度上升了0.74℃,但对于这种上升的理解目前还存在较大争议.是否确实是由于人类活动(主要是工业革命以来)导致了全球CO2水平增高,进而导致全球变暖,需要更多的证据来验证.%In geological history, the earth's climate changed regularly and constantly and the concen- tration of atmospheric CO2 ~dso changed over time, so scientists argue whether there were response- feedback effects between them. In this paper, global climate change is assumed to be a multiple time- scale change, various time scales including long time orbital-scale, thousand year time-scale and nearly hundred years are introduced and analyzed. For long time-scale, both average global tempera- ture and atmospheric CO2 level present a reduction trend. Many times during geological history, at- mospheric CO2 level rose, sometimes to as high as ten times of the present level. It is found that the high C02 level period was not always corresponding to the high temperature period. For thousand year time-scale, it is

  18. Effect of CO2 Concentration on Nitrogen Metabolism of Winter Wheat

    Institute of Scientific and Technical Information of China (English)

    MEN Zhong-hua; LI Sheng-xiu

    2005-01-01

    Hoagland's solution was used as water culture medium to study the effect of CO2 concentration on nitrate metabolism of wheat under natural light and light-shaded conditions. NO3-N, NH4+-N, nitrate reductase activity, total uptake N by wheat plants during solution cultural period and total N in plants were determined for comprehensive evaluation of the effect.Results showed that under both natural light and light-shaded conditions, addition of CO2 increased NO3-N uptake and its assimilative capabilities by plants. However, there were some difference between shoots and roots. With increase of CO2concentration, the concentration of NO3-N and NH4+-N as well as nitrate reductase activity were all decreased for shoots while the difference was not so distinct in roots, and the nitrate reductase activity was not decreased, but increased. Since NO3-N uptake by plants from the solution and the total N in plants were much higher by CO2 addition, it may be concluded that addition of CO2 has resulted in rise of nitrate absorption, assimilation and metabolism of wheat.

  19. Effects of immersion in water containing high concentrations of CO2 (CO2-water) at thermoneutral on thermoregulation and heart rate variability in humans

    Science.gov (United States)

    Sato, Maki; Kanikowska, Dominika; Iwase, Satoshi; Nishimura, Naoki; Shimizu, Yuuki; de Chantemele, Eric Belin; Matsumoto, Takaaki; Inukai, Yoko; Taniguchi, Yumiko; Ogata, Akihiro; Sugenoya, Junichi

    2009-01-01

    Immersion in high concentrations of CO2 dissolved in freshwater (CO2-water) might induce peripheral vasodilatation in humans. In this study, we investigated whether such immersion could affect the autonomic nervous system in humans using spectral analysis of heart rate variability. Ten healthy men participated in this study. Tympanic temperature, cutaneous blood flow and electrocardiogram (ECG) were measured continuously during 20 min of immersion in CO2-water. The ECG was analyzed by spectral analysis of R-R intervals using the maximal entropy method. The decrease in tympanic temperature was significantly greater in CO2-water immersion than in freshwater immersion. Cutaneous blood flow at the immersed site was significantly increased with CO2-water immersion compared to freshwater. The high frequency component (HF: 0.15-0.40 Hz) was significantly higher in CO2-water immersion than in freshwater immersion, but the low frequency (LF: 0.04-0.15 Hz) /high frequency ratio (LF/HF ratio) was significantly lower in CO2-water immersion than in freshwater immersion. The present study contributes evidence supporting the hypothesis that CO2-water immersion activates parasympathetic nerve activity in humans.

  20. Assumption Centred Modelling of Ecosystem Responses to CO2 at Six US Atmospheric CO2 Enrichment Experiments.

    Science.gov (United States)

    Walker, A. P.; De Kauwe, M. G.; Medlyn, B. E.; Zaehle, S.; Luus, K. A.; Ryan, E.; Xia, J.; Norby, R. J.

    2015-12-01

    Plant photosynthetic rates increase and stomatal apertures decrease in response to elevated atmospheric CO[2] (eCO2), increasing both plant carbon (C) availability and water use efficiency. These physiological responses to eCO2 are well characterised and understood, however the ecological effects of these responses as they cascade through a suite of plant and ecosystem processes are complex and subject to multiple interactions and feedbacks. Therefore the response of the terrestrial carbon sink to increasing atmospheric CO[2] remains the largest uncertainty in global C cycle modelling to date, and is a huge contributor to uncertainty in climate change projections. Phase 2 of the FACE Model-Data Synthesis (FACE-MDS) project synthesises ecosystem observations from five long-term Free-Air CO[2] Enrichment (FACE) experiments and one open top chamber (OTC) experiment to evaluate the assumptions of a suite of terrestrial ecosystem models. The experiments are: The evergreen needleleaf Duke Forest FACE (NC), the deciduous broadleaf Oak Ridge FACE (TN), the prairie heating and FACE (WY), and the Nevada desert FACE, and the evergreen scrub oak OTC (FL). An assumption centered approach is being used to analyse: the interaction between eCO2 and water limitation on plant productivity; the interaction between eCO2 and temperature on plant productivity; whether increased rates of soil decomposition observed in many eCO2 experiments can account for model deficiencies in N uptake shown during Phase 1 of the FACE-MDS; and tracing carbon through the ecosystem to identify the exact cause of changes in ecosystem C storage.

  1. Dynamics of dimethylsulphoniopropionate and dimethylsulphide under different CO2 concentrations during a mesocosm experiment

    Directory of Open Access Journals (Sweden)

    C. LeQuéré

    2007-10-01

    Full Text Available We investigated the potential impact of seawater acidification on the concentrations of dimethylsulfide (DMS and dimethylsulfoniopropionate (DMSP, and the activity of the enzyme DMSP-lyase during a pelagic ecosystem CO2 enrichment experiment (PeECE III in spring 2005. Natural phytoplankton blooms were studied for 24 days under present, double and triple partial pressures of CO2 (pCO2; pH=8.3, 8.0, 7.8 in triplicate 25 m³ enclosures. The results indicate similar DMSP concentrations and DMSP-lyase activity patterns for all treatments. Hence, DMSP and DLA do not seem to have been affected by the CO2 treatment. In contrast, DMS concentrations showed small but statistically significant differences in the temporal development of the "present" versus the high CO2 treatments. The "present" enclosures had higher DMS concentrations during the first 10 days, after which the levels decreased earlier and more rapidly than in the other treatments. Integrated over the whole study period, DMS concentrations were not significantly different from those of the double and triple pCO2 treatments. Pigment and flow-cytometric data indicate that phytoplanktonic populations were generally similar between the treatments, suggesting a certain resilience of the marine ecosystem under study to the induced pH changes, which is reflected in DMSP and DLA. However, there were significant differences in bacterial community structure and the abundance of one group of viruses. The amount of DMS accumulated per total DMSP or chlorophyll-a differed significantly between the present and future scenarios, suggesting that the pathways for DMS production or bacterial DMS consumption were affected by seawater pH.

  2. Can rising CO2 concentrations in the atmosphere mitigate the impact of drought years on tree growth?

    Science.gov (United States)

    Achim, Alexis; Plumpton, Heather; Auty, David; Ogee, Jerome; MacCarthy, Heather; Bert, Didier; Domec, Jean-Christophe; Oren, Ram; Wingate, Lisa

    2015-04-01

    Atmospheric CO2 concentrations and nitrogen deposition rates have increased substantially over the last century and are expected to continue unabated. As a result, terrestrial ecosystems will experience warmer temperatures and some may even experience droughts of a more intense and frequent nature that could lead to widespread forest mortality. Thus there is mounting pressure to understand and predict how forest growth will be affected by such environmental interactions in the future. In this study we used annual tree growth data from the Duke Free Air CO2 Enrichment (FACE) experiment to determine the effects of elevated atmospheric CO2 concentration (+200 ppm) and Nitrogen fertilisation (11.2 g of N m-2 yr-1) on the stem biomass increments of mature loblolly pine (Pinus taeda L.) trees from 1996 to 2010. A non-linear mixed-effects model was developed to provide estimates of annual ring specific gravity in all trees using cambial age and annual ring width as explanatory variables. Elevated CO2 did not have a significant effect on annual ring specific gravity, but N fertilisation caused a slight decrease of approximately 2% compared to the non-fertilised in both the ambient and CO2-elevated plots. When basal area increments were multiplied by wood specific gravity predictions to provide estimates of stem biomass, there was a 40% increase in the CO2-elevated plots compared to those in ambient conditions. This difference remained relatively stable until the application of the fertilisation treatment, which caused a further increase in biomass increments that peaked after three years. Unexpectedly the magnitude of this second response was similar in the CO2-elevated and ambient plots (about 25% in each after 3 years), suggesting that there was no interaction between the concentration of CO2 and the availability of soil N on biomass increments. Importantly, during drier years when annual precipitation was less than 1000 mm we observed a significant decrease in annual

  3. Toward verifying fossil fuel CO2 emissions with the CMAQ model: motivation, model description and initial simulation.

    Science.gov (United States)

    Liu, Zhen; Bambha, Ray P; Pinto, Joseph P; Zeng, Tao; Boylan, Jim; Huang, Maoyi; Lei, Huimin; Zhao, Chun; Liu, Shishi; Mao, Jiafu; Schwalm, Christopher R; Shi, Xiaoying; Wei, Yaxing; Michelsen, Hope A

    2014-04-01

    Motivated by the question of whether and how a state-of-the-art regional chemical transport model (CTM) can facilitate characterization of CO2 spatiotemporal variability and verify CO2 fossil-fuel emissions, we for the first time applied the Community Multiscale Air Quality (CMAQ) model to simulate CO2. This paper presents methods, input data, and initial results for CO2 simulation using CMAQ over the contiguous United States in October 2007. Modeling experiments have been performed to understand the roles of fossil-fuel emissions, biosphere-atmosphere exchange, and meteorology in regulating the spatial distribution of CO2 near the surface over the contiguous United States. Three sets of net ecosystem exchange (NEE) fluxes were used as input to assess the impact of uncertainty of NEE on CO2 concentrations simulated by CMAQ. Observational data from six tall tower sites across the country were used to evaluate model performance. In particular, at the Boulder Atmospheric Observatory (BAO), a tall tower site that receives urban emissions from Denver CO, the CMAQ model using hourly varying, high-resolution CO2 fossil-fuel emissions from the Vulcan inventory and Carbon Tracker optimized NEE reproduced the observed diurnal profile of CO2 reasonably well but with a low bias in the early morning. The spatial distribution of CO2 was found to correlate with NO(x), SO2, and CO, because of their similar fossil-fuel emission sources and common transport processes. These initial results from CMAQ demonstrate the potential of using a regional CTM to help interpret CO2 observations and understand CO2 variability in space and time. The ability to simulate a full suite of air pollutants in CMAQ will also facilitate investigations of their use as tracers for CO2 source attribution. This work serves as a proof of concept and the foundation for more comprehensive examinations of CO2 spatiotemporal variability and various uncertainties in the future. Atmospheric CO2 has long been modeled

  4. Thermodynamic Data for Geochemical Modeling of Carbonate Reactions Associated with CO2 Sequestration – Literature Review

    Energy Technology Data Exchange (ETDEWEB)

    Krupka, Kenneth M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Cantrell, Kirk J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); McGrail, B. Peter [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2010-09-01

    Permanent storage of anthropogenic CO2 in deep geologic formations is being considered as a means to reduce the concentration of atmospheric CO2 and thus its contribution to global climate change. To ensure safe and effective geologic sequestration, numerous studies have been completed of the extent to which the CO2 migrates within geologic formations and what physical and geochemical changes occur in these formations when CO2 is injected. Sophisticated, computerized reservoir simulations are used as part of field site and laboratory CO2 sequestration studies. These simulations use coupled multiphase flow-reactive chemical transport models and/or standalone (i.e., no coupled fluid transport) geochemical models to calculate gas solubility, aqueous complexation, reduction/oxidation (redox), and/or mineral solubility reactions related to CO2 injection and sequestration. Thermodynamic data are critical inputs to modeling geochemical processes. The adequacy of thermodynamic data for carbonate compounds has been identified as an important data requirement for the successful application of these geochemical reaction models to CO2 sequestration. A review of thermodynamic data for CO2 gas and carbonate aqueous species and minerals present in published data compilations and databases used in geochemical reaction models was therefore completed. Published studies that describe mineralogical analyses from CO2 sequestration field and natural analogue sites and laboratory studies were also reviewed to identify specific carbonate minerals that are important to CO2 sequestration reactions and therefore require thermodynamic data. The results of the literature review indicated that an extensive thermodynamic database exists for CO2 and CH4 gases, carbonate aqueous species, and carbonate minerals. Values of ΔfG298° and/or log Kr,298° are available for essentially all of these compounds. However, log Kr,T° or heat capacity values at temperatures above 298 K exist for less than

  5. Photosynthesis of Populus euphratica and its response to elevated CO2 concentration in an arid environment

    Institute of Scientific and Technical Information of China (English)

    Honghua Zhou; Yaning Chen; Weihong Li; Yapeng Chen; Lixin Fu

    2009-01-01

    The photosynthetic characterization of Populus euphratica and its response to the elevated carbon dioxide concentration ([CO2]) were analyzed based on its net photosynthetic rate (Pn),stomatal conductance (gs),intercellular CO2 concentration (Ci),transpiration rate (Tr),and water use efficiency (WUE) at different groundwater depths measured by a portable gas exchange system (LI-6400) in the lower reaches of the Tarim River.The results showed that the elevation of [CO2]decreased the gs,and increased the Pn,Ci and WUE of P.euphratica.However,the effects of the elevated [CO2]on gs,Pn,Ci and WUE varied considerably with groundwater depth.The response of photosynthesis to rising [CO2]was stronger at the greater groundwater depth (more than 6 m) than that at the shallower groundwater depth (less than 6 m).The critical groundwater depth required to maintain the normal survival of P.euphratica was less than 6 m.When the groundwater depth increased to more than 6 m,P.euphratica encountered moderate water stress,and the plant suffered severe water stress when the groundwater depth increased to more than 7 m.

  6. Decarbonization and the time-delay between peak CO2 emissions and concentrations

    CERN Document Server

    Seshadri, Ashwin K

    2015-01-01

    Carbon-dioxide (CO2) is the main contributor to anthropogenic global warming, and the timing of its peak concentration in the atmosphere is likely to govern the timing of maximum radiative forcing. While dynamics of atmospheric CO2 is governed by multiple time-constants, we idealize this by a single time-constant to consider some of the factors describing the time-delay between peaks in CO2 emissions and concentrations. This time-delay can be understood as the time required to bring CO2 emissions down from its peak to a small value, and is governed by the rate of decarbonizaton of economic activity. This decarbonization rate affects how rapidly emissions decline after having achieved their peak, and a rapid decline in emissions is essential for limiting peak radiative forcing. Long-term mitigation goals for CO2 should therefore consider not only the timing of peak emissions, but also the rate of decarbonization. We discuss implications for mitigation of the fact that the emissions peak corresponds to small bu...

  7. Seasonally varying contributions to urban CO2 in the Chicago, Illinois, USA region: Insights from a high-resolution CO2 concentration and δ13C record

    Directory of Open Access Journals (Sweden)

    Joel Moore

    2015-06-01

    Full Text Available Abstract Understanding urban carbon cycling is essential given that cities sustain 54% of the global population and contribute 70% of anthropogenic CO2 emissions. When combined with CO2 concentration measurements ([CO2], stable carbon isotope analyses (δ13C can differentiate sources of CO2, including ecosystem respiration and combustion of fossil fuels, such as petroleum and natural gas. In this study, we used a wavelength scanned-cavity ringdown spectrometer to collect ∼2x106 paired measurements for [CO2] and δ13C values in Evanston, IL for August 2011 through February 2012. Evanston is located immediately north of Chicago, IL, the third largest city in the United States. The measurements represent one of the longest records of urban [CO2] and δ13C values thus far reported. We also compiled local meteorological information, as well as complementary [CO2] and δ13C data for background sites in Park Falls, WI and Mauna Loa, HI. We use the dataset to examine how ecosystem processes, fossil fuel usage, wind speed, and wind direction control local atmospheric [CO2] and δ13C in a midcontinent urban setting on a seasonal to daily basis. On average, [CO2] and δ13C values in Evanston were 16–23 ppm higher and 0.97–1.13‰ lower than the background sites. While seasonal [CO2] and δ13C values generally followed broader northern hemisphere trends, the difference between Evanston and the background sites was larger in winter versus summer. Mixing calculations suggest that ecosystem respiration and petroleum combustion equally contributed CO2 in excess of background during the summer and that natural gas combustion contributed 80%–94% of the excess CO2 in winter. Wind speed and direction strongly influenced [CO2] and δ13C values on an hourly time scale. The highest [CO2] and lowest δ13C values occurred at wind speeds <3 m s−1 and when winds blew from the northwest, west, and south over densely populated neighborhoods.

  8. Simplified Predictive Models for CO2 Sequestration Performance Assessment

    Science.gov (United States)

    Mishra, Srikanta; RaviGanesh, Priya; Schuetter, Jared; Mooney, Douglas; He, Jincong; Durlofsky, Louis

    2014-05-01

    We present results from an ongoing research project that seeks to develop and validate a portfolio of simplified modeling approaches that will enable rapid feasibility and risk assessment for CO2 sequestration in deep saline formation. The overall research goal is to provide tools for predicting: (a) injection well and formation pressure buildup, and (b) lateral and vertical CO2 plume migration. Simplified modeling approaches that are being developed in this research fall under three categories: (1) Simplified physics-based modeling (SPM), where only the most relevant physical processes are modeled, (2) Statistical-learning based modeling (SLM), where the simulator is replaced with a "response surface", and (3) Reduced-order method based modeling (RMM), where mathematical approximations reduce the computational burden. The system of interest is a single vertical well injecting supercritical CO2 into a 2-D layered reservoir-caprock system with variable layer permeabilities. In the first category (SPM), we use a set of well-designed full-physics compositional simulations to understand key processes and parameters affecting pressure propagation and buoyant plume migration. Based on these simulations, we have developed correlations for dimensionless injectivity as a function of the slope of fractional-flow curve, variance of layer permeability values, and the nature of vertical permeability arrangement. The same variables, along with a modified gravity number, can be used to develop a correlation for the total storage efficiency within the CO2 plume footprint. In the second category (SLM), we develop statistical "proxy models" using the simulation domain described previously with two different approaches: (a) classical Box-Behnken experimental design with a quadratic response surface fit, and (b) maximin Latin Hypercube sampling (LHS) based design with a Kriging metamodel fit using a quadratic trend and Gaussian correlation structure. For roughly the same number of

  9. 土壤CO2浓度的动态观测、模拟和应用%Dynamic observation, simulation and application of soil CO2 concentration: A review

    Institute of Scientific and Technical Information of China (English)

    盛浩; 罗莎; 周萍; 李腾毅; 王娟; 李洁

    2012-01-01

    Soil CO2 concentration is the consequences of biological activities in above- and below-ground , and its fluctuation may significantly affect the future atmospheric CO2 concentration and the projected climate change. This paper reviewed the methodologies for measuring the soil CO2 concentration in situ as well as their advantages and disadvantages, analyzed the variation patterns and controlling factors of soil CO2 concentration across the temporal ( diurnal, several days, seasonal and inter-annual) and spatial ( soil profile, site and landscape) scales, introduced the primary empirical and mechanical models for estimating and predicting soil CO2 concentration, and summarized the applications and constraints of soil CO2 concentration gradient in determining soil respiration. Four research priorities were proposed, i. e. , to develop new techniques for collecting and determining the soil CO2 in severe soil conditions (e. g. , flooding, lithoso and others) , to approach the responses of soil CO2 concentration to weather change and related regulation mechanisms, to strengthen the researches on the spatial heterogeneity of soil CO2 concentration, and to expand the applications of soil CO2 concentration gradient in the measurement of tropical-subtropical soil respiration.%土壤CO2浓度不仅是地上、地下生物活动的反映,其变化对未来大气CO2浓度和气候变化也有重要影响.本文综述了国内外土壤CO2浓度的原位测定方法及其优缺点,分析了不同时(昼夜、几天、季节、年际)空(剖面、立地、景观)尺度上土壤CO2浓度的变化规律和影响因素,概括了现有土壤CO2浓度的模拟模型和发展态势,并总结了土壤CO2浓度梯度法在土壤呼吸研究中的应用和限制因素.最后展望了未来有待研究的4个领域:1)研发适于恶劣土壤环境(如淹水、石质土)的土壤CO2气体采集、测定技术;2)探讨土壤CO2浓度对天气变化的响应及其调控机理;3)加强土壤CO

  10. Spatiotemporal variability and drivers of pCO2 and air–sea CO2 fluxes in the California Current System: an eddy-resolving modeling study

    Directory of Open Access Journals (Sweden)

    G. Turi

    2013-08-01

    Full Text Available We quantify the CO2 source/sink nature of the California Current System (CalCS and determine the drivers and processes behind the mean and spatiotemporal variability of the partial pressure of CO2 (pCO2 in the surface ocean. To this end, we analyze eddy-resolving, climatological simulations of a coupled physical-ecosystem-biogeochemical ocean model on the basis of the Regional Oceanic Modeling System (ROMS. The model-simulated pCO2 agrees very well with in situ observations over the entire domain with virtually no bias, but the model overestimates pCO2 in the nearshore 100 km, and underestimates the observed temporal variability. In the annual mean, the entire CalCS within 800 km of the coast and from ~ 33° N to 46° N is essentially neutral with regard to atmospheric CO2. The model simulates an integrated uptake flux of −0.9 Tg C yr–1, corresponding to a very small average flux density of −0.05 mol C m–2 yr–1, with an uncertainty of the order of ±0.20 mol C m–2 yr–1. This near zero flux is a consequence of an almost complete regional compensation between the strong outgassing in the nearshore region (first 100 km, with flux densities of more than 3 mol C m–2 yr–1 and a weaker, but more widespread uptake flux in the offshore region with an average flux density of −0.17 mol C m–2 yr–1. This pattern is primarily a result of the interaction between upwelling in the nearshore that brings waters with high concentrations of dissolved inorganic carbon (DIC to the surface, and an intense biological drawdown of this DIC, driven by the nutrients that are upwelled together with the DIC. The biological drawdown occurs too slowly to prevent the escape of a substantial amount of CO2 into the atmosphere, but this is compensated by the biological generation of undersaturated conditions offshore of 100 km, permitting the CalCS to take up most of the escaped CO2. Thus, the biological pump over the entire CalCS is essentially 100

  11. Airborne Measurements of CO2 Column Concentration and Range Using a Pulsed Direct-Detection IPDA Lidar

    Directory of Open Access Journals (Sweden)

    James B. Abshire

    2013-12-01

    Full Text Available We have previously demonstrated a pulsed direct detection IPDA lidar to measure range and the column concentration of atmospheric CO2. The lidar measures the atmospheric backscatter profiles and samples the shape of the 1,572.33 nm CO2 absorption line. We participated in the ASCENDS science flights on the NASA DC-8 aircraft during August 2011 and report here lidar measurements made on four flights over a variety of surface and cloud conditions near the US. These included over a stratus cloud deck over the Pacific Ocean, to a dry lake bed surrounded by mountains in Nevada, to a desert area with a coal-fired power plant, and from the Rocky Mountains to Iowa, with segments with both cumulus and cirrus clouds. Most flights were to altitudes >12 km and had 5–6 altitude steps. Analyses show the retrievals of lidar range, CO2 column absorption, and CO2 mixing ratio worked well when measuring over topography with rapidly changing height and reflectivity, through thin clouds, between cumulus clouds, and to stratus cloud tops. The retrievals shows the decrease in column CO2 due to growing vegetation when flying over Iowa cropland as well as a sudden increase in CO2 concentration near a coal-fired power plant. For regions where the CO2 concentration was relatively constant, the measured CO2 absorption lineshape (averaged for 50 s matched the predicted shapes to better than 1% RMS error. For 10 s averaging, the scatter in the retrievals was typically 2–3 ppm and was limited by the received signal photon count. Retrievals were made using atmospheric parameters from both an atmospheric model and from in situ temperature and pressure from the aircraft. The retrievals had no free parameters and did not use empirical adjustments, and >70% of the measurements passed screening and were used in analysis. The differences between the lidar-measured retrievals and in situ measured average CO2 column concentrations were <1.4 ppm for flight measurement altitudes >6

  12. 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

  13. INTERSPECIFIC VARIATION IN THE GROWTH-RESPONSE OF PLANTS TO AN ELEVATED AMBIENT CO2 CONCENTRATION

    NARCIS (Netherlands)

    POORTER, H

    1993-01-01

    The effect of a doubling in the atmospheric CO2 concentration on the growth of vegetative whole plants was investigated. In a compilation of literature sources, the growth stimulation of 156 plant species was found to be on average 37%. This enhancement is small compared to what could be expected on

  14. The Impact of Atmosferic Concentration CO2 on the Development of the Stomata

    OpenAIRE

    Fiala, Václav

    2015-01-01

    Stomatal density (SD) and stomatal index (SI) are the parameters that are used to reconstruct the paleoclimate. Understanding the environmental factors that affect these values can make the predictive value of the stomata analysis more accurate. In this thesis, I tested the effect of different soil moisture and CO2 concentration in the stomata.

  15. A Neural Network Model for Forecasting CO2 Emission

    Directory of Open Access Journals (Sweden)

    C. Gallo

    2014-06-01

    Full Text Available Air pollution is today a serious problem, caused mainly by human activity. Classical methods are not considered able to efficiently model complex phenomena as meteorology and air pollution because, usually, they make approximations or too rigid schematisations. Our purpose is a more flexible architecture (artificial neural network model to implement a short-term CO2 emission forecasting tool applied to the cereal sector in Apulia region – in Southern Italy - to determine how the introduction of cultural methods with less environmental impact acts on a possible pollution reduction.

  16. Modeling canopy CO2 exchange in the European Russian Arctic

    DEFF Research Database (Denmark)

    Kiepe, Isabell; Friborg, Thomas; Herbst, Mathias

    2013-01-01

    In this study, we use the coupled photosynthesis-stomatal conductance model of Collatz et al. (1991) to simulate the current canopy carbon dioxide exchange of a heterogeneous tundra ecosystem in European Russia. For the parameterization, we used data obtained from in situ leaf level measurements...... in combination with meteorological data from 2008. The modeled CO2 fluxes were compared with net ecosystem exchange (NEE), measured by the eddy covariance technique during the snow-free period in 2008. The findings from this study indicated that the main state parameters of the exchange processes were leaf area...

  17. Modeling The Anthropogenic CO2 Footprint in Europe Using a High Resolution Atmospheric Model

    Science.gov (United States)

    Liu, Yu; Gruber, Nicolas; Brunner, Dominik

    2015-04-01

    The localized nature of most fossil fuel emission sources leaves a distinct footprint on atmospheric CO2 concentrations, yet to date, most studies have used relatively coarse atmospheric transport models to simulate this footprint, causing an excess amount of spatial smoothing. In addition, most studies have considered only monthly variations in emissions, neglecting their substantial diurnal and weekly fluctuations. With the fossil fuel emission fluxes dominating the carbon balance in Europe and many other industrialized countries, it is paramount to simulate the fossil fuel footprint in atmospheric CO2 accurately in time and space in order to discern the footprint of the terrestrial biosphere. Furthermore, a good understanding of the fossil fuel footprint also provides the opportunity to monitor and verify any change in fossil fuel emission. We use here a high resolution (7 km) atmospheric model setup for central Europe based on the operational weather forecast model COSMO and simulate the atmospheric CO2 concentrations separately for 5 fossil fuel emission sectors (i.e., power generation, heating, transport, industrial processes, and rest), and for 10 different country-based regions. The emissions were based on high-resolution emission inventory data (EDGAR(10km) and MeteoTest(500m)), to which we have added detailed time functions for each process and country. The total anthropogenic CO2 footprint compares well with observational estimates based on radiocarbon (C14) and CO for a number of sites across Europe, providing confidence in the emission inventory and atmospheric transport. Despite relatively rapid atmospheric mixing, the fossil fuel footprint shows strong annual mean structures reflecting the point-source nature of most emissions. Among all the processes, the emissions from power plants dominates the fossil fuel footprint, followed by industry, while traffic emissions are less distinct, largely owing to their spatially more distributed nature. However

  18. Reduction of transpiration and altered nutrient allocation contribute to nutrient decline of crops grown in elevated CO(2) concentrations.

    Science.gov (United States)

    McGrath, Justin M; Lobell, David B

    2013-03-01

    Plants grown in elevated [CO(2) ] have lower protein and mineral concentrations compared with plants grown in ambient [CO(2) ]. Dilution by enhanced production of carbohydrates is a likely cause, but it cannot explain all of the reductions. Two proposed, but untested, hypotheses are that (1) reduced canopy transpiration reduces mass flow of nutrients to the roots thus reducing nutrient uptake and (2) changes in metabolite or enzyme concentrations caused by physiological changes alter requirements for minerals as protein cofactors or in other organic complexes, shifting allocation between tissues and possibly altering uptake. Here, we use the meta-analysis of previous studies in crops to test these hypotheses. Nutrients acquired mostly by mass flow were decreased significantly more by elevated [CO(2) ] than nutrients acquired by diffusion to the roots through the soil, supporting the first hypothesis. Similarly, Mg showed large concentration declines in leaves and wheat stems, but smaller decreases in other tissues. Because chlorophyll requires a large fraction of total plant Mg, and chlorophyll concentration is reduced by growth in elevated [CO(2) ], this supports the second hypothesis. Understanding these mechanisms may guide efforts to improve nutrient content, and allow modeling of nutrient changes and health impacts under future climate change scenarios.

  19. Inverse modeling of CO2 sources and sinks using satellite observations of CO2 from TES and surface flask measurements

    Directory of Open Access Journals (Sweden)

    C. A. M. Brenninkmeijer

    2011-02-01

    Full Text Available We infer CO2 surface fluxes using satellite observations of mid-tropospheric CO2 from the Tropospheric Emission Spectrometer (TES and measurements of CO2 from surface flasks in a time-independent inversion analysis based on the GEOS-Chem model. Using TES CO2 observations over oceans, spanning 40° S–40° N, we find that the horizontal and vertical coverage of the TES and flask data are complementary. This complementarity is demonstrated by combining the datasets in a joint inversion, which provides better constraints than from either dataset alone, when a posteriori CO2 distributions are evaluated against independent ship and aircraft CO2 data. In particular, the joint inversion offers improved constraints in the tropics where surface measurements are sparse, such as the tropical forests of South America, which the joint inversion suggests was a weak sink of −0.17 ± 0.20 Pg C in 2006. Aggregating the annual surface-to-atmosphere fluxes from the joint inversion yields −1.13 ± 0.21 Pg C for the global ocean, −2.77 ± 0.20 Pg C for the global land biosphere and −3.90 ± 0.29 Pg C for the total global natural flux (defined as the sum of all biospheric, oceanic, and biomass burning contributions but excluding CO2 emissions from fossil fuel combustion. These global ocean, global land and total global fluxes are shown to be in the range of other inversion results for 2006. To achieve these results, a latitude dependent bias in TES CO2 in the Southern Hemisphere was assessed and corrected using aircraft flask data, and we demonstrate that our results have low sensitivity to variations in the bias correction approach. Overall, this analysis suggests that future carbon data assimilation systems can benefit by integrating in situ and satellite observations of CO2 and that the vertical information provided by satellite observations of mid-tropospheric CO2 combined with measurements of surface CO2, provides an important additional constraint for

  20. Inverse modeling of CO2 sources and sinks using satellite observations of CO2 from TES and surface flask measurements

    Directory of Open Access Journals (Sweden)

    C. A. M. Brenninkmeijer

    2011-06-01

    Full Text Available We infer CO2 surface fluxes using satellite observations of mid-tropospheric CO2 from the Tropospheric Emission Spectrometer (TES and measurements of CO2 from surface flasks in a time-independent inversion analysis based on the GEOS-Chem model. Using TES CO2 observations over oceans, spanning 40° S–40° N, we find that the horizontal and vertical coverage of the TES and flask data are complementary. This complementarity is demonstrated by combining the datasets in a joint inversion, which provides better constraints than from either dataset alone, when a posteriori CO2 distributions are evaluated against independent ship and aircraft CO2 data. In particular, the joint inversion offers improved constraints in the tropics where surface measurements are sparse, such as the tropical forests of South America. Aggregating the annual surface-to-atmosphere fluxes from the joint inversion for the year 2006 yields −1.13±0.21 Pg C for the global ocean, −2.77±0.20 Pg C for the global land biosphere and −3.90±0.29 Pg C for the total global natural flux (defined as the sum of all biospheric, oceanic, and biomass burning contributions but excluding CO2 emissions from fossil fuel combustion. These global ocean and global land fluxes are shown to be near the median of the broad range of values from other inversion results for 2006. To achieve these results, a bias in TES CO2 in the Southern Hemisphere was assessed and corrected using aircraft flask data, and we demonstrate that our results have low sensitivity to variations in the bias correction approach. Overall, this analysis suggests that future carbon data assimilation systems can benefit by integrating in situ and satellite observations of CO2 and that the vertical information provided by satellite observations of mid-tropospheric CO2 combined with measurements of surface CO2, provides an important additional constraint for flux inversions.

  1. Statistical Modelling of CO2 Emissions in Malaysia and Thailand

    Directory of Open Access Journals (Sweden)

    Tay Sze Hui

    2012-01-01

    Full Text Available Carbon dioxide (CO2 emissions is an environmental problem which leads to Earth’s greenhouse effect. Much concerns with carbon dioxide emissions centered around the growing threat of global warming and climate  change. This paper, however, presents a simple model development using multiple regression with interactions for estimating carbon dioxide emissions in Malaysia and Thailand. Five indicators over the period 1971-2006, namely  energy use, GDP per capita, population density, combustible renewables and waste, and CO2 intensity are used in the analysis. Progressive model selections using forward selection, backward elimination and stepwise regression are used to remove insignificant variables, with possible interactions. Model selection techniques are compared against the performance of eight criteria model selection process. Global test, Coefficient test, Wald test and Goodnessof-fit test are carried out to ensure that the best regression model is selected for further analysis. A numerical illustration is included to enhance the understanding of the whole process in obtaining the final best model.

  2. Chemical effects of a high CO2 concentration in oxy-fuel combustion of methane

    DEFF Research Database (Denmark)

    Glarborg, Peter; Bentzen, L.L.B.

    2008-01-01

    in terms of a detailed chemical kinetic mechanism for hydrocarbon oxidation. On the basis of results of the present study, it can be expected that oxy-fuel combustion will lead to strongly increased CO concentrations in the near-burner region. The CO2 present will compete with O-2 for atomic hydrogen......The oxidation of methane in an atmospheric-pres sure flow reactor has been studied experimentally under highly diluted conditions in N-2 and CO2, respectively. The stoichiometry was varied from fuel-lean to fuel-rich, and the temperatures covered the range 1200-1800 K. The results were interpreted...... and lead to formation of CO through the reaction CO2 + H reversible arrow CO + OH. Reactions of CO2 with hydrocarbon radicals may also contribute to CO formation. The most important steps are those of singlet and triplet CH2 with CO2, while other radicals such as CH3 and CH are less important for consuming...

  3. Physiological characteristics of the primitive CO2 concentrating mechanism in PEPC transgenic rice

    Institute of Scientific and Technical Information of China (English)

    焦德茂; 匡廷云; 李霞; 戈巧英; 黄雪清; 郝乃斌; 白克智

    2003-01-01

    The relationship between carbon assimilation and high-level expression of the maize PEPC in PEPC transgenic rice was studied by comparison to that in the untransformed rice, japonica kitaake. Stomatal conductance and photosynthetic rates in PEPC transgenic rice were higher than those of untransformed rice, but the increase of stomatal conductance had no statistical correlation with that of photosynthetic rate. Under high levels of light intensity, the protein contents of PEPC and CA were increased significantly. Therefore the photosynthetic capacity was increased greatly (50%) with atmospheric CO2 supply. While CO2 release in leaf was reduced and the compensation point was lowered correspondingly under CO2 free conditions. Treatment of the rice with the PEPC-specific inhibitor DCDP showed that overexpression of PEPC and enhancement of carbon assimilation were related to the stability of Fv/Fm. Labeling with 14CO2 for 20 s showed more 14C was distributed to C4 primary photosynthate asperate in PEPC transgenic rice, suggesting that there exists a limiting C4 photosynthetic mechanism in leaves. These results suggest that the primitive CO2 concentrating mechanism found in rice could be reproduced through metabolic engineering, and shed light on the physiological basis for transgenic breeding with high photosynthetic efficiency.

  4. Energy from CO2 using capacitive electrodes - a model for energy extraction cycles.

    Science.gov (United States)

    Paz-Garcia, J M; Dykstra, J E; Biesheuvel, P M; Hamelers, H V M

    2015-03-15

    A model is presented for the process of harvesting electrical energy from CO2 emissions using capacitive cells. The principle consists of controlling the mixing process of a concentrated CO2 gas stream with a dilute CO2 gas stream (as, for example, exhaust gas and air), thereby converting part of the released mixing energy into electrical energy. The model describes the transient reactive transport of CO2 gas absorbed in water or in monoethanolamine (MEA) solutions, under the assumption of local chemical equilibrium. The model combines the selective transport of ions through ion-exchange membranes, the accumulation of charge in the porous carbon electrodes and the coupling between the ionic current and the produced electrical current and power. We demonstrate that the model can be used to calculate the energy that can be extracted by mixing concentrated and dilute CO2 containing gas streams. Our calculation results for the process using MEA solutions have various counterintuitive features, including: 1. When dynamic equilibrium is reached in the cyclical process, the electrical charge in the anode is negative both during charging and discharging; 2. Placing an anion-exchange membrane (AEM) in the system is not required, the energy per cycle is just as large with or without an AEM. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. Pulsed Lidar Measurements of Atmospheric CO2 Column Concentration in the ASCENDS 2014 Airborne Campaign

    Science.gov (United States)

    Abshire, J. B.; Ramanathan, A. K.; Mao, J.; Riris, H.; Allan, G. R.; Hasselbrack, W. E.; Chen, J. R.

