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Sample records for increasing co2 concentration

  1. A usage of CO2 hydrate: convenient method to increase CO2 concentration in culturing algae.

    PubMed

    Nakano, Sho; Chang, Kwang-Hyeon; Shijima, Atsushi; Miyamoto, Hiroyuki; Sato, Yukio; Noto, Yuji; Ha, Jin-Yong; Sakamoto, Masaki

    2014-11-01

    The addition of CO2 to algal culture systems can increase algal biomass effectively. Generally, gas bubbling is used to increase CO2 levels in culture systems; however, it is difficult to quantitatively operate to control the concentration using this method. In this study, we tested the usability of CO2 hydrate for phytoplankton culture. Specifically, green algae Pseudokirchneriella subcapitata were cultured in COMBO medium that contained dissolved CO2 hydrate, after which its effects were evaluated. The experiment was conducted according to a general bioassay procedure (OECD TG201). CO2 promoted algae growth effectively (about 2-fold relative to the control), and the decrease in pH due to dissolution of the CO2 in water recovered soon because of photosynthesis. Since the CO2 hydrate method can control a CO2 concentration easily and quantitatively, it is expected to be useful in future applications.

  2. Will atmospheric CO2 concentration continue to increase if anthropogenic CO2 emissions cease?

    NASA Astrophysics Data System (ADS)

    MacDougall, A. H.; Eby, M.; Weaver, A. J.

    2013-12-01

    If anthropogenic CO2 emissions were to suddenly cease, the evolution of the atmospheric CO2 concentration would depend on the magnitude and sign of natural carbon sources and sinks. Experiments using Earth system models indicate that overall carbon sinks would dominate. However, these models have typically neglected the permafrost carbon pool, which has the potential to introduce an additional terrestrial source of carbon to the atmosphere. Here we use the University of Victoria Earth System Climate Model, which has recently been expanded to include permafrost carbon stocks and exchanges with the atmosphere. In a scenario of zeroed CO2 and sulphate aerosol emissions, we assess whether the warming induced by specified constant concentrations of non-CO2 greenhouse gases could slow the CO2 decline following zero emissions, or even reverse this trend and cause CO2 to increase over time. We find that a radiative forcing from non-CO2 gases of approximately 0.6 W m-2 results in a near balance of CO2 emissions from the terrestrial biosphere and uptake of CO2 by the oceans, resulting in near-constant atmospheric CO2 concentrations for at least a century after emissions are eliminated. At higher values of non-CO2 radiative forcing, CO2 concentrations increase over time, regardless of when emissions cease during the 21st century. Given that the present-day radiative forcing from non-CO2 greenhouse gases is about 0.95 W m-2, our results suggest that if we were to eliminate all CO2 and aerosols emissions without also decreasing non-CO2 greenhouse gas emissions, CO2 levels would increase over time, resulting in a small increase in climate warming. The sudden and total cessation of anthropogenic CO2 emissions is an unlikely future scenario. However, such cessation experiments provide a useful method for evaluating the relative strength of the terrestrial and oceanic carbon cycle feedbacks in the presence of forcing from non-CO2 greenhouse gasses.

  3. 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.

  4. Elevated CO2 concentration around alfalfa nodules increases N2 fixation.

    PubMed

    Fischinger, Stephanie A; Hristozkova, Marieta; Mainassara, Zaman-Allah; Schulze, Joachim

    2010-01-01

    Nodule CO2 fixation via PEPC provides malate for bacteroids and oxaloacetate for N assimilation. The process is therefore of central importance for efficient nitrogen fixation. Nodule CO2 fixation is known to depend on external CO2 concentration. The hypothesis of the present paper was that nitrogen fixation in alfalfa plants is enhanced when the nodules are exposed to elevated CO2 concentrations. Therefore nodulated plants of alfalfa were grown in a hydroponic system that allowed separate aeration of the root/nodule compartment that avoided any gas leakage to the shoots. The root/nodule compartments were aerated either with a 2500 microl l(-1) (+CO2) or zero microl l(-1) (-CO2) CO2-containing N2/O2 gas flow (80/20, v/v). Nodule CO2 fixation, nitrogen fixation, and growth were strongly increased in the +CO2 treatment in a 3-week experimental period. More intensive CO2 and nitrogen fixation coincided with higher per plant amounts of amino acids and organic acids in the nodules. Moreover, the concentration of asparagine was increased in both the nodules and the xylem sap. Plants in the +CO2 treatment tended to develop nodules with higher %N concentration and individual activity. In a parallel experiment on plants with inefficient nodules (fix-) the +CO2 treatment remained without effect. Our data support the thesis that nodule CO2 fixation is pivotal for efficient nitrogen fixation. It is concluded that strategies which enhance nodule CO2 fixation will improve nitrogen fixation and nodule formation. Moreover, sufficient CO2 application to roots and nodules is necessary for growth and efficient nitrogen fixation in hydroponic and aeroponic growth systems.

  5. 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

  6. Effects of increased CO2 concentrations on surface temperature of the early earth

    NASA Technical Reports Server (NTRS)

    Kuhn, W. R.; Kasting, J. F.

    1983-01-01

    It is pointed out that enhanced levels of CO2 in the atmosphere could have provided the necessary warming to maintain the temperature above freezing. The processes that have been proposed for these larger amounts of CO2 are increased tectonic activity, a decrease in the solubility of CO2 in the oceans, rock weathering, and sediment deposition. It is shown here that large CO2 concentrations are necessary to maintain the early earth's surface temperature at approximately today's level. A thousand times the present atmospheric level of CO2 in the atmosphere would yield a temperature of 292 K, whereas a 100-fold increase in CO2 concentration would give a temperature of 284 K. The surface warming is highly dependent on the amount of water vapor and clouds, and knowledge of both of these during the early history of the earth is scant.

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

    USDA-ARS?s Scientific Manuscript database

    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...

  8. Response of plants' water use efficiency to increasing atmospheric CO2 concentration.

    PubMed

    Wang, Guoan; Feng, Xiahong

    2012-08-21

    This study assesses plants' adaptation to the elevated atmospheric CO(2) concentrations (c(a)) using 83 tree-ring δ(13)C series from the mid- to high-latitudes of the northern hemisphere. We found that the variation of Δ with the atmospheric CO(2) concentration is nonlinear and that the range of Δ change is relatively small. After 1950, the mean increase in Δ is 0.43‰, corresponding to the average coefficient of Δ-c(a) relationship to be about 0.006‰/ ppmv CO(2). In contrast to the changes in Δ, intercellular CO(2) concentration (c(i)) and intrinsic water-use efficiency (W(i)) both increase linearly with c(a). For the past two and a half centuries, changes in the intercellular CO(2) concentration (c(i)) and intrinsic water-use efficiency (W(i)) are, on average, both about 30%, while the mean change of the c(i)/c(a) ratio is 3%. Most changes have occurred after 1950. W(i) responds to c(a) linearly with sensitivities ranging from 0.06 to 0.6 μmol CO(2)/mmol H(2)O ppmv(-1), and an average 0.33 μmol CO(2)/mmol H(2)O ppmv(-1) during the past 50 years. Statistical analysis shows that the increase in c(a) accounts for 98% of the W(i) variation. The remaining small variance is explained by altitude and temperature. Trees at higher elevations show slightly higher increase in W(i), and they are also more sensitive to the CO(2) increase than trees at lower altitudes. Trees growing at low temperature environments are slightly more sensitive to CO(2) increase than those at higher temperature sites. No significant relationship between precipitation and plants' W(i) response to the atmospheric CO(2) increase is found with these data. Although the temperature and altitude both impact the W(i) response to elevated CO(2), the size of the impact is physically small and can be omitted from ecological models.

  9. Thermodynamic balance of photosynthesis and transpiration at increasing CO2 concentrations and rapid light fluctuations.

    PubMed

    Marín, Dolores; Martín, Mercedes; Serrot, Patricia H; Sabater, Bartolomé

    2014-02-01

    Experimental and theoretical flux models have been developed to reveal the influence of sun flecks and increasing CO2 concentrations on the energy and entropy balances of the leaf. The rapid and wide range of fluctuations in light intensity under field conditions were simulated in a climatic gas exchange chamber and we determined the energy and entropy balance of the leaf based on radiation and gas exchange measurements. It was estimated that the energy of photosynthetic active radiation (PAR) accounts for half of transpiration, which is the main factor responsible for the exportation of the entropy generated in photosynthesis (Sg) out of the leaf in order to maintain functional the photosynthetic machinery. Although the response of net photosynthetic production to increasing concentrations of CO2 under fluctuating light is similar to that under continuous light, rates of transpiration respond slowly to changes of light intensity and are barely affected by the concentration of CO2 in the range of 260-495 ppm, in which net photosynthesis increases by more than 100%. The analysis of the results confirms that future increases of CO2 will improve the efficiency of the conversion of radiant energy into biomass, but will not reduce the contribution of plant transpiration to the leaf thermal balance.

  10. Increasing atmospheric humidity and CO2 concentration alleviate forest mortality risk.

    PubMed

    Liu, Yanlan; Parolari, Anthony J; Kumar, Mukesh; Huang, Cheng-Wei; Katul, Gabriel G; Porporato, Amilcare

    2017-09-12

    Climate-induced forest mortality is being increasingly observed throughout the globe. Alarmingly, it is expected to exacerbate under climate change due to shifting precipitation patterns and rising air temperature. However, the impact of concomitant changes in atmospheric humidity and CO2 concentration through their influence on stomatal kinetics remains a subject of debate and inquiry. By using a dynamic soil-plant-atmosphere model, mortality risks associated with hydraulic failure and stomatal closure for 13 temperate and tropical forest biomes across the globe are analyzed. The mortality risk is evaluated in response to both individual and combined changes in precipitation amounts and their seasonal distribution, mean air temperature, specific humidity, and atmospheric CO2 concentration. Model results show that the risk is predicted to significantly increase due to changes in precipitation and air temperature regime for the period 2050-2069. However, this increase may largely get alleviated by concurrent increases in atmospheric specific humidity and CO2 concentration. The increase in mortality risk is expected to be higher for needleleaf forests than for broadleaf forests, as a result of disparity in hydraulic traits. These findings will facilitate decisions about intervention and management of different forest types under changing climate.

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

  12. Increase in the CO2 exchange rate of leaves of Ilex rotunda with elevated atmospheric CO2 concentration in an urban canyon

    NASA Astrophysics Data System (ADS)

    Takagi, M.; Gyokusen, Koichiro; Saito, Akira

    It was found that the atmospheric carbon dioxide (CO2) concentration in an urban canyon in Fukuoka city, Japan during August 1997 was about 30 µmol mol-1 higher than that in the suburbs. When fully exposed to sunlight, in situ the rate of photosynthesis in single leaves of Ilex rotunda planted in the urban canyon was higher when the atmospheric CO2 concentration was elevated. A biochemically based model was able to predict the in situ rate of photosynthesis well. The model also predicted an increase in the daily CO2 exchange rate for leaves in the urban canyon with an increase in atmospheric CO2 concentration. However, in situ such an increase in the daily CO2 exchange rate may be offset by diminished sunlight, a higher air temperature and a lower relative humidity. Thus, the daily CO2 exchange rate predicted using the model based soleley on the environmental conditions prevailing in the urban canyon was lower than that predicted based only on environmental factors found in the suburbs.

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

    PubMed

    Wu, HongYan; Zou, DingHui; Gao, KunShan

    2008-12-01

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

  14. Adaptation of the NDIR technology to 13CO2 breath tests under increased inspiratory O2 concentrations.

    PubMed

    Vogt, Josef A; Wachter, Ulrich; Mehring, Jürgen; Radermacher, Peter; Georgieff, Michael; Fischer, Heinz; Hölscher, Uvo; Moede, Michael; Fabinski, Walter

    2009-07-01

    Nondispersive infrared spectroscopy (NDIR) allows the continuous analysis of respiratory gases. Due to its high selectivity, simple and robust setup, and small footprint, it is also used to support (13)CO(2) breath tests to assess bacterial growth in the stomach, gut, or liver function. CO(2) NDIR signals, however, are biased by oxygen in the gas matrix. This complicates NDIR-based breath tests, if the inspired oxygen concentration has to be adjusted to the subject's requirements, or hyperoxia-induced effects were studied. To avoid the oxygen-induced bias, a "dilution" approach was developed: expired gas is mixed with N(2) to lower the oxygen content down to the usual range of 15-20%. Accuracy and precision were tested using synthetic gas mixtures with increasing (13)CO(2)-to-(12)CO(2) ratios ((13)CO(2)/(12)CO(2)), either based on synthetic air with approximately 20% volume O(2) or on pure O(2). For samples with delta(13)C values smaller than 300 (or (13)CO(2)/(12)CO(2) smaller than 0.003), the dilution does not significantly increase the bias in the (13)CO(2)/(12)CO(2) determination, and the within-run imprecision is smaller than 1 delta(13)C. The practical use of this approach was validated in a pig study using a sepsis model reflecting a clinical situation that requires an increased oxygen concentration for respiration. The N(2) dilution eliminated the high bias in NDIR measurement, thus allowing the determination of the impact of oxygenation on glucose oxidation in patients ventilated with increased oxygen.

  15. A modeling analysis of the interaction between forest age and forest responsiveness to increasing CO2 concentration.

    PubMed

    Kirschbaum, Miko U F

    2005-07-01

    Typically, forests have rotations of 10-200 years. On that time scale, anthropogenic increases in atmospheric carbon dioxide concentration ([CO2]) and the associated changes in climate are expected to be substantial. These changes will, therefore, almost certainly affect the growth of presently established forest stands. Most studies on the effects of increasing [CO2] on tree growth have been made with young plants. However, the growth of trees within a forest stand varies with age. As a consequence, it is difficult to infer from the available experimental data how rising [CO2] will affect forest productivity over a full rotation. In this study, various mechanisms that may account for the slowing of forest growth with age were introduced into the forest growth model CenW, to assess how these processes affect the modeled growth response to increasing [CO2]. Inclusion of allocation shifts with tree height, individual tree mortality, changing respiration load and nutrient dynamics or age-based reductions in photosynthetic capacity had only small effects on the response to increasing [CO2]. However, when photosynthesis of mature trees was decreased as a function of size, then the growth response to increasing [CO2] was reduced because, at the same age, trees were larger in elevated than in ambient [CO2]. No simple and generally valid interactions between increasing [CO2] and forest age were identified because of the large number of interacting processes, all of which are incompletely understood. Important age x climate change interactions on productivity must occur in real forests and need to be considered to understand likely future trends. However, these interactions are complex and difficult to test. It is therefore not yet possible to predict with confidence the modification of the CO2 response by forest age.

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

    PubMed

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

    2014-05-01

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

  17. Modeling the response of forest isoprene emissions to future increases in atmospheric CO2 concentration and changes in climate (Invited)

    NASA Astrophysics Data System (ADS)

    Monson, R. K.; Heald, C. L.; Guenther, A. B.; Wilkinson, M.

    2009-12-01

    Isoprene emissions from plants to the atmosphere are sensitive to changes in temperature, light and atmospheric CO2 concentration in both the short- (seconds-to-minutes) and long-term (hours-to-months). We now understand that the different time constants for these responses are due to controls by different sets of biochemical and physiological processes n leaves. Progress has been made in the past few years toward converting this process-level understanding into quantitative models. In this talk, we consider this progress with special emphasis on the short- and long-term responses to atmospheric CO2 concentration and temperature. A new biochemically-based model is presented for describing the CO2 responses, and the model is deployed in a global context to predict interactions between the influences of temperature and CO2 on the global isoprene emission rate. The model is based on the theory of enzyme-substrate kinetics, particularly with regard to those reactions that produce puruvate or glyceraldehyde 3-phosphate, the two chloroplastic substrates for isoprene biosynthesis. In the global model, when we accounted for CO2 inhibition of isoprene emission in the long-term response, we observed little impact on present-day global isoprene emission (increase from 508 to 523 Tg C yr-1). However, the large increases in future isoprene emissions predicted from past models which are due to a projected warmer climate, were entirely offset by including the CO2 effects. The isoprene emission response to CO2 was dominated by the long-term growth environment effect, with modulations of 10% or less from the short-term effect. We use this analysis as a framework for grounding future global models of isoprene emission in biochemical and physiological observations.

  18. Subtle biological responses to increased CO2 concentrations by Phaeocystis globosa Scherffel, a harmful algal bloom species

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Smith, Walker O.; Wang, Xiaodong; Li, Shaoshan

    2010-05-01

    Recent investigations into the role of carbon dioxide on phytoplankton growth and composition have clearly shown differential effects among species and assemblages, suggesting that increases in oceanic CO2 may play a critical role in structuring lower trophic levels of marine systems in the future. Furthermore, alarming increases in the occurrence of harmful algal blooms (HABs) in coastal waters have been observed, and while not uniform among systems, appear in some manner to be linked to human impacts (eutrophication) on coastal systems. Models of HABs are in their infancy and do not at present include sophisticated biological effects or their environmental controls. Here we show that subtle biological responses occur in the HAB species Phaeocystis globosa Scherffel as a result of CO2 enrichment induced by gentle bubbling. The alga, which has a polymorphic life history involving the formation of both colonies and solitary cells, exhibited altered growth rates of colonial and solitary forms at [CO2] of 750 ppm, as well as increased colony formation. In addition, substantial modifications of elemental and photosynthetic constituents of the cells (C cell-1, N cell-1, potential quantum yield, chl a cell-1) occurred under elevated CO2 concentrations compared to those found at present CO2 levels. In contrast, other individual and population variables (e.g., colony diameter, total chlorophyll concentration, carbon/nitrogen ratio) were unaffected by increased CO2. Our results suggest that predictions of the future impacts of Phaeocystis blooms on coastal ecosystems and local biogeochemistry need to carefully examine the subtle biological responses of this alga in addition to community and ecosystem effects.

  19. 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

  20. The effect of increased atmospheric temperature and CO2 concentration during crop growth on the chemical composition and in vitro rumen fermentation characteristics of wheat straw.

    PubMed

    He, Xiangyu; Wu, Yanping; Cai, Min; Mu, Chunlong; Luo, Weihong; Cheng, Yanfen; Zhu, Weiyun

    2015-01-01

    This experiment was conducted to investigate the effects of increased atmospheric temperature and CO2 concentration during crop growth on the chemical composition and in vitro rumen fermentation characteristics of wheat straw. The field experiment was carried out from November 2012 to June 2013 at Changshu (31°32'93″N, 120°41'88″E) agro-ecological experimental station. A total of three treatments were set. The concentration of CO2 was increased to 500 μmol/mol in the first treatment (CO2 group). The temperature was increased by 2 °C in the second treatment (TEM group) and the concentration of CO2 and temperature were both increased in the third treatment (CO2 + TEM group). The mean temperature and concentration of CO2 in control group were 10.5 °C and 413 μmol/mol. At harvesting, the wheat straws were collected and analyzed for chemical composition and in vitro digestibility. Results showed that dry matter was significantly increased in all three treatments. Ether extracts and neutral detergent fiber were significantly increased in TEM and CO2 + TEM groups. Crude protein was significantly decreased in CO2 + TEM group. In vitro digestibility analysis of wheat straw revealed that gas production was significantly decreased in CO2 and CO2 + TEM groups. Methane production was significantly decreased in TEM and CO2 + TEM groups. Ammonia nitrogen and microbial crude protein were significantly decreased in all three treatments. Total volatile fatty acids were significantly decreased in CO2 and CO2 + TEM groups. In conclusion, the chemical composition of the wheat straw was affected by temperature and CO2 and the in vitro digestibility of wheat straw was reduced, especially in the combined treatment of temperature and CO2.

  1. High CO2 concentration increases relative leaf carbon gain under dynamic light in Dipterocarpus sublamellatus seedlings in a tropical rain forest, Malaysia.

    PubMed

    Tomimatsu, Hajime; Iio, Atsuhiro; Adachi, Minaco; Saw, Leng-Guan; Fletcher, Christine; Tang, Yanhong

    2014-09-01

    Understory plants in tropical forests often experience a low-light environment combined with high CO2 concentration. We hypothesized that the high CO2 concentration may compensate for leaf carbon loss caused by the low light, through increasing light-use efficiency of both steady-state and dynamic photosynthetic properties. To test the hypothesis, we examined CO2 gas exchange in response to an artificial lightfleck in Dipterocarpus sublamellatus Foxw. seedlings under contrasting CO2 conditions: 350 and 700 μmol CO2 mol(-1) air in a tropical rain forest, Pasoh, Malaysia. Total photosynthetic carbon gain from the lightfleck was about double when subjected to the high CO2 when compared with the low CO2 concentration. The increase of light-use efficiency in dynamic photosynthesis contributed 7% of the increased carbon gain, most of which was due to reduction of photosynthetic induction to light increase under the high CO2. The light compensation point of photosynthesis decreased by 58% and the apparent quantum yield increased by 26% at the high CO2 compared with those at the low CO2. The study suggests that high CO2 increases photosynthetic light-use efficiency under both steady-state and fluctuating light conditions, which should be considered in assessing the leaf carbon gain of understory plants in low-light environments. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  2. Increasing pCO2 correlates with low concentrations of intracellular dimethylsulfoniopropionate in the sea anemone Anemonia viridis

    PubMed Central

    Borell, Esther M; Steinke, Michael; Horwitz, Rael; Fine, Maoz

    2014-01-01

    Marine anthozoans maintain a mutualistic symbiosis with dinoflagellates that are prolific producers of the algal secondary metabolite dimethylsulfoniopropionate (DMSP), the precursor of the climate-cooling trace gas dimethyl sulfide (DMS). Surprisingly, little is known about the physiological role of DMSP in anthozoans and the environmental factors that regulate its production. Here, we assessed the potential functional role of DMSP as an antioxidant and determined how future increases in seawater pCO2 may affect DMSP concentrations in the anemone Anemonia viridis along a natural pCO2 gradient at the island of Vulcano, Italy. There was no significant difference in zooxanthellae genotype and characteristics (density of zooxanthellae, and chlorophyll a) as well as protein concentrations between anemones from three stations along the gradient, V1 (3232 μatm CO2), V2 (682 μatm) and control (463 μatm), which indicated that A. viridis can acclimate to various seawater pCO2. In contrast, DMSP concentrations in anemones from stations V1 (33.23 ± 8.30 fmol cell−1) and V2 (34.78 ± 8.69 fmol cell−1) were about 35% lower than concentrations in tentacles from the control station (51.85 ± 12.96 fmol cell−1). Furthermore, low tissue concentrations of DMSP coincided with low activities of the antioxidant enzyme superoxide dismutase (SOD). Superoxide dismutase activity for both host (7.84 ± 1.37 U·mg−1 protein) and zooxanthellae (2.84 ± 0.41 U·mg−1 protein) at V1 was 40% lower than at the control station (host: 13.19 ± 1.42; zooxanthellae: 4.72 ± 0.57 U·mg−1 protein). Our results provide insight into coastal DMSP production under predicted environmental change and support the function of DMSP as an antioxidant in symbiotic anthozoans. PMID:24634728

  3. Increasing pCO2 correlates with low concentrations of intracellular dimethylsulfoniopropionate in the sea anemone Anemonia viridis.

    PubMed

    Borell, Esther M; Steinke, Michael; Horwitz, Rael; Fine, Maoz

    2014-02-01

    Marine anthozoans maintain a mutualistic symbiosis with dinoflagellates that are prolific producers of the algal secondary metabolite dimethylsulfoniopropionate (DMSP), the precursor of the climate-cooling trace gas dimethyl sulfide (DMS). Surprisingly, little is known about the physiological role of DMSP in anthozoans and the environmental factors that regulate its production. Here, we assessed the potential functional role of DMSP as an antioxidant and determined how future increases in seawater pCO2 may affect DMSP concentrations in the anemone Anemonia viridis along a natural pCO2 gradient at the island of Vulcano, Italy. There was no significant difference in zooxanthellae genotype and characteristics (density of zooxanthellae, and chlorophyll a) as well as protein concentrations between anemones from three stations along the gradient, V1 (3232 μatm CO2), V2 (682 μatm) and control (463 μatm), which indicated that A. viridis can acclimate to various seawater pCO2. In contrast, DMSP concentrations in anemones from stations V1 (33.23 ± 8.30 fmol cell(-1)) and V2 (34.78 ± 8.69 fmol cell(-1)) were about 35% lower than concentrations in tentacles from the control station (51.85 ± 12.96 fmol cell(-1)). Furthermore, low tissue concentrations of DMSP coincided with low activities of the antioxidant enzyme superoxide dismutase (SOD). Superoxide dismutase activity for both host (7.84 ± 1.37 U·mg(-1) protein) and zooxanthellae (2.84 ± 0.41 U·mg(-1) protein) at V1 was 40% lower than at the control station (host: 13.19 ± 1.42; zooxanthellae: 4.72 ± 0.57 U·mg(-1) protein). Our results provide insight into coastal DMSP production under predicted environmental change and support the function of DMSP as an antioxidant in symbiotic anthozoans.

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

    PubMed

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

    2017-04-15

    Green roofs are expected to absorb and store carbon in plants and soils and thereby reduce the high CO2 concentration levels in big cities. Sedum species, which are succulent perennials, are commonly used in extensive green roofs due to their shallow root system and ability to withstand long water deficiencies. Here we examined CO2 fixation and emission rates for Mediterranean Sedum sediforme on green-roof experimental plots. During late winter to early spring, we monitored CO2 concentrations inside transparent tents placed over 1m(2) plots and followed gas exchange at the leaf level using a portable gas-exchange system. We found high rates of CO2 emission at daytime, which is when CO2 concentration in the city is the highest. Both plot- and leaf-scale measurements showed that these CO2 emissions were not fully compensated by the nighttime uptake. We conclude that although carbon sequestration may only be a secondary benefit of green roofs, for improving this ecosystem service, other plant species than Sedum should also be considered for use in green roofs, especially in Mediterranean and other semi-arid climates. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Increasing CO2 differentially affects essential and non-essential amino acid concentration of rice grains grown in cadmium-contaminated soils.

    PubMed

    Wu, Huibin; Song, Zhengguo; Wang, Xiao; Liu, Zhongqi; Tang, Shirong

    2016-09-01

    Environmental pollution by both ambient CO2 and heavy metals has been steadily increasing, but we do not know how fluctuating CO2 concentrations influence plant nutrients under high Cd pollution, especially in crops. Here, we studied the effects of elevated CO2 and Cd accumulation on proteins and amino acids in rice under Cd stress. In this pot experiment, we analyzed the amino-acid profile of 20 rice cultivars that accumulate Cd differently; the plants were grown in Cd-containing soils under ambient conditions and elevated CO2 levels. We found that although Cd concentrations appeared to be higher in most cultivars under elevated CO2 than under ambient CO2, the effect was significant only in seven cultivars. Combined exposure to Cd and elevated CO2 strongly decreased rice protein and amino acid profiles, including essential and non-essential amino acids. Under elevated CO2, the ratios of specific amino acids were either higher or lower than the optimal ratios provided by FAO/WHO, suggesting that CO2 may flatten the overall amino-acid profile, leading to an excess in some amino acids and deficiencies in others when the rice is consumed. Thus, Cd-tainted rice limits the concentration of essential amino acids in rice-based diets, and the combination with elevated CO2 further exacerbates the problem.

  6. Sudden increase in atmospheric CO2 concentration reveals strong coupling between shoot carbon uptake and root nutrient uptake in young walnut trees.

    PubMed

    Delaire, Mickaël; Frak, Ela; Sigogne, Monique; Adam, Boris; Beaujard, François; Le Roux, Xavier

    2005-02-01

    We studied the short-term (i.e., a few days) effect of a sudden increase in CO2 uptake by shoots on nutrient (NO3-, P ion, K+, Ca2+ and Mg2+) uptake by roots during vegetative growth of young walnut (Juglans nigra x J. major L.) trees. The increase in CO2 uptake was induced by a sudden increase in atmospheric CO2 concentration ([CO2]). Twelve 2-year-old trees were transplanted and grown in perlite-filled pots in a greenhouse. Rates of CO2 uptake and water loss by individual trees were determined by a branch bag method from 3 days before until 6 days after [CO2] was increased. Nutrient uptake rates were measured concurrently by a hydroponic recirculating nutrient solution system that provided non-limiting supplies of water and nutrients. Six control trees were kept in ambient [CO2] (360 ppm), and [CO2] was increased to 550 ppm for one set of three trees and to 800 ppm for another set of three trees. Before imposing the elevated [CO2] treatments, all trees exhibited similar daily water loss, CO2 uptake and nutrient uptake rates when expressed per unit leaf area to account for the tree size effect. Daily water loss rates were only slightly affected by elevated [CO2]. Carbon dioxide uptake rates greatly increased with increasing atmospheric [CO2], and nutrient uptake rates were proportional to CO2 uptake rates during the study period, except for P ion. Our results show that, despite the important carbon and nitrogen storage capacities previously observed in young walnut trees, nutrient uptake by roots is strongly coupled to carbon uptake by shoots over periods of a few days.

  7. Can increasing CO2 cool Antarctica?

    NASA Astrophysics Data System (ADS)

    Schmithuesen, Holger; Notholt, Justus; König-Langlo, Gert; Lemke, Peter

    2014-05-01

    CO2 is the strongest anthropogenic forcing agent for climate change since pre-industrial times. Like other greenhouse gases, CO2 absorbs terrestrial surface radiation and causes emission from the atmosphere to space. As the surface is generally warmer than the atmosphere, the total long-wave emission to space is commonly less than the surface emission. However, this does not hold true for the high elevated areas of central Antarctica. Our investigations show, that for the high elevated areas of Antarctica the greenhouse effect (GHE) of CO2 is commonly around zero or even negative. This is based on the quantification of GHE as the difference between long-wave surface emission and top of atmosphere emission. We demonstrate this behaviour with the help of three models: a simple two-layer model, line-by-line calculations, and an ECMWF experiment. Additionally, in this region an increase in CO2 concentration leads to an instantaneous increased long-wave energy loss to space, which is a cooling effect on the earth-atmosphere system. However, short-wave warming by the weak absorption of solar radiation by CO2 are not taken into account here. The reason for this counter-intuitive behaviour is the fact that in the interior of Antarctica the surface is often colder than the stratosphere above. Radiation from the surface in the atmospheric window emitted to space is then relatively lower compared to radiation in the main CO2 band around 15 microns, which originates mostly from the stratosphere. Increasing CO2 concentration leads to increasing emission from the atmosphere to space, while blocking additional portions of surface emission. If the surface is colder than the stratosphere, this leads to additional long-wave energy loss to space for increasing CO2. Our findings for central Antarctica are in strong contrast to the generally known effect that increasing CO2 has on the long-wave emission to space, and hence on the Antarctic climate.

  8. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Increasing atmospheric [CO2] from glacial to future concentrations affects drought tolerance via impacts on leaves, xylem and their integrated function.

    PubMed

    Medeiros, Juliana S; Ward, Joy K

    2013-08-01

    Changes in atmospheric carbon dioxide concentration ([CO2]) affect plant carbon/water tradeoffs, with implications for drought tolerance. Leaf-level studies often indicate that drought tolerance may increase with rising [CO2], but integrated leaf and xylem responses are not well understood in this respect. In addition, the influence of the low [CO2] of the last glacial period on drought tolerance and xylem properties is not well understood. We investigated the interactive effects of a broad range of [CO2] and plant water potentials on leaf function, xylem structure and function and the integration of leaf and xylem function in Phaseolus vulgaris. Elevated [CO2] decreased vessel implosion strength, reduced conduit-specific hydraulic conductance, and compromised leaf-specific xylem hydraulic conductance under moderate drought. By contrast, at glacial [CO2], transpiration was maintained under moderate drought via greater conduit-specific and leaf-specific hydraulic conductance in association with increased vessel implosion strength. Our study involving the integration of leaf and xylem responses suggests that increasing [CO2] does not improve drought tolerance. We show that, under glacial conditions, changes in leaf and xylem properties could increase drought tolerance, while under future conditions, greater productivity may only occur when higher water use can be accommodated. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  10. Increased Accumulation of Carbohydrates and Decreased Photosynthetic Gene Transcript Levels in Wheat Grown at an Elevated CO2 Concentration in the Field.

    PubMed Central

    Nie, G.; Hendrix, D. L.; Webber, A. N.; Kimball, B. A.; Long, S. P.

    1995-01-01

    Repression of photosynthetic genes by increased soluble carbohydrate concentrations may explain acclimation of photosynthesis to elevated CO2 concentration. This hypothesis was examined in a field crop of spring wheat (Triticum aestivum L.) grown at both ambient (approximately 360 [mu]mol mol-1) and elevated (550 [mu]mol mol-1) atmospheric CO2 concentrations using free-air CO2 enrichment at Maricopa, Arizona. The correspondence of steady-state levels of mRNA transcripts (coding for the 83-kD photosystem I apoprotein, sedoheptulose-1,7-bisphosphatase, phosphoribulokinase, phosphoglycerokinase, and the large and small subunits of ribulose-1,5-bisphosphate carboxylase/oxygenase) with leaf carbohydrate concentrations (glucose-6-phosphate, glucose, fructose, sucrose, fructans, and starch) was examined at different stages of crop and leaf development and through the diurnal cycle. Overall only a weak correspondence between increased soluble carbohydrate concentrations and decreased levels for nuclear gene transcripts was found. The difference in soluble carbohydrate concentration between leaves grown at elevated and current ambient CO2 concentrations diminished with crop development, whereas the difference in transcript levels increased. In the flag leaf, soluble carbohydrate concentrations declined markedly with the onset of grain filling; yet transcript levels also declined. The results suggest that, whereas the hypothesis may hold well in model laboratory systems, many other factors modified its significance in this field wheat crop. PMID:12228521

  11. 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.

  12. Aridity under conditions of increased CO2

    NASA Astrophysics Data System (ADS)

    Greve, Peter; Roderick, Micheal L.; Seneviratne, Sonia I.

    2016-04-01

    A string of recent of studies led to the wide-held assumption that aridity will increase under conditions of increasing atmospheric CO2 concentrations and associated global warming. Such results generally build upon analyses of changes in the 'aridity index' (the ratio of potential evaporation to precipitation) and can be described as a direct thermodynamic effect on atmospheric water demand due to increasing temperatures. However, there is widespread evidence that contradicts the 'warmer is more arid' interpretation, leading to the 'global aridity paradox' (Roderick et al. 2015, WRR). Here we provide a comprehensive assessment of modeled changes in a broad set of dryness metrics (primarily based on a range of measures of water availability) over a large range of realistic atmospheric CO2 concentrations. We use an ensemble of simulations from of state-of-the-art climate models to analyse both equilibrium climate experiments and transient historical simulations and future projections. Our results show that dryness is, under conditions of increasing atmospheric CO2 concentrations and related global warming, generally decreasing at global scales. At regional scales we do, however, identify areas that undergo changes towards drier conditions, located primarily in subtropical climate regions and the Amazon Basin. Nonetheless, the majority of regions, especially in tropical and mid- to northern high latitudes areas, display wetting conditions in a warming world. Our results contradict previous findings and highlight the need to comprehensively assess all aspects of changes in hydroclimatological conditions at the land surface. Roderick, M. L., P. Greve, and G. D. Farquhar (2015), On the assessment of aridity with changes in atmospheric CO2, Water Resour. Res., 51, 5450-5463

  13. Differential Response in Plant Taxa Morphology and Physiology During Increases in Late-Quaternary Atmospheric CO2 Concentrations Affect Plant-Climate Interactions.

    NASA Astrophysics Data System (ADS)

    van de Water, P. K.; Barnum, E.

    2004-12-01

    The effects of changing atmospheric CO2 on plant physiology mediate vegetation response to climate change. For example, growth chamber studies on short-lived plants show significant changes in plant morphology and physiological parameters such as changes in biomass and water-use efficiency (WUE; the amount of carbon assimilated to plant water-loss) as atmospheric CO2 concentrations increases from ˜200 p.p.m. to modern concentrations and beyond. Many modern studies show WUE increases linearly with rising atmospheric CO2 meaning that less water is expended for each unit of carbon assimilated. To test for the consistency of these findings with past, long-lived plants and in past communities growing under a similar range of atmospheric CO2 levels, macrofossils of select species were analyzed from packrat (Neotoma sp.) midden chronologies gathered throughout western North America. Measurement of and analysis for the stable isotope content of these macrofossils shows greater morphological and eco-physiological differences between species than expected from study results using growth chambers. For example, isotopic analysis shows long-standing associates, Pinus edulis and Juniperus spp. have significantly different WUE during the transition from the Pleistocene to the Holocene. The WUE in Pinus edulis matches changes in atmospheric CO2 whereas Juniperus spp. does not. Yet over the same period, changes observed in Pinus flexilis needles from trees growing in cooler habitats above the pinyon-juniper woodlands are more similar to Juniperus spp. changes compared against trends in the more closely related Pinus edulis. Morphology changes occurring during this period include increased biomass and reduced stomata. These results show taxonomic differences in the morphological and physiological adaptation to changing CO2 concentrations. These responses need further assessment especially in light of their direct affect on plant-climate interactions.

  14. Recent and Projected Increases in Atmospheric CO2 Concentration Can Enhance Gene Flow between Wild and Genetically Altered Rice (Oryza sativa)

    PubMed Central

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

    2012-01-01

    Although recent and projected increases in atmospheric carbon dioxide can alter plant phenological development, these changes have not been quantified in terms of floral outcrossing rates or gene transfer. Could differential phenological development in response to rising CO2 between genetically modified crops and wild, weedy relatives increase the spread of novel genes, potentially altering evolutionary fitness? Here we show that increasing CO2 from an early 20th century concentration (300 µmol mol−1) to current (400 µmol mol−1) and projected, mid-21st century (600 µmol mol−1) values, enhanced the flow of genes from wild, weedy rice to the genetically altered, herbicide resistant, cultivated population, with outcrossing increasing from 0.22% to 0.71% from 300 to 600 µmol mol−1. The increase in outcrossing and gene transfer was associated with differential increases in plant height, as well as greater tiller and panicle production in the wild, relative to the cultivated population. In addition, increasing CO2 also resulted in a greater synchronicity in flowering times between the two populations. The observed changes reported here resulted in a subsequent increase in rice dedomestication and a greater number of weedy, herbicide-resistant hybrid progeny. Overall, these data suggest that differential phenological responses to rising atmospheric CO2 could result in enhanced flow of novel genes and greater success of feral plant species in agroecosystems. PMID:22649533

  15. The rise of the photosynthetic rate when light intensity increases is delayed in ndh gene-defective tobacco at high but not at low CO2 concentrations.

    PubMed

    Martín, Mercedes; Noarbe, Dolores M; Serrot, Patricia H; Sabater, Bartolomé

    2015-01-01

    The 11 plastid ndh genes have hovered frequently on the edge of dispensability, being absent in the plastid DNA of many algae and certain higher plants. We have compared the photosynthetic activity of tobacco (Nicotiana tabacum, cv. Petit Havana) with five transgenic lines (ΔndhF, pr-ΔndhF, T181D, T181A, and ndhF FC) and found that photosynthetic performance is impaired in transgenic ndhF-defective tobacco plants at rapidly fluctuating light intensities and higher than ambient CO2 concentrations. In contrast to wild type and ndhF FC, which reach the maximum photosynthetic rate in less than 1 min when light intensity suddenly increases, ndh defective plants (ΔndhF and T181A) show up to a 5 min delay in reaching the maximum photosynthetic rate at CO2 concentrations higher than the ambient 360 ppm. Net photosynthesis was determined at different CO2 concentrations when sequences of 130, 870, 61, 870, and 130 μmol m(-2) s(-1) PAR sudden light changes were applied to leaves and photosynthetic efficiency and entropy production (Sg) were determined as indicators of photosynthesis performance. The two ndh-defective plants, ΔndhF and T181A, had lower photosynthetic efficiency and higher Sg than wt, ndhF FC and T181D tobacco plants, containing full functional ndh genes, at CO2 concentrations above 400 ppm. We propose that the Ndh complex improves cyclic electron transport by adjusting the redox level of transporters during the low light intensity stage. In ndhF-defective strains, the supply of electrons through the Ndh complex fails, transporters remain over-oxidized (specially at high CO2 concentrations) and the rate of cyclic electron transport is low, impairing the ATP level required to rapidly reach high CO2 fixation rates in the following high light phase. Hence, ndh genes could be dispensable at low but not at high atmospheric concentrations of CO2.

  16. The rise of the photosynthetic rate when light intensity increases is delayed in ndh gene-defective tobacco at high but not at low CO2 concentrations

    PubMed Central

    Martín, Mercedes; Noarbe, Dolores M.; Serrot, Patricia H.; Sabater, Bartolomé

    2015-01-01

    The 11 plastid ndh genes have hovered frequently on the edge of dispensability, being absent in the plastid DNA of many algae and certain higher plants. We have compared the photosynthetic activity of tobacco (Nicotiana tabacum, cv. Petit Havana) with five transgenic lines (ΔndhF, pr-ΔndhF, T181D, T181A, and ndhF FC) and found that photosynthetic performance is impaired in transgenic ndhF-defective tobacco plants at rapidly fluctuating light intensities and higher than ambient CO2 concentrations. In contrast to wild type and ndhF FC, which reach the maximum photosynthetic rate in less than 1 min when light intensity suddenly increases, ndh defective plants (ΔndhF and T181A) show up to a 5 min delay in reaching the maximum photosynthetic rate at CO2 concentrations higher than the ambient 360 ppm. Net photosynthesis was determined at different CO2 concentrations when sequences of 130, 870, 61, 870, and 130 μmol m-2 s-1 PAR sudden light changes were applied to leaves and photosynthetic efficiency and entropy production (Sg) were determined as indicators of photosynthesis performance. The two ndh-defective plants, ΔndhF and T181A, had lower photosynthetic efficiency and higher Sg than wt, ndhF FC and T181D tobacco plants, containing full functional ndh genes, at CO2 concentrations above 400 ppm. We propose that the Ndh complex improves cyclic electron transport by adjusting the redox level of transporters during the low light intensity stage. In ndhF-defective strains, the supply of electrons through the Ndh complex fails, transporters remain over-oxidized (specially at high CO2 concentrations) and the rate of cyclic electron transport is low, impairing the ATP level required to rapidly reach high CO2 fixation rates in the following high light phase. Hence, ndh genes could be dispensable at low but not at high atmospheric concentrations of CO2. PMID:25709611

  17. Assessment of cultivated and wild, weedy rice lines to concurrent changes in CO2 concentration and air temperature: Determining traits for enhanced seed yield with increasing atmospheric CO2

    USDA-ARS?s Scientific Manuscript database

    Although a number of studies have examined intra-specific variability in growth and yield to projected atmospheric CO2 concentration, [CO2], none have compared the relative responses of cultivated and wild, weedy crop lines. We quantified the growth and seed yield response for three cultivated ("44...

  18. 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

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  20. Searching for a Relationship Between Forest Water Use and Increasing Atmospheric CO2 Concentration with Long-Term Hydrologic Data from the Hubbard Brook Experimental Forest

    SciTech Connect

    Amthor, J.S.

    1998-11-01

    Increases in atmospheric C02 concentration from mid-1956 through mid-1997 were compared with hydrologic records from five forested, gaged watersheds in the Hubbard Brook Experimental Forest (HBEF) in New Hampshire, U.S.A. The purpose of the comparison was to assess whether a relationship between increasing atmospheric CO2 concentration and whole-ecosystem evapotranspiration (ET) could be determined. The HBEF is particularly well suited to this type of study because of the length of the hydrologic record and the physical properties of the watersheds. This analysis is based on HBEF water years (which begin 1 June and end the following 31 May) rather than calendar years. Hydrologic records from individual watersheds used in this analysis ranged from 28 to 41 water years. During the full 41-water-year period, it is estimated that water-year mean atmospheric CO2 concentration increased more than 15% (from about 314 to 363 ppm). In one south-facing watershed (i.e., HBEF watershed 3), there was a statistically significant negative relationship between atmospheric C02 concentration and ET. This translated into a nearly 77 rnndyear reduction in ET as a result of a 50 ppm increase in atmospheric C02 concentration, a result of practical significance. Evapotranspiration from the other watersheds was also negatively related to atmospheric CO2 concentration, but with smaller (and statistically insignificant) magnitudes. Evapotranspiration from the three south-facing (but not the two north-facing) watersheds included in the analysis was "abnormally" low during the most recent 2 years (i.e., water years beginning in 1995 and 1996), and this affected the trends in ET. This recent and abrupt, reduction in ET deserves further analysis, most importantly by an extension of the hydrologic record through continued long-term monitoring in the HBEF (which is ongoing). If ET remains relatively low during the coming years in south-facing watersheds, studies of the physical and/or biological

  1. Tree ring proxies show physiological responses of eastern red cedar to increased CO2 and SO4 concentrations over the 20th century

    NASA Astrophysics Data System (ADS)

    Thomas, R. B.; Spal, S.; Maxwell, S.; Nippert, J. B.

    2011-12-01

    We examined the relationships between tree growth during the past century and the ratio of internal carbon dioxide concentration to atmospheric CO2 concentration (ci/ca) and instantaneous water-use efficiency (iWUE) by analyzing δ13C in tree rings of Juniperus virginiana growing on a limestone outcrop in West Virginia, US. Tree rings from years 1909 to 2008 from five Juniperus virginiana trees that ranged from 116 years to over 300 years in age were measured for basal area growth and used for isotopic analysis. Instantaneous WUE increased from approximately 75 to 112μmol mmol-1 over the past century, representing a 49% increase. In addition, we found a positive relationship between iWUE and the basal area increase over this time period, suggesting the increase in WUE translated into greater growth of the Juniperus trees. Typically, we might expect that increased growth of these trees reflects increased photosynthetic rates and decreased stomatal conductance rates resulting from increased atmospheric CO2 concentrations. However, this area of the central Appalachian Mountains has historically received some of the highest rates of acid deposition in the nation resulting from being downwind from an abundance of coal-fired power plants in the Ohio River valley. Our results show that ci/ca declined 14% between 1909 and 1980, but increased 9.6% between 1980 and 2009. We hypothesize that the directional change in ci/ca that occurred around 1980 was due to a reduction in sulfur emissions imposed by the Clean Air Act, environmental legislation enacted in 1970 and amended in 1990. Sulfur deposition measured by the National Atmospheric Deposition Program (NADP) in West Virginia near our Juniperus site shows a 53% decline between 1979 and 2009 and these NADP data show a highly significant negative correlation with ci/ca of Juniperus over this time period. Previously, experimental studies have shown that acidic sulfur mist leaches calcium from leaves causing a reduction in

  2. Photoassimilation, assimilate translocation and plasmodesmal biogenesis in the source leaves of Arabidopsis thaliana grown under an increased atmospheric CO2 concentration.

    PubMed

    Duan, Zhongrui; Homma, Ayumi; Kobayashi, Megumi; Nagata, Noriko; Kaneko, Yasuko; Fujiki, Yuki; Nishida, Ikuo

    2014-02-01

    Using 18-day-old Arabidopsis thaliana seedlings grown under increased (780 p.p.m., experimental plants) or ambient (390 p.p.m., control plants) CO2 conditions, we evaluated (14)CO2 photoassimilation in and translocation from representative source leaves. The total (14)CO2 photoassimilation amounts increased in the third leaves of the experimental plants in comparison with that found for the third leaves of the control plants, but the rates were comparable for the first leaves of the two groups. In contrast, translocation of labeled assimilates doubled in the first leaves of the experimental group, whereas translocation was, at best, passively enhanced even though photoassimilation increased in their third leaves. The transcript levels of the companion cell-specific sucrose:H(+) symporter gene SUC2 were not significantly affected in the two groups of plants, whereas those of the sucrose effluxer gene SWEET12 and the sieve element-targeted sucrose:H(+) symporter gene SUT4 were up-regulated in the experimental plants, suggesting up-regulation of SUT4-dependent apoplastic phloem loading. Compared with SUC2, SUT4 is a minor component that is expressed in companion cells but functions in sieve elements after transfer through plasmodesmata. The number of aniline blue-stained spots for plasmodesma-associated callose in the midrib wall increased in the first leaf of the experimental plants but was comparable in the third leaf between the experimental and control plants. These results suggest that A. thaliana responds to greater than normal concentrations of CO2 differentially in the first and third leaves in regards to photoassimilation, assimilate translocation and plasmodesmal biogenesis.

