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Sample records for air co2 concentration

  1. Low pCO2 Air-Polarized CO2 Concentrator Development

    NASA Technical Reports Server (NTRS)

    Schubert, Franz H.

    1997-01-01

    Life Systems completed a Ground-based Space Station Experiment Development Study Program which verifies through testing the performance and applicability of the electrochemical Air-Polarized Carbon Dioxide Concentrator (APC) process technology for space missions requiring low (i.e., less than 3 mm Hg) CO2 partial pressure (pCO2) in the cabin atmosphere. Required test hardware was developed and testing was accomplished at an approximate one-person capacity CO2 removal level. Initially, two five-cell electrochemical modules using flight-like 0.5 sq ft cell hardware were tested individually, following by their testing at the integrated APC system level. Testing verified previously projected performance and established a database for sizing of APC systems. A four person capacity APC system was sized and compared with four candidate CO2 removal systems. At its weight of 252 lb, a volume of 7 cu ft and a power consumption of 566 W while operating at 2.2 mm Hg pCO2, the APC was surpassed only by an Electrochemical Depolarized CO2 Concentrator (EDC) (operating with H2), when compared on a total equivalent basis.

  2. Module for measurement of CO2 concentration in exhaled air

    NASA Astrophysics Data System (ADS)

    Puton, Jaroslaw; Palko, Tadeusz; Knap, Andrzej; Jasek, Krzysztof; Siodlowski, Boguslaw

    2003-09-01

    The objective of this work consists in working out of a detection module for capnography (carbon dioxide concentration measurement in anaesthesiology and intensive care). The principle of operation of the module consists of the NDIR method. The basic assumption for construction of this model was using of directly modulated thermal IR source in it. A few models of IR sources were worked out. Their heaters were made from thick platinum layers and foil. Limits of modulation frequency for IR sources were greater than 30 Hz. The detection module consists of an optical part, analogue electronics and microprocessor system with a suitable program. The time dependent concentration of CO2, end tidal concentration of CO2, mean concentration of N2O and breath frequency are output values of the detection module. Measurements are executed 30 times per second. The accuracy of CO2 concentration measurement equals to 5%.

  3. Comparison of CO2 and O2 concentrations in soil air: A lesson learned about CO2 diffusivity in soils

    NASA Astrophysics Data System (ADS)

    Angert, A.; Davidson, E. A.; Savage, K.; Yakir, D.; Luz, B.

    2002-12-01

    Soil respiration is a major component of the global carbon and oxygen cycles and accounts for about one quarter of global respiration. Since respiration consumes O2 and emits CO2, a simple relationship may be expected between the concentration of these gases in soil-air. However, because the [O2] signal in well-drained soils is small, deriving this relationship from field observations is not trivial. In this study, we present high accuracy measurements of O2 concentrations in soil air, that for the first time, enable precise comparison of these concentrations with CO2 concentrations. Soil air was sampled in two sites: an orchard in Israel, and a temperate forest (Harvard forest). The expected ratio of the decrease in [O2] in soil air to the increase in [CO2] can be calculated from the ratio of O2 consumption to CO2 emission in respiration, and the ratio between the diffusivities of these two gases in air as 0.79-0.07. The measured ratio of the decrease in [O2] to the increase in [CO2] in soil air was 0.56-2.48 in the orchard site and 1.06-1.20 in Harvard Forest. These ratios deviate strongly from the expected relationship. In the orchard site, these deviations were probably caused by reactions in the carbonate system due to the calcareous soil of this site. At Harvard Forest, such reactions cannot be quantitatively important because of the low pH of the soil. In this site, we propose that the relationship between CO2 and O2 in the soil air indicates that the ratio of diffusivity of O2 and CO2 in soils is higher than the diffusivity ratio in air. Our results demonstrate that a combination of high accuracy measurements of the O2 and CO2 in soil air is important for better understanding of the soil CO2 dynamics. Such observations will improve estimates of soil respiration that are based only on CO2 concentration and diffusivity.

  4. Methods to reduce the CO(2) concentration of educational buildings utilizing internal ventilation by transferred air.

    PubMed

    Kalema, T; Viot, M

    2014-02-01

    The aim of this study is to develop internal ventilation by transferred air to achieve a good indoor climate with low energy consumption in educational buildings with constant air volume (CAV) ventilation. Both measurements of CO2 concentration and a multi-room calculation model are presented. The study analyzes how to use more efficiently the available spaces and the capacity of CAV ventilation systems in existing buildings and the impact this has on the indoor air quality and the energy consumption of the ventilation. The temperature differences can be used to create natural ventilation airflows between neighboring spaces. The behavior of temperature-driven airflows between rooms was studied and included in the calculation model. The effect of openings between neighboring spaces, such as doors or large apertures in the walls, on the CO2 concentration was studied in different classrooms. The air temperatures and CO2 concentrations were measured using a wireless, internet-based measurement system. The multi-room calculation model predicted the CO2 concentration in the rooms, which was then compared with the measured ones. Using transferred air between occupied and unoccupied spaces can noticeably reduce the total mechanical ventilation rates needed to keep a low CO2 concentration. PMID:23841677

  5. Elevated CO2 significantly delays reproductive development of soybean under Free-Air Concentration Enrichment (FACE).

    PubMed

    Castro, Joseph C; Dohleman, Frank G; Bernacchi, Carl J; Long, Stephen P

    2009-01-01

    The effect of rising atmospheric concentration of carbon dioxide [CO(2)] on the reproductive development of soybean (Glycine max. Merr) has not been evaluated under open-air field conditions. Soybeans grown under Free-Air CO(2) Enrichment (FACE) exhibit warmer canopies due to decreased latent heat loss because of decreased stomatal conductance. According to development models based on accumulated thermal time, or growing degree days ( degrees Cd), increased canopy temperature should accelerate development. The SoyFACE research facility (Champaign, Illinois, USA) was used to test the hypothesis that development is accelerated in soybean when grown in [CO(2)] elevated to 548 micromol mol(-1). Canopy temperature was measured continuously with infrared thermometry, and used in turn to calculate GDD. Opposite to expectation, elevated [CO(2)], while increasing canopy temperature, delayed reproductive development by up to 3 days (P <0.05). Soybean grown in elevated [CO(2)] required approximately 49 degrees Cd more GDD (P <0.05) to complete full bloom stage (R2) and approximately 52 degrees Cd more GDD (P <0.05) to complete the beginning seed (R5) stage, but needed approximately 46 degrees Cd fewer GDD (P <0.05) to complete seed filling (R6). Soybeans grown in elevated [CO(2)] produced significantly more nodes (P <0.01) on the main stem than those grown under current [CO(2)]. This may explain the delay in completion of reproductive development and final maturation of the crop under elevated [CO(2)]. These results show a direct effect of rising [CO(2)] on plant development that will affect both projections of grain supply and may be significant to other species including those in natural communities. PMID:19561049

  6. Soil air CO2 concentration as an integrative parameter of soil structure

    NASA Astrophysics Data System (ADS)

    Ebeling, Corinna; Gaertig, Thorsten; Fründ, Heinz-Christian

    2015-04-01

    The assessment of soil structure is an important but difficult issue and normally takes place in the laboratory. Typical parameters are soil bulk density, porosity, water or air conductivity or gas diffusivity. All methods are time-consuming. The integrative parameter soil air CO2 concentration ([CO2]) can be used to assess soil structure in situ and in a short time. Several studies highlighted that independent of soil respiration, [CO2] in the soil air increases with decreasing soil aeration. Therefore, [CO2] is a useful indicator of soil aeration. Embedded in the German research project RÜWOLA, which focus on soil protection at forest sites, we investigated soil compaction and recovery of soil structure after harvesting. Therefore, we measured soil air CO2 concentrations continuously and in single measurements and compared the results with the measurements of bulk density, porosity and gas diffusivity. Two test areas were investigated: At test area 1 with high natural regeneration potential (clay content approx. 25 % and soil-pH between 5 and 7), solid-state CO2-sensors using NDIR technology were installed in the wheel track of different aged skidding tracks in 5 and 10 cm soil depths. At area 2 (acidic silty loam, soil-pH between 3.5 and 4), CO2-sensors and water-tension sensors (WatermarkR) were installed in 6 cm soil depth. The results show a low variance of [CO2] in the undisturbed soil with a long term mean from May to June 2014 between 0.2 and 0.5 % [CO2] in both areas. In the wheel tracks [CO2] was consistently higher. The long term mean [CO2] in the 8-year-old-wheel track in test area 1 is 5 times higher than in the reference soil and shows a high variation (mean=2.0 %). The 18-year-old wheel track shows a long-term mean of 1.2 % [CO2]. Furthermore, there were strong fluctuations of [CO2] in the wheel tracks corresponding to precipitation and humidity. Similar results were yielded with single measurements during the vegetation period using a portable

  7. Midtropospheric CO2 concentration retrieval from AIRS observations in the tropics

    NASA Astrophysics Data System (ADS)

    Crevoisier, C.; Heilliette, S.; Chédin, A.; Serrar, S.; Armante, R.; Scott, N. A.

    2004-09-01

    Midtropospheric carbon dioxide (CO2) concentration is retrieved in the tropics [20S:20N], over sea, at night, for the period April to October 2003 from the Atmospheric Infrared Sounder (AIRS) observations. The method relies on a non-linear regression inference scheme using neural networks. A rough estimate of the mean precision of the method is about 2.5 ppmv (0.7%). The retrieved seasonal cycle and its latitudinal dependence agree well with aircraft CO2 in situ measurements made at the same altitude range. Maps produced on a monthly basis at a resolution of 15° × 15°, although not yet fully understood, show good agreement with known characteristics of CO2 distribution reflecting both atmospheric transport and surface fluxes (fossil fuel emissions, biomass burning, air-surface gas exchanges).

  8. Diffuse CO 2 soil degassing and CO 2 and H 2S concentrations in air and related hazards at Vulcano Island (Aeolian arc, Italy)

    NASA Astrophysics Data System (ADS)

    Carapezza, M. L.; Barberi, F.; Ranaldi, M.; Ricci, T.; Tarchini, L.; Barrancos, J.; Fischer, C.; Perez, N.; Weber, K.; Di Piazza, A.; Gattuso, A.

    2011-10-01

    La Fossa crater on Vulcano Island is quiescent since 1890. Periodically it undergoes "crises" characterized by marked increase of temperature (T), gas output and concentration of magmatic components in the crater fumaroles (T may exceed 600 °C). During these crises, which so far did not lead to any eruptive reactivation, the diffuse CO 2 soil degassing also increases and in December 2005 an anomalous CO 2 flux of 1350 tons/day was estimated by 1588 measurements over a surface of 1.66 km 2 extending from La Fossa crater to the inhabited zone of Vulcano Porto. The crater area and two other anomalously degassing sites (Levante Beach and Palizzi) have been periodically investigated from December 2004 to August 2010 for diffuse CO 2 soil flux. They show a marked variation with time of the degassing rate, with synchronous maxima in December 2005. Carbon dioxide soil flux and environmental parameters have been also continuously monitored for over one year by an automatic station at Vulcano Porto. In order to assess the hazard of the endogenous gas emissions, CO 2 and H 2S air concentrations have been measured by Tunable Diode Laser profiles near the fumaroles of the crater rim and of the Levante Beach area, where also the viscous gas flux has been estimated. In addition, CO 2 air concentration has been measured both indoor and outdoor in an inhabited sector of Vulcano Porto. Results show that in some sites usually frequented by tourists there is a dangerous H 2S air concentration and CO 2 exceeds the hazardous thresholds in some Vulcano houses. These zones should be immediately monitored for gas hazard should a new crisis arise.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Passive CO2 concentration in higher plants.

    PubMed

    Sage, Rowan F; Khoshravesh, Roxana

    2016-06-01

    Photorespiratory limitations on C3 photosynthesis are substantial in warm, low CO2 conditions. To compensate, certain plants evolved mechanisms to actively concentrate CO2 around Rubisco using ATP-supported CO2 pumps such as C4 photosynthesis. Plants can also passively accumulate CO2 without additional ATP expenditure by localizing the release of photorespired and respired CO2 around Rubisco that is diffusively isolated from peripheral air spaces. Passive accumulation of photorespired CO2 occurs when glycine decarboxylase is localized to vascular sheath cells in what is termed C2 photosynthesis, and through forming sheaths of chloroplasts around the periphery of mesophyll cells. The peripheral sheaths require photorespired CO2 to re-enter chloroplasts where it can be refixed. Passive accumulation of respiratory CO2 is common in organs such as stems, fruits and flowers, due to abundant heterotrophic tissues and high diffusive resistance along the organ periphery. Chloroplasts within these organs are able to exploit this high CO2 to reduce photorespiration. CO2 concentration can also be enhanced passively by channeling respired CO2 from roots and rhizomes into photosynthetic cells of stems and leaves via lacunae, aerenchyma and the xylem stream. Through passive CO2 concentration, C3 species likely improved their carbon economy and maintained fitness during episodes of low atmospheric CO2. PMID:27058940

  11. Photosynthesis, productivity, and yield of maize are not affected by open-air elevation of CO2 concentration in the absence of drought.

    PubMed

    Leakey, Andrew D B; Uribelarrea, Martin; Ainsworth, Elizabeth A; Naidu, Shawna L; Rogers, Alistair; Ort, Donald R; Long, Stephen P

    2006-02-01

    While increasing temperatures and altered soil moisture arising from climate change in the next 50 years are projected to decrease yield of food crops, elevated CO2 concentration ([CO2]) is predicted to enhance yield and offset these detrimental factors. However, C4 photosynthesis is usually saturated at current [CO2] and theoretically should not be stimulated under elevated [CO2]. Nevertheless, some controlled environment studies have reported direct stimulation of C4 photosynthesis and productivity, as well as physiological acclimation, under elevated [CO2]. To test if these effects occur in the open air and within the Corn Belt, maize (Zea mays) was grown in ambient [CO2] (376 micromol mol(-1)) and elevated [CO2] (550 micromol mol(-1)) using Free-Air Concentration Enrichment technology. The 2004 season had ideal growing conditions in which the crop did not experience water stress. In the absence of water stress, growth at elevated [CO2] did not stimulate photosynthesis, biomass, or yield. Nor was there any CO2 effect on the activity of key photosynthetic enzymes, or metabolic markers of carbon and nitrogen status. Stomatal conductance was lower (-34%) and soil moisture was higher (up to 31%), consistent with reduced crop water use. The results provide unique field evidence that photosynthesis and production of maize may be unaffected by rising [CO2] in the absence of drought. This suggests that rising [CO2] may not provide the full dividend to North American maize production anticipated in projections of future global food supply. PMID:16407441

  12. Changes in Air CO2 Concentration Differentially Alter Transcript Levels of NtAQP1 and NtPIP2;1 Aquaporin Genes in Tobacco Leaves

    PubMed Central

    Secchi, Francesca; Schubert, Andrea; Lovisolo, Claudio

    2016-01-01

    The aquaporin specific control on water versus carbon pathways in leaves is pivotal in controlling gas exchange and leaf hydraulics. We investigated whether Nicotiana tabacum aquaporin 1 (NtAQP1) and Nicotiana tabacum plasma membrane intrinsic protein 2;1 (NtPIP2;1) gene expression varies in tobacco leaves subjected to treatments with different CO2 concentrations (ranging from 0 to 800 ppm), inducing changes in photosynthesis, stomatal regulation and water evaporation from the leaf. Changes in air CO2 concentration ([CO2]) affected net photosynthesis (Pn) and leaf substomatal [CO2] (Ci). Pn was slightly negative at 0 ppm air CO2; it was one-third that of ambient controls at 200 ppm, and not different from controls at 800 ppm. Leaves fed with 800 ppm [CO2] showed one-third reduced stomatal conductance (gs) and transpiration (E), and their gs was in turn slightly lower than in 200 ppm– and in 0 ppm–treated leaves. The 800 ppm air [CO2] strongly impaired both NtAQP1 and NtPIP2;1 gene expression, whereas 0 ppm air [CO2], a concentration below any in vivo possible conditions and specifically chosen to maximize the gene expression alteration, increased only the NtAQP1 transcript level. We propose that NtAQP1 expression, an aquaporin devoted to CO2 transport, positively responds to CO2 scarcity in the air in the whole range 0–800 ppm. On the contrary, expression of NtPIP2;1, an aquaporin not devoted to CO2 transport, is related to water balance in the leaf, and changes in parallel with gs. These observations fit in a model where upregulation of leaf aquaporins is activated at low Ci, while downregulation occurs when high Ci saturates photosynthesis and causes stomatal closure. PMID:27089333

  13. Are δ13C values of n-alkanes affected by atmospheric CO2 concentrations? Results from a free-air CO2 enrichment (FACE) experiment.

    NASA Astrophysics Data System (ADS)

    Sandquist, D. R.; Williams, D. G.; Shuman, B. N.; Kim, S.; Chen, J.; Macdonald, C.

    2015-12-01

    Compound-specific carbon isotope (δ13C) analyses of leaf waxes (i.e., n-alkanes) can be linked to large-scale shifts in vegetation, such as dominant taxa, functional types, life-forms and photosynthetic pathways that are usually coupled with environmental changes in climate. However using these δ13C values to interpret finer-scale ecosystem properties, including climate attributes such as CO2 concentrations, is difficult owing to uncertainty in the magnitude of internal biosynthetic fractionations that determine the δ13C of waxes relative to that of bulk leaf material. We investigated the composition, abundance and δ13C of n-alkanes in the aboveground biomass of a C4 grass and a C3 grass exposed to experimentally controlled CO2 at ambient [490ppm] and elevated [630ppm] levels within natural grassland in Wyoming. The δ13C values of bulk tissues were predictably different based on the C3 and C4 photosynthetic pathways, but the difference between bulk tissue and n-alkanes (ɛlipid), for both C29 and C31, was consistently greater in the C4 grass. The magnitudes of these ɛlipid values were large (- 7‰ to -15‰) relative to those found in most other studies. CO2 concentration of the growing environment also had a significant effect on n-alkane δ13C values, with consistently higher values of ~ 2‰ under elevated CO2 found in both species and in both a wet and a dry year. These results underscore the importance of recognizing potential abiotic effects on leaf wax δ13C values, in addition to the biotic drivers their variation, when interpreting climate from leaf-wax biomarkers of terrestrial ecosystems.

  14. Photosynthesis, Productivity, and Yield of Maize Are Not Affected by Open-Air Elevation of CO2 Concentration in the Absence of Drought1[OA

    PubMed Central

    Leakey, Andrew D.B.; Uribelarrea, Martin; Ainsworth, Elizabeth A.; Naidu, Shawna L.; Rogers, Alistair; Ort, Donald R.; Long, Stephen P.

    2006-01-01

    While increasing temperatures and altered soil moisture arising from climate change in the next 50 years are projected to decrease yield of food crops, elevated CO2 concentration ([CO2]) is predicted to enhance yield and offset these detrimental factors. However, C4 photosynthesis is usually saturated at current [CO2] and theoretically should not be stimulated under elevated [CO2]. Nevertheless, some controlled environment studies have reported direct stimulation of C4 photosynthesis and productivity, as well as physiological acclimation, under elevated [CO2]. To test if these effects occur in the open air and within the Corn Belt, maize (Zea mays) was grown in ambient [CO2] (376 μmol mol−1) and elevated [CO2] (550 μmol mol−1) using Free-Air Concentration Enrichment technology. The 2004 season had ideal growing conditions in which the crop did not experience water stress. In the absence of water stress, growth at elevated [CO2] did not stimulate photosynthesis, biomass, or yield. Nor was there any CO2 effect on the activity of key photosynthetic enzymes, or metabolic markers of carbon and nitrogen status. Stomatal conductance was lower (−34%) and soil moisture was higher (up to 31%), consistent with reduced crop water use. The results provide unique field evidence that photosynthesis and production of maize may be unaffected by rising [CO2] in the absence of drought. This suggests that rising [CO2] may not provide the full dividend to North American maize production anticipated in projections of future global food supply. PMID:16407441

  15. Production of Chlorella vulgaris as a source of essential fatty acids in a tubular photobioreactor continuously fed with air enriched with CO2 at different concentrations.

    PubMed

    Ortiz Montoya, Erika Y; Casazza, Alessandro A; Aliakbarian, Bahar; Perego, Patrizia; Converti, Attilio; de Carvalho, João C Monteiro

    2014-01-01

    To reduce CO2 emissions and simultaneously produce biomass rich in essential fatty acids, Chlorella vulgaris CCAP 211 was continuously grown in a tubular photobioreactor using air alone or air enriched with CO2 as the sole carbon source. While on one hand, nitrogen-limited conditions strongly affected biomass growth, conversely, they almost doubled its lipid fraction. Under these conditions using air enriched with 0, 2, 4, 8, and 16% (v/v) CO2 , the maximum biomass concentration was 1.4, 5.8, 6.6, 6.8, and 6.4 gDB L(-1) on a dry basis, the CO2 consumption rate 62, 380, 391, 433, and 430 mgCO2 L(-1) day(-1) , and the lipid productivity 3.7, 23.7, 24.8, 29.5, and 24.4 mg L(-1) day(-1) , respectively. C. vulgaris was able to grow effectively using CO2 -enriched air, but its chlorophyll a (3.0-3.5 g 100gDB (-1) ), chlorophyll b (2.6-3.0 g 100gDB (-1) ), and lipid contents (10.7-12.0 g 100gDB (-1) ) were not significantly influenced by the presence of CO2 in the air. Most of the fatty acids in C. vulgaris biomass were of the saturated series, mainly myristic, palmitic, and stearic acids, but a portion of no less than 45% consisted of unsaturated fatty acids, and about 80% of these were high added-value essential fatty acids belonging to the ω3 and ω6 series. These results highlight that C. vulgaris biomass could be of great importance for human health when used as food additive or for functional food production. PMID:24532479

  16. Development of a coulometric method for assessing the concentration of ambient levels of CO2/air in compressed-gas mixtures

    SciTech Connect

    Mitchell, G.D.; Bell, A.A.

    1991-01-01

    The understanding of global 'greenhouse' issues as they relate to CO2 in the atmosphere is a current environmental concern. At the National Institute of Standards and Technology there is a continuous search for methods of analysis that yield results that are traceable to fundamental quantities. The coulometric method presented here is a reliable method for the direct analysis of CO2/air cylinder gas mixtures. It is based on Faraday's laws of electrolysis and therefore no external standardization is required. A series of CO2/air cylinder gas mixtures ranging in concentration from 300 to 375 micromol/mol (ppm) were analyzed and the results compared to those results obtained by non-dispersive infrared (NDIR) analysis with traceability to gravimetric standards. The coulometric method is rapid, sensitive, precise, and with the proper experimental controls, will yield accurate results.

  17. Zinc depolarized electrochemical CO2 concentration

    NASA Technical Reports Server (NTRS)

    Woods, R. R.; Marshall, R. D.; Schubert, F. H.

    1975-01-01

    Two zinc depolarized electrochemical carbon dioxide concentrator concepts were analytically and experimentally evaluated for portable life support system carbon dioxide (CO2) removal application. The first concept, referred to as the zinc hydrogen generator electrochemical depolarized CO2 concentrator, uses a ZHG to generate hydrogen for direct use in an EDC. The second concept, referred to as the zinc/electrochemical depolarized concentrator, uses a standard EDC cell construction modified for use with the Zn anode. The Zn anode is consumed and subsequently regenerated, thereby eliminating the need to supply H2 to the EDC for the CO2 removal process. The evaluation was based primarily on an analytical evaluation of the two ZnDCs at projected end item performance and hardware design levels. Both ZnDC concepts for PLSS CO2 removal application were found to be noncompetitive in both total equivalent launch weight and individual extravehicular activity mission volume when compared to other candidate regenerable PLSS CO2 scrubbers.

  18. Photosynthetic CO2 uptake in seedlings of two tropical tree species exposed to oscillating elevated concentrations of CO2.

    PubMed

    Holtum, Joseph A M; Winter, Klaus

    2003-11-01

    Do short-term fluctuations in CO2 concentrations at elevated CO2 levels affect net CO2 uptake rates of plants? When exposed to 600 microl CO2 l(-1), net CO2 uptake rates in shoots or leaves of seedlings of two tropical C3 tree species, teak (Tectona grandis L. f.) and barrigon [Pseudobombax septenatum (Jacq.) Dug.], increased by 28 and 52% respectively. In the presence of oscillations with half-cycles of 20 s, amplitude of ca. 170 microl CO2 l(-1) and mean of 600 microl CO2 l(-1), the stimulation in net CO2 uptake by the two species was reduced to 19 and 36%, respectively, i.e. the CO2 stimulation in photosynthesis associated with a change in exposure from 370 to 600 microl CO2 l(-1) was reduced by a third in both species. Similar reductions in CO2-stimulated net CO2 uptake were observed in T. grandis exposed to 40-s oscillations. Rates of CO2 efflux in the dark by whole shoots of T. grandis decreased by 4.8% upon exposure of plants grown at 370 microl CO2 l(-1) to 600 microl CO2 l(-1). The potential implications of the observations on CO2 oscillations and dark respiration are discussed in the context of free-air CO2 enrichment (FACE) systems in which short-term fluctuations of CO2 concentration are a common feature. PMID:12905026

  19. CO2 and O2 concentrations in integral motorcycle helmets.

    PubMed

    Brühwiler, P A; Stämpfli, R; Huber, R; Camenzind, M

    2005-09-01

    Inhaling air which contains excess CO2 and/or is oxygen-deficient is known to present health risks and to diminish human cognitive abilities. The average CO2 concentrations relevant to a motorcyclist wearing an integral helmet were measured 20 years ago and found to be alarmingly large. The purpose of the present study was to examine gas concentrations typically inhaled by a motorcyclist. Average concentrations of CO2 near the upper lip for persons (n = 4) wearing integral motorcycle helmets were measured in the laboratory and the field to facilitate comparison to previous work, and similarly high average concentrations were found: above 2% when stationary, well below 1% for speeds of 50 km/h or more. Very good agreement was obtained between laboratory and field measurements. Detailed measurements of the time-dependent CO2 concentrations passing through a mouthpiece for mouth-breathing showed inhaled levels slightly over half of the corresponding average concentrations, including 1.3+/-0.3% at standstill, though higher concentrations (4% or more) were inhaled at the beginning of each breath. Opening the visor at standstill had on average no effect. At a speed of 50 km/h the inhaled CO2 concentration resembles that for a person without a helmet in still air, at about 0.2%. The oxygen deficiency is generally equal to the CO2 concentration, and could also contribute negatively to a motorcyclist's cognitive abilities. PMID:15893291

  20. Air exchange rates from atmospheric CO2 daily cycle

    PubMed Central

    Carrilho, João Dias; Mateus, Mário; Batterman, Stuart; da Silva, Manuel Gameiro

    2015-01-01

    We propose a new approach for measuring ventilation air exchange rates (AERs). The method belongs to the class of tracer gas techniques, but is formulated in the light of systems theory and signal processing. Unlike conventional CO2 based methods that assume the outdoor ambient CO2 concentration is constant, the proposed method recognizes that photosynthesis and respiration cycle of plants and processes associated with fuel combustion produce daily, quasi-periodic, variations in the ambient CO2 concentrations. These daily variations, which are within the detection range of existing monitoring equipment, are utilized for estimating ventilation rates without the need of a source of CO2 in the building. Using a naturally-ventilated residential apartment, AERs obtained using the new method compared favorably (within 10%) to those obtained using the conventional CO2 decay fitting technique. The new method has the advantages that no tracer gas injection is needed, and high time resolution results are obtained. PMID:26236090

  1. Technology advancement of the electrochemical CO2 concentrating process

    NASA Technical Reports Server (NTRS)

    Schubert, F. H.; Woods, R. R.; Hallick, T. M.; Heppner, D. B.

    1978-01-01

    The overall objectives of the present program are to: (1) improve the performance of the electrochemical CO2 removal technique by increasing CO2 removal efficiencies at pCO2 levels below 400 Pa, increasing cell power output and broadening the tolerance of electrochemical cells for operation over wide ranges of cabin relative humidity; (2) design, fabricate, and assemble development hardware to continue the evolution of the electrochemical concentrating technique from the existing level to an advanced level able to efficiently meet the CO2 removal needs of a spacecraft air revitalization system (ARS); (3) develop and incorporate into the EDC the components and concepts that allow for the efficient integration of the electrochemical technique with other subsystems to form a spacecraft ARS; (4) combine ARS functions to enable the elimination of subsystem components and interfaces; and (5) demonstrate the integration concepts through actual operation of a functionally integrated ARS.

  2. Hourly and seasonal variation in photosynthesis and stomatal conductance of soybean grown at future CO2 and ozone concentrations for three years under fully open air conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Numerous controlled environment studies have suggested that elevation of atmospheric [CO2] to 550 ppm, the concentration anticipated for the year 2050, should increase leaf photosynthetic carbon assimilation (A) by ca. 40%. Simultaneously studies of the effects of tropospheric ozone concentration (...

  3. Precise measurements of the total concentration of atmospheric CO2 and 13CO2/12CO2 isotopic ratio using a lead-salt laser diode spectrometer.

    PubMed

    Croizé, Laurence; Mondelain, Didier; Camy-Peyret, Claude; Delmotte, Marc; Schmidt, Martina

    2008-04-01

    We have developed a tunable diode laser spectrometer, called SIMCO (spectrometer for isotopic measurements of CO(2)), for determining the concentrations of (12)CO(2) and (13)CO(2) in atmospheric air, from which the total concentration of CO(2) and the isotopic composition (expressed in delta units) delta(13)CO(2) are calculated. The two concentrations are measured using a pair of lines around 2290.1 cm(-1), by fitting a line profile model, taking into account the confinement narrowing effect to achieve a better accuracy. Using the Allan variance, we have demonstrated (for an integration time of 25 s) a precision of 0.1 ppmv for the total CO(2) concentration and of 0.3[per thousand] for delta(13)CO(2). The performances on atmospheric air have been tested during a 3 days campaign by comparing the SIMCO instrument with a gas chromatograph (GC) for the measurement of the total CO(2) concentration and with an isotopic ratio mass spectrometer (MS) for the isotopic composition. The CO(2) concentration measurements of SIMCO are in very good agreement with the GC data with a mean difference of Delta(CO(2))=0.16+/-1.20 ppmv for a comparison period of 45 h and the linearity of the concentration between the two instruments is also very good (slope of correlation: 0.9996+/-0.0003) over the range between 380 and 415 ppmv. For delta(13)CO(2), the comparison with the MS data shows a larger mean difference of Delta(delta(13)CO(2))=(-1.9+/-1.2)[per thousand], which could be partly related to small residual fluctuations of the overall SIMCO instrument response. PMID:18447517

  4. Effects of elevated CO2 concentrations on denitrifying and nitrifying popualtions at terrestrial CO2 leakeage analogous sites

    NASA Astrophysics Data System (ADS)

    Christine, Dictor Marie; Catherine, Joulian; Valerie, Laperche; Stephanie, Coulon; Dominique, Breeze

    2010-05-01

    CO2 capture and geological storage (CCS) is recognized to be an important option for carbon abatement in Europe. One of the risks of CCS is the leakage from storage site. A laboratory was conducted on soil samples sampled near-surface from a CO2 leakage analogous site (Latera, Italy) in order to evaluate the impact of an elevated soil CO2 concentration on terrestrial bacterial ecosystems form near surface terrestrial environments and to determine a potential bacterial indicator of CO2 leakage from storage site. Surveys were conducted along a 50m long transect across the vent centre, providing a spectrum of CO2 flux rates, soil gas concentrations and compositions (Beaubien et al., 2007). A bacterial diversity studies, performed by CE-SSCP technique, on a soil profile with increasing CO2 soil concentrations (from 0.3% to 100%) showed that a change on bacterial diversity was noted when CO2 concentration was above 50 % of CO2. From this result, 3 soil samples were taken at 70 cm depth in 3 distinct zones (background soil CO2 content, soil CO2 content of 20% and soil CO2 content of 50%). Then theses soil samples were incubated under closed jars flushed with different air atmospheres (20, 50 and 90 % of CO2) during 18 months. At initial, 3, 6, 12 and 18 months, some soil samples were collected in order to estimate the denitrifying, nitrifying activities as a function of CO2 concentration content and times. Theses enzymatic activities were chosen because one occurs under anaerobic conditions (denitrification) and the other occurs under aerobic conditions (nitrification). Both of them were involved in the nitrogen cycle and are major actors of soil function and groundwater quality preservation. Metabolic diversity using BIOLOG Ecoplates was determined on every soil samples. Physico-chemical parameters (e.g. pH, bulk chemistry, mineralogy) were analyzed to have some information about the evolution of the soil during the incubation with increasing soil CO2 concentrations

  5. Annual and seasonal fCO2 and air-sea CO2 fluxes in the Barents Sea

    NASA Astrophysics Data System (ADS)

    Lauvset, S. K.; Chierici, M.; Counillon, F.; Omar, A.; Nondal, G.; Johannessen, T.; Olsen, A.

    2013-03-01

    The Barents Sea is the strongest CO2 sink in the Arctic region, yet estimates of the air-sea CO2 flux in this area show a large span reflecting uncertainty as well as significant variability both seasonally and regionally. Here we use a previously unpublished data set of seawater CO2 fugacity (fCO2), and map these data over the western Barents Sea through multivariable linear regressions with SeaWiFS/MODIS remote sensing and TOPAZ model data fields. We find that two algorithms are necessary in order to cover the full seasonal cycle, mainly because not all proxy variables are available for the entire year, and because variability in fCO2 is driven by different mechanisms in summer and winter. A comprehensive skill assessment indicates that there is a good overall correspondence between observations and predictions. The algorithms are also validated using two independent data sets, with good results. The gridded fCO2 fields reveal tight links between water mass distribution and fCO2 in all months, and particularly in winter. The seasonal cycle show peaks in the total air-sea CO2 influx in May and September, caused by respectively biological drawdown of CO2 and low sea ice concentration leaving a large open water area. For 2007 the annual average air-sea CO2 flux is - 48 ± 5 gC m- 2, which is comparable to previous estimates.

  6. Dynamics of CO2 fluxes and concentrations during a shallow subsurface CO2 release

    SciTech Connect

    Lewicki, J.L.; Hilley, G.E.; Dobeck, L.; Spangler, L.

    2009-09-01

    A field facility located in Bozeman, Montana provides the opportunity to test methods to detect, locate, and quantify potential CO2 leakage from geologic storage sites. From 9 July to 7 August 2008, 0.3 t CO2 d{sup -1} were injected from a 100-m long, {approx}2.5 m deep horizontal well. Repeated measurements of soil CO2 fluxes on a grid characterized the spatio-temporal evolution of the surface leakage signal and quantified the surface leakage rate. Infrared CO2 concentration sensors installed in the soil at 30 cm depth at 0 to 10 m from the well and at 4 cm above the ground at 0 and 5 m from the well recorded surface breakthrough of CO2 leakage and migration of CO2 leakage through the soil. Temporal variations in CO2 concentrations were correlated with atmospheric and soil temperature, wind speed, atmospheric pressure, rainfall, and CO2 injection rate.

  7. Does atmospheric CO2 seasonality play an important role in governing the air-sea flux of CO2?

    NASA Astrophysics Data System (ADS)

    Halloran, P. R.

    2012-06-01

    The amplitude, phase, and form of the seasonal cycle of atmospheric CO2 concentrations varies on many time and space scales (Peters et al., 2007). Intra-annual CO2 variation is primarily driven by seasonal uptake and release of CO2 by the terrestrial biosphere (Machta et al., 1977; Buchwitz et al., 2007), with a small (Cadule et al., 2010; Heimann et al., 1998), but potentially changing (Gorgues et al., 2010) contribution from the ocean. Variability in the magnitude, spatial distribution, and seasonal drivers of terrestrial net primary productivity (NPP) will be induced by, amongst other factors, anthropogenic CO2 release (Keeling et al., 1996), land-use change (Zimov et al., 1999) and planetary orbital variability, and will lead to changes in CO2atm seasonality. Despite CO2atm seasonality being a dynamic and prominent feature of the Earth System, its potential to drive changes in the air-sea flux of CO2 has not previously (to the best of my knowledge) been explored. It is important that we investigate the impact of CO2atm seasonality change, and the potential for carbon-cycle feedbacks to operate through the modification of the CO2atm seasonal cycle, because the decision had been made to prescribe CO2atm concentrations (rather than emissions) within model simulations for the fifth IPCC climate assessment (Taylor et al., 2009). In this study I undertake ocean-model simulations within which different magnitude CO2atm seasonal cycles are prescribed. These simulations allow me to examine the effect of a change in CO2atm seasonal cycle magnitude on the air-sea CO2 flux. I then use an off-line model to isolate the drivers of the identified air-sea CO2 flux change, and propose mechanisms by which this change may come about. Three mechanisms are identified by which co-variability of the seasonal cycles in atmospheric CO2 concentration, and seasonality in sea-ice extent, wind-speed and ocean temperature, could potentially lead to changes in the air-sea flux of CO2 at mid

  8. Designing an oscillating CO2 concentration experiment for field chambers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Questions have arisen about photosynthetic response to fluctuating carbon dioxide (CO2), which might affect yield in free-air CO2 enrichment (FACE) systems and in open top chambers. A few studies have been conducted based on CO2 controlled to cycles of fixed time-periods and fixed, large amplitude....

  9. Growth strategy of Norway spruce under air elevated [CO2

    NASA Astrophysics Data System (ADS)

    Pokorny, R.; Urban, O.; Holisova, P.; Sprtova, M.; Sigut, L.; Slipkova, R.

    2012-04-01

    Plants will respond to globally increasing atmospheric CO2 concentration ([CO2]) by acclimation or adaptation at physiological and morphological levels. Considering the temporal onset, physiological responses may be categorized as short-term and morphological ones as long-term responses. The degree of plant growth responses, including cell division and cell expansion, is highly variable. It depends mainly on the specie's genetic predisposition, environment, mineral nutrition status, duration of CO2 enrichment, and/or synergetic effects of other stresses. Elevated [CO2] causes changes in tissue anatomy, quantity, size, shape and spatial orientation and can result in altered sink strength. Since, there are many experimental facilities for the investigation of elevated [CO2] effects on trees: i) closed systems or open top chambers (OTCs), ii) semi-open systems (for example glass domes with adjustable lamella windows - DAWs), and iii) free-air [CO2] enrichments (FACE); the results are still unsatisfactory due to: i) relatively short-term duration of experiments, ii) cultivation of young plants with different growth strategy comparing to old ones, iii) plant cultivation under artificial soil and weather conditions, and iv) in non-representative stand structure. In this contribution we are discussing the physiological and morphological responses of Norway spruce trees cultivated in DAWs during eight consecutive growing seasons in the context with other results from Norway spruce cultivation under air-elevated [CO2] conditions. On the level of physiological responses, we discuss the changes in the rate of CO2 assimilation, assimilation capacity, photorespiration, dark respiration, stomatal conductance, water potential and transpiration, and the sensitivity of these physiological processes to temperature. On the level of morphological responses, we discuss the changes in bud and growth phenology, needle and shoot morphology, architecture of crown and root system, wood

  10. Leaf cavity CO2 concentrations and CO2 exchange in onion, Allium cepa L.

    PubMed

    Byrd, G T; Loboda, T; Black, C C; Brown, R H

    1995-06-01

    Onion (Allium cepa L.) plants were examined to determine the photosynthetic role of CO2 that accumulates within their leaf cavities. Leaf cavity CO2 concentrations ranged from 2250 μL L(-1) near the leaf base to below atmospheric (<350 μL L(-1)) near the leaf tip at midday. There was a daily fluctuation in the leaf cavity CO2 concentrations with minimum values near midday and maximum values at night. Conductance to CO2 from the leaf cavity ranged from 24 to 202 μmol m(-2) s(-1) and was even lower for membranes of bulb scales. The capacity for onion leaves to recycle leaf cavity CO2 was poor, only 0.2 to 2.2% of leaf photosynthesis based either on measured CO2 concentrations and conductance values or as measured directly by (14)CO2 labeling experiments. The photosynthetic responses to CO2 and O2 were measured to determine whether onion leaves exhibited a typical C3-type response. A linear increase in CO2 uptake was observed in intact leaves up to 315 μL L(-1) of external CO2 and, at this external CO2 concentration, uptake was inhibited 35.4±0.9% by 210 mL L(-1) O2 compared to 20 mL L(-1) O2. Scanning electron micrographs of the leaf cavity wall revealed degenerated tissue covered by a membrane. Onion leaf cavity membranes apparently are highly impermeable to CO2 and greatly restrict the refixation of leaf cavity CO2 by photosynthetic tissue. PMID:24307095

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

    PubMed

    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. PMID:26273786

  12. Arabidopsis Transcript and Metabolite Profiles: Ecotype-specific Acclimation to Open-air Elevated [CO2

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A FACE (Free-Air CO2 Enrichment) experiment compared physiological parameters, and transcript and metabolite profiles of Arabidopsis thaliana ecotypes Col-0 and Cvi-0 at ambient (~375ppm) and elevated (~550ppm) CO2 concentration ([CO2]). Photosynthesis and photoassimilate pool sizes were enhanced in...

  13. Hourly and seasonal variation in photosynthesis and stomatal conductance of soybean grown at future CO(2) and ozone concentrations for 3 years under fully open-air field conditions.

    PubMed

    Bernacchi, Carl J; Leakey, Andrew D B; Heady, Lindsey E; Morgan, Patrick B; Dohleman, Frank G; McGrath, Justin M; Gillespie, Kelly M; Wittig, Victoria E; Rogers, Alistair; Long, Stephen P; Ort, Donald R

    2006-11-01

    It is anticipated that enrichment of the atmosphere with CO(2) will increase photosynthetic carbon assimilation in C3 plants. Analysis of controlled environment studies conducted to date indicates that plant growth at concentrations of carbon dioxide ([CO(2)]) anticipated for 2050 ( approximately 550 micromol mol(-1)) will stimulate leaf photosynthetic carbon assimilation (A) by 20 to 40%. Simultaneously, concentrations of tropospheric ozone ([O(3)]) are expected to increase by 2050, and growth in controlled environments at elevated [O(3)] significantly reduces A. However, the simultaneous effects of both increases on a major crop under open-air conditions have never been tested. Over three consecutive growing seasons > 4700 individual measurements of A, photosynthetic electron transport (J(PSII)) and stomatal conductance (g(s)) were measured on Glycine max (L.) Merr. (soybean). Experimental treatments used free-air gas concentration enrichment (FACE) technology in a fully replicated, factorial complete block design. The mean A in the control plots was 14.5 micromol m(-2) s(-1). At elevated [CO(2)], mean A was 24% higher and the treatment effect was statistically significant on 80% of days. There was a strong positive correlation between daytime maximum temperatures and mean daily integrated A at elevated [CO(2)], which accounted for much of the variation in CO(2) effect among days. The effect of elevated [CO(2)] on photosynthesis also tended to be greater under water stress conditions. The elevated [O(3)] treatment had no statistically significant effect on mean A, g(s) or J(PSII) on newly expanded leaves. Combined elevation of [CO(2)] and [O(3)] resulted in a slightly smaller increase in average A than when [CO(2)] alone was elevated, and was significantly greater than the control on 67% of days. Thus, the change in atmospheric composition predicted for the middle of this century will, based on the results of a 3 year open-air field experiment, have smaller

  14. Photorespiration in Air and High CO(2)-Grown Chlorella pyrenoidosa.

    PubMed

    Shelp, B J; Canvin, D T

    1981-12-01

    Oxygen inhibition of photosynthesis and CO(2) evolution during photorespiration were compared in high CO(2)-grown and air-grown Chlorella pyrenoidosa, using the artificial leaf technique at pH 5.0. High CO(2) cells, in contrast to air-grown cells, exhibited a marked inhibition of photosynthesis by O(2), which appeared to be competitive and similar in magnitude to that in higher C(3) plants. With increasing time after transfer to air, the photosynthetic rate in high CO(2) cells increased while the O(2) effect declined. Photorespiration, measured as the difference between (14)CO(2) and (12)CO(2) uptake, was much greater and sensitive to O(2) in high CO(2) cells. Some CO(2) evolution was also present in air-grown algae; however, it did not appear to be sensitive to O(2). True photosynthesis was not affected by O(2) in either case. The data indicate that the difference between high CO(2) and air-grown algae could be attributed to the magnitude of CO(2) evolution. This conclusion is discussed with reference to the oxygenase reaction and the control of photorespiration in algae. PMID:16662134

  15. Application of amine-tethered solid sorbents for direct CO2 capture from the ambient air.

    PubMed

    Choi, Sunho; Drese, Jeffrey H; Eisenberger, Peter M; Jones, Christopher W

    2011-03-15

    While current carbon capture and sequestration (CCS) technologies for large point sources can help address the impact of CO(2) buildup on global climate change, these technologies can at best slow the rate of increase of the atmospheric CO(2) concentration. In contrast, the direct CO(2) capture from ambient air offers the potential to be a truly carbon negative technology. We propose here that amine-based solid adsorbents have significant promise as key components of a hypothetical air capture process. Specifically, the CO(2) capture characteristics of hyperbranched aminosilica (HAS) materials are evaluated here using CO(2) mixtures that simulate ambient atmospheric concentrations (400 ppm CO(2) = "air capture") as well as more traditional conditions simulating flue gas (10% CO(2)). The air capture experiments demonstrate that the adsorption capacity of HAS adsorbents are only marginally influenced even with a significant dilution of the CO(2) concentration by a factor of 250, while capturing CO(2) reversibly without significant degradation of performance in multicyclic operation. These results suggest that solid amine-based air capture processes have the potential to be an effective approach to extracting CO(2) from the ambient air. PMID:21323309

  16. How will soybeans respond to elevated temperatures when grown at future CO2 concentrations under fully open air field conditions (FACE)?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Elevating CO2 and temperature both influence plant productivity through their direct effects on photosynthesis. This is true because O2 and CO2 compete for same active sites of ribulose bisphophate carboxylase-oxygenase (rubisco). Increasing temperature increases oxygenation relative to carboxylati...

  17. Long-term growth of soybean and maize at elevated [CO2] under free-air concentration enrichment (FACE) reduces soil moisture depletion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stomatal conductance (gs) is lower when plants are grown at elevated [CO2] compared to ambient [CO2]. This is often assumed to reduce plant water use and ameliorate water stress by conserving soil moisture. However, under field conditions canopy size, canopy structure, microclimate and fluxes of wat...

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

    NASA Astrophysics Data System (ADS)

    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

  19. Hazardous indoor CO2 concentrations in volcanic environments.

    PubMed

    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. PMID:27155095

  20. CO2 Fluxes and Concentrations in a Residential Area in the Southern Hemisphere

    NASA Astrophysics Data System (ADS)

    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.

  1. [Uptake 14CO2 from air and accumulation of 14C in hornwort].

    PubMed

    Shi, Jian-Jun

    2011-02-01

    Uptake 14CO2 from air and accumulation of 14C in the hornwort were studied by using the isotope-tracer techniques in order to get a better understanding of the environmental behavior of 14CO2. And the possibility of hornwort used as the indicator plant in the supervisor of 14CO2 air pollution was discussed. The results show that the hornwort could uptake 14CO2 from the air by some way and formed an accumulating trend. The main way was that the hornwort absorbed free 14CO2 and H 14CO3- from the water through photosynthesis. During the introducing 14CO2, the increasing rate of 14C specific activity in dry hornwort and fresh hornwort were between 91.9-95.6 Bq/(g x d) and 6.1-6.3 Bq/(g x d), respectively, which was roughly equal to the increasing rate in the wheat. The results indicate that the hornwort had strong ability of absorbing 14CO2 indirectly through water. The hornwort has an certain concentration of 14CO2. And the concentration factor (CF) values rise with the introduction of 14CO2 and decline slowly after it reached the maximum value. Owing to its accumulation of 14CO2, hornwort can be used as the indicator plant in the supervisor of 14CO2 air pollution. PMID:21528570

  2. Effect of elevated atmospheric CO2 concentration on soil CO2 and N2O effluxes in a loess grassland

    NASA Astrophysics Data System (ADS)

    Cserhalmi, Dóra; Balogh, János; Papp, Marianna; Horváth, László; Pintér, Krisztina; Nagy, Zoltán

    2014-05-01

    Increasing atmospheric CO2 concentration proved to be the primary factor causing global climate change. Exposition systems to study the response to increasing CO2 levels by the terrestrial vegetation include the open top chamber (OTC) exposition system, also used in this study. Response of biomass growth and ecophysiological variables (e.g. emission of greenhouse gases (CO2, N2O) from the soil) to elevated atmospheric CO2 concentration were investigated in the OTC station, located in the Botanical Garden of the Szent István University, Gödöllő , Hungary. Loess grassland (Salvio nemorosae - Festucetum rupicolae) monoliths were studied in OTCs with target air CO2 concentration of 600 mikromol.mol-1 in 3 chambers. The chamber-effect (shade effect of the side of the chambers) was measured in 3 control chambers under present CO2 level. This management was compared to 3 free air parcels under the natural conditions. Changes of soil temperature and soil water content were recorded in each treatment, while PAR, air temperature, precipitation, wind velocity and humidity were measured by a micrometeorological station. Plant biomass was cut down to 5 cm height once a year. Leaf area index (LAI) was estimated weekly from ceptometer measurements, soil CO2 and N2O effluxes were also measured weekly during the growing period and less frequently during the rest of the year. Soil water content in the upper 30 cm of the soil was lower in the chambers by 3 % (v/v) in average than in the field plots. Soil temperature in the chambers at 3 cm depth was 1.5oC lower than in the free air parcels probably due to the shading effect of the larger biomass in the chambers. In the chambers (both the high CO2 and control ones) biomass values (536.59 ±222.43 gm-2) were higher than in the free parcels (315.67 ±73.36 gm-2). Average LAI was also higher (3.07 ± 2.78) in the chambers than in the free air treatment (2.08 ± 1.95). Soil respiration values in the high CO2 treatment was higher in

  3. BOREAS TE-5 CO2 Concentration and Stable Isotope Composition

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Ehleriinger, Jim; Brooks, J. Renee; Flanagan, Larry

    2000-01-01

    The BOREAS TE-5 team collected measurements in the NSA and SSA on gas exchange, gas composition, and tree growth. This data set contains measurements of the concentration and stable carbon (C-13/C-12 and oxygen (O-18/O-16) isotope ratios of atmospheric CO2 in air samples collected at different heights within forest canopies. The data were collected to determine the influence of photosynthesis and respiration by the forest ecosystems on the concentration and stable isotope ratio of atmospheric CO2 These measurements were collected at the SSA during each 1994 IFC at OJP, OBS, and OA sites. Measurements were also collected at the NSA during each 1994 IFC at the OJP, T6R5S TE UBS, and T2Q6A TE OA sites. The stable isotope ratios are expressed using standard delta notation and in units of per mil. The isotope ratios are expressed relative to the international standard, PDB, for both carbon and oxygen samples. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Activity Archive Center (DAAC).

  4. Effects of CO2 on stomatal conductance: do stomata open at very high CO2 concentrations?

    NASA Technical Reports Server (NTRS)

    Wheeler, R. M.; Mackowiak, C. L.; Yorio, N. C.; Sager, J. C.

    1999-01-01

    Potato and wheat plants were grown for 50 d at 400, 1000 and 10000 micromoles mol-1 carbon dioxide (CO2). and sweetpotato and soybean were grown at 1000 micromoles mol-1 CO2 in controlled environment chambers to study stomatal conductance and plant water use. Lighting was provided with fluorescent lamps as a 12 h photoperiod with 300 micromoles m-2 s-1 PAR. Mid-day stomatal conductances for potato were greatest at 400 and 10000 micromoles mol-1 and least at 1000 micromoles mol-1 CO2. Mid-day conductances for wheat were greatest at 400 micromoles mol-1 and least at 1000 and 10000 micromoles mol-1 CO2. Mid-dark period conductances for potato were significantly greater at 10000 micromoles mol-1 than at 400 or 1000 micromoles mol-1, whereas dark conductance for wheat was similar in all CO2 treatments. Temporarily changing the CO2 concentration from the native 1000 micromoles mol-1 to 400 micromoles mol-1 increased mid-day conductance for all species, while temporarily changing from 1000 to 10000 micromoles mol-1 also increased conductance for potato and sweetpotato. Temporarily changing the dark period CO2 from 1000 to 10000 micromoles mol-1 increased conductance for potato, soybean and sweetpotato. In all cases, the stomatal responses were reversible, i.e. conductances returned to original rates following temporary changes in CO2 concentration. Canopy water use for potato was greatest at 10000, intermediate at 400, and least at 1000 micromoles mol-1 CO2, whereas canopy water use for wheat was greatest at 400 and similar at 1000 and 10000 micromoles mol-1 CO2. Elevated CO2 treatments (i.e. 1000 and 10000 micromoles mol-1) resulted in increased plant biomass for both wheat and potato relative to 400 micromoles mol-1, and no injurious effects were apparent from the 10000 micromoles mol-1 treatment. Results indicate that super-elevated CO2 (i.e. 10000 micromoles mol-1) can increase stomatal conductance in some species, particularly during the dark period, resulting in

  5. Integration of the electrochemical depolorized CO2 concentrator with the Bosch CO2 reduction subsystem

    NASA Technical Reports Server (NTRS)

    Schubert, F. H.; Wynveen, R. A.; Hallick, T. M.

    1976-01-01

    Regenerative processes for the revitalization of spacecraft atmospheres require an Oxygen Reclamation System (ORS) for the collection of carbon dioxide and water vapor and the recovery of oxygen from these metabolic products. Three life support subsystems uniquely qualified to form such an ORS are an Electrochemical CO2 Depolarized Concentrator (EDC), a CO2 Reduction Subsystem (BRS) and a Water Electrolysis Subsystem (WES). A program to develop and test the interface hardware and control concepts necessary for integrated operation of a four man capacity EDC with a four man capacity BRS was successfully completed. The control concept implemented proved successful in operating the EDC with the BRS for both constant CO2 loading as well as variable CO2 loading, based on a repetitive mission profile of the Space Station Prototype (SSP).

  6. What are the costs of limiting CO2 concentrations?

    SciTech Connect

    Edmonds, James A.; Sands, Ronald D.

    2003-01-01

    The problem of stabilizing the concentration of CO2 is fundamentally different than the problem of stabilizing the concentration of a conventional pollutant or even other non-CO2 greenhouse gases. A fraction of any net anthropogenic emission is permanently committed to the atmosphere and in the very long term net anthropogenic emissions must cease if atmospheric CO2 concentrations are to be stabilized. Many of the technologies that could play a large future role in limiting cumulative carbon emissions are minor elements in the present energy system. A portfolio of technologies will be needed to address the variety of technology needs across the world's regions and over time.

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

    PubMed Central

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

    2011-01-01

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

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

    PubMed

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

    2011-12-20

    Capturing carbon dioxide from the atmosphere ("air capture") in an industrial process has been proposed as an option for stabilizing global CO(2) concentrations. Published analyses suggest these air capture systems may cost a few hundred dollars per tonne of CO(2), making it cost competitive with mainstream CO(2) mitigation options like renewable energy, nuclear power, and carbon dioxide capture and storage from large CO(2) emitting point sources. We investigate the thermodynamic efficiencies of commercial separation systems as well as trace gas removal systems to better understand and constrain the energy requirements and costs of these air capture systems. Our empirical analyses of operating commercial processes suggest that the energetic and financial costs of capturing CO(2) from the air are likely to have been underestimated. Specifically, our analysis of existing gas separation systems suggests that, unless air capture significantly outperforms these systems, it is likely to require more than 400 kJ of work per mole of CO(2), requiring it to be powered by CO(2)-neutral power sources in order to be CO(2) negative. We estimate that total system costs of an air capture system will be on the order of $1,000 per tonne of CO(2), based on experience with as-built large-scale trace gas removal systems. PMID:22143760

  9. Physiological responses during short-term acclimation to increasing atmospheric CO2 concentration in Pinus nigra

    NASA Astrophysics Data System (ADS)

    Maseyk, K. S.; Biron, P.; Richard, P.; Canale, L.; Bariac, T.

    2010-12-01

    The response of plants to increasing atmospheric CO2 concentrations is a key element shaping future biogeochemical cycles. While leaf scale manipulations of CO2 concentration provide us with a wealth of information on the biochemical response of leaf photosynthesis, these responses do not necessarily translate to whole plant responses at higher CO2 concentrations. Evidence from free air enrichment studies show different responses of plant gas exchange parameters in their degree of acclimation to long-term increases in atmospheric CO2, relative to those predicted from the instantaneous responses of leaf-level measurements. However, free air enrichment studies are also limited by the fact that they represent a single step change in CO2 and it is therefore of interest to understand how physiological responses derived from leaf-scale increases in CO2 compare to those from exposing the whole plant to increases CO2 across a range of elevated CO2 concentrations. Here we report on a study into the short-term leaf level physiological responses to CO2 concentration of small (1.5m) Pinus nigra trees that were maintained at different CO2 concentrations, therefore allowing potential whole-plant feedback effects to be incorporated into the responses. The trees were maintained at 20°C and 50-60% RH at three ambient CO2 concentrations (Ca of 380 ppm, 500 ppm, 800 ppm) for ~10 days each in a 10m3 growth chamber. The response of gas exchange parameters (assimilation rate, A, stomatal conductance, gs, internal CO2 concentration, Ci, transpiration, E) to leaf level changes in CO2 were measured at each ambient CO2 concentration, allowing the instantaneous response to be compared to the ‘acclimated’ response (i.e. that at the ambient concentration). Typical A-Ci response curves were seen at all CO2 concentrations, with saturation at Ci above 800ppm and Ca above 1500 ppm. However, even over this short period, assimilation rates at a given CO2 concentration deceased with increasing

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

    NASA Astrophysics Data System (ADS)

    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

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

    PubMed

    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. PMID:26263620

  12. Industrial CO2 Removal: CO2 Capture from Ambient Air and Geological Sequestration

    SciTech Connect

    Dooley, James J.

    2011-06-08

    This abstract and its accompanying presentation will provide an overview of two distinct industrial processes for removing carbon dioxide (CO2) from the atmosphere as a means of addressing anthropogenic climate change. The first of these is carbon dioxide capture and storage (CCS) coupled with large scale biomass production (hereafter referred to as bioCCS). The second is CO2 capture from ambient air via industrial systems (hereafter referred to as direct air capture (DAC)). In both systems, the captured CO2 would be injected into deep geologic formations so as to isolate it from the atmosphere. The technical literature is clear that both of these technologies are technically feasible as of today (IPCC, 2005; Keith, 2009; Lackner, 2009; Luckow et al., 2010; Ranjan and Herzog, 2011). What is uncertain is the relative cost of these industrial ambient-air CO2 removal systems when compared to other emissions mitigation measures, the ultimate timing and scale of their deployment, and the resolution of potential site specific constraints that would impact their ultimate commercial deployment.

