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Sample records for atmospheric co2 face

  1. Contemporary evolution of an invasive grass in response to elevated atmospheric CO(2) at a Mojave Desert FACE site.

    Science.gov (United States)

    Grossman, Judah D; Rice, Kevin J

    2014-06-01

    Elevated atmospheric CO2 has been shown to rapidly alter plant physiology and ecosystem productivity, but contemporary evolutionary responses to increased CO2 have yet to be demonstrated in the field. At a Mojave Desert FACE (free-air CO2 enrichment) facility, we tested whether an annual grass weed (Bromus madritensis ssp. rubens) has evolved in response to elevated atmospheric CO2 . Within 7 years, field populations exposed to elevated CO2 evolved lower rates of leaf stomatal conductance; a physiological adaptation known to conserve water in other desert or water-limited ecosystems. Evolution of lower conductance was accompanied by reduced plasticity in upregulating conductance when CO2 was more limiting; this reduction in conductance plasticity suggests that genetic assimilation may be ongoing. Reproductive fitness costs associated with this reduction in phenotypic plasticity were demonstrated under ambient levels of CO2 . Our findings suggest that contemporary evolution may facilitate this invasive species' spread in this desert ecosystem.

  2. Forecasting global atmospheric CO2

    Directory of Open Access Journals (Sweden)

    A. Agustí-Panareda

    2014-05-01

    Full Text Available A new global atmospheric carbon dioxide (CO2 real-time forecast is now available as part of the pre-operational Monitoring of Atmospheric Composition and Climate – Interim Implementation (MACC-II service using the infrastructure of the European Centre for Medium-Range Weather Forecasts (ECMWF Integrated Forecasting System (IFS. One of the strengths of the CO2 forecasting system is that the land surface, including vegetation CO2 fluxes, is modelled online within the IFS. Other CO2 fluxes are prescribed from inventories and from off-line statistical and physical models. The CO2 forecast also benefits from the transport modelling from a state-of-the-art numerical weather prediction (NWP system initialized daily with a wealth of meteorological observations. This paper describes the capability of the forecast in modelling the variability of CO2 on different temporal and spatial scales compared to observations. The modulation of the amplitude of the CO2 diurnal cycle by near-surface winds and boundary layer height is generally well represented in the forecast. The CO2 forecast also has high skill in simulating day-to-day synoptic variability. In the atmospheric boundary layer, this skill is significantly enhanced by modelling the day-to-day variability of the CO2 fluxes from vegetation compared to using equivalent monthly mean fluxes with a diurnal cycle. However, biases in the modelled CO2 fluxes also lead to accumulating errors in the CO2 forecast. These biases vary with season with an underestimation of the amplitude of the seasonal cycle both for the CO2 fluxes compared to total optimized fluxes and the atmospheric CO2 compared to observations. The largest biases in the atmospheric CO2 forecast are found in spring, corresponding to the onset of the growing season in the Northern Hemisphere. In the future, the forecast will be re-initialized regularly with atmospheric CO2 analyses based on the assimilation of CO2 satellite retrievals, as they

  3. The AmazonFACE research program: assessing the effects of increasing atmospheric CO2 on the ecology and resilience of the Amazon forest

    Science.gov (United States)

    Lapola, David; Quesada, Carlos; Norby, Richard; Araújo, Alessandro; Domingues, Tomas; Hartley, Iain; Kruijt, Bart; Lewin, Keith; Meir, Patrick; Ometto, Jean; Rammig, Anja

    2016-04-01

    The existence, magnitude and duration of a supposed "CO2 fertilization" effect in tropical forests remains largely undetermined, despite being suggested for nearly 20 years as a key knowledge gap for understanding the future resilience of Amazonian forests and its impact on the global carbon cycle. Reducing this uncertainty is critical for assessing the future of the Amazon region as well as its vulnerability to climate change. The AmazonFACE (Free-Air CO2 Enrichment) research program is an integrated model-experiment initiative of unprecedented scope in an old-growth Amazon forest near Manaus, Brazil - the first of its kind in tropical forest. The experimental treatment will simulate an atmospheric CO2 concentration [CO2] of the future in order to address the question: "How will rising atmospheric CO2 affect the resilience of the Amazon forest, the biodiversity it harbors, and the ecosystem services it provides, in light of projected climatic changes?" AmazonFACE is divided into three phases: (I) pre-experimental ecological characterization of the research site; (II) pilot experiment comprised of two 30-m diameter plots, with one treatment plot maintained at elevated [CO2] (ambient +200 ppmv), and the other control plot at ambient [CO2]; and (III) a fully-replicated long-term experiment comprised of four pairs of control/treatment FACE plots maintained for 10 years. A team of scientists from Brazil, USA, Australia and Europe will employ state-of-the-art methods to study the forest inside these plots in terms of carbon metabolism and cycling, water use, nutrient cycling, forest community composition, and interactions with environmental stressors. All project phases also encompass ecosystem-modeling activities in a way such that models provide hypothesis to be verified in the experiment, which in turn will feed models to ultimately produce more accurate projections of the environment. Resulting datasets and analyses will be a valuable resource for a broad community

  4. IMPACTS OF INTERACTING ELEVATED ATMOSPHERIC CO2 AND O3 ON THE STRUCTURE AND FUNCTIONING OF A NORTHERN FOREST ECOSYSTEM: OPERATING AND DECOMMISSIONING THE ASPEN FACE PROJECT

    Energy Technology Data Exchange (ETDEWEB)

    Burton, Andrew J. [Michigan Technological University; Zak, Donald R. [University of Michigan; Kubiske, Mark E. [USDA Forest Service; Pregitzer, Kurt S. [University of Idaho

    2014-06-30

    Two of the most important and pervasive greenhouse gases driving global change and impacting forests in the U.S. and around the world are atmospheric CO2 and tropospheric O3. As the only free air, large-scale manipulative experiment studying the interaction of elevated CO2 and O3 on forests, the Aspen FACE experiment was uniquely designed to address the long-term ecosystem level impacts of these two greenhouse gases on aspen-birch-maple forests, which dominate the richly forested Lake States region. The project was established in 1997 to address the overarching scientific question: “What are the effects of elevated [CO2] and [O3], alone and in combination, on the structure and functioning of northern hardwood forest ecosystems?” From 1998 through the middle of the 2009 growing season, we examined the interacting effects of elevated CO2 and O3 on ecosystem processes in an aggrading northern forest ecosystem to compare the responses of early-successional, rapid-growing shade intolerant trembling aspen and paper birch to those of a late successional, slower growing shade tolerant sugar maple. Fumigations with elevated CO2 (560 ppm during daylight hours) and O3 (approximately 1.5 x ambient) were conducted during the growing season from 1998 to 2008, and in 2009 through harvest date. Response variables quantified during the experiment included growth, competitive interactions and stand dynamics, physiological processes, plant nutrient status and uptake, tissue biochemistry, litter quality and decomposition rates, hydrology, soil respiration, microbial community composition and respiration, VOC production, treatment-pest interactions, and treatment-phenology interactions. In 2009, we conducted a detailed harvest of the site. The harvest included detailed sampling of a subset of trees by component (leaves and buds, fine branches, coarse branches and stem, coarse roots, fine roots) and excavation of soil to a depth of 1 m. Throughout the experiment, aspen and birch

  5. IMPACTS OF INTERACTING ELEVATED ATMOSPHERIC CO2 AND O3 ON THE STRUCTURE AND FUNCTIONING OF A NORTHERN FOREST ECOSYSTEM: OPERATING AND DECOMMISSIONING THE ASPEN FACE PROJECT

    Energy Technology Data Exchange (ETDEWEB)

    Burton, Andrew J. [Michigan Technological University; Zak, Donald R. [University of Michigan; Kubiske, Mark E. [USDA Forest Service; Pregitzer, Kurt S. [University of Idaho

    2014-06-30

    Two of the most important and pervasive greenhouse gases driving global change and impacting forests in the U.S. and around the world are atmospheric CO2 and tropospheric O3. As the only free air, large-scale manipulative experiment studying the interaction of elevated CO2 and O3 on forests, the Aspen FACE experiment was uniquely designed to address the long-term ecosystem level impacts of these two greenhouse gases on aspen-birch-maple forests, which dominate the richly forested Lake States region. The project was established in 1997 to address the overarching scientific question: “What are the effects of elevated [CO2] and [O3], alone and in combination, on the structure and functioning of northern hardwood forest ecosystems?” From 1998 through the middle of the 2009 growing season, we examined the interacting effects of elevated CO2 and O3 on ecosystem processes in an aggrading northern forest ecosystem to compare the responses of early-successional, rapid-growing shade intolerant trembling aspen and paper birch to those of a late successional, slower growing shade tolerant sugar maple. Fumigations with elevated CO2 (560 ppm during daylight hours) and O3 (approximately 1.5 x ambient) were conducted during the growing season from 1998 to 2008, and in 2009 through harvest date. Response variables quantified during the experiment included growth, competitive interactions and stand dynamics, physiological processes, plant nutrient status and uptake, tissue biochemistry, litter quality and decomposition rates, hydrology, soil respiration, microbial community composition and respiration, VOC production, treatment-pest interactions, and treatment-phenology interactions. In 2009, we conducted a detailed harvest of the site. The harvest included detailed sampling of a subset of trees by component (leaves and buds, fine branches, coarse branches and stem, coarse roots, fine roots) and excavation of soil to a depth of 1 m. Throughout the experiment, aspen and birch

  6. Trapping atmospheric CO2 with gold.

    Science.gov (United States)

    Collado, Alba; Gómez-Suárez, Adrián; Webb, Paul B; Kruger, Hedi; Bühl, Michael; Cordes, David B; Slawin, Alexandra M Z; Nolan, Steven P

    2014-10-07

    The ability of gold-hydroxides to fix CO2 is reported. [Au(IPr)(OH)] and [{Au(IPr)}2(μ-OH)][BF4] react with atmospheric CO2 to form the trigold carbonate complex [{Au(IPr)}3(μ(3)-CO3)][BF4]. Reactivity studies revealed that this complex behaves as two basic and one cationic Au centres, and that it is catalytically active. DFT calculations and kinetic experiments have been carried out.

  7. CO2 Impacts on the Martian Atmosphere

    Science.gov (United States)

    Kelley, Michael; Bauer, James; Bodewits, Dennis; Farnham, Tony; Stevenson, Rachel; Yelle, Roger

    2014-09-01

    The dynamically new comet C/2013 A1 (Siding Spring) will pass Mars at the extremely close distance of 140,000 km on 2014 Oct 19. This encounter is unique---a record close approach to a planet with spacecraft that can observe its passage---and currently, all 5 Mars orbiters have plans to observe the comet and/or its effects on the planet. Gas from the comet's coma is expected to collide with the Martian atmosphere, altering the abundances of some species and producing significant heating, inflating the upper atmosphere. We propose DDT observations with Spitzer/IRAC to measure the comet's CO2+CO coma (observing window Oct 30 - Nov 20), to use these measurements to derive the coma's CO2 density at Mars during the closest approach, and to aid the interpretation of any observed effects or changes in the Martian atmosphere.

  8. Energyless CO2 Absorption, Generation, and Fixation Using Atmospheric CO2.

    Science.gov (United States)

    Inagaki, Fuyuhiko; Okada, Yasuhiko; Matsumoto, Chiaki; Yamada, Masayuki; Nakazawa, Kenta; Mukai, Chisato

    2016-01-01

    From an economic and ecological perspective, the efficient utilization of atmospheric CO2 as a carbon resource should be a much more important goal than reducing CO2 emissions. However, no strategy to harvest CO2 using atmospheric CO2 at room temperature currently exists, which is presumably due to the extremely low concentration of CO2 in ambient air (approximately 400 ppm=0.04 vol%). We discovered that monoethanolamine (MEA) and its derivatives efficiently absorbed atmospheric CO2 without requiring an energy source. We also found that the absorbed CO2 could be easily liberated with acid. Furthermore, a novel CO2 generator enabled us to synthesize a high value-added material (i.e., 2-oxazolidinone derivatives based on the metal catalyzed CO2-fixation at room temperature) from atmospheric CO2.

  9. Seasonal response of photosynthetic electron transport and energy dissipation in the eighth year of exposure to elevated atmospheric CO2 (FACE) in Pinus taeda (loblolly pine).

    Science.gov (United States)

    Logan, Barry A; Combs, Andrew; Myers, Kalisa; Kent, Rose; Stanley, Lela; Tissue, David T

    2009-06-01

    To determine the effect of growth under elevated CO(2) partial pressures (pCO(2)) on photosynthetic electron transport and photoprotective energy dissipation, we examined light-saturated net photosynthetic CO(2) assimilation (A(sat)), the capacity for photosynthetic O(2) evolution, chlorophyll fluorescence emission and the pigment composition of upper-canopy loblolly pine needles in the eighth year of exposure to elevated pCO(2) (20 Pa above ambient) at the free-air CO(2) enrichment facility in the Duke Forest. During the summer growing season, A(sat) was 50% higher in current-year needles and 24% higher in year-old needles in elevated pCO(2) in comparison with needles of the same age cohort in ambient pCO(2). Thus, photosynthetic down-regulation at elevated pCO(2) was observed in the summer in year-old needles. In the winter, A(sat) was not significantly affected by growth pCO(2). Reductions in A(sat), the capacity for photosynthetic O(2) evolution and photosystem II (PSII) efficiency in the light-acclimated and fully-oxidized states were observed in the winter when compared to summer. Growth at elevated pCO(2) had no significant effect on the capacity for photosynthetic O(2) evolution, PSII efficiencies in the light-acclimated and fully-oxidized states, chlorophyll content or the size and conversion state of the xanthophyll cycle, regardless of season or needle age cohort. Therefore, we observed no evidence that photosynthetic electron transport or photoprotective energy dissipation responded to compensate for the effects of elevated pCO(2) on Calvin cycle activity.

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

    Science.gov (United States)

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

    2015-12-01

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

  11. Regional Ecosystem-Atmosphere CO2 Exchange Via Atmospheric Budgets

    Energy Technology Data Exchange (ETDEWEB)

    Davis, K J; Richardson, S J; Miles, N L

    2007-03-07

    Inversions of atmospheric CO2 mixing ratio measurements to determine CO2 sources and sinks are typically limited to coarse spatial and temporal resolution. This limits our ability to evaluate efforts to upscale chamber- and stand-level CO2 flux measurements to regional scales, where coherent climate and ecosystem mechanisms govern the carbon cycle. As a step towards the goal of implementing atmospheric budget or inversion methodology on a regional scale, a network of five relatively inexpensive CO2 mixing ratio measurement systems was deployed on towers in northern Wisconsin. Four systems were distributed on a circle of roughly 150-km radius, surrounding one centrally located system at the WLEF tower near Park Falls, WI. All measurements were taken at a height of 76 m AGL. The systems used single-cell infrared CO2 analyzers (Licor, model LI-820) rather than the siginificantly more costly two-cell models, and were calibrated every two hours using four samples known to within ± 0.2 ppm CO2. Tests prior to deployment in which the systems sampled the same air indicate the precision of the systems to be better than ± 0.3 ppm and the accuracy, based on the difference between the daily mean of one system and a co-located NOAA-ESRL system, is consistently better than ± 0.3 ppm. We demonstrate the utility of the network in two ways. We interpret regional CO2 differences using a Lagrangian parcel approach. The difference in the CO2 mixing ratios across the network is at least 2-3 ppm, which is large compared to the accuracy and precision of the systems. Fluxes estimated assuming Lagrangian parcel transport are of the same sign and magnitude as eddy-covariance flux measurements at the centrally-located WLEF tower. These results indicate that the network will be useful in a full inversion model. Second, we present a case study involving a frontal passage through the region. The progression of a front across the network is evident; changes as large as four ppm in one minute

  12. The Abundance of Atmospheric CO2 in Ocean Exoplanets: a Novel CO2 Deposition Mechanism

    Science.gov (United States)

    Levi, A.; Sasselov, D.; Podolak, M.

    2017-03-01

    We consider super-Earth sized planets which have a water mass fraction large enough to form an external mantle composed of high-pressure water-ice polymorphs and also lack a substantial H/He atmosphere. We consider such planets in their habitable zone, so that their outermost condensed mantle is a global, deep, liquid ocean. For these ocean planets, we investigate potential internal reservoirs of CO2, the amount of CO2 dissolved in the ocean for the various saturation conditions encountered, and the ocean-atmosphere exchange flux of CO2. We find that, in a steady state, the abundance of CO2 in the atmosphere has two possible states. When wind-driven circulation is the dominant CO2 exchange mechanism, an atmosphere of tens of bars of CO2 results, where the exact value depends on the subtropical ocean surface temperature and the deep ocean temperature. When sea-ice formation, acting on these planets as a CO2 deposition mechanism, is the dominant exchange mechanism, an atmosphere of a few bars of CO2 is established. The exact value depends on the subpolar surface temperature. Our results suggest the possibility of a negative feedback mechanism, unique to water planets, where a reduction in the subpolar temperature drives more CO2 into the atmosphere to increase the greenhouse effect.

  13. The Abundance of Atmospheric CO2 in Ocean Exoplanets: A Novel CO2 Deposition Mechanism

    CERN Document Server

    Levi, Amit; Podolak, Morris

    2016-01-01

    We consider super-Earth sized planets which have a water mass fraction that is large enough to form an external mantle composed of high pressure water ice polymorphs and that lack a substantial H/He atmosphere. We consider such planets in their habitable zone so that their outermost condensed mantle is a global deep liquid ocean. For these ocean planets we investigate potential internal reservoirs of CO2; the amount of CO2 dissolved in the ocean for the various saturation conditions encountered, and the ocean-atmosphere exchange flux of CO2. We find that in steady state the abundance of CO2 in the atmosphere has two possible states. When the wind-driven circulation is the dominant CO2 exchange mechanism, an atmosphere of tens of bars of CO2 results, where the exact value depends on the subtropical ocean surface temperature and the deep ocean temperature. When sea-ice formation, acting on these planets as a CO2 deposition mechanism, is the dominant exchange mechanism, an atmosphere of a few bars of CO2 is esta...

  14. Atmospheric CO2 Variability Observed From ASCENDS Flight Campaigns

    Science.gov (United States)

    Lin, Bing; Browell, Edward; Campbell, Joel; Choi, Yonghoon; Dobler, Jeremy; Fan, Tai-Fang; Harrison, F. Wallace; Kooi, Susan; Liu, Zhaoyan; Meadows, Byron; Nehrir, Amin; Obland, Michael; Plant, James; Yang, Melissa

    2015-01-01

    Significant atmospheric CO2 variations on various spatiotemporal scales were observed during ASCENDS flight campaigns. For example, around 10-ppm CO2 changes were found within free troposphere in a region of about 200x300 sq km over Iowa during a summer 2014 flight. Even over extended forests, about 2-ppm CO2 column variability was measured within about 500-km distance. For winter times, especially over snow covered ground, relatively less horizontal CO2 variability was observed, likely owing to minimal interactions between the atmosphere and land surface. Inter-annual variations of CO2 drawdown over cornfields in the Mid-West were found to be larger than 5 ppm due to slight differences in the corn growing phase and meteorological conditions even in the same time period of a year. Furthermore, considerable differences in atmospheric CO2 profiles were found during winter and summer campaigns. In the winter CO2 was found to decrease from about 400 ppm in the atmospheric boundary layer (ABL) to about 392 ppm above 10 km, while in the summer CO2 increased from 386 ppm in the ABL to about 396 ppm in free troposphere. These and other CO2 observations are discussed in this presentation.

  15. Carbon Turnover in a Crop Rotation Under Free Air CO2 Enrichment (FACE)

    Institute of Scientific and Technical Information of China (English)

    H. J. WEIGEL; K. LEWIN; J. NAGY; A. PACHOLSKI; S. BURKART; M. HELAL; O. HEINEMEYER; B. KLEIKAMP; R. MANDERSCHEID; C. FR(U)HAUF; G. F. HENDREY

    2005-01-01

    Mostly based on assumptions derived from controlled-environment studies, predicted future atmospheric CO2 concentrations [CO2] are expected to have considerable impacts on carbon (C) turnover in agro-ecosystems. In order to allow the in situ examination of C-transformations in the plant-soil system of arable crop rotations under future [CO2], a free air carbon dioxide enrichment (FACE) experiment (550 μmol mol-1 CO2) was started at Braunschweig, Germany in 1999.The crop rotation under investigation comprised winter barley, a cover crop (ryegrass), sugar beets and winter wheat.Assessments of CO2 effects included the determination of above- and belowground biomass production, measurements of canopy CO2- and H2O- fluxes, soil microbial biomass and in situ soil respiration. The results obtained during the 1st crop rotation cycle (3 years) showed that for the selected crops elevated [CO2] entailed significant positive effects (P<0.05) on aboveground (6%-14% stimulation) and belowground biomass production (up to 90% stimulation), while canopy evapotranspiration was reduced. This resulted in increased soil water content. Also, depending on crop type and season, high CO2 stimulated in situ soil respiration (up to 30%), while soil microbial biomass did not show significant respoases to elevated [CO2] during the first rotation cycle.

  16. Effects of atmospheric CO2 enrichment on soil CO2 efflux in a young longleaf pine system

    Science.gov (United States)

    Elevated atmospheric carbon dioxide (CO2) can affect the quantity and quality of plant tissues which will impact carbon (C) cycling and storage in plant/soil systems and the release of CO2 back to the atmosphere. Research is needed to quantify the effects of elevated CO2 on soil CO2 efflux to predi...

  17. A role for atmospheric CO2 in preindustrial climate forcing

    NARCIS (Netherlands)

    Hoof, T.B. van; Wagner-Cremer, F.; Kürschner, W.M.; Visscher, H.

    2008-01-01

    Complementary to measurements in Antarctic ice cores, stomatal frequency analysis of leaves of land plants preserved in peat and lake deposits can provide a proxy record of preindustrial atmospheric CO2 concentration. CO2 trends based on leaf remains of Quercus robur (English oak) from the Netherlan

  18. Long-term elevated atmospheric CO2 enhances forest productivity

    Science.gov (United States)

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

    2011-12-01

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

  19. Sustained effects of atmospheric [CO2] and nitrogen availability on forest soil CO2 efflux.

    Science.gov (United States)

    Oishi, A Christopher; Palmroth, Sari; Johnsen, Kurt H; McCarthy, Heather R; Oren, Ram

    2014-04-01

    Soil CO2 efflux (Fsoil ) is the largest source of carbon from forests and reflects primary productivity as well as how carbon is allocated within forest ecosystems. Through early stages of stand development, both elevated [CO2] and availability of soil nitrogen (N; sum of mineralization, deposition, and fixation) have been shown to increase gross primary productivity, but the long-term effects of these factors on Fsoil are less clear. Expanding on previous studies at the Duke Free-Air CO2 Enrichment (FACE) site, we quantified the effects of elevated [CO2] and N fertilization on Fsoil using daily measurements from automated chambers over 10 years. Consistent with previous results, compared to ambient unfertilized plots, annual Fsoil increased under elevated [CO2] (ca. 17%) and decreased with N (ca. 21%). N fertilization under elevated [CO2] reduced Fsoil to values similar to untreated plots. Over the study period, base respiration rates increased with leaf productivity, but declined after productivity saturated. Despite treatment-induced differences in aboveground biomass, soil temperature and water content were similar among treatments. Interannually, low soil water content decreased annual Fsoil from potential values - estimated based on temperature alone assuming nonlimiting soil water content - by ca. 0.7% per 1.0% reduction in relative extractable water. This effect was only slightly ameliorated by elevated [CO2]. Variability in soil N availability among plots accounted for the spatial variability in Fsoil , showing a decrease of ca. 114 g C m(-2) yr(-1) per 1 g m(-2) increase in soil N availability, with consistently higher Fsoil in elevated [CO2] plots ca. 127 g C per 100 ppm [CO2] over the +200 ppm enrichment. Altogether, reflecting increased belowground carbon partitioning in response to greater plant nutritional needs, the effects of elevated [CO2] and N fertilization on Fsoil in this stand are sustained beyond the early stages of stand development and

  20. Mesoscale modelling of atmospheric CO2 across Denmark

    DEFF Research Database (Denmark)

    Lansø, Anne Sofie

    2016-01-01

    It is scientifically well-established that the increase of atmospheric CO2 affects the entire globe and will lead to higher surface temperatures. Although anthropogenic CO2is emitted straight into the atmosphere, it does not all contribute to the existing atmospheric CO2 reservoir. Approximately 29...... the processes controlling the sources and sinks of atmospheric CO2. This PhD dissertation attempts to increase our understanding of the importance of accounting for high spatiotemporal variability in estimates of CO2 exchanges between the atmosphere and the surface. For this purpose, a mesoscale...... modelling system is constructed, centred around Denmark, based on an atmospheric transport model. In this study, the main areas of focus have been on improving the spatial surface representation, for both land and sea, and investigating the influence of the temporal resolution on the air–sea CO2 exchange...

  1. Biosequestration of atmospheric CO2 and flue gas-containing CO2 by microalgae.

    Science.gov (United States)

    Cheah, Wai Yan; Show, Pau Loke; Chang, Jo-Shu; Ling, Tau Chuan; Juan, Joon Ching

    2015-05-01

    The unceasing rise of greenhouse gas emission has led to global warming and climate change. Global concern on this phenomenon has put forward the microalgal-based CO2 sequestration aiming to sequester carbon back to the biosphere, ultimately reducing greenhouse effects. Microalgae have recently gained enormous attention worldwide, to be the valuable feedstock for renewable energy production, due to their high growth rates, high lipid productivities and the ability to sequester carbon. The photosynthetic process of microalgae uses atmospheric CO2 and CO2 from flue gases, to synthesize nutrients for their growth. In this review article, we will primarily discuss the efficiency of CO2 biosequestration by microalgae species, factors influencing microalgal biomass productions, microalgal cultivation systems, the potential and limitations of using flue gas for microalgal cultivation as well as the bio-refinery approach of microalgal biomass.

  2. Upconversion-based lidar measurements of atmospheric CO2

    DEFF Research Database (Denmark)

    Høgstedt, Lasse; Fix, Andreas; Wirth, Martin

    2016-01-01

    For the first time an upconversion based detection scheme is demonstrated for lidar measurements of atmospheric CO2-concentrations, with a hard target at a range of 3 km and atmospheric backscatter from a range of similar to 450 m. The pulsed signals at 1572 nm are upconverted to 635 nm, and dete......For the first time an upconversion based detection scheme is demonstrated for lidar measurements of atmospheric CO2-concentrations, with a hard target at a range of 3 km and atmospheric backscatter from a range of similar to 450 m. The pulsed signals at 1572 nm are upconverted to 635 nm...

  3. Monitoring Atmospheric CO2 From Space: Challenge & Approach

    Science.gov (United States)

    Lin, Bing; Harrison, F. Wallace; Nehrir, Amin; Browell, Edward; Dobler, Jeremy; Campbell, Joel; Meadows, Byron; Obland, Michael; Kooi, Susan; Fan, Tai-Fang; Ismail, Syed

    2015-01-01

    Atmospheric CO2 is the key radiative forcing for the Earth's climate and may contribute a major part of the Earth's warming during the past 150 years. Advanced knowledge on the CO2 distributions and changes can lead considerable model improvements in predictions of the Earth's future climate. Large uncertainties in the predictions have been found for decades owing to limited CO2 observations. To obtain precise measurements of atmospheric CO2, certain challenges have to be overcome. For an example, global annual means of the CO2 are rather stable, but, have a very small increasing trend that is significant for multi-decadal long-term climate. At short time scales (a second to a few hours), regional and subcontinental gradients in the CO2 concentration are very small and only in an order of a few parts per million (ppm) compared to the mean atmospheric CO2 concentration of about 400 ppm, which requires atmospheric CO2 space monitoring systems with extremely high accuracy and precision (about 0.5 ppm or 0.125%) in spatiotemporal scales around 75 km and 10-s. It also requires a decadal-scale system stability. Furthermore, rapid changes in high latitude environments such as melting ice, snow and frozen soil, persistent thin cirrus clouds in Amazon and other tropical areas, and harsh weather conditions over Southern Ocean all increase difficulties in satellite atmospheric CO2 observations. Space lidar approaches using Integrated Path Differential Absorption (IPDA) technique are considered to be capable of obtaining precise CO2 measurements and, thus, have been proposed by various studies including the 2007 Decadal Survey (DS) of the U.S. National Research Council. This study considers to use the Intensity-Modulated Continuous-Wave (IM-CW) lidar to monitor global atmospheric CO2 distribution and variability from space. Development and demonstration of space lidar for atmospheric CO2 measurements have been made through joint adventure of NASA Langley Research Center and

  4. Implications of "peak oil" for atmospheric CO2 and climate

    CERN Document Server

    Kharecha, P A

    2007-01-01

    Peaking of global oil production may have a large effect on future atmospheric CO2 amount and climate change, depending upon choices made for subsequent energy sources. We suggest that, if estimates of oil and gas reserves by the Energy Information Administration are realistic, it is feasible to keep atmospheric CO2 from exceeding approximately 450 ppm, provided that future exploitation of the huge reservoirs of coal and unconventional fossil fuels incorporates carbon capture and sequestration. Existing coal-fired power plants, without sequestration, must be phased out before mid-century to achieve this limit on atmospheric CO2. We also suggest that it is important to "stretch" oil reserves via energy efficiency, thus avoiding the need to extract liquid fuels from coal or unconventional fossil fuels. We argue that a rising price on carbon emissions is probably needed to keep CO2 beneath the 450 ppm ceiling.

  5. A 40-million-year history of atmospheric CO(2).

    Science.gov (United States)

    Zhang, Yi Ge; Pagani, Mark; Liu, Zhonghui; Bohaty, Steven M; Deconto, Robert

    2013-10-28

    The alkenone-pCO2 methodology has been used to reconstruct the partial pressure of ancient atmospheric carbon dioxide (pCO2) for the past 45 million years of Earth's history (Middle Eocene to Pleistocene epochs). The present long-term CO2 record is a composite of data from multiple ocean localities that express a wide range of oceanographic and algal growth conditions that potentially bias CO2 results. In this study, we present a pCO2 record spanning the past 40 million years from a single marine locality, Ocean Drilling Program Site 925 located in the western equatorial Atlantic Ocean. The trends and absolute values of our new CO2 record site are broadly consistent with previously published multi-site alkenone-CO2 results. However, new pCO2 estimates for the Middle Miocene are notably higher than published records, with average pCO2 concentrations in the range of 400-500 ppm. Our results are generally consistent with recent pCO2 estimates based on boron isotope-pH data and stomatal index records, and suggest that CO2 levels were highest during a period of global warmth associated with the Middle Miocene Climatic Optimum (17-14 million years ago, Ma), followed by a decline in CO2 during the Middle Miocene Climate Transition (approx. 14 Ma). Several relationships remain contrary to expectations. For example, benthic foraminiferal δ(18)O records suggest a period of deglaciation and/or high-latitude warming during the latest Oligocene (27-23 Ma) that, based on our results, occurred concurrently with a long-term decrease in CO2 levels. Additionally, a large positive δ(18)O excursion near the Oligocene-Miocene boundary (the Mi-1 event, approx. 23 Ma), assumed to represent a period of glacial advance and retreat on Antarctica, is difficult to explain by our CO2 record alone given what is known of Antarctic ice sheet history and the strong hysteresis of the East Antarctic Ice Sheet once it has grown to continental dimensions. We also demonstrate that in the

  6. Silicon microring refractometric sensor for atmospheric CO(2) gas monitoring.

    Science.gov (United States)

    Mi, Guangcan; Horvath, Cameron; Aktary, Mirwais; Van, Vien

    2016-01-25

    We report a silicon photonic refractometric CO(2) gas sensor operating at room temperature and capable of detecting CO(2) gas at atmospheric concentrations. The sensor uses a novel functional material layer based on a guanidine polymer derivative, which is shown to exhibit reversible refractive index change upon absorption and release of CO(2) gas molecules, and does not require the presence of humidity to operate. By functionalizing a silicon microring resonator with a thin layer of the polymer, we could detect CO(2) gas concentrations in the 0-500ppm range with a sensitivity of 6 × 10(-9) RIU/ppm and a detection limit of 20ppm. The microring transducer provides a potential integrated solution in the development of low-cost and compact CO(2) sensors that can be deployed as part of a sensor network for accurate environmental monitoring of greenhouse gases.

  7. Modeling Atmospheric CO2 Processes to Constrain the Missing Sink

    Science.gov (United States)

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

    2005-01-01

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

  8. Halloysite Nanotubes Capturing Isotope Selective Atmospheric CO2

    OpenAIRE

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

    2015-01-01

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

  9. Where does CO2 in Antarctica cool the atmosphere ?

    Science.gov (United States)

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

    2016-04-01

    In a recent study we have shown that for the high altitude plateau in Antarctica CO2 causes a surplus in infrared emission to space compared to what is emitted from the surface. This corresponds to a negative greenhouse effect, and is due to the fact that for this region the surface is typically colder than the atmosphere above, opposite to the rest of the world. As a consequence, for this region an increase in CO2 leads to an increase in the energy loss to space, leading to an increase in the negative greenhouse effect. We now studied in more detail the radiative effect of CO2 and compared the results with available measurements from Antarctica. H. Schmithüsen, J. Notholt, G. Köngig-Langlo, T, Jung. How increasing CO2 leads to an increased negative greenhouse effect in Antarctica. Geophysical Research Letters, in press, 2015. doi: 10.1002/2015GL066749.

  10. Water Loss from Terrestrial Planets with CO2-rich Atmospheres

    Science.gov (United States)

    Wordsworth, R. D.; Pierrehumbert, R. T.

    2013-12-01

    Water photolysis and hydrogen loss from the upper atmospheres of terrestrial planets is of fundamental importance to climate evolution but remains poorly understood in general. Here we present a range of calculations we performed to study the dependence of water loss rates from terrestrial planets on a range of atmospheric and external parameters. We show that CO2 can only cause significant water loss by increasing surface temperatures over a narrow range of conditions, with cooling of the middle and upper atmosphere acting as a bottleneck on escape in other circumstances. Around G-stars, efficient loss only occurs on planets with intermediate CO2 atmospheric partial pressures (0.1-1 bar) that receive a net flux close to the critical runaway greenhouse limit. Because G-star total luminosity increases with time but X-ray and ultraviolet/ultravoilet luminosity decreases, this places strong limits on water loss for planets like Earth. In contrast, for a CO2-rich early Venus, diffusion limits on water loss are only important if clouds caused strong cooling, implying that scenarios where the planet never had surface liquid water are indeed plausible. Around M-stars, water loss is primarily a function of orbital distance, with planets that absorb less flux than ~270 W m-2 (global mean) unlikely to lose more than one Earth ocean of H2O over their lifetimes unless they lose all their atmospheric N2/CO2 early on. Because of the variability of H2O delivery during accretion, our results suggest that many "Earth-like" exoplanets in the habitable zone may have ocean-covered surfaces, stable CO2/H2O-rich atmospheres, and high mean surface temperatures.

  11. Climate change and CO2 removal from the atmosphere

    NARCIS (Netherlands)

    Schuiling, R.D.

    2014-01-01

    Several methods have been proposed in recent years to counteract climate change and ocean acidification by removing CO2 from the atmosphere (Carbon Dioxide Removal). The most versatile and widely applicable of these methods is enhanced weathering of olivine, which is capable of removing billions of

  12. ROOT-GROWTH AND FUNCTIONING UNDER ATMOSPHERIC CO2 ENRICHMENT

    NARCIS (Netherlands)

    STULEN, [No Value; DENHERTOG, J

    1993-01-01

    This paper examines the extent to which atmospheric CO2 enrichment may influence growth of plant roots and function in terms of uptake of water and nutrients, and carbon allocation towards symbionts. It is concluded that changes in dry matter allocation greatly depend on the experimental conditions

  13. Thermal decomposition of dolomite under CO2-air atmosphere

    Science.gov (United States)

    Subagjo, Wulandari, Winny; Adinata, Pratitis Mega; Fajrin, Anita

    2017-01-01

    This paper reports a study on thermal decomposition of dolomite under CO2-air. Calcination was carried out non-isothermally by using thermogravimetry analysis-differential scanning calorimetry (TGA-DSC) with a heating rate of 10°C/minute in an air atmosphere as well as 10 vol% CO2 and 90 vol% air atmosphere from 25 to 950°C. In addition, a thermodynamic modeling was also carried out to simulate dolomite calcination in different level of CO2-air atmosphere by using FactSage® 7.0. The the main constituents of typical dolomite from Gresik, East Java include MgCO3 (magnesite), CaCO3 (calcite), Ca(OH)2, CaO, MgO, and less than 1% of metal impurities. Based on the kinetics analysis from TGA results, it is found that non-isothermal dolomite calcination in 10 vol% CO2 atmosphere is occurred in a two-stage reaction; the first stage is the decomposition of magnesite at 650-740 °C with activation energy of 161.23 kJ/mol, and the second stage is the decomposition of calcite at 775-820 °C with activation energy of 162.46 kJ/mol. The magnesite decomposition is found to follow nucleation reaction mechanism of Avrami Eroveyef (A3), while calcite decomposition follows second order chemical reaction equation. Thermodynamic modeling supports these kinetic analyses. The results of this research give insight to the kinetics of dolomite decomposition in CO2-air atmosphere.

  14. Algal constraints on the Cenozoic history of atmospheric CO2?

    Directory of Open Access Journals (Sweden)

    R. E. M. Rickaby

    2007-01-01

    Full Text Available An urgent question for future climate, in light of increased burning of fossil fuels, is the temperature sensitivity of the climate system to atmospheric carbon dioxide (pCO2. To date, no direct proxy for past levels of pCO2 exists beyond the reach of the polar ice core records. We propose a new methodology for placing an upper constraint on pCO2 over the Cenozoic based on the living geological record. Specifically, our premise is that the contrasting calcification tolerance of various extant species of coccolithophore to raised pCO2 reflects an "evolutionary memory" of past atmospheric composition. The different times of first emergence of each morphospecies allows an upper constraint of past pCO2 to be placed on Cenozoic timeslices. Further, our hypothesis has implications for the response of marine calcifiers to ocean acidification. Geologically "ancient" species, which have survived large changes in ocean chemistry, are likely more resilient to predicted acidification.

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

    Science.gov (United States)

    Widory, David; Javoy, Marc

    2003-10-01

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

  16. Atmospheric CO2 enrichment facilitates cation release from soil.

    Science.gov (United States)

    Cheng, L; Zhu, J; Chen, G; Zheng, X; Oh, N-H; Rufty, T W; Richter, D deB; Hu, S

    2010-03-01

    Atmospheric CO(2) enrichment generally stimulates plant photosynthesis and nutrient uptake, modifying the local and global cycling of bioactive elements. Although nutrient cations affect the long-term productivity and carbon balance of terrestrial ecosystems, little is known about the effect of CO(2) enrichment on cation availability in soil. In this study, we present evidence for a novel mechanism of CO(2)-enhancement of cation release from soil in rice agricultural systems. Elevated CO(2) increased organic C allocation belowground and net H(+) excretion from roots, and stimulated root and microbial respiration, reducing soil redox potential and increasing Fe(2+) and Mn(2+) in soil solutions. Increased H(+), Fe(2+), and Mn(2+) promoted Ca(2+) and Mg(2+) release from soil cation exchange sites. These results indicate that over the short term, elevated CO(2) may stimulate cation release from soil and enhance plant growth. Over the long-term, however, CO(2)-induced cation release may facilitate cation losses and soil acidification, negatively feeding back to the productivity of terrestrial ecosystems.

  17. Effects of Atmospheric CO2 Enrichment on Soil CO2 Efflux in a Young Longleaf Pine System

    Directory of Open Access Journals (Sweden)

    G. Brett Runion

    2012-01-01

    Full Text Available The southeastern landscape is composed of agricultural and forest systems that can store carbon (C in standing biomass and soil. Research is needed to quantify the effects of elevated atmospheric carbon dioxide (CO2 on terrestrial C dynamics including CO2 release back to the atmosphere and soil sequestration. Longleaf pine savannahs are an ecologically and economically important, yet understudied, component of the southeastern landscape. We investigated the effects of ambient and elevated CO2 on soil CO2 efflux in a young longleaf pine system using a continuous monitoring system. A significant increase (26.5% in soil CO2 efflux across 90 days was observed under elevated CO2; this occurred for all weekly and daily averages except for two days when soil temperature was the lowest. Soil CO2 efflux was positively correlated with soil temperature with a trend towards increased efflux response to temperature under elevated CO2. Efflux was negatively correlated with soil moisture and was best represented using a quadratic relationship. Soil CO2 efflux was not correlated with root biomass. Our data indicate that, while elevated CO2 will increase feedback of CO2 to the atmosphere via soil efflux, terrestrial ecosystems will remain potential sinks for atmospheric CO2 due to greater biomass production and increased soil C sequestration.

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

    Science.gov (United States)

    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 aestivumyeast 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 1.2-1.9-fold higher than under ambient CO2. This indicates the increased activity of microorganisms, which leads to accelerated C turnover in soil under elevated CO2. Our results clearly showed that the functional characteristics of the soil microbial community (i.e. specific growth rates and enzymes activity) rather than total microbial biomass

  19. Effects of Elevated Atmospheric CO(2) on Rhizosphere Soil Microbial Communities in a Mojave Desert Ecosystem.

    Science.gov (United States)

    Nguyen, L M; Buttner, M P; Cruz, P; Smith, S D; Robleto, E A

    2011-10-01

    The effects of elevated atmospheric carbon dioxide [CO(2)] on microbial communities in arid rhizosphere soils beneath Larrea tridentata were examined. Roots of Larrea were harvested from plots fumigated with elevated or ambient levels of [CO(2)] using Free-Air CO(2) Enrichment (FACE) technology. Twelve bacterial and fungal rRNA gene libraries were constructed, sequenced and categorized into operational taxonomical units (OTUs). There was a significant decrease in OTUs within the Firmicutes (bacteria) in elevated [CO(2)], and increase in Basiomycota (fungi) in rhizosphere soils of plots exposed to ambient [CO(2)]. Phylogenetic analyses indicated that OTUs belonged to a wide range of bacterial and fungal taxa. To further study changes in bacterial communities, Quantitative Polymerase Chain Reaction (QPCR) was used to quantify populations of bacteria in rhizosphere soil. The concentration of total bacteria 16S rDNA was similar in conditions of enriched and ambient [CO(2)]. However, QPCR of Gram-positive microorganisms showed a 43% decrease in the population in elevated [CO(2)]. The decrease in representation of Gram positives and the similar values for total bacterial DNA suggest that the representation of other bacterial taxa was promoted by elevated [CO(2)]. These results indicate that elevated [CO(2)] changes structure and representation of microorganisms associated with roots of desert plants.

  20. Climate Sensitivity, Sea Level, and Atmospheric CO2

    CERN Document Server

    Hansen, James; Russell, Gary; Kharecha, Pushker

    2012-01-01

    Cenozoic temperature, sea level and CO2 co-variations provide insights into climate sensitivity to external forcings and sea level sensitivity to climate change. Pleistocene climate oscillations imply a fast-feedback climate sensitivity 3 {\\pm} 1 {\\deg}C for 4 W/m2 CO2 forcing for the average of climate states between the Holocene and Last Glacial Maximum (LGM), the error estimate being large and partly subjective because of continuing uncertainty about LGM global surface climate. Slow feedbacks, especially change of ice sheet size and atmospheric CO2, amplify total Earth system sensitivity. Ice sheet response time is poorly defined, but we suggest that hysteresis and slow response in current ice sheet models are exaggerated. We use a global model, simplified to essential processes, to investigate state-dependence of climate sensitivity, finding a strong increase in sensitivity when global temperature reaches early Cenozoic and higher levels, as increased water vapor eliminates the tropopause. It follows that...

  1. Water loss from terrestrial planets with CO2-rich atmospheres

    CERN Document Server

    Wordsworth, Robin

    2013-01-01

    Water photolysis and hydrogen loss from the upper atmospheres of terrestrial planets is of fundamental importance to climate evolution but remains poorly understood in general. Here we present a range of calculations we performed to study the dependence of water loss rates from terrestrial planets on atmospheric composition (CO2 and N2 levels), planetary mass, and external parameters (stellar spectrum, orbital distance and impacts). From coupled 1D climate and escape modeling, we show that CO2 can only cause significant water loss by increasing surface temperatures over a narrow range of conditions, with cooling of the middle and upper atmosphere acting as a bottleneck on escape in other circumstances. Around G-stars, efficient loss only occurs on planets with intermediate CO2 atmospheric partial pressures (0.1 to 1 bar) that receive a net flux close to the critical runaway greenhouse limit. Because G-star total luminosity increases with time but XUV/UV luminosity decreases, this places strong limits on moist...

  2. The BErkeley Atmospheric CO2 Observation Network: initial evaluation

    Science.gov (United States)

    Shusterman, Alexis A.; Teige, Virginia E.; Turner, Alexander J.; Newman, Catherine; Kim, Jinsol; Cohen, Ronald C.

    2016-10-01

    With the majority of the world population residing in urban areas, attempts to monitor and mitigate greenhouse gas emissions must necessarily center on cities. However, existing carbon dioxide observation networks are ill-equipped to resolve the specific intra-city emission phenomena targeted by regulation. Here we describe the design and implementation of the BErkeley Atmospheric CO2 Observation Network (BEACO2N), a distributed CO2 monitoring instrument that utilizes low-cost technology to achieve unprecedented spatial density throughout and around the city of Oakland, California. We characterize the network in terms of four performance parameters - cost, reliability, precision, and systematic uncertainty - and find the BEACO2N approach to be sufficiently cost-effective and reliable while nonetheless providing high-quality atmospheric observations. First results from the initial installation successfully capture hourly, daily, and seasonal CO2 signals relevant to urban environments on spatial scales that cannot be accurately represented by atmospheric transport models alone, demonstrating the utility of high-resolution surface networks in urban greenhouse gas monitoring efforts.

  3. [Response and acclimation of photosynthesis in rice leaves to free-air CO2 enrichment (FACE)].

    Science.gov (United States)

    Liao, Yi; Chen, Genyun; Zhang, Haibo; Cai, Shiqing; Zhu, Jianguo; Han, Yong; Liu, Gang; Xu, Daquan

    2002-10-01

    The net photosynthetic rate (Pn), water use efficiency (WUE), and apparent quantum yield of carbon assimilation of rice leaves were boserved contrastively under ambient air (380 mumol.mol-1 CO2) and FACE (580 mumol.mol-1CO2). The results showed that the observed index under FACE were significantly higher than those under ambient air. Nevertheless, along with the time of high CO2 treatment prolonged, the enhancement effect of high CO2 on net photosynthetic rate declined gradually. At the same CO2 concentration, Pn and carboxylation efficiency (CE) in rice leaves under FACE were lower than those under ambient air. Although the stomatal conductances in FACE leaves was obviously lower than that in ambient leaves, their intercellular CO2 concentrations were not significantly different, which implied that the photosynthetic down-regulation in rice leaves grown under FACE was not caused by the decrease of stomatal conductance.

  4. On the statistical optimality of CO2 atmospheric inversions assimilating CO2 column retrievals

    Directory of Open Access Journals (Sweden)

    F. Chevallier

    2015-04-01

    Full Text Available The extending archive of the Greenhouse Gases Observing SATellite (GOSAT measurements (now covering about six years allows increasingly robust statistics to be computed, that document the performance of the corresponding retrievals of the column-average dry air-mole fraction of CO2 (XCO2. Here, we compare a model simulation constrained by surface air-sample measurements with one of the GOSAT retrieval products (NASA's ACOS. The retrieval-minus-model differences result from various error sources, both in the retrievals and in the simulation: we discuss the plausibility of the origin of the major patterns. We find systematic retrieval errors over the dark surfaces of high-latitude lands and over African savannahs. More importantly, we also find a systematic over-fit of the GOSAT radiances by the retrievals over land for the high-gain detector mode, which is the usual observation mode. The over-fit is partially compensated by the retrieval bias-correction. These issues are likely common to other retrieval products and may explain some of the surprising and inconsistent CO2 atmospheric inversion results obtained with the existing GOSAT retrieval products. We suggest that reducing the observation weight in the retrieval schemes (for instance so that retrieval increments to the retrieval prior values are halved for the studied retrieval product would significantly improve the retrieval quality and reduce the need for (or at least reduce the complexity of ad-hoc retrieval bias correction. More generally, we demonstrate that atmospheric inversions cannot be rigorously optimal when assimilating XCO2 retrievals, even with averaging kernels.

  5. An estimate of monthly global emissions of anthropogenic CO2: Impact on the seasonal cycle of atmospheric CO2

    Energy Technology Data Exchange (ETDEWEB)

    Erickson, D [Oak Ridge National Laboratory (ORNL); Mills, R [Oak Ridge National Laboratory (ORNL); Gregg, J [University of Maryland; Blasing, T J [ORNL; Hoffman, F [Oak Ridge National Laboratory (ORNL); Andres, Robert Joseph [ORNL; Devries, M [Oak Ridge National Laboratory (ORNL); Zhu, Z [NASA Goddard Space Flight Center; Kawa, S [NASA Goddard Space Flight Center

    2008-01-01

    Monthly estimates of the global emissions of anthropogenic CO2 are presented. Approximating the seasonal CO2 emission cycle using a 2-harmonic Fourier series with coefficients as a function of latitude, the annual fluxes are decomposed into monthly flux estimates based on data for the United States and applied globally. These monthly anthropogenic CO2 flux estimates are then used to model atmospheric CO2 concentrations using meteorological fields from the NASA GEOS-4 data assimilation system. We find that the use of monthly resolved fluxes makes a significant difference in the seasonal cycle of atmospheric CO2 in and near those regions where anthropogenic CO2 is released to the atmosphere. Local variations of 2-6 ppmv CO2 in the seasonal cycle amplitude are simulated; larger variations would be expected if smaller source-receptor distances could be more precisely specified using a more refined spatial resolution. We also find that in the midlatitudes near the sources, synoptic scale atmospheric circulations are important in the winter and that boundary layer venting and diurnal rectifier effects are more important in the summer. These findings have implications for inverse-modeling efforts that attempt to estimate surface source/sink regions especially when the surface sinks are colocated with regions of strong anthropogenic CO2 emissions.

  6. Changes in calcification of coccoliths under stable atmospheric CO2

    DEFF Research Database (Denmark)

    Berger, C.; Meier, K. J. S.; Kinkel, H.;

    2014-01-01

    The response of coccolithophore calcification to ocean acidification has been studied in culture experiments as well as in present and past oceans. The response, however, is different between species and strains, and for the relatively small carbonate chemistry changes observed in natural...... North Atlantic Ocean. The pre-industrial Holocene, with its predominantly stable atmospheric CO2, provides the conditions for such a comprehensive analysis. For an analysis on changes in major components of Holocene coccolithophores under natural conditions, the family Noelaerhabdaceae was selected...

  7. Deep Sea Memory of High Atmospheric CO2 Concentration

    Science.gov (United States)

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

    2015-04-01

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

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

    Directory of Open Access Journals (Sweden)

    Lucas C R Silva

    Full Text Available BACKGROUND: 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. 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 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. 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.

  9. Elevated Atmospheric CO2 Affects Ectomycorrhizal Species Abundance and Increases Sporocarp Production under Field Conditions

    Directory of Open Access Journals (Sweden)

    Douglas L. Godbold

    2015-04-01

    Full Text Available Anthropogenic activities during the last century have increased levels of atmospheric CO2. Forest net primary productivity increases in response to elevated CO2, altering the quantity and quality of carbon supplied to the rhizosphere. Ectomycorrhizal fungi form obligate symbiotic associations with the fine roots of trees that mediate improved scavenging for nutrients in exchange for a carbohydrate supply. Understanding how the community structure of ectomycorrhizal fungi is altered by climate change is important to further our understanding of ecosystem function. Betula pendula and Fagus sylvatica were grown in an elevated CO2 atmosphere delivered using free air carbon dioxide enrichment (FACE under field conditions in the U.K., and Picea abies was grown under elevated CO2 in glass domes in the Czech Republic. We used morphotyping and sequencing of the internal transcribed spacer region of the fungal ribosomal operon to study ectomycorrhizal community structure. Under FACE, un-colonised roots tips increased in abundance for Fagus sylvatica, and during 2006, sporocarp biomass of Peziza badia significantly increased. In domes, ectomycorrhizal community composition shifted from short-distance and smooth medium-distance to contact exploration types. Supply and competition for carbon belowground can influence ectomycorrhizal community structure with the potential to alter ecosystem function.

  10. Leaf conductance decreased under free-air CO2 enrichment (FACE) for three perennials in the Nevada desert

    Science.gov (United States)

    Nowak, Robert S.; Defalco, Lesley A.; Wilcox, Carolyn S.; Jordan, Dean N.; Coleman, James S.; Seemann, Jeffrey R.; Smith, Stanley D.

    2001-01-01

    A common response of plants to elevated atmospheric CO2 concentration (CO2) is decreased leaf conductance. Consequently, leaf temperature is predicted to increase under elevated CO2.Diurnal patterns of leaf conductance and temperature were measured for three desert perennials, the C3 shrub Larrea tridentata, C3 tussock grass Achnatherum hymenoides and C4tussock grass Pleuraphis rigida, at the Nevada Desert FACE facility. Measurements were made on ambient and c. 550 µmol mol−1 CO2 plots through both a wet and dry year.Reductions in conductance were 35%, 20% and 13% for Pleuraphis, Achnatherum and Larrea, respectively. Decreased conductance occurred throughout the day only for Pleuraphis. Both C3species had smaller CO2 effects during dry periods than wet. Leaf temperature did not differ significantly between elevated and ambient CO2 for any species. Comparisons of blower-control and nonring plots indicated that the FACE apparatus did not confound our results.All three species exhibited decreased leaf conductance under elevated CO2, although reductions were not uniform during the day or among years. Nonetheless, leaf energy balance was only minimally changed for these microphyllous desert perennials.