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

    USDA-ARS?s Scientific Manuscript database

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

  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. 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

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

    PubMed

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

    1999-03-01

    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

  7. Increasing CO2 threatens human nutrition.

    PubMed

    Myers, Samuel S; Zanobetti, Antonella; Kloog, Itai; Huybers, Peter; Leakey, Andrew D B; Bloom, Arnold J; Carlisle, Eli; Dietterich, Lee H; Fitzgerald, Glenn; Hasegawa, Toshihiro; Holbrook, N Michele; Nelson, Randall L; Ottman, Michael J; Raboy, Victor; Sakai, Hidemitsu; Sartor, Karla A; Schwartz, Joel; Seneweera, Saman; Tausz, Michael; Usui, Yasuhiro

    2014-06-05

    Dietary deficiencies of zinc and iron are a substantial global public health problem. An estimated two billion people suffer these deficiencies, causing a loss of 63 million life-years annually. Most of these people depend on C3 grains and legumes as their primary dietary source of zinc and iron. Here we report that C3 grains and legumes have lower concentrations of zinc and iron when grown under field conditions at the elevated atmospheric CO2 concentration predicted for the middle of this century. C3 crops other than legumes also have lower concentrations of protein, whereas C4 crops seem to be less affected. Differences between cultivars of a single crop suggest that breeding for decreased sensitivity to atmospheric CO2 concentration could partly address these new challenges to global health.

  8. Elevated atmospheric CO2 concentration leads to increased whole-plant isoprene emission in hybrid aspen (Populus tremula × Populus tremuloides).

    PubMed

    Sun, Zhihong; Niinemets, Ülo; Hüve, Katja; Rasulov, Bahtijor; Noe, Steffen M

    2013-05-01

    Effects of elevated atmospheric [CO2] on plant isoprene emissions are controversial. Relying on leaf-scale measurements, most models simulating isoprene emissions in future higher [CO2] atmospheres suggest reduced emission fluxes. However, combined effects of elevated [CO2] on leaf area growth, net assimilation and isoprene emission rates have rarely been studied on the canopy scale, but stimulation of leaf area growth may largely compensate for possible [CO2] inhibition reported at the leaf scale. This study tests the hypothesis that stimulated leaf area growth leads to increased canopy isoprene emission rates. We studied the dynamics of canopy growth, and net assimilation and isoprene emission rates in hybrid aspen (Populus tremula × Populus tremuloides) grown under 380 and 780 μmol mol(-1) [CO2]. A theoretical framework based on the Chapman-Richards function to model canopy growth and numerically compare the growth dynamics among ambient and elevated atmospheric [CO2]-grown plants was developed. Plants grown under elevated [CO2] had higher C : N ratio, and greater total leaf area, and canopy net assimilation and isoprene emission rates. During ontogeny, these key canopy characteristics developed faster and stabilized earlier under elevated [CO2]. However, on a leaf area basis, foliage physiological traits remained in a transient state over the whole experiment. These results demonstrate that canopy-scale dynamics importantly complements the leaf-scale processes, and that isoprene emissions may actually increase under higher [CO2] as a result of enhanced leaf area production. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  9. [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.

  10. Reversibility of ENSO in Response to CO2 Concentration Changes

    NASA Astrophysics Data System (ADS)

    Ohba, M.; Nohara, D.

    2013-12-01

    The degree of hysteresis in the behavior of El Niño/Southern Oscillation (ENSO) is examined by using an air-sea coupled climate model, Community Climate System Model version 4. The model is run under simple and idealized climate change scenarios where atmospheric CO2 concentration is gradually increased to four times the pre-industrial level and then gradually reduced at a similar rate along this trajectory. While the simulated ENSO amplitude is reduced when CO2 concentration increases, the amplitude is enhanced when CO2 decreases. This enhancement occurs with a relative El Niño-like warming of sea surface temperature. Most of the El Niño-like warming is attributed to a weakened cold-water upwelling in the equatorial eastern Pacific. This weakened cooling is due to a vertical ocean-temperature gradient that is reduced in relation to a lag between subsurface temperature warming and surface temperature change. From these findings, an ENSO parameterization method for simple climate models is proposed by considering the hysteresis of ocean heat content. This new method captures, relatively well, the ENSO amplitude variation that is asynchronous in response to the CO2 concentration change. Ensemble mean differences in the standard deviation of monthly mean surface temperature and precipitation anomalies between the last 50-yrs of ramp-down phase and the first 50-yrs of ramp-up phase. The two periods show the same CO2 concentrations. The anomalies are derived from 31-yr running window to suppress long-term change. Time series of the globally averaged (a) CO2 concentration (ppmv) and (b) ensemble mean of surface temperature (K) in the ramp-up and ramp-down experiments. During the ramp-up phase, CO2 concentration increases at 1% yr-1 starting at the pre-industrial level. During the ramp-down phase, CO2 decreases at 1% yr-1 starting from 4x CO2. The red line in (b) is a simulated Niño-3.4 index derived from one of the ensemble members. (c) Time-longitude section of

  11. CO(2)-concentrating: consequences in crassulacean acid metabolism.

    PubMed

    Lüttge, Ulrich

    2002-11-01

    The consequences of CO(2)-concentrating in leaf air-spaces of CAM plants during daytime organic acid decarboxylation in Phase III of CAM (crassulacean acid metabolism) are explored. There are mechanistic consequences of internal CO(2) partial pressures, p(i)(CO(2)). These are (i) effects on stomata, i.e. high p(i)(CO(2)) eliciting stomatal closure in Phase III, (ii) regulation of malic acid remobilization from the vacuole, malate decarboxylation and refixation of CO(2) via Rubisco (ribulose bisphosphate carboxylase/oxygenase), and (iii) internal signalling functions during the transitions between Phases II and III and III and IV, respectively, in the natural day/night cycle and in synchronizing the circadian clocks of individual leaf cells or leaf patches in the free-running endogenous rhythmicity of CAM. There are ecophysiological consequences. Obvious beneficial ecophysiological consequences are (i) CO(2)-acquisition, (ii) increased water-use- efficiency, (iii) suppressed photorespiration, and (iv) reduced oxidative stress by over-energization of the photosynthetic apparatus. However, the general potency of these beneficial effects may be questioned. There are also adverse ecophysiological consequences. These are (i) energetics, (ii) pH effects and (iii) Phase III oxidative stress. A major consequence of CO(2)-concentrating in Phase III is O(2)-concentrating, increased p(i)(CO(2)) is accompanied by increased p(i)(O(2)). Do reversible shifts of C(3)/CAM-intermediate plants between the C(3)-CAM-C(3) modes of photosynthesis indicate that C(3)-photosynthesis provides better protection from irradiance stress? There are many open questions and CAM remains a curiosity.

  12. 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.

  13. 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.

  14. The possible evolution and future of CO2-concentrating mechanisms.

    PubMed

    Raven, John A; Beardall, John; Sánchez-Baracaldo, Patricia

    2017-06-01

    CO2-concentrating mechanisms (CCMs), based either on active transport of inorganic carbon (biophysical CCMs) or on biochemistry involving supplementary carbon fixation into C4 acids (C4 and CAM), play a major role in global primary productivity. However, the ubiquitous CO2-fixing enzyme in autotrophs, Rubisco, evolved at a time when atmospheric CO2 levels were very much higher than today and O2 was very low and, as CO2 and O2 approached (by no means monotonically), today's levels, at some time subsequently many organisms evolved a CCM that increased the supply of CO2 and decreased Rubisco oxygenase activity. Given that CO2 levels and other environmental factors have altered considerably between when autotrophs evolved and the present day, and are predicted to continue to change into the future, we here examine the drivers for, and possible timing of, evolution of CCMs. CCMs probably evolved when CO2 fell to 2-16 times the present atmospheric level, depending on Rubisco kinetics. We also assess the effects of other key environmental factors such as temperature and nutrient levels on CCM activity and examine the evidence for evolutionary changes in CCM activity and related cellular processes as well as limitations on continuity of CCMs through environmental variations. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  15. 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

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

    USDA-ARS?s Scientific Manuscript database

    Although recent and projected increases in atmospheric carbon dioxide can alter plant phenological development, these changes have not been quantified in terms of floral outcrossing rates or gene transfer. Could differential phenological development in response to rising CO2 between genetically mod...

  17. Effect of increasing CO2 on the terrestrial carbon cycle

    PubMed Central

    Schimel, David; Fisher, Joshua B.

    2015-01-01

    Feedbacks from the terrestrial carbon cycle significantly affect future climate change. The CO2 concentration dependence of global terrestrial carbon storage is one of the largest and most uncertain feedbacks. Theory predicts the CO2 effect should have a tropical maximum, but a large terrestrial sink has been contradicted by analyses of atmospheric CO2 that do not show large tropical uptake. Our results, however, show significant tropical uptake and, combining tropical and extratropical fluxes, suggest that up to 60% of the present-day terrestrial sink is caused by increasing atmospheric CO2. This conclusion is consistent with a validated subset of atmospheric analyses, but uncertainty remains. Improved model diagnostics and new space-based observations can reduce the uncertainty of tropical and temperate zone carbon flux estimates. This analysis supports a significant feedback to future atmospheric CO2 concentrations from carbon uptake in terrestrial ecosystems caused by rising atmospheric CO2 concentrations. This feedback will have substantial tropical contributions, but the magnitude of future carbon uptake by tropical forests also depends on how they respond to climate change and requires their protection from deforestation. PMID:25548156

  18. Effect of increasing CO2 on the terrestrial carbon cycle.

    PubMed

    Schimel, David; Stephens, Britton B; Fisher, Joshua B

    2015-01-13

    Feedbacks from the terrestrial carbon cycle significantly affect future climate change. The CO2 concentration dependence of global terrestrial carbon storage is one of the largest and most uncertain feedbacks. Theory predicts the CO2 effect should have a tropical maximum, but a large terrestrial sink has been contradicted by analyses of atmospheric CO2 that do not show large tropical uptake. Our results, however, show significant tropical uptake and, combining tropical and extratropical fluxes, suggest that up to 60% of the present-day terrestrial sink is caused by increasing atmospheric CO2. This conclusion is consistent with a validated subset of atmospheric analyses, but uncertainty remains. Improved model diagnostics and new space-based observations can reduce the uncertainty of tropical and temperate zone carbon flux estimates. This analysis supports a significant feedback to future atmospheric CO2 concentrations from carbon uptake in terrestrial ecosystems caused by rising atmospheric CO2 concentrations. This feedback will have substantial tropical contributions, but the magnitude of future carbon uptake by tropical forests also depends on how they respond to climate change and requires their protection from deforestation.

  19. Spatial response of coastal marshes to increased atmospheric CO2

    PubMed Central

    Ratliff, Katherine M.; Braswell, Anna E.; Marani, Marco

    2015-01-01

    The elevation and extent of coastal marshes are dictated by the interplay between the rate of relative sea-level rise (RRSLR), surface accretion by inorganic sediment deposition, and organic soil production by plants. These accretion processes respond to changes in local and global forcings, such as sediment delivery to the coast, nutrient concentrations, and atmospheric CO2, but their relative importance for marsh resilience to increasing RRSLR remains unclear. In particular, marshes up-take atmospheric CO2 at high rates, thereby playing a major role in the global carbon cycle, but the morphologic expression of increasing atmospheric CO2 concentration, an imminent aspect of climate change, has not yet been isolated and quantified. Using the available observational literature and a spatially explicit ecomorphodynamic model, we explore marsh responses to increased atmospheric CO2, relative to changes in inorganic sediment availability and elevated nitrogen levels. We find that marsh vegetation response to foreseen elevated atmospheric CO2 is similar in magnitude to the response induced by a varying inorganic sediment concentration, and that it increases the threshold RRSLR initiating marsh submergence by up to 60% in the range of forcings explored. Furthermore, we find that marsh responses are inherently spatially dependent, and cannot be adequately captured through 0-dimensional representations of marsh dynamics. Our results imply that coastal marshes, and the major carbon sink they represent, are significantly more resilient to foreseen climatic changes than previously thought. PMID:26644577

  20. Spatial response of coastal marshes to increased atmospheric CO2.

    PubMed

    Ratliff, Katherine M; Braswell, Anna E; Marani, Marco

    2015-12-22

    The elevation and extent of coastal marshes are dictated by the interplay between the rate of relative sea-level rise (RRSLR), surface accretion by inorganic sediment deposition, and organic soil production by plants. These accretion processes respond to changes in local and global forcings, such as sediment delivery to the coast, nutrient concentrations, and atmospheric CO2, but their relative importance for marsh resilience to increasing RRSLR remains unclear. In particular, marshes up-take atmospheric CO2 at high rates, thereby playing a major role in the global carbon cycle, but the morphologic expression of increasing atmospheric CO2 concentration, an imminent aspect of climate change, has not yet been isolated and quantified. Using the available observational literature and a spatially explicit ecomorphodynamic model, we explore marsh responses to increased atmospheric CO2, relative to changes in inorganic sediment availability and elevated nitrogen levels. We find that marsh vegetation response to foreseen elevated atmospheric CO2 is similar in magnitude to the response induced by a varying inorganic sediment concentration, and that it increases the threshold RRSLR initiating marsh submergence by up to 60% in the range of forcings explored. Furthermore, we find that marsh responses are inherently spatially dependent, and cannot be adequately captured through 0-dimensional representations of marsh dynamics. Our results imply that coastal marshes, and the major carbon sink they represent, are significantly more resilient to foreseen climatic changes than previously thought.

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  2. 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.

  3. CO2 efflux, CO2 concentration and photosynthetic refixation in stems of Eucalyptus globulus (Labill.).

    PubMed

    Cerasoli, S; McGuire, M A; Faria, J; Mourato, M; Schmidt, M; Pereira, J S; Chaves, M M; Teskey, R O

    2009-01-01

    In spite of the importance of respiration in forest carbon budgets, the mechanisms by which physiological factors control stem respiration are unclear. An experiment was set up in a Eucalyptus globulus plantation in central Portugal with monoculture stands of 5-year-old and 10-year-old trees. CO(2) efflux from stems under shaded and unshaded conditions, as well as the concentration of CO(2) dissolved in sap [CO(2)(*)], stem temperature, and sap flow were measured with the objective of improving our understanding of the factors controlling CO(2) release from stems of E. globulus. CO(2) efflux was consistently higher in 5-year-old, compared with 10-year-old, stems, averaging 3.4 versus 1.3 mumol m(-2) s(-1), respectively. Temperature and [CO(2)(*)] both had important, and similar, influences on the rate of CO(2) efflux from the stems, but neither explained the difference in the magnitude of CO(2) efflux between trees of different age and size. No relationship was found between efflux and sap flow, and efflux was independent of tree volume, suggesting the presence of substantial barriers to the diffusion of CO(2) from the xylem to the atmosphere in this species. The rate of corticular photosynthesis was the same in trees of both ages and only reduced CO(2) efflux by 7%, probably due to the low irradiance at the stem surface below the canopy. The younger trees were growing at a much faster rate than the older trees. The difference between CO(2) efflux from the younger and older stems appears to have resulted from a difference in growth respiration rather than a difference in the rate of diffusion of xylem-transported CO(2).

  4. Effects of increased CO2 levels on monsoons

    NASA Astrophysics Data System (ADS)

    Cherchi, Annalisa; Alessandri, Andrea; Masina, Simona; Navarra, Antonio

    2011-07-01

    Increased atmospheric carbon dioxide concentration provided warmer atmospheric temperature and higher atmospheric water vapor content, but not necessarily more precipitation. A set of experiments performed with a state-of-the-art coupled general circulation model forced with increased atmospheric CO2 concentration (2, 4 and 16 times the present-day mean value) were analyzed and compared with a control experiment to evaluate the effect of increased CO2 levels on monsoons. Generally, the monsoon precipitation responses to CO2 forcing are largest if extreme concentrations of carbon dioxide are used, but they are not necessarly proportional to the forcing applied. In fact, despite a common response in terms of an atmospheric water vapor increase to the atmospheric warming, two out of the six monsoons studied simulate less or equal summer mean precipitation in the 16×CO2 experiment compared to the intermediate sensitivity experiments. The precipitation differences between CO2 sensitivity experiments and CTRL have been investigated specifying the contribution of thermodynamic and purely dynamic processes. As a general rule, the differences depending on the atmospheric moisture content changes (thermodynamic component) are large and positive, and they tend to be damped by the dynamic component associated with the changes in the vertical velocity. However, differences are observed among monsoons in terms of the role played by other terms (like moisture advection and evaporation) in shaping the precipitation changes in warmer climates. The precipitation increase, even if weak, occurs despite a weakening of the mean circulation in the monsoon regions ("precipitation-wind paradox"). In particular, the tropical east-west Walker circulation is reduced, as found from velocity potential analysis. The meridional component of the monsoon circulation is changed as well, with larger (smaller) meridional (vertical) scales.

  5. Evidence that elevated CO2 levels can indirectly increase rhizosphere denitrifier activity

    NASA Technical Reports Server (NTRS)

    Smart, D. R.; Ritchie, K.; Stark, J. M.; Bugbee, B.

    1997-01-01

    We examined the influence of elevated CO2 concentration on denitrifier enzyme activity in wheat rhizoplanes by using controlled environments and solution culture techniques. Potential denitrification activity was from 3 to 24 times higher on roots that were grown under an elevated CO2 concentration of 1,000 micromoles of CO2 mol-1 than on roots grown under ambient levels of CO2. Nitrogen loss, as determined by a nitrogen mass balance, increased with elevated CO2 levels in the shoot environment and with a high NO3- concentration in the rooting zone. These results indicated that aerial CO2 concentration can play a role in rhizosphere denitrifier activity.

  6. Evidence that elevated CO2 levels can indirectly increase rhizosphere denitrifier activity

    NASA Technical Reports Server (NTRS)

    Smart, D. R.; Ritchie, K.; Stark, J. M.; Bugbee, B.

    1997-01-01

    We examined the influence of elevated CO2 concentration on denitrifier enzyme activity in wheat rhizoplanes by using controlled environments and solution culture techniques. Potential denitrification activity was from 3 to 24 times higher on roots that were grown under an elevated CO2 concentration of 1,000 micromoles of CO2 mol-1 than on roots grown under ambient levels of CO2. Nitrogen loss, as determined by a nitrogen mass balance, increased with elevated CO2 levels in the shoot environment and with a high NO3- concentration in the rooting zone. These results indicated that aerial CO2 concentration can play a role in rhizosphere denitrifier activity.

  7. Evidence that elevated CO2 levels can indirectly increase rhizosphere denitrifier activity.

    PubMed

    Smart, D R; Ritchie, K; Stark, J M; Bugbee, B

    1997-11-01

    We examined the influence of elevated CO2 concentration on denitrifier enzyme activity in wheat rhizoplanes by using controlled environments and solution culture techniques. Potential denitrification activity was from 3 to 24 times higher on roots that were grown under an elevated CO2 concentration of 1,000 micromoles of CO2 mol-1 than on roots grown under ambient levels of CO2. Nitrogen loss, as determined by a nitrogen mass balance, increased with elevated CO2 levels in the shoot environment and with a high NO3- concentration in the rooting zone. These results indicated that aerial CO2 concentration can play a role in rhizosphere denitrifier activity.

  8. Evidence that elevated CO2 levels can indirectly increase rhizosphere denitrifier activity.

    PubMed Central

    Smart, D R; Ritchie, K; Stark, J M; Bugbee, B

    1997-01-01

    We examined the influence of elevated CO2 concentration on denitrifier enzyme activity in wheat rhizoplanes by using controlled environments and solution culture techniques. Potential denitrification activity was from 3 to 24 times higher on roots that were grown under an elevated CO2 concentration of 1,000 micromoles of CO2 mol-1 than on roots grown under ambient levels of CO2. Nitrogen loss, as determined by a nitrogen mass balance, increased with elevated CO2 levels in the shoot environment and with a high NO3- concentration in the rooting zone. These results indicated that aerial CO2 concentration can play a role in rhizosphere denitrifier activity. PMID:11536820

  9. A joint global carbon inversion system using both CO2 and 13CO2 atmospheric concentration data

    NASA Astrophysics Data System (ADS)

    Chen, Jing M.; Mo, Gang; Deng, Feng

    2017-03-01

    Observations of 13CO2 at 73 sites compiled in the GLOBALVIEW database are used for an additional constraint in a global atmospheric inversion of the surface CO2 flux using CO2 observations at 210 sites (62 collocated with 13CO2 sites) for the 2002-2004 period for 39 land regions and 11 ocean regions. This constraint is implemented using prior CO2 fluxes estimated with a terrestrial ecosystem model and an ocean model. These models simulate 13CO2 discrimination rates of terrestrial photosynthesis and ocean-atmosphere diffusion processes. In both models, the 13CO2 disequilibrium between fluxes to and from the atmosphere is considered due to the historical change in atmospheric 13CO2 concentration. This joint inversion system using both13CO2 and CO2 observations is effectively a double deconvolution system with consideration of the spatial variations of isotopic discrimination and disequilibrium. Compared to the CO2-only inversion, this 13CO2 constraint on the inversion considerably reduces the total land carbon sink from 3.40 ± 0.84 to 2.53 ± 0.93 Pg C year-1 but increases the total oceanic carbon sink from 1.48 ± 0.40 to 2.36 ± 0.49 Pg C year-1. This constraint also changes the spatial distribution of the carbon sink. The largest sink increase occurs in the Amazon, while the largest source increases are in southern Africa, and Asia, where CO2 data are sparse. Through a case study, in which the spatial distribution of the annual 13CO2 discrimination rate over land is ignored by treating it as a constant at the global average of -14. 1 ‰, the spatial distribution of the inverted CO2 flux over land was found to be significantly modified (up to 15 % for some regions). The uncertainties in our disequilibrium flux estimation are 8.0 and 12.7 Pg C year-1 ‰ for land and ocean, respectively. These uncertainties induced the unpredictability of 0.47 and 0.54 Pg C year-1 in the inverted CO2 fluxes for land and ocean, respectively. Our joint inversion system is therefore

  10. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Errors in the specification or utilization of fossil fuel CO2 emissions within carbon budget or atmospheric CO2 inverse studies can alias the estimation of biospheric and oceanic carbon exchange. A key component in the simulation of CO2 concentrations arising from fossil fuel emissions is the spatial distribution of the emission near coastlines. Regridding of fossil fuel CO2 emissions (FFCO2) from fine to coarse grids to enable atmospheric transport simulations can give rise to mismatches between the emissions and simulated atmospheric dynamics which differ over land or water. For example, emissions originally emanating from the land are emitted from a grid cell for which the vertical mixing reflects the roughness and/or surface energy exchange of an ocean surface. We test this potential "dynamical inconsistency" by examining simulated global atmospheric CO2 concentration driven by two different approaches to regridding fossil fuel CO2 emissions. The two approaches are as follows: (1) a commonly used method that allocates emissions to grid cells with no attempt to ensure dynamical consistency with atmospheric transport and (2) an improved method that reallocates emissions to grid cells to ensure dynamically consistent results. Results show large spatial and temporal differences in the simulated CO2 concentration when comparing these two approaches. The emissions difference ranges from -30.3 TgC grid cell-1 yr-1 (-3.39 kgC m-2 yr-1) to +30.0 TgC grid cell-1 yr-1 (+2.6 kgC m-2 yr-1) along coastal margins. Maximum simulated annual mean CO2 concentration differences at the surface exceed ±6 ppm at various locations and times. Examination of the current CO2 monitoring locations during the local afternoon, consistent with inversion modeling system sampling and measurement protocols, finds maximum hourly differences at 38 stations exceed ±0.10 ppm with individual station differences exceeding -32 ppm. The differences implied by not accounting for this dynamical

  12. Growth at elevated CO2 concentrations leads to modified profiles of secondary metabolites in tobacco cv. SamsunNN and to increased resistance against infection with potato virus Y.

    PubMed

    Matros, Andrea; Amme, Steffen; Kettig, Barbara; Buck-Sorlin, Gerhard H; Sonnewald, Uwe; Mock, Hans-Peter

    2006-01-01

    The effect of elevated CO2 concentrations on the levels of secondary metabolites was investigated in tobacco plants grown under two nitrogen supply (5 and 8 mM NH4NO3) and CO2 conditions (350 and 1000 p.p.m.) each. High CO2 resulted in a dramatic increase of phenylpropanoids in the leaves, including the major carbon-rich compound chlorogenic acid (CGA) and the coumarins scopolin and scopoletin at both nitrogen fertilizations. This was accompanied by increased PAL activity in leaves and roots, which was even higher at the lower nitrogen supply. Hardly any change was observed for the structural phenolic polymer lignin and the sesquiterpenoid capsidiol. In contrast, elevated CO2 led to clearly decreased levels of the main nitrogen-rich constituent nicotine at the lower N-supply (5 mM NH4NO3) but not when plants were grown at the higher N-supply (8 mM NH4NO3). Inoculation experiments with potato virus Y (PVY) were used to evaluate possible ecological consequences of elevated CO2. The titre of viral coat-protein was markedly reduced in leaves under these conditions at both nitrogen levels. Since PR-gene expression and free salicylic acid (SA) levels remained unchanged at elevated CO2, we suggest that the accumulation of phenylpropanoids, for example, the major compound CGA and the coumarins scopolin and scopoletin may result in an earlier confinement of the virus at high CO2. Based on our results two final conclusions emerge. First, elevated CO2 leads to a shift in secondary metabolite composition that is dependent on the availability of nitrogen. Second, changes in the pool of secondary metabolites have important consequences for plant-pathogen interactions as shown for PVY as a test organism.

  13. 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.

  14. 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).

  15. Electrochemical CO2 concentration for the Space Station Program

    NASA Technical Reports Server (NTRS)

    Lance, N.; Schwartz, M.; Boyda, R. B.

    1985-01-01

    Under the sponsorship of NASA, Electrochemical Carbon Dioxide (CO2) Concentration EDC technology has been developed that removes CO2 continuously or cyclically from low CO2 partial pressure (400 Pa) atmospheres with the performance and operating characteristics required for Space Station applications. The most recent advancement of this technology is the development of an advanced preprototype subsystem, the CS-3A, to remove the metabolic CO2 produced by three persons from the projected Space Station atmosphere. This paper provides an overview of EDC technology, shows how it is ideally suited for Space Station application, and presents technology enhancements that will be demonstrated by the CS-3A subsystem development program.

  16. [Effects of nitrogen fertilization on wheat leaf photosynthesis under elevated atmospheric CO2 concentration].

    PubMed

    Yu, Xian-feng; Zhang, Xu-cheng; Guo, Tian-wen; Yu, Jia

    2010-09-01

    In this paper, the effects of nitrogen (N) fertilization on the wheat leaf photosynthesis under long-term elevated atmospheric CO2 concentration (760 micromol x mol(-1)) was studied, based on the measurements of photosynthetic gas exchange parameters and light intensity-photosynthetic rate response curves at jointing stage. Under the long-term elevated atmospheric CO2 concentration, applying sufficient N could increase the wheat leaf photosynthetic rate (Pn), transpiration rate (Tr), and instantaneous water use efficiency (WUEi). Comparing with those under ambient atmospheric CO2 concentration, the Po and WUEi under the elevated atmospheric CO2 concentration increased, while the stomatal conductance (Gs) and intercellular CO2 concentration (Ci) decreased. With the increase of light flux intensity, the Pn and WUEi under the elevated atmospheric CO2 concentration were higher those under ambient atmospheric CO2 concentration, Gs was in adverse, while Ci and Tr had less change. At high fertilization rate of N, the Gs was linearly positively correlated with Pn, Tr, and WUEi, and the Gs and Ci had no correlation with each other under the elevated atmospheric CO2 concentration but negatively correlated under ambient atmospheric CO2 concentration. At low fertilization rate of N, the Gs had no correlations with Pn and WUEi but linearly positively correlated with Ci and Tr. It was suggested that under the elevated atmospheric CO2 concentration, the wheat leaf Pn at low N fertilization rate was limited by non-stomatal factor.

  17. 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

  18. How increasing CO2 leads to an increased negative greenhouse effect in Antarctica

    NASA Astrophysics Data System (ADS)

    Schmithüsen, Holger; Notholt, Justus; König-Langlo, Gert; Lemke, Peter; Jung, Thomas

    2015-12-01

    CO2 is the strongest anthropogenic forcing agent for climate change since preindustrial times. Like other greenhouse gases, CO2 absorbs terrestrial surface radiation and causes emission from the atmosphere to space. As the surface is generally warmer than the atmosphere, the total long-wave emission to space is commonly less than the surface emission. However, this does not hold true for the high elevated areas of central Antarctica. For this region, the emission to space is higher than the surface emission; and the greenhouse effect of CO2 is around zero or even negative, which has not been discussed so far. We investigated this in detail and show that for central Antarctica an increase in CO2 concentration leads to an increased long-wave energy loss to space, which cools the Earth-atmosphere system. These findings for central Antarctica are in contrast to the general warming effect of increasing CO2.

  19. 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.

  20. Systems analysis of the CO2 concentrating mechanism in cyanobacteria.

    PubMed

    Mangan, Niall; Brenner, Michael

    2014-04-29

    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. Copyright © 2014, Mangan et al.

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

    PubMed

    Osada, Noriyuki; Onoda, Yusuke; Hikosaka, Kouki

    2010-09-01

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

  2. Recent increase in surface fCO2 in the western subtropical North Pacific

    NASA Astrophysics Data System (ADS)

    Kim, Dongseon; Choi, Yujeong; Kim, Tae-Wook; Park, Geun-Ha

    2017-05-01

    We observed unusually high levels (> 440 μatm) of carbon dioxide fugacity (fCO2) in surface seawater in the western subtropical North Pacific, the area where Subtropical Mode Water is formed, during summer 2015. The NOAA Kuroshio Extension Observatory moored buoy located in this region also measured high CO2 values, up to 500 μatm during this period. These high sea surface fCO2 (fCO2SW) values are explained by much higher normalized total dissolved inorganic carbon and slightly higher normalized total alkalinity concentrations in this region compared to the equatorial Pacific. Moreover, these values are much higher than the climatological CO2 values, even considering increasing atmospheric CO2, indicating a recent large increase in sea surface CO2 concentrations. A large seasonal change in sea surface temperature contributed to higher surface fCO2SW in the summer of 2015.

  3. Possible CO2 concentrating mechanism in chloroplasts of C3 plants. Role of carbonic anhydrase.

    PubMed

    Fridlyand, L E; Kaler, V L

    1987-12-01

    The possibility of a specific CO2 concentrating mechanism present in chloroplasts of C3 plants is analyzed. Proton gradient between thylakoids and the stroma is assumed to be the driving force for this process. The possible CO2 concentrating mechanisms are: 1. HCO3- permeation into thylakoids, its dehydration there and diffusion of CO2 formed into the stroma; 2. Dehydration of HCO3- present in the stroma at the thylakoid surface in a reaction with H+ leaving the thylakoids through: a) channels of membrane-bound carbonic anhydrase; b) channels of the ATPase complex. A system of equations describing CO3- and CO2 diffusion as well as CO2 assimilation and formation was used. The increase in photosynthesis rate, upon CO2 diffusion being facilitated in the presence of carbonic anhydrase, and due to the action of CO2 concentrating mechanisms, was numerically estimated. The CO2 concentrating mechanism was shown to function effectively only with the entire chloroplast being the CO2 concentrating zone. This is the case when the bulk of stromal carbonic anhydrase is localized near the inner chloroplast envelope. The existence of CO2 concentrating mechanisms around a single granum or around thylakoids is hardly possible. Approaches enabling the detection of similar concentrating mechanisms are discussed.

  4. Dynamics of soil CO2 efflux under varying atmospheric CO2 concentrations reveal dominance of slow processes.

    PubMed

    Kim, Dohyoung; Oren, Ram; Clark, James S; Palmroth, Sari; Oishi, A Christopher; McCarthy, Heather R; Maier, Chris A; Johnsen, Kurt

    2017-09-01

    We evaluated the effect on soil CO2 efflux (FCO2 ) of sudden changes in photosynthetic rates by altering CO2 concentration in plots subjected to +200 ppmv for 15 years. Five-day intervals of exposure to elevated CO2 (eCO2 ) ranging 1.0-1.8 times ambient did not affect FCO2 . FCO2 did not decrease until 4 months after termination of the long-term eCO2 treatment, longer than the 10 days observed for decrease of FCO2 after experimental blocking of C flow to belowground, but shorter than the ~13 months it took for increase of FCO2 following the initiation of eCO2 . The reduction of FCO2 upon termination of enrichment (~35%) cannot be explained by the reduction of leaf area (~15%) and associated carbohydrate production and allocation, suggesting a disproportionate contraction of the belowground ecosystem components; this was consistent with the reductions in base respiration and FCO2 -temperature sensitivity. These asymmetric responses pose a tractable challenge to process-based models attempting to isolate the effect of individual processes on FCO2 . © 2017 John Wiley & Sons Ltd.

  5. Rising CO2 concentration altered wheat grain proteome and flour rheological characteristics.

    PubMed

    Fernando, Nimesha; Panozzo, Joe; Tausz, Michael; Norton, Robert; Fitzgerald, Glenn; Khan, Alamgir; Seneweera, Saman

    2015-03-01

    Wheat cv. H45 was grown under ambient CO2 concentration and Free Air CO2 Enrichment (FACE; e[CO2], ∼550 μmol CO2 mol(-1)). The effect of FACE on wheat grain proteome and associated changes in the flour rheological properties was investigated. A comparative proteomic analysis was performed using 2-D-DIGE followed by MALDI/TOF-MS. Total grain protein concentration was decreased by 9% at e[CO2]. Relative abundance of three high molecular weight glutenin sub units (HMW-GS) were decreased at e[CO2]. In contrast, relative abundance of serpins Z1C and 1-Cys peroxiredoxin was increased at e[CO2]. Elevated [CO2] also decreased the bread volume (by 11%) and dough strength (by 7%) while increased mixing time. However, dough extensibility and dough stability were unchanged at elevated [CO2]. These findings suggest that e[CO2] has a major impact on gluten protein concentration which is associated lower bread quality at e[CO2].

  6. [Effects of plastic film mulching on soil CO2 efflux and CO2 concentration in an oasis cotton field].

    PubMed

    Yu, Yong-xiang; Zhao, Cheng-yi; Jia, Hong-tao; Yu, Bo; Zhou, Tian-he; Yang, Yu-guang; Zhao, Hua

    2015-01-01

    A field study was conducted to compare soil CO2 efflux and CO2 concentration between mulched and non-mulched cotton fields by using closed chamber method and diffusion chamber technique. Soil CO2 efflux and CO2 concentration exhibited a similar seasonal pattern, decreasing from July to October. Mulched field had a lower soil CO2 efflux but a higher CO2 concentration, compared to those of non-mulched fields. Over the measurement period, cumulative CO2 efflux was 1871.95 kg C . hm-2 for mulched field and 2032.81 kg C . hm-2 for non-mulched field. Soil CO2 concentration was higher in mulched field (ranging from 5137 to 25945 µL . L-1) than in non- mulched field (ranging from 2165 to 23986 µL . L-1). The correlation coefficients between soil CO2 concentrations at different depths and soil CO2 effluxes were 0.60 to 0.73 and 0.57 to 0.75 for the mulched and non-mulched fields, indicating that soil CO2 concentration played a crucial role in soil CO2 emission. The Q10 values were 2.77 and 2.48 for the mulched and non-mulched fields, respectively, suggesting that CO2 efflux in mulched field was more sensitive to the temperature.

  7. 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.

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

    PubMed

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

    2012-09-15

    Some morphogenetic and metabolic processes were sensitive to a high atmospheric CO(2) concentration during sunflower primary leaf ontogeny. Young leaves of sunflower plants growing under elevated CO(2) concentration exhibited increased growth, as reflected by the high specific leaf mass referred to as dry weight in young leaves (16 days). The content of photosynthetic pigments decreased with leaf development, especially in plants grown under elevated CO(2) concentrations, suggesting that high CO(2) accelerates chlorophyll degradation, and also possibly leaf senescence. Elevated CO(2) concentration increased the oxidative stress in sunflower plants by increasing H(2)O(2) levels and decreasing activity of antioxidant enzymes such as catalase and ascorbate peroxidase. The loss of plant defenses probably increases the concentration of reactive oxygen species in the chloroplast, decreasing the photosynthetic pigment content as a result. Elevated CO(2) concentration was found to boost photosynthetic CO(2) fixation, especially in young leaves. High CO(2) also increased the starch and soluble sugar contents (glucose and fructose) and the C/N ratio during sunflower primary leaf development. At the beginning of senescence, we observed a strong increase in the hexoses to sucrose ratio that was especially marked at high CO(2) concentration. These results indicate that elevated CO(2) concentration could promote leaf senescence in sunflower plants by affecting the soluble sugar levels, the C/N ratio and the oxidative status during leaf ontogeny. It is likely that systemic signals produced in plants grown with elevated CO(2), lead to early senescence and a higher oxidation state of the cells of these plant leaves. Copyright © 2012 Elsevier GmbH. All rights reserved.

  9. The expression of a carbon concentrating mechanism in Chlamydomonas acidophila under variable phosphorus, iron, and CO2 concentrations.

    PubMed

    Spijkerman, Elly

    2011-09-01

    The CO(2) acquisition was analyzed in Chlamydomonas acidophila at pH 2.4 in a range of medium P and Fe concentrations and at high and low CO(2) condition. The inorganic carbon concentrating factor (CCF) was related to cellular P quota (Q(p)), maximum CO(2)-uptake rate by photosynthesis (V(max,O2)), half saturation constant for CO(2) uptake (K(0.5)), and medium Fe concentration. There was no effect of the medium Fe concentration on the CCF. The CCF increased with increasing Q(p) in both high and low CO(2) grown algae, but maximum Q(p) was 6-fold higher in the low CO(2) cells. In high CO(2) conditions, the CCF was low, ranging between 0.8 and 3.5. High CCF values up to 9.1 were only observed in CO(2)-limited cells, but P- and CO(2)-colimited cells had a low CCF. High CCF did not relate with a low K(0.5) as all CO(2)-limited cells had a low K(0.5) (<4 μM CO(2)). High C(i)-pools in cells with high Q(p) suggested the presence of an active CO(2)-uptake mechanism. The CCF also increased with increasing V(max,O2) which reflect an adaptation to the nutrient in highest demand (CO(2)) under balanced growth conditions. It is proposed that the size of the CCF in C. acidophila is more strongly related to porter density for CO(2) uptake (reflected in V(max,O2)) and less- to high-affinity CO(2) uptake (low K(0.5)) at balanced growth. In addition, high CCF can only be realized with high Q(p).

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

    PubMed

    Cabello, Juan; Morales, Marcia; Revah, Sergio

    2017-04-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

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

  12. 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

  13. 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

  14. 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.

  15. Influence of Leaf Starch Concentration on CO2 Assimilation in Soybean 1

    PubMed Central

    Nafziger, Emerson D.; Koller, H. Ronald

    1976-01-01

    Net photosynthetic rate, CO2 compensation concentration, and starch and soluble sugar concentrations were measured in soybean (Glycine max [L.] Merrill) leaves in an attempt to evaluate the effect of carbohydrate concentration on rate of CO2 assimilation. Plants were grown in a controlled environment room at 23.5 C, 50% relative humidity, 16-hour photoperiod, and quantum flux (400-700 nm) of 510 μeinsteins/m2·sec (30,090 lux) at plant level. On the 21st day after seeding, plants were subjected for 12.5 hours to one of three CO2 concentrations (50, 300, or 2000 μl/l) in an attempt to alter leaf carbohydrate levels. Following the CO2 treatment, gas exchange measurements were made at a CO2 concentration of 300 μl/l on the lowermost trifoliolate leaf. Immediately after measurement, the leaf was removed and stored at −20 C until carbohydrate analyses were performed. Increasing the CO2 concentration for 12.5 hours significantly increased leaf starch concentration but not soluble sugar concentration. There was a strong negative correlation between net photosynthetic rate and starch concentration. Net photosynthetic rate declined from approximately 38 to 22 mg CO2/dm2 leaf area·hr as starch concentration increased from 0.5 to 3 mg/cm2 leaf area. Carbohydrate concentrations had no effect on compensation concentration. The decrease in net photosynthetic rate as starch concentration increased resulted from an increase in mesophyll (liquid phase) CO2 diffusion resistance. This suggests that starch accumulation may reduce net photosynthetic rate by impeding intracellular CO2 transport. PMID:16659526

  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.

  17. 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

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

    NASA Astrophysics Data System (ADS)

    Seshadri, Ashwin K.

    2016-11-01

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

  19. Increased CO2 stimulates reproduction in a coral reef fish.

    PubMed

    Miller, Gabrielle M; Watson, Sue-Ann; McCormick, Mark I; Munday, Philip L

    2013-10-01

    Ocean acidification is predicted to negatively impact the reproduction of many marine species, either by reducing fertilization success or diverting energy from reproductive effort. While recent studies have demonstrated how ocean acidification will affect larval and juvenile fishes, little is known about how increasing partial pressure of carbon dioxide (pCO(2)) and decreasing pH might affect reproduction in adult fishes. We investigated the effects of near-future levels of pCO(2) on the reproductive performance of the cinnamon anemonefish, Amphiprion melanopus, from the Great Barrier Reef, Australia. Breeding pairs were held under three CO(2) treatments [Current-day Control (430 μatm), Moderate (584 μatm) and High (1032 μatm)] for a 9-month period that included the summer breeding season. Unexpectedly, increased CO(2) dramatically stimulated breeding activity in this species of fish. Over twice as many pairs bred in the Moderate (67% of pairs) and High (55%) compared to the Control (27%) CO(2) treatment. Pairs in the High CO(2) group produced double the number of clutches per pair and 67% more eggs per clutch compared to the Moderate and Control groups. As a result, reproductive output in the High group was 82% higher than that in the Control group and 50% higher than that in the Moderate group. Despite the increase in reproductive activity, there was no difference in adult body condition among the three treatment groups. There was no significant difference in hatchling length between the treatment groups, but larvae from the High CO(2) group had smaller yolks than Controls. This study provides the first evidence of the potential effects of ocean acidification on key reproductive attributes of marine fishes and, contrary to expectations, demonstrates an initially stimulatory (hormetic) effect in response to increased pCO(2). However, any long-term consequences of increased reproductive effort on individuals or populations remain to be determined. © 2013 John

  20. Future CO2 concentrations, though not warmer temperatures, enhance wheat photosynthesis temperature responses.

    PubMed

    Alonso, Aitor; Pérez, Pilar; Morcuende, Rosa; Martinez-Carrasco, Rafael

    2008-01-01

    The temperature dependence of C3 photosynthesis is known to vary according to the growth environment. Atmospheric CO2 concentration and temperature are predicted to increase with climate change. To test whether long-term growth in elevated CO2 and temperature modifies photosynthesis temperature response, wheat (Triticum aestivum L.) was grown in ambient CO2 (370 micromol mol(-1)) and elevated CO2 (700 micromol mol(-1)) combined with ambient temperatures and 4 degrees C warmer ones, using temperature gradient chambers in the field. Flag leaf photosynthesis was measured at temperatures ranging from 20 to 35 degrees C and varying CO2 concentrations between ear emergence and anthesis. The maximum rate of carboxylation was determined in vitro in the first year of the experiment and from the photosynthesis-intercellular CO2 response in the second year. With measurement CO2 concentrations of 330 micromol mol(-1) or lower, growth temperature had no effect on flag leaf photosynthesis in plants grown in ambient CO2, while it increased photosynthesis in elevated growth CO2. However, warmer growth temperatures did not modify the response of photosynthesis to measurement temperatures from 20 to 35 degrees C. A central finding of this study was that the increase with temperature in photosynthesis and the photosynthesis temperature optimum were significantly higher in plants grown in elevated rather than ambient CO2. In association with this, growth in elevated CO2 increased the temperature response (activation energy) of the maximum rate of carboxylation. The results provide field evidence that growth under CO2 enrichment enhances the response of Rubisco activity to temperature in wheat.

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

    USDA-ARS?s Scientific Manuscript database

    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...

  2. 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.

  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.

  4. Dynamics of soil CO 2 efflux under varying atmospheric CO 2 concentrations reveal dominance of slow processes

    Treesearch

    Dohyoung Kim; Ram Oren; James S. Clark; Sari Palmroth; A. Christopher Oishi; Heather R. McCarthy; Chris A. Maier; Kurt Johnsen

    2017-01-01

    We evaluated the effect on soil CO2 efflux (FCO2) of sudden changes in photosynthetic rates by altering CO2 concentration in plots subjected to +200 ppmv for 15 years. Five-day intervals of exposure to elevated CO2 (eCO2) ranging 1.0–1.8 times ambient did not affect FCO2. FCO2 did not decrease until 4 months after termination of the long-term eCO2 treatment, longer...

  5. [Effects of elevated atmospheric CO2 concentration on mung bean leaf photosynthesis and chlorophyll fluorescence parameters].

    PubMed

    Hao, Xing-yu; Han, Xue; Li, Ping; Yang, Hong-bin; Lin, Er-da

    2011-10-01

    By using free air CO2 enrichment (FACE) system, a pot experiment under field condition was conducted to study the effects of elevated CO2 concentration (550 +/- 60 micromol mol(-1)) on the leaf photosynthesis and chlorophyll fluorescence parameters of mung bean. Comparing with the control (CO2 concentration averagely 389 +/- 40 micromol mol(-1)), elevated CO2 concentration increased the leaf intercellular CO2 concentration (Ci) and net photosynthesis rate (P(n)) at flowering and pod growth stage by 9.8% and 11.7%, decreased the stomatic conductance (G(s)) and transpiration rate (T(r)) by 32.0% and 24.6%, respectively, and increased the water use efficiency (WUE) by 83.5%. Elevated CO2 concentration had lesser effects on the minimal fluorescence (F0), maximal fluorescence (F(m)), variable fluorescence (F(v)), ratio of variable fluorescence to minimal fluorescence (F(v)/F0), and ratio of variable fluorescence to maximal fluorescence (F(v)/F(m)) at bud stage, but increased the F0 at pod filling stage by 19.1% and decreased the Fm, F(v), F(v)/F0, and F(v)/F(m) by 9.0%, 14.3%, 25.8% , and 6.2%, respectively. These results suggested that elevated CO2 concentration could damage the structure of leaf photosystem II and consequently decrease the leaf photosynthetic capacity in the late growth phase of mung bean.

  6. One-man, self-contained CO2 concentrating system

    NASA Technical Reports Server (NTRS)

    Wynveen, R. A.; Schubert, F. H.; Powell, J. D.

    1972-01-01

    A program to design, fabricate, and test a 1-man, self-contained, electrochemical CO2 concentrating system is described. The system was designed with electronic controls and instrumentation to regulate performance, to analyze and display performance trends, and to detect and isolate faults. Ground support accessories were included to provide power, fluids, and a Parametric Data Display allowing real time indication of operating status in engineering units.

  7. Leaf functional response to increasing atmospheric CO(2) concentrations over the last century in two northern Amazonian tree species: a historical δ(13) C and δ(18) O approach using herbarium samples.

    PubMed

    Bonal, Damien; Ponton, Stéphane; Le Thiec, Didier; Richard, Béatrice; Ningre, Nathalie; Hérault, Bruno; Ogée, Jérôme; Gonzalez, Sophie; Pignal, Marc; Sabatier, Daniel; Guehl, Jean-Marc

    2011-08-01

    We assessed the extent of recent environmental changes on leaf morphological (stomatal density, stomatal surface, leaf mass per unit area) and physiological traits (carbon isotope composition, δ(13)C(leaf) , and discrimination, Δ(13)C(leaf) , oxygen isotope composition, δ(18)O(leaf) ) of two tropical rainforest species (Dicorynia guianensis; Humiria balsamifera) that are abundant in the Guiana shield (Northern Amazonia). Leaf samples were collected in different international herbariums to cover a 200 year time-period (1790-2004) and the whole Guiana shield. Using models describing carbon and oxygen isotope fractionations during photosynthesis, different scenarios of change in intercellular CO(2) concentrations inside the leaf (C(i)), stomatal conductance (g), and photosynthesis (A) were tested in order to understand leaf physiological response to increasing air CO(2) concentrations (C(a)). Our results confirmed that both species displayed physiological response to changing C(a) . For both species, we observed a decrease of about 1.7‰ in δ(13)C(leaf) since 1950, without significant change in Δ(13)C(leaf) and leaf morphological traits. Furthermore, there was no clear change in δ(18)O(leaf) for Humiria over this period. Our simulation approach revealed that an increase in A, rather than a decrease in g, explained the observed trends for these tropical rainforest species, allowing them to maintain a constant ratio of C(i)/C(a) .