  13. Food for Thought: Lower-Than-Expected Crop Yield Stimulation with Rising CO2 Concentrations

    NASA Astrophysics Data System (ADS)

    Long, Stephen P.; Ainsworth, Elizabeth A.; Leakey, Andrew D. B.; Nösberger, Josef; Ort, Donald R.

    2006-06-01

    Model projections suggest that although increased temperature and decreased soil moisture will act to reduce global crop yields by 2050, the direct fertilization effect of rising carbon dioxide concentration ([CO2]) will offset these losses. The CO2 fertilization factors used in models to project future yields were derived from enclosure studies conducted approximately 20 years ago. Free-air concentration enrichment (FACE) technology has now facilitated large-scale trials of the major grain crops at elevated [CO2] under fully open-air field conditions. In those trials, elevated [CO2] enhanced yield by ~50% less than in enclosure studies. This casts serious doubt on projections that rising [CO2] will fully offset losses due to climate change.

  14. Continuous Measurements of the Free Dissolved CO2 Concentration during Photosynthesis of Marine Plants

    PubMed Central

    Brechignac, François; Andre, Marcel

    1985-01-01

    An experimental system consisting of a gas exchange column linked to an assimilation chamber has been developed to record continuously the free dissolved CO2 concentration in seawater containing marine plants. From experiments performed on the red macroalga Chondrus crispus (Rhodophyta, Gigartinales), this measurement is in agreement with the free CO2 concentration calculated from the resistance to CO2 exchanges in a biphasic system (gas and liquid) as earlier reported. The response time of this apparatus is short enough to detect, in conditions of constant pH, a photosynthesis-caused gradient between free CO2 and HCO3− pools which half-equilibrates in 25 seconds. Abolished by carbonic anhydrase, the magnitude of this gradient increases with decreasing time of seawater transit from the chamber to the column apparatus. But its maximum magnitude (0.35 micromolar CO2) is negligible compared to the difference between air and free CO2 (11.4 micromolar CO2). This illustrates the extent of the physical limiting-step occurring at the air-water interface when inorganic carbon consumption in seawater is balanced by dissolving gaseous CO2. The direction of this small free CO2/HCO3− gradient indicates that HCO3− is consumed during photosynthesis. PMID:16664281

  15. Cave air ventilation and CO 2 outgassing by radon-222 modeling: How fast do caves breathe?

    NASA Astrophysics Data System (ADS)

    Kowalczk, Andrew J.; Froelich, Philip N.

    2010-01-01

    In general, the rate and timing of calcite precipitation is in part affected by variations in cave air CO 2 concentrations. Knowledge of cave ventilation processes is required to quantify the effect variations in CO 2 concentrations have on speleothem deposition rates and thus paleoclimate records. In this study we use radon-222 ( 222Rn) as a proxy of ventilation to estimate CO 2 outgassing from the cave to the atmosphere, which can be used to infer relative speleothem deposition rates. Hollow Ridge Cave, a wild cave preserve in Marianna, Florida, is instrumented inside and out with multiple micro-meteorological sensor stations that record continuous physical and air chemistry time-series data. Our time series datasets indicate diurnal and seasonal variations in cave air 222Rn and CO 2 concentrations, punctuated by events that provide clues to ventilation and drip water degassing mechanisms. Average cave air 222Rn and CO 2 concentrations vary seasonally between winter ( 222Rn = 50 dpm L - 1 , where 1 dpm L - 1 = 60 Bq m - 3 ; CO 2 = 360 ppmv) and summer ( 222Rn = 1400 dpm L - 1 ; CO 2 = 3900 ppmv). Large amplitude diurnal variations are observed during late summer and autumn ( 222Rn = 6 to 581 dpm L - 1 ; CO 2 = 360 to 2500 ppmv). We employ a simple first-order 222Rn mass balance model to estimate cave air exchange rates with the outside atmosphere. Ventilation occurs via density driven flow and by winds across the entrances which create a 'venturi' effect. The most rapid ventilation occurs 25 m inside the cave near the entrance: 45 h - 1 (1.33 min turnover time). Farther inside (175 m) exchange is slower and maximum ventilation rates are 3 h - 1 (22 min turnover time). We estimate net CO 2 flux from the epikarst to the cave atmosphere using a CO 2 mass balance model tuned with the 222Rn model. Net CO 2 flux from the epikarst is highest in summer (72 mmol m - 2 day - 1 ) and lowest in late autumn and winter (12 mmol m - 2 day - 1 ). Modeled ventilation and net CO 2

  16. C4 Photosynthesis (The CO2-Concentrating Mechanism and Photorespiration).

    PubMed

    Dai, Z.; Ku, MSB.; Edwards, G. E.

    1993-09-01

    Despite previous reports of no apparent photorespiration in C4 plants based on measurements of gas exchange under 2 versus 21% O2 at varying [CO2], photosynthesis in maize (Zea mays) shows a dual response to varying [O2]. The maximum rate of photosynthesis in maize is dependent on O2 (approximately 10%). This O2 dependence is not related to stomatal conductance, because measurements were made at constant intercellular CO2 concentration (Ci); it may be linked to respiration or pseudocyclic electron flow. At a given Ci, increasing [O2] above 10% inhibits both the rate of photosynthesis, measured under high light, and the maximum quantum yield, measured under limiting light ([phi]CO2). The dual effect of O2 is masked if measurements are made under only 2 versus 21% O2. The inhibition of both photosynthesis and [phi]CO2 by O2 (measured above 10% O2) with decreasing Ci increases in a very similar manner, characteristically of O2 inhibition due to photorespiration. There is a sharp increase in O2 inhibition when the Ci decreases below 50 [mu]bar of CO2. Also, increasing temperature, which favors photorespiration, causes a decrease in [phi]CO2 under limiting CO2 and 40% O2. By comparing the degree of inhibition of photosynthesis in maize with that in the C3 species wheat (Triticum aestivum) at varying Ci, the effectiveness of C4 photosynthesis in concentrating CO2 in the leaf was evaluated. Under high light, 30[deg]C, and atmospheric levels of CO2 (340 [mu]bar), where there is little inhibition of photosynthesis in maize by O2, the estimated level of CO2 around ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) in the bundle sheath compartment was 900 [mu]bar, which is about 3 times higher than the value around Rubisco in mesophyll cells of wheat. A high [CO2] is maintained in the bundle sheath compartment in maize until Ci decreases below approximately 100 [mu]bar. The results from these gas exchange measurements indicate that photorespiration occurs in maize but

  17. Reducing the cost of Ca-based direct air capture of CO2.

    PubMed

    Zeman, Frank

    2014-10-01

    Direct air capture, the chemical removal of CO2 directly from the atmosphere, may play a role in mitigating future climate risk or form the basis of a sustainable transportation infrastructure. The current discussion is centered on the estimated cost of the technology and its link to "overshoot" trajectories, where atmospheric CO2 levels are actively reduced later in the century. The American Physical Society (APS) published a report, later updated, estimating the cost of a one million tonne CO2 per year air capture facility constructed today that highlights several fundamental concepts of chemical air capture. These fundamentals are viewed through the lens of a chemical process that cycles between removing CO2 from the air and releasing the absorbed CO2 in concentrated form. This work builds on the APS report to investigate the effect of modifications to the air capture system based on suggestions in the report and subsequent publications. The work shows that reduced carbon electricity and plastic packing materials (for the contactor) may have significant effects on the overall price, reducing the APS estimate from $610 to $309/tCO2 avoided. Such a reduction does not challenge postcombustion capture from point sources, estimated at $80/tCO2, but does make air capture a feasible alternative for the transportation sector and a potential negative emissions technology. Furthermore, air capture represents atmospheric reductions rather than simply avoided emissions. PMID:25207956

  18. Direct Air Capture of CO2 by Physisorbent Materials.

    PubMed

    Kumar, Amrit; Madden, David G; Lusi, Matteo; Chen, Kai-Jie; Daniels, Emma A; Curtin, Teresa; Perry, John J; Zaworotko, Michael J

    2015-11-23

    Sequestration of CO2, either from gas mixtures or directly from air (direct air capture, DAC), could mitigate carbon emissions. Here five materials are investigated for their ability to adsorb CO2 directly from air and other gas mixtures. The sorbents studied are benchmark materials that encompass four types of porous material, one chemisorbent, TEPA-SBA-15 (amine-modified mesoporous silica) and four physisorbents: Zeolite 13X (inorganic); HKUST-1 and Mg-MOF-74/Mg-dobdc (metal-organic frameworks, MOFs); SIFSIX-3-Ni, (hybrid ultramicroporous material). Temperature-programmed desorption (TPD) experiments afforded information about the contents of each sorbent under equilibrium conditions and their ease of recycling. Accelerated stability tests addressed projected shelf-life of the five sorbents. The four physisorbents were found to be capable of carbon capture from CO2-rich gas mixtures, but competition and reaction with atmospheric moisture significantly reduced their DAC performance. PMID:26440308

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  20. Sensitivity Analysis for Atmospheric Infrared Sounder (AIRS) CO2 Retrieval

    NASA Technical Reports Server (NTRS)

    Gat, Ilana

    2012-01-01

    The Atmospheric Infrared Sounder (AIRS) is a thermal infrared sensor able to retrieve the daily atmospheric state globally for clear as well as partially cloudy field-of-views. The AIRS spectrometer has 2378 channels sensing from 15.4 micrometers to 3.7 micrometers, of which a small subset in the 15 micrometers region has been selected, to date, for CO2 retrieval. To improve upon the current retrieval method, we extended the retrieval calculations to include a prior estimate component and developed a channel ranking system to optimize the channels and number of channels used. The channel ranking system uses a mathematical formalism to rapidly process and assess the retrieval potential of large numbers of channels. Implementing this system, we identifed a larger optimized subset of AIRS channels that can decrease retrieval errors and minimize the overall sensitivity to other iridescent contributors, such as water vapor, ozone, and atmospheric temperature. This methodology selects channels globally by accounting for the latitudinal, longitudinal, and seasonal dependencies of the subset. The new methodology increases accuracy in AIRS CO2 as well as other retrievals and enables the extension of retrieved CO2 vertical profiles to altitudes ranging from the lower troposphere to upper stratosphere. The extended retrieval method for CO2 vertical profile estimation using a maximum-likelihood estimation method. We use model data to demonstrate the beneficial impact of the extended retrieval method using the new channel ranking system on CO2 retrieval.

  1. Rising CO2 concentrations affect settlement behaviour of larval damselfishes

    NASA Astrophysics Data System (ADS)

    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

  2. Is CO2 an Indoor Pollutant? Direct Effects of Low-to-Moderate CO2 Concentrations on Human Decision-Making Performance

    PubMed Central

    Satish, Usha; Shekhar, Krishnamurthy; Hotchi, Toshifumi; Sullivan, Douglas; Streufert, Siegfried; Fisk, William J.

    2012-01-01

    Background: Associations of higher indoor carbon dioxide (CO2) concentrations with impaired work performance, increased health symptoms, and poorer perceived air quality have been attributed to correlation of indoor CO2 with concentrations of other indoor air pollutants that are also influenced by rates of outdoor-air ventilation. Objectives: We assessed direct effects of increased CO2, within the range of indoor concentrations, on decision making. Methods: Twenty-two participants were exposed to CO2 at 600, 1,000, and 2,500 ppm in an office-like chamber, in six groups. Each group was exposed to these conditions in three 2.5-hr sessions, all on 1 day, with exposure order balanced across groups. At 600 ppm, CO2 came from outdoor air and participants’ respiration. Higher concentrations were achieved by injecting ultrapure CO2. Ventilation rate and temperature were constant. Under each condition, participants completed a computer-based test of decision-making performance as well as questionnaires on health symptoms and perceived air quality. Participants and the person administering the decision-making test were blinded to CO2 level. Data were analyzed with analysis of variance models. Results: Relative to 600 ppm, at 1,000 ppm CO2, moderate and statistically significant decrements occurred in six of nine scales of decision-making performance. At 2,500 ppm, large and statistically significant reductions occurred in seven scales of decision-making performance (raw score ratios, 0.06–0.56), but performance on the focused activity scale increased. Conclusions: Direct adverse effects of CO2 on human performance may be economically important and may limit energy-saving reductions in outdoor air ventilation per person in buildings. Confirmation of these findings is needed. PMID:23008272

  3. Estimates of CO2 traffic emissions from mobile concentration measurements

    NASA Astrophysics Data System (ADS)

    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.

  4. A field and laboratory method for monitoring the concentration and isotopic composition of soil CO2.

    PubMed

    Breecker, Dan; Sharp, Zachary D

    2008-01-01

    The stable isotope composition of nmol size gas samples can be determined accurately and precisely using continuous flow isotope ratio mass spectrometry (IRMS). We have developed a technique that exploits this capability in order to measure delta13C and delta18O values and, simultaneously, the concentration of CO2 in sub-mL volume soil air samples. A sampling strategy designed for monitoring CO2 profiles at particular locations of interest is also described. This combined field and laboratory technique provides several advantages over those previously reported: (1) the small sample size required allows soil air to be sampled at a high spatial resolution, (2) the field setup minimizes sampling times and does not require powered equipment, (3) the analytical method avoids the introduction of air (including O2) into the mass spectrometer thereby extending filament life, and (4) pCO2, delta13C and delta18O are determined simultaneously. The reproducibility of measurements of CO2 in synthetic tank air using this technique is: +/-0.08 per thousand (delta13C), +/-0.10 per thousand (delta18O), and +/-0.7% (pCO2) at 5550 ppm. The reproducibility for CO2 in soil air is estimated as: +/-0.06 per thousand (delta13C), +/-0.06 per thousand (delta18O), and +/-1.6% (pCO2). Monitoring soil CO2 using this technique is applicable to studies concerning soil respiration and ecosystem gas exchange, the effect of elevated atmospheric CO2 (e.g. free air carbon dioxide enrichment) on soil processes, soil water budgets including partitioning evaporation from transpiration, pedogenesis and weathering, diffuse solid-earth degassing, and the calibration of speleothem and pedogenic carbonate delta13C values as paleoenvironmental proxies. PMID:18186546

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

    PubMed

    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. PMID:25620370

  6. Systems analysis of the CO2 concentrating mechanism in cyanobacteria

    PubMed Central

    Mangan, Niall M; Brenner, Michael P

    2014-01-01

    Cyanobacteria are photosynthetic bacteria with a unique CO2 concentrating mechanism (CCM), enhancing carbon fixation. Understanding the CCM requires a systems level perspective of how molecular components work together to enhance CO2 fixation. We present a mathematical model of the cyanobacterial CCM, giving the parameter regime (expression levels, catalytic rates, permeability of carboxysome shell) for efficient carbon fixation. Efficiency requires saturating the RuBisCO reaction, staying below saturation for carbonic anhydrase, and avoiding wasteful oxygenation reactions. We find selectivity at the carboxysome shell is not necessary; there is an optimal non-specific carboxysome shell permeability. We compare the efficacy of facilitated CO2 uptake, CO2 scavenging, and HCO3− transport with varying external pH. At the optimal carboxysome permeability, contributions from CO2 scavenging at the cell membrane are small. We examine the cumulative benefits of CCM spatial organization strategies: enzyme co-localization and compartmentalization. DOI: http://dx.doi.org/10.7554/eLife.02043.001 PMID:24842993

  7. Heat-tolerant rice cultivars retain grain appearance quality under free-air CO2 enrichment

    PubMed Central

    2014-01-01

    Background Heat-tolerant rice cultivars have been developed as a countermeasure to poor grain appearance quality under high temperatures. Recent studies showed that elevated CO2 concentrations (E-[CO2]) also reduce grain quality. To determine whether heat-tolerant cultivars also tolerate E-[CO2], we conducted a free-air CO2 enrichment (FACE) experiment with 12 rice cultivars differing in heat tolerance. Results The percentage of undamaged grains of five standard cultivars (Akitakomachi, Kinuhikari, Koshihikari, Matsuribare, Nipponbare) averaged 61.7% in the ambient [CO2] (AMB) plot and 51.7% in the FACE plot, whereas that of heat-tolerant cultivars (Eminokizuna, Wa2398, Kanto 257, Toyama 80, Mineharuka, Kanto 259, Saikai 290) averaged 73.5% in AMB and 71.3% in FACE. This resulted in a significant [CO2] by cultivar interaction. The percentage of white-base or white-back grains increased from 8.4% in AMB to 17.1% in FACE in the sensitive cultivars, but from only 2.1% in AMB to only 4.4% in FACE in the heat-tolerant cultivars. Conclusion Heat-tolerant cultivars retained their grain appearance quality at E-[CO2] under present air temperatures. Further improvements in appearance quality under present conditions will be needed to achieve improvements under E-[CO2], because E-[CO2] will likely lower the threshold temperature for heat stress. PMID:24920972

  8. Instant conversion of air to a clathrate hydrate: CO(2) hydrates directly from moist air and moist CO(2)(g).

    PubMed

    Devlin, J Paul; Monreal, I Abrrey

    2010-12-23

    The rapid conversion of vapor mixtures containing the gases CO(2), H(2)S, and HCN to clathrate hydrates was reported recently. The novel method is based on the pulsing of warm vapor mixtures, including a carrier gas, into a cold condensation chamber. With cooling, the vapors, which also include ∼1% water and either tetrahydrofuran or trimethylene oxide as a catalyst, nucleate aqueous solution nanodroplets that, on a millisecond time scale, crystallize as hydrate nanoparticles that consume 100% of the water. Humid air approximates the content of mixtures used successfully in the vapor-to-hydrate conversions. FTIR spectra are examined for gas hydrates formed directly from air and air enriched with CO(2), as well as hydrate particles for which CO(2)(g) serves as both guest and aerosol medium. In each instance all of the water in the condensed phase converts to a clathrate hydrate. The subsecond ether-catalyzed formation of the hydrates near 230 K requires only a few percent of the CO(2) pressure used in conventional processes that yield fractional amounts of gas hydrates on an hour time scale in the same temperature range. PMID:21105676

  9. Cotton bracts are adapted to a microenvironment of concentrated CO2 produced by rapid fruit respiration

    PubMed Central

    Hu, Yuan-Yuan; Oguchi, Riichi; Yamori, Wataru; von Caemmerer, Susanne; Chow, Wah Soon; Zhang, Wang-Feng

    2013-01-01

    Background and Aims Elucidation of the mechanisms by which plants adapt to elevated CO2 is needed; however, most studies of the mechanisms investigated the response of plants adapted to current atmospheric CO2. The rapid respiration rate of cotton (Gossypium hirsutum) fruits (bolls) produces a concentrated CO2 microenvironment around the bolls and bracts. It has been observed that the intercellular CO2 concentration of a whole fruit (bract and boll) ranges from 500 to 1300 µmol mol−1 depending on the irradiance, even in ambient air. Arguably, this CO2 microenvironment has existed for at least 1·1 million years since the appearance of tetraploid cotton. Therefore, it was hypothesized that the mechanisms by which cotton bracts have adapted to elevated CO2 will indicate how plants will adapt to future increased atmospheric CO2 concentration. Specifically, it is hypothesized that with elevated CO2 the capacity to regenerate ribulose-1,5-bisphosphate (RuBP) will increase relative to RuBP carboxylation. Methods To test this hypothesis, the morphological and physiological traits of bracts and leaves of cotton were measured, including stomatal density, gas exchange and protein contents. Key results Compared with leaves, bracts showed significantly lower stomatal conductance which resulted in a significantly higher water use efficiency. Both gas exchange and protein content showed a significantly greater RuBP regeneration/RuBP carboxylation capacity ratio (Jmax/Vcmax) in bracts than in leaves. Conclusions These results agree with the theoretical prediction that adaptation of photosynthesis to elevated CO2 requires increased RuBP regeneration. Cotton bracts are readily available material for studying adaption to elevated CO2. PMID:23625144

  10. Effect of CO2 concentration on the carbon acquisition of bloom-forming marine phytoplankton

    NASA Astrophysics Data System (ADS)

    Rost, B.; Sültemeyer, D.; Riebesell, U.

    2003-04-01

    In the framework of global change one of the prominent anthropogenic perturbations is the progressive increase in atmospheric CO2 partial pressure (pCO2). The corresponding changes in surface ocean carbonate chemistry are bound to affect marine phytoplankton, in particular their carbon acquisition. Phytoplankton cells have to invest considerable resources in carbon acquisition to ensure high rates of photosynthesis. This constraint is mainly due to the 'imperfection' of their primary carboxylating enzyme RubisCO, which requires high CO2 concentrations for optimal performance. To overcome the low substrate affinity of RubisCO, most phytoplankton species have developed mechanisms to enhance their intracellular CO2 concentration. These CO2 concentrating mechanisms (CCMs) involve active uptake of CO2 and/or HCO3-, as well as the conversion of HCO3- to CO2 catalyzed by carbonic anhydrase (CA). The efficiency and regulation of CCMs appear to differ strongly between major phytoplankton groups, which gives rise to the possibility that increasing CO2 concentrations affect phytoplankton species differently. To assess the effect of CO2 supply on carbon acquisition of phytoplankton we have measured in vivo activities of extracellular CA, photosynthetic O2 evolution, CO2 and HCO3- uptake rates in three bloom-forming phytoplankton species acclimated to different pCO2 levels. The diatom Skeletonema costatum, the flagellate Phaeocystis globosa, and the coccolithophore Emiliania huxleyi, are representatives of main phytoplankton 'functional groups', which each serve a distinct role in marine ecosystem regulation and biogeochemical cycling. Large differences were obtained between the investigated species both with regard to their efficiency to achieve carbon-saturation in photosynthesis and their capability to regulate their CCM as a function of CO2 supply. The observed taxon-specific differences in CO2-sensitivity, if representative for the natural environment, suggest that changes

  11. Variability in AIRS CO2 during active and break phases of Indian summer monsoon.

    PubMed

    Revadekar, J V; Ravi Kumar, K; Tiwari, Yogesh K; Valsala, Vinu

    2016-01-15

    Due to human activities, the atmospheric concentration of Carbon Dioxide (CO2) has been rising extensively since the Industrial Revolution. Indian summer monsoon (ISM) has a dominant westerly component from ocean to land with a strong tendency to ascend and hence may have role in CO2 distribution in lower and middle troposphere over Indian sub-continent. A substantial component of ISM variability arises from the fluctuations on the intra-seasonal scale between active and break phases which correspond to strong and weak monsoon circulation. In view of the above, an attempt is made in this study to examine the AIRS/AQUA satellite retrieved CO2 distribution in response to atmospheric circulation with focus on active and break phase. Correlation analysis indicates the increase in AIRS CO2 linked with strong monsoon circulation. Study also reveals that anomalous circulation pattern during active and break phase show resemblance with high and low values of AIRS CO2. Homogeneous monsoon regions of India show substantial increase in CO2 levels during active phase. Hilly regions of India show strong contrast in CO2 and vertical velocity during active and break phases. PMID:26476061

  12. Predicting the effects of elevated CO2 concentrations on catchment carbon and water fluxes

    NASA Astrophysics Data System (ADS)

    Donohue, R. J.; Roderick, M. L.; McVicar, T.; Farquhar, G. D.

    2014-12-01

    Anthropogenic activities are increasing atmospheric CO2 concentrations. Among the many observed and expected impacts of this on our climate and biosphere, one is the so-called CO2 fertilisation effect. In this effect the efficiency with which vegetation can acquire carbon relative to its water use increases proportionally with CO2 concentration, and this biological response has implications for both carbon and water balances. Despite considerable research into the impacts of CO2 fertilisation, there is still uncertainty on the catchment scale response of vegetation to elevated CO2. Here we present a simple, conceptually based, generic model for quantifying how CO2 fertilisation affects the structure, water use and productivity of vegetation. Using this new Carbon Use Efficiency (CUE) model we can account for Free Air Carbon Enrichment (FACE) experimental results from a diverse range of sites. We use the CUE model to estimate the effect of the ~18% rise in CO2 over the past three decades on the globe's vegetation cover, and transpiration and carbon assimilation rates.

  13. Conversion of CO2 from Air into Methanol Using a Polyamine and a Homogeneous Ruthenium Catalyst.

    PubMed

    Kothandaraman, Jotheeswari; Goeppert, Alain; Czaun, Miklos; Olah, George A; Prakash, G K Surya

    2016-01-27

    A highly efficient homogeneous catalyst system for the production of CH3OH from CO2 using pentaethylenehexamine and Ru-Macho-BH (1) at 125-165 °C in an ethereal solvent has been developed (initial turnover frequency = 70 h(-1) at 145 °C). Ease of separation of CH3OH is demonstrated by simple distillation from the reaction mixture. The robustness of the catalytic system was shown by recycling the catalyst over five runs without significant loss of activity (turnover number > 2000). Various sources of CO2 can be used for this reaction including air, despite its low CO2 concentration (400 ppm). For the first time, we have demonstrated that CO2 captured from air can be directly converted to CH3OH in 79% yield using a homogeneous catalytic system. PMID:26713663

  14. Sea-air of CO2 in the North Pacific using shipboard and satellite data

    NASA Technical Reports Server (NTRS)

    Stephens, Mark P.; Samuels, Geoffrey; Olson, Donald B.; Fine, Rana A.; Takahashi, Taro

    1995-01-01

    A method has been developed to produce high-resolution maps of pCO2 in surface water for the North Pacific using satellite sea surface temperature (SST) data and statistical relationships between measured pCO2 and temperature. In the subtropical North Pacific the pCO in seawater is controlled primarily by temperature. Accordingly, pCO2 values that are calculated from the satellite SST data have good agreement with the measured values (rms deviation of +/- microatm). In the northwestern subpolar region the pCO2 is controlled not only by temperature, but also by significant seasonal changes in the total CO2 concentration, which are caused by seasonal changes in primary production, mixing with subsurface waters and sea-air exchange. Consequently, the parameterization of oceanic p CO2 based on SST data alone is not totally successful in the northwestern region (rms deviation of +/- 40 microatm). The use of additional satellite products, such as wind and ocean color data, as planned for a future study, is considered necessary to account for the pCO2 variability caused by seasonal changes in the total CO2 concentration. The net CO2 flux for the area of the North Pacific included in this study (north of 10 deg N) has been calculated using the monthly pCO2 distributions computed, and monthly wind speeds from the European Centre for Medium-Range Weather Forecasts. The region is found to be a net source to the atmosphere of 1.9 x 10(exp 12) to 5.8 x 10(exp 12) moles of CO2 per year (or 0.02-0.07 Gt C/yr), most of the outflux occurring in the subtropics.

  15. Accelerator Mass Spectrometric determination of radiocarbon in stratospheric CO2, retrieved from AirCore sampling.

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    In this decade, understanding the impact of human activities on climate is one of the key issues of discussion globally. The continuous rise in the concentration of greenhouse gases, e.g., CO2, CH4, etc. in the atmosphere, predominantly due to human activities, is alarming and requires continuous monitoring to understand the dynamics. Radiocarbon is an important atmospheric tracer and one of the many used in the understanding of the global carbon budget, which includes the greenhouse gases like CO2 and CH4. Measurement of 14C (or radiocarbon) in atmospheric CO2 generally requires collection of large air samples (few liters) from which CO2 is extracted and then the concentration of radiocarbon is determined. Currently, Accelerator Mass Spectrometry (AMS) is the most precise, reliable and widely used technique for atmospheric radiocarbon detection. However, the regular collection of air samples from troposphere and stratosphere, for example using aircraft, is prohibitively expensive. AirCore is an innovative atmospheric sampling system, developed by NOAA. It comprises of a long tube descending from a high altitude with one end open and the other closed, and has been demonstrated to be a reliable, cost-effective sampling system for high-altitude profile (up to ~ 30 km) measurements of CH4and CO2(Karion et al. 2010). In Europe, AirCore measurements are being performed on a regular basis near Sodankylä since September 2013. Here we describe the analysis of two such AirCore samples collected in July 2014, Finland, for determining the 14C concentration in stratospheric CO2. The two AirCore samples were collected on consecutive days. Each stratospheric AirCore sample was divided into six fractions, each containing ~ 35 μg CO2 (~9.5 μg C). Each fraction was separately trapped in 1 /4 inch coiled stainless steel tubing for radiocarbon measurements. The procedure for CO2 extraction from the stratospheric air samples; the sample preparation, with samples containing < 10

  16. A joint data assimilation system (Tan-Tracker) to simultaneously estimate surface CO2 fluxes and 3-D atmospheric CO2 concentrations from observations

    NASA Astrophysics Data System (ADS)

    Tian, X.; Xie, Z.; Liu, Y.; Cai, Z.; Fu, Y.; Zhang, H.; Feng, L.

    2014-12-01

    precision for both CO2 concentrations and CO2 fluxes, mainly due to the simultaneous estimation of CO2 concentrations and CFs in our Tan-Tracker data assimilation system. A experiment for assimilating the real dry-air column CO2 retrievals (XCO2) from the Japanese Greenhouse Gases Observation Satellite (GOSAT) further demonstrates its potential wide applications.

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

    PubMed

    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*]. PMID:27012285

  18. Development of balloon-borne CO2 sonde: CO2 vertical profile (0-10km) observations and comparison with the air craft measurements

    NASA Astrophysics Data System (ADS)

    Ouchi, M.; Matsumi, Y.; Nakayama, T.; Machida, T.; Matsueda, H.; Sawa, Y.; Tanaka, T.; Morino, I.; Uchino, O.

    2012-12-01

    The atmospheric CO2 concentration has drastically increased since the Industrial Revolution due to the mass consumption of fossil fuels and natural gas by human activities. CO2 is considered to be a major factor of global warming; therefore it is important to measure CO2 correctly. CO2 vertical profile measurement is the key to estimate CO2 sources and sinks in high precision. However, current CO2 monitoring sites are limited and there are few CO2 vertical profile measurements. We have been developing a balloon-borne instrument that can measure the vertical distribution of CO2 in any place in the world under any kind of weather conditions (CO2 sonde). The target specifications of altitude range is from surface to 10 km. Time resolution is 1min. The CO2 sensor, originally developed for upper air sounding by our team, is based on the non-dispersed infrared absorption spectroscopy technique (NDIR) at the wavelengths of 4.0 and 4.3 micrometer. The data of the optical infrared absorption are transmitted through a GPS sonde with temperature, humidity and GPS data every second. In this study, we will show simultaneous measurement campaigns of the balloon-borne instruments and in-situ aircraft measurements in January and February 2011 in the Tokyo metropolitan area in Japan. We will present the comparisons between the results of CO2 sonde (5 flights) and two types of aircraft measurements. One is observed by the CONTRAIL (Comprehensive Observation Network for TRace gases by AIrLiner) and the other is chartered flight measurements operated by NIES/JAXA.

  19. Capture CO2 from Ambient Air Using Nanoconfined Ion Hydration.

    PubMed

    Shi, Xiaoyang; Xiao, Hang; Lackner, Klaus S; Chen, Xi

    2016-03-14

    Water confined in nanoscopic pores is essential in determining the energetics of many physical and chemical systems. Herein, we report a recently discovered unconventional, reversible chemical reaction driven by water quantities in nanopores. The reduction of the number of water molecules present in the pore space promotes the hydrolysis of CO3(2-) to HCO3(-) and OH(-). This phenomenon led to a nano-structured CO2 sorbent that binds CO2 spontaneously in ambient air when the surrounding is dry, while releasing it when exposed to moisture. The underlying mechanism is elucidated theoretically by computational modeling and verified by experiments. The free energy of CO3 (2-) hydrolysis in nanopores reduces with a decrease of water availability. This promotes the formation of OH(-), which has a high affinity to CO2 . The effect is not limited to carbonate/bicarbonate, but is extendable to a series of ions. Humidity-driven sorption opens a new approach to gas separation technology. PMID:26914978

  20. Mutate Chlorella sp. by nuclear irradiation to fix high concentrations of CO2.

    PubMed

    Cheng, Jun; Huang, Yun; Feng, Jia; Sun, Jing; Zhou, Junhu; Cen, Kefa

    2013-05-01

    To improve biomass productivity and CO2 fixation of microalgae under 15% (v/v) CO2 of flue gas, Chlorella species were mutated by nuclear irradiation and domesticated with high concentrations of CO2. The biomass yield of Chlorella pyrenoidosa mutated using 500 Gy of (60)Co γ irradiation increased by 53.1% (to 1.12 g L(-1)) under air bubbling. The mutants were domesticated with gradually increased high concentrations of CO2 [from 0.038% (v/v) to 15% (v/v)], which increased the biomass yield to 2.41 g L(-1). When light transmission and culture mixing in photo-bioreactors were enhanced at 15% (v/v) CO2, the peak growth rate of the domesticated mutant (named Chlorella PY-ZU1) was increased to 0.68 g L(-1) d(-1). When the ratio of gas flow rate (L min(-1)) to 1L of microalgae culture was 0.011, the peak CO2 fixation rate and the efficiency of Chlorella PY-ZU1 were 1.54 g L(-1) d(-1) and 32.7%, respectively. PMID:23567722

  1. Constraining terrestrial ecosystem CO2 fluxes by integrating models of biogeochemistry and atmospheric transport and data of surface carbon fluxes and atmospheric CO2 concentrations

    NASA Astrophysics Data System (ADS)

    Zhu, Q.; Zhuang, Q.; Henze, D.; Bowman, K.; Chen, M.; Liu, Y.; He, Y.; Matsueda, H.; Machida, T.; Sawa, Y.; Oechel, W.

    2014-09-01

    Regional net carbon fluxes of terrestrial ecosystems could be estimated with either biogeochemistry models by assimilating surface carbon flux measurements or atmospheric CO2 inversions by assimilating observations of atmospheric CO2 concentrations. Here we combine the ecosystem biogeochemistry modeling and atmospheric CO2 inverse modeling to investigate the magnitude and spatial distribution of the terrestrial ecosystem CO2 sources and sinks. First, we constrain a terrestrial ecosystem model (TEM) at site level by assimilating the observed net ecosystem production (NEP) for various plant functional types. We find that the uncertainties of model parameters are reduced up to 90% and model predictability is greatly improved for all the plant functional types (coefficients of determination are enhanced up to 0.73). We then extrapolate the model to a global scale at a 0.5° × 0.5° resolution to estimate the large-scale terrestrial ecosystem CO2 fluxes, which serve as prior for atmospheric CO2 inversion. Second, we constrain the large-scale terrestrial CO2 fluxes by assimilating the GLOBALVIEW-CO2 and mid-tropospheric CO2 retrievals from the Atmospheric Infrared Sounder (AIRS) into an atmospheric transport model (GEOS-Chem). The transport inversion estimates that: (1) the annual terrestrial ecosystem carbon sink in 2003 is -2.47 Pg C yr-1, which agrees reasonably well with the most recent inter-comparison studies of CO2 inversions (-2.82 Pg C yr-1); (2) North America temperate, Europe and Eurasia temperate regions act as major terrestrial carbon sinks; and (3) The posterior transport model is able to reasonably reproduce the atmospheric CO2 concentrations, which are validated against Comprehensive Observation Network for TRace gases by AIrLiner (CONTRAIL) CO2 concentration data. This study indicates that biogeochemistry modeling or atmospheric transport and inverse modeling alone might not be able to well quantify regional terrestrial carbon fluxes. However, combining

  2. Continuous Measurement of CO2 concentration in Arctic Soil by Small Open-path Type CO2 Sensors

    NASA Astrophysics Data System (ADS)

    Nakamoto, K.; Oechel, W. C.; Lipson, D.

    2006-12-01

    Permafrost and seasonally thawed Arctic soils in high northern latitudes hold approximately 25 percent of the world's soil organic carbon. The predicted warming of the Arctic, coupled with regional drying, could release much of the carbon now stored in the Arctic soils. Understanding the mechanisms controlling the release of soil organic carbon as CO2 is critical to predicting sensitive Arctic soils will respond to and influence global climate change. However, there are only a few reports of soil respiration, and very few that report continuous respiration rates. The results of chamber measurements give the overall efflux from the surface and emphasize biological and chemical processes and controls. However, they do not measure soil CO2 concentrations. To our knowledge, continuous measurements of soil CO2 concentration has not been previously conducted in the Arctic, and gas diffusivity of Arctic soils that thaw and freeze are poorly known. To obtain a better understanding of the patterns and controls on carbon release from Arctic soils, long-term measurements of soil respiration and an investigation of the underlying processes were undertaken. In this study, continuous measurements of soil CO2 concentration by small open path type infrared gas analyzers in a revegetated Arctic drained lake basin at Barrow Alaska was undertaken. Measurements were conducted from the beginning of soil thaw in summer through the following winter and summer. Changes in soil CO2 concentration during freezing and thawing processes proved especially interesting. Soil CO2 concentration in the organic layer of the drained lake basin was much higher than that of Typic Psamomoturbals soil from heath vegetation cover in Greenland (Elberling and Brandt 2003) throughout the thawing season. Soil CO2 increased with increasing soil temperature and thaw depth reflecting CO2 production in the soil. Soil CO2 concentration was greater in relatively wet soil than in dry soil. Soil CO2 concentration

  3. Deep Sea Memory of High Atmospheric CO2 Concentration

    NASA Astrophysics Data System (ADS)

    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

  4. Short-term carbon cycling responses of a mature eucalypt woodland to gradual stepwise enrichment of atmospheric CO2 concentration.

    PubMed

    Drake, John E; Macdonald, Catriona A; Tjoelker, Mark G; Crous, Kristine Y; Gimeno, Teresa E; Singh, Brajesh K; Reich, Peter B; Anderson, Ian C; Ellsworth, David S

    2016-01-01

    Projections of future climate are highly sensitive to uncertainties regarding carbon (C) uptake and storage by terrestrial ecosystems. The Eucalyptus Free-Air CO2 Enrichment (EucFACE) experiment was established to study the effects of elevated atmospheric CO2 concentrations (eCO2 ) on a native mature eucalypt woodland with low fertility soils in southeast Australia. In contrast to other FACE experiments, the concentration of CO2 at EucFACE was increased gradually in steps above ambient (+0, 30, 60, 90, 120, and 150 ppm CO2 above ambient of ~400 ppm), with each step lasting approximately 5 weeks. This provided a unique opportunity to study the short-term (weeks to months) response of C cycle flux components to eCO2 across a range of CO2 concentrations in an intact ecosystem. Soil CO2 efflux (i.e., soil respiration or Rsoil ) increased in response to initial enrichment (e.g., +30 and +60 ppm CO2 ) but did not continue to increase as the CO2 enrichment was stepped up to higher concentrations. Light-saturated photosynthesis of canopy leaves (Asat ) also showed similar stimulation by elevated CO2 at +60 ppm as at +150 ppm CO2 . The lack of significant effects of eCO2 on soil moisture, microbial biomass, or activity suggests that the increase in Rsoil likely reflected increased root and rhizosphere respiration rather than increased microbial decomposition of soil organic matter. This rapid increase in Rsoil suggests that under eCO2, additional photosynthate was produced, transported belowground, and respired. The consequences of this increased belowground activity and whether it is sustained through time in mature ecosystems under eCO2 are a priority for future research. PMID:26426394

  5. Determination of radiocarbon in stratospheric CO2, obtained through AirCore sampling.

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    The concentration of Greenhouse Gases (GHG), with carbon dioxide as the most prominent example, has been and still is increasing, predominantly due to emissions from fossil fuel combustion. CO2 is also the most important component of the global carbon cycle. Among other tracers, radiocarbon (Carbon-14) is a unique and an important atmospheric tracer used in the understanding of the global carbon cycle. Radiocarbon is a naturally occurring isotope (radioactive, t 1/2 = 5730 ± 40 years) of carbon produced through the interaction of thermalized neutrons and nitrogen in the upper atmosphere. Generally, for performing atmospheric radiocarbon measurements in the higher atmosphere, large samples (few liters of air) were collected using aircrafts and balloons. However, collecting stratospheric samples on a regular basis for radiocarbon analysis is extremely expensive. Here we describe the determination of radiocarbon concentrations in stratospheric CO2, collected using AirCore sampling. AirCore is an innovative sampling technique for obtaining vertical atmospheric profiles and, in Europe, is done on a regular basis at Sodankylä, Finland for CO2, CH4 and CO. The stratospheric parts of two such AirCore profiles were used in this study as a proof-of-principle. CO2 from the stratospheric air samples were extracted and converted to elemental carbon, which were then measured at the Accelerator Mass Spectrometric (AMS) facility of the Centre for Isotope Research (CIO) at the University of Groningen. The stratospheric part of the AirCore profile was divided into six sections, each contained approximately 10 μg C. A detailed description of the extraction, graphitization, AMS analysis and the derivation of the stratospheric radiocarbon profile will be the main focus. Through our results, we will show that AirCore is a viable sampling method for performing high-precision radiocarbon measurements of stratospheric CO2 with reasonably good spatial resolution on a regular basis

  6. Elevated atmospheric CO 2 concentration and temperature across an urban-rural transect

    NASA Astrophysics Data System (ADS)

    George, K.; Ziska, L. H.; Bunce, J. A.; Quebedeaux, B.

    The heat island effect and the high use of fossil fuels in large city centers are well documented, but by how much fossil fuel consumption is elevating atmospheric CO 2 concentrations and whether elevations in both atmospheric CO 2 and air temperature from rural to urban areas are consistently different from year to year are less well known. Our aim was to record atmospheric CO 2 concentrations, air temperature and other environmental variables in an urban area and compare it to suburban and rural sites to see if urban sites are experiencing climates expected globally in the future with climate change. A transect was established from Baltimore city center (Urban site), to the outer suburbs of Baltimore (suburban site) and out to an organic farm (rural site). At each site a weather station was set-up to monitor environmental variables for 5 years. Atmospheric CO 2 was consistently and significantly increased on average by 66 ppm from the rural to the urban site over the 5 years of the study. Air temperature was also consistently and significantly higher at the urban site (14.8 °C) compared to the suburban (13.6 °C) and rural (12.7 °C) sites. Relative humidity was not different between sites whereas the vapor pressure deficit (VPD) was significantly higher at the urban site compared to the suburban and rural sites. An increase in nitrogen deposition at the rural site of 0.6% and 1.0% compared to the suburban and urban sites was small enough not to affect soil nitrogen content. Dense urban areas with large populations and high vehicular traffic have significantly different microclimates compared to outlying suburban and rural areas. The increases in atmospheric CO 2 and air temperature are similar to changes predicted in the short term with global climate change, therefore providing an environment suitable for studying future effects of climate change on terrestrial ecosystems.

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

    NASA Astrophysics Data System (ADS)

    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

  8. Concentrating on CO2: the Scandinavian and Arctic measurements.

    PubMed

    Bohn, Maria

    2011-01-01

    This article concerns atmospheric carbon dioxide (CO2) measurements made in Scandinavia and in the Arctic region before measurements started at Mauna Loa, Hawaii, in 1958. The CO2 hypothesis of climate change was one reason to measure atmospheric CO2 in the mid-1950s. The earlier history of CO2 measurements--for instance, the work of the chemist Kurt Buch--was also influential in this period. It is unclear when the CO2 hypothesis of climate change began to provide sufficient motivation for measurements, and the measurements may relate in a nonlinear way to the growth in popularity of the hypothesis. Discussions between meteorologist Carl-Gustaf Rossby at Stockholm Högskola and scientists in America reveal how different kinds of CO2 studies varied with regard to precision. PMID:21936192

  9. A Fine-Tuned Fluorinated MOF Addresses the Needs for Trace CO2 Removal and Air Capture Using Physisorption.

    PubMed

    Bhatt, Prashant M; Belmabkhout, Youssef; Cadiau, Amandine; Adil, Karim; Shekhah, Osama; Shkurenko, Aleksander; Barbour, Leonard J; Eddaoudi, Mohamed

    2016-07-27

    The development of functional solid-state materials for carbon capture at low carbon dioxide (CO2) concentrations, namely, from confined spaces (<0.5%) and in particular from air (400 ppm), is of prime importance with respect to energy and environment sustainability. Herein, we report the deliberate construction of a hydrolytically stable fluorinated metal-organic framework (MOF), NbOFFIVE-1-Ni, with the appropriate pore system (size, shape, and functionality), ideal for the effective and energy-efficient removal of trace carbon dioxide. Markedly, the CO2-selective NbOFFIVE-1-Ni exhibits the highest CO2 gravimetric and volumetric uptake (ca. 1.3 mmol/g and 51.4 cm(3) (STP) cm(-3)) for a physical adsorbent at 400 ppm of CO2 and 298 K. Practically, NbOFFIVE-1-Ni offers the complete CO2 desorption at 328 K under vacuum with an associated moderate energy input of 54 kJ/mol, typical for the full CO2 desorption in conventional physical adsorbents but considerably lower than chemical sorbents. Noticeably, the contracted square-like channels, affording the close proximity of the fluorine centers, permitted the enhancement of the CO2-framework interactions and subsequently the attainment of an unprecedented CO2 selectivity at very low CO2 concentrations. The precise localization of the adsorbed CO2 at the vicinity of the periodically aligned fluorine centers, promoting the selective adsorption of CO2, is evidenced by the single-crystal X-ray diffraction study on NbOFFIVE-1-Ni hosting CO2 molecules. Cyclic CO2/N2 mixed-gas column breakthrough experiments under dry and humid conditions corroborate the excellent CO2 selectivity under practical carbon capture conditions. Pertinently, the notable hydrolytic stability positions NbOFFIVE-1-Ni as the new benchmark adsorbent for direct air capture and CO2 removal from confined spaces. PMID:27388208

  10. Performance Prediction Method of CO2 Cycle for Air Cooling

    NASA Astrophysics Data System (ADS)

    Koyama, Shigeru; Xue, Jun; Kuwahara, Ken

    From the perspective of global environmental protection and energy-saving, the research and development on high-efficiency heat pump and refrigeration systems using environment-friendly refrigerants have become one of the most important issues in the air-conditioning and refrigeration sector. In the present work, a steady-state model of the CO2 transcritical cycle for air cooling, which consists of a rotary compressor, a fin-tube gas cooler,a fin-tube evaporator and an expansion valve, has been developed. The detailed model of fin-tube heat exchanger has been constructed by means of the finite volume method, in which the local heat transfer and flow characteristics are evaluated. It should be noted that the effects of the dew condensation generated on the cooling surface are considered in the evaporator model. As a calculation example, the effects of the indoor air wet-bulb temperature on the cycle performance have been examined with this developed simulator.

  11. The optimal atmospheric CO2 concentration for the growth of winter wheat (Triticum aestivum).

    PubMed

    Xu, Ming

    2015-07-20

    This study examined the optimal atmospheric CO2 concentration of the CO2 fertilization effect on the growth of winter wheat with growth chambers where the CO2 concentration was controlled at 400, 600, 800, 1000, and 1200 ppm respectively. I found that initial increase in atmospheric CO2 concentration dramatically enhanced winter wheat growth through the CO2 fertilization effect. However, this CO2 fertilization effect was substantially compromised with further increase in CO2 concentration, demonstrating an optimal CO2 concentration of 889.6, 909.4, and 894.2 ppm for aboveground, belowground, and total biomass, respectively, and 967.8 ppm for leaf photosynthesis. Also, high CO2 concentrations exceeding the optima not only reduced leaf stomatal density, length and conductance, but also changed the spatial distribution pattern of stomata on leaves. In addition, high CO2 concentration also decreased the maximum carboxylation rate (Vc(max)) and the maximum electron transport rate (J(max)) of leaf photosynthesis. However, the high CO2 concentration had little effect on leaf length and plant height. The optimal CO2 fertilization effect found in this study can be used as an indicator in selecting and breeding new wheat strains in adapting to future high atmospheric CO2 concentrations and climate change. PMID:26253981

  12. Formation and Evaluation of Protective Layer over Magnesium Melt Under CO2/Air Mixtures

    NASA Astrophysics Data System (ADS)

    Emami, Samar; Sohn, Hong Yong

    2015-02-01

    Molten magnesium oxidizes rapidly when exposed to air causing melt loss and handling difficulties. The use of certain additive gases to form a protective MgO layer over a magnesium melt has been proposed. The oxidation behavior of molten magnesium in air that contains various concentrations of CO2 was investigated, including the kinetics of the oxide layer growth. Experiments were performed using a thermogravimetric analysis unit in the temperature range of 943 K to 1043 K (670 °C to 770 °C). Results showed that a thin, coherent, and protective MgO-C layer was formed under the test conditions. The thicknesses of this layer formed under CO2/air ranged from 500 nm to 12 μm. Rate parameters were calculated and a model for the process was developed. The morphology and composition of the surface films were studied using SEM and EDS.

  13. Regulation of CO2 Concentrating Mechanism in Cyanobacteria

    PubMed Central

    Burnap, Robert L.; Hagemann, Martin; Kaplan, Aaron

    2015-01-01

    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. PMID:25636131

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

    NASA Technical Reports Server (NTRS)

    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.

  15. Spatial variations in atmospheric CO2 concentrations during the ARCTAS-CARB 2008 Summer Campaign

    NASA Astrophysics Data System (ADS)

    Vadrevu, K. P.; Choi, Y.; Vay, S. A.

    2009-12-01

    The Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) was a major NASA field campaign designed to understand the transport and transformation of trace gases and aerosols on transcontinental and intercontinental scales and their impact on the composition of the arctic atmosphere and climate. Preceding the summer ARCTAS deployment, measurements were conducted over the state of California in collaboration with the California Air Resources Board (CARB) utilizing the airborne chemistry payload already integrated on the NASA DC-8. In situ CO2 measurements were made using a modified infrared CO2 gas analyzer having a precision of 0.1 ppmv and accuracy of ±0.25 ppmv traceable to the WMO scale. This analysis focuses on the atmospheric CO2 variability and biospheric/atmospheric exchange over California. We used multi-satellite remote sensing datasets to relate airborne observations of CO2 to infer sources and sinks. Georeferencing the airborne CO2 transect data with the LANDSAT derived land cover datasets over California suggested significant spatial variations. The airborne CO2 concentrations were found to be 375-380ppm over the Pacific ocean, 385-391ppm in the highly vegetated agricultural areas, 400-420 in the near coastal areas and greater than 425ppmv in the urban areas. Analysis from MODIS fire products suggested significant fires in northern California. CO2 emissions exceeded 425ppmv in the fire affected regions, where mostly Douglas and White Fir conifers and mixed Chaparral vegetation was burnt. Analysis from GOES-East and GOES-West visible satellite imagery suggested significant smoke plumes moving from northern California towards Nevada and Idaho. To infer the biospheric uptake of CO2, we tested the potential correlations between airborne CO2 data and MODIS normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI). Results suggested significant anti-correlations between the airborne CO2 data and

  16. A regenerable solid amine CO2 concentrator for space station

    NASA Technical Reports Server (NTRS)

    Boehm, A. M.; Cusick, R. J.

    1982-01-01

    A regenerable solid amine CO2 control system, which employs water vapor for desorption, is being developed for potential use on long duration space missions. During cyclic operation, CO2 is first absorbed from the cabin atmosphere onto the granular amine. Steam is then used to heat the solid amine bed and desorb the CO2. This paper describes the solid amine system operation and application to the Shuttle Orbiter, Manned Space Platform (MSP) and Space Operations Center (SOC). The importance and interplay of system performance parameters are presented together with supporting data and design characteristics.

  17. Influence of precipitation on the CO2 air-sea flux, an eddy covariance field study

    NASA Astrophysics Data System (ADS)

    Zavarsky, Alexander; Steinhoff, Tobias; Marandino, Christa

    2016-04-01

    During the SPACES-OASIS cruise (July-August 2015) from Durban, SA to Male, MV direct fluxes of CO2 and dimethyl sulfide (DMS) were measured using the eddy covariance (EC) technique. The cruise covered areas of sources and sinks for atmospheric CO2, where the bulk concentration gradient measurements resembled the Takahashi (2009) climatology. Most of the time, bulk CO2 fluxes (F=k* [cwater-cair]), calculated with the parametrization (k) by Nightingale et al. 2000, were in general agreement with direct EC measurements. However, during heavy rain events, the directly measured CO2 fluxes were 4 times higher than predicted. It has been previously described that rain influences the k parametrization of air-sea gas exchange, but this alone cannot explain the measured discrepancy. There is evidence that freshwater input and a change in the carbonate chemistry causes the water side concentration of ?c=cwater-cair to decrease. Unfortunately this cannot be detected by most bulk measurement systems. Using the flux measurements of an additional gas like DMS, this rain influence can be evaluated as DMS does not react to changes in the carbonate system and has a different solubility. A pending question is if the enhanced flux of CO2 in the ocean is sequestered into the ocean mixed layer and below. This question will be tackled using the GOTM model to understand the implications for the global carbon cycle.

  18. Sea-air CO2 fluxes in the Southern Ocean for the period 1990-2009

    NASA Astrophysics Data System (ADS)

    Lenton, A.; Tilbrook, B.; Law, R.; Bakker, D.; Doney, S. C.; Gruber, N.; Hoppema, M.; Ishii, M.; Lovenduski, N. S.; Matear, R. J.; McNeil, B. I.; Metzl, N.; Mikaloff Fletcher, S. E.; Monteiro, P.; Rödenbeck, C.; Sweeney, C.; Takahashi, T.

    2013-01-01

    The Southern Ocean (44° S-75° S) plays a critical role in the global carbon cycle, yet remains one of the most poorly sampled ocean regions. Different approaches have been used to estimate sea-air CO2 fluxes in this region: synthesis of surface ocean observations, ocean biogeochemical models, and atmospheric and ocean inversions. As part of the RECCAP (REgional Carbon Cycle Assessment and Processes) project, we combine these different approaches to quantify and assess the magnitude and variability in Southern Ocean sea-air CO2 fluxes between 1990-2009. Using all models and inversions (26), the integrated median annual sea-air CO2 flux of -0.42 ± 0.07 Pg C yr-1 for the 44° S-75° S region is consistent with the -0.27 ± 0.13 Pg C yr-1 calculated using surface observations. The circumpolar region south of 58° S has a small net annual flux (model and inversion median: -0.04 ± 0.07 Pg C yr-1 and observations: +0.04 ± 0.02 Pg C yr-1), with most of the net annual flux located in the 44° S to 58° S circumpolar band (model and inversion median: -0.36 ± 0.09 Pg C yr-1 and observations: -0.35 ± 0.09 Pg C yr-1). Seasonally, in the 44° S-58° S region, the median of 5 ocean biogeochemical models captures the observed sea-air CO2 flux seasonal cycle, while the median of 11 atmospheric inversions shows little seasonal change in the net flux. South of 58° S, neither atmospheric inversions nor ocean biogeochemical models reproduce the phase and amplitude of the observed seasonal sea-air CO2 flux, particularly in the Austral Winter. Importantly, no individual atmospheric inversion or ocean biogeochemical model is capable of reproducing both the observed annual mean uptake and the observed seasonal cycle. This raises concerns about projecting future changes in Southern Ocean CO2 fluxes. The median interannual variability from atmospheric inversions and ocean biogeochemical models is substantial in the Southern Ocean; up to 25% of the annual mean flux with 25% of this

  19. Simulation of CO 2 concentrations at Tsukuba tall tower using WRF-CO 2 tracer transport model

    NASA Astrophysics Data System (ADS)

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

    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 oE) 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.

  20. Membrane-Associated Polypeptides Induced in Chlamydomonas by Limiting CO(2) Concentrations.

    PubMed

    Spalding, M H; Jeffrey, M

    1989-01-01

    Chlamydomonas reinhardtii and other unicellular green algae have a high apparent affinity for CO(2), little O(2) inhibition of photosynthesis, and reduced photorespiration. These characteristics result from operation of a CO(2)-concentrating system. The CO(2)-concentrating system involves active inorganic carbon transport and is under environmental control. Cells grown at limiting CO(2) concentrations have inorganic carbon transport activity, but cells grown at 5% CO(2) do not. Four membrane-associated polypeptides (M(r) 19, 21, 35, and 36 kilodaltons) have been identified which either appear or increase in abundance during adaptation to limiting CO(2) concentrations. The appearance of two of the polypeptides occurs over roughly the same time course as the appearance of the CO(2)-concentrating system activity in response to CO(2) limitation. PMID:16666503

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

    Zhang, Xia; Gurney, Kevin R.; Rayner, Peter; Baker, David; Liu, Yu-ping

    2016-02-01

    Recent advances in fossil fuel CO2 (FFCO2) emission inventories enable sensitivity tests of simulated atmospheric CO2 concentrations to sub-annual variations in FFCO2 emissions and what this implies for the interpretation of observed CO2. Six experiments are conducted to investigate the potential impact of three cycles of FFCO2 emission variability (diurnal, weekly and monthly) using a global tracer transport model. Results show an annual FFCO2 rectification varying from -1.35 to +0.13 ppm from the combination of all three cycles. This rectification is driven by a large negative diurnal FFCO2 rectification due to the covariation of diurnal FFCO2 emissions and diurnal vertical mixing, as well as a smaller positive seasonal FFCO2 rectification driven by the covariation of monthly FFCO2 emissions and monthly atmospheric transport. The diurnal FFCO2 emissions are responsible for a diurnal FFCO2 concentration amplitude of up to 9.12 ppm at the grid cell scale. Similarly, the monthly FFCO2 emissions are responsible for a simulated seasonal CO2 amplitude of up to 6.11 ppm at the grid cell scale. The impact of the diurnal FFCO2 emissions, when only sampled in the local afternoon, is also important, causing an increase of +1.13 ppmv at the grid cell scale. The simulated CO2 concentration impacts from the diurnally and seasonally varying FFCO2 emissions are centered over large source regions in the Northern Hemisphere, extending to downwind regions. This study demonstrates the influence of sub-annual variations in FFCO2 emissions on simulated CO2 concentration and suggests that inversion studies must take account of these variations in the affected regions.

  3. Effects of elevated atmospheric CO2 concentrations, clipping regimen and differential day/night atmospheric warming on tissue nitrogen concentrations of a perennial pasture grass

    PubMed Central

    Volder, Astrid; Gifford, Roger M.; Evans, John R.

    2015-01-01

    Forecasting the effects of climate change on nitrogen (N) cycling in pastures requires an understanding of changes in tissue N. We examined the effects of elevated atmospheric CO2 concentration, atmospheric warming and simulated grazing (clipping frequency) on aboveground and belowground tissue N concentrations and C : N ratios of a C3 pasture grass. Phalaris aquatica L. cv. ‘Holdfast’ was grown in the field in six transparent temperature gradient tunnels (18 × 1.5 × 1.5 m each), three at ambient atmospheric CO2 and three at 759 p.p.m. CO2. Within each tunnel, there were three air temperature treatments: ambient control, +2.2/+4.0 °C above ambient day/night warming and +3.0 °C continuous warming. A frequent and an infrequent clipping treatment were applied to each warming × CO2 combination. Green leaf N concentrations were decreased by elevated CO2 and increased by more frequent clipping. Both warming treatments increased leaf N concentrations under ambient CO2 concentrations, but did not significantly alter leaf N concentrations under elevated CO2 concentrations. Nitrogen resorption from leaves was decreased under elevated CO2 conditions as well as by more frequent clipping. Fine root N concentrations decreased strongly with increasing soil depth and were further decreased at the 10–60 cm soil depths by elevated CO2 concentrations. The interaction between the CO2 and warming treatments showed that leaf N concentration was affected in a non-additive manner. Changes in leaf C : N ratios were driven by changes in N concentration. Overall, the effects of CO2, warming and clipping treatments on aboveground tissue N concentrations were much greater than on belowground tissue. PMID:26272874

  4. Effects of elevated atmospheric CO2 concentrations, clipping regimen and differential day/night atmospheric warming on tissue nitrogen concentrations of a perennial pasture grass.