  11. Enhanced photosynthetic efficiency in trees world-wide by rising atmospheric CO2 levels

    Science.gov (United States)

    Ehlers, Ina; Wieloch, Thomas; Groenendijk, Peter; Vlam, Mart; van der Sleen, Peter; Zuidema, Pieter A.; Robertson, Iain; Schleucher, Jürgen

    2014-05-01

    The atmospheric CO2 concentration is increasing rapidly due to anthropogenic emissions but the effect on the Earth's biosphere is poorly understood. The ability of the biosphere to fix CO2 through photosynthesis will determine future atmospheric CO2 concentrations as well as future productivity of crops and forests. Manipulative CO2 enrichment experiments (e.g. FACE) are limited to (i) short time spans, (ii) few locations and (iii) large step increases in [CO2]. Here, we apply new stable isotope methodology to tree-ring archives, to study the effect of increasing CO2 concentrations retrospectively during the past centuries. We cover the whole [CO2] increase since industrialization, and sample trees with global distribution. Instead of isotope ratios of whole molecules, we use intramolecular isotope distributions, a new tool for tree-ring analysis with decisive advantages. In experiments on annual plants, we have found that the intramolecular distribution of deuterium (equivalent to ratios of isotopomer abundances) in photosynthetic glucose depends on growth [CO2] and reflects the metabolic flux ratio of photosynthesis to photorespiration. By applying this isotopomer methodology to trees from Oak Ridge FACE experiment, we show that this CO2 response is present in trees on the leaf level. This CO2 dependence constitutes a physiological signal, which is transferred to the wood of the tree rings. In trees from 13 locations on all continents the isotopomer ratio of tree-ring cellulose is correlated to atmospheric [CO2] during the past 200 years. The shift of the isotopomer ratio is universal for all 12 species analyzed, including both broad-leafed trees and conifers. Because the trees originate from sites with widely differing D/H ratios of precipitation, the generality of the response demonstrates that the signal is independent of the source isotope ratio, because it is encoded in an isotopomer abundance ratio. This decoupling of climate signals and physiological

  12. Impacts of Elevated Atmospheric CO2 and O3 on Paper Birch (Betula papyrifera: Reproductive Fitness

    Directory of Open Access Journals (Sweden)

    Joseph N. T. Darbah

    2007-01-01

    Full Text Available Atmospheric CO2 and tropospheric O3 are rising in many regions of the world. Little is known about how these two commonly co-occurring gases will affect reproductive fitness of important forest tree species. Here, we report on the long-term effects of CO3 and O3 for paper birch seedlings exposed for nearly their entire life history at the Aspen FACE (Free Air Carbon Dioxide Enrichment site in Rhinelander, WI. Elevated CO2 increased both male and female flower production, while elevated O3 increased female flower production compared to trees in control rings. Interestingly, very little flowering has yet occurred in combined treatment. Elevated CO2 had significant positive effect on birch catkin size, weight, and germination success rate (elevated CO2 increased germination rate of birch by 110% compared to ambient CO2 concentrations, decreased seedling mortality by 73%, increased seed weight by 17%, increased root length by 59%, and root-to-shoot ratio was significantly decreased, all at 3 weeks after germination, while the opposite was true of elevated O3 (elevated O3 decreased the germination rate of birch by 62%, decreased seed weight by 25%, and increased root length by 15%. Under elevated CO2, plant dry mass increased by 9 and 78% at the end of 3 and 14 weeks, respectively. Also, the root and shoot lengths, as well as the biomass of the seedlings, were increased for seeds produced under elevated CO2, while the reverse was true for seedlings from seeds produced under the elevated O3. Similar trends in treatment differences were observed in seed characteristics, germination, and seedling development for seeds collected in both 2004 and 2005. Our results suggest that elevated CO2 and O3 can dramatically affect flowering, seed production, and seed quality of paper birch, affecting reproductive fitness of this species.

  13. Marine biological controls on atmospheric CO2 and climate

    Science.gov (United States)

    Mcelroy, M. B.

    1983-01-01

    It is argued that the ocean is losing N gas faster than N is being returned to the ocean, and that replenishment of the N supply in the ocean usually occurs during ice ages. Available N from river and estruarine transport and from rainfall after formation by lightning are shown to be at a rate too low to compensate for the 10,000 yr oceanic lifetime of N. Ice sheets advance and transfer moraine N to the ocean, lower the sea levels, erode the ocean beds, promote greater biological productivity, and reduce CO2. Ice core samples have indicated a variability in the atmospheric N content that could be attributed to the ice age scenario.

  14. Variable conductivity and embolism in roots, trunks and branches of tree species growing under future atmospheric CO2 concentration (DUKE FACE site): impacts on whole-plant hydraulic performance and carbon assimilation

    Science.gov (United States)

    domec, J.; Palmroth, S.; Oren, R.; Johnson, D. M.; Ward, E. J.; McCulloh, K.; Gonzalez, C.; Warren, J.

    2013-12-01

    Anatomical and physiological acclimation to water stress of the tree hydraulic system involves tradeoffs between maintenance of stomatal conductance and loss of hydraulic conductivity, with short-term impacts on photosynthesis and long-term consequences to survival and growth. Here we study the role of variations in root, trunk and branch maximum hydraulic specific conductivity (Ks-max) under high and low soil moisture in determining whole-tree hydraulic conductance (Ktree) and in mediating stomatal control of gas exchange in loblolly pine trees growing under ambient and elevated CO2 (CO2a and CO2e). We hypothesized that Ktree would adjust to CO2e, through an increase in root and branch Ks-max in response to anatomical adjustments. Embolism in roots explained the loss of Ktree and therefore indirectly constituted a hydraulic signal involved in stomatal regulation and in the reduction of canopy conductance and carbon assimilation. Across roots, trunk and branches, the increase in Ks-max was associated with a decrease resistance to drought, a consequence of structural acclimation such as larger conduits and lower wood density. In loblolly pine, higher xylem dysfunction under CO2e might impact tree performance in a future climate when increased evaporative demand could cause a greater loss of hydraulic function. The results contributed to our knowledge of the physiological and morphological mechanisms underpinning the responses of tree species to drought and more generally to global change.

  15. Atmospheric Variability of CO2 impact on space observation Requirements

    Science.gov (United States)

    Swanson, A. L.; Sen, B.; Newhart, L.; Segal, G.

    2009-12-01

    If International governments are to reduce GHG levels by 80% by 2050, as recommended by most scientific bodies concerned with avoiding the most hazardous changes in climate, then massive investments in infrastructure and new technology will be required over the coming decades. Such an investment will be a huge commitment by governments and corporations, and while it will offer long-term dividends in lower energy costs, a healthier environment and averted additional global warming, the shear magnitude of upfront costs will drive a call for a monitoring and verification system. Such a system will be required to offer accountability to signatories of governing bodies, as well as, for the global public. Measuring the average global distribution of CO2 is straight forward, as exemplified by the long running station measurements managed by NOAA’s Global Monitoring Division that includes the longterm Keeling record. However, quantifying anthropogenic and natural source/sink distributions and atmospheric mixing have been much more difficult to constrain. And, yet, an accurate accounting of all anthropogenic source strengths is required for Global Treaty verification. The only way to accurately assess Global GHG emissions is to construct an integrated system of ground, air and space based observations with extensive chemical modeling capabilities. We look at the measurement requirements for the space based component of the solutions. To determine what space sensor performance requirements for ground resolution, coverage, and revisit, we have analyzed regional CO2 distributions and variability using NASA and NOAA aircraft flight campaigns. The results of our analysis are presented as variograms showing average spatial variability over several Northern Hemispheric regions. There are distinct regional differences with the starkest contrast between urban versus rural and Coastal Asia versus Coastal US. The results suggest specific consequences on what spatial and temporal

  16. Changes in calcification of coccoliths under stable atmospheric CO2

    Science.gov (United States)

    Berger, C.; Meier, K. J. S.; Kinkel, H.; Baumann, K.-H.

    2014-02-01

    The response of coccolithophore calcification to ocean acidification has been studied in culture experiments as well as in present and past oceans. The response, however, is different between species and strains, and for the relatively small carbonate chemistry changes observed in natural environments, a uniform response of the entire coccolithophore community has not been documented so far. Moreover, previous palaeo-studies basically focus on changes in coccolith weight due to increasing CO2 and the resulting changes in the carbonate system, and only few studies focus on the influence of other environmental factors. In order to untangle changes in coccolithophore calcification due to environmental factors such as temperature and/or productivity from changes caused by increasing pCO2 and decreasing carbonate ion concentration, we here present a study on coccolith calcification from the Holocene North Atlantic Ocean. The pre-industrial Holocene, with its predominantly stable atmospheric CO2, provides the conditions for such a comprehensive analysis. For an analysis on changes in major components of Holocene coccolithophores under natural conditions, the family Noelaerhabdaceae was selected, which constitutes the main part of the assemblage in the North Atlantic. Records of average coccolith weights from three Holocene sediment cores along a north-south transect in the North Atlantic were analysed. During the Holocene, mean weight (and therefore calcification) of Noelaerhabdaceae (Emiliania huxleyi and Gephyrocapsa) coccoliths decreased at the Azores (Geofar KF 16) from around 7 to 6 pg, but increased at the Rockall Plateau (ODP site 980) from around 6 to 8 pg, and at the Vøring Plateau (MD08-3192) from 7 to 10 pg. The amplitude of average weight variability is within the range of glacial-interglacial changes that were interpreted to be an effect of decreasing carbonate ion concentration. By comparison with SEM assemblage counts, we show that weight changes are not

  17. Capturing atmospheric CO2 using supported amine sorbents for microalgae cultivation

    NARCIS (Netherlands)

    Brilman, D.W.F.; Garcia, Alba L.; Veneman, R.

    2013-01-01

    In this work, we propose, demonstrate and evaluate the concept of atmospheric CO2 capture for enhanced algae cultivation (and horticulture), as alternative to the application of flue gas derived CO2. A supported amine sorbent was prepared and able to capture CO2 at atmospheric conditions and releasi

  18. Radiocarbon observations in atmospheric CO2: determining fossil fuel CO2 over Europe using Jungfraujoch observations as background.

    Science.gov (United States)

    Levin, Ingeborg; Hammer, Samuel; Kromer, Bernd; Meinhardt, Frank

    2008-03-01

    Monthly mean 14CO2 observations at two regional stations in Germany (Schauinsland observatory, Black Forest, and Heidelberg, upper Rhine valley) are compared with free tropospheric background measurements at the High Alpine Research Station Jungfraujoch (Swiss Alps) to estimate the regional fossil fuel CO2 surplus at the regional stations. The long-term mean fossil fuel CO2 surplus at Schauinsland is 1.31+/-0.09 ppm while it is 10.96+/-0.20 ppm in Heidelberg. No significant trend is observed at both sites over the last 20 years. Strong seasonal variations of the fossil fuel CO2 offsets indicate a strong seasonality of emissions but also of atmospheric dilution of ground level emissions by vertical mixing.

  19. Separation of biospheric and fossil fuel fluxes of CO2 by atmospheric inversion of CO2 and 14CO2 measurements: Observation System Simulations

    Science.gov (United States)

    Basu, Sourish; Bharat Miller, John; Lehman, Scott

    2016-05-01

    National annual total CO2 emissions from combustion of fossil fuels are likely known to within 5-10 % for most developed countries. However, uncertainties are inevitably larger (by unknown amounts) for emission estimates at regional and monthly scales, or for developing countries. Given recent international efforts to establish emission reduction targets, independent determination and verification of regional and national scale fossil fuel CO2 emissions are likely to become increasingly important. Here, we take advantage of the fact that precise measurements of 14C in CO2 provide a largely unbiased tracer for recently added fossil-fuel-derived CO2 in the atmosphere and present an atmospheric inversion technique to jointly assimilate observations of CO2 and 14CO2 in order to simultaneously estimate fossil fuel emissions and biospheric exchange fluxes of CO2. Using this method in a set of Observation System Simulation Experiments (OSSEs), we show that given the coverage of 14CO2 measurements available in 2010 (969 over North America, 1063 globally), we can recover the US national total fossil fuel emission to better than 1 % for the year and to within 5 % for most months. Increasing the number of 14CO2 observations to ˜ 5000 per year over North America, as recently recommended by the National Academy of Science (NAS) (Pacala et al., 2010), we recover monthly emissions to within 5 % for all months for the US as a whole and also for smaller, highly emissive regions over which the specified data coverage is relatively dense, such as for the New England states or the NY-NJ-PA tri-state area. This result suggests that, given continued improvement in state-of-the art transport models, a measurement program similar in scale to that recommended by the NAS can provide for independent verification of bottom-up inventories of fossil fuel CO2 at the regional and national scale. In addition, we show that the dual tracer inversion framework can detect and minimize biases in

  20. [Monitoring Atmospheric CO2 and delta(13)C (CO2) Background Levels at Shangdianzi Station in Beijing, China].

    Science.gov (United States)

    Xia, Ling-ju; Zhou, Ling-xi; Liu, Li-xin; Zhang, Gen

    2016-04-15

    The study presented time series of atmospheric CO2 concentrations from flask sampling at SDZ regional station in Beijing during 2007 and 2013, together with delta(13)CO2) values during 2009 and 2013. The "representative data" of CO2 and delta(13)C (CO2) were selected from the complete data for further analysis. Annual CO2 concentrations increased from 385.6 x 10(-6) in 2007 to 398.1 x 10(-6) in 2013, with an average growth rate of 2.0 x 10(-6) a(-1), while the delta(13)C values decreased from -8.38% per hundred in 2009 to -8.52% per hundred in 2013, with a mean growth rate of -0.03% per hundred x a(-1). The absolute increase of CO2 from 2007 to 2008 reached the lowest level during 2007 and 2013, possibly due to relatively less carbon emissions during the 2008 Olympic Games period. The peak-to-peak amplitudes of atmospheric CO2 and delta(13)C seasonal variations were 23. 9 x 10 -6 and 1. 03%o, respectively. The isotopic signatures of CO2 sources/sinks were also discussed in this study. The delta8 value for heating season I (Jan. 01-Mar. 14) was -21.30% per hundred, while -25.39% per hundred for heating season 11 (Nov. 15-Dec.31) , and for vegetative season (Mar. 15-Nov. 14) the delta(bio) value was estimated to be -21.28% per hundred, likely suggesting the significant impact of fossil fuel and corn straw combustions during winter heating season and biological activities during vegetative season.

  1. A test of sensitivity to convective transport in a global atmospheric CO2 simulation

    OpenAIRE

    Bian, H.; Kawa, S. R.; M. Chin; Pawson, S.; Zhu, Z.; Rasch, P.; Wu, S.

    2011-01-01

    Two approximations to convective transport have been implemented in an offline chemistry transport model (CTM) to explore the impact on calculated atmospheric CO2 distributions. Global CO2 in the year 2000 is simulated using the CTM driven by assimilated meteorological fields from the NASA's Goddard Earth Observation System Data Assimilation System, Version 4 (GEOS-4). The model simulates atmospheric CO2 by adopting the same CO2 emission inventory and dynamical modules as described in Kawa et...

  2. Simulated effect of calcification feedback on atmospheric CO2 and ocean acidification

    Science.gov (United States)

    Zhang, Han; Cao, Long

    2016-02-01

    Ocean uptake of anthropogenic CO2 reduces pH and saturation state of calcium carbonate materials of seawater, which could reduce the calcification rate of some marine organisms, triggering a negative feedback on the growth of atmospheric CO2. We quantify the effect of this CO2-calcification feedback by conducting a series of Earth system model simulations that incorporate different parameterization schemes describing the dependence of calcification rate on saturation state of CaCO3. In a scenario with SRES A2 CO2 emission until 2100 and zero emission afterwards, by year 3500, in the simulation without CO2-calcification feedback, model projects an accumulated ocean CO2 uptake of 1462 PgC, atmospheric CO2 of 612 ppm, and surface pH of 7.9. Inclusion of CO2-calcification feedback increases ocean CO2 uptake by 9 to 285 PgC, reduces atmospheric CO2 by 4 to 70 ppm, and mitigates the reduction in surface pH by 0.003 to 0.06, depending on the form of parameterization scheme used. It is also found that the effect of CO2-calcification feedback on ocean carbon uptake is comparable and could be much larger than the effect from CO2-induced warming. Our results highlight the potentially important role CO2-calcification feedback plays in ocean carbon cycle and projections of future atmospheric CO2 concentrations.

  3. Simulated effect of calcification feedback on atmospheric CO2 and ocean acidification.

    Science.gov (United States)

    Zhang, Han; Cao, Long

    2016-01-01

    Ocean uptake of anthropogenic CO2 reduces pH and saturation state of calcium carbonate materials of seawater, which could reduce the calcification rate of some marine organisms, triggering a negative feedback on the growth of atmospheric CO2. We quantify the effect of this CO2-calcification feedback by conducting a series of Earth system model simulations that incorporate different parameterization schemes describing the dependence of calcification rate on saturation state of CaCO3. In a scenario with SRES A2 CO2 emission until 2100 and zero emission afterwards, by year 3500, in the simulation without CO2-calcification feedback, model projects an accumulated ocean CO2 uptake of 1462 PgC, atmospheric CO2 of 612 ppm, and surface pH of 7.9. Inclusion of CO2-calcification feedback increases ocean CO2 uptake by 9 to 285 PgC, reduces atmospheric CO2 by 4 to 70 ppm, and mitigates the reduction in surface pH by 0.003 to 0.06, depending on the form of parameterization scheme used. It is also found that the effect of CO2-calcification feedback on ocean carbon uptake is comparable and could be much larger than the effect from CO2-induced warming. Our results highlight the potentially important role CO2-calcification feedback plays in ocean carbon cycle and projections of future atmospheric CO2 concentrations.

  4. Target atmospheric CO2: Where should humanity aim?

    OpenAIRE

    Hansen, J.; Sato, M.; Kharecha, P.; Beerling, D.; Berner, R; Masson-Delmotte, V.; M. Pagani; Raymo, M.; Royer, D. L.; J. C. Zachos

    2008-01-01

    Paleoclimate data show that climate sensitivity is ~3 deg-C for doubled CO2, including only fast feedback processes. Equilibrium sensitivity, including slower surface albedo feedbacks, is ~6 deg-C for doubled CO2 for the range of climate states between glacial conditions and ice-free Antarctica. Decreasing CO2 was the main cause of a cooling trend that began 50 million years ago, large scale glaciation occurring when CO2 fell to 450 +/- 100 ppm, a level that will be exceeded within decades, b...

  5. Trend, seasonal and diurnal variations of atmospheric CO2 in Beijing

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The concentration of atmospheric CO2 in Beijing increased rapidly at a mean growth rate of 3.7%@a?1 from 1993 to 1995. After displaying a peak of (409.7±25.9) ?mol@mol?1 in 1995, it decreased slowly. Both the almost stable anthropogenic CO2 source and increasing biotic CO2 sink contribute to the drop of CO2 concentration from 1995 to 2000. The seasonal variation of CO2 concentration exhibits a clear cycle with a maximum in winter, averaging (426.8±20.6) ?mol@mol?1, and a minimum in summer, averaging (369.1±6.1) ?mol@mol?1. The seasonal variation of CO2 concentration is mainly controlled by phenology. The mean diurnal variation of atmospheric CO2 concentration for a year in Beijing is highly clear: daily maximum CO2 concentration usually occurs at night, but daily minimum CO2 concentration does in the daytime, with a mean diurnal difference more than 34.7 ?mol@mol?1. It has been revealed that the interannual variations of atmospheric CO2 concentration in winter and autumn regulated the interannual trend of atmospheric CO2, whereas the interannual variation of CO2 concentration in summer affected the general tendency of atmospheric CO2 in a less degree.

  6. 3D modelling of the early Martian Climate under a denser CO2 atmosphere: Temperatures and CO2 ice clouds

    CERN Document Server

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

    2012-01-01

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

  7. Target atmospheric CO2: Where should humanity aim?

    CERN Document Server

    Hansen, J; Kharecha, P; Beerling, D; Masson-Delmotte, V; Pagani, M; Raymo, M; Royer, D L; Zachos, J C

    2008-01-01

    Paleoclimate data show that climate sensitivity is ~3 deg-C for doubled CO2, including only fast feedback processes. Equilibrium sensitivity, including slower surface albedo feedbacks, is ~6 deg-C for doubled CO2 for the range of climate states between glacial conditions and ice-free Antarctica. Decreasing CO2 was the main cause of a cooling trend that began 50 million years ago, large scale glaciation occurring when CO2 fell to 425 +/- 75 ppm, a level that will be exceeded within decades, barring prompt policy changes. If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 385 ppm to at most 350 ppm. The largest uncertainty in the target arises from possible changes of non-CO2 forcings. An initial 350 ppm CO2 target may be achievable by phasing out coal use except where CO2 is captured and adopting agricultural and forestry practice...

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

    Institute of Scientific and Technical Information of China (English)

    马登龙; 邓建强; 张早校

    2014-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

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

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

    Science.gov (United States)

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

    2006-07-01

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

  11. Tropical epiphytes in a CO 2-rich atmosphere

    Science.gov (United States)

    Monteiro, José Alberto Fernandez; Zotz, Gerhard; Körner, Christian

    2009-01-01

    We tested the effect on epiphyte growth of a doubling of pre-industrial CO 2 concentration (280 vs. 560 ppm) combined with two light (three fold) and two nutrition (ten fold) treatments under close to natural humid conditions in daylight growth cabinets over 6 months. Across co-treatments and six species, elevated CO 2 increased relative growth rates by only 6% ( p = 0.03). Although the three C3 species, on average, grew 60% faster than the three CAM species, the two groups did not significantly differ in their CO 2 response. The two Orchidaceae, Bulbophyllum (CAM) and Oncidium (C3) showed no CO 2 response, and three out of four Bromeliaceae showed a positive one: Aechmea (CAM, +32% p = 0.08), Catopsis (C3, +11% p = 0.01) and Vriesea (C3, +4% p = 0.02). In contrast, the representative of the species-rich genus Tillandsia (CAM), which grew very well under experimental conditions, showed no stimulation. On average, high light increased growth by 21% and high nutrients by 10%. Interactions between CO 2, light and nutrient treatments (low vs. high) were inconsistent across species. CO 2 responsive taxa such as Catopsis, could accelerate tropical forest dynamics and increase branch breakage, but overall, the responses to doubling CO 2 of these epiphytes was relatively small and the responses were taxa specific.

  12. CO2 flux estimation errors associated with moist atmospheric processes

    Directory of Open Access Journals (Sweden)

    S. Pawson

    2012-04-01

    Full Text Available Vertical transport by moist sub-grid scale processes such as deep convection is a well-known source of uncertainty in CO2 source/sink inversion. However, a dynamical link between moist transport, satellite CO2 retrievals, and source/sink inversion has not yet been established. Here we examine the effect of moist processes on (1 synoptic CO2 transport by Version-4 and Version-5 NASA Goddard Earth Observing System Data Assimilation System (NASA-DAS meteorological analyses, and (2 source/sink inversion. We find that synoptic transport processes, such as fronts and dry/moist conveyors, feed off background vertical CO2 gradients, which are modulated by sub-grid vertical transport. The implication for source/sink estimation is two-fold. First, CO2 variations contained in moist poleward moving air masses are systematically different from variations in dry equatorward moving air. Moist poleward transport is hidden from orbital sensors on satellites, causing a sampling bias, which leads directly to continental scale source/sink estimation errors of up to 0.25 PgC yr−1 in northern mid-latitudes. Second, moist processes are represented differently in GEOS-4 and GEOS-5, leading to differences in vertical CO2 gradients, moist poleward and dry equatorward CO2 transport, and therefore the fraction of CO2 variations hidden in moist air from satellites. As a result, sampling biases are amplified, causing source/sink estimation errors of up to 0.55 PgC yr−1 in northern mid-latitudes. These results, cast from the perspective of moist frontal transport processes, support previous arguments that the vertical gradient of CO2 is a major source of uncertainty in source/sink inversion.

  13. CO2 Flux Estimation Errors Associated with Moist Atmospheric Processes

    Science.gov (United States)

    Parazoo, N. C.; Denning, A. S.; Kawa, S. R.; Pawson, S.; Lokupitiya, R.

    2012-01-01

    Vertical transport by moist sub-grid scale processes such as deep convection is a well-known source of uncertainty in CO2 source/sink inversion. However, a dynamical link between vertical transport, satellite based retrievals of column mole fractions of CO2, and source/sink inversion has not yet been established. By using the same offline transport model with meteorological fields from slightly different data assimilation systems, we examine sensitivity of frontal CO2 transport and retrieved fluxes to different parameterizations of sub-grid vertical transport. We find that frontal transport feeds off background vertical CO2 gradients, which are modulated by sub-grid vertical transport. The implication for source/sink estimation is two-fold. First, CO2 variations contained in moist poleward moving air masses are systematically different from variations in dry equatorward moving air. Moist poleward transport is hidden from orbital sensors on satellites, causing a sampling bias, which leads directly to small but systematic flux retrieval errors in northern mid-latitudes. Second, differences in the representation of moist sub-grid vertical transport in GEOS-4 and GEOS-5 meteorological fields cause differences in vertical gradients of CO2, which leads to systematic differences in moist poleward and dry equatorward CO2 transport and therefore the fraction of CO2 variations hidden in moist air from satellites. As a result, sampling biases are amplified and regional scale flux errors enhanced, most notably in Europe (0.43+/-0.35 PgC /yr). These results, cast from the perspective of moist frontal transport processes, support previous arguments that the vertical gradient of CO2 is a major source of uncertainty in source/sink inversion.

  14. Impact of oceanic circulation changes on atmospheric δ13CO2

    Science.gov (United States)

    Menviel, L.; Mouchet, A.; Meissner, K. J.; Joos, F.; England, M. H.

    2015-12-01

    δ13CO2 measured in Antarctic ice cores provides constraints on oceanic and terrestrial carbon cycle processes linked with millennial-scale and glacial/interglacial changes in atmospheric CO2. However, the interpretation of δ13CO2 is not straightforward. Using two Earth system models of intermediate complexity we perform a set of sensitivity experiments in which the formation rates of North Atlantic Deep Water (NADW), North Pacific Deep Water (NPDW), Antarctic Bottom Water (AABW) and Antarctic Intermediate Water (AAIW) are varied. We study the impact of these circulation changes on atmospheric δ13CO2 as well as on the oceanic δ13C distribution. In general, we find that the formation rates of AABW, NADW, NPDW and AAIW are negatively correlated with changes in δ13CO2: namely strong oceanic ventilation decreases atmospheric δ13CO2. However, since large scale ocean circulation reorganizations also impact nutrient utilization and the Earth's climate the relationship between atmospheric δ13CO2 levels and ocean ventilation rate is not unequivocal. In both models atmospheric δ13CO2 is very sensitive to changes in AABW formation rates: increased AABW formation enhances the upwelling of low δ13C waters to the surface and decreases atmospheric δ13CO2. By contrast, the impact of NADW changes on atmospheric δ13CO2 is less robust and might be model dependent.

  15. Climate Sensitivity, Sea Level, and Atmospheric CO2

    OpenAIRE

    Hansen, James; Sato, Makiko; Russell, Gary; Kharecha, Pushker

    2012-01-01

    Cenozoic temperature, sea level and CO2 co-variations provide insights into climate sensitivity to external forcings and sea level sensitivity to climate change. Climate sensitivity depends on the initial climate state, but potentially can be accurately inferred from precise paleoclimate data. Pleistocene climate oscillations yield a fast-feedback climate sensitivity 3 +/- 1{\\deg}C for 4 W/m2 CO2 forcing if Holocene warming relative to the Last Glacial Maximum (LGM) is used as calibration, bu...

  16. Attitude toward the biological investigation for decreasing atmospheric CO2. Taiki CO2 wo sakugensuru seibutsuteki kenkyu taido

    Energy Technology Data Exchange (ETDEWEB)

    1993-08-01

    Explanation is made of the bioprocess which aims at treating the atmospheric CO2. As a result of investigation by the Electric Power Research Institute (EPRI), it was judged that the direct CO2 removal from the flue gas of power station is costwise disadvantageous and that the biological method by CO2 fixation is economical. The following are projects supported by the EPRI: The seaweed fossilization of CO2 is a medium depth sea mechanism of having seaweeds absorb carbon and making it remain residually in the deepsea even after the plants die. Study is being made of oceanic seaweed cultivation field development, non-calcareous seaweed cultivation and spore collection. The cost is advantageously low. The cultivation of seaweeds and halophilous plants utilizes their photosynthesis to collect CO2. There are examples of studying the possibility of cultivating those plants through comparison with the land trees. The growth ratio of halophilous plants is being also studied together with the possibility that the carbon remains as a residue. The whiting is a phenomenon in which biodecomposed subsea matter becomes CaCO3. Covered with CaCO3, the ssaweeds are deposited. Investigation is being made on the seaweed morphology and condition for the occurrence of whiting. 1 ref., 2 figs., 1 tab.

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

    Science.gov (United States)

    Ohm, H.; Marschner, B.

    2009-04-01

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

  18. Free-air CO2 enrichment (FACE) enhances biomass production in a short-rotation poplar plantation

    NARCIS (Netherlands)

    Calfapietra, C.; Gielen, B.; Galema, A.N.J.; Lukac, M.; Angelis, de P.; Moscatelli, M.C.; Ceulemans, R.; Scarascia-Mugnozza, G.

    2003-01-01

    This paper investigates the possible contribution of Short Rotation Cultures (SRC) to carbon sequestration in both current and elevated atmospheric CO2 concentrations ([CO2]). A dense poplar plantation (1 x 1 m) was exposed to a [CO2] of 550 ppm in Central Italy using the free-air CO2 enrichment (FA

  19. Projected land photosynthesis constrained by changes in the seasonal cycle of atmospheric CO2

    Science.gov (United States)

    Wenzel, Sabrina; Cox, Peter M.; Eyring, Veronika; Friedlingstein, Pierre

    2016-10-01

    Uncertainties in the response of vegetation to rising atmospheric CO2 concentrations contribute to the large spread in projections of future climate change. Climate-carbon cycle models generally agree that elevated atmospheric CO2 concentrations will enhance terrestrial gross primary productivity (GPP). However, the magnitude of this CO2 fertilization effect varies from a 20 per cent to a 60 per cent increase in GPP for a doubling of atmospheric CO2 concentrations in model studies. Here we demonstrate emergent constraints on large-scale CO2 fertilization using observed changes in the amplitude of the atmospheric CO2 seasonal cycle that are thought to be the result of increasing terrestrial GPP. Our comparison of atmospheric CO2 measurements from Point Barrow in Alaska and Cape Kumukahi in Hawaii with historical simulations of the latest climate-carbon cycle models demonstrates that the increase in the amplitude of the CO2 seasonal cycle at both measurement sites is consistent with increasing annual mean GPP, driven in part by climate warming, but with differences in CO2 fertilization controlling the spread among the model trends. As a result, the relationship between the amplitude of the CO2 seasonal cycle and the magnitude of CO2 fertilization of GPP is almost linear across the entire ensemble of models. When combined with the observed trends in the seasonal CO2 amplitude, these relationships lead to consistent emergent constraints on the CO2 fertilization of GPP. Overall, we estimate a GPP increase of 37 ± 9 per cent for high-latitude ecosystems and 32 ± 9 per cent for extratropical ecosystems under a doubling of atmospheric CO2 concentrations on the basis of the Point Barrow and Cape Kumukahi records, respectively.

  20. Dynamics of Soil Organic Carbon Under Uncertain Climate Change and Elevated Atmospheric CO2

    Institute of Scientific and Technical Information of China (English)

    LIN Zhong-Bing; ZHANG Ren-Duo

    2012-01-01

    Climate change and elevated atmospheric CO2 should affect the dynamics of soil organic carbon (SOC).SOC dynamics under uncertain patterns of climate warming and elevated atmospheric CO2 as well as with different soil erosion extents at Nelson Farm during 1998-2100 were simulated using stochastic modelling.Results based on numerous simulations showed that SOC decreased with elevated atmospheric temperature but increased with atmospheric CO2 concentration.Therefore,there was a counteract effect on SOC dynamics between climate warming and elevated CO2.For different soil erosion extents,warming 1 ℃ and elevated atmospheric CO2 resulted in SOC increase at least 15%,while warming 5 ℃ and elevated CO2 resulted in SOC decrease more than 29%.SOCpredictions with uncertainty assessment were conducted for different scenarios of soil erosion,climate change,and elevated CO2.Statistically,SOC decreased linearly with the probability.SOC also decreased with time and the degree of soil erosion.For example,in 2100 with a probability of 50%,SOC was 1617,1 167,and 892 g m-2,respectively,for no,minimum,and maximum soil erosion.Under climate warming 5 ℃ and elevated CO2,the soil carbon pools became a carbon source to the atmosphere (P > 95%).The results suggested that stochastic modelling could be a useful tool to predict future SOC dynamics under uncertain climate change and elevated CO2.

  1. [CO2 Budget and Atmospheric Rectification (COBRA) Over North America

    Science.gov (United States)

    2004-01-01

    The purpose of the CO2 Budget and Rectification Airborne (COBRA) study was to assess terrestrial sources and sinks of carbon dioxide using an air-borne study. The study was designed to address the measurement gap between plot-scale direct flux measurements and background hemispheric-scale constraints and to refine techniques for measuring terrestrial fluxes at regional to continental scales. The initial funded effort (reported on here) was to involve two air-borne campaigns over North America, one in summer and one in winter. Measurements for COBRA (given the acronym C02BAR in the initial proposal) were conducted from the University of North Dakota Citation 11, a twin-engine jet aircraft capable of profiling from the surface to 12 km and cruising for up to 4 hours and 175m/s. Onboard instrumentation measured concentrations of CO2, CO, and H2O, and meteorological parameters at high rates. In addition, two separate flask sampling systems collected discrete samples for laboratory analysis of CO2,CO, CH4, N2O, SF6, H2, 13CO2, C18O16O,O2/N2, and Ar/N2. The project involved a collaboration between a number of institutions, including (but not limited to) Harvard, NOAA-CMDL, the University of North Dakota, and Scripps.

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

    Institute of Scientific and Technical Information of China (English)

    刘植; 刘秀铭; 李平原; 吕镔; 陈家胜; 陈渠; 郭雪莲

    2012-01-01

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

  3. Lidar Measurements of Atmospheric CO2 From Regional to Global Scales

    Science.gov (United States)

    Lin, Bing; Harrison, F. Wallace; Nehrir, Amin; Browell, Edward; Dobler, Jeremy; Campbell, Joel; Meadows, Byron; Obland, Michael; Ismail, Syed; Kooi, Susan; Fan, Tai-Fang

    2015-01-01

    Atmospheric CO2 is a critical forcing for the Earth's climate and the knowledge on its distributions and variations influences predictions of the Earth's future climate. Large uncertainties in the predictions persist due to limited observations. This study uses the airborne Intensity-Modulated Continuous-Wave (IMCW) lidar developed at NASA Langley Research Center to measure regional atmospheric CO2 spatio-temporal variations. Further lidar development and demonstration will provide the capability of global atmospheric CO2 estimations from space, which will significantly advances our knowledge on atmospheric CO2 and reduce the uncertainties in the predictions of future climate. In this presentation, atmospheric CO2 column measurements from airborne flight campaigns and lidar system simulations for space missions will be discussed. A measurement precision of approx.0.3 ppmv for a 10-s average over desert and vegetated surfaces has been achieved. Data analysis also shows that airborne lidar CO2 column measurements over these surfaces agree well with in-situ measurements. Even when thin cirrus clouds present, consistent CO2 column measurements between clear and thin cirrus cloudy skies are obtained. Airborne flight campaigns have demonstrated that precise atmospheric column CO2 values can be measured from current IM-CW lidar systems, which will lead to use this airborne technique in monitoring CO2 sinks and sources in regional and continental scales as proposed by the NASA Atmospheric Carbon and Transport â€" America project. Furthermore, analyses of space CO2 measurements shows that applying the current IM-CW lidar technology and approach to space, the CO2 science goals of space missions will be achieved, and uncertainties in CO2 distributions and variations will be reduced.

  4. Responses of rice growth to copper stress under free-air CO2 enrichment (FACE)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The responses of rice to the second degree contamination of copper were studied by pot experiments under free-air CO2 enrichment (FACE) with 570 μmol·mol-1 of CO2. The results showed that the content of copper in rice leaves was reduced with the CO2 concentration reaching 570 μmol·mol-1 and this happened more significantly under the second degree contamination of copper. Under FACE, activities of superoxide dismutase (SOD) enzyme in rice leaves treated by copper contamination were induced, whereas the contents of glutathione (GSH) and glutathione disulfide (GSSG) had no significant difference from the control. In the presence of ambient CO2, activities of SOD enzyme treated by copper pollution were suppressed during the whole rice growth, however, the contents of GSH and GSSG were induced at tillering and jointing stages, and then restored to the control levels in later growth under the second degree contamination of copper. With the rice growing, the content of malondialdehyde (MDA) rises continuously, but there had been no significant difference between the treatments at the same growth stage. Further studies are needed on the response mechanism of rice to Cu stress under elevated CO2.

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

    Science.gov (United States)

    Wang, W.; Nemani, R.

    2014-09-01

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

  6. Quantifying the drivers of ocean-atmosphere CO2 fluxes

    Science.gov (United States)

    Lauderdale, Jonathan M.; Dutkiewicz, Stephanie; Williams, Richard G.; Follows, Michael J.

    2016-07-01

    A mechanistic framework for quantitatively mapping the regional drivers of air-sea CO2 fluxes at a global scale is developed. The framework evaluates the interplay between (1) surface heat and freshwater fluxes that influence the potential saturated carbon concentration, which depends on changes in sea surface temperature, salinity and alkalinity, (2) a residual, disequilibrium flux influenced by upwelling and entrainment of remineralized carbon- and nutrient-rich waters from the ocean interior, as well as rapid subduction of surface waters, (3) carbon uptake and export by biological activity as both soft tissue and carbonate, and (4) the effect on surface carbon concentrations due to freshwater precipitation or evaporation. In a steady state simulation of a coarse-resolution ocean circulation and biogeochemistry model, the sum of the individually determined components is close to the known total flux of the simulation. The leading order balance, identified in different dynamical regimes, is between the CO2 fluxes driven by surface heat fluxes and a combination of biologically driven carbon uptake and disequilibrium-driven carbon outgassing. The framework is still able to reconstruct simulated fluxes when evaluated using monthly averaged data and takes a form that can be applied consistently in models of different complexity and observations of the ocean. In this way, the framework may reveal differences in the balance of drivers acting across an ensemble of climate model simulations or be applied to an analysis and interpretation of the observed, real-world air-sea flux of CO2.

  7. Atmospheric CO2 capture by algae: Negative carbon dioxide emission path.

    Science.gov (United States)

    Moreira, Diana; Pires, José C M

    2016-09-01

    Carbon dioxide is one of the most important greenhouse gas, which concentration increase in the atmosphere is associated to climate change and global warming. Besides CO2 capture in large emission point sources, the capture of this pollutant from atmosphere may be required due to significant contribution of diffuse sources. The technologies that remove CO2 from atmosphere (creating a negative balance of CO2) are called negative emission technologies. Bioenergy with Carbon Capture and Storage may play an important role for CO2 mitigation. It represents the combination of bioenergy production and carbon capture and storage, keeping carbon dioxide in geological reservoirs. Algae have a high potential as the source of biomass, as they present high photosynthetic efficiencies and high biomass yields. Their biomass has a wide range of applications, which can improve the economic viability of the process. Thus, this paper aims to assess the atmospheric CO2 capture by algal cultures.

  8. Responses of plant rhizosphere to atmospheric CO2 enrichment

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Plant root growth is generally stimulated under elevated CO2. This will bring more carbon to the below-ground through root death and exudate. This potential increase in below-ground carbon sink may lead to changes in long-term soil sequestration and relationship between host plants and symbions. On the other hand, changes in litter components due to the changes in plant chemical composition may also affect soil processes, such as litter decomposition, soil organic matter sequestration and hetero-nutritional bacteria activities. These issues are discussed.

  9. [Influence of elevated atmospheric CO2 on rhizosphere microbes and arbuscular mycorrhizae].

    Science.gov (United States)

    Chen, Jing; Chen, Xin; Tang, Jianjun

    2004-12-01

    The changes of microbial communities in rhizosphere and the formation of mycorrhizae play an important role in affecting the dynamics of plant communities and terrestrial ecosystems. This paper summarized and discussed the effects of elevated atmospheric CO2 on them. Under elevated atmospheric CO2, the carbohydrates accumulated in root systems increased, and the rhizospheric environment and its microbial communities as well as the formation of mycorrhizae changed. It is suggested that the researches in the future should be focused on the effects of rhizosphere microbes and arbuscular mycorrhizae on regulating the carbon dynamics of plant communities and terrestrial ecosystems under elevated atmospheric CO2.

  10. Weathering by tree-root-associating fungi diminishes under simulated Cenozoic atmospheric CO2 decline

    OpenAIRE

    2014-01-01

    Trees dominate terrestrial biotic weathering of silicate minerals by converting solar energy into chemical energy that fuels roots and their ubiquitous nutrient-mobilising fungal symbionts. These biological activities regulate atmospheric CO2 concentrations ([CO2]a) over geologic timescales by driving calcium and magnesium fluvial ion export and marine carbonate formation. However, the important stabilising feedbacks between [CO2]a and biotic weathering anticipated by geo...

  11. Regional and Global Atmospheric CO2 Measurements Using 1.57 Micron IM-CW Lidar

    Science.gov (United States)

    Lin, Bing; Obland, Michael; Nehrir, Amin; Browell, Edward; Harrison, F. Wallace; Dobler, Jeremy; Campbell, Joel; Kooi, Susan; Meadows, Byron; Fan, Tai-Fang; Liu, Zhaoyan

    2015-01-01

    Atmospheric CO2 is a critical forcing for the Earth's climate, and knowledge of its distribution and variations influences predictions of the Earth's future climate. Accurate observations of atmospheric CO2 are also crucial to improving our understanding of CO2 sources, sinks and transports. To meet these science needs, NASA is developing technologies for the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) space mission, which is aimed at global CO2 observations. Meanwhile an airborne investigation of atmospheric CO2 distributions as part of the NASA Suborbital Atmospheric Carbon and Transport â€" America (ACT-America) mission will be conducted with lidar and in situ instrumentation over the central and eastern United States during all four seasons and under a wide range of meteorological conditions. In preparing for the ASCENDS mission, NASA Langley Research Center and Exelis Inc./Harris Corp. have jointly developed and demonstrated the capability of atmospheric CO2 column measurements with an intensity-modulated continuous-wave (IM-CW) lidar. Since 2005, a total of 14 flight campaigns have been conducted. A measurement precision of approx.0.3 ppmv for a 10-s average over desert and vegetated surfaces has been achieved, and the lidar CO2 measurements also agree well with in-situ observations. Significant atmospheric CO2 variations on various spatiotemporal scales have been observed during these campaigns. For example, around 10-ppm CO2 changes were found within free troposphere in a region of about 200A-300 sq km over Iowa during a summer 2014 flight. Results from recent flight campaigns are presented in this paper. The ability to achieve the science objectives of the ASCENDS mission with an IM-CW lidar is also discussed in this paper, along with the plans for the ACT-America aircraft investigation that begins in the winter of 2016.

  12. CO2 greenhouse in the early martian atmosphere: SO2 inhibits condensation.

    Science.gov (United States)

    Yung, Y L; Nair, H; Gerstell, M F

    1997-01-01

    Many investigators of the early martian climate have suggested that a dense carbon dioxide atmosphere was present and warmed the surface above the melting point of water (J.B. Pollack, J.F. Kasting, S.M. Richardson, and K. Poliakoff 1987. Icarus 71, 203-224). However, J.F. Kasting (1991. Icarus 94, 1-13) pointed out that previous thermal models of the primitive martian atmosphere had not considered the condensation of CO2. When this effect was incorporated, Kasting found that CO2 by itself is inadequate to warm the surface. SO2 absorbs strongly in the near UV region of the solar spectrum. While a small amount of SO2 may have a negligible effect by itself on the surface temperature, it may have significantly warmed the middle atmosphere of early Mars, much as ozone warms the terrestrial stratosphere today. If this region is kept warm enough to inhibit the condensation of CO2, then CO2 remains a viable greenhouse gas. Our preliminary radiative modeling shows that the addition of 0.1 ppmv of SO2 in a 2 bar CO2 atmosphere raises the temperature of the middle atmosphere by approximately 10 degrees, so that the upper atmosphere in a 1 D model remains above the condensation temperature of CO2. In addition, this amount of SO2 in the atmosphere provides an effective UV shield for a hypothetical biosphere on the martian surface.

  13. Bioenergy from forestry and changes in atmospheric CO2: reconciling single stand and landscape level approaches.

    Science.gov (United States)

    Cherubini, Francesco; Guest, Geoffrey; Strømman, Anders H

    2013-11-15

    Analyses of global warming impacts from forest bioenergy systems are usually conducted either at a single stand level or at a landscape level, yielding findings that are sometimes interpreted as contrasting. In this paper, we investigate and reconcile the scales at which environmental impact analyses of forest bioenergy systems are undertaken. Focusing on the changes caused in atmospheric CO2 concentration of forest bioenergy systems characterized by different initial states of the forest, we show the features of the analyses at different scales and depict the connections between them. Impacts on atmospheric CO2 concentration at a single stand level are computed through impulse response functions (IRF). Results at a landscape level are elaborated through direct application of IRFs to the emission profile, so to account for the fluxes from all the stands across time and space. Impacts from fossil CO2 emissions are used as a benchmark. At a landscape level, forest bioenergy causes an increase in atmospheric CO2 concentration for the first decades that is similar to the impact from fossil CO2, but then the dynamics clearly diverge because while the impact from fossil CO2 continues to rise that from bioenergy stabilizes at a certain level. These results perfectly align with those obtained at a single stand for which characterization factors have been developed. In the hypothetical case of a sudden cessation of emissions, the change caused in atmospheric CO2 concentration from biogenic CO2 emissions reverses within a couple of decades, while that caused by fossil CO2 emissions remains considerably higher for centuries. When counterfactual aspects like the additional sequestration that would have occurred in the forest if not harvested and the theoretical displacement of fossil CO2 are included in the analysis, results can widely differ, as the CO2 debt at a landscape level ranges from a few years to several centuries (depending on the underlying assumptions considered).

  14. Changes in coccolith calcification under stable atmospheric CO2

    Directory of Open Access Journals (Sweden)

    C. Bauke

    2013-06-01

    Full Text Available Coccolith calcification is known to respond to ocean acidification in culture experiments as well as in present and past oceans. Previous studies basically focus on changes in coccolith weight due to increasing CO2 and the resulting changes in the carbonate system but pay little attention to the influence of other environmental factors. In order to untangle changes in coccolithophore calcification due to environmental factors such as temperature and/or productivity from changes caused by increasing pCO2 and carbonate ion concentration we here present a study on coccolith calcification from the Holocene North Atlantic Ocean. The pre-industrial Holocene with its predominantly stable carbonate system provides the conditions for such a comprehensive analysis. For a realistic analysis on changes in major components of Holocene coccolithophores, the family Noelaerhabdaceae was selected, which constitutes the main part of the assemblage in the North Atlantic. Records of average coccolith weights from three Holocene sediment cores along a North–South transect in the North Atlantic were analysed. During the Holocene mean weight (and therefore calcification of Noelaerhabdaceae (E. huxleyi and Gephyrocapsa coccoliths decreases at the Azores (Geofar KF 16 from around 7 to 5.5 pg, but increases at the Rockall Plateau (ODP Site 980 from around 6 to 8 pg and at the Vøring Plateau (MD08-3192 from 7 to 10.5 pg. This amplitude of average weight variability is within the range of glacial/interglacial changes that were interpreted to be an effect of decreasing carbonate ion concentration. By comparison with SEM assemblage counts, we show that weight changes are partly due to variations in the coccolithophore assemblage, but also an effect of a change in calcification and/or morphotype variability within single species. Our results indicate that there is no single key factor responsible for the observed changes in coccolith weight. A major increase in coccolith

  15. Changes in coccolith calcification under stable atmospheric CO2

    Science.gov (United States)

    Bauke, C.; Meier, K. J. S.; Kinkel, H.; Baumann, K.-H.

    2013-06-01

    Coccolith calcification is known to respond to ocean acidification in culture experiments as well as in present and past oceans. Previous studies basically focus on changes in coccolith weight due to increasing CO2 and the resulting changes in the carbonate system but pay little attention to the influence of other environmental factors. In order to untangle changes in coccolithophore calcification due to environmental factors such as temperature and/or productivity from changes caused by increasing pCO2 and carbonate ion concentration we here present a study on coccolith calcification from the Holocene North Atlantic Ocean. The pre-industrial Holocene with its predominantly stable carbonate system provides the conditions for such a comprehensive analysis. For a realistic analysis on changes in major components of Holocene coccolithophores, the family Noelaerhabdaceae was selected, which constitutes the main part of the assemblage in the North Atlantic. Records of average coccolith weights from three Holocene sediment cores along a North-South transect in the North Atlantic were analysed. During the Holocene mean weight (and therefore calcification) of Noelaerhabdaceae (E. huxleyi and Gephyrocapsa) coccoliths decreases at the Azores (Geofar KF 16) from around 7 to 5.5 pg, but increases at the Rockall Plateau (ODP Site 980) from around 6 to 8 pg and at the Vøring Plateau (MD08-3192) from 7 to 10.5 pg. This amplitude of average weight variability is within the range of glacial/interglacial changes that were interpreted to be an effect of decreasing carbonate ion concentration. By comparison with SEM assemblage counts, we show that weight changes are partly due to variations in the coccolithophore assemblage, but also an effect of a change in calcification and/or morphotype variability within single species. Our results indicate that there is no single key factor responsible for the observed changes in coccolith weight. A major increase in coccolith weight occurs

  16. The Effect of CO2 Ice Cap Sublimation on Mars Atmosphere

    Science.gov (United States)

    Batterson, Courtney

    2016-01-01

    Sublimation of the polar CO2 ice caps on Mars is an ongoing phenomenon that may be contributing to secular climate change on Mars. The transfer of CO2 between the surface and atmosphere via sublimation and deposition may alter atmospheric mass such that net atmospheric mass is increasing despite seasonal variations in CO2 transfer. My study builds on previous studies by Kahre and Haberle that analyze and compare data from the Phoenix and Viking Landers 1 and 2 to determine whether secular climate change is happening on Mars. In this project, I use two years worth of temperature, pressure, and elevation data from the MSL Curiosity rover to create a program that allows for successful comparison of Curiosity pressure data to Viking Lander pressure data so a conclusion can be drawn regarding whether CO2 ice cap sublimation is causing a net increase in atmospheric mass and is thus contributing to secular climate change on Mars.

  17. Phenol-Formaldehyde Resin-Based Carbons for CO2 Separation at Sub-Atmospheric Pressures

    Directory of Open Access Journals (Sweden)

    Noelia Álvarez-Gutiérrez

    2016-03-01

    Full Text Available The challenge of developing effective separation and purification technologies that leave much smaller energy footprints is greater for carbon dioxide (CO2 than for other gases. In addition to its involvement in climate change, CO2 is present as an impurity in biogas and bio-hydrogen (biological production by dark fermentation, in post-combustion processes (flue gas, CO2-N2 and many other gas streams. Selected phenol-formaldehyde resin-based activated carbons prepared in our laboratory have been evaluated under static conditions (adsorption isotherms as potential adsorbents for CO2 separation at sub-atmospheric pressures, i.e., in post-combustion processes or from biogas and bio-hydrogen streams. CO2, H2, N2, and CH4 adsorption isotherms at 25 °C and up to 100 kPa were obtained using a volumetric equipment and were correlated by applying the Sips model. Adsorption equilibrium was then predicted for multicomponent gas mixtures by extending the multicomponent Sips model and the Ideal Adsorbed Solution Theory (IAST in conjunction with the Sips model. The CO2 uptakes of the resin-derived carbons from CO2-CH4, CO2-H2, and CO2-N2 at atmospheric pressure were greater than those of the reference commercial carbon (Calgon BPL. The performance of the resin-derived carbons in terms of equilibrium of adsorption seems therefore relevant to CO2 separation in post-combustion (flue gas, CO2-N2 and in hydrogen fermentation (CO2-H2, CO2-CH4.

  18. Effect of elevated atmospheric CO2 and vegetation type on microbiota associated with decomposing straw

    DEFF Research Database (Denmark)

    Frederiksen, Helle B.; Ronn, R.; Christensen, S.

    2001-01-01

    concentration in the recovered straw samples. After five months of decomposition, hyphal biomass was significantly lower in straw from plants grown at elevated CO2 (-30% and -13% in the fallow and wheat field, respectively). Bacterial biomass was not significantly affected by the CO2 induced changes...... in the litter quality, but the lower decomposition rate and fewer bacterial grazers in the straw from plants grown at elevated CO2 together indicate reduced microbial activity and turnover. Notwithstanding this, these data show that growth at elevated atmospheric CO2 concentration results in slower...

  19. Near-pure vapor condensation in the Martian atmosphere: CO2 ice crystal growth

    OpenAIRE

    Listowski, Constantino; Määttänen, Anni; Riipinen, Ilona; Montmessin, Franck; Lefèvre, Franck

    2013-01-01

    International audience; A new approach is presented to model the condensational growth of carbon dioxide (CO2) ice crystals on Mars. These condensates form in very particular conditions. First, ~95% of the atmosphere is composed of CO2 so that near-pure vapor condensation takes place. Second, the atmosphere is rarefied, having dramatic consequences on the crystal growth. Indeed, the subsequently reduced efficiency of heat transport helps maintain a high temperature difference between the crys...

  20. Acetylene fuel from atmospheric CO2 on Mars

    Science.gov (United States)

    Landis, Geoffrey A.; Linne, Diane L.