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  9. The hysteresis response of soil respiration and soil CO2 concentration to soil temperature

    NASA Astrophysics Data System (ADS)

    Zhang, Q., Sr.; Katul, G. G.; Oren, R.; Daly, E.; Manzoni, S.; Yang, D.

    2015-12-01

    Diurnal hysteresis between soil temperature (Ts) and both CO2 concentration ([CO2]) and soil respiration rate (Rs) were reported across different field experiments. However, the causes of these hysteresis patterns remain a subject of debate, with biotic and abiotic factors both invoked as explanations. To address these issues, a CO2 gas transport model is developed by combining layer-wise mass conservation for subsurface gas-phase CO2, Fickian diffusion for gas transfer, and a CO2 source term that depends on soil temperature, moisture, and photosynthetic rate. Using this model, a hierarchy of numerical experiments were employed to disentangle the causes of the hysteretic [CO2]-Ts and CO2 flux-Ts (i.e., F -Ts) relations. Model results show that gas transport alone can introduce both [CO2]-Ts and F-Ts hysteresis, and also confirm prior findings that heat flow in soils lead to [CO2] and F(z) being out of phase with Ts, thereby providing another reason for the occurrence of both hysteresis. The area (Ahys) of the [CO2]-Ts hysteresis near the surface increases, while the Ahys of the Rs-Ts hysteresis decreases as soils become wetter. Moreover, a time-lagged carbon input from photosynthesis deformed the [CO2]-Ts and Rs-Ts patterns, causing a change in the loop direction from counterclockwise to clockwise with decreasing time lag. An asymmetric 8-shaped pattern emerged as the transition state between the two loop directions. Tracing the pattern and direction of the hysteretic [CO2]-Ts and Rs-Ts relations can provide new ways to fingerprint the effects of photosynthesis stimulation on soil microbial activity and detect the corresponding time lags. Key words: Hysteresis; Photosynthesis; Soil CO2 concentration; Soil respiration; Soil temperature; Soil moisture

  10. Phenotypic Plasticity Conditions the Response of Soybean Seed Yield to Elevated Atmospheric CO2 Concentration1

    PubMed Central

    Kumagai, Etsushi; Aoki, Naohiro; Masuya, Yusuke; Shimono, Hiroyuki

    2015-01-01

    Selection for cultivars with superior responsiveness to elevated atmospheric CO2 concentrations (eCO2) is a powerful option for boosting crop productivity under future eCO2. However, neither criteria for eCO2 responsiveness nor prescreening methods have been established. The purpose of this study was to identify traits responsible for eCO2 responsiveness of soybean (Glycine max). We grew 12 Japanese and U.S. soybean cultivars that differed in their maturity group and determinacy under ambient CO2 and eCO2 for 2 years in temperature gradient chambers. CO2 elevation significantly increased seed yield per plant, and the magnitude varied widely among the cultivars (from 0% to 62%). The yield increase was best explained by increased aboveground biomass and pod number per plant. These results suggest that the plasticity of pod production under eCO2 results from biomass enhancement, and would therefore be a key factor in the yield response to eCO2, a resource-rich environment. To test this hypothesis, we grew the same cultivars at low planting density, a resource-rich environment that improved the light and nutrient supplies by minimizing competition. Low planting density significantly increased seed yield per plant, and the magnitude ranged from 5% to 105% among the cultivars owing to increased biomass and pod number per plant. The yield increase due to low-density planting was significantly positively correlated with the eCO2 response in both years. These results confirm our hypothesis and suggest that high plasticity of biomass and pod production at a low planting density reveals suitable parameters for breeding to maximize soybean yield under eCO2. PMID:26373658

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

    PubMed

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

    2015-01-01

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

  12. How much has the increase in atmospheric CO2 directly affected past soybean production?

    PubMed

    Sakurai, Gen; Iizumi, Toshichika; Nishimori, Motoki; Yokozawa, Masayuki

    2014-05-15

    Understanding the effects of climate change is vital for food security. Among the most important environmental impacts of climate change is the direct effect of increased atmospheric carbon dioxide concentration ([CO2]) on crop yields, known as the CO2 fertilization effect. Although several statistical studies have estimated past impacts of temperature and precipitation on crop yield at regional scales, the impact of past CO2 fertilization is not well known. We evaluated how soybean yields have been enhanced by historical atmospheric [CO2] increases in three major soybean-producing countries. The estimated average yields during 2002-2006 in the USA, Brazil, and China were 4.34%, 7.57%, and 5.10% larger, respectively, than the average yields estimated using the atmospheric [CO2] of 1980. Our results demonstrate the importance of considering atmospheric [CO2] increases in evaluations of the past effects of climate change on crop yields.

  13. Direct effects of CO2 concentration on growth and isotopic composition of marine plankton

    NASA Astrophysics Data System (ADS)

    Wolf-Gladrow, Dieter A.; Riebesell, Ulf; Burkhardt, Steffen; Bijma, Jelle

    1999-04-01

    The assessment of direct effects of anthropogenic CO2 increase on the marine biota has received relatively little attention compared to the intense research on CO2-related responses of the terrestrial biosphere. Yet, due to the rapid air sea gas exchange, the observed past and predicted future rise in atmospheric CO2 causes a corresponding increase in seawater CO2 concentrations, [CO2], in upper ocean waters. Increasing [CO2] leads to considerable changes in the surface ocean carbonate system, resulting in decreases in pH and the carbonate concentration, [CO2-3]. These changes can be shown to have strong impacts on the marine biota. Here we will distinguish between CO2-related responses of the marine biota which (a) potentially affect the ocean's biological carbon pumps and (b) are relevant to the interpretation of diagnostic tools (proxies) used to assess climate change on geological times scales. With regard to the former, three direct effects of increasing [CO2] on marine plankton have been recognized: enhanced phytoplankton growth rate, changing elemental composition of primary produced organic matter, and reduced biogenic calcification. Although quantitative estimates of their impacts on the oceanic carbon cycle are not yet feasible, all three effects increase the ocean's capacity to take up and store atmospheric CO2 and hence, can serve as negative feedbacks to anthropogenic CO2 increase. With respect to proxies used in palaeo-reconstructions, CO2-sensitivity is found in carbon isotope fractionation by phytoplankton and foraminifera. While CO2- dependent isotope fractionation by phytoplankton may be of potential use in reconstructing surface ocean pCO2 at ancient times, CO2-related effects on the isotopic composition of foraminiferal shells confounds the use of the difference in isotopic signals between planktonic and benthic shells as a measure for the strength of

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

    PubMed

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

    2017-07-18

    When reactive fluids flow through a dissolving porous medium, conductive channels form, leading to fluid breakthrough. This phenomenon is caused by the reactive infiltration instability and is important in geologic carbon storage where the dissolution of CO2 in flowing water increases fluid acidity. Using numerical simulations with high resolution digital models of North Sea chalk, we show that the breakthrough porosity is an important indicator of dissolution pattern. Dissolution patterns reflect the balance between the demand and supply of cumulative surface. The demand is determined by the reactive fluid composition while the supply relies on the flow field and the rock's microstructure. We tested three model scenarios and found that aqueous CO2 dissolves porous media homogeneously, leading to large breakthrough porosity. In contrast, solutions without CO2 develop elongated convective channels known as wormholes, with low breakthrough porosity. These different patterns are explained by the different apparent solubility of calcite in free drift systems. Our results indicate that CO2 increases the reactive subvolume of porous media and reduces the amount of solid residual before reactive fluid can be fully channelized. Consequently, dissolved CO2 may enhance contaminant mobilization near injection wellbores, undermine the mechanical sustainability of formation rocks and increase the likelihood of buoyance driven leakage through carbonate rich caprocks.

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

    PubMed

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

    2013-10-01

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

  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. 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).

  18. Improved Criteria for Increasing CO2 Storage Potential with CO2 Enhanced Oil Recovery

    NASA Astrophysics Data System (ADS)

    Bauman, J.; Pawar, R.

    2013-12-01

    In recent years it has been found that deployment of CO2 capture and storage technology at large scales will be difficult without significant incentives. One of the technologies that has been a focus in recent years is CO2 enhanced oil/gas recovery, where additional hydrocarbon recovery provides an economic incentive for deployment. The way CO2 EOR is currently deployed, maximization of additional oil production does not necessarily lead to maximization of stored CO2, though significant amounts of CO2 are stored regardless of the objective. To determine the potential of large-scale CO2 storage through CO2 EOR, it is necessary to determine the feasibility of deploying this technology over a wide range of oil/gas field characteristics. In addition it is also necessary to accurately estimate the ultimate CO2 storage potential and develop approaches that optimize oil recovery along with long-term CO2 storage. This study uses compositional reservoir simulations to further develop technical screening criteria that not only improve oil recovery, but maximize CO2 storage during enhanced oil recovery operations. Minimum miscibility pressure, maximum oil/ CO2 contact without the need of significant waterflooding, and CO2 breakthrough prevention are a few key parameters specific to the technical aspects of CO2 enhanced oil recovery that maximize CO2 storage. We have developed reduced order models based on simulation results to determine the ultimate oil recovery and CO2 storage potential in these formations. Our goal is to develop and demonstrate a methodology that can be used to determine feasibility and long-term CO2 storage potential of CO2 EOR technology.

  19. Coccolithophore Response to CO2 Increase and Related Ecological Changes

    NASA Astrophysics Data System (ADS)

    Ziveri, P.

    2007-12-01

    Changes in ocean chemistry due to anthropogenic CO2 emissions affect marine life, nutrient cycles and biocalcification. Ocean acidification has been identified as a major consequence of rising atmospheric CO2 levels. This makes understanding the response of calcareous plankton, and other effects of global change, an urgent challenge. There have been controversial results from culture experiments and field observations, on the impact of CO2 increase on coccolithophore calcification and ecology. The objective of this presentation is to report the state-of-the-art on the impact of ocean acidification on coccolithophores and possible consequences on their biogeography and ecology. Results will also be reported from a workshop sponsored by the European Science Foundation (Euroclimate Program) and PAGES on Atmopheric CO2, ocean acidification and ecological changes in planktonic calcifying organisms. A wide range of experts contributed to that workshop, from the cellular and genetic to the ecological and global carbon cycle levels. Questions include how the predicted CO2 increase and acidification is likely to affect coccolithophores, what the possible secondary consequences may be, and what research is needed to allow robust predictions for the future.

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

    PubMed

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

    2011-07-13

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

  1. Increases in atmospheric CO2 have little influence on transpiration of a temperate forest canopy.

    PubMed

    Tor-ngern, Pantana; Oren, Ram; Ward, Eric J; Palmroth, Sari; McCarthy, Heather R; Domec, Jean-Christophe

    2015-01-01

    Models of forest energy, water and carbon cycles assume decreased stomatal conductance with elevated atmospheric CO2 concentration ([CO2]) based on leaf-scale measurements, a response not directly translatable to canopies. Where canopy-atmosphere are well-coupled, [CO2 ]-induced structural changes, such as increasing leaf-area index (LD), may cause, or compensate for, reduced mean canopy stomatal conductance (GS), keeping transpiration (EC) and, hence, runoff unaltered. We investigated GS responses to increasing [CO2] of conifer and broadleaved trees in a temperate forest subjected to 17-yr free-air CO2 enrichment (FACE; + 200 μmol mol(-1)). During the final phase of the experiment, we employed step changes of [CO2] in four elevated-[CO2 ] plots, separating direct response to changing [CO2] in the leaf-internal air-space from indirect effects of slow changes via leaf hydraulic adjustments and canopy development. Short-term manipulations caused no direct response up to 1.8 × ambient [CO2], suggesting that the observed long-term 21% reduction of GS was an indirect effect of decreased leaf hydraulic conductance and increased leaf shading. Thus, EC was unaffected by [CO2] because 19% higher canopy LD nullified the effect of leaf hydraulic acclimation on GS . We advocate long-term experiments of duration sufficient for slow responses to manifest, and modifying models predicting forest water, energy and carbon cycles accordingly.

  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).

  3. Food for thought: lower-than-expected crop yield stimulation with rising CO2 concentrations.

    PubMed

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

    2006-06-30

    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 approximately 50% less than in enclosure studies. This casts serious doubt on projections that rising [CO2] will fully offset losses due to climate change.

  4. 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

  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.

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

    PubMed

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

    2015-01-01

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

  7. Photosynthetic response to globally increasing CO2 of co-occurring temperate seagrass species.

    PubMed

    Borum, Jens; Pedersen, Ole; Kotula, Lukasz; Fraser, Matthew W; Statton, John; Colmer, Timothy D; Kendrick, Gary A

    2016-06-01

    Photosynthesis of most seagrass species seems to be limited by present concentrations of dissolved inorganic carbon (DIC). Therefore, the ongoing increase in atmospheric CO2 could enhance seagrass photosynthesis and internal O2 supply, and potentially change species competition through differential responses to increasing CO2 availability among species. We used short-term photosynthetic responses of nine seagrass species from the south-west of Australia to test species-specific responses to enhanced CO2 and changes in HCO3 (-) . Net photosynthesis of all species except Zostera polychlamys were limited at pre-industrial compared to saturating CO2 levels at light saturation, suggesting that enhanced CO2 availability will enhance seagrass performance. Seven out of the nine species were efficient HCO3 (-) users through acidification of diffusive boundary layers, production of extracellular carbonic anhydrase, or uptake and internal conversion of HCO3 (-) . Species responded differently to near saturating CO2 implying that increasing atmospheric CO2 may change competition among seagrass species if co-occurring in mixed beds. Increasing CO2 availability also enhanced internal aeration in the one species assessed. We expect that future increases in atmospheric CO2 will have the strongest impact on seagrass recruits and sparsely vegetated beds, because densely vegetated seagrass beds are most often limited by light and not by inorganic carbon. © 2015 John Wiley & Sons Ltd.

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

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

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

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

    PubMed

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

    2013-07-01

    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. 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. 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. 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.

  10. 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

  11. 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. © 2013 Scandinavian Plant Physiology Society.

  12. Evidence that higher CO2 increases tree growth sensitivity to ...

    EPA Pesticide Factsheets

    Aim: To test the growth-sensitivity to temperature under different ambient CO2 concentrations, we determined paleo tree growth rates as they relate to variation in temperature during the last deglacial period, and compare these to modern tree growth rates as they relate to spatial variation in temperature across the modern species distributional range. During the deglacial period, [CO2] averaged about 230 ppm, whereas modern [CO2] averaged about 330 ppm.Location: Paleo oaks were sampled from Northern Missouri, USA. The paleo temperature reconstruction was from a lake in Northern Illinois, USA. Data used to quantify the growth-sensitivity to temperature for modern oaks were collected across the Great Plains, Midwest and Upper Great Lakes regions.Methods: Growth data were from 53 paleo bur oak log cross-sections collected in Missouri that were preserved in river and stream sediments. These oaks were radiocarbon-dated to between 10.5 and 13.3 cal kyr BP, which spans rapid warming during the last deglaciation. Growth data from modern bur oaks were obtained from increment core collections paired with USDA Forest Service Forest Inventory and Analysis data. Paleotemperatures were obtained from a high-resolution pollen-based reconstruction and modern temperatures were obtained from gridded meteorological data. Results: Growth-sensitivity to temperature (i.e. the slope of growth rate versus temperature) was significantly greater for modern oaks growing at an average [CO2

  13. Monoterpene and herbivore-induced emissions from cabbage plants grown at elevated atmospheric CO 2 concentration

    NASA Astrophysics Data System (ADS)

    Vuorinen, Terhi; Reddy, G. V. P.; Nerg, Anne-Marja; Holopainen, Jarmo K.

    The warming of the lower atmosphere due to elevating CO 2 concentration may increase volatile organic compound (VOC) emissions from plants. Also, direct effects of elevated CO 2 on plant secondary metabolism are expected to lead to increased VOC emissions due to allocation of excess carbon on secondary metabolites, of which many are volatile. We investigated how growing at doubled ambient CO 2 concentration affects emissions from cabbage plants ( Brassica oleracea subsp. capitata) damaged by either the leaf-chewing larvae of crucifer specialist diamondback moth ( Plutella xylostella L.) or generalist Egyptian cotton leafworm ( Spodoptera littoralis (Boisduval)). The emission from cabbage cv. Lennox grown in both CO 2 concentrations, consisted mainly of monoterpenes (sabinene, limonene, α-thujene, 1,8-cineole, β-pinene, myrcene, α-pinene and γ-terpinene). ( Z)-3-Hexenyl acetate, sesquiterpene ( E, E)- α-farnesene and homoterpene ( E)-4,8-dimethyl-1,3,7-nonatriene (DMNT) were emitted mainly from herbivore-damaged plants. Plants grown at 720 μmol mol -1 of CO 2 had significantly lower total monoterpene emissions per shoot dry weight than plants grown at 360 μmol mol -1 of CO 2, while damage by both herbivores significantly increased the total monoterpene emissions compared to intact plants. ( Z)-3-Hexenyl acetate, ( E, E)- α-farnesene and DMNT emissions per shoot dry weight were not affected by the growth at elevated CO 2. The emission of DMNT was significantly enhanced from plants damaged by the specialist P. xylostella compared to the plants damaged by the generalist S. littoralis. The relative proportions of total monoterpenes and total herbivore-induced compounds of total VOCs did not change due to the growth at elevated CO 2, while insect damage increased significantly the proportion of induced compounds. The results suggest that VOC emissions that are induced by the leaf-chewing herbivores will not be influenced by elevated CO 2 concentration.

  14. 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. © 2014 Institute of Botany, Chinese Academy of Sciences.

  15. 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

  16. Responses of legume versus nonlegume tropical tree seedlings to elevated CO2 concentration.

    PubMed

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

    2011-09-01

    We investigated responses of growth, leaf gas exchange, carbon-isotope discrimination, and whole-plant water-use efficiency (W(P)) to elevated CO(2) concentration ([CO(2)]) in seedlings of five leguminous and five nonleguminous tropical tree species. Plants were grown at CO(2) partial pressures of 40 and 70 Pa. As a group, legumes did not differ from nonlegumes in growth response to elevated [CO(2)]. The mean ratio of final plant dry mass at elevated to ambient [CO(2)] (M(E)/M(A)) was 1.32 and 1.24 for legumes and nonlegumes, respectively. However, there was large variation in M(E)/M(A) among legume species (0.92-2.35), whereas nonlegumes varied much less (1.21-1.29). Variation among legume species in M(E)/M(A) 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. W(P) increased markedly in response to elevated [CO(2)] in all species. The ratio of intercellular to ambient CO(2) partial pressures during photosynthesis remained approximately constant at ambient and elevated [CO(2)], as did carbon isotope discrimination, suggesting that W(P) should increase proportionally for a given increase in atmospheric [CO(2)]. These results suggest that tree legumes with a strong capacity for nodule formation could have a competitive advantage in tropical forests as atmospheric [CO(2)] rises and that the water-use efficiency of tropical tree species will increase under elevated [CO(2)].

  17. Increased N2O emission by inhibited plant growth in the CO2 leaked soil environment: Simulation of CO2 leakage from carbon capture and storage (CCS) site.

    PubMed

    Kim, You Jin; He, Wenmei; Ko, Daegeun; Chung, Haegeun; Yoo, Gayoung

    2017-12-31

    Atmospheric carbon dioxide (CO2) concentrations is continuing to increase due to anthropogenic activity, and geological CO2 storage via carbon capture and storage (CCS) technology can be an effective way to mitigate global warming due to CO2 emission. However, the possibility of CO2 leakage from reservoirs and pipelines exists, and such leakage could negatively affect organisms in the soil environment. Therefore, to determine the impacts of geological CO2 leakage on plant and soil processes, we conducted a greenhouse study in which plants and soils were exposed to high levels of soil CO2. Cabbage, which has been reported to be vulnerable to high soil CO2, was grown under BI (no injection), NI (99.99% N2 injection), and CI (99.99% CO2 injection). Mean soil CO2 concentration for CI was 66.8-76.9% and the mean O2 concentrations in NI and CI were 6.6-12.7%, which could be observed in the CO2 leaked soil from the pipelines connected to the CCS sites. The soil N2O emission was increased by 286% in the CI, where NO3(-)-N concentration was 160% higher compared to that in the control. This indicates that higher N2O emission from CO2 leakage could be due to enhanced nitrification process. Higher NO3(-)-N content in soil was related to inhibited plant metabolism. In the CI treatment, chlorophyll content decreased and chlorosis appeared after 8th day of injection. Due to the inhibited root growth, leaf water and nitrogen contents were consistently lowered by 15% under CI treatment. Our results imply that N2O emission could be increased by the secondary effects of CO2 leakage on plant metabolism. Hence, monitoring the environmental changes in rhizosphere would be very useful for impact assessment of CCS technology. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. The hysteresis response of soil CO2 concentration and soil respiration to soil temperature

    NASA Astrophysics Data System (ADS)

    Zhang, Quan; Katul, Gabriel G.; Oren, Ram; Daly, Edoardo; Manzoni, Stefano; Yang, Dawen

    2015-08-01

    Diurnal hysteresis between soil temperature (Ts) and both CO2 concentration ([CO2]) and soil respiration rate (Rs) were reported across different field experiments. However, the causes of these hysteresis patterns remain a subject of debate, with biotic and abiotic factors both invoked as explanations. To address these issues, a CO2 gas transport model is developed by combining a layer-wise mass conservation equation for subsurface gas phase CO2, Fickian diffusion for gas transfer, and a CO2 source term that depends on soil temperature, moisture, and photosynthetic rate. Using this model, a hierarchy of numerical experiments were employed to disentangle the causes of the hysteretic [CO2]-Ts and CO2 flux Ts (i.e., F-Ts) relations. Model results show that gas transport alone can introduce both [CO2]-Ts and F-Ts hystereses and also confirm prior findings that heat flow in soils lead to [CO2] and F being out of phase with Ts, thereby providing another reason for the occurrence of both hystereses. The area (Ahys) of the [CO2]-Ts hysteresis near the surface increases, while the Ahys of the Rs-Ts hysteresis decreases as soils become wetter. Moreover, a time-lagged carbon input from photosynthesis deformed the [CO2]-Ts and Rs-Ts patterns, causing a change in the loop direction from counterclockwise to clockwise with decreasing time lag. An asymmetric 8-shaped pattern emerged as the transition state between the two loop directions. Tracing the pattern and direction of the hysteretic [CO2]-Ts and Rs-Ts relations can provide new ways to fingerprint the effects of photosynthesis stimulation on soil microbial activity and detect time lags between rhizospheric respiration and photosynthesis.

  19. Low temperature reduces the energetic requirement for the CO2 concentrating mechanism in diatoms.

    PubMed

    Kranz, Sven A; Young, Jodi N; Hopkinson, Brian M; Goldman, Johanna A L; Tortell, Philippe D; Morel, François M M

    2015-01-01

    The goal of this study is to investigate the CO2 concentrating mechanism (CCM) of the dominant phytoplankton species during the growing season at Palmer station in the Western Antarctic Peninsula. Key CCM parameters (cellular half-saturation constants for CO2 fixation, carbonic anhydrase activity, CO2 /HCO3 (-) uptake, δ(13) Corg ) in natural phytoplankton assemblages were determined. Those results, together with additional measurements on CO2 membrane permeability from Fragilariopsis cylindrus laboratory cultures, were used to develop a numerical model of the CCM of cold water diatoms. The field data demonstrate that the dominant species throughout the season possess an effective CCM, which achieves near saturation of CO2 for fixation. The model provides a means to examine the role of eCA activity and HCO3 (-) /CO2 uptake in the functioning of the CCM. According to the model, the increase in δ(13) Corg during the bloom results chiefly from decreasing ambient CO2 concentration (which reduces the gross diffusive flux across the membrane) rather than a shift in inorganic carbon uptake from CO2 to HCO3 (-) . The CCM of diatoms in the Western Antarctic Peninsula functions with a relatively small expenditure of energy, resulting chiefly from the low half-saturation constant for Rubisco at cold temperatures. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

  20. Soil CO2 and O2 concentrations in shale and sandstone catchments of central Pennsylvania.

    NASA Astrophysics Data System (ADS)

    Hill, L. Z.; Kaye, J. P.; Brantley, S.

    2016-12-01

    In order to increase understanding of parent material controls on biogeochemical processes, we monitored the depth distribution of soil CO2 and O2 concentrations in central Pennsylvania in two watersheds on different lithologies. We deployed gas monitoring instrumentation on two catena transects, one located on sandstone and the other on shale. As expected, with increasing soil depth, O2 concentrations decreased while pCO2 increased. Over the year of monitoring, CO2 concentrations varied between the shale and sandstone locations. When soils were consistently wet (e.g. September and October 2015) pCO2 at 25 cm below the soil surface was 2 to 3 times greater on the sandstone ridgetop and north-facing mid-slope than its shale counter-parts. During the rest of the growing season, CO2 and O2 concentrations varied more by topographical position than with lithology, as the valley floor positions in both catenas had the highest pCO2 for a given depth. Both infrequent manual sampling from many gas access tubes and continuous sampling by a limited number of buried sensors documented these patterns. Because these sites are in close proximity with similar temperature and precipitation, we hypothesize that elevated pCO2 in the surface of sandstone-derived soils (relative to shale) is a result of a thicker organic horizon and differences in the associated heterotrophic respiration. At depth, the higher pCO2 at the sandstone site may be due to a combination of carbon availability and constraints of diffusion. Adjacent forests underlain by shale and sandstone parent materials are prevalent throughout the Appalachian Mountains and if our sites are representative of this region, processes related to soil CO2 and O2, including weathering rates, nutrient cycling, microbial productivity, root growth, and soil respiration may differ markedly in these adjacent forests.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  2. 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).

  3. Increase of photosynthesis and starch in potato under elevated CO2 is dependent on leaf age.

    PubMed

    Katny, María Angélica Casanova; Hoffmann-Thoma, Gudrun; Schrier, Anton Arij; Fangmeier, Andreas; Jäger, Hans-Jürgen; van Bel, Aart J E

    2005-04-01

    Potato plants (Solanum tuberosum cv. Bintje) were grown in open top chambers under ambient (400 microL L(-1)) and elevated CO2 (720 microL L(-1)). After 50 days one half of each group was transferred to the other CO2 concentration and the effects were studied in relation to leaf age (old, middle-aged and young leaves) in each of the four groups. Under long-term exposure to elevated CO2, photosynthesis increased between 10% and 40% compared to ambient CO2. A subsequent shift of the same plants to ambient CO2 caused a 20-40% decline in photosynthetic rate, which was most pronounced in young leaves. After shifting from long-term ambient to elevated CO2, photosynthesis also increased most strongly in young leaves (90%); these experiments show that photosynthesis was downregulated in the upper young fully expanded leaves of potato growing long-term under elevated CO2. Soluble sugar content in all leaf classes under long-term exposure was stable irrespective of the CO2 treatment, however under elevated CO2 young leaves showed a strongly increased starch accumulation (up to 400%). In all leaf classes starch levels dropped in response to the shift from 720 to 400 microL L(-1) approaching ambient CO2 levels. After the shift to 720 microL L(-1), sucrose and starch levels increased, principally in young Leaves. There is clear evidence that leaves of different age vary in their responses to changes in atmospheric CO2 concentration.

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

    USDA-ARS?s Scientific Manuscript database

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

  5. 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

  6. 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

  7. Changes in CO2 concentration and carbon cycle during the last glacial termination

    NASA Astrophysics Data System (ADS)

    Ahn, J.; Lee, H. G.; Shin, J.; Brook, E.

    2015-12-01

    Ice cores from Antarctica have revealed that atmospheric CO2 concentration is strongly linked with climate over the past hundreds of thousands years. During the last glacial termination CO2 concentration increased by ~80 ppm and the increase rate changed with abrupt climate events such as Bølling-Allerød and Younger Dryas. Precise and high-resolution CO2 records during the events may help us better understand climate-carbon cycle feedbacks. However, most of the existing ice core records are severely smoothed by gradual bubble close-off and gas diffusion in the firn layer. Recently, a CO2 record with an unprecedented temporal resolution was obtained from West Antarctic Ice Sheet (WAIS) Divide ice core, where glaciological conditions permit a relatively small gas smoothing effect. The WAIS Divide record shows three abrupt CO2 increases of 10-15 ppm in less than 200 years during the last glacial termination. The ancient air extracted from the WAIS Divide ice core was in a form of air hydrates and the results must yet be confirmed with other ice cores. Here we present a new high-resolution atmospheric CO2 record from the Siple Dome ice core, in which air is preserved only in bubbles. Our data cover 11.0-21.0 ka with an average time resolution of 65 yrs. The Siple Dome records show that abrupt CO2 increases of ~ 10 ppm within 100-200 years at 11.7, 14.7, and 16.3 ka, confirming the rapid CO2 increases observed in the WAIS Divide record. We are analyzing the common and uncommon features during the three rapid CO2 increases in order to decipher the control mechanisms. The updated results will be presented at the meeting.

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

    PubMed

    Santos, Bruna Marques Dos; Balbuena, Tiago Santana

    2017-01-06

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

  9. Stronger influences of increased CO2 on subdaily precipitation extremes than at the daily scale

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Villarini, Gabriele; Scoccimarro, Enrico; Vecchi, Gabriel A.

    2017-07-01

    Based on idealized experiments (preindustrial control experiment (PI) and 1% yr-1 increase (1%CO2) in atmospheric CO2) from 10 general circulation models produced under the Coupled Model Intercomparison Project Phase 5 and using the fraction of attributable risk, we examine the CO2 effects on extreme precipitation at the subdaily and daily scales. We find that the increased CO2 concentration substantially increases the odds of the occurrence of subdaily precipitation extremes compared to the daily scale in most areas of the world, with the exception of some regions in the subtropics, likely in relation to the subsidence of the Hadley Cell. These results point to the large role that atmospheric CO2 plays in extreme precipitation under an idealized framework.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  11. Designing an oscillating CO2 concentration experiment for field chambers

    USDA-ARS?s Scientific Manuscript database

    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....

  12. Designing an oscillating CO2 concentration experiment for fild chambers

    USDA-ARS?s Scientific Manuscript database

    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....

  13. Elevated atmospheric CO2 concentration enhances salinity tolerance in Aster tripolium L.

    PubMed

    Geissler, Nicole; Hussin, Sayed; Koyro, Hans-Werner

    2010-02-01

    Our study aimed at investigating the influence of elevated atmospheric CO(2) concentration on the salinity tolerance of the cash crop halophyte Aster tripolium L., thereby focussing on protein expression and enzyme activities. The plants were grown in hydroponics using a nutrient solution with or without addition of NaCl (75% seawater salinity), under ambient (380 ppm) and elevated (520 ppm) CO(2). Under ambient CO(2) concentration enhanced expressions and activities of the antioxidant enzymes superoxide dismutase, ascorbate peroxidase, and glutathione-S-transferase in the salt-treatments were recorded as a reaction to oxidative stress. Elevated CO(2) led to significantly higher enzyme expressions and activities in the salt-treatments, so that reactive oxygen species could be detoxified more effectively. Furthermore, the expression of a protective heat shock protein (class 20) increased under salinity and was even further enhanced under elevated CO(2) concentration. Additional energy had to be provided for the mechanisms mentioned above, which was indicated by the increased expression of a beta ATPase subunit and higher v-, p- and f-ATPase activities under salinity. The higher ATPase expression and activities also enable a more efficient ion transport and compartmentation for the maintenance of ion homeostasis. We conclude that elevated CO(2) concentration is able to improve the survival of A. tripolium under salinity because more energy is provided for the synthesis and enhanced activity of enzymes and proteins which enable a more efficient ROS detoxification and ion compartmentation/transport.

  14. Effects of elevated CO2 concentration on seed production in C3 annual plants.

    PubMed

    Hikosaka, Kouki; Kinugasa, Toshihiko; Oikawa, Shimpei; Onoda, Yusuke; Hirose, Tadaki

    2011-02-01

    The response of seed production to CO(2) concentration ([CO(2)]) is known to vary considerably among C(3) annual species. Here we analyse the interspecific variation in CO(2) responses of seed production per plant with particular attention to nitrogen use. Provided that seed production is limited by nitrogen availability, an increase in seed mass per plant results from increase in seed nitrogen per plant and/or from decrease in seed nitrogen concentration ([N]). Meta-analysis reveals that the increase in seed mass per plant under elevated [CO(2)] is mainly due to increase in seed nitrogen per plant rather than seed [N] dilution. Nitrogen-fixing legumes enhanced nitrogen acquisition more than non-nitrogen-fixers, resulting in a large increase in seed mass per plant. In Poaceae, an increase in seed mass per plant was also caused by a decrease in seed [N]. Greater carbon allocation to albumen (endosperm and/or perisperm) than the embryo may account for [N] reduction in grass seeds. These differences in CO(2) response of seed production among functional groups may affect their fitness, leading to changes in species composition in the future high-[CO(2)] ecosystem.

  15. 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.

  16. Increasing shallow groundwater CO2 and limestone weathering, Konza Prairie, USA

    USGS Publications Warehouse

    Macpherson, G.L.; Roberts, J.A.; Blair, J.M.; Townsend, M.A.; Fowle, D.A.; Beisner, K.R.

    2008-01-01

    In a mid-continental North American grassland, solute concentrations in shallow, limestone-hosted groundwater and adjacent surface water cycle annually and have increased steadily over the 15-year study period, 1991-2005, inclusive. Modeled groundwater CO2, verified by measurements of recent samples, increased from 10-2.05 atm to 10-1.94 atm, about a 20% increase, from 1991 to 2005. The measured groundwater alkalinity and alkaline-earth element concentrations also increased over that time period. We propose that carbonate minerals dissolve in response to lowered pH that occurs during an annual carbonate-mineral saturation cycle. The cycle starts with low saturation during late summer and autumn when dissolved CO2 is high. As dissolved CO2 decreases in the spring and early summer, carbonates become oversaturated, but oversaturation does not exceed the threshold for precipitation. We propose that groundwater is a CO2 sink through weathering of limestone: soil-generated CO2 is transformed to alkalinity through dissolution of calcite or dolomite. The annual cycle and long-term increase in shallow groundwater CO2 is similar to, but greater than, atmospheric CO2. ?? 2008 Elsevier Ltd. All rights reserved.

  17. 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.

  18. New constraints on atmospheric CO2 concentration for the Phanerozoic

    NASA Astrophysics Data System (ADS)

    Franks, Peter J.; Royer, Dana L.; Beerling, David J.; Van de Water, Peter K.; Cantrill, David J.; Barbour, Margaret M.; Berry, Joseph A.

    2014-07-01

    Earth's atmospheric CO2 concentration (ca) for the Phanerozoic Eon is estimated from proxies and geochemical carbon cycle models. Most estimates come with large, sometimes unbounded uncertainty. Here, we calculate tightly constrained estimates of ca using a universal equation for leaf gas exchange, with key variables obtained directly from the carbon isotope composition and stomatal anatomy of fossil leaves. Our new estimates, validated against ice cores and direct measurements of ca, are less than 1000 ppm for most of the Phanerozoic, from the Devonian to the present, coincident with the appearance and global proliferation of forests. Uncertainties, obtained from Monte Carlo simulations, are typically less than for ca estimates from other approaches. These results provide critical new empirical support for the emerging view that large (~2000-3000 ppm), long-term swings in ca do not characterize the post-Devonian and that Earth's long-term climate sensitivity to ca is greater than originally thought.

  19. Plastic and adaptive responses of plant respiration to changes in atmospheric CO(2) concentration.

    PubMed

    Gonzàlez-Meler, Miquel A; Blanc-Betes, Elena; Flower, Charles E; Ward, Joy K; Gomez-Casanovas, Nuria

    2009-12-01

    The concentration of atmospheric CO2 has increased from below 200 microl l(-1) during last glacial maximum in the late Pleistocene to near 280 microl l(-1) at the beginning of the Holocene and has continuously increased since the onset of the industrial revolution. Most responses of plants to increasing atmospheric CO2 levels result in increases in photosynthesis, water use efficiency and biomass. Less known is the role that respiration may play during adaptive responses of plants to changes in atmospheric CO2. Although plant respiration does not increase proportionally with CO2-enhanced photosynthesis or growth rates, a reduction in respiratory costs in plants grown at subambient CO2 can aid in maintaining a positive plant C-balance (i.e. enhancing the photosynthesis-to-respiration ratio). The understanding of plant respiration is further complicated by the presence of the alternative pathway that consumes photosynthate without producing chemical energy [adenosine triphosphate (ATP)] as effectively as respiration through the normal cytochrome pathway. Here, we present the respiratory responses of Arabidopsis thaliana plants selected at Pleistocene (200 microl l(-1)), current Holocene (370 microl l(-1)), and elevated (700 microl l(-1)) concentrations of CO2 and grown at current CO2 levels. We found that respiration rates were lower in Pleistocene-adapted plants when compared with Holocene ones, and that a substantial reduction in respiration was because of reduced activity of the alternative pathway. In a survey of the literature, we found that changes in respiration across plant growth forms and CO2 levels can be explained in part by differences in the respiratory energy demand for maintenance of biomass. This trend was substantiated in the Arabidopsis experiment in which Pleistocene-adapted plants exhibited decreases in respiration without concurrent reductions in tissue N content. Interestingly, N-based respiration rates of plants adapted to elevated CO2 also

  20. CO2 absorption/emission and aerodynamic effects of trees on the concentrations in a street canyon in Guangzhou, China.

    PubMed

    Li, Jian-Feng; Zhan, Jie-Min; Li, Y S; Wai, Onyx W H

    2013-06-01

    In this paper, the effects of trees on CO2 concentrations in a street canyon in Guangzhou, China are examined by Computational Fluid Dynamics (CFD) simulations of the concentration distribution, taking into account both the CO2 absorption/emission and aerodynamic effects of trees. Simulation results show that, under a 2 m/s southerly prevailing wind condition, CO2 absorption by trees will reduce the CO2 concentration by around 2.5% in the daytime and at the same time the trees' resistance will increase the difference of CO2 concentrations in the street and at the inflow by 43%. As the traffic density increases to 50 vehicles/min, the effect of trees on the ambient CO2 concentration will change from positive to negative. At night, trees have a negative effect on the concentration in the street canyon mainly because of their resistance to airflow. When environmental wind changes, the effect of trees will be different.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2009-01-01

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

  3. 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

  4. 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.

  5. A Global Perspective of Atmospheric CO2 Concentrations

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

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

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

    PubMed

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

    2015-05-01

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

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

    PubMed

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

    2017-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2017-09-01

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

  9. 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*].

  10. Photosynthesis and Carbohydrate Partitioning for the C3 Desert Shrub Encelia farinosa under Current and Doubled CO2 Concentrations.

    PubMed Central

    Zhang, H.; Nobel, P. S.

    1996-01-01

    Changes in photosynthesis (A) and carbohydrate partitioning were studied for Encelia farinosa, a common C3 desert shrub in the southwestern United States, after a 3-month exposure to the current or a doubled CO2 concentration (750 [mu]L L-1). A remained unchanged under the current CO2 concentration but decreased during the day under the doubled CO2 concentration, resulting in a 46% enhancement in the early morning, 26% at midday, and 15% in the late afternoon by the elevated CO2. The decrease during the day under the doubled CO2 concentration may represent end-product inhibition, because the sucrose and the starch contents increased during the day proportionally more than under the current CO2 concentration. The 14CO2 activity in sink leaves was maximal 3 h after labeling under the doubled and at 5 h under the current CO2 concentration, indicating faster movement of photosynthate out of source leaves and into sink tissues under the doubled CO2 concentration, which may have been responsible for the sustained enhancement in A under the doubled CO2 concentration. PMID:12226266

  11. Concentration variations of atmospheric CO2 observed at Syowa Station, Antarctica from 1984 to 2000

    NASA Astrophysics Data System (ADS)

    Morimoto, Shinji; Nakazawa, Takakiyo; Aoki, Shuji; Hashida, Gen; Yamanouchi, Takashi

    2003-04-01

    Systematic and continuous measurements of the atmospheric CO2 concentration have been carried out at Syowa Station, Antarctica since February 1984. The measurement system was renewed in 1995, but the continuity of the data from the two systems was confirmed by operating them simultaneously. The CO2 data taken for 17 years from 1984 to 2000 showed clear evidence for a seasonal cycle, a secular trend and interannual variations. The seasonal cycle was variable from year to year, with especially larger amplitudes in 1992 and 1998 and a large phase delay in 1993. A rapid increase in the CO2 concentration was observed in 1987, 1994 and 1998 in association with ENSO events. The average rate of the secular CO2 increase for the last 17 years was calculated to be 1.49 ppmv yr-1. Short-term CO2 variations with amplitudes of around 1.0 ppmv were found in the austral summer season of several years after 1990, probably due to an intrusion of CO2-depleted air mass into the Antarctic region.

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

    NASA Astrophysics Data System (ADS)

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

    2017-06-01

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

  13. Will Elevated CO2 Increase Forest Productivity? Evidence from an Australian FACE Experiment

    NASA Astrophysics Data System (ADS)

    Collins, L.

    2015-12-01

    Rising atmospheric CO2 may enhance forest productivity via CO2 fertilisation and increased soil moisture associated with water savings. Quantification of the response of forest productivity to rising CO2 concentrations is important, as increased forest productivity may contribute to the mitigation of anthropogenic climate change. Vegetation greenness indices derived from digital photographs have been correlated with a number of measures of ecosystem productivity including total biomass, leaf area index and gross primary productivity. Our study examines the effect of elevated CO2 on patterns in overstorey and understorey vegetation greenness at a Free Air CO2 Enrichment facility (EucFACE) situated within a temperate eucalypt forest in Sydney, Australia. EucFACE consists of six treatment areas, three subjected to ambient CO2 ('ambient') and three with ambient plus 150 ppm CO2 ('elevated'). Each treatment area had one camera monitoring canopy greenness for a 12 month period and four cameras monitoring one understorey vegetation plot (2.25 m2) each for a 15 month period. Vegetation greenness was measured daily using the green chromatic coordinate (GCC). Understorey and overstorey GCC and rates of understorey greening and browning were not affected by elevated CO2. Periodic differences in canopy greening and browning between CO2 treatments were observed, though these probably reflect an insect defoliation event in one treatment area. Increases in canopy and understorey GCC were associated with a combination of extended periods of high soil volumetric water content (VWC) (>0.1) and high maximum temperatures (>25 °C). Browning appeared to be associated with a combination of periods of high maximum temperatures and low VWC or low minimum temperatures. Our short term findings suggest that eucalypt forest productivity will be sensitive to changes in climate, but may be relatively insensitive to changes in CO2 in the near future.

  14. 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.

  15. 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.

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

  18. Temperature Modulates Coccolithophorid Sensitivity of Growth, Photosynthesis and Calcification to Increasing Seawater pCO2

    PubMed Central

    Sett, Scarlett; Bach, Lennart T.; Schulz, Kai G.; Koch-Klavsen, Signe; Lebrato, Mario; Riebesell, Ulf

    2014-01-01

    Increasing atmospheric CO2 concentrations are expected to impact pelagic ecosystem functioning in the near future by driving ocean warming and acidification. While numerous studies have investigated impacts of rising temperature and seawater acidification on planktonic organisms separately, little is presently known on their combined effects. To test for possible synergistic effects we exposed two coccolithophore species, Emiliania huxleyi and Gephyrocapsa oceanica, to a CO2 gradient ranging from ∼0.5–250 µmol kg−1 (i.e. ∼20–6000 µatm pCO2) at three different temperatures (i.e. 10, 15, 20°C for E. huxleyi and 15, 20, 25°C for G. oceanica). Both species showed CO2-dependent optimum-curve responses for growth, photosynthesis and calcification rates at all temperatures. Increased temperature generally enhanced growth and production rates and modified sensitivities of metabolic processes to increasing CO2. CO2 optimum concentrations for growth, calcification, and organic carbon fixation rates were only marginally influenced from low to intermediate temperatures. However, there was a clear optimum shift towards higher CO2 concentrations from intermediate to high temperatures in both species. Our results demonstrate that the CO2 concentration where optimum growth, calcification and carbon fixation rates occur is modulated by temperature. Thus, the response of a coccolithophore strain to ocean acidification at a given temperature can be negative, neutral or positive depending on that strain's temperature optimum. This emphasizes that the cellular responses of coccolithophores to ocean acidification can only be judged accurately when interpreted in the proper eco-physiological context of a given strain or species. Addressing the synergistic effects of changing carbonate chemistry and temperature is an essential step when assessing the success of coccolithophores in the future ocean. PMID:24505472

  19. [Dynamics of CO2 and CH4 concentration in the mire soil and its impact factors].

    PubMed

    Song, Chang-chun; Yang, Wen-yan; Xu, Xiao-feng; Lou, Yan-jing; Zhang, Jin-bo

    2004-07-01

    The wetland plays a important role in global carbon cycling in terrestrial ecosystem, the greenhouse gas emission in the mire, especially the CO2 and CH4 level, show distinctly spatial and temporal variation. The product and emission of the CO2 and CH4 are related to soil organic carbon (SOC), dissolved organic carbon (DOC) and nitrogen content, meanwhile which are affected by the soil temperature and hydrological condition. The concentration of CO2 and CH4 are high in mire soil in the Sanjiang plain, especial at the root layer (10-35cm). From the middle of September to October, the aboveground of plant came into die, but the CO2 and CH4 level increase significantly in mire soil, and show significantly positive relationship between them. The ecosystem respiration and the soil respiration affected the methane emission distinctly, also with the significantly positive relationship.

  20. 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

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

    PubMed Central

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

    2017-01-01

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

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

    PubMed

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

    2017-01-01

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

  3. Rising atmospheric CO2 concentration may imply higher risk of Fusarium mycotoxin contamination of wheat grains.

    PubMed

    Bencze, Szilvia; Puskás, Katalin; Vida, Gyula; Karsai, Ildikó; Balla, Krisztina; Komáromi, Judit; Veisz, Ottó

    2017-08-01

    Increasing atmospheric CO2 concentration not only has a direct impact on plants but also affects plant-pathogen interactions. Due to economic and health-related problems, special concern was given thus in the present work to the effect of elevated CO2 (750 μmol mol(-1)) level on the Fusarium culmorum infection and mycotoxin contamination of wheat. Despite the fact that disease severity was found to be not or little affected by elevated CO2 in most varieties, as the spread of Fusarium increased only in one variety, spike grain number and/or grain weight decreased significantly at elevated CO2 in all the varieties, indicating that Fusarium infection generally had a more dramatic impact on the grain yield at elevated CO2 than at the ambient level. Likewise, grain deoxynivalenol (DON) content was usually considerably higher at elevated CO2 than at the ambient level in the single-floret inoculation treatment, suggesting that the toxin content is not in direct relation to the level of Fusarium infection. In the whole-spike inoculation, DON production did not change, decreased or increased depending on the variety × experiment interaction. Cooler (18 °C) conditions delayed rachis penetration while 20 °C maximum temperature caused striking increases in the mycotoxin contents, resulting in extremely high DON values and also in a dramatic triggering of the grain zearalenone contamination at elevated CO2. The results indicate that future environmental conditions, such as rising CO2 levels, may increase the threat of grain mycotoxin contamination.

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

    PubMed

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

    2016-09-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  6. Coccolithophore community response to increasing pCO2 in Mediterranean oligotrophic waters

    NASA Astrophysics Data System (ADS)

    Oviedo, A. M.; Ziveri, P.; Gazeau, F.

    2017-02-01

    The effects of elevated partial pressure of CO2 (pCO2) on plankton communities in oligotrophic ecosystems were studied during two mesocosm experiments: one during summer 2012 in the Bay of Calvi, France, and another during winter 2013 in the Bay of Villefranche, France. Here we report on the relative abundances of coccolithophores versus siliceous phytoplankton, coccolithophore community structure, Emiliania huxleyi coccolith morphology and calcification degree. A pCO2 mediated succession of phytoplankton groups did not occur. During both experiments, coccolithophore abundance and community structure varied with time independently of pCO2 levels. Changes in the community structure were partly explained by the concentration of phosphate during the winter experiment. During the summer experiment, it was not clearly related to any of the parameters measured but possibly to changes in temperature. Phenological changes in the community and an attenuated response due to the low biomass building during the winter experiment could have masked the response to pCO2. E. huxleyi dominated the coccolithophore community in winter; it was not affected by elevated pCO2 at any time. In contrast, the abundance of Rabdosphaera clavigera, the dominant species in summer, increased with time and this increase was affected at elevated pCO2. Thus, a different coccolithophore community response based on species-specific sensitivities to pCO2 is still likely. Finally, elevated pCO2 had no traceable effect on E. huxleyi (type A) coccolith morphology or on the degree of coccolith calcification. Our results highlight the possibility that, in oligotrophic regions, nutrient availability, temperature or intrinsic phenological changes might exert larger constrains on the coccolithophore community structure than high pCO2 does solely.