    2015-12-01

    We report progress in demonstrating a pulsed, wavelength-resolved IPDA lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS mission. The CO2 lidar flies on NASA's DC-8 aircraft and measures the atmospheric backscatter profiles and shape of the 1572.33 nm absorption line by using 30 wavelength samples distributed across the lube. Our post-flight analysis estimates the lidar range and pulse energies at each wavelength 10 times per second. The retrievals solve for the optimum CO2 absorption line shape and the column average CO2 concentrations using radiative transfer calculations based on HITRAN, the aircraft altitude, range to the scattering surface, and the atmospheric conditions. We compare these to CO2 concentrations sampled by in-situ sensors on the aircraft. The number of wavelength samples can be reduced in the retrievals. During the ASCENDS airborne campaign in 2013 two flights were made in February over snow in the Rocky Mountains and the Central Plains allowing measurement of snow-covered surface reflectivity. Several improvements were made to the lidar for the 2014 campaign. These included using a new step-locked laser diode source, and incorporating a new HgCdTe APD detector and analog digitizer into the lidar receiver. Testing showed this detector had higher sensitivity, analog response, and a more linear dynamic range than the PMT detector used previously. In 2014 flights were made in late August and early September over the California Central Valley, the redwood forests along the California coast, two desert areas in Nevada and California, and two flights above growing agriculture in Iowa. Two flights were also made under OCO-2 satellite ground tracks. Analyses show the retrievals of lidar range and CO2 column absorption, and mixing ratio worked well when measuring over topography with rapidly changing height and reflectivity, and through thin clouds and aerosol scattering. The lidar measurements clearly

  6. Mathematical modeling as a tool to assess microbial community responses to CO2 injection

    Science.gov (United States)

    Vilcaez, J.

    2014-12-01

    The issue of subsurface microbial community responses to the injection of CO2 has great importance not only from a risk assessment point of view but also from the perspective of CO2 recycling to CH4. In this sense, the objective of this study is to develop mathematical models to make a quantitative description of the responses of subsurface indigenous microbial communities to the injection of CO2. For this end, TOUGHREACTV1.2 reactive transport simulator with its module ECO2N is used as the modeling framework. The targeted microbial community is composed of fermentative bacteria (Organic matter → Acetate & H2), acetotrophic methanogens (Acetate → Methane & CO2), acetotrophic Sulfate Reducing Bacteria (SRB) (Acetate → H2S & CO2), hydrogenotrophic methanogens (H2 & CO2 → CH4), and hydrogenotrophic SRB (H2 → H2S). Due to the multiple hydrogeological, geochemical and microbiological factors intervening in both the response of subsurface microbial communities to the injection of CO2 and the chemical and physical fate of CO2 itself, at this stage simulations have been performed in batch mode. That means numerical simulations aimed to track changes in CO2 saturation levels, pH, and concentrations of mineral and aqueous phase species over time at selected initial conditions. Numerical simulation results indicate that the activity of microbes associated with methanogenic processes in geological storage sites of CO2 is governed by the level of CO2 saturation in the pore space as well as by the presence of pH buffering minerals such as calcite. With calcite in the mineral phase attenuating drops in pH below inhibitory levels, for instance it is shown that acetotrophic and hydrogenotrophic SRB outcompete acetotrophic and hydrogenotrophic methanogens for acetate and H2, respectively. During the initial stages of the reaction when the pH level is lowest, the higher tolerance of hydrogenotrophic methanogens to acidic pH levels is reflected by a preferential formation of

  7. Uptake and Storage of Anthropogenic CO2 in the Pacific Ocean Estimated Using Two Modeling Approaches

    Institute of Scientific and Technical Information of China (English)

    LI Yangchun; XU Yongfu

    2012-01-01

    A basin-wide ocean general circulation model (OGCM) of the Pacific Ocean is employed to estimate the uptake and storage of anthropogenic CO2 using two different simulation approaches.The simulation (named BIO) makes use of a carbon model with biological processes and full thermodynamic equations to calculate surface water partial pressure of CO2,whereas the other simulation (named PTB) makes use of a perturbation approach to calculate surface water partial pressure of anthropogenie CO2.The results from the two simulations agree well with the estimates based on observation data in most important aspects of the vertical distribution as well as the total inventory of anthropogenic carbon.The storage of anthropogenic carbon from BIO is closer to the observation-based estimate than that from PTB.The Revelle factor in 1994 obtained in BIO is generally larger than that obtained in PTB in the whole Pacific,except for the subtropical South Pacific.This,to large extent,leads to the difference in the surface anthropogenic CO2 concentration between the two runs.The relative difference in the annual uptake between the two runs is almost constant during the integration processes after 1850.This is probably not caused by dissolved inorganic carbon (DIC),but rather by a factor independent of time.In both runs,the rate of change in anthropogenic CO2 fluxes with time is consistent with the rate of change in the growth rate of atmospheric partial pressure of CO2.

  8. Productive and morphogenetic responses of buffel grass at different air temperatures and CO2 concentrations

    Directory of Open Access Journals (Sweden)

    Roberta Machado Santos

    2014-08-01

    Full Text Available The objective of the present trial was to evaluate the productive and morphogenetic characteristics of buffel grass subjected to different air temperatures and CO2 concentrations. Three cultivars of buffel grass (Biloela, Aridus and West Australian were compared. Cultivars were grown in growth chambers at three temperatures (day/night: 26/20, 29/23, and 32/26 °C, combined with two concentrations of CO2: 370 and 550 µmol mol-1. The experimental design was completely randomized, in a 3 × 3 × 2 factorial arrangement with three replications. There were interactions between buffel grass cultivars and air temperatures on leaf elongation rate (LER, leaf appearance rate (LAR, leaf lifespan (LL and senescence rate (SR, whereas cultivars vs. carbon dioxide concentration affected forage mass (FM, root mass (RM, shoot/root ratio, LL and SR. Leaf elongation rate and SR were higher as the air temperature was raised. Increasing air temperature also promoted an increase in LAR, except for West Australian. High CO2 concentration provided greater SR of plants, except for Biloela. Cultivar West Australian had higher FM in relation to Biloela and Aridus when the CO2 concentration was increased to 550 µmol mol-1. West Australian was the only cultivar that responded with more forage mass when it was exposed to higher carbon dioxide concentrations, whereas Aridus had depression in forage mass. The increase in air temperatures affects morphogenetic responses of buffel grass, accelerating its vegetative development without increasing forage mass. Elevated carbon dioxide concentration changes productive responses of buffel grass.

  9. Seasonal and diel variation in xylem CO2 concentration and sap pH in sub-Mediterranean oak stems.

    Science.gov (United States)

    Salomón, Roberto; Valbuena-Carabaña, María; Teskey, Robert; McGuire, Mary Anne; Aubrey, Doug; González-Doncel, Inés; Gil, Luis; Rodríguez-Calcerrada, Jesús

    2016-04-01

    Since a substantial portion of respired CO2 remains within the stem, diel and seasonal trends in stem CO2 concentration ([CO2]) are of major interest in plant respiration and carbon budget research. However, continuous long-term stem [CO2] studies are scarce, and generally absent in Mediterranean climates. In this study, stem [CO2] was monitored every 15min together with stem and air temperature, sap flow, and soil water storage during a growing season in 16 stems of Quercus pyrenaica to elucidate the main drivers of stem [CO2] at different temporal scales. Fluctuations in sap pH were also assessed during two growing seasons to evaluate potential errors in estimates of the concentration of CO2 dissolved in xylem sap ([CO2*]) calculated using Henry's law. Stem temperature was the best predictor of stem [CO2] and explained more than 90% and 50% of the variability in stem [CO2] at diel and seasonal scales, respectively. Under dry conditions, soil water storage was the main driver of stem [CO2]. Likewise, the first rains after summer drought caused intense stem [CO2] pulses, suggesting enhanced stem and root respiration and increased resistance to radial CO2 diffusion. Sap flow played a secondary role in controlling stem [CO2] variations. We observed night-time sap pH acidification and progressive seasonal alkalinization. Thus, if the annual mean value of sap pH (measured at midday) was assumed to be constant, night-time sap [CO2*] was substantially overestimated (40%), and spring and autumn sap [CO2*] were misestimated by 25%. This work highlights that diel and seasonal variations in temperature, tree water availability, and sap pH substantially affect xylem [CO2] and sap [CO2*].

  10. Changing atmospheric CO2 concentration was the primary driver of early Cenozoic climate.

    Science.gov (United States)

    Anagnostou, Eleni; John, Eleanor H; Edgar, Kirsty M; Foster, Gavin L; Ridgwell, Andy; Inglis, Gordon N; Pancost, Richard D; Lunt, Daniel J; Pearson, Paul N

    2016-05-19

    The Early Eocene Climate Optimum (EECO, which occurred about 51 to 53 million years ago), was the warmest interval of the past 65 million years, with mean annual surface air temperature over ten degrees Celsius warmer than during the pre-industrial period. Subsequent global cooling in the middle and late Eocene epoch, especially at high latitudes, eventually led to continental ice sheet development in Antarctica in the early Oligocene epoch (about 33.6 million years ago). However, existing estimates place atmospheric carbon dioxide (CO2) levels during the Eocene at 500-3,000 parts per million, and in the absence of tighter constraints carbon-climate interactions over this interval remain uncertain. Here we use recent analytical and methodological developments to generate a new high-fidelity record of CO2 concentrations using the boron isotope (δ(11)B) composition of well preserved planktonic foraminifera from the Tanzania Drilling Project, revising previous estimates. Although species-level uncertainties make absolute values difficult to constrain, CO2 concentrations during the EECO were around 1,400 parts per million. The relative decline in CO2 concentration through the Eocene is more robustly constrained at about fifty per cent, with a further decline into the Oligocene. Provided the latitudinal dependency of sea surface temperature change for a given climate forcing in the Eocene was similar to that of the late Quaternary period, this CO2 decline was sufficient to drive the well documented high- and low-latitude cooling that occurred through the Eocene. Once the change in global temperature between the pre-industrial period and the Eocene caused by the action of all known slow feedbacks (apart from those associated with the carbon cycle) is removed, both the EECO and the late Eocene exhibit an equilibrium climate sensitivity relative to the pre-industrial period of 2.1 to 4.6 degrees Celsius per CO2 doubling (66 per cent confidence), which is similar to the

  11. Changing atmospheric CO2 concentration was the primary driver of early Cenozoic climate

    Science.gov (United States)

    Anagnostou, Eleni; John, Eleanor H.; Edgar, Kirsty M.; Foster, Gavin L.; Ridgwell, Andy; Inglis, Gordon N.; Pancost, Richard D.; Lunt, Daniel J.; Pearson, Paul N.

    2016-05-01

    The Early Eocene Climate Optimum (EECO, which occurred about 51 to 53 million years ago), was the warmest interval of the past 65 million years, with mean annual surface air temperature over ten degrees Celsius warmer than during the pre-industrial period. Subsequent global cooling in the middle and late Eocene epoch, especially at high latitudes, eventually led to continental ice sheet development in Antarctica in the early Oligocene epoch (about 33.6 million years ago). However, existing estimates place atmospheric carbon dioxide (CO2) levels during the Eocene at 500-3,000 parts per million, and in the absence of tighter constraints carbon-climate interactions over this interval remain uncertain. Here we use recent analytical and methodological developments to generate a new high-fidelity record of CO2 concentrations using the boron isotope (δ11B) composition of well preserved planktonic foraminifera from the Tanzania Drilling Project, revising previous estimates. Although species-level uncertainties make absolute values difficult to constrain, CO2 concentrations during the EECO were around 1,400 parts per million. The relative decline in CO2 concentration through the Eocene is more robustly constrained at about fifty per cent, with a further decline into the Oligocene. Provided the latitudinal dependency of sea surface temperature change for a given climate forcing in the Eocene was similar to that of the late Quaternary period, this CO2 decline was sufficient to drive the well documented high- and low-latitude cooling that occurred through the Eocene. Once the change in global temperature between the pre-industrial period and the Eocene caused by the action of all known slow feedbacks (apart from those associated with the carbon cycle) is removed, both the EECO and the late Eocene exhibit an equilibrium climate sensitivity relative to the pre-industrial period of 2.1 to 4.6 degrees Celsius per CO2 doubling (66 per cent confidence), which is similar to the

  12. Modelling Plant and Soil Nitrogen Feedbacks Affecting Forest Carbon Gain at High CO2

    Science.gov (United States)

    McMurtrie, R. E.; Norby, R. J.; Franklin, O.; Pepper, D. A.

    2007-12-01

    Short-term, direct effects of elevated atmospheric CO2 concentrations on plant carbon gain are relatively well understood. There is considerable uncertainty, however, about longer-term effects, which are influenced by various plant and ecosystem feedbacks. A key feedback in terrestrial ecosystems occurs through changes in plant carbon (C) allocation patterns. For instance, if high CO2 were to increase C allocation to roots, then plants may experience positive feedback through improved plant nutrition. A second type of feedback, associated with decomposition of soil-organic matter, may reduce soil-nutrient availability at high CO2. This paper will consider mechanistic models of both feedbacks. Effects of high CO2 on plant C allocation will be investigated using a simple model of forest net primary production (NPP) that incorporates the primary mechanisms of plant carbon and nitrogen (N) balance. The model called MATE (Model Any Terrestrial Ecosystem) includes an equation for annual C balance that depends on light- saturated photosynthetic rate and therefore on [CO2], and an equation for N balance incorporating an expression for N uptake as a function of root mass. The C-N model is applied to a Free Air CO2 Exchange (FACE) experiment at Oak Ridge National Laboratory (ORNL) in Tennessee, USA, where closed-canopy, monoculture stands of the deciduous hardwood sweetgum ( Liquidambar styraciflua) have been growing at [CO2] of 375 and 550 ppm for ten years. Features of this experiment are that the annual NPP response to elevated CO2 has averaged approximately 25% over seven years, but that annual fine-root production has almost doubled on average, with especially large increases in later years of the experiment (Norby et al. 2006). The model provides a simple graphical approach for analysing effects of elevated CO2 and N supply on leaf/root/wood C allocation and productivity. It simulates increases in NPP and fine-root production at the ORNL FACE site that are consistent

  13. A liquid CO2-compatible hydrocarbon surfactant: experiment and modelling

    NARCIS (Netherlands)

    Banerjee, S.; Kleijn, J.M.; Cohen Stuart, M.A.; Leermakers, F.A.M.

    2013-01-01

    Surfactants soluble in liquid CO2 are rare and knowledge on interfacial and self-assembly behaviour is fragmented. We found that polyoxyethylene (5) isooctylphenyl ether is interfacially active at the water–liquid CO2 interface. Water–liquid CO2 interfacial tension was measured at various surfactant

  14. Modelling the electrical resistivity response to CO2 plumes generated in a laboratory, cylindrical sandbox

    Science.gov (United States)

    Kremer, T.; Maineult, A. J.; Binley, A.; Vieira, C.; Zamora, M.

    2012-12-01

    CO2 capture and storage into deep geological formations is one of the main solutions proposed to reduce the concentration of anthropic CO2 in the atmosphere. The monitoring of injection sites is a crucial issue to assess for the long term viability of CO2 storage. With the intention of detecting potential leakages, we are investigating the possibility of using electrical resistivity tomography (ERT) techniques to detect CO2 transfers in the shallow sub-surface. ERT measurements were performed during a CO2 injection in a cylindrical tank filled with Fontainebleau sand and saturated with water. Several measurements protocols were tested. The inversion of the resistances measured with the software R3T (Binley and Kemna (2005)) clearly showed that the CO2 injection induces significant changes in the resistivity distribution of the medium, and that ERT has a promising potential for the detection and survey of CO2 transfers through unconsolidated saturated media. We modeled this experiment using Matlab by building a 3D cellular automaton that describes the CO2 spreading, following the geometric and stochastic approach described by Selker et al. (2007). The CO2 circulation is described as independents, circular and continuous gas channels whose horizontal spread depends on a Gaussian probability law. From the channel distribution we define the corresponding gas concentration distribution and calculate the resistivity of the medium by applying Archie's law for unsaturated conditions. The forward modelling was performed with the software R3T to convert the resistivity distribution into resistances values, each corresponding to one of the electrode arrays used in the experimental measurements. Modelled and measured resistances show a good correlation, except for the electrode arrays located at the top or the bottom of the tank. We improved the precision of the model by considering the effects due to CO2 dissolution in the water which increases the conductivity of the

  15. Sensitivity of grapevine phenology to water availability, temperature and CO2 concentration

    Directory of Open Access Journals (Sweden)

    Johann Martínez-Lüscher

    2016-07-01

    Full Text Available In recent decades, mean global temperatures have increased in parallel with a sharp rise in atmospheric carbon dioxide (CO2 levels, with apparent implications for precipitation patterns. The aim of the present work is to assess the sensitivity of different phenological stages of grapevine to temperature and to study the influence of other factors related to climate change (water availability and CO2 concentration on this relationship. Grapevine phenological records from 9 plantings between 42.75°N and 46.03°N consisting of dates for budburst, flowering and fruit maturity were used. In addition, we used phenological data collected from two years of experiments with grapevine fruit-bearing cuttings with two grapevine varieties under two levels of water availability, two temperature regimes and two levels of CO2. Dormancy breaking and flowering were strongly dependent on spring temperature, while neither variation in temperature during the chilling period nor precipitation significantly affected budburst date. The time needed to reach fruit maturity diminished with increasing temperature and decreasing precipitation. Experiments under semi-controlled conditions revealed great sensitivity of berry development to both temperature and CO2. Water availability had significant interactions with both temperature and CO2; however, in general, water deficit delayed maturity when combined with other factors. Sensitivities to temperature and CO2 varied widely, but higher sensitivities appeared in the coolest year, particularly for the late ripening variety, ‘White Tempranillo’. The knowledge gained in whole plant physiology and multi stress approaches is crucial to predict the effects of climate change and to design mitigation and adaptation strategies allowing viticulture to cope with climate change.

  16. Modeling CO2 air dispersion from gas driven lake eruptions

    Science.gov (United States)

    Chiodini, Giovanni; Costa, Antonio; Rouwet, Dmitri; Tassi, Franco

    2016-04-01

    The most tragic event of gas driven lake eruption occurred at Lake Nyos (Cameroon) on 21 August 1986, when a dense cloud of CO2 suffocated more than 1700 people and an uncounted number of animals in just one night. The event stimulated a series of researches aimed to understand gas origins, gas release mechanisms and strategies for gas hazard mitigation. Very few studies have been carried out for describing the transport of dense CO2 clouds in the atmosphere. Although from a theoretical point of view, gas dispersion can be fully studied by solving the complete equations system for mass, momentum and energy transport, in actual practice, different simplified models able to describe only specific phases or aspects have to be used. In order to simulate dispersion of a heavy gas and to assess the consequent hazard we used a model based on a shallow layer approach (TWODEE2). This technique which uses depth-averaged variables to describe the flow behavior of dense gas over complex topography represents a good compromise between the complexity of computational fluid dynamic models and the simpler integral models. Recently the model has been applied for simulating CO2 dispersion from natural gas emissions in Central Italy. The results have shown how the dispersion pattern is strongly affected by the intensity of gas release, the topography and the ambient wind speed. Here for the first time we applied TWODEE2 code to simulate the dispersion of the large CO2 clouds released by limnic eruptions. An application concerns the case of the 1986 event at lake Nyos. Some difficulties for the simulations were related to the lack of quantitative information: gas flux estimations are not well constrained, meteorological conditions are only qualitatively known, the digital model of the terrain is of poor quality. Different scenarios were taken into account in order to reproduce the qualitative observations available for such episode. The observations regard mainly the effects of gas on

  17. Toward Verifying Fossil Fuel CO2 Emissions with the CMAQ Model: Motivation, Model Description and Initial Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhen; Bambha, Ray P.; Pinto, Joseph P.; Zeng, Tao; Boylan, Jim; Huang, Maoyi; Lei, Huimin; Zhao, Chun; Liu, Shishi; Mao, Jiafu; Schwalm, Christopher R.; Shi, Xiaoying; Wei, Yaxing; Michelsen, Hope A.

    2014-03-14

    Motivated by the urgent need for emission verification of CO2 and other greenhouse gases, we have developed regional CO2 simulation with CMAQ over the contiguous U.S. Model sensitivity experiments have been performed using three different sets of inputs for net ecosystem exchange (NEE) and two fossil fuel emission inventories, to understand the roles of fossil fuel emissions, atmosphere-biosphere exchange and transport in regulating the spatial and diurnal variability of CO2 near the surface, and to characterize the well-known ‘signal-to-noise’ problem, i.e. the interference from the biosphere on the interpretation of atmospheric CO2 observations. It is found that differences in the meteorological conditions for different urban areas strongly contribute to the contrast in concentrations. The uncertainty of NEE, as measured by the difference among the three different NEE inputs, has notable impact on regional distribution of CO2 simulated by CMAQ. Larger NEE uncertainty and impact are found over eastern U.S. urban areas than along the western coast. A comparison with tower CO2 measurements at Boulder Atmospheric Observatory (BAO) shows that the CMAQ model using hourly varied and high-resolution CO2 emission from the Vulcan inventory and CarbonTracker optimized NEE reasonably reproduce the observed diurnal profile, whereas switching to different NEE inputs significantly degrades the model performance. Spatial distribution of CO2 is found to correlate with NOx, SO2 and CO, due to their similarity in emission sources and transport processes. These initial results from CMAQ demonstrate the power of a state-of-the art CTM in helping interpret CO2 observations and verify fossil fuel emissions. The ability to simulate CO2 in CMAQ will also facilitate investigations of the utility of traditionally regulated pollutants and other species as tracers to CO2 source attribution.

  18. Effects of elevated atmospherical CO2 concentration and nitrogen fertilisation on priming effects in soils

    Science.gov (United States)

    Ohm, H.; Marschner, B.

    2009-04-01

    It is expected that the biomass production and thus the input of organic carbon to the soil will increase in response to elevated CO¬2 concentrations in the atmosphere. It remains unclear whether this will lead to a long term increased carbon pool, because only little is known about the stability of the additional carbon inputs. The soil samples were taken on an agricultural field at the experimental farm of the Federal Agricultural Research Centre (FAL) in Braunschweig, Germany. A Free-Air Carbon-dioxide Enrichment (FACE) system was installed here in May 2000. It consists of rings with 20 m diameter. Two rings were operated with CO2 enriched air (550 ppm), another two rings received ambient air (370 ppm). One half of each ring received the full amount of nitrogen fertiliser, the remainder received only half of this N-amount. The soil samples were taken after 6 years of operation and were incubated with 14C-labeled fructose and alanine for 21 days. Furthermore, combined additions with the respective substrate and ammonium nitrate or ammonium nitrate alone were conducted. The microbial biomass was determined after 2 and 21 days. In the untreated controls the SOC mineralisation amounted to 0.59 to 0.68%. The addition of fructose, fructose+NH4NO3, alanine and alanine+NH4NO3 to the different soil samples increased SOC mineralization and thus caused priming effects of different extents. For NH4NO3 no priming effects occurred. The addition of fructose induced positive priming effects in all samples. The lowest priming effect was observed in the sample ambient CO2+50% N (+50%), either with fructose alone or in combination with NH4NO3. The addition of alanine caused similar priming effects in the ambient CO2+100% N and the elevated CO2+100% N samples (+92.4 and +95.6%, respectively). Again, the lowest priming effect was observed in the sample ambient CO2+50% N. The microbial biomass showed a clear increase in the substrate treated samples compared to the controls. The

  19. Experimental and numerical results for CO2 concentration and temperature profiles in an occupied room

    Science.gov (United States)

    Cotel, Aline; Junghans, Lars; Wang, Xiaoxiang

    2014-11-01

    In recent years, a recognition of the scope of the negative environmental impact of existing buildings has spurred academic and industrial interest in transforming existing building design practices and disciplinary knowledge. For example, buildings alone consume 72% of the electricity produced annually in the United States; this share is expected to rise to 75% by 2025 (EPA, 2009). Significant reductions in overall building energy consumption can be achieved using green building methods such as natural ventilation. An office was instrumented on campus to acquire CO2 concentrations and temperature profiles at multiple locations while a single occupant was present. Using openFOAM, numerical calculations were performed to allow for comparisons of the CO2 concentration and temperature profiles for different ventilation strategies. Ultimately, these results will be the inputs into a real time feedback control system that can adjust actuators for indoor ventilation and utilize green design strategies. Funded by UM Office of Vice President for Research.

  20. Correlation of Amine Swingbed On-Orbit CO2 Performance with a Hardware Independent Predictive Model

    Science.gov (United States)

    Papale, William; Sweterlitsch, Jeffery

    2015-01-01

    The Amine Swingbed Payload is an experimental system deployed on the International Space Station (ISS) that includes a two-bed, vacuum regenerated, amine-based carbon dioxide (CO2) removal subsystem as the principal item under investigation. The aminebased subsystem, also described previously in various publications as CAMRAS 3, was originally designed, fabricated and tested by Hamilton Sundstrand Space Systems International, Inc. (HSSSI) and delivered to NASA in November 2008. The CAMRAS 3 unit was subsequently designed into a flight payload experiment in 2010 and 2011, with flight test integration activities accomplished on-orbit between January 2012 and March 2013. Payload activation was accomplished in May 2013 followed by a 1000 hour experimental period. The experimental nature of the Payload and the interaction with the dynamic ISS environment present unique scientific and engineering challenges, in particular to the verification and validation of the expected Payload CO2 removal performance. A modeling and simulation approach that incorporates principles of chemical reaction engineering has been developed for the amine-based system to predict the dynamic cabin CO2 partial pressure with given inputs of sorbent bed size, process air flow, operating temperature, half-cycle time, CO2 generation rate, cabin volume and the magnitude of vacuum available. Simulation runs using the model to predict ambient CO2 concentrations show good correlation to on-orbit performance measurements and ISS dynamic concentrations for the assumed operating conditions. The dynamic predictive modelling could benefit operational planning to help ensure ISS CO2 concentrations are maintained below prescribed limits and for the Orion vehicle to simulate various operating conditions, scenarios and transients.

  1. [Measurements of CO2 Concentration Profile in Troposphere Based on Balloon-Borne TDLAS System].

    Science.gov (United States)

    Yao, Lu; Liu, Wen-qing; Liu, Jian-guo; Kan, Rui-feng; Xu, Zhen-yu; Ruan, Jun; Yuan, Song

    2015-10-01

    The main source and sink of CO2 in the atmosphere are concentrated in the troposphere. It is of great significance to the study of CO2 flux and global climate change to obtain the accurate tropospheric CO2 concentration profile. For the characteristics of high resolution, high sensitivity and fast response of tunable diode laser absorption spectroscopy (TDLAS), a compact balloon-borne system based on direct absorption was developed to detect the CO2 concentration profiles by use of the 2 004. 02 nm, R(16), v1+v3 line without the interfere of H2O absorption and the CO2 density of the number of molecules below 10 km in the troposphere was obtained. Due to the balloon-borne environment, a compact design of one single board integrated with laser driver, signal conditioning, spectra acquiring and concentration retrieving was developed. Limited by the working capability and hardware resources of embedded micro-processor, the spectra processing algorithm was optimized to reduce the time-cost. Compared with the traditional TDLAS sensors with WMS technique, this system was designed based on the direct absorption technique by means of an open-path Herriott cell with 20 m optical-path, which avoided the process of standardization and enhanced the environmental adaptation. The universal design of hardware and software platform achieved diverse gas measuring by changing the laser and adjusting some key parameters in algorithm. The concept of compact design helped to reduce the system's power and volume and balanced the response speed and measure precision. The power consumes below 1.5 W in room temperature and the volume of the single board is 120 mm x 100 mm x 25 mm, and the measurement accuracy is ± 0.6 x 10(-6) at 1.5 s response time. It has been proved that the system can realize high precision detection of CO2 profile at 15 m vertical resolution in troposphere and TDLAS is an available method for balloon-borne detection.

  2. Effects of Elevated CO2 Concentration on the Biomasses and Nitrogen Concentrations in the Organs of Sainfoin(Onobrychis viciaefolia Scop.)

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zheng-chao; SHANGGUAN Zhou-ping

    2009-01-01

    In forage grasses,the nitrogen concentration is directly related to the nutritional value.The studies examined the hypothesis that global elevation of CO2 concentration probably affects the biomass,nitrogen(N)concentration,and allocation and distribution patterns in the organs of forage grasses.While sainfoin(Onobrychis viciaefolia Scop.)seedlings grew on a low nutrient soil in closed chambers for 90 days,they were exposed to two CO2 concentrations(ambient or ambient+350μmol mol-1 CO2)without adding nutrients to them.After 90 days exposure to CO2,the biomasses of leaves,stems,and roots,and N concentrations and contents of different parts were measured.Compared with the ambient CO2 concentration,the elevated CO2 concentration increased the total dry matter by 25.07%,mainly due to the root and leaf having positive response to the elevated CO2 concentration.However,the elevated CO2 concentration did not change the proportions of the dry matters in different parts and the total plants compared with the ambient CO2 concentration.The elevated CO2 concentration lowered the N concentrations of the plant parts.Because the dry matter was higher,the elevated CO2 concentration had no effect on the N content in the plants compared to the ambient CO2 concentration.The elevated CO2 concentration promoted N allocations of the different parts significantly and increased N allocation of the underground part.The results have confirmed the previous suggestions that the elevated CO2 concentration stimulates plant biomass production and decreases the N concentrations of the plant parts.

  3. Sensitivity of Terrestrial Water and Energy Budgets to CO2-Physiological Forcing: An Investigation Using an Offline Land Model

    Science.gov (United States)

    Gopalakrishnan, Ranjith; Bala, Govindsamy; Jayaraman, Mathangi; Cao, Long; Nemani, Ramakrishna; Ravindranath, N. H.

    2011-01-01

    Increasing concentrations of atmospheric carbon dioxide (CO2) influence climate by suppressing canopy transpiration in addition to its well-known greenhouse gas effect. The decrease in plant transpiration is due to changes in plant physiology (reduced opening of plant stomata). Here, we quantify such changes in water flux for various levels of CO2 concentrations using the National Center for Atmospheric Research s (NCAR) Community Land Model. We find that photosynthesis saturates after 800 ppmv (parts per million, by volume) in this model. However, unlike photosynthesis, canopy transpiration continues to decline at about 5.1% per 100 ppmv increase in CO2 levels. We also find that the associated reduction in latent heat flux is primarily compensated by increased sensible heat flux. The continued decline in canopy transpiration and subsequent increase in sensible heat flux at elevated CO2 levels implies that incremental warming associated with the physiological effect of CO2 will not abate at higher CO2 concentrations, indicating important consequences for the global water and carbon cycles from anthropogenic CO2 emissions. Keywords: CO2-physiological effect, CO2-fertilization, canopy transpiration, water cycle, runoff, climate change 1.

  4. 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.

  5. Optimization of a prognostic biosphere model for terrestrial biomass and atmospheric CO2 variability

    Directory of Open Access Journals (Sweden)

    M. Saito

    2014-08-01

    Full Text Available This study investigates the capacity of a prognostic biosphere model to simulate global variability in atmospheric CO2 concentrations and vegetation carbon dynamics under current environmental conditions. Global data sets of atmospheric CO2 concentrations, above-ground biomass (AGB, and net primary productivity (NPP in terrestrial vegetation were assimilated into the biosphere model using an inverse modeling method combined with an atmospheric transport model. In this process, the optimal physiological parameters of the biosphere model were estimated by minimizing the misfit between observed and modeled values, and parameters were generated to characterize various biome types. Results obtained using the model with the optimized parameters correspond to the observed seasonal variations in CO2 concentration and their annual amplitudes in both the Northern and Southern Hemispheres. In simulating the mean annual AGB and NPP, the model shows improvements in estimating the mean magnitudes and probability distributions for each biome, as compared with results obtained using prior simulation parameters. However, the model is less efficient in its simulation of AGB for forest type biomes. This misfit suggests that more accurate values of input parameters, specifically, grid mean AGB values and seasonal variabilities in physiological parameters, are required to improve the performance of the simulation model.

  6. Dynamics of Postcombustion CO2 Capture Plants: Modeling, Validation, and Case Study.

    Science.gov (United States)

    van de Haar, Adam; Trapp, Carsten; Wellner, Kai; de Kler, Robert; Schmitz, Gerhard; Colonna, Piero

    2017-02-22

    The capture of CO2 from power plant flue gases provides an opportunity to mitigate emissions that are harmful to the global climate. While the process of CO2 capture using an aqueous amine solution is well-known from experience in other technical sectors (e.g., acid gas removal in the gas processing industry), its operation combined with a power plant still needs investigation because in this case, the interaction with power plants that are increasingly operated dynamically poses control challenges. This article presents the dynamic modeling of CO2 capture plants followed by a detailed validation using transient measurements recorded from the pilot plant operated at the Maasvlakte power station in the Netherlands. The model predictions are in good agreement with the experimental data related to the transient changes of the main process variables such as flow rate, CO2 concentrations, temperatures, and solvent loading. The validated model was used to study the effects of fast power plant transients on the capture plant operation. A relevant result of this work is that an integrated CO2 capture plant might enable more dynamic operation of retrofitted fossil fuel power plants because the large amount of steam needed by the capture process can be diverted rapidly to and from the power plant.

  7. Effect of CO2 Concentration on Growth and Biochemical Composition of Newly Isolated Indigenous Microalga Scenedesmus bajacalifornicus BBKLP-07.

    Science.gov (United States)

    Patil, Lakkanagouda; Kaliwal, Basappa

    2016-11-23

    Photosynthetic mitigation of CO2 through microalgae is gaining great importance due to its higher photosynthetic ability compared to plants, and the biomass can be commercially exploited for various applications. CO2 fixation capability of the newly isolated freshwater microalgae Scenedesmus bajacalifornicus BBKLP-07 was investigated using a 1-l photobioreactor. The cultivation was carried at varying concentration of CO2 ranging from 5 to 25%, and the temperature and light intensities were kept constant. A maximum CO2 fixation rate was observed at 15% CO2 concentration. Characteristic growth parameters such as biomass productivity, specific growth rate, and maximum biomass yield, and biochemical parameters such as carbohydrate, protein, lipid, chlorophyll, and carotenoid were determined and discussed. It was observed that the effect of CO2 concentration on growth and biochemical composition was quite significant. The maximum biomass productivity was 0.061 ± 0.0007 g/l/day, and the rate of CO2 fixation was 0.12 ± 0.002 g/l/day at 15% CO2 concentration. The carbohydrate and lipid content were maximum at 25% CO2 with 26.19 and 25.81% dry cell weight whereas protein, chlorophyll, and carotenoid contents were 32.89% dry cell weight, 25.07 μg/ml and 6.15 μg/ml respectively at 15% CO2 concentration.

  8. 3D modelling of the early Martian Climate under a denser CO2 atmosphere: Temperatures and CO2 ice clouds

    CERN Document Server

    Forget, Francois; Millour, Ehouarn; Madeleine, Jean-Baptiste; Kerber, Laura; Leconte, Jeremy; Marcq, Emmanuel; Haberle, Robert M

    2012-01-01

    On the basis of geological evidence, it is often stated that the early martian climate was warm enough for liquid water to flow on the surface thanks to the greenhouse effect of a thick atmosphere. We present 3D global climate simulations of the early martian climate performed assuming a faint young sun and a CO2 atmosphere with pressure between 0.1 and 7 bars. The model includes a detailed radiative transfer model using revised CO2 gas collision induced absorption properties, and a parameterisation of the CO2 ice cloud microphysical and radiative properties. A wide range of possible climates is explored by using various values of obliquities, orbital parameters, cloud microphysic parameters, atmospheric dust loading, and surface properties. Unlike on present day Mars, for pressures higher than a fraction of a bar, surface temperatures vary with altitude because of the adiabatic cooling and warming of the atmosphere when it moves vertically. In most simulations, CO2 ice clouds cover a major part of the planet...

  9. Interactive Effects of Drought Stresses and Elevated CO2 Concentration on Photochemistry Efficiency of Cucumber Seedlings

    Institute of Scientific and Technical Information of China (English)

    Qing-Ming Li; Bin-Bin Liu; Yang Wu; Zhi-Rong Zou

    2008-01-01

    To reveal and quantify the interactive effects of drought stresses and elevated CO2 concentration [CO2] on photochemistry efficiency of cucumber seedlings, the portable chlorophyll meter was used to measure the chlorophyll content, and the Imaging-PAM was used to image the chlorophyll fluorescence parameters and rapid light response curves (RLC) of leaves in two adjacent greenhouses. The results showed that chlorophyll content of leaves was reduced significantly with drought stress aggravated. Minimal fluorescence (Fo) was increased while maximal quantum yield of PSII (Fv/Fm) decreased significantly by severe drought stress. The significant decrease of effective quantum yield of PSll (Y(Ⅱ)) accompanied by the significant increase of quantum yield of regulated energy dissipation (Y(NPQ)) was observed under severe drought stress condition, but there was no change of quantum yield of nonregulated energy dissipation (Y(NO)). We detected that the coefficient of photochemical quenching (Qp) decreased, and non-photochemical quenching (NPQ) increased significantly under severe drought stress. Furthermore, we found that maximum apparent electron transport rate (ETRmax) and saturating photosynthetically active radiation (PPFDsat) decreased significantly with drought stress aggravated. However, elevated [CO2] significantly increased FvlFm, Qp and PPFDsat, and decreased NPQ under all water conditions, although there were no significant effects on chlorophyll content, Fo, Y(Ⅱ), Y(NPQ), Y(NO) and ETRmax. Therefore, it is concluded that CO2-fertilized greenhouses or elevated atmospheric [CO2] in the future could be favorable for cucumber growth and development, and beneficial to alleviate the negative effects of drought stresses to a certain extent.

  10. Modeling post-combustion CO2 capture with amine solvents

    OpenAIRE

    Léonard, Grégoire; Heyen, Georges

    2010-01-01

    In order to avoid the emission of large amounts of greenhouse gas, CO2 capture in fossil fuel power plants and subsequent underground CO2 sequestration is studied. The capture occurs by reactive CO2 absorption into chemical solvent systems at moderate temperature (~50°C) followed by solvent regeneration at higher temperature (~120°C). So far, the most employed solvent for acid gas capture is monoethanolamine (MEA). One main drawback of this technology is the high energy consumption necessary ...