    1992-01-01

    The Mars mission scenario proposed by Baker and Zubrin (1990) intended for an unmanned preliminary mission is extended to maximize the total impulse of fuel produced with a minimum mass of hydrogen from Earth. The hydrogen along with atmospheric carbon dioxide is processed into methane and oxygen by the exothermic reaction in an atmospheric processing module. Use of simple chemical reactions to produce acetylene/oxygen rocket fuel on Mars from hydrogen makes it possible to produce an amount of fuel that is nearly 100 times the mass of hydrogen brought from earth. If such a process produces the return propellant for a manned Mars mission, the required mission mass in LEO is significantly reduced over a system using all earth-derived propellants.

  1. Intermediate time scale response of atmospheric CO2 following prescribed fire in a longleaf pine forest

    Science.gov (United States)

    Viner, B.; Parker, M.; Maze, G.; Varnedoe, P.; Leclerc, M.; Starr, G.; Aubrey, D.; Zhang, G.; Duarte, H.

    2016-10-01

    Fire plays an essential role in maintaining the structure and function of longleaf pine ecosystems. While the effects of fire on carbon cycle have been measured in previous studies for short periods during a burn and for multiyear periods following the burn, information on how carbon cycle is influenced by such changes over the span of a few weeks to months has yet to be quantified. We have analyzed high-frequency measurements of CO2 concentration and flux, as well as associated micrometeorological variables, at three levels of the tall Aiken AmeriFlux tower during and after a prescribed burn. Measurements of the CO2 concentration and vertical fluxes were examined as well as calculated net ecosystem exchange (NEE) for periods prior to and after the burn. Large spikes in both CO2 concentration and CO2 flux during the fire and increases in atmospheric CO2 concentration and reduced CO2 flux were observed for several weeks following the burn, particularly below the forest canopy. Both CO2 measurements and NEE were found to return to their preburn states within 60-90 days following the burn when no statistical significance was found between preburn and postburn NEE. This study examines the micrometeorological conditions during a low-intensity prescribed burn and its short-term effects on local CO2 dynamics in a forested environment by identifying observable impacts on local measurements of atmospheric CO2 concentration and fluxes.

  2. A test of sensitivity to convective transport in a global atmospheric CO2 simulation

    Science.gov (United States)

    Bian, H.; Kawa, S. R.; Chin, M.; Pawson, S.; Zhu, Z.; Rasch, P.; Wu, S.

    2006-11-01

    Two approximations to convective transport have been implemented in an offline chemistry transport model (CTM) to explore the impact on calculated atmospheric CO2 distributions. Global CO2 in the year 2000 is simulated using the CTM driven by assimilated meteorological fields from the NASA's Goddard Earth Observation System Data Assimilation System, Version 4 (GEOS-4). The model simulates atmospheric CO2 by adopting the same CO2 emission inventory and dynamical modules as described in Kawa et al. (convective transport scheme denoted as Conv1). Conv1 approximates the convective transport by using the bulk convective mass fluxes to redistribute trace gases. The alternate approximation, Conv2, partitions fluxes into updraft and downdraft, as well as into entrainment and detrainment, and has potential to yield a more realistic simulation of vertical redistribution through deep convection. Replacing Conv1 by Conv2 results in an overestimate of CO2 over biospheric sink regions. The largest discrepancies result in a CO2 difference of about 7.8 ppm in the July NH boreal forest, which is about 30% of the CO2 seasonality for that area. These differences are compared to those produced by emission scenario variations constrained by the framework of Intergovernmental Panel on Climate Change (IPCC) to account for possible land use change and residual terrestrial CO2 sink. It is shown that the overestimated CO2 driven by Conv2 can be offset by introducing these supplemental emissions.

  3. Recent pause in the growth rate of atmospheric CO2 due to enhanced terrestrial carbon uptake

    Science.gov (United States)

    Keenan, Trevor F.; Prentice, I. Colin; Canadell, Josep G.; Williams, Christopher A.; Wang, Han; Raupach, Michael; Collatz, G. James

    2016-11-01

    Terrestrial ecosystems play a significant role in the global carbon cycle and offset a large fraction of anthropogenic CO2 emissions. The terrestrial carbon sink is increasing, yet the mechanisms responsible for its enhancement, and implications for the growth rate of atmospheric CO2, remain unclear. Here using global carbon budget estimates, ground, atmospheric and satellite observations, and multiple global vegetation models, we report a recent pause in the growth rate of atmospheric CO2, and a decline in the fraction of anthropogenic emissions that remain in the atmosphere, despite increasing anthropogenic emissions. We attribute the observed decline to increases in the terrestrial sink during the past decade, associated with the effects of rising atmospheric CO2 on vegetation and the slowdown in the rate of warming on global respiration. The pause in the atmospheric CO2 growth rate provides further evidence of the roles of CO2 fertilization and warming-induced respiration, and highlights the need to protect both existing carbon stocks and regions, where the sink is growing rapidly.

  4. The declining uptake rate of atmospheric CO2 by land and ocean sinks

    Directory of Open Access Journals (Sweden)

    M. R. Raupach

    2014-07-01

    Full Text Available Through 1959–2012, an airborne fraction (AF of 0.44 of total anthropogenic CO2 emissions remained in the atmosphere, with the rest being taken up by land and ocean CO2 sinks. Understanding of this uptake is critical because it greatly alleviates the emissions reductions required for climate mitigation, and also reduces the risks and damages that adaptation has to embrace. An observable quantity that reflects sink properties more directly than the AF is the CO2 sink rate (kS, the combined land–ocean CO2 sink flux per unit excess atmospheric CO2 above preindustrial levels. Here we show from observations that kS declined over 1959–2012 by a factor of about 1 / 3, implying that CO2 sinks increased more slowly than excess CO2. Using a carbon–climate model, we attribute the decline in kS to four mechanisms: slower-than-exponential CO2 emissions growth (~ 35% of the trend, volcanic eruptions (~ 25%, sink responses to climate change (~ 20%, and nonlinear responses to increasing CO2, mainly oceanic (~ 20%. The first of these mechanisms is associated purely with the trajectory of extrinsic forcing, and the last two with intrinsic, feedback responses of sink processes to changes in climate and atmospheric CO2. Our results suggest that the effects of these intrinsic, nonlinear responses are already detectable in the global carbon cycle. Although continuing future decreases in kS will occur under all plausible CO2 emission scenarios, the rate of decline varies between scenarios in non-intuitive ways because extrinsic and intrinsic mechanisms respond in opposite ways to changes in emissions: extrinsic mechanisms cause kS to decline more strongly with increasing mitigation, while intrinsic mechanisms cause kS to decline more strongly under high-emission, low-mitigation scenarios as the carbon–climate system is perturbed further from a near-linear regime.

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

    Science.gov (United States)

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

    2015-03-01

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

  6. Phanerozoic atmospheric CO 2 change: evaluating geochemical and paleobiological approaches

    Science.gov (United States)

    Royer, Dana L.; Berner, Robert A.; Beerling, David J.

    2001-08-01

    . In addition, it assumes that there are no biological or temperature effects and that diagenetic alteration of the boron isotopic composition does not occur. A fifth CO 2 proxy, based on the redox chemistry of marine cerium, has several fundamental flaws and is not discussed in detail here.

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

    Science.gov (United States)

    Osada, Noriyuki; Onoda, Yusuke; Hikosaka, Kouki

    2010-09-01

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

  8. The impact of Southern Ocean residual upwelling on atmospheric CO2 on centennial and millennial timescales

    Science.gov (United States)

    Lauderdale, Jonathan M.; Williams, Richard G.; Munday, David R.; Marshall, David P.

    2017-03-01

    The Southern Ocean plays a pivotal role in climate change by exchanging heat and carbon, and provides the primary window for the global deep ocean to communicate with the atmosphere. There has been a widespread focus on explaining atmospheric CO2 changes in terms of changes in wind forcing in the Southern Ocean. Here, we develop a dynamically-motivated metric, the residual upwelling, that measures the primary effect of Southern Ocean dynamics on atmospheric CO2 on centennial to millennial timescales by determining the communication with the deep ocean. The metric encapsulates the combined, net effect of winds and air-sea buoyancy forcing on both the upper and lower overturning cells, which have been invoked as explaining atmospheric CO2 changes for the present day and glacial-interglacial changes. The skill of the metric is assessed by employing suites of idealized ocean model experiments, including parameterized and explicitly simulated eddies, with online biogeochemistry and integrated for 10,000 years to equilibrium. Increased residual upwelling drives elevated atmospheric CO2 at a rate of typically 1-1.5 parts per million/106 m3 s-1 by enhancing the communication between the atmosphere and deep ocean. This metric can be used to interpret the long-term effect of Southern Ocean dynamics on the natural carbon cycle and atmospheric CO2, alongside other metrics, such as involving the proportion of preformed nutrients and the extent of sea ice cover.

  9. Effects of 7.5% carbon dioxide (CO2) inhalation and ethnicity on face memory.

    Science.gov (United States)

    Attwood, Angela S; Catling, Jon C; Kwong, Alex S F; Munafò, Marcus R

    2015-08-01

    The ability to accurately verify facial identity has important forensic implications, but this ability is fallible. Research suggests that anxiety at the time of encoding can impair subsequent recall, but no studies have investigated the effects of anxiety at the time of recall in an experimental paradigm. This study addresses this gap using the carbon dioxide (CO2) model of anxiety induction. Thirty participants completed two inhalations: one of 7.5% CO2-enriched air and one of medical air (i.e., placebo). Prior to each inhalation, participants were presented with 16 facial images (50% own-ethnicity, 50% other-ethnicity). During the inhalation they were required to identify which faces had been seen before from a set of 32 images (16 seen-before and 16 novel images). Identification accuracy was lower during CO2 inhalation compared to air (F[1,29]=5.5, p=.026, ηp(2)=.16), and false alarm rate was higher for other-ethnicity faces compared to own-ethnicity faces (F[1,29]=11.3, p=.002, ηp(2)=.28). There was no evidence of gas by ethnicity interactions for accuracy or false alarms (ps>.34). Ratings of decision confidence did not differ by gas condition, suggesting that participants were unaware of differences in performance. These findings suggest that anxiety, at the point of recognition, impairs facial identification accuracy. This has substantial implications for eyewitness memory situations, and suggests that efforts should be made to attenuate the anxiety in these situations in order to improve the validity of identification.

  10. Can the envisaged reductions of fossil fuel CO2 emissions be detected by atmospheric observations?

    Science.gov (United States)

    Levin, Ingeborg; Rödenbeck, Christian

    2008-03-01

    The lower troposphere is an excellent receptacle, which integrates anthropogenic greenhouse gases emissions over large areas. Therefore, atmospheric concentration observations over populated regions would provide the ultimate proof if sustained emissions changes have occurred. The most important anthropogenic greenhouse gas, carbon dioxide (CO(2)), also shows large natural concentration variations, which need to be disentangled from anthropogenic signals to assess changes in associated emissions. This is in principle possible for the fossil fuel CO(2) component (FFCO(2)) by high-precision radiocarbon ((14)C) analyses because FFCO(2) is free of radiocarbon. Long-term observations of (14)CO(2) conducted at two sites in south-western Germany do not yet reveal any significant trends in the regional fossil fuel CO(2) component. We rather observe strong inter-annual variations, which are largely imprinted by changes of atmospheric transport as supported by dedicated transport model simulations of fossil fuel CO(2). In this paper, we show that, depending on the remoteness of the site, changes of about 7-26% in fossil fuel emissions in respective catchment areas could be detected with confidence by high-precision atmospheric (14)CO(2) measurements when comparing 5-year averages if these inter-annual variations were taken into account. This perspective constitutes the urgently needed tool for validation of fossil fuel CO(2) emissions changes in the framework of the Kyoto protocol and successive climate initiatives.

  11. Development and Evaluation of a High Sensitivity DIAL System for Profiling Atmospheric CO2

    Science.gov (United States)

    Ismail, Syed; Koch, Grady J.; Refaat, Tamer F.; Abedin, M. N.; Yu, Jirong; Singh, Upendra N.

    2008-01-01

    A ground-based 2-micron Differential Absorption Lidar (DIAL) CO2 profiling system for atmospheric boundary layer studies and validation of space-based CO2 sensors is being developed and tested at NASA Langley Research Center as part of the NASA Instrument Incubator Program. To capture the variability of CO2 in the lower troposphere a precision of 1-2 ppm of CO2 (less than 0.5%) with 0.5 to 1 km vertical resolution from near surface to free troposphere (4-5 km) is one of the goals of this program. In addition, a 1% (3 ppm) absolute accuracy with a 1 km resolution over 0.5 km to free troposphere (4-5 km) is also a goal of the program. This DIAL system leverages 2-micron laser technology developed under NASA's Laser Risk Reduction Program (LRRP) and other NASA programs to develop new solid-state laser technology that provides high pulse energy, tunable, wavelength-stabilized, and double-pulsed lasers that are operable over pre-selected temperature insensitive strong CO2 absorption lines suitable for profiling of lower tropospheric CO2. It also incorporates new high quantum efficiency, high gain, and relatively low noise phototransistors, and a new receiver/signal processor system to achieve high precision DIAL measurements. This presentation describes the capabilities of this system for atmospheric CO2 and aerosol profiling. Examples of atmospheric measurements in the lidar and DIAL mode will be presented.

  12. Covariation of deep Southern Ocean oxygenation and atmospheric CO2 through the last ice age.

    Science.gov (United States)

    Jaccard, Samuel L; Galbraith, Eric D; Martínez-García, Alfredo; Anderson, Robert F

    2016-02-11

    No single mechanism can account for the full amplitude of past atmospheric carbon dioxide (CO2) concentration variability over glacial-interglacial cycles. A build-up of carbon in the deep ocean has been shown to have occurred during the Last Glacial Maximum. However, the mechanisms responsible for the release of the deeply sequestered carbon to the atmosphere at deglaciation, and the relative importance of deep ocean sequestration in regulating millennial-timescale variations in atmospheric CO2 concentration before the Last Glacial Maximum, have remained unclear. Here we present sedimentary redox-sensitive trace-metal records from the Antarctic Zone of the Southern Ocean that provide a reconstruction of transient changes in deep ocean oxygenation and, by inference, respired carbon storage throughout the last glacial cycle. Our data suggest that respired carbon was removed from the abyssal Southern Ocean during the Northern Hemisphere cold phases of the deglaciation, when atmospheric CO2 concentration increased rapidly, reflecting--at least in part--a combination of dwindling iron fertilization by dust and enhanced deep ocean ventilation. Furthermore, our records show that the observed covariation between atmospheric CO2 concentration and abyssal Southern Ocean oxygenation was maintained throughout most of the past 80,000 years. This suggests that on millennial timescales deep ocean circulation and iron fertilization in the Southern Ocean played a consistent role in modifying atmospheric CO2 concentration.

  13. Observations of Atmospheric Δ(14)CO2 at the Global and Regional Background Sites in China: Implication for Fossil Fuel CO2 Inputs.

    Science.gov (United States)

    Niu, Zhenchuan; Zhou, Weijian; Cheng, Peng; Wu, Shugang; Lu, Xuefeng; Xiong, Xiaohu; Du, Hua; Fu, Yunchong

    2016-11-15

    Six months to more than one year of atmospheric Δ(14)CO2 were measured in 2014-2015 at one global background site in Waliguan (WLG) and four regional background sites at Shangdianzi (SDZ), Lin'an (LAN), Longfengshan (LFS) and Luhuitou (LHT), China. The objectives of the study are to document the Δ(14)CO2 levels at each site and to trace the variations in fossil fuel CO2 (CO2ff) inputs at regional background sites. Δ(14)CO2 at WLG varied from 7.1 ± 2.9‰ to 32.0 ± 3.2‰ (average 17.1 ± 6.8‰) in 2015, with high values generally in autumn/summer and low values in winter/spring. During the same period, Δ(14)CO2 values at the regional background sites were found to be significantly (p 0.05) seasonal differences in CO2ff concentrations for the regional sites. Regional sources contributed in part to the CO2ff inputs at LAN and SDZ, while local sources dominated the trend observed at LHT. These data provide a preliminary understanding of atmospheric Δ(14)CO2 and CO2ff inputs for a range of Chinese background sites.

  14. Lidar Observations of Atmospheric CO2 Column During 2014 Summer Flight Campaigns

    Science.gov (United States)

    Lin, Bing; Harrison, F. Wallace; Fan, Tai-Fang

    2015-01-01

    Advanced knowledge in atmospheric CO2 is critical in reducing large uncertainties in predictions of the Earth' future climate. Thus, Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) from space was recommended by the U.S. National Research Council to NASA. As part of the preparation for the ASCENDS mission, NASA Langley Research Center (LaRC) and Exelis, Inc. have been collaborating in development and demonstration of the Intensity-Modulated Continuous-Wave (IM-CW) lidar approach for measuring atmospheric CO2 column from space. Airborne laser absorption lidars such as the Multi-Functional Fiber Laser Lidar (MFLL) and ASCENDS CarbonHawk Experiment Simulator (ACES) operating in the 1.57 micron CO2 absorption band have been developed and tested to obtain precise atmospheric CO2 column measurements using integrated path differential absorption technique and to evaluate the potential of the space ASCENDS mission. This presentation reports the results of our lidar atmospheric CO2 column measurements from 2014 summer flight campaign. Analysis shows that for the 27 Aug OCO-2 under flight over northern California forest regions, significant variations of CO2 column approximately 2 ppm) in the lower troposphere have been observed, which may be a challenge for space measurements owing to complicated topographic condition, heterogeneity of surface reflection and difference in vegetation evapotranspiration. Compared to the observed 2011 summer CO2 drawdown (about 8 ppm) over mid-west, 2014 summer drawdown in the same region measured was much weak (approximately 3 ppm). The observed drawdown difference could be the results of the changes in both meteorological states and the phases of growing seasons. Individual lidar CO2 column measurements of 0.1-s integration were within 1-2 ppm of the CO2 estimates obtained from on-board in-situ sensors. For weak surface reflection conditions such as ocean surfaces, the 1- s integrated signal-to-noise ratio (SNR) of

  15. Root damage by insects reverses the effects of elevated atmospheric CO2 on Eucalypt seedlings.

    Directory of Open Access Journals (Sweden)

    Scott N Johnson

    Full Text Available Predicted increases in atmospheric carbon dioxide (CO2 are widely anticipated to increase biomass accumulation by accelerating rates of photosynthesis in many plant taxa. Little, however, is known about how soil-borne plant antagonists might modify the effects of elevated CO2 (eCO2, with root-feeding insects being particularly understudied. Root damage by insects often reduces rates of photosynthesis by disrupting root function and imposing water deficits. These insects therefore have considerable potential for modifying plant responses to eCO2. We investigated how root damage by a soil-dwelling insect (Xylotrupes gideon australicus modified the responses of Eucalyptus globulus to eCO2. eCO2 increased plant height when E. globulus were 14 weeks old and continued to do so at an accelerated rate compared to those grown at ambient CO2 (aCO2. Plants exposed to root-damaging insects showed a rapid decline in growth rates thereafter. In eCO2, shoot and root biomass increased by 46 and 35%, respectively, in insect-free plants but these effects were arrested when soil-dwelling insects were present so that plants were the same size as those grown at aCO2. Specific leaf mass increased by 29% under eCO2, but at eCO2 root damage caused it to decline by 16%, similar to values seen in plants at aCO2 without root damage. Leaf C:N ratio increased by >30% at eCO2 as a consequence of declining leaf N concentrations, but this change was also moderated by soil insects. Soil insects also reduced leaf water content by 9% at eCO2, which potentially arose through impaired water uptake by the roots. We hypothesise that this may have impaired photosynthetic activity to the extent that observed plant responses to eCO2 no longer occurred. In conclusion, soil-dwelling insects could modify plant responses to eCO2 predicted by climate change plant growth models.

  16. Improving the Ginkgo CO2 barometer: Implications for the early Cenozoic atmosphere

    Science.gov (United States)

    Barclay, Richard S.; Wing, Scott L.

    2016-04-01

    Stomatal properties of fossil Ginkgo have been used widely to infer the atmospheric concentration of CO2 in the geological past (paleo-pCO2). Many of these estimates of paleo-pCO2 have relied on the inverse correlation between pCO2 and stomatal index (SI - the proportion of epidermal cells that are stomata) observed in recent Ginkgo biloba, and therefore depend on the accuracy of this relationship. The SI - pCO2 relationship in G. biloba has not been well documented, however. Here we present new measurements of SI for leaves of G. biloba that grew under pCO2 from 290 to 430 ppm. We prepared and imaged all specimens using a consistent procedure and photo-documented each count. As in prior studies, we found a significant inverse relationship between SI and pCO2, however, the relationship is more linear, has a shallower slope, and a lower correlation coefficient than previously reported. We examined leaves of G. biloba grown under pCO2 of 1500 ppm, but found they had highly variable SI and a large proportion of malformed stomata. We also measured stomatal dimensions, stomatal density, and the carbon isotope composition of G. biloba leaves in order to test a mechanistic model for inferring pCO2. This model overestimated observed pCO2, performing less well than the SI method between 290 and 430 ppm. We used our revised SI-pCO2 response curve, and new observations of selected fossils, to estimate late Cretaceous and Cenozoic pCO2 from fossil Ginkgo adiantoides. All but one of the new estimates is below 800 ppm, and together they show little long-term change in pCO2 or relation to global temperature. The low Paleogene pCO2 levels indicated by the Ginkgo SI proxy are not consistent with the high pCO2 inferred by some climate and carbon cycle models. We cannot currently resolve the discrepancy, but greater agreement between proxy data and models may come from a better understanding of the stomatal response of G. biloba to elevated pCO2, better counts and measurements of

  17. EXPLOSIVE ABSORPTION EFFECT OF POWER CO2 LASER BEAM IN ATMOSPHERE

    OpenAIRE

    Zakharov, V.; Shmelev, V.; Nesterenko, A.

    1991-01-01

    The interaction of a wide beam of intense 10.6 µm and 9.4 µm laser radiation with atmospheric CO2 is studied. The threshold spectroscopic effect of explosive absorption have been obtained. In this effect the absorption coefficient of the atmosphere increases sharply owing to strong self-heating ([MATH] 700-1000 K) of the beam channel.

  18. Plate tectonic controls on atmospheric CO2 levels since the Triassic

    NARCIS (Netherlands)

    van der Meer, D.G.; Zeebe, R.; van Hinsbergen, D.J.J.; Sluijs, A.; Spakman, W.; Torsvik, T.H.

    2014-01-01

    Climate trends on timescales of 10s to 100s of millions of years are controlled by changes in solar luminosity, continent distribution, and atmosphere composition. Plate tectonics affect geography, but also atmosphere composition through volcanic degassing of CO2 at subduction zones and midocean rid

  19. A possible new role for atmospheric 13CO2 in global models

    NARCIS (Netherlands)

    Miller, J. B.; Ballantyne, A.; Berry, J. A.; Peters, W.; Still, C.; Tans, P.; White, J.

    2008-01-01

    The promise of utilizing large-scale atmospheric δ13CO2 measurements to understand terrestrial processes has not been fully realized. Here, we will present recent progress in the use of measurements and simulations of atmospheric δ13C to better understand the signals of the biosphere contained withi

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

    NARCIS (Netherlands)

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

    2011-01-01

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

  1. A possible mechanism of mineral responses to elevated atmospheric CO2 in rice grains

    Institute of Scientific and Technical Information of China (English)

    GUO Jia; ZHANG Ming-qian; WANG Xiao-wen; ZHANG Wei-jian

    2015-01-01

    Increasing attentions have been paid to mineral concentration decrease in miled rice grains caused by CO2 enrichment, but the mechanisms stil remain unclear. Therefore, mineral (Ca, Mg, Fe, Zn and Mn) translocation in plant-soil system with a FACE (Free-air CO2 enrichment) experiment were investigated in Eastern China after 4-yr operation. Results mainly showed that: (1) elevated CO2 signiifcantly increased the biomass of stem and panicle by 21.9 and 24.0%, respectively, but did not affect the leaf biomass. (2) Elevated CO2 signiifcantly increased the contents of Ca, Mg, Fe, Zn, and Mn in panicle by 61.2, 28.9, 87.0, 36.7, and 66.0%, respectively, and in stem by 13.2, 21.3, 47.2, 91.8, and 25.2%, respectively, but did not affect them in leaf. (3) Elevated CO2 had positive effects on the weight ratio of mineral/biomass in stem and panicle. Our results suggest that elevated CO2 can favor the translocation of Ca, Mg, Fe, Zn, and Mn from soil to stem and panicle. The CO2-led mineral decline in miled rice grains may mainly attribute to the CO2-led unbalanced stimulations on the translocations of minerals and carbohydrates from vegetative parts (e.g., leaf, stem, branch and husk) to the grains.

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

    Science.gov (United States)

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

    2015-04-01

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

  3. Advances on the Responses of Root Dynamics to Increased Atmospheric CO2 and Global Climate Change

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Plant roots dynamics responses to elevated atmospheric CO2 concentration, increased temperature and changed precipitation can be a key link between plant growth and long-term changes in soil organic matter and ecosystem carbon balance. This paper reviews some experiments and hypotheses developed in this area, which mainly include plant fine roots growth, root turnover, root respiration and other root dynamics responses to elevated CO2 and global climate change. Some recent new methods of studying root systems were also discussed and summarized. It holds herein that the assemblage of information about root turnover patterns, root respiration and other dynamic responses to elevated atmospheric CO2 and global climatic change can help to better understand and explore some new research areas. In this paper, some research challenges in the plant root responses to the elevated CO2 and other environmental factors during global climate change were also demonstrated.

  4. Developing a passive trap for diffusive atmospheric 14CO2 sampling

    Science.gov (United States)

    Walker, Jennifer C.; Xu, Xiaomei; Fahrni, Simon M.; Lupascu, Massimo; Czimczik, Claudia I.

    2015-10-01

    14C-CO2 measurement is an unique tool to quantify source-based emissions of CO2 for both the urban and natural environments. Acquiring a sample that temporally integrates the atmospheric 14C-CO2 signature that allows for precise 14C analysis is often necessary, but can require complex sampling devices, which can be difficult to deploy and maintain, especially for multiple locations. Here we describe our progress in developing a diffusive atmospheric CO2 molecular sieve trap, which requires no power to operate. We present results from various cleaning procedures, and rigorously tested for blank and memory effects. Traps were tested in the environment along-side conventional sampling flasks for accuracy. Results show that blank and memory effects can be minimized with thorough cleaning and by avoiding overheating, and that diffusively collected air samples agree well with traditionally canister-sampled air.

  5. 2-Micron Pulsed Direct Detection IPDA Lidar for Atmospheric CO2 Measurement

    Science.gov (United States)

    Yu, Jirong; Petros, Mulugeta; Refaat, Tamer; Reithmaier, Karl; Remus, Ruben; Singh, Upendra; Johnson, Will; Boyer, Charlie; Fay, James; Johnston, Susan; Murchison, Luke

    2014-01-01

    A 2-micron high energy, pulsed Integrated Path Differential Absorption (IPDA) lidar has been developed for atmospheric CO2 measurements. Development of this lidar heavily leverages the 2-micron laser technologies developed in LaRC over the last decade. The high pulse energy, direct detection lidar operating at CO2 2-micron absorption band provides an alternate approach to measure CO2 concentrations. This new 2-micron pulsed IPDA lidar has been flown in spring of this year for total ten flights with 27 flight hours. It is able to make measurements of the total amount of atmospheric CO2 from the aircraft to the ground or cloud. It is expected to provide high-precision measurement capability by unambiguously eliminating contamination from aerosols and clouds that can bias the IPDA measurement.

  6. Development of a mobile and high-precision atmospheric CO2 monitoring station

    Science.gov (United States)

    Molnár, M.; Haszpra, L.; Major, I.; Svingor, É.; Veres, M.

    2009-04-01

    Nowadays one of the most burning questions for the science is the rate and the reasons of the recent climate change. Greenhouse gases (GHG), mainly CO2 and CH4 in the atmosphere could affect the climate of our planet. However, the relation between the amount of atmospheric GHG and the climate is complex, full with interactions and feedbacks partly poorly known even by now. The only way to understand the processes, to trace the changes, to develop and validate mathematical models for forecasts is the extensive, high precision, continuous monitoring of the atmosphere. Fossil fuel CO2 emissions are a major component of the European carbon budget. Separation of the fossil fuel signal from the natural biogenic one in the atmosphere is, therefore, a crucial task for quantifying exchange flux of the continental biosphere through atmospheric observations and inverse modelling. An independent method to estimate trace gas emissions is the top-down approach, using atmospheric CO2 concentration measurements combined with simultaneous radiocarbon (14C) observations. As adding fossil fuel CO2 to the atmosphere, therefore, leads not only to an increase in the CO2 content of the atmosphere but also to a decrease in the 14C/12C ratio in atmospheric CO2. The ATOMKI has more than two decade long experience in atmospheric 14CO2 monitoring. As a part of an ongoing research project being carried out in Hungary to investigate the amount and temporal and spatial variations of fossil fuel CO2 in the near surface atmosphere we developed a mobile and high-precision atmospheric CO2 monitoring station. We describe the layout and the operation of the measuring system which is designed for the continuous, unattended monitoring of CO2 mixing ratio in the near surface atmosphere based on an Ultramat 6F (Siemens) infrared gas analyser. In the station one atmospheric 14CO2 sampling unit is also installed which is developed and widely used since more than one decade by ATOMKI. Mixing ratio of CO2 is

  7. Fast Atmosphere-Ocean Model Runs with Large Changes in CO2

    Science.gov (United States)

    Russell, Gary L.; Lacis, Andrew A.; Rind, David H.; Colose, Christopher; Opstbaum, Roger F.

    2013-01-01

    How does climate sensitivity vary with the magnitude of climate forcing? This question was investigated with the use of a modified coupled atmosphere-ocean model, whose stability was improved so that the model would accommodate large radiative forcings yet be fast enough to reach rapid equilibrium. Experiments were performed in which atmospheric CO2 was multiplied by powers of 2, from 1/64 to 256 times the 1950 value. From 8 to 32 times, the 1950 CO2, climate sensitivity for doubling CO2 reaches 8 C due to increases in water vapor absorption and cloud top height and to reductions in low level cloud cover. As CO2 amount increases further, sensitivity drops as cloud cover and planetary albedo stabilize. No water vapor-induced runaway greenhouse caused by increased CO2 was found for the range of CO2 examined. With CO2 at or below 1/8 of the 1950 value, runaway sea ice does occur as the planet cascades to a snowball Earth climate with fully ice covered oceans and global mean surface temperatures near 30 C.

  8. Implications of high amplitude atmospheric CO2 fluctuations on past millennium climate change

    Science.gov (United States)

    van Hoof, Thomas; Kouwenberg, Lenny; Wagner-Cremer, Friederike; Visscher, Henk

    2010-05-01

    Stomatal frequency analysis of leaves of land plants preserved in peat and lake deposits can provide a proxy record of pre-industrial atmospheric CO2 concentration complementary to measurements in Antarctic ice cores. Stomatal frequency based CO2 trends from the USA and NW European support the presence of significant CO2 variability during the first half of the last millennium (Kouwenberg et al., 2005; Wagner et al., 2004; van Hoof et al., 2008). The timing of the most significant perturbation in the stomata records (1200 AD) is in agreement with an observed CO2 fluctuation in the D47 Antarctic ice-core record (Barnola et al., 1995; van Hoof et al., 2005). The amplitude of the stomatal frequency based CO2 changes (> 34ppmv) exceeds the maximum amplitude of CO2 variability in the D47 ice core (Proceedings of the National Academy of Sciences of the USA, v. 105, no. 41, pp. 15815-15818 Wagner F., L.L.R. Kouwenberg, T.B. van Hoof and H. Visscher 2004. Reproducibility of Holocene atmospheric CO2 records based on stomatal frequency. Quartenary Science Reviews. V. 23, pp. 1947-1954

  9. Biomass and toxicity responses of poison ivy (Toxicodendron radicans) to elevated atmospheric CO2.

    Science.gov (United States)

    Mohan, Jacqueline E; Ziska, Lewis H; Schlesinger, William H; Thomas, Richard B; Sicher, Richard C; George, Kate; Clark, James S

    2006-06-13

    Contact with poison ivy (Toxicodendron radicans) is one of the most widely reported ailments at poison centers in the United States, and this plant has been introduced throughout the world, where it occurs with other allergenic members of the cashew family (Anacardiaceae). Approximately 80% of humans develop dermatitis upon exposure to the carbon-based active compound, urushiol. It is not known how poison ivy might respond to increasing concentrations of atmospheric carbon dioxide (CO(2)), but previous work done in controlled growth chambers shows that other vines exhibit large growth enhancement from elevated CO(2). Rising CO(2) is potentially responsible for the increased vine abundance that is inhibiting forest regeneration and increasing tree mortality around the world. In this 6-year study at the Duke University Free-Air CO(2) Enrichment experiment, we show that elevated atmospheric CO(2) in an intact forest ecosystem increases photosynthesis, water use efficiency, growth, and population biomass of poison ivy. The CO(2) growth stimulation exceeds that of most other woody species. Furthermore, high-CO(2) plants produce a more allergenic form of urushiol. Our results indicate that Toxicodendron taxa will become more abundant and more "toxic" in the future, potentially affecting global forest dynamics and human health.

  10. Effect of elevated atmospheric CO2 on carbon allocation patterns in Eriphorum vaginatum

    Science.gov (United States)

    Strom, L.

    2013-12-01

    Greenhouse gases of particular importance to the human induced greenhouse effect are, e.g., CO2 and CH4. Natural and agricultural wetlands together contribute with over 40 % of the annual atmospheric emissions of CH4 and are, therefore, considered to be the largest single contributor of this gas to the troposphere. There is a growing concern that increasing atmospheric concentrations of CO2 will stimulate CH4 production and emission from wetland ecosystems, resulting in feedback mechanisms that in future will increase the radiative forcing of these ecosystems. The aim of this study was to elucidate the effect of elevated atmospheric CO2 on fluxes of CO2 and CH4, biomass allocation patterns and amount of labile substrates (i.e. low molecular weight organic acids, OAs) for CH4 production in the root vicinity of Eriophorum vaginatum. Eriophorum cores and plants were collected at Fäjemyr, a temperate ombrotrophic bog situated in the south of Sweden. These were cultivated under controlled environmental conditions in an atmosphere of 390 or 800 ppm of CO2 (n=5 per treatment). After a one month development period gas fluxes were measured twice per week over one month using a Fourier Transform Infrared spectrometer (Gasmet Dx-4030) and OAs using a liquid chromatography-ionspray tandem mass spectrometry system (Dionex ICS-2500 and Applied Biosystems 2000 Q-Trap triple quadrupole MS). The results clearly show that elevated CO2 significantly affects all measured parts of the carbon cycle. Greenhouse gas fluxes were significantly (repeated measures test) higher under elevated CO2 conditions, NEE p leaves, roots and concentration of OAs around the roots of plants, p = 0.045, p = 0 = 0.045 and p = 0.045 respectively (Kruskal wallis 1-way anova). The study shows higher CH4 emissions under elevated CO2 and that this may be due to a priming effect, due to input of fresh labile-C via living roots and possibly higher biomass. However the concern that elevated atmospheric

  11. The Dependence of Plant δ13C on Atmospheric pCO2

    Science.gov (United States)

    Jahren, H.; Schubert, B.

    2011-12-01

    Numerous studies on multicellular plants have reported increasing carbon isotope fractionation in leaf tissue with increasing concentrations of atmospheric carbon dioxide (pCO2), but the magnitude of the effect is highly variable (i.e., 0.62 to 2.7 % per 100 ppm CO2). The majority of these experiments tested only small differences in CO2 levels (Raphanus sativus plants grown under controlled light, water, and temperature conditions, and varying the pCO2 concentrations across a trajectory of 17 different pCO2 levels ranging from 370 to 4200 ppm. From this large dataset, we show that the carbon isotope discrimination [Δδ13C = (δ13CCO2 - δ13Cplant) / (1000 + δ13Cplant)] is indeed a function of pCO2, however, the relationship is hyperbolic, rather than linear, as is typically assumed. Across the small changes in pCO2 previously studied the response appears linear, however, our expanded dataset clearly shows that increases in Δδ13C level off at high pCO2, which is consistent with the ultimate control over fractionation being the activity of Rubisco as the concentration of pCO2 inside the leaf approaches the pCO2 level outside the leaf. The hyperbolic relationship we have quantified using published and new data is extremely robust (R2 = 0.90, n = 26, P < 0.0001), and evident in n-alkanes as well as bulk tissue, suggesting the potential for application to fossil plant materials in order to reconstruct pCO2 across critical intervals.

  12. Weathering by tree-root-associating fungi diminishes under simulated Cenozoic atmospheric CO2 decline

    Science.gov (United States)

    Quirk, J.; Leake, J. R.; Banwart, S. A.; Taylor, L. L.; Beerling, D. J.

    2014-01-01

    Trees dominate terrestrial biotic weathering of silicate minerals by converting solar energy into chemical energy that fuels roots and their ubiquitous nutrient-mobilising fungal symbionts. These biological activities regulate atmospheric CO2 concentrations ([CO2]a) over geologic timescales by driving calcium and magnesium fluvial ion export and marine carbonate formation. However, the important stabilising feedbacks between [CO2]a and biotic weathering anticipated by geochemical carbon cycle models remain untested. We report experimental evidence for a negative feedback across a declining Cenozoic [CO2]a range from 1500 to 200 ppm, whereby low [CO2]a curtails mineral surface alteration via trenching and etch pitting by arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) fungal partners of tree roots. Optical profile imaging using vertical scanning interferometry reveals changes in nanoscale surface topography consistent with a dual mode of attack involving delamination and trenching by AM and EM fungal hyphae on phyllosilicate mineral flakes. This is consistent with field observations of micropores in feldspar, hornblende and basalt, purportedly caused by EM fungi, but with little confirmatory evidence. Integrating these findings into a process-based biotic weathering model revealed that low [CO2]a effectively acts as a "carbon starvation" brake, causing a three-fold drop in tree-driven fungal weathering fluxes of calcium and magnesium from silicate rock grains as [CO2]a falls from 1500 to 200 ppm. The feedback is regulated through the action of low [CO2]a on host tree productivity and provides empirical evidence for the role of [CO2]a starvation in diminishing the contribution of trees and mycorrhizal fungi to rates of biological weathering. More broadly, diminished tree-driven weathering under declining [CO2]a may provide an important contributory mechanism stabilising Earth's [CO2]a minimum over the past 24 million years.

  13. Weathering by tree root-associating fungi diminishes under simulated Cenozoic atmospheric CO2 decline

    Science.gov (United States)

    Quirk, J.; Leake, J. R.; Banwart, S. A.; Taylor, L. L.; Beerling, D. J.

    2013-10-01

    Trees dominate terrestrial biotic weathering of silicate minerals by converting solar energy into chemical energy that fuels roots and their ubiquitous nutrient-mobilising fungal symbionts. These biological activities regulate atmospheric CO2 ([CO2]a) over geologic timescales by driving calcium and magnesium fluvial ion export and marine carbonate formation, but the important stabilising feedbacks between [CO2]a and biotic weathering anticipated by geochemical carbon cycle models remain untested. We report experimental evidence for a negative feedback across a declining Cenozoic [CO2]a range from 1500 ppm to 200 ppm, whereby low [CO2]a curtails mineral surface alteration via trenching and etch pitting by arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) fungal partners of tree roots. Optical profile imaging using vertical scanning interferometry reveals changes in nanoscale surface topography consistent with a dual mode of attack involving delamination and trenching by AM and EM fungal hyphae on phyllosilicate mineral flakes. This is consistent with field observations of micropores in feldspar, hornblende and basalt, purportedly caused by EM fungi, but with little confirmatory evidence. Integrating these findings into a process-based biotic weathering model revealed that low [CO2]a effectively acts as a "carbon starvation" brake, causing a three-fold drop in tree-driven fungal weathering fluxes of calcium and magnesium from silicate rock grains as [CO2]a falls from 1500 ppm to 200 ppm. The feedback is regulated through the action of low [CO2]a on host tree productivity and provides empirical evidence for the role of [CO2]a starvation in diminishing the contribution of trees and mycorrhizal fungi to rates of biological weathering. More broadly, diminished tree-driven weathering under declining [CO2]a may provide an important contributory mechanism stabilising Earth's [CO2]a minimum over the past 24 million years.

  14. Weathering by tree root-associating fungi diminishes under simulated Cenozoic atmospheric CO2 decline

    Directory of Open Access Journals (Sweden)

    J. Quirk

    2013-10-01

    Full Text Available Trees dominate terrestrial biotic weathering of silicate minerals by converting solar energy into chemical energy that fuels roots and their ubiquitous nutrient-mobilising fungal symbionts. These biological activities regulate atmospheric CO2 ([CO2]a over geologic timescales by driving calcium and magnesium fluvial ion export and marine carbonate formation, but the important stabilising feedbacks between [CO2]a and biotic weathering anticipated by geochemical carbon cycle models remain untested. We report experimental evidence for a negative feedback across a declining Cenozoic [CO2]a range from 1500 ppm to 200 ppm, whereby low [CO2]a curtails mineral surface alteration via trenching and etch pitting by arbuscular mycorrhizal (AM and ectomycorrhizal (EM fungal partners of tree roots. Optical profile imaging using vertical scanning interferometry reveals changes in nanoscale surface topography consistent with a dual mode of attack involving delamination and trenching by AM and EM fungal hyphae on phyllosilicate mineral flakes. This is consistent with field observations of micropores in feldspar, hornblende and basalt, purportedly caused by EM fungi, but with little confirmatory evidence. Integrating these findings into a process-based biotic weathering model revealed that low [CO2]a effectively acts as a "carbon starvation" brake, causing a three-fold drop in tree-driven fungal weathering fluxes of calcium and magnesium from silicate rock grains as [CO2]a falls from 1500 ppm to 200 ppm. The feedback is regulated through the action of low [CO2]a on host tree productivity and provides empirical evidence for the role of [CO2]a starvation in diminishing the contribution of trees and mycorrhizal fungi to rates of biological weathering. More broadly, diminished tree-driven weathering under declining [CO2]a may provide an important contributory mechanism stabilising Earth's [CO2]a minimum over the past 24 million years.

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

    Science.gov (United States)

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

    2012-09-15

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

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

    Science.gov (United States)

    Santos, Bruna Marques Dos; Balbuena, Tiago Santana

    2017-01-06

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

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

    Science.gov (United States)

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

    2016-10-01

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

  18. Atmospheric CO2 enrichment alters energy assimilation, investment and allocation in Xanthium strumarium.

    Science.gov (United States)

    Nagel, Jennifer M; Wang, Xianzhong; Lewis, James D; Fung, Howard A; Tissue, David T; Griffin, Kevin L

    2005-05-01

    Energy-use efficiency and energy assimilation, investment and allocation patterns are likely to influence plant growth responses to increasing atmospheric CO2 concentration ([CO2]). Here, we describe the influence of elevated [CO2] on energetic properties as a mechanism of growth responses in Xanthium strumarium. Individuals of X. strumarium were grown at ambient or elevated [CO2] and harvested. Total biomass and energetic construction costs (CC) of leaves, stems, roots and fruits and percentage of total biomass and energy allocated to these components were determined. Photosynthetic energy-use efficiency (PEUE) was calculated as the ratio of total energy gained via photosynthetic activity (Atotal) to leaf CC. Elevated [CO2] increased leaf Atotal, but decreased CC per unit mass of leaves and roots. Consequently, X. strumarium individuals produced more leaf and root biomass at elevated [CO2] without increasing total energy investment in these structures (CCtotal). Whole-plant biomass was associated positively with PEUE. Whole-plant construction required 16.1% less energy than modeled whole-plant energy investment had CC not responded to increased [CO2]. As a physiological mechanism affecting growth, altered energetic properties could positively influence productivity of X. strumarium, and potentially other species, at elevated [CO2].

  19. Atmospheric pCO2 control on speleothem stable carbon isotope compositions

    Science.gov (United States)

    Breecker, Daniel O.

    2017-01-01

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

  20. Effects of elevated atmospheric CO2 and/or O3 on intra- and interspecific competitive ability of aspen.

    Science.gov (United States)

    Kubiske, M E; Quinn, V S; Marquardt, P E; Karnosky, D F

    2007-03-01

    Three model communities of trembling aspen (monoculture, and mixed with either paper birch or sugar maple) were grown for seven years in elevated atmospheric CO(2) and O(3) using Free Air CO(2) Enrichment (FACE) technology. We utilized trends in species' importance, calculated as an index of volume growth and survival, as indications of shifting community composition. For the pure aspen communities, different clones emerged as having the highest change in relative importance values depending on the pollutant exposure. In the control and elevated CO(2) treatments, clone 42E was rapidly becoming the most successful clone while under elevated O(3), clone 8 L emerged as the dominant clone. In fact, growth of clone 8 L was greater in the elevated O(3) treatment compared to controls. For the mixed aspen-birch community, importance of aspen and birch changed by - 16 % and + 62 %, respectively, in the controls. In the treatments, however, importance of aspen and birch changed by - 27 % and + 87 %, respectively, in elevated O(3), and by - 10 % and + 45 %, respectively, in elevated CO(2). Thus, the presence of elevated O(3) hastened conversion of stands to paper birch, whereas the presence of elevated CO(2) delayed it. Relative importance of aspen and maple changed by - 2 % and + 3 %, respectively, after seven years in the control treatments. But in elevated O(3), relative importance of aspen and maple changed by - 2 % and + 5 %, respectively, and in elevated CO(2) by + 9 and - 20 %, respectively. Thus, elevated O(3) slightly increases the rate of conversion of aspen stands to sugar maple, but maple is placed at a competitive disadvantage to aspen under elevated CO(2).

  1. VARIABILITY OF ATMOSPHERIC CO2 OVER INDIA AND SURROUNDING OCEANS AND CONTROL BY SURFACE FLUXES

    Directory of Open Access Journals (Sweden)

    R. K. Nayak

    2012-08-01

    Full Text Available In the present study, seasonal and inter-annual variability of atmospheric CO2 concentration over India and surrounding oceans during 2002–2010 derived from Atmospheric InfrarRed Sounder observation and their relation with the natural flux exchanges over terrestrial Indian and surrounding oceans were analyzed. The natural fluxes over the terrestrial Indian in the form of net primary productivity (NPP were simulated based on a terrestrial biosphere model governed by time varying climate parameters (solar radiation, air temperature, precipitation etc and satellite greenness index together with the land use land cover and soil attribute maps. The flux exchanges over the oceans around India (Tropical Indian Ocean: TIO were calculated based on a empirical model of CO2 gas dissolution in the oceanic water governed by time varying upper ocean parameters such as gradient of partial pressure of CO2 between ocean and atmosphere, winds, sea surface temperature and salinity. Comparison between the variability of atmospheric CO2 anomaly with the anomaly of surface fluxes over India and surrounding oceans suggests that biosphere uptake over India and oceanic uptake over the south Indian Ocean could play positive role on the control of seasonal variability of atmospheric carbon dioxide growth rate. On inter-annual scale, flux exchanges over the tropical north Indian Ocean could play positive role on the control of atmospheric carbon dioxide growth rate.

  2. Radiative transfer in CO2-rich atmospheres: 1. Collisional line mixing implies a colder early Mars

    Science.gov (United States)

    Ozak, N.; Aharonson, O.; Halevy, I.

    2016-06-01

    Fast and accurate radiative transfer methods are essential for modeling CO2-rich atmospheres, relevant to the climate of early Earth and Mars, present-day Venus, and some exoplanets. Although such models already exist, their accuracy may be improved as better theoretical and experimental constraints become available. Here we develop a unidimensional radiative transfer code for CO2-rich atmospheres, using the correlated k approach and with a focus on modeling early Mars. Our model differs from existing models in that it includes the effects of CO2 collisional line mixing in the calculation of the line-by-line absorption coefficients. Inclusion of these effects results in model atmospheres that are more transparent to infrared radiation and, therefore, in colder surface temperatures at radiative-convective equilibrium, compared with results of previous studies. Inclusion of water vapor in the model atmosphere results in negligible warming due to the low atmospheric temperatures under a weaker early Sun, which translate into climatically unimportant concentrations of water vapor. Overall, the results imply that sustained warmth on early Mars would not have been possible with an atmosphere containing only CO2 and water vapor, suggesting that other components of the early Martian climate system are missing from current models or that warm conditions were not long lived.

  3. The impact on atmospheric CO2 of iron fertilization induced changes in the ocean's biological pump

    Directory of Open Access Journals (Sweden)

    J. C. McWilliams

    2007-10-01

    Full Text Available Using numerical simulations, we quantify the impact of changes in the ocean's biological pump on the air-sea balance of CO2 by fertilizing a small surface patch in the high-nutrient, low-chlorophyll region of the eastern tropical Pacific with iron. Decade-long fertilization experiments are conducted in a basin-scale, eddy-permitting coupled physical biogeochemical ecological model. In contrast to previous studies, we find that most of the dissolved inorganic carbon (DIC removed from the euphotic zone by the enhanced biological export is replaced by uptake of CO2 from the atmosphere. Atmospheric uptake efficiencies, the ratio of the perturbation in air-sea CO2 flux to the perturbation in export flux across 100 m, are 0.75 to 0.93 in our patch size-scale experiments. The atmospheric uptake efficiency is insensitive to the duration of the experiment. The primary factor controlling the atmospheric uptake efficiency is the vertical distribution of the enhanced biological production. Iron fertilization at the surface tends to induce production anomalies primarily near the surface, leading to high efficiencies. In contrast, mechanisms that induce deep production anomalies (e.g. altered light availability tend to have a low uptake efficiency, since most of the removed DIC is replaced by lateral and vertical transport and mixing. Despite high atmospheric uptake efficiencies, patch-scale iron fertilization of the ocean's biological pump tends to remove little CO2 from the atmosphere over the decadal timescale considered here.

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

    Science.gov (United States)

    Kluge, M

    1969-06-01

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

  5. Assessing the near surface sensitivity of SCIAMACHY atmospheric CO2 retrieved using (FSI WFM-DOAS

    Directory of Open Access Journals (Sweden)

    N. Vinnichenko

    2007-02-01

    Full Text Available Satellite observations of atmospheric CO2 offer the potential to identify regional carbon surface sources and sinks and to investigate carbon cycle processes. The extent to which satellite measurements are useful however, depends on the near surface sensitivity of the chosen sensor. In this paper, the capability of the SCIAMACHY instrument on board ENVISAT, to observe lower tropospheric and surface CO2 variability is examined. To achieve this, atmospheric CO2 retrieved from SCIAMACHY near infrared (NIR spectral measurements, using the Full Spectral Initiation (FSI WFM-DOAS algorithm, is compared to in situ aircraft observations over Siberia and additionally to tower and surface CO2 data over Mongolia, Europe and North America. Preliminary validation of daily averaged SCIAMACHY/FSI CO2 against ground based Fourier Transform Spectrometer (FTS column measurements made at Park Falls, reveal a negative bias of about −2.0% for collocated measurements within ±1.0degree of the site. However, at this spatial threshold SCIAMACHY can only capture the variability of the FTS observations at monthly timescales. To observe day to day variability of the FTS observations, the collocation limits must be increased. Furthermore, comparisons to in-situ CO2 observations demonstrate that SCIAMACHY is capable of observing lower tropospheric variability on (at least monthly timescales. Out of seventeen time series comparisons, eleven have correlation coefficients of 0.7 or more, and have similar seasonal cycle amplitudes. Additional evidence of the near surface sensitivity of SCIAMACHY, is provided through the significant correlation of FSI derived CO2 with MODIS vegetation indices at over twenty selected locations in the United States. The SCIAMACHY/MODIS comparison reveals that at many of the sites, the amount of CO2 variability is coincident with the amount of vegetation activity. It is evident, from this analysis, that SCIAMACHY therefore has the potential to

  6. Assessing the near surface sensitivity of SCIAMACHY atmospheric CO2 retrieved using (FSI WFM-DOAS

    Directory of Open Access Journals (Sweden)

    N. Vinnichenko

    2007-07-01

    Full Text Available Satellite observations of atmospheric CO2 offer the potential to identify regional carbon surface sources and sinks and to investigate carbon cycle processes. The extent to which satellite measurements are useful however, depends on the near surface sensitivity of the chosen sensor. In this paper, the capability of the SCIAMACHY instrument on board ENVISAT, to observe lower tropospheric and surface CO2 variability is examined. To achieve this, atmospheric CO2 retrieved from SCIAMACHY near infrared (NIR spectral measurements, using the Full Spectral Initiation (FSI WFM-DOAS algorithm, is compared to in-situ aircraft observations over Siberia and additionally to tower and surface CO2 data over Mongolia, Europe and North America. Preliminary validation of daily averaged SCIAMACHY/FSI CO2 against ground based Fourier Transform Spectrometer (FTS column measurements made at Park Falls, reveal a negative bias of about −2.0% for collocated measurements within ±1.0° of the site. However, at this spatial threshold SCIAMACHY can only capture the variability of the FTS observations at monthly timescales. To observe day to day variability of the FTS observations, the collocation limits must be increased. Furthermore, comparisons to in-situ CO2 observations demonstrate that SCIAMACHY is capable of observing a seasonal signal that is representative of lower tropospheric variability on (at least monthly timescales. Out of seventeen time series comparisons, eleven have correlation coefficients of 0.7 or more, and have similar seasonal cycle amplitudes. Additional evidence of the near surface sensitivity of SCIAMACHY, is provided through the significant correlation of FSI derived CO2 with MODIS vegetation indices at over twenty selected locations in the United States. The SCIAMACHY/MODIS comparison reveals that at many of the sites, the amount of CO2 variability is coincident with the amount of vegetation activity. The presented analysis suggests that

  7. VUV-absorption cross section of CO2 at high temperatures and impact on exoplanet atmospheres

    Directory of Open Access Journals (Sweden)

    Venot Olivia

    2014-02-01

    Full Text Available Ultraviolet (UV absorption cross sections are an essential ingredient of photochemical atmosphere models. Exoplanet searches have unveiled a large population of short-period objects with hot atmospheres, very different from what we find in our solar system. Transiting exoplanets whose atmospheres can now be studied by transit spectroscopy receive extremely strong UV fluxes and have typical temperatures ranging from 400 to 2500 K. At these temperatures, UV photolysis cross section data are severely lacking. Our goal is to provide high-temperature absorption cross sections and their temperature dependency for important atmospheric compounds. This study is dedicated to CO2, which is observed and photodissociated in exoplanet atmospheres. We performed these measurements for the 115 - 200 nm range at 300, 410, 480, and 550 K. In the 195 - 230 nm range, we worked at seven temperatures between 465 and 800 K. We found that the absorption cross section of CO2 is very sensitive to temperature, especially above 160 nm. Within the studied range of temperature, the CO2 cross section can vary by more than two orders of magnitude. This, in particular, makes the absorption of CO2 significant up to wavelengths as high as 230 nm, while it is negligible above 200 nm at 300 K. To investigate the influence of these new data on the photochemistry of exoplanets, we implemented the measured cross section into a 1D photochemical model. The model predicts that accounting for this temperature dependency of CO2 cross section can affect the computed abundances of NH3, CO2, and CO by one order of magnitude in the atmospheres of hot Jupiter and hot Neptune.