    PubMed

    Volder, Astrid; Gifford, Roger M; Evans, John R

    2015-01-01

    Forecasting the effects of climate change on nitrogen (N) cycling in pastures requires an understanding of changes in tissue N. We examined the effects of elevated atmospheric CO2 concentration, atmospheric warming and simulated grazing (clipping frequency) on aboveground and belowground tissue N concentrations and C : N ratios of a C3 pasture grass. Phalaris aquatica L. cv. 'Holdfast' was grown in the field in six transparent temperature gradient tunnels (18 × 1.5 × 1.5 m each), three at ambient atmospheric CO2 and three at 759 p.p.m. CO2. Within each tunnel, there were three air temperature treatments: ambient control, +2.2/+4.0 °C above ambient day/night warming and +3.0 °C continuous warming. A frequent and an infrequent clipping treatment were applied to each warming × CO2 combination. Green leaf N concentrations were decreased by elevated CO2 and increased by more frequent clipping. Both warming treatments increased leaf N concentrations under ambient CO2 concentrations, but did not significantly alter leaf N concentrations under elevated CO2 concentrations. Nitrogen resorption from leaves was decreased under elevated CO2 conditions as well as by more frequent clipping. Fine root N concentrations decreased strongly with increasing soil depth and were further decreased at the 10-60 cm soil depths by elevated CO2 concentrations. The interaction between the CO2 and warming treatments showed that leaf N concentration was affected in a non-additive manner. Changes in leaf C : N ratios were driven by changes in N concentration. Overall, the effects of CO2, warming and clipping treatments on aboveground tissue N concentrations were much greater than on belowground tissue. PMID:26272874

  5. Effects of incubation in an atmosphere of 20% CO2 in air on the Syrian hamster embryo clonal transformation assay.

    PubMed

    Przygoda, R T; Takayama, K; Traul, K A; Tummey, A

    1985-01-01

    An atmosphere containing 10% CO2 has been generally accepted as optimal for the growth of Syrian hamster embryo cells in a clonal transformation assay. Data presented in this paper show that 10% CO2 may not be the optimum environment for this assay. Using 10 or 20% (analytically measured) CO2 in air (1 atm pressure), hamster embryo cell pools were examined for clonal growth characteristics and transformability using five known carcinogens and a single noncarcinogenic compound. At 10% CO2, only 2 of 11 pools were transformed by the five carcinogens but not by the noncarcinogen. At 20% CO2, six of seven pools were transformed by the five carcinogens and not by the noncarcinogen. Further, the transformation frequencies were found to be greater in cultures incubated in an atmosphere consisting of 20% CO2 in air. The data also show that 20% CO2 increased the cloning efficiency of these cells. A comparison of the 10 and 20% CO2 data to results reported from other laboratories suggests that conflicting interlaboratory results with this assay system may be due, in part, to variations of CO2 concentrations. In some instances, the CO2 levels indicated by incubator flow meters vary considerably from analytically determined CO2 values. To prevent these CO2 discrepancies and their resultant effects on transformation and cloning efficiency, methods for monitoring the CO2 environment other than flow meters are recommended. The observation of increased cloning efficiencies and transformation rates strongly suggests that culture incubation at 20% CO2 is a preferred environment for the conduct of this assay. PMID:3936836

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

    NASA Astrophysics Data System (ADS)

    Turi, G.; Lachkar, Z.; Gruber, N.

    2013-08-01

    nutrient concentrations of the upwelled waters a primary determinant of the overall source/sink nature of the CalCS. The comparison of the standard simulation with one for preindustrial conditions show that the CalCS is taking up anthropogenic CO2 at a rate of about -1 mol C m-2 yr-1, implying that the region was a small source of CO2 to the atmosphere in preindustrial times. The air-sea CO2 fluxes vary substantially in time, both on seasonal and sub-seasonal timescales, largely driven by variations in surface ocean pCO2. There are important differences among the subregions. Notably, the total variance of the fluxes in the central nearshore CalCS is roughly 4-5 times larger than elsewhere. Most of the variability in pCO2 is associated with the seasonal cycle, except in the nearshore, where sub-seasonal variations driven by mesoscale processes dominate. In the regions offshore of 100 km, changes in surface temperature are the main driver, while in the nearshore region, changes in surface temperature, as well as anomalies in DIC and alkalinity (Alk) owing to changes in circulation, biological productivity and air-sea CO2 fluxes dominate. The dominance of eddy-driven variability in the nearshore 100 km leads to a complex spatiotemporal mosaic of surface ocean pCO2 and air-sea CO2 fluxes that require a substantial observational effort to determine the source/sink nature of this region reliably.

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

    NASA Astrophysics Data System (ADS)

    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

  8. Phytochemical changes in leaves of subtropical grasses and fynbos shrubs at elevated atmospheric CO 2 concentrations

    NASA Astrophysics Data System (ADS)

    Hattas, D.; Stock, W. D.; Mabusela, W. T.; Green, I. R.

    2005-07-01

    The effects of elevated atmospheric CO 2 concentrations on plant polyphenolic, tannin, nitrogen, phosphorus and total nonstructural carbohydrate concentrations were investigated in leaves of subtropical grass and fynbos shrub species. The hypothesis tested was that carbon-based secondary compounds would increase when carbon gain is in excess of growth requirements. This premise was tested in two ecosystems involving plants with different photosynthetic mechanisms and growth strategies. The first ecosystem comprised grasses from a C 4-dominated, subtropical grassland, where three plots were subjected to three different free air CO 2 enrichment treatments, i.e., elevated (600 to 800 μmol mol -1), intermediate (400 μmol mol -1) and ambient atmospheric CO 2. One of the seven grass species, Alloteropsis semialata, had a C 3 photosynthetic pathway while the other grasses were all C 4. The second ecosystem was simulated in a microcosm experiment where three fynbos species were grown in open-top chambers at ambient and 700 μmol mol -1 atmospheric CO 2 in low nutrient acid sands typical of south western coastal and mountain fynbos ecosystems. Results showed that polyphenolics and tannins did not increase in the grass species under elevated CO 2 and only in Leucadendron laureolum among the fynbos species. Similarly, foliar nitrogen content of grasses was largely unaffected by elevated CO 2, and among the fynbos species, only L. laureolum and Leucadendron xanthoconus showed changes in foliar nitrogen content under elevated CO 2, but these were of different magnitude. The overall decrease in nitrogen and phosphorus and consequent increase in C:N and C:P ratio in both ecosystems, along with the increase in polyphenolics and tannins in L. laureolum in the fynbos ecosystem, may negatively affect forage quality and decomposition rates. It is concluded that fast growing grasses do not experience sink limitation and invest extra carbon into growth rather than polyphenolics and

  9. [Advances in research on CO2 concentrating mechanism of green algae].

    PubMed

    Xia, Jianrong; Gao, Kunshan

    2002-11-01

    Unicellular green algae plays a key role in freshwater ecosystem, which possesses a CO2 concentrating mechanism that can increase the level of CO2 at the active site of ribulose bisphosphate carboxylase-oxygenase (Rubisco) by actively transporting inorganic carbon when adapted to low CO2 concentration. The mechanism results in an increase in photosynthetic rate, and a decrease in photorespiration. This mechanism and its environmental regulation such as light, temperature, CO2 concentration and nutrient are reviewed in this paper to enhance further studies on response of phytoplankton to elevated atmospheric CO2 concentration in China. PMID:12625019

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

    NASA Astrophysics Data System (ADS)

    Turi, G.; Lachkar, Z.; Gruber, N.

    2014-02-01

    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-biogeochemical oceanic model on the basis of the Regional Oceanic Modeling System (ROMS). 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 ± 3.6 Tg C yr-1, corresponding to an average flux density of -0.05 ± 0.20 mol C m-2 yr-1. This near zero flux is a consequence of an almost complete regional compensation between (i) strong outgassing in the nearshore region (first 100 km) that brings waters with high concentrations of dissolved inorganic carbon (DIC) to the surface and (ii) and a weaker, but more widespread uptake flux in the offshore region due to an intense biological reduction of this DIC, driven by the nutrients that are upwelled together with the DIC. The air-sea CO2 fluxes vary substantially in time, both on seasonal and sub-seasonal timescales, largely driven by variations in surface ocean pCO2. Most of the variability in pCO2 is associated with the seasonal cycle, with the exception of the nearshore region, where sub-seasonal variations driven by mesoscale processes dominate. In the regions offshore of 100 km, changes in surface temperature are the main driver, while in the nearshore region, changes in surface temperature, as well as anomalies in DIC and alkalinity (Alk) owing to changes in circulation, biological productivity and air-sea CO2 fluxes dominate. The prevalence of eddy-driven variability in the nearshore 100 km leads to a complex spatiotemporal mosaic of surface ocean pCO2 and air-sea CO2 fluxes that require a substantial observational effort to determine the source

  11. Assessing model sensitivity and uncertainty across multiple Free-Air CO2 Enrichment experiments.

    NASA Astrophysics Data System (ADS)

    Cowdery, E.; Dietze, M.

    2015-12-01

    As atmospheric levels of carbon dioxide levels continue to increase, it is critical that terrestrial ecosystem models can accurately predict ecological responses to the changing environment. Current predictions of net primary productivity (NPP) in response to elevated atmospheric CO2 concentrations are highly variable and contain a considerable amount of uncertainty. It is necessary that we understand which factors are driving this uncertainty. The Free-Air CO2 Enrichment (FACE) experiments have equipped us with a rich data source that can be used to calibrate and validate these model predictions. To identify and evaluate the assumptions causing inter-model differences we performed model sensitivity and uncertainty analysis across ambient and elevated CO2 treatments using the Data Assimilation Linked Ecosystem Carbon (DALEC) model and the Ecosystem Demography Model (ED2), two process-based models ranging from low to high complexity respectively. These modeled process responses were compared to experimental data from the Kennedy Space Center Open Top Chamber Experiment, the Nevada Desert Free Air CO2 Enrichment Facility, the Rhinelander FACE experiment, the Wyoming Prairie Heating and CO2 Enrichment Experiment, the Duke Forest Face experiment and the Oak Ridge Experiment on CO2 Enrichment. By leveraging data access proxy and data tilling services provided by the BrownDog data curation project alongside analysis modules available in the Predictive Ecosystem Analyzer (PEcAn), we produced automated, repeatable benchmarking workflows that are generalized to incorporate different sites and ecological models. Combining the observed patterns of uncertainty between the two models with results of the recent FACE-model data synthesis project (FACE-MDS) can help identify which processes need further study and additional data constraints. These findings can be used to inform future experimental design and in turn can provide informative starting point for data assimilation.

  12. Free-air CO2 enrichment of sorghum: soil carbon and nitrogen dynamics.

    PubMed

    Prior, S A; Torbert, H A; Runion, G B; Rogers, H H; Kimball, B A

    2008-01-01

    The positive impact of elevated atmospheric CO(2) concentration on crop biomass production suggests more carbon inputs to soil. Further study on the effect of elevated CO(2) on soil carbon and nitrogen dynamics is key to understanding the potential for long-term carbon storage in soil. Soil samples (0- to 5-, 5- to 10-, and 10- to 20-cm depths) were collected after 2 yr of grain sorghum [Sorghum bicolor (L.) Moench.] production under two atmospheric CO(2) levels: (370 [ambient] and 550 muL L(-1) [free-air CO(2) enrichment; FACE]) and two water treatments (ample water and limited water) on a Trix clay loam (fine, loamy, mixed [calcareous], hyperthermic Typic Torrifluvents) at Maricopa, AZ. In addition to assessing treatment effects on soil organic C and total N, potential C and N mineralization and C turnover were determined in a 60-d laboratory incubation study. After 2 yr of FACE, soil C and N were significantly increased at all soil depths. Water regime had no effect on these measures. Increased total N in the soil was associated with reduced N mineralization under FACE. Results indicated that potential C turnover was reduced under water deficit conditions at the top soil depth. Carbon turnover was not affected under FACE, implying that the observed increase in soil C with elevated CO(2) may be stable relative to ambient CO(2) conditions. Results suggest that, over the short-term, a small increase in soil C storage could occur under elevated atmospheric CO(2) conditions in sorghum production systems with differing water regimes. PMID:18453395

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

    NASA Astrophysics Data System (ADS)

    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

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

    PubMed

    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

  15. Effects of free-air CO2 and temperature enrichment on soybean growth and development

    NASA Astrophysics Data System (ADS)

    Ruiz Vera, U. M.; Bernacchi, C. J.

    2012-12-01

    According to the growing degree days approach, the progression of plant developmental stages requires certain accumulation of heat; therefore greenhouse gas-induced warming of the atmosphere could contribute to more rapid plant development. However, the influence of rising carbon dioxide concentration ([CO2]) on development of crops is uncertain, accelerating and other times delaying certain developmental stages. In soybean, the increase of [CO2] is shown to delay reproductive development, which is attributed to a higher investment of resources into extra nodes. The combined effects of elevated temperature and [CO2] can have significant changes in the progression through development that can influence on total grain production, carbon uptake, and susceptibility to early end-of-season frosts. We designed the Temperature by Free Air CO2 Enrichment (T-FACE) experiment to test over two growing seasons (2009 and 2011) and under field conditions the impact of increased temperature and/or [CO2] on soybean. The heated T-FACE subplots were situated in the larger FACE plots at 385 or 585 ppm of [CO2] and subjected to either ambient or heated (+~3.5°C) temperatures. The experiment is full factorial with ambient temperature and [CO2] (control), elevated temperature (eT), elevated [CO2] (eC) and combined (eT+eC) treatments. We hypothesized that soybean grown (1) under elevated [CO2] will produce more nodes than control, (2) under high temperature will produce nodes faster than control and (3) under both elevated temperature and [CO2] will produce more nodes in less time than control. For reproductive development, we hypothesized that (1) reproductive development will initiate simultaneously regardless of increased [CO2] or temperature because soybean reproduction is triggered by day length, (2) elevated temperature will accelerate the progression through key reproductive stages and (3) the delay in soybean reproductive development by elevated [CO2] will be ameliorated by the

  16. CO2 Capture from the Air: Technology Assessment and Implications for Climate Policy

    NASA Astrophysics Data System (ADS)

    Keith, D. W.

    2002-05-01

    for global climate policy are examined using DIAM [2], a stylized integrated assessment model. We find that air capture can fundamentally alter the temporal dynamics of global warming mitigation. The reason for this is that air capture differs from conventional mitigation in three key aspects. First, it removes emissions from any part of the economy with equal ease or difficulty, so its cost provides an absolute cap on the cost of mitigation. Second, it permits reduction in concentrations faster than the natural carbon cycle: the effects of irreversibility are thus partly alleviated. Third, because it is less coupled with the energy system, air capture may offer stronger economies of scale and smaller adjustment costs than the more conventional mitigation technologies. Air capture limits the total cost of a worst-case climate scenario. In an optimal sequential decision framework with uncertainty, existence of air capture decreases the need for near-term precautionary abatement. Like geoengineering, air capture thus poses a moral hazard. 1. S. Elliott, et al. Compensation of atmospheric CO2 buildup through engineered chemical sinkage. Geophys. Res. Let., 28:1235-1238, 2001. 2. Minh Ha-Duong, Michael J. Grubb, and Jean-Charles Hourcade. Influence of socioeconomic inertia and uncertainty on optimal CO2-emission abatement. Nature, 390: 270-274, 1997.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  18. Comparing surface and mid-troposphere CO2 concentration and fluxes from central U.S. grasslands

    NASA Astrophysics Data System (ADS)

    Cochran, F. V.; Brunsell, N. A.; Quick, A. T.

    2010-12-01

    Terrestrial ecosystem dynamics influence the Earth’s climate system, which is affected by variations in atmospheric carbon dioxide (CO2). Assessments of CO2 concentration and net fluxes at regional scales are needed to diminish uncertainties related to the effects of land-use change on ecosystem processes, to identify land management practices that have the potential to mitigate CO2 emissions, and to discern sources and sinks within geopolitical boundaries for reasons of carbon accountability. Understanding how surface CO2 concentration and flux dynamics within heterogeneous landscapes scale to mid-troposphere concentrations is the focus of this study. CO2 flux data from three eddy covariance (EC) towers in northeastern Kansas are compared to mid-tropospheric data collected by the Atmospheric Infrared Sounder (AIRS). EC tower data from two watershed sites on the Konza Prairie Biological Station (KPBS) for the period 2006-2010 and one study site at the Nelson Environmental Study Area (NESA) for the period 2007-2010 are examined. KPBS site 1D is primarily C4 grasses, burned annually; KPBS site 4B is a mix of C3 forbs and C4 grasses, burned every four years; and the NESA site is a mix of C3/C4 grasses, burned approximately every five years, and experiencing woody encroachment. Results show higher concentration of CO2 in the mid-troposphere. Furthermore, mid-troposphere CO2 exhibited daily and seasonal lags and decreased amplitude in flux dynamics compared to surface CO2. Long-term, combined observations of surface and atmospheric CO2 offer the potential for a better understanding of the natural processes and anthropogenic activities related to CO2 source-sink dynamics, seasonal and interannual variability, and climate forcings, including temperature and precipitation changes.

  19. Laser Sounder for Global Measurement of CO2 Concentrations in the Troposphere from Space: Progress

    NASA Technical Reports Server (NTRS)

    Abshire, J. B.; Krainak, M.; Riris, H. J.; Sun, X.; Riris, H.; Andrews, A. E.; Collatz, J.

    2004-01-01

    We describe progress toward developing a laser-based technique for the remote measurement of the tropospheric CO2 concentrations from orbit. Our goal is to demonstrate a lidar technique and instrument technology that will permit measurements of the CO2 column abundance in the lower troposphere from aircraft at the few ppm level, with a capability of scaling to permit global CO2 measurements from orbit. Accurate measurements of the tropospheric CO2 mixing ratio from space are challenging due to the many potential error sources. These include possible interference from other trace gas species, the effects of temperature, clouds, aerosols & turbulence in the path, changes in surface reflectivity, and variability in dry air density caused by changes in atmospheric pressure, water vapor and topographic height. Some potential instrumental errors include frequency drifts in the transmitter, small transmission and sensitivity drifts in the instrument. High signal-to-noise ratios and measurement stability are needed for mixing ratio estimates at the few ppm level. We have been developing a laser sounder approach as a candidate for a future space mission. It utilizes multiple different laser transmitters to permit simultaneous measurement of CO2 and O2 extinction, and aerosol backscatter in the same measurement path. It directs the narrow co-aligned laser beams from the instrument's fiber lasers toward nadir, and measures the energy of the strong laser echoes reflected from the Earth's land and water surfaces. During the measurement its narrow linewidth lasers are rapidly tuned on- and off- selected CO2 line near 1572 nm and an O2 absorption line near 770 nm. The receiver measures the energies of the laser echoes from the surface and any clouds and aerosols in the path with photon counting detectors. Ratioing the on- to off-line echo pulse energies for each gas permits the column extinction and column densities of CO2 and O2 to be estimated simultaneously via the

  20. Lower responsiveness of canopy evapotranspiration rate than of leaf stomatal conductance to open-air CO2 elevation in rice.

    PubMed

    Shimono, Hiroyuki; Nakamura, Hirofumi; Hasegawa, Toshihiro; Okada, Masumi

    2013-08-01

    An elevated atmospheric CO2 concentration ([CO2 ]) can reduce stomatal conductance of leaves for most plant species, including rice (Oryza sativa L.). However, few studies have quantified seasonal changes in the effects of elevated [CO2 ] on canopy evapotranspiration, which integrates the response of stomatal conductance of individual leaves with other responses, such as leaf area expansion, changes in leaf surface temperature, and changes in developmental stages, in field conditions. We conducted a field experiment to measure seasonal changes in stomatal conductance of the uppermost leaves and in the evapotranspiration, transpiration, and evaporation rates using a lysimeter method. The study was conducted for flooded rice under open-air CO2 elevation. Stomatal conductance decreased by 27% under elevated [CO2 ], averaged throughout the growing season, and evapotranspiration decreased by an average of 5% during the same period. The decrease in daily evapotranspiration caused by elevated [CO2 ] was more significantly correlated with air temperature and leaf area index (LAI) rather than with other parameters of solar radiation, days after transplanting, vapor-pressure deficit and FAO reference evapotranspiration. This indicates that higher air temperatures, within the range from 16 to 27 °C, and a larger LAI, within the range from 0 to 4 m(2)  m(-2) , can increase the magnitude of the decrease in evapotranspiration rate caused by elevated [CO2 ]. The crop coefficient (i.e. the evapotranspiration rate divided by the FAO reference evapotranspiration rate) was 1.24 at ambient [CO2 ] and 1.17 at elevated [CO2 ]. This study provides the first direct measurement of the effects of elevated [CO2 ] on rice canopy evapotranspiration under open-air conditions using the lysimeter method, and the results will improve future predictions of water use in rice fields. PMID:23564676

  1. Free Air CO2 Enrichment (FACE) Data from the Duke Forest FACE Facility

    DOE Data Explorer

    DOE has conducted trace gas enrichment experiments since the mid 1990s. The FACE Data Management System is a central repository and archive for Free-Air Carbon Dioxide Enrichment (FACE) data, as well as for the related open-top chamber (OTC) experiments. FACE Data Management System is located at DOEÆs Carbon Dioxide Information Analysis Center (CDIAC). While the data from the various FACE sites, each one a unique user facility, are centralized at CDIAC, each of the FACE sites presents its own view of its activities and information. For that reason, DOE Data Explorer users are advised to see both the central repository at http://public.ornl.gov/face/index.shtml and the individual home pages of each site. The Duke University FACE website actually presents information on several FACE experiments. The Forest-Atmosphere Carbon Transfer and Storage (FACTS-I) facility is located in the Blackwood Division of the Duke Forest. It consists of four free-air CO2 enrichment (FACE) plots that provide elevated atmospheric CO2 concentration and four plots that provide ambient CO2 control. The system has been in operation since June, 1994 in the prototype plot, and since August, 1996 in the three additional plots. The prototype plot and its reference were halved with a barrier inserted in the soil in 1998 to conduct, together with five additional plot pairs, CO2 X soil nutrient enrichment experiments. The rest of the plots were partitioned in early 2005 and incorporated into the CO2 X nutrient experiment. To increase statistical power, four additional ambient plots were established in January, 2005, halved, and one half of each fertilized. [copied from http://face.env.duke.edu/description.cfm] The Duke FACE home page makes information available from both completed and ongoing projects, provides a searchable database of publications and presentations, and data, images, and links to related websites.

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Isotopic air sampling in a tallgrass prairie to partition net ecosystem CO2 exchange

    NASA Astrophysics Data System (ADS)

    Lai, Chun-Ta; Schauer, Andrew J.; Owensby, Clenton; Ham, Jay M.; Ehleringer, James R.

    2003-09-01

    Stable isotope ratios of various ecosystem components and net ecosystem exchange (NEE) CO2 fluxes were measured in a C3-C4 mixture tallgrass prairie near Manhattan, Kansas. The July 2002 study period was chosen because of contrasting soil moisture contents, which allowed us to address the effects of drought on photosynthetic CO2 uptake and isotopic discrimination. Significantly higher NEE fluxes were observed for both daytime uptake and nighttime respiration during well-watered conditions when compared to a drought period. Given these differences, we investigated two carbon-flux partitioning questions: (1) What proportions of NEE were contributed by C3 versus C4 species? (2) What proportions of NEE fluxes resulted from canopy assimilation versus ecosystem respiration? To evaluate these questions, air samples were collected every 2 hours during daytime for 3 consecutive days at the same height as the eddy covariance system. These air samples were analyzed for both carbon isotope ratios and CO2 concentrations to establish an empirical relationship for isoflux calculations. An automated air sampling system was used to collect nighttime air samples to estimate the carbon isotope ratios of ecosystem respiration (δR) at weekly intervals for the entire growing season. Models of C3 and C4 photosynthesis were employed to estimate bulk canopy intercellular CO2 concentration in order to calculate photosynthetic discrimination against 13C. Our isotope/NEE results showed that for this grassland, C4 vegetation contributed ˜80% of the NEE fluxes during the drought period and later ˜100% of the NEE fluxes in response to an impulse of intense precipitation. For the entire growing season, the C4 contribution ranged from ˜68% early in the spring to nearly 100% in the late summer. Using an isotopic approach, the calculated partitioned respiratory fluxes were slightly greater than chamber-measured estimates during midday under well-watered conditions. In addition, time series

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

    NASA Astrophysics Data System (ADS)

    Zhou, Cong; Shi, Runhe; Gao, Wei

    2015-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

  6. The growth of soybean under free air [CO(2)] enrichment (FACE) stimulates photosynthesis while decreasing in vivo Rubisco capacity.

    PubMed

    Bernacchi, Carl J; Morgan, Patrick B; Ort, Donald R; Long, Stephen P

    2005-01-01

    Down-regulation of light-saturated photosynthesis (A(sat)) at elevated atmospheric CO(2) concentration, [CO(2)], has been demonstrated for many C(3) species and is often associated with inability to utilize additional photosynthate and/or nitrogen limitation. In soybean, a nitrogen-fixing species, both limitations are less likely than in crops lacking an N-fixing symbiont. Prior studies have used controlled environment or field enclosures where the artificial environment can modify responses to [CO(2)]. A soybean free air [CO(2)] enrichment (FACE) facility has provided the first opportunity to analyze the effects of elevated [CO(2)] on photosynthesis under fully open-air conditions. Potential ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) carboxylation (V(c,max)) and electron transport through photosystem II (J(max)) were determined from the responses of A(sat) to intercellular [CO(2)] (C(i)) throughout two growing seasons. Mesophyll conductance to CO(2) (g(m)) was determined from the responses of A(sat) and whole chain electron transport (J) to light. Elevated [CO(2)] increased A(sat) by 15-20% even though there was a small, statistically significant, decrease in V(c,max). This differs from previous studies in that V(c,max)/J(max) decreased, inferring a shift in resource investment away from Rubisco. This raised the C(i) at which the transition from Rubisco-limited to ribulose-1,5-bisphosphate regeneration-limited photosynthesis occurred. The decrease in V(c,max) was not the result of a change in g(m), which was unchanged by elevated [CO(2)]. This first analysis of limitations to soybean photosynthesis under fully open-air conditions reveals important differences to prior studies that have used enclosures to elevate [CO(2)], most significantly a smaller response of A(sat) and an apparent shift in resources away from Rubisco relative to capacity for electron transport. PMID:15252734

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

    NASA Astrophysics Data System (ADS)

    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

  8. Sensitivity of the air-sea CO2 exchange in the Baltic Sea and Danish inner waters to atmospheric short-term variability

    NASA Astrophysics Data System (ADS)

    Lansø, A. S.; Bendtsen, J.; Christensen, J. H.; Sørensen, L. L.; Chen, H.; Meijer, H. A. J.; Geels, C.

    2015-05-01

    Minimising the uncertainties in estimates of air-sea CO2 exchange is an important step toward increasing the confidence in assessments of the CO2 cycle. Using an atmospheric transport model makes it possible to investigate the direct impact of atmospheric parameters on the air-sea CO2 flux along with its sensitivity to, for example, short-term temporal variability in wind speed, atmospheric mixing height and atmospheric CO2 concentration. With this study, the importance of high spatiotemporal resolution of atmospheric parameters for the air-sea CO2 flux is assessed for six sub-basins within the Baltic Sea and Danish inner waters. A new climatology of surface water partial pressure of CO2 (pCO2w) has been developed for this coastal area based on available data from monitoring stations and on-board pCO2w measuring systems. Parameterisations depending on wind speed were applied for the transfer velocity to calculate the air-sea CO2 flux. Two model simulations were conducted - one including short-term variability in atmospheric CO2 (VAT), and one where it was not included (CAT). A seasonal cycle in the air-sea CO2 flux was found for both simulations for all sub-basins with uptake of CO2 in summer and release of CO2 to the atmosphere in winter. During the simulated period 2005-2010, the average annual net uptake of atmospheric CO2 for the Baltic Sea, Danish straits and Kattegat was 287 and 471 Gg C yr-1 for the VAT and CAT simulations, respectively. The obtained difference of 184 Gg C yr-1 was found to be significant, and thus ignoring short-term variability in atmospheric CO2 does have a sizeable effect on the air-sea CO2 exchange. The combination of the atmospheric model and the new pCO2w fields has also made it possible to make an estimate of the marine part of the Danish CO2 budget for the first time. A net annual uptake of 2613 Gg C yr-1 was found for the Danish waters. A large uncertainty is connected to the air-sea CO2 flux in particular caused by the transfer

  9. Sensitivity of the air-sea CO2 exchange in the Baltic Sea and Danish inner waters to atmospheric short term variability

    NASA Astrophysics Data System (ADS)

    Lansø, A. S.; Bendtsen, J.; Christensen, J. H.; Sørensen, L. L.; Chen, H.; Meijer, H. A. J.; Geels, C.

    2014-12-01

    Minimising the uncertainties in estimates of air-sea CO2 exchange is an important step toward increasing the confidence in assessments of the CO2 cycle. Using an atmospheric transport model makes it possible to investigate the direct impact of atmospheric parameters on the air-sea CO2 flux along with its sensitivity to e.g. short-term temporal variability in wind speed, atmospheric mixing height and the atmospheric CO2 concentration. With this study the importance of high spatiotemporal resolution of atmospheric parameters for the air-sea CO2 flux is assessed for six sub-basins within the Baltic Sea and Danish inner waters. A new climatology of surface water partial pressure of CO2 (pCO2) has been developed for this coastal area based on available data from monitoring stations and underway pCO2 measuring systems. Parameterisations depending on wind speed were applied for the transfer velocity to calculate the air-sea CO2 flux. Two model simulations were conducted - one including short term variability in atmospheric CO2 (VAT), and one where it was not included (CAT). A seasonal cycle in the air-sea CO2 flux was found for both simulations for all sub-basins with uptake of CO2 in summer and release of CO2 to the atmosphere in winter. During the simulated period 2005-2010 the average annual net uptake of atmospheric CO2 for the Baltic Sea, Danish Straits and Kattegat was 287 and 471 Gg C yr-1 for the VAT and CAT simulations, respectively. The obtained difference of 184 Gg C yr-1 was found to be significant, and thus ignoring short term variability in atmospheric CO2 does have a sizeable effect on the air-sea CO2 exchange. The combination of the atmospheric model and the new pCO2 fields has also made it possible to make an estimate of the marine part of the Danish CO2 budget for the first time. A net annual uptake of 2613 Gg C yr-1 was found for the Danish waters. A large uncertainty is connected to the air-sea CO2 flux in particular caused by the transfer velocity

  10. CO2 Emissions from Air Travel by AGU and ESA Conference Attendees

    NASA Astrophysics Data System (ADS)

    Scott, B.; Plug, L. J.

    2003-12-01

    Air travel by scientists is one contributor to rising concentrations of CO2 and other greenhouse gases in the atmosphere. To assess the magnitude of this contribution in per-capita and overall terms, we calculated emissions derived from air travel for two major scientific conferences held in 2002: the western meeting of the American Geophysical Union (AGU) in San Francisco and the Ecological Society of America meeting in Tucson (ESA). Round trip travel distance for sampled attendees is 7971 +/- 6968 km (1 sigma range given, n=337) for AGU and 5452 +/- 5664 km for ESA (n=263), conservatively assuming great circle routes were followed. Using accepted CO2 production rates for commercial aircraft, mean AGU emissions are 1.3 tonnes per attendee and 12351 tonnes total and for ESA 0.9 tonnes per attendee and 3140 tonnes total. Although small compared to total anthropogenic emissions (2.275 x 1010 tonnes y-1 in 1999), per attendee emissions are significant compared to annual per-capita emissions; CO2 emission per AGU and ESA attendee exceeds the per capita annual emission of 42% and 19% of Earth's population, respectively. Per attendee AGU emissions are ≈6% of U.S. and ≈14% of British and Japanese per capita annual emission. Relocation of AGU and ESA to cities which minimize travel distances, Denver and Omaha respectively, would result in modest emission reductions of 8% and 14% (assuming 2002 attendee composition). To form a preliminary estimate of annual CO2 emissions for scientists in academia, we surveyed Earth Science faculty at our home institution. Mean annual air travel distance for professional activities was 38064 km y-1 (7 respondents). The consequent release of 6.1 tonnes y-1 of CO2 is 30% of annual per capita emissions in North America, and exceeds global per capita average of 4 tonnes y-1 by 150%. Society and the environment often benefit from scientific enquiry which is facilitated by travel. These benefits, however, might be balanced against the

  11. Elevated CO(2) concentration affects leaf photosynthesis-nitrogen relationships in Pinus taeda over nine years in FACE.

    PubMed

    Crous, Kristine Y; Walters, Michael B; Ellsworth, David S

    2008-04-01

    To investigate whether long-term elevated carbon dioxide concentration ([CO(2)]) causes declines in photosynthetic enhancement and leaf nitrogen (N) owing to limited soil fertility, we measured photosynthesis, carboxylation capacity and area-based leaf nitrogen concentration (N(a)) in Pinus taeda L. growing in a long-term free-air CO(2) enrichment (FACE) facility at an N-limited site. We also determined how maximum rates of carboxylation (V(cmax)) and electron transport (J(max)) varied with N(a) under elevated [CO(2)]. In trees exposed to elevated [CO(2)] for 5 to 9 years, the slope of the relationship between leaf photosynthetic capacity (A(net-Ca)) and N(a) was significantly reduced by 37% in 1-year-old needles, whereas it was unaffected in current-year needles. The slope of the relationships of both V(cmax) and J(max) with N(a) decreased in 1-year-old needles after up to 9 years of growth in elevated [CO(2)], which was accompanied by a 15% reduction in N allocation to the carboxylating enzyme. Nitrogen fertilization (110 kg N ha(-1)) in the ninth year of exposure to elevated [CO(2)] restored the slopes of the relationships of V(cmax) and J(max) with N(a) to those of control trees (i.e., in ambient [CO(2)]). The J(max):V(cmax) ratio was unaffected by either [CO(2)] or N fertilization. Changes in the apparent allocation of N to photosynthetic components may be an important adjustment in pines exposed to elevated [CO(2)] on low-fertility sites. We conclude that fundamental relationships between photosynthesis or its component processes with N(a) may be altered in aging pine needles after more than 5 years of exposure to elevated atmospheric [CO(2)]. PMID:18244946

  12. Development of a Next-Generation Membrane-Integrated Adsorption Processor for CO2 Removal and Compression for Closed-Loop Air Revitalization Systems

    NASA Technical Reports Server (NTRS)

    Mulloth, Lila; LeVan, Douglas

    2002-01-01

    The current CO2 removal technology of NASA is very energy intensive and contains many non-optimized subsystems. This paper discusses the concept of a next-generation, membrane integrated, adsorption processor for CO2 removal nd compression in closed-loop air revitalization systems. This processor will use many times less power than NASA's current CO2 removal technology and will be capable of maintaining a lower CO2 concentration in the cabin than that can be achieved by the existing CO2 removal systems. The compact, consolidated, configuration of gas dryer, CO2 separator, and CO2 compressor will allow continuous recycling of humid air in the cabin and supply of compressed CO2 to the reduction unit for oxygen recovery. The device has potential application to the International Space Station and future, long duration, transit, and planetary missions.

  13. A multi-layer, closed-loop system for continuous measurement of CO2 concentrations and its isotopic signature in forest soils as a basis for CO2 efflux calculation and for revealing its controls

    NASA Astrophysics Data System (ADS)

    Jochheim, Hubert; Wirth, Stephan

    2015-04-01

    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 two 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.

  14. Pyropia yezoensis can utilize CO2 in the air during moderate dehydration

    NASA Astrophysics Data System (ADS)

    Zhou, Wei; He, Linwen; Yang, Fang; Lin, Apeng; Zhang, Baoyu; Niu, Jianfeng; Wang, Guangce

    2014-03-01

    Pyropia yezoensis, an intertidal seaweed, experiences regular dehydration and rehydration with the tides. In this study, the responses of P. yezoensis to dehydration and rehydration under high and low CO2 concentrations ((600-700)×10-6 and (40-80)×10-6, named Group I and Group II respectively) were investigated. The thalli of Group I had a significantly higher effective photosystem II quantum yield than the thalli of Group II at 71% absolute water content (AWC). There was little difference between thalli morphology, total Rubisco activity and total protein content at 100% and 71% AWC, which might be the basis for the normal performance of photosynthesis during moderate dehydration. A higher effective photosystem I quantum yield was observed in the thalli subjected to a low CO2 concentration during moderate dehydration, which might be caused by the enhancement of cyclic electron flow. These results suggested that P. yezoensis can directly utilize CO2 in ambient air during moderate dehydration.

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

    PubMed Central

    Zhao, Xing-Zheng; Wang, Gen-Xuan; Shen, Zhu-Xia; Zhang, Hao; Qiu, Mu-Qing

    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. PMID:16532530

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

    PubMed

    Zhao, Xing-zheng; Wang, Gen-xuan; Shen, Zhu-xia; Zhang, Hao; Qiu, Mu-qing

    2006-04-01

    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 CO(2) concentrations and different soil moisture when the possible effects of elevated CO(2) concentration on trees are assessed. In this study, we grew Cinnamomum camphora seedlings under two CO(2) concentrations (350 micromol/mol and 500 micromol/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 CO(2) on underground and aboveground plant growth, and its dependence on soil moisture. The results indicated that high CO(2) 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 CO(2) 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 CO(2) 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 CO(2) concentration significantly increased the water content in aboveground and underground parts. Then we concluded that high CO(2) concentration favours more tree aboveground biomass growth than underground biomass growth under favorable soil water conditions. And CO(2) enrichment enhanced lateral growth of shoot and vertical growth of root. The responses of plants to elevated CO(2) depend on soil water availability, and plants may benefit more from CO(2) enrichment with sufficient water supply. PMID:16532530

  17. Nonlinear regional warming with increasing CO2 concentrations

    NASA Astrophysics Data System (ADS)

    Good, Peter; Lowe, Jason A.; Andrews, Timothy; Wiltshire, Andrew; Chadwick, Robin; Ridley, Jeff K.; Menary, Matthew B.; Bouttes, Nathaelle; Dufresne, Jean Louis; Gregory, Jonathan M.; Schaller, Nathalie; Shiogama, Hideo

    2015-02-01

    When considering adaptation measures and global climate mitigation goals, stakeholders need regional-scale climate projections, including the range of plausible warming rates. To assist these stakeholders, it is important to understand whether some locations may see disproportionately high or low warming from additional forcing above targets such as 2 K (ref. ). There is a need to narrow uncertainty in this nonlinear warming, which requires understanding how climate changes as forcings increase from medium to high levels. However, quantifying and understanding regional nonlinear processes is challenging. Here we show that regional-scale warming can be strongly superlinear to successive CO2 doublings, using five different climate models. Ensemble-mean warming is superlinear over most land locations. Further, the inter-model spread tends to be amplified at higher forcing levels, as nonlinearities grow--especially when considering changes per kelvin of global warming. Regional nonlinearities in surface warming arise from nonlinearities in global-mean radiative balance, the Atlantic meridional overturning circulation, surface snow/ice cover and evapotranspiration. For robust adaptation and mitigation advice, therefore, potentially avoidable climate change (the difference between business-as-usual and mitigation scenarios) and unavoidable climate change (change under strong mitigation scenarios) may need different analysis methods.

  18. Laser detection of CO2 concentration in human breath at various diseases

    NASA Astrophysics Data System (ADS)

    Ageev, Boris G.; Nikiforova, Olga Y.

    2015-12-01

    Absorption spectra of human breath in 10 μm region were recorded by the use of intracavity laser photo-acoustic gas analyzer based on tunable waveguide CO2 laser. Healthy persons and patients with various diseases were studied. For determination of CO2 concentration in exhalation samples gas analyzer was calibrated by reference gaseous mixture CO2-N2. It was obtained that CO2 concentration values in human breath of healthy persons are greater than that of patients with various diseases.

  19. The OceanFlux Greenhouse Gases methodology for deriving a sea surface climatology of CO2 fugacity in support of air-sea gas flux studies

    NASA Astrophysics Data System (ADS)

    Goddijn-Murphy, L. M.; Woolf, D. K.; Land, P. E.; Shutler, J. D.; Donlon, C.

    2015-07-01

    Climatologies, or long-term averages, of essential climate variables are useful for evaluating models and providing a baseline for studying anomalies. The Surface Ocean CO2 Atlas (SOCAT) has made millions of global underway sea surface measurements of CO2 publicly available, all in a uniform format and presented as fugacity, fCO2. As fCO2 is highly sensitive to temperature, the measurements are only valid for the instantaneous sea surface temperature (SST) that is measured concurrently with the in-water CO2 measurement. To create a climatology of fCO2 data suitable for calculating air-sea CO2 fluxes, it is therefore desirable to calculate fCO2 valid for a more consistent and averaged SST. This paper presents the OceanFlux Greenhouse Gases methodology for creating such a climatology. We recomputed SOCAT's fCO2 values for their respective measurement month and year using monthly composite SST data on a 1° × 1° grid from satellite Earth observation and then extrapolated the resulting fCO2 values to reference year 2010. The data were then spatially interpolated onto a 1° × 1° grid of the global oceans to produce 12 monthly fCO2 distributions for 2010, including the prediction errors of fCO2 produced by the spatial interpolation technique. The partial pressure of CO2 (pCO2) is also provided for those who prefer to use pCO2. The CO2 concentration difference between ocean and atmosphere is the thermodynamic driving force of the air-sea CO2 flux, and hence the presented fCO2 distributions can be used in air-sea gas flux calculations together with climatologies of other climate variables.

  20. Direct electrolytic dissolution of silicate minerals for air CO2 mitigation and carbon-negative H2 production

    PubMed Central

    Rau, Greg H.; Carroll, Susan A.; Bourcier, William L.; Singleton, Michael J.; Smith, Megan M.; Aines, Roger D.

    2013-01-01

    We experimentally demonstrate the direct coupling of silicate mineral dissolution with saline water electrolysis and H2 production to effect significant air CO2 absorption, chemical conversion, and storage in solution. In particular, we observed as much as a 105-fold increase in OH− concentration (pH increase of up to 5.3 units) relative to experimental controls following the electrolysis of 0.25 M Na2SO4 solutions when the anode was encased in powdered silicate mineral, either wollastonite or an ultramafic mineral. After electrolysis, full equilibration of the alkalized solution with air led to a significant pH reduction and as much as a 45-fold increase in dissolved inorganic carbon concentration. This demonstrated significant spontaneous air CO2 capture, chemical conversion, and storage as a bicarbonate, predominantly as NaHCO3. The excess OH− initially formed in these experiments apparently resulted via neutralization of the anolyte acid, H2SO4, by reaction with the base mineral silicate at the anode, producing mineral sulfate and silica. This allowed the NaOH, normally generated at the cathode, to go unneutralized and to accumulate in the bulk electrolyte, ultimately reacting with atmospheric CO2 to form dissolved bicarbonate. Using nongrid or nonpeak renewable electricity, optimized systems at large scale might allow relatively high-capacity, energy-efficient (<300 kJ/mol of CO2 captured), and inexpensive (<$100 per tonne of CO2 mitigated) removal of excess air CO2 with production of carbon-negative H2. Furthermore, when added to the ocean, the produced hydroxide and/or (bi)carbonate could be useful in reducing sea-to-air CO2 emissions and in neutralizing or offsetting the effects of ongoing ocean acidification. PMID:23729814

  1. Direct electrolytic dissolution of silicate minerals for air CO2 mitigation and carbon-negative H2 production.

    PubMed

    Rau, Greg H; Carroll, Susan A; Bourcier, William L; Singleton, Michael J; Smith, Megan M; Aines, Roger D

    2013-06-18

    We experimentally demonstrate the direct coupling of silicate mineral dissolution with saline water electrolysis and H2 production to effect significant air CO2 absorption, chemical conversion, and storage in solution. In particular, we observed as much as a 10(5)-fold increase in OH(-) concentration (pH increase of up to 5.3 units) relative to experimental controls following the electrolysis of 0.25 M Na2SO4 solutions when the anode was encased in powdered silicate mineral, either wollastonite or an ultramafic mineral. After electrolysis, full equilibration of the alkalized solution with air led to a significant pH reduction and as much as a 45-fold increase in dissolved inorganic carbon concentration. This demonstrated significant spontaneous air CO2 capture, chemical conversion, and storage as a bicarbonate, predominantly as NaHCO3. The excess OH(-) initially formed in these experiments apparently resulted via neutralization of the anolyte acid, H2SO4, by reaction with the base mineral silicate at the anode, producing mineral sulfate and silica. This allowed the NaOH, normally generated at the cathode, to go unneutralized and to accumulate in the bulk electrolyte, ultimately reacting with atmospheric CO2 to form dissolved bicarbonate. Using nongrid or nonpeak renewable electricity, optimized systems at large scale might allow relatively high-capacity, energy-efficient (<300 kJ/mol of CO2 captured), and inexpensive (<$100 per tonne of CO2 mitigated) removal of excess air CO2 with production of carbon-negative H2. Furthermore, when added to the ocean, the produced hydroxide and/or (bi)carbonate could be useful in reducing sea-to-air CO2 emissions and in neutralizing or offsetting the effects of ongoing ocean acidification. PMID:23729814

  2. Impacts of potential CO2-reduction policies on air quality in the United States.

    PubMed

    Trail, Marcus A; Tsimpidi, Alexandra P; Liu, Peng; Tsigaridis, Kostas; Hu, Yongtao; Rudokas, Jason R; Miller, Paul J; Nenes, Athanasios; Russell, Armistead G

    2015-04-21

    Impacts of emissions changes from four potential U.S. CO2 emission reduction policies on 2050 air quality are analyzed using the community multiscale air quality model (CMAQ). Future meteorology was downscaled from the Goddard Institute for Space Studies (GISS) ModelE General Circulation Model (GCM) to the regional scale using the Weather Research Forecasting (WRF) model. We use emissions growth factors from the EPAUS9r MARKAL model to project emissions inventories for two climate tax scenarios, a combined transportation and energy scenario, a biomass energy scenario and a reference case. Implementation of a relatively aggressive carbon tax leads to improved PM2.5 air quality compared to the reference case as incentives increase for facilities to install flue-gas desulfurization (FGD) and carbon capture and sequestration (CCS) technologies. However, less capital is available to install NOX reduction technologies, resulting in an O3 increase. A policy aimed at reducing CO2 from the transportation sector and electricity production sectors leads to reduced emissions of mobile source NOX, thus reducing O3. Over most of the U.S., this scenario leads to reduced PM2.5 concentrations. However, increased primary PM2.5 emissions associated with fuel switching in the residential and industrial sectors leads to increased organic matter (OM) and PM2.5 in some cities. PMID:25811418

  3. Sea-air CO2 exchange in the western Arctic coastal ocean

    NASA Astrophysics Data System (ADS)

    Evans, Wiley; Mathis, Jeremy T.; Cross, Jessica N.; Bates, Nicholas R.; Frey, Karen E.; Else, Brent G. T.; Papkyriakou, Tim N.; DeGrandpre, Mike D.; Islam, Fakhrul; Cai, Wei-Jun; Chen, Baoshan; Yamamoto-Kawai, Michiyo; Carmack, Eddy; Williams, William. J.; Takahashi, Taro

    2015-08-01

    The biogeochemical seascape of the western Arctic coastal ocean is in rapid transition. Changes in sea ice cover will be accompanied by alterations in sea-air carbon dioxide (CO2) exchange, of which the latter has been difficult to constrain owing to sparse temporal and spatial data sets. Previous assessments of sea-air CO2 flux have targeted specific subregional areas of the western Arctic coastal ocean. Here a holistic approach is taken to determine the net sea-air CO2 flux over this broad region. We compiled and analyzed an extensive data set of nearly 600,000 surface seawater CO2 partial pressure (pCO2) measurements spanning 2003 through 2014. Using space-time colocated, reconstructed atmospheric pCO2 values coupled with the seawater pCO2 data set, monthly climatologies of sea-air pCO2 differences (ΔpCO2) were created on a 0.2° latitude × 0.5° longitude grid. Sea-air CO2 fluxes were computed using the ΔpCO2 grid and gas transfer rates calculated from climatology of wind speed second moments. Fluxes were calculated with and without the presence of sea ice, treating sea ice as an imperfect barrier to gas exchange. This allowed for carbon uptake by the western Arctic coastal ocean to be assessed under existing and reduced sea ice cover conditions, in which carbon uptake increased 30% over the current 10.9 ± 5.7 Tg C (1 Tg = 1012 g) yr-1 of sea ice-adjusted exchange in the region. This assessment extends beyond previous subregional estimates in the region in an all-inclusive manner and points to key unresolved aspects that must be targeted by future research.

  4. Modeling CO2 air dispersion from gas driven lake eruptions

    NASA Astrophysics Data System (ADS)

    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

  5. Drought × CO2 interactions in trees: a test of the low-intercellular CO2 concentration (Ci ) mechanism.

    PubMed

    Kelly, Jeff W G; Duursma, Remko A; Atwell, Brian J; Tissue, David T; Medlyn, Belinda E

    2016-03-01

    Models of tree responses to climate typically project that elevated atmospheric CO2 concentration (eCa ) will reduce drought impacts on forests. We tested one of the mechanisms underlying this interaction, the 'low Ci effect', in which stomatal closure in drought conditions reduces the intercellular CO2 concentration (Ci ), resulting in a larger relative enhancement of photosynthesis with eCa , and, consequently, a larger relative biomass response. We grew two Eucalyptus species of contrasting drought tolerance at ambient and elevated Ca for 6-9 months in large pots maintained at 50% (drought) and 100% field capacity. Droughted plants did not have significantly lower Ci than well-watered plants, which we attributed to long-term changes in leaf area. Hence, there should not have been an interaction between eCa and water availability on biomass, and we did not detect one. The xeric species did have higher Ci than the mesic species, indicating lower water-use efficiency, but both species exhibited similar responses of photosynthesis and biomass to eCa , owing to compensatory differences in the photosynthetic response to Ci . Our results demonstrate that long-term acclimation to drought, and coordination among species traits may be important for predicting plant responses to eCa under low water availability. PMID:26526873

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Suppression of Ripening-Associated Gene Expression in Tomato Fruits Subjected to a High CO2 Concentration.

    PubMed Central

    Rothan, C.; Duret, S.; Chevalier, C.; Raymond, P.

    1997-01-01

    High concentrations of CO2 block or delay the ripening of fruits. In this study we investigated the effects of high CO2 on ripening and on the expression of stress- and ripening-inducible genes in cherry tomato (Lycopersicon esculentum Mill.) fruit. Mature-green tomato fruits were submitted to a high CO2 concentration (20%) for 3 d and then transferred to air. These conditions effectively inhibited ripening-associated color changes and ethylene production, and reduced the protein content. No clear-cut effect was observed on the expression of two proteolysis-related genes, encoding polyubiquitin and ubiquitin-conjugating enzyme E2, respectively. Exposure of fruit to high CO2 also resulted in the strong induction of two genes encoding stress-related proteins: a ripening-regulated heat-shock protein and glutamate decarboxylase. Induction of these two genes indicated that high CO2 had a stress effect, most likely through cytosolic acidification. In addition, high CO2 blocked the accumulation of mRNAs for genes involved in the main ripening-related changes: ethylene synthesis (1-aminocyclopropane-1-carboxylic acid synthase and 1-aminocyclopropane-1-carboxylic acid oxidase), color (phytoene synthase), firmness (polygalacturonase), and sugar accumulation (acid invertase). The expression of ripening-specific genes was affected by CO2 regardless of whether their induction was ethylene- or development-dependent. It is proposed that the inhibition of tomato fruit ripening by high CO2 is due, in part, to the suppression of the expression of ripening-associated genes, which is probably related to the stress effect exerted by high CO2. PMID:12223703

  8. Growth Kinetics, Carbohydrate, and Leaf Phosphate Content of Clover (Trifolium subterraneum L.) after Transfer to a High CO2 Atmosphere or to High Light and Ambient Air 1

    PubMed Central

    Morin, Francoise; André, Marcel; Betsche, Thomas

    1992-01-01

    Intact air-grown (photosynthetic photon flux density, 400 microeinsteins per square meter per second) clover plants (Trifolium subterraneum L.) were transfered to high CO2 (4000 microliters CO2 per liter; photosynthetic photon flux density, 400 microeinsteins per square meter per second) or to high light (340 microliters CO2 per liter; photosynthetic photon flux density, 800 microeinsteins per square meter per second) to similarly stimulate photosynthetic net CO2 uptake. The daily increment of net CO2 uptake declined transiently in high CO2, but not in high light, below the values in air/standard light. After about 3 days in high CO2, the daily increment of net CO2 uptake increased but did not reach the high light values. Nightly CO2 release increased immediately in high light, whereas there was a 3-day lag phase in high CO2. During this time, starch accumulated to a high level, and leaf deterioration was observed only in high CO2. After 12 days, starch was two- to threefold higher in high CO2 than in high light, whereas sucrose was similar. Leaf carbohydrates were determined during the first and fourth day in high CO2. Starch increased rapidly throughout the day. Early in the day, sucrose was low and similar in high CO2 and ambient air (same light). Later, sucrose increased considerably in high CO2. The findings that (a) much more photosynthetic carbon was partitioned into the leaf starch pool in high CO2 than in high light, although net CO2 uptake was similar, and that (b) rapid starch formation occurred in high CO2 even when leaf sucrose was only slightly elevated suggest that low sink capacity was not the main constraint in high CO2. It is proposed that carbon partitioning between starch (chloroplast) and sucrose (cytosol) was perturbed by high CO2 because of the lack of photorespiration. Total phosphate pools were determined in leaves. Concentrations based on fresh weight of orthophosphate, soluble esterified phosphate, and total phosphate markedly declined

  9. Communication: The influence of CO2 poisoning on overvoltages and discharge capacity in non-aqueous Li-Air batteries

    NASA Astrophysics Data System (ADS)

    Mekonnen, Yedilfana S.; Knudsen, Kristian B.; Mýrdal, Jon S. G.; Younesi, Reza; Højberg, Jonathan; Hjelm, Johan; Norby, Poul; Vegge, Tejs

    2014-03-01

    The effects of Li2CO3 like species originating from reactions between CO2 and Li2O2 at the cathode of non-aqueous Li-air batteries were studied by density functional theory (DFT) and galvanostatic charge-discharge measurements. Adsorption energies of CO2 at various nucleation sites on a stepped ({1bar 100}) Li2O2 surface were determined and even a low concentration of CO2 effectively blocks the step nucleation site and alters the Li2O2 shape due to Li2CO3 formation. Nudged elastic band calculations show that once CO2 is adsorbed on a step valley site, it is effectively unable to diffuse and impacts the Li2O2 growth mechanism, capacity, and overvoltages. The charging processes are strongly influenced by CO2 contamination, and exhibit increased overvoltages and increased capacity, as a result of poisoning of nucleation sites: this effect is predicted from DFT calculations and observed experimentally already at 1% CO2. Large capacity losses and overvoltages are seen at higher CO2 concentrations.

  10. Technology advancement of the electrochemical CO2 concentrating process

    NASA Technical Reports Server (NTRS)

    Schubert, F. H.; Heppner, D. B.; Hallick, T. M.; Woods, R. R.

    1979-01-01

    Two multicell, liquid-cooled, advanced electrochemical depolarized carbon dioxide concentrator modules were fabricated. The cells utilized advanced, lightweight, plated anode current collectors, internal liquid cooling and lightweight cell frames. Both were designed to meet the carbon dioxide removal requirements of one-person, i.e., 1.0 kg/d (2.2 lb/d).

  11. Technology advancement of the electrochemical CO2 concentrating process

    NASA Technical Reports Server (NTRS)

    Schubert, F. H.; Woods, R. R.; Hallick, T. M.; Heppner, D. B.

    1977-01-01

    A five-cell, liquid-cooled advanced electrochemical depolarized carbon dioxide concentrator module was fabricated. The cells utilized the advanced, lightweight, plated anode current collector concept and internal liquid-cooling. The five cell module was designed to meet the carbon dioxide removal requirements of one man and was assembled using plexiglass endplates. This one-man module was tested as part of an integrated oxygen generation and recovery subsystem.

  12. Nocturnal intermittency in surface CO2 concentrations in sub-Saharan Africa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Data obtained over four adjacent fields of differing management practices in Zimbabwe illustrate the role of atmospheric intermittency as a mechanism for transferring CO2 between the surface and the atmosphere above. At night, limited atmospheric mixing permits CO2 concentrations to increase to leve...

  13. CO2 enrichment increases element concentrations in grass mixtures by changing species abundances

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The continuing rise in atmospheric carbon dioxide (CO2) concentration may increase plant growth relatively more than the uptake of soil-derived chemical elements that are essential for herbivores. Rising CO2 also may alter the nutritional quality of forage or fodder derived from multi-species veget...

  14. Late miocene atmospheric CO(2) concentrations and the expansion of C(4) grasses

    PubMed

    Pagani; Freeman; Arthur

    1999-08-01

    The global expansion of C(4) grasslands in the late Miocene has been attributed to a large-scale decrease in atmospheric carbon dioxide (CO(2)) concentrations. This triggering mechanism is controversial, in part because of a lack of direct evidence for change in the partial pressure of CO(2) (pCO(2)) and because other factors are also important determinants in controlling plant-type distributions. Alkenone-based pCO(2) estimates for the late Miocene indicate that pCO(2) increased from 14 to 9 million years ago and stabilized at preindustrial values by 9 million years ago. The estimates presented here provide no evidence for major changes in pCO(2) during the late Miocene. Thus, C(4) plant expansion was likely driven by additional factors, possibly a tectonically related episode of enhanced low-latitude aridity or changes in seasonal precipitation patterns on a global scale (or both). PMID:10436153

  15. On Using CO2 Concentration Measurements at Mountain top and Valley Locations in Regional Flux Studies.

    NASA Astrophysics Data System (ADS)

    de Wekker, S. F.; Song, G.; Stephens, B. B.