  11. Modeling forest C and N allocation responses to free-air CO2 enrichment

    Science.gov (United States)

    Luus, Kristina; De Kauwe, Martin; Walker, Anthony; Werner, Christian; Iversen, Colleen; McCarthy, Heather; Medlyn, Belinda; Norby, Richard; Oren, Ram; Zak, Donald; Zaehle, Sönke

    2015-04-01

    Vegetation allocation patterns and soil-vegetation partitioning of C and N are predicted to change in response to rising atmospheric concentrations of CO2. These allocation responses to rising CO2 have been examined at the ecosystem level through through free-air CO2 enrichment (FACE) experiments, and their global implications for the timing of progressive N limitation (PNL) and C sequestration have been predicted for ~100 years using a variety of ecosystem models. However, recent FACE model-data syntheses studies [1,2,3] have indicated that ecosystem models do not capture the 5-10 year site-level ecosystem allocation responses to elevated CO2. This may be due in part to the missing representation of the rhizosphere interactions between plants and soil biota in models. Ecosystem allocation of C and N is altered by interactions between soil and vegetation through the priming effect: as plant N availability diminishes, plants respond physiologically by altering their tissue allocation strategies so as to increase rates of root growth and rhizodeposition. In response, either soil organic material begins to accumulate, which hastens the onset of PNL, or soil microbes start to decompose C more rapidly, resulting in increased N availability for plant uptake, which delays PNL. In this study, a straightforward approach for representing rhizosphere interactions in ecosystem models was developed through which C and N allocation to roots and rhizodeposition responds dynamically to elevated CO2 conditions, modifying soil decomposition rates without pre-specification of the direction in which soil C and N accumulation should shift in response to elevated CO2. This approach was implemented in a variety of ecosystem models ranging from stand (G'DAY), to land surface (CLM 4.5, O-CN), to dynamic global vegetation (LPJ-GUESS) models. Comparisons against data from three forest FACE sites (Duke, Oak Ridge & Rhinelander) indicated that representing rhizosphere interactions allowed

  12. Influence of the concentration of CO2 and SO2 on the absorption of CO2 by a lithium orthosilicate-based absorbent.

    Science.gov (United States)

    Pacciani, R; Torres, J; Solsona, P; Coe, C; Quinn, R; Hufton, J; Golden, T; Vega, L F

    2011-08-15

    A novel, high temperature solid absorbent based on lithium orthosilicate (Li(4)SiO(4)) has shown promise for postcombustion CO(2) capture. Previous studies utilizing a clean, synthetic flue gas have shown that the absorbent has a high CO(2) capacity, >25 wt %, along with high absorption rates, lower heat of absorption and lower regeneration temperature than other solids such as calcium oxide. The current effort was aimed at evaluating the Li(4)SiO(4) based absorbent in the presence of contaminants found in typical flue gas, specifically SO(2), by cyclic exposure to gas mixtures containing CO(2), H(2)O (up to 25 vol. %), and SO(2) (up to 0.95 vol. %). In the absence of SO(2), a stable CO(2) capacity of ∼ 25 wt % over 25 cycles at 550 °C was achieved. The presence of SO(2), even at concentrations as low as 0.002 vol. %, resulted in an irreversible reaction with the absorbent and a decrease in CO(2) capacity. Analysis of SO(2)-exposed samples revealed that the absorbent reacted chemically and irreversibly with SO(2) at 550 °C forming Li(2)SO(4). Thus, industrial application would require desulfurization of flue gas prior to contacting the absorbent. Reactivity with SO(2) is not unique to the lithium orthosilicate material, so similar steps would be required for other absorbents that chemically react with SO(2).

  13. Impacts of increased atmospheric CO2 concentration on photosynthesis and growth of micro- and macro-algae.

    Science.gov (United States)

    Wu, HongYan; Zou, DingHui; Gao, KunShan

    2008-12-01

    Marine photosynthesis drives the oceanic biological CO(2) pump to absorb CO(2) from the atmosphere, which sinks more than one third of the industry-originated CO(2) into the ocean. The increasing atmospheric CO(2) and subsequent rise of pCO(2) in seawater, which alters the carbonate system and related chemical reactions and results in lower pH and higher HCO(3) (-) concentration, affect photosynthetic CO(2) fixation processes of phytoplanktonic and macroalgal species in direct and/or indirect ways. Although many unicellular and multicellular species can operate CO(2)-concentrating mechanisms (CCMs) to utilize the large HCO(3) (-) pool in seawater, enriched CO(2) up to several times the present atmospheric level has been shown to enhance photosynthesis and growth of both phytoplanktonic and macro-species that have less capacity of CCMs. Even for species that operate active CCMs and those whose photosynthesis is not limited by CO(2) in seawater, increased CO(2) levels can down-regulate their CCMs and therefore enhance their growth under light-limiting conditions (at higher CO(2) levels, less light energy is required to drive CCM). Altered physiological performances under high-CO(2) conditions may cause genetic alteration in view of adaptation over long time scale. Marine algae may adapt to a high CO(2) oceanic environment so that the evolved communities in future are likely to be genetically different from the contemporary communities. However, most of the previous studies have been carried out under indoor conditions without considering the acidifying effects on seawater by increased CO(2) and other interacting environmental factors, and little has been documented so far to explain how physiology of marine primary producers performs in a high-CO(2) and low-pH ocean.

  14. Impacts of increased atmospheric CO2 concentration on photosynthesis and growth of micro- and macro-algae

    Institute of Scientific and Technical Information of China (English)

    WU HongYan; ZOU DingHui; GAO KunShan

    2008-01-01

    Marine photosynthesis drives the oceanic biological CO2 pump to absorb CO2 from the atmosphere, which sinks more than one third of the industry-originated CO2 into the ocean. The increasing atmospheric CO2 and subsequent rise of pCO2 in seawater, which alters the carbonate system and related chemical reactions and results in lower pH and higher HCO3- concentration, affect photosynthetic CO2 fixation processes of phytoplanktonic and macroalgal species in direct and/or indirect ways. Although many unicellular and multicellular species can operate CO2-concentrating mechanisms (CCMs) to utilize the large HCO3- pool in seawater, enriched CO2 up to several times the present atmospheric level has been shown to enhance photosynthesis and growth of both phytoplanktonic and macro-species that have less capacity of CCMs. Even for species that operate active CCMs and those whose photosynthesis is not limited by CO2 in seawater, increased CO2 levels can down-regulate their CCMs and therefore enhance their growth under light-limiting conditions (at higher CO2 levels, less light energy is required to drive CCM). Altered physiological performances under high-CO2 conditions may cause genetic alteration in view of adaptation over long time scale. Marine algae may adapt to a high CO2 oceanic environment so that the evolved communities in future are likely to be genetically different from the contemporary communities. However, most of the previous studies have been carried out under indoor conditions without considering the acidifying effects on seawater by increased CO2 and other interacting environmental factors, and little has been documented so far to explain how physiology of marine primary producers performs in a high-CO2 and low-pH ocean.

  15. Impacts of increased atmospheric CO2 concentration on photosynthesis and growth of micro-and macro-algae

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Marine photosynthesis drives the oceanic biological CO2 pump to absorb CO2 from the atmosphere, which sinks more than one third of the industry-originated CO2 into the ocean. The increasing atmos-pheric CO2 and subsequent rise of pCO2 in seawater, which alters the carbonate system and related chemical reactions and results in lower pH and higher HCO3- concentration, affect photosynthetic CO2 fixation processes of phytoplanktonic and macroalgal species in direct and/or indirect ways. Although many unicellular and multicellular species can operate CO2-concentrating mechanisms (CCMs) to util-ize the large HCO3- pool in seawater, enriched CO2 up to several times the present atmospheric level has been shown to enhance photosynthesis and growth of both phytoplanktonic and macro-species that have less capacity of CCMs. Even for species that operate active CCMs and those whose photo-synthesis is not limited by CO2 in seawater, increased CO2 levels can down-regulate their CCMs and therefore enhance their growth under light-limiting conditions (at higher CO2 levels, less light energy is required to drive CCM). Altered physiological performances under high-CO2 conditions may cause genetic alteration in view of adaptation over long time scale. Marine algae may adapt to a high CO2 oceanic environment so that the evolved communities in future are likely to be genetically different from the contemporary communities. However, most of the previous studies have been carried out under indoor conditions without considering the acidifying effects on seawater by increased CO2 and other interacting environmental factors, and little has been documented so far to explain how physi-ology of marine primary producers performs in a high-CO2 and low-pH ocean.

  16. Effects of elevated temperature and CO2 concentration on photosynthesis of the alpine plants in Zoige Plateau, China

    Science.gov (United States)

    Zijuan, Zhou; Peixi, Su; Rui, Shi; Tingting, Xie

    2017-04-01

    Increasing temperature and carbon dioxide concentration are the important aspects of global climate change. Alpine ecosystem response to global change was more sensitive and rapid than other ecosystems. Increases in temperature and atmospheric CO2concentrations have strong impacts on plant physiology. Photosynthesis is the basis for plant growth and the decisive factor for the level of productivity, and also is a very sensitive physiological process to climate change. In this study, we examined the interactive effects of elevated temperature and atmospheric CO2 concentration on the light response of photosynthesis in two alpine plants Elymus nutans and Potentilla anserine, which were widely distributed in alpine meadow in the Zoige Plateau, China. We set up as follows: the control (Ta 20˚ C, CO2 380μmolṡmol-1), elevated temperature (Ta 25˚ C, CO2 380 μmolṡmol-1), elevated CO2 concentration (Ta 20˚ C, CO2 700μmolṡmol-1), elevated temperature and CO2 concentration (Ta 25˚ C, CO2 700μmolṡmol-1). The results showed that compared to P. anserine, E. nutans had a higher maximum net photosynthetic rate (Pnmax), light saturation point (LSP) and apparent quantum yield (AQY) in the control. Elevated temperature increased the Pnmaxand LSP values in P. anserine, while Pnmaxand LSP were decreased in E. nutans. Elevated CO2 increased the Pnmaxand LSP values in E. nutans and P. anserine, while the light compensation point (LCP) decreased; Elevated both temperature and CO2, the Pnmaxand LSP were all increased for E. nutans and P. anserine, but did not significantly affect AQY. We concluded that although elevated temperature had a photoinhibition for E. nutans, the interaction of short-term elevated CO2 concentration and temperature can improve the photosynthetic capacity of alpine plants. Key Words: elevated temperature; CO2 concentration; light response; alpine plants

  17. Carbon fluxes acclimate more strongly to elevated growth temperatures than to elevated CO2 concentrations in a northern conifer.

    Science.gov (United States)

    Kroner, Yulia; Way, Danielle A

    2016-08-01

    Increasing temperatures and atmospheric CO2 concentrations will affect tree carbon fluxes, generating potential feedbacks between forests and the global climate system. We studied how elevated temperatures and CO2 impacted leaf carbon dynamics in Norway spruce (Picea abies), a dominant northern forest species, to improve predictions of future photosynthetic and respiratory fluxes from high-latitude conifers. Seedlings were grown under ambient (AC, c. 435 μmol mol(-1) ) or elevated (EC, 750 μmol mol(-1) ) CO2 concentrations at ambient, +4 °C, or +8 °C growing temperatures. Photosynthetic rates (Asat ) were high in +4 °C/EC seedlings and lowest in +8 °C spruce, implying that moderate, but not extreme, climate change may stimulate carbon uptake. Asat , dark respiration (Rdark ), and light respiration (Rlight ) rates acclimated to temperature, but not CO2 : the thermal optimum of Asat increased, and Rdark and Rlight were suppressed under warming. In all treatments, the Q10 of Rlight (the relative increase in respiration for a 10 °C increase in leaf temperature) was 35% higher than the Q10 of Rdark , so the ratio of Rlight to Rdark increased with rising leaf temperature. However, across all treatments and a range of 10-40 °C leaf temperatures, a consistent relationship between Rlight and Rdark was found, which could be used to model Rlight in future climates. Acclimation reduced daily modeled respiratory losses from warm-grown seedlings by 22-56%. When Rlight was modeled as a constant fraction of Rdark , modeled daily respiratory losses were 11-65% greater than when using measured values of Rlight . Our findings highlight the impact of acclimation to future climates on predictions of carbon uptake and losses in northern trees, in particular the need to model daytime respiratory losses from direct measurements of Rlight or appropriate relationships with Rdark .

  18. 古大气CO2浓度重建方法技术研究现状%On Methods and Technologies for Reconstruction of Paleoatmospheric CO2 Concentration

    Institute of Scientific and Technical Information of China (English)

    王尹; 李祥辉; 刘玲

    2012-01-01

    温室气候引起的全球气候变暖越来越引起人们的关注,大气中不断上升的CO2浓度被认为是导致气候变暖的主要因素.地史时期大气CO2浓度变化与温室气候可能存在类似的关系,可提供参考,因而古大气CO2浓度重建是首要任务.总结近年来古大气CO2浓度重建的进展,重点介绍GEOCARB模型模拟、植物叶片气孔参数和同位素指针的方法和技术.GEOCARB模型是反映全球古大气CO2浓度长期变化的碳相关模型;气孔参数方法是使用气孔比例来估计古大气CO2浓度;同位素指针包括成壤碳酸盐、浮游植物有机质生物标记物、钙质浮游有孔虫、古苔藓植物等,其中成壤碳酸盐碳同位素方法使用最为广泛.国内只是在叶片参数研究方面有一些进展,古大气CO2浓度重建工作任重而道远.%It has been more and more paid attention to the globalclimate change caused by the warming greenhouse effect. And the increasing of atmospheric CO2 concentration is thought to be the main factor of global warming. There could be a similar linkage of CO2 concentration and greenhouse climate between modern and ancient analogues, for which the estimate of paleoatmospheric CO2 concentration is a first task to reconstruct ancient climate. Then, this paper aims to summarize the main methods and technologies of paleoatmospheric CO2 concentration estimate at the arts of states by analyses and synthetization of recent published references. So far, there are three main methods to reconstruct ancient atmospheric CO2 concentration. They are GEOCARB model, stomatal parameters of fossil plant, and isotopes proxy indicators. The GEOCARB model is an extremely carbon-model relevant, and has been established by Berner (1990s . -2000s), showing a long tendency for changes of ancient atmospheric CO2 concentration. The method of stomatal parameter of fossil plant is used to estimate the CO2 concentration by stomatal ratio, which is often

  19. Quantifying and reducing uncertainties in estimated soil CO2 fluxes with hierarchical data-model integration

    Science.gov (United States)

    Ogle, Kiona; Ryan, Edmund; Dijkstra, Feike A.; Pendall, Elise

    2016-12-01

    Nonsteady state chambers are often employed to measure soil CO2 fluxes. CO2 concentrations (C) in the headspace are sampled at different times (t), and fluxes (f) are calculated from regressions of C versus t based on a limited number of observations. Variability in the data can lead to poor fits and unreliable f estimates; groups with too few observations or poor fits are often discarded, resulting in "missing" f values. We solve these problems by fitting linear (steady state) and nonlinear (nonsteady state, diffusion based) models of C versus t, within a hierarchical Bayesian framework. Data are from the Prairie Heating and CO2 Enrichment study that manipulated atmospheric CO2, temperature, soil moisture, and vegetation. CO2 was collected from static chambers biweekly during five growing seasons, resulting in >12,000 samples and >3100 groups and associated fluxes. We compare f estimates based on nonhierarchical and hierarchical Bayesian (B versus HB) versions of the linear and diffusion-based (L versus D) models, resulting in four different models (BL, BD, HBL, and HBD). Three models fit the data exceptionally well (R2 ≥ 0.98), but the BD model was inferior (R2 = 0.87). The nonhierarchical models (BL and BD) produced highly uncertain f estimates (wide 95% credible intervals), whereas the hierarchical models (HBL and HBD) produced very precise estimates. Of the hierarchical versions, the linear model (HBL) underestimated f by 33% relative to the nonsteady state model (HBD). The hierarchical models offer improvements upon traditional nonhierarchical approaches to estimating f, and we provide example code for the models.

  20. Changes in the salinity tolerance of sweet pepper plants as affected by nitrogen form and high CO2 concentration.

    Science.gov (United States)

    Piñero, María C; Pérez-Jiménez, Margarita; López-Marín, Josefa; Del Amor, Francisco M

    2016-08-01

    The assimilation and availability of nitrogen in its different forms can significantly affect the response of primary productivity under the current atmospheric alteration and soil degradation. An elevated CO2 concentration (e[CO2]) triggers changes in the efficiency and efficacy of photosynthetic processes, water use and product yield, the plant response to stress being altered with respect to ambient CO2 conditions (a[CO2]). Additionally, NH4(+) has been related to improved plant responses to stress, considering both energy efficiency in N-assimilation and the overcoming of the inhibition of photorespiration at e[CO2]. Therefore, the aim of this work was to determine the response of sweet pepper plants (Capsicum annuum L.) receiving an additional supply of NH4(+) (90/10 NO3(-)/NH4(+)) to salinity stress (60mM NaCl) under a[CO2] (400μmolmol(-1)) or e[CO2] (800μmolmol(-1)). Salt-stressed plants grown at e[CO2] showed DW accumulation similar to that of the non-stressed plants at a[CO2]. The supply of NH4(+) reduced growth at e[CO2] when salinity was imposed. Moreover, NH4(+) differentially affected the stomatal conductance and water use efficiency and the leaf Cl(-), K(+), and Na(+) concentrations, but the extent of the effects was influenced by the [CO2]. An antioxidant-related response was prompted by salinity, the total phenolics and proline concentrations being reduced by NH4(+) at e[CO2]. Our results show that the effect of NH4(+) on plant salinity tolerance should be globally re-evaluated as e[CO2] can significantly alter the response, when compared with previous studies at a[CO2].

  1. Retrieval of Atmospheric CO2 Concentration above Clouds and Cloud Top Pressure from Airborne Lidar Measurements during ASCENDS Science Campaigns

    Science.gov (United States)

    Mao, J.; Ramanathan, A. K.; Rodriguez, M.; Allan, G. R.; Hasselbrack, W. E.; Abshire, J. B.; Riris, H.; Kawa, S. R.

    2014-12-01

    NASA Goddard is developing an integrated-path, differential absorption (IPDA) lidar approach to measure atmospheric CO2 concentrations from space as a candidate for NASA's ASCENDS (Active Sensing of CO2 Emissions over Nights, Days, and Seasons) mission. The approach uses pulsed lasers to measure both CO2 and O2 absorption simultaneously in the vertical path to the surface at a number of wavelengths across a CO2 line at 1572.335 nm and an O2 line doublet near 764.7 nm. Measurements of time-resolved laser backscatter profiles from the atmosphere allow the technique to estimate column CO2 and O2 number density and range to cloud tops in addition to those to the ground. This allows retrievals of CO2 column above clouds and cloud top pressure, and all-sky measurement capability from space. This additional information can be used to evaluate atmospheric transport processes and other remote sensing carbon data in the free atmosphere, improve carbon data assimilation in models and help global and regional carbon flux estimates. We show some preliminary results of this capability using airborne lidar measurements from the summers of 2011 and 2014 ASCENDS science campaigns. These show simultaneous retrievals of CO2 and O2 column densities for laser returns from low-level marine stratus clouds in the west coast of California. This demonstrates the supplemental capability of the future space carbon mission to measure CO2 above clouds, which is valuable particularly for the areas with persistent cloud covers, e.g, tropical ITCZ, west coasts of continents with marine layered clouds and southern ocean with highest occurrence of low-level clouds, where underneath carbon cycles are active but passive remote sensing techniques using the reflected short wave sunlight are unable to measure accurately due to cloud scattering effect. We exercise cloud top pressure retrieval from O2 absorption measurements during the flights over the low-level marine stratus cloud decks, which is one of

  2. 大气CO2浓度非均匀动态分布条件下的气候模拟%Climate simulation for dynamic heterogeneous distribution of atmospheric CO2 concentration

    Institute of Scientific and Technical Information of China (English)

    杨成荫; 王汉杰; 韩士杰; 赵苏璇

    2012-01-01

    利用现有大气本底站的大气CO2浓度观测信息,综合考虑不同经济区划与土地覆盖类型对应的CO2浓度差异及其季节变化规律,构建模式区域内以月为单位的网格化大气CO2浓度非均匀动态分布数据模型.由此数据模型驱动RegCM4-CLM3.5区域气候模式运行,对东亚区2000年3月-2009年2月之间的气候变化特征进行了模拟,进而对大气CO2浓度非均匀动态分布可能引起的区域气候效应进行了初步研究.结果表明:目前气候模式中CO2浓度的常态均匀分布假设可能将温室效应夸大了10%左右.对大气CO2浓度非均匀动态分布影响气温变化的可能机制进行研究表明:CO2的自身效应(改变大气透射率)并不是导致Exp2试验温度降低的主要原因.大气CO2浓度的变化影响了大气与植物胞间CO2分压差,陆地植被通过改变气孔阻力适应这种变化,气孔阻力的变化直接影响到植物与大气间水分的交换,这种作用一方面通过蒸发冷却改变环境温度,另一方面,蒸发水分改变了近地面层湿度,进而水汽扩散到空中影响低云的分布.冬季,植物处于非生长季,对大气CO2浓度变化响应微弱,湿度和低云变化不明显;夏季,植物生长旺盛,由CO2生理学强迫激发的云反馈效应强烈,其效果是使中低云趋于增加,进而减弱了到达对流层低层的太阳短波辐射,造成温室效应减弱.%Based on the baseline concentration data of atmospheric CO2 observed from the GAW stations, considering the heterogeneous distributional characteristics of CO2 concentration among different economic regions and land use types, this paper constitutes a dynamical heterogeneous atmospheric CO2 concentration data set that varies monthly within a regional climate model domain around China. By running the RegCM4-CLM3. 5 regional climate model with the dynamic heterogeneous CO2 concentration data set, the climate change characteristics of the East Asia

  3. Stochastic Modeling of CO2 Migrations and Chemical Reactions in Deep Saline Formations

    Science.gov (United States)

    Ni, C.; Lee, I.; Lin, C.

    2013-12-01

    correlation lengths in a Gaussian covariance model are varied in the MCS and the uncertainty of the CO2 and other chemical concentrations are evaluated based on 144 random realizations. In this study a constant injection rate of100Mt/year supercritical CO2 is applied in the bottom of CF. The continuous injection time is 20 years and the uncertainty results are evaluated at 100 years. By comparing with the case without small-scale variability simulation results show that the CO2 plume sizes in the horizontal direction increase from tens of meters to hundreds of meters when the variances of small-scale variability are varied from 1.0 to 4.0. The changes of correlation lengths (i.e., from 100m, 200m, to 400m) show small contribution on the size increases of CO2 plumes. Other uncertainties of chemical concentrations show behaviors similar to the CO2 plume patterns.

  4. Amelioration of boron toxicity in sweet pepper as affected by calcium management under an elevated CO2 concentration.

    Science.gov (United States)

    Piñero, María Carmen; Pérez-Jiménez, Margarita; López-Marín, Josefa; Del Amor, Francisco M

    2017-03-10

    We investigated B tolerance in sweet pepper plants (Capsicum annuun L.) under an elevated CO2 concentration, combined with the application of calcium as a nutrient management amelioration technique. The data show that high B affected the roots more than the aerial parts, since there was an increase in the shoot/root ratio, when plants were grown with high B levels; however, the impact was lessened when the plants were grown at elevated CO2, since the root FW reduction caused by excess B was less marked at the high CO2 concentration (30.9% less). Additionally, the high B concentration affected the membrane permeability of roots, which increased from 39 to 54% at ambient CO2 concentration, and from 38 to 51% at elevated CO2 concentration, producing a cation imbalance in plants, which was differentially affected by the CO2 supply. The Ca surplus in the nutrient solution reduced the nutritional imbalance in sweet pepper plants produced by the high B concentration, at both CO2 concentrations. The medium B concentration treatment (toxic according to the literature) did not result in any toxic effect. Hence, there is a need to review the literature on critical and toxic B levels taking into account increases in atmospheric CO2.

  5. Importance of fossil fuel emission uncertainties over Europe for CO2 modeling: model intercomparison

    Directory of Open Access Journals (Sweden)

    F. Delage

    2011-07-01

    Full Text Available Inverse modeling techniques used to quantify surface carbon fluxes commonly assume that the uncertainty of fossil fuel CO2 (FFCO2 emissions is negligible and that intra-annual variations can be neglected. To investigate these assumptions, we analyzed the differences between four fossil fuel emission inventories with spatial and temporal differences over Europe and their impact on the model simulated CO2 concentration. Large temporal flux variations characterize the hourly fields (~40 % and ~80 % for the seasonal and diurnal cycles, peak-to-peak and annual country totals differ by 10 % on average and up to 40 % for some countries (i.e., the Netherlands. These emissions have been prescribed to seven different transport models, resulting in 28 different FFCO2 concentrations fields. The modeled FFCO2 concentration time series at surface sites using time-varying emissions show larger seasonal cycles (+2 ppm at the Hungarian tall tower (HUN and smaller diurnal cycles in summer (−1 ppm at HUN than when using constant emissions. The concentration range spanned by all simulations varies between stations, and is generally larger in winter (up to ~10 ppm peak-to-peak at HUN than in summer (~5 ppm. The contribution of transport model differences to the simulated concentration std-dev is 2–3 times larger than the contribution of emission differences only, at typical European sites used in global inversions. These contributions to the hourly (monthly std-dev's amount to ~1.2 (0.8 ppm and ~0.4 (0.3 ppm for transport and emissions, respectively. First comparisons of the modeled concentrations with 14C-based fossil fuel CO2 observations show that the large transport differences still hamper a quantitative evaluation/validation of the emission inventories. Changes in the estimated monthly biosphere flux (Fbio over Europe, using two inverse modeling approaches, are relatively small (less that 5 % while changes in annual Fbio (up to ~0.15 % GtC yr−1 are only

  6. 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.

  7. Dual-Pump Coherent Anti-Stokes Raman Scattering Temperature and CO2 Concentration Measurements

    Science.gov (United States)

    Lucht, Robert P.; Velur-Natarajan, Viswanathan; Carter, Campbell D.; Grinstead, Keith D., Jr.; Gord, James R.; Danehy, Paul M.; Fiechtner, G. J.; Farrow, Roger L.

    2003-01-01

    Measurements of temperature and CO2 concentration using dual-pump coherent anti-Stokes Raman scattering, (CARS) are described. The measurements were performed in laboratory flames,in a room-temperature gas cell, and on an engine test stand at the U.S. Air Force Research Laboratory, Wright-Patterson Air Force Base. A modeless dye laser, a single-mode Nd:YAG laser, and an unintensified back-illuminated charge-coupled device digital camera were used for these measurements. The CARS measurements were performed on a single-laser-shot basis. The standard deviations of the temperatures and CO2 mole fractions determined from single-shot dual-pump CARS spectra in steady laminar propane/air flames were approximately 2 and 10% of the mean values of approximately 2000 K and 0.10, respectively. The precision and accuracy of single-shot temperature measurements obtained from the nitrogen part of the dual-pump CARS system were investigated in detail in near-adiabatic hydrogen/air/CO2 flames. The precision of the CARS temperature measurements was found to be comparable to the best results reported in the literature for conventional two-laser, single-pump CARS. The application of dual-pump CARS for single-shot measurements in a swirl-stabilized combustor fueled with JP-8 was also demonstrated.

  8. Photosynthetic response to variation in CO2 concentrations and temperature of four broad-leaved trees in Beijing region

    Institute of Scientific and Technical Information of China (English)

    Zhibo MA; Shengqing SHI; Qinyan MA; Yutao WANG; Xingliang LIU

    2008-01-01

    Responses of the photosynthetic characteris-tics to variation in CO2 concentration and temperature of Ginkgo biloba, Eucornmia ulmoides, Magnolia denudata and Tiliajaponica were measured during the peak growing season. The results show that the ambient CO2 concentra-tion could not meet the requirements for photosynthesis of these four species. The optimal temperatures for pho-tosynthesis were lower than the average daytime air tem-perature. Hence, the photosynthesis of these four species was restricted by the low CO2 concentration and high daytime air temperature at the time of measurement. Marked enhancements in the net photosynthetic rate were found in all four species when the CO2 concentration was doubled. When the dependency on CO2 and temperature were examined simultaneously, it was seen that for increased CO2 concentrations there was a shift in the optimum temperature for M. denudata and T. japonica towards higher temperatures. Due to their independence on CO2 concentrations, this trend could not be found in the G. biloba and E. ulmoides data sets. The stomatal con-ductance (Gs) was sensitive to a vapor pressure deficit (VPD) which in turn was sensitive to temperature. An increase in temperature would cause the VPD to increase and plants might be assumed to react by reducing their stomatal apertures. The effect on stomatal resistance would be most significant at high temperatures. The restriction to stomatal conductance for these four species would increase if CO2 concentrations were elevated at the same temperature.

  9. Responses of CO2 emission and pore water DOC concentration to soil warming and water table drawdown in Zoige Peatlands

    Science.gov (United States)

    Yang, Gang; Wang, Mei; Chen, Huai; Liu, Liangfeng; Wu, Ning; Zhu, Dan; Tian, Jianqing; Peng, Changhui; Zhu, Qiuan; He, Yixin

    2017-03-01

    Peatlands in Zoige Plateau contains more than half of peatland carbon stock in China. This part of carbon is losing with climate change through dissolved organic carbon (DOC) export and carbon dioxide (CO2) emissions, both of which are vulnerable to the environmental changes, especially on the Zoige Plateau with a pace of twice the observed rate of global climate warming. This research aimed to understand how climate change including soil warming, rainfall reduction and water table change affect CO2 emissions and whether the trends of changes in CO2 emission are consistent with those of pore water DOC concentration. A mesocosm experiment was designed to investigate the CO2 emission and pore water DOC during the growing seasons of 2009-2010 under scenarios of passive soil warming, 20% rainfall reduction and changes to the water table levels. The results showed a positive relationship between CO2 emission and DOC concentration. For single factor effect, we found no significant relationship between water table and CO2 emission or DOC concentration. However, temperature at 5 cm depth was found to have positive linear relationship with CO2 emission and DOC concentration. The combined effect of soil warming and rainfall reduction increased CO2 emission by 96.8%. It suggested that the drying and warming could stimulate potential emission of CO2. Extending this result to the entire peatland area in Zoige Plateau translates into 0.45 Tg CO2 emission per year over a growing season. These results suggested that the dryer and warmer Zoige Plateau will increase CO2 emission. We also found the contribution rate of DOC concentration to CO2 emission was increased by 12.1% in the surface layer and decreased by 13.8% in the subsurface layer with combined treatment of soil warming and rainfall reduction, which indicated that the warmer and dryer environmental conditions stimulate surface peat decomposition process.

  10. Effect of HCO3- concentration on CO2 corrosion in oil and gas fields

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The effect of HCO3- concentration on CO2 corrosion was investigated by polarization measurement of potentiodynamic scans and weight-loss method. Under the conditions of high pressure and high temperature, the corrosion rate of steel X65 decreased with the increase of HCO3- concentration, while pH of solution increased. SEM, EDS, and XRD results of the corrosion scales indicated that the typical FeCO3 crystallite was found at low HCO3- concentration but Ca(Fe,Mg)(CO3)2 was found at high HCO3 concentration. Ca2+ and Mg2+ are precipitated preferential to Fe2+ at high pH value. Potentiodynamic polarization curves showed that the cathodic current density decreases with the increase of HCO3- concentration at low HCO3- concentration. When the HCO3- concentration reaches 0.126 mol/L, increasing HCO3 concentration promotes cathodic reactions. Anodic behavior is an active process at low HCO3- concentration and the anodic current density decreases with the increase of HCO3- concentration. An evident active-passive behavior is exhibited in anodic process at 0.126 mol/L HCO3-.

  11. Low Temperature Performance of Selective Catalytic Reduction of NO with NH3 under a Concentrated CO2 Atmosphere

    Directory of Open Access Journals (Sweden)

    Xiang Gou

    2015-10-01

    Full Text Available Selective catalytic reduction of NOx with NH3 (NH3-SCR has been widely investigated to reduce NOx emissions from combustion processes, which cause environmental challenges. However, most of the current work on NOx reduction has focused on using feed gas without CO2 or containing small amounts of CO2. In the future, oxy-fuel combustion will play an important role for power generation, and this process generates high concentrations of CO2 in flue gas. Therefore, studies on the SCR process under concentrated CO2 atmosphere conditions are important for future SCR deployment in oxy-fuel combustion processes. In this work, Mn- and Ce-based catalysts using activated carbon as support were used to investigate the effect of CO2 on NO conversion. A N2 atmosphere was used for comparison. Different process conditions such as temperature, SO2 concentration, H2O content in the feed gas and space velocity were studied. Under Mn-Ce/AC conditions, the results suggested that Mn metal could reduce the inhibition effect of CO2 on the NO conversion, while Ce metal increased the inhibition effect of CO2. High space velocity also resulted in a reduction of CO2 inhibition on the NO conversion, although the overall performance of SCR was greatly reduced at high space velocity. Future investigations to design novel Mn-based catalysts are suggested to enhance the SCR performance under concentrated CO2 atmosphere conditions.

  12. Effect of Fe ion concentration on fatigue life of carbon steel in aqueous CO2 environment

    DEFF Research Database (Denmark)

    Rogowska, Magdalena; Gudme, J.; Rubin, A.

    2016-01-01

    In this work, the corrosion fatigue behaviour of steel armours used in the flexible pipes, in aqueous solutions initially containing different concentrations of Fe2+, was investigated by four-point bending testing under saturated 1 bar CO2 condition. Corrosion fatigue results were supported with ex...... of Fe2+ marginally above the solubility limit of FeCO3 compared to the samples tested in highly supersaturated solution of Fe2+. Results revealed that the impact of the alternating stresses on the corrosion behaviour of samples reduces with lowering the applied stresses. At the stress range of 100 MPa...

  13. Why CO2 cools the middle atmosphere - a consolidating model perspective

    Science.gov (United States)

    Goessling, Helge F.; Bathiany, Sebastian

    2016-08-01

    Complex models of the atmosphere show that increased carbon dioxide (CO2) concentrations, while warming the surface and troposphere, lead to lower temperatures in the stratosphere and mesosphere. This cooling, which is often referred to as "stratospheric cooling", is evident also in observations and considered to be one of the fingerprints of anthropogenic global warming. Although the responsible mechanisms have been identified, they have mostly been discussed heuristically, incompletely, or in combination with other effects such as ozone depletion, leaving the subject prone to misconceptions. Here we use a one-dimensional window-grey radiation model of the atmosphere to illustrate the physical essence of the mechanisms by which CO2 cools the stratosphere and mesosphere: (i) the blocking effect, associated with a cooling due to the fact that CO2 absorbs radiation at wavelengths where the atmosphere is already relatively opaque, and (ii) the indirect solar effect, associated with a cooling in places where an additional (solar) heating term is present (which on Earth is particularly the case in the upper parts of the ozone layer). By contrast, in the grey model without solar heating within the atmosphere, the cooling aloft is only a transient blocking phenomenon that is completely compensated as the surface attains its warmer equilibrium. Moreover, we quantify the relative contribution of these effects by simulating the response to an abrupt increase in CO2 (and chlorofluorocarbon) concentrations with an atmospheric general circulation model. We find that the two permanent effects contribute roughly equally to the CO2-induced cooling, with the indirect solar effect dominating around the stratopause and the blocking effect dominating otherwise.

  14. Concentration of soil CO2 as an indicator of the decalcification rate after liming treatment

    Science.gov (United States)

    Chmiel, Stanisław; Hałas, Stanisław; Głowacki, Sławomir; Sposób, Joanna; Maciejewska, Ewa; Trembaczowski, Andrzej

    2016-04-01

    This paper presents the results of investigation of decalcification of acid sandy and loamy sand soils by infiltration waters, and potential Ca-leaching after liming treatment. For this purpose, monthly measurements were made of the concentration of CO2 in the soil air, dissolved inorganic carbon in the soil waters, and their ionic composition. The determined dissolved inorganic carbon ranged from 5.9 to 10.6 mg dm-3 and from 9.9 to 16.5 mg dm-3 for the sandy and loamy sand soil, respectively. The Ca concentration in soil waters was determined as 5.9-12.4 mg dm-3 in sandy soil and 14.2-19.8 mg dm-3 in soil loamy sand. The calculated rate of decalcification amounted to 23.0 kg ha-1 year-1 in soil sandy and 19.4 kg ha-1 year-1 in loamy sand soil. The potential Ca-leaching is predicted as 124 kg ha-1 year-1 for S and 87 kg ha-1 year-1 for loamy sand soil. At the treatment level of 3 000 kg ha-1 4 year-1 of CaO, ~20% of the Ca-fertilizer can be leached after the liming treatment. The results of the CO2 concentration in the soil air may be useful in estimation of Ca-leaching from soils developed by slightly clayey sands and clayey sands in zones with a moderate climate.

  15. Modeling of CO2 Solubility in Aqueous Potassium Lysinate Solutions at Post-Combustion CO2 Capture Conditions

    Science.gov (United States)

    Bian, Y.; Shen, S.

    2017-05-01

    Aqueous potassium lysinate (LysK) has been proposed as an alternative to aqueous alkanolamines for CO2 capture due to fast kinetics and large absorption capacity. However, thermodynamic modeling for aqueous LysK system has not been available yet. In this work, a modified Kent-Eisenberg model with correlated equilibrium constants was developed to interpret the vapor-liquid equilibrium (VLE) data at postcombustion capture conditions. The predictions from the developed model are in good agreement with the experimental results with AAD within 19 %.

  16. [Effect of CO2 fertilization on residual concentration of cypermethrin in rhizosphere of C3 and C4 plant].