  8. Role of Southern Ocean stratification in glacial atmospheric CO2 reduction

    Science.gov (United States)

    Kobayashi, H.; Oka, A.

    2014-12-01

    Paleoclimate proxy data at the glacial period shows high salinity of more than 37.0 psu in the deep South Atlantic. At the same time, data also indicate that the residence time of the water mass was more than 3000 years. These data implies that the stratification by salinity was stronger in the deep Southern Ocean (SO) in the Last Glacial Maximum (LGM). Previous studies using Ocean General Circulation Model (OGCM) fail to explain the low glacial atmospheric carbon dioxide (CO2) concentration at LGM. The reproducibility of salinity and water mass age is considered insufficient in these OGCMs, which may in turn affect the reproducibility of the atmospheric CO2concentration. In coarse-resolution OGCMs, The deep water is formed by unrealistic open-ocean deep convection in the SO. Considering these facts, we guessed previous studies using OGCM underestimated the salinity and water mass age at LGM. This study investigate the role of the enhanced stratification in the glacial SO on the variation of atmospheric CO2 concentration by using OGCM. In order to reproduce the recorded salinity of the deep water, relaxation of salinity toward value of recorded data is introduced in our OGCM simulations. It was found that deep water formation in East Antarctica is required for explaining the high salinity in the South Atlantic. In contrast, it is difficult to explain the glacial water mass age, even if we assume the situation vertical mixing is very weak in the SO. Contrary to previous estimate, the high salinity of the deep SO resulted in increase of Antarctic Bottom water (AABW) flow and decrease the residence time of carbon in the deep ocean, which increased atmospheric CO2 concentration. On the other hand, the weakening of the vertical mixing in the SO contributed to increase the vertical gradient of dissolved inorganic carbon (DIC), which decreased atmospheric CO2 concentration. Adding the contribution of the enhanced stratification in the glacial SO, we obtained larger

  9. Investigating CO2 Reservoirs at Gale Crater and Evidence for a Dense Early Atmosphere

    Science.gov (United States)

    Niles, P. B.; Archer, P. D.; Heil, E.; Eigenbrode, J.; McAdam, A.; Sutter, B.; Franz, H.; Navarro-Gonzalez, R.; Ming, D.; Mahaffy, P. R.; Martin-Torres, F. J.; Zorzano, M.

    2015-01-01

    One of the most compelling features of the Gale landing site is its age. Based on crater counts, the formation of Gale crater is dated to be near the beginning of the Hesperian near the pivotal Hesperian/Noachian transition. This is a time period on Mars that is linked to increased fluvial activity through valley network formation and also marks a transition from higher erosion rates/clay mineral formation to lower erosion rates with mineralogies dominated by sulfate minerals. Results from the Curiosity mission have shown extensive evidence for fluvial activity within the crater suggesting that sediments on the floor of the crater and even sediments making up Mt. Sharp itself were the result of longstanding activity of liquid water. Warm/wet conditions on early Mars are likely due to a thicker atmosphere and increased abundance of greenhouse gases including the main component of the atmosphere, CO2. Carbon dioxide is minor component of the Earth's atmosphere yet plays a major role in surface water chemistry, weathering, and formation of secondary minerals. An ancient martian atmosphere was likely dominated by CO2 and any waters in equilibrium with this atmosphere would have different chemical characteristics. Studies have noted that high partial pressures of CO2 would result in increased carbonic acid formation and lowering of the pH so that carbonate minerals are not stable. However, if there were a dense CO2 atmosphere present at the Hesperian/Noachian transition, it would have to be stored in a carbon reservoir on the surface or lost to space. The Mt. Sharp sediments are potentially one of the best places on Mars to investigate these CO2 reservoirs as they are proposed to have formed in the early Hesperian, from an alkaline lake, and record the transition to an aeolian dominated regime near the top of the sequence. The total amount of CO2 in the Gale crater soils and sediments is significant but lower than expected if a thick atmosphere was present at the

  10. VUV-absorption cross section of CO2 at high temperatures and impact on exoplanet atmospheres

    CERN Document Server

    Venot, Olivia; Bénilan, Yves; Gazeau, Marie-Claire; Hébrard, Eric; Larcher, Gwenaelle; Schwell, Martin; Dobrijevic, Michel; Selsis, Franck

    2015-01-01

    Ultraviolet (UV) absorption cross sections are an essential ingredient of photochemical atmosphere models. Exoplanet searches have unveiled a large population of short-period objects with hot atmospheres, very different from what we find in our solar system. Transiting exoplanets whose atmospheres can now be studied by transit spectroscopy receive extremely strong UV fluxes and have typical temperatures ranging from 400 to 2500 K. At these temperatures, UV photolysis cross section data are severely lacking. Our goal is to provide high-temperature absorption cross sections and their temperature dependency for important atmospheric compounds. This study is dedicated to CO2, which is observed and photodissociated in exoplanet atmospheres. We performed these measurements for the 115 - 200 nm range at 300, 410, 480, and 550 K. In the 195 - 230 nm range, we worked at seven temperatures between 465 and 800 K. We found that the absorption cross section of CO2 is very sensitive to temperature, especially above 160 nm....

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

    Science.gov (United States)

    Schubert, Brian A.; Jahren, A. Hope

    2012-11-01

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

  12. Soil Organic C and N Destabilization and Decline Following a Decade of Free-air CO2 Enrichment (FACE) in an Aridland Ecosystem

    Science.gov (United States)

    Strahm, B. D.; Sparks, J. P.

    2009-12-01

    Arid and semiarid environments constitute ~40% of the earth’s land surface and are expected to be particularly susceptible to global change factors. As a result, there may be dramatic shifts in the biogeochemistry of soil C and N in these systems that will have implications on productivity and long-term C sink/source dynamics. We have observed a 14-32% decrease in soil organic C and N concentrations in response to a decade of free-air CO2 enrichment (FACE) in the Mojave Desert at the Nevada Desert FACE Facility. The variability in the magnitude of change is largely driven by cover type. Soils under the dominant forms of vegetative cover, Larrea tridentata and Lycium sp. contained up to an order of magnitude more organic C and N than adjacent areas of bare ground, often colonized by biological soil crusts, and exhibited much larger shifts in the bioavailability of these pools in response to future atmospheric CO2 concentrations. Although elevated CO2 resulted in a nearly universal decrease in active cycling organic C and N (40-88%) across all cover types, a decrease of up to 28% was observed in the resistant, or slowly cycling, organic C and N pools under the dominant vegetation. Such changes suggest that predicted future atmospheric CO2 concentrations may contribute to the significant destabilization of soil organic C and N stocks in arid ecosystems, resulting in declines in productivity and negative feedbacks to rising atmospheric C concentrations.

  13. Rapid coupling of Antarctic temperature and atmospheric CO2 during deglaciation

    Directory of Open Access Journals (Sweden)

    T. D. van Ommen

    2012-02-01

    Full Text Available Antarctic ice cores provide clear evidence of a close coupling between variations in Antarctic temperature and the atmospheric concentration of CO2 during the glacial/interglacial cycles of the past 800 thousand years. Precise information on the relative timing of the temperature and CO2 changes can assist in refining our understanding of the physical processes involved in this coupling. Here, we focus on the last deglaciation, 19 000 to 11 000 years before present, during which CO2 concentrations increased by ~80 parts per million by volume and Antarctic temperature increased by ~10 °C. Utilising a recently developed proxy for regional Antarctic temperature, derived from five near-coastal ice cores, and two ice core CO2 records with high dating precision, we show that the increase in CO2 lagged the increase in regional Antarctic temperature by only 0–400 years. This new value for the lag, consistent for both CO2 records, implies a faster feedback between temperature and CO2 than the centennial to millennial-scale lags suggested by previous studies.

  14. Atmospheric CO2 fertilization effects on biomass yields of 10 crops in northern Germany

    Directory of Open Access Journals (Sweden)

    Jan F. Degener

    2015-07-01

    Full Text Available The quality and quantity of the influence that atmospheric CO2 has on cropgrowth is still a matter of debate. This study's aim is to estimate if CO2 will have an effect on biomass yields at all, to quantify and spatially locate the effects and to explore if an elevated photosynthesis rate or water-use-efficiency is predominantly responsible. This study uses a numerical carbon based crop model (BioSTAR to estimate biomass yields within theadministrative boundaries of Niedersachsen in Northern Germany. 10 crops are included (winter grains: wheat, barley,rye, triticale - early, medium, late maize variety - sunflower, sorghum, spring wheat, modeled annuallyfor the entire 21st century on 91,014 separate sites. Modeling was conducted twice, once with an annually adaptedCO2 concentration according to the SRES-A1B scenario and once with a fixed concentration of 390 ppm to separate the influence of CO2 from that of the other input variables.Rising CO2 concentrations will play a central role in keeping future yields of all crops above or aroundtoday's level. Differences in yields between modeling with fixed or adapted CO2 can be as high as60 % towards the century's end. Generally yields will increase when CO2 rises and decline whenit is kept constant. As C4-crops are equivalently affected it is presumed that anelevated efficiency in water use is the main responsible factor for all plants.

  15. CO2 Dissociation using the Versatile Atmospheric Dielectric Barrier Discharge Experiment (VADER

    Directory of Open Access Journals (Sweden)

    Michael Allen Lindon

    2014-09-01

    Full Text Available Dissociation of CO2 is investigated in an atmospheric pressure dielectric barrier discharge (DBD with a simple, zero dimensional (0-D chemical model and through experiment. The model predicts that the primary CO2 dissociation pathway within a DBD is electron impact dissociation and electron-vibrational excitation. The relaxation kinetics following dissociation are dominated by atomic oxygen chemistry. The experiments included investigating the energy efficiencies and dissociation rates of CO2 within a planar DBD, while the gas flow rate, voltage, gas composition, driving frequency, catalyst, and pulse modes were varied. Some of the VADER results include a maximum CO2 dissociation energy efficiency of 2.5 +/- 0.5%, a maximum CO$_2$ dissociation rate of 4 +/- 0.4*10^-6 mol CO2/s (5 +/- 0.5% percent dissociation, discovering that a resonant driving frequency of ~30 kHz, dependent on both applied voltage and breakdown voltage, is best for efficient CO2 dissociation and that TiO2, a photocatalyst, improved dissociation efficiencies by an average of 18% at driving frequencies above 5 kHz.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  17. Glyphosate Resistance of C3 and C4 Weeds under Rising Atmospheric CO2.

    Science.gov (United States)

    Fernando, Nimesha; Manalil, Sudheesh; Florentine, Singarayer K; Chauhan, Bhagirath S; Seneweera, Saman

    2016-01-01

    The present paper reviews current knowledge on how changes of plant metabolism under elevated CO2 concentrations (e[CO2]) can affect the development of the glyphosate resistance of C3 and C4 weeds. Among the chemical herbicides, glyphosate, which is a non-selective and post-emergence herbicide, is currently the most widely used herbicide in global agriculture. As a consequence, glyphosate resistant weeds, particularly in major field crops, are a widespread problem and are becoming a significant challenge to future global food production. Of particular interest here it is known that the biochemical processes involved in photosynthetic pathways of C3 and C4 plants are different, which may have relevance to their competitive development under changing environmental conditions. It has already been shown that plant anatomical, morphological, and physiological changes under e[CO2] can be different, based on (i) the plant's functional group, (ii) the available soil nutrients, and (iii) the governing water status. In this respect, C3 species are likely to have a major developmental advantage under a CO2 rich atmosphere, by being able to capitalize on the overall stimulatory effect of e[CO2]. For example, many tropical weed grass species fix CO2 from the atmosphere via the C4 photosynthetic pathway, which is a complex anatomical and biochemical variant of the C3 pathway. Thus, based on our current knowledge of CO2 fixing, it would appear obvious that the development of a glyphosate-resistant mechanism would be easier under an e[CO2] in C3 weeds which have a simpler photosynthetic pathway, than for C4 weeds. However, notwithstanding this logical argument, a better understanding of the biochemical, genetic, and molecular measures by which plants develop glyphosate resistance and how e[CO2] affects these measures will be important before attempting to innovate sustainable technology to manage the glyphosate-resistant evolution of weeds under e[CO2]. Such information will be of

  18. A critique of Phanerozoic climatic models involving changes in the CO 2 content of the atmosphere

    Science.gov (United States)

    Boucot, A. J.; Gray, Jane

    2001-12-01

    Critical consideration of varied Phanerozoic climatic models, and comparison of them against Phanerozoic global climatic gradients revealed by a compilation of Cambrian through Miocene climatically sensitive sediments (evaporites, coals, tillites, lateritic soils, bauxites, calcretes, etc.) suggests that the previously postulated climatic models do not satisfactorily account for the geological information. Nor do many climatic conclusions based on botanical data stand up very well when examined critically. Although this account does not deal directly with global biogeographic information, another powerful source of climatic information, we have tried to incorporate such data into our thinking wherever possible, particularly in the earlier Paleozoic. In view of the excellent correlation between CO 2 present in Antarctic ice cores, going back some hundreds of thousands of years, and global climatic gradient, one wonders whether or not the commonly postulated Phanerozoic connection between atmospheric CO 2 and global climatic gradient is more coincidence than cause and effect. Many models have been proposed that attempt to determine atmospheric composition and global temperature through geological time, particularly for the Phanerozoic or significant portions of it. Many models assume a positive correlation between atmospheric CO 2 and surface temperature, thus viewing changes in atmospheric CO 2 as playing the critical role in regulating climate/temperature, but none agree on the levels of atmospheric CO 2 through time. Prior to the relatively recent interval of time in which atmospheric CO 2 is directly measurable, a variety of biological and geological proxies have been proposed to correlate with atmospheric CO 2 level or with pCO 2/temperature. Atmospheric models may be constructed for the Pre-Cenozoic but the difficulties of assessing variables in their construction are many and complex. None of the modelers have gathered enough biological and geological data to

  19. Potential impact of rising atmospheric CO2 on quality of grains in chickpea (Cicer arietinum L.).

    Science.gov (United States)

    Saha, Saurav; Chakraborty, Debashis; Sehgal, Vinay K; Pal, Madan

    2015-11-15

    Experiments were conducted in open-top chambers to assess the effect of atmospheric CO2 enrichment (E-CO2) on the quality of grains in chickpea (Cicer arietinum L.) crop. Physical attributes of the grains was not affected, but the hydration and swelling capacities of the flour increased. Increase in carbohydrates and reduction in protein made the grains more carbonaceous (higher C:N) under E-CO2. Among other mineral nutrients, K, Ca and Zn concentrations decreased, while P, Mg, Cu, Fe, Mn and B concentrations did not change. The pH, bulk density and cooking time of chickpea flour remained unaffected, although the water absorption capacity of flour increased and oil absorption reduced. Results suggest that E-CO2 could affect the grain quality adversely and nutritional imbalance in grains of chickpea might occur.

  20. Enhanced priming of old, not new soil carbon at elevated atmospheric CO2

    DEFF Research Database (Denmark)

    Vestergard, Mette; Reinsch, Sabine; Bengtson, Per;

    2016-01-01

    accelerate the decomposition of soil organic C (SOC), a phenomenon termed ‘the priming effect’, and the priming effect is most pronounced at low soil N availability. Hence, we hypothesized that priming of SOC decomposition in response to labile C addition would increase in soil exposed to long-term elevated...... CO2 exposure. Further, we hypothesized that long-term warming would enhance SOC priming rates, whereas drought would decrease the priming response.We incubated soil from a long-term, full-factorial climate change field experiment, with the factors elevated atmospheric CO2 concentration, warming...... priming of SOC, and the priming response was higher in soil exposed to long-term elevated CO2 treatment. Drought tended to decrease the priming response, whereas long-term warming did not affect the level of priming significantly.We were also able to assess whether SOC-derived primed C in elevated CO2...

  1. Recent advances in developing COS as a tracer of Biosphere-atmosphere exchange of CO2

    Science.gov (United States)

    Asaf, D.; Stimler, K.; Yakir, D.

    2012-04-01

    Potential use of COS as tracer of CO2 flux into vegetation, based on its co-diffusion with CO2 into leaves without outflux, stimulated research on COS-CO2 interactions. Atmospheric measurements by NOAA in recent years, across a global latitudinal transect, indicated a ratio of the seasonal drawdowns in COS and CO2 (normalized to their respective ambient concentrations) of about 6. We carried out leaf-scale gas exchange measurements of COS and CO2 in 22 plant species of deciduous, evergreen trees, grasses, and shrubs, under a range of light intensities and ambient COS concentrations (using mid IR laser spectroscopy). A narrow range in the normalized ratio of the net uptake rates of COS and CO2 (termed leaf relative uptake; LRU) was observed with a mean value of 1.61±0.26. These results reflect the dominance of stomatal conductance over both COS and CO2 uptake, imposing a relatively constant ratio between the two fluxes, except under low light conditions when CO2, but not COS, metabolism is light limited. A relatively constant ratio under common ambient conditions will facilitate the application of COS as a tracer of gross photosynthesis from leaf to global scales. We also report first eddy flux measurements of COS/CO2 at the ecosystem scales. Preliminarily results indicate a ratio of the COS flux, Fcos, to net ecosystem CO2 exchange, NEE, of 3-5 (termed ecosystem relative uptake; ERU). Combining measurements of COS and CO2 and the new information on their ratios at different scales should permit the direct estimation of gross CO2 uptake, GPP, by land ecosystems according to: GPP=NEE*ERU/LRU. In addition, we show that COS effect on stomatal conductance may require a special attention. Increasing COS concentrations between 250 and 2800 pmol mol-1 (enveloping atmospheric levels) stimulate stomatal conductance. It seems likely that the stomata are responding to H2S produced in the leaves from COS.

  2. A biogenic CO2 flux adjustment scheme for the mitigation of large-scale biases in global atmospheric CO2 analyses and forecasts

    Science.gov (United States)

    Agustí-Panareda, Anna; Massart, Sébastien; Chevallier, Frédéric; Balsamo, Gianpaolo; Boussetta, Souhail; Dutra, Emanuel; Beljaars, Anton

    2016-08-01

    Forecasting atmospheric CO2 daily at the global scale with a good accuracy like it is done for the weather is a challenging task. However, it is also one of the key areas of development to bridge the gaps between weather, air quality and climate models. The challenge stems from the fact that atmospheric CO2 is largely controlled by the CO2 fluxes at the surface, which are difficult to constrain with observations. In particular, the biogenic fluxes simulated by land surface models show skill in detecting synoptic and regional-scale disturbances up to sub-seasonal time-scales, but they are subject to large seasonal and annual budget errors at global scale, usually requiring a posteriori adjustment. This paper presents a scheme to diagnose and mitigate model errors associated with biogenic fluxes within an atmospheric CO2 forecasting system. The scheme is an adaptive scaling procedure referred to as a biogenic flux adjustment scheme (BFAS), and it can be applied automatically in real time throughout the forecast. The BFAS method generally improves the continental budget of CO2 fluxes in the model by combining information from three sources: (1) retrospective fluxes estimated by a global flux inversion system, (2) land-use information, (3) simulated fluxes from the model. The method is shown to produce enhanced skill in the daily CO2 10-day forecasts without requiring continuous manual intervention. Therefore, it is particularly suitable for near-real-time CO2 analysis and forecasting systems.

  3. Comparing Global Atmospheric CO2 Flux and Transport Models with Remote Sensing (and Other) Observations

    Science.gov (United States)

    Kawa, S. R.; Collatz, G. J.; Pawson, S.; Wennberg, P. O.; Wofsy, S. C.; Andrews, A. E.

    2010-01-01

    We report recent progress derived from comparison of global CO2 flux and transport models with new remote sensing and other sources of CO2 data including those from satellite. The overall objective of this activity is to improve the process models that represent our understanding of the workings of the atmospheric carbon cycle. Model estimates of CO2 surface flux and atmospheric transport processes are required for initial constraints on inverse analyses, to connect atmospheric observations to the location of surface sources and sinks, to provide the basic framework for carbon data assimilation, and ultimately for future projections of carbon-climate interactions. Models can also be used to test consistency within and between CO2 data sets under varying geophysical states. Here we focus on simulated CO2 fluxes from terrestrial vegetation and atmospheric transport mutually constrained by analyzed meteorological fields from the Goddard Modeling and Assimilation Office for the period 2000 through 2009. Use of assimilated meteorological data enables direct model comparison to observations across a wide range of scales of variability. The biospheric fluxes are produced by the CASA model at 1x1 degrees on a monthly mean basis, modulated hourly with analyzed temperature and sunlight. Both physiological and biomass burning fluxes are derived using satellite observations of vegetation, burned area (as in GFED-3), and analyzed meteorology. For the purposes of comparison to CO2 data, fossil fuel and ocean fluxes are also included in the transport simulations. In this presentation we evaluate the model's ability to simulate CO2 flux and mixing ratio variability in comparison to remote sensing observations from TCCON, GOSAT, and AIRS as well as relevant in situ observations. Examples of the influence of key process representations are shown from both forward and inverse model comparisons. We find that the model can resolve much of the synoptic, seasonal, and interannual

  4. Soil organic carbon dust emission: an omitted global source of atmospheric CO2.

    Science.gov (United States)

    Chappell, Adrian; Webb, Nicholas P; Butler, Harry J; Strong, Craig L; McTainsh, Grant H; Leys, John F; Viscarra Rossel, Raphael A

    2013-10-01

    Soil erosion redistributes soil organic carbon (SOC) within terrestrial ecosystems, to the atmosphere and oceans. Dust export is an essential component of the carbon (C) and carbon dioxide (CO(2)) budget because wind erosion contributes to the C cycle by removing selectively SOC from vast areas and transporting C dust quickly offshore; augmenting the net loss of C from terrestrial systems. However, the contribution of wind erosion to rates of C release and sequestration is poorly understood. Here, we describe how SOC dust emission is omitted from national C accounting, is an underestimated source of CO(2) and may accelerate SOC decomposition. Similarly, long dust residence times in the unshielded atmospheric environment may considerably increase CO(2) emission. We developed a first approximation to SOC enrichment for a well-established dust emission model and quantified SOC dust emission for Australia (5.83 Tg CO(2)-e yr(-1)) and Australian agricultural soils (0.4 Tg CO(2)-e yr(-1)). These amount to underestimates for CO(2) emissions of ≈10% from combined C pools in Australia (year = 2000), ≈5% from Australian Rangelands and ≈3% of Australian Agricultural Soils by Kyoto Accounting. Northern hemisphere countries with greater dust emission than Australia are also likely to have much larger SOC dust emission. Therefore, omission of SOC dust emission likely represents a considerable underestimate from those nations' C accounts. We suggest that the omission of SOC dust emission from C cycling and C accounting is a significant global source of uncertainty. Tracing the fate of wind-eroded SOC in the dust cycle is therefore essential to quantify the release of CO(2) from SOC dust to the atmosphere and the contribution of SOC deposition to downwind C sinks.

  5. Glacial atmospheric CO2 decline in association with decrease of marine sedimentary phosphorus

    Institute of Scientific and Technical Information of China (English)

    WENG; Huanxin; ZHANG; Xingmao; WU; Nengyou; WANG; Ying; CHEN; Lihong; ZHONG; Hexian; QIN; Yachao

    2006-01-01

    The environmental and biogeochemical information extracted from the sediments collected from the northern shelf of the South China Sea shows that terrigenous inputs of phosphorus into the sea remained relatively constant, and the variation of phosphorus contents at different depths was caused by climatic and environmental changes. The findings also suggest that the vertical variation of phosphorus content was opposite to those of calcium carbonate and cadmium, and the functional correlation between CO2 and PO43? in seawater was given by calculating the chemical equilibrium, indicating that the accumulation of marine sedimentary phosphorus may have something to do with the variation of atmospheric CO2. The decreased phosphorus accumulation as well as the correspondingly-increased calcium carbonate content might be one of key factors causing glacial atmospheric CO2 decline.

  6. Recharge of the early atmosphere of Mars by impact-induced release of CO2

    Science.gov (United States)

    Carr, Michael H.

    1989-01-01

    The question as to whether high impact rates early in the history of Mars could have aided in maintaining a relatively thick CO2 atmosphere is discussed. Such impacts could have released CO2 into the atmosphere by burial, by shock-induced release during impact events, and by the addition of carbon to Mars from the impacting bolides. On the assumption that cratering rates on Mars were comparable to those of the moon's Nectarial period, burial rates are a result of 'impact gardening' at the end of heavy bombardment are estimated to have ranged from 20 to 45 m/million years; at these rates, 0.1-0.2 bar of CO2 would have been released every 10 million years as a result of burial to depths at which carbonate dissociation temperatures are encountered.

  7. Atmospheric pCO2 Reconstructed across the Early Eocene Hyperthermals

    Science.gov (United States)

    Cui, Y.; Schubert, B.

    2015-12-01

    Negative carbon isotope excursions (CIEs) are commonly associated with extreme global warming. The Early Eocene is punctuated by five such CIEs, the Paleocene-Eocene thermal maximum (PETM, ca. 55.8 Ma), H1 (ca. 53.6 Ma), H2 (ca. 53.5 Ma), I1 (ca. 53.3 Ma), and I2 (ca. 53.2 Ma), each characterized by global warming. The negative CIEs are recognized in both marine and terrestrial substrates, but the terrestrial substrates exhibit a larger absolute magnitude CIE than the marine substrates. Here we reconcile the difference in CIE magnitude between the terrestrial and marine substrates for each of these events by accounting for the additional carbon isotope fractionation by C3 land plants in response to increased atmospheric pCO2. Our analysis yields background and peak pCO2 values for each of the events. Assuming a common mechanism for each event, we calculate that background pCO2 was not static across the Early Eocene, with the highest background pCO2 immediately prior to I2, the last of the five CIEs. Background pCO2 is dependent on the source used in our analysis with values ranging from 300 to 720 ppmv provided an injection of 13C-depleted carbon with δ13C value of -60‰ (e.g. biogenic methane). The peak pCO2 during each event scales according to the magnitude of CIE, and is therefore greatest during the PETM and smallest during H2. Both background and peak pCO2 are higher if we assume a mechanism of permafrost thawing (δ13C = -25‰). Our reconstruction of pCO2 across these events is consistent with trends in the δ18O value of deep-sea benthic foraminifera, suggesting a strong link between pCO2 and temperature during the Early Eocene.

  8. Mechanisms for synoptic variations of atmospheric CO2 in North America, South America and Europe

    Directory of Open Access Journals (Sweden)

    I. T. Baker

    2008-12-01

    Full Text Available Synoptic variations of atmospheric CO2 produced by interactions between weather and surface fluxes are investigated mechanistically and quantitatively in midlatitude and tropical regions using continuous in-situ CO2 observations in North America, South America and Europe and forward chemical transport model simulations with the Parameterized Chemistry Transport Model. Frontal CO2 climatologies show consistently strong, characteristic frontal CO2 signals throughout the midlatitudes of North America and Europe. Transitions between synoptically identifiable CO2 air masses or transient spikes along the frontal boundary typically characterize these signals. One case study of a summer cold front shows CO2 gradients organizing with deformational flow along weather fronts, producing strong and spatially coherent variations. In order to differentiate physical and biological controls on synoptic variations in midlatitudes and a site in Amazonia, a boundary layer budget equation is constructed to break down boundary layer CO2 tendencies into components driven by advection, moist convection, and surface fluxes. This analysis suggests that, in midlatitudes, advection is dominant throughout the year and responsible for 60–70% of day-to-day variations on average, with moist convection contributing less than 5%. At a site in Amazonia, vertical mixing, in particular coupling between convective transport and surface CO2 flux, is most important, with advection responsible for 26% of variations, moist convection 32% and surface flux 42%. Transport model sensitivity experiments agree with budget analysis. These results imply the existence of a recharge-discharge mechanism in Amazonia important for controlling synoptic variations of boundary layer CO2, and that forward and inverse simulations should take care to represent moist convective transport. Due to the scarcity of tropical observations at the time of this study, results in Amazonia are not generalized for

  9. Effect of CO2 on Atmospheric Corrosion of UNS G10190 Steel under Thin Electrolyte Film

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The atmospheric corrosion of UNS G10190 steel under a thin electrolyte film in the atmosphere polluted by CO2 has been studied in the lab using an atmospheric corrosion monitor(ACM) in combination with XRD and SEM observations of the surface of steel. The ACM study indicated that the corrosion rate of the steel increased with increasing carbon dioxide concentration. The XRD and SEM observations showed that no carbonate was found in the corrosion product on the steel surface. The corrosion product consisted of two layers, i. e., inner and outer layer. From the experimental results, it was concluded that CO2 played an enhancing role in the atmospheric corrosion of UNS G10190 steel. The film of the corrosion product showed slight protection.

  10. Response of microbial extracellular enzyme activities and r- vs. K- selected microorganisms to elevated atmospheric CO2 depends on soil aggregate size

    Science.gov (United States)

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

    2014-05-01

    Increased belowground carbon (C) transfer by plant roots under elevated atmospheric CO2 and the contrasting environment in soil macro- and microaggregates could affect properties of the microbial community in the rhizosphere. We evaluated the effect of 5 years of elevated CO2 (550 ppm) on four extracellular enzymes: ß-glucosidase, chitinase, phosphatase, and sulfatase along with the contribution of fast- (r-strategists) and slow-growing microorganisms (K-strategists) in soil aggregates. We fractionated the bulk soil from the ambient and elevated CO2 treatments of FACE-Hohenheim (Stuttgart) into large macro- (>2 mm), small macro- (0.25-2.00 mm), and microaggregates (soil and aggregates amended with glucose and nutrients. In the bulk soil and isolated aggregates before and after activation with glucose, the actual and the potential enzyme activities were measured. Although C-org and C-mic as well as the activities of ß-glucosidase, phosphatase, and sulfatase were unaffected in bulk soil and in aggregate-size classes by elevated CO2, significant changes were observed in potential enzyme production after substrate amendment. After adding glucose, enzyme activities under elevated CO2 were 1.2-1.9-fold higher than under ambient CO2. In addition, µ values were significantly higher under elevated than ambient CO2 for bulk soil, small macroaggregates, and microaggregates. Based on changes in µ, GMB, and lag-period, we conclude that elevated atmospheric CO2 stimulated the r-selected microorganisms, especially in soil microaggregates. In contrast, significantly higher chitinase activity in bulk soil and in large macroaggregates under elevated CO2 revealed an increased contribution of fungi to turnover processes. We conclude that quantitative and qualitative changes of C input by plants into the soil at elevated CO2 affect microbial community functioning, but not its total content. An increase in r-selected microorganisms could accelerate C turnover in terrestrial

  11. Stabilization of CO2 Atmospheres on Exoplanets around M Dwarf Stars

    CERN Document Server

    Gao, Peter; Robinson, Tyler D; Li, Cheng; Yung, Yuk L

    2015-01-01

    We investigate the chemical stability of CO2-dominated atmospheres of M dwarf terrestrial exoplanets using a 1-dimensional photochemical model. On planets orbiting Sun-like stars, the photolysis of CO2 by Far-UV (FUV) radiation is balanced by the reaction between CO and OH, the rate of which depends on H2O abundance. By comparison, planets orbiting M dwarf stars experience higher FUV radiation compared to planets orbiting Sun-like stars, and they are also likely to have low H2O abundance due to M dwarfs having a prolonged, high-luminosity pre-main sequence (Luger & Barnes 2015). We show that, for H2O-depleted planets around M dwarfs, a CO2-dominated atmosphere is stable to conversion to CO and O2 by relying on a catalytic cycle involving H2O2 photolysis. However, this cycle breaks down for planets with atmospheric hydrogen mixing ratios below ~1 ppm, resulting in ~40% of the atmospheric CO2 being converted to CO and O2 on a time scale of 1 Myr. The increased abundance of O2 also results in high O3 concent...

  12. Antarctic ice sheet sensitivity to atmospheric CO2 variations in the early to mid-Miocene.

    Science.gov (United States)

    Levy, Richard; Harwood, David; Florindo, Fabio; Sangiorgi, Francesca; Tripati, Robert; von Eynatten, Hilmar; Gasson, Edward; Kuhn, Gerhard; Tripati, Aradhna; DeConto, Robert; Fielding, Christopher; Field, Brad; Golledge, Nicholas; McKay, Robert; Naish, Timothy; Olney, Matthew; Pollard, David; Schouten, Stefan; Talarico, Franco; Warny, Sophie; Willmott, Veronica; Acton, Gary; Panter, Kurt; Paulsen, Timothy; Taviani, Marco

    2016-03-29

    Geological records from the Antarctic margin offer direct evidence of environmental variability at high southern latitudes and provide insight regarding ice sheet sensitivity to past climate change. The early to mid-Miocene (23-14 Mya) is a compelling interval to study as global temperatures and atmospheric CO2 concentrations were similar to those projected for coming centuries. Importantly, this time interval includes the Miocene Climatic Optimum, a period of global warmth during which average surface temperatures were 3-4 °C higher than today. Miocene sediments in the ANDRILL-2A drill core from the Western Ross Sea, Antarctica, indicate that the Antarctic ice sheet (AIS) was highly variable through this key time interval. A multiproxy dataset derived from the core identifies four distinct environmental motifs based on changes in sedimentary facies, fossil assemblages, geochemistry, and paleotemperature. Four major disconformities in the drill core coincide with regional seismic discontinuities and reflect transient expansion of grounded ice across the Ross Sea. They correlate with major positive shifts in benthic oxygen isotope records and generally coincide with intervals when atmospheric CO2 concentrations were at or below preindustrial levels (∼280 ppm). Five intervals reflect ice sheet minima and air temperatures warm enough for substantial ice mass loss during episodes of high (∼500 ppm) atmospheric CO2 These new drill core data and associated ice sheet modeling experiments indicate that polar climate and the AIS were highly sensitive to relatively small changes in atmospheric CO2 during the early to mid-Miocene.

  13. N2O influence on isotopic measurements of atmospheric CO2

    NARCIS (Netherlands)

    Sirignano, C; Neubert, REM; Meijer, HAJ

    2004-01-01

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

  14. Prebiotic synthesis in atmospheres containing CH4, CO, and CO2. I - Amino acids

    Science.gov (United States)

    Schlesinger, G.; Miller, S. L.

    1983-01-01

    The prebiotic synthesis of amino acids, HCN, H2CO, and NH3 using a spark discharge on various simulated primitive earth atmospheres at 25 C is investigated. Various mixtures of CH4, CO, CO2, N2, NH3, H2O, and H2 were utilized in different experiments. The yields of amino acids (1.2-4.7 percent based on the carbon) are found to be approximately independent of the H2/CH4 ratio and the presence of NH3, and a wide variety of amino acids are obtained. Glycine is found to be almost the only amino acid produced from CO and CO2 model atmospheres, with the maximum yield being about the same for the three carbon sources at high H2/carbon ratios,whereas CH4 is superior at low H2/carbon ratios. In addition, it is found that the directly synthesized NH3 together with the NH3 obtained from the hydrolysis of HCN, nitriles, and urea could have been a major source of ammonia in the atmosphere and oceans of the primitive earth. It is determined that prebiotic syntheses from HCN and H2CO to give products such as purines and sugars and some amino acids could have occurred in primitive atmospheres containing CO and CO2 provided the H2/CO and H2/CO2 ratios were greater than about 1.0.

  15. Soil type influences the sensitivity of nutrient dynamics to changes in atmospheric CO2

    Science.gov (United States)

    Numerous studies have indicated that increases in atmospheric CO2 have the potential to decrease nitrogen availability through the process of progressive nitrogen limitation (PNL). The timing and magnitude of PNL in field experiments is varied due to numerous ecosystem processes. Here we examined ...

  16. On the repetitive operation of a self-switched transversely excited atmosphere CO2 laser

    Indian Academy of Sciences (India)

    Pallavi Raote; Gautam Patil; J Padma Nilaya; D J Biswas

    2010-11-01

    The repetition rate capability of self-switched transversely excited atmosphere (TEA) CO2 laser was studied for different gas flow configurations. For an optimized gas flow configuration, repetitive operation was achieved at a much smaller gas replenishment factor between two successive pulses when compared with repetitive systems energized by conventional pulsers.

  17. Antarctic ice sheet sensitivity to atmospheric CO2 variations in the early to mid-Miocene

    Science.gov (United States)

    Levy, Richard; Harwood, David; Florindo, Fabio; Sangiorgi, Francesca; Tripati, Robert; von Eynatten, Hilmar; Gasson, Edward; Kuhn, Gerhard; Tripati, Aradhna; DeConto, Robert; Fielding, Christopher; Field, Brad; Golledge, Nicholas; McKay, Robert; Naish, Timothy; Olney, Matthew; Pollard, David; Schouten, Stefan; Talarico, Franco; Warny, Sophie; Willmott, Veronica; Acton, Gary; Panter, Kurt; Paulsen, Timothy; Taviani, Marco; SMS Science Team; Acton, Gary; Askin, Rosemary; Atkins, Clifford; Bassett, Kari; Beu, Alan; Blackstone, Brian; Browne, Gregory; Ceregato, Alessandro; Cody, Rosemary; Cornamusini, Gianluca; Corrado, Sveva; DeConto, Robert; Del Carlo, Paola; Di Vincenzo, Gianfranco; Dunbar, Gavin; Falk, Candice; Field, Brad; Fielding, Christopher; Florindo, Fabio; Frank, Tracy; Giorgetti, Giovanna; Grelle, Thomas; Gui, Zi; Handwerger, David; Hannah, Michael; Harwood, David M.; Hauptvogel, Dan; Hayden, Travis; Henrys, Stuart; Hoffmann, Stefan; Iacoviello, Francesco; Ishman, Scott; Jarrard, Richard; Johnson, Katherine; Jovane, Luigi; Judge, Shelley; Kominz, Michelle; Konfirst, Matthew; Krissek, Lawrence; Kuhn, Gerhard; Lacy, Laura; Levy, Richard; Maffioli, Paola; Magens, Diana; Marcano, Maria C.; Millan, Cristina; Mohr, Barbara; Montone, Paola; Mukasa, Samuel; Naish, Timothy; Niessen, Frank; Ohneiser, Christian; Olney, Mathew; Panter, Kurt; Passchier, Sandra; Patterson, Molly; Paulsen, Timothy; Pekar, Stephen; Pierdominici, Simona; Pollard, David; Raine, Ian; Reed, Joshua; Reichelt, Lucia; Riesselman, Christina; Rocchi, Sergio; Sagnotti, Leonardo; Sandroni, Sonia; Sangiorgi, Francesca; Schmitt, Douglas; Speece, Marvin; Storey, Bryan; Strada, Eleonora; Talarico, Franco; Taviani, Marco; Tuzzi, Eva; Verosub, Kenneth; von Eynatten, Hilmar; Warny, Sophie; Wilson, Gary; Wilson, Terry; Wonik, Thomas; Zattin, Massimiliano

    2016-03-01

    Geological records from the Antarctic margin offer direct evidence of environmental variability at high southern latitudes and provide insight regarding ice sheet sensitivity to past climate change. The early to mid-Miocene (23-14 Mya) is a compelling interval to study as global temperatures and atmospheric CO2 concentrations were similar to those projected for coming centuries. Importantly, this time interval includes the Miocene Climatic Optimum, a period of global warmth during which average surface temperatures were 3-4 °C higher than today. Miocene sediments in the ANDRILL-2A drill core from the Western Ross Sea, Antarctica, indicate that the Antarctic ice sheet (AIS) was highly variable through this key time interval. A multiproxy dataset derived from the core identifies four distinct environmental motifs based on changes in sedimentary facies, fossil assemblages, geochemistry, and paleotemperature. Four major disconformities in the drill core coincide with regional seismic discontinuities and reflect transient expansion of grounded ice across the Ross Sea. They correlate with major positive shifts in benthic oxygen isotope records and generally coincide with intervals when atmospheric CO2 concentrations were at or below preindustrial levels (˜280 ppm). Five intervals reflect ice sheet minima and air temperatures warm enough for substantial ice mass loss during episodes of high (˜500 ppm) atmospheric CO2. These new drill core data and associated ice sheet modeling experiments indicate that polar climate and the AIS were highly sensitive to relatively small changes in atmospheric CO2 during the early to mid-Miocene.

  18. Airborne 2-Micron Double Pulsed Direct Detection IPDA Lidar for Atmospheric CO2 Measurement

    Science.gov (United States)

    Yu, Jirong; Petros, Mulugeta; Refaat, Tamer F.; Reithmaier, Karl; Remus, Ruben; Singh, Upendra; Johnson, Will; Boyer, Charlie; Fay, James; Johnston, Susan; Murchison, Luke

    2015-01-01

    An airborne 2-micron double-pulsed Integrated Path Differential Absorption (IPDA) lidar has been developed for atmospheric CO2 measurements. This new 2-miron pulsed IPDA lidar has been flown in spring of 2014 for total ten flights with 27 flight hours. It provides high precision measurement capability by unambiguously eliminating contamination from aerosols and clouds that can bias the IPDA measurement.

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

    DEFF Research Database (Denmark)

    Saxe, Henrik; Hamelin, Lorie; Hinrichsen, Torben

    2014-01-01

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

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

    DEFF Research Database (Denmark)

    Saxe, Henrik; Hamelin, Lorie; Hinrichsen, Torben

    2014-01-01

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

  1. Rates of consumption of atmospheric CO2 through the weathering of loess during the next 100 yr of climate change

    Directory of Open Access Journals (Sweden)

    D. Pollard

    2012-08-01

    lysocline expected in the oceans with increasing atmospheric CO2, we predict an acceleration of the lysocline deepening in soils in the central area of the Mississippi Valley, but a slowdown of its deepening in the Southern and Northern section. This result illustrates the complex behavior of carbonate weathering facing short term global climate change. Predicting the global response of terrestrial weathering to increased atmospheric CO2 and temperature in the future will mostly depend upon our ability to make precise assessments of which areas of the globe increase or decrease in precipitation and soil drainage.

  2. Glacial-Interglacial Atmospheric CO2 Change--The Glacial Burial Hypothesis

    Institute of Scientific and Technical Information of China (English)

    Ning ZENG

    2003-01-01

    Organic carbon buried under the great ice sheets of the Northern Hemisphere is suggested to bethe missing link in the atmospheric CO2 change over the glacial-interglacial cycles. At glaciation, theadvancement of continental ice sheets buries vegetation and soil carbon accumulated during warmer pe-riods. At deglaciation, this burial carbon is released back into the atmosphere. In a simulation over twoglacial-interglacial cycles using a synchronously coupled atmosphere-land-ocean carbon model forced byreconstructed climate change, it is found that there is a 547-Gt terrestrial carbon release from glacialmaximum to interglacial, resulting in a 60-Gt (about 30-ppmv) increase in the atmospheric CO2, with theremainder absorbed by the ocean in a scenario in which ocean acts as a passive buffer. This is in contrastto previous estimates of a land uptake at deglaciation. This carbon source originates from glacial burial,continental shelf, and other land areas in response to changes in ice cover, sea level, and climate. The inputof light isotope enriched terrestrial carbon causes atmospheric 513C to drop by about 0.3% at deglaciation,followed by a rapid rise towards a high interglacial value in response to oceanic warming and regrowthon land. Together with other ocean based mechanisms such as change in ocean temperature, the glacialburial hypothesis may offer a full explanation of the observed 80 100-ppmv atmospheric CO2 change.

  3. Temporal variations of atmospheric CO2 and CO at Ahmedabad in western India

    Science.gov (United States)

    Chandra, Naveen; Lal, Shyam; Venkataramani, S.; Patra, Prabir K.; Sheel, Varun

    2016-05-01

    About 70 % of the anthropogenic carbon dioxide (CO2) is emitted from the megacities and urban areas of the world. In order to draw effective emission mitigation policies for combating future climate change as well as independently validating the emission inventories for constraining their large range of uncertainties, especially over major metropolitan areas of developing countries, there is an urgent need for greenhouse gas measurements over representative urban regions. India is a fast developing country, where fossil fuel emissions have increased dramatically in the last three decades and are predicted to continue to grow further by at least 6 % per year through to 2025. The CO2 measurements over urban regions in India are lacking. To overcome this limitation, simultaneous measurements of CO2 and carbon monoxide (CO) have been made at Ahmedabad, a major urban site in western India, using a state-of-the-art laser-based cavity ring down spectroscopy technique from November 2013 to May 2015. These measurements enable us to understand the diurnal and seasonal variations in atmospheric CO2 with respect to its sources (both anthropogenic and biospheric) and biospheric sinks. The observed annual average concentrations of CO2 and CO are 413.0 ± 13.7 and 0.50 ± 0.37 ppm respectively. Both CO2 and CO show strong seasonality with lower concentrations (400.3 ± 6.8 and 0.19 ± 0.13 ppm) during the south-west monsoon and higher concentrations (419.6 ± 22.8 and 0.72 ± 0.68 ppm) during the autumn (SON) season. Strong diurnal variations are also observed for both the species. The common factors for the diurnal cycles of CO2 and CO are vertical mixing and rush hour traffic, while the influence of biospheric fluxes is also seen in the CO2 diurnal cycle. Using CO and CO2 covariation, we differentiate the anthropogenic and biospheric components of CO2 and found significant contributions of biospheric respiration and anthropogenic emissions in the late night (00:00-05:00 h, IST

  4. Δ(14)CO2 from dark respiration in plants and its impact on the estimation of atmospheric fossil fuel CO2.

    Science.gov (United States)

    Xiong, Xiaohu; Zhou, Weijian; Cheng, Peng; Wu, Shugang; Niu, Zhenchuan; Du, Hua; Lu, Xuefeng; Fu, Yunchong; Burr, George S

    2017-04-01

    Radiocarbon ((14)C) has been widely used for quantification of fossil fuel CO2 (CO2ff) in the atmosphere and for ecosystem source partitioning studies. The strength of the technique lies in the intrinsic differences between the (14)C signature of fossil fuels and other sources. In past studies, the (14)C content of CO2 derived from plants has been equated with the (14)C content of the atmosphere. Carbon isotopic fractionation mechanisms vary among plants however, and experimental study on fractionation associated with dark respiration is lacking. Here we present accelerator mass spectrometry (AMS) radiocarbon results of CO2 respired from 21 plants using a lab-incubation method and associated bulk organic matter. From the respired CO2 we determine Δ(14)Cres values, and from the bulk organic matter we determine Δ(14)Cbom values. A significant difference between Δ(14)Cres and Δ(14)Cbom (P < 0.01) was observed for all investigated plants, ranging from -42.3‰ to 10.1‰. The results show that Δ(14)Cres values are in agreement with mean atmospheric Δ(14)CO2 for several days leading up to the sampling date, but are significantly different from corresponding bulk organic Δ(14)C values. We find that although dark respiration is unlikely to significantly influence the estimation of CO2ff, an additional bias associated with the respiration rate during a plant's growth period should be considered when using Δ(14)C in plants to quantify atmospheric CO2ff.

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

    Science.gov (United States)

    Goessling, Helge F.; Bathiany, Sebastian

    2016-08-01

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

  6. Atmospheric radon, CO2 and CH4 dynamics in an Australian coal seam gas field

    Science.gov (United States)

    Tait, D. R.; Santos, I. R.; Maher, D. T.

    2013-12-01

    Atmospheric radon (222Rn), carbon dioxide (CO2), and methane concentrations (CH4) as well as carbon stable isotope ratios (δ13C) were used to gain insight into atmospheric chemistry within an Australian coal seam gas (CSG) field (Surat Basin, Tara region, Queensland). A˜3 fold increase in maximum 222Rn concentration was observed inside the gas field compared to outside of it. There was a significant relationship between maximum and average 222Rn concentrations and the number of gas wells within a 2 km to 4 km radius of the sampling sites (n = 5 stations; p gas field related to point sources (well heads, pipelines, etc.) and diffse soil sources due to changes in the soil structural and hydrological characteristics. A rapid qualitative assessment of CH4 and CO2 concentration, and carbon isotopes using a mobile cavity ring-down spectrometer system showed a widespread enrichment of both CH4 and CO2 within the production gas field. Concentrations of CH4 and CO2 were as high as 6.89 ppm and 541 ppm respectively compared average concentrations of 1.78 ppm (CH4) and 388 ppm (CO2) outside the gas field. The δ13C values showed distinct differences between areas inside and outside the production field with the δ13C value of the CH4 source within the field matching that of the methane in the CSG.

  7. Potential effects of elevated atmospheric carbon dioxide (CO2) on coastal wetlands

    Science.gov (United States)

    McKee, Karen

    2006-01-01

    Carbon dioxide (CO2) concentration in the atmosphere has steadily increased from 280 parts per million (ppm) in preindustrial times to 381 ppm today and is predicted by some models to double within the next century. Some of the important pathways whereby changes in atmospheric CO2 may impact coastal wetlands include changes in temperature, rainfall, and hurricane intensity (fig. 1). Increases in CO2 can contribute to global warming, which may (1) accelerate sea-level rise through melting of polar ice fields and steric expansion of oceans, (2) alter rainfall patterns and salinity regimes, and (3) change the intensity and frequency of tropical storms and hurricanes. Sea-level rise combined with changes in storm activity may affect erosion and sedimentation rates and patterns in coastal wetlands and maintenance of soil elevations.Feedback loops between plant growth and hydroedaphic conditions also contribute to maintenance of marsh elevations through accumulation of organic matter. Although increasing CO2 concentration may contribute to global warming and climate changes, it may also have a direct impact on plant growth and development by stimulating photosynthesis or improving water use efficiency. Scientists with the U.S. Geological Survey are examining responses of wetland plants to elevated CO2 concentration and other factors. This research will lead to a better understanding of future changes in marsh species composition, successional rates and patterns, ecological functioning, and vulnerability to sea-level rise and other global change factors.

  8. [Open-path online monitoring of ambient atmospheric CO2 based on laser absorption spectrum].

    Science.gov (United States)

    He, Ying; Zhang, Yu-Jun; Kan, Rui-Feng; Xia, Hui; Geng, Hui; Ruan, Jun; Wang, Min; Cui, Xiao-Juan; Liu, Wen-Qing

    2009-01-01

    With the conjunction of tunable diode laser absorption spectroscopy technology (TDLAS) and the open long optical path technology, the system designing scheme of CO2 on-line monitoring based on near infrared tunable diode laser absorption spectroscopy technology was discussed in detail, and the instrument for large-range measurement was set up. By choosing the infrared absorption line of CO2 at 1.57 microm whose line strength is strong and suitable for measurement, the ambient atmospheric CO2 was measured continuously with a 30 s temporal resolution at an suburb site in the autumn of 2007. The diurnal atmospheric variations of CO2 and continuous monitoring results were presented. The results show that the variation in CO2 concentration has an obvious diurnal periodicity in suburb where the air is free of interference and contamination. The general characteristic of diurnal variation is that the concentration is low in the daytime and high at night, so it matches the photosynthesis trend. The instrument can detect gas concentration online with high resolution, high sensitivity, high precision, short response time and many other advantages, the monitoring requires no gas sampling, the calibration is easy, and the detection limit is about 4.2 x 10(-7). It has been proved that the system and measurement project are feasible, so it is an effective method for gas flux continuous online monitoring of large range in ecosystem based on TDLAS technology.

  9. Persistent stimulation of photosynthesis in short rotation coppice mulberry under elevated CO2 atmosphere.

    Science.gov (United States)

    Madhana Sekhar, Kalva; Rachapudi, Venkata Sreeharsha; Mudalkar, Shalini; Reddy, Attipalli Ramachandra

    2014-08-01

    Current study was undertaken to elucidate the responses of short rotation coppice (SRC) mulberry under elevated CO2 atmosphere (550μmolmol(-1)). Throughout the experimental period, elevated CO2 grown mulberry plants showed significant increase in light saturated photosynthetic rates (A') by increasing intercellular CO2 concentrations (Ci) despite reduced stomatal conductance (gs). Reduced gs was linked to decrease in transpiration (E) resulting in improved water use efficiency (WUE). There was a significant increase in carboxylation efficiency (CE) of Rubisco, apparent quantum efficiency (AQE), light and CO2 saturated photosynthetic rates (AMAX), photosynthetic nitrogen use efficiency (PNUE), chlorophyll a fluorescence characteristics (FV/FM and PIABS), starch and other carbohydrates in high CO2 grown plants which clearly demonstrate no photosynthetic acclimation in turn resulted marked increase in above and below ground biomass. Our results strongly suggest that short rotation forestry (<1year) with mulberry plantations should be effective to mitigate raising CO2 levels as well as for the production of renewable bio-energy.

  10. High Materials Performance in Supercritical CO2 in Comparison with Atmospheric Pressure CO2 and Supercritical Steam

    Energy Technology Data Exchange (ETDEWEB)

    Holcomb, Gordon [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Tylczak, Joseph [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Carney, Casey [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Dogan, Omer N. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)

    2017-02-26

    This presentation covers environments (including advanced ultra-supercritical (A-USC) steam boiler/turbine and sCO2 indirect power cycle), effects of pressure, exposure tests, oxidation results, and mechanical behavior after exposure.