    2007-12-01

    Data from the Regional Atmospheric Continuous CO2 Network in the Rocky Mountains (Rocky RACCOON) are used to investigate atmospheric controls on temporal and spatial variability of CO2 in mountainous terrain and the usefulness of mountain top and valley measurement for the estimation of regional CO2 fluxes. Rocky RACCOON consists of four sites installed in fall of 2005 and spring of 2006: Niwot Ridge, near Ward, Colorado; Storm Peak Laboratory near Steamboat Springs, Colorado; Fraser Experimental Forest, near Fraser Colorado; and Hidden Peak, near Snowbird, Utah. The network uses the NCAR-developed Autonomous Inexpensive Robust CO2 Analyzer. These units measure CO2 concentrations at three levels on a tower, producing individual measurements every 2.5 minutes precise to 0.1 ppm CO2 and closely tied to the WMO CO2 scale. Three of the sites are located on a mountain top while one site is located in a valley. Initial analyses show interesting relationships between CO2 concentration and atmospheric parameters, such as wind speed and direction, temperature, and incoming solar radiation. The nature of these relationships is further investigated with an atmospheric mesoscale model. Idealized and realistic simulations are able to capture the observed behavior of spatial and temporal CO2 variability and reveal the responsible physical processes. The implications of the results and the value of the measurements for providing information on local to regional scale respiration and photosynthesis rates in the Rockies are discussed.

  16. Effects of Elevated CO2 Concentration on Photosynthesis and Respiration of Populus Deltodies

    NASA Technical Reports Server (NTRS)

    Anderson, Angela M.

    1998-01-01

    To determine how increased atmospheric CO2 will affect the physiology of cottonwood trees, cuttings of the cloned Populus deltodies [cottonwood] were grown in open-top chambers containing ambient or elevated CO2 concentration. The control treatment was maintained at ambient Biosphere 2 atmospheric CO2 (c. 450 +/- 50 micro l/l), and elevated CO2 treatment was maintained at approximately double ambient Biosphere 2 atmospheric CO2 (c. 1000 +/- 50 micro l/l). The effects of elevated CO2 on leaf photosynthesis, and stomatal conductance were measured. The cottonwoods exposed to CO2 enrichment showed no significant indication of photosynthetic down-regulation. There was no significant difference in the maximum assimilation rate between the treatment and the control (P less than 0.24). The CO2 enriched treatment showed a decreased stomatal conductance of 15% (P less than 0.03). The elevated CO2 concentrated atmosphere had an effect on the respiration rates of the plants; the compensation point of the treatment was on average 13% higher than the control (P less than 0.01).

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

    PubMed

    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. PMID:23771683

  18. Seasonal variations of seawater pCO2 and sea-air CO2 fluxes in a fringing coral reef, northern South China Sea

    NASA Astrophysics Data System (ADS)

    Yan, Hongqiang; Yu, Kefu; Shi, Qi; Tan, Yehui; Liu, Guohui; Zhao, Meixia; Li, Shu; Chen, Tianran; Wang, Yinghui

    2016-01-01

    Evidence based on four field surveys conducted between July 2009 and April 2011 indicates that both sea surface partial pressures of CO2 (pCO2) and sea-air CO2 fluxes at Luhuitou fringing reef in Sanya, Hainan Island, northern South China Sea (SCS) are subject to significant seasonal variations. The diurnal variation of seawater pCO2 ranges from 264 to 579 μatm in summer, which is much larger than that in autumn (152-335 μatm), in winter (84-260 μatm), and in spring (114-228 μatm). The sea-air CO2 flux in summer (˜9.6 mmol CO2 m-2 d-1) is also larger than that in other seasons (i.e.,˜3 mmol CO2 m-2 d-1 in spring, ˜3.5 mmol CO2 m-2 d-1 in autumn, and ˜2.7 mmol CO2 m-2 d-1 in winter). The atmospheric pCO2 in this reef shows small diurnal and seasonal variations. The integration of the time-series pCO2 data shows that the reef area is a weak source of atmospheric CO2 at ˜0.54 mol CO2 m-2 yr-1. Further analyses indicate that the seasonal variations of the surface seawater pCO2 in Luhuitou fringing reef are mainly affected by seasonally-dependent biological metabolic processes (organic processe and inorganic process), and that the organic process play a more important role than the inorganic process. Seasonal sea surface temperature (SST) variations and hydrodynamic processes may also have some influence on seawater pCO2 variation.

  19. Rice grain yield and quality responses to free-air CO2 enrichment combined with soil and water warming.

    PubMed

    Usui, Yasuhiro; Sakai, Hidemitsu; Tokida, Takeshi; Nakamura, Hirofumi; Nakagawa, Hiroshi; Hasegawa, Toshihiro

    2016-03-01

    Rising air temperatures are projected to reduce rice yield and quality, whereas increasing atmospheric CO2 concentrations ([CO2 ]) can increase grain yield. For irrigated rice, ponded water is an important temperature environment, but few open-field evaluations are available on the combined effects of temperature and [CO2 ], which limits our ability to predict future rice production. We conducted free-air CO2 enrichment and soil and water warming experiments, for three growing seasons to determine the yield and quality response to elevated [CO2 ] (+200 μmol mol(-1) , E-[CO2 ]) and soil and water temperatures (+2 °C, E-T). E-[CO2 ] significantly increased biomass and grain yield by approximately 14% averaged over 3 years, mainly because of increased panicle and spikelet density. E-T significantly increased biomass but had no significant effect on the grain yield. E-T decreased days from transplanting to heading by approximately 1%, but days to the maximum tiller number (MTN) stage were reduced by approximately 8%, which limited the panicle density and therefore sink capacity. On the other hand, E-[CO2 ] increased days to the MTN stage by approximately 4%, leading to a greater number of tillers. Grain appearance quality was decreased by both treatments, but E-[CO2 ] showed a much larger effect than did E-T. The significant decrease in undamaged grains (UDG) by E-[CO2 ] was mainly the result of an increased percentage of white-base grains (WBSG), which were negatively correlated with grain protein content. A significant decrease in grain protein content by E-[CO2 ] accounted in part for the increased WBSG. The dependence of WBSG on grain protein content, however, was different among years; the slope and intercept of the relationship were positively correlated with a heat dose above 26 °C. Year-to-year variation in the response of grain appearance quality demonstrated that E-[CO2 ] and rising air temperatures synergistically reduce grain appearance quality of

  20. Preliminary evaluation of a membrane-based system for removing CO2 from air

    NASA Technical Reports Server (NTRS)

    Mccray, Scott B.; Wytcherley, Randi W.; Friesen, Dwayne T.; Ray, Rod J.

    1990-01-01

    Processes to remove and/or recover CO2 from air are essential to the long-term success of the U.S. space program. The results of a preliminary investigation of the use of a novel membrane-based system for removal of CO2 from air are presented. Features of this technology that make it attractive include the following: (1) it is lightweight; (2) it requires no consumables or expendables; (3) it is relatively simple; and (4) it does not rely directly on other subsystems. Preliminary designs of systems for removing CO2 from spacecraft cabin atmospheres and from the extravehicular mobility unit are presented.

  1. Land plants equilibrate O2 and CO2 concentrations in the atmosphere.

    PubMed

    Igamberdiev, Abir U; Lea, Peter J

    2006-02-01

    The role of land plants in establishing our present day atmosphere is analysed. Before the evolution of land plants, photosynthesis by marine and fresh water organisms was not intensive enough to deplete CO(2) from the atmosphere, the concentration of which was more than the order of magnitude higher than present. With the appearance of land plants, the exudation of organic acids by roots, following respiratory and photorespiratory metabolism, led to phosphate weathering from rocks thus increasing aquatic productivity. Weathering also replaced silicates by carbonates, thus decreasing the atmospheric CO(2) concentration. As a result of both intensive photosynthesis and weathering, CO(2 )was depleted from the atmosphere down to low values approaching the compensation point of land plants. During the same time period, the atmospheric O(2) concentration increased to maximum levels about 300 million years ago (Permo-Carboniferous boundary), establishing an O(2)/CO(2) ratio above 1000. At this point, land plant productivity and weathering strongly decreased, exerting negative feedback on aquatic productivity. Increased CO(2) concentrations were triggered by asteroid impacts and volcanic activity and in the Mesozoic era could be related to the gymnosperm flora with lower metabolic and weathering rates. A high O(2)/CO(2) ratio is metabolically linked to the formation of citrate and oxalate, the main factors causing weathering, and to the production of reactive oxygen species, which triggered mutations and stimulated the evolution of land plants. The development of angiosperms resulted in a decrease in CO(2) concentration during the Cenozoic era, which finally led to the glacial-interglacial oscillations in the Pleistocene epoch. Photorespiration, the rate of which is directly related to the O(2)/CO(2) ratio, due to the dual function of Rubisco, may be an important mechanism in maintaining the limits of O(2) and CO(2) concentrations by restricting land plant productivity

  2. [Effects of high concentration CO2 on lily growth and its two allelochemicals].

    PubMed

    Wei, Shenglin

    2005-01-01

    Under greenhouse condition, this paper studied the effects of different concentrations CO2 to the growth of oriental yellow poly-bud cut lily and to the two allelochemicals in lily leaves. The results showed that the optimum CO2 concentration for Pn was 600 micromol x mol(-1). There was less impact on photosynthesis when continually supplying 600-1000 micromol x mol(-1) CO2 for 45 days, probably due to the photosynthesis adaptability of new bulblets. 600 micromol x mol(-1) CO2 could increase the stem height about 0.57 grades, and also had a positive effect on the growth of color bud. 600 micromol x mol(-1) and 800 micromol x mol(-1) CO2 could markedly increase the contents of polyphenols and flavonoids in lily leaves, and there was no plant leaves withered, because the appropriate concentrations CO2 was beneficial to the Pn and to the formation and transformation of carbohydrates and allelochemicals, which increased the premunition of the plant. The contents of polyphenols and flavonoids in lily leaves reached the maximum when the concentration of CO2 was 600 micromol x mol(-1). PMID:15852968

  3. The minimal CO2-concentrating mechanism of Prochlorococcus spp. MED4 is effective and efficient.

    PubMed

    Hopkinson, Brian M; Young, Jodi N; Tansik, Anna L; Binder, Brian J

    2014-12-01

    As an oligotrophic specialist, Prochlorococcus spp. has streamlined its genome and metabolism including the CO2-concentrating mechanism (CCM), which serves to elevate the CO2 concentration around Rubisco. The genomes of Prochlorococcus spp. indicate that they have a simple CCM composed of one or two HCO3(-) pumps and a carboxysome, but its functionality has not been examined. Here, we show that the CCM of Prochlorococcus spp. is effective and efficient, transporting only two molecules of HCO3(-) per molecule of CO2 fixed. A mechanistic, numerical model with a structure based on the CCM components present in the genome is able to match data on photosynthesis, CO2 efflux, and the intracellular inorganic carbon pool. The model requires the carboxysome shell to be a major barrier to CO2 efflux and shows that excess Rubisco capacity is critical to attaining a high-affinity CCM without CO2 recovery mechanisms or high-affinity HCO3(-) transporters. No differences in CCM physiology or gene expression were observed when Prochlorococcus spp. was fully acclimated to high-CO2 (1,000 µL L(-1)) or low-CO2 (150 µL L(-1)) conditions. Prochlorococcus spp. CCM components in the Global Ocean Survey metagenomes were very similar to those in the genomes of cultivated strains, indicating that the CCM in environmental populations is similar to that of cultured representatives. PMID:25315602

  4. [Variation of CO2 concentration in solar greenhouse in Northern China].

    PubMed

    Wei, Min; Xing, Yuxian; Wang, Xiufeng; Ma, Hong

    2003-03-01

    The variation of CO2 concentration in winter-spring cultivated solar greenhouse in northern China was studied. The diurnal change of CO2 concentration showed an irregular 'U' shape in most case, the maximum value appeared prior to unveiling straw mat in the morning, and the minimum between 12:00 and 14:00 PM. Sometimes, an irregular 'W' shape curve with two valleys was also observed, with the first one appeared prior to the ventilation at noon, and the second occurred between 15:00-16:30 PM. During the period of winter-spring cultivation, the daily maximum concentration of CO2 in solar greenhouse decreased gradually, while the daily minimum concentration and daytime average concentration dropped first, then went up. At the same time, the time of CO2 depletion lasted longer and longer. In December, CO2 depletion happened 2.1-3.1 hours after morning unveiling. In the next March, however, it moved up to 0.6-1.1 hours after unveiling in the morning. At daytime, both during and after ventilation, solar greenhouse often showed CO2 depletion. The period of CO2 depletion extended from 4-5.8 hours per day in December to 8-8.5 hours per day in March of next year. The spacial distribution of CO2 concentrations within the greenhouse showed that in the morning and in the evening, the order was the front > the middle > the back, and the ground > the canopy > the upper, and at midday, the order was the front < the middle < the back, and the ground > the upper > the canopy. Photon flux density was the most important environmental factor affecting CO2 concentration in greenhouse. Ventilation did not avoided CO2 depletion. Canopy photosynthetic rate and soil respiratory rate were measured at different growth stages of tomato. At seedling stage, CO2 concentration in greenhouse was higher than that outside, due to the vigorous soil respiration and lower canopy photosynthetic rate. But at fruiting stage, severe CO2 depletion occurred because of stronger canopy photosynthesis and weak

  5. A 2-Micron Pulsed Integrated Path Differential Absorption Lidar Development For Atmospheric CO2 Concentration Measurements

    NASA Technical Reports Server (NTRS)

    Yu, Jirong; Petros, Mulugeta; Reithmaier, Karl; Bai, Yingxin; Trieu, Bo C.; Refaat, Tamer F.; Kavaya, Michael J.; Singh, Upendra N.

    2012-01-01

    A 2-micron pulsed, Integrated Path Differential Absorption (IPDA) lidar instrument for ground and airborne atmospheric CO2 concentration measurements via direct detection method is being developed at NASA Langley Research Center. This instrument will provide an alternate approach to measure atmospheric CO2 concentrations with significant advantages. A high energy pulsed approach provides high-precision measurement capability by having high signal-to-noise level and unambiguously eliminates the contamination from aerosols and clouds that can bias the IPDA measurement.

  6. Regulation of hormonal responses of sweet pepper as affected by salinity and elevated CO2 concentration.

    PubMed

    Piñero, María Carmen; Houdusse, Fabrice; Garcia-Mina, Jose M; Garnica, María; Del Amor, Francisco M

    2014-08-01

    This study examines the extent to which the predicted CO2 -protective effects on the inhibition of growth, impairment of photosynthesis and nutrient imbalance caused by saline stress are mediated by an effective adaptation of the endogenous plant hormonal balance. Therefore, sweet pepper plants (Capsicum annuum, cv. Ciclón) were grown at ambient or elevated [CO2] (400 or 800 µmol mol(-1)) with a nutrient solution containing 0 or 80 mM NaCl. The results show that, under saline conditions, elevated [CO2] increased plant dry weight, leaf area, leaf relative water content and net photosynthesis compared with ambient [CO2], whilst the maximum potential quantum efficiency of photosystem II was not modified. In salt-stressed plants, elevated [CO2 ] increased leaf NO3(-) concentration and reduced Cl(-) concentration. Salinity stress induced ABA accumulation in the leaves but it was reduced in the roots at high [CO2], being correlated with the stomatal response. Under non-stressed conditions, IAA was dramatically reduced in the roots when high [CO2] was applied, which resulted in greater root DW and root respiration. Additionally, the observed high CK concentration in the roots (especially tZR) could prevent downregulation of photosynthesis at high [CO2], as the N level in the leaves was increased compared with the ambient [CO2], under salt-stress conditions. These results demonstrate that the hormonal balance was altered by the [CO2], which resulted in significant changes at the growth, gas exchange and nutritional levels. PMID:24152078

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

    NASA Astrophysics Data System (ADS)

    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.

  8. Validation of AIRS Retrievals of CO2 via Comparison to In Situ Measurements

    NASA Technical Reports Server (NTRS)

    Olsen, Edward T.; Chahine, Moustafa T.; Chen, Luke L.; Jiang, Xun; Pagano, Thomas S.; Yung, Yuk L.

    2008-01-01

    Topics include AIRS on Aqua, 2002-present with discussion about continued operation to 2011 and beyond and background, including spectrum, weighting functions, and initialization; comparison with aircraft and FTIR measurements in Masueda (CONTRAIL) JAL flask measurements, Park Falls, WI FTIR, Bremen, GDF, and Spitsbergen, Norway; AIRS retrievals over addition FTIR sites in Darwin, AU and Lauder, NZ; and mid-tropospheric carbon dioxide weather and contribution from major surface sources. Slide titles include typical AIRS infrared spectrum, AIRS sensitivity for retrieving CO2 profiles, independence of CO2 solution with respect to the initial guess, available in situ measurements for validation and comparison, comparison of collocated V1.5x AIRS CO2 (N_coll greater than or equal to 9) with INTEX-NA and SPURT;

  9. Inference of super-resolution ocean pCO2 and air-sea CO2 fluxes from non-linear and multiscale processing methods

    NASA Astrophysics Data System (ADS)

    Hernández-Carrasco, Ismael; Sudre, Joel; Garçon, Veronique; Yahia, Hussein; Dewitte, Boris; Garbe, Christoph; Illig, Séréna; Montes, Ivonne; Dadou, Isabelle; Paulmier, Aurélien; Butz, André

    2014-05-01

    In recent years the role of submesoscale activity is emerging as being more and more important to understand global ocean properties, for instance, for accurately estimating the sources and sinks of Greenhouse Gases (GHGs) at the air-sea interface. The scarcity of oceanographic cruises and the lack of available satellite products for GHG concentrations at high resolution prevent from obtaining a global assessment of their spatial variability at small scales. In this work we develop a novel method to reconstruct maps of CO2 fluxes at super resolution (4km) using SST and ocean colour data at this resolution, and CarbonTracker CO2 fluxes data at low resolution (110 km). The responsible process for propagating the information between scales is related to cascading properties and multiscale organization, typical of fully developed turbulence. The methodology, based on the Microcanonical Multifractal Formalism, makes use, from the knowledge of singularity exponents, of the optimal wavelet for the determination of the energy injection mechanism between scales. We perform a validation analysis of the results of our algorithm using pCO2 ocean data from in-situ measurements in the upwelling region off Namibia.

  10. Free-air CO2 enrichment (face): model analysis of gaseous dispersion arrays for studying rising atmospheric CO2 effects on vegetation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Atmospheric carbon dioxide (CO2) has risen from about 280 to 380 micromol/mol since the beginning of the industrial revolution due mainly to burning of fossil fuels. Free-Air CO2 Enrichment (FACE) arrays have been devised with large areas and undisturbed aerial conditions that allow secondary soil o...

  11. Direct measurements of air-sea CO2 exchange over a coral reef

    NASA Astrophysics Data System (ADS)

    McGowan, Hamish A.; MacKellar, Mellissa C.; Gray, Michael A.

    2016-05-01

    Quantification of CO2 exchange with the atmosphere over coral reefs has relied on microscale measurements of pCO2 gradients across the air-sea interfacial boundary; shipboard measurements of air-sea CO2 exchange over adjacent ocean inferred to represent over reef processes or ecosystem productivity modeling. Here we present by way of case study the first direct measurements of air-sea CO2 exchange over a coral reef made using the eddy covariance method. Research was conducted during the summer monsoon over a lagoonal platform reef in the southern Great Barrier Reef, Australia. Results show the reef flat to be a net source of CO2 to the atmosphere of similar magnitude as coastal lakes, while adjacent shallow and deep lagoons were net sinks as was the surrounding ocean. This heterogeneity in CO2 exchange with the atmosphere confirms need for spatially representative direct measurements of CO2 over coral reefs to accurately quantify their role in atmospheric carbon budgets.

  12. Variability of CO2 concentrations and fluxes in and above an urban street canyon

    NASA Astrophysics Data System (ADS)

    Lietzke, Björn; Vogt, Roland

    2013-08-01

    The variability of CO2 concentrations and fluxes in dense urban environments is high due to the inherent heterogeneity of these complex areas and their spatio-temporally variable anthropogenic sources. With a focus on micro- to local-scale CO2-exchange processes, measurements were conducted in a street canyon in the city of Basel, Switzerland in 2010. CO2 fluxes were sampled at the top of the canyon (19 m) and at 39 m while vertical CO2 concentration profiles were measured in the center and at a wall of the canyon. CO2 concentration distributions in the street canyon and exchange processes with the layers above show, apart from expected general diurnal patterns due mixing layer heights, a strong dependence on wind direction relative to the canyon. As a consequence of the resulting corkscrew-like canyon vortex, accumulation of CO2 inside the canyon is modulated with distinct distribution patterns. The evaluation of diurnal traffic data provides good explanations for the vertical and horizontal differences in CO2-distribution inside the canyon. Diurnal flux characteristics at the top of the canyon can almost solely be explained with traffic density expressed by the strong linear dependence. Even the diurnal course of the flux at 39 m shows a remarkable relationship to traffic density for east wind conditions while, for west wind situations, a change toward source areas with lower emissions leads to a reduced flux.

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

    NASA Astrophysics Data System (ADS)

    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

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

    PubMed

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

    2016-05-01

    The global atmospheric CO(2) 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 CO(2) concentrations, an experiment was conducted using the Free Air CO(2) 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 CO(2) on the amylose and protein contents of the grains were analyzed. The results showed that elevated CO(2) 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 CO(2) 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 CO(2) 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 CO(2) concentration increased enzyme activity expression and starch synthesis, affecting the

  15. Tomato–Pseudomonas syringae interactions under elevated CO2 concentration: the role of stomata

    PubMed Central

    Li, Xin; Sun, Zenghui; Shao, Shujun; Zhang, Shuai; Ahammed, Golam Jalal; Zhang, Guanqun; Jiang, Yuping; Zhou, Jie; Xia, Xiaojian; Zhou, Yanhong; Yu, Jingquan; Shi, Kai

    2015-01-01

    Increasing atmospheric CO2 concentrations ([CO2]) in agricultural and natural ecosystems is known to reduce plant stomatal opening, but it is unclear whether these CO2-induced stomatal alterations are associated with foliar pathogen infections. In this study, tomato plants were grown under ambient and elevated [CO2] and inoculated with Pseudomonas syringae pv. tomato strain DC3000, a strain that is virulent on tomato plants. We found that elevated [CO2] enhanced tomato defence against P. syringae. Scanning electron microscopy analysis revealed that stomatal aperture of elevated [CO2] plants was considerably smaller than their ambient counterparts, which affected the behaviour of P. syringae bacteria on the upper surface of epidermal peels. Pharmacological experiments revealed that nitric oxide (NO) played a role in elevated [CO2]-induced stomatal closure. Silencing key genes involved in NO generation and stomatal closing, nitrate reductase (NR) and guard cell slow-type anion channel 1 (SLAC1), blocked elevated [CO2]-induced stomatal closure and resulted in significant increases in P. syringae infection. However, the SLAC1-silenced plants, but not the NR-silenced plants, still had significantly higher defence under elevated [CO2] compared with plants treated with ambient [CO2]. Similar results were obtained when the stomata-limiting factor for P. syringae entry was excluded by syringe infiltration inoculation. These results indicate that elevated [CO2] induces defence against P. syringae in tomato plants, not only by reducing the stomata-mediated entry of P. syringae but also by invoking a stomata-independent pathway to counteract P. syringae. This information is valuable for designing proper strategies against bacterial pathogens under changing agricultural and natural ecosystems. PMID:25336683

  16. Responses of Legume Versus Nonlegume Tropical Tree Seedlings to Elevated CO2 Concentration1[OA

    PubMed Central

    Cernusak, Lucas A.; Winter, Klaus; Martínez, Carlos; Correa, Edwin; Aranda, Jorge; Garcia, Milton; Jaramillo, Carlos; Turner, Benjamin L.

    2011-01-01

    We investigated responses of growth, leaf gas exchange, carbon-isotope discrimination, and whole-plant water-use efficiency (WP) to elevated CO2 concentration ([CO2]) in seedlings of five leguminous and five nonleguminous tropical tree species. Plants were grown at CO2 partial pressures of 40 and 70 Pa. As a group, legumes did not differ from nonlegumes in growth response to elevated [CO2]. The mean ratio of final plant dry mass at elevated to ambient [CO2] (ME/MA) was 1.32 and 1.24 for legumes and nonlegumes, respectively. However, there was large variation in ME/MA among legume species (0.92–2.35), whereas nonlegumes varied much less (1.21–1.29). Variation among legume species in ME/MA was closely correlated with their capacity for nodule formation, as expressed by nodule mass ratio, the dry mass of nodules for a given plant dry mass. WP increased markedly in response to elevated [CO2] in all species. The ratio of intercellular to ambient CO2 partial pressures during photosynthesis remained approximately constant at ambient and elevated [CO2], as did carbon isotope discrimination, suggesting that WP should increase proportionally for a given increase in atmospheric [CO2]. These results suggest that tree legumes with a strong capacity for nodule formation could have a competitive advantage in tropical forests as atmospheric [CO2] rises and that the water-use efficiency of tropical tree species will increase under elevated [CO2]. PMID:21788363

  17. Technical Note: Cost-efficient approaches to measure carbon dioxide (CO2) fluxes and concentrations in terrestrial and aquatic environments using mini loggers

    NASA Astrophysics Data System (ADS)

    Bastviken, D.; Sundgren, I.; Natchimuthu, S.; Reyier, H.; Gålfalk, M.

    2015-06-01

    Fluxes of CO2 are important for our understanding of the global carbon cycle and greenhouse gas balances. Several significant CO2 fluxes in nature may still be unknown as illustrated by recent findings of high CO2 emissions from aquatic environments, previously not recognized in global carbon balances. Therefore, it is important to develop convenient and affordable ways to measure CO2 in many types of environments. At present, direct measurements of CO2 fluxes from soil or water, or CO2 concentrations in surface water, are typically labor intensive or require costly equipment. We here present an approach with measurement units based on small inexpensive CO2 loggers, originally made for indoor air quality monitoring, that were tested and adapted for field use. Measurements of soil-atmosphere and lake-atmosphere fluxes, as well as of spatiotemporal dynamics of water CO2 concentrations (expressed as the equivalent partial pressure, pCO2aq) in lakes and a stream network are provided as examples. Results from all these examples indicate that this approach can provide a cost- and labor-efficient alternative for direct measurements and monitoring of CO2 flux and pCO2aq in terrestrial and aquatic environments.

  18. Technical Note: Cost-efficient approaches to measure carbon dioxide (CO2) fluxes and concentrations in terrestrial and aquatic environments using mini loggers

    NASA Astrophysics Data System (ADS)

    Bastviken, D.; Sundgren, I.; Natchimuthu, S.; Reyier, H.; Gålfalk, M.

    2015-02-01

    Fluxes of CO2 are important for our understanding of the global carbon cycle and greenhouse gas balances. Several significant CO2 fluxes in nature may still be neglected as illustrated by recent findings of high CO2 emissions from aquatic environments, previously not recognized in global carbon balances. Therefore it is important to develop convenient and affordable ways to measure CO2 in many types of environments. At present, direct measurements of CO2 fluxes from soils or waters, or CO2 concentrations in surface water, are typically labour intensive or require costly equipment. We here present an approach with measurement units based on small inexpensive CO2 loggers, originally made for indoor air quality monitoring, that were tested and adapted for field use. Measurements of soil-atmosphere and lake-atmosphere fluxes, as well as of spatio-temporal dynamics of water CO2 concentrations (expressed as the equivalent partial pressure, pCO2aq) in lakes and a stream network are provided as examples. Results from all these examples indicate that this approach can provide a cost- and labor efficient alternative for direct measurements and monitoring of CO2 flux and pCO2aq in terrestrial and aquatic environments.

  19. Monitoring CO2 and CH4 concentrations along an urban-rural transect in London, UK

    NASA Astrophysics Data System (ADS)

    Boon, Alex; Broquet, Gregoire; Clifford, Debbie; Chevallier, Frederic; Butterfield, David

    2013-04-01

    Cities are important sources of carbon dioxide (CO2) and methane (CH4). Anthropogenic CO2 is released in the combustion of fossil fuels for heating, electricity and transport. The major sources of CH4 in city environments are natural gas leakage, landfill sites and transport emissions. Monitoring of urban greenhouse gas concentrations is crucial for cities aiming to reduce emissions through measures such as changes to the transport infrastructure and green planning. We present measurements of CO2 and CH4 concentrations using Cavity Ring-Down Spectroscopy (CRDS) at four sites located in and around London, UK. Two sites were located in the inner city, one in the suburban fringe and the fourth in a rural location close to the city. This study was funded by Astrium Services Ltd as part of a pilot scheme to monitor city-scale GHG emissions and presented a unique opportunity to study changes in greenhouse gas concentrations across an urban to rural 'transect'. The CHIMERE chemistry-transport model is used to estimate CO2 and CH4 concentrations throughout the four month measurement period during the summer of 2012. Comparisons are made between the measured and modelled CO2 and CH4 concentrations and the representativity of the study sites for future urban greenhouse gas monitoring is considered. This study also examines the ability of a variety of measurement and modelling techniques to partition anthropogenic and biogenic CO2 sources.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  2. 13CO2 recovery fraction in expired air of septic patients under mechanical ventilation.

    PubMed

    Auxiliadora-Martins, M; Martins, M A; Coletto, F A; Martins-Filho, O A; Marchini, J S; Basile-Filho, A

    2008-07-01

    The continuous intravenous administration of isotopic bicarbonate (NaH13CO2) has been used for the determination of the retention of the 13CO2 fraction or the 13CO2 recovered in expired air. This determination is important for the calculation of substrate oxidation. The aim of the present study was to evaluate, in critically ill patients with sepsis under mechanical ventilation, the 13CO2 recovery fraction in expired air after continuous intravenous infusion of NaH13CO2 (3.8 micromol/kg diluted in 0.9% saline in ddH2O). A prospective study was conducted on 10 patients with septic shock between the second and fifth day of sepsis evolution (APACHE II, 25.9 +/- 7.4). Initially, baseline CO2 was collected and indirect calorimetry was also performed. A primer of 5 mL NaH13CO2 was administered followed by continuous infusion of 5 mL/h for 6 h. Six CO2 production (VCO2) measurements (30 min each) were made with a portable metabolic cart connected to a respirator and hourly samples of expired air were obtained using a 750-mL gas collecting bag attached to the outlet of the respirator. 13CO2 enrichment in expired air was determined with a mass spectrometer. The patients presented a mean value of VCO2 of 182 +/- 52 mL/min during the steady-state phase. The mean recovery fraction was 0.68 +/- 0.06%, which is less than that reported in the literature (0.82 +/- 0.03%). This suggests that the 13CO2 recovery fraction in septic patients following enteral feeding is incomplete, indicating retention of 13CO2 in the organism. The severity of septic shock in terms of the prognostic index APACHE II and the sepsis score was not associated with the 13CO2 recovery fraction in expired air. PMID:18719737

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

    NASA Astrophysics Data System (ADS)

    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

  4. Spatial and temporal variability of air-sea CO2 exchange of alongshore waters in summer near Barrow, Alaska

    NASA Astrophysics Data System (ADS)

    Ikawa, Hiroki; Oechel, Walter C.

    2014-03-01

    Alongshore water off Barrow, Alaska is a useful area for studying the carbon cycle of the Arctic coastal sea, because the different coastal characteristics extant in the area likely represent much larger regions of the coastal water of the western Arctic Ocean. Especially noteworthy is the inflow shelf water transferred northward by the Arctic Coastal Current into the Chukchi Sea from the North Pacific and turbid water in the Elson Lagoon where a significant amount of coastal erosion has been reported along the extensive coastal line and where a part of the water from the lagoon drains into the Beaufort Sea adjacent to the Chukchi Sea. To investigate spatial and temporal variations of air-sea CO2 flux (CO2 flux) of the alongshore water, partial pressure of CO2 of surface seawater (pCO2sw) was measured in summer, 2007 and 2008, and CO2 flux was directly measured by eddy covariance at a fixed point for the Beaufort Sea in summer 2008. Measured pCO2sw in the Chukchi Sea side was the lowest in the beginning of the measurement season and increased later in the season both in 2007 and 2008. The average CO2 flux estimated based on pCO2sw in the Chukchi Sea side was -0.10 μmol m-2 s-1 (±0.1 s.d.) using the sign convention of positive fluxes into the atmosphere from the ocean. pCO2sw in the Beaufort Sea and the Elson Lagoon was relatively higher in early summer and decreased in the middle of the summer. The overall average CO2 flux was -0.07 μmol m-2 s-1 (±0.1 s.d.) for the Beaufort Sea side and -0.03 μmol m-2 s-1 (±0.07 s.d.) for the Elson Lagoon respectively, indicating a sink of CO2 despite high carbon inflows from the terrestrial margin into the Elson Lagoon. A strong sink of CO2 was often observed from the Beaufort Sea by eddy covariance in the middle of the summer. This sink activity in the middle summer in the Beaufort Sea and Elson Lagoon was likely due to biological carbon uptake as inferred by low apparent oxygen utilization and high chlorophyll

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

    PubMed

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

    2015-07-01

    The combined effects of elevated CO2 and cadmium (Cd) on photosynthetic rate, chlorophyll fluorescence and Cd accumulation in hyperaccumulator Sedum alfredii 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 µL L(-1)) or elevated (800 µL 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 all the Cd treatments, but reduced chlorophyll concentration, dark respiration and photorespiration. After 10 days growth in medium with 50 µM Cd under elevated CO2 , PSII activities were significantly enhanced (P < 0.05) with Pm, Fv/Fm, Φ(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. alfredii 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. alfredii due to increased photosynthetic carbon uptake rate and photosynthetic light-use efficiency, and showed great potential to improve the phytoextraction of Cd by S. alfredii. PMID:25370532

  6. [Effects of elevated CO2 concentration on the quality of agricultural products: a review].

    PubMed

    Chai, Ru-shan; Niu, Yao-fang; Zhu, Li-qing; Wang, Huan; Zhang, Yong-song

    2011-10-01

    The increasing concentration of atmospheric CO2 and the nutritional quality of human diets are the two important issues we are facing. At present, the atmospheric CO2 concentration is about 380 micromol mol(-1), and to be reached 550 micromol mol(-1) by 2050. A great deal of researches indicated that the quality of agricultural products is not only determined by inherited genes, but also affected by the crop growth environmental conditions. This paper summarized the common methods adopted at home and abroad for studying the effects of CO2 enrichment on the quality of agricultural products, and reviewed the research advances in evaluating the effects of elevated CO2 on the quality of rice, wheat, soybean, and vegetables. Many experimental results showed that elevated CO2 concentration causes a decrease of protein content in the grains of staple food crops and an overall decreasing trend of trace elements contents in the crops, but improves the quality of vegetable products to some extent. Some issues and future directions regarding the effects of elevated CO2 concentration on the quality of agricultural products were also discussed, based on the present status of related researches. PMID:22263486

  7. Simultaneous measurement of CO2 concentration and isotopic ratios in gas samples using IRMS

    NASA Astrophysics Data System (ADS)

    Yu, Eun-Ji; Lee, Dongho; Bong, Yeon-Sik; Lee, Kwang-Sik

    2014-05-01

    Isotopic methods are indispensable tools for studies on atmosphere-biosphere exchanges of CO2 and environmental monitoring such as CO2 leakage detection from subsurface carbon storages. CO2 concentration is an important variable in interpreting isotopic composition of CO2 especially in atmospheric applications (e.g., 'Keeling plot'). Optical methods such as CRDS (Cavity Ring Down Spectroscopy) are gaining attention recently because of its capability to simultaneously measure CO2 concentration and isotopic ratios with a short measurement interval (up to 1 sec.). On the other hand, IRMS (Isotope Ratio Mass Spectrometer) has been used only for isotopic measurements. In this study, we propose a method to measure CO2 concentration from gas samples along with isotopic ratios using conventional IRMS system. The system consists of Delta V Plus IRMS interfaced with GasBench II (Thermo Scientific, Germany). 12-mL vials with open top screw cap and rubber septum were used for both gas sampling and analysis. For isotopic analysis, gases in the vials were transferred into GasBench II by He carrier flow and CO2 was trapped by a single cryotrap (-180 ºC) after passing a water trap (Mg(ClO4)2). Upon release of the cryotrap, liberated CO2 was separated from N2O using gas chromatography column inside the GasBench II and introduced online into the IRMS. Isotopic ratios were measured for the masses of 44, 45 and 46, and the peak intensity (mV of mass 44 and peak area) was recorded for the concentration calculation. For the determination of CO2 concentration, a calibration curve relating the peak intensity with molar concentration of CO2 was constructed. By dissolving NaHCO3 in de-ionized water, solutions containing 0.05, 0.1, 0.25 and 0.5 µmol of inorganic carbon were prepared in 12 mL vials. Phosphoric acid was injected through rubber septum of the vials to acidify the solution and released CO2 was analyzed for the isotopic ratios and the corresponding peak intensity was recorded

  8. The Concentrations and Possible Effects of CO2 in Geysers of Yellowstone National Park

    NASA Astrophysics Data System (ADS)

    Hurwitz, S.; Evans, W.; Thordsen, J. J.; Murphy, F.

    2012-12-01

    It has long been proposed that non-condensable gases could have a significant impact on the dynamics of geyser eruptions in Yellowstone National Park (Bloss and Barth, 1949). More recently, Hutchinson et al. (1997) postulated that CO2 dissolved in Old Faithful Geyser waters exerts a significant control on its eruptions. Based on the concentrations of major cations and the pH of erupted water and assuming mineral buffering, they calculated a CO2 partial pressure of <0.3 bar. To test the hypothesis suggesting that CO2 could be significant in geyser eruption dynamics, in April 2012 we sampled water and dissolved gases in research well Y-7 located in Biscuit Basin, approximately 3 km NNW of Old Faithful Geyser. Concentrations of major elements in the well are similar to those at Old Faithful Geyser, suggesting that a comparison can be made. The two samples were collected using a pre-evacuated stainless steel sealed sampler near the bottom of the well at a depth of 72 meters and a temperature of 141 °C. The partial pressures of CO2 and H2O(v) at in-situ conditions were calculated to be 0.9 and 3.7 bars, respectively. The calculated dissolved CO2 concentration is less than the saturation concentration at a hydrostatic (+atmospheric) load of ~8 bar (~72 m). However, the measured dissolved CO2 concentrations are more than double the highest concentrations calculated by Hutchinson et al., 1997, and likely support their hypothesis regarding the significance of CO2 in geyser eruptions. Initial calculations suggest CO2 helps induce boiling at shallow levels, exsolving into the steam phase that drives the eruption. The initial bubbles may be CO2 rich, such that the presence of CO2 can have a significant effect on the subsurface seismic signals and on the dynamics of the erupting jet. As boiling progresses during decompression, the CO2 signal will be diluted by the addition of steam. *** Bloss, F.D. and T.F.W. Barth, Bull. Geol. Soc. Amer., 60, 861-8865, 1949. *** Hutchinson, R

  9. The urgency of the development of CO2 capture from ambient air

    PubMed Central

    Lackner, Klaus S.; Brennan, Sarah; Matter, Jürg M.; Park, A.-H. Alissa; Wright, Allen; van der Zwaan, Bob

    2012-01-01

    CO2 capture and storage (CCS) has the potential to develop into an important tool to address climate change. Given society’s present reliance on fossil fuels, widespread adoption of CCS appears indispensable for meeting stringent climate targets. We argue that for conventional CCS to become a successful climate mitigation technology—which by necessity has to operate on a large scale—it may need to be complemented with air capture, removing CO2 directly from the atmosphere. Air capture of CO2 could act as insurance against CO2 leaking from storage and furthermore may provide an option for dealing with emissions from mobile dispersed sources such as automobiles and airplanes. PMID:22843674

  10. The urgency of the development of CO2 capture from ambient air.

    PubMed

    Lackner, Klaus S; Brennan, Sarah; Matter, Jürg M; Park, A-H Alissa; Wright, Allen; van der Zwaan, Bob

    2012-08-14

    CO(2) capture and storage (CCS) has the potential to develop into an important tool to address climate change. Given society's present reliance on fossil fuels, widespread adoption of CCS appears indispensable for meeting stringent climate targets. We argue that for conventional CCS to become a successful climate mitigation technology--which by necessity has to operate on a large scale--it may need to be complemented with air capture, removing CO(2) directly from the atmosphere. Air capture of CO(2) could act as insurance against CO(2) leaking from storage and furthermore may provide an option for dealing with emissions from mobile dispersed sources such as automobiles and airplanes. PMID:22843674

  11. Jena Reference Air Set (JRAS): a multi-point scale anchor for isotope measurements of CO2 in air

    NASA Astrophysics Data System (ADS)

    Wendeberg, M.; Richter, J. M.; Rothe, M.; Brand, W. A.

    2013-03-01

    The need for a unifying scale anchor for isotopes of CO2 in air was brought to light at the 11th WMO/IAEA Meeting of Experts on Carbon Dioxide in Tokyo 2001. During discussions about persistent discrepancies in isotope measurements between the worlds leading laboratories, it was concluded that a unifying scale anchor for Vienna Pee Dee Belemnite (VPDB) of CO2 in air was desperately needed. Ten years later, at the 2011 Meeting of Experts on Carbon Dioxide in Wellington, it was recommended that the Jena Reference Air Set (JRAS) become the official scale anchor for isotope measurements of CO2 in air (Brailsford, 2012). The source of CO2 used for JRAS is two calcites. After releasing CO2 by reaction with phosphoric acid, the gases are mixed into CO2-free air. This procedure ensures both isotopic stability and longevity of the CO2. That the reference CO2 is generated from calcites and supplied as an air mixture is unique to JRAS. This is made to ensure that any measurement bias arising from the extraction procedure is eliminated. As every laboratory has its own procedure for extracting the CO2, this is of paramount importance if the local scales are to be unified with a common anchor. For a period of four years, JRAS has been evaluated through the IMECC1 program, which made it possible to distribute sets of JRAS gases to 13 laboratories worldwide. A summary of data from the six laboratories that have reported the full set of results is given here along with a description of the production and maintenance of the JRAS scale anchors. 1 IMECC refers to the EU project "Infrastructure for Measurements of the European Carbon Cycle" (http://imecc.ipsl.jussieu.fr/).

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  13. Surface Ocean pCO2 Seasonality and Sea-Air CO2 Flux Estimates for the North American East Coast

    NASA Technical Reports Server (NTRS)

    Signorini, Sergio; Mannino, Antonio; Najjar, Raymond G., Jr.; Friedrichs, Marjorie A. M.; Cai, Wei-Jun; Salisbury, Joe; Wang, Zhaohui Aleck; Thomas, Helmuth; Shadwick, Elizabeth

    2013-01-01

    Underway and in situ observations of surface ocean pCO2, combined with satellite data, were used to develop pCO2 regional algorithms to analyze the seasonal and interannual variability of surface ocean pCO2 and sea-air CO2 flux for five physically and biologically distinct regions of the eastern North American continental shelf: the South Atlantic Bight (SAB), the Mid-Atlantic Bight (MAB), the Gulf of Maine (GoM), Nantucket Shoals and Georges Bank (NS+GB), and the Scotian Shelf (SS). Temperature and dissolved inorganic carbon variability are the most influential factors driving the seasonality of pCO2. Estimates of the sea-air CO2 flux were derived from the available pCO2 data, as well as from the pCO2 reconstructed by the algorithm. Two different gas exchange parameterizations were used. The SS, GB+NS, MAB, and SAB regions are net sinks of atmospheric CO2 while the GoM is a weak source. The estimates vary depending on the use of surface ocean pCO2 from the data or algorithm, as well as with the use of the two different gas exchange parameterizations. Most of the regional estimates are in general agreement with previous studies when the range of uncertainty and interannual variability are taken into account. According to the algorithm, the average annual uptake of atmospheric CO2 by eastern North American continental shelf waters is found to be between 3.4 and 5.4 Tg C/yr (areal average of 0.7 to 1.0 mol CO2 /sq m/yr) over the period 2003-2010.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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

  16. Air-water CO2 outgassing in the Lower Lakes (Alexandrina and Albert, Australia) following a millennium drought.

    PubMed

    Li, Siyue; Bush, Richard T; Ward, Nicholas J; Sullivan, Leigh A; Dong, Fangyong

    2016-01-15

    Lakes are an important source and sink of atmospheric CO2, and thus are a vital component of the global carbon cycle. However, with scarce data on potentially important subtropical and tropical areas for whole continents such as Australia, the magnitude of large-scale lake CO2 emissions is unclear. This study presents spatiotemporal changes of dissolved inorganic carbon and water - to - air interface CO2 flux in the two of Australia's largest connected, yet geomorphically different freshwater lakes (Lake Alexandrina and Lake Albert, South Australia), during drought (2007 to September-2010) and post-drought (October 2010 to 2013). Lake levels in the extreme drought were on average approximately 1m lower than long-term average (0.71 m AHD). Drought was associated with an increase in the concentrations of dissolved inorganic species, organic carbon, nitrogen, Chl-a and major ions, as well as water acidification as a consequence of acid sulfate soil (ASS) exposure, and hence, had profound effects on lake pCO2 concentrations. Lakes Alexandrina and Albert were a source of CO2 to the atmosphere during the drought period, with efflux ranging from 0.3 to 7.0 mmol/m(2)/d. The lake air-water CO2 flux was negative in the post-drought, ranging between -16.4 and 0.9 mmol/m(2)/d. The average annual CO2 emission was estimated at 615.5×10(6) mol CO2/y during the drought period. These calculated emission rates are in the lower range for lakes, despite the potential for drought conditions that shift the lakes from sink to net source for atmospheric CO2. These observations have significant implications in the context of predicted increasing frequency and intensity of drought as a result of climate change. Further information on the spatial and temporal variability in CO2 flux from Australian lakes is urgently warranted to revise the global carbon budget for lakes. PMID:26520269

  17. 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

    NASA Astrophysics Data System (ADS)

    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.

  18. APO observations in Southern Greenland: evaluation of modelled air-sea O2 and CO2 fluxes

    NASA Astrophysics Data System (ADS)

    Bonne, Jean-Louis; Bopp, Laurent; Delmotte, Marc; Cadule, Patricia; Resplandy, Laure; Nevison, Cynthia; Manizza, Manfredi; Valentin Lavric, Jost; Manning, Andrew C.; Masson-Delmotte, Valérie

    2014-05-01

    Since September 2007, the atmospheric CO2 mole fraction and O2/N2 ratio (a proxy for O2 concentration) have been monitored continuously at the coastal site of Ivittuut, southern Greenland (61.21° N, 48.17° W). From 2007 to 2013, our measurements show multi-annual trends of +2.0 ppm/year and -20 per meg/year respectively for CO2 and O2/N2, with annual average peak-to-peak seasonal amplitudes of 14+/-1 ppm and 130+/-15 per meg. We investigate the implications of our data set in terms of APO (Atmospheric Potential Oxygen). This tracer, obtained by a linear combination of CO2 and O2/N2 data, is invariant to CO2 and O2 exchanges in the land biota, but sensitive to the oceanic component of the O2 cycle. It is used as a bridge to evaluate air-sea CO2 and O2 fluxes from atmospheric variations of CO2 and O2/N2. Global ocean biogeochemical models produce estimates of CO2 and O2 air-sea fluxes. Atmospheric APO variations can be simulated through transportation of these fluxes in the atmosphere by Eulerian transport models. Thus, model values of atmospheric APO can be extracted at the station location. This study is based on air-sea flux outputs from CMIP5 simulations. After atmospheric transportation, they give access to atmospheric APO climatologies which can be compared, in terms of seasonal cycles and inter-annual variability, to the in situ observations. A preliminary study is based on the CCSM ocean model air-sea fluxes transported in the atmosphere with the MATCH transport model, over the period 1979-2004. The amplitude of the APO seasonal cycle is correctly captured, but year to year variations on this seasonal cycle appears to be underestimated compared to observations. The LMDZ atmospheric transport model is also used to transport the ocean fluxes from five CMIP5 models, over the period 1979-2005, showing different amplitudes and timings of APO seasonal cycles. This methodology is a first step to evaluate the origin of observed APO variations at our site and then

  19. The stomatal CO2 proxy does not saturate at high atmospheric CO2 concentrations: evidence from stomatal index responses of Araucariaceae conifers.

    PubMed

    Haworth, Matthew; Elliott-Kingston, Caroline; McElwain, Jennifer C

    2011-09-01

    The inverse relationship between the number of stomata on a leaf surface and the atmospheric carbon dioxide concentration ([CO(2)]) in which the leaf developed allows plants to optimise water-use efficiency (WUE), but it also permits the use of fossil plants as proxies of palaeoatmospheric [CO(2)]. The ancient conifer family Araucariaceae is often represented in fossil floras and may act as a suitable proxy of palaeo-[CO(2)], yet little is known regarding the stomatal index (SI) responses of extant Araucariaceae to [CO(2)]. Four Araucaria species (Araucaria columnaris, A. heterophylla, A. angustifolia and A. bidwillii) and Agathis australis displayed no significant relationship in SI to [CO(2)] below current ambient levels (~380 ppm). However, representatives of the three extant genera within the Araucariaceae (A. bidwillii, A. australis and Wollemia nobilis) all exhibited significant reductions in SI when grown in atmospheres of elevated [CO(2)] (1,500 ppm). Stomatal conductance was reduced and WUE increased when grown under elevated [CO(2)]. Stomatal pore length did not increase alongside reduced stomatal density (SD) and SI in the three araucariacean conifers when grown at elevated [CO(2)]. These pronounced SD and SI reductions occur at higher [CO(2)] levels than in other species with more recent evolutionary origins, and may reflect an evolutionary legacy of the Araucariaceae in the high [CO(2)] world of the Mesozoic Era. Araucariacean conifers may therefore be suitable stomatal proxies of palaeo-[CO(2)] during periods of "greenhouse" climates and high [CO(2)] in the Earth's history. PMID:21461935

  20. Continuous monitoring of surface CO2 flux and soil gas concentrations in an agricultural soil under the snow cover manipulation experiment in Hokkaido, northern Japan

    NASA Astrophysics Data System (ADS)

    Ohkubo, S.; Yanai, Y.; Nagata, O.; Iwata, Y.; Hirota, T.

    2010-12-01

    In the eastern part of Hokkaido, northern Japan, a timing of snow fall has been getting earlier and soil-frost depth has been decreasing in agricultural land year by year since late 1980. It is reported that the significant decrease in frost depths was due to the early development of snow cover that insulates ground from cold. Agricultural land is usually managed by human operations and so there is a possibility of controlling greenhouse gas (GHG) emissions. It is therefore important how snow and soil frost influence the dynamics of GHGs. CO2 is one of the main GHGs. We continuously and automatically observed CO2 flux above soil or snow surface and CO2 concentration in soil at 10 cm depth, using automatically controlled chambers and CO2 sensors over agricultural land at Sapporo site (141°25’E, 43°05’N) in northern Japan. Observations were conducted from 25 September 2009 to 31 May 2010, with occasional manual observations. We prepared two experimental plots, an untreated control and a snow cover removal plot, to evaluate the influence of soil-frost and snow depth on CO2 dynamics. Acquired automatic data in CO2 flux and soil gas CO2 concentration generally have diurnal variations which had a positive peak in the daytime as affected by soil temperature, except winter period. Rainfall increased CO2 flux and soil gas CO2 concentration. During soil freezing and snow covered period, few CO2 flux was observed. Soil gas CO2 concentration had been increasing during soil freezing period. After soil thawing, CO2 flux had increased and CO2 concentration had decreased temporarily. These phenomena being seen regardless of soil temperature, supportred that snow and soil-frost layer prevent gas diffusion to the air. The gas diffusion coefficient calculated from CO2 flux and soil gas CO2 concentration during soil gas CO2 concentration had been increasing during soil freezing period, was less than about one order of magnitudes of those in other periods. Temperature response

  1. Amine-Oxide Hybrid Materials for CO2 Capture from Ambient Air.

    PubMed

    Didas, Stephanie A; Choi, Sunho; Chaikittisilp, Watcharop; Jones, Christopher W

    2015-10-20

    Oxide supports functionalized with amine moieties have been used for decades as catalysts and chromatographic media. Owing to the recognized impact of atmospheric CO2 on global climate change, the study of the use of amine-oxide hybrid materials as CO2 sorbents has exploded in the past decade. While the majority of the work has concerned separation of CO2 from dilute mixtures such as flue gas from coal-fired power plants, it has been recognized by us and others that such supported amine materials are also perhaps uniquely suited to extract CO2 from ultradilute gas mixtures, such as ambient air. As unique, low temperature chemisorbents, they can operate under ambient conditions, spontaneously extracting CO2 from ambient air, while being regenerated under mild conditions using heat or the combination of heat and vacuum. This Account describes the evolution of our activities on the design of amine-functionalized silica materials for catalysis to the design, characterization, and utilization of these materials in CO2 separations. New materials developed in our laboratory, such as hyperbranched aminosilica materials, and previously known amine-oxide hybrid compositions, have been extensively studied for CO2 extraction from simulated ambient air (400 ppm of CO2). The role of amine type and structure (molecular, polymeric), support type and structure, the stability of the various compositions under simulated operating conditions, and the nature of the adsorbed CO2 have been investigated in detail. The requirements for an effective, practical air capture process have been outlined and the ability of amine-oxide hybrid materials to meet these needs has been discussed. Ultimately, the practicality of such a "direct air capture" process is predicated not only on the physicochemical properties of the sorbent, but also how the sorbent operates in a practical process that offers a scalable gas-solid contacting strategy. In this regard, the utility of low pressure drop monolith

  2. Diurnal Variation of CO2 concentration above a tropical reservoir in the central Amazonia

    NASA Astrophysics Data System (ADS)

    do Vale, R. S.; Santana, R. A. S. D.; Tota, J.; Souza, R. A. F. D.; Miller, S. D.

    2014-12-01

    The tropical reservoirs of hydroeletric plants have an important role in greenhouse gas emissions into the atmosphere. Due to the large extension of the reservoirs, the lake breeze or land breeze can influence the transport and dispersion of gases. The Balbina reservoir (59° 28' 50'' W, 1° 53' 25''; S), located near Manaus-AM in central Amazonia, is the second biggest hydroeletric plant resevoir in the Amazon basin and has a flooded area of 1770 km2 with an average depth of 10 m, which is enough to produce a dynamic land-lake breeze. In this reservoir, we measured wind direction and velocity from a meteorological buoy and carbon dioxide (CO2) concentrations at 2 m above the lake surface with a high frequency sensor, from 18th to 19th July/2013. The CO2 concentrations were measured at 10 Hz and data were averaged every 5 min during 32 hours. The lake breeze and land breeze from the forest around the lake showed a well-defined behavior, the lake breeze being predominantly from south (S) and the land breeze predominantly from north (N). The CO2 concentration averages were 392 and 426 ppm for daytime and nighttime, respectively. During daytime the atmosphere above the lake was well mixed due to unstable stratification and moderately strong wind speeds. The accumulation of CO2 concentration above the lake at night may have been affected by low wind speeds and enhanced CO2 flux from the water surface due to buoyancy-induced turbulence and physical processes that brought high-CO2 water to the surface. Advection of CO2 from the adjacent forest (land breeze) was also possible.

  3. Flow properties in expansion tube with helium, argon, air, and CO2

    NASA Technical Reports Server (NTRS)

    Miller, C. G.

    1974-01-01

    Test flow velocities from 5 to 7 km/sec were generated in a 6-in. expansion tube using helium, argon, air, and CO2 test gases. Pitot pressure profiles across the flow at the test section are presented for the four test gases, and measured flow quantities are compared to computer predicted values. Comparison of predicted and measured flow quantities suggests the expansion to be near thermochemical equilibrium for all test gases and implies the existence of a totally reflected shock at the secondary diaphragm. Argon, air, and CO2 flows were observed to attenuate while traversing the acceleration section, whereas no attenuation was observed for helium.

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  5. Abrupt CO2 experiments as tools for predicting and understanding CMIP5 representative concentration pathway projections

    NASA Astrophysics Data System (ADS)

    Good, Peter; Gregory, Jonathan M.; Lowe, Jason A.; Andrews, Timothy

    2013-02-01

    A fast simple climate modelling approach is developed for predicting and helping to understand general circulation model (GCM) simulations. We show that the simple model reproduces the GCM results accurately, for global mean surface air temperature change and global-mean heat uptake projections from 9 GCMs in the fifth coupled model inter-comparison project (CMIP5). This implies that understanding gained from idealised CO2 step experiments is applicable to policy-relevant scenario projections. Our approach is conceptually simple. It works by using the climate response to a CO2 step change taken directly from a GCM experiment. With radiative forcing from non-CO2 constituents obtained by adapting the Forster and Taylor method, we use our method to estimate results for CMIP5 representative concentration pathway (RCP) experiments for cases not run by the GCMs. We estimate differences between pairs of RCPs rather than RCP anomalies relative to the pre-industrial state. This gives better results because it makes greater use of available GCM projections. The GCMs exhibit differences in radiative forcing, which we incorporate in the simple model. We analyse the thus-completed ensemble of RCP projections. The ensemble mean changes between 1986-2005 and 2080-2099 for global temperature (heat uptake) are, for RCP8.5: 3.8 K (2.3 × 1024 J); for RCP6.0: 2.3 K (1.6 × 1024 J); for RCP4.5: 2.0 K (1.6 × 1024 J); for RCP2.6: 1.1 K (1.3 × 1024 J). The relative spread (standard deviation/ensemble mean) for these scenarios is around 0.2 and 0.15 for temperature and heat uptake respectively. We quantify the relative effect of mitigation action, through reduced emissions, via the time-dependent ratios (change in RCPx)/(change in RCP8.5), using changes with respect to pre-industrial conditions. We find that the effects of mitigation on global-mean temperature change and heat uptake are very similar across these different GCMs.

  6. Atmospheric CO2 concentrations during ancient greenhouse climates were similar to those predicted for A.D. 2100

    PubMed Central

    Breecker, D. O.; Sharp, Z. D.; McFadden, L. D.