    Science.gov (United States)

    Mu, Nan; Diao, Xiao-Jun; Wang, Shu-Guang; Wang, Peng-Teng; Li, Pan-Feng

    2012-06-01

    In order to achieve sustainable economic and environmental development in China, CO2-emission reduction and phytoremediation of polluted soil must be resolved. According to the effect of biological carbon sequestration on rhizosphere microenvironment, we propose that phytoremediation of polluted soil can be enhanced by CO2 fertilization, and hope to provide information for resolving dilemma of CO2-emission reduction and phytoremediation technology. In this study, effects of CO2 fertilization on cypermethrin reduction in rhizosphere of C3-plant (bush bean) and C4-plant (maize) were investigated. Results showed that dry weight of shoot and root of bush bean (C3 plant) was increased by CO2 fertilization. Relative to ambient CO2, dry weight of root was increased by 54.3%, 31.9% and 30.0% in soil added with 0, 20 and 40 mg x kg(-1) cypermethrin respectively. Microbial biomass was increased by CO2 fertilization in rhizosphere soil added with 0 mg x kg(-1) cypermethrin, but negative effect was found in rhizosphere soil added with 20 and 40 mg x kg(-1) cypermethrin. CO2 fertilization slightly affected residual concentration of cypermethrin in rhizosphere soil added with 0 mg x kg(-1) cypermethrin, but significantly decreased residual concentration of cypermethrin as 24.0% and 16.9% in soil added with 20 and 40 mg x kg(-1) relative to ambient CO2. In maize plant, however, plant growth, microbial biomass and residual cypermethrin concentration in rhizosphere was slightly affected by CO2 fertilization, and even negative effect was observed. This study indicated that CO2 fertilization decreases the residual concentration of cypermethrin in rhizosphere of C3-plant, and it is possible to enhance phytoremediation of organic-polluted soil by C3-plant through CO2 fertilization. However, further study is needed for C4-plant.

  17. Solvation of CO2 in water: effect of RuBP on CO2 concentration in bundle sheath of C4 plants.

    Science.gov (United States)

    Sadhukhan, Tumpa; Latif, Iqbal A; Datta, Sambhu N

    2014-07-24

    An understanding of the temperature-dependence of solubility of carbon dioxide (CO2) in water is important for many industrial processes. Voluminous work has been done by both quantum chemical methods and molecular dynamics (MD) simulations on the interaction between CO2 and water, but a quantitative evaluation of solubility remains elusive. In this work, we have approached the problem by considering quantum chemically calculated total energies and thermal energies, and incorporating the effects of mixing, hydrogen bonding, and phonon modes. An overall equation relating the calculated free energy and entropy of mixing with the gas-solution equilibrium constant has been derived. This equation has been iteratively solved to obtain the solubility as functions of temperature and dielectric constant. The calculated solubility versus temperature plot excellently matches the observed plot. Solubility has been shown to increase with dielectric constant, for example, by addition of electrolytes. We have also found that at the experimentally reported concentration of enzyme RuBP in bundle sheath cells of chloroplast in C4 green plants, the concentration of CO2 can effectively increase by as much as a factor of 7.1-38.5. This stands in agreement with the observed effective rise in concentration by as much as 10 times.

  18. Effect of Different High CO2 Concentrations on the Development of 2-cell Mouse Embryos in vitro

    Institute of Scientific and Technical Information of China (English)

    Li-hua LU; Wei-jie ZHU

    2003-01-01

    Objective To investigate effects of different high CO2 concentrations on the development of 2-cell mouse embryos in vitroMethods At levels of 5% CO2 (control group), 5.7% CO2, 6.0% CO2 and 15% CO2, embryos were incubated in drops with CZB medium, respectively, and the drops were covered by paraffin oil which was treated with three-distilled water. In addition, at the level of 15% CO2, there were another two groups, in which paraffin oil was treated with phosphate-buffered saline (PBS) solution or the drops were uncovered. The development of embryos in all stages was noted.Results The developmental rates of blastocysts in five experimental groups were significantly lower than that of the control group (P0.05). At the level of 15% CO2, 15% embryos developed in the 4-cell stage with irregular blastomere and degenerated quickly in the group which paraffin oil was treated with distilled water; 2.2% embryos developed in the 4-cell stage in the group which paraffin oil was treated with PBS and the rest stagnated in the 2-cell stage. Conclusions High CO2 concentrations had toxic effect on the in vitro development of 2-cell mouse embryos, and was responsible for the inhibition of the embryos. It is important for the development of embryos in vitro to detect strictly CO2 concentration.

  19. Activities of carboxylating enzymes in the CAM species Opuntia ficus-indica grown under current and elevated CO2 concentrations.

    Science.gov (United States)

    Israel, A A; Nobel, P S

    1994-06-01

    Responses of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and phosphoenolpyruvate carboxylase (PEPCase) to an elevated atmospheric CO2 concentration were determined along with net CO2 uptake rates for the Crassulacean acid metabolism species Opuntia ficus-indica growing in open-top chambers. During the spring 13 months after planting, total daily net CO2 uptake of basal and first-order daughter cladodes was 28% higher at 720 than at 360 μl CO2 l(-1). The enhancement, caused mainly by higher CO2 assimilation during the early part of the night, was also observed during late summer (5 months after planting) and the following winter. The activities of Rubisco and PEPCase measured in vitro were both lower at the elevated CO2 concentration, particularly under the more favorable growth conditions in the spring and late summer. Enzyme activity in second-order daughter cladodes increased with cladode age, becoming maximal at 6 to 10 days. The effect ofelevated CO2 on Rubisco and PEPCase activity declined with decreasing irradiance, especially for Rubisco. Throughout the 13-month observation period, O. ficus-indica thus showed increased CO2 uptake when the atmospheric CO2 concentration was doubled despite lower activities of both carboxylating enzymes.

  20. Impacts of Elevated CO2 Concentration on Biochemical Composition,Carbonic Anhydrase, and Nitrate Reductase Activity of Freshwater Green Algae

    Institute of Scientific and Technical Information of China (English)

    Jian-Rong XIA; Kun-Shan GAO

    2005-01-01

    To investigate the biochemical response of freshwater green algae to elevated CO2 concentrations,Chlorella pyrenoidosa Chick and Chlamydomonas reinhardtii Dang cells were cultured at different CO2concentrations within the range 3-186 μmol/L and the biochemical composition, carbonic anhydrase (CA),and nitrate reductase activities of the cells were investigated. Chlorophylls (Chl), carotenoids, carbonhydrate,and protein contents were enhanced to varying extents with increasing CO2 concentration from 3-186μmol/L. The CO2 enrichment significantly increased the Chl a/Chl b ratio in Chlorella pyrenoidosa, but not in Chlamydomonas reinhardtii. The CO2 concentration had significant effects on CA and nitrate reductase activity. Elevating CO2 concentration to 186 μmol/L caused a decline in intracellular and extracellullar CA activity. Nitrate reductase activity, under either light or dark conditions, in C. reinhardtii and C. pyrenoidosa was also significantly decreased with CO2 enrichment. From this study, it can be concluded that CO2enrichment can affect biochemical composition, CA, and nitrate reductase activity, and that the biochemical response was species dependent.

  1. A data driven model for the impact of IFT and density variations on CO2 storage capacity in geologic formations

    Science.gov (United States)

    Nomeli, Mohammad A.; Riaz, Amir

    2017-09-01

    Carbon dioxide (CO2) storage in depleted hydrocarbon reservoirs and deep saline aquifers is one of the most promising solutions for decreasing CO2 concentration in the atmosphere. One of the important issues for CO2 storage in subsurface environments is the sealing efficiency of low-permeable cap-rocks overlying potential CO2 storage reservoirs. Though we focus on the effect of IFT in this study as a factor influencing sealing efficiency or storage capacity, other factors such as interfacial interactions, wettability, pore radius and interfacial mass transfer also affect the mobility and storage capacity of CO2 phase in the pore space. The study of the variation of IFT is however important because the pressure needed to penetrate a pore depends on both the pore size and the interfacial tension. Hence small variations in IFT can affect flow across a large population of pores. A novel model is proposed to find the IFT of the ternary systems (CO2/brine-salt) in a range of temperatures (300-373 K), pressures (50-250 bar), and up to 6 molal salinity applicable to CO2 storage in geological formations through a multi-variant non-linear regression of experimental data. The method uses a general empirical model for the quaternary system CO2/brine-salts that can be made to coincide with experimental data for a variety of solutions. We introduce correction parameters into the model, which compensates for uncertainties, and enforce agreement with experimental data. The results for IFT show a strong dependence on temperature, pressure, and salinity. The model has been found to describe the experimental data in the appropriate parameter space with reasonable precision. Finally, we use the new model to evaluate the effects of formation depth on the actual efficiency of CO2 storage. The results indicate that, in the case of CO2 storage in deep subsurface environments as a global-warming mitigation strategy, CO2 storage capacity increases with reservoir depth.

  2. Changing Amazon biomass and the role of atmospheric CO2 concentration, climate, and land use

    Science.gov (United States)

    Almeida Castanho, Andrea D.; Galbraith, David; Zhang, Ke; Coe, Michael T.; Costa, Marcos H.; Moorcroft, Paul

    2016-01-01

    The Amazon tropical evergreen forest is an important component of the global carbon budget. Its forest floristic composition, structure, and function are sensitive to changes in climate, atmospheric composition, and land use. In this study biomass and productivity simulated by three dynamic global vegetation models (Integrated Biosphere Simulator, Ecosystem Demography Biosphere Model, and Joint UK Land Environment Simulator) for the period 1970-2008 are compared with observations from forest plots (Rede Amazónica de Inventarios Forestales). The spatial variability in biomass and productivity simulated by the DGVMs is low in comparison to the field observations in part because of poor representation of the heterogeneity of vegetation traits within the models. We find that over the last four decades the CO2 fertilization effect dominates a long-term increase in simulated biomass in undisturbed Amazonian forests, while land use change in the south and southeastern Amazonia dominates a reduction in Amazon aboveground biomass, of similar magnitude to the CO2 biomass gain. Climate extremes exert a strong effect on the observed biomass on short time scales, but the models are incapable of reproducing the observed impacts of extreme drought on forest biomass. We find that future improvements in the accuracy of DGVM predictions will require improved representation of four key elements: (1) spatially variable plant traits, (2) soil and nutrients mediated processes, (3) extreme event mortality, and (4) sensitivity to climatic variability. Finally, continued long-term observations and ecosystem-scale experiments (e.g. Free-Air CO2 Enrichment experiments) are essential for a better understanding of the changing dynamics of tropical forests.

  3. Changing Amazon biomass and the role of atmospheric CO2 concentration, climate, and land use

    Science.gov (United States)

    de Almeida Castanho, Andrea D.; Galbraith, David; Zhang, Ke; Coe, Michael T.; Costa, Marcos H.; Moorcroft, Paul

    2016-01-01

    The Amazon tropical evergreen forest is an important component of the global carbon budget. Its forest floristic composition, structure, and function are sensitive to changes in climate, atmospheric composition, and land use. In this study biomass and productivity simulated by three dynamic global vegetation models (Integrated Biosphere Simulator, Ecosystem Demography Biosphere Model, and Joint UK Land Environment Simulator) for the period 1970-2008 are compared with observations from forest plots (Rede Amazónica de Inventarios Forestales). The spatial variability in biomass and productivity simulated by the DGVMs is low in comparison to the field observations in part because of poor representation of the heterogeneity of vegetation traits within the models. We find that over the last four decades the CO2 fertilization effect dominates a long-term increase in simulated biomass in undisturbed Amazonian forests, while land use change in the south and southeastern Amazonia dominates a reduction in Amazon aboveground biomass, of similar magnitude to the CO2 biomass gain. Climate extremes exert a strong effect on the observed biomass on short time scales, but the models are incapable of reproducing the observed impacts of extreme drought on forest biomass. We find that future improvements in the accuracy of DGVM predictions will require improved representation of four key elements: (1) spatially variable plant traits, (2) soil and nutrients mediated processes, (3) extreme event mortality, and (4) sensitivity to climatic variability. Finally, continued long-term observations and ecosystem-scale experiments (e.g. Free-Air CO2 Enrichment experiments) are essential for a better understanding of the changing dynamics of tropical forests.

  4. Effect of elevated atmospheric CO2 concentration on growth and leaf litter decomposition of Quercus acutissima and Fraxinus rhynchophylla.

    Science.gov (United States)

    Cha, Sangsub; Chae, Hee-Myung; Lee, Sang-Hoon; Shim, Jae-Kuk

    2017-01-01

    The atmospheric carbon dioxide (CO2) level is expected to increase substantially, which may change the global climate and carbon dynamics in ecosystems. We examined the effects of an elevated atmospheric CO2 level on the growth of Quercus acutissima and Fraxinus rhynchophylla seedlings. We investigated changes in the chemical composition of leaf litter, as well as litter decomposition. Q. acutissima and F. rhynchophylla did not show differences in dry weight between ambient CO2 and enriched CO2 treatments, but they exhibited different patterns of carbon allocation, namely, lower shoot/root ratio (S/R) and decreased specific leaf area (SLA) under CO2-enriched conditions. The elevated CO2 concentration significantly reduced the nitrogen concentration in leaf litter while increasing lignin concentrations and carbon/nitrogen (C/N) and lignin/N ratios. The microbial biomass associated with decomposing Q. acutissima leaf litter was suppressed in CO2 enrichment chambers, while that of F. rhynchophylla was not. The leaf litter of Q. acutissima from the CO2-enriched chambers, in contrast with F. rhynchophylla, contained much lower nutrient concentrations than that of the litter in the ambient air chambers. Consequently, poorer litter quality suppressed decomposition.

  5. Visible-light photoconductivity of Zn1-xCoxO and its dependence on Co2+ concentration

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Claire A.; Cohn, Alicia; Kaspar, Tiffany C.; Chambers, Scott A.; Salley, G. Mackay; Gamelin, Daniel R.

    2011-09-06

    Many metal oxides investigated for solar photocatalysis or photoelectrochemistry have band gaps that are too wide to absorb a sufficient portion of the solar spectrum. Doping with impurity ions has been extensively explored as a strategy to sensitize such oxides to visible light, but the electronic structures of the resulting materials are frequently complex and poorly understood. Here, we report a detailed photoconductivity investigation of the wide-gap II-VI semiconductor ZnO doped with Co2+ (Zn1-xCoxO), which responds to visible light in photoelectrochemical and photoconductivity experiments and thus represents a well-defined model system for understanding dopant-sensitized oxides. Variable-temperature scanning photoconductivity measurements have been performed on high-structural-quality Zn1-xCoxO epitaxial films to examine the relationship between dopant concentration (x) and visible-light photoconductivity, with particular focus on mid-gap d-d photoactivity. Excitation into the intense 4T1(P) d-d band at ~2.0 eV (620 nm) leads to Co2+/3+ ionization with a quantum efficiency that increases with decreasing cobalt concentration and increasing sample temperature. Both spontaneous and thermally assisted ionization from the Co2+ d-d excited state are found to become less effective as x is increased, attributed to an increasing conduction-band-edge potential. These trends counter the increasing light absorption with increasing x, explaining the experimental maximum in external photon-to-current conversion efficiencies at values well below the solid solubility of Co2+ in ZnO.

  6. Transcriptome response to elevated atmospheric CO2 concentration in the Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae

    Directory of Open Access Journals (Sweden)

    Wenjing Wu

    2016-10-01

    Full Text Available Background Carbon dioxide (CO2 is a pervasive chemical stimulus that plays a critical role in insect life, eliciting behavioral and physiological responses across different species. High CO2 concentration is a major feature of termite nests, which may be used as a cue for locating their nests. Termites also survive under an elevated CO2 concentration. However, the mechanism by which elevated CO2 concentration influences gene expression in termites is poorly understood. Methods To gain a better understanding of the molecular basis involved in the adaptation to CO2 concentration, a transcriptome of Coptotermes formosanus Shiraki was constructed to assemble the reference genes, followed by comparative transcriptomic analyses across different CO2 concentration (0.04%, 0.4%, 4% and 40% treatments. Results (1 Based on a high throughput sequencing platform, we obtained approximately 20 GB of clean data and revealed 189,421 unigenes, with a mean length and an N50 length of 629 bp and 974 bp, respectively. (2 The transcriptomic response of C. formosanus to elevated CO2 levels presented discontinuous changes. Comparative analysis of the transcriptomes revealed 2,936 genes regulated among 0.04%, 0.4%, 4% and 40% CO2 concentration treatments, 909 genes derived from termites and 2,027 from gut symbionts. Genes derived from termites appears selectively activated under 4% CO2 level. In 40% CO2 level, most of the down-regulated genes were derived from symbionts. (3 Through similarity searches to data from other species, a number of protein sequences putatively involved in chemosensory reception were identified and characterized in C. formosanus, including odorant receptors, gustatory receptors, ionotropic receptors, odorant binding proteins, and chemosensory proteins. Discussion We found that most genes associated with carbohydrate metabolism, energy metabolism, and genetic information processing were regulated under different CO2 concentrations. Results

  7. Reactive transport modeling of CO2 injection in the Farnsworth, Texas hydrocarbon field

    Science.gov (United States)

    Ahmmed, B.; Appold, M. S.; McPherson, B. J. O. L.; Grigg, R.; White, M. D.

    2014-12-01

    The Farnsworth hydrocarbon field in northern Texas has been an experimental site for CO2 sequestration and enhanced oil recovery for the U.S. Department of Energy-sponsored Southwest Partnership (SWP) since April, 2013. CO2 is to be injected into the Pennsylvanian Morrow Sandstone at a rate of 200,000 tonnes per year for at least five years. The Morrow is a quartz-rich sandstone that lies at a depth of about 2400 m. Pore water in the Morrow has a total dissolved solids content of about 3600 mg/L dominated by Na, Cl, bicarbonate, and Ca. A reactive solute transport model was constructed for a 1700 × 1700 × 95 m volume using the TOUGHREACT software and the ECO2N equation of state for aqueous brine and CO2. Simulations were carried out to 100 years. The results showed immiscible CO2 gas to be concentrated in a lateral plume extending radially from the well screen, its ascent impeded by vigorous lateral groundwater flow in the more permeable upper Morrow. CO2 was much more widespread in aqueous solution, lowering pH throughout much of the model volume after 100 years, to a minimum of about 4.7. The low reactivity of the Morrow Sandstone due to its quartz-rich matrix and dilute pore fluid resulted in little mineral precipitation or dissolution, with net volume changes for any mineral no higher than order 10-4. The simulations predicted net dissolution of albite, calcite, and chlorite, and net precipitation of dawsonite, illite, and magnesite. The Morrow matrix was predicted to undergo slight net dissolution overall, resulting in porosity increases of up to 0.01%, suggesting that the Morrow would be resistant to significant changes in hydraulic properties as a result of the proposed amount of CO2 injection. For the 100 year simulation times calculated thus far, only a small fraction of the injected CO2 would be sequestered as carbonate minerals, with most of the injected CO2 dissolved in the aqueous phase.

  8. The seasonal cycle amplitude of total column CO2: factors behind the model-observation mismatch

    NARCIS (Netherlands)

    Basu, S.; Houweling, S.; Peters, W.; Sweeney, C.; Machida, T.; Maksyutov, S.; Patra, P. K.; Saito, R.; Chevallier, F.; Niwa, Y.; Matsueda, H.; Sawa, Y.

    2011-01-01

    CO2 surface fluxes that are statistically consistent with surface layer measurements of CO2, when propagated forward in time by atmospheric transport models, underestimate the seasonal cycle amplitude of total column CO2 in the northern temperate latitudes by 1–2 ppm. In this paper we verify the sys

  9. Elevated atmospheric CO2 concentration alters the effect of phosphate supply on growth of Japanese red pine (Pinus densiflora) seedlings.

    Science.gov (United States)

    Kogawara, Satoshi; Norisada, Mariko; Tange, Takeshi; Yagi, Hisayoshi; Kojima, Katsumi

    2006-01-01

    We demonstrated that the inorganic phosphate (P(i)) requirement for growth of Japanese red pine (Pinus densiflora Sieb. & Zucc.) seedlings is increased by elevated CO(2) concentration ([CO(2)]) and that responses of the ectomycorrhizal fungus Pisolithus tinctorius (Pers.) Coker & Couch to P(i) supply are also altered. To investigate the growth response of non-mycorrhizal seedlings to P(i) supply in elevated [CO(2)], non-mycorrhizal seedlings were grown for 73 days in ambient or elevated [CO(2)] (350 or 700 micromol mol(-1)) with nutrient solutions containing one of seven phosphate concentrations (0, 0.02, 0.04, 0.06, 0.08, 0.10 and 0.20 mM). In ambient [CO(2)], the growth response to P(i) was saturated at about 0.1 mM P(i), whereas in elevated [CO(2)], the growth response to P(i) supply did not saturate, even at the highest P(i) supply (0.2 mM), indicating that the P(i) requirement is higher in elevated [CO(2)] than in ambient [CO(2)]. The increased requirement was due mainly to an altered shoot growth response to P(i) supply. The enhanced P(i) requirement in elevated [CO(2)] was not associated with a change in photosynthetic response to P(i) or a change in leaf phosphorus (P) status. We investigated the effect of P(i) supply (0.04, 0.08 and 0.20 mM) on the ectomycorrhizal fungus P. tinctorius in mycorrhizal seedlings grown in ambient or elevated [CO(2)]. Root ergosterol concentration (an indicator of fungal biomass) decreased with increasing P(i) supply in ambient [CO(2)], but the decrease was far less in elevated [CO(2)]. In ambient [CO(2)] the ratio of extramatrical mycelium to root biomass decreased with increasing P(i) supply but did not change in elevated [CO(2)]. We conclude that, because elevated [CO(2)] increased the P(i) requirement for shoot growth, the significance of the ectomycorrhizal association was also increased in elevated [CO(2)].

  10. Carbon allocation and element composition in four Chlamydomonas mutants defective in genes related to the CO2 concentrating mechanism.

    Science.gov (United States)

    Memmola, Francesco; Mukherjee, Bratati; Moroney, James V; Giordano, Mario

    2014-09-01

    Four mutants of Chlamydomonas reinhardtii with defects in different components of the CO2 concentrating mechanism (CCM) or in Rubisco activase were grown autotrophically at high pCO2 and then transferred to low pCO2, in order to study the role of different components of the CCM on carbon allocation and elemental composition. To study carbon allocation, we measured the relative size of the main organic pools by Fourier Transform Infrared spectroscopy. Total reflection X-ray fluorescence was used to analyze the elemental composition of algal cells. Our data show that although the organic pools increased their size at high CO2 in all strains, their stoichiometry was highly homeostatic, i.e., the ratios between carbohydrates and proteins, lipid and proteins, and carbohydrates and lipids, did not change significantly. The only exception was the wild-type 137c, in which proteins decreased relative to carbohydrates and lipids, when the cells were transferred to low CO2. It is noticeable that the two wild types used in this study responded differently to the transition from high to low CO2. Malfunctions of the CCM influenced the concentration of several elements, somewhat altering cell elemental stoichiometry: especially the C/P and N/P ratios changed appreciably in almost all strains as a function of the growth CO2 concentration, except in 137c and the Rubisco activase mutant rca1. In strain cia3, defective in the lumenal carbonic anhydrase (CA), the cell quotas of P, S, Ca, Mn, Fe, and Zn were about 5-fold higher at low CO2 than at high CO2. A Principle Components Analysis showed that, mostly because of its elemental composition, cia3 behaved in a substantially different way from all other strains, at low CO2. The lumenal CA thus plays a crucial role, not only for the correct functioning of the CCM, but also for element utilization. Not surprisingly, growth at high CO2 attenuated differences among strains.

  11. Supercritical CO2 Power Cycles: Design Considerations for Concentrating Solar Power

    Energy Technology Data Exchange (ETDEWEB)

    Neises, Ty; Turchi, Craig

    2014-09-01

    A comparison of three supercritical CO2 Brayton cycles: the simple cycle, recompression cycle and partial-cooling cycle indicates the partial-cooling cycle is favored for use in concentrating solar power (CSP) systems. Although it displays slightly lower cycle efficiency versus the recompression cycle, the partial-cooling cycle is estimated to have lower total recuperator size, as well as a lower maximum s-CO2 temperature in the high-temperature recuperator. Both of these effects reduce recuperator cost. Furthermore, the partial-cooling cycle provides a larger temperature differential across the turbine, which translates into a smaller, more cost-effective thermal energy storage system. The temperature drop across the turbine (and by extension, across a thermal storage system) for the partial-cooling cycle is estimated to be 23% to 35% larger compared to the recompression cycle of equal recuperator conductance between 5 and 15 MW/K. This reduces the size and cost of the thermal storage system. Simulations by NREL and Abengoa Solar indicate the partial-cooling cycle results in a lower LCOE compared with the recompression cycle, despite the former's slightly lower cycle efficiency. Advantages of the recompression cycle include higher thermal efficiency and potential for a smaller precooler. The overall impact favors the use of a partial-cooling cycle for CSP compared to the more commonly analyzed recompression cycle.

  12. Development of a low cost and low power consumption system for monitoring CO_{2} soil concentration in volcanic areas.

    Science.gov (United States)

    Awadallah Estévez, Shadia; Moure-García, David; Torres-González, Pedro; Acosta Sánchez, Leopoldo; Domínguez Cerdeña, Itahiza

    2017-04-01

    Volatiles dissolved in magma are released as gases when pressure or stress conditions change. H2O, CO2, SO2 and H2S are the most abundant gases involved in volcanic processes. Emission rates are related to changes in the volcanic activity. Therefore, in order to predict possible eruptive events, periodic measurements of CO2 concentrations from the soil should be carried out. In the last years, CO2 monitoring has been widespread for many reasons. A direct relationship between changes in volcanic activity and variations in concentration, diffuse flux and isotope ratios of this gas, have been observed prior to some eruptions or unrest processes. All these factors have pointed out the fact that CO2 emission data are crucial in volcanic monitoring programs. In addition, relevant instrumentation development has also taken place: improved accuracy, cost reduction and portability. Considering this, we propose a low cost and a low power consumption system for measuring CO2 concentration in the soil based on Arduino. Through a perforated pick-axe buried at a certain depth, gas samples are periodically taken with the aid of a piston. These samples are injected through a pneumatic circuit in the spectrometer, which measures the CO2 concentration. Simultaneously, the system records the following meteorological parameters: atmospheric pressure, precipitation, relative humidity and air and soil temperature. These parameters are used to correct their possible influence in the CO2 soil concentration. Data are locally stored (SD card) and transmitted via GPRS or WIFI to a data analysis center.

  13. Spatial variations in daily average CO2 concentrations above wetland surface of Xianghai National Nature Reserve, China

    Institute of Scientific and Technical Information of China (English)

    BAI Jun-hong; OUYANG Hua; WANG Qing-gai; ZHOU Cai-ping; XU Xiao-feng

    2005-01-01

    Horizontal and vertical variations of daily average CO2 concentration above the wetland surface were studied in Xianghai National Nature Reserve of China in August, 2000. The primary purpose was to study spatial distribution characteristics of CO2 concentration on the four levels of height(0. 1 m, 0.6 m, 1.2 m and 2 m) and compare the differences of CO2 concentration under different land covers. Results showed that daily average CO2 concentration above wetland surface in Xianghai National Natural Reserve was lower than that above other wetlands in northeast China as well as the worldwide average, suggesting that Xianghai wetland absorbed CO2 in August and acted as"sink" of CO2. The horizontal variations on the four levels of height along the latitude were distinct, and had the changing tendency of"decreasing after increasing" with the increase of height. The areas with obvious variations were consistent on different levels of height,and those with the highest variations appeared above surface of shore, sloping field, Typha wetland and Phragmites wetland; the vertical variations were greatly different, with the higher variations in Phragmites wetland and Typha wetland, and the lands near the shore and the sloping field with the lower variations. Spatial variations of daily average CO2 concentrations above wetland surface were affected by surface qualities and land covers.

  14. Impact of elevated CO2 concentration on dynamics of leaf photosynthesis in Fagus sylvatica is modulated by sky conditions.

    Science.gov (United States)

    Urban, Otmar; Klem, Karel; Holišová, Petra; Šigut, Ladislav; Šprtová, Mirka; Teslová-Navrátilová, Petra; Zitová, Martina; Špunda, Vladimír; Marek, Michal V; Grace, John

    2014-02-01

    It has been suggested that atmospheric CO2 concentration and frequency of cloud cover will increase in future. It remains unclear, however, how elevated CO2 influences photosynthesis under complex clear versus cloudy sky conditions. Accordingly, diurnal changes in photosynthetic responses among beech trees grown at ambient (AC) and doubled (EC) CO2 concentrations were studied under contrasting sky conditions. EC stimulated the daily sum of fixed CO2 and light use efficiency under clear sky. Meanwhile, both these parameters were reduced under cloudy sky as compared with AC treatment. Reduction in photosynthesis rate under cloudy sky was particularly associated with EC-stimulated, xanthophyll-dependent thermal dissipation of absorbed light energy. Under clear sky, a pronounced afternoon depression of CO2 assimilation rate was found in sun-adapted leaves under EC compared with AC conditions. This was caused in particular by stomata closure mediated by vapour pressure deficit.

  15. Reduction of CO 2 concentration in a zinc/air battery by absorption in a rotating packed bed

    Science.gov (United States)

    Cheng, Hsu-Hsiang; Tan, Chung-Sung

    The reduction of CO 2 concentration in a gas stream containing 500 ppm of CO 2 by a technique combining chemical absorption with Higee (high gravity) was investigated in this study. Using a 2.0 L aqueous amine-based solution to treat the feed gas with a flow rate which varied from 12.9 to 20.6 L min -1, piperazine (PZ) was found to be more effective than 2-(2-aminoethylamino) ethanol (AEEA) and monoethanolamine (MEA) for reducing the CO 2 concentration to a level below 20 ppm. The effects of temperature, rotating speed, amine solution flow rate, and gas flow rate on the removal efficiency of CO 2 were systematically examined. The results indicated that the proposed compact device could effectively reduce CO 2 to a level below 20 ppm, as required by a zinc/air battery, for a long period of time using PZ and its mixture with AEEA and MEA as the absorbents.

  16. A multi-scale model for CO2 sequestration enhanced coalbed methane recovery

    Institute of Scientific and Technical Information of China (English)

    G.X.WANG; X.R.WEI; V.RUDOLPH; C.T.WEI; Y.QIN

    2009-01-01

    This paper presents a multi-scale model to simulate the multicomponent gas diffusion and flow in bulk coals for CO2 sequestration enhanced coalbed methane recovery. The model is developed based on a bi-dispersed structure model by assuming that coal con-sists of microporous micro-particles, meso/macro-pores and open microfractures. The bi-disperse diffusion theory and the Maxwell-Stefan approach were incorporated in the model, providing an improved simulation of the CH4-CO2/CH4-N2 counter diffusion dynamics. In the model,the counter diffusion process is numerically coupled with the flow of the mixture gases occurring within macro-pores or fractures in coal so as to account for the interaction between diffusion and flow in gas transport through coals.The model was validated by both experimental data from literature and our CO2 flush tests, and shows an excellent agreement with the experiments. The results reveal that the gas diffusivities, in particular the micro-pore diffusivities are strongly concentration-dependent.

  17. Spatial and temporal distribution characteristics of near-surface CO2 concentration over China based on GOSAT data

    Science.gov (United States)

    Zhao, Jing; Cui, Weihong; Sun, Yunhua

    2014-11-01

    To study the spatial and temporal distribution characteristics of near-surface CO2 concentration over China, the data of GOSAT L4B and auxiliary data of Mt Waliguan background observations, population density, total energy consumption (coal) and GDP in 2009 were applied to this study. The ArcGIS Geostatistical Analytical Method was used. The ground-based validation was processed by comparing GOSAT data with Mt Waliguan background observations. The variation characteristics of the near-surface CO2 concentration over China was analysed spatially and temporally. The results show that: GOSAT retrieved near-surface products are consistent with Mt Waliguan ground-based measurement; Near-surface CO2 concentration over China is relatively concentrated, and has significant differences between the East and the West, with a overall characteristic that CO2 concentration in the east of China is high and in the west is low; Near-surface CO2 concentration over China has a significant seasonal variation characteristic, and the monthly average concentration rise to the highest value of 396.512 ppmv in April (spring), which is significantly higher than other seasons, decline to the lowest value of 382.781 ppmv in July (summer); All relationships illustrate a big uncertainty, resulting a conclusion that the reasons causing the spatial distribution of near-surface CO2 concentration may be varied, could not be easily determined as anthropogenic or natural ressons, which need further study.

  18. Effects of elevated CO2 concentration on growth and water usage of tomato seedlings under different ammonium/nitrate ratios

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Increasing atmospheric CO2 concentration is generally expected to enhance photosynthesis and growth of agricultural C3 vegetable crops,and therefore results in an increase in crop yield.However,little is known about the combined effect of elevated CO2 and N species on plant growth and development.Two growth-chamber experiments were conducted to determine the effects of NH4+/NO3- ratio and elevated CO2 concentration on the physiological development and water use of tomato seedlings.Tomato was grown for 45 d in containers with nutrient solutions varying in NH4+/NO3- ratios and CO2 concentrations in growth chambers.Results showed that plant height,stem thickness,total dry weight,dry weight of the leaves,stems and roots,G value (total plant dry weight/seedling days),chlorophyll content,photosynthetic rate,leaf-level and whole plant-level water use efficiency and cumulative water consumption of tomato seedlings were increased with increasing proportion of NO3- in nutrient solutions in the elevated CO2 treatment.Plant biomass,plant height,stem thickness and photosynthetic rate were 67%,22%,24% and 55% higher at elevated CO2 concentration than at ambient CO2 concentration,depending on the values of NH4+/NO3- ratio.These results indicated that elevating CO2 concentration did not mitigate the adverse effects of 100% NH4+-N (in nutrient solution) on the tomato seedlings.At both CO2 levels,NH4+/NO3- ratios of nutrient solutions strongly influenced almost every measure of plant performance,and nitrate-fed plants attained a greater biomass production,as compared to ammonium-fed plants.These phenomena seem to be related to the coordinated regulation of photosynthetic rate and cumulative water consumption of tomato seedlings.

  19. The sensitivity of stand-scale photosynthesis and transpiration to changes in atmospheric CO2 concentration and climate

    Directory of Open Access Journals (Sweden)

    B. Kruijt

    1999-01-01

    Full Text Available The 3-dimensional forest model MAESTRO was used to simulate daily and annual photosynthesis and transpiration fluxes of forest stands and the sensitivity of these fluxes to potential changes in atmospheric CO2 concentration ([CO2], temperature, water stress and phenology. The effects of possible feed-backs from increased leaf area and limitations to leaf nutrition were simulated by imposing changes in leaf area and nitrogen content. Two different tree species were considered: Picea sitchensis (Bong. Carr., a conifer with long needle longevity and large leaf area, and Betula pendula Roth., a broad-leaved deciduous species with an open canopy and small leaf area. Canopy photosynthetic production in trees was predicted to increase with atmospheric [CO2] and length of the growing season and to decrease with increased water stress. Associated increases in leaf area increased production further only in the B. pendula canopy, where the original leaf area was relatively small. Assumed limitations in N uptake affected B. pendula more than P. sitchensis. The effect of increased temperature was shown to depend on leaf area and nitrogen content. The different sensitivities of the two species were related to their very different canopy structure. Increased [CO2] reduced transpiration, but larger leaf area, early leaf growth, and higher temperature all led to increased water use. These effects were limited by feedbacks from soil water stress. The simulations suggest that, with the projected climate change, there is some increase in stand annual `water use efficiency', but the actual water losses to the atmosphere may not always decrease.

  20. The sensitivity of stand-scale photosynthesis and transpiration to changes in atmospheric CO2 concentration and climate

    Science.gov (United States)

    Kruijt, B.; Barton, C.; Rey, A.; Jarvis, P. G.

    The 3-dimensional forest model MAESTRO was used to simulate daily and annual photosynthesis and transpiration fluxes of forest stands and the sensitivity of these fluxes to potential changes in atmospheric CO2 concentration ([CO2]), temperature, water stress and phenology. The effects of possible feed-backs from increased leaf area and limitations to leaf nutrition were simulated by imposing changes in leaf area and nitrogen content. Two different tree species were considered: Picea sitchensis (Bong.) Carr., a conifer with long needle longevity and large leaf area, and Betula pendula Roth., a broad-leaved deciduous species with an open canopy and small leaf area. Canopy photosynthetic production in trees was predicted to increase with atmospheric [CO2] and length of the growing season and to decrease with increased water stress. Associated increases in leaf area increased production further only in the B. pendula canopy, where the original leaf area was relatively small. Assumed limitations in N uptake affected B. pendula more than P. sitchensis. The effect of increased temperature was shown to depend on leaf area and nitrogen content. The different sensitivities of the two species were related to their very different canopy structure. Increased [CO2] reduced transpiration, but larger leaf area, early leaf growth, and higher temperature all led to increased water use. These effects were limited by feedbacks from soil water stress. The simulations suggest that, with the projected climate change, there is some increase in stand annual `water use efficiency', but the actual water losses to the atmosphere may not always decrease.

  1. Fast cloud adjustment to increasing CO2 in a superparameterized climate model

    Science.gov (United States)

    Wyant, Matthew C.; Bretherton, Christopher S.; Blossey, Peter N.; Khairoutdinov, Marat

    2012-05-01

    Two-year simulation experiments with a superparameterized climate model, SP-CAM, are performed to understand the fast tropical (30S-30N) cloud response to an instantaneous quadrupling of CO2 concentration with SST held fixed at present-day values. The greenhouse effect of the CO2 perturbation quickly warms the tropical land surfaces by an average of 0.5 K. This shifts rising motion, surface precipitation, and cloud cover at all levels from the ocean to the land, with only small net tropical-mean cloud changes. There is a widespread average reduction of about 80 m in the depth of the trade inversion capping the marine boundary layer (MBL) over the cooler subtropical oceans. One apparent contributing factor is CO2-enhanced downwelling longwave radiation, which reduces boundary-layer radiative cooling, a primary driver of turbulent entrainment through the trade inversion. A second contributor is a slight CO2-induced heating of the free troposphere above the MBL, which strengthens the trade inversion and also inhibits entrainment. There is a corresponding downward displacement of MBL clouds with a very slight decrease in mean cloud cover and albedo. Two-dimensional cloud-resolving model (CRM) simulations of this MBL response are run to steady state using composite SP-CAM simulated thermodynamic and wind profiles from a representative cool subtropical ocean regime, for the control and 4xCO2 cases. Simulations with a CRM grid resolution equal to that of SP-CAM are compared with much finer resolution simulations. The coarse-resolution simulations maintain a cloud fraction and albedo comparable to SP-CAM, but the fine-resolution simulations have a much smaller cloud fraction. Nevertheless, both CRM configurations simulate a reduction in inversion height comparable to SP-CAM. The changes in low cloud cover and albedo in the CRM simulations are small, but both simulations predict a slight reduction in low cloud albedo as in SP-CAM.

  2. 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

  3. 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.