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

    Directory of Open Access Journals (Sweden)

    J. W. C. White

    2011-05-01

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

  12. Does Size Matter? Atmospheric CO2 May Be a Stronger Driver of Stomatal Closing Rate Than Stomatal Size in Taxa That Diversified under Low CO2

    Science.gov (United States)

    Elliott-Kingston, Caroline; Haworth, Matthew; Yearsley, Jon M.; Batke, Sven P.; Lawson, Tracy; McElwain, Jennifer C.

    2016-01-01

    One strategy for plants to optimize stomatal function is to open and close their stomata quickly in response to environmental signals. It is generally assumed that small stomata can alter aperture faster than large stomata. We tested the hypothesis that species with small stomata close faster than species with larger stomata in response to darkness by comparing rate of stomatal closure across an evolutionary range of species including ferns, cycads, conifers, and angiosperms under controlled ambient conditions (380 ppm CO2; 20.9% O2). The two species with fastest half-closure time and the two species with slowest half-closure time had large stomata while the remaining three species had small stomata, implying that closing rate was not correlated with stomatal size in these species. Neither was response time correlated with stomatal density, phylogeny, functional group, or life strategy. Our results suggest that past atmospheric CO2 concentration during time of taxa diversification may influence stomatal response time. We show that species which last diversified under low or declining atmospheric CO2 concentration close stomata faster than species that last diversified in a high CO2 world. Low atmospheric [CO2] during taxa diversification may have placed a selection pressure on plants to accelerate stomatal closing to maintain adequate internal CO2 and optimize water use efficiency. PMID:27605929

  13. North America's net terrestrial CO2 exchange with the atmosphere 1990-2009

    Science.gov (United States)

    King, A. W.; Andres, R. J.; Davis, K. J.; Hafer, M.; Hayes, D. J.; Huntzinger, D. N.; de Jong, B.; Kurz, W. A.; McGuire, A. D.; Vargas, R.; Wei, Y.; West, T. O.; Woodall, C. W.

    2015-01-01

    Scientific understanding of the global carbon cycle is required for developing national and international policy to mitigate fossil fuel CO2 emissions by managing terrestrial carbon uptake. Toward that understanding and as a contribution to the REgional Carbon Cycle Assessment and Processes (RECCAP) project, this paper provides a synthesis of net land-atmosphere CO2 exchange for North America (Canada, United States, and Mexico) over the period 1990-2009. Only CO2 is considered, not methane or other greenhouse gases. This synthesis is based on results from three different methods: atmospheric inversion, inventory-based methods and terrestrial biosphere modeling. All methods indicate that the North American land surface was a sink for atmospheric CO2, with a net transfer from atmosphere to land. Estimates ranged from -890 to -280 Tg C yr-1, where the mean of atmospheric inversion estimates forms the lower bound of that range (a larger land sink) and the inventory-based estimate using the production approach the upper (a smaller land sink). This relatively large range is due in part to differences in how the approaches represent trade, fire and other disturbances and which ecosystems they include. Integrating across estimates, "best" estimates (i.e., measures of central tendency) are -472 ± 281 Tg C yr-1 based on the mean and standard deviation of the distribution and -360 Tg C yr-1 (with an interquartile range of -496 to -337) based on the median. Considering both the fossil fuel emissions source and the land sink, our analysis shows that North America was, however, a net contributor to the growth of CO2 in the atmosphere in the late 20th and early 21st century. With North America's mean annual fossil fuel CO2 emissions for the period 1990-2009 equal to 1720 Tg C yr-1 and assuming the estimate of -472 Tg C yr-1 as an approximation of the true terrestrial CO2 sink, the continent's source : sink ratio for this time period was 1720:472, or nearly 4:1.

  14. North America's net terrestrial CO2 exchange with the atmosphere 1990–2009

    Science.gov (United States)

    King, A.W.; Andres, R.J.; Davis, K.J.; Hafer, M.; Hayes, D.J.; Huntzinger, Deborah N.; de Jong, Bernardus; Kurz, W.A.; McGuire, Anthony; Vargas, Rodrigo I.; Wei, Y.; West, Tristram O.; Woodall, Christopher W.

    2015-01-01

    Scientific understanding of the global carbon cycle is required for developing national and international policy to mitigate fossil fuel CO2 emissions by managing terrestrial carbon uptake. Toward that understanding and as a contribution to the REgional Carbon Cycle Assessment and Processes (RECCAP) project, this paper provides a synthesis of net land–atmosphere CO2 exchange for North America (Canada, United States, and Mexico) over the period 1990–2009. Only CO2 is considered, not methane or other greenhouse gases. This synthesis is based on results from three different methods: atmospheric inversion, inventory-based methods and terrestrial biosphere modeling. All methods indicate that the North American land surface was a sink for atmospheric CO2, with a net transfer from atmosphere to land. Estimates ranged from −890 to −280 Tg C yr−1, where the mean of atmospheric inversion estimates forms the lower bound of that range (a larger land sink) and the inventory-based estimate using the production approach the upper (a smaller land sink). This relatively large range is due in part to differences in how the approaches represent trade, fire and other disturbances and which ecosystems they include. Integrating across estimates, "best" estimates (i.e., measures of central tendency) are −472 ± 281 Tg C yr−1 based on the mean and standard deviation of the distribution and −360 Tg C yr−1 (with an interquartile range of −496 to −337) based on the median. Considering both the fossil fuel emissions source and the land sink, our analysis shows that North America was, however, a net contributor to the growth of CO2 in the atmosphere in the late 20th and early 21st century. With North America's mean annual fossil fuel CO2 emissions for the period 1990–2009 equal to 1720 Tg C yr−1 and assuming the estimate of −472 Tg C yr−1 as an approximation of the true terrestrial CO2 sink, the continent's source : sink ratio for this time period was

  15. Infrared radiation and inversion population of CO2 laser levels in Venusian and Martian atmospheres

    Science.gov (United States)

    Gordiyets, B. F.; Panchenko, V. Y.

    1983-01-01

    Formation mechanisms of nonequilibrium 10 micron CO2 molecule radiation and the possible existence of a natural laser effect in the upper atmospheres of Venus and Mars are theoretically studied. An analysis is made of the excitation process of CO2 molecule vibrational-band levels (with natural isotropic content) induced by direct solar radiation in bands 10.6, 9.4, 4.3, 2.7 and 2.0 microns. The model of partial vibrational-band temperatures was used in the case. The problem of IR radiation transfer in vibrational-rotational bands was solved in the radiation escape approximation.

  16. Abiotic formation of O2 and O3 in high-CO2 terrestrial atmospheres

    CERN Document Server

    Segura, A; Kasting, J F; Crisp, D; Cohen, M

    2007-01-01

    Previous research has indicated that high amounts of ozone (O3) and oxygen (O2) may be produced abiotically in atmospheres with high concentrations of CO2. The abiotic production of these two gases, which are also characteristic of photosynthetic life processes, could pose a potential "false-positive" for remote-sensing detection of life on planets around other stars.We show here that such false positives are unlikely on any planet that possesses abundant liquid water, as rainout of oxidized species onto a reduced planetary surface should ensure that atmospheric H2 concentrations remain relatively high, and that O2 and O3 remain low. Our aim is to determine the amount of O3 and O2 formed in a high CO2 atmosphere for a habitable planet without life. We use a photochemical model that considers hydrogen (H2) escape and a detailed hydrogen balance to calculate the O2 and O3 formed on planets with 0.2 of CO2 around the Sun, and 0.02, 0.2 and 2 bars of CO2 around a young Sun-like star with higher UV radiation. The ...

  17. Sensitivity of global biogenic isoprenoid emissions to climate variability and atmospheric CO2

    Science.gov (United States)

    Naik, Vaishali; Delire, Christine; Wuebbles, Donald J.

    2004-03-01

    Isoprenoids (isoprene and monoterpenes) are the most dominant class of biogenic volatile organic compounds (BVOCs) and have been shown to significantly affect global tropospheric chemistry and composition, climate, and the global carbon cycle. In this study we assess the sensitivity of biogenic isoprene and monoterpene emissions to combined and isolated fluctuations in observed global climate and atmospheric carbon dioxide (CO2) concentration during the period 1971-1990. We integrate surface emission algorithms within the framework of a dynamic global ecosystem model, the Integrated Biospheric Simulator (IBIS), to simulate biogenic fluxes of isoprenoids as a component of the climate-vegetation dynamics. IBIS predicts global land surface isoprene emissions of 454 Tg C and monoterpenes of 72 Tg C annually and captures the spatial and temporal patterns well. The combined fluctuations in climate and atmospheric CO2 during 1971-1990 caused significant interannual and seasonal variability in global biogenic isoprenoid fluxes that was somewhat related to the El Niño-Southern Oscillation. Furthermore, an increasing trend in the simulated emissions was seen during this period that is attributed partly to the warming trend and partly to CO2 fertilization effect. The isolated effect of increasing CO2 during this period was to steadily increase emissions as a result of increases in foliar biomass. These fluctuations in biogenic emissions could have significant impacts on regional and global atmospheric chemistry and the global carbon budget.

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

    Science.gov (United States)

    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.

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

    DEFF Research Database (Denmark)

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

    2001-01-01

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

  20. Elevated atmospheric CO2 stimulates soil fungal diversity through increased fine root production in a semiarid shrubland ecosystem.

    Science.gov (United States)

    Lipson, David A; Kuske, Cheryl R; Gallegos-Graves, La Verne; Oechel, Walter C

    2014-08-01

    Soil fungal communities are likely to be central in mediating microbial feedbacks to climate change through their effects on soil carbon (C) storage, nutrient cycling, and plant health. Plants often produce increased fine root biomass in response to elevated atmospheric carbon dioxide (CO2 ), but the responses of soil microbial communities are variable and uncertain, particularly in terms of species diversity. In this study, we describe the responses of the soil fungal community to free air CO2 enrichment (FACE) in a semiarid chaparral shrubland in Southern California (dominated by Adenomstoma fasciculatum) using large subunit rRNA gene sequencing. Community composition varied greatly over the landscape and responses to FACE were subtle, involving a few specific groups. Increased frequency of Sordariomycetes and Leotiomycetes, the latter including the Helotiales, a group that includes many dark septate endophytes known to associate positively with roots, was observed in the FACE plots. Fungal diversity, both in terms of richness and evenness, increased consistently in the FACE treatment, and was relatively high compared to other studies that used similar methods. Increases in diversity were observed across multiple phylogenetic levels, from genus to class, and were distributed broadly across fungal lineages. Diversity was also higher in samples collected close to (5 cm) plants compared to samples in canopy gaps (30 cm away from plants). Fungal biomass correlated well with soil organic matter (SOM) content, but patterns of diversity were correlated with fine root production rather than SOM. We conclude that the fungal community in this ecosystem is tightly linked to plant fine root production, and that future changes in the fungal community in response to elevated CO2 and other climatic changes will be primarily driven by changes in plant belowground allocation. Potential feedbacks mediated by soil fungi, such as soil C sequestration, nutrient cycling, and

  1. Rapid exchange between atmospheric CO2 and carbonate anion intercalated within magnesium rich layered double hydroxide.

    Science.gov (United States)

    Sahoo, Pathik; Ishihara, Shinsuke; Yamada, Kazuhiko; Deguchi, Kenzo; Ohki, Shinobu; Tansho, Masataka; Shimizu, Tadashi; Eisaku, Nii; Sasai, Ryo; Labuta, Jan; Ishikawa, Daisuke; Hill, Jonathan P; Ariga, Katsuhiko; Bastakoti, Bishnu Prasad; Yamauchi, Yusuke; Iyi, Nobuo

    2014-10-22

    The carbon cycle, by which carbon atoms circulate between atmosphere, oceans, lithosphere, and the biosphere of Earth, is a current hot research topic. The carbon cycle occurring in the lithosphere (e.g., sedimentary carbonates) is based on weathering and metamorphic events so that its processes are considered to occur on the geological time scale (i.e., over millions of years). In contrast, we have recently reported that carbonate anions intercalated within a hydrotalcite (Mg0.75Al0.25(OH)2(CO3)0.125·yH2O), a class of a layered double hydroxide (LDH), are dynamically exchanging on time scale of hours with atmospheric CO2 under ambient conditions. (Ishihara et al., J. Am. Chem. Soc. 2013, 135, 18040-18043). The use of (13)C-labeling enabled monitoring by infrared spectroscopy of the dynamic exchange between the initially intercalated (13)C-labeled carbonate anions and carbonate anions derived from atmospheric CO2. In this article, we report the significant influence of Mg/Al ratio of LDH on the carbonate anion exchange dynamics. Of three LDHs of various Mg/Al ratios of 2, 3, or 4, magnesium-rich LDH (i.e., Mg/Al ratio = 4) underwent extremely rapid exchange of carbonate anions, and most of the initially intercalated carbonate anions were replaced with carbonate anions derived from atmospheric CO2 within 30 min. Detailed investigations by using infrared spectroscopy, scanning electron microscopy, powder X-ray diffraction, elemental analysis, adsorption, thermogravimetric analysis, and solid-state NMR revealed that magnesium rich LDH has chemical and structural features that promote the exchange of carbonate anions. Our results indicate that the unique interactions between LDH and CO2 can be optimized simply by varying the chemical composition of LDH, implying that LDH is a promising material for CO2 storage and/or separation.

  2. Carbon Dioxide Production Responsibility on the Basis of comparing in Situ and mean CO2 Atmosphere Concentration Data

    CERN Document Server

    Mavrodiev, S Cht; Vachev, B

    2008-01-01

    The method is proposed for estimation of regional CO2 and other greenhouses and pollutants production responcibility. The comparison of CO2 local emissions reduction data with world CO2 atmosphere data will permit easy to judge for overall effect in curbing not only global warming but also chemical polution.

  3. The impact on atmospheric CO2 of iron fertilization induced changes in the ocean's biological pump

    Directory of Open Access Journals (Sweden)

    J. C. McWilliams

    2008-03-01

    Full Text Available Using numerical simulations, we quantify the impact of changes in the ocean's biological pump on the air-sea balance of CO2 by fertilizing a small surface patch in the high-nutrient, low-chlorophyll region of the eastern tropical Pacific with iron. Decade-long fertilization experiments are conducted in a basin-scale, eddy-permitting coupled physical/biogeochemical/ecological model. In contrast to previous studies, we find that most of the dissolved inorganic carbon (DIC removed from the euphotic zone by the enhanced biological export is replaced by uptake of CO2 from the atmosphere. Atmospheric uptake efficiencies, the ratio of the perturbation in air-sea CO2 flux to the perturbation in export flux across 100 m, integrated over 10 years, are 0.75 to 0.93 in our patch size-scale experiments. The atmospheric uptake efficiency is insensitive to the duration of the experiment. The primary factor controlling the atmospheric uptake efficiency is the vertical distribution of the enhanced biological production and export. Iron fertilization at the surface tends to induce production anomalies primarily near the surface, leading to high efficiencies. In contrast, mechanisms that induce deep production anomalies (e.g. altered light availability tend to have a low uptake efficiency, since most of the removed DIC is replaced by lateral and vertical transport and mixing. Despite high atmospheric uptake efficiencies, patch-scale iron fertilization of the ocean's biological pump tends to remove little CO2 from the atmosphere over the decadal timescale considered here.

  4. Atmospheric CO2 Amplification of Orbitally Forced Changes in the Hydrological Cycle in the Early Mesozoic

    Science.gov (United States)

    Olsen, P. E.; Schaller, M. F.; Kent, D. V.

    2015-12-01

    Models of increasing atmospheric CO2 predict an intensification of the hydrological cycle coupled with warming, possibly amplifying effects of orbitally-forced fluctuations. While there is some Pleistocene evidence of this, CO2 concentrations were much lower than projected for the future. For the potentially more relevant Early Mesozoic, with CO2 >1000 ppm, we observe that both the soil carbonate and stomatal proxies for CO2 strongly and positively correlate with climatic-precession variance in correlative continental and marine strata of both eastern North America and Europe with temporal correlation robustly supported by magneto-, astro-, and U-Pb zircon geochronology. Eastern North American lacustrine and paleosol strata are generally characterized by >3000 ppm CO2 over most of the Norian (228-207 Ma) dropping to ~1000-3000 ppm during the succeeding latest Norian to late Rhaetian (207 to 201.6 Ma) correlative with a dramatic drop in the amplitude of the response to orbital forcing. This is followed by an extraordinary doubling to nearly tripling of CO2 (~2000-5000 ppm) in the latest Rhaetian to Early Jurassic (201.6 to 200.6 Ma) and a concurrent profound increase in the amplitude of the apparent climatic-precession variance during the eruption of the massive Central Atlantic Magmatic Province. Decreasing CO2 (~1000-2000 ppm) afterward is tracked by decreasing amplitude in the orbitally-paced cyclicity. Likewise, in the UK, high amplitude cyclicity in the lacustrine to paralic Twyning Md. Fm. gives way upward into the paralic Blue Anchor and marine Rhaetian Westbury fms in which lithological cyclicity is muted. Again, the amplitude of the orbitially-paced lithological cyclicity dramatically increases into the paralic to marine late Rhaetian Lilstock Fm. and marine latest Rhaetian to Early Jurassic Blue Lias. Parallel and correlative transitions are seen in at least western Germany. The agreement between the continental eastern US and paralic to marine European

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

    Science.gov (United States)

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

    2016-04-01

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

  6. 2-micron Double Pulsed IPDA Lidar for Atmospheric CO2 Measurement

    Science.gov (United States)

    Yu, Jirong; Petros, Mulugeta; Refaat, Tamer; Reithmaier, Karl; Remus, Ruben; Singh, Upendra; Johnson, Will; Boyer, Charlie; Fay, James; Johnston, Susan; Murchison, Luke; Scola, Tory

    2015-04-01

    We have developed a high energy pulsed 2-micron IPDA lidar instrument to measure the atmospheric CO2 column density. The IPDA lidar is operated on the long wavelength wing of R(30) CO2 line at 2050.967 nm (4875.749 cm-1) in the side-line operation mode. The R(30) line is an excellent absorption line for the measurements of CO2 in 2µm wavelength region with regard to the strength of the absorption lines, low susceptibility to atmospheric temperature variability, and freedom from problematic interference with other absorption lines. The Ho:Tm:YLF laser transmitter is designed to be operated in a unique double pulse format that can produce two-pulse pair in 10 Hz operation. Typically, the output energies of the laser transmitter are 100mJ and 45mJ for the first pulse and the second pulse, respectively. We injection seed the first pulse with on-line frequency and the second pulse with off-line frequency. The IPDA lidar instrument size, weight and power consumption were restricted to small research aircraft payload requirements. The airborne IPDA lidar instrument measures the total integrated column content of CO2 from the instrument to the ground but with weighting that can be tuned by controlling the transmitted wavelengths. Therefore, the transmitter could be tuned to weight the column measurement to the surface for optimum CO2 interaction studies or up to the free troposphere for optimum transport studies. The 2-μm CO2 IPDA lidar airborne demonstration was conducted during March 20, 2014 through April 10, 2014. IPDA lidar airborne flights included various operating and environmental conditions. Environmental conditions included different flight altitude up to 8.3 km, different ground target conditions such as vegetation, soil, ocean, snow and sand and different cloud conditions. Besides, some flights targeted power plant incinerators for investigating the IPDA sensitivity to CO2 plums. The lidar instrument is robust during all of the flights. This paper describes

  7. Climate change and agroecosystems: the effect of elevated atmospheric CO2 and temperature on crop growth, development, and yield

    Directory of Open Access Journals (Sweden)

    Streck Nereu Augusto

    2005-01-01

    Full Text Available The amount of carbon dioxide (CO2 of the Earths atmosphere is increasing, which has the potential of increasing greenhouse effect and air temperature in the future. Plants respond to environment CO2 and temperature. Therefore, climate change may affect agriculture. The purpose of this paper was to review the literature about the impact of a possible increase in atmospheric CO2 concentration and temperature on crop growth, development, and yield. Increasing CO2 concentration increases crop yield once the substrate for photosynthesis and the gradient of CO2 concentration between atmosphere and leaf increase. C3 plants will benefit more than C4 plants at elevated CO2. However, if global warming will take place, an increase in temperature may offset the benefits of increasing CO2 on crop yield.

  8. Measuring atmospheric CO2 from space using Full Spectral Initiation (FSI WFM-DOAS

    Directory of Open Access Journals (Sweden)

    M. P. Barkley

    2006-01-01

    Full Text Available Satellite measurements of atmospheric CO2 concentrations are a rapidly evolving area of scientific research which can help reduce the uncertainties in the global carbon cycle fluxes and provide insight into surface sources and sinks. One of the emerging CO2 measurement techniques is a relatively new retrieval algorithm called Weighting Function Modified Differential Optical Absorption Spectroscopy (WFM-DOAS that has been developed by Buchwitz et al. (2000. This algorithm is designed to measure the total columns of CO2 (and other greenhouse gases through the application to spectral measurements in the near infrared (NIR, made by the SCIAMACHY instrument on-board ENVISAT. The algorithm itself is based on fitting the logarithm of a model reference spectrum and its derivatives to the logarithm of the ratio of a measured nadir radiance and solar irradiance spectrum. In this work, a detailed error assessment of this technique has been conducted and it has been found necessary to include suitable a priori information within the retrieval in order to minimize the errors on the retrieved CO2 columns. Hence, a more flexible implementation of the retrieval technique, called Full Spectral Initiation (FSI WFM-DOAS, has been developed which generates a reference spectrum for each individual SCIAMACHY observation using the estimated properties of the atmosphere and surface at the time of the measurement. Initial retrievals over Siberia during the summer of 2003 show that the measured CO2 columns are not biased from the input a priori data and that whilst the monthly averaged CO2 distributions contain a high degree of variability, they also contain interesting spatial features.

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

    Institute of Scientific and Technical Information of China (English)

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

    2007-01-01

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

  10. Atmospheric CO2 enrichment and drought stress modify root exudation of barley.

    Science.gov (United States)

    Calvo, Olga C; Franzaring, Jürgen; Schmid, Iris; Müller, Matthias; Brohon, Nolwenn; Fangmeier, Andreas

    2017-03-01

    Rising CO2 concentrations associated with drought stress is likely to influence not only aboveground growth, but also belowground plant processes. Little is known about root exudation being influenced by elements of climate change. Therefore, this study wanted to clarify whether barley root exudation responds to drought and CO2 enrichment and whether this reaction differs between an old and a recently released malting barley cultivar. Barley plants were grown in pots filled with sand in controlled climate chambers at ambient (380 ppm) or elevated (550 ppm) atmospheric [CO2 ] and a normal or reduced water supply. Root exudation patterns were examined at the stem elongation growth stage and when the inflorescences emerged. At both dates, root exudates were analyzed for different compounds such as total free amino acids, proline, potassium, and some phytohormones. Elevated [CO2 ] decreased the concentrations in root exudates of some compounds such as total free amino acids, proline, and abscisic acid. Moreover, reduced water supply increased proline, potassium, electric conductivity, and hormone concentrations. In general, the modern cultivar showed higher concentrations of proline and abscisic acid than the old one, but the cultivars responded differentially under elevated CO2 . Plant developmental stage had also an impact on the root exudation patterns of barley. Generally, we observed significant effects of CO2 enrichment, watering levels, and, to a lesser extent, cultivar on root exudation. However, we did not find any mitigation of the adverse effects of drought by elevated CO2 . Understanding the multitude of relationships within the rhizosphere is an important aspect that has to be taken into consideration in the context of crop performance and carbon balance under conditions of climate change.

  11. Response of leaf litter decomposition to rises in atmospheric CO2 and temperature

    Science.gov (United States)

    Hammrich, A.; Flury, S.; Gessner, M. O.

    2007-05-01

    Atmospheric concentrations of CO2 have considerably increased in the last century and are expected to rise further. Elevated CO2 concentrations not only increase global temperature but also have potential to change plant litter quality, for example by increasing lignin content, changing C:N ratios and altering tannin contents. These chemical changes may interact with increased temperature to alter litter decomposition. To test whether changes in litter quality and warming affect decomposition, we conducted a field experiment with leaf litter collected from six species of mature deciduous trees exposed to either ambient or elevated CO2 levels. We used a set of 16 enclosures installed in four blocks in a freshwater marsh in a prealpine lake to test for the effects of CO2-mediated litter quality and temperature and the interaction of both factors. We measured leaf mass loss of the twelve litter types in control and heated enclosures (4 °C above ambient) and also in the open marsh. In contrast to expectations, species decomposing at low (oak and beech) and medium (hornbeam and maple) rates showed faster mass loss when leaves were grown under elevated CO2 conditions, whereas fast-decomposing species (cherry and basswood) showed no clear response. The accelerated decomposition of CO2-enriched litter could be due to higher amounts of nonstructural carbohydrates, which may have been either leached or readily degraded. Warming had a surprisingly small influence on mass loss of the tested litter species, and interactive effects were weak. These results suggest that direct and indirect effects of elevated CO2 levels on litter decomposition may not be readily predictable from first principles.

  12. Marginal Lands Gross Primary Production Dominate Atmospheric CO2 Interannual Variations

    Science.gov (United States)

    Ahlström, A.; Raupach, M. R.; Schurgers, G.; Arneth, A.; Jung, M.; Reichstein, M.; Smith, B.

    2014-12-01

    Since the 1960s terrestrial ecosystems have acted as a substantial sink for atmospheric CO2, sequestering about one quarter of anthropogenic emissions in an average year. Variations in this land carbon sink are also responsible for most of the large interannual variability in atmospheric CO2 concentrations. While most evidence places the majority of the sink in highly productive forests and at high latitudes experiencing warmer and longer growing seasons, the location and the processes governing the interannual variations are still not well characterised. Here we evaluate the hypothesis that the long-term trend and the variability in the land CO2 sink are respectively dominated by geographically distinct regions: the sink by highly productive lands, mainly forests, and the variability by semi-arid or "marginal" lands where vegetation activity is strongly limited by water and therefore responds strongly to climate variability. Using novel analysis methods and data from both upscaled flux-tower measurements and a dynamic global vegetation model, we show that (1) the interannual variability in the terrestrial CO2 sink arises mainly from variability in terrestrial gross primary production (GPP); (2) most of the interannual variability in GPP arises in tropical and subtropical marginal lands, where negative anomalies are driven mainly by warm, dry conditions and positive anomalies by cool, wet conditions; (3) the variability in the GPP of high-latitude marginal lands (tundra and shrublands) is instead controlled by temperature and light, with warm bright conditions resulting in positive anomalies. The influence of ENSO (El Niño-Southern Oscillation) on the growth rate of atmospheric CO2 concentrations is mediated primarily through climatic effects on GPP in marginal lands, with opposite signs in subtropical and higher-latitude regions. Our results show that the land sink of CO2 (dominated by forests) and its interannual variability (dominated by marginal lands) are

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

    Science.gov (United States)

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

    2017-01-01

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

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

    Science.gov (United States)

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

    2017-01-01

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

  15. Progress in Modeling Global Atmospheric CO2 Fluxes and Transport: Results from Simulations with Diurnal Fluxes

    Science.gov (United States)

    Collatz, G. James; Kawa, R.

    2007-01-01

    Progress in better determining CO2 sources and sinks will almost certainly rely on utilization of more extensive and intensive CO2 and related observations including those from satellite remote sensing. Use of advanced data requires improved modeling and analysis capability. Under NASA Carbon Cycle Science support we seek to develop and integrate improved formulations for 1) atmospheric transport, 2) terrestrial uptake and release, 3) biomass and 4) fossil fuel burning, and 5) observational data analysis including inverse calculations. The transport modeling is based on meteorological data assimilation analysis from the Goddard Modeling and Assimilation Office. Use of assimilated met data enables model comparison to CO2 and other observations across a wide range of scales of variability. In this presentation we focus on the short end of the temporal variability spectrum: hourly to synoptic to seasonal. Using CO2 fluxes at varying temporal resolution from the SIB 2 and CASA biosphere models, we examine the model's ability to simulate CO2 variability in comparison to observations at different times, locations, and altitudes. We find that the model can resolve much of the variability in the observations, although there are limits imposed by vertical resolution of boundary layer processes. The influence of key process representations is inferred. The high degree of fidelity in these simulations leads us to anticipate incorporation of realtime, highly resolved observations into a multiscale carbon cycle analysis system that will begin to bridge the gap between top-down and bottom-up flux estimation, which is a primary focus of NACP.

  16. Oceanic iron fertilization:one of strategies for sequestration atmospheric CO2

    Institute of Scientific and Technical Information of China (English)

    宋金明

    2003-01-01

    Carbon cycle is connected with the most important environmental issue of Global Change.As one of the major carbon reservoirs, oceans play an important part in the carbon cycle. In recentyears, iron seems to give us a good news that oceanic iron fertilization could stimulate biological produc-tivity as CO2 sink of human-produced CO2. Oceanic iron fertilization experiments have verified thatadding iron into high nutrient low chlorophyll (HNLC) seawaters can increase phytoplankton productionand export organic carbon, and hence increase carbon sink of anthropogenic CO2, to reduce globalwarming. In sixty days, the export organic carbon could reach 10 000 times for adding iron by modelprediction and in situ experiment, I.e. The atmospheric CO2 uptake and inorganic carbon drawdown inupper seawaters also have the same magnitude. Therefore, oceanic iron fertilization is one of the strate-gies for increasing carbon sink of anthropogenic CO2. The paper is focused on the iron fertilization, es-pecially in situ ocean iron experiments in order that the future research is more efficient.

  17. Phosphorus feedbacks constraining tropical ecosystem responses to changes in atmospheric CO2 and climate

    Science.gov (United States)

    Yang, Xiaojuan; Thornton, Peter E.; Ricciuto, Daniel M.; Hoffman, Forrest M.

    2016-07-01

    The effects of phosphorus (P) availability on carbon (C) cycling in the Amazon region are investigated using CLM-CNP. We demonstrate that the coupling of P dynamics reduces the simulated historical terrestrial C sink due to increasing atmospheric CO2 concentrations ([CO2]) by about 26%. Our exploratory simulations show that the response of tropical forest C cycling to increasing [CO2] depends on how elevated CO2 affects phosphatase enzyme production. The effects of warming are more complex, depending on the interactions between humidity, C, and nutrient dynamics. While a simulation with low humidity generally shows the reduction of net primary productivity (NPP), a second simulation with higher humidity suggests overall increases in NPP due to the dominant effects of reduced water stress and more nutrient availability. Our simulations point to the need for (1) new observations on how elevated [CO2] affects phosphatase enzyme production and (2) more tropical leaf-scale measurements under different temperature/humidity conditions with different soil P availability.

  18. Plant-soil distribution of potentially toxic elements in response to elevated atmospheric CO2.

    Science.gov (United States)

    Duval, Benjamin D; Dijkstra, Paul; Natali, Susan M; Megonigal, J Patrick; Ketterer, Michael E; Drake, Bert G; Lerdau, Manuel T; Gordon, Gwyneth; Anbar, Ariel D; Hungate, Bruce A

    2011-04-01

    The distribution of contaminant elements within ecosystems is an environmental concern because of these elements' potential toxicity to animals and plants and their ability to hinder microbial ecosystem services. As with nutrients, contaminants are cycled within and through ecosystems. Elevated atmospheric CO2 generally increases plant productivity and alters nutrient element cycling, but whether CO2 causes similar effects on the cycling of contaminant elements is unknown. Here we show that 11 years of experimental CO2 enrichment in a sandy soil with low organic matter content causes plants to accumulate contaminants in plant biomass, with declines in the extractable contaminant element pools in surface soils. These results indicate that CO2 alters the distribution of contaminant elements in ecosystems, with plant element accumulation and declining soil availability both likely explained by the CO2 stimulation of plant biomass. Our results highlight the interdependence of element cycles and the importance of taking a broad view of the periodic table when the effects of global environmental change on ecosystem biogeochemistry are considered.

  19. Atmospheric CO2 observations and models suggest strong carbon uptake by forests in New Zealand

    Science.gov (United States)

    Steinkamp, Kay; Mikaloff Fletcher, Sara E.; Brailsford, Gordon; Smale, Dan; Moore, Stuart; Keller, Elizabeth D.; Baisden, W. Troy; Mukai, Hitoshi; Stephens, Britton B.

    2017-01-01

    A regional atmospheric inversion method has been developed to determine the spatial and temporal distribution of CO2 sinks and sources across New Zealand for 2011-2013. This approach infers net air-sea and air-land CO2 fluxes from measurement records, using back-trajectory simulations from the Numerical Atmospheric dispersion Modelling Environment (NAME) Lagrangian dispersion model, driven by meteorology from the New Zealand Limited Area Model (NZLAM) weather prediction model. The inversion uses in situ measurements from two fixed sites, Baring Head on the southern tip of New Zealand's North Island (41.408° S, 174.871° E) and Lauder from the central South Island (45.038° S, 169.684° E), and ship board data from monthly cruises between Japan, New Zealand, and Australia. A range of scenarios is used to assess the sensitivity of the inversion method to underlying assumptions and to ensure robustness of the results. The results indicate a strong seasonal cycle in terrestrial land fluxes from the South Island of New Zealand, especially in western regions covered by indigenous forest, suggesting higher photosynthetic and respiratory activity than is evident in the current a priori land process model. On the annual scale, the terrestrial biosphere in New Zealand is estimated to be a net CO2 sink, removing 98 (±37) Tg CO2 yr-1 from the atmosphere on average during 2011-2013. This sink is much larger than the reported 27 Tg CO2 yr-1 from the national inventory for the same time period. The difference can be partially reconciled when factors related to forest and agricultural management and exports, fossil fuel emission estimates, hydrologic fluxes, and soil carbon change are considered, but some differences are likely to remain. Baseline uncertainty, model transport uncertainty, and limited sensitivity to the northern half of the North Island are the main contributors to flux uncertainty.

  20. Changes in fungal community composition in response to elevated atmospheric CO2 and nitrogen fertilization varies with soil horizon

    Directory of Open Access Journals (Sweden)

    Carolyn F Weber

    2013-04-01

    Full Text Available Increasing levels of atmospheric carbon dioxide (CO2 and rates of nitrogen (N-deposition to forest ecosystems are predicted to alter the structure and function of soil fungal communities, but the spatially heterogeneous distribution of soil fungi has hampered investigations aimed at understanding such impacts. We hypothesized that soil physical and chemical properties and fungal community composition would be differentially impacted by elevated atmospheric CO2 (eCO2 and N-fertilization in spatially separated field samples, in the forest floor, 0-2 cm, 2-5 cm and 5-10 cm depth intervals in a loblolly pine Free-Air-Carbon Dioxide Enrichment (FACE experiment. In all soils, quantitative PCR-based estimates of fungal biomass were highest in the forest floor. Fungal richness, based on pyrosequencing of the fungal ribosomal large subunit gene, increased in response to N-fertilization in 0-2 cm and forest floor intervals. Composition shifted in forest floor, 0-2 cm and 2-5 cm intervals in response to N-fertilization, but the shift was most distinct in the 0-2 cm interval, in which the largest number of statistically significant changes in soil chemical parameters (i.e phosphorus, organic matter, calcium, pH was also observed. In the 0-2 cm interval, increased recovery of sequences from the Thelephoraceae, Tricholomataceae, Hypocreaceae, Clavicipitaceae, and Herpotrichiellaceae families and decreased recovery of sequences from the Amanitaceae correlated with N-fertilization. In this same depth interval, Amanitaceae, Tricholomataceae and Herpotriciellaceae sequences were recovered less frequently from soils exposed to eCO2 relative to ambient conditions. These results demonstrated that vertical stratification should be taken into consideration in future efforts to elucidate environmental impacts on fungal communities and their feedbacks on ecosystem processes.

  1. Carbon allocation changes: an adaptive response to variations in atmospheric CO2

    Science.gov (United States)

    Harrison, Sandy; Li, Guangqi; Prentice, Iain Colin

    2016-04-01

    Given the ubiquity of nutrient constraints on primary production, an optimal carbon allocation strategy is expected to increase total below-ground allocation (fine root production and turnover, allocation to mycorrhizae and carbon exudation to the rhizophere) as atmospheric CO2 concentration increases. Conversely, below-ground allocation should be reduced when atmospheric CO2 concentrations were low, as occurred during glacial times. Using a coupled generic primary production and tree-growth model, we quantify the changes in carbon allocation that are required to explain the apparent homoeostasis of tree radial growth during recent decades and between glacial and interglacial conditions. These results suggest a resolution of the apparent paradox of continuing terrestrial CO2 uptake (a consequence of CO2 fertilization) and the widespread lack of observed enhancement of stem growth in trees. Adaptive shifts in carbon allocation are thus a key feature that should to be accounted for in models to predict tree growth and future timber harvests, as well as in large-scale ecosystem and carbon cycle models.

  2. Changes in Atlantic Thermohaline Circulation under Different Atmospheric CO2 Scenarios in a Climate Model

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The changes in the thermohaline circulation (THC) because of the increased CO2 in the atmosphere play an important role in future climate regimes.In this article, a new climate model developed at the Max-Planck Institute for Meteorology is used to study the variation in THC strength, the changes of North Atlantic deep-water (NADW) formation, and the regional responses of the THC in the North Atlantic to increasing atmospheric CO2.From 2000 to 2100, under increased CO2 scenarios (B1, A1B, and A2), the strength of THC decreases by 4 Sv (106 m3/s), 5.1 Sv, and 5.2 Sv, respectively, equivalent to a reduction of 20%, 25%, and 25.1% of the present THC strength.The analyses show that the oceanic deep convective activity significantly strengthens in the Greenland-Iceland-Norway(GIN) Seas owing to saltier (denser) upper oceans, whereas weakens in the Labrador Sea and in the south of the Denmark Strait region (SDSR) because of surface warming and freshening due to global warming.The saltiness of the GIN Seas is mainly caused by the increase of the saline North Atlantic inflow through the Faro-Bank (FB) Channel.Under the scenario A1B, the deep-water formation rate in the North Atlantic decreases from 16.2 Sv to 12.9 Sv with increasing CO2.

  3. Atmospheric inversion for cost effective quantification of city CO2 emissions

    Science.gov (United States)

    Wu, L.; Broquet, G.; Ciais, P.; Bellassen, V.; Vogel, F.; Chevallier, F.; Xueref-Remy, I.; Wang, Y.

    2015-11-01

    Cities, currently covering only a very small portion (market- or policy-based mitigation actions. Here we propose a monitoring tool that could support the development of such procedures at the city scale. It is based on an atmospheric inversion method that exploits inventory data and continuous atmospheric CO2 concentration measurements from a network of stations within and around cities to estimate city CO2 emissions. We examine the cost-effectiveness and the performance of such a tool. The instruments presently used to measure CO2 concentrations at research stations are expensive. However, cheaper sensors are currently developed and should be useable for the monitoring of CO2 emissions from a megacity in the near-term. Our assessment of the inversion method is thus based on the use of several types of hypothetical networks, with a range of numbers of sensors sampling at 25 m a.g.l. The study case for this assessment is the monitoring of the emissions of the Paris metropolitan area (~ 12 million inhabitants and 11.4 Tg C emitted in 2010) during the month of January 2011. The performance of the inversion is evaluated in terms of uncertainties in the estimates of total and sectoral CO2 emissions. These uncertainties are compared to a notional ambitious target to diagnose annual total city emissions with an uncertainty of 5 % (2-sigma). We find that, with 10 stations only, which is the typical size of current pilot networks that are deployed in some cities, the uncertainty for the 1-month total city CO2 emissions is significantly reduced by the inversion by ~ 42 % but still corresponds to an annual uncertainty that is two times larger than the target of 5 %. By extending the network from 10 to 70 stations, the inversion can meet this requirement. As for major sectoral CO2 emissions, the uncertainties in the inverted emissions using 70 stations are reduced significantly over that obtained using 10 stations by 32 % for commercial and residential buildings, by 33 % for

  4. Scaling laws for perturbations in the ocean–atmosphere system following large CO2 emissions

    Directory of Open Access Journals (Sweden)

    N. Towles

    2015-07-01

    Full Text Available Scaling relationships are found for perturbations to atmosphere and ocean variables from large transient CO2 emissions. Using the Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir (LOSCAR model (Zeebe et al., 2009; Zeebe, 2012b, we calculate perturbations to atmosphere temperature, total carbon, ocean temperature, total ocean carbon, pH, alkalinity, marine-sediment carbon, and carbon-13 isotope anomalies in the ocean and atmosphere resulting from idealized CO2 emission events. The peak perturbations in the atmosphere and ocean variables are then fit to power law functions of the form of γ DαEβ, where D is the event duration, E is its total carbon emission, and γ is a coefficient. Good power law fits are obtained for most system variables for E up to 50 000 PgC and D up to 100 kyr. Although all of the peak perturbations increase with emission rate E/D, we find no evidence of emission-rate-only scaling, α + β = 0. Instead, our scaling yields α + β ≃ 1 for total ocean and atmosphere carbon and 0 < α + β < 1 for most of the other system variables.

  5. Miniaturized Laser Heterodyne Radiometer for Measurements of CO2 in the Atmospheric Column

    Science.gov (United States)

    Wilson, E. L.; Mclinden, M. L.; Miller, J. H.; Allan, G. R.; Lott, L. E.; Melroy, H. R.; Clarke, G. B.

    2013-01-01

    We have developed a low-cost, miniaturized laser heterodyne radiometer for highly sensitive measurements of carbon dioxide (CO2) in the atmospheric column. In this passive design, sunlight that has undergone absorption by CO2 in the atmosphere is collected and mixed with continuous wave laser light that is step-scanned across the absorption feature centered at 1,573.6 nm. The resulting radio frequency beat signal is collected as a function of laser wavelength, from which the total column mole fraction can be de-convolved. We are expanding this technique to include methane (CH4) and carbon monoxide (CO), and with minor modifications, this technique can be expanded to include species such as water vapor (H2O) and nitrous oxide (N2O).

  6. Atmospheric CO2 and CH4 Measurement Network on Towers in Siberia

    Science.gov (United States)

    Shimoyama, K.; Machida, T.; Shinohara, A.; Maksyutov, S.; Arshinov, M.; Davydov, D.; Fofonov, A.; Krasnov, O.; Fedoseev, N.; Belan, B.; Belan, H.; Inoue, G.

    2006-12-01

    In order to estimate CO2 and CH4 fluxes at regional to sub-continental scale by an inverse model, a network of tall towers for atmospheric CO2 and CH4 measurements has been established over a region of thousand square kilometers in west Siberia. In-situ continuous measurements have been conducted at 6 stations: Berezorechka (56.17N, 84.33E) since 2002, Parabel (58.25N, 82.40E) and Igrim (63.20N, 64.48E) since 2004, Demyanskoe (59.78N, 70.87E) and Noyabrsk (63.43N, 76.76E) since 2005, and Yakutsk (62.83N, 129.35E) in east Siberia since 2005. Over next two years, installations of 4 more stations are planned. This study provides some results of observation from this network. Seasonal cycles of CO2 showed quite similar trends in growing season (May to September) among the west Siberian sites. The remarkable decrease of CO2 concentration occurred in early May and the seasonal minimum was observed between July and August. On the other hand, the short-term (from several days to week) variations in CO2 concentrations were quite different among the sites, particularly during the growing season. Rather large variation of more than 25 ppm within a week was observed during winter. The changes in CO2 concentrations at the nearby sites were almost identical. Monthly mean values of CO2 during the growing season were relatively higher at the northern sites than at southern sites. These observational results evidentially reflected the regional characteristics of CO2 flux variation, transportation, and mixing process. Daily cycles of CH4 in summer showed nocturnal increase and diurnal decrease which was due to emission of CH4 from wetland accumulated over night, and diurnal convective mixing. Relatively high concentrations of CH4 were observed in winter and summer. Because there is one of the world's vastest wetland in western Siberia, the peak of CH4 in summer implies the significant role of CH4 emissions from the west Siberian wetland to the atmosphere. On the other hand, an

  7. Investigating the Multiple Food Sources and N Chemistry of Invasive Earthworms at the Rhinelander, WI, Free Air CO2 Enrichment (FACE) Experiment

    Science.gov (United States)

    Top, S. M.; Filley, T. R.

    2013-12-01

    Rising levels of atmospheric CO2 can directly and indirectly alter biogeochemical cycling in forest ecosystems through changes to plant productivity, tissue chemistry, and associated feedbacks to microbial and faunal communities. At the Rhinelander free air CO2 enrichment site (FACE), Rhinelander WI, we examined the consumption and movement of plant tissue and soil by invasive earthworm species using a multi-proxy stable isotope and amino acid chemistry analysis of plant and soil, as well as fecal matter extracted from invasive earthworms present at the site. Using an isotopic mixing model that exploits the 13C-depleted CO2 source and a previous 15N labeling in the FACE experiment, we determined potential sources to the earthworm fecal matter and the movement of amino compounds. For epigeic, surface dwelling earthworms, the stable isotope modeling showed the largest contribution to the C and N in fecal matter was from leaf litter (up to 80%) which was depleted in amino acid C under elevated CO2 conditions. Fecal matter from the endogeic, mineral soil dwelling earthworms was primarily derived from 0-5 cm soil (up to 56%) and fine root tissue (up to 70%). Additionally, amino acid C in this group of earthworms had a proportionately greater relative concentration compared to the epigeic species and the 0-5cm soil. Here we demonstrate that earthworms are incorporating multiple sources (leaf litter, root, and soil) into their fecal matter, which then get deposited throughout the soil profile, where nutrients could become available for plant use.

  8. Proposing a mechanistic understanding of changes in atmospheric CO2 during the last 740 000 years

    Directory of Open Access Journals (Sweden)

    H. Fischer

    2006-02-01

    Full Text Available Atmospheric carbon dioxide (CO2 measured in Antarctic ice cores shows a natural variability of 80 to 100 ppmv during the last four glacial cycles and variations of approximately 60 ppmv in the two cycles between 410 and 650 kyr BP. We here use dust and the isotopic temperature proxy deuterium (δD from the EPICA Dome C Antarctic ice core covering the last 740 kyr together with other paleo-climatic records to force the ocean/atmosphere/biosphere box model of the global carbon cycle BICYCLE in a forward mode over this time in order to reconstruct the natural variability of pCO2. Our simulation results covered by our proposed scenario are based on process understanding gained previously for carbon cycle variations during Termination I. These results match the pCO2 measured in the Vostok ice core well (r2=0.80 and we predict prior to Termination V significantly smaller amplitudes in pCO2 variations mainly based on a reduced interglacial ocean circulation and reduced interglacial Southern Ocean sea surface temperature. These predictions for the pre-Vostok period match the new pCO2 data from the EPICA Dome C ice core for the time period 410 to 650 kyr BP equally well (r2=0.79. This is the first forward modelling approach which covers all major processes acting on the global carbon cycle on glacial/interglacial time scales. The contributions of different processes (terrestrial carbon storage, sea ice, sea level, ocean temperature, ocean circulation, CaCO3 chemistry, marine biota are analysed.

  9. Development of Laser, Detector, and Receiver Systems for an Atmospheric CO2 Lidar Profiling System

    Science.gov (United States)

    Ismail, Syed; Koch, Grady; Abedin, Nurul; Refaat, Tamer; Rubio, Manuel; Singh, Upendra

    2008-01-01

    A ground-based Differential Absorption Lidar (DIAL) is being developed with the capability to measure range-resolved and column amounts of atmospheric CO2. This system is also capable of providing high-resolution aerosol profiles and cloud distributions. It is being developed as part of the NASA Earth Science Technology Office s Instrument Incubator Program. This three year program involves the design, development, evaluation, and fielding of a ground-based CO2 profiling system. At the end of a three-year development this instrument is expected to be capable of making measurements in the lower troposphere and boundary layer where the sources and sinks of CO2 are located. It will be a valuable tool in the validation of NASA Orbiting Carbon Observatory (OCO) measurements of column CO2 and suitable for deployment in the North American Carbon Program (NACP) regional intensive field campaigns. The system can also be used as a test-bed for the evaluation of lidar technologies for space-application. This DIAL system leverages 2-micron laser technology developed under a number of NASA programs to develop new solid-state laser technology that provides high pulse energy, tunable, wavelength-stabilized, and double-pulsed lasers that are operable over pre-selected temperature insensitive strong CO2 absorption lines suitable for profiling of lower tropospheric CO2. It also incorporates new high quantum efficiency, high gain, and relatively low noise phototransistors, and a new receiver/signal processor system to achieve high precision DIAL measurements.

  10. Climate warming due to increasing atmospheric CO2 - Simulations with a multilayer coupled atmosphere-ocean seasonal energy balance model

    Science.gov (United States)

    Li, Peng; Chou, Ming-Dah; Arking, Albert

    1987-01-01

    The transient response of the climate to increasing CO2 is studied using a modified version of the multilayer energy balance model of Peng et al. (1982). The main characteristics of the model are described. Latitudinal and seasonal distributions of planetary albedo, latitude-time distributions of zonal mean temperatures, and latitudinal distributions of evaporation, water vapor transport, and snow cover generated from the model and derived from actual observations are analyzed and compared. It is observed that in response to an atmospheric doubling of CO2, the model reaches within 1/e of the equilibrium response of global mean surface temperature in 9-35 years for the probable range of vertical heat diffusivity in the ocean. For CO2 increases projected by the National Research Council (1983), the model's transient response in annually and globally averaged surface temperatures is 60-75 percent of the corresponding equilibrium response, and the disequilibrium increases with increasing heat diffusivity of the ocean.

  11. Response of free-living soil protozoa and microorganisms to elevated atmospheric CO2 and presence of mycorrhiza

    DEFF Research Database (Denmark)

    Rønn, R.; Gavito, M.; Larsen, J.

    2002-01-01

    Possible interactions between mycorrhiza, atmospheric CO2, free-living soil microorganisms and protozoa were investigated in pot experimental systems. Pea plants (Pisum sativum L. cv. Solara) were grown under ambient (360 mul l(-1)) or elevated (700 mul l(-1)) atmospheric CO2 concentration...... with or without the presence of the arbuscular mycorrhizal (AM) fungus Glomus caledonium. It was hypothesised that (1) the populations of free-living soil protozoa would increase as a response to elevated CO2, (2) the effect of elevated CO2 on protozoa would be moderated by the presence of mycorrhiza and (3......) the presence of arbuscular mycorrhiza would affect soil protozoan numbers regardless of atmospheric CO2. After 3 weeks growth there was no difference in bacterial numbers (direct counts) in soil, but the number of free-living bacterial-feeding protozoa was significantly higher under elevated CO2...

  12. What would dense atmospheric observation networks bring to the quantification of city CO2 emissions?

    Science.gov (United States)

    Wu, Lin; Broquet, Grégoire; Ciais, Philippe; Bellassen, Valentin; Vogel, Felix; Chevallier, Frédéric; Xueref-Remy, Irène; Wang, Yilong

    2016-06-01

    Cities currently covering only a very small portion ( global energy-related CO2, but they are associated with 71-76 % of CO2 emissions from global final energy use. Although many cities have set voluntary climate plans, their CO2 emissions are not evaluated by the monitoring, reporting, and verification (MRV) procedures that play a key role for market- or policy-based mitigation actions. Here we analyze the potential of a monitoring tool that could support the development of such procedures at the city scale. It is based on an atmospheric inversion method that exploits inventory data and continuous atmospheric CO2 concentration measurements from a network of stations within and around cities to estimate city CO2 emissions. This monitoring tool is configured for the quantification of the total and sectoral CO2 emissions in the Paris metropolitan area (˜ 12 million inhabitants and 11.4 TgC emitted in 2010) during the month of January 2011. Its performances are evaluated in terms of uncertainty reduction based on observing system simulation experiments (OSSEs). They are analyzed as a function of the number of sampling sites (measuring at 25 m a.g.l.) and as a function of the network design. The instruments presently used to measure CO2 concentrations at research stations are expensive (typically ˜ EUR 50 k per sensor), which has limited the few current pilot city networks to around 10 sites. Larger theoretical networks are studied here to assess the potential benefit of hypothetical operational lower-cost sensors. The setup of our inversion system is based on a number of diagnostics and assumptions from previous city-scale inversion experiences with real data. We find that, given our assumptions underlying the configuration of the OSSEs, with 10 stations only the uncertainty for the total city CO2 emission during 1 month is significantly reduced by the inversion by ˜ 42 %. It can be further reduced by extending the network, e.g., from 10 to 70 stations, which is

  13. Glacial interglacial rain ratio changes: Implications for atmospheric CO2 and ocean sediment interaction

    Science.gov (United States)

    Munhoven, Guy

    2007-03-01

    A reduction of the carbonate-carbon to organic-carbon export rain ratio during glacial times has been advanced to explain the glacial-interglacial atmospheric CO2 variations. This hypothesis is tested and implications for the dynamics of sedimentary carbonate preservation and dissolution are explored with a multi-box model ( MBM) of the ocean carbon cycle, fully coupled to a new transient early diagenesis model (called MEDUSA). A peak reduction of the rain ratio by 40% at the Last Glacial Maximum (LGM) was found to produce a net atmospheric pCO2 reduction of about 40 ppm. Changing shelf carbonate accumulation rates and continental weathering inputs produced a 55-60 ppm reduction. The combination of the two mechanisms generates a pCO2 change of 90-95 ppm, which compares well with the observed data. However, the resulting model sedimentary record does not conform to actual sedimentary records. The changes related to continental shelf processes and variable weathering flux depress the calcite saturation horizon (CSH) by about 1 km at the LGM; if rain ratio variations are also considered, that depression increases by another km. In addition to this large amplitude for the CSH, possibly due to the adopted box-model approach, the changing rain ratio also leads to transition zone changes in the model sedimentary record that are opposite in phase with data-based reconstructions. Realistic changes in the aragonite fraction of the carbonate rain were found to have only a minimal impact on atmospheric pCO2. Finally, chemical erosion of deep-sea sediment was shown to reduce the amplitude of variation of the sedimentary CCD by about 10-20%. It may provide a mechanism to improve the model-data agreement.