  7. Improved cardiac contractile functions in hypoxia-reoxygenation in rats treated with low concentration Co(2+).

    PubMed

    Endoh, H; Kaneko, T; Nakamura, H; Doi, K; Takahashi, E

    2000-12-01

    An intracellular mechanism that senses decreases in tissue oxygen level and stimulates hypoxia-related gene expression has been reported in various cell types including the cardiac cell. The mechanism can also be activated by Co(2+) in normoxia. Thus we investigated the effects of prior chronic oral CoCl(2) on mechanical functions of isolated, perfused rat hearts in hypoxia-reoxygenation. In normoxic rats, 43 days of Co(2+) administration increased hematocrit from 45 +/- 0.3% (control, n = 18) to 51 +/- 0.6% (n = 19). In hypoxia and reoxygenation, Co(2+)-pretreated hearts exhibited a significantly higher rate-pressure product (267 and 163%, respectively) and coronary flow (127 and 118%, respectively) and lower end-diastolic pressure (72 and 60%, respectively) compared with the control hearts. Although the oral Co(2+) administration significantly raised myocardial Co(2+) concentration, it did not affect mitochondrial respiration, tissue glycogen concentration, or myocardial tissue histology. The levels of vascular endothelial growth factor, aldolase-A, and glucose transporter-1 mRNA were significantly elevated in the Co(2+)-treated myocardium. We conclude that cardiac contractile functions would gain hypoxic tolerance when the endogenous cellular oxygen-sensing mechanism is activated.

  8. Evaluation of terrestrial carbon cycle models with atmospheric CO2 measurements: Results from transient simulations considering increasing CO2, climate, and land-use effects

    USGS Publications Warehouse

    Dargaville, R.J.; Heimann, Martin; McGuire, A.D.; Prentice, I.C.; Kicklighter, D.W.; Joos, F.; Clein, J.S.; Esser, G.; Foley, J.; Kaplan, J.; Meier, R.A.; Melillo, J.M.; Moore, B.; Ramankutty, N.; Reichenau, T.; Schloss, A.; Sitch, S.; Tian, H.; Williams, L.J.; Wittenberg, U.

    2002-01-01

    An atmospheric transport model and observations of atmospheric CO2 are used to evaluate the performance of four Terrestrial Carbon Models (TCMs) in simulating the seasonal dynamics and interannual variability of atmospheric CO2 between 1980 and 1991. The TCMs were forced with time varying atmospheric CO2 concentrations, climate, and land use to simulate the net exchange of carbon between the terrestrial biosphere and the atmosphere. The monthly surface CO2 fluxes from the TCMs were used to drive the Model of Atmospheric Transport and Chemistry and the simulated seasonal cycles and concentration anomalies are compared with observations from several stations in the CMDL network. The TCMs underestimate the amplitude of the seasonal cycle and tend to simulate too early an uptake of CO2 during the spring by approximately one to two months. The model fluxes show an increase in amplitude as a result of land-use change, but that pattern is not so evident in the simulated atmospheric amplitudes, and the different models suggest different causes for the amplitude increase (i.e., CO2 fertilization, climate variability or land use change). The comparison of the modeled concentration anomalies with the observed anomalies indicates that either the TCMs underestimate interannual variability in the exchange of CO2 between the terrestrial biosphere and the atmosphere, or that either the variability in the ocean fluxes or the atmospheric transport may be key factors in the atmospheric interannual variability.

  9. 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.

  10. Vulnerability of lodging risk to elevated CO2 and increased soil temperature differs between rice cultivars

    USDA-ARS?s Scientific Manuscript database

    Anthropogenic increases in atmospheric carbon dioxide concentration, [CO2], and subsequent increases in surface temperatures, are likely to impact the growth and yield of cereal crops. One means for yield reduction is for climate parameters to increase the occurrence of lodging. Using an in situ f...

  11. Radiative and Physiological Effects of Increased CO2: How Does This Interaction Affect Climate?

    NASA Technical Reports Server (NTRS)

    Bounoua, Lahouari

    2011-01-01

    Several climate models indicate that in a 2xCO2 environment, temperature and precipitation would increase and runoff would increase faster than precipitation. These models, however, did not allow the vegetation to increase its leaf density as a response to the physiological effects of increased CO2 and consequent changes in climate. Other assessments included these interactions but did not account for the vegetation downregulation to reduce plant's photosynthetic activity and as such resulted in a weak vegetation negative response. When we combine these interactions in climate simulations with 2xCO2, the associated increase in precipitation contributes primarily to increase evapotranspiration rather than surface runoff, consistent with observations, and results in an additional cooling effect not fully accounted for in previous 2xCO2 simulations. By accelerating the water cycle, this feedback slows but does not alleviate the projected warming, reducing the land surface warming by 0.6 C. Compared to previous studies, these results imply that long term negative feedback from CO2-induced increases in vegetation density could reduce temperature following a stabilization of CO2 concentration.

  12. Sensitivity of simulated CO2 concentration to spatial aggregation and temporal structure in fossil fuel CO2 emissions generated by FFDAS

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Gurney, K. R.; Rayner, P. J.; Asefi-Najafabady, S.; Liu, Y.; Razlivanov, I. N.; Coltin, K.; McRobert, A.

    2013-12-01

    Accurate representation of fossil fuel CO2 emissions is becoming increasingly critical to atmospheric CO2 inversions, forward carbon cycle modeling and carbon budget studies. With the advent of remotely sensed CO2 concentration and a growing surface CO2 observing network, mischaracterization of the spatial and temporal structure of fossil fuel CO2 emissions can result in considerable error in quantification of the global carbon cycle and interactions with climate change. Here we present a sensitivity analysis of two key aspects of the new global FFDAS version 2.0 fossil fuel CO2 emissions data product, which represents hourly fossil fuel CO2 emissions across the globe. The first is an investigation into the potential aggregation bias of coastal fossil fuel CO2 emissions when aggregated from the 0.1 degree spatial resolution to coarser grid spacing. The second is an analysis of the impact of diurnal, weekly, and monthly time cycles. For the aggregation analysis, we compare a 'shuffled' coastline fossil fuel CO2 emissions to a non-'shuffled' case and analyze the CO2 concentration differences at ground-based coastal CO2 monitoring locations. For the time sensitivity study, we compare a temporally 'flat' fossil fuel CO2 emissions data product to cases with diurnal, weekly, and monthly time structure. We also compare 'flat' emissions to a data product with all time cycles present. The coastal aggregation bias experiment indicates that annual mean surface CO2 concentration differences between the 'shuffled' and non-'shuffled' simulations vary from -6.60 to +6.54 ppmv at coastline locations in the US, Europe and eastern Asia. Examination of these differences at the hourly timescale shows CO2 concentration percent differences at monitoring sites as large as ~60%. Turning to the time sensitivity study, a comparison of flat emissions to emissions with only a diurnal time cycle, exhibit hourly-mean surface CO2 concentration differences ranging from -1.98 to +7.15 ppmv (-8% to

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

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

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

  14. Relationship between photosynthesis and leaf nitrogen concentration in ambient and elevated [CO2] in white birch seedlings.

    PubMed

    Cao, Bing; Dang, Qing-Lai; Zhang, Shouren

    2007-06-01

    To study the effects of elevated CO2 concentration ([CO2]) on relationships between nitrogen (N) nutrition and foliar gas exchange parameters, white birch (Betula papyrifera Marsh.) seedlings were exposed to one of five N-supply regimes (10, 80, 150, 220, 290 mg N l(-1)) in either ambient [CO2] (360 micromol mol(-1)) or elevated [CO2] (720 micromol mol(-1)) in environment-controlled greenhouses. Foliar gas exchange and chlorophyll fluorescence were measured after 60 and 80 days of treatment. Photosynthesis showed a substantial down-regulation (up to 57%) in response to elevated [CO2] and the magnitude of the down-regulation generally decreased exponentially with increasing leaf N concentration. When measured at the growth [CO2], elevated [CO2] increased the overall rate of photosynthesis (P(n)) and instantaneous water-use efficiency (IWUE) by up to 69 and 236%, respectively, but decreased transpiration (E) and stomatal conductance (g(s)) in all N treatments. However, the degree of stimulation of photosynthesis by elevated [CO2] decreased as photosynthetic down-regulation increased from 60 days to 80 days of treatment. Elevated [CO2] significantly increased total photosynthetic electron transport in all N treatments at 60 days of treatment, but the effect was insignificant after 80 days of treatment. Both P(n) and IWUE generally increased with increasing leaf N concentration except at very high leaf N concentrations, where both P(n) and IWUE declined. The relationships of P(n) and IWUE with leaf N concentration were modeled with both a linear regression and a second-order polynomial function. Elevated [CO2] significantly and substantially increased the slope of the linear regression for IWUE, but had no significant effect on the slope for P(n). The optimal leaf N concentration for P(n) and IWUE derived from the polynomial function did not differ between the CO2 treatments when leaf N was expressed on a leaf area basis. However, the mass-based optimal leaf N

  15. Biodynamic mechanism of variations of the atmospheric CO2 concentration

    NASA Astrophysics Data System (ADS)

    Lapenis, A. G.

    1988-06-01

    Using Lapenis's (1986) five-zone model of the world ocean, it is shown that changes in the production of lime plankton caused by changes in the oceanic water circulation during ice ages could significantly affect the oceanic calcium and carbon balances. Changes in Ca and C occurring in surface waters due to glaciation would in turn cause significant declines in atmospheric CO2. A decrease in the atmospheric CO2 would cause additional cooling of the earth surface during ice ages.

  16. Elevated CO2 and O3t concentrations differentially affect selected groups of the fauna in temperate forest soils

    Treesearch

    Gladys I. Loranger; Kurt S. Pregitzer; John S. King

    2004-01-01

    Rising atmospheric CO2 concentrations may change soil fauna abundance. How increase of tropospheric ozone (O3t) concentration will modify these responses is still unknown. We have assessed independent and interactive effects of elevated [CO2] and [O3t] on selected groups of soil...

  17. Multi-day, real-time measurements of CO2 concentration, CO2/SO2 ratios, and d13C of CO2 in volcanic plume

    NASA Astrophysics Data System (ADS)

    Jost, H. J. H.; Rizzo, A. L.; Liuzzo, M.; Ancellin, M. A.

    2015-12-01

    New real-time measurements of CO2 /SO2 ratios, the CO2 concentration and δ13C of CO2 were acquired from July 16 to 20, 2014 in the active plume about 1 km away from the source at the Central Craters of Mount Etna volcano, Italy. During this innovative study we measured d13C in plume gases at a frequency of 0.1 Hz over 5 days of measurements. Assuming two member mixing processes, the extrapolated carbon-isotope composition of the volcanic CO2 ranged from -1.3‰ to +1.5‰, with uncertainties in the repeated single measurements (i.e., made over periods from 4 to 20 min) that were generally <0.7‰, and surprisingly larger variations over the 5-day study period. The range of extrapolated d13C values mostly overlaps with that obtained by discrete sampling and using isotope-ratio mass spectrometry technique (-2.5‰ < d13C < -0.5‰). However, the particular conditions of volcanic activity during the campaign lead us to propose that the carbon-isotope composition of CO2 degassed from magma can reach values (up to +1.5‰), higher than previously reported. Simultaneous measurements of the CO2 and SO2 concentrations using the MultiGAS technique were also performed. The volcanic d13C and CO2/SO2 ratios exhibited similar trends over the 5 days of measurements, with the ratios of both tracers peaking on July 16, possibly as a result of the early degassing of CO2 while an eruption was ongoing at Mount Etna. New questions about the variability of this geochemical tracer arise from the observed variations and the highest d13C values measured at Mount Etna during this campaign. The comparisons with the CO2/SO2 ratio also confirm that monitoring d13C in plume gases in real time, coupled to other geochemical tracers, is important for elucidating the magma dynamics at depth.

  18. A review of national and international activities on modeling the effects of increased CO2 concentrations on the simulation of regional crop production: A report on linkage between climate and crop models

    NASA Astrophysics Data System (ADS)

    Decker, W. L.; Achutuni, R.

    1987-01-01

    General circulation models have been used to estimate the probable changes in climate due to increased levels of carbon dioxide. These models, generally, project increases in the mean surface temperatures; but changes in precipitation due to CO2 enrichment are not as clear. Some process models, which utilize a minimum amount of empiricism, can be adopted for use in studying the impacts of both climate change scenarios and the direct effects of CO2 fertilization. The CERES-Maize, CERES-Wheat, SORGF, GLYCIM, and SOYGRO are among those classified for this use. A great deal of effort is directed toward these developments. WMO/UNEP/ICSU has sponsored at least two European meetings but with only limited success for testing production models. A similar effort has been conducted by the Commission of European Communities. An attempt has been made to modify the CERES models, which have been used in climate studies, for use in simulation of the direct effects. Initial simulations involving this modification, show that doubling CO2 will increase corn production 12 to 30% at locations in northern Illinois for the four-year period 1982 to 1985. Photosynthesis influenced yields more than decreased transpiration.

  19. Recent Widespread Tree Growth Decline Despite Increasing Atmospheric CO2

    PubMed Central

    Silva, Lucas C. R.; Anand, Madhur; Leithead, Mark D.

    2010-01-01

    Background The synergetic effects of recent rising atmospheric CO2 and temperature are expected to favor tree growth in boreal and temperate forests. However, recent dendrochronological studies have shown site-specific unprecedented growth enhancements or declines. The question of whether either of these trends is caused by changes in the atmosphere remains unanswered because dendrochronology alone has not been able to clarify the physiological basis of such trends. Methodology/Principal Findings Here we combined standard dendrochronological methods with carbon isotopic analysis to investigate whether atmospheric changes enhanced water use efficiency (WUE) and growth of two deciduous and two coniferous tree species along a 9° latitudinal gradient across temperate and boreal forests in Ontario, Canada. Our results show that although trees have had around 53% increases in WUE over the past century, growth decline (measured as a decrease in basal area increment – BAI) has been the prevalent response in recent decades irrespective of species identity and latitude. Since the 1950s, tree BAI was predominantly negatively correlated with warmer climates and/or positively correlated with precipitation, suggesting warming induced water stress. However, where growth declines were not explained by climate, WUE and BAI were linearly and positively correlated, showing that declines are not always attributable to warming induced stress and additional stressors may exist. Conclusions Our results show an unexpected widespread tree growth decline in temperate and boreal forests due to warming induced stress but are also suggestive of additional stressors. Rising atmospheric CO2 levels during the past century resulted in consistent increases in water use efficiency, but this did not prevent growth decline. These findings challenge current predictions of increasing terrestrial carbon stocks under climate change scenarios. PMID:20657763

  20. Recent widespread tree growth decline despite increasing atmospheric CO2.

    PubMed

    Silva, Lucas C R; Anand, Madhur; Leithead, Mark D

    2010-07-21

    The synergetic effects of recent rising atmospheric CO(2) and temperature are expected to favor tree growth in boreal and temperate forests. However, recent dendrochronological studies have shown site-specific unprecedented growth enhancements or declines. The question of whether either of these trends is caused by changes in the atmosphere remains unanswered because dendrochronology alone has not been able to clarify the physiological basis of such trends. Here we combined standard dendrochronological methods with carbon isotopic analysis to investigate whether atmospheric changes enhanced water use efficiency (WUE) and growth of two deciduous and two coniferous tree species along a 9 degrees latitudinal gradient across temperate and boreal forests in Ontario, Canada. Our results show that although trees have had around 53% increases in WUE over the past century, growth decline (measured as a decrease in basal area increment--BAI) has been the prevalent response in recent decades irrespective of species identity and latitude. Since the 1950s, tree BAI was predominantly negatively correlated with warmer climates and/or positively correlated with precipitation, suggesting warming induced water stress. However, where growth declines were not explained by climate, WUE and BAI were linearly and positively correlated, showing that declines are not always attributable to warming induced stress and additional stressors may exist. Our results show an unexpected widespread tree growth decline in temperate and boreal forests due to warming induced stress but are also suggestive of additional stressors. Rising atmospheric CO2 levels during the past century resulted in consistent increases in water use efficiency, but this did not prevent growth decline. These findings challenge current predictions of increasing terrestrial carbon stocks under climate change scenarios.

  1. 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

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

    PubMed

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

    2017-04-01

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

  3. A direct human influence on atmospheric CO2 seasonality from increased cropland productivity

    NASA Astrophysics Data System (ADS)

    Gray, J. M.; Frolking, S. E.; Kort, E. A.; Ray, D. K.; Kucharik, C. J.; Ramankutty, N.; Friedl, M. A.

    2014-12-01

    Ground- and aircraft-based measurements show that the seasonal amplitude of Northern Hemisphere atmospheric carbon dioxide (CO2) concentrations has increased by as much as 50% over the last 50 years. This increase has been linked to changes in Temperate, Boreal and Arctic ecosystem properties and processes such as enhanced photosynthesis, increased heterotrophic respiration, and expansion of woody vegetation. However, the precise causal mechanisms behind observed changes in atmospheric CO2 seasonality remain unclear. Here we show that increases in agricultural productivity, which have been largely overlooked in previous investigations, explain as much as 25% of observed changes in atmospheric CO2 seasonality, and perhaps more. Specifically, Northern Hemisphere extratropical maize, wheat, rice, and soybean production grew by 240% between 1961-2008, thereby increasing the amount of net carbon uptake by croplands during the Northern Hemisphere growing season by 0.33 Pg. Maize alone accounts for two-thirds of this change, owing mostly to agricultural intensification within concentrated production zones in the Midwestern United States and Northern China. Since a substantial portion of seasonality enhancement results from a process that is roughly neutral in terms of its impact on the terrestrial carbon sink, our results show that care must be taken when making inferences regarding the linkages between CO2 seasonality and terrestrial carbon sink dynamics. More generally, these results demonstrate how intensive management of agricultural ecosystems over the last five decades have imparted a substantial and direct fingerprint of anthropogenic activities on seasonal patterns of Northern Hemisphere atmospheric CO2.

  4. Agricultural green revolution as a driver of increasing atmospheric CO2 seasonal amplitude

    SciTech Connect

    Zeng, Ning; Zhao, Fang; Collatz, George; Kalnay, Eugenia; Salawitch, Ross J.; West, Tristram O.; Guanter, Luis

    2014-11-20

    The atmospheric carbon dioxide (CO2) record displays a prominent seasonal cycle that arises mainly from changes in vegetation growth and the corresponding CO2 uptake during the boreal spring and summer growing seasons and CO2 release during the autumn and winter seasons. The CO2 seasonal amplitude has increased over the past five decades, suggesting an increase in Northern Hemisphere biospheric activity. It has been proposed that vegetation growth may have been stimulated by higher concentrations of CO2 as well as by warming in recent decades, but such mechanisms have been unable to explain the full range and magnitude of the observed increase in CO2 seasonal amplitude. Here we suggest that the intensification of agriculture (the Green Revolution, in which much greater crop yield per unit area was achieved by hybridization, irrigation and fertilization) during the past five decades is a driver of changes in the seasonal characteristics of the global carbon cycle. Our analysis of CO2 data and atmospheric inversions shows a robust 15 per cent long-term increase in CO2 seasonal amplitude from 1961 to 2010, punctuated by large decadal and interannual variations. Using a terrestrial carbon cycle model that takes into account high-yield cultivars, fertilizer use and irrigation, we find that the long-term increase in CO2 seasonal amplitude arises from two major regions: the mid-latitude cropland between 256N and 606N and the high-latitude natural vegetation between 506N and 706 N. The long-term trend of seasonal amplitude increase is 0.311 ± 0.027 percent per year, of which sensitivity experiments attribute 45, 29 and 26 per cent to land-use change, climate variability and change, and increased productivity due to CO2 fertilization, respectively. Vegetation growth was earlier by one to two weeks, as measured by the mid-point of vegetation carbon uptake, and took up 0.5 petagrams more carbon in July, the height of the growing season, during 2001–2010 than in 1961–1970

  5. Agricultural Green Revolution as a driver of increasing atmospheric CO2 seasonal amplitude.

    PubMed

    Zeng, Ning; Zhao, Fang; Collatz, George J; Kalnay, Eugenia; Salawitch, Ross J; West, Tristram O; Guanter, Luis

    2014-11-20

    The atmospheric carbon dioxide (CO2) record displays a prominent seasonal cycle that arises mainly from changes in vegetation growth and the corresponding CO2 uptake during the boreal spring and summer growing seasons and CO2 release during the autumn and winter seasons. The CO2 seasonal amplitude has increased over the past five decades, suggesting an increase in Northern Hemisphere biospheric activity. It has been proposed that vegetation growth may have been stimulated by higher concentrations of CO2 as well as by warming in recent decades, but such mechanisms have been unable to explain the full range and magnitude of the observed increase in CO2 seasonal amplitude. Here we suggest that the intensification of agriculture (the Green Revolution, in which much greater crop yield per unit area was achieved by hybridization, irrigation and fertilization) during the past five decades is a driver of changes in the seasonal characteristics of the global carbon cycle. Our analysis of CO2 data and atmospheric inversions shows a robust 15 per cent long-term increase in CO2 seasonal amplitude from 1961 to 2010, punctuated by large decadal and interannual variations. Using a terrestrial carbon cycle model that takes into account high-yield cultivars, fertilizer use and irrigation, we find that the long-term increase in CO2 seasonal amplitude arises from two major regions: the mid-latitude cropland between 25° N and 60° N and the high-latitude natural vegetation between 50° N and 70° N. The long-term trend of seasonal amplitude increase is 0.311 ± 0.027 per cent per year, of which sensitivity experiments attribute 45, 29 and 26 per cent to land-use change, climate variability and change, and increased productivity due to CO2 fertilization, respectively. Vegetation growth was earlier by one to two weeks, as measured by the mid-point of vegetation carbon uptake, and took up 0.5 petagrams more carbon in July, the height of the growing season, during 2001-2010 than in

  6. Milk pH as a function of CO2 concentration, temperature, and pressure in a heat exchanger.

    PubMed

    Ma, Y; Barbano, D M

    2003-12-01

    Raw skim milk, with or without added CO2, was heated, held, and cooled in a small pilot-scale tubular heat exchanger (372 ml/min). The experiment was replicated twice, and, for each replication, milk was first carbonated at 0 to 1 degree C to contain 0 (control), 600, 1200, 1800, and 2400 ppm added CO2 using a continuous carbonation unit. After storage at 0 to 1 degree C, portions of milk at each CO2 concentration were heated to 40, 56, 72, and 80 degrees C, held at the desired temperature for 30 s (except 80 degrees C, holding 20 s) and cooled to 0 to 1 degree C. At each temperature, five pressures were applied: 69, 138, 207, 276, and 345 kPa. Pressure was controlled with a needle valve at the heat exchanger exit. Both the pressure gauge and pH probe were inline at the end of the holding section. Milk pH during heating depended on CO2 concentration, temperature, and pressure. During heating of milk without added CO2, pH decreased linearly as a function of increasing temperature but was independent of pressure. In general, the pH of milk with added CO2 decreased with increasing CO2 concentration and pressure. For milk with added CO2, at a fixed CO2 concentration, the effect of pressure on pH decrease was greater at a higher temperature. At a fixed temperature, the effect of pressure on pH decrease was greater for milk with a higher CO2 concentration. Thermal death of bacteria during pasteurization of milk without added CO2 is probably due not only to temperature but also to the decrease in pH that occurs during the process. Increasing milk CO2 concentration and pressure decreases the milk pH even further during heating and may further enhance the microbial killing power of pasteurization.

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

    PubMed

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

    2013-10-01

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

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

    USDA-ARS?s Scientific Manuscript database

    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...

  9. Reversibility in an Earth System model in response to CO2 concentration changes

    NASA Astrophysics Data System (ADS)

    Boucher, O.; Halloran, P. R.; Burke, E. J.; Doutriaux-Boucher, M.; Jones, C. D.; Lowe, J.; Ringer, M. A.; Robertson, E.; Wu, P.

    2012-06-01

    We use the HadGEM2-ES Earth System model to examine the degree of reversibility of a wide range of components of the Earth System under idealized climate change scenarios where the atmospheric CO2 concentration is gradually increased to four times the pre-industrial level and then reduced at a similar rate from several points along this trajectory. While some modelled quantities respond almost immediately to the atmospheric CO2 concentrations, others exhibit a time lag relative to the change in CO2. Most quantities also exhibit a lag relative to the global-mean surface temperature change, which can be described as a hysteresis behaviour. The most surprising responses are from low-level clouds and ocean stratification in the Southern Ocean, which both exhibit hysteresis on timescales longer than expected. We see no evidence of critical thresholds in these simulations, although some of the hysteresis phenomena become more apparent above 2 × CO2 or 3 × CO2. Our findings have implications for the parametrization of climate impacts in integrated assessment and simple climate models and for future climate studies of geoengineering scenarios.

  10. 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

  11. Exchange of carbonyl sulfide (OCS) between soils and atmosphere under various CO2 concentrations

    NASA Astrophysics Data System (ADS)

    Bunk, Rüdiger; Behrendt, Thomas; Yi, Zhigang; Andreae, Meinrat O.; Kesselmeier, Jürgen

    2017-06-01

    A new continuous integrated cavity output spectroscopy analyzer and an automated soil chamber system were used to investigate the exchange processes of carbonyl sulfide (OCS) between soils and the atmosphere under laboratory conditions. The exchange patterns of OCS between soils and the atmosphere were found to be highly dependent on soil moisture and ambient CO2 concentration. With increasing soil moisture, OCS exchange ranged from emission under dry conditions to an uptake within an optimum moisture range, followed again by emission at high soil moisture. Elevated CO2 was found to have a significant impact on the exchange rate and direction as tested with several soils. There is a clear tendency toward a release of OCS at higher CO2 levels (up to 7600 ppm), which are typical for the upper few centimeters within soils. At high soil moisture, the release of OCS increased sharply. Measurements after chloroform vapor application show that there is a biotic component to the observed OCS exchange. Furthermore, soil treatment with the fungi inhibitor nystatin showed that fungi might be the dominant OCS consumers in the soils we examined. We discuss the influence of soil moisture and elevated CO2 on the OCS exchange as a change in the activity of microbial communities. Physical factors such as diffusivity that are governed by soil moisture also play a role. Comparing KM values of the enzymes to projected soil water CO2 concentrations showed that competitive inhibition is unlikely for carbonic anhydrase and PEPCO but might occur for RubisCO at higher CO2 concentrations.

  12. Historical patterns of acidification and increasing CO2 flux associated with Florida springs

    USGS Publications Warehouse

    Barrera, Kira E.; Robbins, Lisa L.

    2017-01-01

    Florida has one of the highest concentrations of springs in the world, with many discharging into rivers and predominantly into eastern Gulf of Mexico coast, and they likely influence the hydrochemistry of these adjacent waters; however, temporal and spatial trends have not been well studied. We present over 20 yr of hydrochemical, seasonally sampled data to identify temporal and spatial trends of pH, alkalinity, partial pressure of carbon dioxide (pCO2), and CO2flux from five first-order-magnitude (springs that discharge greater than 2.83 m3 s−1) coastal spring groups fed by the Floridan Aquifer System that ultimately discharge into the Gulf of Mexico. All spring groups had pCO2 levels (averages 3174.3–6773.2 μatm) that were much higher than atmospheric levels of CO2 and demonstrated statistically significant temporal decreases in pH and increases in CO2 flux, pCO2, and alkalinity. Total carbon flux emissions increased from each of the spring groups by between 3.48 × 107 and 2.856 × 108 kg C yr−1 over the time period. By 2013 the Springs Groups in total emitted more than 1.1739 × 109 kg C yr−1. Increases in alkalinity and pCO2 varied from 90.9 to 347.6 μmol kg−1 and 1262.3 to 2666.7 μatm, respectively. Coastal data show higher CO2 evasion than the open Gulf of Mexico, which suggests spring water influences nearshore waters. The results of this study have important implications for spring water quality, dissolution of the Florida carbonate platform, and identification of the effect and partitioning of carbon fluxes to and within coastal and marine ecosystems.

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

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

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

  14. Self-diffusivity, M-S and Fick diffusivity of CO2 in Na-clay: The influences of concentration and temperature.

    PubMed

    Hu, Haixiang; Xing, Yanfei; Li, Xiaochun

    2017-07-14

    Storing CO2 in underground saline aquifers is an important way to reduce CO2 emission in atmosphere, where gas/fluid diffusion in clay plays a key role in CO2 leakage and migration. Various diffusivities, self-diffusivity, Maxwell-Stefan (M-S) diffusivity and Fick diffusivity, in clay interlayer are investigated by molecular dynamics (MD). Self-diffusivity varies with CO2 concentration, and reaches the maximum value at 2 molecules/unit-cell. High fluid concentration leads to clay swelling, thereby increasing self-diffusivity. However, the fractional free volume of clay explains the trend of CO2 self-diffusivity, which does not decrease with CO2 concentration monotonously but reaches the maximum when CO2 concentration reaches 2. Displacement distribution of CO2 molecules is analysed to explore the microscopic diffusion mechanism, which is characterised by logarithmic normal distribution. The mean value of such distribution further explains the self-diffusivity dependence on CO2 concentration. M-S and Fick diffusivities of CO2 are calculated by MD for the first time, both of which increase with increasing CO2 and H2O concentration and temperature. Based on self-diffusivity and M-S diffusivity, a quantity representing the coupling strength between CO2 molecules is presented; it increases firstly with CO2 concentration but begins to decrease when CO2 concentration is beyond 2.

  15. 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

  16. Seasonality Affects Macroalgal Community Response to Increases in pCO2

    PubMed Central

    Baggini, Cecilia; Salomidi, Maria; Voutsinas, Emanuela; Bray, Laura; Krasakopoulou, Eva; Hall-Spencer, Jason M.

    2014-01-01

    Ocean acidification is expected to alter marine systems, but there is uncertainty about its effects due to the logistical difficulties of testing its large-scale and long-term effects. Responses of biological communities to increases in carbon dioxide can be assessed at CO2 seeps that cause chronic exposure to lower seawater pH over localised areas of seabed. Shifts in macroalgal communities have been described at temperate and tropical pCO2 seeps, but temporal and spatial replication of these observations is needed to strengthen confidence our predictions, especially because very few studies have been replicated between seasons. Here we describe the seawater chemistry and seasonal variability of macroalgal communities at CO2 seeps off Methana (Aegean Sea). Monitoring from 2011 to 2013 showed that seawater pH decreased to levels predicted for the end of this century at the seep site with no confounding gradients in Total Alkalinity, salinity, temperature or wave exposure. Most nutrient levels were similar along the pH gradient; silicate increased significantly with decreasing pH, but it was not limiting for algal growth at all sites. Metal concentrations in seaweed tissues varied between sites but did not consistently increase with pCO2. Our data on the flora are consistent with results from laboratory experiments and observations at Mediterranean CO2 seep sites in that benthic communities decreased in calcifying algal cover and increased in brown algal cover with increasing pCO2. This differs from the typical macroalgal community response to stress, which is a decrease in perennial brown algae and proliferation of opportunistic green algae. Cystoseira corniculata was more abundant in autumn and Sargassum vulgare in spring, whereas the articulated coralline alga Jania rubens was more abundant at reference sites in autumn. Diversity decreased with increasing CO2 regardless of season. Our results show that benthic community responses to ocean acidification are

  17. Meteorological factors controlling soil gases and indoor CO2 concentration: a permanent risk in degassing areas.

    PubMed

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

    2009-02-01

    Furnas volcano is one of the three quiescent central volcanoes of São Miguel Island (Azores Archipelago, Portugal). Its present activity is marked by several degassing manifestations, including fumarolic fields, thermal and cold CO2 springs and soil diffuse degassing areas. One of the most important soil diffuse degassing areas extends below Furnas village, located inside the volcano caldera. A continuous gas geochemistry programme was started at Furnas volcano in October 2001 with the installation of a permanent soil CO2 efflux station that has coupled meteorological sensors to measure barometric pressure, rain, air and soil temperature, air humidity, soil water content and wind speed and direction. Spike-like oscillations are observed on the soil CO2 efflux time series and are correlated with low barometric pressure and heavy rainfall periods. Stepwise multiple regression analysis, applied to the time series obtained, verified that the meteorological variables explain 43.3% of the gas efflux variations. To assess the impact of these influences in inhabited zones a monitoring test was conducted in a Furnas village dwelling placed where soil CO2 concentration is higher than 25 vol.%. Indoor CO2 air concentration measurements at the floor level reached values as higher as 20.8 vol.% during stormy weather periods. A similar test was performed in another degassing area, Mosteiros village, located on the flank of Sete Cidades volcano (S. Miguel Island), showing the same kind of relation between indoor CO2 concentrations and barometric pressure. This work shows that meteorological conditions alone increase the gas exposure risk for populations living in degassing areas.

  18. Plant growth responses to elevated atmospheric CO2 are increased by phosphorus sufficiency but not by arbuscular mycorrhizas

    PubMed Central

    Jakobsen, Iver; Smith, Sally E.; Smith, F. Andrew; Watts-Williams, Stephanie J.; Clausen, Signe S.; Grønlund, Mette

    2016-01-01

    Capturing the full growth potential in crops under future elevated CO2 (eCO2) concentrations would be facilitated by improved understanding of eCO2 effects on uptake and use of mineral nutrients. This study investigates interactions of eCO2, soil phosphorus (P), and arbuscular mycorrhizal (AM) symbiosis in Medicago truncatula and Brachypodium distachyon grown under the same conditions. The focus was on eCO2 effects on vegetative growth, efficiency in acquisition and use of P, and expression of phosphate transporter (PT) genes. Growth responses to eCO2 were positive at P sufficiency, but under low-P conditions they ranged from non-significant in M. truncatula to highly significant in B. distachyon. Growth of M. truncatula was increased by AM at low P conditions at both CO2 levels and eCO2×AM interactions were sparse. Elevated CO2 had small effects on P acquisition, but enhanced conversion of tissue P into biomass. Expression of PT genes was influenced by eCO2, but effects were inconsistent across genes and species. The ability of eCO2 to partly mitigate P limitation-induced growth reductions in B. distachyon was associated with enhanced P use efficiency, and requirements for P fertilizers may not increase in such species in future CO2-rich climates. PMID:27811084

  19. Plant growth responses to elevated atmospheric CO2 are increased by phosphorus sufficiency but not by arbuscular mycorrhizas.

    PubMed

    Jakobsen, Iver; Smith, Sally E; Smith, F Andrew; Watts-Williams, Stephanie J; Clausen, Signe S; Grønlund, Mette

    2016-11-01

    Capturing the full growth potential in crops under future elevated CO2 (eCO2) concentrations would be facilitated by improved understanding of eCO2 effects on uptake and use of mineral nutrients. This study investigates interactions of eCO2, soil phosphorus (P), and arbuscular mycorrhizal (AM) symbiosis in Medicago truncatula and Brachypodium distachyon grown under the same conditions. The focus was on eCO2 effects on vegetative growth, efficiency in acquisition and use of P, and expression of phosphate transporter (PT) genes. Growth responses to eCO2 were positive at P sufficiency, but under low-P conditions they ranged from non-significant in M. truncatula to highly significant in B. distachyon Growth of M. truncatula was increased by AM at low P conditions at both CO2 levels and eCO2×AM interactions were sparse. Elevated CO2 had small effects on P acquisition, but enhanced conversion of tissue P into biomass. Expression of PT genes was influenced by eCO2, but effects were inconsistent across genes and species. The ability of eCO2 to partly mitigate P limitation-induced growth reductions in B. distachyon was associated with enhanced P use efficiency, and requirements for P fertilizers may not increase in such species in future CO2-rich climates.

  20. Analytical solution for the effect of increasing CO2 on global mean temperature

    NASA Astrophysics Data System (ADS)

    Wigley, T. M. L.; Schlesinger, M. E.

    1985-06-01

    The effect on global mean temperature of forcing by a step function change in CO2 concentration and by a steady CO2 increase is analyzed. The former case involves a response time which is strongly dependent on both the effective diffusivity of the ocean below the upper mixed layer, or kappa, and the climate sensitivity, or dT(2x). In the latter case the damped response means that, at any given time, the climate system may be quite far removed from its equilibrium with the prevailing CO2 level. In earlier work this equilibrium was expressed as lag time, but this is shown to be misleading because of the sensitivity of the lag to the history of past CO2 variations. Since both the lag and the degree of disequilibrium are strongly dependent on kappa and dT(2x), and because of uncertainties in the preindustrial CO2 level, the observed global warming over the past 100 years can be shown to be compatible with a wide range of CO2-doubling temperature changes.

  1. [Dynamic observation, simulation and application of soil CO2 concentration: a review].

    PubMed

    Sheng, Hao; Luo, Sha; Zhou, Ping; Li, Teng-Yi; Wang, Juan; Li, Jie

    2012-10-01

    Soil CO2 concentration is the consequences of biological activities in above- and below-ground, and its fluctuation may significantly affect the future atmospheric CO2 concentration and the projected climate change. This paper reviewed the methodologies for measuring the soil CO2 concentration in situ as well as their advantages and disadvantages, analyzed the variation patterns and controlling factors of soil CO2 concentration across the temporal (diurnal, several days, seasonal and inter-annual) and spatial (soil profile, site and landscape) scales, introduced the primary empirical and mechanical models for estimating and predicting soil CO2 concentration, and summarized the applications and constraints of soil CO2 concentration gradient in determining soil respiration. Four research priorities were proposed, i. e., to develop new techniques for collecting and determining the soil CO2 in severe soil conditions (e. g., flooding, lithoso and others), to approach the responses of soil CO2 concentration to weather change and related regulation mechanisms, to strengthen the researches on the spatial heterogeneity of soil CO2 concentration, and to expand the applications of soil CO2 concentration gradient in the measurement of tropical-subtropical soil respiration.

  2. Detection of near-atmospheric concentrations of CO2 by an olfactory subsystem in the mouse.

    PubMed

    Hu, Ji; Zhong, Chun; Ding, Cheng; Chi, Qiuyi; Walz, Andreas; Mombaerts, Peter; Matsunami, Hiroaki; Luo, Minmin

    2007-08-17

    Carbon dioxide (CO2) is an important environmental cue for many organisms but is odorless to humans. It remains unclear whether the mammalian olfactory system can detect CO2 at concentrations around the average atmospheric level (0.038%). We demonstrated the expression of carbonic anhydrase type II (CAII), an enzyme that catabolizes CO2, in a subset of mouse olfactory neurons that express guanylyl cyclase D (GC-D+ neurons) and project axons to necklace glomeruli in the olfactory bulb. Exposure to CO2 activated these GC-D+ neurons, and exposure of a mouse to CO2 activated bulbar neurons associated with necklace glomeruli. Behavioral tests revealed CO2 detection thresholds of approximately 0.066%, and this sensitive CO2 detection required CAII activity. We conclude that mice detect CO2 at near-atmospheric concentrations through the olfactory subsystem of GC-D+ neurons.

  3. Ammonium and nitrate acquisition by plants in response to elevated CO2 concentration: the roles of root physiology and architecture.

    PubMed

    Bauer, G A; Berntson, G M

    2001-02-01

    We examined changes in root system architecture and physiology and whole-plant patterns of nitrate reductase (NR) activity in response to atmospheric CO2 enrichment and N source to determine how changes in the form of N supplied to plants interact with rising CO2 concentration ([CO2]). Seedlings of Betula alleghaniensis Britt. and Pinus strobus L., which differ in growth rate, root architecture, and the partitioning of NR activity between leaves (Betula) and roots (Pinus), were grown in ambient (400 microl l(-1)) and elevated (800 microl l(-1)) [CO2] and supplied with either nitrate (NO3-) or ammonium (NH4+) as their sole N source. After 15 weeks of growth, plants were harvested and root system architecture, N uptake kinetics, and NR activity measured. Betula alleghaniensis responded to elevated [CO2] with significant increases in growth, regardless of the source of N. Pinus strobus showed no significant response in biomass production or allocation to elevated [CO2]. Both species exhibited significantly greater growth with NH4+ than with NO3-, along with lower root:shoot biomass ratios. Betula showed significant increases in total root length in response to elevated [CO2]. However, root N uptake rates in Betula (for both NO3- and NH4+) were either reduced or unchanged by elevated [CO2]. Pinus showed the opposite response to elevated [CO2], with no change in root architecture, but an increase in maximal uptake rates in response to elevated [CO2]. Nitrate reductase activity (on a mass basis) was reduced in leaves of Betula in elevated [CO2], but did not change in other tissues. Nitrate reductase activity was unaffected by elevated [CO2] in Pinus. Scaling this response to the whole-plant, NR activity was reduced in elevated [CO2] in Betula but not in Pinus. However, because Betula plants were larger in elevated [CO2], total whole-plant NR activity was unaffected.

  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

    2015-08-13

    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.

  5. 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

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

    PubMed

    Israel, A A; Nobel, P S

    1994-06-01

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

  7. Robust increase of seasonal amplitude in simulated terrestrial CO2 exchange in last decades

    NASA Astrophysics Data System (ADS)

    Inatomi, M. I.; Ito, A.

    2014-12-01

    Ongoing climatic change is expected to affect terrestrial carbon budget by altering growing period and photosynthetic and respiratory processes. Indeed, a recent atmospheric study (Graven et al. 2013) shows that seasonal amplitude of atmospheric CO2 concentration has bee increased since 1960. Because of the lack of long-term observational data except phenology, it is difficult to confirm such enhancement of vegetation activity through a direct approach. Therefore, we examined the simulated terrestrial CO2 exchange by a process-based model (VISIT) from 1901 to 2010, using the MsTMIP protocol. Several metrics were used to characterize the seasonal amplitude: maximum photosynthetic uptake and respiratory release and cumulative net biome production (NBP). To separate the effects of climatic change and elevated atmospheric increase, two simulation results (climate, climate+CO2) were compared. The results showed that the seasonal amplitude defined as the maximum?minimum cumulative NBP in the Northern Hemisphere increased by 16% from the 1960s to the 2000s. Such increase in seasonal amplitude was more evident in North America and Europe, compared with Siberia and Asia. In the climate-only simulation, northern seasonal amplitude decreased from 1965 to 1980, a climatic cooling period, and then increased since then. These results indicate that the observed increase of atmospheric CO2 concentration amplitude is largely attributable to enhanced terrestrial vegetation activity. We would compare these results with those by other terrestrial ecosystem models and possibly with some observational record.

  8. Regional Effects of Doubled CO2 Concentrations on the Hydrology of California

    NASA Astrophysics Data System (ADS)

    Snyder, M. A.; Bell, J. L.; Sloan, L. C.

    2001-12-01

    The effects of changing atmospheric CO2 concentration have been evaluated primarily using global scale models and statistical downscaling techniques. This study incorporates ensembles of experiments with a high resolution regional climate model (RCM) over a hydrologicaly sensitive region, and tests the effects of 280 ppm CO2 (1x) and 560 ppm CO2 (2x) on the climate of California. The model output was subdivided by hydrologic regions and then analyzed. A control run using modern day CO2 concentrations and climatological sea surface temperatures (SST) was performed and compared with observations. The model performs well in simulating the mean modern day climate, but underestimates the variability. The RCM output for the 1x and 2x cases was analyzed to determine differences, the significance of the results, and the amount of variability. Statistically significant temperature increases of up to 3.8 \\deg C occur on an annual average basis throughout the state. Precipitation increases by 23% over the northern half of the state, while precipitation in the southern half shows no change. Annual average snow accumulation decreases everywhere in the state by up to 120 mm water equivalent.

  9. 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.

  10. 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

  11. 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.

  12. Photorespiratory and respiratory decarboxylations in leaves of C3 plants under different CO2 concentrations and irradiances.

    PubMed

    Pärnik, T; Ivanova, H; Keerberg, O

    2007-12-01

    We used an advanced radiogasometric method to study the effects of short-term changes in CO2 concentration ([CO2]) on the rates and substrates of photorespiratory and respiratory decarboxylations under steady-state photosynthesis and in the dark. Experiments were carried out on Plantago lanceolata, Poa trivialis, Secale cereale, Triticum aestivum, Helianthus annuus and Arabidopsis thaliana plants. Rates of photorespiration and respiration measured at a low [CO2] (40 micromol mol(-1)) were equal to those at normal [CO2] (360 micromol mol(-1)). Under low [CO2], the substrates of decarboxylation reactions were derived mainly from stored photosynthates, while under normal [CO2] primary photosynthates were preferentially consumed. An increase in [CO2] from 320 to 2300 micromol mol(-1) brought about a fourfold decrease in the rate of photorespiration with a concomitant 50% increase in the rate of respiration in the light. Respiration in the dark did not depend on [CO2] up to 30 mmol mol(-1). A positive correlation was found between the rate of respiration in the dark and the rate of photosynthesis during the preceding light period. The respiratory decarboxylation of stored photosynthates was suppressed by light. The extent of light inhibition decreased with increasing [CO2]; no inhibition was detected at 30 mmol mol(-1) CO2.

  13. 12CO2 emission from different metabolic pathways measured in illuminated and darkened C3 and C4 leaves at low, atmospheric and elevated CO2 concentration.

    PubMed

    Pinelli, Paola; Loreto, Francesco

    2003-07-01

    The detection of 12CO2 emission from leaves in air containing 13CO2 allows simple and fast determination of the CO2 emitted by different sources, which are separated on the basis of their labelling velocity. This technique was exploited to investigate the controversial effect of CO2 concentration on mitochondrial respiration. The 12CO2 emission was measured in illuminated and darkened leaves of one C4 plant and three C3 plants maintained at low (30-50 ppm), atmospheric (350-400 ppm) and elevated (700-800 ppm) CO2 concentration. In C3 leaves, the 12CO2 emission in the light (Rd) was low at ambient CO2 and was further quenched in elevated CO2, when it was often only 20-30% of the 12CO2 emission in the dark, interpreted as the mitochondrial respiration in the dark (Rn). Rn was also reduced in elevated CO2. At low CO2, Rd was often 70-80% of Rn, and a burst of 12CO2 was observed on darkening leaves of Mentha sativa and Phragmites australis after exposure for 4 min to 13CO2 in the light. The burst was partially removed at low oxygen and was never observed in C4 leaves, suggesting that it may be caused by incomplete labelling of the photorespiratory pool at low CO2. This pool may be low in sclerophyllous leaves, as in Quercus ilex where no burst was observed. Rd was inversely associated with photosynthesis, suggesting that the Rd/Rn ratio reflects the refixation of respiratory CO2 by photosynthesizing leaves rather than the inhibition of mitochondrial respiration in the light, and that CO2 produced by mitochondrial respiration in the light is mostly emitted at low CO2, and mostly refixed at elevated CO2. In the leaves of the C4 species Zea mays, the 12CO2 emission in the light also remained low at low CO2, suggesting efficient CO2 refixation associated with sustained photosynthesis in non-photorespiratory conditions. However, Rn was inhibited in CO2-free air, and the velocity of 12CO2 emission after darkening was inversely associated with the CO2 concentration. The

  14. [Eco-physiological response of Quercus variabilis seedlings to increased atmospheric CO2 and N supply].

    PubMed

    Du, Qi-Ran; Lei, Jing-Pin; Liu, Jian-Feng; Wang, Peng-Cheng; Xiao, Wen-Fa; Pan, Lei

    2014-01-01

    The effect of CO2 enhancement, nitrogen deposition and their interaction on the northern boundary (Zhuanghe in Liaoning Province) of Quercus variabilis seedlings was studied by controlling the CO2 concentration (700 micromol x mol(-1); 400 micromol x mol(-1)) and nitrogen level (non nitrogen fertilizer: CK; nitrogen fertilizer: 120 kg N x hm(-2)). The results showed that under elevated CO2 the Q. variabilis seedlings' leaf morphology, photosynthetic pigments and leaf nitrogen content tended to decrease, and the dark respiration rate decreased 63. 3% and soluble sugar increased 2.6%. Nitrogen deposition significantly promoted the Q. variabilis seedlings' leaf morphology and photosynthetic pigments, leading to increased leaf nitrogen content, decreased potassium content, and 26.7% of increase in nitrogen to potassium ratio. CO2 and N interaction played a significant role on promoting the Q. variabilis seedlings' leaf morphology and photosynthetic. The maximum net photosynthetic and light saturation point were 1.4 and 2.6 times of the control, while dark respiration and light compensation point decreased 65.9% and 50.0%, respectively. Elevated CO2 and nitrogen deposition had a positive effect on Q. variabilis seedlings to some degree, which might result in the movement of distribution boundary of Q. variabilis to north.