  4. Extended UNIQUAC model for thermodynamic modeling of CO2 absorption in aqueous alkanolamine solutions

    DEFF Research Database (Denmark)

    Faramarzi, Leila; Kontogeorgis, Georgios; Thomsen, Kaj

    2009-01-01

    The extended UNIQUAC model [K. Thomsen, R Rasmussen, Chem. Eng. Sci. 54 (1999) 1787-1802] was applied to the thermodynamic representation of carbon dioxide absorption in aqueous monoethanolamine (MEA), methyldiethanolamine (MDEA) and varied strength mixtures of the two alkanolamines (MEA-MDEA). F......The extended UNIQUAC model [K. Thomsen, R Rasmussen, Chem. Eng. Sci. 54 (1999) 1787-1802] was applied to the thermodynamic representation of carbon dioxide absorption in aqueous monoethanolamine (MEA), methyldiethanolamine (MDEA) and varied strength mixtures of the two alkanolamines (MEA......) are included in the parameter estimation process. The previously unavailable standard state properties of the alkanolamine ions appearing in this work, i.e. MEA protonate, MEA carbamate and MDEA protonate are determined. The concentration of the species in both MEA and MDEA solutions containing CO2...

  5. CO32- concentration and pCO2 thresholds for calcification and dissolution on the Molokai reef flat, Hawaii

    Science.gov (United States)

    Yates, K.K.; Halley, R.B.

    2006-01-01

    The severity of the impact of elevated atmospheric pCO2 to coral reef ecosystems depends, in part, on how sea-water pCO2 affects the balance between calcification and dissolution of carbonate sediments. Presently, there are insufficient published data that relate concentrations of pCO 2 and CO32- to in situ rates of reef calcification in natural settings to accurately predict the impact of elevated atmospheric pCO2 on calcification and dissolution processes. Rates of net calcification and dissolution, CO32- concentrations, and pCO2 were measured, in situ, on patch reefs, bare sand, and coral rubble on the Molokai reef flat in Hawaii. Rates of calcification ranged from 0.03 to 2.30 mmol CaCO3 m-2 h-1 and dissolution ranged from -0.05 to -3.3 mmol CaCO3 m-2 h-1. Calcification and dissolution varied diurnally with net calcification primarily occurring during the day and net dissolution occurring at night. These data were used to calculate threshold values for pCO2 and CO32- at which rates of calcification and dissolution are equivalent. Results indicate that calcification and dissolution are linearly correlated with both CO32- and pCO2. Threshold pCO2 and CO32- values for individual substrate types showed considerable variation. The average pCO2 threshold value for all substrate types was 654??195 ??atm and ranged from 467 to 1003 ??atm. The average CO32- threshold value was 152??24 ??mol kg-1, ranging from 113 to 184 ??mol kg-1. Ambient seawater measurements of pCO2 and CO32- indicate that CO32- and pCO2 threshold values for all substrate types were both exceeded, simultaneously, 13% of the time at present day atmospheric pCO2 concentrations. It is predicted that atmospheric pCO2 will exceed the average pCO2 threshold value for calcification and dissolution on the Molokai reef flat by the year 2100.

  6. CO32- concentration and pCO2 thresholds for calcification and dissolution on the Molokai reef flat, Hawaii

    Science.gov (United States)

    Yates, K. K.; Halley, R. B.

    2006-07-01

    The severity of the impact of elevated atmospheric pCO2 to coral reef ecosystems depends, in part, on how seawater pCO2 affects the balance between calcification and dissolution of carbonate sediments. Presently, there are insufficient published data that relate concentrations of pCO2 and CO32- to in situ rates of reef calcification in natural settings to accurately predict the impact of elevated atmospheric pCO2 on calcification and dissolution processes. Rates of net calcification and dissolution, CO32- concentrations, and pCO2 were measured, in situ, on patch reefs, bare sand, and coral rubble on the Molokai reef flat in Hawaii. Rates of calcification ranged from 0.03 to 2.30 mmol CaCO3 m-2 h-1 and dissolution ranged from -0.05 to -3.3 mmol CaCO3 m-2 h-1. Calcification and dissolution varied diurnally with net calcification primarily occurring during the day and net dissolution occurring at night. These data were used to calculate threshold values for pCO2 and CO32- at which rates of calcification and dissolution are equivalent. Results indicate that calcification and dissolution are linearly correlated with both CO32- and pCO2. Threshold pCO2 and CO32- values for individual substrate types showed considerable variation. The average pCO2 threshold value for all substrate types was 654±195 μatm and ranged from 467 to 1003 μatm. The average CO32- threshold value was 152±24 μmol kg-1, ranging from 113 to 184 μmol kg-1. Ambient seawater measurements of pCO2 and CO32- indicate that CO32- and pCO2 threshold values for all substrate types were both exceeded, simultaneously, 13% of the time at present day atmospheric pCO2 concentrations. It is predicted that atmospheric pCO2 will exceed the average pCO2 threshold value for calcification and dissolution on the Molokai reef flat by the year 2100.

  7. CO32− concentration and pCO2 thresholds for calcification and dissolution on the Molokai reef flat, Hawaii

    Directory of Open Access Journals (Sweden)

    K. K. Yates

    2006-01-01

    Full Text Available The severity of the impact of elevated atmospheric pCO2 to coral reef ecosystems depends, in part, on how seawater pCO2 affects the balance between calcification and dissolution of carbonate sediments. Presently, there are insufficient published data that relate concentrations of pCO2 and CO32− to in situ rates of reef calcification in natural settings to accurately predict the impact of elevated atmospheric pCO2 on calcification and dissolution processes. Rates of net calcification and dissolution, CO32− concentrations, and pCO2 were measured, in situ, on patch reefs, bare sand, and coral rubble on the Molokai reef flat in Hawaii. Rates of calcification ranged from 0.03 to 2.30 mmol CaCO3 m−2 h−1 and dissolution ranged from –0.05 to –3.3 mmol CaCO3 m−2 h−1. Calcification and dissolution varied diurnally with net calcification primarily occurring during the day and net dissolution occurring at night. These data were used to calculate threshold values for pCO2 and CO32− at which rates of calcification and dissolution are equivalent. Results indicate that calcification and dissolution are linearly correlated with both CO32− and pCO2. Threshold pCO2 and CO32− values for individual substrate types showed considerable variation. The average pCO2 threshold value for all substrate types was 654±195 μatm and ranged from 467 to 1003 μatm. The average CO32− threshold value was 152±24 μmol kg−1, ranging from 113 to 184 μmol kg−1. Ambient seawater measurements of pCO2 and CO32− indicate that CO32− and pCO2 threshold values for all substrate types were both exceeded, simultaneously, 13% of the time at present day atmospheric pCO2 concentrations. It is predicted that atmospheric pCO2 will exceed the average pCO2 threshold value for calcification and dissolution on the Molokai reef flat by the year 2100.

  8. Effects of different CO2 concentration on growth and photosynthetic of rain tree plants (Albizia saman jacq.Merr)

    Science.gov (United States)

    Fathurrahman, F.; Nizam, M. S.; Wan Juliana, W. A.; Doni, Febri; NorLailatul, W. M.; Che Radziah, C. M. Z.

    2016-11-01

    A preliminary study was conducted to determine the effect of elevated carbon dioxide (CO2) in rain tree growth under controllable growth chamber. The tolerance towards CO2 absorption in the photosynthesis process for the growth of tree rain is still unknown. In this study, rain tree seedlings were incubated for three months in a growth chamber with three different CO2 concentration treatment: GC1 (300 ppm), GC2 (600 ppm) and GC3 (900 ppm) at similar condition of temperature (28°C), humidity (60%) and lighting (1200 lux). The results showed that increased CO2 significantly increase the growth rate and chlorophyll content in rain tree. The results of this study add to the further understanding of how the improvement of the growth and physiological characteristics of rain tree was affected by CO2 enrichment treatment. This research can for used for global warming mitigation in the future.

  9. Measurement of Lower-Atmospheric CO2 Concentration Distribution Using a Compact 1.6 μm DIAL

    Science.gov (United States)

    Shibata, Yasukuni; Nagasawa, Chikao; Abo, Makoto

    2016-06-01

    Knowledge of present carbon sources and sinks including their spatial distribution and their variation in time is one of the essential information for predicting future CO2 atmospheric concentration levels. The differential absorption lidar (DIAL) is expected to measure atmospheric CO2 profiles in the atmospheric boundary layer and lower troposphere from a ground platform. We have succeeded to develop a compact 1.6 μm DIAL system for measuring CO2 concentration profiles in the lower atmosphere. This 1.6 μm DIAL system consists of the optical parametric generator (OPG) transmitter that excited by the LD pumped Nd:YAG laser with high repetition rate and the receiving optics that included the near-infrared photomultiplier tube operating at the analog mode and a 25 cm telescope. CO2 concentration profiles were obtained up to 2.5 km altitude.

  10. Los Angeles megacity: a high-resolution land-atmosphere modelling system for urban CO2 emissions

    Science.gov (United States)

    Feng, Sha; Lauvaux, Thomas; Newman, Sally; Rao, Preeti; Ahmadov, Ravan; Deng, Aijun; Díaz-Isaac, Liza I.; Duren, Riley M.; Fischer, Marc L.; Gerbig, Christoph; Gurney, Kevin R.; Huang, Jianhua; Jeong, Seongeun; Li, Zhijin; Miller, Charles E.; O'Keeffe, Darragh; Patarasuk, Risa; Sander, Stanley P.; Song, Yang; Wong, Kam W.; Yung, Yuk L.

    2016-07-01

    Megacities are major sources of anthropogenic fossil fuel CO2 (FFCO2) emissions. The spatial extents of these large urban systems cover areas of 10 000 km2 or more with complex topography and changing landscapes. We present a high-resolution land-atmosphere modelling system for urban CO2 emissions over the Los Angeles (LA) megacity area. The Weather Research and Forecasting (WRF)-Chem model was coupled to a very high-resolution FFCO2 emission product, Hestia-LA, to simulate atmospheric CO2 concentrations across the LA megacity at spatial resolutions as fine as ˜ 1 km. We evaluated multiple WRF configurations, selecting one that minimized errors in wind speed, wind direction, and boundary layer height as evaluated by its performance against meteorological data collected during the CalNex-LA campaign (May-June 2010). Our results show no significant difference between moderate-resolution (4 km) and high-resolution (1.3 km) simulations when evaluated against surface meteorological data, but the high-resolution configurations better resolved planetary boundary layer heights and vertical gradients in the horizontal mean winds. We coupled our WRF configuration with the Vulcan 2.2 (10 km resolution) and Hestia-LA (1.3 km resolution) fossil fuel CO2 emission products to evaluate the impact of the spatial resolution of the CO2 emission products and the meteorological transport model on the representation of spatiotemporal variability in simulated atmospheric CO2 concentrations. We find that high spatial resolution in the fossil fuel CO2 emissions is more important than in the atmospheric model to capture CO2 concentration variability across the LA megacity. Finally, we present a novel approach that employs simultaneous correlations of the simulated atmospheric CO2 fields to qualitatively evaluate the greenhouse gas measurement network over the LA megacity. Spatial correlations in the atmospheric CO2 fields reflect the coverage of individual measurement sites when a

  11. Controle de Sitophilus zeamais Mots. através de diferentes concentrações de CO2 e O2 Control of Sitophilus zeamais Mots with different concentrations of CO2 and O2

    Directory of Open Access Journals (Sweden)

    Jerson Vanderlei Carús Guedes

    1996-08-01

    Full Text Available Instalou-se um experimento com objetivo de avaliar o efeito de diferentes concentrações dos gases: CO2 e O2 balanceado com N, no controle de Sitophilus zeamais. Utilizou-se parcelas subdivididas no tempo com parcela principal distribuída segundo o delineamento inteiramente casualizado com quatro repetições. A unidade experimental constou de um vidro com volume de cinco litros, onde estavam acondicionados 0,15 kg de milho desinfestado e 200 insetos adultos não sexados. Foram avaliadas oito concentrações de gases (tratamentos: 0,03% de CO2 e 21% de O2 (testemunha, 10% de CO2 e 16% de O2, 15% CO2 e 16% O2, 20% CO2 e 16% O2, 0% CO2 e 5% O2, 0% CO2 e 1% O2, 75% CO2 e 5% O2, e 12% CO2 e 8% O2. Os resultados demonstraram que 20% de CO2 controla totalmente os insetos em cinco dias. Tratamento com 15% de CO2 associado com 5% de O2, controla a totalidade dos insetos após dez dias. Concentração de 1% O2, sem adição de CO2, também controla 100% da população de Sitophilus zeamais. após 15 dias.This experiment was carried out aiming to evaluate the effect of different CO2 and 0(2 concentrations on the contral of Sitophilus zeamais. The experimental design was a split-plot in time, with the main plot distribucted in a completly randomized design, with four replications. The plot was consisted of a 5-liter glass chamber, in which 0.15 kg of desinfected maize with 200 unsexed adults insects. Eight gas concentrations were avaluated: 0.03% of CO2 and 21% of O2 (control, 10% of CO2 and 16% of O2, 15% of CO2 and 16% of O2, 20% of CO2 and 16% of O2, 0% of CO2 and 5% of O2, 0% of CO2 and 1% of O2, 15% of CO2 and 5% of O2 and 12% of CO2 and 8% of O2. Results demonstrated that 20% of CO2 controlled the insects in five days. Treatment with 15% of CO2 and 5% of 0(2 controlled 100% of insects in 10 days and 0% of CO2 and 1% of O2 controlled in 15 days.

  12. Technical note: Evaluation of three machine learning models for surface ocean CO2 mapping

    Science.gov (United States)

    Zeng, Jiye; Matsunaga, Tsuneo; Saigusa, Nobuko; Shirai, Tomoko; Nakaoka, Shin-ichiro; Tan, Zheng-Hong

    2017-04-01

    Reconstructing surface ocean CO2 from scarce measurements plays an important role in estimating oceanic CO2 uptake. There are varying degrees of differences among the 14 models included in the Surface Ocean CO2 Mapping (SOCOM) inter-comparison initiative, in which five models used neural networks. This investigation evaluates two neural networks used in SOCOM, self-organizing maps and feedforward neural networks, and introduces a machine learning model called a support vector machine for ocean CO2 mapping. The technique note provides a practical guide to selecting the models.

  13. Removal of high concentration CO2 from natural gas at elevated pressure via absorption process in packed column

    Institute of Scientific and Technical Information of China (English)

    L.S.Tan; K.K.Lau; M.A.Bustam; A.M.Shariff

    2012-01-01

    Carbon dioxide (CO2) removal is an essential step in natural gas (NG) processing to provide high quality gas stream products and minimize operational difficulties.This preliminary study aims to investigate the removal of CO2 at high concentration level from the mixture of CO2-NG gas stream at elevated pressure via absorption process.This is to explore the possibility of exploring high CO2 content natural gas reserves by treatment at offshore platform.A mixed amine solvent,Stonvent-Ⅱ,was used for the absorption of approximately 75 vol% CO2 in CO2-NG stream at a pressure of 10 barg.The initial solvent temperature was varied in order to study the impact of initial temperature on the absorption performance.Preliminary study at temperatures of 35 ℃ and 45 ℃ indicates that Stonvent-Ⅱ was able to perform almost 100% removal of CO2 under both conditions.However,the CO2 absorption effect took place faster when the initial liquid temperature was lower.This is because when the initial liquid temperature is high,the temperature increase in the packing bed caused by the reaction heat is high which impacts the efficiency of absorption negatively.

  14. Modelling distribution of evaporating CO2 in parallel minichannels

    DEFF Research Database (Denmark)

    Brix, Wiebke; Kærn, Martin Ryhl; Elmegaard, Brian

    2010-01-01

    -known empirical correlations for calculating frictional pressure drop and heat transfer coefficients. An investigation of different correlations for boiling two-phase flow shows that the choice of correlation is insignificant regarding the overall results. It is shown that non-uniform airflow leads...... to maldistribution of the refrigerant and considerable capacity reduction of the evaporator. Uneven inlet ualities to the different channels show only minor effects on the refrigerant distribution and evaporator capacity as long as the channels are vertically oriented with CO2 flowing upwards. For horizontal...

  15. A model for estimating CO2 solubility in aqueous alkanolamines

    DEFF Research Database (Denmark)

    Gabrielsen, Jostein; Michelsen, Michael Locht; Stenby, Erling Halfdan

    2005-01-01

    Partial pressures of carbon dioxide (CO2) over aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), and N-methyldiethanolamine (MDEA) have been correlated using a simple approach where only one chemical equilibrium reaction is taken into account and assuming ideal gas and ideal liquid...... properties. The approach combines the Henry's law constant and the chemical reaction equilibrium constant for the formation of carbamate for primary and secondary alkanolamines (MEA, DEA) or bicarbonate for tertiary alkanolamines(MDEA), resulting in an explicit expression for calculating the partial pressure...

  16. Regional modelling of water and CO2-fluxes with a one-dimensional SVAT model

    Science.gov (United States)

    Kuhnert, M.; Köstner, B.

    2009-04-01

    Climate change affects site conditions for vegetation and may affect changes in the distribution of plant species. Investigations of these effects are difficult, because other influences on plant performance like land use and management also need to be considered. Carbon gain can be used as a sensitive indicator for changes in the vitality of the considered vegetation types that are affected by different climate and weather patterns. The objective of the presented study is the quantification of net photosynthesis rate, respiration and transpiration of different vegetation types on the regional scale. The study regions are the Weißeritz catchment in the Ore Mountains and the region Torgau-Oschatz in the Elbe basin both located in Saxony (East Germany) but significantly differing in elevation and site conditions. The carbon and water fluxes are simulated by an ecophysiological based Soil-Vegetation-Atmosphere-Transfer model for three periods (1996-2006, 2015-2025 and 2035-2045). The considered vegetation types are forest and grassland. The used model SVAT-CN is a multi-layer model, which enables the calculation of hourly carbon gain by coupling micrometerological data with ecophysiological processes. The calculations are based on the equations of Farquhar and Ball for net photosynthesis rate and stomata conductivity, respectively. It is a one-dimensional model which also considers soil water processes. The soil is coupled with the vegetation by one factor that depends on the matric potential and steers the calculation of the stomata conductivity. The equations of the soil water processes are based on a combination of bucket model and Richard's equation. Simulations are based on measured weather data (Dept. of Meteorology at Technische Universität Dresden and LfL Sachsen) with varying levels of atmospheric CO2 concentrations up to 580 ppm. Further, climate projections (ECHAM5-OM, IPCC emission scenario A1B), with downscaling to a 18x18km grid by the regional climate

  17. Effect of compressed CO2 on the critical micelle concentration and aggregation number of AOT reverse micelles in isooctane.

    Science.gov (United States)

    Chen, Jing; Zhang, Jianling; Han, Buxing; Feng, Xiaoying; Hou, Minqiang; Li, Wenjing; Zhang, Zhaofu

    2006-10-25

    The effect of compressed CO2 on the critical micelle concentration (cmc) and aggregation number of sodium bis-2-ethylhexylsulfosuccinate (AOT) reverse micelles in isooctane solution was studied by UV/Vis and fluorescence spectroscopy methods in the temperature range of 303.2-318.2 K and at different pressures or mole fractions of CO2 (X(CO2)). The capacity of the reverse micelles to solubilize water was also determined by direct observation. The standard Gibbs free energy (DeltaGo(m)), standard enthalpy (DeltaHo(m)), and standard entropy (DeltaSo(m)) for the formation of the reverse micelles were calculated by using the cmc data determined. It was discovered that the cmc versus X(CO2) curve and the DeltaGo(m) versus X(CO2) curve for a fixed temperature have a minimum, and the aggregation number and water-solubilization capacity of the reverse micelles reach a maximum at the X(CO2) value corresponding to that minimum. These results indicate that CO2 at a suitable concentration favors the formation of and can stabilize AOT reverse micelles. A detailed thermodynamic study showed that the driving force for the formation of the reverse micelles is entropy.

  18. European source and sink areas of CO2 retrieved from Lagrangian transport model interpretation of combined O2 and CO2 measurements at the high alpine research station Jungfraujoch

    Directory of Open Access Journals (Sweden)

    D. Brunner

    2011-08-01

    Full Text Available The University of Bern monitors carbon dioxide (CO2 and oxygen (O2 at the High Altitude Research Station Jungfraujoch since the year 2000 by means of flasks sampling and since 2005 using a continuous in situ measurement system. This study investigates the transport of CO2 and O2 towards Jungfraujoch using backward Lagrangian Particle Dispersion Model (LPDM simulations and utilizes CO2 and O2 signatures to classify air masses. By investigating the simulated transport patterns associated with distinct CO2 concentrations it is possible to decipher different source and sink areas over Europe. The highest CO2 concentrations, for example, were observed in winter during pollution episodes when air was transported from Northeastern Europe towards the Alps, or during south Foehn events with rapid uplift of polluted air from Northern Italy, as demonstrated in two case studies. To study the importance of air-sea exchange for variations in O2 concentrations at Jungfraujoch the correlation between CO2 and APO (Atmospheric Potential Oxygen deviations from a seasonally varying background was analyzed. Anomalously high APO concentrations were clearly associated with air masses originating from the Atlantic Ocean, whereas low APO concentrations were found in air masses advected either from the east from the Eurasian continent in summer, or from the Eastern Mediterranean in winter. Those air masses with low APO in summer were also strongly depleted in CO2 suggesting a combination of CO2 uptake by vegetation and O2 uptake by dry summer soils. Other subsets of points in the APO-CO2 scatter plot investigated with respect to air mass origin included CO2 and APO background values and points with regular APO but anomalous CO2 concentrations. Background values were associated with free tropospheric air masses with little contact with the boundary layer during the last few days, while high or low CO2 concentrations reflect the various levels of influence of anthropogenic

  19. Numerical modeling of cold magmatic CO2 flux measurements for the exploration of hidden geothermal systems

    Science.gov (United States)

    Peiffer, Loïc.; Wanner, Christoph; Pan, Lehua

    2015-10-01

    The most accepted conceptual model to explain surface degassing of cold magmatic CO2 in volcanic-geothermal systems involves the presence of a gas reservoir. In this study, numerical simulations using the TOUGH2-ECO2N V2.0 package are performed to get quantitative insights into how cold CO2 soil flux measurements are related to reservoir and fluid properties. Although the modeling is based on flux data measured at a specific geothermal site, the Acoculco caldera (Mexico), some general insights have been gained. Both the CO2 fluxes at the surface and the depth at which CO2 exsolves are highly sensitive to the dissolved CO2 content of the deep fluid. If CO2 mainly exsolves above the reservoir within a fracture zone, the surface CO2 fluxes are not sensitive to the reservoir size but depend on the CO2 dissolved content and the rock permeability. For gas exsolution below the top of the reservoir, surface CO2 fluxes also depend on the gas saturation of the deep fluid as well as the reservoir size. The absence of thermal anomalies at the surface is mainly a consequence of the low enthalpy of CO2. The heat carried by CO2 is efficiently cooled down by heat conduction and to a certain extent by isoenthalpic volume expansion depending on the temperature gradient. Thermal anomalies occur at higher CO2 fluxes (>37,000 g m-2 d-1) when the heat flux of the rising CO2 is not balanced anymore. Finally, specific results are obtained for the Acoculco area (reservoir depth, CO2 dissolved content, and gas saturation state).

  20. Estimation of CO2 Transport Costs in South Korea Using a Techno-Economic Model

    Directory of Open Access Journals (Sweden)

    Kwangu Kang

    2015-03-01

    Full Text Available In this study, a techno–economic model was used to calculate the costs of CO2 transport and specify the major equipment required for transport in order to demonstrate and implement CO2 sequestration in the offshore sediments of South Korea. First, three different carbon capture and storage demonstration scenarios were set up involving the use of three CO2 capture plants and one offshore storage site. Each transport scenario considered both the pipeline transport and ship transport options. The temperature and pressure conditions of CO2 in each transport stage were determined from engineering and economic viewpoints, and the corresponding specifications and equipment costs were calculated. The transport costs for a 1 MtCO2/year transport rate were estimated to be US$33/tCO2 and US$28/tCO2 for a pipeline transport of ~530 km and ship transport of ~724 km, respectively. Through the economies of scale effect, the pipeline and ship transport costs for a transport rate of 3 MtCO2/year were reduced to approximately US$21/tCO2 and US$23/tCO2, respectively. A CO2 hub terminal did not significantly reduce the cost because of the short distance from the hub to the storage site and the small number of captured sources.

  1. Using Carbonyl Sulfide column measurements and a Chemical Transport Model to investigate variability in biospheric CO2 fluxes

    Science.gov (United States)

    Wang, Yuting; Petri, Christof; Palm, Mathias; Warneke, Thorsten; Baker, Ian; Berry, Joe; Suntharalingam, Parvadha; Campbell, Elliott; Wolf, Adam; Deutscher, Nick; Notholt, Justus

    2015-04-01

    Understanding the CO2 processes on land is of great importance, because the terrestrial exchange drives the seasonal and interannual variability of CO2 in the atmosphere. Atmospheric inversions based on CO2 concentration measurements alone can only determine net biosphere fluxes, but not differentiate between photosynthesis (uptake) and respiration (production). Carbonyl sulfide (OCS) could provide an important additional constraint: it is also taken up by plants during photosynthesis but not emitted during respiration, and therefore is a potential means to differentiate between these processes. Solar absorption Fourier Transform InfraRed (FTIR) spectrometry allows for the retrieval of the atmospheric concentrations of both CO2 and OCS. Here, we investigate co-located and nearly simultaneous measurements of OCS and CO2 measured at 3 sites via FTIR spectrometers. These northern-hemispheric sites span a wide range of latitudes and all have multiple year time-series. The sites include Ny-Alesund (79°N), Bremen (53°N) and Paramaribo (6°N). We compare these measurements to simulations of OCS and CO2 using the GEOS-Chem model. The simulations are driven by different land biospheric fluxes of OCS and CO2 to match the seasonality of the measurements. The simple biosphere model (SiB-COS) are used in the study because it simultaneously calculates the biospheric fluxes of both OCS and CO2. The CO2 simulation with SiB fluxes agrees with the measurements better than a simulation using CASA. Comparison of the OCS simulations with different fluxes indicates that the latitudinal distribution of the OCS fluxes within SiB needs to be adjusted.

  2. Low Temperature Performance of Selective Catalytic Reduction of NO with NH3 under a Concentrated CO2 Atmosphere

    OpenAIRE

    Xiang Gou; Chunfei Wu; Kai Zhang; Guoyou Xu; Meng Si; Yating Wang; Enyu Wang; Liansheng Liu; Jinxiang Wu

    2015-01-01

    Selective catalytic reduction of NOx with NH3 (NH3-SCR) has been widely investigated to reduce NOx emissions from combustion processes, which cause environmental challenges. However, most of the current work on NOx reduction has focused on using feed gas without CO2 or containing small amounts of CO2. In the future, oxy-fuel combustion will play an important role for power generation, and this process generates high concentrations of CO2 in flue gas. Therefore, studies on the SCR process unde...

  3. Modeling approaches to describe H2O and CO2 exchange in mare ecosystems

    Science.gov (United States)

    Olchev, A.; Novenko, E.; Volkova, E.

    2012-04-01

    The modern climatic conditions is strongly influenced by both internal variability of climatic system, and various external natural and anthropogenic factors (IPCC 2007). Significant increase of concentration of greenhouse gases in the atmosphere and especially the growth of atmospheric CO2 due to human activity are considered as the main factors that are responsible for global warming and climate changes. A significant part of anthropogenic CO2 is absorbed from the atmosphere by land biota and especially by vegetation cover. However, it is still not completely clear what is the role of different land ecosystems and especially forests and mares in global cycles of H2O and CO2 and what is a sensitivity of these ecosystems to climate changes. Within the frameworks of this study the spatial and temporal variability of H2O and CO2 fluxes in different types of mare ecosystems of the forest-steppe zone in European part of Russia was described using modeling approaches and results of field measurements. For this modeling and experimental study the mare ecosystems of Tula region were selected. The Tula region is located mostly in the forest-steppe zone and it is unique area for such studies because almost all existed types of mare ecosystems of Northern Eurasia distinguished by a geomorphological position, water and mineral supply can be found there. Most mares in Tula region have a relatively small size and surrounded by very heterogeneous forests that make not possible an application of the classical measuring and modeling approaches e.g. an eddy covariance technique or one-dimensional H2O and CO2 exchange models for flux estimation in such sites. In our study to describe the radiation, sensible heat, H2O and CO2 exchange between such heterogeneous mare ecosystems and the atmosphere a three-dimensional model Forbog-3D and one-dimensional Mixfor-SVAT were applied. The main concept used in the Forbog-3D and Mixfor-SVAT models is an aggregated description of physical and

  4. The Effect of Shaking, CO2 Concentration and Light Intensity on Biomass Growth of Green Microalgae Desmodesmus communis

    Directory of Open Access Journals (Sweden)

    J. Vanags

    2015-01-01

    Full Text Available There are many factors that can affect microalgae growth. In this research, four different groups of experiments were set up in order to determine the influence of different mixing conditions, CO2 concentration and light intensities on Desmodesmus communis growth. The range of CO2 concentration in the air - CO2 mixture was 0–16 v/v%, light intensities ranged between 100 µmol m-2s-1 and 300 µmol m-2s-1. The best biomass productivity and biomass yield of 0.54 g d-1 and 3.53 g l-1 respectively were achieved when mixing was provided by using shaker as well as gas bubbling with air - CO2 mixture of 96:4 v/v% and light intensity of 300 µmol m-2s-1. DOI: http://dx.doi.org/10.5755/j01.erem.70.4.8437

  5. Experimental Investigation and Simplistic Geochemical Modeling of CO2 Mineral Carbonation Using the Mount Tawai Peridotite

    Directory of Open Access Journals (Sweden)

    Omeid Rahmani

    2016-03-01

    Full Text Available In this work, the potential of CO2 mineral carbonation of brucite (Mg(OH2 derived from the Mount Tawai peridotite (forsterite based (Mg2SiO4 to produce thermodynamically stable magnesium carbonate (MgCO3 was evaluated. The effect of three main factors (reaction temperature, particle size, and water vapor were investigated in a sequence of experiments consisting of aqueous acid leaching, evaporation to dryness of the slurry mass, and then gas-solid carbonation under pressurized CO2. The maximum amount of Mg converted to MgCO3 is ~99%, which occurred at temperatures between 150 and 175 °C. It was also found that the reduction of particle size range from >200 to <75 µm enhanced the leaching rate significantly. In addition, the results showed the essential role of water vapor in promoting effective carbonation. By increasing water vapor concentration from 5 to 10 vol %, the mineral carbonation rate increased by 30%. This work has also numerically modeled the process by which CO2 gas may be sequestered, by reaction with forsterite in the presence of moisture. In both experimental analysis and geochemical modeling, the results showed that the reaction is favored and of high yield; going almost to completion (within about one year with the bulk of the carbon partitioning into magnesite and that very little remains in solution.

  6. Modeling the convective stability of CO2 sequestration by a discontinuous and unstably stratified density profile

    Science.gov (United States)

    Wanstall, Taber; Hadji, Layachi

    2016-11-01

    The convective stability associated with carbon sequestration is modeled by adopting an unstably stratified basic profile having a step function density with top heavy carbon saturated layer overlying a lighter carbon free layer. The model takes into account the anisotropy in both permeability and carbon dioxide diffusion, and chemical reactions between the CO2 rich brine and host mineralogy. We carry out a linear stability analysis to derive the instability threshold parameters for a variety of CO2 boundary conditions. We solve for the minimum thickness of the carbon-rich layer at which convection sets in and quantify how its value is influenced by diffusion, anisotropy, permeability, reaction and type of boundary conditions. The discontinuity leads to convective concentration contours that have the shape of an asymmetric lens which we quantify by deriving and making use of the CO2 flux expressions at the interface. The linear problem is extended to the nonlinear regime, the analysis of which leads to the determination of a uniformly valid super critical steady solution.

  7. Global Monthly CO2 Flux Inversion Based on Results of Terrestrial Ecosystem Modeling

    NARCIS (Netherlands)

    Deng, F.; Chen, J.; Peters, W.; Krol, M.

    2008-01-01

    Most of our understanding of the sources and sinks of atmospheric CO2 has come from inverse studies of atmospheric CO2 concentration measurements. However, the number of currently available observation stations and our ability to simulate the diurnal planetary boundary layer evolution over continent

  8. A STELLA model to estimate soil CO2 emissions from a short-rotation woody crop

    Science.gov (United States)

    Ying Ouyang; Theodor D. Leininger; Jeff Hatten; Prem B. Parajuli

    2012-01-01

    The potential for climatic factors as well as soil–plant–climate interactions to change as a result of rising levels of atmospheric CO2 concentration is an issue of increasing international environmental concern. Agricultural and forest practices and managements may be important contributors to mitigating elevated atmospheric CO2...

  9. Global Monthly CO2 Flux Inversion Based on Results of Terrestrial Ecosystem Modeling

    NARCIS (Netherlands)

    Deng, F.; Chen, J.; Peters, W.; Krol, M.

    2008-01-01

    Most of our understanding of the sources and sinks of atmospheric CO2 has come from inverse studies of atmospheric CO2 concentration measurements. However, the number of currently available observation stations and our ability to simulate the diurnal planetary boundary layer evolution over

  10. Inline monitoring of CO2 absorption processes using simple analytical techniques and multivariate modeling

    NARCIS (Netherlands)

    Ham, L.V. van der; Bakker, D.E.; Geers, L.F.G.; Goetheer, E.L.V.

    2014-01-01

    The solvent and the dissolved CO2 concentrations are two essential properties of CO2 absorption processes. Currently, they are typically monitored using time-consuming offline analytical techniques. Initial development efforts aiming at a cost-effective and reliable inline monitoring system are desc

  11. Root growth and function of three Mojave Desert grasses in response to elevated atmospheric CO2 concentration

    Science.gov (United States)

    Yoder, C.K.; Vivin, P.; DeFalco, L.A.; Seemann, J.R.; Nowak, R.S.

    2000-01-01

    respiration was significantly correlated with either root C∶N ratio or root water content when all data per species were included within a simple regression model. The results of this study provide little evidence for up-regulation of root physiology in response to elevated CO2 and indicate that root biomass responses to CO2 are species-specific.

  12. Mesozooplankton community development at elevated CO2 concentrations: results from a mesocosm experiment in an Arctic fjord

    Directory of Open Access Journals (Sweden)

    B. Niehoff

    2013-03-01

    Full Text Available The increasing CO2 concentration in the atmosphere caused by burning fossil fuels leads to increasing pCO2 and decreasing pH in the world ocean. These changes may have severe consequences for marine biota, especially in cold-water ecosystems due to higher solubility of CO2. However, studies on the response of mesozooplankton communities to elevated CO2 are still lacking. In order to test whether abundance and taxonomic composition change with pCO2, we have sampled nine mesocosms, which were deployed in Kongsfjorden, an Arctic fjord at Svalbard, and were adjusted to eight CO2 concentrations, initially ranging from 185 μatm to 1420 μatm. Vertical net hauls were taken weekly over about one month with an Apstein net (55 μm mesh size in all mesocosms and the surrounding fjord. In addition, sediment trap samples, taken every second day in the mesocosms, were analysed to account for losses due to vertical migration and mortality. The taxonomic analysis revealed that meroplanktonic larvae (Cirripedia, Polychaeta, Bivalvia, Gastropoda, and Decapoda dominated in the mesocosms while copepods (Calanus spp., Oithona similis, Acartia longiremis and Microsetella norvegica were found in lower abundances. In the fjord copepods prevailed for most of our study. With time, abundance and taxonomic composition developed similarly in all mesocosms and the pCO2 had no significant effect on the overall community structure. Also, we did not find significant relationships between the pCO2 level and the abundance of single taxa. Changes in heterogeneous communities are, however, difficult to detect, and the exposure to elevated pCO2 was relatively short. We therefore suggest that future mesocosm experiments should be run for longer periods.

  13. A New Material Balance Equation Model for Analyzing Dynamic Performance of CO2 Flooding

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Implementing a CO2 flooding scheme successfully requires the capacity to get accurate information of reservoir dynamic performance and fluids injected. Despite some numerical simulation studies, the complicated drive mechanisms and actual reservoir performance have not been fully understood. There is a strong need to develop models from different perspectives to complement current simulators and provide valuable insights into the reservoir performance during CO2 flooding.The aim of this study is to develop a model by using an improved material balance equation (MBE) to analyze quickly the performance of CO2 flooding. After matching the historical field data the proposed model can be used to evaluate,monitor and predict the overall reservoir dynamic performance during CO2 flooding. In order to account accurately for the complex displacement process involving compositional effect and multiphase flow, the PVT properties and flowability of reservoir fluids are incorporated in the model. This study investigates the effects of a number of factors,such as reservoir pressure, the amount of CO2 injected, the CO2 partition ratios in reservoir fluids, the possibility of the existence of a free CO2 gas cap, the proporfon of reservoir fluids contacted with CO2, the starting time of CO2 flooding,oil swelling, and oil flowability improvement by mixing with CO2. The model was used to analyze the CO2 flooding project in Weyburn oil field, Saskatchewan, Canada. This study shows that the proposed model is an effective complementary tool to analyze and monitor the overall reservoir performance during CO2 flooding.

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

    Science.gov (United States)

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

    2017-04-15

    Green roofs are expected to absorb and store carbon in plants and soils and thereby reduce the high CO2 concentration levels in big cities. Sedum species, which are succulent perennials, are commonly used in extensive green roofs due to their shallow root system and ability to withstand long water deficiencies. Here we examined CO2 fixation and emission rates for Mediterranean Sedum sediforme on green-roof experimental plots. During late winter to early spring, we monitored CO2 concentrations inside transparent tents placed over 1m(2) plots and followed gas exchange at the leaf level using a portable gas-exchange system. We found high rates of CO2 emission at daytime, which is when CO2 concentration in the city is the highest. Both plot- and leaf-scale measurements showed that these CO2 emissions were not fully compensated by the nighttime uptake. We conclude that although carbon sequestration may only be a secondary benefit of green roofs, for improving this ecosystem service, other plant species than Sedum should also be considered for use in green roofs, especially in Mediterranean and other semi-arid climates.

  15. Accounting for geochemical alterations of caprock fracture permeability in basin-scale models of leakage from geologic CO2 reservoirs

    Science.gov (United States)

    Guo, B.; Fitts, J. P.; Dobossy, M.; Bielicki, J. M.; Peters, C. A.