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

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    WU HongYan; ZOU DingHui; GAO KunShan

    2008-01-01

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

  16. Carbon isotope evidence implying high O2/CO2 ratios in the Permo-Carboniferous atmosphere

    Science.gov (United States)

    Beerling, D. J.; Lake, J. A.; Berner, R. A.; Hickey, L. J.; Taylor, D. W.; Royer, D. L.

    2002-11-01

    Theoretical models predict a marked increase in atmospheric O2 to ∼35% during the Permo-Carboniferous (∼300 Ma) occurring against a low (∼0.03%) CO2 level. An upper O2 value of 35%, however, remains disputed because ignition data indicate that excessive global forest fires would have ensued. This uncertainty limits interpretation of the role played by atmospheric oxygen in Late Paleozoic biotic evolution. Here, we describe new results from laboratory experiments with vascular land plants that establish that a rise in O2 to 35% increases isotopic fractionation (Δ13C) during growth relative to control plants grown at 21% O2. Despite some effect of the background atmospheric CO2 level on the magnitude of the increase, we hypothesize that a substantial Permo-Carboniferous rise in O2 could have imprinted a detectable geochemical signature in the plant fossil record. Over 50 carbon isotope measurements on intact carbon from four fossil plant clades with differing physiological ecologies and ranging in age from Devonian to Cretaceous reveal a substantial Δ13C anomaly (5‰) occurring between 300 and 250 Ma. The timing and direction of the Δ13C excursion is consistent with the effects of a high O2 atmosphere on plants, as predicted from photosynthetic theory and observed in our experiments. Preliminary calibration of the fossil Δ13C record against experimental data yields a predicted O2/CO2 mixing ratio of the ancient atmosphere consistent with that calculated from long-term models of the global carbon and oxygen cycles. We conclude that further work on the effects of O2 in the combustion of plant materials and the spread of wildfire is necessary before existing data can be used to reliably set the upper limit for paleo-O2 levels.

  17. H2O and CO2 exchange between a sphagnum mire ecosystem and the atmosphere

    Science.gov (United States)

    Olchev, Alexander; Volkova, Elena; Karataeva, Tatiana; Novenko, Elena

    2013-04-01

    The modern climatic conditions are strongly influenced by both internal variability of climatic system, and various external natural and anthropogenic factors (IPCC 2007). Significant increase of concentration of greenhouse gases in the atmosphere and especially the growth of atmospheric CO2 due to human activity are considered as the main factors that are responsible for modern global warming and climate changes. A significant part of anthropogenic CO2 is absorbed from the atmosphere by land biota and especially by vegetation cover. However, it is still not completely clear what is the role of different land ecosystems and especially forests and mires in global cycles of H2O and CO2 and what is a sensitivity of these ecosystems to climate changes. Within the framework of this study the spatial and temporal variability of H2O and CO2 fluxes between a mire ecosystem and the atmosphere was described using results of the field measurements and modeling approach. For the study a mire ecosystem located in Tula region in European part of Russia was selected. The selected mire has karst origin, depth of peat float is 2.5-3.0 m (depth of depression is more than 10 meter), area is about 1 ha. The mire vegetation is characterized by sedge and sphagnum mosses cover. The mire is surrounded by broad-leaved forest of about 20 meter high. To describe the temporal and spatial patterns of H2O and CO2 fluxes within selected mire the chamber method was applied. The measurement were carried out along transect from mire edge to center from June to September of 2012. For measurements the transparent ventilated chambers combined with portable infrared CO2/H2O analyzer LI-840 (Li-Cor, USA) was used. To estimate the gross primary production and respiration of different type of vegetation within the mire the measurements were conducted both under actual light conditions and artificial shading. Results of the experimental studies showed that the maximal CO2 fluxes was observed in central

  18. Nitrogen and Carbon Cycling in a Grassland Community Ecosystem as Affected by Elevated Atmospheric CO2

    Directory of Open Access Journals (Sweden)

    H. A. Torbert

    2012-01-01

    Full Text Available Increasing global atmospheric carbon dioxide (CO2 concentration has led to concerns regarding its potential effects on terrestrial ecosystems and the long-term storage of carbon (C and nitrogen (N in soil. This study examined responses to elevated CO2 in a grass ecosystem invaded with a leguminous shrub Acacia farnesiana (L. Willd (Huisache. Seedlings of Acacia along with grass species were grown for 13 months at CO2 concentrations of 385 (ambient, 690, and 980 μmol mol−1. Elevated CO2 increased both C and N inputs from plant growth which would result in higher soil C from litter fall, root turnover, and excretions. Results from the incubation indicated an initial (20 days decrease in N mineralization which resulted in no change in C mineralization. However, after 40 and 60 days, an increase in both C and N mineralization was observed. These increases would indicate that increases in soil C storage may not occur in grass ecosystems that are invaded with Acacia over the long term.

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

    Science.gov (United States)

    Hussain Laskar, Amzad; Liang, Mao-Chang

    2016-09-01

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

  20. Evidence for a biological pump driver of atmospheric CO2 rise during Heinrich Stadial 1

    Science.gov (United States)

    Hertzberg, Jennifer E.; Lund, David C.; Schmittner, Andreas; Skrivanek, Alexandra L.

    2016-12-01

    The initial trigger of the atmospheric CO2 rise during Heinrich Stadial 1 (HS1: 14.5-17.5 kyr B.P.) remains elusive. We present a compilation of four paired surface and intermediate-depth foraminiferal δ13C records to test whether reduced biological pump efficiency led to the initial CO2 rise during the last deglaciation. Surface ocean δ13C decreased across HS1 while intermediate-depth δ13C increased, leading to a reduction in the upper ocean δ13C gradient. Our compilation also suggests the δ13C gradient increased during the Bølling-Allerød (12.9-14.5 kyr B.P.) and decreased during the Younger Dryas (YD: 11.7-12.9 kyr B.P.). The HS1 and YD data are consistent with reduced biological export of isotopically light carbon from the surface ocean and its remineralization at depth. Our results support the idea that a weaker Atlantic Meridional Overturning Circulation decreased biological pump efficiency by increasing the overall fraction of preformed nutrients in the global ocean, leading to an increase in atmospheric CO2.

  1. Elevated atmospheric CO2 increases water use efficiency in Florida scrub oak

    Science.gov (United States)

    Drake, B. G.; Hayek, L. C.; Johnson, D. P.; Li, J.; Powell, T. L.

    2009-12-01

    Plants are expected to have higher rates of photosynthesis and reduced transpiration as atmospheric CO2 (Ca) continues to rise. But will higher Ca reduce water loss, and increase water use efficiency and soil water in native ecosystems? We tested this question using large (3.0m by 2.8m) open top chambers to expose Florida scrub oak on Merritt Island Wildlife Refuge, Kennedy Space Center, FL, from May 1996 to June 2007 to elevated levels of atmospheric CO2, (Ce = Ca + 350ppm) compared to ambient Ca. Although Ce stimulated total shoot biomass 68% by the end of the study, the effect of Ce on annual growth declined each year (Seiler et al. 2009, Global Change Biology15, 356-367). Compared with the effects of Ca, Ce increased net ecosystem CO2 exchange approximately 70% on average for the entire study, increased leaf area index (LAI) seasonally, reduced evapotranspiration except during mid-summer of some years, and, depending on the relative effect of Ce on LAI, increased volumetric soil water content.. These results are consistent with the observation that continental river discharge has increased as Ca has risen throughout the past 50 years (Gedney et al., Nature, Vol. 439, 16 February 2006).

  2. A permafrost glacial hypothesis to explain atmospheric CO2 and the ice ages during the Pleistocene

    Directory of Open Access Journals (Sweden)

    R. Tarozo

    2010-10-01

    Full Text Available Over the past several 100 ka glacial-interglacial cycles, the concentration of atmospheric CO2 was closely coupled to global temperature, which indicates the importance of CO2 as a greenhouse gas. The reasons for changes in atmospheric CO2 have mainly been sought in the ocean, yet proxy evidence does not support the notion of increased oceanic carbon storage during glacials. Here we present results from the first permafrost loess sequence in Siberia spanning two glacial cycles (~240 ka, which reveal that permafrost soils repeatedly sequestered huge amounts of terrestrial carbon during glacial periods. This can be explained with permafrost favouring more intensive waterlogging conditions and better preservation of soil organic matter. Terrestrial carbon stored in permafrost soils was released upon warming and provided a powerful feedback mechanism for the glacial terminations. We outline a "permafrost glacial hypothesis" building on integrated annual insolation forcing, which readily explains the observed succession of the ice ages during the Pleistocene, including the mid-Pleistocene transition.

  3. Shellfish face uncertain future in high CO2 world: influence of acidification on oyster larvae calcification and growth in estuaries.

    Directory of Open Access Journals (Sweden)

    A Whitman Miller

    Full Text Available BACKGROUND: Human activities have increased atmospheric concentrations of carbon dioxide by 36% during the past 200 years. One third of all anthropogenic CO(2 has been absorbed by the oceans, reducing pH by about 0.1 of a unit and significantly altering their carbonate chemistry. There is widespread concern that these changes are altering marine habitats severely, but little or no attention has been given to the biota of estuarine and coastal settings, ecosystems that are less pH buffered because of naturally reduced alkalinity. METHODOLOGY/PRINCIPAL FINDINGS: To address CO(2-induced changes to estuarine calcification, veliger larvae of two oyster species, the Eastern oyster (Crassostrea virginica, and the Suminoe oyster (Crassostrea ariakensis were grown in estuarine water under four pCO(2 regimes, 280, 380, 560 and 800 microatm, to simulate atmospheric conditions in the pre-industrial era, present, and projected future concentrations in 50 and 100 years respectively. CO(2 manipulations were made using an automated negative feedback control system that allowed continuous and precise control over the pCO(2 in experimental aquaria. Larval growth was measured using image analysis, and calcification was measured by chemical analysis of calcium in their shells. C. virginica experienced a 16% decrease in shell area and a 42% reduction in calcium content when pre-industrial and end of 21(st century pCO(2 treatments were compared. C. ariakensis showed no change to either growth or calcification. Both species demonstrated net calcification and growth, even when aragonite was undersaturated, a result that runs counter to previous expectations for invertebrate larvae that produce aragonite shells. CONCLUSIONS AND SIGNIFICANCE: Our results suggest that temperate estuarine and coastal ecosystems are vulnerable to the expected changes in water chemistry due to elevated atmospheric CO(2 and that biological responses to acidification, especially calcifying

  4. GEOCARBSULF: A combined model for Phanerozoic atmospheric O 2 and CO 2

    Science.gov (United States)

    Berner, Robert A.

    2006-12-01

    A model for the combined long-term cycles of carbon and sulfur has been constructed which combines all the factors modifying weathering and degassing of the GEOCARB III model [Berner R.A., Kothavala Z., 2001. GEOCARB III: a revised model of atmospheric CO 2 over Phanerozoic time. Am. J. Sci. 301, 182-204] for CO 2 with rapid recycling and oxygen dependent carbon and sulfur isotope fractionation of an isotope mass balance model for O 2 [Berner R.A., 2001. Modeling atmospheric O 2 over Phanerozoic time. Geochim. Cosmochim. Acta65, 685-694]. New isotopic data for both carbon and sulfur are used and new feedbacks are created by combining the models. Sensitivity analysis is done by determining (1) the effect on weathering rates of using rapid recycling (rapid recycling treats carbon and sulfur weathering in terms of young rapidly weathering rocks and older more slowly weathering rocks); (2) the effect on O 2 of using different initial starting conditions; (3) the effect on O 2 of using different data for carbon isotope fractionation during photosynthesis and alternative values of oceanic δ13C for the past 200 million years; (4) the effect on sulfur isotope fractionation and on O 2 of varying the size of O 2 feedback during sedimentary pyrite formation; (5) the effect on O 2 of varying the dependence of organic matter and pyrite weathering on tectonic uplift plus erosion, and the degree of exposure of coastal lands by sea level change; (6) the effect on CO 2 of adding the variability of volcanic rock weathering over time [Berner, R.A., 2006. Inclusion of the weathering of volcanic rocks in the GEOCARBSULF model. Am. J. Sci.306 (in press)]. Results show a similar trend of atmospheric CO 2 over the Phanerozoic to the results of GEOCARB III, but with some differences during the early Paleozoic and, for variable volcanic rock weathering, lower CO 2 values during the Mesozoic. Atmospheric oxygen shows a major broad late Paleozoic peak with a maximum value of about 30% O 2 in

  5. Escape of Mars' CO2 atmosphere by suprathermal atoms during the past 4 Gyrs

    Science.gov (United States)

    Amerstorfer, Ute; Gröller, Hannes; Lichtenegger, Herbert; Lammer, Helmut; Tian, Feng

    2016-04-01

    The escape of atmospheric particles plays a crucial role in the evolution of the atmosphere of Mars. Especially, the escape of oxygen and carbon is thought to have influenced its amount of CO2. With a Monte-Carlo model we investigate the escape of hot oxygen and carbon from the martian atmosphere for three points in time in its history corresponding to 3, 10, and 20 times the present EUV level. We study and discuss different possible sources of hot oxygen and carbon atoms in the thermosphere and their changing importance with the EUV flux. We find that the escape due to photodissociation increases with increasing EUV level, as is a commonly assumed opinion. However, for the escape via other reactions, e.g. dissociative recombination, this is only true until the EUV level reaches 10 times the present EUV flux, but then the rates start to decrease. Our results thus suggest that some escape mechanisms related to the loss of CO2 are less important than previously thought for atmospheres exposed to higher EUV radiation. This work receives funding from the Austrian Science Fund (FWF): P 24247-N16.

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

    Science.gov (United States)

    Lu, J.; Yu, J.

    2013-12-01

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

  7. Thermal infrared laser heterodyne spectroradiometry for solar occultation atmospheric CO2 measurements

    Science.gov (United States)

    Hoffmann, Alex; Macleod, Neil A.; Huebner, Marko; Weidmann, Damien

    2016-12-01

    This technology demonstration paper reports on the development, demonstration, performance assessment, and initial data analysis of a benchtop prototype quantum cascade laser heterodyne spectroradiometer, operating within a narrow spectral window of ˜ 1 cm-1 around 953.1 cm-1 in transmission mode and coupled to a passive Sun tracker. The instrument has been specifically designed for accurate dry air total column, and potentially vertical profile, measurements of CO2. Data from over 8 months of operation in 2015 near Didcot, UK, confirm that atmospheric measurements with noise levels down to 4 times the shot noise limit can be achieved with the current instrument. Over the 8-month period, spectra with spectral resolutions of 60 MHz (0.002 cm-1) and 600 MHz (0.02 cm-1) have been acquired with median signal-to-noise ratios of 113 and 257, respectively, and a wavenumber calibration uncertainty of 0.0024 cm-1.Using the optimal estimation method and RFM as the radiative transfer forward model, prior analysis and theoretical benchmark modelling had been performed with an observation system simulator (OSS) to target an optimized spectral region of interest. The selected narrow spectral window includes both CO2 and H2O ro-vibrational transition lines to enable the measurement of dry air CO2 column from a single spectrum. The OSS and preliminary retrieval results yield roughly 8 degrees of freedom for signal (over the entire state vector) for an arbitrarily chosen a priori state with relatively high uncertainty ( ˜ 4 for CO2). Preliminary total column mixing ratios obtained are consistent with GOSAT monthly data. At a spectral resolution of 60 MHz with an acquisition time of 90 s, instrumental noise propagation yields an error of around 1.5 ppm on the dry air total column of CO2, exclusive of biases and geophysical parameters errors at this stage.

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

    Science.gov (United States)

    Zimnoch, Miroslaw; Jasek, Alina; Rozanski, Kazimierz

    2014-05-01

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

  9. Contribution of various carbon sources toward isoprene synthesis mediated by altered atmospheric CO2 concentrations

    Science.gov (United States)

    Trowbridge, A. M.; Asensio, D.; Eller, A. S.; Wilkinson, M. J.; Schnitzler, J.; Jackson, R. B.; Monson, R. K.

    2010-12-01

    Biogenically released isoprene is abundant in the troposphere, and has an essential function in determining atmospheric chemistry and important implications for plant metabolism. As a result, considerable effort has been made to understand the underlying mechanisms driving isoprene synthesis, particularly in the context of a rapidly changing environment. Recently, a number of studies have focused on the contribution of recently assimilated carbon as opposed to stored/alternative intracellular or extracellular carbon sources in the context of environmental stress. Results from these studies can offer clues about the importance of various carbon pools for isoprene production and elucidate the corresponding physiological changes that are responsible for these dynamic shifts in carbon allocation. We performed a 13CO2-labeling study using proton-transfer-reaction mass spectrometry (PTR-MS) to examine the kinetics of the incorporation of recently assimilated photosynthate into isoprene emitted from poplar (Poplar x canescens) under sub-ambient, ambient, and elevated CO2 growth conditions. We also monitored the importance of pyruvate-derived carbon for isoprene biosynthesis and obtained a detailed account of where individual carbons are derived from by analyzing the ratio of the 3C subunit of isoprene (M41+) (a fragment which contains two carbons from pyruvate) to the ratio of the parent isoprene molecule (M69+). Dynamics in the M41+:M69+ ratio indicate that recently assimilated carbon is incorporated into the pyruvate carbon pool slowly across all CO2 treatments and is therefore accessible for isoprene synthesis at a slower rate when compared to substrates derived directly from photosynthesis. Analysis of the rates of change for individual masses indicated that the carbon pools in trees grown in sub-ambient CO2 (200 ppm) are labeled ~2 times faster than those of trees grown in ambient or elevated CO2. Analysis of the total isoprene emission rates between treatments

  10. Regional inversion of CO2 ecosystem fluxes from atmospheric measurements. Reliability of the uncertainty estimates

    Energy Technology Data Exchange (ETDEWEB)

    Broquet, G.; Chevallier, F.; Breon, F.M.; Yver, C.; Ciais, P.; Ramonet, M.; Schmidt, M. [Laboratoire des Sciences du Climat et de l' Environnement, CEA-CNRS-UVSQ, UMR8212, IPSL, Gif-sur-Yvette (France); Alemanno, M. [Servizio Meteorologico dell' Aeronautica Militare Italiana, Centro Aeronautica Militare di Montagna, Monte Cimone/Sestola (Italy); Apadula, F. [Research on Energy Systems, RSE, Environment and Sustainable Development Department, Milano (Italy); Hammer, S. [Universitaet Heidelberg, Institut fuer Umweltphysik, Heidelberg (Germany); Haszpra, L. [Hungarian Meteorological Service, Budapest (Hungary); Meinhardt, F. [Federal Environmental Agency, Kirchzarten (Germany); Necki, J. [AGH University of Science and Technology, Krakow (Poland); Piacentino, S. [ENEA, Laboratory for Earth Observations and Analyses, Palermo (Italy); Thompson, R.L. [Max Planck Institute for Biogeochemistry, Jena (Germany); Vermeulen, A.T. [Energy research Centre of the Netherlands ECN, EEE-EA, Petten (Netherlands)

    2013-07-01

    The Bayesian framework of CO2 flux inversions permits estimates of the retrieved flux uncertainties. Here, the reliability of these theoretical estimates is studied through a comparison against the misfits between the inverted fluxes and independent measurements of the CO2 Net Ecosystem Exchange (NEE) made by the eddy covariance technique at local (few hectares) scale. Regional inversions at 0.5{sup 0} resolution are applied for the western European domain where {approx}50 eddy covariance sites are operated. These inversions are conducted for the period 2002-2007. They use a mesoscale atmospheric transport model, a prior estimate of the NEE from a terrestrial ecosystem model and rely on the variational assimilation of in situ continuous measurements of CO2 atmospheric mole fractions. Averaged over monthly periods and over the whole domain, the misfits are in good agreement with the theoretical uncertainties for prior and inverted NEE, and pass the chi-square test for the variance at the 30% and 5% significance levels respectively, despite the scale mismatch and the independence between the prior (respectively inverted) NEE and the flux measurements. The theoretical uncertainty reduction for the monthly NEE at the measurement sites is 53% while the inversion decreases the standard deviation of the misfits by 38 %. These results build confidence in the NEE estimates at the European/monthly scales and in their theoretical uncertainty from the regional inverse modelling system. However, the uncertainties at the monthly (respectively annual) scale remain larger than the amplitude of the inter-annual variability of monthly (respectively annual) fluxes, so that this study does not engender confidence in the inter-annual variations. The uncertainties at the monthly scale are significantly smaller than the seasonal variations. The seasonal cycle of the inverted fluxes is thus reliable. In particular, the CO2 sink period over the European continent likely ends later than

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

    Science.gov (United States)

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

    2016-05-19

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

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

    Science.gov (United States)

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

    2016-05-01

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

  13. The potential for regional-scale bias in top-down CO2 flux estimates due to atmospheric transport errors

    Directory of Open Access Journals (Sweden)

    S. M. Miller

    2014-09-01

    Full Text Available Estimates of CO2 fluxes that are based on atmospheric data rely upon a meteorological model to simulate atmospheric CO2 transport. These models provide a quantitative link between surface fluxes of CO2 and atmospheric measurements taken downwind. Therefore, any errors in the meteorological model can propagate into atmospheric CO2 transport and ultimately bias the estimated CO2 fluxes. These errors, however, have traditionally been difficult to characterize. To examine the effects of CO2 transport errors on estimated CO2 fluxes, we use a global meteorological model-data assimilation system known as "CAM–LETKF" to quantify two aspects of the transport errors: error variances (standard deviations and temporal error correlations. Furthermore, we develop two case studies. In the first case study, we examine the extent to which CO2 transport uncertainties can bias CO2 flux estimates. In particular, we use a common flux estimate known as CarbonTracker to discover the minimum hypothetical bias that can be detected above the CO2 transport uncertainties. In the second case study, we then investigate which meteorological conditions may contribute to month-long biases in modeled atmospheric transport. We estimate 6 hourly CO2 transport uncertainties in the model surface layer that range from 0.15 to 9.6 ppm (standard deviation, depending on location, and we estimate an average error decorrelation time of ∼2.3 days at existing CO2 observation sites. As a consequence of these uncertainties, we find that CarbonTracker CO2 fluxes would need to be biased by at least 29%, on average, before that bias were detectable at existing non-marine atmospheric CO2 observation sites. Furthermore, we find that persistent, bias-type errors in atmospheric transport are associated with consistent low net radiation, low energy boundary layer conditions. The meteorological model is not necessarily more uncertain in these conditions. Rather, the extent to which meteorological

  14. The potential for regional-scale bias in top-down CO2 flux estimates due to atmospheric transport errors

    Science.gov (United States)

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

    2014-09-01

    Estimates of CO2 fluxes that are based on atmospheric data rely upon a meteorological model to simulate atmospheric CO2 transport. These models provide a quantitative link between surface fluxes of CO2 and atmospheric measurements taken downwind. Therefore, any errors in the meteorological model can propagate into atmospheric CO2 transport and ultimately bias the estimated CO2 fluxes. These errors, however, have traditionally been difficult to characterize. To examine the effects of CO2 transport errors on estimated CO2 fluxes, we use a global meteorological model-data assimilation system known as "CAM-LETKF" to quantify two aspects of the transport errors: error variances (standard deviations) and temporal error correlations. Furthermore, we develop two case studies. In the first case study, we examine the extent to which CO2 transport uncertainties can bias CO2 flux estimates. In particular, we use a common flux estimate known as CarbonTracker to discover the minimum hypothetical bias that can be detected above the CO2 transport uncertainties. In the second case study, we then investigate which meteorological conditions may contribute to month-long biases in modeled atmospheric transport. We estimate 6 hourly CO2 transport uncertainties in the model surface layer that range from 0.15 to 9.6 ppm (standard deviation), depending on location, and we estimate an average error decorrelation time of ∼2.3 days at existing CO2 observation sites. As a consequence of these uncertainties, we find that CarbonTracker CO2 fluxes would need to be biased by at least 29%, on average, before that bias were detectable at existing non-marine atmospheric CO2 observation sites. Furthermore, we find that persistent, bias-type errors in atmospheric transport are associated with consistent low net radiation, low energy boundary layer conditions. The meteorological model is not necessarily more uncertain in these conditions. Rather, the extent to which meteorological uncertainties

  15. Assessment of model estimates of land-atmosphere CO2 exchange across Northern Eurasia

    Science.gov (United States)

    Rawlins, M. A.; McGuire, A. D.; Kimball, J. S.; Dass, P.; Lawrence, D.; Burke, E.; Chen, X.; Delire, C.; Koven, C.; MacDougall, A.; Peng, S.; Rinke, A.; Saito, K.; Zhang, W.; Alkama, R.; Bohn, T. J.; Ciais, P.; Decharme, B.; Gouttevin, I.; Hajima, T.; Ji, D.; Krinner, G.; Lettenmaier, D. P.; Miller, P.; Moore, J. C.; Smith, B.; Sueyoshi, T.

    2015-07-01

    A warming climate is altering land-atmosphere exchanges of carbon, with a potential for increased vegetation productivity as well as the mobilization of permafrost soil carbon stores. Here we investigate land-atmosphere carbon dioxide (CO2) cycling through analysis of net ecosystem productivity (NEP) and its component fluxes of gross primary productivity (GPP) and ecosystem respiration (ER) and soil carbon residence time, simulated by a set of land surface models (LSMs) over a region spanning the drainage basin of Northern Eurasia. The retrospective simulations cover the period 1960-2009 at 0.5° resolution, which is a scale common among many global carbon and climate model simulations. Model performance benchmarks were drawn from comparisons against both observed CO2 fluxes derived from site-based eddy covariance measurements as well as regional-scale GPP estimates based on satellite remote-sensing data. The site-based comparisons depict a tendency for overestimates in GPP and ER for several of the models, particularly at the two sites to the south. For several models the spatial pattern in GPP explains less than half the variance in the MODIS MOD17 GPP product. Across the models NEP increases by as little as 0.01 to as much as 0.79 g C m-2 yr-2, equivalent to 3 to 340 % of the respective model means, over the analysis period. For the multimodel average the increase is 135 % of the mean from the first to last 10 years of record (1960-1969 vs. 2000-2009), with a weakening CO2 sink over the latter decades. Vegetation net primary productivity increased by 8 to 30 % from the first to last 10 years, contributing to soil carbon storage gains. The range in regional mean NEP among the group is twice the multimodel mean, indicative of the uncertainty in CO2 sink strength. The models simulate that inputs to the soil carbon pool exceeded losses, resulting in a net soil carbon gain amid a decrease in residence time. Our analysis points to improvements in model elements

  16. Assessment of model estimates of land–atmosphere CO2 exchange across Northern Eurasia

    Directory of Open Access Journals (Sweden)

    M. A. Rawlins

    2015-02-01

    Full Text Available A warming climate is altering land–atmosphere exchanges of carbon, with a potential for increased vegetation productivity as well as the mobilization of permafrost soil carbon stores. Here we investigate land–atmosphere carbon dioxide (CO2 dynamics through analysis of net ecosystem productivity (NEP and its component fluxes of gross primary productivity (GPP and ecosystem respiration (ER and soil carbon residence time, simulated by a set of land surface models (LSMs over a region spanning the drainage basin of northern Eurasia. The retrospective simulations were conducted over the 1960–2009 record and at 0.5° resolution, which is a scale common among many global carbon and climate model simulations. Model performance benchmarks were drawn from comparisons against both observed CO2 fluxes derived from site-based eddy covariance measurements as well as regional-scale GPP estimates based on satellite remote sensing data. The site-based comparisons show the timing of peak GPP to be well simulated. Modest overestimates in model GPP and ER are also found, which are relatively higher for two boreal forest validation sites than the two tundra sites. Across the suite of model simulations, NEP increases by as little as 0.01 to as much as 0.79 g C m−2 yr−2, equivalent to 3 to 340% of the respective model means, over the analysis period. For the multimodel average the increase is 135% of the mean from the first to last ten years of record (1960–1969 vs 2000–2009, with a weakening CO2 sink over the latter decades. Vegetation net primary productivity increased by 8 to 30% from the first to last ten years, contributing to soil carbon storage gains, while model mean residence time for soil organic carbon decreased by 10% (−5 to −16%. This suggests that inputs to the soil carbon pool exceeded losses, resulting in a net gain amid a decrease in residence time. Our analysis points to improvements in model elements controlling vegetation

  17. Assessment of model estimates of land-atmosphere CO2 exchange across northern Eurasia

    Science.gov (United States)

    Rawlins, M.A.; McGuire, A.D.; Kimball, J.S.; Dass, P.; Lawrence, D.; Burke, E.; Chen, X.; Delire, C.; Koven, C.; MacDougall, A.; Peng, S.; Rinke, A.; Saito, K.; Zhang, W.; Alkama, R.; Bohn, T. J.; Ciais, P.; Decharme, B.; Gouttevin, I.; Hajima, T.; Ji, D.; Krinner, G.; Lettenmaier, D.P.; Miller, P.; Moore, J.C.; Smith, B.; Sueyoshi, T.

    2015-01-01

    A warming climate is altering land-atmosphere exchanges of carbon, with a potential for increased vegetation productivity as well as the mobilization of permafrost soil carbon stores. Here we investigate land-atmosphere carbon dioxide (CO2) cycling through analysis of net ecosystem productivity (NEP) and its component fluxes of gross primary productivity (GPP) and ecosystem respiration (ER) and soil carbon residence time, simulated by a set of land surface models (LSMs) over a region spanning the drainage basin of Northern Eurasia. The retrospective simulations cover the period 1960–2009 at 0.5° resolution, which is a scale common among many global carbon and climate model simulations. Model performance benchmarks were drawn from comparisons against both observed CO2 fluxes derived from site-based eddy covariance measurements as well as regional-scale GPP estimates based on satellite remote-sensing data. The site-based comparisons depict a tendency for overestimates in GPP and ER for several of the models, particularly at the two sites to the south. For several models the spatial pattern in GPP explains less than half the variance in the MODIS MOD17 GPP product. Across the models NEP increases by as little as 0.01 to as much as 0.79 g C m−2 yr−2, equivalent to 3 to 340 % of the respective model means, over the analysis period. For the multimodel average the increase is 135 % of the mean from the first to last 10 years of record (1960–1969 vs. 2000–2009), with a weakening CO2 sink over the latter decades. Vegetation net primary productivity increased by 8 to 30 % from the first to last 10 years, contributing to soil carbon storage gains. The range in regional mean NEP among the group is twice the multimodel mean, indicative of the uncertainty in CO2 sink strength. The models simulate that inputs to the soil carbon pool exceeded losses, resulting in a net soil carbon gain amid a decrease in residence time. Our analysis points to improvements in model

  18. Responses of wheat and rice to factorial combinations of ambient and elevated CO2 and temperature in FACE experiments.

    Science.gov (United States)

    Cai, Chuang; Yin, Xinyou; He, Shuaiqi; Jiang, Wenyu; Si, Chuanfei; Struik, Paul C; Luo, Weihong; Li, Gang; Xie, Yingtian; Xiong, Yan; Pan, Genxing

    2016-02-01

    Elevated CO2 and temperature strongly affect crop production, but understanding of the crop response to combined CO2 and temperature increases under field conditions is still limited while data are scarce. We grew wheat (Triticum aestivum L.) and rice (Oryza sativa L.) under two levels of CO2 (ambient and enriched up to 500 μmol mol(-1) ) and two levels of canopy temperature (ambient and increased by 1.5-2.0 °C) in free-air CO2 enrichment (FACE) systems and carried out a detailed growth and yield component analysis during two growing seasons for both crops. An increase in CO2 resulted in higher grain yield, whereas an increase in temperature reduced grain yield, in both crops. An increase in CO2 was unable to compensate for the negative impact of an increase in temperature on biomass and yield of wheat and rice. Yields of wheat and rice were decreased by 10-12% and 17-35%, respectively, under the combination of elevated CO2 and temperature. The number of filled grains per unit area was the most important yield component accounting for the effects of elevated CO2 and temperature in wheat and rice. Our data showed complex treatment effects on the interplay between preheading duration, nitrogen uptake, tillering, leaf area index, and radiation-use efficiency, and thus on yield components and yield. Nitrogen uptake before heading was crucial in minimizing yield loss due to climate change in both crops. For rice, however, a breeding strategy to increase grain number per m(2) and % filled grains (or to reduce spikelet sterility) at high temperature is also required to prevent yield reduction under conditions of global change.

  19. Atmospheric CO2 Consumption in Uplifting Mountain Ranges: New Insight From the New Zealand Southern Alps

    Science.gov (United States)

    Jacobson, A. D.; Blum, J. D.; Chamberlain, C. P.

    2004-12-01

    Rates of physical erosion and chemical weathering in uplifting mountain ranges are generally higher than the rates observed in tectonically stable regions. This observation has led to the hypothesis that orogenic events lead to global cooling over geologic time scales by accelerating the rate of atmospheric CO2 drawdown from silicate weathering. However, recent studies of rivers draining the rapidly uplifting Himalaya Mountains have demonstrated that much of the chemical weathering flux is dominated by carbonate dissolution, which does not influence long-term atmospheric CO2 levels. To examine if carbonate weathering dominates in other orogenic environments, we have undertaken investigations of rivers draining the New Zealand Southern Alps, which present a largely unexplored setting for systematically examining tectonic controls on the carbon cycle. In particular, we quantified rates of physical erosion and both silicate and carbonate weathering across a gradient of variable uplift rates but constant bedrock composition. We also compared the findings to global mean values as well as to data for major world rivers in other tectonic and climatic settings. Rapid uplift in the western Southern Alps elevates mechanical erosion rates by a factor of ~13 relative to those on the tectonically stable eastern side. Similarly, the average chemical weathering rate is ~5 times higher on the western compared to eastern side of the mountain range. However, because the proportion of stream-water Ca2+ and Mg2+ from the weathering of trace hydrothermal calcite increases as the rate of mechanical erosion increases, the long-term atmospheric CO2 consumption rate on the western side is only ~2 times higher than that on the eastern side and only ~1.5 times higher than the global mean value. These data demonstrate that tectonic uplift in the New Zealand Southern Alps accelerates physical erosion and chemical weathering rates but does not greatly enhance the rate of long-term atmospheric

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

    Directory of Open Access Journals (Sweden)

    Xiang Gou

    2015-10-01

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

  1. Porous Ionic Polymers as a Robust and Efficient Platform for Capture and Chemical Fixation of Atmospheric CO2.

    Science.gov (United States)

    Sun, Qi; Jin, Yingyin; Aguila, Briana; Meng, Xiangju; Ma, Shengqian; Xiao, Feng-Shou

    2017-03-22

    Direct use of atmospheric CO2 as a C1 source to synthesize high-value chemicals through environmentally benign processes is of great interest, yet challenging. Porous heterogeneous catalysts that are capable of simultaneously capturing and converting CO2 are promising candidates for such applications. Herein, a family of organic ionic polymers with nanoporous structure, large surface area, strong affinity for CO2 , and very high density of catalytic active sites (halide ions) was synthesized through the free-radical polymerization of vinylfunctionalized quaternary phosphonium salts. The resultant porous ionic polymers (PIPs) exhibit excellent activities in the cycloaddition of epoxides with atmospheric CO2 , outperforming the corresponding soluble phosphonium salt analogues and ranking among the highest of known metal-free catalytic systems. The high CO2 uptake capacity of the PIPs facilitates the enrichment of CO2 molecules around the catalytic centers, thereby benefiting its conversion. We have demonstrated for the first time that atmospheric CO2 can be directly converted to cyclic carbonates at room temperature using a heterogeneous catalytic system under metal-solvent free conditions. Moreover, the catalysts proved to be robust and fully recyclable, demonstrating promising potential for practical utilization for the chemical fixation of CO2 . Our work thereby paves a way to the advance of PIPs as a new type of platform for capture and conversion of CO2 .

  2. CHEMICAL WEATHERING PROCESSES AND ATMOSPHERIC CO2 CONSUMPTION OF HUANGHE RIVER AND CHANGJIANG RIVER BASINS

    Institute of Scientific and Technical Information of China (English)

    LI Jing-ying; ZHANG Jing

    2005-01-01

    Rock weathering plays an important role in studying the long-term carbon cycles and global climaticchange. According to the statistics analysis, the Huanghe (Yellow) River water chemistry was mainly controlled byevaporite and carbonate weathering, which were responsible for over 90% of total dissolved ions. As compared withthe Huanghe River basin, dissolved load of the Changjiang (Yangtze) River was mainly originated from the carbonate dissolution.The chemical weathering rates were estimated to be 39.29t/(km2·a)and 61.58t/(km2·a)by deduting the HCO3- derived from atmosphere in the Huanghe River and Changjiang River watersheds, respectively. The CO2 con-sumption rates by rock weathering were calculated to be 120.84 × 103mol/km2 and 452.46 × 103mol/km2 annually in thetwo basins, respectively. The total CO2 consumption of the two basins amounted to 918.51 × 109mol/a, accounting for3.83% of the world gross. In contrast to other world watersheds, the stronger evaporite reaction and infirm silicateweathering can explain such feature that CO2 consumption rates were lower than a global average, suggesting that thesequential weathering may be go on in the two Chinese drainage basins.

  3. Arctic sea ice and atmospheric circulation under the abrupt4xCO2 scenario

    Institute of Scientific and Technical Information of China (English)

    YU Xiaoyong; Annette Rinke; JI Duoying; CUI Xuefeng; John C Moore

    2014-01-01

    We analyze sea ice changes from eight different earth system models that have conducted experiment abrupt4xCO2 of the Coupled Model Intercomparison Project Phase 5 (CMIP5). In response to abrupt quadrupling of CO2 from preindustrial levels, Arctic temperatures dramatically rise by about 10°C—16°C in winter and the seasonal sea ice cycle and sea ice concentration are signiifcantly changed compared with the pre-industrial control simulations (piControl). Changes of Arctic sea ice concentration are spatially correlated with temperature patterns in all seasons and highest in autumn. Changes in sea ice are associated with changes in atmospheric circulation patterns at heights up to the jet stream. While the pattern of sea level pressure changes is generally similar to the surface air temperature change pattern, the wintertime 500 hPa circulation displays a positive Paciifc North America (PNA) anomaly under abrupt4xCO2-piControl. This large scale teleconnection may contribute to, or feedback on, the simulated sea ice cover change and is associated with an intensiifcation of the jet stream over East Asia and the north Paciifc in winter.

  4. CO2 laser doppler systems for the measurement of atmospheric winds and turbulence

    Science.gov (United States)

    Huffaker, R. M.

    1975-01-01

    Two CO2 laser doppler systems developed by NASA and some results obtained with them are discussed. A continuous wave, monostatic system for short-range wind measurement is described, and direct comparisons between the data obtained with it and with a cup-anemometer/wind vane system and a hot-wire anemometer show excellent agreement between the systems. Improvements being made in three CW, CO2 laser doppler systems, including a filter bank for optimized signal processing and a versatile scanning system, are noted. A pulsed CO2 system for measuring clear air turbulence is described, and results of test performance on board a Convair 990 are presented. It is noted that while the system was able to measure air speed and turbulence, the range of its transmitter-atmosphere-receiver was lower than predicted, and a difference of about 20 to 30 dB existed between the actual and theoretical turbulence measurements. Factors that may account for this loss are listed.

  5. Atmospheric observations of carbon monoxide and fossil fuel CO2 emissions from East Asia

    DEFF Research Database (Denmark)

    Turnbull, Jocelyn C.; Tans, Pieter P.; Lehman, Scott J.;

    2011-01-01

    Flask samples from two sites in East Asia, Tae-Ahn Peninsula, Korea (TAP), and Shangdianzi, China (SDZ), were measured for trace gases including CO2, CO and fossil fuel CO2(CO(2)ff, derived from Delta(CO2)-C-14 observations). The five-year TAP record shows high CO(2)ff when local air comes from t...

  6. Impacts of 3 years of elevated atmospheric CO2 on rhizosphere carbon flow and microbial community dynamics

    NARCIS (Netherlands)

    Drigo, B.; Kowalchuk, G.A.; Knapp, B.A.; Pijl, A.S.; Boschker, H.T.S.; Van Veen, J.A.

    2013-01-01

    Carbon (C) uptake by terrestrial ecosystems represents an important option for partially mitigating anthropogenic CO2 emissions. Short-term atmospheric elevated CO2 exposure has been shown to create major shifts in C flow routes and diversity of the active soil-borne microbial community. Long-term i

  7. Increased reliability of passive mode-locking a multi-atmosphere TE CO2 laser by injection mode-locking

    NARCIS (Netherlands)

    Goor, van F.A.

    1986-01-01

    By injection of manosecond pulses from an AM mode-locked TEA CO2 laser in a passive mode-locked multi-atmosphere TE CO2 laser the shot-to-shot reproducibility of the generated subnanosecond pulses was increased to almost 100%.

  8. Effects of elevated atmospheric CO2 and N fertilization on bahiagrass pastures in the Southeastern U.S.

    Science.gov (United States)

    The effects of elevated atmospheric CO2 on pasture systems remain understudied in the Southeastern US. A 10-year study of bahiagrass (Paspalum notatum Flüggé) response to elevated CO2 was established in 2005 using open top field chambers on a Blanton loamy sand (loamy siliceous, thermic, Grossarenic...

  9. TransCom model simulations of hourly atmospheric CO2: Experimental overview and diurnal cycle results for 2002

    NARCIS (Netherlands)

    Law, R. M.; Peters, W.; RöDenbeck, C.; Aulagnier, C.; Baker, I.; Bergmann, D. J.; Bousquet, P.; Brandt, J.; Bruhwiler, L.; Cameron-Smith, P. J.; Christensen, J. H.; Delage, F.; Denning, A. S.; Fan, S.; Geels, C.; Houweling, S.; Imasu, R.; Karstens, U.; Kawa, S. R.; Kleist, J.; Krol, M. C.; Lin, S.-J.; Lokupitiya, R.; Maki, T.; Maksyutov, S.; Niwa, Y.; Onishi, R.; Parazoo, N.; Patra, P. K.; Pieterse, G.; Rivier, L.; Satoh, M.; Serrar, S.; Taguchi, S.; Takigawa, M.; Vautard, R.; Vermeulen, A. T.; Zhu, Z.

    2008-01-01

    A forward atmospheric transport modeling experiment has been coordinated by the TransCom group to investigate synoptic and diurnal variations in CO2. Model simulations were run for biospheric, fossil, and air-sea exchange of CO2 and for SF6 and radon for 2000-2003. Twenty-five models or model varian

  10. Simulating low frequency changes in atmospheric CO2 during the last 740 000 years

    Directory of Open Access Journals (Sweden)

    P. Köhler

    2006-01-01

    Full Text Available Atmospheric CO2 measured in Antarctic ice cores shows a natural variability of 80 to 100 ppmv during the last four glacial cycles and variations of approximately 60 ppmv in the two cycles between 410 and 650 kyr BP. We here use various paleo-climatic records from the EPICA Dome C Antarctic ice core and from oceanic sediment cores covering the last 740 kyr to force the ocean/atmosphere/biosphere box model of the global carbon cycle BICYCLE in a forward mode over this time in order to interpret the natural variability of CO2. Our approach is based on the previous interpretation of carbon cycle variations during Termination I (Köhler et al., 2005a. In the absense of a process-based sediment module one main simplification of BICYCLE is that carbonate compensation is approximated by the temporally delayed restoration of deep ocean [CO32−]. Our results match the low frequency changes in CO2 measured in the Vostok and the EPICA Dome C ice core for the last 650 kyr BP (r2≈0.75. During these transient simulations the carbon cycle reaches never a steady state due to the ongoing variability of the overall carbon budget caused by the time delayed response of the carbonate compensation to other processes. The average contributions of different processes to the rise in CO2 during Terminations I to V and during earlier terminations are: the rise in Southern Ocean vertical mixing: 36/22 ppmv, the rise in ocean temperature: 26/11 ppmv, iron limitation of the marine biota in the Southern Ocean: 20/14 ppmv, carbonate compensation: 15/7 ppmv, the rise in North Atlantic deep water formation: 13/0 ppmv, the rise in gas exchange due to a decreasing sea ice cover: −8/−7 ppmv, sea level rise: −12/−4 ppmv, and rising terrestrial carbon storage: −13/−6 ppmv. According to our model the smaller interglacial CO2 values in the pre-Vostok period prior to Termination V are mainly caused by smaller interglacial Southern Ocean SST and an Atlantic THC which stayed

  11. Using Mauna Loa Atmospheric CO2 Data in Large General Education Geoscience Courses

    Science.gov (United States)

    Richardson, R. M.; Kapp, J. L.

    2007-12-01

    We have been using the Mauna Loa atmospheric CO2 dataset (http://scrippsco2.ucsd.edu/data/in_situ_co2/monthly_mlo.csv) in a large (up to 300) General Education Geoscience course, primarily in small breakout groups (30 students). The exercise is designed to address quantitative literacy including percentages, slopes and linear trends, issues of data completeness and bias, quality of extrapolations, as well as implications for climate change. We are significantly revising the course, which serves 600 students a semester, with help from a curriculum grant. A major goal is to improve student learning by incorporating inquiry based activities in the large lecture setting. Lectures now incorporate several activities throughout a given class period, in which students are asked to use critical thinking skills such as interpreting patterns in data and graphs, analyzing a scientific hypothesis for its coherence with the scientific method, and answering higher order synthesis questions in both verbal and written form. This differs from our past format where class periods were dominated by lecture, with a single short activity done individually about every other lecture. To test the effectiveness of the new course format we will give students the same atmospheric CO2 exercise in the lecture setting that they were given previously in breakout groups. Students will work in small groups in lecture after receiving a short introduction to the exercise by the instructor. They will plot CO2 concentrations, make extrapolations, and interpret patterns in the data. We will compare scores on the exercise with previous semesters. We expect that students will do better having had more experience with interpreting scientific data and practicing higher order thinking skills. We also expect working in small groups will foster better learning through peer teaching and discussion. We will incorporate responses from students who took part in the exercises from current and previous semesters. We

  12. Fixing atmospheric CO2 by environment adaptive sorbent and renewable energy

    Science.gov (United States)

    Wang, T.; Liu, J.; Ge, K.; Fang, M.

    2014-12-01

    Fixing atmospheric CO2, followed by geologic storage in remote areas is considered an environmentally secure approach to climate mitigation. A moisture swing sorbent was investigated in the laboratory for CO2 capture at a remote area with humid and windy conditions. The energy requirement of moisture swing absorption could be greatly reduced compared to that of traditional high-temperature thermal swing, by assuming that the sorbent can be naturally dried and regenerated at ambient conditions. However, for currently developed moisture swing materials, the CO2 capacity would drop significantly at high relative humidity. The CO2 capture amount can be reduced by the poor thermodynamics and kinetics at high relative humidity or low temperature. Similar challenges also exist for thermal or vacuum swing sorbents. Developing sorbent materials which adapt to specific environments, such as high humidity or low temperature, can ensure sufficient capture capacity on the one hand, and realize better economics on the other hand (Figure 1) .An environment adaptive sorbent should have the abilities of tunable capacity and fast kinetics at extreme conditions, such as high humidity or low temperature. In this presentation, the possibility of tuning CO2 absorption capacity of a polymerized ionic liquid material is discussed. The energy requirement evaluation shows that tuning the CO2 binding energy of sorbent, rather than increasing the temperature or reducing the humidity of air, could be much more economic. By determining whether the absorption process is controlled by physical diffusion controlled or chemical reaction, an effective approach to fast kinetics at extreme conditions is proposed. A shrinking core model for mass transfer kinetics is modified to cope with the relatively poor kinetics of air capture. For the studied sample which has a heterogeneous structure, the kinetic analysis indicates a preference of sorbent particle size optimization, rather than support layer

  13. Terrestrial carbon cycle responses to drought and climate stress: New insights using atmospheric observations of CO2 and delta13C

    Science.gov (United States)

    Alden, Caroline B.

    Atmospheric concentrations of carbon dioxide (CO2) continue to rise well into the second decade of the new millennium, in spite of broad-scale human understanding of the impacts of fossil fuel emissions on the earth's climate. Natural sinks for CO2 that are relevant on human time scales---the world's oceans and land biosphere---appear to have kept pace with emissions. The continuously increasing strength of the land biosphere sink for CO2 is surpassing expectations given our understanding of the CO2 fertilization and warming effects on the balance between photosynthesis and respiration, especially in the face of ongoing forest degradation. The climate and carbon cycle links between the atmosphere and land biosphere are not well understood, especially at regional (100 km to 10,000 km) scales. The climate modulating effects of changing plant stomatal conductance in response to temperature and water availability is a key area of uncertainty. Further, the differential response to climate change of C3 and C4 plant functional types is not well known at regional scales. This work outlines the development of a novel application of atmospheric observations of delta13C of CO2 to investigate the links between climate and water and carbon cycling and the integrated responses of C3 and C4 ecosystems to climate variables. A two-step Bayesian batch inversion for 3-hourly, 1x1º CO2 fluxes (step one), and for 3-hourly 1x1º delta13C of recently assimilated carbon (step two) is created here for the first time, and is used to investigate links between regional climate indicators and changes in delta13C of the biosphere. Results show that predictable responses of regional-scale, integrated plant discrimination to temperature, precipitation and relative humidity anomalies can be recovered from atmospheric signals. Model development, synthetic data simulations to test sensitivity, and results for the year 2010 are presented here. This dissertation also includes two other applications

  14. Airborne Lidar for Simultaneous Measurement of Column CO2 and Water Vapor in the Atmosphere

    Science.gov (United States)

    Singh, Upendra N.; Petros, Mulugeta; Refaat, Tamer F.; Antill, Charles W.; Remus, Ruben; Yu, Jirong

    2016-01-01

    The 2-micron wavelength region is suitable for atmospheric carbon dioxide (CO2) measurements due to the existence of distinct absorption feathers for the gas at this particular wavelength. For more than 20 years, researchers at NASA Langley Research Center (LaRC) have developed several high-energy and high repetition rate 2-micron pulsed lasers. This paper will provide status and details of an airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar. The development of this active optical remote sensing IPDA instrument is targeted for measuring both CO2 and water vapor (H2O) in the atmosphere from an airborne platform. This presentation will focus on the advancement of the 2-micron triple-pulse IPDA lidar development. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of seed laser locking, wavelength control, receiver telescope, detection system and data acquisition. Future plans for the IPDA lidar system for ground integration, testing and flight validation will also be presented.

  15. Regional atmospheric CO2 inversion reveals seasonal and geographic differences in Amazon net biome exchange.

    Science.gov (United States)

    Alden, Caroline B; Miller, John B; Gatti, Luciana V; Gloor, Manuel M; Guan, Kaiyu; Michalak, Anna M; van der Laan-Luijkx, Ingrid T; Touma, Danielle; Andrews, Arlyn; Basso, Luana S; Correia, Caio S C; Domingues, Lucas G; Joiner, Joanna; Krol, Maarten C; Lyapustin, Alexei I; Peters, Wouter; Shiga, Yoichi P; Thoning, Kirk; van der Velde, Ivar R; van Leeuwen, Thijs T; Yadav, Vineet; Diffenbaugh, Noah S

    2016-10-01

    Understanding tropical rainforest carbon exchange and its response to heat and drought is critical for quantifying the effects of climate change on tropical ecosystems, including global climate-carbon feedbacks. Of particular importance for the global carbon budget is net biome exchange of CO2 with the atmosphere (NBE), which represents nonfire carbon fluxes into and out of biomass and soils. Subannual and sub-Basin Amazon NBE estimates have relied heavily on process-based biosphere models, despite lack of model agreement with plot-scale observations. We present a new analysis of airborne measurements that reveals monthly, regional-scale (~1-8 × 10(6)  km(2) ) NBE variations. We develop a regional atmospheric CO2 inversion that provides the first analysis of geographic and temporal variability in Amazon biosphere-atmosphere carbon exchange and that is minimally influenced by biosphere model-based first guesses of seasonal and annual mean fluxes. We find little evidence for a clear seasonal cycle in Amazon NBE but do find NBE sensitivity to aberrations from long-term mean climate. In particular, we observe increased NBE (more carbon emitted to the atmosphere) associated with heat and drought in 2010, and correlations between wet season NBE and precipitation (negative correlation) and temperature (positive correlation). In the eastern Amazon, pulses of increased NBE persisted through 2011, suggesting legacy effects of 2010 heat and drought. We also identify regional differences in postdrought NBE that appear related to long-term water availability. We examine satellite proxies and find evidence for higher gross primary productivity (GPP) during a pulse of increased carbon uptake in 2011, and lower GPP during a period of increased NBE in the 2010 dry season drought, but links between GPP and NBE changes are not conclusive. These results provide novel evidence of NBE sensitivity to short-term temperature and moisture extremes in the Amazon, where monthly and sub

  16. CO2 absorption characteristics of a Li2TiO3 blanket material under atmospheric exposure

    Science.gov (United States)

    Furuyama, Yuichi; Yahata, Kyohei; Nakamori, Ryoma; Taniike, Akira; Samata, Hiroaki; Kitamura, Akira

    2014-12-01

    Non-Rutherford backscattering spectroscopy (NRBS) for the composition analysis and X-ray diffraction (XRD) for the crystallographic structure analysis have been applied to the blanket candidate material, Li2TiO3, which is known to absorb CO2 though chemically stable. It is found that the amount of CO2 absorbed by atmospheric exposure of the low- and medium-density samples is greater than or comparable to that by dry CO2 gas exposure. By varying the density of the Li2TiO3 and composition of the ambient gas, conditions to minimize the amount of CO2 absorbed are discussed.