    2010-01-01

    Quantifying atmospheric CO2 concentrations ([CO2]atm) during Earth’s ancient greenhouse episodes is essential for accurately predicting the response of future climate to elevated CO2 levels. Empirical estimates of [CO2]atm during Paleozoic and Mesozoic greenhouse climates are based primarily on the carbon isotope composition of calcium carbonate in fossil soils. We report that greenhouse [CO2]atm have been significantly overestimated because previously assumed soil CO2 concentrations during carbonate formation are too high. More accurate [CO2]atm, resulting from better constraints on soil CO2, indicate that large (1,000s of ppmV) fluctuations in [CO2]atm did not characterize ancient climates and that past greenhouse climates were accompanied by concentrations similar to those projected for A.D. 2100. PMID:20080721

  7. Atmospheric CO2 concentrations during ancient greenhouse climates were similar to those predicted for A.D. 2100.

    PubMed

    Breecker, D O; Sharp, Z D; McFadden, L D

    2010-01-12

    Quantifying atmospheric CO(2) concentrations ([CO(2)](atm)) during Earth's ancient greenhouse episodes is essential for accurately predicting the response of future climate to elevated CO(2) levels. Empirical estimates of [CO(2)](atm) during Paleozoic and Mesozoic greenhouse climates are based primarily on the carbon isotope composition of calcium carbonate in fossil soils. We report that greenhouse [CO(2)](atm) have been significantly overestimated because previously assumed soil CO(2) concentrations during carbonate formation are too high. More accurate [CO(2)](atm), resulting from better constraints on soil CO(2), indicate that large (1,000s of ppmV) fluctuations in [CO(2)](atm) did not characterize ancient climates and that past greenhouse climates were accompanied by concentrations similar to those projected for A.D. 2100. PMID:20080721

  8. Air--Sea CO2 Cycling in the Southeastern Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Else, Brent Gordon Thomas

    During the fourth International Polar Year, an interdisciplinary study was conducted to examine the couplings between sea ice, ocean, atmosphere, and ecosystem in the southeastern Beaufort Sea. This thesis examines components of the system that control the air-sea exchange of carbon dioxide. Using eddy covariance measurements, we found enhanced CO2 exchange associated with new ice formation in winter flaw leads. This exchange was typically directed towards the surface, although we also measured one instance of outgassing. Sea surface dissolved CO2 measurements (pCO 2sw) in Amundsen Gulf showed significant undersaturation with respect to the atmosphere at freeze-up, followed by a slow increase over the winter until spring phytoplankton blooms caused strong undersaturation at break-up. Over the summer, pCO2sw increased until becoming slightly supersaturated due to surface warming. Along the southern margins of Amundsen Gulf and on the Mackenzie Shelf we found pCO2sw supersaturations in the fall due to wind-driven coastal upwelling. In the spring, this upwelling occurred along the landfast ice edges of Amundsen Gulf. By combining observations of enhanced winter gas exchange with observations of pCO 2sw in Amundsen Gulf, we derived an annual budget of air-sea CO2 exchange for the region. This exercise showed that uptake through the winter season was as important as the open water season, making the overall annual uptake of CO2 about double what had previously been calculated. Prior to this work, the prevailing paradigm of airsea CO2 cycling in Arctic polynya regions posited that strong CO2 absorption occurs in the open water seasons, and that a potential outgassing during the winter is inhibited by the sea ice cover. As a new paradigm, we propose that the spatial and temporal variability of many processes---including phytoplankton blooms, sea surface temperature and salinity changes, upwelling, river input, continental shelf processes, and the potential for high rates

  9. Can we use the CO2 concentrations determined by continuous-flow isotope ratio mass spectrometry from small samples for the Keeling plot approach?

    PubMed

    Joos, Ottmar; Saurer, Matthias; Heim, Alexander; Hagedorn, Frank; Schmidt, Michael W I; Siegwolf, Rolf T W

    2008-12-01

    A common method to estimate the carbon isotopic composition of soil-respired air is to use Keeling plots (delta(13)C versus 1/CO2 concentration). This approach requires the precise determination of both CO2 concentration ([CO2]), usually measured with an infrared gas analyser (IRGA) in the field, and the analysis of delta(13)C by isotope ratio mass spectrometry (IRMS) in the laboratory. We measured [CO2] with an IRGA in the field (n = 637) and simultaneously collected air samples in 12 mL vials for analysis of the 13C values and the [CO2] using a continuous-flow isotope ratio mass spectrometer. In this study we tested if measurements by the IRGA and IRMS yielded the same results for [CO2], and also investigated the effects of different sample vial preparation methods on the [CO2] measurement and the thereby obtained Keeling plot results. Our results show that IRMS measurements of the [CO2] (during the isotope analysis) were lower than when the [CO2] was measured in the field with the IRGA. This is especially evident when the sample vials were not treated in the same way as the standard vials. From the three different vial preparation methods, the one using N2-filled and overpressurised vials resulted in the best agreement between the IRGA and IRMS [CO2] values. There was no effect on the (13)C-values from the different methods. The Keeling plot results confirmed that the overpressurised vials performed best. We conclude that in the cases where the ranges of [CO2] are large (>300 ppm; in our case it ranged between 70 and 1500 ppm) reliable estimation of the [CO2] with small samples using IRMS is possible for Keeling plot application. We also suggest some guidelines for sample handling in order to achieve proper results. PMID:19009520

  10. Seasonal variations of stable, including clumped, isotopologues of CO2 in air: Initial observations from La Jolla, Ca

    NASA Astrophysics Data System (ADS)

    Thiagarajan, N.; Passey, B. H.; Keeling, R. F.; Eiler, J. M.

    2014-12-01

    The budget of atmospheric CO2 is commonly studied using records of CO2 concentrations and isotopic abundances. δ13C and δ18O are the most frequently used isotopic tracers and can be used to constrain marine and terrestrial fluxes. However, the large number of sources and sinks prevents concentrations, d13C and d18O alone from uniquely constraining the budget. Δ17O as well as clumped isotopologues of CO2 can provide independent constraints on CO2 fluxes. Here we present a record covering multiple 1+ year periods between 2003 and 2012 documenting seasonal variations at La Jolla, CA, of δ13C, δ18O and clumped isotopologues of CO2 as well as preliminary results for Δ17O. Samples were collected from the La Jolla pier only on days a seaward breeze was present, therefore local anthropogenic effects should be minimal. We report the clumped isotopologues of CO2 using Δ47 notation in the absolute reference frame. In the years studied, δ13C showed a seasonal cycle that is consistent with previous measurements and can be explained by the seasonal variation in photosynthetic activity of plants as well as a longer term trend of fossil fuel injection into the atmosphere. Similarly δ18O showed a seasonal and interannual cycle that is consistent with previous measurements and can be explained by the interaction of the terrestrial biosphere with the hydrologic cycle. The La Jolla ∆47 record shows a strong seasonal pattern for all years studied, and initial results suggest seasonality is also present in ∆17O. The La Jolla ∆47 pattern is similar to the Pasadena ∆47 record collected for 2003-2004. Both records exhibit amplitudes and phasing of ∆47 variations that are not consistent with the equilibration of CO2 with the local air or sea surface temperatures, nor can they be explained by fossil fuel burning, which can only weakly influence the seasonal cycles. The seasonal cycle may be explained in part by a competition between low ∆47 from respiration sources and

  11. Air-water CO2 exchange in five hypereutrophic lakes in Bangalore, India

    NASA Astrophysics Data System (ADS)

    Singh, G.; Ghosh, P.; Bala, G.; Bastviken, D.

    2014-12-01

    Inland water bodies play a significant role in terrestrial carbon cycling, rather than being just conduits for the transport of terrestrial carbon to the oceans. Recent syntheses estimate that freshwaters emit substantial amounts of CO2 (1.4 Pg C yr-1) (Tranvik et al. 2009) and CH4 (0.65 Pg C yr-1) (Bastviken et al. 2011), which are similar in magnitude to the global terrestrial carbon sink (2.5 ± 1.7 Pg C yr-1) (IPCC 2013). However, eutrophic waters, which constitute the majority of the global freshwater supply (ILEC/UNEP 1994, Liu et al. 2012, Carpenter et al. 1998), are vastly underrepresented in these estimates. These waters, due to high primary productivity leading to CO2 undersaturation, can act as sinks rather than sources of CO2, thus reversing the role of lakes in the carbon cycle (Balmer and Downing 2011, Pacheco et al. 2013). We are investigating the air-water CO2 exchange of five hypereutrophic lakes in urban Bangalore using a novel Non-Dispersive Infrared (NDIR)-based CO2 sensor installed in flux chambers that can be used to measure CO2 exchange in lakes in situ. This work is a part of a larger study called Bangalore Carbon Mapping Study that aims to track the spatial flows of carbon in an urban area of a developing country. Preliminary observations reveal that these lakes absorb CO2 during the photosynthetic hours, at an average rate of 3.4 mg C m-2 h-1. The ongoing study will characterize the complete diurnal cycle of CO2 exchange, its variation over different seasons, and its relationships with various limnological and catchment characteristics. The flux estimates thus produced will also be compared with those predicted by the current models for air-water gas exchange based on wind speed.

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Reconstruction of super-resolution fields of ocean pCO2 and air-sea fluxes of CO2 from satellite imagery in the Southeastern Atlantic

    NASA Astrophysics Data System (ADS)

    Hernández-Carrasco, I.; Sudre, J.; Garçon, V.; Yahia, H.; Garbe, C.; Paulmier, A.; Dewitte, B.; Illig, S.; Dadou, I.

    2015-01-01

    The knowledge of Green House Gases GHGs fluxes at the air-sea interface at high resolution is crucial to accurately quantify the role of the ocean in the absorption and emission of GHGs. In this paper we present a novel method to reconstruct maps of surface ocean partial pressure of CO2, pCO2, and air-sea CO2 fluxes at super resolution (4 km) using Sea Surface Temperature (SST) and Ocean Colour (OC) data at this resolution, and CarbonTracker CO2 fluxes data at low resolution (110 km). Inference of super-resolution of pCO2, and air-sea CO2 fluxes is performed using novel nonlinear signal processing methodologies that prove efficient in the context of oceanography. The theoretical background comes from the Microcanonical Multifractal Formalism which unlocks the geometrical determination of cascading properties of physical intensive variables. As a consequence, a multiresolution analysis performed on the signal of the so-called singularity exponents allows the correct and near optimal cross-scale inference of GHGs fluxes, as the inference suits the geometric realization of the cascade. We apply such a methodology to the study offshore of the Benguela area. The inferred representation of oceanic partial pressure of CO2 improves and enhances the description provided by CarbonTracker, capturing the small scale variability. We examine different combinations of Ocean Colour and Sea Surface Temperature products in order to increase the number of valid points and the quality of the inferred pCO2 field. The methodology is validated using in-situ measurements by means of statistical errors. We obtain that mean absolute and relative errors in the inferred values of pCO2 with respect to in-situ measurements are smaller than for CarbonTracker.

  14. Reconstruction of super-resolution ocean pCO2 and air-sea fluxes of CO2 from satellite imagery in the southeastern Atlantic

    NASA Astrophysics Data System (ADS)

    Hernández-Carrasco, I.; Sudre, J.; Garçon, V.; Yahia, H.; Garbe, C.; Paulmier, A.; Dewitte, B.; Illig, S.; Dadou, I.; González-Dávila, M.; Santana-Casiano, J. M.

    2015-09-01

    An accurate quantification of the role of the ocean as source/sink of greenhouse gases (GHGs) requires to access the high-resolution of the GHG air-sea flux at the interface. In this paper we present a novel method to reconstruct maps of surface ocean partial pressure of CO2 ( pCO2) and air-sea CO2 fluxes at super resolution (4 km, i.e., 1/32° at these latitudes) using sea surface temperature (SST) and ocean color (OC) data at this resolution, and CarbonTracker CO2 fluxes data at low resolution (110 km). Inference of super-resolution pCO2 and air-sea CO2 fluxes is performed using novel nonlinear signal processing methodologies that prove efficient in the context of oceanography. The theoretical background comes from the microcanonical multifractal formalism which unlocks the geometrical determination of cascading properties of physical intensive variables. As a consequence, a multi-resolution analysis performed on the signal of the so-called singularity exponents allows for the correct and near optimal cross-scale inference of GHG fluxes, as the inference suits the geometric realization of the cascade. We apply such a methodology to the study offshore of the Benguela area. The inferred representation of oceanic partial pressure of CO2 improves and enhances the description provided by CarbonTracker, capturing the small-scale variability. We examine different combinations of ocean color and sea surface temperature products in order to increase the number of valid points and the quality of the inferred pCO2 field. The methodology is validated using in situ measurements by means of statistical errors. We find that mean absolute and relative errors in the inferred values of pCO2 with respect to in situ measurements are smaller than for CarbonTracker.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Aircraft measurements of the concentrations of CO2, CH4, N2O, and CO and the carbon and oxygen isotopic ratios of CO2 in the troposphere over Russia

    NASA Astrophysics Data System (ADS)

    Nakazawa, Takakiyo; Sugawara, Satoshi; Inoue, Gen; Machida, Toshinobu; Makshyutov, Shamil; Mukai, Hitoshi

    1997-02-01

    About 370 air samples were collected using aircraft in the troposphere over Russia in the summers of 1992, 1993, and 1994. These were then analyzed for the CO2, CH4, N2O and CO concentrations, as well as for δ13C and δ18O of CO2. Measured vertical profiles of tropospheric CO2 showed that the concentration increased with height over all locations. In the lower troposphere over the wetland and taiga regions, extremely low CO2 concentrations of 335-345 parts per million by volume (ppmv) were often observed. Measured values of δ13C and the CO2 concentration were negatively correlated with each other, the rate of change in δ13C with respect to the CO2 concentration being about -0.05‰/ppmv. This implies that the variations in the CO2 concentration observed over Russia in the summer are primarily caused by terrestrial biospheric activities. In the middle and upper troposphere, the CO2 concentration and δ13C showed systematic differences between each other in 1992, 1993, and 1994, probably due to their secular changes. The δ18O and CO2 observed in the lowest part of the troposphere over east and west Siberia were also negatively correlated with each other, with the rate of change in δ18O with respect to CO2 estimated to be about -0.1 l‰/ppmv. This relation may be caused by isotopic equilibrium of oxygen in CO2 with soil water through respiration of living plants and decomposition of organic matter and with chloroplast water in leaves through photosynthesis of living plants. In contrast to CO2, the CH4 concentration decreased with height. Extremely high CH4 concentrations were observed over the west Siberian lowland, owing to a large amount of CH4 emitted from wetlands. The N2O concentrations were fairly constant through the troposphere over all locations covered by this study, with an average value of about 311 parts per billion by volume (ppbv). The CO concentrations also showed vertical profiles, with a small gradient over natural wetlands, taiga, and tundra

  17. CO2 and H2S concentrations in the atmosphere at the Solfatara of Pozzuoli

    NASA Astrophysics Data System (ADS)

    Carapezza, M.; Gurrieri, S.; Nuccio, P. M.; Valenza, M.

    1984-06-01

    The CO2 and H2S concentration in the Solfatara atmosphere has been measured. The concentrations of both gases are higher neraby the more active areas and decrease away from them. A sharp horizontal and vertical gradient of the CO2 content has been recognized. Such gradient is assumed to result from a diffusion of gas from the ground to the atmosphere. The total output of CO2 has been computed based on a turbulent diffusion model. The obtained value is in good agreement with previously abserved values ( Italiano et al., 1984). The feasibility of monitoring the atmosphere of Solfatara for either gas hazard and surveillance of volcanic activity has also been evaluated.

  18. Poly(ethylenimine)-Functionalized Monolithic Alumina Honeycomb Adsorbents for CO2 Capture from Air.

    PubMed

    Sakwa-Novak, Miles A; Yoo, Chun-Jae; Tan, Shuai; Rashidi, Fereshteh; Jones, Christopher W

    2016-07-21

    The development of practical and effective gas-solid contactors is an important area in the development of CO2 capture technologies. Target CO2 capture applications, such as postcombustion carbon capture and sequestration (CCS) from power plant flue gases or CO2 extraction directly from ambient air (DAC), require high flow rates of gas to be processed at low cost. Extruded monolithic honeycomb structures, such as those employed in the catalytic converters of automobiles, have excellent potential as structured contactors for CO2 adsorption applications because of the low pressure drop imposed on fluid moving through the straight channels of such structures. Here, we report the impregnation of poly(ethylenimine) (PEI), an effective aminopolymer reported commonly for CO2 separation, into extruded monolithic alumina to form structured CO2 sorbents. These structured sorbents are first prepared on a small scale, characterized thoroughly, and compared with powder sorbents with a similar composition. Despite consistent differences observed in the filling of mesopores with PEI between the monolithic and powder sorbents, their performance in CO2 adsorption is similar across a range of PEI contents. A larger monolithic cylinder (1 inch diameter, 4 inch length) is evaluated under conditions closer to those that might be used in large-scale applications and shows a similar performance to the smaller monoliths and powders tested initially. This larger structure is evaluated over five cycles of CO2 adsorption and steam desorption and demonstrates a volumetric capacity of 350 molCO2  m-3monolith and an equilibration time of 350 min under a 0.4 m s(-1) linear flow velocity through the monolith channels using 400 ppm CO2 in N2 as the adsorption gas at 30 °C. This volumetric capacity surpasses that of a similar technology considered previously, which suggested that CO2 could be removed from air at an operating cost as low as $100 per ton. PMID:27304708

  19. An assessment of the Atlantic and Arctic sea-air CO2 fluxes, 1990-2009

    NASA Astrophysics Data System (ADS)

    Schuster, U.; McKinley, G. A.; Bates, N.; Chevallier, F.; Doney, S. C.; Fay, A. R.; González-Dávila, M.; Gruber, N.; Jones, S.; Krijnen, J.; Landschützer, P.; Lefèvre, N.; Manizza, M.; Mathis, J.; Metzl, N.; Olsen, A.; Rios, A. F.; Rödenbeck, C.; Santana-Casiano, J. M.; Takahashi, T.; Wanninkhof, R.; Watson, A. J.

    2013-01-01

    The Atlantic and Arctic Oceans are critical components of the global carbon cycle. Here we quantify the net sea-air CO2 flux, for the first time, across different methodologies for consistent time and space scales for the Atlantic and Arctic basins. We present the long-term mean, seasonal cycle, interannual variability and trends in sea-air CO2 flux for the period 1990 to 2009, and assign an uncertainty to each. We use regional cuts from global observations and modeling products, specifically a pCO2-based CO2 flux climatology, flux estimates from the inversion of oceanic and atmospheric data, and results from six ocean biogeochemical models. Additionally, we use basin-wide flux estimates from surface ocean pCO2 observations based on two distinct methodologies. Our estimate of the contemporary sea-air flux of CO2 (sum of anthropogenic and natural components) by the Atlantic between 40° S and 79° N is -0.49 ± 0.05 Pg C yr-1, and by the Arctic it is -0.12 ± 0.06 Pg C yr-1, leading to a combined sea-air flux of -0.61 ± 0.06 Pg C yr-1 for the two decades (negative reflects ocean uptake). We do find broad agreement amongst methodologies with respect to the seasonal cycle in the subtropics of both hemispheres, but not elsewhere. Agreement with respect to detailed signals of interannual variability is poor, and correlations to the North Atlantic Oscillation are weaker in the North Atlantic and Arctic than in the equatorial region and southern subtropics. Linear trends for 1995 to 2009 indicate increased uptake and generally correspond between methodologies in the North Atlantic, but there is disagreement amongst methodologies in the equatorial region and southern subtropics.

  20. Atlantic and Arctic sea-air CO2 fluxes, 1990-2009

    NASA Astrophysics Data System (ADS)

    Schuster, U.; McKinley, G. A.; Bates, N.; Chevallier, F.; Doney, S. C.; Fay, A. R.; González-Dávila, M.; Gruber, N.; Jones, S.; Krijnen, J.; Landschützer, P.; Lefèvre, N.; Manizza, M.; Mathis, J.; Metzl, N.; Olsen, A.; Rios, A. F.; Rödenbeck, C.; Santana-Casiano, J. M.; Takahashi, T.; Wanninkhof, R.; Watson, A. J.

    2012-08-01

    The Atlantic and Arctic oceans are critical components of the global carbon cycle. Here we quantify the net sea-air CO2 flux, for the first time, across different methodologies for consistent time and space scales, for the Atlantic and Arctic basins. We present the long-term mean, seasonal cycle, interannual variability and trends in sea-air CO2 flux for the period 1990 to 2009, and assign an uncertainty to each. We use regional cuts from global observations and modelling products, specifically a pCO2-based CO2 flux climatology, flux estimates from the inversion of oceanic and atmospheric data, and results from six ocean biogeochemical models. Additionally, we use basin-wide flux estimates from surface ocean pCO2 observations based on two distinct methodologies. Our best estimate of the contemporary sea-to-air flux of CO2 (sum of anthropogenic and natural components) by the Atlantic between 40° S and 79° N is -0.49 ± 0.11 Pg C yr-1 and by the Arctic is -0.12 ± 0.06 Pg C yr-1, leading to a combined sea-to-air flux of -0.61 ± 0.12 Pg C yr-1 for the two decades (negative reflects ocean uptake). We do find broad agreement amongst methodologies with respect to the seasonal cycle in the subtropics of both hemispheres, but not elsewhere. Agreement with respect to detailed signals of interannual variability is poor; and correlations to the North Atlantic Oscillation are weaker in the North Atlantic and Arctic than in the equatorial region and South Subtropics. Linear trends for 1995 to 2009 indicate increased uptake and generally correspond between methodologies in the North Atlantic, but there is disagreement amongst methodologies in the equatorial region and South Subtropics.

  1. Direct Air Capture of CO2 - an Overview of Carbon Engineering's Technology and Pilot Plant Development

    NASA Astrophysics Data System (ADS)

    Holmes, G.; Corless, A.

    2014-12-01

    At Carbon Engineering, we are developing and commercializing technology to scrub CO2 directly from atmospheric air at industrial scale. By providing atmospheric CO2 for use in fuel production, we can enable production of transportation fuels with ultra-low carbon intensities, which command price premiums in the growing set of constrained fuels markets such as California's LCFS. We are a Calgary based startup founded in 2009 with 10 employees, and we are considered a global leader in the direct air capture (DAC) field. We will review CE's DAC technology, based on a wet-scrubbing "air contactor" which absorbs CO2 into aqueous solution, and a chemical looping "regeneration" component, which liberates pure CO2 from this aqueous solution while re-making the original absorption chemical. CE's DAC tecnology exports purified atmospheric CO2, combined with the combustion CO2 from plant energy usage, as the end product. We will also discuss CE's 2014-2015 end-to-end Pilot Demonstration Unit. This is a $7M technology demonstration plant that CE is building with the help of key industrial partners and equipment vendors. Vendor design and engineering requirements have been used to specify the pilot air contactor, pellet reactor, calciner, and slaker modules, as well as auxiliary systems. These modules will be run for several months to obtain the engineering and performance data needed for subsequent commercial plant design, as well as to test the residual integration risks associated with CE's process. By the time of the AGU conference, the pilot is expected to be in late stages of fabrication or early stages of site installation.

  2. Effects of nitrate fertilization on CO2 and CH4 concentrations in small boreal lakes

    NASA Astrophysics Data System (ADS)

    Klaus, Marcus; Bergström, Ann-Kristin; Karlsson, Jan

    2013-04-01

    Ecosystem functioning in boreal lakes is largely affected by atmospheric nitrogen loading enhanced by anthropogenic activities. Additional deposition of nitrate entering these systems affects pelagic metabolic processes and thus the production and consumption of aquatic greenhouse gases. This study assesses the effect of nitrate fertilization on concentrations of dissolved carbon dioxide (CO2) and methane (CH4) in six small lakes in northern Sweden (area: 1.0-4.8 ha, max. depth: 4.5-8.5 m) with three different levels of dissolved organic carbon (DOC) concentrations (clear lakes: 7 mg l-1, medium brown lakes: 13 mg l-1, dark brown lakes: 18 mg l-1). A whole lake fertilization experiment was carried out utilizing a Before-After-Control-Impact (BACI) design with one reference year (2011) and one impact year (2012); including one control lake and one impact lake for each DOC level. During 2012, the impact lakes were fertilized with potassium nitrate once in March and biweekly from June to September. Fertilization caused epilimnion total nitrogen concentration to increase by around 10% in the impact lakes relative to the reference year while it decreased by around 20% in the control lakes. From June to September, epilimnion water was sampled biweekly by grab sampling and analyzed in the field by an infrared gas analyzer or in the laboratory using a gas chromatographer. Three additional samples were taken along a depth profile on three occasions. In the reference year, concentrations of CO2 and CH4 did not differ significantly between control and impact lakes (p>0.05). In the impact year, epilimnion CO2 concentrations were significantly higher compared to the reference year in all medium and dark brown lakes. Fertilization mostly caused a slight reduction in CO2 and CH4 concentrations in the impact lakes relative to the control lakes. This effect was not significant but most pronounced and coherent across the whole water column in clear lakes. In clear lakes, CO2 and CH4

  3. 40 CFR 86.1867-12 - CO2 credits for reducing leakage of air conditioning refrigerant.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... VEHICLES AND ENGINES General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles § 86.1867-12 CO2 credits... passenger automobiles and/or light trucks. Credits shall be calculated according to this section for...

  4. AIRS CO2 Retrievals Using the Method of Vanishing Partial Derivatives (VPD)

    NASA Technical Reports Server (NTRS)

    Chahine, Moustafa; Yung, Yuk; Li, Qinbin; Olsen, Ed; Chen, Luke; Krakauer, Nir

    2006-01-01

    This document consists of presentation slides that review the work being done with observations from the Atmospheric Infrared Sounder (AIRS) using the concept of Vanishing Partial Derivatives. The infrared region is where several minor gases such as CO2, O3, CO, CH4 and SO2 are radiatively active.

  5. Cost Effective Measures to Reduce CO2 Emissions in the Air Freight Sector

    NASA Technical Reports Server (NTRS)

    Blinge, Magnus

    2003-01-01

    This paper presents cost effective measures to reduce CO2 emissions in the air freight sector. One door-to-door transport chain is studied in detail from a Scandinavian city to a city in southern Europe. The transport chain was selected by a group of representatives from the air freight sector in order to encompass general characteristics within the sector. Three different ways of shipping air cargo are studied, i.e., by air freighter, as belly freight (in passenger aircrafts) and trucking. CO2 emissions are calculated for each part of the transport chain and its relative importance towards the total amount CO2 emitted during the whole transport chain is shown. It is confirmed that the most CO2 emitting part of the transport chain is the actual flight and that it is in the take-off and climbing phases that most fuel are burned. It is also known that the technical development of aircraft implies a reduction in fuel consumption for each new generation of aircraft. Thus, the aircraft manufacturers have an important role in this development. Having confirmed these observations, this paper focuses on other factors that significantly affects the fuel consumption. Analyzed factors are, e.g., optimization of speed and altitude, traffic management, congestion on and around the airfields, tankering, "latest acceptance time" for goods and improving the load factor. The different factors relative contribution to the total emission levels for the transport chain has been estimated.

  6. Net carbon storage in a poplar plantation (POPFACE) after three years of free-air CO2 enrichment.

    PubMed

    Gielen, B; Calfapietra, C; Lukac, M; Wittig, V E; De Angelis, P; Janssens, I A; Moscatelli, M C; Grego, S; Cotrufo, M F; Godbold, D L; Hoosbeek, M R; Long, S P; Miglietta, F; Polle, A; Bernacchi, C J; Davey, P A; Ceulemans, R; Scarascia-Mugnozza, G E

    2005-11-01

    A high-density plantation of three genotypes of Populus was exposed to an elevated concentration of carbon dioxide ([CO(2)]; 550 micromol mol(-1)) from planting through canopy closure using a free-air CO(2) enrichment (FACE) technique. The FACE treatment stimulated gross primary productivity by 22 and 11% in the second and third years, respectively. Partitioning of extra carbon (C) among C pools of different turnover rates is of critical interest; thus, we calculated net ecosystem productivity (NEP) to determine whether elevated atmospheric [CO(2)] will enhance net plantation C storage capacity. Free-air CO(2) enrichment increased net primary productivity (NPP) of all genotypes by 21% in the second year and by 26% in the third year, mainly because of an increase in the size of C pools with relatively slow turnover rates (i.e., wood). In all genotypes in the FACE treatment, more new soil C was added to the total soil C pool compared with the control treatment. However, more old soil C loss was observed in the FACE treatment compared with the control treatment, possibly due to a priming effect from newly incorporated root litter. FACE did not significantly increase NEP, probably as a result of this priming effect. PMID:16105807

  7. A Possible CO2 Conducting and Concentrating Mechanism in Plant Stomata SLAC1 Channel

    PubMed Central

    Du, Qi-Shi; Fan, Xina-Wei; Wang, Cheng-Hua; Huang, Ri-Bo

    2011-01-01

    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 CO2 and HCO3– 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 CO2 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 pKa values of ionizable amino acid side chains in AtSLAC1 are calculated using software PROPKA3.0, and the concentration of CO2 and anion HCO3– 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 CO2 concentration is enhanced around 104 times by the pH difference between these regions, and CO2 is stored in the hydrophobic region, which is a CO2 pool. The pH driven CO2 conduction from outside to inside balances the back electromotive force and maintain the influx of anions (e.g. Cl– and NO3–) from inside to outside. SLAC1 may be a pathway providing CO2 for photosynthesis in the guard cells. PMID:21931667

  8. A statistical analysis of three ensembles of crop model responses to temperature and CO2 concentration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ensembles of process-based crop models are now commonly used to simulate crop growth and development for climate scenarios of temperature and/or precipitation changes corresponding to different projections of atmospheric CO2 concentrations. This approach generates large datasets with thousands of de...

  9. Rising atmospheric CO2 lowers food zinc, iron, and protein concentrations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dietary deficiencies of zinc and iron are a major global public health problem. Most people who experience these deficiencies depend on agricultural crops for zinc and iron. In this context, the influence of rising concentrations of atmospheric CO2 on the availability of these nutrients from crops i...

  10. [Effects of elevated CO2 concentration on physiological characters of three dwarf ornamental bamboo species].

    PubMed

    Zhuang, Ming-Hao; Chen, Shuang-Lin; Li, Ying-Chun; Guo, Zi-Wu; Yang, Qing-Ping

    2013-09-01

    By using open-top chambers (OTCs) to simulate the scenes of elevated CO2 concentrations [500 micromol x mol(-1) (T1) and 700 micromol x mol(-1) (T2)], and taking ambient atmospheric CO2 concentration as the control (CK), this paper studied the effects of elevated CO2 concentration on the lipid peroxidation and anti-oxidation enzyme system in Indocalamus decorus, Pleioblastus kongosanensis, and Sasa glabra leaves. After 103 days treatment, the O2(-)* and MDA contents, relative electron conduction, and soluble sugar content in the three dwarf ornamental bamboo species leaves in T1 had no obvious change, but the activities of anti-oxidation enzymes (SOD, POD, CAT, and APX) changed to a certain extent. In T2, the MDA content and relative electron conduction had no obvious change, but the O2(-)* and soluble sugar contents and the anti-oxidation enzymes activities changed obviously. The adaptation capacity of the three bamboo species to elevated CO2 concentration was in the order of I. decorus > P. kongosanensis > S. glabra. PMID:24417095

  11. Tillage and wind effects on soil CO2 concentrations in muck soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rising atmospheric carbon dioxide (CO2 ) concentrations from agricultural activities has prompted the need to quantify greenhouse gas emissions to better understand carbon (C ) cycling and its role in environmental quality. The specific objective of this work was to determine the effect of no-tillag...

  12. Belowground grassland herbivores are resistant to elevated atmospheric CO2 concentrations in grassland ecosystems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grasslands are considered to be one of the most sensitive ecosystems to rising atmospheric CO2 concentrations. Moreover, grasslands support large populations of belowground herbivores that consume a major portion of plant biomass. The direct trophic link between herbivores and plants suggests that...

  13. Effect of dissolved inorganic carbon on oxygen evolution and uptake by Chlamydomonas reinhardtii suspensions adapted to ambient and CO2-enriched air.

    PubMed

    Sültemeyer, D F; Klug, K; Fock, H P

    1987-01-01

    Mass spectrometric measurements of (16)O2 and (18)O2 isotopes were used to compare the rates of gross O2 evolution (E0), O2 uptake (U0) and net O2 evolution (NET) in relation to different concentrations of dissolved inorganic carbon (DIC) by Chlamydomonas reinhardtii cells grown in air (air-grown), in air enriched with 5% CO2 (CO2-grown) and by cells grown in 5% CO2 and then adapted to air for 6h (air-adapted).At a photon fluence rate (PFR) saturating for photosynthesis (700 μmol photons m(-2) s(-1)), pH=7.0 and 28°C, U0 equalled E0 at the DIC compensation point which was 10μM DIC for CO2-grown and zero for air-grown cells. Both E0 and U0 were strongly dependent on DIC and reached DIC saturation at 480 μM and 70 μM for CO2-grown and air-grown algae respectively. U0 increased from DIC compensation to DIC saturation. The U0 values were about 40 (CO2-grown), 165 (air-adapted) and 60 μmol O2 mg Chl(-1) h(-1) (air-grown). Above DIC compensation the U0/E0 ratios of air-adapted and air-grown algae were always higher than those of CO2-grown cells. These differences in O2 exchange between CO2- and air-grown algae seem to be inducable since air-adapted algae respond similarly to air-grown cells.For all algae, the rates of dark respiratory O2 uptake measured 5 min after darkening were considerably lower than the rates of O2 uptake just before darkening. The contribution of dark respiration, photorespiration and the Mehler reaction to U0 is discussed and the energy requirement of the inducable CO2/HCO3 (-) concentrating mechanism present in air-adapted and air-grown C. reinhardtii cells is considered. PMID:24435578

  14. Increased nitrate availability in the soil of a mixed mature temperate forest subjected to elevated CO2 concentration (canopy FACE)

    NASA Astrophysics Data System (ADS)

    Schleppi, Patrick; Inga, Bucher-Wallin; Frank, Hagedorn; Christian, Körner

    2013-04-01

    In a mature temperate forest in Hofstetten, Switzerland, deciduous tree canopies were subjected to a free-air CO2 enrichment (FACE) for a period of eight years. The effect of this treatment on the availability of nitrogen (N) in the soil was assessed along three transects across the experimental area, one under Fagus sylvatica, one under Quercus robur and Q. petraea and one under Carpinus betulus. Nitrate, ammonium and dissolved organic N (DON) were analysed in soil solution obtained with suction cups. Nitrate and ammonium were also captured in buried ion-exchange resin bags. These parameters were related to the local intensity of the FACE treatment as measured from the 13C depletion of dissolved inorganic carbon in the soil solution, because the CO2 used for the treatment was depleted in 13C (Schleppi et al., 2012). Over the eight years of the experiment, the CO2 enrichment reduced DON concentrations, did not affect ammonium, but induced higher nitrate concentrations, both in soil solution and in resin bags. In the nitrate captured in the resin bags, the natural abundance of the isotope 15N strongly increased. This indicates that the CO2 enrichment accelerated net nitrification, probably as an effect of the higher soil moisture resulting from the reduced transpiration of the CO2-enriched trees. It is also possible that N mineralisation was enhanced by root exudates (priming effect) or that the uptake of inorganic N by these trees decreased slightly as the result of a reduced N demand for fine root growth. In this mature deciduous forest we did not observe any progressive N limitation due to elevated atmospheric CO2 concentrations; on the contrary, we observed an enhanced N availability over the eight years of our measurements. This may, together with the global warming projected, exacerbate problems related to N saturation and nitrate leaching, although it is uncertain how long the observed trends will last in the future. Following the experiment with deciduous

  15. Tracing changes of N2O emission pathways in a permanent grassland under elevated atmospheric CO2 concentrations

    NASA Astrophysics Data System (ADS)

    Gorenflo, Andre; Moser, Gerald; Brenzinger, Kristof; Elias, Dafydd; McNamara, Neill; Clough, Tim; Maček, Irena; Vodnik, Dominik; Braker, Gesche; Schimmelpfennig, Sonja; Gerstner, Judith; Müller, Christoph

    2015-04-01

    The increase of greenhouse gases (GHG) in the atmosphere is of concern due to its effect on global temperatures. Nitrous oxide (N2O) with a Global Warming Potential of 298 over a 100 year period is of particular concern because strong feedback effects of elevated atmospheric CO2 on N2O emissions have been observed. However, so far the changes in processes which are responsible for such a feedback effect are only poorly understood. Our study was carried out in situ in a long-term Free Air Carbon dioxide Enrichment (FACE) study on permanent grassland at atmospheric CO2 concentrations 20% above ambient which expected at the middle of this century. We performed an in situ 15N tracing with differentially labelled NH4NO3 to trace the main N2O emission pathways. Over a period of more than one year we monitored at least weakly the N2O emissions with the closed chamber technique and analyzed the 15N signature of the N2O. The observed gaseous emissions under ambient and elevated atmospheric CO2 were associated with the observed gross N transformations and the microbial activities to identify the main emission pathways under ambient and elevated CO2.

  16. Airborne Lidar Measurements of Atmospheric Column CO2 Concentration to Cloud Tops

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    Globally distributed atmospheric CO2 measurements with high precision, low bias and full seasonal sampling are crucial to advance carbon cycle sciences. However, two thirds of the Earth's surface is typically covered by clouds, and passive remote sensing approaches from space, e.g., OCO-2 and GOSAT, are limited to cloud-free scenes. They are unable to provide useful retrievals in cloudy areas where the photon path-length can't be well characterized. Thus, passive approaches have limited global coverage and poor sampling in cloudy regions, even though some cloudy regions have active carbon surface fluxes. NASA Goddard is developing a pulsed integrated-path, differential absorption (IPDA) lidar approach to measure atmospheric column CO2 concentrations from space as a candidate for NASA's ASCENDS mission. Measurements of time-resolved laser backscatter profiles from the atmosphere also allow this technique to estimate column CO2 and range to cloud tops in addition to those to the ground with precise knowledge of the photon path-length. This allows retrievals of column CO2 concentrations to cloud tops, providing much higher spatial coverage and some information about vertical structure of CO2. This is expected to benefit atmospheric transport process studies, carbon data assimilation in models, and global and regional carbon flux estimation. We show some preliminary results of the all-sky retrieval capability using airborne lidar measurements from the 2011, 2013 and 2014 ASCENDS airborne campaigns on the NASA DC-8. These show retrievals of atmospheric CO2 over low-level marine stratus clouds, cumulus clouds at the top of planetary boundary layer, some mid-level clouds and visually thin high-level cirrus clouds. The CO2 retrievals from the lidar are validated against in-situ measurements and compared to Goddard PCTM model simulations. Lidar cloud slicing to derive CO2 abundance in the planetary boundary layer and free troposphere also has been demonstrated. The

  17. Concentrated solar energy for thermochemically producing liquid fuels from CO2 and H2O

    NASA Astrophysics Data System (ADS)

    Loutzenhiser, Peter G.; Stamatiou, Anastasia; Villasmil, Willy; Meier, Anton; Steinfeld, Aldo

    2011-01-01

    A two-step solar thermochemical cycle for producing syngas from H2O and CO2 via Zn/ZnO redox reactions is considered. The first, endothermic step is the thermolysis of ZnO to Zn and O2 using concentrated solar radiation as the source of process heat. The second, non-solar, exothermic step is the reaction of Zn with mixtures of H2O and CO2 yielding high-quality syngas (mainly H2 and CO) and ZnO; the latter is recycled to the first solar step, resulting in net reactions CO2 = CO+0.5O2 and H2O= H2 +0.5O2. Syngas is further processed to liquid fuels via Fischer-Tropsch or other catalytic reforming processes. State-of-the-art reactor technologies and experimental results are provided for both steps of the cycle.

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

    NASA Astrophysics Data System (ADS)

    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

  19. Quantifying the air quality-CO2 tradeoff potential for airports

    NASA Astrophysics Data System (ADS)

    Ashok, Akshay; Dedoussi, Irene C.; Yim, Steve H. L.; Balakrishnan, Hamsa; Barrett, Steven R. H.

    2014-12-01

    Aircraft movements on the airport surface are responsible for CO2 emissions that contribute to climate change and other emissions that affect air quality and human health. While the potential for optimizing aircraft surface movements to minimize CO2 emissions has been assessed, the implications of CO2 emissions minimization for air quality have not been quantified. In this paper, we identify conditions in which there is a tradeoff between CO2 emissions and population exposure to O3 and secondary PM2.5 - i.e. where decreasing fuel burn (which is directly proportional to CO2 emissions) results in increased exposure. Fuel burn and emissions are estimated as a function of thrust setting for five common gas turbine engines at 34 US airports. Regional air quality impacts, which are dominated by ozone and secondary PM2.5, are computed as a function of airport location and time using the adjoint of the GEOS-Chem chemistry-transport model. Tradeoffs between CO2 emissions and population exposure to PM2.5 and O3 occur between 2-18% and 5-60% of the year, respectively, depending on airport location, engine type, and thrust setting. The total duration of tradeoff conditions is 5-12 times longer at maximum thrust operations (typical for takeoff) relative to 4% thrust operations (typical for taxiing). Per kilogram of additional fuel burn at constant thrust setting during tradeoff conditions, reductions in population exposure to PM2.5 and O3 are 6-13% and 32-1060% of the annual average (positive) population exposure per kilogram fuel burn, where the ranges encompass the medians over the 34 airports. For fuel burn increases due to thrust increases (i.e. for constant operating time), reductions in both PM2.5 and O3 exposure are 1.5-6.4 times larger in magnitude than those due to increasing fuel burn at constant thrust (i.e. increasing operating time). Airports with relatively high population exposure reduction potentials - which occur due to a combination of high duration and

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

    PubMed Central

    Haworth, Matthew; Hoshika, Yasutomo; Killi, Dilek

    2016-01-01

    Meta-analysis is extensively used to synthesize the results of free air CO2 enrichment (FACE) studies to produce an average effect size, which is then used to model likely plant response to rising [CO2]. The efficacy of meta-analysis is reliant upon the use of data that characterizes the range of responses to a given factor. Previous meta-analyses of the effect of FACE on plants have not incorporated the potential impact of reporting bias in skewing data. By replicating the methodology of these meta-analytic studies, we demonstrate that meta-analysis of FACE has likely exaggerated the effect size of elevated [CO2] on plants by 20 to 40%; having significant implications for predictions of food security and vegetation response to climate change. Incorporation of the impact of reporting bias did not affect the significance or the direction of the [CO2] effect. PMID:27536310

  1. The effects of free-air CO2 enrichment (FACE) on carbon and nitrogen accumulation in grains of rice (Oryza sativa L.)

    PubMed Central

    Zhu, Chunwu; Hasegawa, Toshihiro

    2013-01-01

    Rising atmospheric CO2 concentrations will probably increase rice (Oryza sativa L.) yield but decrease grain nitrogen (GN) concentration. Grains attached to different positions in the panicles differ greatly in weight and quality, but their responses to elevated CO2 (e[CO2]) are poorly understood, which limits our understanding of the mechanisms of yield enhancement and quality degradation. Thus a free-air CO2 enrichment experiment was conducted to examine the effects of e[CO2] on grain mass (GM), grain carbon (GC), and GN accumulation in the spikelets attached to the upper primary rachis branch (superior spikelets; SS) and those attached to the lower secondary rachis (inferior spikelets; IS). e[CO2] stimulated the rice yield by 13% but decreased the N concentration in the panicle by 7% when averaged over two levels of N fertilizations (P < 0.01). The responses of SS and IS to e[CO2] were different particularly under higher N supply. For SS, e[CO2] decreased GN by 24% (P < 0.01) but did not affect GM. For IS, e[CO2] increased GM by 13% (P < 0.05) but GN was not affected. The reduction of GN due to e[CO2] started to appear at the beginning of grain filling. These results suggest that future [CO2] levels probably stimulate the grain growth of IS, most of which are not marketable due to limited size, at the expense of GN reduction in SS. Translocation of N from SS to IS may be a possible mechanism for reduction in GN of SS. This may degrade the grain quality of marketable rice under e[CO2]. PMID:23918962

  2. Air-Sea Exchange Of CO2: A Multi-Technology Approach

    NASA Astrophysics Data System (ADS)

    Tengberg, A.; Almroth, E.; Anderson, L.; Hall, P.; Hjalmarsson, S.; Lefevre, D.; Omstedt, A.; Rutgersson, A.; Sahlee, E.; Smedman, A.; Wesslander, K.

    2006-12-01

    We report on experiences and results from a multidisciplinary project in which we try to elucidate the complex processes involved in air-sea exchange of CO2. This study was performed in the Baltic Sea (off the Swedish island Gotland) and combined the following technologies: - Meteorological measurements of wind, turbulence, temperature, humidity, humidity flux, CO2 and CO2 flux at several levels from a fixed observation tower - Hourly PCO2 measurements with a moored automatic instrument - Collection of dissolved oxygen, temperature, salinity and turbidity data at different levels in the water column at 1-minute intervals - Daily light (PAR) and primary production measurements obtained with a moored automatic incubator - Daily primary production measurements using manual methods - Use of an acoustic current profiler to collect water column information on currents, turbulence, water level and waves - Repetitive water column profiles, from a ship, of dissolved inorganic carbon, oxygen, nutrients, alkalinity, pH, PAR, Chlorophyll A, salinity and temperature

  3. CO2 Fixation, Lipid Production, and Power Generation by a Novel Air-Lift-Type Microbial Carbon Capture Cell System.

    PubMed

    Hu, Xia; Liu, Baojun; Zhou, Jiti; Jin, Ruofei; Qiao, Sen; Liu, Guangfei

    2015-09-01

    An air-lift-type microbial carbon capture cell (ALMCC) was constructed for the first time by using an air-lift-type photobioreactor as the cathode chamber. The performance of ALMCC in fixing high concentration of CO2, producing energy (power and biodiesel), and removing COD together with nutrients was investigated and compared with the traditional microbial carbon capture cell (MCC) and air-lift-type photobioreactor (ALP). The ALMCC system produced a maximum power density of 972.5 mW·m(-3) and removed 86.69% of COD, 70.52% of ammonium nitrogen, and 69.24% of phosphorus, which indicate that ALMCC performed better than MCC in terms of power generation and wastewater treatment efficiency. Besides, ALMCC demonstrated 9.98- and 1.88-fold increases over ALP and MCC in the CO2 fixation rate, respectively. Similarly, the ALMCC significantly presented a higher lipid productivity compared to those control reactors. More importantly, the preliminary analysis of energy balance suggested that the net energy of the ALMCC system was significantly superior to other systems and could theoretically produce enough energy to cover its consumption. In this work, the established ALMCC system simultaneously achieved the high level of CO2 fixation, energy recycle, and municipal wastewater treatment effectively and efficiently. PMID:26270956

  4. Automated CO2 extraction from air for clumped isotope analysis in the atmo- and biosphere

    NASA Astrophysics Data System (ADS)

    Hofmann, Magdalena; Ziegler, Martin; Pons, Thijs; Lourens, Lucas; Röckmann, Thomas

    2015-04-01

    The conventional stable isotope ratios 13C/12C and 18O/16O in atmospheric CO2 are a powerful tool for unraveling the global carbon cycle. In recent years, it has been suggested that the abundance of the very rare isotopologue 13C18O16O on m/z 47 might be a promising tracer to complement conventional stable isotope analysis of atmospheric CO2 [Affek and Eiler, 2006; Affek et al. 2007; Eiler and Schauble, 2004; Yeung et al., 2009]. Here we present an automated analytical system that is designed for clumped isotope analysis of atmo- and biospheric CO2. The carbon dioxide gas is quantitatively extracted from about 1.5L of air (ATP). The automated stainless steel extraction and purification line consists of three main components: (i) a drying unit (a magnesium perchlorate unit and a cryogenic water trap), (ii) two CO2 traps cooled with liquid nitrogen [Werner et al., 2001] and (iii) a GC column packed with Porapak Q that can be cooled with liquid nitrogen to -30°C during purification and heated up to 230°C in-between two extraction runs. After CO2 extraction and purification, the CO2 is automatically transferred to the mass spectrometer. Mass spectrometric analysis of the 13C18O16O abundance is carried out in dual inlet mode on a MAT 253 mass spectrometer. Each analysis generally consists of 80 change-over-cycles. Three additional Faraday cups were added to the mass spectrometer for simultaneous analysis of the mass-to-charge ratios 44, 45, 46, 47, 48 and 49. The reproducibility for δ13C, δ18O and Δ47 for repeated CO2 extractions from air is in the range of 0.11o (SD), 0.18o (SD) and 0.02 (SD)o respectively. This automated CO2 extraction and purification system will be used to analyse the clumped isotopic signature in atmospheric CO2 (tall tower, Cabauw, Netherlands) and to study the clumped isotopic fractionation during photosynthesis (leaf chamber experiments) and soil respiration. References Affek, H. P., Xu, X. & Eiler, J. M., Geochim. Cosmochim. Acta 71, 5033

  5. Extraction of CO2 from air samples for isotopic analysis and limits to ultra high precision delta18O determination in CO2 gas.

    PubMed

    Werner, R A; Rothe, M; Brand, W A

    2001-01-01

    The determination of delta18O values in CO2 at a precision level of +/-0.02 per thousand (delta-notation) has always been a challenging, if not impossible, analytical task. Here, we demonstrate that beyond the usually assumed major cause of uncertainty - water contamination - there are other, hitherto underestimated sources of contamination and processes which can alter the oxygen isotope composition of CO2. Active surfaces in the preparation line with which CO2 comes into contact, as well as traces of air in the sample, can alter the apparent delta18O value both temporarily and permanently. We investigated the effects of different surface materials including electropolished stainless steel, Duran glass, gold and quartz, the latter both untreated and silanized. CO2 frozen with liquid nitrogen showed a transient alteration of the 18O/16O ratio on all surfaces tested. The time to recover from the alteration as well as the size of the alteration varied with surface type. Quartz that had been ultrasonically cleaned for several hours with high purity water (0.05 microS) exhibited the smallest effect on the measured oxygen isotopic composition of CO2 before and after freezing. However, quartz proved to be mechanically unstable with time when subjected to repeated large temperature changes during operation. After several days of operation the gas released from the freezing step contained progressively increasing trace amounts of O2 probably originating from inclusions within the quartz, which precludes the use of quartz for cryogenically trapping CO2. Stainless steel or gold proved to be suitable materials after proper pre-treatment. To ensure a high trapping efficiency of CO2 from a flow of gas, a cold trap design was chosen comprising a thin wall 1/4" outer tube and a 1/8" inner tube, made respectively from electropolished stainless steel and gold. Due to a considerable 18O specific isotope effect during the release of CO2 from the cold surface, the thawing time had to

  6. [Study on the change of dune CO2 concentration in the autumn at Minqin in Tengger desert].

    PubMed

    Shao, Tian-Jie; Zhao, Jing-Bo; Yu, Ke-Ke; Dong, Zhi-Bao

    2010-12-01

    In order to find out the CO2 concentration of the desert area, the influence of it on the CO2 in the atmosphere and the role that it played on the global carbon cycle, the research team utilized in September 2009 infrared CO2 monitor to observe the CO2 concentration of the 12 drill holes day and night in Minqin desert area in the Tengger desert. The difference of various observation spots' CO2 concentration of the desert area in the Tengger desert area is relatively big. The CO2 concentration at night is low but high in the daytime and the CO2 concentration at each observation spot changes from 310 x 10(-6) to 2 630 x 10(-6). The CO2 concentration is also obviously different in depth and the CO2 concentration at different depths in order of size is as follows: 4 m(3m) > 2 m > 1m. Compared with Xi' an area where is in the temperate and semi-humid region, the CO2 concentration of the desert area in Tengger desert is very low. The diurnal variation of CO2 concentration of the desert area in Tengger desert is obvious, and from the day 09:00 am to 09:00 am the next day, the CO2 concentrations at different depths which rang from 1 m to 4 m present the regularity that it changes from low to high, and then from high to low. The diurnal variation in temperature is the main reason that causes the change of the CO2 concentration in the sand layer, both of which have the positive correlation. The sand layer's CO2 concentration with higher water content is obviously higher than that with lower water content. The moisture content of sand layer is the main factor of the CO2 concentration. The CO2 concentration above 4m in the desert area is higher than that above the surface, which maybe indicates that the CO2 from the highest desert area is also the resource of CO2 in the atmosphere. PMID:21360892

  7. Spatial and temporal performance of the miniface (free air CO2 enrichment) system on Bog Ecosystems in northern and Central Europe.

    PubMed

    Miglietta, F; Hoosbeek, M R; Foot, J; Gigon, F; Hassinen, A; Heijmans, M; Peressotti, A; Saarinen, T; Van Breemen, N; Wallén, B

    2001-01-01

    The Bog Ecosystem Research Initiative (BERI) project was initiated to investigate, at five climatically different sites across Europe, the effects of elevated CO2 and N deposition on the net exchange of CO2 and CH4 between bogs and the atmosphere, and to study the effects of elevated CO2 and N deposition on the plant biodiversity of bog communities. A major challenge to investigate the effects of elevated CO2 on vegetation and ecosystems is to apply elevated CO2 concentrations to growing vegetation without changing the physical conditions like climate and radiation. Most available CO2 enrichment methods disturb the natural conditions to some degree, for instance closed chambers or open top chambers. Free Air CO2 Enrichment (FACE) systems have proven to be suitable to expose plants to elevated CO2 concentrations with minimal disturbance of their natural environment. The size and spatial scale of the vegetation studied within the BERI project allowed the use of a modified version of a small FACE system called MiniFACE. This paper describes the BERI MiniFACE design as well as its temporal and spatial performance at the five BERI field locations. The temporal performance of the MiniFACE system largely met the quality criteria defined by the FACE Protocol. One minute average CO2 concentrations measured at the centre of the ring stayed within 20% of the pre-set target for more than 95% of the time. Increased wind speeds were found to improve the MiniFACE system's temporal performance. Spatial analyses showed no apparent CO2 gradients across a ring during a 4 day period and the mean differences between each sampling point and the centre of the ring did not exceed 10%. Observations made during a windy day, causing a CO2 concentration gradient, and observations made during a calm day indicated that short term gradients tend to average out over longer periods of time. On a day with unidirectional strong winds, CO2 concentrations at the upwind side of the ring centre were

  8. Technique development for estimation of CO2 and CH4 concentration using radiative transfer modeling

    NASA Astrophysics Data System (ADS)

    Prasad, Prabhunath; Rastogi, Shantanu; Singh, Rp; Panigrahy, S.

    2012-07-01

    Atmospheric carbon dioxide (CO _{2}) and methane (CH _{4}) are the well-known green house gases. Accurate spatially and temporally continuous estimation of these gases is essential for many environmental studies. Satellite observations provide important input in global monitoring of green house gases, and the area of scientific research which can help to reduce the uncertainty in measurement of trace gas concentration evolved rapidly. Spectral techniques are used to derive GHG concentration by developing the relation between satellite derived differential absorption indices with gaseous concentration. In the present work spectra were simulated to study the effect of different CO _{2} and CH _{4} concentration for estimation of atmospheric transmittances in the near infrared spectral region. Forward simulation was carried out using GUI based PcLnWin3.1 model. It uses calculations made by the FASCODE using HITRAN, molecular spectroscopic databases. It was found that for study of CO _{2} suitable spectral window is the 1.6 μm (6250 cm ^{-1}) band where there are two prominent absorptions at 1.576 μm (6348 cm ^{-1}) due to 2v _{1}+2v _{2}+v _{3} and 1.606 μm (6228 cm ^{-1}) due to v _{1}+4v _{2}+v _{3}. Of these 1.606 μm is dominant and more suitable. The suitable CH _{4} spectral window is 1.666 μm where although most of the P branch dissolves in water absorption but Q and R bands are sensitive and not affected by any other absorption. Optimum spectral resolution for correct determination of gas concentrations was found. It was observed from that the resolving power about 8000 (Δ λ ˜ 0.2 nm) is needed for detection of atmospheric CO _{2} and CH _{4} concentration at the 1.60 μm and 1.66 μm spectral region respectively.

  9. Mid-stratospheric measurements of CO2, CH4, and CO using AirCore

    NASA Astrophysics Data System (ADS)

    Chen, H.; Karion, A.; Newberger, T.; Sweeney, C.; Andrews, A. E.; Tans, P. P.

    2011-12-01

    AirCore, a long tube descending from a high altitude with one end open and the other closed, has been demonstrated to be a reliable, cost-effective sampling system for CO2 and CH4 measurements. Previous studies show that vertical profiles from the ground level up to ~ 20 km (~ 40 mbar) can be achieved during a balloon flight. The ceiling of the profile is restricted mainly by the diffusion of air in the AirCore and the resolution of the analyzer used for the analysis. Here air with an extremely high CO mixing ratio (~ 10 ppm) has been employed as the initial fill air in the AirCore. This high CO fill gas is used as a label to track the mixing between sampled air and fill air at the top of the profile thus providing the ability to retrieve full profiles for CO2 and CH4 up to the balloon's ceiling height of ~ 30 km (~ 11 mbar). Stratospheric measurements of CO lack agreement among previous studies, (i.e. cryogenic sampling, in-situ measurements, and remote sensing) due to difficulties that are inherent to the various techniques and possibly due to latitudinal and seasonal variations that could not be represented by the available sparse observations. Efforts to collect an accurate profile of stratospheric CO using the AirCore, are complicated by the reaction of CO and O3 in the coil, which is particular important for stratospheric air with high O3. To remove the influence of O3 on the CO measurements from AirCore, we have investigated three O3 scrubbers: 1) Manganese dioxide (MnO2); 2) Sodium Sulfite (Na2SO3); 3) Sodium thiosulfate (Na2S2O3). Laboratory tests reveal that Sodium thiosulfate is the best choice as it has sufficient capacity to absorb O3 and does not impact measurements of CO2 and CH4. We will show experimental results from both aircraft and balloon flights. Regular ongoing stratospheric profiles of CO2, CH4, and CO are necessary to improve and validate total column measurements by remote sensing techniques, such as FTS and satellite. Such measurements

  10. Co-location of air capture, subseafloor CO2 sequestration, and energy production on the Kerguelen plateau.

    PubMed

    Goldberg, David S; Lackner, Klaus S; Han, Patrick; Slagle, Angela L; Wang, Tao

    2013-07-01

    Reducing atmospheric CO2 using a combination of air capture and offshore geological storage can address technical and policy concerns with climate mitigation. Because CO2 mixes rapidly in the atmosphere, air capture could operate anywhere and in principle reduce CO2 to preindustrial levels. We investigate the Kerguelen plateau in the Indian Ocean, which offers steady wind resources, vast subseafloor storage capacities, and minimal risk of economic damages or human inconvenience and harm. The efficiency of humidity swing driven air capture under humid and windy conditions is tested in the laboratory. Powered by wind, we estimate ∼75 Mt CO2/yr could be collected using air capture and sequestered below seafloor or partially used for synfuel. Our analysis suggests that Kerguelen offers a remote and environmentally secure location for CO2 sequestration using renewable energy. Regional reservoirs could hold over 1500 Gt CO2, sequestering a large fraction of 21st century emissions. PMID:23745611

  11. Effects of atmospheric CO2 enrichment on the growth and development of Hymenocallis littoralis (Amaryllidaceae) and the concentrations of several antineoplastic and antiviral constituents of its bulbs.