    2012-12-01

    Climate mitigation, public acceptance and energy, markets demand that the potential CO2 leakage rates from geologic storage reservoirs are predicted to be low and are known to a high level of certainty. Current approaches to predict CO2 leakage rates assume constant permeability of leakage pathways (e.g., wellbores, faults, fractures). A reactive transport model was developed to account for geochemical alterations that result in permeability evolution of leakage pathways. The one-dimensional reactive transport model was coupled with the basin-scale Estimating Leakage Semi-Analytical (ELSA) model to simulate CO2 and brine leakage through vertical caprock pathways for different CO2 storage reservoir sites and injection scenarios within the Mt. Simon and St. Peter sandstone formations of the Michigan basin. Mineral dissolution in the numerical reactive transport model expands leakage pathways and increases permeability as a result of calcite dissolution by reactions driven by CO2-acidified brine. A geochemical model compared kinetic and equilibrium treatments of calcite dissolution within each grid block for each time step. For a single fracture, we investigated the effect of the reactions on leakage by performing sensitivity analyses of fracture geometry, CO2 concentration, calcite abundance, initial permeability, and pressure gradient. Assuming that calcite dissolution reaches equilibrium at each time step produces unrealistic scenarios of buffering and permeability evolution within fractures. Therefore, the reactive transport model with a kinetic treatment of calcite dissolution was coupled to the ELSA model and used to compare brine and CO2 leakage rates at a variety of potential geologic storage sites within the Michigan basin. The results are used to construct maps based on the susceptibility to geochemically driven increases in leakage rates. These maps should provide useful and easily communicated inputs into decision-making processes for siting geologic CO2

  16. Atmospheric CO2 content in the last 120,000 years: The phosphate-extraction model.

    Science.gov (United States)

    Keir, R. S.; Berger, W. H.

    1983-07-01

    Broecker [1982] has proposed that during the retreat of the Wisconsin ice sheets, atmospheric CO2 increased because of the extraction of phosphorus from the ocean as sea level rose. Using a time-dependent box-model, we examine the consequences of the phosphate extraction hypothesis over the last 120,000 years, assuming that δ18O change in core V28-238 is analogous to sea level variation. The model takes into account the total CO2 and alkalinity balance in the deep sea and in an `upper' reservoir consisting of the surface ocean and atmosphere, which are assumed to be in equilibrium. Dissolution of deep-sea calcium carbonate sediment is assumed to respond to the supply of particulate carbonate from the `upper' box and to the dissolved carbonate-ion concentration of the deep sea. Assuming 1015 mole of phosphorus and 1017 mole of carbon were extracted during deglaciation, the predicted increase in pCO2 is 54 ppm. Variation of pCO2 follows the ice-volume forcing function with a 1000 yr lag, which is the input residence time of water in the deep sea. The accumulation (supply minus dissolution) of CaCO3 and the percent preservation (accumulation over supply) follow the derivative of the ice-volume function. Both are similar to the solution index and percent fragments of core V28-238. In addition, unusually good preservation is predicted during deglaciation due to carbon extraction. If phosphorus but not carbon is assumed to be extracted, the accumulation of CaCO3 varies little, remaining near a value equivalent to the river input.

  17. Phase Equilibria of Water/CO2 and Water/n-Alkane Mixtures from Polarizable Models.

    Science.gov (United States)

    Jiang, Hao; Economou, Ioannis G; Panagiotopoulos, Athanassios Z

    2017-02-16

    Phase equilibria of water/CO2 and water/n-alkane mixtures over a range of temperatures and pressures were obtained from Monte Carlo simulations in the Gibbs ensemble. Three sets of Drude-type polarizable models for water, namely the BK3, GCP, and HBP models, were combined with a polarizable Gaussian charge CO2 (PGC) model to represent the water/CO2 mixture. The HBP water model describes hydrogen bonds between water and CO2 explicitly. All models underestimate CO2 solubility in water if standard combining rules are used for the dispersion interactions between water and CO2. With the dispersion parameters optimized to phase compositions, the BK3 and GCP models were able to represent the CO2 solubility in water, however, the water composition in CO2-rich phase is systematically underestimated. Accurate representation of compositions for both water- and CO2-rich phases cannot be achieved even after optimizing the cross interaction parameters. By contrast, accurate compositions for both water- and CO2-rich phases were obtained with hydrogen bonding parameters determined from the second virial coefficient for water/CO2. Phase equilibria of water/n-alkane mixtures were also studied using the HBP water and an exponenial-6 united-atom n-alkanes model. The dispersion interactions between water and n-alkanes were optimized to Henry's constants of methane and ethane in water. The HBP water and united-atom n-alkane models underestimate water content in the n-alkane-rich phase; this underestimation is likely due to the neglect of electrostatic and induction energies in the united-atom model.

  18. Amine modeling for CO2 capture: internals selection.

    Science.gov (United States)

    Karpe, Prakash; Aichele, Clint P

    2013-04-16

    Traditionally, trays have been the mass-transfer device of choice in amine absorption units. However, the need to process large volumes of flue gas to capture CO2 and the resultant high costs of multiple trains of large trayed columns have prompted process licensors and vendors to investigate alternative mass-transfer devices. These alternatives include third-generation random packings and structured packings. Nevertheless, clear-cut guidelines for selection of packings for amine units are lacking. This paper provides well-defined guidelines and a consistent framework for the choice of mass-transfer devices for amine absorbers and regenerators. This work emphasizes the role played by the flow parameter, a measure of column liquid loading and pressure, in the type of packing selected. In addition, this paper demonstrates the significant economic advantage of packings over trays in terms of capital costs (CAPEX) and operating costs (OPEX).

  19. REDUCING UNCERTAINTIES IN MODEL PREDICTIONS VIA HISTORY MATCHING OF CO2 MIGRATION AND REACTIVE TRANSPORT MODELING OF CO2 FATE AT THE SLEIPNER PROJECT

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Chen

    2015-03-31

    An important question for the Carbon Capture, Storage, and Utility program is “can we adequately predict the CO2 plume migration?” For tracking CO2 plume development, the Sleipner project in the Norwegian North Sea provides more time-lapse seismic monitoring data than any other sites, but significant uncertainties still exist for some of the reservoir parameters. In Part I, we assessed model uncertainties by applying two multi-phase compositional simulators to the Sleipner Benchmark model for the uppermost layer (Layer 9) of the Utsira Sand and calibrated our model against the time-lapsed seismic monitoring data for the site from 1999 to 2010. Approximate match with the observed plume was achieved by introducing lateral permeability anisotropy, adding CH4 into the CO2 stream, and adjusting the reservoir temperatures. Model-predicted gas saturation, CO2 accumulation thickness, and CO2 solubility in brine—none were used as calibration metrics—were all comparable with the interpretations of the seismic data in the literature. In Part II & III, we evaluated the uncertainties of predicted long-term CO2 fate up to 10,000 years, due to uncertain reaction kinetics. Under four scenarios of the kinetic rate laws, the temporal and spatial evolution of CO2 partitioning into the four trapping mechanisms (hydrodynamic/structural, solubility, residual/capillary, and mineral) was simulated with ToughReact, taking into account the CO2-brine-rock reactions and the multi-phase reactive flow and mass transport. Modeling results show that different rate laws for mineral dissolution and precipitation reactions resulted in different predicted amounts of trapped CO2 by carbonate minerals, with scenarios of the conventional linear rate law for feldspar dissolution having twice as much mineral trapping (21% of the injected CO2) as scenarios with a Burch-type or Alekseyev et al.–type rate law for feldspar dissolution (11%). So far, most reactive transport modeling (RTM) studies for

  20. Adaptation to high CO2 concentration in an optimal environment: radiation capture, canopy quantum yield and carbon use efficiency

    Science.gov (United States)

    Monje, O.; Bugbee, B.

    1998-01-01

    The effect of elevated [CO2] on wheat (Triticum aestivum L. Veery 10) productivity was examined by analysing radiation capture, canopy quantum yield, canopy carbon use efficiency, harvest index and daily C gain. Canopies were grown at either 330 or 1200 micromoles mol-1 [CO2] in controlled environments, where root and shoot C fluxes were monitored continuously from emergence to harvest. A rapidly circulating hydroponic solution supplied nutrients, water and root zone oxygen. At harvest, dry mass predicted from gas exchange data was 102.8 +/- 4.7% of the observed dry mass in six trials. Neither radiation capture efficiency nor carbon use efficiency were affected by elevated [CO2], but yield increased by 13% due to a sustained increase in canopy quantum yield. CO2 enrichment increased root mass, tiller number and seed mass. Harvest index and chlorophyll concentration were unchanged, but CO2 enrichment increased average life cycle net photosynthesis (13%, P < 0.05) and root respiration (24%, P < 0.05). These data indicate that plant communities adapt to CO2 enrichment through changes in C allocation. Elevated [CO2] increases sink strength in optimal environments, resulting in sustained increases in photosynthetic capacity, canopy quantum yield and daily C gain throughout the life cycle.

  1. Adaptation to high CO2 concentration in an optimal environment: radiation capture, canopy quantum yield and carbon use efficiency

    Science.gov (United States)

    Monje, O.; Bugbee, B.

    1998-01-01

    The effect of elevated [CO2] on wheat (Triticum aestivum L. Veery 10) productivity was examined by analysing radiation capture, canopy quantum yield, canopy carbon use efficiency, harvest index and daily C gain. Canopies were grown at either 330 or 1200 micromoles mol-1 [CO2] in controlled environments, where root and shoot C fluxes were monitored continuously from emergence to harvest. A rapidly circulating hydroponic solution supplied nutrients, water and root zone oxygen. At harvest, dry mass predicted from gas exchange data was 102.8 +/- 4.7% of the observed dry mass in six trials. Neither radiation capture efficiency nor carbon use efficiency were affected by elevated [CO2], but yield increased by 13% due to a sustained increase in canopy quantum yield. CO2 enrichment increased root mass, tiller number and seed mass. Harvest index and chlorophyll concentration were unchanged, but CO2 enrichment increased average life cycle net photosynthesis (13%, P CO2 enrichment through changes in C allocation. Elevated [CO2] increases sink strength in optimal environments, resulting in sustained increases in photosynthetic capacity, canopy quantum yield and daily C gain throughout the life cycle.

  2. Adaptation to high CO2 concentration in an optimal environment: radiation capture, canopy quantum yield and carbon use efficiency

    Science.gov (United States)

    Monje, O.; Bugbee, B.

    1998-01-01

    The effect of elevated [CO2] on wheat (Triticum aestivum L. Veery 10) productivity was examined by analysing radiation capture, canopy quantum yield, canopy carbon use efficiency, harvest index and daily C gain. Canopies were grown at either 330 or 1200 micromoles mol-1 [CO2] in controlled environments, where root and shoot C fluxes were monitored continuously from emergence to harvest. A rapidly circulating hydroponic solution supplied nutrients, water and root zone oxygen. At harvest, dry mass predicted from gas exchange data was 102.8 +/- 4.7% of the observed dry mass in six trials. Neither radiation capture efficiency nor carbon use efficiency were affected by elevated [CO2], but yield increased by 13% due to a sustained increase in canopy quantum yield. CO2 enrichment increased root mass, tiller number and seed mass. Harvest index and chlorophyll concentration were unchanged, but CO2 enrichment increased average life cycle net photosynthesis (13%, P CO2 enrichment through changes in C allocation. Elevated [CO2] increases sink strength in optimal environments, resulting in sustained increases in photosynthetic capacity, canopy quantum yield and daily C gain throughout the life cycle.

  3. Effects of elevated CO2 and drought on wheat : testing crop simulation models for different experimental and climatic conditions

    NARCIS (Netherlands)

    Ewert, F.; Rodriguez, D.; Jamieson, P.; Semenov, M.A.; Mitchell, R.A.C.; Goudriaan, J.; Porter, J.R.; Kimball, B.A.; Pinter, P.J.; Manderscheid, R.; Weigel, H.J.; Fangmeier, A.; Fereres, E.; Villalobos, F.

    2002-01-01

    Effects of increasing carbon dioxide concentration [CO2] on wheat vary depending on water supply and climatic conditions, which are difficult to estimate. Crop simulation models are often used to predict the impact of global atmospheric changes on food production. However, models have rarely been te

  4. The concentration and efflux of tree stem CO2 and the role of xylem sap flow

    Institute of Scientific and Technical Information of China (English)

    Ping ZHAO; Dirk H(O)LSCHER

    2009-01-01

    The accurate assessment of actual tree stem respiration and its relation with temperature plays a considerable role in investigating the forest carbon cycle.An increasing number of research reports have indicated that tree stem respiration determined with the commonlyapplied chamber gas exchange measuring system does not follow expectations regarding temperature relationships.theory that the respired CO2 in a tree stem would all diffuse outward into the atmosphere,However,it neglects partial CO2 that is dissolved in the xylem sap and is carried away by the transpirational stream.Scientists have started to realize that the respired CO2 measured with the chamber gas exchange method is only a portion of the total stem respiration (CO2 efflux),while the other portion,which is sometimes very substantial in quantity (thought to occupy maybe 15%-75% of the total stem respiration),is transported to the upper part of the stem and to the canopy by sap flow.This suggests that the CO2 produced by respiration is re-allocated within the stem.Accordingly,the change in CO2 efflux could be reflected in the rates of sap flow in addition to its dependence on temperature.Proper methods and instruments are required to quantify the internal and external CO2 fluxes in the trunk and their interaction with related environmental factors.

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

    Energy Technology Data Exchange (ETDEWEB)

    Spangler, Lee H.; Dobeck, Laura M.; Repasky, Kevin S.; Nehrir, Amin R.; Humphries, Seth D.; Barr, Jamie L.; Keith, Charlie J.; Shaw, Joseph A.; Rouse, Joshua H.; Cunningham, Alfred B.; Benson, Sally M.; Oldenburg, Curtis M.; Lewicki, Jennifer L.; Wells, Arthur W.; Diehl, J. R.; Strazisar, Brian; Fessenden, Julianna; Rahn, Thom A.; Amonette, James E.; Barr, Jonathan L.; Pickles, William L.; Jacobson, James D.; Silver, Eli A.; Male, Erin J.; Rauch, Henry W.; Gullickson, Kadie; Trautz, Robert; Kharaka, Yousif; Birkholzer, Jens; Wielopolski, Lucien

    2010-03-01

    A facility has been constructed to perform controlled shallow releases of CO2 at flow rates that challenge near surface detection techniques and can be scalable to desired retention rates of large scale CO2 storage projects. Preinjection measurements were made to determine background conditions and characterize natural variability at the site. Modeling of CO2 transport and concentration in saturated soil and the vadose zone was also performed to inform decisions about CO2 release rates and sampling strategies. Four releases of CO2 were carried out over the summer field seasons of 2007 and 2008. Transport of CO2 through soil, water, plants, and air was studied using near surface detection techniques. Soil CO2 flux, soil gas concentration, total carbon in soil, water chemistry, plant health, net CO2 flux, atmospheric CO2 concentration, movement of tracers, and stable isotope ratios were among the quantities measured. Even at relatively low fluxes, most techniques were able to detect elevated levels of CO2 in the soil, atmosphere, or water. Plant stress induced by CO2 was detectable above natural seasonal variations.

  6. 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.

  7. The counteracting effects of elevated atmospheric CO2 concentrations and drought episodes: Studies of enchytraeid communities in a dry heathland

    DEFF Research Database (Denmark)

    Maraldo, Kristine; Krogh, Paul Henning; Linden, Leon;

    2010-01-01

    The potential impacts of interactions of multiple climate change factors in soil ecosystems have received little attention. Most studies have addressed effects of single factors such as increased temperature or atmospheric CO2 but little is known about how such environmental factors will interact....... In the present study we investigate the effects of in situ exposure to elevated atmospheric CO2 concentration, increased temperatures and prolonged drought episodes on field communities of Enchytraeidae (Oligochaeta) in a dry heathland (Brandbjerg, Denmark). Increased CO2 had a positive effect on enchytraeid...... biomass, whereas drought significantly reduced it. Elevated temperature did not result in any detectable effects. No interactions between the three factors were observed. Interestingly, the positive effect of increased CO2 and the negative effect of drought were cancelled out when applied in combination...

  8. Elevated CO2 response of photosynthesis depends on ozone concentration in aspen

    Science.gov (United States)

    Asko Noormets; Olevi Kull; Anu Sober; Mark E. Kubiske; David F. Karnosky

    2010-01-01

    The effect of elevated CO2 and O3 on apparent quantum yield (ø), maximum photosynthesis (Pmax), carboxylation efficiency (Vcmax) and electron transport capacity (Jmax) at different canopy locations was studied in two aspen (Populus...

  9. 光合作用对胞间和大气CO_2响应曲线的比较%A comparison of response curves of winter wheat photosynthesis to flag leaf intercellular and air CO_2 concentrations

    Institute of Scientific and Technical Information of China (English)

    叶子飘; 于强

    2009-01-01

    By using Li-6400 portable photosynthesis system, the photosynthetic parameters of winter wheat (Triticum aestivum) during its heading stage in North China Plain were measured at air temperature 25℃ and 30℃ and at photosynthetically available radiation 1500 and 2000 mmol·m~(-2)·s~(-1). The measured data were fitted with the modified rectangular hyperbola models of the photosynthetic responses to flag leaf intercellular CO_2 concentration (A/C_i) and air CO_2 concentration (A/C_a), aimed to approach the reasonability of the fitted results obtained from the models. The photosynthetic capacity and CO_2 compensation point estimated by the modified A/C_i curve and A/C_a curve were nearly the same, but the photorespiration and initial earboxylation ef-ficiency estimated by them were completely different. The difference between the two modified curves came from the calculated but not the real intercellular CO_2 concentration. Modified A/C_a curve was more reasonable than the modified A/C_i curve, because the photorespiration rate esti-mated by the former was close to the measured value.%利用Li-6400便携式光合作用系统测定华北平原冬小麦在温度为25℃和30℃、光合有效辐射为1500和2000 mmol·m~(-2)·s~(-1)条件下处于抽穗时期旗叶的CO_2响应曲线,研究植物光合作用对胞间CO_2响应(A/C_i)和对大气CO_2响应(A/C_a)的直角双曲线修正模型所给拟合结果的合理性.结果表明:由A/C_i和A/C_a修正模型所给的光合能力和CO_2补偿点几乎相同,但得到的光呼吸速率和初始羧化效率则完全不等;产生这种差异的原因是利用叶片气体交换测定的数据所计算的胞间CO_2浓度并不是植物叶片本身的胞间CO_2浓度;A/C_a修正模型比A/C_i修正模型更为合理是因为A/C_a所估算的光呼吸速率接近测量值.

  10. Dynamics of the terrestrial biosphere, climate and atmospheric CO2 concentration during interglacials: a comparison between Eemian and Holocene

    Directory of Open Access Journals (Sweden)

    G. Schurgers

    2006-01-01

    Full Text Available A complex earth system model (atmosphere and ocean general circulation models, ocean biogeochemistry and terrestrial biosphere was used to perform transient simulations of two interglacial sections (Eemian, 128–113 ky B.P., and Holocene, 9 ky B.P.–present. The changes in terrestrial carbon storage during these interglacials were studied with respect to changes in the earth's orbit. The effects of different climate factors on changes in carbon storage were studied in offline experiments in which the vegetation model was forced only with temperature, hydrological parameters, radiation, or CO2 concentration from the transient runs. The largest anomalies in terrestrial carbon storage were caused by temperature changes. However, the increase in storage due to forest expansion and increased photosynthesis in the high latitudes was nearly balanced by the decrease due to increased respiration. Large positive effects on carbon storage were caused by an enhanced monsoon circulation in the subtropics between 128 and 121 ky B.P. and between 9 and 6 ky B.P., and by increases in incoming radiation during summer for 45° to 70° N compared to a control simulation with present-day insolation. Compared to this control simulation, the net effect of these changes was a positive carbon storage anomaly in the terrestrial biosphere of about 200 Pg C for 125 ky B.P. and 7 ky B.P., and a negative anomaly around 150 Pg C for 116 ky B.P. Although the net increases for Eemian and Holocene were rather similar, the magnitudes of the processes causing these effects were different. The decrease in terrestrial carbon storage during the experiments was the main driver of an increase in atmospheric CO2 concentration during both the Eemian and the Holocene.

  11. Putting an ultrahigh concentration of amine groups into a metal-organic framework for CO2 capture at low pressures.

    Science.gov (United States)

    Liao, Pei-Qin; Chen, Xun-Wei; Liu, Si-Yang; Li, Xu-Yu; Xu, Yan-Tong; Tang, Minni; Rui, Zebao; Ji, Hongbing; Zhang, Jie-Peng; Chen, Xiao-Ming

    2016-10-19

    Tremendous efforts have been devoted to increasing the CO2 capture performance of porous materials, especially for low CO2 concentration environments. Here, we report that hydrazine can be used as a diamine short enough to functionalize the small-pore metal-organic framework [Mg2(dobdc)] (H4dobdc = 2,5-dihydroxyl-1,4-benzenedicarboxylic acid). By virtue of the ultrahigh concentration of free amine groups (6.01 mmol g(-1) or 7.08 mmol cm(-3)) capable of reversible carbamic acid formation, the new material [Mg2(dobdc)(N2H4)1.8] achieves a series of new records for CO2 capture, such as single-component isotherm uptakes of 3.89 mmol g(-1) or 4.58 mmol cm(-3) at the atmospheric CO2 concentration of 0.4 mbar at 298 K and 1.04 mmol g(-1) or 1.22 mmol cm(-3) at 328 K, as well as more than a 4.2 mmol g(-1) or 4.9 mmol cm(-3) adsorption/desorption working capacity under dynamic mixed-gas conditions with CO2 concentrations similar to those in flue gases and ambient air.

  12. Climate sensitivity due to increased CO2: experiments with a coupled atmosphere and ocean general circulation model

    Science.gov (United States)

    Washington, Warren M.; Meehl, Gerald A.

    1989-06-01

    A version of the National Center for Atmospheric Research community climate model — a global, spectral (R15) general circulation model — is coupled to a coarse-grid (5° latitude-] longitude, four-layer) ocean general circulation model to study the response of the climate system to increases of atmospheric carbon dioxide (CO2). Three simulations are run: one with an instantaneous doubling of atmospheric CO2 (from 330 to 660 ppm), another with the CO2 concentration starting at 330 ppm and increasing linearly at a rate of 1% per year, and a third with CO2 held constant at 330 pm. Results at the end of 30 years of simulation indicate a globally averaged surface air temperature increase of 1.6° C for the instantaneous doubling case and 0.7°C for the transient forcing case. Inherent characteristics of the coarse-grid ocean model flow sea-surface temperatures (SSTs) in the tropics and higher-than-observed SSTs and reduced sea-ice extent at higher latitudes] produce lower sensitivity in this model after 30 years than in earlier simulations with the same atmosphere coupled to a 50-m, slab-ocean mixed layer. Within the limitations of the simulated meridional overturning, the thermohaline circulation weakens in the coupled model with doubled CO2 as the high-latitude ocean-surface layer warms and freshens and westerly wind stress is decreased. In the transient forcing case with slowly increasing CO2 (30% increase after 30 years), the zonal mean warming of the ocean is most evident in the surface layer near 30° 50° S. Geographical plots of surface air temperature change in the transient case show patterns of regional climate anomalies that differ from those in the instantaneous CO2 doubling case, particularly in the North Atlantic and northern European regions. This suggests that differences in CO2 forcing in the climate system are important in CO2 response in regard to time-dependent climate anomaly regimes. This confirms earlier studies with simple climate models

  13. A SIMULATION OF CO2 UPTAKE IN A THREE DIMENSIONAL OCEAN CARBON CYCLE MODEL

    Institute of Scientific and Technical Information of China (English)

    金心; 石广玉

    2001-01-01

    A three-dimensional ocean carbon cycle model which is a general circulation model couple.d with simple biogeochemical processes is used to simulate CO2 uptake by the ocean. The OGCM used is a modified version of the Geophysical Fluid Dynamics Laboratory modular ocean model (MOM2). The ocean chemistry and a simple ocean biota model are included. Principal variables are .total CO2, alkalinity and phosphate. The vertical profile of POC flux observed by sediment traps is adopted, the rain ratio, a ratio of production rate of calcite against that of POC, and the bio-production efficiency should be 0. 06 and 2 per year, separately. The uptake of anthropogenicCO2 by the ocean is studied. Calculated oceanic uptake of anthropogenic CO2 during the 1980s is 2. 05× 10 15g (Pg) per year. The regional distributions of global oceanic CO2 are discussed.

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

    Science.gov (United States)

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

    2017-01-01

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

  15. Characteristics of variations of climate change and atmospheric CO2 concentration at different time scales over the past 500 Ma

    Science.gov (United States)

    LIU, Z.; Huang, S. S. X. E. C.; Tang, X.

    2015-12-01

    It is generally believed that current global warming is due to the persistent rise of atmospheric greenhouse gas CO2. The consensus is based mostly on the observational data of past decades and the polar ice core records. To understand the relationship between climate change and atmospheric CO2, their behaviors over a longer interval at different time scales need to be appreciated. Here, we collect and analyze past 500 Ma records of atmospheric CO2 and temperature in six time periods, namely Phanerozoic, Cenozoic, middle Pleistocene, last deglaciation, past millennium, and recent decades. According to the carriers and time spans, we divide these records into three categories: 1.The millionaire and longer records from model calculation and paleosols/paleobotany proxies. Although the trends of both variables are generally consistent on this time scale, it is difficult to establish a clear causal relationship because of great uncertainties and low resolutions of both sets of data. 2.The orbital scale mainly from the polar ice core. High precise CO2 and temperature reconstructions allow for an examination of the possible role of atmospheric CO2 in the glacial-interglacial transformation. 3.The records at centennial and shorter time scales over the past millennium from ice, snow, and instrumental data. The past millennium records are most abundant and accurate, especially CO2 has been measured directly in recent decades. However, due to the difficulties in distinguishing the effect of CO2 from other factors, there are great uncertainties in the interpretation of climate change versus CO2. Overall, we come to the following conclusions:1.Paleoclimatic reconstructions show that both temperature and atmospheric CO2 have generally decreased over the past 500 Ma. However, there are no consistent sequential orders in the changes between these two variables. 2.The Earth's atmospheric CO2 has a drastic oscillation history. There were many high CO2 periods when the values were

  16. Patterns in CH4 and CO2 concentrations across boreal rivers: Major drivers and implications for fluvial greenhouse emissions under climate change scenarios.

    Science.gov (United States)

    Campeau, Audrey; Del Giorgio, Paul A

    2014-04-01

    It is now widely accepted that boreal rivers and streams are regionally significant sources of carbon dioxide (CO2), yet their role as methane (CH4) emitters, as well as the sensitivity of these greenhouse gas (GHG) emissions to climate change, are still largely undefined. In this study, we explore the large-scale patterns of fluvial CO2 and CH4 partial pressure (pCO2 , pCH4) and gas exchange (k) relative to a set of key, climate-sensitive river variables across 46 streams and rivers in two distinct boreal landscapes of Northern Québec. We use the resulting models to determine the direction and magnitude of C-gas emissions from these boreal fluvial networks under scenarios of climate change. River pCO2 and pCH4 were positively correlated, although the latter was two orders of magnitude more variable. We provide evidence that in-stream metabolism strongly influences the dynamics of surface water pCO2 and pCH4 , but whereas pCO2 is not influenced by temperature in the surveyed streams and rivers, pCH4 appears to be strongly temperature-dependent. The major predictors of ambient gas concentrations and exchange were water temperature, velocity, and DOC, and the resulting models indicate that total GHG emissions (C-CO2 equivalent) from the entire network may increase between by 13 to 68% under plausible scenarios of climate change over the next 50 years. These predicted increases in fluvial GHG emissions are mostly driven by a steep increase in the contribution of CH4 (from 36 to over 50% of total CO2 -equivalents). The current role of boreal fluvial networks as major landscape sources of C is thus likely to expand, mainly driven by large increases in fluvial CH4 emissions.

  17. Modeling char conversion under suspension fired conditions in O2/N2 and O2/CO2 atmospheres

    DEFF Research Database (Denmark)

    Brix, Jacob; Jensen, Peter Arendt; Jensen, Anker Degn

    2011-01-01

    concentrations between 5 and 28 vol.%. The COal COmbustion MOdel, COCOMO, includes the three char morphologies: cenospheric char, network char and dense char each divided between six discrete particle sizes. Both combustion and gasification with CO2 are accounted for and reaction rates include thermal char......The aim of this investigation has been to model combustion under suspension fired conditions in O2/N2 and O2/CO2 mixtures. Experiments used for model validation have been carried out in an electrically heated Entrained Flow Reactor (EFR) at temperatures between 1173 K and 1673 K with inlet O2...

  18. Changes in the activities of starch metabolism enzymes in rice grains in response to elevated CO2 concentration

    Science.gov (United States)

    Xie, Li-Yong; Lin, Er-Da; Zhao, Hong-Liang; Feng, Yong-Xiang

    2016-05-01

    The global atmospheric CO2 concentration is currently (2012) 393.1 μmol mol-1, an increase of approximately 42 % over pre-industrial levels. In order to understand the responses of metabolic enzymes to elevated CO2 concentrations, an experiment was conducted using the Free Air CO2 Enrichment (FACE )system. Two conventional japonica rice varieties ( Oryza sativa L. ssp. japonica) grown in North China, Songjing 9 and Daohuaxiang 2, were used in this study. The activities of ADPG pyrophosphorylase, soluble and granule-bound starch synthases, and soluble and granule-bound starch branching enzymes were measured in rice grains, and the effects of elevated CO2 on the amylose and protein contents of the grains were analyzed. The results showed that elevated CO2 levels significantly increased the activity of ADPG pyrophosphorylase at day 8, 24, and 40 after flower, with maximum increases of 56.67 % for Songjing 9 and 21.31 % for Daohuaxiang 2. Similarly, the activities of starch synthesis enzymes increased significantly from the day 24 after flower to the day 40 after flower, with maximum increases of 36.81 % for Songjing 9 and 66.67 % for Daohuaxiang 2 in soluble starch synthase (SSS), and 25.00 % for Songjing 9 and 36.44 % for Daohuaxiang 2 in granule-bound starch synthase (GBSS), respectively. The elevated CO2 concentration significantly increased the activity of soluble starch branching enzyme (SSBE) at day 16, 32, and 40 after flower, and also significantly increased the activity of granule-bound starch branching enzyme (GBSBE) at day 8, 32, and 40 after flower. The elevated CO2 concentration increased the peak values of enzyme activity, and the timing of the activity peaks for SSS and GBSBE were earlier in Songjing 9 than in Daohuaxiang 2. There were obvious differences in developmental stages between the two varieties of rice, which indicated that the elevated CO2 concentration increased enzyme activity expression and starch synthesis, affecting the final contents

  19. Quantifying the Multivariate ENSO Index (MEI) coupling to CO2 concentration and to the length of day variations

    CERN Document Server

    Mazzarella, A; Scafetta, N

    2012-01-01

    The El Ni\\~no Southern Oscillation (ENSO) is the Earth's strongest climate fluctuation on inter-annual time-scales and has global impacts although originating in the tropical Pacific. Many point indices have been developed to describe ENSO but the Multivariate ENSO Index (MEI) is considered the most representative since it links six different meteorological parameters measured over the tropical Pacific. Extreme values of MEI are correlated to the extreme values of atmospheric CO2 concentration rate variations and negatively correlated to equivalent scale extreme values of the length of day (LOD) rate variation. We evaluate a first order conversion function between MEI and the other two indexes using their annual rate of variation. The quantification of the strength of the coupling herein evaluated provides a quantitative measure to test the accuracy of theoretical model predictions. Our results further confirm the idea that the major local and global Earth-atmosphere system mechanisms are significantly couple...

  20. Interactive effects of elevated CO2 concentration and irrigation on photosynthetic parameters and yield of maize in Northeast China.

    Directory of Open Access Journals (Sweden)

    Fanchao Meng

    Full Text Available Maize is one of the major cultivated crops of China, having a central role in ensuring the food security of the country. There has been a significant increase in studies of maize under interactive effects of elevated CO2 concentration ([CO2] and other factors, yet the interactive effects of elevated [CO2] and increasing precipitation on maize has remained unclear. In this study, a manipulative experiment in Jinzhou, Liaoning province, Northeast China was performed so as to obtain reliable results concerning the later effects. The Open Top Chambers (OTCs experiment was designed to control contrasting [CO2] i.e., 390, 450 and 550 µmol·mol(-1, and the experiment with 15% increasing precipitation levels was also set based on the average monthly precipitation of 5-9 month from 1981 to 2010 and controlled by irrigation. Thus, six treatments, i.e. C550W+15%, C550W0, C450W+15%, C450W0, C390W+15% and C390W0 were included in this study. The results showed that the irrigation under elevated [CO2] levels increased the leaf net photosynthetic rate (Pn and intercellular CO2 concentration (Ci of maize. Similarly, the stomatal conductance (Gs and transpiration rate (Tr decreased with elevated [CO2], but irrigation have a positive effect on increased of them at each [CO2] level, resulting in the water use efficiency (WUE higher in natural precipitation treatment than irrigation treatment at elevated [CO2] levels. Irradiance-response parameters, e.g., maximum net photosynthetic rate (Pnmax and light saturation points (LSP were increased under elevated [CO2] and irrigation, and dark respiration (Rd was increased as well. The growth characteristics, e.g., plant height, leaf area and aboveground biomass were enhanced, resulting in an improved of yield and ear characteristics except axle diameter. The study concluded by reporting that, future elevated [CO2] may favor to maize when coupled with increasing amount of precipitation in Northeast China.

  1. Boundary layer structure and stability classification validated with CO2 concentrations over the Northern Spanish Plateau

    Directory of Open Access Journals (Sweden)

    B. de Torre

    2009-01-01

    Full Text Available A description of the lower boundary layer is vital to enhance our understanding of dispersion processes. In this paper, Radio Acoustic Sounding System sodar measurements obtained over three years were used to calculate the Brunt-Väisälä frequency and the Monin-Obukhov length. The Brunt-Väisälä frequency enabled investigation of the structure of this layer. At night, several layers were noticeable and the maximum was observed at the first level, 40 m, whereas during the day, it was present at about 320 m. The Monin-Obukhov length was calculated with the four first levels measured, 40–100 m, by an original iterative method and used to establish four stability classes: drainage, extremely stable, stable and unstable. Wind speed and temperature median profiles linked to these classes were also presented. Wind speeds were the lowest, but temperatures were the highest and inversions were intense at night in drainage situations. However, unstable situations were linked to high wind speeds and superadiabatic temperature profiles. Detrended CO2 concentrations were used to determine the goodness of the classification proposed evidencing values which under drainage at night in spring were nearly 28 ppm higher than those corresponding to unstable situations. Finally, atmosphere structure was presented for the proposed stability classes and related with wind speed profiles. Under extremely stable situations, low level jets were coupled to the surface, with median wind speeds below 8 m s−1 and cores occasionally at 120 m. However, jets were uncoupled in stable situations, wind speed medians were higher than 11 m s−1 and their core heights were around 200 m.

  2. Response of CO2 Concentration in Andisol to Rainfall Events by Using Buried Tubing Gas Monitoring System

    Science.gov (United States)

    Endo, Toshifumi; Tokida, Takeshi; Imoto, Hiromi; Nishimura, Taku; Miyazaki, Tsuyoshi

    For the purpose of continuous soil CO2 gas monitoring, gas permeable resins were evaluated. Among polytetrafluoroethylen (PTFE), polyfluoroethylene propylene (PFEP) and silicone, the silicone rubber tube had highest permeability for oxygen gas. Buried Tubing Gas Monitoring System (BT-GMS) consisting of silicone rubber tube connected to a Non-diffuse infrared (NDIR) -CO2 gas and galvanic cell O2 gas sensors were constructed, and buried into an Andisol upland field at a depth of 20cm. Thermo-couples and EC-5 soil moisture sensors were inserted into 10 and 20cm deep layers. Soil CO2 gas concentration, temperature and moisture were continuously monitored for 5 months. Soil CO2 concentration was sensitive to rainfall events and soil moisture change. Responses were keen during summer until early autumn when soil temperature was higher than 20°C. Then, when soil temperature got lower the response tended to be dull. This suggested quick CO2 gas concentration change following a rainfall event was mostly due to enhancement in soil respiration with soil moisture rise.

  3. Why are Nitrogen Concentrations in Plant Tissues Lower under Elevated CO2? A Critical Examination of the Hypotheses

    Institute of Scientific and Technical Information of China (English)

    Daniel R. Taub; Xianzhong Wang

    2008-01-01

    Plants grown under elevated atmospheric [CO2] typically have decreased tissue concentrations of N compared with plants grown under current ambient [CO2]. The physiological mechanisms responsible for this phenomenon have not been definitely established, although a considerable number of hypotheses have been advanced to account for it. In this review we discuss and critically evaluate these hypotheses. One contributing factor to the decreases in tissue N concentrations clearly is dilution of N by increased photosynthetic assimilation of C. In addition, studies on intact plants show strong evidence for a general decrease in the specific uptake rates (uptake per unit mass or length of root) of N by roots under elevated CO2. This decreased root uptake appears likely to be the result both of decreased N demand by shoots and of decreased ability of the soil-root system to supply N. The best-supported mechanism for decreased N supply is a decrease in transpiration-driven mass flow of N in soils due to decreased stomatal conductance at elevated CO2, although some evidence suggests that altered root system architecture may also play a role. There is also limited evidence suggesting that under elevated CO2, plants may exhibit increased rates of N loss through volatilization and/or root exudation, further contributing to lowering tissue N concentrations.

  4. Discrete element modeling of indentation tests to investigate mechanisms of CO2-related chemomechanical rock alteration

    Science.gov (United States)

    Sun, Zhuang; Espinoza, D. Nicolas; Balhoff, Matthew T.