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

    Science.gov (United States)

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

    2015-01-01

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

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

    Science.gov (United States)

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

    2015-05-27

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

  19. Free atmospheric CO2 enrichment increased above ground biomass but did not affect symbiotic N2-fixation and soil carbon dynamics in a mixed deciduous stand in Wales

    Directory of Open Access Journals (Sweden)

    A. R. Smith

    2011-02-01

    Full Text Available Through increases in net primary production (NPP, elevated CO2 is hypothesized to increase the amount of plant litter entering the soil. The fate of this extra carbon on the forest floor or in mineral soil is currently not clear. Moreover, increased rates of NPP can be maintained only if forests can escape nitrogen limitation. In a Free atmospheric CO2 Enrichment (FACE experiment near Bangor, Wales, 4 ambient and 4 elevated [CO2] plots were planted with patches of Betula pendula, Alnus glutinosa and Fagus sylvatica on a former arable field. After 4 years, biomass averaged for the 3 species was 5497 (se 270 g m−2 in ambient and 6450 (se 130 g m−2 in elevated [CO2] plots, a significant increase of 17% (P = 0.018. During that time, only a shallow L forest floor litter layer had formed due to intensive bioturbation. Total soil C and N contents increased irrespective of treatment and species as a result of afforestation. We could not detect an additional C sink in the soil, nor were soil C stabilization processes affected by elevated [CO2]. We observed a decrease of leaf N content in Betula and Alnus under elevated [CO2], while the soil C/N ratio decreased regardless of CO2 treatment. The ratio of N taken up from the soil and by N2-fixation in Alnus was not affected by elevated [CO2]. We infer that increased nitrogen use efficiency is the mechanism by which increased NPP is sustained under elevated [CO2] at this site.

  20. Arbuscular mycorrhiza infection enhances the growth response of Lolium perenne to elevated atmospheric pCO(2).

    Science.gov (United States)

    Hartwig, U A; Wittmann, P; Braun, R; Hartwig-Räz, B; Jansa, J; Mozafar, A; Lüscher, A; Leuchtmann, A; Frossard, E; Nösberger, J

    2002-05-01

    Elevated atmospheric pCO(2) increases the C-availability for plants and thus leads to a comparable increase in plant biomass production and nutrient demand. Arbuscular mycorrhizal fungi (AMF) are considered to play an important role in the nutrient uptake of plants as well as to be a significant C-sink. Therefore, an increased colonization of plant roots by AMF is expected under elevated atmospheric pCO(2). To test these hypotheses, Lolium perenne L. plants were grown from seeds in a growth chamber in pots containing a silica sand/soil mixture for 9 weeks with and without inoculation with Glomus intraradices (Schenck and Smith). The growth response of plants at two different levels of N fertilization (1.5 or 4.5 mM) combined with ambient (35 Pa) and elevated atmospheric pCO(2) (60 Pa) was compared. The inoculation with G. intraradices, the elevated atmospheric pCO(2) and the high N fertilization treatment all led to an increased plant biomass production of 16%, 20% and 49%, respectively. AMF colonization and high N fertilization increased the plant growth response to elevated atmospheric pCO(2); the plant growth response to high N fertilization was also increased by AMF colonization. The root/shoot ratio was reduced by high N fertilization or elevated atmospheric pCO(2), but was not affected by AMF colonization. The unchanged specific leaf area indicated that if AMF colonization represented an increased C-sink, this was fully covered by the plant. Elevated atmospheric pCO(2) strongly increased AMF colonization (60%) while the high N fertilization had a slightly negative effect. AMF colonization neither improved the N nor P nutrition status, but led to an improved total P uptake. The results underline the importance of AMF for the response of grassland ecosystems to elevated atmospheric pCO(2).

  1. Impact of difference in absorption line parameters in spectroscopic databases on CO2 and CH4 atmospheric content retrievals

    Science.gov (United States)

    Chesnokova, T. Yu.; Chentsov, A. V.; Rokotyan, N. V.; Zakharov, V. I.

    2016-09-01

    The impact of uncertainties in CH4 and CO2 absorption line parameters in modern spectroscopic databases on the atmospheric transmission simulation in the near-infrared region is investigated. The atmospheric contents of CH4 and CO2 are retrieved from the absorption solar spectra measured by a ground-based Fourier transform spectrometer. Different spectroscopic databases are used in the forward radiative transfer model and a comparison of the retrieved results is made.

  2. Sensitivity of Pliocene Arctic climate to orbital forcing, atmospheric CO2 and sea ice albedo parameterisation

    Science.gov (United States)

    Howell, Fergus; Haywood, Alan; Pickering, Steven

    2016-04-01

    General circulation model (GCM) simulations of the mid-Pliocene Warm Period (mPWP, 3.264 to 3.025 Myr ago) do not reproduce the magnitude of Northern Hemisphere high latitude surface air and sea surface temperature (SAT and SST) warming that proxy data indicates. There is also large uncertainty regarding the state of sea ice cover in the mPWP. Evidence for both perennial and seasonal mPWP Arctic sea ice is found in analyses of marine sediments, whilst in a multi-model ensemble of mPWP climate simulations, half of the ensemble simulated ice-free summer Arctic conditions. Given the strong influence that sea ice exerts on high latitude temperatures, a better understanding of the nature of mPWP Arctic sea ice would be highly beneficial in understanding proxy derived estimates of high latitude surface temperature change, and the ability of climate models to reproduce this. In GCM simulations, the mPWP is typically represented with fixed orbital forcing, usually identical to modern, and atmospheric CO2 concentrations of ˜ 400 ppm. However, orbital forcing varied over the ˜ 240,000 years of the mPWP, and it is likely that atmospheric CO2 varied as well. A previous study has suggested that the parameterisation of sea ice albedo in the HadCM3 GCM may not reflect the sea ice albedo for a warmer climate, where seasonal sea ice constitutes a greater proportion of the Arctic sea ice cover. These three factors, in isolation and combined, can greatly influence the simulation of Arctic sea ice cover and the degree of high latitude surface temperature warming. This paper explores the impact of various combinations of potential mPWP orbital forcing, atmospheric CO2 concentrations and minimum sea ice albedo on sea ice extent and high latitude warming. The focus is on the Northern Hemisphere, due to availability of proxy data, and the large data-model discrepancies in this region. Changes in orbital forcings are demonstrated to be sufficient to alter the Arctic sea ice simulated by

  3. Response of the Atlantic Thermohaline Circulation to Increased Atmospheric CO2 in a Coupled Model.

    Science.gov (United States)

    Hu, Aixue; Meehl, Gerald A.; Washington, Warren M.; Dai, Aiguo

    2004-11-01

    Changes in the thermohaline circulation (THC) due to increased CO2 are important in future climate regimes. Using a coupled climate model, the Parallel Climate Model (PCM), regional responses of the THC in the North Atlantic to increased CO2 and the underlying physical processes are studied here. The Atlantic THC shows a 20-yr cycle in the control run, qualitatively agreeing with other modeling results. Compared with the control run, the simulated maximum of the Atlantic THC weakens by about 5 Sv (1 Sv 106 m3 s-1) or 14% in an ensemble of transient experiments with a 1% CO2 increase per year at the time of CO2 doubling. The weakening of the THC is accompanied by reduced poleward heat transport in the midlatitude North Atlantic. Analyses show that oceanic deep convective activity strengthens significantly in the Greenland Iceland Norway (GIN) Seas owing to a saltier (denser) upper ocean, but weakens in the Labrador Sea due to a fresher (lighter) upper ocean and in the south of the Denmark Strait region (SDSR) because of surface warming. The saltiness of the GIN Seas are mainly caused by an increased salty North Atlantic inflow, and reduced sea ice volume fluxes from the Arctic into this region. The warmer SDSR is induced by a reduced heat loss to the atmosphere, and a reduced sea ice flux into this region, resulting in less heat being used to melt ice. Thus, sea ice related salinity effects appear to be more important in the GIN Seas, but sea ice melt-related thermal effects seem to be more important in the SDSR region. On the other hand, the fresher Labrador Sea is mainly attributed to increased precipitation. These regional changes produce the overall weakening of the THC in the Labrador Sea and SDSR, and more vigorous ocean overturning in the GIN Seas. The northward heat transport south of 60°N is reduced with increased CO2, but increased north of 60°N due to the increased flow of North Atlantic water across this latitude.

  4. Atmospheric CO2 uptake throughout bio-enhanced brucite-water reaction at Montecastelli serpentinites (Italy)

    Science.gov (United States)

    Bedini, Federica; Boschi, Chiara; Ménez, Benedicte; Perchiazzi, Natale; Zanchetta, Giovanni

    2014-05-01

    In the last several years, interactions between microorganisms and minerals have intrigued and catched the interest of the scientific community. Montecastelli serpentinites (Tuscany, Italy) are characterized by CO2-mineral carbonation, an important process which leads to spontaneous formation of carbonate phases uptaking atmospheric CO2. In the studied areas carbonate precipitates, mainly hydrated Mg-carbonates, are present in form of crusts, coating and spherules on exposed rock surfaces, and filling rock fractures. Petrographic and mineralogical observations revealed that Tuscan brucite-rich serpentinites hosts preserve their original chemical compositions with typical mesh-textured serpentine (± brucite) after olivine, magnetite-rich mesh rims and relicts of primary spinel. Representative hydrated carbonate samples have been collected in three different areas and analyzed to investigate the role of biological activity and its influence in the serpentine-hydrated Mg-carbonates reaction. The different types of whitish precipitates have been selected under binocular microscope for XRD analyses performed at the Dipartimento di Scienze della Terra (University of Pisa, Italy): their mineralogical composition consists of mainly hydromagnesite and variable amount of other metastable carbonate phases (i.e. nesquehonite, manasseite, pyroaurite, brugnatellite and aragonite). Moreover, the crystallinity analysis of whitish crust and spherules have been carried out by detailed and quantitative XRD analyses to testify a possible biologically controlled growth, inasmuch as the crystal structure of biominerals could be affected by many lattice defects (i.e. dislocations, twinning, etc.) and this observation cause low crystallinity of the mineral. The presence of microbial cells and relicts of organic matter has already been detected by confocal laser scanning microscopy (CLSM) combined with Raman spectromicroscopy in a previous study (Bedini et al., 2013). The presence of

  5. Elevated atmospheric CO2 triggers compensatory feeding by root herbivores on a C3 but not a C4 grass.

    Directory of Open Access Journals (Sweden)

    Scott N Johnson

    Full Text Available Predicted increases in atmospheric carbon dioxide (CO2 concentrations often reduce nutritional quality for herbivores by increasing the C:N ratio of plant tissue. This frequently triggers compensatory feeding by aboveground herbivores, whereby they consume more shoot material in an attempt to meet their nutritional needs. Little, however, is known about how root herbivores respond to such changes. Grasslands are particularly vulnerable to root herbivores, which can collectively exceed the mass of mammals grazing aboveground. Here we provide novel evidence for compensatory feeding by a grass root herbivore, Sericesthis nigrolineata, under elevated atmospheric CO2 (600 µmol mol(-1 on a C3 (Microlaena stipoides but not a C4 (Cymbopogon refractus grass species. At ambient CO2 (400 µmol mol(-1 M. stipoides roots were 44% higher in nitrogen (N and 7% lower in carbon (C concentrations than C. refractus, with insects performing better on M. stipoides. Elevated CO2 decreased N and increased C:N in M. stipoides roots, but had no impact on C. refractus roots. Root-feeders displayed compensatory feeding on M. stipoides at elevated CO2, consuming 118% more tissue than at ambient atmospheric CO2. Despite this, root feeder biomass remained depressed by 24%. These results suggest that compensatory feeding under elevated atmospheric CO2 may make some grass species particularly vulnerable to attack, potentially leading to future shifts in the community composition of grasslands.

  6. Low atmospheric CO2 levels during the Little Ice Age due to cooling-induced terrestrial uptake

    Science.gov (United States)

    Rubino, M.; Etheridge, D. M.; Trudinger, C. M.; Allison, C. E.; Rayner, P. J.; Enting, I.; Mulvaney, R.; Steele, L. P.; Langenfelds, R. L.; Sturges, W. T.; Curran, M. A. J.; Smith, A. M.

    2016-09-01

    Low atmospheric carbon dioxide (CO2) concentration during the Little Ice Age has been used to derive the global carbon cycle sensitivity to temperature. Recent evidence confirms earlier indications that the low CO2 was caused by increased terrestrial carbon storage. It remains unknown whether the terrestrial biosphere responded to temperature variations, or there was vegetation re-growth on abandoned farmland. Here we present a global numerical simulation of atmospheric carbonyl sulfide concentrations in the pre-industrial period. Carbonyl sulfide concentration is linked to changes in gross primary production and shows a positive anomaly during the Little Ice Age. We show that a decrease in gross primary production and a larger decrease in ecosystem respiration is the most likely explanation for the decrease in atmospheric CO2 and increase in atmospheric carbonyl sulfide concentrations. Therefore, temperature change, not vegetation re-growth, was the main cause of the increased terrestrial carbon storage. We address the inconsistency between ice-core CO2 records from different sites measuring CO2 and δ13CO2 in ice from Dronning Maud Land (Antarctica). Our interpretation allows us to derive the temperature sensitivity of pre-industrial CO2 fluxes for the terrestrial biosphere (γL = -10 to -90 Pg C K-1), implying a positive climate feedback and providing a benchmark to reduce model uncertainties.

  7. Modelling changes in nitrogen cycling to sustain increases in forest productivity under elevated atmospheric CO2 and contrasting site conditions

    Directory of Open Access Journals (Sweden)

    R. F. Grant

    2013-04-01

    Full Text Available If increases in net primary productivity (NPP caused by rising concentrations of atmospheric CO2 (Ca are to be sustained, key N processes such as soil mineralization, biological fixation, root uptake and plant translocation must be hastened. Simulating the response of these processes to elevated Ca is therefore vital for models used to project the effects of rising Ca on NPP. In this modelling study, hypotheses are proposed for changes in soil mineralization, biological fixation, root uptake and plant translocation with changes in Ca. Algorithms developed from these hypotheses were tested in the ecosystem model ecosys against changes in N and C cycling measured over several years under ambient vs. elevatedCa in Free Air CO2 Enrichment (FACE experiments at the Duke Forest in North Carolina, the Oak Ridge National Laboratory forest in Tennessee, and the USDA research forest in Wisconsin, USA. Simulating more rapid soil N mineralization was found to be vital for modelling sustained increases in NPP measured under elevated vs. ambient Ca at all three FACE sites. This simulation was accomplished by priming decomposition of N-rich humus from increases in microbial biomass generated by increased litterfall modelled under elevated Ca. Simulating more rapid nonsymbiotic N2 fixation, root N uptake and plant N translocation under elevated Ca was found to make much smaller contributions to modelled increases in NPP, although such contributions might be greater over longer periods and under more N-limited conditions than those simulated here. Greater increases in NPP with Ca were also modelled with increased temperature and water stress, and with coniferous vs. deciduous plant functional types. These increases were also associated with changes in N cycling.

  8. Modelling changes in nitrogen cycling to sustain increases in forest productivity under elevated atmospheric CO2 and contrasting site conditions

    Science.gov (United States)

    Grant, R. F.

    2013-11-01

    If increases in net primary productivity (NPP) caused by rising concentrations of atmospheric CO2 (Ca) are to be sustained, key N processes such as soil mineralization, biological fixation, root uptake and nutrient conservation must also be increased. Simulating the response of these processes to elevated Ca is therefore vital for models used to project the effects of rising Ca on NPP. In this modelling study, hypotheses are proposed for changes in soil mineralization, biological fixation, root nutrient uptake and plant nutrient conservation with changes in Ca. Algorithms developed from these hypotheses were tested in the ecosystem model ecosys against changes in N and C cycling measured over several years under ambient vs. elevated Ca in Free Air CO2 Enrichment (FACE) experiments in the USA at the Duke Forest in North Carolina, the Oak Ridge National Laboratory forest in Tennessee, and the USDA research forest in Wisconsin. More rapid soil N mineralization was found to be vital for simulating sustained increases in NPP measured under elevated vs. ambient Ca at all three FACE sites. This simulation was accomplished by priming decomposition of N-rich humus from increases in microbial biomass generated by increased litterfall modelled under elevated Ca. Greater nonsymbiotic N2 fixation from increased litterfall, root N uptake from increased root growth, and plant N conservation from increased translocation under elevated Ca were found to make smaller contributions to simulated increases in NPP. However greater nutrient conservation enabled larger increases in NPP with Ca to be modelled with coniferous vs. deciduous plant functional types. The effects of these processes on productivity now need to be examined over longer periods under transient rises in Ca and a greater range of site conditions.

  9. In-situ measurement of atmospheric CO2 at the four WMO/GAW stations in China

    Directory of Open Access Journals (Sweden)

    S. X Fang

    2013-10-01

    Full Text Available Atmospheric carbon dioxide (CO2 mole fractions were continuously measured from January 2009 to December 2011 at 4 atmospheric observatories in China ((Lin'an, LAN, (Longfengshan, LFS, (Shangdianzi, SDZ, and (Waliguan, WLG using Cavity Ring Down Spectroscopy instruments. All sites are regional (LAN, LFS, SDZ or global (WLG measurement stations of the World Meteorological Organization/Global Atmosphere Watch program (WMO/GAW. LAN is located near the megacity of Shanghai, in China's most economically developed region. LFS is in a forest and rice production area, close to the city of Harbin in the northern east of China. SDZ is located 150 km north east of Beijing. WLG, hosting the longest record of measured CO2 mole fractions in China, is a high altitude site in northwest China recording background CO2 values. The CO2 growth rates are 2.2 ± 0.2 ppm yr−1 for LAN, 2.3 ± 0.2 ppm yr−1 for LFS, 2.0 ± 0.2 ppm yr−1 for SDZ, and 1.2 ± 0.1 ppm yr−1 (1σ for WLG, during the period of 2009 to 2011. The growth rate at WLG may be underestimated due to the data gaps during the observation period. The highest annual mean CO2 mole fraction of 404.1 ± 4.1 ppm was observed at LAN in 2011. A comprehensive analysis of CO2 variations, their diurnal and seasonal cycles as well as the analysis of the influence of different wind regimes on the CO2 mole fractions allows a thorough characterization of the sampling sites and of the key processes driving the CO2 mole fractions. These data form a basis to improve our understanding of atmospheric CO2 variations in China and the underlying fluxes, using atmospheric inversion models.

  10. Land Use Effects on Atmospheric C-13 Imply a Sizable Terrestrial CO2 Sink in Tropical Latitudes

    Science.gov (United States)

    Townsend, Alan R.; Asner, Gregory P.; Tans, Pieter P.; White, James W. C.

    2000-01-01

    Records of atmospheric CO2 and 13-CO2, can be used to distinguish terrestrial vs. oceanic exchanges of CO2 with the atmosphere. However, this approach has proven difficult in the tropics, partly due to extensive land conversion from C-3 to C-4 vegetation. We estimated the effects of such conversion on biosphere-atmosphere C-13 exchange for 1991 through 1999, and then explored how this 'land-use disequilibrium' altered the partitioning of net atmospheric CO2 exchanges between ocean and land using NOAA-CMDL data and a 2D, zonally averaged atmospheric transport model. Our results show sizable CO2 uptake in C-3-dominated tropical regions in seven of the nine years; 1997 and 1998, which included a strong ENSO event, are near neutral. Since these fluxes include any deforestation source, our findings imply either that such sources are smaller than previously estimated, and/or the existence of a large terrestrial CO2 sink in equatorial latitudes.

  11. Potential maternal effects of elevated atmospheric CO2 on development and disease severity in a Mediterranean legume

    Directory of Open Access Journals (Sweden)

    José M. Grünzweig

    2011-07-01

    Full Text Available Global change can greatly affect plant populations both directly by influencing growing conditions and indirectly by maternal effects on development of offspring. More information is needed on transgenerational effects of global change on plants and on their interactions with pathogens. The current study assessed potential maternal effects of atmospheric CO2 enrichment on performance and disease susceptibility of first-generation offspring of the Mediterranean legume Onobrychis crista-galli. Mother plants were grown at three CO2 concentrations, and the study focused on their offspring that were raised under common ambient climate and CO2. In addition, progeny were exposed to natural infection by the fungal pathogen powdery mildew. In one out of three years, offspring of high-CO2 treatments (440 and 600 ppm had lower shoot biomass and reproductive output than offspring of low-CO2 treatment (280 ppm. Disease severity in a heavy-infection year was higher in high-CO2 than in low-CO2 offspring. However, some of the findings on maternal effects changed when the population was divided into two functionally diverging plant types distinguishable by flower color (pink, Type P; white Type W. Disease severity in a heavy-infection year was higher in high-CO2 than in low-CO2 progeny in the more disease-resistant (Type P, but not in the more susceptible plant type (Type W. In a low-infection year, maternal CO2 treatments did not differ in disease severity. Mother plants of Type P exposed to low CO2 produced larger seeds than all other combinations of CO2 and plant type, which might contribute to higher offspring performance. This study showed that elevated CO2 potentially exerts environmental maternal effects on performance of progeny and, notably, also on their susceptibility to natural infection by a pathogen. Maternal effects of global change might differently affect functionally divergent plant types, which could impact population fitness and alter plant

  12. Advanced Sine Wave Modulation of Continuous Wave Laser System for Atmospheric CO2 Differential Absorption Measurements

    Science.gov (United States)

    Campbell, Joel F.; Lin, Bing; Nehrir, Amin R.

    2014-01-01

    NASA Langley Research Center in collaboration with ITT Exelis have been experimenting with Continuous Wave (CW) laser absorption spectrometer (LAS) as a means of performing atmospheric CO2 column measurements from space to support the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission.Because range resolving Intensity Modulated (IM) CW lidar techniques presented here rely on matched filter correlations, autocorrelation properties without side lobes or other artifacts are highly desirable since the autocorrelation function is critical for the measurements of lidar return powers, laser path lengths, and CO2 column amounts. In this paper modulation techniques are investigated that improve autocorrelation properties. The modulation techniques investigated in this paper include sine waves modulated by maximum length (ML) sequences in various hardware configurations. A CW lidar system using sine waves modulated by ML pseudo random noise codes is described, which uses a time shifting approach to separate channels and make multiple, simultaneous online/offline differential absorption measurements. Unlike the pure ML sequence, this technique is useful in hardware that is band pass filtered as the IM sine wave carrier shifts the main power band. Both amplitude and Phase Shift Keying (PSK) modulated IM carriers are investigated that exibit perfect autocorrelation properties down to one cycle per code bit. In addition, a method is presented to bandwidth limit the ML sequence based on a Gaussian filter implemented in terms of Jacobi theta functions that does not seriously degrade the resolution or introduce side lobes as a means of reducing aliasing and IM carrier bandwidth.

  13. Carbon Dioxide (CO2) Retrievals from Atmospheric Chemistry Experiment (ACE) Solar Occultation Measurements

    Science.gov (United States)

    Rinsland, Curtis P.; Chiou, Linda; Boone, Chris; Bernath, Peter

    2010-01-01

    The Atmospheric Chemistry Experiment ACE satellite (SCISAT-1) was launched into an inclined orbit on 12 August 2003 and is now recording high signal-to-noise 0.02 per centimeter resolution solar absorption spectra covering 750-4400 per centimeter (2.3-13 micrometers). A procedure has been developed for retrieving average dry air CO2 mole fractions (X(sub CO2)) in the altitude range 7-10 kilometers from the SCISAT-1 spectra. Using the N2 continuum absorption in a window region near 2500 per centimeter, altitude shifts are applied to the tangent heights retrieved in version 2.2 SCISAT-1 processing, while cloudy or aerosol-impacted measurements are eliminated. Monthly-mean XCO2 covering 60 S to 60 N latitude for February 2004 to March 2008 has been analyzed with consistent trends inferred in both hemispheres. The ACE XCO2 time series have been compared with previously-reported surface network measurements, predictions based on upper tropospheric aircraft measurements, and space-based measurements. The retrieved X(sub CO2) from the ACE-FTS spectra are higher on average by a factor of 1.07 plus or minus 0.025 in the northern hemisphere and by a factor of 1.09 plus or minus 0.019 on average in the southern hemisphere compared to surface station measurements covering the same time span. The ACE derived trend is approximately 0.2% per year higher than measured at surface stations during the same observation period.

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

    Science.gov (United States)

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

    2016-01-01

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

  15. Controle de Rhyzopertha dominica pela atmosfera controlada com CO2, em trigo Control of Rhyzopertha dominica using a controlled atmosphere with CO2, in wheat

    Directory of Open Access Journals (Sweden)

    Rogério Amaro Gonçalves

    2000-01-01

    Full Text Available A utilização de gases inertes como fumigantes no controle de pragas é uma alternativa ao uso de fosfina. O objetivo deste trabalho foi avaliar a eficiência de uma atmosfera com CO2 no controle de Rhyzoperta dominica (Fabr. (Coleoptera: Bostrichidae em grãos de trigo armazenado. O trabalho constou de cinco concentrações de CO2 (0, 30 , 40, 50 e 60%, completadas com N2, três períodos de exposição (5, 10, 15 dias, três populações de R. dominica (Fabr. (Coleoptera: Bostrichidae (Campo Mourão, PR, Sete Lagoas, MG e Santa Rosa, RS e sete fases de desenvolvimento do inseto (ovo, larva de 1º, 2º, 3º e 4º ínstar, pupa e adulto com três repetições. As diferentes fases da R. dominica foram acondicionadas em tecido organza e levadas para câmaras de expurgo de 200 litros com 75% deste volume repletos de grãos. As câmaras foram vedadas com borracha de silicone para garantir a hermeticidade. Após a vedação das câmaras injetavam-se os gases contendo diferentes teores de CO2. Os resultados mostraram que todos os teores de CO2 causaram 100% de mortalidade de adultos das três populações nos três períodos de exposição utilizados. Em pupas a mortalidade atingiu 100% no teor de 60% de CO2 para as três populações no período de 15 dias de exposição; porém, todos os teores de CO2 utilizados no período de 15 dias de exposição causaram 100% de mortalidade das pupas da população de Santa Rosa. Para o adequado controle de larvas de diferentes ínstares são necessários teores de CO2 iguais ou acima de 50%. Nos períodos de 10 e 15 dias de exposição, todos os teores de CO2 causaram 100% de mortalidade dos ovos das três populações avaliadas.Controlled atmosphere with inert gases offers an alternative to phosphine use to control stored grain pests. The objective of this research was to test a controlled atmosphere with CO2 to control Rhyzoperta dominica, (Fabr. (Coleoptera: Bostrichidae, an important pest of stored wheat

  16. The Influence of CO2 Admixtures on the Product Composition in a Nitrogen-Methane Atmospheric Glow Discharge Used as a Prebiotic Atmosphere Mimic

    Science.gov (United States)

    Mazankova, V.; Torokova, L.; Krcma, F.; Mason, N. J.; Matejcik, S.

    2016-04-01

    This work extends our previous experimental studies of the chemistry of Titan's atmosphere by atmospheric glow discharge. The Titan's atmosphere seems to be similarly to early Earth atmospheric composition. The exploration of Titan atmosphere was initiated by the exciting results of the Cassini-Huygens mission and obtained results increased the interest about prebiotic atmospheres. Present work is devoted to the role of CO2 in the prebiotic atmosphere chemistry. Most of the laboratory studies of such atmosphere were focused on the chemistry of N2 + CH4 mixtures. The present work is devoted to the study of the oxygenated volatile species in prebiotic atmosphere, specifically CO2 reactivity. CO2 was introduced to the standard N2 + CH4 mixture at different mixing ratio up to 5 % CH4 and 3 % CO2. The reaction products were characterized by FTIR spectroscopy. This work shows that CO2 modifies the composition of the gas phase with the detection of oxygenated compounds: CO and others oxides. There is a strong influence of CO2 on increasing concentration other products as cyanide (HCN) and ammonia (NH3).

  17. The Influence of CO2 Admixtures on the Product Composition in a Nitrogen-Methane Atmospheric Glow Discharge Used as a Prebiotic Atmosphere Mimic

    Science.gov (United States)

    Mazankova, V.; Torokova, L.; Krcma, F.; Mason, N. J.; Matejcik, S.

    2016-11-01

    This work extends our previous experimental studies of the chemistry of Titan's atmosphere by atmospheric glow discharge. The Titan's atmosphere seems to be similarly to early Earth atmospheric composition. The exploration of Titan atmosphere was initiated by the exciting results of the Cassini-Huygens mission and obtained results increased the interest about prebiotic atmospheres. Present work is devoted to the role of CO2 in the prebiotic atmosphere chemistry. Most of the laboratory studies of such atmosphere were focused on the chemistry of N2 + CH4 mixtures. The present work is devoted to the study of the oxygenated volatile species in prebiotic atmosphere, specifically CO2 reactivity. CO2 was introduced to the standard N2 + CH4 mixture at different mixing ratio up to 5 % CH4 and 3 % CO2. The reaction products were characterized by FTIR spectroscopy. This work shows that CO2 modifies the composition of the gas phase with the detection of oxygenated compounds: CO and others oxides. There is a strong influence of CO2 on increasing concentration other products as cyanide (HCN) and ammonia (NH3).

  18. Range Resolved CO2 Atmospheric Backscattering Measurements Using Fiber Lasers and RZPN Code Modulation

    Science.gov (United States)

    Burris, John

    2011-01-01

    We report the use of a return-to- zero (RZPN) pseudo noise modulation technique for making range resolved measurements of CO2 within the planetary boundary layer (PBL) using commercial, off-the-shelf, components. Conventional, range resolved, DIAL measurements require laser pulse widths that are significantly shorter than the desired spatial resolution and necessitate using pulses whose temporal spacing is such that scattered returns from only a single pulse are observed by the receiver at any one time (for the PBL pulse separations must be greater than approximately 20 microseconds). This imposes significant operational limitations when using currently available fiber lasers because of the resulting low duty cycle (less than approximately 0.0005) and consequent low average laser output power. The RZPN modulation technique enables a fiber laser to operate at much higher duty cycles (approaching 0.04) thereby more effectively utilizing the amplifier's output. This increases the counts received by approximately two orders of magnitude. Our approach involves employing two distributed feedback lasers (DFB), each modulated by a different RPZN code, whose outputs are then amplified by a CW fiber amplifier. One laser is tuned to a CO2 absorption line; the other operates offline thereby permitting the simultaneous acquisition of both on and offline signals using independent RZPN codes. This minimizes the impact of atmospheric turbulence on the measurement. The on and offline signals are retrieved by deconvolving the return signal using the appropriate kernels.

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

    Science.gov (United States)

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

    2017-01-01

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

  20. Impact of atmospheric CO2 on growth, photosynthesis and nitrogen metabolism in cucumber (Cucumis sativus L.) plants.

    Science.gov (United States)

    Agüera, Eloísa; Ruano, David; Cabello, Purificación; de la Haba, Purificación

    2006-07-01

    Expression and activity of nitrate reductase (NR; EC 1.6.6.1) and glutamine synthetase (GS; EC 6.3.1.2) were analysed in relation to the rate of CO(2) assimilation in cucumber (Cucumis sativus L.) leaves. Intact plants were exposed to different atmospheric CO(2) concentrations (100, 400 and 1200microLL(-1)) for 14 days. A correlation between the in vivo rates of net CO(2) assimilation and the atmospheric CO(2) concentrations was observed. Transpiration rate and stomatal conductance remained unaffected by CO(2) levels. The exposure of the cucumber plants to rising CO(2) concentrations led to a concomitant increase in the contents of starch and soluble sugars, and a decrease in the nitrate content in leaves. At very low CO(2), NR and GS expression decreased, in spite of high nitrate contents, whereas at normal and elevated CO(2) expression and activity were high although the nitrate content was very low. Thus, in cucumber, NR and GS expression appear to be dominated by sugar levels, rather than by nitrate contents.

  1. Automatic processing of atmospheric CO2 and CH4 mole fractions at the ICOS Atmosphere Thematic Centre

    Science.gov (United States)

    Hazan, Lynn; Tarniewicz, Jérôme; Ramonet, Michel; Laurent, Olivier; Abbaris, Amara

    2016-09-01

    The Integrated Carbon Observation System Atmosphere Thematic Centre (ICOS ATC) automatically processes atmospheric greenhouse gases mole fractions of data coming from sites of the ICOS network. Daily transferred raw data files are automatically processed and archived. Data are stored in the ICOS atmospheric database, the backbone of the system, which has been developed with an emphasis on the traceability of the data processing. Many data products, updated daily, explore the data through different angles to support the quality control of the dataset performed by the principal operators in charge of the instruments. The automatic processing includes calibration and water vapor corrections as described in the paper. The mole fractions calculated in near-real time (NRT) are automatically revaluated as soon as a new instrument calibration is processed or when the station supervisors perform quality control. By analyzing data from 11 sites, we determined that the average calibration corrections are equal to 1.7 ± 0.3 µmol mol-1 for CO2 and 2.8 ± 3 nmol mol-1 for CH4. These biases are important to correct to avoid artificial gradients between stations that could lead to error in flux estimates when using atmospheric inversion techniques. We also calculated that the average drift between two successive calibrations separated by 15 days amounts to ±0.05 µmol mol-1 and ±0.7 nmol mol-1 for CO2 and CH4, respectively. Outliers are generally due to errors in the instrument configuration and can be readily detected thanks to the data products provided by the ATC. Several developments are still ongoing to improve the processing, including automated spike detection and calculation of time-varying uncertainties.

  2. Transcriptional and metabolic insights into the differential physiological responses of arabidopsis to optimal and supraoptimal atmospheric CO2.

    Directory of Open Access Journals (Sweden)

    Fatma Kaplan

    Full Text Available BACKGROUND: In tightly closed human habitats such as space stations, locations near volcano vents and closed culture vessels, atmospheric CO(2 concentration may be 10 to 20 times greater than Earth's current ambient levels. It is known that super-elevated (SE CO(2 (>1,200 µmol mol(-1 induces physiological responses different from that of moderately elevated CO(2 (up to 1,200 µmol mol(-1, but little is known about the molecular responses of plants to supra-optimal [CO(2]. METHODOLOGY/PRINCIPAL FINDINGS: To understand the underlying molecular causes for differential physiological responses, metabolite and transcript profiles were analyzed in aerial tissue of Arabidopsis plants, which were grown under ambient atmospheric CO(2 (400 µmol mol(-1, elevated CO(2 (1,200 µmol mol(-1 and SE CO(2 (4,000 µmol mol(-1, at two developmental stages early and late vegetative stage. Transcript and metabolite profiling revealed very different responses to elevated versus SE [CO(2]. The transcript profiles of SE CO(2 treated plants were closer to that of the control. Development stage had a clear effect on plant molecular response to elevated and SE [CO(2]. Photosynthetic acclimation in terms of down-regulation of photosynthetic gene expression was observed in response to elevated [CO(2], but not that of SE [CO(2] providing the first molecular evidence that there appears to be a fundamental disparity in the way plants respond to elevated and SE [CO(2]. Although starch accumulation was induced by both elevated and SE [CO(2], the increase was less at the late vegetative stage and accompanied by higher soluble sugar content suggesting an increased starch breakdown to meet sink strength resulting from the rapid growth demand. Furthermore, many of the elevated and SE CO(2-responsive genes found in the present study are also regulated by plant hormone and stress. CONCLUSIONS/SIGNIFICANCE: This study provides new insights into plant acclimation to elevated and SE [CO

  3. Modelling the CO2 atmosphere-ocean flux in the upwelling zones using radiative transfer tools

    Science.gov (United States)

    Krapivin, Vladimir F.; Varotsos, Costas A.

    2016-12-01

    An advanced mathematical model of the radiation forcing on the ocean surface is proposed for the assessment of the CO2 fluxes between atmosphere and ocean boundary in the upwelling zones. Two types of the upwelling are considered: coastal and local in the open ocean that are closely associated with changes in solar irradiance. The proposed model takes into account the maximal number of the carbon fluxes in the upwelling ecosystem considering that in the latter the only original source of energy and matter for all forms of life is the energy of the solar radiation. The vertical structure of the upwelling zone is represented by four levels: the upper mixed layer above the thermocline, the intermediate photic layer below the thermocline, the deep ocean and the near-bottom layer. Peruvian upwelling and typical local upwelling of tropical pelagic region are considered as examples for the model calculations.

  4. Ocean-Atmosphere coupling and CO2 exchanges in the Southwestern Atlantic Ocean

    Science.gov (United States)

    Souza, R.; Pezzi, L. P.; Carmargo, R.; Acevedo, O. C.

    2013-05-01

    The establishment of the INTERCONF Program (Air-Sea Interactions at the Brazil-Malvinas Confluence Zone) in 2004 and subsequent developing of projects such as the SIMTECO (Integrated System for Monitoring the Weather, the Climate and the Ocean in the South of Brazil) and ACEx (Atlantic Ocean Carbon Experiment) from 2010 in Brazil brought to light the importance of understanding the impact of the Southwestern Atlantic Ocean's mesoscale variability on the modulation of the atmospheric boundary layer (ABL) at the synoptic scale. Recent results of all these projects showed that the ABL modulation, as well as the ocean-atmosphere turbulent (heat, momentum and CO2) fluxes are dependent on the behavior of the ocean's surface thermal gradients, especially those found in the Brazil-Malvinas Confluence Zone and at the southern coast off Brazil during the winter. As expected, when atmospheric large scale systems are not present over the study area, stronger heat fluxes are found over regions of higher sea surface temperature (SST) including over warm core eddies shed towards the subantarctic (cold) environment. In the coastal region off southern Brazil, the wintertime propagation of the Brazilian Costal Current (La Plata Plume) acts rising the chlorophyll concentration over the continental shelf as well as diminishing considerably the SST - hence producing prominent across-shore SST gradients towards the offshore region dominated by the Brazil Current waters. Owing to that, heat fluxes are directed towards the ocean in coastal waters that are also responsible for the carbon sinking off Brazil in wintertime. All this description is dependent on the synoptic atmospheric cycle and strongly perturbed when transient systems (cold fronts, subtropical cyclones) are present in the area. However, remote sensing data used here suggest that the average condition of the atmosphere directly responding to the ocean's mesoscale variability appears to imprint a signal that extends from the

  5. Microbial imprint on soil-atmosphere H2, COS, and CO2 fluxes

    Science.gov (United States)

    Meredith, L. K.; Commane, R.; Munger, J. W.; Wofsy, S. C.; Prinn, R. G.

    2013-12-01

    Microorganisms drive large trace gas fluxes between soil and atmosphere, but the signal can be difficult to detect and quantify in the presence of stronger exchange processes in an ecosystem. Partitioning methods are often needed to estimate trace gas budgets and to develop process-based models to explore the sensitivity of microbe-mediated fluxes. In this study, we test the performance of trace gases with predominantly microbe-mediated soil fluxes as a metric of the soil microbial uptake activity of other trace gases. Using simultaneous, collocated measurements at Harvard Forest, we consider three trace gases with microbe-mediated soil fluxes of various importance relative to their other (mainly plant-mediated) ecosystem fluxes: molecular hydrogen (H2), carbonyl sulfide (COS), and carbon dioxide (CO2). These gases probe different aspects of the soil trace-gas microbiology. Soil H2 uptake is a redox reaction driving the energy metabolism of a portion of the microbial community, while soil CO2 respiration is a partial proxy for the overall soil microbial metabolism. In comparison, very little is understood about the microbiological and environmental drivers of soil COS uptake and emissions. In this study, we find that H2, COS, and CO2 soil uptake rates are often correlated, but the relative soil uptake between gases is not constant, and is influenced by seasonality and local environmental conditions. We also consider how differences in the microbial communities and pathways involved in the soil fluxes may explain differences in the observations. Our results are important for informing previous studies using tracer approaches. For example, H2 has been used to estimate COS soil uptake, which must be accounted for to use COS as a carbon cycle tracer. Furthermore, the global distribution of H2 deposition velocity has been inferred from net primary productivity (CO2). Given that insufficient measurement frequency and spatial distribution exists to partition global net

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

    Institute of Scientific and Technical Information of China (English)

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

    2006-01-01

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

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

    Science.gov (United States)

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

    2016-07-01

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

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

    Science.gov (United States)

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

    2016-04-01

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

  9. Exploring the climatic impact of the continental vegetation on the Mezosoic atmospheric CO2 and climate history

    Directory of Open Access Journals (Sweden)

    N. Bouttes

    2008-09-01

    Full Text Available In this contribution, we continue our exploration of the factors defining the Mesozoic climatic history. We improve the Earth system model GEOCLIM designed for long term climate and geochemical reconstructions by adding the explicit calculation of the biome dynamics using the LPJ model. The coupled GEOCLIM-LPJ model thus allows the simultaneous calculation of the climate with a 2-D spatial resolution, the coeval atmospheric CO2, and the continental biome distribution. We found that accounting for the climatic role of the continental vegetation dynamics (albedo change, water cycle and surface roughness modulations strongly affects the reconstructed geological climate. Indeed the calculated partial pressure of atmospheric CO2 over the Mesozoic is twice the value calculated when assuming a uniform constant vegetation. This increase in CO2 is triggered by a global cooling of the continents, itself triggered by a general increase in continental albedo owing to the development of desertic surfaces. This cooling reduces the CO2 consumption through silicate weathering, and hence results in a compensating increase in the atmospheric CO2 pressure. This study demonstrates that the impact of land plants on climate and hence on atmospheric CO2 is as important as their geochemical effect through the enhancement of chemical weathering of the continental surface. Our GEOCLIM-LPJ simulations also define a climatic baseline for the Mesozoic, around which exceptionally cool and warm events can be identified.

  10. THE RESPONSE OF PLANT CARBOHYDRATES TO ELEVATED CO2: WHAT HAVE WE LEARNT FROM FACE STUDIES?

    Energy Technology Data Exchange (ETDEWEB)

    ROGERS,A.; AINSWORTH,E.A.; BERNACCHI,C.J.; GIBON,Y.; STITT,M.; LONG,S.P.

    2004-08-29

    Atmospheric CO{sub 2} concentration ([CO{sub 2}]) is expected to rise from a current level of 372 {micro}mol mol{sup -1} to about 550 {micro}mol mol{sup -1} by the middle of the century (Prentice 2001). Accumulation of foliar carbohydrates is one of the most pronounced and universal changes observed in the leaves of C{sub 3} plants grown at elevated [CO{sub 2}] (Drake et al 1997). Carbohydrates are the product of photosynthetic cells and the substrate for sink metabolism. However, carbohydrates are not just substrates, changes in the composition and pool size of foliar carbohydrates have the potential to communicate source-sink balance and a role for carbohydrates in the regulation of the expression of many plant genes is well established (Koch 1996). Importantly, carbohydrate feedback is thought to be the mechanism through which long-term exposure to elevated [CO{sub 2}] leads to a reduction in carboxylation capacity (Rogers et a1 199S, Long et al 2004). Foliar sugar content has recently been linked to an increased susceptibility of soybeans to insect herbivory (Hamilton et al submitted). In addition increases in the C:N ratio of leaf litter of plants grown at elevated [CO{sub 2}] has been implicated in negative feedbacks on ecosystem productivity (Oechel et al 1994). Understanding of the response of foliar carbohydrates will form an important part of our ability to understand and predict the effects of rising [CO{sub 2}] on plants and ecosystems. As Free-Air CO{sub 2} enrichment technology was emerging, understanding of the link between carbohydrates and plant responses to rising [CO{sub 2}] was increasing. However, there were concerns that the hypotheses generated using model system or from studies on mostly juvenile plants grown for relatively short periods of time in controlled environments may not translate to the field. Of particular concern was the effect of a limited rooting volume. Arp (1991) argued that photosynthetic acclimation to elevated [CO{sub 2

  11. Airborne Laser Absorption Spectrometer Measurements of CO2 Column Mixing Ratios: Source and Sink Detection in the Atmospheric Environment

    Directory of Open Access Journals (Sweden)

    Menzies Robert T.

    2016-01-01

    Full Text Available The JPL airborne Laser Absorption Spectrometer instrument has been flown several times in the 2007-2011 time frame for the purpose of measuring CO2 mixing ratios in the lower atmosphere. The four most recent flight campaigns were on the NASA DC-8 research aircraft, in support of the NASA ASCENDS (Active Sensing of CO2 Emissions over Nights, Days, and Seasons mission formulation studies. This instrument operates in the 2.05-μm spectral region. The Integrated Path Differential Absorption (IPDA method is used to retrieve weighted CO2 column mixing ratios. We present key features of the CO2LAS signal processing, data analysis, and the calibration/validation methodology. Results from flights in various U.S. locations during the past three years include observed mid-day CO2 drawdown in the Midwest, also cases of point-source and regional plume detection that enable the calculation of emission rates.

  12. Airborne Laser Absorption Spectrometer Measurements of CO2 Column Mixing Ratios: Source and Sink Detection in the Atmospheric Environment

    Science.gov (United States)

    Menzies, Robert T.; Spiers, Gary D.; Jacob, Joseph C.

    2016-06-01

    The JPL airborne Laser Absorption Spectrometer instrument has been flown several times in the 2007-2011 time frame for the purpose of measuring CO2 mixing ratios in the lower atmosphere. The four most recent flight campaigns were on the NASA DC-8 research aircraft, in support of the NASA ASCENDS (Active Sensing of CO2 Emissions over Nights, Days, and Seasons) mission formulation studies. This instrument operates in the 2.05-μm spectral region. The Integrated Path Differential Absorption (IPDA) method is used to retrieve weighted CO2 column mixing ratios. We present key features of the CO2LAS signal processing, data analysis, and the calibration/validation methodology. Results from flights in various U.S. locations during the past three years include observed mid-day CO2 drawdown in the Midwest, also cases of point-source and regional plume detection that enable the calculation of emission rates.

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

    DEFF Research Database (Denmark)

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

    2010-01-01

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

  14. Effect of atmospheric CO 2 enrichment on rubisco content in herbaceous species from high and low altitude

    Science.gov (United States)

    Sage, Rowan F.; Schäppi, Bernd; Körner, Christian

    Atmospheric CO 2 enrichment reduces Rubisco content in many species grown in controlled environments; however, relatively few studies have examined CO 2 effects on Rubisco content of plants grown in their natural habitat. We examined the response of Rubisco content to atmospheric CO 2 enrichment (600-680 μmol mol -1 in place of ppm) in 5 herbaceous species growing in a low altitude grassland (550 m) near Basel, Switzerland, and 3 herbaceous species from Swiss alpine grassland at 2470 m. At low elevation, the dominant grass Bromus erectus and the subdominant dicot Sanquisorba minor exhibited 20% to 25% reduction of Rubisco content following high CO 2 exposure; no CO 2 effect was observed in the subdominants Carex flacca, Lotus corniculatus and Trifolium repens. At the Alpine site, the subdominant grass Poa alpina maintained 27% less Rubisco content when grown at high CO 2 while the co-dominant forb Leontodon helveticus had 19% less Rubisco in high CO 2. Rubisco content was unaffected in the tundra dominant Carex curvula. Because the degree of Rubisco modulation was similar between high and low elevation sites, it does not appear that differences in local partial pressure of CO 2 (altitude) or differences in stress in general induce different patterns of modulation of photosynthetic capacity in response to high CO 2. In addition, the degree of Rubisco reduction (<30%) was less than might be indicated by the low biomass response to CO 2 enrichment previously observed at these sites. Thus, plants in Swiss lowland and alpine grassland appear to maintain greater Rubisco concentration and photosynthetic capacity than whole plants can effectively exploit in terms of harvestable biomass.

  15. Impacts of 3 years of elevated atmospheric CO2 on rhizosphere carbon flow and microbial community dynamics.

    Science.gov (United States)

    Drigo, Barbara; Kowalchuk, George A; Knapp, Brigitte A; Pijl, Agata S; Boschker, Henricus T S; van Veen, Johannes A

    2013-02-01

    Carbon (C) uptake by terrestrial ecosystems represents an important option for partially mitigating anthropogenic CO2 emissions. Short-term atmospheric elevated CO2 exposure has been shown to create major shifts in C flow routes and diversity of the active soil-borne microbial community. Long-term increases in CO2 have been hypothesized to have subtle effects due to the potential adaptation of soil microorganism to the increased flow of organic C. Here, we studied the effects of prolonged elevated atmospheric CO2 exposure on microbial C flow and microbial communities in the rhizosphere. Carex arenaria (a nonmycorrhizal plant species) and Festuca rubra (a mycorrhizal plant species) were grown at defined atmospheric conditions differing in CO2 concentration (350 and 700 ppm) for 3 years. During this period, C flow was assessed repeatedly (after 6 months, 1, 2, and 3 years) by (13) C pulse-chase experiments, and label was tracked through the rhizosphere bacterial, general fungal, and arbuscular mycorrhizal fungal (AMF) communities. Fatty acid biomarker analyses and RNA-stable isotope probing (RNA-SIP), in combination with real-time PCR and PCR-DGGE, were used to examine microbial community dynamics and abundance. Throughout the experiment the influence of elevated CO2 was highly plant dependent, with the mycorrhizal plant exerting a greater influence on both bacterial and fungal communities. Biomarker data confirmed that rhizodeposited C was first processed by AMF and subsequently transferred to bacterial and fungal communities in the rhizosphere soil. Over the course of 3 years, elevated CO2 caused a continuous increase in the (13) C enrichment retained in AMF and an increasing delay in the transfer of C to the bacterial community. These results show that, not only do elevated atmospheric CO2 conditions induce changes in rhizosphere C flow and dynamics but also continue to develop over multiple seasons, thereby affecting terrestrial ecosystems C utilization processes.

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

    OpenAIRE

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

    2005-01-01

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

  17. Reactions in a Mixture of CH4 and CO2 under the Aciton of Microwave Discharge at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    YunpengXu; ZhijianTian; 等

    2002-01-01

    Reactions between CH4 and CO2 under the action of continuous microwave discharge at atmospheric pressure were studied in a special homemade reactor,The main products were CO and H2,while acetylene and ethylene were also found in the products.Experimental results show that conversions of CH4 and CO2 could be higher than 90% without the presence of any catalyst,Effects of CO2/CH4 molar ratio and total flow rate of the feed gas on the reaction were also investigated.

  18. The effect of elevated atmospheric CO2 concentration on gross nitrogen and carbon dynamics in a permanent grassland: A field pulse-labeling study

    Science.gov (United States)

    Moser, Gerald; Gorenflo, André; Keidel, Lisa; Brenzinger, Kristof; Elias, Dafydd; McNamara, Niall; Maček, Irena; Vodnik, Dominik; Braker, Gesche; Schimmelpfennig, Sonja; Gerstner, Judith; Müller, Christoph

    2014-05-01

    To predict ecosystem reactions to elevated atmospheric CO2 (eCO2) it is essential to understand the interactions between plant carbon input, microbial community composition and activity and associated nutrient dynamics. Long-term observations (> 14 years) within the Giessen Free Air Carbon dioxide Enrichment (Giessen FACE) study on permanent grassland showed next to an enhanced biomass production an unexpected strong positive feedback effect on ecosystem respiration and nitrous oxide (N2O) production. The overall goal of this study is to understand the long-term effects of eCO2 and carbon input on microbial community composition and activity as well as the associated nitrogen dynamics, N2O production and plant N uptake in the Giessen FACE study on permanent grassland. A combination of 13CO2 pulse labelling with 15N tracing of 15NH4+ and 15NO3- was carried out in situ. Different fractions of soil organic matter (recalcitrant, labile SOM) and the various mineral N pools in the soil (NH4+, NO3-), gross N transformation rates, pool size dependent N2O and N2 emissions as well as N species dependent plant N uptake rates and the origin of the CO2 respiration have been quantified. Microbial analyses include exploring changes in the composition of microbial communities involved in the turnover of NH4+, NO3-, N2O and N2, i.e. ammonia oxidizing, denitrifying, and microbial communities involved in dissimilatory nitrate reduction to ammonia (DNRA). mRNA based analyses will be employed to comparably evaluate the long-term effects of eCO2 on the structure and abundance of these communities, while transcripts of these genes will be used to target the fractions of the communities which actively contribute to N transformations. We quantified the contribution of mycorrhizae on N2O emissions and observed the phenological development of the mycorrhizae after the labeling.

  19. Intraspecific variation in the response of Arabidopsis thaliana lines to elevated atmospheric CO2

    NARCIS (Netherlands)

    Van der Kooij, TAW; De Kok, LJ; Stulen, I.

    2000-01-01

    Since a study of the intraspecific variation in the response to elevated CO2 of different genetic lines of one species might reveal the parameters essential for the response of a species to elevated CO2, thirteen lines of Arabidopsis thaliana L. were exposed to elevated CO2 (700 mul l(-1)). All line

  20. How does atmospheric elevated CO2 affect crop pests and their natural enemies? Case histories from China

    Institute of Scientific and Technical Information of China (English)

    Yu-Cheng Sun; Jin Yin; Fa-Jun Chen; Gang Wu; Feng Ge

    2011-01-01

    Global atmospheric CO2 concentrations have risen rapidly since the Industrial Revolution and are considered as a primary factor in climate change.The effects of elevated CO2 on herbivore insects were found to be primarily through the CO2-induced changes occurring in their host plants,which then possibly affect the intensity and frequency of pest outbreaks on crops.This paper reviews several ongoing research models using primary pests of crops (cotton bollworm,whitefly,aphids) and their natural enemies (ladybeetles,parasitoids) in China to examine insect responses to elevated CO2.It is generally indicated that elevated CO2 prolonged the development of cotton bollworm,Helicoverpa armigera,a chewing insect,by decreasing the foliar nitrogen of host plants.In contrast,the phloemsucking aphid and whitefly insects had species-specific responses to elevated CO2 because of complex interactions that occur in the phloem sieve elements of plants.Some aphid species,such as cotton aphid,Aphis gossypii and wheat aphid,Sitobion avenae,were considered to represent the only feeding guild to respond positively to elevated CO2 conditions.Although whitefly,Bemisia tabaci,a major vector of Tomato yellow leaf curl virus,had neutral response to elevated CO2,the plants became less vulnerable to the virus infection under elevated CO2.The predator and parasitoid response to elevated CO2 were frequently idiosyncratic.These documents from Chinese scientists suggested that elevated CO2 initially affects the crop plant and then cascades to a higher trophic level through the food chain to encompass herbivores (pests),their natural enemies,pathogens and underground nematodes,which disrupt the natural balance observed previously in agricultural ecosystems.