    PubMed

    Idso, S B; Kimball, B A; Pettit Iii, G R; Garner, L C; Pettit, G R; Backhaus, R A

    2000-06-01

    Two 2-yr crops of tropical spider lily (Hymenocallis littoralis) plants were grown in field soil in clear-plastic-wall open-top enclosures in the Sonoran Desert environment of central Arizona. Half of the plants were exposed to ambient air of 400 ppm atmospheric CO(2) concentration and half of them were exposed to air of 700 ppm CO(2). This 75% increase in the air's CO(2) content resulted in a 48% increase in aboveground plant biomass and a 56% increase in belowground (bulb) biomass. It also increased the concentrations of five bulb constituents that have been demonstrated to possess anticancer and antiviral activities. Mean percentage increases in these concentrations were 6% for a two-constituent (1:1) mixture of 7-deoxynarciclasine and 7-deoxy-trans-dihydronarciclasine, 8% for pancratistatin, 8% for trans-dihydronarciclasine, and 28% for narciclasine, for a mean active ingredient percentage concentration increase of 12%. Combined with the 56% increase in bulb biomass, these percentage concentration increases resulted in a mean active ingredient increase of 75% for the 75% increase in the air's CO(2) concentration used in our experiments. PMID:10860907

  12. Ocean Carbon Cycling and CO2 Air-Sea Exchange in Eastern Boundary Upwelling Systems

    NASA Astrophysics Data System (ADS)

    Plattner, G.; Gruber, N.; Lachkar, Z.; Frenzel, H.; Loher, D.

    2008-12-01

    Eastern boundary current (EBC) upwelling systems are regions of intense biogeochemical transformations and transports. Strong upwelling of nutrient- and carbon-rich waters tends to lead to CO2 outgassing nearshore and biologically-driven CO2 uptake offshore. Yet, the net air-sea CO2 balance of EBCs remains unknown. High near-shore productivity coupled with filaments and other meso- and submesoscale phenomena cause a substantial lateral export of organic carbon. We investigate these coastal processes in the California Current (CalCS) and the Canary Current Systems (CanCS), on the basis of the eddy-resolving, physical-biogeochemical model ROMS. Our results confirm the onshore-offshore trends in the air-sea fluxes, with substantial spatial and temporal differences due to topography, upwelling strength, and eddy activity. The CalCS is modeled to be, on average, a very small source of CO2 to the atmosphere, consistent with a recent data-based estimate by Chavez and Takahashi, while for the CanCS this is not clear yet. Regarding offshore transport, the CalCS appears to be stronger than the CanCS. Spatio-temporal variability of all carbon fluxes is substantial, particularly nearshore, posing a tremendous challenge for observing systems targeting e.g. air-sea CO2 fluxes in these dynamic regions. Further analyses of the processes that determine the mean carbon fluxes and their spatio-temporal variability will be presented. Characteristic differences and similarities between the two EBC systems will be discussed.

  13. Dynamics of air-sea CO2 fluxes based on FerryBox measurements and satellite-based prediction of pCO2 in the Western English Channel

    NASA Astrophysics Data System (ADS)

    Marrec, Pierre; Thierry, Cariou; Eric, Mace; Pascal, Morin; Marc, Vernet; Yann, Bozec

    2014-05-01

    Since April 2012, we installed an autonomous FerryBox system on a Voluntary Observing Ship (VOS), which crosses the Western English Channel (WEC) between Roscoff and Plymouth on a daily basis. High-frequency data of sea surface temperature (SST), salinity (SSS), fluorescence, dissolved oxygen (DO) and partial pressure of CO2 (pCO2) were recorded for two years across the all-year mixed southern WEC (sWEC) and the seasonally stratified northern WEC (nWEC). These contrasting hydrographical provinces strongly influenced the spatio-temporal distributions of pCO2 and air-sea CO2 fluxes. During the productive period (from May to September), the nWEC acted as a sink for atmospheric CO2 of -5.6 mmolC m-2 d-1 and -4.6 mmolC m-2 d-1, in 2012 and 2013, respectively. During the same period, the sWEC showed significant inter-annual variability degassing CO2 to the atmosphere in 2012 (1.4 mmolC m-2 d-1) and absorbing atmospheric CO2 in 2013 (-1.6 mmolC m-2 d-1). In 2012, high-frequency data revealed that an intense and short (less than 10 days) summer phytoplankton bloom in the nWEC contributed to 31% of the total CO2 drawdown during the productive period, highlighting the necessity of pCO2 high-frequency measurements in coastal ecosystems. Based on this multi-annual dataset, we developed pCO2 algorithms using multiple linear regression (MLR) based on SST, SSS, chlorophyll-a (Chl-a) concentration, time, latitude and mixed layer depth to predict pCO2 in the two hydrographical provinces of the WEC. MLR were performed based on more than 200,000 underway observations spanning the range from 150 to 480 µatm. The root mean square errors (RMSE) of the MLR fit to the data were 17.2 µatm and 21.5 µatm for the s WEC and the nWEC with correlation coefficient (r²) of 0.71 and 0.79, respectively. We applied these algorithms to satellite SST and Chl-a products and to modeled SSS estimates in the entire WEC. Based on these high-frequency and satellite approaches, we will discuss the main

  14. Diel Variation in Gene Expression of the CO2-Concentrating Mechanism during a Harmful Cyanobacterial Bloom.

    PubMed

    Sandrini, Giovanni; Tann, Robert P; Schuurmans, J Merijn; van Beusekom, Sebastiaan A M; Matthijs, Hans C P; Huisman, Jef

    2016-01-01

    Dense phytoplankton blooms in eutrophic waters often experience large daily fluctuations in environmental conditions. We investigated how this diel variation affects in situ gene expression of the CO2-concentrating mechanism (CCM) and other selected genes of the harmful cyanobacterium Microcystis aeruginosa. Photosynthetic activity of the cyanobacterial bloom depleted the dissolved CO2 concentration, raised pH to 10, and caused large diel fluctuations in the bicarbonate and O2 concentration. The Microcystis population consisted of three Ci uptake genotypes that differed in the presence of the low-affinity and high-affinity bicarbonate uptake genes bicA and sbtA. Expression of the bicarbonate uptake genes bicA, sbtA, and cmpA (encoding a subunit of the high-affinity bicarbonate uptake system BCT1), the CCM transcriptional regulator gene ccmR and the photoprotection gene flv4 increased at first daylight and was negatively correlated with the bicarbonate concentration. In contrast, genes of the two CO2 uptake systems were constitutively expressed, whereas expression of the RuBisCO chaperone gene rbcX, the carboxysome gene ccmM, and the photoprotection gene isiA was highest at night and down-regulated during daytime. In total, our results show that the harmful cyanobacterium Microcystis is very responsive to the large diel variations in carbon and light availability often encountered in dense cyanobacterial blooms. PMID:27148233

  15. Diel Variation in Gene Expression of the CO2-Concentrating Mechanism during a Harmful Cyanobacterial Bloom

    PubMed Central

    Sandrini, Giovanni; Tann, Robert P.; Schuurmans, J. Merijn; van Beusekom, Sebastiaan A. M.; Matthijs, Hans C. P.; Huisman, Jef

    2016-01-01

    Dense phytoplankton blooms in eutrophic waters often experience large daily fluctuations in environmental conditions. We investigated how this diel variation affects in situ gene expression of the CO2-concentrating mechanism (CCM) and other selected genes of the harmful cyanobacterium Microcystis aeruginosa. Photosynthetic activity of the cyanobacterial bloom depleted the dissolved CO2 concentration, raised pH to 10, and caused large diel fluctuations in the bicarbonate and O2 concentration. The Microcystis population consisted of three Ci uptake genotypes that differed in the presence of the low-affinity and high-affinity bicarbonate uptake genes bicA and sbtA. Expression of the bicarbonate uptake genes bicA, sbtA, and cmpA (encoding a subunit of the high-affinity bicarbonate uptake system BCT1), the CCM transcriptional regulator gene ccmR and the photoprotection gene flv4 increased at first daylight and was negatively correlated with the bicarbonate concentration. In contrast, genes of the two CO2 uptake systems were constitutively expressed, whereas expression of the RuBisCO chaperone gene rbcX, the carboxysome gene ccmM, and the photoprotection gene isiA was highest at night and down-regulated during daytime. In total, our results show that the harmful cyanobacterium Microcystis is very responsive to the large diel variations in carbon and light availability often encountered in dense cyanobacterial blooms. PMID:27148233

  16. Free Air CO2 Enrichment (FACE) Research Data from the Nevada Desert FACE Facility (NDFF)

    DOE Data Explorer

    DOE has conducted trace gas enrichment experiments since the mid 1990s. The FACE Data Management System is a central repository and archive for Free-Air Carbon Dioxide Enrichment (FACE) data, as well as for the related open-top chamber (OTC) experiments. FACE Data Management System is located at the Carbon Dioxide Information Analysis Center (CDIAC). While the data from the various FACE sites, each one a unique user facility, are centralized at CDIAC, each of the FACE sites presents its own view of its activities and information. For that reason, DOE Data Explorer users are advised to see both the central repository at http://public.ornl.gov/face/index.shtml and the individual home pages of each site. NDFF whole-ecosystem manipulation is a flagship experiment of the Terrestrial Carbon Process (TCP) research program of the US Dept. of Energy. It is also a core project of the International Geosphere-Biosphere Program (IGBP) and a contribution to the US Global Change Research Program. The NDFF was developed in conjunction with the National Science Foundation (NSF) and DOE-EPSCoR programs. FACE (Free-Air-Carbon dioxide-Enrichment) technology allows researchers to elevate the carbon dioxide level in large study plots while minimizing ecosystem disturbance. At the NDFF the concentration of CO2 was elevated by 50 percent above the present atmospheric levels in three plots in the Mojave Desert ecosystem, while six other plots remained at the current level. This experimental design provided a large area in which integrated teams of scientists could describe and quantify processes regulating carbon, nutrient, and water balances in desert ecosystems.

  17. Sea breeze forcing of estuary turbulence and air-water CO2 exchange

    NASA Astrophysics Data System (ADS)

    Orton, Philip M.; McGillis, Wade R.; Zappa, Christopher J.

    2010-07-01

    The sea breeze is often a dominant meteorological feature at the coastline, but little is known about its estuarine impacts. Measurements at an anchored catamaran and meteorological stations along the Hudson River and New York Bay estuarine system are used to illustrate some basic characteristics and impacts of the feature. The sea breeze propagates inland, arriving in phase with peak solar forcing at seaward stations, but several hours later at up-estuary stations. Passage of the sea breeze front raises the water-to-air CO2 flux by 1-2 orders of magnitude, and drives turbulence comparable to spring tide levels in the upper meter of the water column, where most primary productivity occurs in this highly turbid system. Modeling and observational studies often use remotely-measured winds to compute air-water fluxes (e.g., momentum, CO2), and this leads to a factor of two flux error on sea breeze days during the study.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. An approach for verifying biogenic greenhouse gas emissions inventories with atmospheric CO 2 concentration data

    DOE PAGESBeta

    Ogle, Stephen; Davis, Kenneth J.; Lauvaux, Thomas; Schuh, Andrew E.; Cooley, Dan; West, Tristram O.; Heath, L.; Miles, Natasha; Richardson, S. J.; Breidt, F. Jay; et al

    2015-03-10

    Verifying national greenhouse gas (GHG) emissions inventories is a critical step to ensure that reported emissions data to the United Nations Framework Convention on Climate Change (UNFCCC) are accurate and representative of a country’s contribution to GHG concentrations in the atmosphere. Verification could include a variety of evidence, but arguably the most convincing verification would be confirmation of a change in GHG concentrations in the atmosphere that is consistent with reported emissions to the UNFCCC. We report here on a case study evaluating this option based on a prototype atmospheric CO2 measurement network deployed in the Mid-Continent Region of themore » conterminous United States. We found that the atmospheric CO2 measurement data did verify the accuracy of the emissions inventory within the confidence limits of the emissions estimates, suggesting that this technology could be further developed and deployed more widely in the future for verifying reported emissions.« less

  20. Evaluation of Potential pH-Driven Metal Release Due to Elevated Groundwater CO2 Concentrations

    NASA Astrophysics Data System (ADS)

    Tinnacher, R. M.; Varadharajan, C.; Zheng, L.; Spycher, N.; Birkholzer, J. T.; Trautz, R. C.; Pugh, J. D.; Esposito, R.; Nico, P. S.

    2012-12-01

    The injection of carbon dioxide (CO2) emissions from industrial sources into deep geologic formations is a potential option for the control of CO2 concentrations in the atmosphere. While the risk of CO2 migration from the storage reservoir into potable groundwater is low considering the safeguards of site characterization and permitting, it is important to understand what type of potential impacts could occur and how to identify these impacts. Elevated CO2 concentrations may potentially lead to a decrease in groundwater pH and the subsequent release of metals and ions from natural sediments into the groundwater solution. In this risk scenario, potential metal release processes, such as enhanced mineral dissolution, metal desorption and/or ion exchange reactions, may be driven by changes in groundwater pH, the presence of carbonate ligands in solution or a combination of the two. However, a detailed understanding and a distinction of pH-driven and carbonate-driven metal release reactions are important for the development of site monitoring plans and remediation strategies, required by regulations in the unlikely event of a release. Hence, in this study we characterized metal release from natural sediments into synthetic groundwater solutions at two pH conditions in order to mimic the native groundwater pH (pH ~8.5) and the low pH conditions expected in the event of elevated CO2 concentrations (pH~5). In addition, results are compared between tests performed in the presence and absence of elevated CO2. Metal release was investigated in lab-scale sequential leaching experiments using two sediment types with different organic carbon contents over a time-frame of 25 days. Supernatant solutions were monitored for pH and characterized in terms of metal concentrations (ICP-MS), total inorganic carbon (TIC) and anion composition. Furthermore, experimental results were compared with data from a field study involving the controlled release of groundwater containing dissolved

  1. Physiological framework for adaptation of stomata to CO2 from glacial to future concentrations

    PubMed Central

    Franks, Peter J.; Leitch, Ilia J.; Ruszala, Elizabeth M.; Hetherington, Alistair M.; Beerling, David J.

    2012-01-01

    In response to short-term fluctuations in atmospheric CO2 concentration, ca, plants adjust leaf diffusive conductance to CO2, gc, via feedback regulation of stomatal aperture as part of a mechanism for optimizing CO2 uptake with respect to water loss. The operational range of this elaborate control mechanism is determined by the maximum diffusive conductance to CO2, gc(max), which is set by the size (S) and density (number per unit area, D) of stomata on the leaf surface. Here, we show that, in response to long-term exposure to elevated or subambient ca, plants alter gc(max) in the direction of the short-term feedback response of gc to ca via adjustment of S and D. This adaptive feedback response to ca, consistent with long-term optimization of leaf gas exchange, was observed in four species spanning a diverse taxonomic range (the lycophyte Selaginella uncinata, the fern Osmunda regalis and the angiosperms Commelina communis and Vicia faba). Furthermore, using direct observation as well as flow cytometry, we observed correlated increases in S, guard cell nucleus size and average apparent 1C DNA amount in epidermal cell nuclei with increasing ca, suggesting that stomatal and leaf adaptation to ca is linked to genome scaling. PMID:22232765

  2. A terrestrial biosphere model optimized to atmospheric CO2 concentration and above ground woody biomass

    NASA Astrophysics Data System (ADS)

    Saito, M.; Ito, A.; Maksyutov, S. S.

    2013-12-01

    This study documents an optimization of a prognostic biosphere model (VISIT; Vegetation Integrative Similator for Trace gases) to observations of atmospheric CO2 concentration and above ground woody biomass by using a Bayesian inversion method combined with an atmospheric tracer transport model (NIES-TM; National Institute for Environmental Studies / Frontier Research Center for Global Change (NIES/FRCGC) off-line global atmospheric tracer transport model). The assimilated observations include 74 station records of surface atmospheric CO2 concentration and aggregated grid data sets of above ground woody biomass (AGB) and net primary productivity (NPP) over the globe. Both the biosphere model and the atmospheric transport model are used at a horizontal resolution of 2.5 deg x 2.5 deg grid with temporal resolutions of a day and an hour, respectively. The atmospheric transport model simulates atmospheric CO2 concentration with nine vertical levels using daily net ecosystem CO2 exchange rate (NEE) from the biosphere model, oceanic CO2 flux, and fossil fuel emission inventory. The models are driven by meteorological data from JRA-25 (Japanese 25-year ReAnalysis) and JCDAS (JMA Climate Data Assimilation System). Statistically optimum physiological parameters in the biosphere model are found by iterative minimization of the corresponding Bayesian cost function. We select thirteen physiological parameter with high sensitivity to NEE, NPP, and AGB for the minimization. Given the optimized physiological parameters, the model shows error reductions in seasonal variation of the CO2 concentrations especially in the northern hemisphere due to abundant observation stations, while errors remain at a few stations that are located in coastal coastal area and stations in the southern hemisphere. The model also produces moderate estimates of the mean magnitudes and probability distributions in AGB and NPP for each biome. However, the model fails in the simulation of the terrestrial

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

    PubMed

    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. PMID:26904819

  4. Retrieval of Mid-tropospheric CO2 Directly from AIRS Measurements

    NASA Technical Reports Server (NTRS)

    Olsen, Edward T.; Chahine, Moustafa T.; Chen, Luke L.; Pagano, Thomas S.

    2008-01-01

    We apply the method of Vanishing Partial Derivatives (VPD) to AIRS spectra to retrieve daily the global distribution of CO2 at a nadir geospatial resolution of 90 km x 90 km without requiring a first-guess input beyond the global average. Our retrievals utilize the 15 (micro)m band radiances, a complex spectral region. This method may be of value in other applications, in which spectral signatures of multiple species are not well isolated spectrally from one another.

  5. Air-Sea CO2 fluxes in the Atlantic as measured during boreal spring and autumn

    NASA Astrophysics Data System (ADS)

    Padin, X. A.; Vázquez-Rodríguez, M.; Castaño, M.; Velo, A.; Alonso-Pérez, F.; Gago, J.; Gilcoto, M.; Álvarez, M.; Pardo, P. C.; de La Paz, M.; Ríos, A. F.; Pérez, F. F.

    2010-05-01

    A total of fourteen hydrographic cruises from 2000 to 2008 were conducted during the spring and autumn seasons between Spain and the Southern Ocean under the framework of the Spanish research project FICARAM. The underway measurements were processed and analysed to describe the meridional air-sea CO2 fluxes (FCO2) in the covered sector of the Atlantic Ocean. The data has been grouped into different biogeochemical oceanographic provinces based on thermohaline characteristics. The spatial and temporal distributions of FCO2 followed expected distributions and annual trends reproducing the recent climatological ΔfCO2 estimations with a mean difference of -3 ± 18 μatm (Takahashi et al., 2009). The reduction in the CO2 saturation along the meridional FICARAM cruises represented an increase of 0.02 ± 0.14 mol m-2 yr-1 in the ocean uptake of atmospheric CO2. The subtropical waters in both Hemispheres acted as a sink of atmospheric CO2 during the successive spring seasons and as a source in autumn. The coarse reduction of the ocean uptake of atmospheric CO2 observed in the North Atlantic Ocean was linked to conditions of negative phase of the North Atlantic Oscillation that prevailed during the FICARAM period. Surface waters in the North Equatorial Counter Current revealed a significant long-term decrease of sea surface salinity of -0.16 ± 0.01 yr-1 coinciding with a declination of -3.5 ± 0.9 μatm yr-1 in the air-sea disequilibrium of CO2 fugacity and a rise of oceanic CO2 uptake of -0.09 ± 0.03 mol m-2 yr-1. The largest CO2 source was located in the equatorial upwelling system. These tropical waters that reached emissions of 0.7 ± 0.5 and 1.0 ± 0.7 mol m-2 y-1 in spring and autumn, respectively, showed an interannual warming of 0.11 ± 0.03 °C yr-1 and a wind speed decrease of -0.58 ± 0.14 m s-1 yr-1 in spring cruises which suggest the weakening of upwelling events associated with warm El Niño - Southern Oscillation episodes. Contrary the surface waters of the

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

    NASA Astrophysics Data System (ADS)

    Dong, Liang; Liang, Hanwei

    2014-08-01

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

  7. Response of thermohaline circulation to higher atmospheric CO2 concentration and absence of ice sheets

    NASA Astrophysics Data System (ADS)

    Motoi, T.; Chan, W.-L.; Yih, H.

    2003-04-01

    Response of thermohaline circulation to higher CO2 concentration in the atmosphere and absence of large ice sheets are investigated by using a coupled ocean-atmosphere model. Two runs, named C run and x4CNIS run are carried out. The C run is control run with standard atmospheric CO2 concentration of 300 ppm and Greenland and Antarctic ice sheets. The x4CNIS run has atmospheric CO2 concentration of 1200 ppm, which is 4 times that of the standard value, and no ice sheet. Both the C run and x4CNIS run are integrated for more than 10000 years until equilibrium response is completed. The intensity of thermohaline circulation in the North Atlantic Ocean in x4CNIS run decreases to 3 Sv from 17 Sv during the first two hundred years and turns to gradually increasing phase from 3 Sv to 8 Sv for about 2000 years. It then increases rapidly from 8 Sv to 30 Sv within 200 years and reaches stable level of 24 Sv, which is larger than that of 17 Sv at begining, with larger oscillations. The temperatures of surface and deep waters in the sub-antarctic region and of deep tropical water are about 6.5 deg. warmer in the x4CNIS run than in the C run.

  8. Nitrogen balance for wheat canopies (Triticum aestivum cv. Veery 10) grown under elevated and ambient CO2 concentrations

    NASA Technical Reports Server (NTRS)

    Smart, D. R.; Ritchie, K.; Bloom, A. J.; Bugbee, B. B.

    1998-01-01

    We examined the hypothesis that elevated CO2 concentration would increase NO3- absorption and assimilation using intact wheat canopies (Triticum aestivum cv. Veery 10). Nitrate consumption, the sum of plant absorption and nitrogen loss, was continuously monitored for 23 d following germination under two CO2 concentrations (360 and 1000 micromol mol-1 CO2) and two root zone NO3- concentrations (100 and 1000 mmol m3 NO3-). The plants were grown at high density (1780 m-2) in a 28 m3 controlled environment chamber using solution culture techniques. Wheat responded to 1000 micromol mol-1 CO2 by increasing carbon allocation to root biomass production. Elevated CO2 also increased root zone NO3- consumption, but most of this increase did not result in higher biomass nitrogen. Rather, nitrogen loss accounted for the greatest part of the difference in NO3- consumption between the elevated and ambient [CO2] treatments. The total amount of NO3(-)-N absorbed by roots or the amount of NO3(-)-N assimilated per unit area did not significantly differ between elevated and ambient [CO2] treatments. Instead, specific leaf organic nitrogen content declined, and NO3- accumulated in canopies growing under 1000 micromol mol-1 CO2. Our results indicated that 1000 micromol mol-1 CO2 diminished NO3- assimilation. If NO3- assimilation were impaired by high [CO2], then this offers an explanation for why organic nitrogen contents are often observed to decline in elevated [CO2] environments.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    Capturing and storing CO2 in basaltic formations is one of the most promising options for mitigating atmospheric CO2 emissions resulting from the burning of fossil fuels. These geologic reservoirs have high reactive potential for CO2-mineral trapping due to an abundance of divalent-cation containing silicates, such as forsterite (Mg2SiO4). Recent studies have shown that carbonation of these silicates under wet scCO2 conditions, e. g. encountered near a CO2 injection well, proceeds along a different pathway and is more effective than in CO2-saturated aqueous fluids. The presence of an adsorbed water film on the forsterite surface seems to be key to reactivity towards carbonation. In this study, we employed in situ high pressure IR spectroscopy to investigate the dependence of adsorbed water film thickness on forsterite carbonation chemistry. Post reaction ex situ SEM, TEM, TGA, XRD, and NMR measurements will also be discussed. Several IR titrations were performed of forsterite with water at 50 °C and 90 bar scCO2. Aliquots of water were titrated at 4-hour reaction-time increments. Once a desired total water concentration was reached, data were collected for about another 30 hours. One titration involved 10 additions, which corresponds to 6.8 monolayers of adsorbed water. Clearly, a carbonate was precipitating, and its spectral signature matched magnesite. Another titration involved 8 aliquots, or up to 4.4 monolayers of water. The integrated absorbance under the CO stretching bands of carbonate as a function of time after reaching 4.4 monolayers showed an increase and then a plateau. We are currently unsure of the identity of the carbonate that precipitated, but it could be an amorphous anhydrous phase or magnesite crystals with dimensions of only several nanometers. A third titration only involved 3 additions, or up to 1.6 monolayers of water. The integrated absorbance under the CO stretching bands of carbonate as a function of time after reaching 1.6 monolayers

  10. Sustained enhancement of photosynthesis in coffee trees grown under free-air CO2 enrichment conditions: disentangling the contributions of stomatal, mesophyll, and biochemical limitations.

    PubMed

    DaMatta, Fábio M; Godoy, Alice G; Menezes-Silva, Paulo E; Martins, Samuel C V; Sanglard, Lílian M V P; Morais, Leandro E; Torre-Neto, André; Ghini, Raquel

    2016-01-01

    Coffee (Coffea spp.), a globally traded commodity, is a slow-growing tropical tree species that displays an improved photosynthetic performance when grown under elevated atmospheric CO2 concentrations ([CO2]). To investigate the mechanisms underlying this response, two commercial coffee cultivars (Catuaí and Obatã) were grown using the first free-air CO2 enrichment (FACE) facility in Latin America. Measurements were conducted in two contrasting growth seasons, which were characterized by the high (February) and low (August) sink demand. Elevated [CO2] led to increases in net photosynthetic rates (A) in parallel with decreased photorespiration rates, with no photochemical limitations to A. The stimulation of A by elevated CO2 supply was more prominent in August (56% on average) than in February (40% on average). Overall, the stomatal and mesophyll conductances, as well as the leaf nitrogen and phosphorus concentrations, were unresponsive to the treatments. Photosynthesis was strongly limited by diffusional constraints, particularly at the stomata level, and this pattern was little, if at all, affected by elevated [CO2]. Relative to February, starch pools (but not soluble sugars) increased remarkably (>500%) in August, with no detectable alteration in the maximum carboxylation capacity estimated on a chloroplast [CO2] basis. Upregulation of A by elevated [CO2] took place with no signs of photosynthetic downregulation, even during the period of low sink demand, when acclimation would be expected to be greatest. PMID:26503540

  11. Sustained enhancement of photosynthesis in coffee trees grown under free-air CO2 enrichment conditions: disentangling the contributions of stomatal, mesophyll, and biochemical limitations

    PubMed Central

    DaMatta, Fábio M.; Godoy, Alice G.; Menezes-Silva, Paulo E.; Martins, Samuel C.V.; Sanglard, Lílian M.V.P.; Morais, Leandro E.; Torre-Neto, André; Ghini, Raquel

    2016-01-01

    Coffee (Coffea spp.), a globally traded commodity, is a slow-growing tropical tree species that displays an improved photosynthetic performance when grown under elevated atmospheric CO2 concentrations ([CO2]). To investigate the mechanisms underlying this response, two commercial coffee cultivars (Catuaí and Obatã) were grown using the first free-air CO2 enrichment (FACE) facility in Latin America. Measurements were conducted in two contrasting growth seasons, which were characterized by the high (February) and low (August) sink demand. Elevated [CO2] led to increases in net photosynthetic rates (A) in parallel with decreased photorespiration rates, with no photochemical limitations to A. The stimulation of A by elevated CO2 supply was more prominent in August (56% on average) than in February (40% on average). Overall, the stomatal and mesophyll conductances, as well as the leaf nitrogen and phosphorus concentrations, were unresponsive to the treatments. Photosynthesis was strongly limited by diffusional constraints, particularly at the stomata level, and this pattern was little, if at all, affected by elevated [CO2]. Relative to February, starch pools (but not soluble sugars) increased remarkably (>500%) in August, with no detectable alteration in the maximum carboxylation capacity estimated on a chloroplast [CO2] basis. Upregulation of A by elevated [CO2] took place with no signs of photosynthetic downregulation, even during the period of low sink demand, when acclimation would be expected to be greatest. PMID:26503540

  12. Responses to iron limitation in Hordeum vulgare L. as affected by the atmospheric CO2 concentration.

    PubMed

    Haase, S; Rothe, A; Kania, A; Wasaki, J; Römheld, V; Engels, C; Kandeler, E; Neumann, G

    2008-01-01

    Elevated atmospheric CO2 treatments stimulated biomass production in Fe-sufficient and Fe-deficient barley plants, both in hydroponics and in soil culture. Root/shoot biomass ratio was increased in severely Fe-deficient plants grown in hydroponics but not under moderate Fe limitation in soil culture. Significantly increased biomass production in high CO2 treatments, even under severe Fe deficiency in hydroponic culture, indicates an improved internal Fe utilization. Iron deficiency-induced secretion of PS in 0.5 to 2.5 cm sub-apical root zones was increased by 74% in response to elevated CO2 treatments of barley plants in hydroponics but no PS were detectable in root exudates collected from soil-grown plants. This may be attributed to suppression of PS release by internal Fe concentrations above the critical level for Fe deficiency, determined at final harvest for soil-grown barley plants, even without additional Fe supply. However, extremely low concentrations of easily plant-available Fe in the investigated soil and low Fe seed reserves suggest a contribution of PS-mediated Fe mobilization from sparingly soluble Fe sources to Fe acquisition of the soil-grown barley plants during the preceding culture period. Higher Fe contents in shoots (+52%) of plants grown in soil culture without Fe supply under elevated atmospheric CO2 concentrations may indicate an increased efficiency for Fe acquisition. No significant influence on diversity and function of rhizosphere-bacterial communities was detectable in the outer rhizosphere soil (0-3 mm distance from the root surface) by DGGE of 16S rRNA gene fragments and analysis of marker enzyme activities for C-, N-, and P-cycles. PMID:18453445

  13. Implications of Limiting CO2 Concentrations for Land Use and Energy

    SciTech Connect

    Wise, Marshall A.; Calvin, Katherine V.; Thomson, Allison M.; Clarke, Leon E.; Bond-Lamberty, Benjamin; Sands, Ronald D.; Smith, Steven J.; Janetos, Anthony C.; Edmonds, James A.

    2009-05-29

    This paper is the first to simultaneously examine the implications of extending the concept of placing a value on carbon beyond fossil fuel and industrial emissions to all sources, including those associated with land use and land use change. The paper reports a variety of results that have bearing on recent discussions in the literature regarding the role of bioenergy and the indirect emission of carbon through land-use change as well as the burgeoning literature on interactions between bioenergy and crop prices. This paper goes beyond results currently in the literature by using an integrated assessment model to assess energy use and supply, atmospheric composition, land use, and terrestrial carbon in the context of limiting the concentration of atmospheric CO2. We find that when the concept of valuing carbon emissions is extended to all carbon emissions, regardless of origin, that in contrast to a mitigation scenario where only fossil fuel and industrial carbon emissions are valued, deforestation is replaced by afforestation and expanded unmanaged ecosystems; the cost of limiting CO2 concentrations falls; crop prices rise; and human diets are transformed as people shift away from consumption of beef and other carbon-intensive protein sources. The increase in crop prices flows directly from the consideration of land-use change emissions in a comprehensive emissions mitigation program and occurs even in the absence of the use of purpose-grown bioenergy. Finally, we find that the assumed rate of improvement in food and fiber crop productivity (e.g. wheat, rice, corn) has a strong influence on land-use change emissions, making the technology for growing crops potentially as important for limiting atmospheric CO2 concentrations as energy technologies such as CO2 capture and storage.

  14. The environmental plasticity and ecological genomics of the cyanobacterial CO2 concentrating mechanism.

    PubMed

    Badger, Murray R; Price, G Dean; Long, Ben M; Woodger, Fiona J

    2006-01-01

    Cyanobacteria probably exhibit the widest range of diversity in growth habitats of all photosynthetic organisms. They are found in cold and hot, alkaline and acidic, marine, freshwater, saline, terrestrial, and symbiotic environments. In addition to this, they originated on earth at least 2.5 billion years ago and have evolved through periods of dramatic O2 increases, CO2 declines, and temperature changes. One of the key problems they have faced through evolution and in their current environments is the capture of CO2 and its efficient use by Rubisco in photosynthesis. A central response to this challenge has been the development of a CO2 concentrating mechanism (CCM) that can be adapted to various environmental limitations. There are two primary functional elements of this CCM. Firstly, the containment of Rubisco in carboxysome protein microbodies within the cell (the sites of CO2) elevation), and, secondly, the presence of several inorganic carbon (Ci) transporters that deliver HCO3- intracellularly. Cyanobacteria show both species adaptation and acclimation of this mechanism. Between species, there are differences in the suites of Ci transporters in each genome, the nature of the carboxysome structures and the functional roles of carbonic anhydrases. Within a species, different CCM activities can be induced depending on the Ci availability in the environment. This acclimation is largely based on the induction of multiple Ci transporters with different affinities and specificities for either CO2 or HCO3- as substrates. These features are discussed in relation to our current knowledge of the genomic sequences of a diverse array of cyanobacteria and their ecological environments. PMID:16216846

  15. Laser Sounder for Global Measurement of CO2 Concentrations in the Troposphere from Space

    NASA Technical Reports Server (NTRS)

    Abshire, James B.; Riris, Haris; Kawa, S. Randy; Sun, Xiaoli; Chen, Jeffrey; Stephen, Mark A.; Collatz, G. James; Mao, Jianping; Allan, Graham

    2007-01-01

    Measurements of tropospheric CO2 abundance with global-coverage, a few hundred km spatial and monthly temporal resolution are needed to quantify processes that regulate CO2 storage by the land and oceans. The Orbiting Carbon Observatory (OCO) is the first space mission focused on atmospheric CO2 for measuring total column CO, and O2 by detecting the spectral absorption in reflected sunlight. The OCO mission is an essential step, and will yield important new information about atmospheric CO2 distributions. However there are unavoidable limitations imposed by its measurement approach. These include best accuracy only during daytime at moderate to high sun angles, interference by cloud and aerosol scattering, and limited signal from CO2 variability in the lower tropospheric CO2 column. We have been developing a new laser-based technique for the remote measurement of the tropospheric CO2 concentrations from orbit. Our initial goal is to demonstrate a lidar technique and instrument technology that will permit measurements of the CO2 column abundance in the lower troposphere from aircraft. Our final goal is to develop a space instrument and mission approach for active measurements of the CO2 mixing ratio at the 1-2 ppmv level. Our technique is much less sensitive to cloud and atmospheric scattering conditions and would allow continuous measurements of CO2 mixing ratio in the lower troposphere from orbit over land and ocean surfaces during day and night. Our approach is to use the 1570nm CO2 band and a 3-channel laser absorption spectrometer (i.e. lidar used an altimeter mode), which continuously measures at nadir from a near polar circular orbit. The approach directs the narrow co-aligned laser beams from the instrument's lasers toward nadir, and measures the energy of the laser echoes reflected from land and water surfaces. It uses several tunable fiber laser transmitters which allowing measurement of the extinction from a single selected CO2 absorption line in the 1570

  16. Simulation of climate change impacts on grain sorghum production grown under free air CO2 enrichment

    NASA Astrophysics Data System (ADS)

    Fu, Tongcheng; Ko, Jonghan; Wall, Gerard W.; Pinter, Paul J.; Kimball, Bruce A.; Ottman, Michael J.; Kim, Han-Yong

    2016-07-01

    Potential impacts of climate change on grain sorghum (Sorghum bicolor) productivity were investigated using the CERES-sorghum model in the Decision Support System for Agrotechnology Transfer v4.5. The model was first calibrated for a sorghum cultivar grown in a free air CO2 enrichment experiment at the University of Arizona, Maricopa, Arizona, USA in 1998. The model was then validated with an independent dataset collected in 1999. The simulated grain yield, growth, and soil water of sorghum for the both years were in statistical agreement with the corresponding measurements, respectively. Neither simulated nor measured yields responded to elevated CO2, but both were sensitive to water supply. The validated model was then applied to simulate possible effects of climate change on sorghum grain yield and water use efficiency in western North America for the years 2080-2100. The projected CO2 fertilizer effect on grain yield was dominated by the adverse effect of projected temperature increases. Therefore, temperature appears to be a dominant driver of the global climate change influencing future sorghum productivity. These results suggest that an increase in water demand for sorghum production should be anticipated in a future high-CO2 world.

  17. The physiology and genetics of CO2 concentrating mechanisms in model diatoms.

    PubMed

    Hopkinson, Brian M; Dupont, Christopher L; Matsuda, Yusuke

    2016-06-01

    Diatoms, a diverse and ecologically-important group of unicellular algae, use a CO2 concentrating mechanism to enhance the performance of RubisCO and overcome the limited availability of CO2 in their habitats. The recent development of genetic manipulation techniques for the model diatoms Phaeodactylum tricornutum and Thalassiosira pseudonana and the sequencing of their genomes have enabled the rapid identification of genes involved in their CO2 concentrating mechanisms (CCMs). These include numerous carbonic anhydrases (CAs), which are localized to distinct subcellular compartments in the two diatom species, and putative bicarbonate transporters, one of which has been functionally characterized. New physiological data on the P. tricornutum CCM are consistent with this molecular data and suggest that the major driver of the CCM is a 'chloroplast-pump' that actively transports bicarbonate into the chloroplast. In T. pseudonana, the localization of a CA in the chloroplast stroma presents a paradox as this would be expected to impede function of a biophysical CCM, though the recent proposal of a modified C4 CCM offers a potential explanation. PMID:27055267

  18. Laser Sounder for Global Measurement of CO2 Concentrations in the Troposphere from Space: Update

    NASA Astrophysics Data System (ADS)

    Abshire, J. B.; Riris, H.; Kawa, S. R.; Sun, X.; Krainak, M. A.; Mao, J.; Jian, P.; Collatz, G. J.; Stephen, M.

    2006-12-01

    We report progress in developing a laser technique for the remote measurement of the tropospheric CO2 concentrations from orbit. Our initial goal is to demonstrate a lidar technique and instrument technology that will permit measurements of the CO2 column abundance in the lower troposphere from aircraft. Our final goal is to develop a practical space instrument and mission approach for active CO2 measurements at the 1 ppmv level. This would allow continuous measurements of CO2 mixing ratio, both day and night, over land and ocean surfaces, under realistic atmospheric scattering conditions. Measuring the CO2 mixing ratio in the troposphere from space is quite challenging. High signal-to-noise ratios and measurement stabilities are needed for accurate mixing ratio estimates. Our laser sounder approach has some fundamental advantages over passive sensors which use sunlight. It always uses a common nadir/zenith measurement path and the narrow laser divergence angles produce small laser footprints. The laser source allows it to measure in sunlight and darkness over different surfaces giving full global coverage. It can measure continuously over the ocean, to cloud tops and through broken clouds. The lasers are pulsed and potential measurement errors from aerosol scattering can be greatly reduced by using time gating in the receiver. Our approach uses a dual channel laser altimeter/spectrometer, which continuously measures at nadir from a near polar circular orbit. It uses several tunable fiber lasers for simultaneous measurement of the absorption from CO2 and O2, and aerosol backscatter in the same path. It directs the narrow co-aligned laser beams from the instrument's lasers toward nadir, and measures the energy of the laser echoes reflected from land and water surfaces During the measurement its lasers are tuned on- and off- a selected CO2 line near 1572 nm and a selected O2 line near 768 nm in the Oxygen A band at kHz rates. The receiver uses a 1-m diameter

  19. Cyanobacterial CO2-concentrating mechanism components: function and prospects for plant metabolic engineering.

    PubMed

    Long, Benedict M; Rae, Benjamin D; Rolland, Vivien; Förster, Britta; Price, G Dean

    2016-06-01

    Global population growth is projected to outpace plant-breeding improvements in major crop yields within decades. To ensure future food security, multiple creative efforts seek to overcome limitations to crop yield. Perhaps the greatest limitation to increased crop yield is photosynthetic inefficiency, particularly in C3 crop plants. Recently, great strides have been made toward crop improvement by researchers seeking to introduce the cyanobacterial CO2-concentrating mechanism (CCM) into plant chloroplasts. This strategy recognises the C3 chloroplast as lacking a CCM, and being a primordial cyanobacterium at its essence. Hence the collection of solute transporters, enzymes, and physical structures that make cyanobacterial CO2-fixation so efficient are viewed as a natural source of genetic material for C3 chloroplast improvement. Also we highlight recent outstanding research aimed toward the goal of introducing a cyanobacterial CCM into C3 chloroplasts and consider future research directions. PMID:26999306

  20. Can seasonal and interannual variation in landscape CO2 fluxes be detected by atmospheric observations of CO2 concentrations made at a tall tower?

    NASA Astrophysics Data System (ADS)

    Smallman, T. L.; Williams, M.; Moncrieff, J. B.

    2014-02-01

    The coupled numerical weather model WRF-SPA (Weather Research and Forecasting model and Soil-Plant-Atmosphere model) has been used to investigate a 3 yr time series of observed atmospheric CO2 concentrations from a tall tower in Scotland, UK. Ecosystem-specific tracers of net CO2 uptake and net CO2 release were used to investigate the contributions to the tower signal of key land covers within its footprint, and how contributions varied at seasonal and interannual timescales. In addition, WRF-SPA simulated atmospheric CO2 concentrations were compared with two coarse global inversion models, CarbonTrackerEurope and the National Oceanic and Atmospheric Administration's CarbonTracker (CTE-CT). WRF-SPA realistically modelled both seasonal (except post harvest) and daily cycles seen in observed atmospheric CO2 at the tall tower (R2 = 0.67, rmse = 3.5 ppm, bias = 0.58 ppm). Atmospheric CO2 concentrations from the tall tower were well simulated by CTE-CT, but the inverse model showed a poorer representation of diurnal variation and simulated a larger bias from observations (up to 1.9 ppm) at seasonal timescales, compared to the forward modelling of WRF-SPA. However, we have highlighted a consistent post-harvest increase in the seasonal bias between WRF-SPA and observations. Ecosystem-specific tracers of CO2 exchange indicate that the increased bias is potentially due to the representation of agricultural processes within SPA and/or biases in land cover maps. The ecosystem-specific tracers also indicate that the majority of seasonal variation in CO2 uptake for Scotland's dominant ecosystems (forests, cropland and managed grassland) is detectable in observations within the footprint of the tall tower; however, the amount of variation explained varies between years. The between years variation in detectability of Scotland's ecosystems is potentially due to seasonal and interannual variation in the simulated prevailing wind direction. This result highlights the importance of

  1. Laser Sounder for Global Measurement of CO2 Concentrations in the Troposphere from Space

    NASA Technical Reports Server (NTRS)

    Abshire, James B.; Riris, Haris; Kawa, S. Randy; Sun, Xiaoli; Chen, Jeffrey; Stephen, Mark A.; Collatz, G. James; Mao, Jianping; Allan, Graham

    2007-01-01

    Measurements of tropospheric CO2 abundance with global-coverage, a few hundred km spatial and monthly temporal resolution are needed to quantify processes that regulate CO2 storage by the land and oceans. The Orbiting Carbon Observatory (OCO) is the first space mission focused on atmospheric CO2 for measuring total column CO, and O2 by detecting the spectral absorption in reflected sunlight. The OCO mission is an essential step, and will yield important new information about atmospheric CO2 distributions. However there are unavoidable limitations imposed by its measurement approach. These include best accuracy only during daytime at moderate to high sun angles, interference by cloud and aerosol scattering, and limited signal from CO2 variability in the lower tropospheric CO2 column. We have been developing a new laser-based technique for the remote measurement of the tropospheric CO2 concentrations from orbit. Our initial goal is to demonstrate a lidar technique and instrument technology that will permit measurements of the CO2 column abundance in the lower troposphere from aircraft. Our final goal is to develop a space instrument and mission approach for active measurements of the CO2 mixing ratio at the 1-2 ppmv level. Our technique is much less sensitive to cloud and atmospheric scattering conditions and would allow continuous measurements of CO2 mixing ratio in the lower troposphere from orbit over land and ocean surfaces during day and night. Our approach is to use the 1570nm CO2 band and a 3-channel laser absorption spectrometer (i.e. lidar used an altimeter mode), which continuously measures at nadir from a near polar circular orbit. The approach directs the narrow co-aligned laser beams from the instrument's lasers toward nadir, and measures the energy of the laser echoes reflected from land and water surfaces. It uses several tunable fiber laser transmitters which allowing measurement of the extinction from a single selected CO2 absorption line in the 1570

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

    PubMed

    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]. PMID:27317970

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

    NASA Astrophysics Data System (ADS)

    Michael, Peter J.; Graham, David W.

    2015-11-01

    In order to better determine the behavior of CO2 relative to incompatible elements, and improve the accuracy of mantle CO2 concentration and flux estimates, we determined CO2 glass and vesicle concentrations, plus trace element contents for fifty-one ultradepleted mid-ocean ridge basalt (MORB) glasses from the global mid-ocean ridge system. Fifteen contained no vesicles and were volatile undersaturated for their depth of eruption. Thirty-six contained vesicles and/or were slightly oversaturated, and so may not have retained all of their CO2. If this latter group lost some bubbles during emplacement, then CO2/Ba calculated for the undersaturated group alone is the most reliable and uniform ratio at 98 ± 10, and CO2/Nb is 283 ± 32. If the oversaturated MORBs did not lose bubbles, then CO2/Nb is the most uniform ratio within the entire suite of ultradepleted MORBs at 291 ± 132, while CO2/Ba decreases with increasing incompatible element enrichment. Additional constraints on CO2/Ba and CO2/Nb ratios are provided by published estimates of CO2 contents in highly vesicular enriched basalts that may have retained their vesicles e.g., the Mid-Atlantic Ridge "popping rocks", and from olivine-hosted melt inclusions in normal MORBs. As incompatible element enrichment increases, CO2/Nb increases progressively from 283 ± 32 in ultradepleted MORBs to 603 ± 69 in depleted melt inclusions to 936 ± 132 in enriched, vesicular basalts. In contrast, CO2/Ba is nearly uniform in these sample suites at 98 ± 10, 106 ± 24 and 111 ± 11 respectively. This suggests that Ba is the best proxy for estimating CO2 contents of MORBs, with an overall average CO2/Ba = 105 ± 9. Atlantic, Pacific and Indian basalts have similar values. Gakkel Ridge has lower CO2/Ba because of anomalously high Ba, and is not included in our global averages. Using the CO2/Ba ratio and published compilations of trace elements in average MORBs, the CO2 concentration of a primary, average MORB is 2085+ 473/- 427

  4. Air-water gas exchange and CO2 flux in a mangrove-dominated estuary

    USGS Publications Warehouse

    Ho, David T.; Ferrón, Sara; Engel, Victor C.; Larsen, Laurel G.; Barr, Jordan G.

    2014-01-01

    Mangrove forests are highly productive ecosystems, but the fate of mangrove-derived carbon remains uncertain. Part of that uncertainty stems from the fact that gas transfer velocities in mangrove-surrounded waters are not well determined, leading to uncertainty in air-water CO2 fluxes. Two SF6 tracer release experiments were conducted to determine gas transfer velocities (k(600) = 8.3 ± 0.4 and 8.1 ± 0.6 cm h−1), along with simultaneous measurements of pCO2 to determine the air-water CO2 fluxes from Shark River, Florida (232.11 ± 23.69 and 171.13 ± 20.28 mmol C m−2 d−1), an estuary within the largest contiguous mangrove forest in North America. The gas transfer velocity results are consistent with turbulent kinetic energy dissipation measurements, indicating a higher rate of turbulence and gas exchange than predicted by commonly used wind speed/gas exchange parameterizations. The results have important implications for carbon fluxes in mangrove ecosystems.

  5. Vibro-acoustic characterization of flexible hose in CO2 car air conditioning systems

    NASA Astrophysics Data System (ADS)

    Angelini, F.; Bergami, A.; Martarelli, M.; Tomasini, E. P.

    2008-06-01

    Following the EU directive 2006/40/EC proscribing from 2011 that refrigerant fluids must have a global warming potential not higher than 150, it will not be allowed anymore to employ the current R134a on car air conditioning systems. Maflow s.p.a (automotive hose maker) is developing products for each possible new refrigerant. This paper is focused on hoses for CO2 refrigerants operating in the worst conditions because of the high pressures and temperatures at which they are working (with R134a the high pressure is 18 bar and low pressure is 3 bar; with CO2 the high pressure is 100 bar and low pressure is 35 bar). Therefore the noise emission control of the CO2 air conditioning systems is very important. The aim of this study is to develop a standard measurement method for the vibro - acoustic characterization of High Pressure (HP - Shark F4) and Low Pressure (LP - ULEV) hoses to reduce noise emission and raise car passenger comfort; in particular deep research on high pressure hose. The method is based on the measurement of the vibration level of the hoses in a standard test bench by means of a Laser Doppler Vibrometer (LDV) and its acoustic emission by a sound intensity probe.

  6. Air-water gas exchange and CO2 flux in a mangrove-dominated estuary

    NASA Astrophysics Data System (ADS)

    Ho, David T.; Ferrón, Sara; Engel, Victor C.; Larsen, Laurel G.; Barr, Jordan G.

    2014-01-01

    forests are highly productive ecosystems, but the fate of mangrove-derived carbon remains uncertain. Part of that uncertainty stems from the fact that gas transfer velocities in mangrove-surrounded waters are not well determined, leading to uncertainty in air-water CO2 fluxes. Two SF6 tracer release experiments were conducted to determine gas transfer velocities (k(600) = 8.3 ± 0.4 and 8.1 ± 0.6 cm h-1), along with simultaneous measurements of pCO2 to determine the air-water CO2 fluxes from Shark River, Florida (232.11 ± 23.69 and 171.13 ± 20.28 mmol C m-2 d-1), an estuary within the largest contiguous mangrove forest in North America. The gas transfer velocity results are consistent with turbulent kinetic energy dissipation measurements, indicating a higher rate of turbulence and gas exchange than predicted by commonly used wind speed/gas exchange parameterizations. The results have important implications for carbon fluxes in mangrove ecosystems.

  7. Elevated CO2 and warming differentially impact carbon isotope discrimination and tissue N concentration in five grassland species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We measured carbon isotope discrimination ('13C) and tissue N concentration in above ground biomass over four years at the Prairie Heating and CO2 Enrichment (PHACE) experiment in southeastern Wyoming, USA. This factorial experiment combined FACE (ambient and elevated [600 ppm] CO2 concentration), e...

  8. Effect of Co2+ concentration on the crystal structure of electrodeposited Co nanowires

    NASA Astrophysics Data System (ADS)

    Mukhtar, Aiman; Mehmood, Tahir; Khan, Babar Shahzad; Tan, Ming

    2016-05-01

    The structure of Co nanowires deposited at the same potential depends on Co2+ concentration in solution. When depositing at -1.6 V, the formed Co nanowire are hcp phase in 0.356 M solution, a mixture of hcp and fcc phases in 0.53 M solution, almost fcc phase in 0.71 M solution and pure fcc phase in 1.06 M solution. The transient curves show two interesting observations. First, the imax increases with increasing concentration of Co2+ ions while the tm decreases with increasing concentration. Second, the imax and tm observed in depositing Co nanowires at -1.6 V in the 0.71 M solution are close to those in depositing Co nanowires at -3.0 V in the 0.356 M solution. A higher imax and shorter tm can represent a larger Ns (saturation nucleus density). Therefore we believe that the deposition at -1.6 V in higher concentrations such as 0.71 and 1.067 M can lead to a larger Ns, indicating the formation of smaller critical nuclei. The structure of Co can be determined by the critical nucleus size and smaller critical nuclei favor the formation of fcc Co. Therefore the fcc Co nanowires were observed when depositing in the high concentration solution such as 0.71 and 1.067 M.

  9. 13CO2/12CO2 ratio analysis in exhaled air by lead-salt tunable diode lasers for noninvasive diagnostics in gastroenterology

    NASA Astrophysics Data System (ADS)

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

    1999-07-01

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

  10. Biases in the air-sea flux of CO2 resulting from ocean surface temperature gradients

    NASA Astrophysics Data System (ADS)

    Ward, B.; Wanninkhof, R.; McGillis, W. R.; Jessup, A. T.; Degrandpre, M. D.; Hare, J. E.; Edson, J. B.

    2004-08-01

    The difference in the fugacities of CO2 across the diffusive sublayer at the ocean surface is the driving force behind the air-sea flux of CO2. Bulk seawater fugacity is normally measured several meters below the surface, while the fugacity at the water surface, assumed to be in equilibrium with the atmosphere, is measured several meters above the surface. Implied in these measurements is that the fugacity values are the same as those across the diffusive boundary layer. However, temperature gradients exist at the interface due to molecular transfer processes, resulting in a cool surface temperature, known as the skin effect. A warm layer from solar radiation can also result in a heterogeneous temperature profile within the upper few meters of the ocean. Here we describe measurements carried out during a 14-day study in the equatorial Pacific Ocean (GasEx-2001) aimed at estimating the gradients of CO2 near the surface and resulting flux anomalies. The fugacity measurements were corrected for temperature effects using data from the ship's thermosalinograph, a high-resolution profiler (SkinDeEP), an infrared radiometer (CIRIMS), and several point measurements at different depths on various platforms. Results from SkinDeEP show that the largest cool skin and warm layer biases occur at low winds, with maximum biases of -4% and +4%, respectively. Time series ship data show an average CO2 flux cool skin retardation of about 2%. Ship and drifter data show significant CO2 flux enhancement due to the warm layer, with maximums occurring in the afternoon. Temperature measurements were compared to predictions based on available cool skin parameterizations to predict the skin-bulk temperature difference, along with a warm layer model.

  11. [Effect of air temperature and rainfall on wetland ecosystem CO2 exchange in China].

    PubMed

    Chu, Xiao-jing; Han, Guang-xuan

    2015-10-01

    Wetland can be a potential efficient sink to reduce global warming due to its higher primary productivity and lower carbon decomposition rate. While there has been a series progress on the influence mechanism of ecosystem CO2 exchange over China' s wetlands, a systematic metaanalysis of data still needs to be improved. We compiled data of ecosystem CO2 exchange of 21 typical wetland vegetation types in China from 29 papers and carried out an integrated analysis of air temperature and precipitation effects on net ecosystem CO2 exchange (NEE), ecosystem respiration (Reco), gross primary productivity (GPP), the response of NEE to PAR, and the response of Reco to temperature. The results showed that there were significant responses (P<0.05) of NEE (R2 = 50%, R2=57%), GPP (R2 = 60%, R2 = 50%) Reco (R2 = 44%, R2=50%) with increasing air temperature and enhanced precipitation on the annual scale. On the growing season scale, air temperature accounted for 50% of the spatial variation of NEE, 36% of GPP and 19% of Reco, respectively. Both NEE (R2 = 33%) and GPP (R2 =25%) were correlated positively with precipitation (P<0.05). However, the relationship between Reco and precipitation was not significant (P>0.05). Across different Chinese wetlands, both precipitation and temperature had no significant effect on apparent quantum yield (α) or ecosystem respiration in the daytime (Reco,day, P>0.05). The maximum photosynthesis rate (Amax) was remarkably correlated with precipitation (P <0.01), but not with air temperature. Besides, there was no significant correlation between basal respiration (Rref) and precipitation (P>0.05). Precipitation was negatively correlated with temperature sensitivity of Reco (Q10, P<0.05). Furthermore, temperature accounted for 35% and 46% of the variations in temperature sensitivity of Reco (Q10) and basal respiration (Rref P<0.05), respectively. PMID:26995905

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  14. Decreases in stomatal conductance of soybean (Glycine max) under open-air elevation of CO2 is closely coupled with decreases in ecosystem evapotranspiration

    NASA Astrophysics Data System (ADS)

    Bernacchi, C.; Kimball, B. A.; Quarles, D. R.; Long, S. P.; Ort, D. R.

    2006-12-01

    Stomatal responses to atmospheric change have been documented through a range of enclosure-based experiments. Increases in atmospheric concentration of CO2 ([CO2]) has been shown to decrease stomatal conductance (gs) for a many species under numerous conditions. Less well understood, however, is the extent to which leaf level responses translate to changes in ecosystem evapotranspiration, ET. Since many changes at the soil, plant and canopy microclimate level may feed back on ET, it is not certain that decrease in gs will decrease ET in rainfed crops. To examine the scaling of the effect of elevated [CO2] on gs at the leaf to ecosystem ET, soybean (Glycine max) was grown in field conditions under control (ca 375 μmol CO2 mol-1 air) and elevated [CO2] (ca. 550 μmol mol^{- 1}) using Free Air CO2 Enrichment (FACE). ET was measured from the time of canopy closure to crop senescence using a residual energy balance approach over four growing seasons. Elevated [CO2] caused ET to decrease between 9 and 16% depending on year and despite large increases in photosynthesis and seed yield. Although elevated [CO2] increased leaf area and canopy temperature (Tc), ET was closely coupled (0.78) to gs of the upper canopy leaves; this relationship was not altered by growth at elevated [CO2]. The findings are consistent with model and historical analyses which suggest that, despite system feedbacks, decreased gs at elevated [CO2] results in decreased transfer of water vapor to the atmosphere.

  15. Sea-air CO2 fluxes in the Southern Ocean for the period 1990-2009

    NASA Astrophysics Data System (ADS)

    Lenton, A.; Tilbrook, B.; Law, R. M.; Bakker, D.; Doney, S. C.; Gruber, N.; Ishii, M.; Hoppema, M.; Lovenduski, N. S.; Matear, R. J.; McNeil, B. I.; Metzl, N.; Mikaloff Fletcher, S. E.; Monteiro, P. M. S.; Rödenbeck, C.; Sweeney, C.; Takahashi, T.