    2016-11-01

    During CO2 injection into geological formations, petrophysical and geomechanical properties of host formations can be altered due to mineral dissolution and precipitation. Field and laboratory results have shown that sandstone and siltstone can be altered by CO2-water mixtures, but few quantitative studies have been performed to fully investigate underlying mechanisms. Based on the hypothesis that CO2-water mixtures alter the integrity of rock structure by attacking cements rather than grains, we attempt to explain the degradation of cementation due to long-term contact with CO2 and water and mechanisms for changes in rock mechanical properties. Many sandstones, including calcite-cemented quartzitic sandstone, chlorite-cemented quartzitic sandstone, and hematite-cemented quartzitic sandstone, contain interparticle cements that are more readily affected by CO2-water mixtures than grains. A model that couples the discrete element method and the bonded-particle model is used to perform simulations of indentation tests on synthetic rocks with crystal and random packings. The model is verified against the analytical cavity expansion model and validated against laboratory indentation tests on Entrada sandstone with and without CO2 alteration. Sensitivity analysis is performed for cementation microscopic parameters including stiffness, size, axial, and shear strength. The simulation results indicate that the CO2-related degradation of mechanical properties in bleached Entrada sandstone can be attributed to the reduction of cement size rather than cement strength. Our study indicates that it is possible to describe the CO2-related rock alteration through particle-scale mechanisms.

  5. A general model for CO2 regulation: the case of Denmark

    DEFF Research Database (Denmark)

    Svendsen, Gert Tinggaard

    1998-01-01

    for the public electricity sector. Permits are then to be devaluated in year 2005 by 20%. A CO2 tax should be correctly set at a $50 level in year 2005 for households, transportation sector and private firms not participating in the CO2 market. This model may guide future energy policies in other countries...

  6. Mathematical modelling of gain-switched RF-excited CO2 waveguide laser

    Institute of Scientific and Technical Information of China (English)

    Hussain Badran; Tian Zhao-Shuo; Wang Qi

    2004-01-01

    The detailed mathematical models for the evolution of light pulses in RF-excited CO2 waveguide lasers are derived.Explicit expressions for the pulse characteristics in RF-excited CO2 waveguide lasers are obtained. The effects of losses and unsaturated gain on output power are calculated.

  7. Application of simplified models to CO2 migration and immobilization in large-scale geological systems

    KAUST Repository

    Gasda, Sarah E.

    2012-07-01

    Long-term stabilization of injected carbon dioxide (CO 2) is an essential component of risk management for geological carbon sequestration operations. However, migration and trapping phenomena are inherently complex, involving processes that act over multiple spatial and temporal scales. One example involves centimeter-scale density instabilities in the dissolved CO 2 region leading to large-scale convective mixing that can be a significant driver for CO 2 dissolution. Another example is the potentially important effect of capillary forces, in addition to buoyancy and viscous forces, on the evolution of mobile CO 2. Local capillary effects lead to a capillary transition zone, or capillary fringe, where both fluids are present in the mobile state. This small-scale effect may have a significant impact on large-scale plume migration as well as long-term residual and dissolution trapping. Computational models that can capture both large and small-scale effects are essential to predict the role of these processes on the long-term storage security of CO 2 sequestration operations. Conventional modeling tools are unable to resolve sufficiently all of these relevant processes when modeling CO 2 migration in large-scale geological systems. Herein, we present a vertically-integrated approach to CO 2 modeling that employs upscaled representations of these subgrid processes. We apply the model to the Johansen formation, a prospective site for sequestration of Norwegian CO 2 emissions, and explore the sensitivity of CO 2 migration and trapping to subscale physics. Model results show the relative importance of different physical processes in large-scale simulations. The ability of models such as this to capture the relevant physical processes at large spatial and temporal scales is important for prediction and analysis of CO 2 storage sites. © 2012 Elsevier Ltd.

  8. Growing wheat in Biosphere 2 under elevated CO2: observations and modeling

    Science.gov (United States)

    Tubiello, F. N.; Mahato, T.; Morton, T.; Druitt, J. W.; Volk, T.; Marino, B. D.

    1999-01-01

    Spring wheat (Triticum aestivum L., cv. Yecora Rojo) was grown in the intensive agricultural biome (IAB) of Biosphere 2 during the l995-l996 winter/spring season. Environmental conditions were characterized by a day/night temperature regime of 27/17 degrees C, relative humidity (RH) levels around 45%, mean atmospheric CO2 concentration of 450 ppmv, and natural light conditions with mean intensities about half of outside levels. Weekly samples of above-ground plant matter were collected throughout the growing season and phenological events recorded. A computer model, CERES-Wheat, previously tested under both field and controlled conditions, was used to simulate the observed crop growth and to help in data analysis. We found that CERES-Wheat simulated the data collected at Biosphere 2 to within 10% of observed, thus suggesting that wheat growth inside the IAB was comparable to that documented in other environments. The model predicts phenological stages and final dry matter (DM) production within l0% of the observed data. Measured DM production rates, normalized for light absorbed by the crop. suggested photosynthetic efficiencies intermediate between those observed under optimal field conditions and those recorded in NASA-Controlled Ecological Life-Support Systems (CELSS). We suggest that such a difference can be explained primarily in terms of low light levels inside the IAB, with additional effects due to elevated CO2 concentrations and diffuse light fractions.

  9. The effects of inorganic nitrogen form and CO2 concentration on wheat yield and nutrient accumulation and distribution

    Directory of Open Access Journals (Sweden)

    Eli eCarlisle

    2012-09-01

    Full Text Available Nitrogen (N is the most limiting nutrient for plant growth and primary productivity. Inorganic N is available to plants from the soil as ammonium (NH4+ and nitrate (NO3–. We studied how wheat grown hydroponically to senescence in controlled environmental chambers is affected by N form (NH4+ vs. NO3– and CO2 concentration (‘subambient’, ‘ambient’, and ‘elevated’ in terms of biomass, yield, and nutrient accumulation and partitioning. NH4+-grown wheat had the strongest response to CO2 concentration. Plants exposed to subambient and ambient CO2 concentrations typically had the greatest biomass and nutrient accumulation under both N forms. In general NH4+ plants had higher concentrations of total N, P, K, S, Ca, Zn, Fe, and Cu, while NO3– plants had higher concentrations of Mg, B, Mn, and NO3–-N. NH4+ plants contained amounts of phytate similar to NO3– plants but had higher bioavailable Zn, which could have ramifications for human health. NH4+ plants allocated more nutrients and biomass to aboveground tissues whereas NO3– plants allocated more nutrients to the roots. The two inorganic nitrogen forms influenced plant growth and nutrient status so distinctly that they should be treated separately. Moreover, plant growth and nutrient status varied in a non-linear manner with atmospheric CO2 concentration.

  10. Phtotsynthetic physiological Response of Larrea tridentata due to the increase of CO2 concentration and drought%拉瑞尔Larrea tridentata光合特性对CO2摩尔分数和干旱的响应

    Institute of Scientific and Technical Information of China (English)

    张香凝; 乔杰; 孙向阳; 王保平; 崔令军

    2011-01-01

    Li-6400 portable photosynthesis system was used to measure the photosynthetic physiological responses of larrea tridentara to the increase of CO2 concentration and drought. The results showed that: Water stress had little influence on the leaf's actinic process. Photosynthetic apparatus were not harmed by drought when the soil water potential was above-0.884 5 MPa. The light saturation point, the photosynthetic rate and the apparent photon utilization efficiency increased as the CO2 concentration increased. The positive effect of CO2 concentration increased is bigger than the negative effect from the drought, so the drought resistance ability of L. tridentata was raised to a certain extent by the CO2 concentration increase. The CO2 concentration saturation point(CSP) increased with the PARs and CO2 concentration increase. This indicated that the CO2 utilization efficiency increased. The stomatal conductance and transpiration decreased while WUE increased with the increase in CO2 concentration. The CO2 concentration which saturated leaf RubisCO while cause stoma closed was 700-800 μmol·mo1-1. The current CO2 concentration has not saturated the RubisCO of L. tridentata. The CO2 concentration increased in the future will promote the photosynthesis of L. tridentata, and may increase the drought resistance ability of L.tridentata.%利用Li-6400光合测定系统测定拉瑞尔L.tridentata 的光合生理特性及其对CO2摩尔分数升高和干旱的响应.结果表明:土壤水势在-0.8845 MPa以上,L.tridentata的光合器没有任何损害,抵御干旱的能力很强;适当的增加CO2摩尔分数有利于提高光饱和点、光量子利用效率和最大净光合速率,且CO2摩尔分数升高的正效应要大于土壤水分胁迫的负效应,因而在一定程度上CO2摩尔分数的增加,提高了L.tridentata的抗旱能力;随着光合有效辐射的增强和CO2摩尔分数的升高,叶片净光合速率、CO2饱和点和羧化速率都有增大趋势,叶片对高摩尔分数CO

  11. A hybrid model of the CO2 geochemical cycle and its application to large impact events

    Science.gov (United States)

    Kasting, J. F.; Pollack, J. B.; Toon, O. B.; Richardson, S. M.

    1986-01-01

    The effects of a large asteriod or comet impact on modern and ancient marine biospheres are analyzed. A hybrid model of the carbonate-silicate geochemical cycle, which is capable of calculating the concentrations of carbon dioxide in the atmosphere, ocean, and sedimentary rocks, is described. The differences between the Keir and Berger (1983) model and the hybrid model are discussed. Equilibrium solutions are derived for the preindustrial atmosphere/ocean system and for a system similar to that of the late Cretaceous Period. The model data reveal that globl darkening caused by a stratospheric dust veil could destroy the existing phytoplankton within a period of several weeks or months, nd the dissolution of atmospheric NO(x) compounds would lower the pH of ocean surface waters and release CO2 into the atmosphere. It is noted that the surface temperatures could be increased by several degrees and surface oceans would be uninhabitable for calcaerous organisms for approximately 20 years.

  12. Fast Cloud Adjustment to Increasing CO2 in a Superparameterized Climate Model

    Directory of Open Access Journals (Sweden)

    Marat Khairoutdinov

    2012-05-01

    Full Text Available Two-year simulation experiments with a superparameterized climate model, SP-CAM, are performed to understand the fast tropical (30S-30N cloud response to an instantaneous quadrupling of CO2 concentration with SST held fixed at present-day values.The greenhouse effect of the CO2 perturbation quickly warms the tropical land surfaces by an average of 0.5 K. This shifts rising motion, surface precipitation, and cloud cover at all levels from the ocean to the land, with only small net tropical-mean cloud changes. There is a widespread average reduction of about 80 m in the depth of the trade inversion capping the marine boundary layer (MBL over the cooler subtropical oceans.One apparent contributing factor is CO2-enhanced downwelling longwave radiation, which reduces boundary-layer radiative cooling, a primary driver of turbulent entrainment through the trade inversion. A second contributor is a slight CO2-induced heating of the free troposphere above the MBL, which strengthens the trade inversion and also inhibits entrainment. There is a corresponding downward displacement of MBL clouds with a very slight decrease in mean cloud cover and albedo.Two-dimensional cloud-resolving model (CRM simulations of this MBL response are run to steady state using composite SP-CAM simulated thermodynamic and wind profiles from a representative cool subtropical ocean regime, for the control and 4xCO2 cases. Simulations with a CRM grid resolution equal to that of SP-CAM are compared with much finer resolution simulations. The coarse-resolution simulations maintain a cloud fraction and albedo comparable to SP-CAM, but the fine-resolution simulations have a much smaller cloud fraction. Nevertheless, both CRM configurations simulate a reduction in inversion height comparable to SP-CAM. The changes in low cloud cover and albedo in the CRM simulations are small, but both simulations predict a slight reduction in low cloud albedo as in SP-CAM.

  13. Modeling CO 2 ice clouds with a Mars Global Climate Model

    Science.gov (United States)

    Audouard, Joachim; Määttänen, Anni; Listowski, Constantino; Millour, Ehouarn; Forget, Francois; Spiga, Aymeric

    2016-10-01

    Since the first claimed detection of CO2 ice clouds by the Mariner campaign (Herr and Pimentel, 1970), more recent observations and modelling works have put new constraints concerning their altitude, region, time and mechanisms of formation (Clancy and Sandor, 1998; Montmessin et al., 2007; Colaprete et al., 2008; Määttänen et al., 2010; Vincendon et al., 2011; Spiga et al. 2012; Listowski et al. 2014). CO2 clouds are observed at the poles at low altitudes (LMD, Forget et al., 1999). It covers CO2 microphysics, growth, evolution and dynamics with a methodology inspired from the water ice clouds scheme recently included in the LMD GCM (Navarro et al., 2014).Two main factors control the formation and evolution of CO2 clouds in the Martian atmosphere: sufficient supersaturation of CO2 is needed and condensation nuclei must be available. Topography-induced gravity-waves (GW) are expected to propagate to the upper atmosphere where they produce cold pockets of supersaturated CO2 (Spiga et al., 2012), thus allowing the formation of clouds provided enough condensation nuclei are present. Such supersaturations have been observed by various instruments, in situ (Schofield et al., 1997) and from orbit (Montmessin et al., 2006, 2011; Forget et al., 2009).Using a GW-induced temperature profile and the 1-D version of the GCM, we simulate the formation of CO2 clouds in the mesosphere and investigate the sensitivity of our microphysics scheme. First results and steps towards the integration in the 3-D GCM will be presented and discussed at the conference.This work is funded by the Laboratory of Excellence ESEP.

  14. Characteristics of PM10 and CO2 concentrations on 100 underground subway station platforms in 2014 and 2015

    Science.gov (United States)

    Hwang, Sung Ho; Park, Wha Me; Park, Jae Bum; Nam, Taegyun

    2017-10-01

    In this study, the concentrations of particulate matter 10 μm or less in diameter (PM10) and carbon dioxide (CO2) were measured in 100 underground subway stations, and the potential health risks of PM10, and environmental factors affecting these concentrations were analyzed. The concentrations were measured from May 2014 to September 2015 in stations along Seoul Metro lines 1-4. There were significantly different PM10 concentrations among the underground subway stations along lines 1, 2, 3, and 4. The PM10 concentrations were associated with the CO2 concentrations, construction years, station depths, and numbers of passengers. The underground PM10 concentrations were significantly higher than the outdoor PM10 concentrations. In addition, the PM10 concentrations were higher in the stations that were constructed in the 1970s than in those constructed after the 1970s. The PM10 and CO2 concentrations varied significantly, depending on the construction year and number of passengers. The hazard quotient is higher than the acceptable level of 1.0 μg kg-1 day for children, indicating that they are at risk of exposure to unsafe PM10 levels when travelling by the metro. Therefore, stricter management may be necessary for the stations constructed in the 1970s as well as those with higher numbers of passengers.

  15. Engineering the Cyanobacterial Carbon Concentrating Mechanism for Enhanced CO2 Capture and Fixation

    Energy Technology Data Exchange (ETDEWEB)

    Sandh, Gustaf; Cai, Fei; Shih, Patrick; Kinney, James; Axen, Seth; Salmeen, Annette; Zarzycki, Jan; Sutter, Markus; Kerfeld, Cheryl

    2011-06-02

    In cyanobacteria CO2 fixation is localized in a special proteinaceous organelle, the carboxysome. The CO2 fixation enzymes are encapsulated by a selectively permeable protein shell. By structurally and functionally characterizing subunits of the carboxysome shell and the encapsulated proteins, we hope to understand what regulates the shape, assembly and permeability of the shell, as well as the targeting mechanism and organization of the encapsulated proteins. This knowledge will be used to enhance CO2 fixation in both cyanobacteria and plants through synthetic biology. The same strategy can also serve as a template for the production of modular synthetic bacterial organelles. Our research is conducted using a variety of techniques such as genomic sequencing and analysis, transcriptional regulation, DNA synthesis, synthetic biology, protein crystallization, Small Angle X-ray Scattering (SAXS), protein-protein interaction assays and phenotypic characterization using various types of cellular imaging, e.g. fluorescence microscopy, Transmission Electron Microscopy (TEM), and Soft X-ray Tomography (SXT).

  16. Laser Sounder for Measuring Atmospheric CO2 Concentrations: Progress Toward Ascends

    Science.gov (United States)

    Abshire, J. B.; Kawa, S. R.; Riris, H.; Allan, G. R.; Sun, X.; Stephen, M. A.; Wilson, E.; Burris, J. F.; Mao, J.

    2008-01-01

    The next generation of space-based, active remote sensing instruments for measurement of tropospheric CO2 promises a capability to quantify global carbon sources and sinks at regional scales. Active (laser) methods will extend CO2 measurement coverage in time, space, and perhaps precision such that the underlying mechanisms for carbon exchange at the surface can be understood with .sufficient detail to confidently project the future of carbon-climate interaction and the influence of remediative policy actions. The recent Decadal Survey for Earth Science by the US National Research Council has recommended such a mission called the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) for launch in 2013-2016. We have been developing a laser technique for measurement of tropospheric CO2 for a number of years. Our immediate goal is to develop and demonstrate the method and instrument technology that will permit measurements of the CO2 column abundance over a horizontal path and from aircraft at the few-ppmv level. Our longer-term goal is to demonstrate the required capabilities of the technique, develop a space mission approach, and design the instrument for an ASCENDS-type mission. Our approach is to use a dual channel laser absorption spectrometer (i.e., differential absorption in altimeter mode), which continuously measures from a near-polar circular orbit. We use several co-aligned tunable fiber laser transmitters allowing simultaneous measurement of the absorption from a CO2 line in the 1570 nm band, O2 extinction in the oxygen A-band (near 765 nm), and aerosol backscatter in the same measurement path. We measure the energy of the laser echoes at nadir reflected from land and water surfaces, day and night. The lasers have spectral widths much narrower than the gas absorption lines and are turned on and off the selected CO2 and O2 lines at kHz rates. The gas extinction and column densities for the CO2 and O2 gases are estimated from the ratio of

  17. Effect of polymer concentration on the structure and performance of PEI hollow fiber membrane contactor for CO2 stripping.

    Science.gov (United States)

    Naim, R; Ismail, A F

    2013-04-15

    A series of polyetherimide (PEI) hollow fiber membranes with various polymer concentrations (13-16 wt.%) for CO2 stripping process in membrane contactor application was fabricated via wet phase inversion method. The PEI membranes were characterized in terms of liquid entry pressure, contact angle, gas permeation and morphology analysis. CO2 stripping performance was investigated via membrane contactor system in a stainless steel module with aqueous diethanolamine as liquid absorbent. The hollow fiber membranes showed decreasing patterns in gas permeation, contact angle, mean pore size and effective surface porosity with increasing polymer concentration. On the contrary, wetting pressure of PEI membranes has enhanced significantly with polymer concentration. Various polymer concentrations have different effects on the CO2 stripping flux in which membrane with 14 wt.% polymer concentration showed the highest stripping flux of 2.7 × 10(-2)mol/m(2)s. From the performance comparison with other commercial membrane, it is anticipated that the PEI membrane has a good prospect in CO2 stripping via membrane contactor.

  18. Soil and biomass carbon pools in model communities of tropical plants under elevated CO2.

    Science.gov (United States)

    Arnone, J A; Körner, Ch

    1995-09-01

    The experimental data presented here relate to the question of whether terrestrial ecosystems will sequester more C in their soils, litter and biomass as atmospheric CO2 concentrations rise. Similar to our previous study with relatively fertile growth conditions (Körner and Arnone 1992), we constructed four rather nutrient-limited model communities of moist tropical plant species in greenhouses (approximately 7 m(2) each). Plant communities were composed of seven species (77 individuals per community) representing major taxonomic groups and various life forms found in the moist tropics. Two ecosystems were exposed to 340 μl CO2 l(-1) and two to 610 μl l(-1) for 530 days of humid tropical growth conditions. In order to permit precise determination of C deposition in the soil, plant communities were initially established in C-free unwashed quartz sand. Soils were then amended with known amounts of organic matter (containing C and nutrients). Mineral nutrients were also supplied over the course of the experiment as timed-release full-balance fertilizer pellets. Soils represented by far the largest repositories for fixed C in all ecosystems. Almost 5 times more C (ca. 80% of net C fixation) was sequestered in the soil than in the biomass, but this did not differ between CO2 treatments. In addition, at the whole-ecosystem level we found a remarkably small and statistically non-significant increase in C sequestration (+4%; the sum of C accretion in the soil, biomass, litter and necromass). Total community biomass more than quadrupled during the experiment, but at harvest was, on average, only 8% greater (i.e. 6% per year; n.s.) under elevated CO2, mainly due to increased root biomass (+15%, P=0.12). Time courses of leaf area index of all ecosystems suggested that canopy expansion was approaching steady state by the time systems were harvested. Net primary productivity (NPP) of all ecosystems-i.e. annual accumulation of biomass, necromass, and leaf litter (but not

  19. Pore-scaling Modeling of Physical Property Changes During CO2 Injection into Sandstone

    Science.gov (United States)

    Keehm, Y.; Yoo, G.

    2009-12-01

    Carbon dioxide is a green-house gas and is believed to be an important factor in global warming and climate change. Many countries around the world are working on reducing and sequestrating CO2 to follow international regulations. One of promising area for CO2 sequestration is the storage in geological formation. To accurately determine the performance of geological injection and storage, quantification and monitoring of the physical property changes are essential. In this paper, we are presenting a new approach for the monitoring of CO2 sequestration in sandstone using pore-scale simulation techniques. The method consists of three steps: 1) acquisition of high-resolution pore microstructures by X-ray micro-tomography; 2) CO2 injection simulation using lattice-Boltzmann (LB) two-phase flow simulation; and 3) FEM property simulations (electrical and elastic) at different CO2 saturations during the injection. We use three different sandstone samples: sand-pack, Berea sandstone, and B2 sandstone from offshore of Korea. The porosity of the sand-pack is 42% and that of two sandstone samples is around 17%. The digital pore structures were obtained by X-ray micro-tomography with a spatial resolution of 2 micron. The LB two-phase flow simulation is then conducted by injecting CO2 into fully water-saturated samples and gives a realistic movement of CO2 in the pore structure. At each CO2 saturation, electrical and elastic properties are determined by pore-scale FEM simulation techniques. The electrical conductivity decreases almost linearly as CO2 saturations increases; however, the P-wave velocity decrease more rapidly at the low CO2 saturation (up to 30%), than at higher saturation. S-wave velocity does not show any significant changes. The higher porosity rock shows more sensitivity to saturation changes. The modeling shows that we can have quantitative relations between physical properties and CO2 saturation, which can be used to determine injection performance and

  20. Net sea-air CO2 fluxes and modelled pCO2 in the southwestern subtropical Atlantic continental shelf during spring 2010 and summer 2011

    Science.gov (United States)

    Ito, Rosane Gonçalves; Garcia, Carlos Alberto Eiras; Tavano, Virginia Maria

    2016-05-01

    Sea-air CO2 fluxes over continental shelves vary substantially in time on both seasonal and sub-seasonal scales, driven primarily by variations in surface pCO2 due to several oceanic mechanisms. Furthermore, coastal zones have not been appropriately considered in global estimates of sea-air CO2 fluxes, despite their importance to ecology and to productivity. In this work, we aimed to improve our understanding of the role played by shelf waters in controlling sea-air CO2 fluxes by investigating the southwestern Atlantic Ocean (21-35°S) region, where physical, chemical and biological measurements were made on board the Brazilian R. V. Cruzeiro do Sul during late spring 2010 and early summer 2011. Features such as discharge from the La Plata River, intrusions of tropical waters on the outer shelf due to meandering and flow instabilities of the Brazil Current, and coastal upwelling in the Santa Marta Grande Cape and São Tomé Cape were detected by both in situ measurements and ocean colour and thermal satellite imagery. Overall, shelf waters in the study area were a source of CO2 to the atmosphere, with an average of 1.2 mmol CO2 m-2 day-1 for the late spring and 11.2 mmol CO2 m-2 day-1 for the early summer cruises. The spatial variability in ocean pCO2 was associated with surface ocean properties (temperature, salinity and chlorophyll-a concentration) in both the slope and shelf waters. Empirical algorithms for predicting temperature-normalized surface ocean pCO2 as a function of surface ocean properties were shown to perform well in both shelf and slope waters, except (a) within cyclonic eddies produced by baroclinic instability of the Brazil Current as detected by satellite SST imagery and (b) in coastal upwelling regions. In these regions, surface ocean pCO2 values were higher as a result of upwelled CO2-enriched subsurface waters. Finally, a pCO2 algorithm based on both sea surface temperature and surface chlorophyll-a was developed that enabled the spatial

  1. CO2浓度升高对作物生理影响研究进展%The Effects of CO2 Concentration Enrichment on Crops Physiology

    Institute of Scientific and Technical Information of China (English)

    姜帅; 居辉; 刘勤

    2013-01-01

      农业是对气候变化反应最为敏感部门,CO2浓度升高又是气候变化的主要特征之一,同时CO2作为作物的光合底物,对作物的生长发育以及生理生化过程具有重要影响。气候变化对农业影响关系到国家粮食安全,明确CO2浓度升高对作物的生理影响是客观评价气候变化对作物生产影响的重要组成部分,对正确认识粮食供给能力具有重要意义。综述了高浓度CO2对作物光合作用的影响,包括作物光合作用对短期和长期高CO2浓度的响应;归纳了高浓度CO2对蒸腾作用的影响;总结了高浓度CO2对水分利用率的影响;分析了高浓度CO2对作物呼吸的影响。分析认为,短期CO2浓度升高提高了作物光合作用,但持续性的高CO2浓度对光合的促进作用由于光合适应而有所减弱,CO2浓度升高使气孔开张度减小或关闭,气孔导度下降,作物蒸腾作用降低,水分利用效率提高,最后提出了目前研究中的一些不足和今后需要深入研究方向。%Agriculture is a particularly sensitive part to changes in climate variability. The elevated CO2 is one of main features of climate change. As the raw materials of photosynthesis, CO2 has essential effects on the growth and development of crops and some physiological and biochemical process. Because the effects of climate change on the agriculture are important to national food security, so to clearly find out effects of the elevated CO2 on the physiological process of crops is a major part of evaluating the effects of climate change on the production of crops. This is very important for us to know the food supply capacity. In this review, we summarized the photosynthesis of crops responded on the elevated CO2 included a transient and long-term respond to it, generalized the impacts of the elevated CO2 on the transpiration rate of crops, summed up water use efficiency of crops responded on the elevated CO2

  2. High resolution modeling of CO2 over Europe: implications for representation errors of satellite retrievals

    Directory of Open Access Journals (Sweden)

    T. Koch

    2010-01-01

    Full Text Available Satellite retrievals for column CO2 with better spatial and temporal sampling are expected to improve the current surface flux estimates of CO2 via inverse techniques. However, the spatial scale mismatch between remotely sensed CO2 and current generation inverse models can induce representation errors, which can cause systematic biases in flux estimates. This study is focused on estimating these representation errors associated with utilization of satellite measurements in global models with a horizontal resolution of about 1 degree or less. For this we used simulated CO2 from the high resolution modeling framework WRF-VPRM, which links CO2 fluxes from a diagnostic biosphere model to a weather forecasting model at 10×10 km2 horizontal resolution. Sub-grid variability of column averaged CO2, i.e. the variability not resolved by global models, reached up to 1.2 ppm with a median value of 0.4 ppm. Statistical analysis of the simulation results indicate that orography plays an important role. Using sub-grid variability of orography and CO2 fluxes as well as resolved mixing ratio of CO2, a linear model can be formulated that could explain about 50% of the spatial patterns in the systematic (bias or correlated error component of representation error in column and near-surface CO2 during day- and night-times. These findings give hints for a parameterization of representation error which would allow for the representation error to taken into account in inverse models or data assimilation systems.

  3. Contribution of various carbon sources toward isoprene synthesis mediated by altered atmospheric CO2 concentrations

    Science.gov (United States)

    Trowbridge, A. M.; Asensio, D.; Eller, A. S.; Wilkinson, M. J.; Schnitzler, J.; Jackson, R. B.; Monson, R. K.

    2010-12-01

    Biogenically released isoprene is abundant in the troposphere, and has an essential function in determining atmospheric chemistry and important implications for plant metabolism. As a result, considerable effort has been made to understand the underlying mechanisms driving isoprene synthesis, particularly in the context of a rapidly changing environment. Recently, a number of studies have focused on the contribution of recently assimilated carbon as opposed to stored/alternative intracellular or extracellular carbon sources in the context of environmental stress. Results from these studies can offer clues about the importance of various carbon pools for isoprene production and elucidate the corresponding physiological changes that are responsible for these dynamic shifts in carbon allocation. We performed a 13CO2-labeling study using proton-transfer-reaction mass spectrometry (PTR-MS) to examine the kinetics of the incorporation of recently assimilated photosynthate into isoprene emitted from poplar (Poplar x canescens) under sub-ambient, ambient, and elevated CO2 growth conditions. We also monitored the importance of pyruvate-derived carbon for isoprene biosynthesis and obtained a detailed account of where individual carbons are derived from by analyzing the ratio of the 3C subunit of isoprene (M41+) (a fragment which contains two carbons from pyruvate) to the ratio of the parent isoprene molecule (M69+). Dynamics in the M41+:M69+ ratio indicate that recently assimilated carbon is incorporated into the pyruvate carbon pool slowly across all CO2 treatments and is therefore accessible for isoprene synthesis at a slower rate when compared to substrates derived directly from photosynthesis. Analysis of the rates of change for individual masses indicated that the carbon pools in trees grown in sub-ambient CO2 (200 ppm) are labeled ~2 times faster than those of trees grown in ambient or elevated CO2. Analysis of the total isoprene emission rates between treatments

  4. The response of ecosystem water-use efficiency to rising atmospheric CO2 concentrations: sensitivity and large-scale biogeochemical implications.

    Science.gov (United States)

    Knauer, Jürgen; Zaehle, Sönke; Reichstein, Markus; Medlyn, Belinda E; Forkel, Matthias; Hagemann, Stefan; Werner, Christiane

    2017-03-01

    Ecosystem water-use efficiency (WUE) is an important metric linking the global land carbon and water cycles. Eddy covariance-based estimates of WUE in temperate/boreal forests have recently been found to show a strong and unexpected increase over the 1992-2010 period, which has been attributed to the effects of rising atmospheric CO2 concentrations on plant physiology. To test this hypothesis, we forced the observed trend in the process-based land surface model JSBACH by increasing the sensitivity of stomatal conductance (gs ) to atmospheric CO2 concentration. We compared the simulated continental discharge, evapotranspiration (ET), and the seasonal CO2 exchange with observations across the extratropical northern hemisphere. The increased simulated WUE led to substantial changes in surface hydrology at the continental scale, including a significant decrease in ET and a significant increase in continental runoff, both of which are inconsistent with large-scale observations. The simulated seasonal amplitude of atmospheric CO2 decreased over time, in contrast to the observed upward trend across ground-based measurement sites. Our results provide strong indications that the recent, large-scale WUE trend is considerably smaller than that estimated for these forest ecosystems. They emphasize the decreasing CO2 sensitivity of WUE with increasing scale, which affects the physiological interpretation of changes in ecosystem WUE.

  5. Regional-scale geostatistical inverse modeling of North American CO2 fluxes: a synthetic data study

    Directory of Open Access Journals (Sweden)

    A. M. Michalak

    2010-07-01

    Full Text Available A series of synthetic data experiments is performed to investigate the ability of a regional atmospheric inversion to estimate grid-scale CO2 fluxes during the growing season over North America. The inversions are performed within a geostatistical framework without the use of any prior flux estimates or auxiliary variables, in order to focus on the atmospheric constraint provided by the nine towers collecting continuous, calibrated CO2 measurements in 2004. Using synthetic measurements and their associated concentration footprints, flux and model-data mismatch covariance parameters are first optimized, and then fluxes and their uncertainties are estimated at three different temporal resolutions. These temporal resolutions, which include a four-day average, a four-day-average diurnal cycle with 3-hourly increments, and 3-hourly fluxes, are chosen to help assess the impact of temporal aggregation errors on the estimated fluxes and covariance parameters. Estimating fluxes at a temporal resolution that can adjust the diurnal variability is found to be critical both for recovering covariance parameters directly from the atmospheric data, and for inferring accurate ecoregion-scale fluxes. Accounting for both spatial and temporal a priori covariance in the flux distribution is also found to be necessary for recovering accurate a posteriori uncertainty bounds on the estimated fluxes. Overall, the results suggest that even a fairly sparse network of 9 towers collecting continuous CO2 measurements across the continent, used with no auxiliary information or prior estimates of the flux distribution in time or space, can be used to infer relatively accurate monthly ecoregion scale CO2 surface fluxes over North America within estimated uncertainty bounds. Simulated random transport error is shown to decrease the quality of flux estimates in under-constrained areas at the ecoregion scale, although the uncertainty bounds remain realistic. While these synthetic

  6. Importance of fossil fuel emission uncertainties over Europe for CO2 modeling: model intercomparison

    NARCIS (Netherlands)

    Peylin, P.; Houweling, S.; Krol, M.C.|info:eu-repo/dai/nl/078760410; Karstens, U.; Pieterse, G.|info:eu-repo/dai/nl/304840858; Ciais, P.; Heimann, M.

    2011-01-01

    Inverse modeling techniques used to quantify surface carbon fluxes commonly assume that the uncertainty of fossil fuel CO2 (FFCO2) emissions is negligible and that intra-annual variations can be neglected. To investigate these assumptions, we analyzed the differences between four fossil fuel

  7. Effects of temperature, CO 2/O 2 concentrations and light intensity on cellular multiplication of microalgae, Euglena gracilis

    Science.gov (United States)

    Kitaya, Y.; Azuma, H.; Kiyota, M.

    Microalgae culture is likely to play an important role in aquatic food production modules in bioregenerative systems for producing feeds for fish, converting CO 2 to O 2 and remedying water quality as well as aquatic higher plants. In the present study, the effects of culture conditions on the cellular multiplication of microalgae, Euglena gracilis, was investigated as a fundamental study to determine the optimum culture conditions for microalgae production in aquatic food production modules including both microalgae culture and fish culture systems. E. gracilis was cultured under conditions with five levels of temperatures (25-33 °C), three levels of CO 2 concentrations (2-6%), five levels of O 2 concentrations (10-30%), and six levels of photosynthetic photon flux (20-200 μmol m -2 s -1). The number of Euglena cells in a certain volume of solution was monitored with a microscope under each environmental condition. The multiplication rate of the cells was highest at temperatures of 27-31 °C, CO 2 concentration of 4%, O 2 concentration of 20% and photosynthetic photon flux of about 100 μmol m -2 s -1. The results demonstrate that E. gracilis could efficiently produce biomass and convert CO 2 to O 2 under relatively low light intensities in aquatic food production modules.

  8. Responses of Irrigated Winter Wheat Yield in North China to Increased Temperature and Elevated CO2 Concentration

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    North China is one of the main regions of irrigated winter wheat production in China. Climate warming is apparent in this region, especially during the growing season of winter wheat. To understand how the yield of irrigated winter wheat in North China might be aff ected by climate warming and CO2 concentration enrichment in future, a set of manipulative fi eld experiments was conducted in a site in the North China Plain under increased temperature and elevated CO2 concentration by using open top chambers and infrared radiator heaters. The results indicated that an average temperature increase of 1.7℃in the growing season with CO2 concentration of 560 µmol mol−1 did not reduce the yield of irrigated winter wheat. The thousand-kernel weight of winter wheat did not change signifi cantly despite improvement in the fi lling rate, because the increased temperature shortened the duration of grain fi lling. The number of eff ective panicles and the grain number per ear of winter wheat did not show signifi cant changes. There was a large increase in the shoot biomass because of the increase in stem number and plant height. Consequently, under the prescribed scenario of asymmetric temperature increases and elevated CO2 concentration, the yield of irrigated winter wheat in North China is not likely to change signifi cantly, but the harvest index of winter wheat is likely to be greatly reduced.

  9. Effects of temperature, CO2/O2 concentrations and light intensity on cellular multiplication of microalgae, Euglena gracilis

    Science.gov (United States)

    Kitaya, Y.; Azuma, H.; Kiyota, M.

    2005-01-01

    Microalgae culture is likely to play an important role in aquatic food production modules in bioregenerative systems for producing feeds for fish, converting CO2 to O2 and remedying water quality as well as aquatic higher plants. In the present study, the effects of culture conditions on the cellular multiplication of microalgae, Euglena gracilis, was investigated as a fundamental study to determine the optimum culture conditions for microalgae production in aquatic food production modules including both microalgae culture and fish culture systems. E. gracilis was cultured under conditions with five levels of temperatures (25-33 degrees C), three levels of CO2 concentrations (2-6%), five levels of O2 concentrations (10-30%), and six levels of photosynthetic photon flux (20-200 micromoles m-2 s-1). The number of Euglena cells in a certain volume of solution was monitored with a microscope under each environmental condition. The multiplication rate of the cells was highest at temperatures of 27-31 degrees C, CO2 concentration of 4%, O2 concentration of 20% and photosynthetic photon flux of about 100 micromoles m-2 s-1. The results demonstrate that E. gracilis could efficiently produce biomass and convert CO2 to O2 under relatively low light intensities in aquatic food production modules. c2005 Published by Elsevier Ltd on behalf of COSPAR.

  10. Assessment of aversion to different concentrations of CO2 gas by weaned pigs using an approach-avoidance paradigm

    Science.gov (United States)

    The objective of this study was to examine the aversiveness of carbon dioxide (CO2) to weaned pigs using approach-avoidance and condition place avoidance paradigms. A preference-testing device was custom designed with two connected chambers maintained at static gas concentrations. The control chambe...

  11. The influence of irradiance and external CO2 concentration on photosynthesis of different tomato genotypes

    NARCIS (Netherlands)

    Nilwik, H.J.M.; Gosiewski, W.; Bierhuizen, J.F.

    1982-01-01

    With 4 genotypes of tomato, irradiance and CO2-response curves of net photosynthesis were analysed by means of curve fitting. Estimated values of the light compensation point Ic showed small but significant differences between the genotypes, the overall value being in the order of 8 W m−2. The photo

  12. Raw Baseline Concentrations and Environmental Controls on Background CO2 and CH4 for Sites Across Canada

    Science.gov (United States)

    Fougère, C. R.; Risk, D. A.; Lavoie, M.; Baillie, J.; Atherton, E. E.; Marshall, A. D.; Williams, J. P.; MacKay, K.; O'Connell, E.; Macintyre, C. M.; Spafford, L. A.