  15. CO2 increases 14C-primary production in an Arctic plankton community

    NASA Astrophysics Data System (ADS)

    Engel, A.; Borchard, C.; Piontek, J.; Schulz, K.; Riebesell, U.; Bellerby, R.

    2012-08-01

    Responses to ocean acidification in plankton communities were studied during a CO2-enrichment experiment in the Arctic Ocean, accomplished from June to July 2010 in Kongsfjorden, Svalbard (78°56, 2' N, 11°53, 6' E). Enclosed in 9 mesocosms (volume: 43.9-47.6 m3), plankton was exposed to CO2 concentrations, ranging from glacial to projected mid-next-century levels. Fertilization with inorganic nutrients at day 13 of the experiment supported the accumulation of phytoplankton biomass, as indicated by two periods of high Chl a concentration. This study tested for CO2 sensitivities in primary production (PP) of particulate organic carbon (PPPOC) and of dissolved organic carbon (PPDOC). Therefore, 14C-bottle incubations (24 h) of mesocosm samples were performed at 1 m depth receiving about 60% of incoming radiation. PP for all mesocosms averaged 8.06 ± 3.64 μmol C l-1 d-1 and was slightly higher than in the outside fjord system. Comparison between mesocosms revealed significantly higher PPPOC at elevated compared to low pCO2 after nutrient addition. PPDOC was significantly higher in CO2 enriched mesocosms before as well as after nutrient addition, suggesting that CO2 had a direct influence on DOC production. DOC concentrations inside the mesocosms increased before nutrient addition and more in high CO2 mesocosms. After addition of nutrients, however, further DOC accumulation was negligible and not significantly different between treatments, indicating rapid utilization of freshly produced DOC. Bacterial biomass production (BP) was coupled to PP in all treatments, indicating that 3.5 ± 1.9% of PP, or 21.6 ± 12.5% of PPDOC provided sufficient carbon for synthesis of bacterial biomass. The response of 14C-based PP rates to CO2 enrichment was at odds with O2-based net community production (NCP) rates that were also determined during this study, albeit at lower light level. We conclude that the enhanced release of labile DOC during autotrophic production at high CO2

  16. CO2 increases 14C primary production in an Arctic plankton community

    NASA Astrophysics Data System (ADS)

    Engel, A.; Borchard, C.; Piontek, J.; Schulz, K. G.; Riebesell, U.; Bellerby, R.

    2013-03-01

    Responses to ocean acidification in plankton communities were studied during a CO2-enrichment experiment in the Arctic Ocean, accomplished from June to July 2010 in Kongsfjorden, Svalbard (78°56' 2'' N, 11°53' 6'' E). Enclosed in 9 mesocosms (volume: 43.9-47.6 m3), plankton was exposed to CO2 concentrations, ranging from glacial to projected mid-next-century levels. Fertilization with inorganic nutrients at day 13 of the experiment supported the accumulation of phytoplankton biomass, as indicated by two periods of high chl a concentration. This study tested for CO2 sensitivities in primary production (PP) of particulate organic carbon (PPPOC) and of dissolved organic carbon (PPDOC). Therefore, 14C-bottle incubations (24 h) of mesocosm samples were performed at 1 m depth receiving about 60% of incoming radiation. PP for all mesocosms averaged 8.06 ± 3.64 μmol C L-1 d-1 and was slightly higher than in the outside fjord system. Comparison between mesocosms revealed significantly higher PPPOC at elevated compared to low pCO2 after nutrient addition. PPDOC was significantly higher in CO2-enriched mesocosms before as well as after nutrient addition, suggesting that CO2 had a direct influence on DOC production. DOC concentrations inside the mesocosms increased before nutrient addition and more in high CO2 mesocosms. After addition of nutrients, however, further DOC accumulation was negligible and not significantly different between treatments, indicating rapid utilization of freshly produced DOC. Bacterial biomass production (BP) was coupled to PP in all treatments, indicating that 3.5 ± 1.9% of PP or 21.6 ± 12.5% of PPDOC provided on average sufficient carbon for synthesis of bacterial biomass. During the later course of the bloom, the response of 14C-based PP rates to CO2 enrichment differed from net community production (NCP) rates that were also determined during this mesocosm campaign. We conclude that the enhanced release of labile DOC during autotrophic

  17. Future carbon balance of China's forests under climate change and increasing CO2.

    PubMed

    Ju, W M; Chen, J M; Harvey, D; Wang, S

    2007-11-01

    The possible response of the carbon (C) balance of China's forests to an increase in atmospheric CO(2) concentration and climate change was investigated through a series of simulations using the Integrated Terrestrial Ecosystem Carbon (InTEC) model, which explicitly represents the effects of climate, CO(2) concentration, and nitrogen deposition on future C sequestration by forests. Two climate change scenarios (CGCM2-A2 and -B2) were used to drive the model. Simulations showed that China's forests were a C sink in the 1990 s, averaging 189 Tg C yr(-1) (about 13% of the global total). This sink peaks around 2020 and then gradually declines to 33.5 Tg C yr(-1) during 2091-2100 without climate and CO(2) changes. Effects of pure climate change of CGCM2-A2 and -B2 without allowing CO(2) effects on C assimilation in plants might reduce the average net primary productivity (NPP) of China's forests by 29% and 18% during 2091-2100, respectively. Total soil C stocks might decrease by 16% and 11% during this period. China's forests might broadly act as C sources during 2091-2100, with values of about 50 g Cm(-2)yr(-1) under the moderate warming of CGCM2-B2 and 50-200 g Cm(-2)yr(-1) under the warmer scenario of CGCM2-A2. An increase in CO(2) might broadly increase future C sequestration of China's forests. However, this CO(2) fertilization effect might decline with time. The CO(2) fertilization effects on NPP by the end of this century are 349.6 and 241.7 Tg C yr(-1) under CGCM2-A2 and -B2 increase scenarios, respectively. These effects increase by 199.1 and 126.6 Tg C yr(-1) in the first 50 years, and thereafter, by 150.5 and 115.1 Tg C yr(-1) in the second 50 years under CGCM2-A2 and -B2 increase scenarios, respectively. Under a CO(2) increase without climate change, the majority of China's forests would be C sinks during 2091-2100, ranging from 0 to 100 g Cm(-2)yr(-1). The positive effect of CO(2) fertilization on NPP and net ecosystem productivity would be exceeded by the

  18. Genotypic variation in physiological and growth responses of Populus tremuloides to elevated atmospheric CO2 concentration.

    PubMed

    Wang, X; Curtis, P S; Pregitzer, K S; Zak, D R

    2000-09-01

    Physiological and biomass responses of six genotypes of Populus tremuloides Michx., grown in ambient t (357 micromol mol(-1)) or twice ambient (707 micromol mol(-1)) CO2 concentration ([CO2]) and in low-N or high-N soils, were studied in 1995 and 1996 in northern Lower Michigan, USA. There was a significant CO2 x genotype interaction in photosynthetic responses. Net CO2 assimilation (A) was significantly enhanced by elevated [CO2] for five genotypes in high-N soil and for four genotypes in low-N soil. Enhancement of A by elevated [CO2] ranged from 14 to 68%. Genotypes also differed in their biomass responses to elevated [CO2], but biomass responses were poorly correlated with A responses. There was a correlation between magnitude of A enhancement by elevated [CO2] and stomatal sensitivity to CO2. Genotypes with low stomatal sensitivity to CO2 had a significantly higher A at elevated [CO2] than at ambient [CO2], but elevated [CO2] did not affect the ratio of intercellular [CO2] to leaf surface [CO2]. Stomatal conductance and A of different genotypes responded differentially to recovery from drought stress. Photosynthetic quantum yield and light compensation point were unaffected by elevated [CO2]. We conclude that P. tremuloides genotypes will respond differentially to rising atmospheric [CO2], with the degree of response dependent on other abiotic factors, such as soil N and water availability. The observed genotypic variation in growth could result in altered genotypic representation within natural populations and could affect the composition and structure of plant communities in a higher [CO2] environment in the future.

  19. Associations between classroom CO2 concentrations and student attendance in Washington and Idaho.

    PubMed

    Shendell, D G; Prill, R; Fisk, W J; Apte, M G; Blake, D; Faulkner, D

    2004-10-01

    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(2)). Absence and dCO(2) data were collected from 409 traditional and 25 portable classrooms from 22 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(2) concentrations above 1000 p.p.m. A 1000 p.p.m. increase in dCO(2) was associated (P < 0.05) with a 0.5-0.9% decrease in annual average daily attendance (ADA), corresponding to a relative 10-20% increase in student absence. Annual ADA was 2% higher (P < 0.0001) in traditional than in portable classrooms. This study provides motivation for larger school studies to investigate associations of student attendance, and occupant health and student performance, with longer term indoor minus outdoor CO(2) concentrations and more accurately measured ventilation rates. If our findings are confirmed, improving classroom ventilation should be considered a practical means of reducing student absence. Adequate or enhanced ventilation may be achieved, for example, with educational training programs for teachers and facilities staff on ventilation system operation and maintenance. Also, technological interventions such as improved automated control systems could provide continuous ventilation during occupied times, regardless of

  20. Elevated atmospheric CO2 increases microbial growth rates and enzymes activity in soil

    NASA Astrophysics Data System (ADS)

    Blagodatskaya, Evgenia; Blagodatsky, Sergey; Dorodnikov, Maxim; Kuzyakov, Yakov

    2010-05-01

    Increasing the belowground translocation of assimilated carbon by plants grown under elevated CO2 can cause a shift in the structure and activity of the microbial community responsible for the turnover of organic matter in soil. We investigated the long-term effect of elevated CO2 in the atmosphere on microbial biomass and specific growth rates in root-free and rhizosphere soil. The experiments were conducted under two free air carbon dioxide enrichment (FACE) systems: in Hohenheim and Braunschweig, as well as in the intensively managed forest mesocosm of the Biosphere 2 Laboratory (B2L) in Oracle, AZ. Specific microbial growth rates (μ) were determined using the substrate-induced respiration response after glucose and/or yeast extract addition to the soil. We evaluated the effect of elevated CO2 on b-glucosidase, chitinase, phosphatase, and sulfatase to estimate the potential enzyme activity after soil amendment with glucose and nutrients. For B2L and both FACE systems, up to 58% higher μ were observed under elevated vs. ambient CO2, depending on site, plant species and N fertilization. The μ-values increased linearly with atmospheric CO2 concentration at all three sites. The effect of elevated CO2 on rhizosphere microorganisms was plant dependent and increased for: Brassica napus=Triticum aestivumincrease or decrease of microbial growth rates depending on plant species. The μ-value increase was lower for microorganisms growing on yeast extract then for those growing on glucose, i.e. the effect of elevated CO2 was smoothed on rich vs. simple substrate. So, the r/K strategies ratio can be better revealed by studying growth on simple (glucose) than on rich substrate mixtures (yeast extract). After adding glucose, enzyme activities under elevated CO2 were

  1. Faster turnover of new soil carbon inputs under increased atmospheric CO2.

    PubMed

    van Groenigen, Kees Jan; Osenberg, Craig W; Terrer, César; Carrillo, Yolima; Dijkstra, Feike A; Heath, James; Nie, Ming; Pendall, Elise; Phillips, Richard P; Hungate, Bruce A

    2017-10-01

    Rising levels of atmospheric CO2 frequently stimulate plant inputs to soil, but the consequences of these changes for soil carbon (C) dynamics are poorly understood. Plant-derived inputs can accumulate in the soil and become part of the soil C pool ("new soil C"), or accelerate losses of pre-existing ("old") soil C. The dynamics of the new and old pools will likely differ and alter the long-term fate of soil C, but these separate pools, which can be distinguished through isotopic labeling, have not been considered in past syntheses. Using meta-analysis, we found that while elevated CO2 (ranging from 550 to 800 parts per million by volume) stimulates the accumulation of new soil C in the short term (<1 year), these effects do not persist in the longer term (1-4 years). Elevated CO2 does not affect the decomposition or the size of the old soil C pool over either temporal scale. Our results are inconsistent with predictions of conventional soil C models and suggest that elevated CO2 might increase turnover rates of new soil C. Because increased turnover rates of new soil C limit the potential for additional soil C sequestration, the capacity of land ecosystems to slow the rise in atmospheric CO2 concentrations may be smaller than previously assumed. © 2017 John Wiley & Sons Ltd.

  2. Faster Turnover of New Soil Carbon Inputs under Increased Atmospheric CO2

    NASA Astrophysics Data System (ADS)

    van Groenigen, K. J.; Osenberg, C. W.; Carrillo, Y.; Dijkstra, F. A.; Heath, J.; Nie, M.; Pendall, E.; Phillips, R.; Hungate, B. A.

    2016-12-01

    Rising levels of atmospheric CO2 frequently stimulate plant inputs to soil, but the consequences of these changes for soil carbon (C) dynamics are poorly understood. Plant-derived inputs can accumulate in the soil and become part of the soil C pool ("new soil C"), or accelerate losses of pre-existing soil C. The dynamics of these pools will likely differ and alter the long-term fate of soil C, but these separate pools, which can be distinguished through isotopic labeling, have not been considered in past syntheses. Here we show, using meta-analysis, that while elevated CO2 (ranging from 550 to 800 parts per million by volume) stimulates the accumulation of new soil C in the short term (<1 year), these effects do not persist in the long term (> 1 year). Moreover, elevated CO2 does not affect the decomposition or the size of the pre-existing soil C pool over any temporal scale. Our results are inconsistent with predictions of conventional soil C models and suggest an increase in turnover rates of new soil C under elevated CO2. Because increased soil C turnover rates limit the potential for soils to sequester additional C, the capacity of land ecosystems to slow the rise in atmospheric CO2 concentrations may be smaller than previously assumed.

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

    PubMed Central

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

    2017-01-01

    The atmospheric carbon dioxide (CO2) level is expected to increase substantially, which may change the global climate and carbon dynamics in ecosystems. We examined the effects of an elevated atmospheric CO2 level on the growth of Quercus acutissima and Fraxinus rhynchophylla seedlings. We investigated changes in the chemical composition of leaf litter, as well as litter decomposition. Q. acutissima and F. rhynchophylla did not show differences in dry weight between ambient CO2 and enriched CO2 treatments, but they exhibited different patterns of carbon allocation, namely, lower shoot/root ratio (S/R) and decreased specific leaf area (SLA) under CO2-enriched conditions. The elevated CO2 concentration significantly reduced the nitrogen concentration in leaf litter while increasing lignin concentrations and carbon/nitrogen (C/N) and lignin/N ratios. The microbial biomass associated with decomposing Q. acutissima leaf litter was suppressed in CO2 enrichment chambers, while that of F. rhynchophylla was not. The leaf litter of Q. acutissima from the CO2-enriched chambers, in contrast with F. rhynchophylla, contained much lower nutrient concentrations than that of the litter in the ambient air chambers. Consequently, poorer litter quality suppressed decomposition. PMID:28182638

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

    PubMed

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

    2017-01-01

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

  5. Experimental study on CO and CO2 emissions from spontaneous heating of coals at varying temperatures and O2 concentrations.

    PubMed

    Yuan, Liming; Smith, Alex C

    2013-11-01

    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.

  6. Contemporary reliance on bicarbonate acquisition predicts increased growth of seagrass Amphibolis antarctica in a high-CO2 world.

    PubMed

    Burnell, Owen W; Connell, Sean D; Irving, Andrew D; Watling, Jennifer R; Russell, Bayden D

    2014-01-01

    Rising atmospheric CO2 is increasing the availability of dissolved CO2 in the ocean relative to HCO3 (-). Currently, many marine primary producers use HCO3 (-) for photosynthesis, but this is energetically costly. Increasing passive CO2 uptake relative to HCO3 (-) pathways could provide energy savings, leading to increased productivity and growth of marine plants. Inorganic carbon-uptake mechanisms in the seagrass Amphibolis antarctica were determined using the carbonic anhydrase inhibitor acetazolamide (AZ) and the buffer tris(hydroxymethyl)aminomethane (TRIS). Amphibolis antarctica seedlings were also maintained in current and forecasted CO2 concentrations to measure their physiology and growth. Photosynthesis of A. antarctica was significantly reduced by AZ and TRIS, indicating utilization of HCO3 (-)-uptake mechanisms. When acclimated plants were switched between CO2 treatments, the photosynthetic rate was dependent on measurement conditions but not growth conditions, indicating a dynamic response to changes in dissolved CO2 concentration, rather than lasting effects of acclimation. At forecast CO2 concentrations, seedlings had a greater maximum electron transport rate (1.4-fold), photosynthesis (2.1-fold), below-ground biomass (1.7-fold) and increase in leaf number (2-fold) relative to plants in the current CO2 concentration. The greater increase in photosynthesis (measured as O2 production) compared with the electron transport rate at forecasted CO2 concentration suggests that photosynthetic efficiency increased, possibly due to a decrease in photorespiration. Thus, it appears that the photosynthesis and growth of seagrasses reliant on energetically costly HCO3 (-) acquisition, such as A. antarctica, might increase at forecasted CO2 concentrations. Greater growth might enhance the future prosperity and rehabilitation of these important habitat-forming plants, which have experienced declines of global significance.

  7. Contemporary reliance on bicarbonate acquisition predicts increased growth of seagrass Amphibolis antarctica in a high-CO2 world

    PubMed Central

    Burnell, Owen W.; Connell, Sean D.; Irving, Andrew D.; Watling, Jennifer R.; Russell, Bayden D.

    2014-01-01

    Rising atmospheric CO2 is increasing the availability of dissolved CO2 in the ocean relative to HCO3−. Currently, many marine primary producers use HCO3− for photosynthesis, but this is energetically costly. Increasing passive CO2 uptake relative to HCO3− pathways could provide energy savings, leading to increased productivity and growth of marine plants. Inorganic carbon-uptake mechanisms in the seagrass Amphibolis antarctica were determined using the carbonic anhydrase inhibitor acetazolamide (AZ) and the buffer tris(hydroxymethyl)aminomethane (TRIS). Amphibolis antarctica seedlings were also maintained in current and forecasted CO2 concentrations to measure their physiology and growth. Photosynthesis of A. antarctica was significantly reduced by AZ and TRIS, indicating utilization of HCO3−-uptake mechanisms. When acclimated plants were switched between CO2 treatments, the photosynthetic rate was dependent on measurement conditions but not growth conditions, indicating a dynamic response to changes in dissolved CO2 concentration, rather than lasting effects of acclimation. At forecast CO2 concentrations, seedlings had a greater maximum electron transport rate (1.4-fold), photosynthesis (2.1-fold), below-ground biomass (1.7-fold) and increase in leaf number (2-fold) relative to plants in the current CO2 concentration. The greater increase in photosynthesis (measured as O2 production) compared with the electron transport rate at forecasted CO2 concentration suggests that photosynthetic efficiency increased, possibly due to a decrease in photorespiration. Thus, it appears that the photosynthesis and growth of seagrasses reliant on energetically costly HCO3− acquisition, such as A. antarctica, might increase at forecasted CO2 concentrations. Greater growth might enhance the future prosperity and rehabilitation of these important habitat-forming plants, which have experienced declines of global significance. PMID:27293673

  8. 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.

  9. 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

    canonical range (1.5 to 4.5 degrees Celsius), indicating that a large fraction of the warmth of the early Eocene greenhouse was driven by increased CO2 concentrations, and that climate sensitivity was relatively constant throughout this period.

  10. 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

    canonical range (1.5 to 4.5 degrees Celsius), indicating that a large fraction of the warmth of the early Eocene greenhouse was driven by increased CO2 concentrations, and that climate sensitivity was relatively constant throughout this period.

  11. Changes in the structure and propagation of the MJO with increasing CO2

    NASA Astrophysics Data System (ADS)