    2013-06-01

    The Southern Ocean (44-75° S) plays a critical role in the global carbon cycle, yet remains one of the most poorly sampled ocean regions. Different approaches have been used to estimate sea-air CO2 fluxes in this region: synthesis of surface ocean observations, ocean biogeochemical models, and atmospheric and ocean inversions. As part of the RECCAP (REgional Carbon Cycle Assessment and Processes) project, we combine these different approaches to quantify and assess the magnitude and variability in Southern Ocean sea-air CO2 fluxes between 1990-2009. Using all models and inversions (26), the integrated median annual sea-air CO2 flux of -0.42 ± 0.07 Pg C yr-1 for the 44-75° S region, is consistent with the -0.27 ± 0.13 Pg C yr-1 calculated using surface observations. The circumpolar region south of 58° S has a small net annual flux (model and inversion median: -0.04 ± 0.07 Pg C yr-1 and observations: +0.04 ± 0.02 Pg C yr-1), with most of the net annual flux located in the 44 to 58° S circumpolar band (model and inversion median: -0.36 ± 0.09 Pg C yr-1 and observations: -0.35 ± 0.09 Pg C yr-1). Seasonally, in the 44-58° S region, the median of 5 ocean biogeochemical models captures the observed sea-air CO2 flux seasonal cycle, while the median of 11 atmospheric inversions shows little seasonal change in the net flux. South of 58° S, neither atmospheric inversions nor ocean biogeochemical models reproduce the phase and amplitude of the observed seasonal sea-air CO2 flux, particularly in the Austral Winter. Importantly, no individual atmospheric inversion or ocean biogeochemical model is capable of reproducing both the observed annual mean uptake and the observed seasonal cycle. This raises concerns about projecting future changes in Southern Ocean CO2 fluxes. The median interannual variability from atmospheric inversions and ocean biogeochemical models is substantial in the Southern Ocean; up to 25% of the annual mean flux, with 25% of this interannual

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  17. Regenerable device for scrubbing breathable air of CO2 and moisture without special heat exchanger equipment

    NASA Technical Reports Server (NTRS)

    Tepper, E. H. (Inventor)

    1977-01-01

    The device concerns the circulation of cabin air through canisters which absorb and adsorb carbon dioxide, together with excess moisture, and return the scrubbed air to the cabin for recirculation. A coating on an inert substrate in granular form absorbs and adsorbs the impurities at standard temperatures and pressures, but desorbs such impurities at low pressures (vacuum) and standard temperatures. This fact is exploited by making the device in a stack of cells consisting of layers or cells which are isolated from one another flow-wise and are connected to separate manifolds and valving systems into two separate subsets. A first subset may be connected for the flow breathable air therethrough until the polyethyleneimine of its cells is saturated with CO2 and H2O. During the same period the second subset of cells is manifolded to a vacuum source.

  18. Concentrations and δ13C values of atmospheric CO2 in a less-urbanized environment: Are they different from large metropolitan areas?

    NASA Astrophysics Data System (ADS)

    Childree, P.; FENG, W.; Thieme, D. M.

    2012-12-01

    The carbon isotope compositions (δ13C values) and CO2 concentrations were measured for seventy-four atmospheric samples collected in the city of Valdosta to evaluate the sources of CO2 input in a less developed urban environment. The results are compared to studies conducted in larger metropolitan areas to evaluate possible difference in sources and concentrations. Sixty-one of the samples were collected at four "outdoor" sites within a ~100 km2 area around the city, while thirteen "indoor" samples were collected in classrooms on the Valdosta State University campus, located north of downtown. Four sample collection trips were made from March to April of 2012. The samples were collected from 5 AM to 6 PM to encompass possible diurnal changes in atmospheric CO2. The thirteen indoor air samples had concentrations ranging from 429 to 681 ppmV with δ13C values ranging from -14.0 to -10.3 ‰. The sixty-one outdoor samples ranged from 397 to 539 ppmV with δ13C values ranging from -13.0 to -7.0 ‰. The higher outdoor CO2 concentrations (> 450 ppmV) correspond to lower δ13C values and are for samples collected during prolonged calm periods (wind speed < 1 km/h). At higher wind speed, however, outside air masses (mostly from the Gulf of Mexico) were carried into the region, which led to decreased CO2 levels and increased δ13C values. Therefore, the elevated CO2 readings likely reflected influx of locally produced CO2. On a diagram of δ13C vs.104/CO2 (Keeling plot), the domain occupied by the Valdosta samples is mostly located within the boundaries of two endmember mixing lines: 1) mixing between global atmospheric background and petroleum burning; 2) mixing between global atmospheric background and natural gas burning. Results are compared to those from a Dallas, Texas study that showed more contribution of CO2 from soil respiration and petroleum burning. This study suggests that even in a smaller urban area, fossil fuel consumptions are still the main source of the

  19. Roles of biological and physical processes in driving seasonal air-sea CO2 flux in the Southern Ocean: New insights from CARIOCA pCO2

    NASA Astrophysics Data System (ADS)

    Merlivat, L.; Boutin, J.; Antoine, D.

    2015-07-01

    On a mean annual basis, the Southern Ocean is a sink for atmospheric CO2. However the seasonality of the air-sea CO2 flux in this region is poorly documented. We investigate processes regulating air-sea CO2 flux in a large area of the Southern Ocean (38°S-55°S, 60°W-60°E) that represents nearly one third of the subantarctic zone. A seasonal budget of CO2 partial pressure, pCO2 and of dissolved inorganic carbon, DIC in the mixed layer is assessed by quantifying the impacts of biology, physics and thermodynamical effect on seawater pCO2. A focus is made on the quantification at a monthly scale of the biological consumption as it is the dominant process removing carbon from surface waters. In situ biological carbon production rates are estimated from high frequency estimates of DIC along the trajectories of CARIOCA drifters in the Atlantic and Indian sector of the Southern Ocean during four spring-summer seasons over the 2006-2009 period. Net community production (NCP) integrated over the mixed layer is derived from the daily change of DIC, and mixed layer depth estimated from Argo profiles. Eleven values of NCP are estimated and range from 30 to 130 mmol C m- 2 d- 1. They are used as a constraint for validating satellite net primary production (NPP). A satellite data-based global model is used to compute depth integrated net primary production, NPP, for the same periods along the trajectories of the buoys. Realistic NCP/NPP ratios are obtained under the condition that the SeaWiFS chlorophyll are corrected by a factor of ≈ 2-3, which is an underestimation previously reported for the Southern Ocean. Monthly satellite based NPP are computed over the 38°S-55°S, 60°W-60°E area. pCO2 derived from these NPP combined with an export ratio, and taking into account the impact of physics and thermodynamics is in good agreement with the pCO2 seasonal climatology of Takahashi (2009). On an annual timescale, mean NCP values, 4.4 to 4.9 mol C m- 2 yr- 1 are ≈ 4-5 times

  20. The impact of elevated CO2 concentration on the quality of algal starch as a potential biofuel feedstock.

    PubMed

    Tanadul, Orn-U-Ma; VanderGheynst, Jean S; Beckles, Diane M; Powell, Ann L T; Labavitch, John M

    2014-07-01

    Cultured microalgae are viewed as important producers of lipids and polysaccharides, both of which are precursor molecules for the production of biofuels. This study addressed the impact of elevated carbon dioxide (CO2) on Chlorella sorokiniana production of starch and on several properties of the starch produced. The production of C. sorokiniana biomass, lipid and starch were enhanced when cultures were supplied with 2% CO2. Starch granules from algae grown in ambient air and 2% CO2 were analyzed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The granules from algae grown in 2% CO2 were disk-shaped and contained mainly stromal starch; granules from cultures grown in ambient air were cup-shaped with primarily pyrenoid starch. The granules from cells grown in 2% CO2 had a higher proportion of the accumulated starch as the highly branched, amylopectin glucan than did granules from cells grown in air. The rate of hydrolysis of starch from 2% CO2-grown cells was 1.25 times greater than that from air-grown cells and 2-11 times higher than the rates of hydrolysis of starches from cereal grains. These data indicate that culturing C. sorokiniana in elevated CO2 not only increases biomass yield but also improves the structure and composition of starch granules for use in biofuel generation. These modifications in culture conditions increase the hydrolysis efficiency of the starch hydrolysis, thus providing potentially important gains for biofuel production. PMID:24474069

  1. Combining Experiments and Simulation of Gas Absorption for Teaching Mass Transfer Fundamentals: Removing CO2 from Air Using Water and NaOH

    ERIC Educational Resources Information Center

    Clark, William M.; Jackson, Yaminah Z.; Morin, Michael T.; Ferraro, Giacomo P.

    2011-01-01

    Laboratory experiments and computer models for studying the mass transfer process of removing CO2 from air using water or dilute NaOH solution as absorbent are presented. Models tie experiment to theory and give a visual representation of concentration profiles and also illustrate the two-film theory and the relative importance of various…

  2. Development of a Low-Power CO2 Removal and Compression System for Closed-Loop Air Revitalization in Future Spacecraft

    NASA Technical Reports Server (NTRS)

    Mulloth, Lila M.; Rosen, Micha; Affleck, David; LeVan, M. Douglas; Moate, Joe R.

    2005-01-01

    The current CO2 removal technology of NASA is very energy intensive and contains many non-optimized subsystems. This paper discusses the design and prototype development of a two-stage CO2 removal and compression system that will utilize much less power than NASA s current CO2 removal technology. This integrated system contains a Nafion membrane followed by a residual water adsorber that performs the function of the desiccant beds in the four-bed molecular sieve (4BMS) system of the International Space Station (ISS). The membrane and the water adsorber are followed by a two-stage CO2 removal and compression subsystem that satisfies the operations of the CO2 adsorbent beds of the 4BMS aid the interface compressor for the Sabatier reactor connection. The two-stage compressor will utilize the principles of temperature-swing adsorption (TSA) compression technology for CO2 removal and compression. The similarities in operation and cycle times of the CO2 removal (first stage) and compression (second stage) operations will allow thermal coupling of the processes to maximize the efficiency of the system. In addition to the low-power advantage, this processor will maintain a lower CO2 concentration in the cabin than that can be achieved by the existing CO2 removal systems. The compact, consolidated, configuration of membrane gas dryer and CO2 separator and compressor will allow continuous recycling of humid air in the cabin and supply of compressed CO2 to the reduction unit for oxygen recovery. The device has potential application to the International Space Station and future, long duration, transit, and planetary missions.

  3. Functionalized Polysilsesquioxane-Based Hybrid Silica Solid Amine Sorbents for the Regenerative Removal of CO2 from Air.

    PubMed

    Abhilash, Kochukunju Adisser Saraladevi; Deepthi, Thomas; Sadhana, Retnakumari Amma; Benny, K George

    2015-08-19

    Functionalized polysilsesquioxane-based hybrid silica materials are presented as solid amine sorbents for direct CO2 capture from air. The sorbent was synthesized from amine and vinyl functionalized alkoxysilanes by a simple, energy efficient, and cost-effective co-condensation method. The material, containing bound amine functionalities, was found to have a selective CO2 capturing capacity of 1.68 mmol/g from atmospheric air with an adsorption half time of 50 min. This material also showed a maximum adsorption capacity of 2.28 mmol/g in pure CO2 and 1.92 mmol/g in 10% CO2. Desorption started at a temperature as low as 60 °C, and complete desorption occurred at 80 °C. The sorbent exhibited high recycling ability, and 100 cycles of adsorption/desorption were demonstrated in pure CO2 and 50 cycles in ambient air without any loss in efficiency. PMID:26196267

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

    NASA Astrophysics Data System (ADS)

    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. Adjoint-Based Methods for Estimating CO2 Sources and Sinks from Atmospheric Concentration Data

    NASA Technical Reports Server (NTRS)

    Andrews, Arlyn E.

    2003-01-01

    Work to develop adjoint-based methods for estimating CO2 sources and sinks from atmospheric concentration data was initiated in preparation for last year's summer institute on Carbon Data Assimilation (CDAS) at the National Center for Atmospheric Research in Boulder, CO. The workshop exercises used the GSFC Parameterized Chemistry and Transport Model and its adjoint. Since the workshop, a number of simulations have been run to evaluate the performance of the model adjoint. Results from these simulations will be presented, along with an outline of challenges associated with incorporating a variety of disparate data sources, from sparse, but highly precise, surface in situ observations to less accurate, global future satellite observations.

  6. Carbon Release from Melting Arctic Permafrost on the North Slope, AK: 12CO2 and 13CO2 Concentrations and Fluxes, and Their Relationship to Methane and Methane Isotope Concentrations Measured in August 2013

    NASA Astrophysics Data System (ADS)

    Munster, J. B.; Sayres, D. S.; Healy, C. E.; Dumas, E. J.; Dobosy, R.; Kochendorfer, J.; Heuer, M.; Meyers, T. P.; Baker, B.; Anderson, J. G.

    2014-12-01

    One of the most important uncertainties in climate change is the positive feedback mechanism associated with the melting Arctic. As the Arctic permafrost destabilizes, labile carbon stored in the permafrost is subject to respiration and methanogenesis, producing greenhouse gases CO2 and CH4. Understanding the timing and rate of this release is paramount to our long-term understanding of the global climate structure, yet the remote location of the North Slope logistically precludes widespread tower measurements, necessitating airborne measurements. Presented are 12C and 13C CO2 concentration flux measurements taken via an aircraft at a height of 10-30m during mid to late August 2013 from the north slope of Alaska. The data show different regimes for CO2 vs δ-13C over regions within a roughly 100km box, indicating heterogenous landscape with differing dominant biological processes. The data are compared to CH4 measurements that were taken simultaneously, showing highly varying concentrations of CH4 with several different archetypical relationships to the total CO2 regimes. The relationship between CO2, δ-13C CO2, and CH4 concentrations provide further insight into the biological processes occurring in the melting Arctic permafrost. The data show that the dominant uptake and emission processes change by time of day and location. While the CO2 and isotopologue data alone indicates whether a region is dominant in respiration or photosynthesis, combining the data with CH4 measurements provides insight into the provenance of the CH4 as well as methanogenic biological pathways active on the North Slope, while mass balance between CH4, CO2 or δ-13C CO2 determines whether the methane signature is from methanogenesis, natural hydrocarbon seeps, or methane flaring. The data show few if any cases for which increases in methane concentrations are accompanied by a deviation in CO2 or δ-13C CO2 that would indicate incomplete methane flaring or natural seeps.

  7. CO2 Extraction from Ambient Air Using Alkali-Metal Hydroxide Solutions Derived from Concrete Waste and Steel Slag

    NASA Astrophysics Data System (ADS)

    Stolaroff, J. K.; Lowry, G. V.; Keith, D. W.

    2003-12-01

    To mitigate global climate change, deep reductions in CO2 emissions are required in the coming decades. Carbon sequestration will play a crucial role in this reduction. Early adoption of carbon sequestration in low-cost niche markets will help develop the technology and experience required for large-scale deployment. One such niche may be the use of alkali metals from industrial waste streams to form carbonate minerals, a safe and stable means of sequestering carbon. In this research, the potential of using two industrial waste streams---concrete and steel slag---for sequestering carbon is assessed. The scheme is outlined as follows: Ca and Mg are leached with water from a finely ground bed of steel slag or concrete. The resulting solution is sprayed through air, capturing CO2 and forming solid carbonates, and collected. The feasibility of this scheme is explored with a combination of experiments, theoretical calculations, cost accounting, and literature review. The dissolution kinetics of steel slag and concrete as a function of particle size and pH is examined. In stirred batch reactors, the majority of Ca which dissolved did so within the first hour, yielding between 50 and 250 (mg; Ca)/(g; slag) and between 10 and 30 (mg; Ca)/(g; concrete). The kinetics of dissolution are thus taken to be sufficiently fast to support the type of scheme described above. As proof-of-concept, further experiments were performed where water was dripped slowly through a stagnant column of slag or concrete and collected at the bottom. Leachate Ca concentrations in the range of 15 mM were achieved --- sufficient to support the scheme. Using basic physical principles and numerical methods, the quantity of CO2 captured by falling droplets is estimated. Proportion of water loss and required pumping energy is similarly estimated. The results indicate that sprays are capable of capturing CO2 from the air and that the water and energy requirements are tractable. An example system for

  8. Warming does not stimulate mitochondrial respiration and it responds to leaf carbohydrates availability in soybean plants grown under elevated CO2 concentrations

    NASA Astrophysics Data System (ADS)

    Ruiz Vera, U. M.; Gomez-Casanovas, N.; Bernacchi, C.; Ort, D. R.; Siebers, M.

    2015-12-01

    There is a lack of understanding on the mechanism underlying the response of mitochondrial respiration (Rs) to the single and combined effects of increasing CO2 concentration ([CO2]) and warming. We investigated the response of Rs to the single and combined effects of elevated [CO2] and warming in soybean plants over a complete growing season using Temperature by Free Air CO2 enrichment technology under field conditions. The treatments were: control, elevated [CO2] (eC), high temperature (eT), and elevated [CO2]+high temperature (eT+eC). Given that photosynthetic rates in eT+eC grown plants were not higher than in plants grown under eC, we hypothesized that Rs would increase only slightly in plants grown under eT+eC compared to eC plants, due to the increase of temperature. Contrary to our prediction, our preliminary results showed that plants grown under the warming treatments had low Rs, thus eT+eC had lower Rs than eC. The response of Rs to these factors was consistent at two different plant high levels (canopy and five nodes down the canopy). Changes in Rs were explained by variations in the carbohydrate content. Our results indicate that the response of Rs to changes in [CO2] and temperature will depend on the carbohydrate availability of plant tissues and thus on how photosynthesis is affected by this environmental factors.

  9. Wood properties of trembling aspen and paper birch after 5 years of exposure to elevated concentrations of CO(2) and O(3).

    PubMed

    Kostiainen, Katri; Kaakinen, Seija; Warsta, Elina; Kubiske, Mark E; Nelson, Neil D; Sober, Jaak; Karnosky, David F; Saranpää, Pekka; Vapaavuori, Elina

    2008-05-01

    We investigated the interactive effects of elevated concentrations of carbon dioxide ([CO(2)]) and ozone ([O(3)]) on radial growth, wood chemistry and structure of five 5-year-old trembling aspen (Populus tremuloides Michx.) clones and the wood chemistry of paper birch (Betula papyrifera Marsh.). Material for the study was collected from the Aspen FACE (free-air CO(2) enrichment) experiment in Rhinelander, WI, where the saplings had been exposed to four treatments: control, elevated [CO(2)] (560 ppm), elevated [O(3)] (1.5 x ambient) and their combination for five growing seasons. Wood properties of both species were altered in response to exposure to the treatments. In aspen, elevated [CO(2)] decreased uronic acids (constituents of, e.g., hemicellulose) and tended to increase stem diameter. In response to elevated [O(3)] exposure, acid-soluble lignin concentration decreased and vessel lumen diameter tended to decrease. Elevated [O(3)] increased the concentration of acetone-soluble extractives in paper birch, but tended to decrease the concentration of these compounds in aspen. In paper birch, elevated [CO(2)] decreased and elevated [O(3)] increased starch concentration. The responses of wood properties to 5 years of fumigation differed from those previously reported after 3 years of fumigation. PMID:18316312

  10. CO2 laser cleaning of black deposits formed during the excimer laser etching of polyimide in air

    NASA Astrophysics Data System (ADS)

    Koren, G.; Donelon, J. J.

    1988-01-01

    Pulsed CO2 laser cleaning of black debris formed during the excimer laser ablation of polyimide in air is demonstrated. The 10.6 μm CO2 laser radiation is strongly absorbed in the debris but only weakly absorbed in polyimide thus enabling the clean removal of the debris without damaging the polyimide.

  11. Effects of impregnated metal ions on air/CO2-gasification of woody biomass.

    PubMed

    Hurley, Scott; Li, Hanning; Xu, Chunbao Charles

    2010-12-01

    Several impregnated metal ions (Fe (III), Co (II), Ni (II), and Ru (IV)) and a raw iron ore (natural limonite) were examined as catalysts for gasification of pine sawdust in air/CO(2) at 700 and 800 degrees C. The yields of char and tar both increased with increasing CO(2) content in the feed gas. All the impregnated metal ions, in particular Ni (II), Co (II) and Ru (IV), were very effective for promoting biomass gasification in CO(2), leading to greatly reduced yields of tar and char accompanied by significantly enhanced formation of CO and H(2). At 800 degrees C, the impregnation of Fe (III), Ni (II), Co (II) or Ru (IV) led to almost complete conversion of the solid biomass into gas/liquid products, producing an extremely low char yield (<1-4 wt.%), and a very high yield of combustible gas (from 51.7 wt.% for Fe to 84 wt.% for Ru). The tar yield reduced from 32.1 wt.% without catalyst to 19-27 wt.% with the impregnated metal ions. PMID:20667716

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

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

    2016-09-01

    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. PMID:27551079

  14. Micrometeorological survey of air-sea ice CO2 fluxes in arctic coastal waters

    NASA Astrophysics Data System (ADS)

    Heinesch, Bernard; Tison, Jean-Louis; Carnat, Gauthier; Heicken, Hajo; Geilfus, Nicolas-Xavier; Goosens, Thomas; Papakyriakou, Tim; Yernaux, Michel; Delille, Bruno

    2010-05-01

    We carried out a 6 month study that aimed to robustly track CO2 exchange between land-fast sea-ice and the atmosphere during the winter and spring season. A meteorological mast equipped for eddy-covariance measurements was installed on land-fast sea-ice near Barrow (Alaska), 1 km off the coast, from the end of January 2009 to the beginning of June 2009, before ice break-up. These data were supported by continuous measurements of solar radiation, snow depth, ice thickness and temperature profile in the ice. Biogeochemical data necessary for the understanding of the CO2 dynamics in sea-ice were obtained through discrete ice coring. Two regimes were detected for the CO2 exchanges linked with the status of the sea-ice: a winter regime and a spring summer regime. From 27 of March onwards brine volume at the sea ice-snow interface was above the threshold of permeability for liquid according to Golden et al (1998). During this period, we observed some conspicuous CO2 fluxes events tightly linked to wind speed. The flux was directed from the sea-ice to the atmosphere and reached up to 0.6 umol m-2 s-1 (51.8 mmol m-2 d-1). This flux to the atmosphere is expected as sea-ice at the air interface is permeable during a large part of the period and brines are oversaturated compared to the atmosphere. CO2 may accumulate in the snow layer which thus acts as a buffer that is flushed under occurrence of high wind speeds and associated pressure pumping. During the spring-summer period i.e. from 27 of April onwards, we observed a marked increase in sea ice temperature. Temperature profiles suggest that convective events occurred within the ice cover between April 27 and May 05. Within these convective events, two regimes were observed. First, for a period of 5 days, pCO2 was still above the threshold of saturation and CO2 fluxes were still mainly positive but lower than in the winter period, ranging from 0.1 to 0.2 umol m-2 s-1. This flux was only moderately controlled by windspeed

  15. Algal evolution in relation to atmospheric CO2: carboxylases, carbon-concentrating mechanisms and carbon oxidation cycles

    PubMed Central

    Raven, John A.; Giordano, Mario; Beardall, John; Maberly, Stephen C.

    2012-01-01

    Oxygenic photosynthesis evolved at least 2.4 Ga; all oxygenic organisms use the ribulose bisphosphate carboxylase-oxygenase (Rubisco)–photosynthetic carbon reduction cycle (PCRC) rather than one of the five other known pathways of autotrophic CO2 assimilation. The high CO2 and (initially) O2-free conditions permitted the use of a Rubisco with a high maximum specific reaction rate. As CO2 decreased and O2 increased, Rubisco oxygenase activity increased and 2-phosphoglycolate was produced, with the evolution of pathways recycling this inhibitory product to sugar phosphates. Changed atmospheric composition also selected for Rubiscos with higher CO2 affinity and CO2/O2 selectivity correlated with decreased CO2-saturated catalytic capacity and/or for CO2-concentrating mechanisms (CCMs). These changes increase the energy, nitrogen, phosphorus, iron, zinc and manganese cost of producing and operating Rubisco–PCRC, while biosphere oxygenation decreased the availability of nitrogen, phosphorus and iron. The majority of algae today have CCMs; the timing of their origins is unclear. If CCMs evolved in a low-CO2 episode followed by one or more lengthy high-CO2 episodes, CCM retention could involve a combination of environmental factors known to favour CCM retention in extant organisms that also occur in a warmer high-CO2 ocean. More investigations, including studies of genetic adaptation, are needed. PMID:22232762

  16. Algal evolution in relation to atmospheric CO2: carboxylases, carbon-concentrating mechanisms and carbon oxidation cycles.

    PubMed

    Raven, John A; Giordano, Mario; Beardall, John; Maberly, Stephen C

    2012-02-19

    Oxygenic photosynthesis evolved at least 2.4 Ga; all oxygenic organisms use the ribulose bisphosphate carboxylase-oxygenase (Rubisco)-photosynthetic carbon reduction cycle (PCRC) rather than one of the five other known pathways of autotrophic CO(2) assimilation. The high CO(2) and (initially) O(2)-free conditions permitted the use of a Rubisco with a high maximum specific reaction rate. As CO(2) decreased and O(2) increased, Rubisco oxygenase activity increased and 2-phosphoglycolate was produced, with the evolution of pathways recycling this inhibitory product to sugar phosphates. Changed atmospheric composition also selected for Rubiscos with higher CO(2) affinity and CO(2)/O(2) selectivity correlated with decreased CO(2)-saturated catalytic capacity and/or for CO(2)-concentrating mechanisms (CCMs). These changes increase the energy, nitrogen, phosphorus, iron, zinc and manganese cost of producing and operating Rubisco-PCRC, while biosphere oxygenation decreased the availability of nitrogen, phosphorus and iron. The majority of algae today have CCMs; the timing of their origins is unclear. If CCMs evolved in a low-CO(2) episode followed by one or more lengthy high-CO(2) episodes, CCM retention could involve a combination of environmental factors known to favour CCM retention in extant organisms that also occur in a warmer high-CO(2) ocean. More investigations, including studies of genetic adaptation, are needed. PMID:22232762

  17. Soil-specific C and N responses to changing atmospheric CO2 concentrations in a mesic grassland ecosystem

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Long-term increases in ecosystem productivity under elevated atmospheric CO2 can be expected only when the increased assimilation of carbon (C) is not limited by soil nutrients, namely nitrogen (N). We examined how changes in atmospheric CO2 concentrations affect C and N dynamics in a mesic grasslan...

  18. The Molecular Bronchoscope: A Tool for Measurement of Spatially Dependent CO2 Concentrations in the Lungs.

    PubMed

    Ciaffoni, Luca; Couper, John H; Richmond, Graham; Hancock, Gus; Ritchie, Grant A D

    2016-09-01

    Respiratory physicians use bronchoscopy for visual assessment of the lungs' topography and collecting tissue samples for external analysis. We propose a novel bronchoscope tool that would enable spatially dependent measurements of the functioning of the lungs by determining local concentrations of carbon dioxide, which will be produced by healthy parts of the lung at rates that are higher than from portions where gas exchange is impaired. The gas analyzer is based on a compact laser absorption spectrometer making use of fiber optics for delivery and return of low intensity diode laser radiation to and from the measurement chamber at the distal end of a flexible conduit. The appropriate optical wavelength was chosen such that light is selectively absorbed only by gaseous CO2. The optical absorption takes place over a short path (8.8 mm) within a rigid, 12 mm long, perforated probe tip. Wavelength modulation spectroscopy was adopted as the analytical technique to reduce the noise on the optical signal and yield measurements of relative CO2 concentration every 180 ms with a precision as low as 600 part-per-million by volume. The primary objective of such a device is to see if additional spatial information about the lungs functionality can be gathered, which will complement visual observation. PMID:27487178

  19. Enhanced sea-air CO2 exchange influenced by a tropical depression in the South China Sea

    NASA Astrophysics Data System (ADS)

    Sun, Qingyang; Tang, DanLing; Legendre, Louis; Shi, Ping

    2014-10-01

    Ship measurements made 2 days after the passage of a tropical depression (TD) in the South China Sea (SCS, April 2011) showed two contrasted responses of the partial pressure of CO2 at sea surface (pCO2,sw). In low sea-surface salinity (SSS) water, pCO2,sw was low (349 ± 7 μatm), and the area was a carbon sink (-4.7 ± 1.8 mmol CO2 m-2 d-1), whereas in water with high SSS and chlorophyll a and low dissolved oxygen and sea surface temperature, pCO2,sw was higher than for normal SCS water (376 ± 8 versus 362 ± 4 μatm) and the area was a carbon source (1.2 ± 3.1 mmol CO2 m-2 d-1). Satellite data showed two large areas of low SSS before the TD, which were likely influenced by rainfall, and these areas were considered to have low pCO2,sw because of their low SSS. The high pCO2,sw after the TD is explained by the uplifting to the surface of deeper and CO2-rich water, due to winds accompanied by the TD. The difference in sea-air CO2 flux between the TD-affected area and the lower-SSS water was 1.99 + 4.70 = 6.7 mmol CO2 m-2 d-1, indicating a 100% change caused by the TD compared to the average seasonal value in spring in southern SCS (3.3 ± 0.3 mmol CO2 m-2 d-1). Undersaturation of CO2 prior to the TD due to dilution by freshwater and the preexisting cold eddy, and slow translation speed of the TD, are considered to account for the CO2 flux change.

  20. Decreases in stomatal conductance of soybean under open-air elevation of [CO2] are closely coupled with decreases in ecosystem evapotranspiration.

    PubMed

    Bernacchi, Carl J; Kimball, Bruce A; Quarles, Devin R; Long, Stephen P; Ort, Donald R

    2007-01-01

    Stomatal responses to atmospheric change have been well documented through a range of laboratory- and field-based experiments. Increases in atmospheric concentration of CO(2) ([CO(2)]) have been shown to decrease stomatal conductance (g(s)) for a wide range of species under numerous conditions. Less well understood, however, is the extent to which leaf-level responses translate to changes in ecosystem evapotranspiration (ET). Since many changes at the soil, plant, and canopy microclimate levels may feed back on ET, it is not certain that a decrease in g(s) will decrease ET in rain-fed crops. To examine the scaling of the effect of elevated [CO(2)] on g(s) at the leaf to ecosystem ET, soybean (Glycine max) was grown in field conditions under control (approximately 375 micromol CO(2) mol(-1) air) and elevated [CO(2)] (approximately 550 micromol mol(-1)) using free air CO(2) enrichment. ET was determined from the time of canopy closure to crop senescence using a residual energy balance approach over four growing seasons. Elevated [CO(2)] caused ET to decrease between 9% and 16% depending on year and despite large increases in photosynthesis and seed yield. Ecosystem ET was linked with g(s) of the upper canopy leaves when averaged across the growing seasons, such that a 10% decrease in g(s) results in a 8.6% decrease in ET; this relationship was not altered by growth at elevated [CO(2)]. The findings are consistent with model and historical analyses that suggest that, despite system feedbacks, decreased g(s) of upper canopy leaves at elevated [CO(2)] results in decreased transfer of water vapor to the atmosphere. PMID:17114275

  1. Decreases in Stomatal Conductance of Soybean under Open-Air Elevation of [CO2] Are Closely Coupled with Decreases in Ecosystem Evapotranspiration12[W][OA

    PubMed Central

    Bernacchi, Carl J.; Kimball, Bruce A.; Quarles, Devin R.; Long, Stephen P.; Ort, Donald R.

    2007-01-01

    Stomatal responses to atmospheric change have been well documented through a range of laboratory- and field-based experiments. Increases in atmospheric concentration of CO2 ([CO2]) have been shown to decrease stomatal conductance (gs) for a wide range of species under numerous conditions. Less well understood, however, is the extent to which leaf-level responses translate to changes in ecosystem evapotranspiration (ET). Since many changes at the soil, plant, and canopy microclimate levels may feed back on ET, it is not certain that a decrease in gs will decrease ET in rain-fed crops. To examine the scaling of the effect of elevated [CO2] on gs at the leaf to ecosystem ET, soybean (Glycine max) was grown in field conditions under control (approximately 375 μmol CO2 mol−1 air) and elevated [CO2] (approximately 550 μmol mol−1) using free air CO2 enrichment. ET was determined from the time of canopy closure to crop senescence using a residual energy balance approach over four growing seasons. Elevated [CO2] caused ET to decrease between 9% and 16% depending on year and despite large increases in photosynthesis and seed yield. Ecosystem ET was linked with gs of the upper canopy leaves when averaged across the growing seasons, such that a 10% decrease in gs results in a 8.6% decrease in ET; this relationship was not altered by growth at elevated [CO2]. The findings are consistent with model and historical analyses that suggest that, despite system feedbacks, decreased gs of upper canopy leaves at elevated [CO2] results in decreased transfer of water vapor to the atmosphere. PMID:17114275

  2. The Influence of Atmospheric CO2 Concentration and Climate Variability on Amazon Tropical Forest

    NASA Astrophysics Data System (ADS)

    Castanho, A. D. D. A.; Galbraith, D.; Zhang, K.; Coe, M. T.; Costa, M. H.; Moorcroft, P. R.

    2014-12-01

    Tropical forests are important regulators of atmospheric CO2 concentration and any change in tropical forest C balance will directly affect global climate. Long term studies from undisturbed old-growth forest monitoring sites distributed across Amazonia have presented an overall increase in aboveground biomass in the last decades, and the increase in atmospheric CO2 concentrations is considered the main driver for this observed carbon sink. The main goal of this work was to use simulations from dynamic global vegetation models (DGVM) to explore how much of the observed historical (1970-2008) increase in biomass in undisturbed tropical forest in Amazonia could be attributed to the CO2 fertilization effect or associated to climate change. We compared simulated biomass and productivity from three DGVMs (IBIS, ED2 and JULES) with observations from forest plots (RAINFOR). The analyses helped clarify the variability of historical and potential future simulations.The analyses showed that models shared similar results and deficiencies. The three models represented the two major model types: conventional dynamic global vegetation models that simulate community dynamics and competition between plant functional types (PFTs) using an aggregated 'big-leaf' representation (IBIS and Jules), and a size-and-age structured terrestrial ecosystem model that captures individual scale dynamics and competition (ED2). In general, the ED2 model results were more sensitive to climate, but all models greatly underestimate the impact of extreme climatic events (e.g. drought) compared to field data.All the DGVM's studied tend to simulate the average biomass well and to overestimate productivity of vegetation under current conditions. All the models presented very low spatial variability compared to field observation. The lack of spatial variability of biomass and productivity is attributed to the lack of nutrient and residence time spatial heterogeneity. All of the DGVMs results suggest that

  3. Effects of elevated atmospheric CO2 concentration on leaf dark respiration of Xanthium strumarium in light and in darkness.

    PubMed

    Wang, X; Lewis, J D; Tissue, D T; Seemann, J R; Griffin, K L

    2001-02-27

    Leaf dark respiration (R) is an important component of plant carbon balance, but the effects of rising atmospheric CO(2) on leaf R during illumination are largely unknown. We studied the effects of elevated CO(2) on leaf R in light (R(L)) and in darkness (R(D)) in Xanthium strumarium at different developmental stages. Leaf R(L) was estimated by using the Kok method, whereas leaf R(D) was measured as the rate of CO(2) efflux at zero light. Leaf R(L) and R(D) were significantly higher at elevated than at ambient CO(2) throughout the growing period. Elevated CO(2) increased the ratio of leaf R(L) to net photosynthesis at saturated light (A(max)) when plants were young and also after flowering, but the ratio of leaf R(D) to A(max) was unaffected by CO(2) levels. Leaf R(N) was significantly higher at the beginning but significantly lower at the end of the growing period in elevated CO(2)-grown plants. The ratio of leaf R(L) to R(D) was used to estimate the effect of light on leaf R during the day. We found that light inhibited leaf R at both CO(2) concentrations but to a lesser degree for elevated (17-24%) than for ambient (29-35%) CO(2)-grown plants, presumably because elevated CO(2)-grown plants had a higher demand for energy and carbon skeletons than ambient CO(2)-grown plants in light. Our results suggest that using the CO(2) efflux rate, determined by shading leaves during the day, as a measure for leaf R is likely to underestimate carbon loss from elevated CO(2)-grown plants. PMID:11226264

  4. LASER BIOLOGY AND MEDICINE: Laser analysis of the 13C/12C isotope ratio in CO2 in exhaled air

    NASA Astrophysics Data System (ADS)

    Stepanov, E. V.

    2002-11-01

    Tunable diode lasers (TDLs) are applied to the diagnostics of gastroenterological diseases using respiratory tests and preparations enriched with the stable 13C isotope. This method of the analysis of the 13C/12C isotope ratio in CO2 in exhaled air is based on the selective measurement of the resonance absorption at the vibrational — rotational structure of 12CO2 and 13CO2. The CO2 transmission spectra in the region of 4.35 μm were measured with a PbEuSe double-heterostructure TDL. The accuracy of carbon isotope ratio measurements in CO2 of exhaled air performed with the TDL was ~0.5%. The data of clinical tests of the developed laser-based analyser are presented.

  5. [Effects of simulated elevation of atmospheric CO2 concentration on the physiological features of spring phytoplankton in Taihu Lake].

    PubMed

    Zhao, Xu-Hui; Tang, Long-Sheng; Shi, Xiao-Li; Yang, Zhou; Kong, Fan-Xiang

    2013-06-01

    To disclose the impact of different CO2 concentrations (270 x 10(-6), 380 x 10(-6), 750 x 10(-6)) on physiological features of spring phytoplankton, an in situ simulated experiment was carried out in Meiliang Bay of Taihu Lake from 29 April to 26 May in 2012. The results showed that atmospheric CO2 elevation would significantly alter the pH value and carbonate chemical environments of Taihu Lake, resulting in weakening the advantages of carbon concentrating mechanism (CCM) of phytoplankton. Phytoplankton in Taihu Lake tended to use more dissolved CO2 (CO2, aq) due to the deliberate CO2 sequestration under the high CO2 level treatment. When atmospheric CO2 concentration doubles at the end of century, the maximum growth rate constant of phytoplankton (U(max)), NPP, chlorophyll a (Chl-a)-specific NPP would increase by 63.1%, 69.6% and 33.8%, respectively. Atmospheric CO2 elevation promoted the maximum photosynthetic efficiency of chlorophyta and bacillariophyta in Taihu Lake and its promotion effect on bacillariophyta was more notable than that on chlorophyta. However, it did not change the photosynthetic efficiency of cyanobacteria which was very low in spring. Meanwhile, the stoichiometry value of phytoplankton changed significantly due to the CO2 elevation, as phytoplankton cells assimilated more C and N, but less P under the treatment of high CO2 level. Our results indicated the enhanced CO2 level could dramatically change the physiological features of phytoplankton. This information would help us to understand and predict the response of phytoplankton in Taihu Lake to the future climate change. PMID:23947023

  6. Temporal variations in air-sea CO2 exchange near large kelp beds near San Diego, California

    NASA Astrophysics Data System (ADS)

    Ikawa, Hiroki; Oechel, Walter C.

    2015-01-01

    study presents nearly continuous air-sea CO2 flux for 7 years using the eddy covariance method for nearshore water near San Diego, California, as well as identifying environmental processes that appear to control temporal variations in air-sea CO2 flux at different time scales using time series decomposition. Monthly variations in CO2 uptake are shown to be positively influenced by photosynthetically active photon flux density (PPFD) and negatively related to wind speeds. In contrast to the monthly scale, wind speeds often influenced CO2 uptake positively on an hourly scale. Interannual variations in CO2 flux were not correlated with any independent variables, but did reflect surface area of the adjacent kelp bed in the following year. Different environmental influences on CO2 flux at different temporal scales suggest the importance of long-term flux monitoring for accurately identifying important environmental processes for the coastal carbon cycle. Overall, the study area was a strong CO2 sink into the sea (CO2 flux of ca. -260 g C m-2 yr-1). If all coastal areas inhabited by macrophytes had a similar CO2 uptake rate, the net CO2 uptake from these areas alone would roughly equal the net CO2 sink estimated for the entire global coastal ocean to date. A similar-strength CO2 flux, ranging between -0.09 and -0.01 g C m-2 h-1, was also observed over another kelp bed from a pilot study of boat-based eddy covariance measurements.

  7. Analysis of Changes in Biochemical Composition Under Free-Air CO2 enrichment by 13C Nuclear Magnetic Resonance: Leaf Litter, Roots, and Soils From Oak Ridge

    NASA Astrophysics Data System (ADS)

    Hockaday, W. C.; Masiello, C. A.; Baldock, J. A.; Iversen, C. M.; Norby, R. J.

    2007-12-01

    Changes in plant biochemistry as a result of increasing atmospheric carbon dioxide concentration [CO2] influence the cycling of the terrestrial carbon pool and thereby constitute a climate feedback. We have investigated molecular-level changes in the chemical composition of the organic carbon pool of a deciduous forest in Oak Ridge, Tennessee, after 9 years of free-air CO2 enrichment. We employ a novel approach based upon solid-state 13C nuclear magnetic resonance (NMR) analysis and application of a molecular mixing model. This method generates quantitative estimates of total lipids, proteins, carbohydrates, and lignin. 13C NMR spectra were acquired for acid-insoluble soil organic matter from depths of 0 - 5 cm and 5 - 15 cm in two ambient and two elevated [CO2] treatments. In the upper 5 cm, elevated [CO2] soils show a 7% increase in lignin, while lipids and proteins decrease by approximately 10%. Below 5 cm, soil lipid content decreased by 15% relative to ambient [CO2] soils. Changes in the composition of the SOM pool may be attributed to changes in plant biochemistry under elevated [CO2]. Therefore we have performed 13C NMR analysis of major aboveground and belowground biomass inputs: senesced leaves and fine roots (<1 mm diameter). Significant [CO2] effects on root chemistry are observed. Based upon these data, we are able to make a preliminary assessment of the contributions of leaf C and root C to changes in the molecular composition of the SOM pool.

  8. Experimental study on CO and CO2 emissions from spontaneous heating of coals at varying temperatures and O2 concentrations

    PubMed Central

    Yuan, Liming; Smith, Alex C.

    2015-01-01

    Laboratory experiments were conducted to investigate carbon monoxide (CO) and carbon dioxide (CO2) emissions from spontaneous heating of three U.S. coal samples in an isothermal oven at temperatures between 50 and 110 °C. The oxygen (O2) concentration of an oxygen/nitrogen (N2) mixture flowing through the coal sample was 3, 5, 10, 15, and 21%, respectively. The temperature at the center of the coal sample was continuously monitored, while the CO, CO2, and O2 concentrations of the exit gas were continuously measured. The results indicate that the CO and CO2 concentrations and the CO/CO2 ratio increased when the initial temperature was increased. As the inlet O2 concentration increased, the CO and CO2 concentrations increased, while the CO/CO2 ratios tended to converge to the same value. The ratio of CO/CO2 was found to be independent of coal properties, approaching a constant value of 0.2. The maximum CO production rate correlated well with the maximum coal temperature rise. The apparent order of reaction for coal oxidation was estimated to be between 0.52 and 0.72. The experimental results in this study could be used for early detection and evaluation of a spontaneous heating in underground coal mines. PMID:26203211

  9. Variations in rn and CO2 Soil Gas Concentrations in Karabayir Eskisehir-Turkey and Their Correlations with Earthquakes

    NASA Astrophysics Data System (ADS)

    Yasin, Didem; Hilmi Gülbay, Ahmet; Yüce, Galip; Durgut, Aykut; Oruç, Cemal

    2016-04-01

    Variations in radon and CO2 gas concentrations of soil relations to earthquakes take attention of many researchers. The aim of this study is to monitor changes in soil radon and CO2 gas concentrations and to search possible anomalies originated from the seismicity in the vicinity of Eskisehir. Eskisehir is located between Aegean-Western Anatolian block where the extensional regime is present and the snistrial strike-slip fault zone, with a normal component, belonging to Central Anatolian Block on which the compressional forces are effective. Radon and CO2 gas concentrations in soil were daily measured for about 3 months in 2015. Meteorological parameters (barometric pressure, temperature, rain and humidity) and all soil gasdata were correlated with the seismicity occured in 17-110 km distance from the soil gas measurement location during the same period. According to the first results, generally concentrations of Rn and CO2 began to decrease before earthquakes and CO2 and radon concentrations are linear which means. CO2 can be considered as acarrier gas for radon. Keywords: radon, CO2, Eskisehir, earthquake, soil

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

    PubMed

    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. PMID:24316065

  11. Photosynthetic fractionation of 13C and concentrations of dissolved CO2 in the central equatorial Pacific during the last 255,000 years

    NASA Technical Reports Server (NTRS)

    Jasper, J. P.; Hayes, J. M.; Mix, A. C.; Prahl, F. G.

    1994-01-01

    Carbon isotopically based estimates of CO2 levels have been generated from a record of the photosynthetic fractionation of 13C [is equivalent to epsilon(p)] in a central equatorial Pacific sediment core that spans the last approximately 255 ka. Contents of 13C in phytoplanktonic biomass were determined by analysis of C37 alkadienones. These compounds are exclusive products of Prymnesiophyte algae which at present grow most abundantly at depths of 70-90 m in the central equatorial Pacific. A record of the isotopic composition of dissolved CO2 was constructed from isotopic analyses of the planktonic foraminifera Neogloboquadrina dutertrei, which calcifies at 70-90 m in the same region. Values of epsilon(p), derived by comparison of the organic and inorganic delta values, were transformed to yield concentrations of dissolved CO2 [is equivalent to c(e)] based on a new, site-specific calibration of the relationship between epsilon(p) and c(e). The calibration was based on reassessment of existing epsilon(p) versus c(e) data, which support a physiologically based model in which epsilon(p) is inversely related to c(e). Values of PCO2, the partial pressure of CO2 that would be in equilibrium with the estimated concentrations of dissolved CO2, were calculated using Henry's law and the temperature determined from the alkenone-unsaturation index U(K/37). Uncertainties in these values arise mainly from uncertainties about the appropriateness (particularly over time) of the site-specific relationship between epsilon(p) and 1/c(e). These are discussed in detail and it is concluded that the observed record of epsilon(p) most probably reflects significant variations in delta pCO2, the ocean-atmosphere disequilibrium, which appears to have ranged from approximately 110 microatmospheres during glacial intervals (ocean > atmosphere) to approximately 60 microatmospheres during interglacials. Fluxes of CO2 to the atmosphere would thus have been significantly larger during glacial

  12. An inverse modeling approach for tree-ring-based climate reconstructions under changing atmospheric CO2 concentrations

    NASA Astrophysics Data System (ADS)

    Boucher, É.; Guiot, J.; Hatté, C.; Daux, V.; Danis, P.-A.; Dussouillez, P.

    2013-11-01

    Over the last decades, dendroclimatologists have relied upon linear transfer functions to reconstruct historical climate. Transfer functions need to be calibrated using recent data from periods where CO2 concentrations reached unprecedented levels (near 400 ppm). Based on these transfer functions, dendroclimatologists must then reconstruct a different past, a past where CO2 concentrations were much below 300 ppm. However, relying upon transfer functions calibrated in this way may introduce an unanticipated bias in the reconstruction of past climate, particularly if CO2 levels have had a noticeable fertilizing effect since the beginning of the industrial era. As an alternative to the transfer function approach, we run the MAIDENiso ecophysiological model in an inverse mode to link together climatic variables, atmospheric CO2 concentrations and tree growth parameters. Our approach endeavors to find the optimal combination of meteorological conditions that best simulate observed tree ring patterns. We test our approach in the Fontainebleau forest (France). By comparing two different CO2 scenarios, we present evidence that increasing CO2 concentrations have had a slight, yet significant, effect on reconstruction results. We demonstrate that higher CO2 concentrations augment the efficiency of water use by trees, therefore favoring the reconstruction of a warmer and drier climate. Under elevated CO2 concentrations, trees close their stomata and need less water to produce the same amount of wood. Inverse process-based modeling represents a powerful alternative to the transfer function technique, especially for the study of divergent tree-ring-to-climate relationships. The approach has several advantages, most notably its ability to distinguish between climatic effects and CO2 imprints on tree growth. Therefore our method produces reconstructions that are less biased by anthropogenic greenhouse gas emissions and that are based on sound ecophysiological knowledge.

  13. Effects of elevated atmospheric CO2 concentration on the nutrient uptake characteristics of Japanese larch (Larix kaempferi).

    PubMed

    Shinano, Takuro; Yamamoto, Takuya; Tawaraya, Keitaro; Tadokoro, Masaru; Koike, Takayoshi; Osaki, Mitsuru

    2007-01-01

    We evaluated the response of Japanese larch (Larix kaempferi Sieb. & Zucc.) to elevated atmospheric CO(2) concentration ([CO(2)]) (689 +/- 75 ppm in 2002 and 697 +/- 90 ppm in 2003) over 2 years in a field experiment with open-top chambers. Root activity was assessed as nitrogen, phosphorus and potassium uptake rates estimated from successive measurements of absorbed amounts. Dry matter production of whole plants was unaffected by elevated [CO(2)] in the first year of treatment, but increased significantly in response to elevated [CO(2)] in the second year. In contrast, elevated [CO(2)] increased the root to shoot ratio and fine root dry mass in the first year, but not in the second year. Elevated [CO(2)] had no effect on tissue N, P and K concentrations. Uptake rates of N, P and K correlated with whole-plant relative growth rates, but were unaffected by growth [CO(2)], as was ectomycorrhizal colonization, a factor assumed to be important for nutrient uptake in trees. We conclude that improved growth of Larix kaempferi in response to elevated [CO(2)] is accompanied by increased root biomass, but not by increased root activity. PMID:17169911

  14. The Minimal CO2-Concentrating Mechanism of Prochlorococcus spp. MED4 Is Effective and Efficient1[W][OPEN

    PubMed Central

    Young, Jodi N.; Tansik, Anna L.; Binder, Brian J.

    2014-01-01

    As an oligotrophic specialist, Prochlorococcus spp. has streamlined its genome and metabolism including the CO2-concentrating mechanism (CCM), which serves to elevate the CO2 concentration around Rubisco. The genomes of Prochlorococcus spp. indicate that they have a simple CCM composed of one or two HCO3− pumps and a carboxysome, but its functionality has not been examined. Here, we show that the CCM of Prochlorococcus spp. is effective and efficient, transporting only two molecules of HCO3− per molecule of CO2 fixed. A mechanistic, numerical model with a structure based on the CCM components present in the genome is able to match data on photosynthesis, CO2 efflux, and the intracellular inorganic carbon pool. The model requires the carboxysome shell to be a major barrier to CO2 efflux and shows that excess Rubisco capacity is critical to attaining a high-affinity CCM without CO2 recovery mechanisms or high-affinity HCO3− transporters. No differences in CCM physiology or gene expression were observed when Prochlorococcus spp. was fully acclimated to high-CO2 (1,000 µL L−1) or low-CO2 (150 µL L−1) conditions. Prochlorococcus spp. CCM components in the Global Ocean Survey metagenomes were very similar to those in the genomes of cultivated strains, indicating that the CCM in environmental populations is similar to that of cultured representatives. PMID:25315602

  15. Development of a Prototype Algal Reactor for Removing CO2 from Cabin Air

    NASA Technical Reports Server (NTRS)

    Patel, Vrajen; Monje, Oscar

    2013-01-01

    Controlling carbon dioxide in spacecraft cabin air may be accomplished using algal photobioreactors (PBRs). The purpose of this project was to evaluate the use of a commercial microcontroller, the Arduino Mega 2560, for measuring key photioreactor variables: dissolved oxygen, pH, temperature, light, and carbon dioxide. The Arduino platform is an opensource physical computing platform composed of a compact microcontroller board and a C++/C computer language (Arduino 1.0.5). The functionality of the Arduino platform can be expanded by the use of numerous add-ons or 'shields'. The Arduino Mega 2560 was equipped with the following shields: datalogger, BNC shield for reading pH sensor, a Mega Moto shield for controlling CO2 addition, as well as multiple sensors. The dissolved oxygen (DO) probe was calibrated using a nitrogen bubbling technique and the pH probe was calibrated via an Omega pH simulator. The PBR was constructed using a 2 L beaker, a 66 L box for addition of CO2, a micro porous membrane, a diaphragm pump, four 25 watt light bulbs, a MasterFiex speed controller, and a fan. The algae (wild type Synechocystis PCC6803) was grown in an aerated flask until the algae was dense enough to used in the main reactor. After the algae was grown, it was transferred to the 2 L beaker where CO2 consumption and O2 production was measured using the microcontroller sensor suite. The data was recorded via the datalogger and transferred to a computer for analysis.

  16. Concentration dependent refractive index of CO2/CH4 mixture in gaseous and supercritical phase.

    PubMed

    Giraudet, C; Marlin, L; Bégué, D; Croccolo, F; Bataller, H

    2016-04-01

    Carbon dioxide (CO2)/methane (CH4) binary mixtures are investigated at pressure values up to 20 MPa at 303 K in order to investigate the pressure dependence of the optical concentration contrast factor, ∂n/∂cP,T, through gaseous and supercritical phase. Refractive index is measured by means of a Michelson interferometer. Refractivities of the mixtures are found in good agreement with Lorentz-Lorenz predictions after density calculations by means of the AGA8-DC92 equation of state. Experimental polarizabilities of pure fluids are compared to quantum calculations of monomers and dimers for each pressure; it results that the quantity of dimers is small in the investigated thermodynamic conditions. Finally, by extending our experimental database with numerical simulations, we evidence that ∂n/∂cP,T presents a critical enhancement similar to heat capacity. PMID:27059567

  17. Concentration dependent refractive index of CO2/CH4 mixture in gaseous and supercritical phase

    NASA Astrophysics Data System (ADS)

    Giraudet, C.; Marlin, L.; Bégué, D.; Croccolo, F.; Bataller, H.

    2016-04-01

    Carbon dioxide (CO2)/methane (CH4) binary mixtures are investigated at pressure values up to 20 MPa at 303 K in order to investigate the pressure dependence of the optical concentration contrast factor, (" separators=" ∂ n / ∂ c ) P , T , through gaseous and supercritical phase. Refractive index is measured by means of a Michelson interferometer. Refractivities of the mixtures are found in good agreement with Lorentz-Lorenz predictions after density calculations by means of the AGA8-DC92 equation of state. Experimental polarizabilities of pure fluids are compared to quantum calculations of monomers and dimers for each pressure; it results that the quantity of dimers is small in the investigated thermodynamic conditions. Finally, by extending our experimental database with numerical simulations, we evidence that (" separators=" ∂ n / ∂ c ) P , T presents a critical enhancement similar to heat capacity.

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

    PubMed

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

    2009-03-01

    Analytical details for 13C and 18O isotope analyses of atmospheric CO2 in large air samples are given. The large air samples of nominally 300 L were collected during the passenger aircraft-based atmospheric chemistry research project CARIBIC and analyzed for a large number of trace gases and isotopic composition. In the laboratory, an ultra-pure and high efficiency extraction system and high-quality isotope ratio mass spectrometry were used. Because direct comparison with other laboratories was practically impossible, the extraction and measurement procedures were tested in considerable detail. Extracted CO2 was measured twice vs. two different working reference CO2 gases of different isotopic composition. The two data sets agree well and their distributions can be used to evaluate analytical errors due to isotope measurement, ion corrections, internal calibration consistency, etc. The calibration itself is based on NBS-19 and also verified using isotope analyses on pure CO2 gases (NIST Reference Materials (RMs) and NARCIS CO2 gases). The major problem encountered could be attributed to CO2-water exchange in the air sampling cylinders. This exchange decreased over the years. To exclude artefacts due to such isotopic exchange, the data were filtered to reject negative delta18O(CO2) values. Examples of the results are given. PMID:19219897

  19. Biomass Energy for Transport and Electricity: Large scale utilization under low CO2 concentration scenarios

    SciTech Connect

    Luckow, Patrick; Wise, Marshall A.; Dooley, James J.; Kim, Son H.

    2010-01-25

    This paper examines the potential role of large scale, dedicated commercial biomass energy systems under global climate policies designed to stabilize atmospheric concentrations of CO2 at 400ppm and 450ppm. We use an integrated assessment model of energy and agriculture systems to show that, given a climate policy in which terrestrial carbon is appropriately valued equally with carbon emitted from the energy system, biomass energy has the potential to be a major component of achieving these low concentration targets. The costs of processing and transporting biomass energy at much larger scales than current experience are also incorporated into the modeling. From the scenario results, 120-160 EJ/year of biomass energy is produced by midcentury and 200-250 EJ/year by the end of this century. In the first half of the century, much of this biomass is from agricultural and forest residues, but after 2050 dedicated cellulosic biomass crops become the dominant source. A key finding of this paper is the role that carbon dioxide capture and storage (CCS) technologies coupled with commercial biomass energy can play in meeting stringent emissions targets. Despite the higher technology costs of CCS, the resulting negative emissions used in combination with biomass are a very important tool in controlling the cost of meeting a target, offsetting the venting of CO2 from sectors of the energy system that may be more expensive to mitigate, such as oil use in transportation. The paper also discusses the role of cellulosic ethanol and Fischer-Tropsch biomass derived transportation fuels and shows that both technologies are important contributors to liquid fuels production, with unique costs and emissions characteristics. Through application of the GCAM integrated assessment model, it becomes clear that, given CCS availability, bioenergy will be used both in electricity and transportation.

  20. Stable carbon isotope composition and concentrations of CO 2 and CH 4 in the deep catotelm of a peat bog

    NASA Astrophysics Data System (ADS)

    Steinmann, Philipp; Eilrich, Bernd; Leuenberger, Markus; Burns, Stephen J.

    2008-12-01

    Vertical profiles of concentration and C-isotopic composition of dissolved methane and carbon dioxide were observed over 26 months in the catotelm of a deep (6.5 m) peat bog in Switzerland. The dissolved concentrations of these gases increase with depth while CO 2 predominates over CH 4 (CO 2 ca. 5 times CH 4). This pattern can be reproduced by a reaction-advection-ebullition model, where CO 2 and CH 4 are formed in a ratio of 1:1. The less soluble methane is preferentially lost via outgassing (bubbles). The isotopic fractionation between CO 2 and CH 4 also increases with depth, with αC values ranging from 1.045 to 1.075. The isotopic composition of the gases traces the passage of respiration-derived CO 2 (from the near surface) through a shallow zone with methanogenesis of low isotopic fractionation (splitting of fermentation-derived acetate). This solution then moves through the catotelm, where methanogenesis occurs by CO 2 reduction (large isotopic fractionation). In the upper part of the catotelm the C-13-depleted respiration-derived CO 2 pool buffers the isotopic composition of CO 2; the δ 13C of CO 2 increases only slowly. At the same time strongly depleted CH 4 is formed as CO 2 reduction consumes the depleted CO 2. In the lower part of the catotelm, the respiration-derived CO 2 and shallow CH 4 become less important and CO 2 reduction is the dominant source of CO 2 and CH 4. Now, the δ 13C values of both gases increase until equilibrium is reached with respect to the isotopic composition of the substrate. Thus, the δ 13C values of methane reach a minimum at intermediate depth, and the deep methane has δ 13C values comparable to shallow methane. A simple mixing model for the isotopic evolution is suggested. Only minor changes of the observed patterns of methanogenesis (in terms of concentration and isotopic composition) occur over the seasons. The most pronounced of these is a slightly higher rate of acetate splitting in spring.

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

    USGS Publications Warehouse

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Five-years of microenvironment data along an urban-rural transect; temperature and CO2 concentrations in urban area at levels expected globally with climate change.