    2016-12-01

    Concentrations of gases in the lower atmosphere are controlled by spatially and temporally heterogeneous factors such as air temperature, biological activity and degree of industrial development. Seeing as how baseline concentrations are often required for studies of environmental change, we need a better understanding of the spatiotemporal controls on baseline atmospheric gas concentrations. In this study we collected >2.5M CO2 and CH4 concentration measurements across Canada over the course of two years and multiple seasons, by driving laser-based spectrometers in excess of 100,000 linear km. Geo-located concentration data were acquired at a frequency of 1 Hz and from an approximate height of 1.5 m. A signal processing algorithm was used to remove short-term plume features that were related to local industrial activity, so as to derive background concentrations that were more generally representative of natural landscape variation. We assessed relationships between background concentrations and environmental factors for each province, as well as areas with and without a high degree of oil and gas production. We also compared concentration signatures between winter and summer for some provinces, and were additionally able to provide a full season-by-season comparison for the province of Saskatchewan. Results suggest that temperature is the primary spatiotemporal control on CO2 and CH4 background concentrations, suggesting that the biosphere is the dominant regulator of concentrations near the ground surface. Local wind speeds and atmospheric pooling were comparatively less useful predictors of landscape CO2 and CH4 variation. These results will facilitate improved CO2 and CH4 baseline data estimates for environmental studies of many types in non-urban environments.

  13. A new simulation model and its application in CO2 short-circuiting transfer welding

    Institute of Scientific and Technical Information of China (English)

    胡连海; 李桓; 李俊岳; 杨立军

    2002-01-01

    A new simulation model of CO2 short-circuiting transfer welding may be employed to develop a new pattern of welding machine and to predict welding process parameters to obtain the optimum welding technology properties. In this paper, a new simulating model is developed according to the AWP (adapting welding physics process) waveform control method. Good agreement is shown between the predicted and experimentally determined results. The model will make an important promotion in the development of CO2 arc welding technique.

  14. CO2 migration in the vadose zone: experimental and numerical modelling of controlled gas injection

    Science.gov (United States)

    gasparini, andrea; credoz, anthony; grandia, fidel; garcia, david angel; bruno, jordi

    2014-05-01

    The mobility of CO2 in the vadose zone and its subsequent transfer to the atmosphere is a matter of concern in the risk assessment of the geological storage of CO2. In this study the experimental and modelling results of controlled CO2 injection are reported to better understanding of the physical processes affecting CO2 and transport in the vadose zone. CO2 was injected through 16 micro-injectors during 49 days of experiments in a 35 m3 experimental unit filled with sandy material, in the PISCO2 facilities at the ES.CO2 centre in Ponferrada (North Spain). Surface CO2 flux were monitored and mapped periodically to assess the evolution of CO2 migration through the soil and to the atmosphere. Numerical simulations were run to reproduce the experimental results, using TOUGH2 code with EOS7CA research module considering two phases (gas and liquid) and three components (H2O, CO2, air). Five numerical models were developed following step by step the injection procedure done at PISCO2. The reference case (Model A) simulates the injection into a homogeneous soil(homogeneous distribution of permeability and porosity in the near-surface area, 0.8 to 0.3 m deep from the atmosphere). In another model (Model B), four additional soil layers with four specific permeabilities and porosities were included to predict the effect of differential compaction on soil. To account for the effect of higher soil temperature, an isothermal simulation called Model C was also performed. Finally, the assessment of the rainfall effects (soil water saturation) on CO2 emission on surface was performed in models called Model D and E. The combined experimental and modelling approach shows that CO2 leakage in the vadose zone quickly comes out through preferential migration pathways and spots with the ranges of fluxes in the ground/surface interface from 2.5 to 600 g·m-2·day-1. This gas channelling is mainly related to soil compaction and climatic perturbation. This has significant implications to

  15. Multi-scale modeling of CO2 dispersion leaked from seafloor off the Japanese coast.

    Science.gov (United States)

    Kano, Yuki; Sato, Toru; Kita, Jun; Hirabayashi, Shinichiro; Tabeta, Shigeru

    2010-02-01

    A numerical simulation was conducted to predict the change of pCO(2) in the ocean caused by CO(2) leaked from an underground aquifer, in which CO(2) is purposefully stored. The target space of the present model was the ocean above the seafloor. The behavior of CO(2) bubbles, their dissolution, and the advection-diffusion of dissolved CO(2) were numerically simulated. Here, two cases for the leakage rate were studied: an extreme case, 94,600 t/y, which assumed that a large fault accidentally connects the CO(2) reservoir and the seafloor; and a reasonable case, 3800 t/y, based on the seepage rate of an existing EOR site. In the extreme case, the calculated increase in DeltapCO(2) experienced by floating organisms was less than 300 ppm, while that for immobile organisms directly over the fault surface periodically exceeded 1000 ppm, if momentarily. In the reasonable case, the calculated DeltapCO(2) and pH were within the range of natural fluctuation. Copyright 2009 Elsevier Ltd. All rights reserved.

  16. Numerical Simulation Study on the Impacts of Tropospheric O3 and CO2 Concentration Changes on Winter Wheat. Part Ⅱ:Simulation Results and Analyses

    Institute of Scientific and Technical Information of China (English)

    ZHENG Changling; WANG Chunyi

    2006-01-01

    With the rapid development of industrialization and urbanization, the enrichment of tropospheric ozone and carbon dioxide concentration at striking rates has caused effects on biosphere, especially on crops. It is generally accepted that the increase of CO2 concentration will have obverse effects on plant productivity while ozone is reported as the air pollutant most damaging to agricultural crops and other plants. The Model of Carbon and Nitrogen Biogeochemistry in Agroecosystems (DNDC) was adapted to evaluate simultaneously impacts of climate change on winter wheat.Growth development and yield formation of winter wheat under different Os and CO2 concentration conditions are simulated with the improved DNDC model whose structure has been described in another paper. Through adjusting the DNDC model applicability, winter wheat growth and development in Gucheng Station were simulated well in 1993 and 1999, which is in favor of modifying the model further. The model was validated against experiment observation, including development stage data, leaf area index, each organ biomass, and total aboveground biomass. Sensitivity tests demonstrated that the simulated results in development stage and biomass were sensitive to temperature change. The main conclusions of the paper are the following: 1) The growth and yield of winter wheat under CO2 concentration of 500 ppmv, 700 ppmv and the current ozone concentration are simulated respectively by the model. The results are well fitted with the observed data of OTCs experiments. The results show that increase of CO2 concentration may improve the growth of winter wheat and elevate the yield. 2) The growth and yield of winter wheat under O3 concentration of 50 ppbv, 100 ppbv, 200 ppbv and the based concentration CO2 are simulated respectively by the model. The simulated curves of stem, leaf, and spike organs growth as well as leaf area index are well accounted with the observed data. The results reveal that ozone has negative

  17. CO2 conversion by plasma technology: insights from modeling the plasma chemistry and plasma reactor design

    Science.gov (United States)

    Bogaerts, A.; Berthelot, A.; Heijkers, S.; Kolev, St.; Snoeckx, R.; Sun, S.; Trenchev, G.; Van Laer, K.; Wang, W.

    2017-06-01

    In recent years there has been growing interest in the use of plasma technology for CO2 conversion. To improve this application, a good insight into the underlying mechanisms is of great importance. This can be obtained from modeling the detailed plasma chemistry in order to understand the chemical reaction pathways leading to CO2 conversion (either in pure form or mixed with another gas). Moreover, in practice, several plasma reactor types are being investigated for CO2 conversion, so in addition it is essential to be able to model these reactor geometries so that their design can be improved, and the most energy efficient CO2 conversion can be achieved. Modeling the detailed plasma chemistry of CO2 conversion in complex reactors is, however, very time-consuming. This problem can be overcome by using a combination of two different types of model: 0D chemical reaction kinetics models are very suitable for describing the detailed plasma chemistry, while the characteristic features of different reactor geometries can be studied by 2D or 3D fluid models. In the first instance the latter can be developed in argon or helium with a simple chemistry to limit the calculation time; however, the ultimate aim is to implement the more complex CO2 chemistry in these models. In the present paper, examples will be given of both the 0D plasma chemistry models and the 2D and 3D fluid models for the most common plasma reactors used for CO2 conversion in order to emphasize the complementarity of both approaches. Furthermore, based on the modeling insights, the paper discusses the possibilities and limitations of plasma-based CO2 conversion in different types of plasma reactors, as well as what is needed to make further progress in this field.

  18. Kinetic study of CO2 reaction with CaO by a modified random pore model

    Directory of Open Access Journals (Sweden)

    Nouri S.M.M.

    2016-03-01

    Full Text Available In this work, a modified random pore model was developed to study the kinetics of the carbonation reaction of CaO. Pore size distributions of the CaO pellets were measured by nitrogen adsorption and mercury porosimetry methods. The experiments were carried out in a thermogravimeter at different isothermal temperatures and CO2 partial pressures. A fractional concentration dependency function showed the best accuracy for predicting the intrinsic rate of reaction. The activation energy was determined as 11 kcal/mole between 550–700°C. The effect of product layer formation was also taken into account by using the variable product layer diffusivity. Also, the model was successfully predicted the natural lime carbonation reaction data extracted from the literature.

  19. Supercritical CO2 extraction of oil and omega-3 concentrate from Sacha inchi (Plukenetia volubilis L. from Antioquia, Colombia

    Directory of Open Access Journals (Sweden)

    D. M. Triana-Maldonado

    2017-03-01

    Full Text Available Sacha inchi (Plukenetia volubilis L. seeds were employed for oil extraction with supercritical CO2 at laboratory scale. The supercritical extraction was carried out at a temperature of 60 °C, pressure range of 400–500 bars and CO2 flow of 40–80 g/min. The maximum recovery was 58% in 180 min, favored by increasing the residence time of CO2 in the extraction tank. Subsequently, the process was evaluated at pilot scale reaching a maximum recovery of 60% in 105 min, with a temperature of 60 °C, pressure of 450 bars and CO2 flow of 1270 g/min. The fatty acid composition of the oil was not affected for an extraction period of 30–120 min. The Sacha inchi oil was fractionated with supercritical CO2 to obtain an omega-3 concentrate oil without finding a considerable increase in the proportion of this compound, due to the narrow range in the carbon number of fatty acids present in the oil (16–18 carbons, making it difficult for selective separation.

  20. Removal of Low-Molecular Weight Aldehydes by Selected Houseplants under Different Light Intensities and CO2 Concentrations

    Directory of Open Access Journals (Sweden)

    Jian Li

    2016-11-01

    Full Text Available The removal of five low-molecular weight aldehydes by two houseplants (Schefflera octophylla (Lour. Harms and Chamaedorea elegans were investigated in a laboratory simulation environment with short-term exposure to different low light intensities and CO2 concentrations. Under normal circumstances, the C1–C5 aldehyde removal rates of Schefflera octophylla (Lour. Harms and Chamaedorea elegans (Lour. Harms ranged from 0.311 μmol/m2/h for valeraldehyde to 0.677 μmol/m2/h for formaldehyde, and 0.526 μmol/m2/h for propionaldehyde to 1.440 μmol/m2/h for formaldehyde, respectively. However, when the light intensities varied from 0 to 600 lx, a significant correlation between the aldehyde removal rate and the light intensity was found. Moreover, the CO2 experiments showed that the total aldehyde removal rates of Schefflera octophylla (Lour. Harms and Chamaedorea elegans (Lour. Harms decreased 32.0% and 43.2%, respectively, with increasing CO2 concentrations from 350 ppmv to 1400 ppmv. This might be explained by the fact that the excessive CO2 concentration decreased the stomatal conductance which limited the carbonyl uptake from the stomata.

  1. CO2 capture from the atmosphere and simultaneous concentration using zeolites and amine-grafted SBA-15.

    Science.gov (United States)

    Stuckert, Nicholas R; Yang, Ralph T

    2011-12-01

    CO(2) capture from the atmosphere and concentration by cyclic adsorption-desorption processes are studied for the first time. New high microporosity materials, zeolite types Li-LSX and K-LSX, are compared to zeolite NaX and amine-grafted SBA-15 with low amine content. Breakthrough performance showed low silica type X (LSX) to have the most promise for application in dry conditions and capable of high space velocities of at least 63,000 h(-1), with minimal spreading of the CO(2) breakthrough curve. Amine-grafted silica was the only adsorbent able to operate in wet conditions, but at a lower space velocity of 1500 h(-1), due to slower uptake rates. The results illustrate that the uptake rate is as important as the equilibrium adsorbed amount in determining the cyclic process performance. Li-LSX was found to have double the capacity of zeolite NaX at atmospheric conditions, also higher than all other reported zeolites. It is further demonstrated that by using a combined temperature and vacuum swing cycle, the CO(2) concentration in the desorption product is >90% for all adsorbents in pellet form. This is the first report of such high CO(2) product concentrations from a single cycle, using atmospheric air.

  2. Technical Note: Long-term memory effect in the atmospheric CO2 concentration at Mauna Loa

    Directory of Open Access Journals (Sweden)

    M. Efstathiou

    2006-11-01

    Full Text Available The monthly mean values of the atmospheric carbon dioxide concentration derived from in-situ air samples collected at Mauna Loa Observatory, Hawaii, during 1958–2004 (the longest continuous record available in the world are analyzed by employing the detrended fluctuation analysis to detect scaling behavior in this time series. The main result is that the fluctuations of carbon dioxide concentrations exhibit long-range power-law correlations (long memory with lag times ranging from four months to eleven years, which correspond to 1/f noise. This result indicates that random perturbations in the carbon dioxide concentrations give rise to noise, characterized by a frequency spectrum following a power-law with exponent that approaches to one; the latter shows that the correlation times grow strongly. This feature is pointing out that a correctly rescaled subset of the original time series of the carbon dioxide concentrations resembles the original time series. Finally, the power-law relationship derived from the real measurements of the carbon dioxide concentrations could also serve as a tool to improve the confidence of the atmospheric chemistry-transport and global climate models.

  3. Technical Note: Long-term memory effect in the atmospheric CO2 concentration at Mauna Loa

    Directory of Open Access Journals (Sweden)

    C. Varotsos

    2007-01-01

    Full Text Available The monthly mean values of the atmospheric carbon dioxide concentration derived from in-situ air samples collected at Mauna Loa Observatory, Hawaii, USA during 1958–2004 (the longest continuous record available in the world are analyzed by employing the detrended fluctuation analysis to detect scaling behavior in this time series. The main result is that the fluctuations of carbon dioxide concentrations exhibit long-range power-law correlations (long memory with lag times ranging from four months to eleven years, which correspond to 1/f noise. This result indicates that random perturbations in the carbon dioxide concentrations give rise to noise, characterized by a frequency spectrum following a power-law with exponent that approaches to one; the latter shows that the correlation times grow strongly. This feature is pointing out that a correctly rescaled subset of the original time series of the carbon dioxide concentrations resembles the original time series. Finally, the power-law relationship derived from the real measurements of the carbon dioxide concentrations could also serve as a tool to improve the confidence of the atmospheric chemistry-transport and global climate models.

  4. 从树轮纤维素δ13C序列看树木生长对大气 CO2浓度变化的响应%Response of CO2 Concentration Parameters and Water-Use Efficiency Derived from Tree-Ring δ13C Series to Atmospheric CO2 Increase

    Institute of Scientific and Technical Information of China (English)

    陈拓; 秦大河; 任贾文; 孙维贞; 李江风

    2001-01-01

    The well-documented increase in CO2 content of atmosphere since the beginning of industrialization has been variously attributed to the anthropogenic activities, such as agricultural explosion, global deforestation and enhanced fossil fuel combustion and so on. It was estimated that about one third of anthropogenic CO2 released to atmosphere was taken up by terrestrial plants. To evaluate how the land carbon reservoir has been acting as a sink to the anthropogenic CO2 input to atmosphere, it is important to study how plants in forests physiologically adjust to the changing atmospheric conditions. This has been studied intensively using controlled experiments, but it has been difficuh to scale short-term observations to long term ecosystem-level response. However, models of carbon discrimination during carbon fixation show that Cs plants are not passive recorders: carbon isotopic variations are subjected to strong physiological control through leaf gas exchange regulation. Therefore, records of carbon discrimination in tree-ring cellulose could be used to study past variations of the ecophysiology of trees in reaction to environmental variations, in addition to the reconstruction of past environments. In this paper, based on the tree-ring series from Zhaosu County of Xinjiang, the changes of the ratio of CO2 concentration in the intercellular space of leaves to that-on the atmosphere (Ci/Ca), CO2 concentration in the intercellular space of leaves (Ci) and plant water-use efficiency (A/g) derivec[ from carbon isotope chronology were analyzed for the past 240 a. The results show a relatively constant Ci/Ca value of 0. 52 during the whole period, suggesting a strategy of response of plants to increased atmospheric CO2 concentration. Significant increasing trends of Ci and A/g are also found, implying more carbon being fixed; Further analysis shows that their changes are related to atmospheric CO2 concentration, thus it is demonstrated that trees maybe take up the

  5. Calcium, magnesium, and phosphorus metabolism, and parathyroid-calcitonin function during prolonged exposure to elevated CO2 concentrations on submarines.

    Science.gov (United States)

    Messier, A A; Heyder, E; Braithwaite, W R; McCluggage, C; Peck, A; Schaefer, K E

    1979-01-01

    Studies of calcium and phosphorus metabolism and acid-base balance were carried out on three Fleet Ballistic Missile (FBM) submarines during prolonged exposure to elevated concentrations of CO2. The average CO2 concentration in the submarine atmosphere during patrols ranged from 0.85% to 1% CO2. In the three studies, in which 9--15 subjects participated, the urinary excretion of calcium and phosphate fell during the first three weeks to a level commensurate with a decrease in plasma calcium and increase in phosphorus. In the fourth week of one patrol, a marked increase was found in urinary calcium excretion, associated with a rise in blood PCO2 and bicarbonate. Urinary calcium excretion decreased again during the 5th to 8th week, with a secondary decrease in blood pH and plasma calcium. During the third patrol, the time course of acid-base changes corresponded well with that found during the second patrol. There was a trend toward an increase in plasma calcium between the fourth and fifth week commensurate with the transient rise in pH and bicarbonate. Plasma parathyroid and calcitonin hormone activities were measured in two patrols and no significant changes were found. Hydroxyproline excretion decreased in the three-week study and remained unchanged in the second patrol, which lasted 57 days. It is suggested that during prolonged exposure to low levels of CO2 (up to 1% CO2), calcium metabolism is controlled by the uptake and release of CO2 in the bones. The resulting phases in bone buffering, rather than renal regulation, determine acid-base balance.

  6. Soil and Root Respiration Under Elevated CO2 Concentrations During Seedling Growth of Pinus sylvestris var. sylvestriformis

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The objectives of this study were to investigate the effect of higher CO2 concentrations (500 and 700 μmol mol-1) in atmosphere on total soil respiration and the contribution of root respiration to total soil respiration during seedling growth of Pinus sylvestris var. sylvestriformis. During the four growing seasons (May-October) from 1999 to 2003, the seedlings were exposed to elevated concentrations of CO2 in open-top chambers. The total soil respiration and contribution of root respiration were measured using an LI-6400-09 soil CO2 flux chamber on June 15 and October 8, 2003. To separate root respiration from total soil respiration, three PVC cylinders were inserted approximately 30 cm deep into the soil in each chamber. There were marked diurnal changes in air and soil temperatures on June 15. Both the total soil respiration and the soil respiration without roots showed a strong diurnal pattern, increasing from before sunrise to about 14:00in the afternoon and then decreasing before the next sunrise. No increase in the mean total soil respiration and mean soil respiration with roots severed was observed under the elevated CO2 treatments on June 15, 2003, as compared to the open field and control chamber with ambient CO2. However, on October 8, 2003, the total soil respiration and soil respiration with roots severed in the open field were lower than those in the control and elevated CO2 chambers. The mean contribution of root respiration measured on June 15, 2003, ranged from 8.3% to 30.5% and on October 8, 2003,from 20.6% to 48.6%.

  7. Modeling pCO2 variability in the Gulf of Mexico

    Directory of Open Access Journals (Sweden)

    Z. Xue

    2014-08-01

    Full Text Available A three-dimensional coupled physical–biogeochemical model was used to simulate and examine temporal and spatial variability of surface pCO2 in the Gulf of Mexico (GoM. The model is driven by realistic atmospheric forcing, open boundary conditions from a data-assimilative global ocean circulation model, and observed freshwater and terrestrial nutrient and carbon input from major rivers. A seven-year model hindcast (2004–2010 was performed and was validated against in situ measurements. The model revealed clear seasonality in surface pCO2. Based on the multi-year mean of the model results, the GoM is an overall CO2 sink with a flux of 1.34 × 1012 mol C yr−1, which, together with the enormous fluvial carbon input, is balanced by the carbon export through the Loop Current. A sensitivity experiment was performed where all biological sources and sinks of carbon were disabled. In this simulation surface pCO2 was elevated by ~ 70 ppm, providing the evidence that biological uptake is a primary driver for the observed CO2 sink. The model also provided insights about factors influencing the spatial distribution of surface pCO2 and sources of uncertainty in the carbon budget.

  8. VOLATILECALC: A silicate melt-H2O-CO2 solution model written in Visual Basic for excel

    Science.gov (United States)

    Newman, S.; Lowenstern, J. B.

    2002-01-01

    We present solution models for the rhyolite-H2O-CO2 and basalt-H2O-CO2 systems at magmatic temperatures and pressures below ~ 5000 bar. The models are coded as macros written in Visual Basic for Applications, for use within MicrosoftR Excel (Office'98 and 2000). The series of macros, entitled VOLATILECALC, can calculate the following: (1) Saturation pressures for silicate melt of known dissolved H2O and CO2 concentrations and the corresponding equilibrium vapor composition; (2) open- and closed-system degassing paths (melt and vapor composition) for depressurizing rhyolitic and basaltic melts; (3) isobaric solubility curves for rhyolitic and basaltic melts; (4) isoplethic solubility curves (constant vapor composition) for rhyolitic and basaltic melts; (5) polybaric solubility curves for the two end members and (6) end member fugacities of H2O and CO2 vapors at magmatic temperatures. The basalt-H2O-CO2 macros in VOLATILECALC are capable of calculating melt-vapor solubility over a range of silicate-melt compositions by using the relationships provided by Dixon (American Mineralogist 82 (1997) 368). The output agrees well with the published solution models and experimental data for silicate melt-vapor systems for pressures below 5000 bar. ?? 2002 Elsevier Science Ltd. All rights reserved.

  9. Fast Atmosphere-Ocean Model Runs with Large Changes in CO2

    Science.gov (United States)

    Russell, Gary L.; Lacis, Andrew A.; Rind, David H.; Colose, Christopher; Opstbaum, Roger F.

    2013-01-01

    How does climate sensitivity vary with the magnitude of climate forcing? This question was investigated with the use of a modified coupled atmosphere-ocean model, whose stability was improved so that the model would accommodate large radiative forcings yet be fast enough to reach rapid equilibrium. Experiments were performed in which atmospheric CO2 was multiplied by powers of 2, from 1/64 to 256 times the 1950 value. From 8 to 32 times, the 1950 CO2, climate sensitivity for doubling CO2 reaches 8 C due to increases in water vapor absorption and cloud top height and to reductions in low level cloud cover. As CO2 amount increases further, sensitivity drops as cloud cover and planetary albedo stabilize. No water vapor-induced runaway greenhouse caused by increased CO2 was found for the range of CO2 examined. With CO2 at or below 1/8 of the 1950 value, runaway sea ice does occur as the planet cascades to a snowball Earth climate with fully ice covered oceans and global mean surface temperatures near 30 C.

  10. Large divergence of satellite and Earth system model estimates of global terrestrial CO2 fertilization

    Science.gov (United States)

    Smith, W. Kolby; Reed, Sasha C.; Cleveland, Cory C.; Ballantyne, Ashley P; Anderegg, William R. L.; Wieder, William R.; Liu, Yi Y; Running, Steven W.

    2015-01-01

    Atmospheric mass balance analyses suggest that terrestrial carbon (C) storage is increasing, partially abating the atmospheric [CO2] growth rate, although the continued strength of this important ecosystem service remains uncertain. Some evidence suggests that these increases will persist owing to positive responses of vegetation growth (net primary productivity; NPP) to rising atmospheric [CO2] (that is, ‘CO2 fertilization’). Here, we present a new satellite-derived global terrestrial NPP data set, which shows a significant increase in NPP from 1982 to 2011. However, comparison against Earth system model (ESM) NPP estimates reveals a significant divergence, with satellite-derived increases (2.8 ± 1.50%) less than half of ESM-derived increases (7.6  ±  1.67%) over the 30-year period. By isolating the CO2 fertilization effect in each NPP time series and comparing it against a synthesis of available free-air CO2 enrichment data, we provide evidence that much of the discrepancy may be due to an over-sensitivity of ESMs to atmospheric [CO2], potentially reflecting an under-representation of climatic feedbacks and/or a lack of representation of nutrient constraints. Our understanding of CO2 fertilization effects on NPP needs rapid improvement to enable more accurate projections of future C cycle–climate feedbacks; we contend that better integration of modelling, satellite and experimental approaches offers a promising way forward.

  11. Evolution and challenges of dynamic global vegetation models for some aspects of plant physiology and elevated atmospheric CO2

    Science.gov (United States)

    Rezende, L. F. C.; Arenque, B. C.; Aidar, S. T.; Moura, M. S. B.; Von Randow, C.; Tourigny, E.; Menezes, R. S. C.; Ometto, J. P. H. B.

    2016-07-01

    Dynamic global vegetation models (DGVMs) simulate surface processes such as the transfer of energy, water, CO2, and momentum between the terrestrial surface and the atmosphere, biogeochemical cycles, carbon assimilation by vegetation, phenology, and land use change in scenarios of varying atmospheric CO2 concentrations. DGVMs increase the complexity and the Earth system representation when they are coupled with atmospheric global circulation models (AGCMs) or climate models. However, plant physiological processes are still a major source of uncertainty in DGVMs. The maximum velocity of carboxylation (Vcmax), for example, has a direct impact over productivity in the models. This parameter is often underestimated or imprecisely defined for the various plant functional types (PFTs) and ecosystems. Vcmax is directly related to photosynthesis acclimation (loss of response to elevated CO2), a widely known phenomenon that usually occurs when plants are subjected to elevated atmospheric CO2 and might affect productivity estimation in DGVMs. Despite this, current models have improved substantially, compared to earlier models which had a rudimentary and very simple representation of vegetation-atmosphere interactions. In this paper, we describe this evolution through generations of models and the main events that contributed to their improvements until the current state-of-the-art class of models. Also, we describe some main challenges for further improvements to DGVMs.

  12. Evolution and challenges of dynamic global vegetation models for some aspects of plant physiology and elevated atmospheric CO2.

    Science.gov (United States)

    Rezende, L F C; Arenque, B C; Aidar, S T; Moura, M S B; Von Randow, C; Tourigny, E; Menezes, R S C; Ometto, J P H B

    2016-07-01

    Dynamic global vegetation models (DGVMs) simulate surface processes such as the transfer of energy, water, CO2, and momentum between the terrestrial surface and the atmosphere, biogeochemical cycles, carbon assimilation by vegetation, phenology, and land use change in scenarios of varying atmospheric CO2 concentrations. DGVMs increase the complexity and the Earth system representation when they are coupled with atmospheric global circulation models (AGCMs) or climate models. However, plant physiological processes are still a major source of uncertainty in DGVMs. The maximum velocity of carboxylation (Vcmax), for example, has a direct impact over productivity in the models. This parameter is often underestimated or imprecisely defined for the various plant functional types (PFTs) and ecosystems. Vcmax is directly related to photosynthesis acclimation (loss of response to elevated CO2), a widely known phenomenon that usually occurs when plants are subjected to elevated atmospheric CO2 and might affect productivity estimation in DGVMs. Despite this, current models have improved substantially, compared to earlier models which had a rudimentary and very simple representation of vegetation-atmosphere interactions. In this paper, we describe this evolution through generations of models and the main events that contributed to their improvements until the current state-of-the-art class of models. Also, we describe some main challenges for further improvements to DGVMs.

  13. 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.

  14. Testing the Early Mars H2-CO2 Greenhouse Hypothesis with a 1-D Photochemical Model

    CERN Document Server

    Batalha, Natasha; Ramirez, Ramses; Kasting, James

    2015-01-01

    A recent study by Ramirez et al. (2014) demonstrated that an atmosphere with 1.3-4 bar of CO2 and H2O, in addition to 5-20% H2, could have raised the mean annual and global surface temperature of early Mars above the freezing point of water. Such warm temperatures appear necessary to generate the rainfall (or snowfall) amounts required to carve the ancient martian valleys. Here, we use our best estimates for early martian outgassing rates, along with a 1-D photochemical model, to assess the conversion efficiency of CO, CH4, and H2S to CO2, SO2, and H2. Our outgassing estimates assume that Mars was actively recycling volatiles between its crust and interior, as Earth does today. H2 production from serpentinization and deposition of banded iron-formations is also considered. Under these assumptions, maintaining an H2 concentration of ~1-2% by volume is achievable, but reaching 5% H2 requires additional H2 sources or a slowing of the hydrogen escape rate below the diffusion limit. If the early martian atmosphere...

  15. Identification of CO2 disposal locations in an ocean general circulation model of the North Pacific

    Institute of Scientific and Technical Information of China (English)

    XU Yongfu; AOKI Shigeaki; HARADA Koh

    2009-01-01

    A basin-wide ocean general circulation model of the North Pacific is used to identify which location is more effi-cient for ocean CO2 sequestration in the North Pacific. Four injection depths at each one of fifteen locations are chosen. In terms of effectiveness index (EI) and escape factor (EF), it is clear that the effectiveness increases with increasing latitude at the end of the 50 a injection period. Site-by-site differences in the EI can be over 9% for the 1 000 m injection depth in the western North Pacific at the end of 50 a of continuous injection. The difference is much larger for the 500 m injection. The difference decreases with increasing injection depth. However, the site-by-site difference is small for the injection in the eastern North Pacific. The sequestration is more efficient for the injection in the east than in the west. For the 500 m injection depth, the difference in ef-fectiveness between the west and the east is over 10% at the end of 50 a injection period. The largest concentra-tion of sequestered CO2 increases with increasing injection depth. For the injection in both the western and cen-tral North Pacific, the largest exchange flux always appears to be at about 42°N, 150°E, whereas for the injec-tion in the eastern area the large flux appears to be in the equatorial region (120°W).

  16. Effects of CO2 Concentration on Leaf Photosynthesis and Stomatal Conductance of Potatoes Grown Under Different Irradiance Levels and Photoperiods

    Science.gov (United States)

    Wheeler, R. M.; Fitzpatrick, A. H.; Tibbitts, T. W.

    2012-01-01

    Potato (Solanum tuberosum L.) cvs. Russet Burbank, Denali, and Norland, were grown in environmental rooms controlled at approx 350 micro mol/mol (ambient during years 1987/1988) and 1000 micro mol/mol (enriched) CO2 concentrations. Plants and electric lamps were arranged to provide two irradiance zones, 400 and 800 micro mol/mol/square m/S PPF and studies were repeated using two photoperiods (12-h light / 12-h dark and continuous light). Leaf photosynthetic rates and leaf stomatal conductance were measured using fully expanded, upper canopy leaves at weekly intervals throughout growth (21 through 84 days after transplanting). Increasing the CO2 from approx 350 to 1000 micro mol/mol under the 12-h photoperiod increased leaf photosynthetic rates by 39% at 400 micro mol/mol/square m/S PPF and 27% at 800 micro mol/mol/square m/S PPF. Increasing the CO2 from approx 350 to 1000 micro mol/mol under continuous light decreased leaf photosynthetic rates by 7% at 400 micro mol/mol/square m/S PPF and 13% at 800 micro mol/mol/square m/S PPF. Increasing the CO2 from approx 350 to 1000 micro mol/mol under the 12-h photoperiod plants decreased stomatal conductance by an average of 26% at 400 micro mol/mol/square m/S PPF and 42% at 800 micro mol/mol/square m/S PPF. Under continuous light, CO2 enrichment resulted in a small increase (2%) of stomatal conductance at 400 micro mol/mol/square m/S PPF, and a small decrease (3%) at 800 micro mol/mol/square m/S PPF. Results indicate that CO2 enrichment under the 12-h photoperiod showed the expected increase in photosynthesis and decrease in stomatal conductance for a C3 species like potato, but the decreases in leaf photosynthetic rates and minimal effect on conductance from CO2 enrichment under continuous light were not expected. The plant leaves under continuous light showed more chlorosis and some rusty flecking versus plants under the 12-h photoperiod, suggesting the continuous light was more stressful on the plants. The increased

  17. Modeling of CO2 solubility in single and mixed electrolyte solutions using statistical associating fluid theory

    Science.gov (United States)

    Jiang, Hao; Panagiotopoulos, Athanassios Z.; Economou, Ioannis G.

    2016-03-01

    Statistical associating fluid theory (SAFT) is used to model CO2 solubilities in single and mixed electrolyte solutions. The proposed SAFT model implements an improved mean spherical approximation in the primitive model to represent the electrostatic interactions between ions, using a parameter K to correct the excess energies ("KMSA" for short). With the KMSA formalism, the proposed model is able to describe accurately mean ionic activity coefficients and liquid densities of electrolyte solutions including Na+, K+, Ca2+, Mg2+, Cl-, Br- and SO42- from 298.15 K to 473.15 K using mostly temperature independent parameters, with sole exception being the volume of anions. CO2 is modeled as a non-associating molecule, and temperature-dependent CO2-H2O and CO2-ion cross interactions are used to obtain CO2 solubilities in H2O and in single ion electrolyte solutions. Without any additional fitting parameters, CO2 solubilities in mixed electrolyte solutions and synthetic brines are predicted, in good agreement with experimental measurements.

  18. Fitting mitochondrial respiration rates under light by photosynthetic CO2 response models%植物光合CO2响应模型对光下(暗)呼吸速率拟合的探讨

    Institute of Scientific and Technical Information of China (English)

    康华靖; 陶月良; 权伟; 王伟; 欧阳竹

    2014-01-01

    the photosynthetic response to intercellular CO2 concentration (A/Ci) and air CO2 concentration (A/Ca),aiming to approach the reasonability of the fitted results obtained from the models.Important finding The sequence of fitting effect of the three CO2 response models in descending order was as follows:modified rectangular hyperbola model > rectangular hyperbola model > biochemical model.Fitted values of A/Ca curve was more reasonable than A/Ci curve,because the photorespiration and mitochondrial respiration under light (Rd) estimated by the former better matched the measured values.However,there were significant differences in the whole between the fitted and measured values.The reason could be that the effect of CO2 concentrations on Rd and apparent photorespiration (Rpa) is neglected in all the current CO2 response models.Our results showed that CO2 concentration had a marked effect on Rpa and Rd.With increasing CO2 concentration,Rpa and Rd increased first,and then decreased sharply.Take 2 000 μmol·m-2·s-1 for example,Rpa varied between 5.035 and 11.670 μmol CO2·m-2·s-1,and Rd varied between 0.491 and 2.987 μmol CO2·m-2·s-1.Regression analyses indicated that Rpa and Rd were well related to CO2 concentrations at different light intensities.

  19. Structure of the transport uncertainty in mesoscale inversions of CO2 sources and sinks using ensemble model simulations

    Directory of Open Access Journals (Sweden)

    J. Noilhan

    2008-12-01

    Full Text Available We study the characteristics of a statistical ensemble of mesoscale simulations in order to estimate the model error in the simulation of CO2 concentrations. The ensemble consists of ten members and the reference simulation using the operationnal short range forecast PEARP, perturbed by Singular Vector (SV technic. We then used this ensemble of simulations as the initial and boundary conditions for the meso scale model simulations, here the atmospheric transport model Méso-NH, transporting CO2 fluxes from the ISBA-A-gs land surface model. The final ensemble represents the model dependence to the boundary conditions, conserving the physical properties of the dynamical schemes. First, the variance of our ensemble is estimated over the domain, with associated spatial and temporal correlations. Second, we extract the signal from noisy horizontal correlations, due to the limited size ensemble, using diffusion equation modelling. Finally, we compute the diagonal and non-diagonal terms of the observation error covariance matrix and introduced it into our CO2 flux matrix inversion over 18 days of the 2005 intensive campaign CERES over the South West of France. On the horizontal plane, variance of the ensemble follows the discontinuities of the mesoscale structures during the day, but remain locally driven during the night. On the vertical, surface layer variance shows large correlations with the upper levels in the boundary layer (>0.6, down to 0.4 with the low free troposphere. Large temporal correlations were found during the afternoon (>0.5 for several hours, reduced during the night. Diffusion equation model extracted relevant error covariance signals on the horizontal space, and shows reduced correlations over mountain area and during the night over the continent. The posterior error reduction on the inverted CO2 fluxes accounting for the model error correlations illustrates finally the predominance of the temporal over the spatial correlations

  20. Direct Detection 1.6?m DIAL / Doppler Lidar for Measurements of CO2 Concentration and Wind Profiles (Invited)

    Science.gov (United States)

    Shibata, Y.; Nagasawa, C.; Abo, M.

    2013-12-01

    Knowledge of present carbon sources and sinks including their spatial distribution and their variation in time is one of the essential information for predicting future CO2 atmospheric concentration levels. Moreover, wind information is an important parameter for transport simulations and inverse estimation of surface CO2 flux. The differential absorption lidar (DIAL) and the Doppler wind lidar with the range resolution is expected to measure atmospheric CO2 profiles and wind profiles in the atmospheric boundary layer and lower troposphere from a ground platform. We have succeeded to develop a scanning 1.6 μm DIAL and incoherent Doppler lidar system for simultaneously measuring CO2 concentration and wind speed profiles. Our 1.6 μm DIAL system consists of the Optical Parametric Generator (OPG) transmitter that excited by the LD pumped Nd: YAG laser with high repetition rate (500 Hz) and the receiving optics that included the near-infrared photomultiplier tube with high quantum efficiency operating at the photon counting mode, a fiber Bragg grating (FBG) filter to detect a Doppler shift, and a 25 cm telescope [1] [2]. We had developed an optical parametric oscillator (OPO) system for 1.6 μm CO2 DIAL[3]. To achieve continuous tuning of the resonant OPO output without mode hopping, it is necessary to vary the OPO cavity length synchronously with the seed-frequency. On the other hand, the OPG does not require a cavity and instead rely on sufficient conversion efficiency to be obtained with a single pass through the crystal. The single-frequency oscillation of the OPG was achieved by injection seeding. The CO