    Adames, Ángel F.; Kim, Daehyun; Sobel, Adam H.; Del Genio, Anthony; Wu, Jingbo

    2017-06-01

    Changes in the Madden-Julian Oscillation (MJO) with increasing CO2 concentrations are examined using the Goddard Institute for Space Studies Global Climate Model (GCM). Four simulations performed with fixed CO2 concentrations of 0.5, 1, 2, and 4 times preindustrial levels using the GCM coupled with a mixed layer ocean model are analyzed in terms of the basic state, rainfall, moisture and zonal wind variability, and the structure and propagation of the MJO. The GCM simulates basic state changes associated with increasing CO2 that are consistent with results from earlier studies: column water vapor increases at ˜7.1% K-1, precipitation also increases but at a lower rate (˜3% K-1), and column relative humidity shows little change. Moisture and rainfall variability intensify with warming while zonal wind variability shows little change. Total moisture and rainfall variability increases at a rate this is similar to that of the mean state change. The intensification is faster in the MJO-related anomalies than in the total anomalies, though the ratio of the MJO band variability to its westward counterpart increases at a much slower rate. On the basis of linear regression analysis and space-time spectral analysis, it is found that the MJO exhibits faster eastward propagation, faster westward energy dispersion, a larger zonal scale, and deeper vertical structure in warmer climates.Plain Language SummaryChanges in the Madden-Julian Oscillation (MJO) with <span class="hlt">increasing</span> carbon dioxide (<span class="hlt">CO</span><span class="hlt">2</span>) <span class="hlt">concentrations</span> are examined using the Goddard Institute for Space Studies Global Climate Model (GCM). Four simulations performed with varying amounts of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>. We analyze the climatology and variability in rainfall and water vapor, and the structure and propagation of the MJO. The GCM simulates basic state changes associated with <span class="hlt">increasing</span> <span class="hlt">CO</span><span class="hlt">2</span> that are consistent with results from earlier studies: column water vapor <span class="hlt">increases</span> at 7</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3248712','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3248712"><span>Physiological framework for adaptation of stomata to <span class="hlt">CO</span><span class="hlt">2</span> from glacial to future <span class="hlt">concentrations</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Franks, Peter J.; Leitch, Ilia J.; Ruszala, Elizabeth M.; Hetherington, Alistair M.; Beerling, David J.</p> <p>2012-01-01</p> <p>In response to short-term fluctuations in atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>, ca, plants adjust leaf diffusive conductance to <span class="hlt">CO</span><span class="hlt">2</span>, gc, via feedback regulation of stomatal aperture as part of a mechanism for optimizing <span class="hlt">CO</span><span class="hlt">2</span> uptake with respect to water loss. The operational range of this elaborate control mechanism is determined by the maximum diffusive conductance to <span class="hlt">CO</span><span class="hlt">2</span>, 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 <span class="hlt">increases</span> in S, guard cell nucleus size and average apparent 1C DNA amount in epidermal cell nuclei with <span class="hlt">increasing</span> ca, suggesting that stomatal and leaf adaptation to ca is linked to genome scaling. PMID:22232765</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22232765','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22232765"><span>Physiological framework for adaptation of stomata to <span class="hlt">CO</span><span class="hlt">2</span> from glacial to future <span class="hlt">concentrations</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Franks, Peter J; Leitch, Ilia J; Ruszala, Elizabeth M; Hetherington, Alistair M; Beerling, David J</p> <p>2012-02-19</p> <p>In response to short-term fluctuations in atmospheric <span class="hlt">CO</span>(<span class="hlt">2</span>) <span class="hlt">concentration</span>, c(a), plants adjust leaf diffusive conductance to <span class="hlt">CO</span>(<span class="hlt">2</span>), g(c), via feedback regulation of stomatal aperture as part of a mechanism for optimizing <span class="hlt">CO</span>(<span class="hlt">2</span>) uptake with respect to water loss. The operational range of this elaborate control mechanism is determined by the maximum diffusive conductance to <span class="hlt">CO</span>(<span class="hlt">2</span>), g(c(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 c(a), plants alter g(c(max)) in the direction of the short-term feedback response of g(c) to c(a) via adjustment of S and D. This adaptive feedback response to c(a), 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 <span class="hlt">increases</span> in S, guard cell nucleus size and average apparent 1C DNA amount in epidermal cell nuclei with <span class="hlt">increasing</span> c(a), suggesting that stomatal and leaf adaptation to c(a) is linked to genome scaling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19500129','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19500129"><span>Productivity and community structure of ectomycorrhizal fungal sporocarps under <span class="hlt">increased</span> atmospheric <span class="hlt">CO</span><span class="hlt">2</span> and O3.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Andrew, Carrie; Lilleskov, Erik A</p> <p>2009-08-01</p> <p>Sporocarp production is essential for ectomycorrhizal fungal recombination and dispersal, which influences fungal community dynamics. <span class="hlt">Increasing</span> atmospheric carbon dioxide (<span class="hlt">CO</span><span class="hlt">2</span>) and ozone (O3) affect host plant carbon gain and allocation, which may in turn influence ectomycorrhizal sporocarp production if the carbon available to the ectomycorrhizal fungus is dependant upon the quantity of carbon assimilated by the host. We measured sporocarp production of ectomycorrhizal fungi over 4 years at the Aspen FACE (free air <span class="hlt">CO</span><span class="hlt">2</span> enrichment) site, which corresponded to stand ages seven to 10 years. Total mean sporocarp biomass was greatest under elevated <span class="hlt">CO</span><span class="hlt">2</span>, regardless of O3 <span class="hlt">concentration</span>, while it was generally lowest under elevated O3 with ambient <span class="hlt">CO</span><span class="hlt">2</span>. Community composition differed significantly among the treatments, with less difference in the final year of the study. Whether this convergence was due to succession or environmental factors is uncertain. <span class="hlt">CO</span><span class="hlt">2</span> and O3 affect ectomycorrhizal sporocarp productivity and community composition, with likely effects on dispersal, colonization and sporocarp-dependent food webs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4840274','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4840274"><span>Diel Variation in Gene Expression of the <span class="hlt">CO</span><span class="hlt">2</span>-<span class="hlt">Concentrating</span> Mechanism during a Harmful Cyanobacterial Bloom</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sandrini, Giovanni; Tann, Robert P.; Schuurmans, J. Merijn; van Beusekom, Sebastiaan A. M.; Matthijs, Hans C. P.; Huisman, Jef</p> <p>2016-01-01</p> <p>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 <span class="hlt">CO</span><span class="hlt">2</span>-<span class="hlt">concentrating</span> mechanism (CCM) and other selected genes of the harmful cyanobacterium Microcystis aeruginosa. Photosynthetic activity of the cyanobacterial bloom depleted the dissolved <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>, raised pH to 10, and caused large diel fluctuations in the bicarbonate and O2 <span class="hlt">concentration</span>. 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 <span class="hlt">increased</span> at first daylight and was negatively correlated with the bicarbonate <span class="hlt">concentration</span>. In contrast, genes of the two <span class="hlt">CO</span><span class="hlt">2</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18453445','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18453445"><span>Responses to iron limitation in Hordeum vulgare L. as affected by the atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Haase, S; Rothe, A; Kania, A; Wasaki, J; Römheld, V; Engels, C; Kandeler, E; Neumann, G</p> <p>2008-01-01</p> <p>Elevated atmospheric <span class="hlt">CO</span><span class="hlt">2</span> treatments stimulated biomass production in Fe-sufficient and Fe-deficient barley plants, both in hydroponics and in soil culture. Root/shoot biomass ratio was <span class="hlt">increased</span> in severely Fe-deficient plants grown in hydroponics but not under moderate Fe limitation in soil culture. Significantly <span class="hlt">increased</span> biomass production in high <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">increased</span> by 74% in response to elevated <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">concentrations</span> above the critical level for Fe deficiency, determined at final harvest for soil-grown barley plants, even without additional Fe supply. However, extremely low <span class="hlt">concentrations</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> may indicate an <span class="hlt">increased</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.V53B2833S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V53B2833S"><span>Development of new measuring technique using sound velocity for <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> in Cameroonian volcanic lakes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sanemasa, M.; Saiki, K.; Kaneko, K.; Ohba, T.; Kusakabe, M.; Tanyileke, G.; Hell, J.</p> <p>2012-12-01</p> <p>1. Introduction Limnic eruptions at Lakes Monoun and Nyos in Cameroon, which are sudden degassing of magmatic <span class="hlt">CO</span><span class="hlt">2</span> dissolved in the lake water, occurred in 1984 and 1986, respectively. The disasters killed about 1800 people around the lakes. Because of ongoing <span class="hlt">CO</span><span class="hlt">2</span> accumulation in the bottom water of the lakes, tragedy of limnic eruptions will possibly occur again. To prevent from further disasters, artificial degassing of <span class="hlt">CO</span><span class="hlt">2</span> from the lake waters has been undergoing. Additionally, <span class="hlt">CO</span><span class="hlt">2</span> monitoring of the lake waters is needed. Nevertheless, <span class="hlt">CO</span><span class="hlt">2</span> measurement is done only once or twice a year because current methods of <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">concentration</span> using sound velocity has been proposed (Kleis and Sanchez, 1990). This method allows us to evaluate solute <span class="hlt">concentration</span> fast. We applied the method to dissolved <span class="hlt">CO</span><span class="hlt">2</span> and examined the correlation between sound velocity and <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> in laboratory experiment. Furthermore, using the obtained correlation, we tried to estimate the <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> of waters in the Cameroonian lakes. 2. Laboratory experiment We examined the correlation between sound velocity and <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>. A profiler (Minos X, made by AML oceanography) and pure water were packed in cylindrical stainless vessel and high-pressure <span class="hlt">CO</span><span class="hlt">2</span> 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. <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> was calculated by Henry's law. The result indicated that the change of sound velocity [m s-1] is proportional to <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> [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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170003497&hterms=concentration&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dconcentration','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170003497&hterms=concentration&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dconcentration"><span>Interactions Between Temperature and Intercellular <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">Concentration</span> in Controlling Leaf Isoprene Emission Rates</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Monson, Russell K.; Neice, Amberly A.; Trahan, Nicole A.; Shiach, Ian; McCorkel, Joel T.; Moore, David J. P.</p> <p>2016-01-01</p> <p>Plant isoprene emissions have been linked to several reaction pathways involved in atmospheric photochemistry. Evidence exists from a limited set of past observations that isoprene emission rate (I(sub s)) decreases as a function of <span class="hlt">increasing</span> atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>, and that <span class="hlt">increased</span> temperature suppresses the <span class="hlt">CO</span><span class="hlt">2</span> effect. We studied interactions between intercellular <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> (C(sub I)) and temperature as they affect I(sub s) in field-grown hybrid poplar trees in one of the warmest climates on earth - the Sonoran Desert of the southwestern United States. We observed an unexpected midsummer down regulation of I(sub s) despite the persistence of relatively high temperatures. High temperature suppression of the I(sub s):C(sub I) relation occurred at all times during the growing season, but sensitivity of I(sub s) to <span class="hlt">increased</span> C(sub I) was greatest during the midsummer period when I(subs) was lowest. We interpret the seasonal down regulation of I(sub s) and <span class="hlt">increased</span> sensitivity of I(sub s) to C(sub I) as being caused by weather changes associated with the onset of a regional monsoon system. Our observations on the temperature suppression of the I(sub s):C(sub I) relation are best explained by the existence of a small pool of chloroplastic inorganic phosphate, balanced by several large, connected metabolic fluxes, which together, determine the C(sub I) and temperature dependencies of phosphoenolpyruvate import into the chloroplast.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27352095','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27352095"><span>Interactions between temperature and intercellular <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> in controlling leaf isoprene emission rates.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Monson, Russell K; Neice, Amberly A; Trahan, Nicole A; Shiach, Ian; McCorkel, Joel T; Moore, David J P</p> <p>2016-11-01</p> <p>Plant isoprene emissions have been linked to several reaction pathways involved in atmospheric photochemistry. Evidence exists from a limited set of past observations that isoprene emission rate (Is ) decreases as a function of <span class="hlt">increasing</span> atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>, and that <span class="hlt">increased</span> temperature suppresses the <span class="hlt">CO</span><span class="hlt">2</span> effect. We studied interactions between intercellular <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> (Ci ) and temperature as they affect Is in field-grown hybrid poplar trees in one of the warmest climates on earth - the Sonoran Desert of the southwestern United States. We observed an unexpected midsummer downregulation of Is despite the persistence of relatively high temperatures. High temperature suppression of the Is :Ci relation occurred at all times during the growing season, but sensitivity of Is to <span class="hlt">increased</span> Ci was greatest during the midsummer period when Is was lowest. We interpret the seasonal downregulation of Is and <span class="hlt">increased</span> sensitivity of Is to Ci as being caused by weather changes associated with the onset of a regional monsoon system. Our observations on the temperature suppression of the Is :Ci relation are best explained by the existence of a small pool of chloroplastic inorganic phosphate, balanced by several large, connected metabolic fluxes, which together, determine the Ci and temperature dependencies of phosphoenolpyruvate import into the chloroplast. © 2016 John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=336166','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=336166"><span>Using FACE systems to screen wheat cultivars for yield <span class="hlt">increases</span> at elevated <span class="hlt">CO</span><span class="hlt">2</span></span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>Because of continuing <span class="hlt">increases</span> in atmospheric <span class="hlt">CO</span><span class="hlt">2</span>, identifying cultivars of crops with larger yield <span class="hlt">increases</span> at elevated <span class="hlt">CO</span><span class="hlt">2</span> may provide an avenue to <span class="hlt">increase</span> crop yield potential in future climates. Free-air <span class="hlt">CO</span><span class="hlt">2</span> enrichment (FACE) systems have most often been used with multiple replications of ea...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17966516','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17966516"><span>Effects of elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> on growth and water usage of tomato seedlings under different ammonium/nitrate ratios.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Juan; Zhou, Jian-Min; Duan, Zeng-Qiang</p> <p>2007-01-01</p> <p><span class="hlt">Increasing</span> atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> is generally expected to enhance photosynthesis and growth of agricultural C3 vegetable crops, and therefore results in an <span class="hlt">increase</span> in crop yield. However, little is known about the combined effect of elevated <span class="hlt">CO</span><span class="hlt">2</span> and N species on plant growth and development. Two growth-chamber experiments were conducted to determine the effects of NH4+/NO3- ratio and elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> on the physiological development and water use of tomato seedlings. Tomato was grown for 45 d in containers with nutrient solutions varying in NH4+/NO3- ratios and <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> in growth chambers. Results showed that plant height, stem thickness, total dry weight, dry weight of the leaves, stems and roots, G value (total plant dry weight/seedling days), chlorophyll content, photosynthetic rate, leaf-level and whole plant-level water use efficiency and cumulative water consumption of tomato seedlings were <span class="hlt">increased</span> with <span class="hlt">increasing</span> proportion of NO3- in nutrient solutions in the elevated <span class="hlt">CO</span><span class="hlt">2</span> treatment. Plant biomass, plant height, stem thickness and photosynthetic rate were 67%, 22%, 24% and 55% higher at elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> than at ambient <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>, depending on the values of NH4+/NO3- ratio. These results indicated that elevating <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> did not mitigate the adverse effects of 100% NH4(+)-N (in nutrient solution) on the tomato seedlings. At both <span class="hlt">CO</span><span class="hlt">2</span> levels, NH4+/NO3- ratios of nutrient solutions strongly influenced almost every measure of plant performance, and nitrate-fed plants attained a greater biomass production, as compared to ammonium-fed plants. These phenomena seem to be related to the coordinated regulation of photosynthetic rate and cumulative water consumption of tomato seedlings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14503447','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14503447"><span>Short-term <span class="hlt">concentration</span> of <span class="hlt">CO</span><span class="hlt">2</span> in the ambient air of Nagpur city.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Manuel, Jovita A; Gajghate, D G; Hasan, M Z; Singh, R N</p> <p>2002-07-01</p> <p>Carbon dioxide <span class="hlt">concentration</span> is an index of total amount of combustion and natural ventilation in an urban environment and therefore required more careful attention for assessment of <span class="hlt">CO</span><span class="hlt">2</span> level in air environment. First time, an attempt was made to monitor <span class="hlt">CO</span><span class="hlt">2</span> levels in Ambient Air of Nagpur during August 2001-December 2001 at Industrial, Commercial and Residential sites. The largest amount of <span class="hlt">CO</span><span class="hlt">2</span> occurred at night due to darkness which depresses the photosynthesis to its lowest level. The lowest <span class="hlt">concentration</span> of <span class="hlt">CO</span><span class="hlt">2</span> was showed in afternoon hours when photosynthesis is at its maximum. The average <span class="hlt">concentration</span> of <span class="hlt">CO</span><span class="hlt">2</span> was found to be 361, 366 and 339 ppm at Industrial, Commercial and Industrial sites respectively. This generation of database of ambient <span class="hlt">CO</span><span class="hlt">2</span> will help to formulate the strategy for prevention of global warming phenomenon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24316065','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24316065"><span>Impact of elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> on dynamics of leaf photosynthesis in Fagus sylvatica is modulated by sky conditions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Urban, Otmar; Klem, Karel; Holišová, Petra; Šigut, Ladislav; Šprtová, Mirka; Teslová-Navrátilová, Petra; Zitová, Martina; Špunda, Vladimír; Marek, Michal V; Grace, John</p> <p>2014-02-01</p> <p>It has been suggested that atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> and frequency of cloud cover will <span class="hlt">increase</span> in future. It remains unclear, however, how elevated <span class="hlt">CO</span><span class="hlt">2</span> 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) <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> were studied under contrasting sky conditions. EC stimulated the daily sum of fixed <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014BGeo...11..735S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014BGeo...11..735S"><span>Can seasonal and interannual variation in landscape <span class="hlt">CO</span><span class="hlt">2</span> fluxes be detected by atmospheric observations of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> made at a tall tower?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smallman, T. L.; Williams, M.; Moncrieff, J. B.</p> <p>2014-02-01</p> <p>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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> from a tall tower in Scotland, UK. Ecosystem-specific tracers of net <span class="hlt">CO</span><span class="hlt">2</span> uptake and net <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> at the tall tower (R2 = 0.67, rmse = 3.5 ppm, bias = 0.58 ppm). Atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> 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 <span class="hlt">increase</span> in the seasonal bias between WRF-SPA and observations. Ecosystem-specific tracers of <span class="hlt">CO</span><span class="hlt">2</span> exchange indicate that the <span class="hlt">increased</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3530562','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3530562"><span><span class="hlt">Increased</span> Feeding and Nutrient Excretion of Adult Antarctic Krill, Euphausia superba, Exposed to Enhanced Carbon Dioxide (<span class="hlt">CO</span><span class="hlt">2</span>)</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Saba, Grace K.; Schofield, Oscar; Torres, Joseph J.; Ombres, Erica H.; Steinberg, Deborah K.</p> <p>2012-01-01</p> <p>Ocean acidification has a wide-ranging potential for impacting the physiology and metabolism of zooplankton. Sufficiently elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> can alter internal acid-base balance, compromising homeostatic regulation and disrupting internal systems ranging from oxygen transport to ion balance. We assessed feeding and nutrient excretion rates in natural populations of the keystone species Euphausia superba (Antarctic krill) by conducting a <span class="hlt">CO</span><span class="hlt">2</span> perturbation experiment at ambient and elevated atmospheric <span class="hlt">CO</span><span class="hlt">2</span> levels in January 2011 along the West Antarctic Peninsula (WAP). Under elevated <span class="hlt">CO</span><span class="hlt">2</span> conditions (∼672 ppm), ingestion rates of krill averaged 78 µg C individual−1 d−1 and were 3.5 times higher than krill ingestion rates at ambient, present day <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>. Additionally, rates of ammonium, phosphate, and dissolved organic carbon (DOC) excretion by krill were 1.5, 1.5, and 3.0 times higher, respectively, in the high <span class="hlt">CO</span><span class="hlt">2</span> treatment than at ambient <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>. Excretion of urea, however, was ∼17% lower in the high <span class="hlt">CO</span><span class="hlt">2</span> treatment, suggesting differences in catabolic processes of krill between treatments. Activities of key metabolic enzymes, malate dehydrogenase (MDH) and lactate dehydrogenase (LDH), were consistently higher in the high <span class="hlt">CO</span><span class="hlt">2</span> treatment. The observed shifts in metabolism are consistent with <span class="hlt">increased</span> physiological costs associated with regulating internal acid-base equilibria. This represents an additional stress that may hamper growth and reproduction, which would negatively impact an already declining krill population along the WAP. PMID:23300621</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007BGeo....4..481R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007BGeo....4..481R"><span>Assessing the potential long-term <span class="hlt">increase</span> of oceanic fossil fuel <span class="hlt">CO</span><span class="hlt">2</span> uptake due to <span class="hlt">CO</span><span class="hlt">2</span>-calcification feedback</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ridgwell, A.; Zondervan, I.; Hargreaves, J. C.; Bijma, J.; Lenton, T. M.</p> <p>2007-07-01</p> <p>Plankton manipulation experiments exhibit a wide range of sensitivities of biogenic calcification to simulated anthropogenic acidification of the ocean, with the "lab rat" of planktic calcifiers, Emiliania huxleyi apparently not representative of calcification generally. We assess the implications of this observational uncertainty by creating an ensemble of realizations of an Earth system model that encapsulates a comparable range of uncertainty in calcification response to ocean acidification. We predict that a substantial reduction in marine carbonate production is possible in the future, with enhanced ocean <span class="hlt">CO</span><span class="hlt">2</span> sequestration across the model ensemble driving a 4-13% reduction in the year 3000 atmospheric fossil fuel <span class="hlt">CO</span><span class="hlt">2</span> burden. Concurrent changes in ocean circulation and surface temperatures in the model contribute about one third to the <span class="hlt">increase</span> in <span class="hlt">CO</span><span class="hlt">2</span> uptake. We find that uncertainty in the predicted strength of <span class="hlt">CO</span><span class="hlt">2</span>-calcification feedback seems to be dominated by the assumption as to which species of calcifier contribute most to carbonate production in the open ocean.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930073156&hterms=CO2+concentrations&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DCO2%2Bconcentrations','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930073156&hterms=CO2+concentrations&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DCO2%2Bconcentrations"><span>The relationship of global green leaf biomass to atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Tucker, C. J.; Fung, Inez Y.; Keeling, C. D.; Gammon, R. H.</p> <p>1985-01-01</p> <p>Advanced very high resolution radiometer data from NOAA's polar orbiting meteorological satellite have been obtained globally for a 21 month period, processed to produce a green leaf biomass spectral vegetative index for the entire terrestrial surface by month, zonally aggregated by latitude, and compared to atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> from observing stations. A strong inverse association was found between the monthly Pt. Barrow <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> and the vegetation index measurements from 50 deg N to 80 deg N, between the monthly Mauna Loa <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> and the vegetation index measurements from 10 deg N to 30 deg N, 10 deg N to 80 deg N, and the global total, and between the globally averaged <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> and the globally averaged vegetation index. No relationships between atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> and the vegetative index measurements from any latitude zone or combinations of zones were found for the South Pole station.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=159575','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=159575"><span><span class="hlt">CO</span><span class="hlt">2</span> Uptake and Electron Transport Rates in Wild-Type and a Starchless Mutant of Nicotiana sylvestris (The Role and Regulation of Starch Synthesis at Saturating <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">Concentrations</span>).</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Eichelmann, H.; Laisk, A.</p> <p>1994-01-01</p> <p><span class="hlt">CO</span><span class="hlt">2</span> uptake rate, chlorophyll fluorescence, and 830-nm absorbance were measured in wild-type (wt) Nicotiana sylvestris (Speg. et Comes) and starchless mutant NS 458 leaves at different light intensities and <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>. Initial slopes of the relationships between <span class="hlt">CO</span><span class="hlt">2</span> uptake and light and <span class="hlt">CO</span><span class="hlt">2</span> were similar, but the maximum rate at <span class="hlt">CO</span><span class="hlt">2</span> and light saturation was only 30% in the mutant compared with the wt. O2 enhancement of photosynthesis at <span class="hlt">CO</span><span class="hlt">2</span> and light saturation was relatively much greater in the mutant than in the wt. In 21% O2, the electron transport rate (ETR) calculated from fluorescence peaked near the beginning of the <span class="hlt">CO</span><span class="hlt">2</span> saturation of photosynthesis. With the further <span class="hlt">increase</span> of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> ETR remained nearly constant or declined a little in the wt but drastically declined in the mutant. Absorbance measurements at 830 nm indicated photosystem I acceptor side reduction in both plants at saturating <span class="hlt">CO</span><span class="hlt">2</span> and light. Assimilatory charge (postillumination <span class="hlt">CO</span><span class="hlt">2</span> uptake) measurements indicated trapping of chloroplast inorganic phosphate, supposedly in hexose phosphates, in the mutant. It is concluded that starch synthesis gradually substitutes for photorespiration as electron acceptor with <span class="hlt">increasing</span> <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> in the wt but not in the mutant. It is suggested that starch synthesis is co-controlled by the activity of the chloroplast fructose bisphosphatase. PMID:12232360</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SPIE.9810E..1XA','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9810E..1XA"><span>Laser detection of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> in human breath at various diseases</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ageev, Boris G.; Nikiforova, Olga Y.</p> <p>2015-12-01</p> <p>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 <span class="hlt">CO</span><span class="hlt">2</span> laser. Healthy persons and patients with various diseases were studied. For determination of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> in exhalation samples gas analyzer was calibrated by reference gaseous mixture <span class="hlt">CO</span><span class="hlt">2</span>-N2. It was obtained that <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> values in human breath of healthy persons are greater than that of patients with various diseases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22882384','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22882384"><span>Effects of elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> and water deficit on fructan metabolism in Viguiera discolor Baker.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Oliveira, V F; Silva, E A; Zaidan, L B P; Carvalho, M A M</p> <p>2013-05-01</p> <p>Elevated [<span class="hlt">CO</span><span class="hlt">2</span> ] is suggested to mitigate the negative effects of water stress in plants; however responses vary among species. Fructans are recognised as protective compounds against drought and other stresses, as well as having a role as reserve carbohydrates. We analysed the combined effects of elevated [<span class="hlt">CO</span><span class="hlt">2</span> ] and water deficit on fructan metabolism in the Cerrado species Viguiera discolor Baker. Plants were cultivated for 18 days in open-top chambers (OTC) under ambient (∼380 ppm), and high (∼760 ppm) [<span class="hlt">CO</span><span class="hlt">2</span> ]. In each OTC, plants were submitted to three treatments: (i) daily watering (control), (ii) withholding water (WS) for 18 days and (iii) re-watering (RW) on day 11. Analyses were performed at time 0 and days 5, 8, 11, 15 and 18. High [<span class="hlt">CO</span><span class="hlt">2</span> ] <span class="hlt">increased</span> photosynthesis in control plants and <span class="hlt">increased</span> water use efficiency in WS plants. The decline in soil water content was more distinct in WS 760 (WS under 760 ppm), although the leaf and tuberous root water status was similar to WS 380 plants (WS under 380 ppm). Regarding fructan active enzymes, 1-SST activity decreased in WS plants in both <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>, a result consistent with the decline in photosynthesis and, consequently, in substrate availability. Under WS and both [<span class="hlt">CO</span><span class="hlt">2</span> ] treatments, 1-FFT and 1-FEH seemed to act in combination to generate osmotically active compounds and thus overcome water deficit. The proportion of hexoses to sucrose, 1-kestose and nystose (SKN) was higher in WS plants. In WS 760, this <span class="hlt">increase</span> was higher than in WS 380, and was not accompanied by decreases in SKN at the beginning of the treatment, as observed in WS 380 plants. These results suggest that the higher [<span class="hlt">CO</span><span class="hlt">2</span> ] in the atmosphere contributed to maintain, for a longer period, the pool of hexoses and of low DP fructans, favouring the maintenance of the water status and plant survival under drought. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24752528','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24752528"><span>Carbon allocation and element composition in four Chlamydomonas mutants defective in genes related to the <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrating</span> mechanism.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Memmola, Francesco; Mukherjee, Bratati; Moroney, James V; Giordano, Mario</p> <p>2014-09-01</p> <p>Four mutants of Chlamydomonas reinhardtii with defects in different components of the <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrating</span> mechanism (CCM) or in Rubisco activase were grown autotrophically at high p<span class="hlt">CO</span><span class="hlt">2</span> and then transferred to low p<span class="hlt">CO</span><span class="hlt">2</span>, in order to study the role of different components of the CCM on carbon allocation and elemental composition. To study carbon allocation, we measured the relative size of the main organic pools by Fourier Transform Infrared spectroscopy. Total reflection X-ray fluorescence was used to analyze the elemental composition of algal cells. Our data show that although the organic pools <span class="hlt">increased</span> their size at high <span class="hlt">CO</span><span class="hlt">2</span> in all strains, their stoichiometry was highly homeostatic, i.e., the ratios between carbohydrates and proteins, lipid and proteins, and carbohydrates and lipids, did not change significantly. The only exception was the wild-type 137c, in which proteins decreased relative to carbohydrates and lipids, when the cells were transferred to low <span class="hlt">CO</span><span class="hlt">2</span>. It is noticeable that the two wild types used in this study responded differently to the transition from high to low <span class="hlt">CO</span><span class="hlt">2</span>. Malfunctions of the CCM influenced the <span class="hlt">concentration</span> of several elements, somewhat altering cell elemental stoichiometry: especially the C/P and N/P ratios changed appreciably in almost all strains as a function of the growth <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>, except in 137c and the Rubisco activase mutant rca1. In strain cia3, defective in the lumenal carbonic anhydrase (CA), the cell quotas of P, S, Ca, Mn, Fe, and Zn were about 5-fold higher at low <span class="hlt">CO</span><span class="hlt">2</span> than at high <span class="hlt">CO</span><span class="hlt">2</span>. A Principle Components Analysis showed that, mostly because of its elemental composition, cia3 behaved in a substantially different way from all other strains, at low <span class="hlt">CO</span><span class="hlt">2</span>. The lumenal CA thus plays a crucial role, not only for the correct functioning of the CCM, but also for element utilization. Not surprisingly, growth at high <span class="hlt">CO</span><span class="hlt">2</span> attenuated differences among strains.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23947023','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23947023"><span>[Effects of simulated elevation of atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> on the physiological features of spring phytoplankton in Taihu Lake].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhao, Xu-Hui; Tang, Long-Sheng; Shi, Xiao-Li; Yang, Zhou; Kong, Fan-Xiang</p> <p>2013-06-01</p> <p>To disclose the impact of different <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> (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 <span class="hlt">CO</span><span class="hlt">2</span> elevation would significantly alter the pH value and carbonate chemical environments of Taihu Lake, resulting in weakening the advantages of carbon <span class="hlt">concentrating</span> mechanism (CCM) of phytoplankton. Phytoplankton in Taihu Lake tended to use more dissolved <span class="hlt">CO</span><span class="hlt">2</span> (<span class="hlt">CO</span><span class="hlt">2</span>, aq) due to the deliberate <span class="hlt">CO</span><span class="hlt">2</span> sequestration under the high <span class="hlt">CO</span><span class="hlt">2</span> level treatment. When atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> doubles at the end of century, the maximum growth rate constant of phytoplankton (U(max)), NPP, chlorophyll a (Chl-a)-specific NPP would <span class="hlt">increase</span> by 63.1%, 69.6% and 33.8%, respectively. Atmospheric <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> elevation, as phytoplankton cells assimilated more C and N, but less P under the treatment of high <span class="hlt">CO</span><span class="hlt">2</span> level. Our results indicated the enhanced <span class="hlt">CO</span><span class="hlt">2</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA....13546C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA....13546C"><span>Carbon Balance at Landscape Level inferred fromTower <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">Concentration</span> Measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, J. M.; Chen, B.; Higuchi, K.; Chan, D.; Shashkov, A.; Lin, H.; Liu, J.</p> <p>2003-04-01</p> <p>Terrestrial carbon sinks are considerable in the global carbon budget, but the accumulation of carbon in terrestrial ecosystems is very small (~0.2% per year) relative to the total carbon stocks in forests. Currently, eddy-covariance instruments mounted on towers are the only reliable means to measure carbon balance of a land surface, albeit limited to small areas and not free of caveats. In our quest of understanding the collective performance of ecosystems under the changing climate, it is highly desirable to have the ability to acquire carbon cycle information for large areas (landscape) consisting of patches of different ecosystems. For this purpose we explored methodologies of inferring carbon cycle information from tower <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> measurements affected by large areas (100-10000 km2). An ecosystem model named Boreal Ecosystem Productivity Simulator (BEPS) is coupled with a carbon-specific Vertical Diffusion Scheme (VDS) in order to decipher temporal variations in <span class="hlt">CO</span><span class="hlt">2</span> for landscape-level photosynthesis and respiration information. The coupled BEPS-VDS is applied to a unique 9-year (1990-2000 with 1997-8 missing data) 5-minute <span class="hlt">CO</span><span class="hlt">2</span> record measured on a 40-m tower over boreal forests near Fraserdale, Ontario, Canada. Over the period, the mean diurnal amplitude of the measured <span class="hlt">CO</span><span class="hlt">2</span> at 40 m <span class="hlt">increased</span> by 5.58 ppmv, or 28% in the growing season. The <span class="hlt">increase</span> in nighttime ecosystem respiration, causing the <span class="hlt">increase</span> in the daily maximum <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>, was responsible for 65% of the <span class="hlt">increase</span> in the diurnal amplitude, i.e., 3.61 ppmv, corresponding to an <span class="hlt">increase</span> in the mean daily air temperature by about 2.77 degC and precipitation by 5% over the same period. The rest (35%) is explained by the <span class="hlt">increase</span> in ecosystem daytime photosynthesis, causing the decrease in the daily minimum <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>. As the nighttime stable boundary layer (SBL) (270-560 m) was much shallower than the daytime convective boundary layer (CBL) (1000-1600 m), the <span class="hlt">increase</span> in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170005574&hterms=basics+change+state&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dbasics%2Bchange%2Bstate','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170005574&hterms=basics+change+state&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dbasics%2Bchange%2Bstate"><span>Changes in the Structure and Propagation of the MJO with <span class="hlt">Increasing</span> <span class="hlt">CO</span><span class="hlt">2</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Adames, Angel F.; Kim, Daehyun; Sobel, Adam H.; Del Genio, Anthony; Wu, Jingbo</p> <p>2017-01-01</p> <p>Changes in the Madden-Julian Oscillation (MJO) with <span class="hlt">increasing</span> <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> are examined using the Goddard Institute for Space Studies Global Climate Model (GCM). Four simulations performed with fixed <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> of 0.5, 1, 2 and 4 times pre-industrial levels using the GCM coupled with a mixed layer ocean model are analyzed in terms of the basic state, rainfall and moisture variability, and the structure and propagation of the MJO.The GCM simulates basic state changes associated with <span class="hlt">increasing</span> <span class="hlt">CO</span><span class="hlt">2</span> that are consistent with results from earlier studies: column water vapor <span class="hlt">increases</span> at approximately 7.1% K(exp -1), precipitation also <span class="hlt">increases</span> but at a lower rate (approximately 3% K(exp -1)), and column relative humidity shows little change. Moisture and rainfall variability intensify with warming. Total moisture and rainfall variability <span class="hlt">increases</span> at a rate that is similar to that of the mean state change. The intensification is faster in the MJO-related anomalies than in the total anomalies, though the ratio of the MJO band variability to its westward counterpart <span class="hlt">increases</span> at a much slower rate. On the basis of linear regression analysis and space-time spectral analysis, it is found that the MJO exhibits faster eastward propagation, faster westward energy dispersion, a larger zonal scale and deeper vertical structure in warmer climates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Natur.515..398G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Natur.515..398G"><span>Direct human influence on atmospheric <span class="hlt">CO</span><span class="hlt">2</span> seasonality from <span class="hlt">increased</span> cropland productivity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gray, Josh M.; Frolking, Steve; Kort, Eric A.; Ray, Deepak K.; Kucharik, Christopher J.; Ramankutty, Navin; Friedl, Mark A.</p> <p>2014-11-01</p> <p>Ground- and aircraft-based measurements show that the seasonal amplitude of Northern Hemisphere atmospheric carbon dioxide (<span class="hlt">CO</span><span class="hlt">2</span>) <span class="hlt">concentrations</span> has <span class="hlt">increased</span> by as much as 50 per cent over the past 50 years. This <span class="hlt">increase</span> has been linked to changes in temperate, boreal and arctic ecosystem properties and processes such as enhanced photosynthesis, <span class="hlt">increased</span> heterotrophic respiration, and expansion of woody vegetation. However, the precise causal mechanisms behind the observed changes in atmospheric <span class="hlt">CO</span><span class="hlt">2</span> seasonality remain unclear. Here we use production statistics and a carbon accounting model to show that <span class="hlt">increases</span> in agricultural productivity, which have been largely overlooked in previous investigations, explain as much as a quarter of the observed changes in atmospheric <span class="hlt">CO</span><span class="hlt">2</span> seasonality. Specifically, Northern Hemisphere extratropical maize, wheat, rice, and soybean production grew by 240 per cent between 1961 and 2008, thereby <span class="hlt">increasing</span> the amount of net carbon uptake by croplands during the Northern Hemisphere growing season by 0.33 petagrams. Maize alone accounts for two-thirds of this change, owing mostly to agricultural intensification within <span class="hlt">concentrated</span> production zones in the midwestern United States and northern China. Maize, wheat, rice, and soybeans account for about 68 per cent of extratropical dry biomass production, so it is likely that the total impact of <span class="hlt">increased</span> agricultural production exceeds the amount quantified here.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28943996','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28943996"><span>Changes in the structure and propagation of the MJO with <span class="hlt">increasing</span> <span class="hlt">CO</span><span class="hlt">2</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Adames, Ángel F; Kim, Daehyun; Sobel, Adam H; Del Genio, Anthony; Wu, Jingbo</p> <p>2017-06-01</p> <p>Changes in the Madden-Julian Oscillation (MJO) with <span class="hlt">increasing</span> <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> are examined using the Goddard Institute for Space Studies Global Climate Model (GCM). Four simulations performed with fixed <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> of 0.5, 1, 2, and 4 times preindustrial levels using the GCM coupled with a mixed layer ocean model are analyzed in terms of the basic state, rainfall, moisture and zonal wind variability, and the structure and propagation of the MJO. The GCM simulates basic state changes associated with <span class="hlt">increasing</span> <span class="hlt">CO</span><span class="hlt">2</span> that are consistent with results from earlier studies: column water vapor <span class="hlt">increases</span> at ∼7.1% K(-1), precipitation also <span class="hlt">increases</span> but at a lower rate (∼3% K(-1)), and column relative humidity shows little change. Moisture and rainfall variability intensify with warming while zonal wind variability shows little change. Total moisture and rainfall variability <span class="hlt">increases</span> at a rate this is similar to that of the mean state change. The intensification is faster in the MJO-related anomalies than in the total anomalies, though the ratio of the MJO band variability to its westward counterpart <span class="hlt">increases</span> at a much slower rate. On the basis of linear regression analysis and space-time spectral analysis, it is found that the MJO exhibits faster eastward propagation, faster westward energy dispersion, a larger zonal scale, and deeper vertical structure in warmer climates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28444330','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28444330"><span>Progress and challenges of engineering a biophysical <span class="hlt">CO</span><span class="hlt">2</span>-<span class="hlt">concentrating</span> mechanism into higher plants.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rae, Benjamin D; Long, Benedict M; Förster, Britta; Nguyen, Nghiem D; Velanis, Christos N; Atkinson, Nicky; Hee, Wei Yih; Mukherjee, Bratati; Price, G Dean; McCormick, Alistair J</p> <p>2017-06-01</p> <p>Growth and productivity in important crop plants is limited by the inefficiencies of the C3 photosynthetic pathway. Introducing <span class="hlt">CO</span><span class="hlt">2</span>-<span class="hlt">concentrating</span> mechanisms (CCMs) into C3 plants could overcome these limitations and lead to <span class="hlt">increased</span> yields. Many unicellular microautotrophs, such as cyanobacteria and green algae, possess highly efficient biophysical CCMs that <span class="hlt">increase</span> <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> around the primary carboxylase enzyme, Rubisco, to enhance <span class="hlt">CO</span><span class="hlt">2</span> assimilation rates. Algal and cyanobacterial CCMs utilize distinct molecular components, but share several functional commonalities. Here we outline the recent progress and current challenges of engineering biophysical CCMs into C3 plants. We review the predicted requirements for a functional biophysical CCM based on current knowledge of cyanobacterial and algal CCMs, the molecular engineering tools and research pipelines required to translate our theoretical knowledge into practice, and the current challenges to achieving these goals. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28472267','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28472267"><span>The Influence of Elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">Concentration</span> on the Fitness Traits of Frankliniella occidentalis and Frankliniella intonsa (Thysanoptera: Thripidae).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>ShuQi, He; Ying, Lin; Lei, Qian; ZhiHua, Li; Chao, Xi; Lu, Yang; FuRong, Gui</p> <p>2017-06-01</p> <p>Development and fecundity were investigated in an invasive alien thrips species, Frankliniella occidentalis (Pergande), and a related native species, Frankliniella intonsa (Trybom), under high <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>. Results show that the two thrips species reacted differently toward elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>. Developmental duration decreased significantly (11.93%) in F. occidentalis at the <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> of 800 µl/liter; survival rate of all stages also significantly <span class="hlt">increased</span> (e.g., survival rate of first instar <span class="hlt">increased</span> 17.80%), adult longevity of both female and male extended (e.g., female <span class="hlt">increased</span> 2.02 d on average), and both fecundity and daily eggs laid per female were higher at a <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> of 800 µl/liter than at 400 µl/liter. Developmental duration of F. intonsa decreased, insignificantly, at a <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> of 800 µl/liter. Unlike F. occidentalis, survival rate of F. intonsa declined considerably at higher <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> level (e.g., survival rate of first instar decreased 19.70%), adult longevity of both female and male curtailed (e.g., female reduced 3.82 d on average), and both fecundity and daily eggs laid per female were reduced to 24.86 and 0.83, respectively, indicating that there exist significant differences between the two <span class="hlt">CO</span><span class="hlt">2</span> levels. Results suggest that the population fitness of invasive thrips species might be enhanced with <span class="hlt">increase</span> in <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>, and accordingly change the local thrips population composition with their invasion. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26526873','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26526873"><span>Drought × <span class="hlt">CO</span><span class="hlt">2</span> interactions in trees: a test of the low-intercellular <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> (Ci ) mechanism.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kelly, Jeff W G; Duursma, Remko A; Atwell, Brian J; Tissue, David T; Medlyn, Belinda E</p> <p>2016-03-01</p> <p>Models of tree responses to climate typically project that elevated atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> (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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> (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. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1784b0007F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1784b0007F"><span>Effects of different <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> on growth and photosynthetic of rain tree plants (Albizia saman jacq.Merr)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fathurrahman, F.; Nizam, M. S.; Wan Juliana, W. A.; Doni, Febri; NorLailatul, W. M.; Che Radziah, C. M. Z.</p> <p>2016-11-01</p> <p>A preliminary study was conducted to determine the effect of elevated carbon dioxide (<span class="hlt">CO</span><span class="hlt">2</span>) in rain tree growth under controllable growth chamber. The tolerance towards <span class="hlt">CO</span><span class="hlt">2</span> absorption in the photosynthesis process for the growth of tree rain is still unknown. In this study, rain tree seedlings were incubated for three months in a growth chamber with three different <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> treatment: GC1 (300 ppm), GC2 (600 ppm) and GC3 (900 ppm) at similar condition of temperature (28°C), humidity (60%) and lighting (1200 lux). The results showed that <span class="hlt">increased</span> <span class="hlt">CO</span><span class="hlt">2</span> significantly <span class="hlt">increase</span> the growth rate and chlorophyll content in rain tree. The results of this study add to the further understanding of how the improvement of the growth and physiological characteristics of rain tree was affected by <span class="hlt">CO</span><span class="hlt">2</span> enrichment treatment. This research can for used for global warming mitigation in the future.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017InPhT..80..131C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017InPhT..80..131C"><span>Measurement of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> at high-temperature based on tunable diode laser absorption spectroscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Jiuying; Li, Chuanrong; Zhou, Mei; Liu, Jianguo; Kan, Ruifeng; Xu, Zhenyu</p> <p>2017-01-01</p> <p>A diode laser sensor based on absorption spectroscopy has been developed for sensitive measurement of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> at high-temperature. Measurement of <span class="hlt">CO</span><span class="hlt">2</span> can provide information about the extent of combustion and mix in a combustor that may be used to improve fuel efficiency. Most methods of in-situ combustion measurement of <span class="hlt">CO</span><span class="hlt">2</span> use the spectroscopic parameters taken from database like HITEMP which is mainly derived from the theoretical calculation and remains a high degree of uncertainty in the spectroscopic parameters. A fiber-coupled diode laser system for measurement of <span class="hlt">CO</span><span class="hlt">2</span> in combustion environment by use of the high-temperature spectroscopic parameters which are obtained by experiment was proposed. Survey spectra of the R(50) line of <span class="hlt">CO</span><span class="hlt">2</span> at 5007.787 cm-1 were recorded at high-temperature and various pressures to determine line intensities. The line intensities form the theoretical foundation for future applications of this diode laser sensor system. Survey spectra of four test gas mixtures containing 5.01%<span class="hlt">CO</span><span class="hlt">2</span>, 10.01%<span class="hlt">CO</span><span class="hlt">2</span>, 20.08%<span class="hlt">CO</span><span class="hlt">2</span>, and 49.82%<span class="hlt">CO</span><span class="hlt">2</span> were measured to verify the accuracy of the diode laser sensor system. The measured results indicate that this sensor can measure <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> with 2% uncertainty in high temperatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19650000387','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19650000387"><span>Test strips detect different <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> in closed compartments</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1965-01-01</p> <p>Four different test strips, using crystal violet for one pair of strips and basic fuchsin as a dye for the second pair, give unambiguous colorimetric indications of four different <span class="hlt">concentrations</span> of carbon dioxide in the atmosphere of a closed compartment. Tetraethylene pentamine is used as a dye decoloring agent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19790017964','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790017964"><span>Technology advancement of the electrochemical <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrating</span> process</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schubert, F. H.; Heppner, D. B.; Hallick, T. M.; Woods, R. R.</p> <p>1979-01-01</p> <p>Two multicell, liquid-cooled, advanced electrochemical depolarized carbon dioxide <span class="hlt">concentrator</span> 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).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1394443','SCIGOV-DOEDE'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1394443"><span>Atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">Concentrations</span> from Aircraft for 1972-1981, CSIRO Monitoring Program</span></a></p> <p><a target="_blank" href="http://www.osti.gov/dataexplorer">DOE Data Explorer</a></p> <p>Beardsmore, D. J.; Pearman, G. I.</p> <p>2012-01-01</p> <p>From 1972 through 1981, air samples were collected in glass flasks from aircraft at a variety of latitudes and altitudes over Australia, New Zealand, and Antarctica. The samples were analyzed for <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> with nondispersive infrared gas analysis. The resulting data contain the sampling dates, type of aircraft, flight number, flask identification number, sampling time, geographic sector, distance in kilometers from the listed distance measuring equipment (DME) station, station number of the radio navigation distance measuring equipment, altitude of the aircraft above mean sea level, sample analysis date, flask pressure, tertiary standards used for the analysis, analyzer used, and <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>. These data represent the first published record of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> in the Southern Hemisphere expressed in the WMO 1981 <span class="hlt">CO</span><span class="hlt">2</span> Calibration Scale and provide a precise record of atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> in the troposphere and lower stratosphere over Australia and New Zealand.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27593278','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27593278"><span>Combined effects of elevated temperature and <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> on Cd and Zn accumulation dynamics in Triticum aestivum L.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Xiaoheng; Li, Yu; Lu, Hong; Wang, Shigong</p> <p>2016-09-01</p> <p>A simulated climate warming experiment was conducted to evaluate the combined effects of elevated temperature and <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">increased</span> Cd bioaccumulation in the shoots by 1.4-2.5 times, and <span class="hlt">increased</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> <span class="hlt">increase</span> also led to <span class="hlt">increased</span> Cd <span class="hlt">concentration</span>, and decreased Zn <span class="hlt">concentration</span> in subcellular compartments of wheat seedlings. The largest Cd <span class="hlt">concentration</span> <span class="hlt">increase</span> (174.4%) was observed in the cell wall and debris fractions of shoots after they were subjected to the highest <span class="hlt">CO</span><span class="hlt">2</span> and temperature treatment (TC3). The largest Zn <span class="hlt">concentration</span> decrease (53.1%) was observed in the soluble (F3) fractions of shoots after they were subjected to the medium <span class="hlt">CO</span><span class="hlt">2</span> and temperature treatment (TC2). The temperature and <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">increase</span> had no significant effect on the proportional distribution of Cd and Zn in the subcellular fractions. The root-to-shoot translocation of Cd <span class="hlt">increased</span> with the <span class="hlt">increasing</span> temperature and <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>. However, the Zn distributions only fluctuated within a small range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/963195','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/963195"><span>Implications of Limiting <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">Concentrations</span> for Land Use and Energy</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>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.</p> <p>2009-05-29</p> <p>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 <span class="hlt">concentration</span> of atmospheric <span class="hlt">CO</span><span class="hlt">2</span>. 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> falls; crop prices rise; and human diets are transformed as people shift away from consumption of beef and other carbon-intensive protein sources. The <span class="hlt">increase</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> as energy technologies such as <span class="hlt">CO</span><span class="hlt">2</span> capture and storage.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770021792','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770021792"><span>Technology advancement of the electrochemical <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrating</span> process</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schubert, F. H.; Woods, R. R.; Hallick, T. M.; Heppner, D. B.</p> <p>1977-01-01</p> <p>A five-cell, liquid-cooled advanced electrochemical depolarized carbon dioxide <span class="hlt">concentrator</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AtmEn.115..286K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AtmEn.115..286K"><span>Characteristics of ground level <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> over contrasting land uses in a tropical urban environment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kishore Kumar, M.; Shiva Nagendra, S. M.</p> <p>2015-08-01</p> <p>Indian cities feature high human population density, heterogeneous traffic, mixed land-use patterns and mostly tropical meteorological conditions. Characteristics of ambient <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> under these distinctive features are very specific and the related studies are limited. This paper presents the characteristics of ground level <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> at three contrasting land uses (residential, commercial and industrial) in a tropical urban area of India. The <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> were monitored in Chennai city for 31 days at each land use during June-September, 2013. Emissions of <span class="hlt">CO</span><span class="hlt">2</span> from all the major anthropogenic sources present at the three study sites were also quantified. Results indicated that the daily average <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> 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, <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>, while soil and plant respiration phenomena had a greater control over the night time <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>. Further, the <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> were high during the stagnation and stable meteorological conditions than the ventilation and unstable conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013BGD....1018479B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013BGD....1018479B"><span>An inverse modeling approach for tree-ring-based climate reconstructions under changing atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Boucher, É.; Guiot, J.; Hatté, C.; Daux, V.; Danis, P.-A.; Dussouillez, P.</p> <p>2013-11-01</p> <p>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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> reached unprecedented levels (near 400 ppm). Based on these transfer functions, dendroclimatologists must then reconstruct a different past, a past where <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> scenarios, we present evidence that <span class="hlt">increasing</span> <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> have had a slight, yet significant, effect on reconstruction results. We demonstrate that higher <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> augment the efficiency of water use by trees, therefore favoring the reconstruction of a warmer and drier climate. Under elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>, 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 <span class="hlt">CO</span><span class="hlt">2</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V31D..04L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V31D..04L"><span>Forsterite Carbonation in Wet-sc<span class="hlt">CO</span><span class="hlt">2</span>: Dependence on Adsorbed Water <span class="hlt">Concentration</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Loring, J.; Benezeth, P.; Qafoku, O.; Thompson, C.; Schaef, T.; Bonneville, A.; McGrail, P.; Felmy, A.; Rosso, K.</p> <p>2013-12-01</p> <p>Capturing and storing <span class="hlt">CO</span><span class="hlt">2</span> in basaltic formations is one of the most promising options for mitigating atmospheric <span class="hlt">CO</span><span class="hlt">2</span> emissions resulting from the burning of fossil fuels. These geologic reservoirs have high reactive potential for <span class="hlt">CO</span><span class="hlt">2</span>-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 sc<span class="hlt">CO</span><span class="hlt">2</span> conditions, e. g. encountered near a <span class="hlt">CO</span><span class="hlt">2</span> injection well, proceeds along a different pathway and is more effective than in <span class="hlt">CO</span><span class="hlt">2</span>-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 sc<span class="hlt">CO</span><span class="hlt">2</span>. Aliquots of water were titrated at 4-hour reaction-time increments. Once a desired total water <span class="hlt">concentration</span> 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 <span class="hlt">increase</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12121454','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12121454"><span><span class="hlt">CO</span><span class="hlt">2</span>-<span class="hlt">concentrating</span> mechanisms in Egeria densa, a submersed aquatic plant.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lara, María V; Casati, Paula; Andreo, Carlos S</p> <p>2002-08-01</p> <p>Egeria densa is an aquatic higher plant which has developed different mechanisms to deal with photosynthesis under conditions of low <span class="hlt">CO</span><span class="hlt">2</span> availability. On the one hand it shows leaf pH-polarity, which has been proposed to be used for bicarbonate utilization. In this way, at high light intensities and low dissolved carbon <span class="hlt">concentration</span>, this species generates a low pH at the adaxial leaf surface. This acidification shifts the equilibrium HCO3-/<span class="hlt">CO</span><span class="hlt">2</span> towards <span class="hlt">CO</span><span class="hlt">2</span>, which enters the cell by passive diffusion. By this means, E. densa <span class="hlt">increases</span> the <span class="hlt">concentration</span> of <span class="hlt">CO</span><span class="hlt">2</span> available for photosynthesis inside the cells, when this gas is limiting. On the other hand, under stress conditions resulting from high temperature and high light intensities, it shows a biochemical adaptation with the induction of a C4-like mechanism but without Kranz anatomy. Transfer from low to high temperature and light conditions induces <span class="hlt">increased</span> levels of phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) and NADP-malic enzyme (NADP-ME, EC 1.1.1.40), both key enzymes participating in the Hatch-Slack cycle in plants with C4 metabolism. Moreover, one PEPC isoform, whose synthesis is induced by high temperature and light, is phosphorylated in the light, and changes in kinetic and regulatory properties are correlated with changes in the phosphorylation state of this enzyme. In the present review, we describe these two processes in this submersed angiosperm that appear to help it perform photosynthesis under conditions of extreme temperatures and high light intensities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/40013','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/40013"><span><span class="hlt">Increased</span> resin flow in mature pine trees growing under elevated <span class="hlt">CO</span><span class="hlt">2</span> and moderate soil fertility</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>K.A. Novick; G.G. Katul; H.R. McCarthy; R. Oren</p> <p>2012-01-01</p> <p>Warmer climates induced by elevated atmospheric <span class="hlt">CO</span><span class="hlt">2</span> (e<span class="hlt">CO</span><span class="hlt">2</span>) are expected to <span class="hlt">increase</span> damaging bark beetle activity in pine forests, yet the effect of e<span class="hlt">CO</span><span class="hlt">2</span> on resin production—the tree’s primary defense against beetle attack—remains largely unknown. Following growth-differentiation balance theory, if extra carbohydrates produced under e<span class="hlt">CO</span><span class="hlt">2</span> are not consumed by respiration...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12226410','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12226410"><span>Effect of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">Concentration</span> on Carbonic Anhydrase and Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Expression in Pea.