    SciTech Connect

    George, Kate; Ziska, Lewis H; Bunce, James A; Quebedeaux, Bruno

    2007-11-01

    The heat island effect and the high use of fossil fuels in large city centers is well documented, but by how much fossil fuel consumption is elevating atmospheric CO2 concentrations and whether elevations in both atmospheric CO2 and air temperature are consistent from year to year are less well known. Our aim was to record atmospheric CO2 concentrations, air temperature and other environmental variables in an urban area and compare it to suburban and rural sites to see if urban sites are experiencing climates expected globally in the future with climate change. A transect was established from Baltimore city center (Urban site), to the outer suburbs of Baltimore (suburban site) and out to an organic farm (rural site). At each site a weather station was set-up to monitor environmental variables annually for five years. Atmospheric CO2 was significantly increased on average by 66 ppm from the rural to the urban site over the five years of the study. Air temperature was significantly higher at the urban site (14.8 oC) compared to the suburban (13.6 oC) and rural (12.7 oC) sites. Relative humidity was not different between sites but vapor pressure deficit (VPD) was significantly higher at the urban site compared to the suburban and rural sites. During wet years relative humidity was significantly increased and VPD significantly reduced. Increased nitrogen deposition at the rural site (2.1 % compared to 1.8 and 1.2 % at the suburban and urban sites) was small enough not to affect soil nitrogen content. Dense urban areas with large populations and high vehicular traffic have significantly different microclimates compared to outlying suburban and rural areas. The increases in atmospheric CO2 and air temperature are similar to changes predicted in the short term with global climate change, therefore providing an environment suitable for studying future effects of climate change on terrestrial ecosystems.

  4. Global and Regional Seasonal Variability of Mid-Tropospheric CO2 as Measured by the Atmospheric Infrared Sounder (AIRS)

    NASA Technical Reports Server (NTRS)

    Pagano, Thomas S.; Olsen, Edward T.; Nguyen, Hai

    2012-01-01

    The Atmospheric Infrared Sounder (AIRS) is a hyperspectral infrared instrument on the Earth Observing System (EOS) Aqua Spacecraft, launched on May 4, 2002 into a near polar sun-synchronous orbit. AIRS has 2378 infrared channels ranging from 3.7 ?m to 15.4 ?m and a 13.5 km footprint at nadir. AIRS, in conjunction with the Advanced Microwave Sounding Unit (AMSU), produces temperature profiles with 1K/km accuracy on a global scale, as well as water vapor profiles and trace gas amounts for CO2, CO, SO2, O3 and CH4. AIRS CO2 climatologies have been shown to be useful for identifying anomalies associated with geophysical events such as El Nino-Southern Oscillation or Madden-Julian oscillation. In this study, monthly representations of mid-tropospheric CO2 are constructed from 10 years of AIRS Version 5 monthly Level 3 data. We compare the AIRS mid-tropospheric CO2 representations to ground-based measurements from the Scripps and National Oceanic and Atmospheric Administration Climate Modeling and Diagnostics Laboratory (NOAA CMDL) ground networks to better understand the phase lag of the CO2 seasonal cycle between the surface and middle troposphere. Results show only a small phase lag in the tropics that grows to approximately two months in the northern latitudes.

  5. Spatio-temporal visualization of air-sea CO2 flux and carbon budget using volume rendering

    NASA Astrophysics Data System (ADS)

    Du, Zhenhong; Fang, Lei; Bai, Yan; Zhang, Feng; Liu, Renyi

    2015-04-01

    This paper presents a novel visualization method to show the spatio-temporal dynamics of carbon sinks and sources, and carbon fluxes in the ocean carbon cycle. The air-sea carbon budget and its process of accumulation are demonstrated in the spatial dimension, while the distribution pattern and variation of CO2 flux are expressed by color changes. In this way, we unite spatial and temporal characteristics of satellite data through visualization. A GPU-based direct volume rendering technique using half-angle slicing is adopted to dynamically visualize the released or absorbed CO2 gas with shadow effects. A data model is designed to generate four-dimensional (4D) data from satellite-derived air-sea CO2 flux products, and an out-of-core scheduling strategy is also proposed for on-the-fly rendering of time series of satellite data. The presented 4D visualization method is implemented on graphics cards with vertex, geometry and fragment shaders. It provides a visually realistic simulation and user interaction for real-time rendering. This approach has been integrated into the Information System of Ocean Satellite Monitoring for Air-sea CO2 Flux (IssCO2) for the research and assessment of air-sea CO2 flux in the China Seas.

  6. [Effects of drought stress, high temperature and elevated CO2 concentration on the growth of winter wheat].

    PubMed

    Si, Fu-Yan; Qiao, Yun-Zhou; Jiang, Jing-Wei; Dong, Bao-Di; Shi, Chang-Hai; Liu, Meng-Yu

    2014-09-01

    The impacts of climate change on the grain yield, photosynthesis, and water conditions of winter wheat were assessed based on an experiment, in which wheat plants were subjected to ambient and elevated CO2 concentrations, ambient and elevated temperatures, and low and high water conditions independently and in combination. The CO2 enrichment alone had no effect on the photosynthesis of winter wheat, whereas higher temperature and drought significantly decreased the photosynthetic rate. Water conditions in flag leaves were not significantly changed at the elevated CO2 concentration or elevated temperature. However, drought stress decreased the relative water content in flag leaves, and the combination of elevated temperature and drought reduced the water potential in flag leaves. The combination of elevated CO2 concentration, elevated temperature, and drought significantly reduced the photosynthetic rate and water conditions, and led to a 41.4% decrease in grain yield. The elevated CO2 concentration alone increased the grain yield by 21.2%, whereas the elevated temperature decreased the grain yield by 12.3%. The grain yield was not affected by the combination of elevated CO2 concentration and temperature, but the grain yield was significantly decreased by the drought stress if combined with any of the climate scenarios applied in this study. These findings suggested that maintaining high soil water content might be a vital means of reducing the potential harm caused by the climate change. PMID:25757312

  7. Effect of Elevated CO2 Concentration, Elevated Temperature and No Nitrogen Fertilization on Methanogenic Archaeal and Methane-Oxidizing Bacterial Community Structures in Paddy Soil

    PubMed Central

    Liu, Dongyan; Tago, Kanako; Hayatsu, Masahito; Tokida, Takeshi; Sakai, Hidemitsu; Nakamura, Hirofumi; Usui, Yasuhiro; Hasegawa, Toshihiro; Asakawa, Susumu

    2016-01-01

    Elevated concentrations of atmospheric CO2 ([CO2]) enhance the production and emission of methane in paddy fields. In the present study, the effects of elevated [CO2], elevated temperature (ET), and no nitrogen fertilization (LN) on methanogenic archaeal and methane-oxidizing bacterial community structures in a free-air CO2 enrichment (FACE) experimental paddy field were investigated by PCR-DGGE and real-time quantitative PCR. Soil samples were collected from the upper and lower soil layers at the rice panicle initiation (PI) and mid-ripening (MR) stages. The composition of the methanogenic archaeal community in the upper and lower soil layers was not markedly affected by the elevated [CO2], ET, or LN condition. The abundance of the methanogenic archaeal community in the upper and lower soil layers was also not affected by elevated [CO2] or ET, but was significantly increased at the rice PI stage and significantly decreased by LN in the lower soil layer. In contrast, the composition of the methane-oxidizing bacterial community was affected by rice-growing stages in the upper soil layer. The abundance of methane-oxidizing bacteria was significantly decreased by elevated [CO2] and LN in both soil layers at the rice MR stage and by ET in the upper soil layer. The ratio of mcrA/pmoA genes correlated with methane emission from ambient and FACE paddy plots at the PI stage. These results indicate that the decrease observed in the abundance of methane-oxidizing bacteria was related to increased methane emission from the paddy field under the elevated [CO2], ET, and LN conditions. PMID:27600710

  8. Investigating the major carbon input to cave-air CO2 and speleothem calcite by using the respiratory quotient

    NASA Astrophysics Data System (ADS)

    Bergel, S.; Breecker, D.; Carlson, P.; Larson, T.; Banner, J. L.

    2014-12-01

    Speleothems (cave mineral deposits) are used to reconstruct changes in rainfall, moisture sources, atmospheric temperatures, and vegetation. Soil respiration is generally considered to be one of the major sources of cave-air CO2, and by extension a major source of carbon in speleothem calcite. However, the δ13C values from speleothem calcite are difficult to interpret. The purpose of this study is to investigate the major source of carbon in cave-air CO2 using a novel tracer, and thereby increase the accuracy of δ13C from speleothem calcite as a paleoenvironmental proxy. Potential sources of CO2 in cave-air include (1) soil respiration (primarily from roots and microbes), (2) animal respiration, (3) in-cave decomposition of organic matter, (4) deep magmatic or metamorphic sources, and (5) atmospheric air. Of these potential sources, soil respiration and atmospheric air are currently considered to be most significant in most caves. We use the respiratory quotient (RQ, which is the number of moles of CO2 produced per mole of O2 consumed, defined here in relation to atmospheric air) to compare cave air and overlying soil gas at two localities in central Texas: Natural Bridge Caverns and Inner Space Cavern. Soil gas samples (RQ = 1.32) follow a trend expected for respiration followed by diffusion whereas cave air samples (RQ = 0.97) follow a trend expected for respiration without subsequent diffusion. We suggest that root and rhizomicrobial respiration below the soil in the epikarst fracture network, where gas transport is dominated by advection rather than diffusion, contributes significantly to cave-air CO2. This is important because 12CO2 preferentially diffuses out of soils, elevating the d13C values of residual soil CO2, whereas no carbon isotope fractionation occurs during advection. Our interpretation of RQ values suggests that the d13C value of cave-air CO2 is not influenced by diffusive loss of CO2. In order to further investigate soil and cave carbon

  9. Using Concentrations and Isotopic Compositions of CO2 to Distinguish Microbial Production of CO2 in Unsaturated Zone Sediments in Hydrogeochemical Models

    NASA Astrophysics Data System (ADS)

    Conrad, M. E.; Arora, B.; Williams, K. H.; Bill, M.; Spycher, N.; Steefel, C. I.; Tokunaga, T. K.; Hubbard, S. S.

    2014-12-01

    Quantifying levels of microbial activity in unsaturated subsurface environments is an important factor for understanding exchange of greenhouse gases (e.g., CO2, CH4, N2O) with the atmosphere. For CO2, this is problematic due the variety of processes affecting its sources, fate and transport in the vadose zone (e.g., root respiration, carbonate dissolution and precipitation, exchange with pore water/groundwater and microbial production and consumption). To determine the impacts of all these processes and dependence on variables including temperature, moisture content and pH requires coupled numerical models supported by robust, long-term data sets. We are attempting to do this for a small (~90,000 m2) floodplain adjacent to the Colorado River in the town of Rifle, Colorado. The geology of the site consists of 6-8 m of Quaternary alluvium composed of quartz and feldspar sands with silts, clays, pebbles, and cobbles overlying the less permeable Tertiary Wasatch Formation. The unsaturated zone is 3-4 m thick overlying a perched aquifer above the alluvium-Wasatch contact. Depth-distributed gas samplers and suction lysimeters for pore water sampling were installed at three locations across the site in March of 2013. From April 2013 to present, soil gas samples have been collected on a bi-weekly to monthly interval and analyzed for gas concentrations and isotopic compositions. Through the first year, several significant spatial and temporal trends have emerged from the data including higher soil gas CO2 (up to 6% near the water table) with higher δ13C values during the warmer summer months, possibly signifying higher levels of microbial activity. In the shallower soils, CO2 concentrations are lower (atmospheric to 2%) with more variable δ13C values (ranging from -18‰ in the summer to -24‰ in the winter) likely due to slower exchange with the atmosphere during the winter when surface soils are more saturated due to snow cover and melting. Extensive data has also

  10. Measurements of the CO_2 15 μm Band System Broadened by Air, N_2 and CO_2 at Terrestrial Atmospheric Temperatures

    NASA Astrophysics Data System (ADS)

    Smith, M. A. H.; Devi, V. Malathy; Benner, D. Chris; Blake, T. A.; Sams, R. L.

    2009-06-01

    In earth remote sensing, retrievals of atmospheric temperature profiles are often based on observed radiances in infrared spectral regions where emission from atmospheric CO_2 predominates. To achieve improved retrieval accuracy, systematic errors in the forward model must be reduced, especially those associated with errors in the spectroscopic line calculation. We have recorded more than 110 new high-resolution infrared spectra of the 15-μm band system of CO_2 to accurately determine line intensities, self-, air- and N_2-broadened widths and pressure-induced line shifts, along with their temperature dependences. The spectra were recorded with the Bruker IFS 120 HR Fourier transform spectrometer at Pacific Northwest National Laboratory (PNNL) and temperature-controlled sample cells. Sample temperatures were between 206K and 298K. Maximum total pressures were 15 Torr for self-broadening and 613 Torr for air- and N_2-broadening. Analysis is done using a multispectrum fitting technique to retrieve the spectroscopic parameters. Line mixing and other non-Lorentz, non-Voigt line shapes are also assessed. The resulting line parameters are compared with the HITRAN database and with other measurements. D. Chris Benner, C.P. Rinsland, V. Malathy Devi, M.A.H. Smith, and D. Atkins, J. Quant. Spectrosc. Radiat. Transfer 53, 705-721 (1995) L.S. Rothman et al., J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005) L.S. Rothman et al., J. Quant. Spectrosc. Radiat. Transfer, in press (2009)

  11. Carbon isotope fractionation by marine phytoplankton in culture: The effects of CO2 concentration, pH, temperature, and species

    NASA Astrophysics Data System (ADS)

    Hinga, Kenneth R.; Arthur, Michael A.; Pilson, Michael E. Q.; Whitaker, Dania

    1994-03-01

    Closed cultures of marine phytoplankton were established under variable conditions of CO2 concentration, temperature, growth rate (by light limitation), and pH (but with nearly identical [CO2aq]) in order to assess the relative influence of these variables on the extent of carbon isotope fractionation relative to dissolved inorganic carbon sources. Culture biomass was not allowed to increase beyond levels that would significantly affect the dissolved carbon system in the closed cultures. In experiments with Skeletonema costatum and Emiliania huxleyi, increasing CO2 concentrations led to increased carbon isotope discrimination (resulting in organic matter progressively depleted in δ13C, i.e., a greater, more negative ɛp). ɛp values for E. huxleyi were 8-10‰ less than for S. costatum under identical conditions. For the S. costatum cultures, there was nearly a 20 ‰ range in [CO2aq]-dependent ɛp. The effect was nonlinear with a leveling off at high [CO2aq]. Over a pH range of 7.5-8.3 but at a constant [CO2aq] there was a variation in carbon isotope fractionation by S. costatum of about 9 ‰ with a minimum at pH 7.8-7.9. There was a temperature effect of ˜8‰ on fractionation even after equilibrium temperature dependency of δ13C of CO2aq was taken into account. No growth rate effect was found for S. costatum over a modest range of growth rates. Culture experiments used to determine the carbon isotope fractionation by phytoplankton species must be conducted under well-defined conditions of temperature, pH, and CO2 concentrations. Hindcasts of ancient atmospheric pCO2 from measurements of δ13C of organic carbon in marine sediments will require careful calibration because of the variety of possible factors that influence δ13Corg.

  12. An experimental evaluation of the use of C3 δ13C plant tissue as a proxy for the paleoatmospheric δ13CO2 signature of air

    NASA Astrophysics Data System (ADS)

    Lomax, B. H.; Knight, C. A.; Lake, J. A.

    2012-09-01

    Previous work suggests that the relationship between the carbon isotope composition of air (δ13Ca) and plant leaf tissue (δ13Cp) can be used to track changes in the carbon isotope composition of paleo-atmospheric CO2. Here we test this assertion in a series of experiments using the model plant Arabidopsis thaliana grown under a range of atmospheric CO2 concentrations relevant to geologic time (380, 760, 1000, 1500, 2000 and 3000 ppm). Nested within these CO2 experiments water availability was controlled (giving two sets of experimental plants; low and high water treatment at each CO2 concentration) to manipulate stomatal opening, a key process governing carbon fixation and isotope discrimination. Results show a highly significant relationship between δ13Ca and δ13Cp under both experimental water treatments. To test the utility of δ13Cp to predict δ13Ca we compare calculated δ13Ca to measured values of δ13Ca. These data show that although there is a significant relationship between calculated and measured δ13Ca, there is disparity between the two values of δ13Ca and a large difference between calculated values under different water treatments even when grown in a common CO2 concentration. These results demonstrate that environmental factors that alter stomatal opening can severely impact on the use and reliability of δ13Cp to predict δ13Ca and as such, results should be interpreted with caution.

  13. Synthesis of DNL-6 with a high concentration of Si (4 Al) environments and its application in CO(2) separation.

    PubMed

    Su, Xiong; Tian, Peng; Fan, Dong; Xia, Qinghua; Yang, Yue; Xu, Shutao; Zhang, Lin; Zhang, Ying; Wang, Dehua; Liu, Zhongmin

    2013-05-01

    The synthesis of DNL-6 with a high concentration of Si (4 Al) environments [Si/(Si+Al+P)=0.182 mol, denoted as M-DNL-6] is demonstrated. This represents the highest reported concentration of such environments in silicoaluminophosphate (SAPO) molecular sieves. Adsorption studies show that the high Si (4 Al) content in M-DNL-6, with an increased number of Brønsted acid sites in the framework, greatly promotes the adsorption of CO(2). M-DNL-6 exhibits a large CO(2) uptake capacity of up to 6.18 mmol g(-1) at 273 K and 101 kPa, and demonstrates high ratios of CO(2)/CH(4) and CO(2)/N(2) separation. From breakthrough and cycling experiments, M-DNL-6 demonstrates the ability to completely separate CO(2) from CH(4) or N(2) with a dynamic capacity of approximately 8.0 wt % before breakthrough. Importantly, the adsorbed CO(2) is easily released from the adsorbent through a simple gas purging operation at room temperature to regain 95 % of the original adsorption capacity. These results suggest that M-DNL-6 can be used as a potential adsorbent for CO(2) capture in pressure swing adsorption processes. PMID:23606439

  14. High-Pressure Measurements of Temperature and CO2 Concentration Using Tunable Diode Lasers at 2 μm.

    PubMed

    Cai, Tingdong; Gao, Guangzhen; Wang, Minrui; Wang, Guishi; Liu, Ying; Gao, Xiaoming

    2016-03-01

    A sensor for simultaneous measurements of temperature and carbon dioxide (CO2) concentration at elevated pressure is developed using tunable diode lasers at 2 µm. Based on some selection rules, a CO2 line pair at 5006.140 and 5010.725 cm(-1) is selected for the TDL sensor. In order to ensure the accuracy and rapidity of the sensor, a quasi-fixed-wavelength WMS is employed. Normalization of the 2f signal with the 1f signal magnitude is used to remove the need for calibration and correct for transmission variation due to beam steering, mechanical misalignments, soot, and windows fouling. Temperatures are obtained from comparison of the background-subtracted 1f-normalized WMS-2f signals ratio and a 1f-normalized WMS-2f peak values ratio model. CO2 concentration is inferred from the 1f-normalized WMS-2f peak values of the CO2 transition at 5006.140 cm(-1). Measurements of temperature and CO2 concentration are carried out in static cell experiments (P = 1-10 atm, T = 500-1200 K) to validate the accuracy and ability of the sensor. The results show that accuracy of the sensor for temperature and CO2 concentration are 1.66% temperature and 3.1%, respectively. All the measurements show the potential utility of the sensor for combustion diagnose at elevated pressure. PMID:26798080

  15. Model-data synthesis for the next generation of forest free-air CO2 enrichment (FACE) experiments.

    PubMed

    Norby, Richard J; De Kauwe, Martin G; Domingues, Tomas F; Duursma, Remko A; Ellsworth, David S; Goll, Daniel S; Lapola, David M; Luus, Kristina A; MacKenzie, A Rob; Medlyn, Belinda E; Pavlick, Ryan; Rammig, Anja; Smith, Benjamin; Thomas, Rick; Thonicke, Kirsten; Walker, Anthony P; Yang, Xiaojuan; Zaehle, Sönke

    2016-01-01

    The first generation of forest free-air CO2 enrichment (FACE) experiments has successfully provided deeper understanding about how forests respond to an increasing CO2 concentration in the atmosphere. Located in aggrading stands in the temperate zone, they have provided a strong foundation for testing critical assumptions in terrestrial biosphere models that are being used to project future interactions between forest productivity and the atmosphere, despite the limited inference space of these experiments with regards to the range of global ecosystems. Now, a new generation of FACE experiments in mature forests in different biomes and over a wide range of climate space and biodiversity will significantly expand the inference space. These new experiments are: EucFACE in a mature Eucalyptus stand on highly weathered soil in subtropical Australia; AmazonFACE in a highly diverse, primary rainforest in Brazil; BIFoR-FACE in a 150-yr-old deciduous woodland stand in central England; and SwedFACE proposed in a hemiboreal, Pinus sylvestris stand in Sweden. We now have a unique opportunity to initiate a model-data interaction as an integral part of experimental design and to address a set of cross-site science questions on topics including responses of mature forests; interactions with temperature, water stress, and phosphorus limitation; and the influence of biodiversity. PMID:26249015

  16. Temporal variability and spatial dynamics of CO2 and CH4 concentrations and fluxes in the Zambezi River system

    NASA Astrophysics Data System (ADS)

    Teodoru, Cristian; Borges, Alberto; Bouillon, Steven; Nyoni, Frank; Nyambe, Imasiku

    2014-05-01

    Spanning over 2900 km in length and with a catchment of approximately 1.4 million km2, the Zambezi River is the fourth largest river in Africa and the largest flowing into the Indian Ocean from the African continent. Yet, there is surprisingly little or no information on carbon (C) cycling in this large river system. As part of a broader study on the riverine biogeochemistry in the Zambezi River basin, we present here mainstream dissolved CO2 and CH4 data collected during 2012 and 2013 over two climatic seasons (dry and wet) to constrain the interannual variability, seasonality and spatial heterogeneity of partial pressure of CO2 (pCO2) and CH4 concentrations and fluxes along the aquatic continuum, in relation to physico-chemical parameters (temperature, conductivity, oxygen, and pH) and various carbon pools (dissolved and particulate, organic and inorganic carbon, total alkalinity, primary production, respiration and net aquatic metabolism). Both pCO2 and CH4 variability was high, ranging from minimal values of 150 ppm and 7 nM, respectively, mainly in the two large reservoirs (the Kariba and the Cabora Bassa characterized by high pH and oxygen and low DOC), up to maximum values of 12,500 ppm and 12,130 nM, CO2 and CH4, respectively, mostly below floodplains/wetlands (low pH and oxygen levels, high DOC and POC concentrations). The interannual variability was relatively large for both CO2 and CH4 (mean pCO2: 2350 ppm in 2013 vs. 3180 ppm in 2013; mean CH4: 600 nM in 2012 vs. 1000 nM in 2013) and significantly higher (up to two fold) during wet season compared to dry season closely linked to distinct seasonal hydrological characteristics. Overall, no clear pattern was observed along the longitudinal gradient as river CO2 and CH4 concentrations are largely influenced by the presence of floodplains/wetlands, anthropogenic reservoirs or natural barriers (waterfalls/ rapids). Following closely the concentration patterns, river CO2 and CH4 mean fluxes of 3440 mg C-CO2 m

  17. Where does the carbon go? A model–data intercomparison of vegetation carbon allocation and turnover processes at two temperate forest free-air CO2 enrichment sites

    PubMed Central

    De Kauwe, Martin G; Medlyn, Belinda E; Zaehle, Sönke; Walker, Anthony P; Dietze, Michael C; Wang, Ying-Ping; Luo, Yiqi; Jain, Atul K; El-Masri, Bassil; Hickler, Thomas; Wårlind, David; Weng, Ensheng; Parton, William J; Thornton, Peter E; Wang, Shusen; Prentice, I Colin; Asao, Shinichi; Smith, Benjamin; McCarthy, Heather R; Iversen, Colleen M; Hanson, Paul J; Warren, Jeffrey M; Oren, Ram; Norby, Richard J

    2014-01-01

    Elevated atmospheric CO2 concentration (eCO2) has the potential to increase vegetation carbon storage if increased net primary production causes increased long-lived biomass. Model predictions of eCO2 effects on vegetation carbon storage depend on how allocation and turnover processes are represented. We used data from two temperate forest free-air CO2 enrichment (FACE) experiments to evaluate representations of allocation and turnover in 11 ecosystem models. Observed eCO2 effects on allocation were dynamic. Allocation schemes based on functional relationships among biomass fractions that vary with resource availability were best able to capture the general features of the observations. Allocation schemes based on constant fractions or resource limitations performed less well, with some models having unintended outcomes. Few models represent turnover processes mechanistically and there was wide variation in predictions of tissue lifespan. Consequently, models did not perform well at predicting eCO2 effects on vegetation carbon storage. Our recommendations to reduce uncertainty include: use of allocation schemes constrained by biomass fractions; careful testing of allocation schemes; and synthesis of allocation and turnover data in terms of model parameters. Data from intensively studied ecosystem manipulation experiments are invaluable for constraining models and we recommend that such experiments should attempt to fully quantify carbon, water and nutrient budgets. PMID:24844873

  18. Where does the carbon go? A model-data intercomparison of vegetation carbon allocation and turnover processes at two temperate forest free-air CO2 enrichment sites.

    PubMed

    De Kauwe, Martin G; Medlyn, Belinda E; Zaehle, Sönke; Walker, Anthony P; Dietze, Michael C; Wang, Ying-Ping; Luo, Yiqi; Jain, Atul K; El-Masri, Bassil; Hickler, Thomas; Wårlind, David; Weng, Ensheng; Parton, William J; Thornton, Peter E; Wang, Shusen; Prentice, I Colin; Asao, Shinichi; Smith, Benjamin; McCarthy, Heather R; Iversen, Colleen M; Hanson, Paul J; Warren, Jeffrey M; Oren, Ram; Norby, Richard J

    2014-08-01

    Elevated atmospheric CO2 concentration (eCO2) has the potential to increase vegetation carbon storage if increased net primary production causes increased long-lived biomass. Model predictions of eCO2 effects on vegetation carbon storage depend on how allocation and turnover processes are represented. We used data from two temperate forest free-air CO2 enrichment (FACE) experiments to evaluate representations of allocation and turnover in 11 ecosystem models. Observed eCO2 effects on allocation were dynamic. Allocation schemes based on functional relationships among biomass fractions that vary with resource availability were best able to capture the general features of the observations. Allocation schemes based on constant fractions or resource limitations performed less well, with some models having unintended outcomes. Few models represent turnover processes mechanistically and there was wide variation in predictions of tissue lifespan. Consequently, models did not perform well at predicting eCO2 effects on vegetation carbon storage. Our recommendations to reduce uncertainty include: use of allocation schemes constrained by biomass fractions; careful testing of allocation schemes; and synthesis of allocation and turnover data in terms of model parameters. Data from intensively studied ecosystem manipulation experiments are invaluable for constraining models and we recommend that such experiments should attempt to fully quantify carbon, water and nutrient budgets. PMID:24844873

  19. Combined effects of elevated temperature and CO2 concentration on Cd and Zn accumulation dynamics in Triticum aestivum L.

    PubMed

    Wang, Xiaoheng; Li, Yu; Lu, Hong; Wang, Shigong

    2016-09-01

    A simulated climate warming experiment was conducted to evaluate the combined effects of elevated temperature and CO2 concentration on the bioaccumulation, translocation and subcellular distributions of Cd and Zn in wheat seedlings (Triticum aestivum L. cv. Xihan 1.) at Dingxi, Gansu Province, China. The objective was to find evidence that global climate change is affecting the bioaccumulation of Cd and Zn in T. aestivum L. cv. Xihan 1. The results showed that compared to control A, elevated temperature and CO2 increased Cd bioaccumulation in the shoots by 1.4-2.5 times, and increased that in the roots by 1.2-1.5 times, but decreased Zn levels in wheat shoots by 1.4-2.0 times, while decreased that in the roots by 1.6-1.9 times. Moreover, temperature and CO2 concentration increase also led to increased Cd concentration, and decreased Zn concentration in subcellular compartments of wheat seedlings. The largest Cd concentration increase (174.4%) was observed in the cell wall and debris fractions of shoots after they were subjected to the highest CO2 and temperature treatment (TC3). The largest Zn concentration decrease (53.1%) was observed in the soluble (F3) fractions of shoots after they were subjected to the medium CO2 and temperature treatment (TC2). The temperature and CO2 increase had no significant effect on the proportional distribution of Cd and Zn in the subcellular fractions. The root-to-shoot translocation of Cd increased with the increasing temperature and CO2 concentration. However, the Zn distributions only fluctuated within a small range. PMID:27593278

  20. Energy requirements for CO2 capture from ambient air (DAC) competitive with capture from flue-gas (PCC)

    NASA Astrophysics Data System (ADS)

    Meinrenken, Christoph

    2015-03-01

    Capture of CO2, whether from a flue gas source (PCC) or from distributed sources via ambient air (DAC), is a key enabling technology to provide carbon for sustainable synthetic energy carriers such as solar fuels. Based on thermodynamic minimum considerations, DAC is often expected to require about 3 times more energy (per ton CO2 captured) than PCC because CO2 in ambient air is more dilute. Here, we calculate the energy required for a humidity swing-based DAC installation that uses an anionic exchange resin as sorbent. The calculation uses recently measured equilibrium CO2 loadings of the sorbent as function of partial CO2 pressure, temperature, and humidity. We calculate the installation's electricity consumption to be about 45 kJ per mole of pure CO2 at 1 bar (scenario-dependent). Furthermore, we estimate the amount of heat provided by ambient air and thus provide context of the overall energy and entropy balance and thermodynamic minimum views. The electricity consumption is competitive with typical parasitic loads of PCC-equipped coal-fired power plants (40-50 kJ per mole at same pressure) and significantly lower than predicted for other DAC installations such as Na(OH) sorbent-based systems. Our analyses elucidate why DAC is not always more energy-intensive that PCC, thus alleviating often cited concerns of significant cost impediments. Financial support by ABB for research presented herein is gratefully acknowledged.

  1. Effect of elevated CO2 concentration and nitrate: ammonium ratios on gas exchange and growth of cassava (Manihot esculenta Crantz)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study evaluated how different nitrogen forms affect growth and photosynthetic responses of cassava to CO2 concentration. Cassava was grown in 12-L pots in a greenhouse (30/25o C day / night) at 390 or 750 ppm of CO2. Three nitrogen treatments were applied: (a) 12 mM NO3-, (b) 6 mM NO3- + 6 mM N...

  2. Coupling Between the Changes in CO2 Concentration and Sediment Biogeochemistry in the Salinas De San Pedro Mudflat, California, USA

    NASA Astrophysics Data System (ADS)

    Rezaie Boroon, M.; Diaz, S.; Torres, V.; Lazzaretto, T.; Dehyn, D.

    2013-12-01

    We investigated the effects of elevated carbon dioxide [CO2] on biogeochemistry of marsh sediment including speciation of selected heavy metals in Salinas de San Pedro mudflat in California. The Salinas de San Pedro mudflat has higher carbon (C) content than the vast majority of fully-vegetated salt marshes even with the higher tidal action in the mudflat. Sources for CO2 were identified as atmospheric CO2 as well as due to local fault degassing process. We measured carbon dioxide [CO2], methane [CH4], total organic carbon, dissolved oxygen, salinity, and heavy metal concentration in various salt marsh locations. Overall, our results showed that CO2 concentration ranging from 418.7 to 436.9 [ppm], which are slightly different in various chambers but are in good agreement with some heavy metal concentrations values in mudflat at or around the same location. The selected metal concentration values (ppm) ranging from 0.003 - 0.011(As); 0.001-0.005 (Cd); 0.04-0.02 (Cr); 0.13-0.38 (Cu); 0.11-0.38 (Pb); 0.0009-0.020 (Se); and 0.188-0.321 (Zn). The low dissolved O2 [ppm] in the pore water sediment indicates suboxic environment. Additionally, CO2 [ppm] and loss on ignition (LOI) [%] correlated inversely; the higher CO2 content, the lower was the LOI; that is to say the excess CO2 may caused higher rates of decomposition and therefore it leads to lower soil organic matter (LOI) [%] on the mudflat surface. It appears that the elevated CO2 makes changes in salt marsh pore water chemistry for instance the free ionic metal (Cu2+, Pb2+, etc.) speciation is one of the most reactive form because simply assimilated by the non-decayed or alive organisms in sediment of salt marsh and/or in water. This means that CO2 not only is a sign of improvement in plant productivity, but also activates microbial decomposition through increases in dissolved organic carbon availability. CO2 also increases acidification processes such as anaerobic degradation of microorganism and oxidation of

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

    NASA Astrophysics Data System (ADS)

    Niehoff, B.; Schmithüsen, T.; Knüppel, N.; Daase, M.; Czerny, J.; Boxhammer, T.

    2013-03-01

    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.

  4. Experimental and modeling study on effects of N2 and CO2 on ignition characteristics of methane/air mixture

    PubMed Central

    Zeng, Wen; Ma, Hongan; Liang, Yuntao; Hu, Erjiang

    2014-01-01

    The ignition delay times of methane/air mixture diluted by N2 and CO2 were experimentally measured in a chemical shock tube. The experiments were performed over the temperature range of 1300–2100 K, pressure range of 0.1–1.0 MPa, equivalence ratio range of 0.5–2.0 and for the dilution coefficients of 0%, 20% and 50%. The results suggest that a linear relationship exists between the reciprocal of temperature and the logarithm of the ignition delay times. Meanwhile, with ignition temperature and pressure increasing, the measured ignition delay times of methane/air mixture are decreasing. Furthermore, an increase in the dilution coefficient of N2 or CO2 results in increasing ignition delays and the inhibition effect of CO2 on methane/air mixture ignition is stronger than that of N2. Simulated ignition delays of methane/air mixture using three kinetic models were compared to the experimental data. Results show that GRI_3.0 mechanism gives the best prediction on ignition delays of methane/air mixture and it was selected to identify the effects of N2 and CO2 on ignition delays and the key elementary reactions in the ignition chemistry of methane/air mixture. Comparisons of the calculated ignition delays with the experimental data of methane/air mixture diluted by N2 and CO2 show excellent agreement, and sensitivity coefficients of chain branching reactions which promote mixture ignition decrease with increasing dilution coefficient of N2 or CO2. PMID:25750753

  5. Experimental and modeling study on effects of N2 and CO2 on ignition characteristics of methane/air mixture.

    PubMed

    Zeng, Wen; Ma, Hongan; Liang, Yuntao; Hu, Erjiang

    2015-03-01

    The ignition delay times of methane/air mixture diluted by N2 and CO2 were experimentally measured in a chemical shock tube. The experiments were performed over the temperature range of 1300-2100 K, pressure range of 0.1-1.0 MPa, equivalence ratio range of 0.5-2.0 and for the dilution coefficients of 0%, 20% and 50%. The results suggest that a linear relationship exists between the reciprocal of temperature and the logarithm of the ignition delay times. Meanwhile, with ignition temperature and pressure increasing, the measured ignition delay times of methane/air mixture are decreasing. Furthermore, an increase in the dilution coefficient of N2 or CO2 results in increasing ignition delays and the inhibition effect of CO2 on methane/air mixture ignition is stronger than that of N2. Simulated ignition delays of methane/air mixture using three kinetic models were compared to the experimental data. Results show that GRI_3.0 mechanism gives the best prediction on ignition delays of methane/air mixture and it was selected to identify the effects of N2 and CO2 on ignition delays and the key elementary reactions in the ignition chemistry of methane/air mixture. Comparisons of the calculated ignition delays with the experimental data of methane/air mixture diluted by N2 and CO2 show excellent agreement, and sensitivity coefficients of chain branching reactions which promote mixture ignition decrease with increasing dilution coefficient of N2 or CO2. PMID:25750753

  6. Toward a lithium-"air" battery: the effect of CO2 on the chemistry of a lithium-oxygen cell.

    PubMed

    Lim, Hyung-Kyu; Lim, Hee-Dae; Park, Kyu-Young; Seo, Dong-Hwa; Gwon, Hyeokjo; Hong, Jihyun; Goddard, William A; Kim, Hyungjun; Kang, Kisuk

    2013-07-01

    Lithium-oxygen chemistry offers the highest energy density for a rechargeable system as a "lithium-air battery". Most studies of lithium-air batteries have focused on demonstrating battery operations in pure oxygen conditions; such a battery should technically be described as a "lithium-dioxygen battery". Consequently, the next step for the lithium-"air" battery is to understand how the reaction chemistry is affected by the constituents of ambient air. Among the components of air, CO2 is of particular interest because of its high solubility in organic solvents and it can react actively with O2(-•), which is the key intermediate species in Li-O2 battery reactions. In this work, we investigated the reaction mechanisms in the Li-O2/CO2 cell under various electrolyte conditions using quantum mechanical simulations combined with experimental verification. Our most important finding is that the subtle balance among various reaction pathways influencing the potential energy surfaces can be modified by the electrolyte solvation effect. Thus, a low dielectric electrolyte tends to primarily form Li2O2, while a high dielectric electrolyte is effective in electrochemically activating CO2, yielding only Li2CO3. Most surprisingly, we further discovered that a high dielectric medium such as DMSO can result in the reversible reaction of Li2CO3 over multiple cycles. We believe that the current mechanistic understanding of the chemistry of CO2 in a Li-air cell and the interplay of CO2 with electrolyte solvation will provide an important guideline for developing Li-air batteries. Furthermore, the possibility for a rechargeable Li-O2/CO2 battery based on Li2CO3 may have merits in enhancing cyclability by minimizing side reactions. PMID:23758262

  7. Response of evapotranspiration from tallgrass prairie vegetation to CO2 at subambient to elevated concentrations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effects of CO2 enrichment on leaf transpiration are well-documented, but our understanding of how CO2 interacts with other variables to regulate evapotranspiration is more limited. We installed weighing lysimeters planted to species characteristic of tallgrass prairie into a field chamber used to r...

  8. Initial response of evapotranspiration from tallgrass prairie vegetation to CO2 at subambient to elevated concentrations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effects of CO2 enrichment on leaf transpiration are well-documented, but our understanding of how CO2 interacts with other variables to regulate evapotranspiration is more limited. We installed weighing lysimeters planted to species characteristic of tallgrass prairie in a field chamber used to reg...

  9. Phase I Final Report: New Technology Platform to Measure Atmospheric Fluxes and Concentrations of Carbon Isotopes in CO2

    SciTech Connect

    Miles J. Weida, Ph.D. Senior Scientist, Applications Development

    2009-03-24

    There were four goals of the Phase I research carried out to develop the basis for a new technology platform to measure atmospheric fluxes and concentrations of carbon isotopes in CO2. The first was to extend the Daylight Solutions external cavity quantum cascade laser (ECqcL) package to allow continuous, rapid (<10 msec) sweeping of the laser wavelength to acquire spectra. This involved developing a rapid tuning mechanism for our broadly tunable quantum cascade (QC) lasers that meets the requirements of a CO2 isotopologue sensing application. The second goal was to undertake QC device development to procure QC devices capable of lasing in the 4.3 to 4.5 μm spectral region necessary for CO2 isotopologue detection. Final devices procured from this process were to be mounted, coated, and tested to demonstrate their suitability for scanning from 4.3 to 4.5 μm. The third goal was to develop spectral acquisition and analysis algorithms to enable real-time data acquisition and spectral fitting to determine gas temperature and isotopologue concentrations. This involved determining the best spectral analysis algorithm for retrieving CO2 isotopologue temperature and concentration information based on a targeted (i.e. 5% to 10% of center wavelength) scan of CO2 isotopologue absorption features. The culminating goal of Phase I was integration of these three components into a bench-top prototype that can measure CO2 isotopologue ratios in the laboratory.

  10. First continuous measurements of δ18O-CO2 in air with a Fourier transform infrared spectrometer

    NASA Astrophysics Data System (ADS)

    Vardag, S. N.; Hammer, S.; Sabasch, M.; Griffith, D. W. T.; Levin, I.

    2015-02-01

    The continuous in situ measurement of δ18O in atmospheric CO2 opens a new door to differentiating between CO2 source and sink components with high temporal resolution. Continuous 13C-CO2 measurement systems have already been commercially available for some time, but until now, only few instruments have been able to provide a continuous measurement of the oxygen isotope ratio in CO2. Besides precise 13C/12C observations, the Fourier transform infrared (FTIR) spectrometer is also able to measure the 18O / 16O ratio in CO2, but the precision and accuracy of the measurements have not yet been evaluated. Here we present a first analysis of δ18O-CO2 (and δ13C-CO2) measurements with the FTIR analyser in Heidelberg. We used Allan deviation to determine the repeatability of δ18O-CO2 measurements and found that it decreases from 0.25‰ for 10 min averages to about 0.1‰ after 2 h and remains at that value up to 24 h. We evaluated the measurement precision over a 10-month period (intermediate measurement precision) using daily working gas measurements and found that our spectrometer measured δ18O-CO2 to better than 0.3‰ at a temporal resolution of less than 10 min. The compatibility of our FTIR-spectrometric measurements to isotope-ratio mass-spectrometric (IRMS) measurements was determined by comparing FTIR measurements of cylinder gases and ambient air with IRMS measurements of flask samples, filled with gases of the same cylinders or collected from the same ambient air intake. Two-sample t tests revealed that, at the 0.01 significance level, the FTIR and the IRMS measurements do not differ significantly from each other and are thus compatible. We describe two weekly episodes of ambient air measurements, one in winter and one in summer, and discuss what potential insights and new challenges combined highly resolved CO2, δ13C-CO2 and δ18O-CO2 records may provide in terms of better understanding regional scale continental carbon exchange processes.

  11. Regionalized global budget of the CO2 exchange at the air-water interface in continental shelf seas

    NASA Astrophysics Data System (ADS)

    Laruelle, Goulven G.; Lauerwald, Ronny; Pfeil, Benjamin; Regnier, Pierre

    2014-11-01

    Over the past decade, estimates of the atmospheric CO2 uptake by continental shelf seas were constrained within the 0.18-0.45 Pg C yr-1 range. However, most of those estimates are based on extrapolations from limited data sets of local flux measurements (n < 100). Here we propose to derive the CO2 air-sea exchange of the shelf seas by extracting 3 · 106 direct surface ocean CO2 measurements from the global database SOCAT (Surface Ocean CO2 Atlas), atmospheric CO2 values from GlobalVIEW and calculating gas transfer rates using readily available global temperature, salinity, and wind speed fields. We then aggregate our results using a global segmentation of the shelf in 45 units and 152 subunits to establish a consistent regionalized CO2 exchange budget at the global scale. Within each unit, the data density determines the spatial and temporal resolutions at which the air-sea CO2 fluxes are calculated and range from a 0.5° resolution in the best surveyed regions to a whole unit resolution in areas where data coverage is limited. Our approach also accounts, for the first time, for the partial sea ice cover of polar shelves. Our new regionalized global CO2 sink estimate of 0.19 ± 0.05 Pg C yr-1 falls in the low end of previous estimates. Reported to an ice-free surface area of 22 · 106 km2, this value yields a flux density of 0.7 mol C m-2 yr-1, ~40% more intense than that of the open ocean. Our results also highlight the significant contribution of Arctic shelves to this global CO2 uptake (0.07 Pg C yr-1).

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

    NASA Technical Reports Server (NTRS)

    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.

  13. Response of Archaeal Communities in the Rhizosphere of Maize and Soybean to Elevated Atmospheric CO2 Concentrations

    PubMed Central

    Nelson, David M.; Cann, Isaac K. O.; Mackie, Roderick I.

    2010-01-01

    Background Archaea are important to the carbon and nitrogen cycles, but it remains uncertain how rising atmospheric carbon dioxide concentrations ([CO2]) will influence the structure and function of soil archaeal communities. Methodology/Principal Findings We measured abundances of archaeal and bacterial 16S rRNA and amoA genes, phylogenies of archaeal 16S rRNA and amoA genes, concentrations of KCl-extractable soil ammonium and nitrite, and potential ammonia oxidation rates in rhizosphere soil samples from maize and soybean exposed to ambient (∼385 ppm) and elevated (550 ppm) [CO2] in a replicated and field-based study. There was no influence of elevated [CO2] on copy numbers of archaeal or bacterial 16S rRNA or amoA genes, archaeal community composition, KCl-extractable soil ammonium or nitrite, or potential ammonia oxidation rates for samples from maize, a model C4 plant. Phylogenetic evidence indicated decreased relative abundance of crenarchaeal sequences in the rhizosphere of soybean, a model leguminous-C3 plant, at elevated [CO2], whereas quantitative PCR data indicated no changes in the absolute abundance of archaea. There were no changes in potential ammonia oxidation rates at elevated [CO2] for soybean. Ammonia oxidation rates were lower in the rhizosphere of maize than soybean, likely because of lower soil pH and/or abundance of archaea. KCl-extractable ammonium and nitrite concentrations were lower at elevated than ambient [CO2] for soybean. Conclusion Plant-driven shifts in soil biogeochemical processes in response to elevated [CO2] affected archaeal community composition, but not copy numbers of archaeal genes, in the rhizosphere of soybean. The lack of a treatment effect for maize is consistent with the fact that the photosynthesis and productivity of maize are not stimulated by elevated [CO2] in the absence of drought. PMID:21209969

  14. Effect of carbonic anhydrase on silicate weathering and carbonate formation at present day CO2 concentrations compared to primordial values

    PubMed Central

    Xiao, Leilei; Lian, Bin; Hao, Jianchao; Liu, Congqiang; Wang, Shijie

    2015-01-01

    It is widely recognized that carbonic anhydrase (CA) participates in silicate weathering and carbonate formation. Nevertheless, it is still not known if the magnitude of the effect produced by CA on surface rock evolution changes or not. In this work, CA gene expression from Bacillus mucilaginosus and the effects of recombination protein on wollastonite dissolution and carbonate formation under different conditions are explored. Real-time fluorescent quantitative PCR was used to explore the correlation between CA gene expression and sufficiency or deficiency in calcium and CO2 concentration. The results show that the expression of CA genes is negatively correlated with both CO2 concentration and ease of obtaining soluble calcium. A pure form of the protein of interest (CA) is obtained by cloning, heterologous expression, and purification. The results from tests of the recombination protein on wollastonite dissolution and carbonate formation at different levels of CO2 concentration show that the magnitudes of the effects of CA and CO2 concentration are negatively correlated. These results suggest that the effects of microbial CA in relation to silicate weathering and carbonate formation may have increased importance at the modern atmospheric CO2 concentration compared to 3 billion years ago. PMID:25583135

  15. Effect of carbonic anhydrase on silicate weathering and carbonate formation at present day CO2 concentrations compared to primordial values

    NASA Astrophysics Data System (ADS)

    Xiao, Leilei; Lian, Bin; Hao, Jianchao; Liu, Congqiang; Wang, Shijie

    2015-01-01

    It is widely recognized that carbonic anhydrase (CA) participates in silicate weathering and carbonate formation. Nevertheless, it is still not known if the magnitude of the effect produced by CA on surface rock evolution changes or not. In this work, CA gene expression from Bacillus mucilaginosus and the effects of recombination protein on wollastonite dissolution and carbonate formation under different conditions are explored. Real-time fluorescent quantitative PCR was used to explore the correlation between CA gene expression and sufficiency or deficiency in calcium and CO2 concentration. The results show that the expression of CA genes is negatively correlated with both CO2 concentration and ease of obtaining soluble calcium. A pure form of the protein of interest (CA) is obtained by cloning, heterologous expression, and purification. The results from tests of the recombination protein on wollastonite dissolution and carbonate formation at different levels of CO2 concentration show that the magnitudes of the effects of CA and CO2 concentration are negatively correlated. These results suggest that the effects of microbial CA in relation to silicate weathering and carbonate formation may have increased importance at the modern atmospheric CO2 concentration compared to 3 billion years ago.

  16. Effect of Errors in Measuring Leaf Temperature and Ambient Gas Concentration on Calculated Resistances to CO2 and Water Vapor Exchanges in Plant Leaves

    PubMed Central

    Slatyer, R. O.

    1971-01-01

    Errors as small as 1 C in the measurement of leaf temperature (Tleaf) are shown to cause significant changes in the estimated value of the stomatal resistance (expressed in terms of total resistance to water vapor transfer, ∑rH2O). The effect increases as Tleaf increases and as ambient relative humidity increases, if other conditions are maintained constant. The effect on the key CO2 exchange parameter, the intracellular (or mesophyll) resistance, rint, tends to be small under open stomata conditions but increases rapidly as stomatal closure occurs, particularly if the true value of rint is relatively small. Errors in the determination of the ambient water vapor and CO2 concentrations can also significantly affect the calculated value of ∑rH2O and rint. The effect on ∑rH2O and ∑rCO2 increases as the ratio of the inlet/outlet concentration departs from unity and also increases as the assumed leaf-air concentration difference decreases. The combined effect on rint tends to be less than the individual effects on ∑rH2O and ∑rCO2 since both are in the same direction. PMID:16657607

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

    PubMed Central

    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

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

    NASA Astrophysics Data System (ADS)

    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

  19. [Near surface CO2 concentration and its quantitative relationship with character of underlying surface in Shanghai City, China].

    PubMed

    Pan, Chen; Zhu, Xi-yang; Jia, Wen-xiao; Yang, Fang; Liu, Ming; Xiang, Wei-ning

    2015-07-01

    Land use change and fossil fuel combustion due to urbanization have a significant effect on global carbon cycle and climate change. It's important to have an explicit understanding of the spatial distribution of CO2 to recognize and control GHG emission, which is helpful to reduce human-induced contribution to global climate change. The study area of this project was set in the city of Shanghai with intensive human activity and rapid urbanization. The monitoring of near surface CO2 concentration along 3 transects was conducted across an urban-rural gradient by means of near infrared gas analyzer Li-840A in spring, 2014. Remote sensing data were also used to derive underlying surface information. Further quantitative analysis of the mechanism of CO2 concentration's response to the characteristics of underlying surface was presented in this paper. The results showed that the average near surface CO2 concentration was (443.4±22.0) µmol . mol-1. CO2 concentration in city center was in average 12.5% (52.5 µLmol . mol-1) higher than that in the suburban area. Also, CO2 concentration showed a significant spatial differentiation, with the highest CO2 concentration in the northwest, the second highest in the southwest, and the lowest in the southeast, which was in accordance with the urbanization level of the underlying surface. The results revealed that the vegetation coverage rate (CVeg) was an important indicator to describe near surface CO2 concentration with a negative correlation, and the impervious surface area coverage rate (CISA) had lower explanatory power with a positive correlation. The study also found that the determination coefficient (R2) between CO2 concentration (CCO2) and CISA or CVeg achieved its highest value when the buffer distance was 5 km, and their quantitative relationships be described by a stepwise regression equation: CCO2=0.32CISA-0.89CVeg+445.13 (R2 =0.66, P<0.01). PMID:26710641

  20. Effect of irradiance, sucrose, and CO2 concentration on the growth of potato (Solanum tuberosum L.) in vitro

    NASA Technical Reports Server (NTRS)

    Yorio, Neil C.; Wheeler, Raymond M.; Weigel, Russell C.

    1995-01-01

    Growth measurements were taken of potato plantlets (Solanum tuberosum L.) cvs. Norland (NL), Denali (DN), and Kennebec (KN), grown in vitro. Studies were conducted in a growth chamber, with nodal explants grown for 21 days on Murashige and Skoog salts with either 0, 1, 2, or 3% sucrose and capped with loose-fitted Magenta 2-way caps that allowed approximately 2.25 air exchanges/hour. Plantlets were exposed to either 100 or 300 micro mol/sq m/s photosynthetic photon flux (PPF), and the growth chamber was maintained at either 400 or 4000 micro mol/mol CO2. Regardless of PPF, all cvs. that were grown at 4000 micro mol/mol CO2 showed significant increases in total plantlet dry weight (TDW) and shoot length (SL) when sucrose was omitted from the media, indicating an autotrophic response. At 400 micro mol/mol CO2, all cvs. showed an increase in TDW and SL with increasing sucrose under both PPF levels. Within any sucrose treatment, the highest TDW for all cvs. resulted from 300 micro mol/sq m/s PPF and 4000 micro mol/mol CO2 At 4000 micro mol/mol CO2, TDW showed no further increase with sucrose levels above 1% for cvs. NL and DN at both PPF levels, suggesting that sucrose levels greater than 1% may hinder growth when CO2 enrichment is used.

  1. Electroviscous effect of concentrated suspensions in salt-free media: water dissociation and CO2 influence.

    PubMed

    Ruiz-Reina, Emilio; Carrique, Félix

    2010-05-15

    The electroviscous effect of realistic salt-free colloidal suspensions is analyzed theoretically. We study the influence on the electroviscous coefficient of the surface charge density and the particle volume fraction. By realistic salt-free colloidal suspensions we mean aqueous suspensions which have been deionized as far as possible without any electrolyte added during the preparation, in which the only ions present can be (i) the so-called added counterions, coming from the ionization of surface groups and thus counterbalancing the surface charge, (ii) the H(+) and OH(-) ions from water dissociation, and (iii) the ions produced by the atmospheric CO(2) contamination. Our model is elaborated in the framework of a classical mean-field theory, using the spherical cell model approach and the appropriate local equilibrium reactions. It is valid for arbitrary surface charge density and particle concentrations. We have also made a new interpretation of the electroviscous coefficient: the electroviscous coefficient p of the suspension is the ratio between the electrohydrodynamic and the pure hydrodynamic contributions to the specific viscosity of the suspension. The numerical results show that it is necessary to consider the water dissociation influence for volume fractions lower than approximately 10(-3), whereas the atmospheric contamination, if the suspensions are open to the atmosphere, is important in the region of volume fractions φ<0.03. PMID:20231023

  2. Impacts of upwind wildfire emissions on CO, CO2, and PM2.5 concentrations in Salt Lake City, Utah

    NASA Astrophysics Data System (ADS)

    Mallia, D. V.; Lin, J. C.; Urbanski, S.; Ehleringer, J.; Nehrkorn, T.

    2015-01-01

    burning is known to contribute large quantities of CO2, CO, and PM2.5 to the atmosphere. Biomass burning not only affects the area in the vicinity of fire but may also impact the air quality far downwind from the fire. The 2007 and 2012 western U.S. wildfire seasons were characterized by significant wildfire activity across much of the Intermountain West and California. In this study, we determined the locations of wildfire-derived emissions and their aggregate impacts on Salt Lake City, a major urban center downwind of the fires. To determine the influences of biomass burning emissions, we initiated an ensemble of stochastic back trajectories at the Salt Lake City receptor within the Stochastic Time-Inverted Lagrangian Transport (STILT) model, driven by wind fields from the Weather Research and Forecasting (WRF) model. The trajectories were combined with a new, high-resolution biomass burning emissions inventory—the Wildfire Emissions Inventory. Initial results showed that the WRF-STILT model was able to replicate many periods of enhanced wildfire activity observed in the measurements. Most of the contributions for the 2007 and 2012 wildfire seasons originated from fires located in Utah and central Idaho. The model results suggested that during intense episodes of upwind wildfires in 2007 and 2012, fires contributed as much as 250 ppb of CO during a 3 h period and 15 µg/m3 of PM2.5 averaged over 24 h at Salt Lake City. Wildfires had a much smaller impact on CO2 concentrations in Salt Lake City, with contributions rarely exceeding 2 ppm enhancements.

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

    PubMed

    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. PMID:27074931

  4. Associations between classroom CO2 concentrations and student attendance in Washington and Idaho

    SciTech Connect

    Shendell, Derek G.; Prill, Richard; Fisk, William J.; Apte, Michael G.; Blake, David; Faulkner, David

    2004-01-01

    Student attendance in American public schools is a critical factor in securing limited operational funding. Student and teacher attendance influence academic performance. Limited data exist on indoor air and environmental quality (IEQ) in schools, and how IEQ affects attendance, health, or performance. This study explored the association of student absence with measures of indoor minus outdoor carbon dioxide concentration (dCO{sub 2}). Absence and dCO{sub 2} data were collected from 409 traditional and 25 portable classrooms from 14 schools located in six school districts in the states of Washington and Idaho. Study classrooms had individual heating, ventilation, and air conditioning (HVAC) systems, except two classrooms without mechanical ventilation. Classroom attributes, student attendance and school-level ethnicity, gender, and socioeconomic status (SES) were included in multivariate modeling. Forty-five percent of classrooms studied had short-term indoor CO{sub 2} concentrations above 1000 parts-per-million (ppm). A 1000 ppm increase in dCO{sub 2} was associated (p < 0.05) with a 0.5% to 0.9% decrease in annual average daily attendance (ADA), corresponding to a relative 10% to 20% increase in student absence. Outside air (ventilation) rates estimated from dCO{sub 2} and other collected data were not associated with absence. Annual ADA was 2% higher (p < 0.0001) in traditional than in portable classrooms.

  5. Dynamics of air-sea CO2 fluxes in the northwestern European shelf based on voluntary observing ship and satellite observations

    NASA Astrophysics Data System (ADS)

    Marrec, P.; Cariou, T.; Macé, E.; Morin, P.; Salt, L. A.; Vernet, M.; Taylor, B.; Paxman, K.; Bozec, Y.

    2015-09-01

    From January 2011 to December 2013, we constructed a comprehensive pCO2 data set based on voluntary observing ship (VOS) measurements in the western English Channel (WEC). We subsequently estimated surface pCO2 and air-sea CO2 fluxes in northwestern European continental shelf waters using multiple linear regressions (MLRs) from remotely sensed sea surface temperature (SST), chlorophyll a concentration (Chl a), wind speed (WND), photosynthetically active radiation (PAR) and modeled mixed layer depth (MLD). We developed specific MLRs for the seasonally stratified northern WEC (nWEC) and the permanently well-mixed southern WEC (sWEC) and calculated surface pCO2 with uncertainties of 17 and 16 μatm, respectively. We extrapolated the relationships obtained for the WEC based on the 2011-2013 data set (1) temporally over a decade and (2) spatially in the adjacent Celtic and Irish seas (CS and IS), two regions which exhibit hydrographical and biogeochemical characteristics similar to those of WEC waters. We validated these extrapolations with pCO2 data from the SOCAT and LDEO databases and obtained good agreement between modeled and observed data. On an annual scale, seasonally stratified systems acted as a sink of CO2 from the atmosphere of -0.6 ± 0.3, -0.9 ± 0.3 and -0.5 ± 0.3 mol C m-2 yr-1 in the northern Celtic Sea, southern Celtic sea and nWEC, respectively, whereas permanently well-mixed systems acted as source of CO2 to the atmosphere of 0.2 ± 0.2 and 0.3 ± 0.2 mol C m-2 yr-1 in the sWEC and IS, respectively. Air-sea CO2 fluxes showed important inter-annual variability resulting in significant differences in the intensity and/or direction of annual fluxes. We scaled the mean annual fluxes over these provinces for the last decade and obtained the first annual average uptake of -1.11 ± 0.32 Tg C yr-1 for this part of the northwestern European continental shelf. Our study showed that combining VOS data with satellite observations can be a powerful tool to

  6. Dynamics of air-sea CO2 fluxes in the North-West European Shelf based on Voluntary Observing Ship (VOS) and satellite observations

    NASA Astrophysics Data System (ADS)

    Marrec, P.; Cariou, T.; Macé, E.; Morin, P.; Salt, L. A.; Vernet, M.; Taylor, B.; Paxman, K.; Bozec, Y.

    2