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Majeau, N.; Coleman, J. R.</p> <p>1996-10-01</p> <p>The effect of external <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> on the expression of carbonic anhydrase (CA) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) was examined in pea (Pisum sativum cv Little Marvel) leaves. Enzyme activities and their transcript levels were reduced in plants grown at 1000 [mu]L/L <span class="hlt">CO</span><span class="hlt">2</span> compared with plants grown in ambient air. Growth at 160 [mu]L/L <span class="hlt">CO</span><span class="hlt">2</span> also appeared to reduce steady-state transcript levels for rbcS, the gene encoding the small subunit of Rubisco, and for ca, the gene encoding CA; however, rbcS transcripts were reduced to a greater extent at this <span class="hlt">concentration</span>. Rubisco activity was slightly lower in plants grown at 160 [mu]L/L <span class="hlt">CO</span><span class="hlt">2</span>, and CA activity was significantly higher than that observed in air-grown plants. Transfer of plants from 1000 [mu]L/L to air levels of <span class="hlt">CO</span><span class="hlt">2</span> resulted in a rapid <span class="hlt">increase</span> in both ca and rbcS transcript abundance in fully expanded leaves, followed by an <span class="hlt">increase</span> in enzyme activity. Plants transferred from air to high-<span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> appeared to modulate transcript abundance and enzyme activity less quickly. Foliar carbohydrate levels were also examined in plants grown continuously at high and ambient <span class="hlt">CO</span><span class="hlt">2</span>, and following changes in growth conditions that rapidly altered ca and rbcS transcript abundance and enzyme activities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoRL..4311339T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoRL..4311339T"><span><span class="hlt">Increased</span> light-use efficiency in northern terrestrial ecosystems indicated by <span class="hlt">CO</span><span class="hlt">2</span> and greening observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thomas, Rebecca T.; Prentice, Iain Colin; Graven, Heather; Ciais, Philippe; Fisher, Joshua B.; Hayes, Daniel J.; Huang, Maoyi; Huntzinger, Deborah N.; Ito, Akihiko; Jain, Atul; Mao, Jiafu; Michalak, Anna M.; Peng, Shushi; Poulter, Benjamin; Ricciuto, Daniel M.; Shi, Xiaoying; Schwalm, Christopher; Tian, Hanqin; Zeng, Ning</p> <p>2016-11-01</p> <p>Observations show an <span class="hlt">increasing</span> amplitude in the seasonal cycle of <span class="hlt">CO</span><span class="hlt">2</span> (ASC) north of 45°N of 56 ± 9.8% over the last 50 years and an <span class="hlt">increase</span> in vegetation greenness of 7.5-15% in high northern latitudes since the 1980s. However, the causes of these changes remain uncertain. Historical simulations from terrestrial biosphere models in the Multiscale Synthesis and Terrestrial Model Intercomparison Project are compared to the ASC and greenness observations, using the TM3 atmospheric transport model to translate surface fluxes into <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>. We find that the modeled change in ASC is too small but the mean greening trend is generally captured. Modeled <span class="hlt">increases</span> in greenness are primarily driven by warming, whereas ASC changes are primarily driven by <span class="hlt">increasing</span> <span class="hlt">CO</span><span class="hlt">2</span>. We suggest that <span class="hlt">increases</span> in ecosystem-scale light use efficiency (LUE) have contributed to the observed ASC <span class="hlt">increase</span> but are underestimated by current models. We highlight potential mechanisms that could <span class="hlt">increase</span> modeled LUE.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24881373','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24881373"><span>[Diurnal and seasonal variations of surface atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> in the river estuarine marsh].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Lin-Hai; Tong, Chuan; Zeng, Cong-Sheng</p> <p>2014-03-01</p> <p>Characteristics of diurnal and seasonal variations of surface atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> were analyzed in the Minjiang River estuarine marsh from December 2011 to November 2012. The results revealed that both the diurnal and seasonal variation of surface atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> showed single-peak patterns, with the valley in the daytime and the peak value at night for the diurnal variations, and the maxima in winter and minima in summer for the seasonal variation. Diurnal amplitude of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> varied from 16.96 micromol x mol(-1) to 38.30 micromol x mol(-1). The seasonal averages of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> in spring, summer, autumn and winter were (353.74 +/- 18.35), (327.28 +/- 8.58), (354.78 +/- 14.76) and (392.82 +/- 9.71) micromol x mol(-1), respectively, and the annual mean <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> was (357.16 +/- 26.89) micromol x mol(-1). The diurnal <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> of surface atmospheric was strongly negatively correlated with temperature, wind speed, photosynthetically active radiation and total solar radiation (P < 0.05). The diurnal <span class="hlt">concentration</span> of <span class="hlt">CO</span><span class="hlt">2</span> was negatively related with tidal level in January, but significantly positively related in July.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.A51A0103C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.A51A0103C"><span>Simulation of Atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">Concentrations</span> in California’s South Coast Basin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Costigan, K. R.; Dubey, M. K.</p> <p>2009-12-01</p> <p>Verification of green house gas emission control treaties will require the coupling of measurements and models that can account for sources, sinks, and transport of these gasses. This paper presents an application of the Weather Research and Forecasting Chemistry model (WRF-Chem) to study <span class="hlt">CO</span><span class="hlt">2</span> transport in California’s South Coast Basin. The model is run for the week of 23-29 March 2008 to correspond with the atmospheric <span class="hlt">CO</span><span class="hlt">2</span> abundances measured with a ground-based Fourier transform spectrometer (FTS) and reported by Wunch et al. (2009). <span class="hlt">CO</span><span class="hlt">2</span> emissions used as input for the model are estimated from the Vulcan <span class="hlt">CO</span><span class="hlt">2</span> inventory (Gurney et al., 2009) and <span class="hlt">CO</span><span class="hlt">2</span> is treated as a passive tracer in the simulation. In particular, this paper addresses details of the simulation and analysis of the simulated meteorological conditions that may explain some of the observed day-to-day variations in <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28705662','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28705662"><span>Transcriptional response of the extremophile red alga Cyanidioschyzon merolae to changes in <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rademacher, Nadine; Wrobel, Thomas J; Rossoni, Alessandro W; Kurz, Samantha; Bräutigam, Andrea; Weber, Andreas P M; Eisenhut, Marion</p> <p>2017-10-01</p> <p>Cyanidioschyzon merolae (C. merolae) is an acidophilic red alga growing in a naturally low carbon dioxide (<span class="hlt">CO</span><span class="hlt">2</span>) environment. Although it uses a ribulose 1,5-bisphosphate carboxylase/oxygenase with high affinity for <span class="hlt">CO</span><span class="hlt">2</span>, the survival of C. merolae relies on functional photorespiratory metabolism. In this study, we quantified the transcriptomic response of C. merolae to changes in <span class="hlt">CO</span><span class="hlt">2</span> conditions. We found distinct changes upon shifts between <span class="hlt">CO</span><span class="hlt">2</span> conditions, such as a concerted up-regulation of photorespiratory genes and responses to carbon starvation. We used the transcriptome data set to explore a hypothetical <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrating</span> mechanism in C. merolae, based on the assumption that photorespiratory genes and possible candidate genes involved in a <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrating</span> mechanism are co-expressed. A putative bicarbonate transport protein and two α-carbonic anhydrases were identified, which showed enhanced transcript levels under reduced <span class="hlt">CO</span><span class="hlt">2</span> conditions. Genes encoding enzymes of a PEPCK-type C4 pathway were co-regulated with the photorespiratory gene cluster. We propose a model of a hypothetical low <span class="hlt">CO</span><span class="hlt">2</span> compensation mechanism in C. merolae integrating these low <span class="hlt">CO</span><span class="hlt">2</span>-inducible components. Copyright © 2017 Elsevier GmbH. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.B43D1599D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.B43D1599D"><span>On Using <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">Concentration</span> Measurements at Mountain top and Valley Locations in Regional Flux Studies.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de Wekker, S. F.; Song, G.; Stephens, B. B.</p> <p>2007-12-01</p> <p>Data from the Regional Atmospheric Continuous <span class="hlt">CO</span><span class="hlt">2</span> Network in the Rocky Mountains (Rocky RACCOON) are used to investigate atmospheric controls on temporal and spatial variability of <span class="hlt">CO</span><span class="hlt">2</span> in mountainous terrain and the usefulness of mountain top and valley measurement for the estimation of regional <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> Analyzer. These units measure <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> at three levels on a tower, producing individual measurements every 2.5 minutes precise to 0.1 ppm <span class="hlt">CO</span><span class="hlt">2</span> and closely tied to the WMO <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26529678','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26529678"><span>The nature of the <span class="hlt">CO</span><span class="hlt">2</span> -<span class="hlt">concentrating</span> mechanisms in a marine diatom, Thalassiosira pseudonana.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Clement, Romain; Dimnet, Laura; Maberly, Stephen C; Gontero, Brigitte</p> <p>2016-03-01</p> <p>Diatoms are widespread in aquatic ecosystems where they may be limited by the supply of inorganic carbon. Their carbon dioxide-<span class="hlt">concentrating</span> mechanisms (CCMs) involving transporters and carbonic anhydrases (CAs) are well known, but the contribution of a biochemical CCM involving C4 metabolism is contentious. The CCM(s) present in the marine-centric diatom, Thalassiosira pseudonana, were studied in cells exposed to high or low <span class="hlt">concentrations</span> of <span class="hlt">CO</span><span class="hlt">2</span> , using a range of approaches. At low <span class="hlt">CO</span><span class="hlt">2</span> , cells possessed a CCM based on active uptake of <span class="hlt">CO</span><span class="hlt">2</span> (70% contribution) and bicarbonate, while at high <span class="hlt">CO</span><span class="hlt">2</span> , cells were restricted to <span class="hlt">CO</span><span class="hlt">2</span> . CA was highly and rapidly activated on transfer to low <span class="hlt">CO</span><span class="hlt">2</span> and played a key role because inhibition of external CA produced uptake kinetics similar to cells grown at high <span class="hlt">CO</span><span class="hlt">2</span> . The activities of phosphoenolpyruvate (PEP) carboxylase (PEPC) and the PEP-regenerating enzyme, pyruvate phosphate dikinase (PPDK), were lower in cells grown at low than at high <span class="hlt">CO</span><span class="hlt">2</span> . The ratios of PEPC and PPDK to ribulose bisphosphate carboxylase were substantially lower than 1, even at low <span class="hlt">CO</span><span class="hlt">2</span> . Our data suggest that the kinetic properties of this species results from a biophysical CCM and not from C4 type metabolism.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040088900&hterms=carbon+capture&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dcarbon%2Bcapture','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040088900&hterms=carbon+capture&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dcarbon%2Bcapture"><span>Adaptation to high <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> in an optimal environment: radiation capture, canopy quantum yield and carbon use efficiency</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Monje, O.; Bugbee, B.</p> <p>1998-01-01</p> <p>The effect of elevated [<span class="hlt">CO</span><span class="hlt">2</span>] 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 [<span class="hlt">CO</span><span class="hlt">2</span>] 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 [<span class="hlt">CO</span><span class="hlt">2</span>], but yield <span class="hlt">increased</span> by 13% due to a sustained <span class="hlt">increase</span> in canopy quantum yield. <span class="hlt">CO</span><span class="hlt">2</span> enrichment <span class="hlt">increased</span> root mass, tiller number and seed mass. Harvest index and chlorophyll <span class="hlt">concentration</span> were unchanged, but <span class="hlt">CO</span><span class="hlt">2</span> enrichment <span class="hlt">increased</span> average life cycle net photosynthesis (13%, P < 0.05) and root respiration (24%, P < 0.05). These data indicate that plant communities adapt to <span class="hlt">CO</span><span class="hlt">2</span> enrichment through changes in C allocation. Elevated [<span class="hlt">CO</span><span class="hlt">2</span>] <span class="hlt">increases</span> sink strength in optimal environments, resulting in sustained <span class="hlt">increases</span> in photosynthetic capacity, canopy quantum yield and daily C gain throughout the life cycle.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040088900&hterms=radiation+effect+plant&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dradiation%2Beffect%2Bplant','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040088900&hterms=radiation+effect+plant&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dradiation%2Beffect%2Bplant"><span>Adaptation to high <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> in an optimal environment: radiation capture, canopy quantum yield and carbon use efficiency</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Monje, O.; Bugbee, B.</p> <p>1998-01-01</p> <p>The effect of elevated [<span class="hlt">CO</span><span class="hlt">2</span>] 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 [<span class="hlt">CO</span><span class="hlt">2</span>] 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 [<span class="hlt">CO</span><span class="hlt">2</span>], but yield <span class="hlt">increased</span> by 13% due to a sustained <span class="hlt">increase</span> in canopy quantum yield. <span class="hlt">CO</span><span class="hlt">2</span> enrichment <span class="hlt">increased</span> root mass, tiller number and seed mass. Harvest index and chlorophyll <span class="hlt">concentration</span> were unchanged, but <span class="hlt">CO</span><span class="hlt">2</span> enrichment <span class="hlt">increased</span> average life cycle net photosynthesis (13%, P < 0.05) and root respiration (24%, P < 0.05). These data indicate that plant communities adapt to <span class="hlt">CO</span><span class="hlt">2</span> enrichment through changes in C allocation. Elevated [<span class="hlt">CO</span><span class="hlt">2</span>] <span class="hlt">increases</span> sink strength in optimal environments, resulting in sustained <span class="hlt">increases</span> in photosynthetic capacity, canopy quantum yield and daily C gain throughout the life cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11543216','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11543216"><span>Adaptation to high <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> in an optimal environment: radiation capture, canopy quantum yield and carbon use efficiency.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Monje, O; Bugbee, B</p> <p>1998-01-01</p> <p>The effect of elevated [<span class="hlt">CO</span><span class="hlt">2</span>] 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 [<span class="hlt">CO</span><span class="hlt">2</span>] 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 [<span class="hlt">CO</span><span class="hlt">2</span>], but yield <span class="hlt">increased</span> by 13% due to a sustained <span class="hlt">increase</span> in canopy quantum yield. <span class="hlt">CO</span><span class="hlt">2</span> enrichment <span class="hlt">increased</span> root mass, tiller number and seed mass. Harvest index and chlorophyll <span class="hlt">concentration</span> were unchanged, but <span class="hlt">CO</span><span class="hlt">2</span> enrichment <span class="hlt">increased</span> average life cycle net photosynthesis (13%, P < 0.05) and root respiration (24%, P < 0.05). These data indicate that plant communities adapt to <span class="hlt">CO</span><span class="hlt">2</span> enrichment through changes in C allocation. Elevated [<span class="hlt">CO</span><span class="hlt">2</span>] <span class="hlt">increases</span> sink strength in optimal environments, resulting in sustained <span class="hlt">increases</span> in photosynthetic capacity, canopy quantum yield and daily C gain throughout the life cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24960074','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24960074"><span>Solvation of <span class="hlt">CO</span><span class="hlt">2</span> in water: effect of RuBP on <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> in bundle sheath of C4 plants.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sadhukhan, Tumpa; Latif, Iqbal A; Datta, Sambhu N</p> <p>2014-07-24</p> <p>An understanding of the temperature-dependence of solubility of carbon dioxide (<span class="hlt">CO</span><span class="hlt">2</span>) in water is important for many industrial processes. Voluminous work has been done by both quantum chemical methods and molecular dynamics (MD) simulations on the interaction between <span class="hlt">CO</span><span class="hlt">2</span> and water, but a quantitative evaluation of solubility remains elusive. In this work, we have approached the problem by considering quantum chemically calculated total energies and thermal energies, and incorporating the effects of mixing, hydrogen bonding, and phonon modes. An overall equation relating the calculated free energy and entropy of mixing with the gas-solution equilibrium constant has been derived. This equation has been iteratively solved to obtain the solubility as functions of temperature and dielectric constant. The calculated solubility versus temperature plot excellently matches the observed plot. Solubility has been shown to <span class="hlt">increase</span> with dielectric constant, for example, by addition of electrolytes. We have also found that at the experimentally reported <span class="hlt">concentration</span> of enzyme RuBP in bundle sheath cells of chloroplast in C4 green plants, the <span class="hlt">concentration</span> of <span class="hlt">CO</span><span class="hlt">2</span> can effectively <span class="hlt">increase</span> by as much as a factor of 7.1-38.5. This stands in agreement with the observed effective rise in <span class="hlt">concentration</span> by as much as 10 times.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMGC53B1266M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMGC53B1266M"><span>Quantifying carbon cycling via continuous measurement of atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> and δ13C in Chicago, IL</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moore, J.; Jacobson, A. D.</p> <p>2012-12-01</p> <p>While cities emit ~70% of the annual anthropogenic <span class="hlt">CO</span><span class="hlt">2</span> flux, most studies of atmospheric carbon cycling have focused on rural areas. Thus, carbon cycling in urban areas remains an understudied topic. We are using wavelength scanned cavity ring down spectroscopy to continuously measure the <span class="hlt">concentration</span> and carbon isotope composition of atmospheric <span class="hlt">CO</span><span class="hlt">2</span> ([<span class="hlt">CO</span><span class="hlt">2</span>] and δ13C, respectively) on the Northwestern University campus, located on the western shore of Lake Michigan, 13 miles north of downtown Chicago. We have collected ~11,500 data points per day, along with complementary local meteorological information, for the time period spanning August 2011 to February 2012. We are using isotope mixing models to calculate quantities of locally-sourced <span class="hlt">CO</span><span class="hlt">2</span> from anthropogenic versus natural sources, i.e., gasoline and natural gas combustion versus C3 plant and soil respiration. Broad trends in the data fall into three categories consistent with the Northern Hemisphere seasonal cycle: summer (August - September), fall (October - November), and winter (December - February). Within each category, we observe short-term trends occurring on hourly to daily time scales. Overall, we find that [<span class="hlt">CO</span><span class="hlt">2</span>] and δ13C anti-correlate, with δ13C decreasing when [<span class="hlt">CO</span><span class="hlt">2</span>] <span class="hlt">increases</span>. Local carbon cycling is most evident when wind speeds are less than 4.5 m/s (10 mph). As wind speeds <span class="hlt">increase</span>, [<span class="hlt">CO</span><span class="hlt">2</span>] and δ13C approach global background values. Preliminary findings for each period include: Summer (Aug. - Sept.): The mean [<span class="hlt">CO</span><span class="hlt">2</span>] and δ13C are 400 ppm and -8.3 ‰, respectively, which are about 12 ppm higher and 0.1 ‰ lower than measured values at Mauna Loa, HI. Early morning hours have statistically higher [<span class="hlt">CO</span><span class="hlt">2</span>] than afternoon hours. The early morning maximum is likely due to a combination of plant respiration and petroleum combustion, while the afternoon minimum is due to photosynthetic <span class="hlt">CO</span><span class="hlt">2</span> uptake. Both the lowest and highest [<span class="hlt">CO</span><span class="hlt">2</span>] occur when wind originates from the south and west over the most densely</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25608664','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25608664"><span><span class="hlt">CO</span><span class="hlt">2</span> enrichment and N addition <span class="hlt">increase</span> nutrient loss from decomposing leaf litter in subtropical model forest ecosystems.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Juxiu; Fang, Xiong; Deng, Qi; Han, Tianfeng; Huang, Wenjuan; Li, Yiyong</p> <p>2015-01-22</p> <p>As atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> <span class="hlt">increases</span>, many experiments have been carried out to study effects of <span class="hlt">CO</span><span class="hlt">2</span> enrichment on litter decomposition and nutrient release. However, the result is still uncertain. Meanwhile, the impact of <span class="hlt">CO</span><span class="hlt">2</span> enrichment on nutrients other than N and P are far less studied. Using open-top chambers, we examined effects of elevated <span class="hlt">CO</span><span class="hlt">2</span> and N addition on leaf litter decomposition and nutrient release in subtropical model forest ecosystems. We found that both elevated <span class="hlt">CO</span><span class="hlt">2</span> and N addition <span class="hlt">increased</span> nutrient (C, N, P, K, Ca, Mg and Zn) loss from the decomposing litter. The N, P, Ca and Zn loss was more than tripled in the chambers exposed to both elevated <span class="hlt">CO</span><span class="hlt">2</span> and N addition than those in the control chambers after 21 months of treatment. The stimulation of nutrient loss under elevated <span class="hlt">CO</span><span class="hlt">2</span> was associated with the <span class="hlt">increased</span> soil moisture, the higher leaf litter quality and the greater soil acidity. Accelerated nutrient release under N addition was related to the higher leaf litter quality, the <span class="hlt">increased</span> soil microbial biomass and the greater soil acidity. Our results imply that elevated <span class="hlt">CO</span><span class="hlt">2</span> and N addition will <span class="hlt">increase</span> nutrient cycling in subtropical China under the future global change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4350107','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4350107"><span>Natural high p<span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">increases</span> autotrophy in Anemonia viridis (Anthozoa) as revealed from stable isotope (C, N) analysis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Horwitz, Rael; Borell, Esther M.; Yam, Ruth; Shemesh, Aldo; Fine, Maoz</p> <p>2015-01-01</p> <p>Contemporary cnidarian-algae symbioses are challenged by <span class="hlt">increasing</span> <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> (ocean warming and acidification) affecting organisms' biological performance. We examined the natural variability of carbon and nitrogen isotopes in the symbiotic sea anemone Anemonia viridis to investigate dietary shifts (autotrophy/heterotrophy) along a natural p<span class="hlt">CO</span><span class="hlt">2</span> gradient at the island of Vulcano, Italy. δ13C values for both algal symbionts (Symbiodinium) and host tissue of A. viridis became significantly lighter with <span class="hlt">increasing</span> seawater p<span class="hlt">CO</span><span class="hlt">2</span>. Together with a decrease in the difference between δ13C values of both fractions at the higher p<span class="hlt">CO</span><span class="hlt">2</span> sites, these results indicate there is a greater net autotrophic input to the A. viridis carbon budget under high p<span class="hlt">CO</span><span class="hlt">2</span> conditions. δ15N values and C/N ratios did not change in Symbiodinium and host tissue along the p<span class="hlt">CO</span><span class="hlt">2</span> gradient. Additional physiological parameters revealed anemone protein and Symbiodinium chlorophyll a remained unaltered among sites. Symbiodinium density was similar among sites yet their mitotic index <span class="hlt">increased</span> in anemones under elevated p<span class="hlt">CO</span><span class="hlt">2</span>. Overall, our findings show that A. viridis is characterized by a higher autotrophic/heterotrophic ratio as p<span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">increases</span>. The unique trophic flexibility of this species may give it a competitive advantage and enable its potential acclimation and ecological success in the future under <span class="hlt">increased</span> ocean acidification. PMID:25739995</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NatSR...5E7952L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatSR...5E7952L"><span><span class="hlt">CO</span><span class="hlt">2</span> enrichment and N addition <span class="hlt">increase</span> nutrient loss from decomposing leaf litter in subtropical model forest ecosystems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Juxiu; Fang, Xiong; Deng, Qi; Han, Tianfeng; Huang, Wenjuan; Li, Yiyong</p> <p>2015-01-01</p> <p>As atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> <span class="hlt">increases</span>, many experiments have been carried out to study effects of <span class="hlt">CO</span><span class="hlt">2</span> enrichment on litter decomposition and nutrient release. However, the result is still uncertain. Meanwhile, the impact of <span class="hlt">CO</span><span class="hlt">2</span> enrichment on nutrients other than N and P are far less studied. Using open-top chambers, we examined effects of elevated <span class="hlt">CO</span><span class="hlt">2</span> and N addition on leaf litter decomposition and nutrient release in subtropical model forest ecosystems. We found that both elevated <span class="hlt">CO</span><span class="hlt">2</span> and N addition <span class="hlt">increased</span> nutrient (C, N, P, K, Ca, Mg and Zn) loss from the decomposing litter. The N, P, Ca and Zn loss was more than tripled in the chambers exposed to both elevated <span class="hlt">CO</span><span class="hlt">2</span> and N addition than those in the control chambers after 21 months of treatment. The stimulation of nutrient loss under elevated <span class="hlt">CO</span><span class="hlt">2</span> was associated with the <span class="hlt">increased</span> soil moisture, the higher leaf litter quality and the greater soil acidity. Accelerated nutrient release under N addition was related to the higher leaf litter quality, the <span class="hlt">increased</span> soil microbial biomass and the greater soil acidity. Our results imply that elevated <span class="hlt">CO</span><span class="hlt">2</span> and N addition will <span class="hlt">increase</span> nutrient cycling in subtropical China under the future global change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25739995','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25739995"><span>Natural high p<span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">increases</span> autotrophy in Anemonia viridis (Anthozoa) as revealed from stable isotope (C, N) analysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Horwitz, Rael; Borell, Esther M; Yam, Ruth; Shemesh, Aldo; Fine, Maoz</p> <p>2015-03-05</p> <p>Contemporary cnidarian-algae symbioses are challenged by <span class="hlt">increasing</span> <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> (ocean warming and acidification) affecting organisms' biological performance. We examined the natural variability of carbon and nitrogen isotopes in the symbiotic sea anemone Anemonia viridis to investigate dietary shifts (autotrophy/heterotrophy) along a natural p<span class="hlt">CO</span><span class="hlt">2</span> gradient at the island of Vulcano, Italy. δ(13)C values for both algal symbionts (Symbiodinium) and host tissue of A. viridis became significantly lighter with <span class="hlt">increasing</span> seawater p<span class="hlt">CO</span><span class="hlt">2</span>. Together with a decrease in the difference between δ(13)C values of both fractions at the higher p<span class="hlt">CO</span><span class="hlt">2</span> sites, these results indicate there is a greater net autotrophic input to the A. viridis carbon budget under high p<span class="hlt">CO</span><span class="hlt">2</span> conditions. δ(15)N values and C/N ratios did not change in Symbiodinium and host tissue along the p<span class="hlt">CO</span><span class="hlt">2</span> gradient. Additional physiological parameters revealed anemone protein and Symbiodinium chlorophyll a remained unaltered among sites. Symbiodinium density was similar among sites yet their mitotic index <span class="hlt">increased</span> in anemones under elevated p<span class="hlt">CO</span><span class="hlt">2</span>. Overall, our findings show that A. viridis is characterized by a higher autotrophic/heterotrophic ratio as p<span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">increases</span>. The unique trophic flexibility of this species may give it a competitive advantage and enable its potential acclimation and ecological success in the future under <span class="hlt">increased</span> ocean acidification.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4302290','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4302290"><span><span class="hlt">CO</span><span class="hlt">2</span> enrichment and N addition <span class="hlt">increase</span> nutrient loss from decomposing leaf litter in subtropical model forest ecosystems</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Liu, Juxiu; Fang, Xiong; Deng, Qi; Han, Tianfeng; Huang, Wenjuan; Li, Yiyong</p> <p>2015-01-01</p> <p>As atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> <span class="hlt">increases</span>, many experiments have been carried out to study effects of <span class="hlt">CO</span><span class="hlt">2</span> enrichment on litter decomposition and nutrient release. However, the result is still uncertain. Meanwhile, the impact of <span class="hlt">CO</span><span class="hlt">2</span> enrichment on nutrients other than N and P are far less studied. Using open-top chambers, we examined effects of elevated <span class="hlt">CO</span><span class="hlt">2</span> and N addition on leaf litter decomposition and nutrient release in subtropical model forest ecosystems. We found that both elevated <span class="hlt">CO</span><span class="hlt">2</span> and N addition <span class="hlt">increased</span> nutrient (C, N, P, K, Ca, Mg and Zn) loss from the decomposing litter. The N, P, Ca and Zn loss was more than tripled in the chambers exposed to both elevated <span class="hlt">CO</span><span class="hlt">2</span> and N addition than those in the control chambers after 21 months of treatment. The stimulation of nutrient loss under elevated <span class="hlt">CO</span><span class="hlt">2</span> was associated with the <span class="hlt">increased</span> soil moisture, the higher leaf litter quality and the greater soil acidity. Accelerated nutrient release under N addition was related to the higher leaf litter quality, the <span class="hlt">increased</span> soil microbial biomass and the greater soil acidity. Our results imply that elevated <span class="hlt">CO</span><span class="hlt">2</span> and N addition will <span class="hlt">increase</span> nutrient cycling in subtropical China under the future global change. PMID:25608664</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24411401','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24411401"><span>Respiratory <span class="hlt">CO</span><span class="hlt">2</span> response depends on plasma bicarbonate <span class="hlt">concentration</span> in mechanically ventilated patients.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rialp, G; Raurich, J M; Llompart-Pou, J A; Ayestarán, I; Ibáñez, J</p> <p>2014-05-01</p> <p>There is controversy about the effects of high plasma bicarbonate <span class="hlt">concentration</span> ([HCO3(-)]) and the <span class="hlt">CO</span><span class="hlt">2</span> response test. We analyzed the relationship between [HCO3(-)] and the variation in hydrogen ion <span class="hlt">concentration</span> (pH) for a given change in Pa<span class="hlt">CO</span><span class="hlt">2</span>, and its effects upon <span class="hlt">CO</span><span class="hlt">2</span> response. A retrospective study was carried out. Two intensive care units. Subjects with and without chronic obstructive pulmonary disease (COPD), at the beginning of weaning from mechanical ventilation. The <span class="hlt">CO</span><span class="hlt">2</span> response was evaluated by the re-inhalation of expired air method, measuring the hypercapnic ventilatory response (ΔVE/ΔPa<span class="hlt">CO</span><span class="hlt">2</span>) and hypercapnic drive response (ΔP01/ΔPa<span class="hlt">CO</span><span class="hlt">2</span>), where VE is minute volume and P0.1 is airway occlusion pressure 0.1s after the initiation of inspiration. [HCO3(-)] and <span class="hlt">CO</span><span class="hlt">2</span> response. A total of 120 patients in the non-COPD group and 48 in the COPD group were studied. COPD patients had higher mean [HCO3(-)] than non-COPD patients (33.2 ± 5.4 vs. 25.7 ± 3.7 mmol/l, p<0.001). In both non-COPD and COPD patients we observed a significant inverse linear relationship between [HCO3(-)] and pH change per mmHg of Pa<span class="hlt">CO</span><span class="hlt">2</span> (p<0.001), ΔVE/ΔPa<span class="hlt">CO</span><span class="hlt">2</span> (p<0.001) and ΔP0.1/ΔPa<span class="hlt">CO</span><span class="hlt">2</span> (p<0.001). There is an inverse linear relationship between [HCO3(-)] and the variation of pH for a given change in Pa<span class="hlt">CO</span><span class="hlt">2</span> and the <span class="hlt">CO</span><span class="hlt">2</span> response. Copyright © 2013 Elsevier España, S.L. and SEMICYUC. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11373676','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11373676"><span>Limited carbon storage in soil and litter of experimental forest plots under <span class="hlt">increased</span> atmospheric <span class="hlt">CO</span><span class="hlt">2</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schlesinger, W H; Lichter, J</p> <p>2001-05-24</p> <p>The current rise in atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> is thought to be mitigated in part by carbon sequestration within forest ecosystems, where carbon can be stored in vegetation or soils. The storage of carbon in soils is determined by the fraction that is sequestered in persistent organic materials, such as humus. In experimental forest plots of loblolly pine (Pinus taeda) exposed to high <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>, nearly half of the carbon uptake is allocated to short-lived tissues, largely foliage. These tissues fall to the ground and decompose, normally contributing only a small portion of their carbon content to refractory soil humic materials. Such findings call into question the role of soils as long-term carbon sinks, and show the need for a better understanding of carbon cycling in forest soils. Here we report a significant accumulation of carbon in the litter layer of experimental forest plots after three years of growth at <span class="hlt">increased</span> <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> (565 microl l(-1)). But fast turnover times of organic carbon in the litter layer (of about three years) appear to constrain the potential size of this carbon sink. Given the observation that carbon accumulation in the deeper mineral soil layers was absent, we suggest that significant, long-term net carbon sequestration in forest soils is unlikely.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1911588H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1911588H"><span><span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> characteristics and possible influence of waves on the rate of <span class="hlt">CO</span><span class="hlt">2</span> transfer between the ocean and the atmosphere in a coastal region.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Herrera-Vazquez, Carlos F.; Ocampo-Torres, Francisco J.</p> <p>2017-04-01</p> <p>In order to understand the physical processes involved in the air-sea transfer velocity of <span class="hlt">CO</span><span class="hlt">2</span> in a coastal region. The possible influence of the waves as an external agent is studied in order to characterize the <span class="hlt">CO</span><span class="hlt">2</span> transfer. The air-sea transfer velocity of <span class="hlt">CO</span><span class="hlt">2</span> was calculated from direct measurements of <span class="hlt">CO</span><span class="hlt">2</span> flux and <span class="hlt">CO</span><span class="hlt">2</span> partial pressure difference at the area of Punta Morro in Ensenada, B. C., Mexico during the period from 13 April to 3 May of 2016. <span class="hlt">CO</span><span class="hlt">2</span> fluxes were measured at the coastline at a height of 10m by a flux measurement tower using eddy covariance method; in the sea, at a distance of approximately 1000m from the measuring tower, a <span class="hlt">CO</span><span class="hlt">2</span> sensor (Pro-Oceanus) was used to measure the <span class="hlt">CO</span><span class="hlt">2</span> partial pressures in air and sea water at a distance of approximately 2m of the surface. On the sea bottom at a depth of 10m and 400m from the coastline, a <span class="hlt">CO</span><span class="hlt">2</span> sensor (SAMI-<span class="hlt">CO</span><span class="hlt">2</span>) and acoustic profiler (Aquadopp, Nortek AS) were installed measuring <span class="hlt">CO</span><span class="hlt">2</span> partial pressure in the sea water and waves, respectively. The results show that <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> is not homogeneous in the study area, we were able to identify both horizontal and vertical gradients of p<span class="hlt">CO</span><span class="hlt">2</span> in the air and in sea water. Close to the sea surface, values of p<span class="hlt">CO</span><span class="hlt">2</span> in sea water were always smaller than there in air. The measured <span class="hlt">CO</span><span class="hlt">2</span> flux was in average negative during our field experiment. The air-sea transfer velocity of <span class="hlt">CO</span><span class="hlt">2</span> was obtained, resulting in a subtle relation with the significant wave height incident to the coast.This work is a RugDiSMar project (CONACYT 155793) contribution. Partial support from CB-2015-01-255377 is appreciated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.B33A0375F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.B33A0375F"><span>Plant Water Use Efficiency Response to the Atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">Concentration</span> is Greater in High Altitude Environments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Feng, X.; Wang, G.</p> <p>2009-12-01</p> <p>Intrinsic water-use efficiency of plants (A/g ratio, where A is <span class="hlt">CO</span><span class="hlt">2</span> assimilation rate and g is stomatal conductance of H2O) quantifies the amount of carbon assimilated per unit leaf area per unit time per unit cost of water. There has been a large body of work showing that intrinsic plant water use efficiency (WUE) <span class="hlt">increases</span> with <span class="hlt">increasing</span> atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>. This conclusion has strong implications for quantifying the effects of terrestrial carbon sequestration and plant transpiration under the condition of continuously <span class="hlt">increasing</span> anthropogenic <span class="hlt">CO</span><span class="hlt">2</span>. Less attention has been given to assessing whether the plant response to the atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">increase</span> differs as a function of environmental variables, such as temperature, precipitation and altitude. One would expect interactions between the <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> and other environmental variables, and the joint effects on the plant WUE might be different from the effect of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> alone. However, these interactions can be quite complicated and difficult to predict; even the sign of response remains uncertain. For example, one would expect that plants growing under a dry climate may benefit from the <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">increase</span> more than those under wet climate, and thus A would <span class="hlt">increase</span> more in a dry climate. Stomata density of leaves typically decreases with <span class="hlt">increasing</span> <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>, causing g to decrease, and A/g to <span class="hlt">increase</span>. However, it is not known if stomata density decreases more or less under dry or wet climate conditions. Similar uncertainties or lack of knowledge apply to temperature effects. In this work, we adopt an empirical approach using carbon isotopic ratios in tree rings. Over 50 tree-ring δ13C series are compiled from the literature. The response of δ13C to atmospheric conditions (<span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> and δ13C) is obtained, and the rates of change of the WUE are obtained at several different times between AD 1800 and 2000. These rates are then compared statistically with location’s mean annual</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25757312','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25757312"><span>[Effects of drought stress, high temperature and elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> on the growth of winter wheat].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Si, Fu-Yan; Qiao, Yun-Zhou; Jiang, Jing-Wei; Dong, Bao-Di; Shi, Chang-Hai; Liu, Meng-Yu</p> <p>2014-09-01</p> <p>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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>, ambient and elevated temperatures, and low and high water conditions independently and in combination. The <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>, elevated temperature, and drought significantly reduced the photosynthetic rate and water conditions, and led to a 41.4% decrease in grain yield. The elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> alone <span class="hlt">increased</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26226561','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26226561"><span><span class="hlt">CO</span><span class="hlt">2</span> pulse and acid-base status during <span class="hlt">increasing</span> work rate exercise in health and disease.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kisaka, Tomohiko; Cox, Timothy A; Dumitrescu, Daniel; Wasserman, Karlman</p> <p>2015-11-01</p> <p>The <span class="hlt">CO</span><span class="hlt">2</span> pulse (VCO2/heart rate), analogous to the O2 pulse (VO2/heart rate), was calculated during cardiopulmonary exercise testing and evaluated in normal and diseased states. Our aim was to define its application in its release in excess of that from VCO2/heart rate in the presence of impaired cardiovascular and lung function. In the current study, forty-five patients were divided into six physiological states: normal, exercise-induced myocardial ischemia, chronic heart failure, pulmonary vasculopathy, chronic obstructive pulmonary disease, and interstitial lung disease. We subtracted the O2 pulse from the <span class="hlt">CO</span><span class="hlt">2</span> pulse to determine the exhaled <span class="hlt">CO</span><span class="hlt">2</span> that could be attributed to <span class="hlt">CO</span><span class="hlt">2</span> pulse of buffering of lactic acid. The difference between the <span class="hlt">CO</span><span class="hlt">2</span> pulse and O2 pulse (VCO2/heart rate-VO2/heart rate) includes <span class="hlt">CO</span><span class="hlt">2</span> generated from HCO3(-) buffering of lactic acid. The accumulated <span class="hlt">CO</span><span class="hlt">2</span> per body mass was found to be significantly correlated with the corresponding [HCO3(-)] decrease (R(2)=0.72; P<0.0001). In summary, the <span class="hlt">increase</span> in <span class="hlt">CO</span><span class="hlt">2</span> pulse over the O2 pulse accounted for the anaerobically-generated excess-<span class="hlt">CO</span><span class="hlt">2</span> in each of the physiological states and correlated with the decreases in the arterial Bicarbonate <span class="hlt">concentration</span>. Copyright © 2015 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28075582','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28075582"><span>The Form in Which Nitrogen Is Supplied Affects the Polyamines, Amino Acids, and Mineral Composition of Sweet Pepper Fruit under an Elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">Concentration</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Piñero, Maria C; Otálora, Ginés; Porras, Manuel E; Sánchez-Guerrero, Mari C; Lorenzo, Pilar; Medrano, Evangelina; Del Amor, Francisco M</p> <p>2017-02-01</p> <p>We investigated the effect of supplying nitrogen, as NO3(-) or as NO3(-)/NH4(+), on the composition of fruits of sweet pepper (Capsicum annuum L. cv. Melchor) plants grown with different <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> ([<span class="hlt">CO</span><span class="hlt">2</span>]): ambient or elevated (800 μmol mol(-1)). The results show that the application of NH4(+) and high [<span class="hlt">CO</span><span class="hlt">2</span>] affected the chroma related to the <span class="hlt">concentrations</span> of chlorophylls. The <span class="hlt">concentrations</span> of Ca, Cu, Mg, P, and Zn were significantly reduced in the fruits of plants nourished with NH4(+), the loss of Fe being more dramatic at <span class="hlt">increased</span> [<span class="hlt">CO</span><span class="hlt">2</span>], which was also the case with the protein <span class="hlt">concentration</span>. The <span class="hlt">concentration</span> of total phenolics was <span class="hlt">increased</span> by NH4(+), being unaffected by [<span class="hlt">CO</span><span class="hlt">2</span>]. Globally, the NH4(+) was the main factor that affected fruit free amino acid <span class="hlt">concentrations</span>. Polyamines were affected differently: putrescine was <span class="hlt">increased</span> by elevated [<span class="hlt">CO</span><span class="hlt">2</span>], while the response of cadaverine depended on the form of N supplied.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.B11A0337B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.B11A0337B"><span>Responses of Plant Respiration to Pleistocene Changes in Atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">Concentrations</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Blanc-Betes, E.; Gonzalez-Meler, M.; Gomez-Casanovas, N.; Ward, J. K.</p> <p>2008-12-01</p> <p>Vegetation plays a crucial role on the terrestrial C cycling through the processes of photosynthesis and respiration. At a global scale, these two processes are essential components of the C cycle, because 30% to 70% of the <span class="hlt">CO</span><span class="hlt">2</span> fixed by photosynthesis is released back to the atmosphere each year by plant respiration. Therefore, small changes in these two fluxes can have a significant impact on atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>. Changes in <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> in the atmosphere have prompted plant evolutionary responses that have resulted in novel physiological photosynthetic adaptations such as the photosynthetic C oxidation pathway or the rise of C4-photosynthesis. However, little is known about the role of respiration on the nature of plant acclimation and adaptation to different <span class="hlt">CO</span><span class="hlt">2</span> scenarios when the photosynthesis-to-respiration ratio is low. Plant respiration is further complicated by the presence of the alternative pathway that burns photosynthate without producing chemical energy (ATP). Here, we explore the effects of Pleistocene levels of <span class="hlt">CO</span><span class="hlt">2</span> on plant respiration and on the activity of the alternative pathway. We <span class="hlt">concentrated</span> in plants that have a low photosynthesis-to-respiration ratio such as plants grown in shade and CAM plants, and on Arabidopsis thaliana plants that were selected at Pleistocene <span class="hlt">CO</span><span class="hlt">2</span> levels (200ppm), current (360ppm) and projected (680 ppm) atmospheric levels of <span class="hlt">CO</span><span class="hlt">2</span>. Our results, indicate that regardless of the overall respiration response to <span class="hlt">CO</span><span class="hlt">2</span> levels the activity of the alternative pathway was inversely correlated with atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> in all plants. Because alternative pathway activity is not coupled to ATP production and does not support maintenance or growth processes as effectively as normal respiration, plants exposed to Pleistocene <span class="hlt">CO</span><span class="hlt">2</span> levels will run respiration more efficiently than plants exposed to current or higher <span class="hlt">CO</span><span class="hlt">2</span> levels. The effectiveness of respiration can either play a survival role at low <span class="hlt">CO</span><span class="hlt">2</span> levels, or</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23080144','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23080144"><span>Time-course of ventilation, arterial and pulmonary <span class="hlt">CO</span>(<span class="hlt">2</span>) tension during <span class="hlt">CO</span> (<span class="hlt">2</span>) <span class="hlt">increase</span> in humans.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Satoh, Toru; Okada, Yasumasa; Hara, Yasushi; Sakamaki, Fumio; Kyotani, Shingo; Tomita, Takeshi; Nagaya, Noritoshi; Nakanishi, Norifumi</p> <p>2012-01-01</p> <p>A change of ventilation (VE), Pa<span class="hlt">CO</span>( <span class="hlt">2</span> ) (arterial <span class="hlt">CO</span>( <span class="hlt">2</span> ) tension) and Pv<span class="hlt">CO</span>( <span class="hlt">2</span> ) (pulmonary arterial <span class="hlt">CO</span>( <span class="hlt">2</span> ) tension) with time was not evaluated precisely during exercise or <span class="hlt">CO</span>( <span class="hlt">2</span> ) rebreathing in humans. In this study, changes of these variables with time were fitted to exponential curves {y = Exp ( x/ T + A ) + k} and compared. When exercise pulmonary hemodynamics was examined in 15 cardiac patients to decide therapies, we asked the patients to undergo <span class="hlt">CO</span>( <span class="hlt">2</span> ) rebreathing using air with supplementation of consumed O( 2 ). Arterial and pulmonary blood was drawn every minute. During exercise, T was 28.2 ± 8.4 and 26.8 ± 12.4, and A was 0.80 ± 0.50 and 0.50 ± 0.90 in VE and Pv<span class="hlt">CO</span>( <span class="hlt">2</span> ), respectively, with no statistical differences. During <span class="hlt">CO</span>( <span class="hlt">2</span> ) rebreathing, T was 18.6 ± 5.8, 41.8 ± 38.0 and 21.6 ± 9.7 and A was 0.39 ± 0.67, 1.64 ± 1.35 and 0.17 ± 0.83 in VE, Pa<span class="hlt">CO</span>( <span class="hlt">2</span> ) and Pv<span class="hlt">CO</span>( <span class="hlt">2</span> ), respectively, with statistical difference of Pa<span class="hlt">CO</span>( <span class="hlt">2</span> ) from other variables, suggesting that VE and Pv<span class="hlt">CO</span>( <span class="hlt">2</span> ) showed same mode of change according to time but Pa<span class="hlt">CO</span>( <span class="hlt">2</span> ) did not.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28926863','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28926863"><span>Evaluation of Cannabinoid and Terpenoid Content: Cannabis Flower Compared to Supercritical <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">Concentrate</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sexton, Michelle; Shelton, Kyle; Haley, Pam; West, Mike</p> <p>2017-09-19</p> <p>A recent cannabis use survey revealed that 60% of cannabis users rely on smelling the flower to select their cannabis. Olfactory indicators in plants include volatile compounds, principally represented by the terpenoid fraction. Currently, medicinal- and adult-use cannabis is marketed in the United States with relatively little differentiation between products other than by a common name, association with a species type, and Δ-9 tetrahydrocannabinol/cannabidiol potency. Because of this practice, how terpenoid compositions may change during an extraction process is widely overlooked. Here we report on a comparative study of terpenoid and cannabinoid potencies of flower and supercritical fluid <span class="hlt">CO</span><span class="hlt">2</span> (SC-<span class="hlt">CO</span><span class="hlt">2</span>) extract from six cannabis chemovars grown in Washington State. To enable this comparison, we employed a validated high-performance liquid chromatography/diode array detector methodology for quantification of seven cannabinoids and developed an internal gas chromatography-mass spectrometry method for quantification of 42 terpenes. The relative potencies of terpenoids and cannabinoids in flower versus <span class="hlt">concentrate</span> were significantly different. Cannabinoid potency <span class="hlt">increased</span> by factors of 3.2 for Δ-9 tetrahydrocannabinol and 4.0 for cannabidiol in <span class="hlt">concentrates</span> compared to flower. Monoterpenes were lost in the extraction process; a ketone <span class="hlt">increased</span> by 2.2; an ether by 2.7; monoterpene alcohols by 5.3, 7 and 9.4; and sesquiterpenes by 5.1, 4.2, 7.7, and 8.9. Our results demonstrate that the product of SC-<span class="hlt">CO</span><span class="hlt">2</span> extraction may have a significantly different chemotypic fingerprint from that of cannabis flower. These results highlight the need for more complete characterization of cannabis and associated products, beyond cannabinoid content, in order to further understand health-related consequences of inhaling or ingesting <span class="hlt">concentrated</span> forms. Georg Thieme Verlag KG Stuttgart · New York.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25985653','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25985653"><span>[Responses of non-structural carbohydrate metabolism of cucumber seedlings to drought stress and doubled <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dong, Yan-hong; Liu, Bin-bin; Zhang, Xu; Liu, Xue-na; Ai, Xi-zhen; Li, Qing-ming</p> <p>2015-01-01</p> <p>The effects of doubled <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> on non-structural carbohydrate metabolism of cucumber (Cucumis sativus L. cv. 'Jinyou No.1') seedlings under drought stress were investigated. Split plot design was deployed, with two levels of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> (ambient <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>, 380 µmol . mol-1, and doubled <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>, 760±20 µmol . mol-1) in the main plots, and three levels of water treatments (control, moderate drought stress, and severe drought stress) simulated by PEG 6000 in the split-plots. The results showed that non-structural carbohydrates of cucumber leaves, including glucose, fructose, sucrose, and stachyose, <span class="hlt">increased</span> with the doubling of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>, which resulted in the decreased osmotic potential, improving the drought stress in cucumber seedlings. During the drought stress, sucrose synthase, soluble acid invertase and al- kaline invertase started with an <span class="hlt">increase</span>, and followed with a decline in the leaves. In the root system, however, soluble acid invertase and alkaline invertase <span class="hlt">increased</span> gradually throughout the whole process, whereas sucrose phosphate synthase firstly <span class="hlt">increased</span> and then decreased. The treatment of doubled <span class="hlt">CO</span><span class="hlt">2</span> enhanced the activity of sucrose synthase, but decreased the activity of sucrose phosphate synthase. The synergistic action of the two enzymes and invertase accelerated the decomposition of sucrose and inhibited the synthesis of sucrose, leading to the accumulation of hexose, which lowered the cellular osmotic potential and enhanced the water uptake capacity. In conclusion, doubled <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> could alleviate the adverse effects of drought stress and improve the drought tolerance of cucumber seedlings. Such mitigating effect on cucumber was more significant under severe drought stress.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.A23N..02A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.A23N..02A"><span>Advances in Pulsed Lidar Measurements of <span class="hlt">CO</span><span class="hlt">2</span> Column <span class="hlt">Concentrations</span> from Aircraft and for Space</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Abshire, J. B.; Ramanathan, A. K.; Allan, G. R.; Hasselbrack, W. E.; Riris, H.; Numata, K.; Mao, J.; Sun, X.</p> <p>2016-12-01</p> <p>We have demonstrated an improved pulsed, multiple-wavelength integrated path differential absorption lidar for measuring the tropospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>. The lidar measures the range resolved shape of the 1572.33 nm <span class="hlt">CO</span><span class="hlt">2</span> absorption line to scattering surfaces, including the ground and the tops of clouds. Airborne measurements have used both 30 and 15 fixed wavelength samples distributed across the line. Analysis estimates the lidar range and pulse energies at each wavelength 10 times per second. The retrievals solve for the <span class="hlt">CO</span><span class="hlt">2</span> absorption line shape and the column average <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> by using radiative transfer calculations, the aircraft altitude and range to the scattering surface, and the atmospheric conditions. We compare these to <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> from in-situ sensors. In recent campaigns the lidar used a step-locked laser diode source, and a new HgCdTe APD detector in the receiver. During August and September 2014 the ASCENDS campaign flew over the California Central Valley, a coastal redwood forest, desert areas, and above growing crops in Iowa. Analyses show the retrievals of lidar range and <span class="hlt">CO</span><span class="hlt">2</span> column absorption, and mixing ratio worked well when measuring over variable topography and through thin clouds and aerosols. The retrievals clearly show the decrease in <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> over growing cropland. Airborne lidar measurements of horizontal gradients of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> across Nevada, Colorado and Nebraska showed good agreement with those from a model of <span class="hlt">CO</span><span class="hlt">2</span> flux and transport (PCTM). In several flights the agreement of the lidar with the column average <span class="hlt">concentration</span> was < 1ppm, with standard deviation of 0.9 ppm. Two additional flights were made in February 2016 using a larger laser spot size and an optimized receiver. These improved the sensitivity x3, and the retrievals show 0.7 ppm precision over the desert in 1 second averaging time. A summary of these results will be presented, along with on-going developments for a space version.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5299434','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5299434"><span>Responses of the marine diatom Thalassiosira pseudonana to changes in <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>: a proteomic approach</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Clement, Romain; Lignon, Sabrina; Mansuelle, Pascal; Jensen, Erik; Pophillat, Matthieu; Lebrun, Regine; Denis, Yann; Puppo, Carine; Maberly, Stephen C.; Gontero, Brigitte</p> <p>2017-01-01</p> <p>The <span class="hlt">concentration</span> of <span class="hlt">CO</span><span class="hlt">2</span> in many aquatic systems is variable, often lower than the KM of the primary carboxylating enzyme Rubisco, and in order to photosynthesize efficiently, many algae operate a facultative <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrating</span> mechanism (CCM). Here we measured the responses of a marine diatom, Thalassiosira pseudonana, to high and low <span class="hlt">concentrations</span> of <span class="hlt">CO</span><span class="hlt">2</span> at the level of transcripts, proteins and enzyme activity. Low <span class="hlt">CO</span><span class="hlt">2</span> caused many metabolic pathways to be remodeled. Carbon acquisition enzymes, primarily carbonic anhydrase, stress, degradation and signaling proteins were more abundant while proteins associated with nitrogen metabolism, energy production and chaperones were less abundant. A protein with similarities to the Ca2+/ calmodulin dependent protein kinase II_association domain, having a chloroplast targeting sequence, was only present at low <span class="hlt">CO</span><span class="hlt">2</span>. This protein might be a specific response to <span class="hlt">CO</span><span class="hlt">2</span> limitation since a previous study showed that other stresses caused its reduction. The protein sequence was found in other marine diatoms and may play an important role in their response to low <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>. PMID:28181560</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11295163','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11295163"><span>Stomatal density and stomatal index as indicators of paleoatmospheric <span class="hlt">CO</span>(<span class="hlt">2</span>) <span class="hlt">concentration</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Royer, D L.</p> <p>2001-03-01</p> <p>A growing number of studies use the plant species-specific inverse relationship between atmospheric <span class="hlt">CO</span>(<span class="hlt">2</span>) <span class="hlt">concentration</span> and stomatal density (SD) or stomatal index (SI) as a proxy for paleo-<span class="hlt">CO</span>(<span class="hlt">2</span>) levels. A total of 285 previously published SD and 145 SI responses to variable <span class="hlt">CO</span>(<span class="hlt">2</span>) <span class="hlt">concentrations</span> from a pool of 176 C(3) plant species are analyzed here to test the reliability of this method. The percentage of responses inversely responding to <span class="hlt">CO</span>(<span class="hlt">2</span>) rises from 40 and 36% (for SD and SI, respectively) in experimental studies to 88 and 94% (for SD and SI, respectively) in fossil studies. The inconsistent experimental responses verify previous concerns involving this method, however the high percentage of fossil responses showing an inverse relationship clearly validates the method when applied over time scales of similar length. Furthermore, for all groups of observations, a positive relationship between <span class="hlt">CO</span>(<span class="hlt">2</span>) and SD/SI is found in only </=12% of cases. Thus, <span class="hlt">CO</span>(<span class="hlt">2</span>) appears to inversely affect stomatal initiation, although the mechanism may involve genetic adaptation and therefore is often not clearly expressed under short <span class="hlt">CO</span>(<span class="hlt">2</span>) exposure times.Experimental responses of SD and SI based on open-top chambers (OTCs) inversely relate to <span class="hlt">CO</span>(<span class="hlt">2</span>) less often than greenhouse-based responses (P<0.01 for both SD and SI), and should be avoided when experimental responses are required for <span class="hlt">CO</span>(<span class="hlt">2</span>) reconstructions. In the combined data set, hypostomatous species follow the inverse relationship more often than amphistomatous species (56 vs. 44% for SD; 69 vs. 32% for SI; P<0.03 for both comparisons). Both the SD and SI of fossil responses are equally likely to inversely relate to <span class="hlt">CO</span>(<span class="hlt">2</span>) when exposed to elevated versus subambient <span class="hlt">CO</span>(<span class="hlt">2</span>) <span class="hlt">concentrations</span> (relative to today). This result casts doubt on previous claims that stomata cannot respond to <span class="hlt">CO</span>(<span class="hlt">2</span>) <span class="hlt">concentrations</span> above present-day levels. Although the proportion of SD and SI responses inversely relating to <span class="hlt">CO</span>(<span class="hlt">2</span>) are similar, SD is more</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.1581L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.1581L"><span>Rainfall distribution is the main driver of runoff under future <span class="hlt">CO</span><span class="hlt">2</span>-<span class="hlt">concentration</span> in a temperate deciduous forest</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Leuzinger, S.; Körner, C.</p> <p>2009-04-01</p> <p>Reduced stomatal conductance under elevated <span class="hlt">CO</span><span class="hlt">2</span> results in <span class="hlt">increased</span> soil moisture, provided all other factors remain constant. Whether this results in <span class="hlt">increased</span> 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 <span class="hlt">CO</span><span class="hlt">2</span>, 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 %) <span class="hlt">increased</span> ecosystem runoff under elevated <span class="hlt">CO</span><span class="hlt">2</span>. Out of the 37986 days (1.1.1901 to 31.12.2004), only 576 days produce higher runoff under in the elevated <span class="hlt">CO</span><span class="hlt">2</span> scenario. Only 1 out of 17 years produces a <span class="hlt">CO</span><span class="hlt">2</span>-signal greater than 20 mma-1, which mostly depends on a few single days when runoff under elevated <span class="hlt">CO</span><span class="hlt">2</span> exceeds runoff under ambient conditions. The maximum signal for a double pre-industrial <span class="hlt">CO</span><span class="hlt">2</span>-<span class="hlt">concentration</span> 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. <span class="hlt">Increased</span> runoff under elevated <span class="hlt">CO</span><span class="hlt">2</span> is 9 times more sensitive to variations in rain pattern than to the applied reduction in transpiration under elevated <span class="hlt">CO</span><span class="hlt">2</span>. Thus the key driver of <span class="hlt">increased</span> runoff under future <span class="hlt">CO</span><span class="hlt">2</span>-<span class="hlt">concentration</span> is the day by day rainfall pattern. We argue that <span class="hlt">increased</span> runoff due to a first-order plant physiological <span class="hlt">CO</span><span class="hlt">2</span>-effect will be very small (<3 %) in the landscape dominated by temperate deciduous forests, and will hardly <span class="hlt">increase</span> flooding risk in forest catchments. It is likely that these results are equally</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12836540','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12836540"><span>[Variation of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> in solar greenhouse in Northern China].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wei, Min; Xing, Yuxian; Wang, Xiufeng; Ma, Hong</p> <p>2003-03-01</p> <p>The variation of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> in winter-spring cultivated solar greenhouse in northern China was studied. The diurnal change of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> 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 <span class="hlt">concentration</span> of <span class="hlt">CO</span><span class="hlt">2</span> in solar greenhouse decreased gradually, while the daily minimum <span class="hlt">concentration</span> and daytime average <span class="hlt">concentration</span> dropped first, then went up. At the same time, the time of <span class="hlt">CO</span><span class="hlt">2</span> depletion lasted longer and longer. In December, <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> depletion. The period of <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> in greenhouse. Ventilation did not avoided <span class="hlt">CO</span><span class="hlt">2</span> depletion. Canopy photosynthetic rate and soil respiratory rate were measured at different growth stages of tomato. At seedling stage, <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> in greenhouse was higher than that outside, due to the vigorous soil respiration and lower canopy photosynthetic rate. But at fruiting stage, severe <span class="hlt">CO</span><span class="hlt">2</span> depletion occurred because of stronger canopy photosynthesis and weak</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23286998','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23286998"><span>Variation in the leaf δ(13)C is correlated with salinity tolerance under elevated <span class="hlt">CO</span>(<span class="hlt">2</span>) <span class="hlt">concentration</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>del Amor, Francisco M</p> <p>2013-02-15</p> <p><span class="hlt">Increasing</span> atmospheric <span class="hlt">CO</span>(<span class="hlt">2</span>) <span class="hlt">concentration</span> is expected to impact agricultural systems through a direct effect on leaf gas exchange and also due to effects on the global availability of good-quality water as a result of climate warming. Thus, the planning of land use for agriculture requires new tools to identify the capability of current cultivars to adapt to growth restrictions under new ambient conditions. We hypothesized that salinity stress may produce a specific pattern of carbon isotopic composition (δ(13)C) in tomato (Solanum lycopersicum L.) at elevated <span class="hlt">CO</span>(<span class="hlt">2</span>) <span class="hlt">concentration</span> ([<span class="hlt">CO</span>(<span class="hlt">2</span>)]) that could be used in the breeding of salinity tolerance in a near-future climate scenario. Five commercial tomato cultivars were evaluated at elevated (800 μmol mol(-1)) or standard (400 μmol mol(-1)) [<span class="hlt">CO</span>(<span class="hlt">2</span>)], being irrigated with a nutrient solution containing 0, 60 or 120 mM NaCl. The biomass enhanced ratio, leaf net <span class="hlt">CO</span>(<span class="hlt">2</span>) assimilation and stomatal conductance, leaf NO(3)(-) and Cl(-) <span class="hlt">concentrations</span> and leaf free amino acid profile were analyzed in relation to the pattern of δ(13)C, under different saline stress conditions. The results indicate that at high [<span class="hlt">CO</span>(<span class="hlt">2</span>)]: (i) salinity tolerance was enhanced, but the response was strongly cultivar dependent, (ii) leaf NO(3)(-) <span class="hlt">concentration</span> was <span class="hlt">increased</span> whilst Cl(-) and proline <span class="hlt">concentrations</span> decreased, and (iii) leaf δ(13)C was highly correlated with plant dry matter accumulation and with leaf proline <span class="hlt">concentration</span>, leaf gas exchange and ion <span class="hlt">concentrations</span>. This study shows that δ(13)C is a useful tool for the determination of the salinity tolerance of tomato at high [<span class="hlt">CO</span>(<span class="hlt">2</span>)], as an integrative parameter of the stress period, and was validated by traditional physiological plant stress traits. Copyright © 2012 Elsevier GmbH. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120011816','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120011816"><span>A 2-Micron Pulsed Integrated Path Differential Absorption Lidar Development For Atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">Concentration</span> Measurements</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yu, Jirong; Petros, Mulugeta; Reithmaier, Karl; Bai, Yingxin; Trieu, Bo C.; Refaat, Tamer F.; Kavaya, Michael J.; Singh, Upendra N.</p> <p>2012-01-01</p> <p>A 2-micron pulsed, Integrated Path Differential Absorption (IPDA) lidar instrument for ground and airborne atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> measurements via direct detection method is being developed at NASA Langley Research Center. This instrument will provide an alternate approach to measure atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.A21G0238M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.A21G0238M"><span>Quantification and modelling of on-road <span class="hlt">CO</span><span class="hlt">2</span> emissions and its impacts on ambient <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> in an Indian coastal city</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Madhipatla, K. K.</p> <p>2015-12-01</p> <p>This paper presents the results of <span class="hlt">CO</span><span class="hlt">2</span> emission inventory, monitoring of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> and modelling of on road <span class="hlt">CO</span><span class="hlt">2</span> emissions in an Indian coastal city. Bottom up approach was adopted for quantifying the grid wise on road <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> and vehicular traffic were carried out at a residential site in Chennai to understand the impact of vehicular emissions on the ambient <span class="hlt">CO</span><span class="hlt">2</span> levels. Further, AERMOD, a US EPA regulatory model, was deployed to find the spatial variation of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> due to the emissions from 38 major corridors of Chennai. Results indicated that a total emission of 0.65 Tg/year of <span class="hlt">CO</span><span class="hlt">2</span> was emitted by the vehicular traffic from the major roads of Chennai. Cars were identified as the larger emitters of <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> at the study area were in the range 391.52 to 666.37 ppm, with a mean hourly <span class="hlt">concentration</span> of 448 ± 33.45 ppm. It was observed that the <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> during the evening peak hours (R2=0.02). In addition, night time <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> per year to the ambient atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16608457','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16608457"><span>Enhancement of rice canopy carbon gain by elevated <span class="hlt">CO</span>(<span class="hlt">2</span>) is sensitive to growth stage and leaf nitrogen <span class="hlt">concentration</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sakai, H; Hasegawa, T; Kobayashi, K</p> <p>2006-01-01</p> <p><span class="hlt">Increasing</span> our understanding of the factors regulating seasonal changes in rice canopy carbon gain (C(gain): daily net photosynthesis -- night respiration) under elevated <span class="hlt">CO</span>(<span class="hlt">2</span>) <span class="hlt">concentrations</span> ([<span class="hlt">CO</span>(<span class="hlt">2</span>)]) will reduce our uncertainty in predicting future rice yields and assist in the development of adaptation strategies. In this study we measured <span class="hlt">CO</span>(<span class="hlt">2</span>) exchange from rice (Oryza sativa) canopies grown at c. 360 and 690 micromol mol(-1)[<span class="hlt">CO</span>(<span class="hlt">2</span>)] in growth chambers continuously over three growing seasons. Stimulation of C(gain) by elevated [<span class="hlt">CO</span>(<span class="hlt">2</span>)] was 22-79% during vegetative growth, but decreased to between -12 and 5% after the grain-filling stage, resulting in a 7-22% net enhancement for the whole season. The decreased stimulation of C(gain) resulted mainly from decreased canopy net photosynthesis and partially from <span class="hlt">increased</span> respiration. A decrease in canopy photosynthetic capacity was noted where leaf nitrogen (N) decreased. The effect of elevated [<span class="hlt">CO</span>(<span class="hlt">2</span>)] on leaf area was generally small, but most dramatic under ample N conditions; this <span class="hlt">increased</span> the stimulation of whole-season C(gain). These results suggest that a decrease in C(gain) enhancement following elevated <span class="hlt">CO</span>(<span class="hlt">2</span>) levels is difficult to avoid, but that careful management of nitrogen levels can alter the whole-season C(gain) enhancement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.B51C0327U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.B51C0327U"><span>Estimation of regional <span class="hlt">CO</span><span class="hlt">2</span> fluxes in northern Wisconsin using the ring of towers <span class="hlt">concentration</span> measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Uliasz, M.; Denning, A. S.; Corbin, K.; Miles, N.; Richardson, S.; Davis, K.</p> <p>2006-12-01</p> <p>The WLEF TV tower in northern Wisconsin is instrumented to take continuous measurements of <span class="hlt">CO</span><span class="hlt">2</span> mixing ratio at 6 levels from 11 to 396m. During the spring and summer of 2004 additional <span class="hlt">CO</span><span class="hlt">2</span> measurements were deployed on five 76 m communication towers forming a ring around the WLEF tower with a 100-150 km radius. The data from the ring of towers are being used to estimate regional fluxes of <span class="hlt">CO</span><span class="hlt">2</span>. The modeling framework developed for this purpose is based on SiB-RAMS: Regional Atmospheric Modeling System linked to Simple Biosphere model. The RAMS domain extends over the entire continental US with nested grids centered in northern Wisconsin. The <span class="hlt">CO</span><span class="hlt">2</span> lateral boundary conditions are provided by a global transport model PCTM (Parameterized Chemistry and Transport Model). This model system is capable to realistically reproduce diurnal cycle of <span class="hlt">CO</span><span class="hlt">2</span> fluxes as well as their spatial patterns in regional scale related to different vegetation types. However, there is still significant uncertainty in simulating atmospheric transport of <span class="hlt">CO</span><span class="hlt">2</span> due to synoptic and mesoscale circulations. We are attempting to assimilate available <span class="hlt">CO</span><span class="hlt">2</span> tower data into our modeling system in order to provide corrections for the fluxes simulated by the SiB-RAMS. These corrections applied separately to respiration and assimilation fluxes have spatial patterns but are assumed constant in time during a period of 10 days. Another correction is estimated for the <span class="hlt">CO</span><span class="hlt">2</span> inflow <span class="hlt">concentration</span> entering the regional domain. The <span class="hlt">CO</span><span class="hlt">2</span> data assimilation is based the Lagrangian Particle Dispersion (LPD) model and the Bayessian inversion technique. The LPD model is driven by meteorological fields from the SiB-RAMS and is used for a regional domain in its adjoint mode to trace particles backward in time to derive influence functions for each <span class="hlt">concentration</span> sample. The influence functions provide information on potential contributions both from surface sources and inflow fluxes that make their way through the modeling domain</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1075114','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1075114"><span>Changes of Ribulose Bisphosphate Carboxylase/Oxygenase Content, Ribulose Bisphosphate <span class="hlt">Concentration</span>, and Photosynthetic Activity during Adaptation of High-<span class="hlt">CO</span><span class="hlt">2</span> Grown Cells to Low-<span class="hlt">CO</span><span class="hlt">2</span> Conditions in Chlorella pyrenoidosa1</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Yokota, Akiho; Canvin, David T.</p> <p>1986-01-01</p> <p>Changes of some photosynthetic properties of high-<span class="hlt">CO</span><span class="hlt">2</span> grown cells of Chlorella pyrenoidosa during adaptation to low-<span class="hlt">CO</span><span class="hlt">2</span> conditions have been investigated. The Km value of photosynthesis of the high-<span class="hlt">CO</span><span class="hlt">2</span> grown cells for dissolved inorganic carbon was 3.3 millimolar and decreased to 25 to 30 micromolar within 4 hours after transferring to air. In the presence of saturating <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> the photosynthetic activity of the high-<span class="hlt">CO</span><span class="hlt">2</span> grown cells was 1.5 times as high as that of the low-<span class="hlt">CO</span><span class="hlt">2</span> grown cells. There was a significant rise of the photosynthetic activity during adaptation of the high-<span class="hlt">CO</span><span class="hlt">2</span> grown cells to air, followed by a steady decrease. The activity of ribulose 1,5-bisphosphate carboxylase/oxygenase in both the high- and low-<span class="hlt">CO</span><span class="hlt">2</span> grown cells was close to the photosynthetic activity of the cells. The <span class="hlt">concentration</span> of ribulose 1,5-bisphosphate (RuBP) was higher in the low-<span class="hlt">CO</span><span class="hlt">2</span> adapting and low-<span class="hlt">CO</span><span class="hlt">2</span> grown cells than in the high-<span class="hlt">CO</span><span class="hlt">2</span> grown cells regardless of the photosynthetic rate. This seems to be due to an <span class="hlt">increased</span> RuBP regeneration activity during adaptation followed by maintenance of the new higher <span class="hlt">concentration</span>. The RuBP level always exceeded the <span class="hlt">concentration</span> of ribulose 1,5-bisphosphate carboxylase/oxygenase RuBP binding sites in both the high- and low-<span class="hlt">CO</span><span class="hlt">2</span> grown cells at any dissolved inorganic carbon <span class="hlt">concentration</span>. PMID:16664623</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016IJBm...60..727X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016IJBm...60..727X"><span>Changes in the activities of starch metabolism enzymes in rice grains in response to elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xie, Li-Yong; Lin, Er-Da; Zhao, Hong-Liang; Feng, Yong-Xiang</p> <p>2016-05-01</p> <p>The global atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> is currently (2012) 393.1 μmol mol-1, an <span class="hlt">increase</span> of approximately 42 % over pre-industrial levels. In order to understand the responses of metabolic enzymes to elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>, an experiment was conducted using the Free Air <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> on the amylose and protein contents of the grains were analyzed. The results showed that elevated <span class="hlt">CO</span><span class="hlt">2</span> levels significantly <span class="hlt">increased</span> the activity of ADPG pyrophosphorylase at day 8, 24, and 40 after flower, with maximum <span class="hlt">increases</span> of 56.67 % for Songjing 9 and 21.31 % for Daohuaxiang 2. Similarly, the activities of starch synthesis enzymes <span class="hlt">increased</span> significantly from the day 24 after flower to the day 40 after flower, with maximum <span class="hlt">increases</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> significantly <span class="hlt">increased</span> the activity of soluble starch branching enzyme (SSBE) at day 16, 32, and 40 after flower, and also significantly <span class="hlt">increased</span> the activity of granule-bound starch branching enzyme (GBSBE) at day 8, 32, and 40 after flower. The elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> <span class="hlt">increased</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> <span class="hlt">increased</span> enzyme activity expression and starch synthesis, affecting the final contents</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26433368','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26433368"><span>Changes in the activities of starch metabolism enzymes in rice grains in response to elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xie, Li-Yong; Lin, Er-Da; Zhao, Hong-Liang; Feng, Yong-Xiang</p> <p>2016-05-01</p> <p>The global atmospheric <span class="hlt">CO</span>(<span class="hlt">2</span>) <span class="hlt">concentration</span> is currently (2012) 393.1 μmol mol(-1), an <span class="hlt">increase</span> of approximately 42 % over pre-industrial levels. In order to understand the responses of metabolic enzymes to elevated <span class="hlt">CO</span>(<span class="hlt">2</span>) <span class="hlt">concentrations</span>, an experiment was conducted using the Free Air <span class="hlt">CO</span>(<span class="hlt">2</span>) 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 <span class="hlt">CO</span>(<span class="hlt">2</span>) on the amylose and protein contents of the grains were analyzed. The results showed that elevated <span class="hlt">CO</span>(<span class="hlt">2</span>) levels significantly <span class="hlt">increased</span> the activity of ADPG pyrophosphorylase at day 8, 24, and 40 after flower, with maximum <span class="hlt">increases</span> of 56.67 % for Songjing 9 and 21.31 % for Daohuaxiang 2. Similarly, the activities of starch synthesis enzymes <span class="hlt">increased</span> significantly from the day 24 after flower to the day 40 after flower, with maximum <span class="hlt">increases</span> 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 <span class="hlt">CO</span>(<span class="hlt">2</span>) <span class="hlt">concentration</span> significantly <span class="hlt">increased</span> the activity of soluble starch branching enzyme (SSBE) at day 16, 32, and 40 after flower, and also significantly <span class="hlt">increased</span> the activity of granule-bound starch branching enzyme (GBSBE) at day 8, 32, and 40 after flower. The elevated <span class="hlt">CO</span>(<span class="hlt">2</span>) <span class="hlt">concentration</span> <span class="hlt">increased</span> 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 <span class="hlt">CO</span>(<span class="hlt">2</span>) <span class="hlt">concentration</span> <span class="hlt">increased</span> enzyme activity expression and starch synthesis, affecting the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUSM.A31C..04V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUSM.A31C..04V"><span>Effect of urban parks on <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> in Toluca, Mexico</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vieyra Gómez, J. A.; González Sosa, E.; Mastachi-Loza, C. A.; Cervantes, M.; Martínez Valdéz, H.</p> <p>2013-05-01</p> <p>Despite green areas are used for amusement, they have several benefits such as: microclimate regulation, groundwater recharge, noise abatement, oxygen production and <span class="hlt">CO</span><span class="hlt">2</span> capture. The last one has a notable importance, as <span class="hlt">CO</span><span class="hlt">2</span> is considered to be one of the most pollutant gases of the greenhouse effect. The city of Toluca, has a considerable urban growth. However, there are few studies aimed to assess the importance of the green areas in urban locations. About this, it is estimated than only 4m2/hab of vegetal coverage is found in big cities, which means a 50% deficit according to the international standards.The aim of this study was to assess the urban parks impact in Toluca, as regulators of <span class="hlt">CO</span><span class="hlt">2</span> means through measurements in autumn-winter seasonal period, 2012-2013.It was performed 20 measurements in 4 local parks (Urawa, Alameda, Municipal and Metropolitano), in order to evaluate the possible effect of urban parks on <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>. Transects were made inside and outside the parks and the <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> were registered by a portable quantifier (GMP343).The data analysis allowed the separation of the parks based on <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>; however, it was perceived a decreasing of <span class="hlt">CO</span><span class="hlt">2</span> inside the parks (370ppm), between 10 and 40 ppm less than those areas with traffic and pedestrians (399 ppm).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AtmEn..74...60L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AtmEn..74...60L"><span>Variability of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> and fluxes in and above an urban street canyon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lietzke, Björn; Vogt, Roland</p> <p>2013-08-01</p> <p>The variability of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> 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 <span class="hlt">CO</span><span class="hlt">2</span>-exchange processes, measurements were conducted in a street canyon in the city of Basel, Switzerland in 2010. <span class="hlt">CO</span><span class="hlt">2</span> fluxes were sampled at the top of the canyon (19 m) and at 39 m while vertical <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> profiles were measured in the center and at a wall of the canyon. <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">CO</span><span class="hlt">2</span>-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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.B21A0440S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.B21A0440S"><span>Carbon Flux Estimated from <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">Concentration</span> using Half Order Derivative Method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shahnaz, S.; Wang, J.</p> <p>2013-12-01</p> <p>The object of this study is to test the half-order derivative method for estimating carbon flux from <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> time series data at single level near the surface. When the transport process is described by a diffusion equation, carbon flux may be expressed as a weighted average of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> time-series known as half-order time derivative. <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> and flux data collected from Ameriflux network at 10 sites in USA, Canada, Mexico and Brazil were used in this study. The preliminary results show good agreement between the modeled and observed <span class="hlt">CO</span><span class="hlt">2</span> flux during growing seasons. The study suggests that the half order derivative method is a useful tool in monitoring global carbon budget as direct measurements of carbon flux over extensive regions are limited.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1394545','SCIGOV-DOEDE'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1394545"><span>Atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">Concentrations</span>--The Canadian Background Air Pollution Monitoring Network (1993)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/dataexplorer">DOE Data Explorer</a></p> <p>Trivett, N. B. A.; Hudec, V. C.; Wong, C. S.</p> <p>1993-01-01</p> <p>Flask air samples collected at roughly weekly intervals at three Canadian sites [Alert, Northwest Territories (July 1975 through July 1992); Sable Island, Nova Scotia (March 1975 through July 1992); and Cape St. James, British Columbia (May 1979 through July 1992)] were analyzed for <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> with the measurements directly traceable to the WMO primary <span class="hlt">CO</span><span class="hlt">2</span> standards. Each record includes the date, atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>, and flask classification code. They provide an accurate record of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> levels in Canada during the past two decades. Because these data are directly traceable to WMO standards, this record may be compared with records from other Background Air Pollution Monitoring Network (BAPMoN) stations. The data are in three files (one for each of the monitoring stations) ranging in size from 9.4 to 20.1 kB.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGC51D0991R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGC51D0991R"><span>Coupling Between the Changes in <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">Concentration</span> and Sediment Biogeochemistry in the Salinas De San Pedro Mudflat, California, USA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rezaie Boroon, M.; Diaz, S.; Torres, V.; Lazzaretto, T.; Dehyn, D.</p> <p>2013-12-01</p> <p>We investigated the effects of elevated carbon dioxide [<span class="hlt">CO</span><span class="hlt">2</span>] 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 <span class="hlt">CO</span><span class="hlt">2</span> were identified as atmospheric <span class="hlt">CO</span><span class="hlt">2</span> as well as due to local fault degassing process. We measured carbon dioxide [<span class="hlt">CO</span><span class="hlt">2</span>], methane [CH4], total organic carbon, dissolved oxygen, salinity, and heavy metal <span class="hlt">concentration</span> in various salt marsh locations. Overall, our results showed that <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> ranging from 418.7 to 436.9 [ppm], which are slightly different in various chambers but are in good agreement with some heavy metal <span class="hlt">concentrations</span> values in mudflat at or around the same location. The selected metal <span class="hlt">concentration</span> 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, <span class="hlt">CO</span><span class="hlt">2</span> [ppm] and loss on ignition (LOI) [%] correlated inversely; the higher <span class="hlt">CO</span><span class="hlt">2</span> content, the lower was the LOI; that is to say the excess <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> not only is a sign of improvement in plant productivity, but also activates microbial decomposition through <span class="hlt">increases</span> in dissolved organic carbon availability. <span class="hlt">CO</span><span class="hlt">2</span> also <span class="hlt">increases</span> acidification processes such as anaerobic degradation of microorganism and oxidation of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFM.B23A0926H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.B23A0926H"><span>Boundary-layer measurements of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>, carbon and oxygen isotopes of atmospheric <span class="hlt">CO</span><span class="hlt">2</span> over montane forest regions in Colorado, USA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, J.; Lai, C.; Stephens, B.; Ehleringer, J.; Monson, R.; Schimel, D.</p> <p>2004-12-01</p> <p>Air samples were collected with 100ml flasks in the atmospheric and canopy boundary layers using aircraft and ground-based samplers as an integral part of the Airborne Carbon in the Mountains Experiment (ACME) in May and July 2004. A total number of 524 flasks were collected during the two study periods for the analyses of <span class="hlt">concentration</span>, carbon (\\delta13C) and oxygen (\\delta18O) isotopes of atmospheric <span class="hlt">CO</span><span class="hlt">2</span>. Air samples were collected in the early morning (beginning ~ 7:00 am) using a C-130 airplane to characterize regional-scale isotopic signals of respiration (\\delta13CR) in the residual boundary layer. As the ground heated after sunrise and the convective boundary layer (CBL) <span class="hlt">increased</span>, flasks were collected again to estimate isotope ratios of net <span class="hlt">CO</span><span class="hlt">2</span> exchange between the atmosphere and the biosphere. In addition, vertical profiles of atmospheric <span class="hlt">CO</span><span class="hlt">2</span>, \\delta13C and \\delta18O in the CBL were measured with the aircraft. Two automated sampling systems conducted the ground-based sampling. The first sampled at 15-min intervals the night before a flight (9:00 pm to 12:30 am). These measurements were conducted within forest canopies and were used to capture \\delta13C ratios of nighttime respiration at the ecosystem scale. The second was programmed to sample every 45 minutes and started approximately two hours before the airborne flights (4:30 am to 3:00 pm). These measurements overlapped aircraft observations, providing information about daytime <span class="hlt">CO</span><span class="hlt">2</span> exchange in the atmosphere-forest interface. Preliminary results showed that a <span class="hlt">CO</span><span class="hlt">2</span> gradient of 27.9 ppm with a corresponding \\delta13C difference of 1.16 \\permil was captured in the residual boundary layer on a July morning. Using a two-source mixing line approach, the regional-scale \\delta13CR was estimated to be -24.5 \\pm 0.4 (S.E.) \\permil, which was significantly (p < 0.05) more positive compared to measured nighttime /delta13CR values within the forest canopy (-25.7 \\pm 0.1 \\permil). This difference</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.B13B0514H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.B13B0514H"><span>Different behavior of an Earth system model toward four <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> scenarios</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hajima, T.; Ise, T.; Tachiiri, K.; Kato, E.; Watanabe, S.; Kawamiya, M.</p> <p>2012-12-01</p> <p>Earth system models (ESMs) have been developed to understand the mechanisms of long-term climate change with carbon cycle feedbacks. In this study, past simulations (1850-2005) and projection experiments (2006 to 2100) were conducted using an ESM named "MIROC-ESM", forced by four representative <span class="hlt">concentration</span> pathway (RCP) scenarios that describe how anthropogenic forcing such as greenhouse gases (GHGs), aerosols, and land-use will develop in the future. The main purpose of this study is to explore the mechanisms of the Earth system differently responding to the scenarios. We found that climate response to the <span class="hlt">increase</span> of atmospheric carbon showed large variation among scenarios, strongly affected by ocean heat uptake efficiency as well as anthropogenic forcing. Large variation among scenarios was also found in carbon cycle sensitivity measured by cumulative airborne fraction. The variation of carbon cycle sensitivity can be explained by Land-use change scenarios, and may be attributable to the dependence of <span class="hlt">concentration</span>-carbon feedback on the rate of atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">increase</span>. The earth system would show a similar response to emitted carbon during the 21st century if the difference of ocean heat uptake efficiency and variation of radiative forcing from non-<span class="hlt">CO</span><span class="hlt">2</span> anthropogenic agents among scenarios were small.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.4059B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.4059B"><span>Monitoring <span class="hlt">CO</span><span class="hlt">2</span> and CH4 <span class="hlt">concentrations</span> along an urban-rural transect in London, UK</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Boon, Alex; Broquet, Gregoire; Clifford, Debbie; Chevallier, Frederic; Butterfield, David</p> <p>2013-04-01</p> <p>Cities are important sources of carbon dioxide (<span class="hlt">CO</span><span class="hlt">2</span>) and methane (CH4). Anthropogenic <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">concentrations</span> is crucial for cities aiming to reduce emissions through measures such as changes to the transport infrastructure and green planning. We present measurements of <span class="hlt">CO</span><span class="hlt">2</span> and CH4 <span class="hlt">concentrations</span> 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 <span class="hlt">concentrations</span> across an urban to rural 'transect'. The CHIMERE chemistry-transport model is used to estimate <span class="hlt">CO</span><span class="hlt">2</span> and CH4 <span class="hlt">concentrations</span> throughout the four month measurement period during the summer of 2012. Comparisons are made between the measured and modelled <span class="hlt">CO</span><span class="hlt">2</span> and CH4 <span class="hlt">concentrations</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> sources.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Natur.542..169F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Natur.542..169F"><span>Climate science: Ocean circulation drove <span class="hlt">increase</span> in <span class="hlt">CO</span><span class="hlt">2</span> uptake</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fletcher, Sara E. Mikaloff</p> <p>2017-02-01</p> <p>The ocean's uptake of carbon dioxide <span class="hlt">increased</span> during the 2000s. Models reveal that this was driven primarily by weak circulation in the upper ocean, solving a mystery of ocean science. See Letter p.215</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008BGeo....5..407V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008BGeo....5..407V"><span>Dynamics of dimethylsulphoniopropionate and dimethylsulphide under different <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> during a mesocosm experiment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vogt, M.; Steinke, M.; Turner, S.; Paulino, A.; Meyerhöfer, M.; Riebesell, U.; Lequéré, C.; Liss, P.</p> <p>2008-03-01</p> <p>The potential impact of seawater acidification on the <span class="hlt">concentrations</span> of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP), and the activity of the enzyme DMSP-lyase was investigated during a pelagic ecosystem <span class="hlt">CO</span><span class="hlt">2</span> enrichment experiment (PeECE III) in spring 2005. Natural phytoplankton blooms were studied for 24 days under present, double and triple partial pressures of <span class="hlt">CO</span><span class="hlt">2</span> (p<span class="hlt">CO</span><span class="hlt">2</span>; pH=8.3, 8.0, 7.8) in triplicate 25 m3 enclosures. The results indicate similar DMSP <span class="hlt">concentrations</span> and DMSP-lyase activity (DLA) patterns for all treatments. Hence, DMSP and DLA do not seem to have been affected by the <span class="hlt">CO</span><span class="hlt">2</span> treatment. In contrast, DMS <span class="hlt">concentrations</span> showed small but statistically significant differences in the temporal development of the low versus the high <span class="hlt">CO</span><span class="hlt">2</span> treatments. The low p<span class="hlt">CO</span><span class="hlt">2</span> enclosures had higher DMS <span class="hlt">concentrations</span> during the first 10 days, after which the levels decreased earlier and more rapidly than in the other treatments. Integrated over the whole study period, DMS <span class="hlt">concentrations</span> were not significantly different from those of the double and triple p<span class="hlt">CO</span><span class="hlt">2</span> treatments. Pigment and flow-cytometric data indicate that phytoplanktonic populations were generally similar between the treatments, suggesting a certain resilience of the marine ecosystem under study to the induced pH changes, which is reflected in DMSP and DLA. However, there were significant differences in bacterial community structure and the abundance of one group of viruses infecting nanoeukaryotic algae. The amount of DMS accumulated per total DMSP or chlorophyll-a differed significantly between the present and future scenarios, suggesting that the pathways for DMS production or bacterial DMS consumption were affected by seawater pH. A comparison with previous work (PeECE II) suggests that DMS <span class="hlt">concentrations</span> do not respond consistently to pelagic ecosystem <span class="hlt">CO</span><span class="hlt">2</span> enrichment experiments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4029897','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4029897"><span>Interactive Effects of Elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">Concentration</span> and Irrigation on Photosynthetic Parameters and Yield of Maize in Northeast China</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Meng, Fanchao; Zhang, Jiahua; Yao, Fengmei; Hao, Cui</p> <p>2014-01-01</p> <p>Maize is one of the major cultivated crops of China, having a central role in ensuring the food security of the country. There has been a significant <span class="hlt">increase</span> in studies of maize under interactive effects of elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> ([<span class="hlt">CO</span><span class="hlt">2</span>]) and other factors, yet the interactive effects of elevated [<span class="hlt">CO</span><span class="hlt">2</span>] and <span class="hlt">increasing</span> precipitation on maize has remained unclear. In this study, a manipulative experiment in Jinzhou, Liaoning province, Northeast China was performed so as to obtain reliable results concerning the later effects. The Open Top Chambers (OTCs) experiment was designed to control contrasting [<span class="hlt">CO</span><span class="hlt">2</span>] i.e., 390, 450 and 550 µmol·mol−1, and the experiment with 15% <span class="hlt">increasing</span> precipitation levels was also set based on the average monthly precipitation of 5–9 month from 1981 to 2010 and controlled by irrigation. Thus, six treatments, i.e. C550W+15%, C550W0, C450W+15%, C450W0, C390W+15% and C390W0 were included in this study. The results showed that the irrigation under elevated [<span class="hlt">CO</span><span class="hlt">2</span>] levels <span class="hlt">increased</span> the leaf net photosynthetic rate (Pn) and intercellular <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> (Ci) of maize. Similarly, the stomatal conductance (Gs) and transpiration rate (Tr) decreased with elevated [<span class="hlt">CO</span><span class="hlt">2</span>], but irrigation have a positive effect on <span class="hlt">increased</span> of them at each [<span class="hlt">CO</span><span class="hlt">2</span>] level, resulting in the water use efficiency (WUE) higher in natural precipitation treatment than irrigation treatment at elevated [<span class="hlt">CO</span><span class="hlt">2</span>] levels. Irradiance-response parameters, e.g., maximum net photosynthetic rate (Pnmax) and light saturation points (LSP) were <span class="hlt">increased</span> under elevated [<span class="hlt">CO</span><span class="hlt">2</span>] and irrigation, and dark respiration (Rd) was <span class="hlt">increased</span> as well. The growth characteristics, e.g., plant height, leaf area and aboveground biomass were enhanced, resulting in an improved of yield and ear characteristics except axle diameter. The study concluded by reporting that, future elevated [<span class="hlt">CO</span><span class="hlt">2</span>] may favor to maize when coupled with <span class="hlt">increasing</span> amount of precipitation in Northeast China. PMID:24848097</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24848097','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24848097"><span>Interactive effects of elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> and irrigation on photosynthetic parameters and yield of maize in Northeast China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Meng, Fanchao; Zhang, Jiahua; Yao, Fengmei; Hao, Cui</p> <p>2014-01-01</p> <p>Maize is one of the major cultivated crops of China, having a central role in ensuring the food security of the country. There has been a significant <span class="hlt">increase</span> in studies of maize under interactive effects of elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> ([<span class="hlt">CO</span><span class="hlt">2</span>]) and other factors, yet the interactive effects of elevated [<span class="hlt">CO</span><span class="hlt">2</span>] and <span class="hlt">increasing</span> precipitation on maize has remained unclear. In this study, a manipulative experiment in Jinzhou, Liaoning province, Northeast China was performed so as to obtain reliable results concerning the later effects. The Open Top Chambers (OTCs) experiment was designed to control contrasting [<span class="hlt">CO</span><span class="hlt">2</span>] i.e., 390, 450 and 550 µmol·mol(-1), and the experiment with 15% <span class="hlt">increasing</span> precipitation levels was also set based on the average monthly precipitation of 5-9 month from 1981 to 2010 and controlled by irrigation. Thus, six treatments, i.e. C550W+15%, C550W0, C450W+15%, C450W0, C390W+15% and C390W0 were included in this study. The results showed that the irrigation under elevated [<span class="hlt">CO</span><span class="hlt">2</span>] levels <span class="hlt">increased</span> the leaf net photosynthetic rate (Pn) and intercellular <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> (Ci) of maize. Similarly, the stomatal conductance (Gs) and transpiration rate (Tr) decreased with elevated [<span class="hlt">CO</span><span class="hlt">2</span>], but irrigation have a positive effect on <span class="hlt">increased</span> of them at each [<span class="hlt">CO</span><span class="hlt">2</span>] level, resulting in the water use efficiency (WUE) higher in natural precipitation treatment than irrigation treatment at elevated [<span class="hlt">CO</span><span class="hlt">2</span>] levels. Irradiance-response parameters, e.g., maximum net photosynthetic rate (Pnmax) and light saturation points (LSP) were <span class="hlt">increased</span> under elevated [<span class="hlt">CO</span><span class="hlt">2</span>] and irrigation, and dark respiration (Rd) was <span class="hlt">increased</span> as well. The growth characteristics, e.g., plant height, leaf area and aboveground biomass were enhanced, resulting in an improved of yield and ear characteristics except axle diameter. The study concluded by reporting that, future elevated [<span class="hlt">CO</span><span class="hlt">2</span>] may favor to maize when coupled with <span class="hlt">increasing</span> amount of precipitation in Northeast China.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JCrGr.469...36T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JCrGr.469...36T"><span>Effects of <span class="hlt">CO</span><span class="hlt">2</span> fine bubble injection on reactive crystallization of dolomite from <span class="hlt">concentrated</span> brine</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tsuchiya, Yuko; Wada, Yoshinari; Hiaki, Toshihiko; Onoe, Kaoru; Matsumoto, Masakazu</p> <p>2017-07-01</p> <p>In this study, we used the minute gas-liquid interfaces around <span class="hlt">CO</span><span class="hlt">2</span> fine bubbles as new reaction fields where the crystal nucleation proceeds dominantly and developed a crystallization technique to synthesize dolomite (CaMg(CO3)2) with the desired crystal quality. CaMg(CO3)2 has a crystal structure derived from calcite by ordered replacement of the Ca2+ in calcite by Mg2+. To improve the functionality of the crystal for better utilization of the CaMg(CO3)2, an effective method for an approach to a Mg/Ca ratio of 1.0 and downsizing is indispensable in the crystallization process. In the vicinity of the minute gas-liquid interfaces, the accumulation of Ca2+ and Mg2+ is caused by the negative electric charge on the fine bubbles surface; thus, CaMg(CO3)2 fine particles with a high Mg/Ca ratio can be expected to crystallize. At a reaction temperature (Tr) of 298 K and <span class="hlt">CO</span><span class="hlt">2</span> flow rate (FCO2) of 11.9 mmol/(L min), <span class="hlt">CO</span><span class="hlt">2</span> bubbles with an average bubble diameter (dbbl) of 40-2000 μm were continuously supplied to 300 mL of the <span class="hlt">concentrated</span> brine coming from salt manufacture discharge and CaMg(CO3)2 crystallized within a reaction time of 120 min. Fine bubbles with dbbl of 40 μm were generated using a self-supporting bubble generator by <span class="hlt">increasing</span> the impeller shear rate under reduced pressure. For comparison, the bubbles with dbbl of 300 or 2000 μm were obtained using a dispersing-type generator. Moreover, FCO2 and Tr were varied as operating parameters during the reactive crystallization supplying <span class="hlt">CO</span><span class="hlt">2</span> fine bubbles. Consequently, <span class="hlt">CO</span><span class="hlt">2</span> fine bubble injection is effective for the high-yield crystallization of CaMg(CO3)2 with a Mg/Ca ratio of 1.0 and downsizing of CaMg(CO3)2 particles owing to the acceleration of crystal nucleation caused by the local <span class="hlt">increase</span> in the supersaturation at the minute gas-liquid interfaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.B21K..04C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.B21K..04C"><span>The Influence of Atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">Concentration</span> and Climate Variability on Amazon Tropical Forest</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Castanho, A. D. D. A.; Galbraith, D.; Zhang, K.; Coe, M. T.; Costa, M. H.; Moorcroft, P. R.</p> <p>2014-12-01</p> <p>Tropical forests are important regulators of atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> 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 <span class="hlt">increase</span> in aboveground biomass in the last decades, and the <span class="hlt">increase</span> in atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> 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) <span class="hlt">increase</span> in biomass in undisturbed tropical forest in Amazonia could be attributed to the <span class="hlt">CO</span><span class="hlt">2</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ESASP.724...70X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ESASP.724...70X"><span>Measurement of <span class="hlt">Concentration</span> of <span class="hlt">CO</span><span class="hlt">2</span> in Atmosphere In Situ Based on TDLAS</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xin, Fengxin; Guo, Jinjia; Chen, Zhen; Liu, Zhishen</p> <p>2014-11-01</p> <p>As one of the main greenhouse gases in the atmosphere, <span class="hlt">CO</span><span class="hlt">2</span> has a significant impact on global climate change and the ecological environment. Because of close relationship between human activities and the <span class="hlt">CO</span><span class="hlt">2</span> emissions, it is very meaningful of detecting atmospheric <span class="hlt">CO</span><span class="hlt">2</span> accurately. 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 <span class="hlt">CO</span><span class="hlt">2</span> at 1.57μm, the system is calibrated by 100% <span class="hlt">CO</span><span class="hlt">2</span> gas cell. The atmospheric <span class="hlt">CO</span><span class="hlt">2</span> in situ is measured with long open-path way. Furthermore, the results show that <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> in atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ESASP.724E..70X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ESASP.724E..70X"><span>Measurement of <span class="hlt">Concentration</span> of <span class="hlt">CO</span><span class="hlt">2</span> in Atmosphere In Situ Based on TDLAS</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xin, Fengxin; Guo, Jinjia; Chen, Zhen; Liu, Zhishen</p> <p>2014-11-01</p> <p>As one of the main greenhouse gases in the atmosphere, <span class="hlt">CO</span><span class="hlt">2</span>has a significant impact on global climate change and the ecological environment. Because of close relationship between human activities and the <span class="hlt">CO</span><span class="hlt">2</span> emissions, it is very meaningful of detecting atmospheric <span class="hlt">CO</span><span class="hlt">2</span>accurately. 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 <span class="hlt">CO</span><span class="hlt">2</span>at 1.57μm, the system is calibrated by 100% <span class="hlt">CO</span><span class="hlt">2</span> gas cell. The atmospheric <span class="hlt">CO</span><span class="hlt">2</span> in situ is measured with long open-path way. Furthermore, the results show that <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> in atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4640122','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4640122"><span>Does long-term cultivation of saplings under elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> influence their photosynthetic response to temperature?</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Šigut, Ladislav; Holišová, Petra; Klem, Karel; Šprtová, Mirka; Calfapietra, Carlo; Marek, Michal V.; Špunda, Vladimír; Urban, Otmar</p> <p>2015-01-01</p> <p>Background and Aims Plants growing under elevated atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> often have reduced stomatal conductance and subsequently <span class="hlt">increased</span> leaf temperature. This study therefore tested the hypothesis that under long-term elevated <span class="hlt">CO</span><span class="hlt">2</span> the temperature optima of photosynthetic processes will shift towards higher temperatures and the thermostability of the photosynthetic apparatus will <span class="hlt">increase</span>. Methods The hypothesis was tested for saplings of broadleaved Fagus sylvatica and coniferous Picea abies exposed for 4–5 years to either ambient (AC; 385 µmol mol−1) or elevated (EC; 700 µmol mol−1) <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>. Temperature response curves of photosynthetic processes were determined by gas-exchange and chlorophyll fluorescence techniques. Key Results Initial assumptions of reduced light-saturated stomatal conductance and <span class="hlt">increased</span> leaf temperatures for EC plants were confirmed. Temperature response curves revealed stimulation of light-saturated rates of <span class="hlt">CO</span><span class="hlt">2</span> assimilation (Amax) and a decline in photorespiration (RL) as a result of EC within a wide temperature range. However, these effects were negligible or reduced at low and high temperatures. Higher temperature optima (Topt) of Amax, Rubisco carboxylation rates (VCmax) and RL were found for EC saplings compared with AC saplings. However, the shifts in Topt of Amax were instantaneous, and disappeared when measured at identical <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>. Higher values of Topt at elevated <span class="hlt">CO</span><span class="hlt">2</span> were attributed particularly to reduced photorespiration and prevailing limitation of photosynthesis by ribulose-1,5-bisphosphate (RuBP) regeneration. Temperature response curves of fluorescence parameters suggested a negligible effect of EC on enhancement of thermostability of photosystem II photochemistry. Conclusions Elevated <span class="hlt">CO</span><span class="hlt">2</span> instantaneously <span class="hlt">increases</span> temperature optima of Amax due to reduced photorespiration and limitation of photosynthesis by RuBP regeneration. However, this <span class="hlt">increase</span> disappears when plants</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25851132','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25851132"><span>Does long-term cultivation of saplings under elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> influence their photosynthetic response to temperature?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Šigut, Ladislav; Holišová, Petra; Klem, Karel; Šprtová, Mirka; Calfapietra, Carlo; Marek, Michal V; Špunda, Vladimír; Urban, Otmar</p> <p>2015-11-01</p> <p>Plants growing under elevated atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> often have reduced stomatal conductance and subsequently <span class="hlt">increased</span> leaf temperature. This study therefore tested the hypothesis that under long-term elevated <span class="hlt">CO</span><span class="hlt">2</span> the temperature optima of photosynthetic processes will shift towards higher temperatures and the thermostability of the photosynthetic apparatus will <span class="hlt">increase</span>. The hypothesis was tested for saplings of broadleaved Fagus sylvatica and coniferous Picea abies exposed for 4-5 years to either ambient (AC; 385 µmol mol(-1)) or elevated (EC; 700 µmol mol(-1)) <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>. Temperature response curves of photosynthetic processes were determined by gas-exchange and chlorophyll fluorescence techniques. Initial assumptions of reduced light-saturated stomatal conductance and <span class="hlt">increased</span> leaf temperatures for EC plants were confirmed. Temperature response curves revealed stimulation of light-saturated rates of <span class="hlt">CO</span><span class="hlt">2</span> assimilation (Amax) and a decline in photorespiration (RL) as a result of EC within a wide temperature range. However, these effects were negligible or reduced at low and high temperatures. Higher temperature optima (Topt) of Amax, Rubisco carboxylation rates (VCmax) and RL were found for EC saplings compared with AC saplings. However, the shifts in Topt of Amax were instantaneous, and disappeared when measured at identical <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>. Higher values of Topt at elevated <span class="hlt">CO</span><span class="hlt">2</span> were attributed particularly to reduced photorespiration and prevailing limitation of photosynthesis by ribulose-1,5-bisphosphate (RuBP) regeneration. Temperature response curves of fluorescence parameters suggested a negligible effect of EC on enhancement of thermostability of photosystem II photochemistry. Elevated <span class="hlt">CO</span><span class="hlt">2</span> instantaneously <span class="hlt">increases</span> temperature optima of Amax due to reduced photorespiration and limitation of photosynthesis by RuBP regeneration. However, this <span class="hlt">increase</span> disappears when plants are exposed to identical <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span>. In</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19924213','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19924213"><span>Reconstruction of the history of anthropogenic <span class="hlt">CO</span>(<span class="hlt">2</span>) <span class="hlt">concentrations</span> in the ocean.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Khatiwala, S; Primeau, F; Hall, T</p> <p>2009-11-19</p> <p>The release of fossil fuel <span class="hlt">CO</span>(<span class="hlt">2</span>) to the atmosphere by human activity has been implicated as the predominant cause of recent global climate change. The ocean plays a crucial role in mitigating the effects of this perturbation to the climate system, sequestering 20 to 35 per cent of anthropogenic <span class="hlt">CO</span>(<span class="hlt">2</span>) emissions. Although much progress has been made in recent years in understanding and quantifying this sink, considerable uncertainties remain as to the distribution of anthropogenic <span class="hlt">CO</span>(<span class="hlt">2</span>) in the ocean, its rate of uptake over the industrial era, and the relative roles of the ocean and terrestrial biosphere in anthropogenic <span class="hlt">CO</span>(<span class="hlt">2</span>) sequestration. Here we address these questions by presenting an observationally based reconstruction of the spatially resolved, time-dependent history of anthropogenic carbon in the ocean over the industrial era. Our approach is based on the recognition that the transport of tracers in the ocean can be described by a Green's function, which we estimate from tracer data using a maximum entropy deconvolution technique. Our results indicate that ocean uptake of anthropogenic <span class="hlt">CO</span>(<span class="hlt">2</span>) has <span class="hlt">increased</span> sharply since the 1950s, with a small decline in the rate of <span class="hlt">increase</span> in the last few decades. We estimate the inventory and uptake rate of anthropogenic <span class="hlt">CO</span>(<span class="hlt">2</span>) in 2008 at 140 +/- 25 Pg C and 2.3 +/- 0.6 Pg C yr(-1), respectively. We find that the Southern Ocean is the primary conduit by which this <span class="hlt">CO</span>(<span class="hlt">2</span>) enters the ocean (contributing over 40 per cent of the anthropogenic <span class="hlt">CO</span>(<span class="hlt">2</span>) inventory in the ocean in 2008). Our results also suggest that the terrestrial biosphere was a source of <span class="hlt">CO</span>(<span class="hlt">2</span>) until the 1940s, subsequently turning into a sink. Taken over the entire industrial period, and accounting for uncertainties, we estimate that the terrestrial biosphere has been anywhere from neutral to a net source of <span class="hlt">CO</span>(<span class="hlt">2</span>), contributing up to half as much <span class="hlt">CO</span>(<span class="hlt">2</span>) as has been taken up by the ocean over the same period.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.H41C1189N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.H41C1189N"><span>Using Subsurface <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">Concentrations</span> and Isotopologues to Identify <span class="hlt">CO</span><span class="hlt">2</span> Seepage from CCS/<span class="hlt">CO</span><span class="hlt">2</span>-EOR Projects: A Signal-to-Noise Based Analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nickerson, N. R.; Risk, D. A.</p> <p>2012-12-01</p> <p>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 <span class="hlt">CO</span><span class="hlt">2</span>. 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 <span class="hlt">CO</span><span class="hlt">2</span>, δ13<span class="hlt">CO</span><span class="hlt">2</span>, and Δ14<span class="hlt">CO</span><span class="hlt">2</span>. For inter-comparisons, we used a simulated northern temperate landscape similar to that of Weyburn, Saskatchewan (home of the IEAGHG Weyburn-Midale <span class="hlt">CO</span><span class="hlt">2</span> Monitoring and Storage Project), in which realistic spatial and temporal <span class="hlt">CO</span><span class="hlt">2</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27233774','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27233774"><span>Key knowledge and data gaps in modelling the influence of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> on the terrestrial carbon sink.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pugh, T A M; Müller, C; Arneth, A; Haverd, V; Smith, B</p> <p>2016-09-20</p> <p>Primary productivity of terrestrial vegetation is expected to <span class="hlt">increase</span> under the influence of <span class="hlt">increasing</span> atmospheric carbon dioxide <span class="hlt">concentrations</span> ([<span class="hlt">CO</span><span class="hlt">2</span>]). Depending on the fate of such additionally fixed carbon, this could lead to an <span class="hlt">increase</span> in terrestrial carbon storage, and thus a net terrestrial sink of atmospheric carbon. Such a mechanism is generally believed to be the primary global driver behind the observed large net uptake of anthropogenic <span class="hlt">CO</span><span class="hlt">2</span> emissions by the biosphere. Mechanisms driving <span class="hlt">CO</span><span class="hlt">2</span> uptake in the Terrestrial Biosphere Models (TBMs) used to attribute and project terrestrial carbon sinks, including that from <span class="hlt">increased</span> [<span class="hlt">CO</span><span class="hlt">2</span>], remain in large parts unchanged since those models were conceived two decades ago. However, there exists a large body of new data and understanding providing an opportunity to update these models, and directing towards important topics for further research. In this review we highlight recent developments in understanding of the effects of elevated [<span class="hlt">CO</span><span class="hlt">2</span>] on photosynthesis, and in particular on the fate of additionally fixed carbon within the plant with its implications for carbon turnover rates, on the regulation of photosynthesis in response to environmental limitations on in-plant carbon sinks, and on emergent ecosystem responses. We recommend possible avenues for model improvement and identify requirements for better data on core processes relevant to the understanding and modelling of the effect of <span class="hlt">increasing</span> [<span class="hlt">CO</span><span class="hlt">2</span>] on the global terrestrial carbon sink. Copyright © 2016 The Authors. Published by Elsevier GmbH.. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoRL..44.1537H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..44.1537H"><span><span class="hlt">CO</span><span class="hlt">2</span> emission of Indonesian fires in 2015 estimated from satellite-derived atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Heymann, J.; Reuter, M.; Buchwitz, M.; Schneising, O.; Bovensmann, H.; Burrows, J. P.; Massart, S.; Kaiser, J. W.; Crisp, D.</p> <p>2017-02-01</p> <p>Indonesia experienced an exceptional number of fires in 2015 as a result of droughts related to the recent El Niño event and human activities. These fires released large amounts of carbon dioxide (<span class="hlt">CO</span><span class="hlt">2</span>) into the atmosphere. Emission databases such as the Global Fire Assimilation System version 1.2 and the Global Fire Emission Database version 4s estimated the <span class="hlt">CO</span><span class="hlt">2</span> emission to be approximately 1100 Mt<span class="hlt">CO</span><span class="hlt">2</span> in the time period from July to November 2015. This emission was indirectly estimated by using parameters like burned area, fire radiative power, and emission factors. In the study presented in this paper, we estimate the Indonesian fire <span class="hlt">CO</span><span class="hlt">2</span> emission by using the column-averaged dry air mole fraction of <span class="hlt">CO</span><span class="hlt">2</span>, XCO2, derived from measurements of the Orbiting Carbon Observatory-2 satellite mission. The estimated <span class="hlt">CO</span><span class="hlt">2</span> emission is 748 ± 209 Mt<span class="hlt">CO</span><span class="hlt">2</span>, which is about 30% lower than provided by the emission databases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.9858Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.9858Y"><span>Simultaneous measurement of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> and isotopic ratios in gas samples using IRMS</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yu, Eun-Ji; Lee, Dongho; Bong, Yeon-Sik; Lee, Kwang-Sik</p> <p>2014-05-01</p> <p>Isotopic methods are indispensable tools for studies on atmosphere-biosphere exchanges of <span class="hlt">CO</span><span class="hlt">2</span> and environmental monitoring such as <span class="hlt">CO</span><span class="hlt">2</span> leakage detection from subsurface carbon storages. <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> is an important variable in interpreting isotopic composition of <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> was trapped by a single cryotrap (-180 ºC) after passing a water trap (Mg(ClO4)2). Upon release of the cryotrap, liberated <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">concentration</span> calculation. For the determination of <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>, a calibration curve relating the peak intensity with molar <span class="hlt">concentration</span> of <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> was analyzed for the isotopic ratios and the corresponding peak intensity was recorded</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.B32B..01K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.B32B..01K"><span>Effects of Pre-industrial and Future Atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> on Net Ecosystem Exchange on Arid and Semi-Arid Ecosystems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kalhori, A. A. M.; Deutschman, D.; Cheng, Y.; Oechel, W. C.</p> <p>2014-12-01</p> <p>Ecosystem carbon dioxide flux was studied between 1997 and 2000 under six different <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> (250 ppm, 350 ppm, 450 ppm, 550 ppm, 650 ppm, and 750 ppm) using <span class="hlt">CO</span><span class="hlt">2</span> LT (<span class="hlt">CO</span><span class="hlt">2</span> controlled, naturally Lit, Temperature controlled) null balance chambers in Southern California chaparral dominated by Adenostoma fasciculatum. The purpose of this study is to evaluate possible effects of altered levels of atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> on carbon fluxes in a natural chaparral ecosystem. Here we present that the <span class="hlt">increase</span> of <span class="hlt">CO</span><span class="hlt">2</span> from near pre-industrial levels of around 250 ppm to recent past <span class="hlt">CO</span><span class="hlt">2</span> levels of 350 ppm are sufficient to <span class="hlt">increase</span> NEE. These data indicate that chaparral ecosystems will <span class="hlt">increase</span> carbon sequestration under elevated <span class="hlt">CO</span><span class="hlt">2</span> levels and that under elevated atmospheric <span class="hlt">CO</span><span class="hlt">2</span> there will be greater sink or reduced source of ecosystem <span class="hlt">CO</span><span class="hlt">2</span> to the atmosphere as a result of improved moisture status. The effect of elevated <span class="hlt">CO</span><span class="hlt">2</span> on <span class="hlt">increasing</span> NEE was greatest during the warm and dry season versus the cold and wet season. Further, it appears that <span class="hlt">increasing</span> atmospheric <span class="hlt">CO</span><span class="hlt">2</span> will have greater relative effects in areas of <span class="hlt">increasing</span> water stress as <span class="hlt">CO</span><span class="hlt">2</span> treatment effects on NEE were greater in modestly dry years and with longer periods of drought. The daily maximum NEE difference between the lowest (250 ppm) and the highest (750 ppm) <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> treatments for January was -0.127gC m-2 h-1, but for June was -0.267 gC m-2 h-1 in this study, which was a 210 percent <span class="hlt">increase</span>. The differences between the lower treatments and higher treatments were greater in the later years indicating there was an accumulative effect. Cumulative of net ecosystem exchange (gC m-2) between 1/1/1997 and 1/1/2001 under six different <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> is presented in the figure attached.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.V11A2739H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V11A2739H"><span>The <span class="hlt">Concentrations</span> and Possible Effects of <span class="hlt">CO</span><span class="hlt">2</span> in Geysers of Yellowstone National Park</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hurwitz, S.; Evans, W.; Thordsen, J. J.; Murphy, F.</p> <p>2012-12-01</p> <p>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 <span class="hlt">CO</span><span class="hlt">2</span> dissolved in Old Faithful Geyser waters exerts a significant control on its eruptions. Based on the <span class="hlt">concentrations</span> of major cations and the pH of erupted water and assuming mineral buffering, they calculated a <span class="hlt">CO</span><span class="hlt">2</span> partial pressure of <0.3 bar. To test the hypothesis suggesting that <span class="hlt">CO</span><span class="hlt">2</span> 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. <span class="hlt">Concentrations</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> and H2O(v) at in-situ conditions were calculated to be 0.9 and 3.7 bars, respectively. The calculated dissolved <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> is less than the saturation <span class="hlt">concentration</span> at a hydrostatic (+atmospheric) load of ~8 bar (~72 m). However, the measured dissolved <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> are more than double the highest <span class="hlt">concentrations</span> calculated by Hutchinson et al., 1997, and likely support their hypothesis regarding the significance of <span class="hlt">CO</span><span class="hlt">2</span> in geyser eruptions. Initial calculations suggest <span class="hlt">CO</span><span class="hlt">2</span> helps induce boiling at shallow levels, exsolving into the steam phase that drives the eruption. The initial bubbles may be <span class="hlt">CO</span><span class="hlt">2</span> rich, such that the presence of <span class="hlt">CO</span><span class="hlt">2</span> can have a significant effect on the subsurface seismic signals and on the dynamics of the erupting jet. As boiling progresses during decompression, the <span class="hlt">CO</span><span class="hlt">2</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1615962N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1615962N"><span>The impact of elevated <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> on soil microbial community, soil organic matter storage and nutrient cycling at a natural <span class="hlt">CO</span><span class="hlt">2</span> vent in NW Bohemia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nowak, Martin; Beulig, Felix; von Fischer, Joe; Muhr, Jan; Kuesel, Kirsten; Trumbore, Susan</p> <p>2014-05-01</p> <p>Natural <span class="hlt">CO</span><span class="hlt">2</span> vents or 'mofettes' are diffusive or advective exhalations of geogenic <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> fertilization of <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> to soil organic carbon formation within mofette soils, either resulting from plant litter or from microbial <span class="hlt">CO</span><span class="hlt">2</span> uptake. This is possible because the geogenic <span class="hlt">CO</span><span class="hlt">2</span> has a distinct isotopic signature (δ13C = -2 o Δ14C = -1000 ) that is very different from the isotopic signature of atmospheric <span class="hlt">CO</span><span class="hlt">2</span>. 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 <span class="hlt">CO</span><span class="hlt">2</span> is re-fixed and stored as SOM. In order to quantify microbial contribution to <span class="hlt">CO</span><span class="hlt">2</span> fixation and SOM storage, microbial <span class="hlt">CO</span><span class="hlt">2</span> uptake rates were determined by incubating mofette soils with 13<span class="hlt">CO</span><span class="hlt">2</span> labelled gas. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1357496-dynamic-analysis-concentrated-solar-supercritical-co2-based-power-generation-closed-loop-cycle','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1357496-dynamic-analysis-concentrated-solar-supercritical-co2-based-power-generation-closed-loop-cycle"><span>Dynamic analysis of <span class="hlt">concentrated</span> solar supercritical <span class="hlt">CO</span><span class="hlt">2</span>-based power generation closed-loop cycle</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Osorio, Julian D.; Hovsapian, Rob; Ordonez, Juan C.</p> <p>2016-01-01</p> <p>Here, the dynamic behavior of a <span class="hlt">concentrated</span> solar power (CSP) supercritical <span class="hlt">CO</span><span class="hlt">2</span> cycle is studied under different seasonal conditions. The system analyzed is composed of a central receiver, hot and cold thermal energy storage units, a heat exchanger, a recuperator, and multi-stage compression-expansion subsystems with intercoolers and reheaters between compressors and turbines respectively. Energy models for each component of the system are developed in order to optimize operating and design parameters such as mass flow rate, intermediate pressures and the effective area of the recuperator to lead to maximum efficiency. Our results show that the parametric optimization leads the systemmore » to a process efficiency of about 21 % and a maximum power output close to 1.5 MW. The thermal energy storage allows the system to operate for several hours after sunset. This operating time is approximately <span class="hlt">increased</span> from 220 to 480 minutes after optimization. The hot and cold thermal energy storage also lessens the temperature fluctuations by providing smooth changes of temperatures at the turbines and compressors inlets. Our results indicate that <span class="hlt">concentrated</span> solar systems using supercritical <span class="hlt">CO</span><span class="hlt">2</span> could be a viable alternative to satisfying energy needs in desert areas with scarce water and fossil fuel resources.« less</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4291579','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4291579"><span>Effect of carbonic anhydrase on silicate weathering and carbonate formation at present day <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> compared to primordial values</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Xiao, Leilei; Lian, Bin; Hao, Jianchao; Liu, Congqiang; Wang, Shijie</p> <p>2015-01-01</p> <p>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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span>. The results show that the expression of CA genes is negatively correlated with both <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> 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 <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> show that the magnitudes of the effects of CA and <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> are negatively correlated. These results suggest that the effects of microbial CA in relation to silicate weathering and carbonate formation may have <span class="hlt">increased</span> importance at the modern atmospheric <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentration</span> compared to 3 billion years ago. PMID:25583135</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NatSR...5E7733X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatSR...5E7733X"><span>Effect of carbonic anhydrase on silicate weathering and carbonate formation at present day <span class="hlt">CO</span><span class="hlt">2</span> <span class="hlt">concentrations</span> compared to primordial values</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiao, Leilei; Lian, Bin; Hao, Jianchao; Liu, Congqiang; Wang, Shijie</p> <p>2015-01-01</p> <p>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 <span class="hlt">CO</span><span class="hl