  1. Intensity-Modulated Continuous-Wave Laser Absorption Spectrometer at 1.57 Micrometer for Atmospheric CO2 Measurements

    Science.gov (United States)

    Lin, Bing

    2014-01-01

    Understanding the earth's carbon cycle is essential for diagnosing current and predicting future climates, which requires precise global measurements of atmospheric CO2 through space missions. The Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) space mission will provide accurate global atmospheric CO2 measurements to meet carbon science requirements. The joint team of NASA Langley Research Center and ITT Exelis, Inc. proposes to use the intensity-modulated, continuous-wave (IM-CW) laser absorption spectrometer (LAS) approach for the ASCENDS mission. Prototype LAS instruments have been developed and used to demonstrate the power, signal-to-noise ratio, precision and accuracy, spectral purity, and stability of the measurement and the instrument needed for atmospheric CO2 observations from space. The ranging capability from laser platform to ground surfaces or intermediate backscatter layers is achieved by transmitted range-encoded IM laser signals. Based on the prototype instruments and current lidar technologies, space LAS systems and their CO2 column measurements are analyzed. These studies exhibit a great potential of using IM-CW LAS system for the active space CO2 mission ASCENDS.

  2. Prebiotic synthesis in atmospheres containing CH4, CO, and CO2. II. Hydrogen cyanide, formaldehyde and ammonia.

    Science.gov (United States)

    Schlesinger, G; Miller, S L

    1983-01-01

    The electric discharge synthesis of HCN, H2CO, NH3 and urea has been investigated using various mixtures of CH4, CO, CO2, N2, NH3, H2O, and H2. HCN and H2CO were each synthesized in yields as high as 10% from CH4 as a carbon source. Similar yields were obtained from CO when H2/CO greater than 1.0 and from CO2 when H2/CO2 greater than 2.0. At H2/CO2 less than 1.0 the yields fall off drastically. Good yields of NH3 (0.7 to 5%) and fair yields of urea (0.02 to 0.63%) based on nitrogen were also obtained. The directly synthesized NH3 together with the NH3 obtained from the hydrolysis of HCN, nitriles and urea could have been a major source of ammonia in the atmosphere and oceans of the primitive earth. These results show that prebiotic syntheses from HCN and H2CO to give products such as purines and sugars and some amino acids could have occurred in primitive atmospheres containing CO and CO2 provided the H2/CO and H2/CO2 ratios were greater than about 1.0. Methane containing atmospheres give comparable quantities of HCN and H2CO, and are superior in the synthesis of amino acids.

  3. Nitrogen fertilization has a stronger effect on soil nitrogen-fixing bacterial communities than elevated atmospheric CO2.

    Science.gov (United States)

    Berthrong, Sean T; Yeager, Chris M; Gallegos-Graves, Laverne; Steven, Blaire; Eichorst, Stephanie A; Jackson, Robert B; Kuske, Cheryl R

    2014-05-01

    Biological nitrogen fixation is the primary supply of N to most ecosystems, yet there is considerable uncertainty about how N-fixing bacteria will respond to global change factors such as increasing atmospheric CO2 and N deposition. Using the nifH gene as a molecular marker, we studied how the community structure of N-fixing soil bacteria from temperate pine, aspen, and sweet gum stands and a brackish tidal marsh responded to multiyear elevated CO2 conditions. We also examined how N availability, specifically, N fertilization, interacted with elevated CO2 to affect these communities in the temperate pine forest. Based on data from Sanger sequencing and quantitative PCR, the soil nifH composition in the three forest systems was dominated by species in the Geobacteraceae and, to a lesser extent, Alphaproteobacteria. The N-fixing-bacterial-community structure was subtly altered after 10 or more years of elevated atmospheric CO2, and the observed shifts differed in each biome. In the pine forest, N fertilization had a stronger effect on nifH community structure than elevated CO2 and suppressed the diversity and abundance of N-fixing bacteria under elevated atmospheric CO2 conditions. These results indicate that N-fixing bacteria have complex, interacting responses that will be important for understanding ecosystem productivity in a changing climate.

  4. CO2 sinks and sources from the record obtained in the atmospheric Tall Tower station in LMU (La Muela, Spain)

    Science.gov (United States)

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

    2009-04-01

    Continuous in-situ atmospheric CO2 measurements at La Muela Tall Tower (LMU 41°36'N, 1°6'W, in the middle of the Ebre watershed) are carried out since May 2006 at three different altitudes (79, 57 and 41 m above ground level; ground level 570 m above sea level). Local and advected CO2 influence the diurnal CO2 atmospheric signal in LMU. A method for analyzing both the diurnal cycle release and capture of CO2 has been developed. The atmospheric CO2 series can be splitted into the daily source and the daily sink series. Four-days-backwards GFS-NOAA-NCEP/FLEXPART Lagrangian Dispersion Model simulations have been used to calculate back trajectories of air and the residence time on the Footprint Layer (0-300 magl) for air masses arriving at LMU at 0 and 12 a.m. each day. Four-days-back trajectories allow identifying the possible main influence areas for the air masses arriving at LMU. Therefore, coupling these two methods allows estimating sources, sinks, and trends at the different time scales for the different main upcoming wind trajectories arriving in La Muela. 2008 CO2 mixing ratios in LMU have been evaluated in relationship to well definited source areas and different synoptic conditions.

  5. Effects of Soil Fertility and Atmospheric CO2 Enrichment on Leaf, Stem and Root Dark Respiration of Populus tremuloides

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    An open-top chamber experiment was conducted at the University of Michigan Biological Station near Pellston, Michigan, USA, to study the effects of soil fertility and CO2 on leaf, stem and root dark respiration (Rd) of Populus tremuloides. Overall, area-based daytime leaf Rd (Rda) was significantly greater at elevated than at ambient CO2 in high-fertility soil, but not in low-fertility soil. Mass-based leaf Rd (Rdm) was overall greater for high- than for low-fertility soil grown trees at elevated, but not at ambient CO2. Nighttime leaf Rda and Rdm were unaffected by soil fertility or CO2, nor was stem Rda, which ranged from 1.0 to 1.4 μmol m-2 s-1 in the spring and 3.5 to 4.5 μmol m-2 s-1 in the summer. Root Rda was significantly higher in high- than in low-fertility soil, but was unaffected by CO2. Since biomass production of P. tremuloides will be significantly greater at elevated CO2 while specific Rd will either increase or remain unchanged, we predict that carbon loss to the atmosphere through respiration from this ecologically important species would increase at higher CO2. Soil fertility would also interact with elevated CO2 in affecting the carbon flow in the plant-soil-air system.

  6. Effects of Soil Fertility and Atmospheric CO2 Enrichment on Leaf,Stem and Root Dark Respiration of Populus tremuloides

    Institute of Scientific and Technical Information of China (English)

    X.Z.WANG; P.S.CURTIS; 等

    2001-01-01

    An open-top chamber experiment was conducted at the University of Michigan Biological Station near Pellston,Michigan,USA,to study the effects of soil fertility and CO2 on leaf,sdtem and root dark respiration (Rd) of Populus tremuloides.Overall,area-based daytime leaf Rd(Rda) was significantly greater at elevated than at ambient CO2 in high-fertility soil,but not in low-fertility soil.Mass-based leaf Rd(Rdm) was overall greater for high-than for low-fertility soil grown trees at elevated,but not at ambient CO2 .Nighttime leaf Rda and Rdm were unaffected by soil fertility or CO2,nor was stem Rda ,which ranged from 1.0 to 1.4μmol m-2s-1 in the spring and 3.5 to 4.5μmol m-2s-1 in the summer.Root Rda was significantly higher in high-than in low-fertiliy soil,but was unaffected by CO2.Since biomass production of P.tremuloides will be significantly greater at elevated CO2 while specific Rd will either increase or remain unchanged,we predict that carbon loss to the atmosphere through respiration from this ecologically important species would increase at higher CO2.Soil fertility would also interact with elevated CO2 in affecting the carbon flow in the plant-soil-air system.

  7. Soil and water warming accelerates phenology and down-regulation of leaf photosynthesis of rice plants grown under free-air CO2 enrichment (FACE).

    Science.gov (United States)

    Adachi, Minaco; Hasegawa, Toshihiro; Fukayama, Hiroshi; Tokida, Takeshi; Sakai, Hidemitsu; Matsunami, Toshinori; Nakamura, Hirofumi; Sameshima, Ryoji; Okada, Masumi

    2014-02-01

    To enable prediction of future rice production in a changing climate, we need to understand the interactive effects of temperature and elevated [CO2] (E[CO2]). We therefore examined if the effect of E[CO2] on the light-saturated leaf photosynthetic rate (Asat) was affected by soil and water temperature (NT, normal; ET, elevated) under open-field conditions at the rice free-air CO2 enrichment (FACE) facility in Shizukuishi, Japan, in 2007 and 2008. Season-long E[CO2] (+200 µmol mol(-1)) increased Asat by 26%, when averaged over two years, temperature regimes and growth stages. The effect of ET (+2°C) on Asat was not significant at active tillering and heading, but became negative and significant at mid-grain filling; Asat in E[CO2]-ET was higher than in ambient [CO2] (A[CO2])-NT by only 4%. Photosynthetic down-regulation at E[CO2] also became apparent at mid-grain filling; Asat compared at the same [CO2] in the leaf cuvette was significantly lower in plants grown in E[CO2] than in those grown in A[CO2]. The additive effects of E[CO2] and ET decreased Asat by 23% compared with that of A[CO2]-NT plants. Although total crop nitrogen (N) uptake was increased by ET, N allocation to the leaves and to Rubisco was reduced under ET and E[CO2] at mid-grain filling, which resulted in a significant decrease (32%) in the maximum rate of ribulose-1,5-bisphosphate carboxylation on a leaf area basis. Because the change in N allocation was associated with the accelerated phenology in E[CO2]-ET plants, we conclude that soil and water warming accelerates photosynthetic down-regulation at E[CO2].

  8. Subtarget Effect on Laser Plasma Generated by Transversely Excited Atmospheric CO2 Laser at Atmospheric Gas Pressure

    Science.gov (United States)

    Kagawa, Kiichiro; Lie, Tjung Jie; Hedwig, Rinda; Abdulmajid, Syahrun Nur; Suliyanti, Maria Margaretha; Kurniawan, Hendrik

    2000-05-01

    An experimental study has been carried out on the dynamical process taking place in the laser plasma generated by Transversely Excited Atmospheric CO2 laser (100 mJ, 50 ns) irradiation of a soft sample at surrounding helium pressure of 1 atm. It is shown that the presence of a copper subtarget behind the soft sample is crucial in raising the gushing speed of the atoms to the level adequate for the generation of shock wave laser plasma even at atmospheric pressure. It is also found that the time profiles of spatially integrated emission intensity of the target’s atoms and gas atoms exhibit a characteristic dynamical process that consists of successive excitation and cooling stages even at such a high pressure, which is typical of shock wave laser plasma. It is therefore suggested that the generation of the laser plasma at atmospheric pressure is more likely due to the shock wave mechanism than to the widely known breakdown mechanism. Initial spectrochemical analysis of water from the blow off of a boiler system was also carried out, showing a detection limit of as low as 5 ppm for calcium.

  9. CO2 flux history 1982–2001 inferred from atmospheric data using a global inversion of atmospheric transport

    Directory of Open Access Journals (Sweden)

    M. Heimann

    2003-05-01

    Full Text Available Based on about 20 years of NOAA/CMDL's atmospheric CO2 concentration data and a global atmospheric tracer transport model, we estimate interannual variations and spatial patterns of surface CO2 fluxes in the period 01/1982–12/2000, by using a time-dependent Bayesian inversion technique. To increase the reliability of the estimated temporal features, particular care is exerted towards the selection of data records that are homogeneous in time. Fluxes are estimated on a grid-scale resolution (~8° latitude×10° longitude, constrained by a-priori spatial correlations, and then integrated over different sets of regions. The transport model is driven by interannually varying re-analysed meteorological fields. We make consistent use of unsmoothed measurements. In agreement with previous studies, land fluxes are estimated to be the main driver of interannual variations in the global CO2 fluxes, with the pace predominantly being set by the El Niño/La Niña contrast. An exception is a 2–3 year period of increased sink of atmospheric carbon after Mt. Pinatubo's volcanic eruption in 1991. The largest differences in fluxes between El Niño and La Niña are found in the tropical land regions, the main share being due to the Amazon basin. The flux variations for the Post-Pinatubo period, the 1997/1998 El Niño, and the 1999 La Niña events are exploited to investigate relations between CO2 fluxes and climate forcing. A rough comparison points to anomalies in precipitation as a prominent climate factor for short-term variability of tropical land fluxes, both through their role on NPP and through promoting fire in case of droughts. Some large flux anomalies seem to be directly related to large biomass burning events recorded by satellite observation. Global ocean carbon uptake shows a trend similar to the one expected if ocean uptake scales proportional to the anthropogenic atmospheric perturbation. In contrast to temporal variations, the longterm spatial

  10. Effect of photosynthesis on the abundance of 18O13C16O in atmospheric CO2

    Science.gov (United States)

    Hofmann, Magdalena E. G.; Pons, Thijs L.; Ziegler, Martin; Lourens, Lucas J.; Röckmann, Thomas

    2016-04-01

    The abundance of the isotopologue 18O13C16O (Δ47) in atmospheric air is a promising new tracer for the atmospheric carbon cycle (Eiler and Schauble, 2004; Affek and Eiler, 2006; Affek et al., 2007). The large gross fluxes in CO2 between the atmosphere and biosphere are supposed to play a major role in controlling its abundance. Eiler and Schauble (2004) set up a box model describing the effect of air-leaf interaction on the abundance of 18O13C16O in atmospheric air. The main assumption is that the exchange between CO2 and water within the mesophyll cells will imprint a Δ47 value on the back-diffusing CO2 that reflects the leaf temperature. Additionally, kinetic effects due to CO2 diffusion into and out of the stomata are thought to play a role. We investigated the effect of photosynthesis on the residual CO2 under controlled conditions using a leaf chamber set-up to quantitatively test the model assumptions suggested by Eiler and Schauble (2004). We studied the effect of photosynthesis on the residual CO2 using two C3 and one C4 plant species: (i) sunflower (Helianthus annuus), a C3 species with a high leaf conductance for CO2 diffusion, (ii) ivy (Hedera hibernica), a C3 species with a low conductance, and (iii), maize (Zea mays), a species with the C4 photosynthetic pathway. We also investigated the effect of different light intensities (photosynthetic photon flux density of 200, 700 and 1800 μmol m2s-1), and thus, photosynthetic rate in sunflower and maize. A leaf was mounted in a cuvette with a transparent window and an adjustable light source. The air inside was thoroughly mixed, making the composition of the outgoing air equal to the air inside. A gas-mixing unit was attached at the entrance of the cuvette that mixed air with a high concentration of scrambled CO2 with a Δ47 value of 0 to 0.1‰ with CO2 free air to set the CO2 concentration of ingoing air at 500 ppm. The flow rate through the cuvette was adjusted to the photosynthetic activity of the leaf

  11. Capability of Raman lidar for monitoring the variation of atmospheric CO2 profile

    Institute of Scientific and Technical Information of China (English)

    Zhao Pei-Tao; Zhang Yin-Chao; Wang Lian; Hu Shun-Xing; Su Jia; Cao Kai-Fa; Zhao Yue-Feng; Hu Huan-Ling

    2008-01-01

    Lidar (Light detection and ranging) has special capabilities for remote sensing of many different behaviours of the atmosphere.One of the techniques which show a great deal of promise for several applications is Raman scattering.The detecting capability,including maximum operation range and minimum detectable gas concentration is one of the most significant parameters for lidar remote sensing of pollutants.In this paper,based on the new method for evaluating the capabilities of a Raman lidar system,we present an evaluation of detecting capability of Raman lidar for monitoring atmospheric CO2 in Hefei.Numerical simulations about the influence of atmospheric conditions on lidar detecting capability were carried out,and a conclusion can be drawn that the maximum difference of the operation ranges caused by the weather conditions alone can reach about 0.4 to 0.5kin with a measuring precision within 30ppmv.The range of minimum detectable concentration caused by the weather conditions alone can reach about 20 to 35 ppmv in vertical direction for 20000 shots at a distance of 1 km on the assumption that other parameters are kept constant.The other corresponding parameters under different conditions are also given.The capability of Raman lidar operated in vertical direction was found to be superior to that operated in horizontal direction.During practical measurement with the Raman lidar whose hardware components were fixed,aerosol scattering extinction effect would be a significant factor that influenced the capability of Raman lidar.This work may be a valuable reference for lidar system designing,measurement accuracy improving and data processing.

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

    NARCIS (Netherlands)

    Lanso, A. S.; Bendtsen, J.; Christensen, J. H.; Sorensen, L. L.; Chen, Huilin; Meijer, H. A. J.; Geels, C.

    2015-01-01

    Minimising the uncertainties in estimates of air-sea CO2 exchange is an important step toward increasing the confidence in assessments of the CO2 cycle. Using an atmospheric transport model makes it possible to investigate the direct impact of atmospheric parameters on the air-sea CO2 flux along wit

  13. Elevated atmospheric [CO2 ] can dramatically increase wheat yields in semi-arid environments and buffer against heat waves.

    Science.gov (United States)

    Fitzgerald, Glenn J; Tausz, Michael; O'Leary, Garry; Mollah, Mahabubur R; Tausz-Posch, Sabine; Seneweera, Saman; Mock, Ivan; Löw, Markus; Partington, Debra L; McNeil, David; Norton, Robert M

    2016-06-01

    Wheat production will be impacted by increasing concentration of atmospheric CO2 [CO2 ], which is expected to rise from about 400 μmol mol(-1) in 2015 to 550 μmol mol(-1) by 2050. Changes to plant physiology and crop responses from elevated [CO2 ] (e[CO2 ]) are well documented for some environments, but field-level responses in dryland Mediterranean environments with terminal drought and heat waves are scarce. The Australian Grains Free Air CO2 Enrichment facility was established to compare wheat (Triticum aestivum) growth and yield under ambient (~370 μmol(-1) in 2007) and e[CO2 ] (550 μmol(-1) ) in semi-arid environments. Experiments were undertaken at two dryland sites (Horsham and Walpeup) across three years with two cultivars, two sowing times and two irrigation treatments. Mean yield stimulation due to e[CO2 ] was 24% at Horsham and 53% at Walpeup, with some treatment responses greater than 70%, depending on environment. Under supplemental irrigation, e[CO2 ] stimulated yields at Horsham by 37% compared to 13% under rainfed conditions, showing that water limited growth and yield response to e[CO2 ]. Heat wave effects were ameliorated under e[CO2 ] as shown by reductions of 31% and 54% in screenings and 10% and 12% larger kernels (Horsham and Walpeup). Greatest yield stimulations occurred in the e[CO2 ] late sowing and heat stressed treatments, when supplied with more water. There were no clear differences in cultivar response due to e[CO2 ]. Multiple regression showed that yield response to e[CO2 ] depended on temperatures and water availability before and after anthesis. Thus, timing of temperature and water and the crop's ability to translocate carbohydrates to the grain postanthesis were all important in determining the e[CO2 ] response. The large responses to e[CO2 ] under dryland conditions have not been previously reported and underscore the need for field level research to provide mechanistic understanding for adapting crops to a changing

  14. A multiscale and multidisciplinary investigation of ecosystem-atmosphere CO2 exchange over the rocky mountains of colorado

    Science.gov (United States)

    Sun, Jielun; Oncley, S.P.; Burns, Sean P.; Stephens, B.B.; Lenschow, D.H.; Campos, T.; Monson, Russell K.; Schimel, D.S.; Sacks, W.J.; De Wekker, S. F. J.; Lai, C.-T.; Lamb, B.; Ojima, D.; Ellsworth, P.Z.; Sternberg, L.S.L.; Zhong, S.; Clements, C.; Moore, D.J.P.; Anderson, D.E.; Watt, A.S.; Hu, Jiawen; Tschudi, M.; Aulenbach, S.; Allwine, E.; Coons, T.

    2010-01-01

    A field study combined with modeling investigation demonstrated that the organization of CO2 transport by mountain terrain strongly affects the regional CO2 budget. Atmospheric dynamics can lead to complicated flows generated by inhomogeneous landscapes, topography or synoptic weather systems. The field campaign conducted of a ground deployment, the Carbon in the Mountain Experiment (CME04), and an aircraft deployment of the national Center for Atmospheric Research (NCAR) C-130, the Airborne Carbon in the Mountains Experiment (ACME04) over the period of spring to fall of 2004 to cover the seasonal variation of ecosystem-atmosphere carbon exchange. The role of the mountain circulation in CO2 transport can be played over seemingly flat terrain by mesoscale flows generated by various physical processes. The three dimensional observation strategy considered can also be applied over flat terrain.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  16. Coastal upwelling fluxes of O2, N2O, and CO2 assessed from continuous atmospheric observations at Trinidad, California

    Directory of Open Access Journals (Sweden)

    T. J. Lueker

    2004-01-01

    Full Text Available Continuous atmospheric records of O2/N2, CO2 and N2O obtained at Trinidad, California document the effects of air-sea exchange during coastal upwelling and plankton bloom events. The atmospheric records provide continuous observations of air-sea fluxes related to synoptic scale upwelling events over several upwelling seasons. Combined with satellite, buoy and local meteorology data, calculated anomalies in O2/N2 and N2O were utilized in a simple atmospheric transport model to compute air-sea fluxes during coastal upwelling. CO2 fluxes were linked to the oceanic component of the O2 fluxes through local hydrographic data and estimated as a function of upwelling intensity (surface ocean temperature and wind speed. Regional air-sea fluxes of O2/N2, N2O, and CO2 during coastal upwelling were estimated with the aid of satellite wind and SST data. Upwelling CO2 fluxes were found to represent ~10% of export production along the northwest coast of North America. Synoptic scale upwelling events impact the net exchange of atmospheric CO2 along the coastal margin, and will vary in response to the frequency and duration of alongshore winds that are subject to climate change.

  17. Bacteria and fungi respond differently to multifactorial climate change in a temperate heathland, traced with 13C-glycine and FACE CO2.

    Directory of Open Access Journals (Sweden)

    Louise C Andresen

    Full Text Available It is vital to understand responses of soil microorganisms to predicted climate changes, as these directly control soil carbon (C dynamics. The rate of turnover of soil organic carbon is mediated by soil microorganisms whose activity may be affected by climate change. After one year of multifactorial climate change treatments, at an undisturbed temperate heathland, soil microbial community dynamics were investigated by injection of a very small concentration (5.12 µg C g(-1 soil of (13C-labeled glycine ((13C2, 99 atom % to soils in situ. Plots were treated with elevated temperature (+1°C, T, summer drought (D and elevated atmospheric carbon dioxide (510 ppm [CO2], as well as combined treatments (TD, TCO2, DCO2 and TDCO2. The (13C enrichment of respired CO2 and of phospholipid fatty acids (PLFAs was determined after 24 h. (13C-glycine incorporation into the biomarker PLFAs for specific microbial groups (Gram positive bacteria, Gram negative bacteria, actinobacteria and fungi was quantified using gas chromatography-combustion-stable isotope ratio mass spectrometry (GC-C-IRMS. Gram positive bacteria opportunistically utilized the freshly added glycine substrate, i.e. incorporated (13C in all treatments, whereas fungi had minor or no glycine derived (13C-enrichment, hence slowly reacting to a new substrate. The effects of elevated CO2 did suggest increased direct incorporation of glycine in microbial biomass, in particular in G(+ bacteria, in an ecosystem subjected to elevated CO2. Warming decreased the concentration of PLFAs in general. The FACE CO2 was (13C-depleted (δ(13C = 12.2‰ compared to ambient (δ(13C = ∼-8‰, and this enabled observation of the integrated longer term responses of soil microorganisms to the FACE over one year. All together, the bacterial (and not fungal utilization of glycine indicates substrate preference and resource partitioning in the microbial community, and therefore suggests a diversified response pattern to

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

    Science.gov (United States)

    Washington, Warren M.; Meehl, Gerald A.

    1989-06-01

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

  19. Lateral transport of soil carbon and land-atmosphere CO2 flux induced by water erosion in China.

    Science.gov (United States)

    Yue, Yao; Ni, Jinren; Ciais, Philippe; Piao, Shilong; Wang, Tao; Huang, Mengtian; Borthwick, Alistair G L; Li, Tianhong; Wang, Yichu; Chappell, Adrian; Van Oost, Kristof

    2016-06-14

    Soil erosion by water impacts soil organic carbon stocks and alters CO2 fluxes exchanged with the atmosphere. The role of erosion as a net sink or source of atmospheric CO2 remains highly debated, and little information is available at scales larger than small catchments or regions. This study attempts to quantify the lateral transport of soil carbon and consequent land-atmosphere CO2 fluxes at the scale of China, where severe erosion has occurred for several decades. Based on the distribution of soil erosion rates derived from detailed national surveys and soil carbon inventories, here we show that water erosion in China displaced 180 ± 80 Mt C⋅y(-1) of soil organic carbon during the last two decades, and this resulted a net land sink for atmospheric CO2 of 45 ± 25 Mt C⋅y(-1), equivalent to 8-37% of the terrestrial carbon sink previously assessed in China. Interestingly, the "hotspots," largely distributed in mountainous regions in the most intensive sink areas (>40 g C⋅m(-2)⋅y(-1)), occupy only 1.5% of the total area suffering water erosion, but contribute 19.3% to the national erosion-induced CO2 sink. The erosion-induced CO2 sink underwent a remarkable reduction of about 16% from the middle 1990s to the early 2010s, due to diminishing erosion after the implementation of large-scale soil conservation programs. These findings demonstrate the necessity of including erosion-induced CO2 in the terrestrial budget, hence reducing the level of uncertainty.

  20. Lateral transport of soil carbon and land-atmosphere CO2 flux induced by water erosion in China

    Science.gov (United States)

    Yue, Yao; Ni, Jinren; Ciais, Philippe; Piao, Shilong; Wang, Tao; Huang, Mengtian; Borthwick, Alistair G. L.; Li, Tianhong; Wang, Yichu; Chappell, Adrian; Van Oost, Kristof

    2016-06-01

    Soil erosion by water impacts soil organic carbon stocks and alters CO2 fluxes exchanged with the atmosphere. The role of erosion as a net sink or source of atmospheric CO2 remains highly debated, and little information is available at scales larger than small catchments or regions. This study attempts to quantify the lateral transport of soil carbon and consequent land-atmosphere CO2 fluxes at the scale of China, where severe erosion has occurred for several decades. Based on the distribution of soil erosion rates derived from detailed national surveys and soil carbon inventories, here we show that water erosion in China displaced 180 ± 80 Mt Cṡy-1 of soil organic carbon during the last two decades, and this resulted a net land sink for atmospheric CO2 of 45 ± 25 Mt Cṡy-1, equivalent to 8-37% of the terrestrial carbon sink previously assessed in China. Interestingly, the “hotspots,” largely distributed in mountainous regions in the most intensive sink areas (>40 g Cṡm-2ṡy-1), occupy only 1.5% of the total area suffering water erosion, but contribute 19.3% to the national erosion-induced CO2 sink. The erosion-induced CO2 sink underwent a remarkable reduction of about 16% from the middle 1990s to the early 2010s, due to diminishing erosion after the implementation of large-scale soil conservation programs. These findings demonstrate the necessity of including erosion-induced CO2 in the terrestrial budget, hence reducing the level of uncertainty.

  1. [Effect of atmospheric CO2 concentration and nitrogen application level on absorption and transportation of nutrient elements in oilseed rape].

    Science.gov (United States)

    Wang, Wen-ming; Zhang, Zhen-hua; Song, Hai-xing; Liu, Qiang; Rong, Xiang-min; Guan, Chun-yun; Zeng, Jing; Yuan, Dan

    2015-07-01

    Effect of elevated atmospheric-CO2 (780 µmol . mol-1) on the absorption and transportation of secondary nutrient elements (calcium, magnesium, sulphur) and micronutrient elements (iron, manganese, zinc, molybdenum and boron) in oilseed rape at the stem elongation stage were studied by greenhouse simulated method. Compared with the ambient CO2 condition, the content of Zn in stem was increased and the contents of other nutrient elements were decreased under the elevated atmospheric-CO2 with no nitrogen (N) application; the contents of Ca, S, B and Zn were increased, and the contents of Mg, Mn, Mo and Fe were decreased under the elevated atmospheric CO2 with N application (0.2 g N . kg-1 soil); except the content of Mo in leaf was increased, the contents of other nutrient elements were decreased under the elevated atmospheric-CO2 with two levels of N application. Compared with the ambient CO2 condition, the amounts of Ca and S relative to the total amount of secondary nutrient elements in stem and the amounts of B and Zn relative to the total amount of micronutrient elements in stem were increased under the elevated-CO2 treatment with both levels of N application, and the corresponding values of Mg, Fe, Mn and Mo were decreased; no-N application treatment increased the proportion of Ca distributed into the leaves, and the proportion of Mg distributed into leaves was increased by the normal-N application level; the proportions of Mn, Zn and Mo distributed into the leaves were increased at both N application levels. Without N application, the elevation of atmospheric CO2 increased the transport coefficients of SFe, Mo and SS,B, but decreased the transport coefficients of SMg,Fe, SMg, Mn and SS,Fe, indicating the proportions of Mo, S transported into the upper part of plant tissues was higher than that of Fe, and the corresponding value of B was higher than that observed for S, the corresponding value of Mg was higher than that of Fe and Mn. Under normal-N application

  2. Evolution and challenges of dynamic global vegetation models for some aspects of plant physiology and elevated atmospheric CO2

    Science.gov (United States)

    Rezende, L. F. C.; Arenque, B. C.; Aidar, S. T.; Moura, M. S. B.; Von Randow, C.; Tourigny, E.; Menezes, R. S. C.; Ometto, J. P. H. B.

    2016-07-01

    Dynamic global vegetation models (DGVMs) simulate surface processes such as the transfer of energy, water, CO2, and momentum between the terrestrial surface and the atmosphere, biogeochemical cycles, carbon assimilation by vegetation, phenology, and land use change in scenarios of varying atmospheric CO2 concentrations. DGVMs increase the complexity and the Earth system representation when they are coupled with atmospheric global circulation models (AGCMs) or climate models. However, plant physiological processes are still a major source of uncertainty in DGVMs. The maximum velocity of carboxylation (Vcmax), for example, has a direct impact over productivity in the models. This parameter is often underestimated or imprecisely defined for the various plant functional types (PFTs) and ecosystems. Vcmax is directly related to photosynthesis acclimation (loss of response to elevated CO2), a widely known phenomenon that usually occurs when plants are subjected to elevated atmospheric CO2 and might affect productivity estimation in DGVMs. Despite this, current models have improved substantially, compared to earlier models which had a rudimentary and very simple representation of vegetation-atmosphere interactions. In this paper, we describe this evolution through generations of models and the main events that contributed to their improvements until the current state-of-the-art class of models. Also, we describe some main challenges for further improvements to DGVMs.

  3. Evolution and challenges of dynamic global vegetation models for some aspects of plant physiology and elevated atmospheric CO2.

    Science.gov (United States)

    Rezende, L F C; Arenque, B C; Aidar, S T; Moura, M S B; Von Randow, C; Tourigny, E; Menezes, R S C; Ometto, J P H B

    2016-07-01

    Dynamic global vegetation models (DGVMs) simulate surface processes such as the transfer of energy, water, CO2, and momentum between the terrestrial surface and the atmosphere, biogeochemical cycles, carbon assimilation by vegetation, phenology, and land use change in scenarios of varying atmospheric CO2 concentrations. DGVMs increase the complexity and the Earth system representation when they are coupled with atmospheric global circulation models (AGCMs) or climate models. However, plant physiological processes are still a major source of uncertainty in DGVMs. The maximum velocity of carboxylation (Vcmax), for example, has a direct impact over productivity in the models. This parameter is often underestimated or imprecisely defined for the various plant functional types (PFTs) and ecosystems. Vcmax is directly related to photosynthesis acclimation (loss of response to elevated CO2), a widely known phenomenon that usually occurs when plants are subjected to elevated atmospheric CO2 and might affect productivity estimation in DGVMs. Despite this, current models have improved substantially, compared to earlier models which had a rudimentary and very simple representation of vegetation-atmosphere interactions. In this paper, we describe this evolution through generations of models and the main events that contributed to their improvements until the current state-of-the-art class of models. Also, we describe some main challenges for further improvements to DGVMs.

  4. Atmospheric CO2 mole fraction affects stand-scale carbon use efficiency of sunflower by stimulating respiration in light.

    Science.gov (United States)

    Gong, Xiao Ying; Schäufele, Rudi; Lehmeier, Christoph Andreas; Tcherkez, Guillaume; Schnyder, Hans

    2017-03-01

    Plant carbon-use-efficiency (CUE), a key parameter in carbon cycle and plant growth models, quantifies the fraction of fixed carbon that is converted into net primary production rather than respired. CUE has not been directly measured, partly because of the difficulty of measuring respiration in light. Here, we explore if CUE is affected by atmospheric CO2 . Sunflower stands were grown at low (200 μmol mol(-1) ) or high CO2 (1000 μmol mol(-1) ) in controlled environment mesocosms. CUE of stands was measured by dynamic stand-scale (13) C labelling and partitioning of photosynthesis and respiration. At the same plant age, growth at high CO2 (compared with low CO2 ) led to 91% higher rates of apparent photosynthesis, 97% higher respiration in the dark, yet 143% higher respiration in light. Thus, CUE was significantly lower at high (0.65) than at low CO2 (0.71). Compartmental analysis of isotopic tracer kinetics demonstrated a greater commitment of carbon reserves in stand-scale respiratory metabolism at high CO2 . Two main processes contributed to the reduction of CUE at high CO2 : a reduced inhibition of leaf respiration by light and a diminished leaf mass ratio. This work highlights the relevance of measuring respiration in light and assessment of the CUE response to environment conditions.

  5. Airborne & Ground-based measurements of atmospheric CO2 using the 1.57-μm laser absorption spectrometer

    Science.gov (United States)

    Sakaizawa, D.; Kawakami, S.; Nakajima, M.; Tanaka, T.; Miyamoto, Y.; Morino, I.; Uchino, O.; Asai, K.

    2009-12-01

    Greenhouse gases observing satellite (GOSAT) started the measurement of global CO2 abundances to reveal its continental inventory using two passive remote sensors. The goal that the sensor needs to be done is to achieve an 1% relative accuracy in order to reduce uncertainties of CO2 budget. Nevertheless, in the future global CO2 monitoring, more accurate measurement of global tropospheric CO2 abundances with the monthly regional scale are required to improve the knowledge of CO2 exchanges among the land, ocean, and atmosphere. In order to fulfill demands, a laser remote sensor, such as DIAL or laser absorption spectrometer (LAS), is a potential candidate of future space-based missions. Nowadays, those technologies are required to demonstrate an accuracy of the few-ppm level through airborne & ground-based measurements. We developed the prototype of the 1.57um LAS for a step of the next missions and perform it at the ground-based and airborne platform to show the properly validated performance in the framework of GOSAT validation. Our CO2 LAS is consisted of all optical fiber circuits & compact receiving /transmitting optics to achieve the portable, flexible and rigid system. The optical sources of on- and off-line are distributed feedback lasers, which are tuned at the strong and weak position of the R12 line in the (30012rate and combined and amplified using an erbium doped fiber amplifier. Scattered signals from the hard target are collected by the 11cm receiving telescope and detected and stored into the laptop computer. After that, we evaluated the atmospheric CO2 density using the meteorological parameters and ratio between the on- and off-line signals. The resultant of the ground-based measurement of 3km optical length indicated that the statistical error of the path averaged atmospheric CO2 density is less than 2.8ppm with 25 minutes averaging. The variation of the path averaged atmospheric CO2 is also quite consistent with that obtained from the in

  6. Coupling between atmospheric CO2 and temperature during the onset of the Little Ice Age

    OpenAIRE

    Hoof, T.B. van

    2004-01-01

    Present day global warming is primarily caused by the greenhouse effect of the increased CO2 emissions since the onset of the industrial revolution. A coupling between temperature and the greenhouse gas CO2 has also been observed in several ice-core records on a glacial-interglacial timescale as well as on a millennial timescale during the glacials. In marked contrast, no significant ice-derived CO2 fluctuations occur on centennial time scales contemporaneously with well-documented cooling ev...

  7. Phenol-Formaldehyde Resin-Based Carbons for CO2 Separation at Sub-Atmospheric Pressures

    OpenAIRE

    2016-01-01

    The challenge of developing effective separation and purification technologies that leave much smaller energy footprints is greater for carbon dioxide (CO2) than for other gases. In addition to its involvement in climate change, CO2 is present as an impurity in biogas and bio-hydrogen (biological production by dark fermentation), in post-combustion processes (flue gas, CO2-N2) and many other gas streams. Selected phenol-formaldehyde resin-based activated carbons prepared in our laboratory hav...

  8. Fossil plants indicate that the most significant decrease in atmospheric CO2 happened prior to the Eocene-Oligocene boundary

    Science.gov (United States)

    Steinthorsdottir, Margret; Porter, Amanda; Holohan, Aidan; Kunzmann, Lutz; Collinson, Margaret; McElwain, Jennifer

    2016-04-01

    A unique stratigraphic sequence of fossil leaves of Eotrigonobalanus furcinervis (extinct trees of the beech family, Fagaceae) from central Germany was utilized to derive an atmospheric pCO2 record with multiple data points spanning the late middle to late Eocene, two sampling levels which may be earliest Oligocene, and two samples from later in the Oligocene. Using the stomatal proxy, which relies on the inverse relationship between pCO2 and leaf stomatal density, we show that a ~40% decrease in pCO2 preceded the large shift in marine oxygen isotope records that characterizes the Eocene-Oliogocene climate transition. The results endorse the theory that pCO2 drawdown was the main forcer of the Eocene-Oligocene climate change, and a 'tipping point' was reached in the latest Eocene, triggering the plunge of the Earth System into icehouse conditions.

  9. Coal devolatilization and char conversion under suspension fired conditions in O2/N2 and O2/CO2 atmospheres

    DEFF Research Database (Denmark)

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

    2010-01-01

    was burned at 1573 K and 1673 K a faster conversion was found in N2 suggesting that the lower molecular diffusion coefficient of O2 in CO2 lowers the char conversion rate when external mass transfer influences combustion. The reaction of char with CO2 was not observed to have an influence on char conversion......The aim of the present investigation is to examine differences between O2/N2 and O2/CO2 atmospheres during devolatilization and char conversion of a bituminous coal at conditions covering temperatures between 1173 K and 1673 K and inlet oxygen concentrations between 5 and 28 vol.%. The experiments...... indicates that a shift from air to oxy-fuel combustion does not influence the devolatilization process significantly. Char combustion experiments yielded similar char conversion profiles when N2 was replaced with CO2 under conditions where combustion was primarily controlled by chemical kinetics. When char...

  10. Pulsed Airborne Lidar Measurements of Atmospheric CO2 Column Absorption and Line Shapes from 3-13 km Altitudes

    Science.gov (United States)

    Abshire, James; Riris, Haris; Allan, Graham; Weaver, Clark; Mao, Jianping; Sun, Xiaoli; Hasselbrack, William

    2010-01-01

    We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's planned ASCENDS space mission. Our technique uses two pulsed laser transmitters allowing simultaneous measurement of a CO2 absorption line in the 1570 nm band, O2 extinction in the Oxygen A-band and surface height and backscatter. The lidar measures the energy and time of flight of the laser echoes reflected from the atmosphere and surface. The lasers are rapidly and precisely stepped in wavelength across the CO2 line and an O2 line region during the measurement. The direct detection receiver uses a telescope and photon counting detectors, and measures the background light and energies of the laser echoes from the surface along with scattering from any aerosols in the path. The gas extinction and column densities for the CO2 and O2 gases are estimated from the ratio of the on- and off- line signals via the DIAL technique. Time gating is used to isolate the laser echo signals from the surface, and to reject laser photons scattered in the atmosphere. The time of flight of the laser pulses are also used to estimate the height of the scattering surface and to identify cases of mixed cloud and ground scattering. We have developed an airborne lidar to demonstrate the CO2 measurement from the NASA Glenn Lear-25 aircraft. The airborne lidar steps the pulsed laser's wavelength across the selected CO2 line with 20 steps per scan. The line scan rate is 450 Hz, the laser pulse widths are 1 usec, and laser pulse energy is 24 uJ. The time resolved laser backscatter is collected by a 20 cm telescope, detected by a photomultiplier and is recorded by a photon counting system. We made initial airborne measurements on flights during fall 2008. Laser backscatter and absorption measurements were made over a variety of land and water surfaces and through thin clouds. The atmospheric CO2 column measurements using the 1572.33 nm CO2 lines. Two flights were made above the

  11. Tree species influence soil-atmosphere fluxes of the greenhouse gases CO2, CH4 and N2O

    Science.gov (United States)

    Steffens, Christina; Vesterdal, Lars; Pfeiffer, Eva-Maria

    2016-04-01

    In the temperate zone, forests are the greatest terrestrial sink for atmospheric CO2, and tree species affect soil C stocks and soil CO2 emissions. When considering the total greenhouse gas (GHG) balance of the forest soil, the relevant GHGs CH4 and N2O should also be considered as they have a higher global warming potential than CO2. The presented data are first results from a field study in a common garden site in Denmark where tree species with ectomycorrhizal colonization (beech - Fagus sylvatica, oak - Quercus robur) and with arbuscular mycorrhizal colonization (maple - Acer pseudoplatanus, ash - Fraxinus excelsior) have been planted in monocultures in adjacent blocks of about 0.25 ha in the year 1973 on former arable land. The soil-atmosphere fluxes of all three gases were measured every second week since August 2015. The hypothesis is that the total GHG efflux from forest soil would differ between species, and that these differences could be related to the type of mycorrhizal association and leaf litter quality. Preliminary results (August to December 2015) indicate that tree species influence the fluxes (converted to CO2-eq) of the three GHGs. Total soil CO2 efflux was in the low end of the range reported for temperate broadleaved forests but similar to the measurements at the same site approximately ten years ago. It was highest under oak (9.6±2.4 g CO2 m-2 d-1) and lowest under maple (5.2±1.6 g CO2 m-2 d-1). In contrast, soil under oak was a small but significant sink for CH4(-0.005±0.003 g CO2-eq m-2 d-1), while there were almost no detectable CH4 fluxes in maple. Emissions of N2O were highest under beech (0.6±0.6 g CO2-eq m-2 d-1) and oak (0.2±0.09 g CO2-eq m-2 d-1) and lowest under ash (0.03±0.04 g CO2-eq m-2 d-1). In the total GHG balance, soil CH4 uptake was negligible (≤0.1% of total emissions). Emissions of N2O (converted to CO2-eq) contributed mycorrhiza and produce leaf litter with a lower lignin:N ratio.

  12. Root dynamics in an artificially constructed regenerating longleaf pine ecosystem are affected by atmospheric CO(2) enrichment.

    Science.gov (United States)

    Pritchard, S G.; Davis, M A.; Mitchell, R J.; Prior, S A.; Boykin, D L.; Rogers, H H.; Runion, G B.

    2001-08-01

    Differential responses to elevated atmospheric CO(2) concentration exhibited by different plant functional types may alter competition for above- and belowground resources in a higher CO(2) world. Because C allocation to roots is often favored over C allocation to shoots in plants grown with CO(2) enrichment, belowground function of forest ecosystems may change significantly. We established an outdoor facility to examine the effects of elevated CO(2) on root dynamics in artificially constructed communities of five early successional forest species: (1) a C(3) evergreen conifer (longleaf pine, Pinus palustris Mill.); (2) a C(4) monocotyledonous bunch grass (wiregrass, Aristida stricta Michx.); (3) a C(3) broadleaf tree (sand post oak, Quercus margaretta); (4) a C(3) perennial herbaceous legume (rattlebox, Crotalaria rotundifolia Walt. ex Gemel); and (5) an herbaceous C(3) dicotyledonous perennial (butterfly weed, Asclepias tuberosa L.). These species are common associates in early successional longleaf pine savannahs throughout the southeastern USA and represent species that differ in life-form, growth habit, physiology, and symbiotic relationships. A combination of minirhizotrons and soil coring was used to examine temporal and spatial rooting dynamics from October 1998 to October 1999. CO(2)-enriched plots exhibited 35% higher standing root crop length, 37% greater root length production per day, and 47% greater root length mortality per day. These variables, however, were enhanced by CO(2) enrichment only at the 10-30 cm depth. Relative root turnover (flux/standing crop) was unchanged by elevated CO(2). Sixteen months after planting, root biomass of pine was 62% higher in elevated compared to ambient CO(2) plots. Conversely, the combined biomass of rattlebox, wiregrass, and butterfly weed was 28% greater in ambient compared to high CO(2) plots. There was no difference in root biomass of oaks after 16 months of exposure to elevated CO(2). Using root and shoot

  13. Monitoring of leaked CO2 through sediment, water column and atmosphere in sub-seabed CCS experiment

    Science.gov (United States)

    Shitashima, K.; Sakamoto, A.; Maea, Y.

    2013-12-01

    CO2 capture and storage in sub-seabed geological formations (sub-seabed CCS) is currently being studied as a feasible option to mitigate the accumulation of anthropogenic CO2 in the atmosphere. In implementing sub-seabed CCS, detecting and monitoring the impact of the sequestered CO2 on the ocean environment is highly important. The first controlled CO2 release experiment, entitled 'Quantifying and Monitoring Potential Ecosystem Impacts of Geological Carbon Storage (QICS)', took place in Ardmucknish Bay, Oban, in May-July 2012. We applied the in-situ pH/pCO2/ORP sensor to the QICS experiment for detection and monitoring of leaked CO2, and carried out several observations. The on-line sensor that was connected by 400m of RS422 cable was deployed close to the CO2 leakage (bubbling) point, and the fluctuations of pH, pCO2 and ORP were monitored in real-time in a observation van on land. Three sets of off-line sensors were also placed on seafloor in respective points (release point, and two low impacted regions at 25m and 75m distant) for three months. The long-term monitoring of pH in sediment at 50cm depth under the seafloor was conducted. The spear type electrode was stabbed into sediment by diver near the CO2 leakage point. Wide-area mapping surveys of pH, pCO2 and ORP in seawater around the leakage point were carried out by AUV (REMUS-100) that some chemical sensors were installed in. The AUV cruised along the grid line in two layers of 4m and 2m above the seafloor during both of periods of low tide and high tide. Atmospheric CO2 in sea surface above the leakage point was observed by the LI-COR CO2 Analyzer. The analyzer was attached to the bow of ship, and the ship navigated a wide-area along a grid observation line during both of periods of low tide and high tide.

  14. Mechanisms for synoptic transport of atmospheric CO2 in the midlatitudes and tropics

    Directory of Open Access Journals (Sweden)

    R. Lokupitiya

    2008-06-01

    Full Text Available Synoptic variations of CO2 mixing ratio produced by interactions between weather and surface fluxes are investigated mechanistically and quantitatively in midlatitude and tropical regions using continuous in-situ CO2 observations in North America, South America and Europe and forward chemical transport model simulations with the Parameterized Chemistry Transport Model. Frontal CO2 climatologies show consistently strong, characteristic frontal CO2 signals throughout the midlatitudes of North America and Europe. Transitions between synoptically identifiable CO2 air masses or transient spikes along the frontal boundary typically characterize these signals. One case study of a summer cold front shows that CO2 gradients organize with deformational flow along weather fronts producing strong and spatially coherent variations. A boundary layer budget equation is constructed in order to determine contributions to boundary layer CO2 tendencies by horizontal and vertical advection, moist convection, and biological and anthropogenic surface fluxes. Analysis of this equation suggests that, in midlatitudes, advection is responsible for 50–90% of the amplitude of frontal variations in the summer, depending on upstream influences, and 50% of all day-to-day variations throughout the year. Simulations testing sensitivity to local cloud and surface fluxes further suggest that horizontal advection is a major source of CO2 variability in midlatitudes. In the tropics, coupling between convective transport and surface CO2 flux is most important. Due to the scarcity of tropical observations available at the time of this study, future work should extend such mechanistic analysis to additional tropical locations.

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

    Science.gov (United States)

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

    2015-12-01

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

  16. Interaction between Medicago truncatula and Pseudomonas fluorescens: evaluation of costs and benefits across an elevated atmospheric CO(2.

    Directory of Open Access Journals (Sweden)

    Clémentine Lepinay

    Full Text Available Soil microorganisms play a key role in both plants nutrition and health. Their relation with plant varies from mutualism to parasitism, according to the balance of costs and benefits for the two partners of the interaction. These interactions involved the liberation of plant organic compounds via rhizodeposition. Modification of atmospheric CO(2 concentration may affect rhizodeposition and as a consequence trophic interactions that bind plants and microorganisms. Positive effect of elevated CO(2 on plants are rather well known but consequences for micoorganisms and their interactions with plants are still poorly understood. A gnotobiotic system has been developed to study the interaction between Medicago truncatula Jemalong J5 and the mutualistic bacteria Pseudomonas fluorescens strain C7R12 under two atmospheric CO(2 concentrations: ambient (365 ppm versus enriched (750 ppm. Costs and benefits for each partner have been determined over time by measuring plant development and growth, the C and N contents of the various plant parts and the density of the bacteria in rhizosphere compartments. Following the increase in CO(2, there was a beneficial effect of P. fluorescens C7R12 on development, vegetative growth, and C/N content of M. truncatula. Concerning plant reproduction, an early seed production was noticed in presence of the bacterial strain combined with increased atmospheric CO(2 conditions. Paradoxically, this transient increase in seed production was correlated with a decrease in bacterial density in the rhizosphere soil, revealing a cost of increased CO(2 for the bacterial strain. This shift of costs-benefits ratio disappeared later during the plant growth. In conclusion, the increase in CO(2 concentration modifies transiently the cost-benefit balance in favor of the plant. These results may be explained either by a competition between the two partners or a change in bacterial physiology. The ecosystem functioning depends on the

  17. Are microbial N transformation rates in a permanent grassland soil after 17 years of elevated atmospheric CO2 sensitive to soil temperature?

    Science.gov (United States)

    Moser, Gerald; Gorenflo, André; Brenzinger, Kristof; Clough, Tim; Braker, Gesche; Müller, Christoph

    2016-04-01

    Long-term observations (17 years) within the Giessen Free Air Carbon dioxide Enrichment (Giessen FACE) study on permanent grassland showed that the carbon fertilization caused significant changes in the ecosystem nitrogen cycle. These changes are responsible for a doubling of annual N2O emissions under elevated atmospheric CO2 (eCO2) caused by increased emissions during the plant growing season. The goal of this lab study was to understand how soil temperature influences the long-term effects of eCO2 and plant carbon input on microbial N transformations in the Giessen FACE. Therefore, a pulse labelling study with 15N tracing of 15NH4+ and 15NO3- was carried out with incubated soil samples from elevated and ambient CO2 FACE rings in climate chambers at two different temperatures (10°C and 19°C), while water filled pore space of the samples was adjusted to the same level. The various N pools in the soil (NH4+, NO3-, NO2-, soil organic matter), N2O emissions and simultaneous gross N transformation rates were quantified. The quantification of the gross N transformations are based on the turnover of 15NH4+, 15NO3-, 15NO2- and shall illuminate the interaction between carbon fertilization, temperature and changes in nitrogen cycle in this grassland soil. While the soil respiration after labelling was significantly increased at 19°C compared to 10°C, N2O emissions showed no significant differences. There were also no significant differences of N2O emissions between soil samples from control and elevated CO2 rings within each temperature level. As the soil temperature (within the range of 10-19°C) had no significant effects on N transformations responsible for the observed doubling of N2O emissions under eCO2, it seems most likely that other factors like direct carbon input by plants and/or soil moisture differences between ambient and elevated rings in the field are responsible for the observed increase in N2O emissions under eCO2.

  18. Plant species, atmospheric CO2 and soil N interactively or additively control C allocation within plant-soil systems

    Institute of Scientific and Technical Information of China (English)

    FU; Shenglei; Howard; Ferris

    2006-01-01

    Two plant species, Medicago truncatula (legume) and Avena sativa (non-legume), were grown in low- or high-N soils under two CO2 concentrations to test the hypothesis whether C allocation within plant-soil system is interactively or additively controlled by soil N and atmospheric CO2 is dependent upon plant species. The results showed the interaction between plant species and soil N had a significant impact on microbial activity and plant growth. The interaction between CO2 and soil N had a significant impact on soil soluble C and soil microbial biomass C under Madicago but not under Avena. Although both CO2 and soil N affected plant growth significantly, there was no interaction between CO2 and soil N on plant growth. In other words, the effects of CO2 and soil N on plant growth were additive. We considered that the interaction between N2 fixation trait of legume plant and elevated CO2 might have obscured the interaction between soil N and elevated CO2 on the growth of legume plant. In low-N soil, the shoot-to-root ratio of Avena dropped from 2.63±0.20 in the early growth stage to 1.47±0.03 in the late growth stage, indicating that Avena plant allocated more energy to roots to optimize nutrient uptake (i.e. N) when soil N was limiting. In high-N soil, the shoot-to-root ratio of Medicago increased significantly over time (from 2.45±0.30 to 5.43±0.10), suggesting that Medicago plants allocated more energy to shoots to optimize photosynthesis when N was not limiting.The shoot-to-root ratios were not significantly different between two CO2 levels.

  19. Plant species, atmospheric CO2 and soil N interactively or additively control C allocation within plant-soil systems.

    Science.gov (United States)

    F U, Shenglei; Ferris, Howard

    2006-12-01

    Two plant species, Medicago truncatula (legume) and Avena sativa (non-legume), were grown in low- or high-N soils under two CO2 concentrations to test the hypothesis whether C allocation within plant-soil system is interactively or additively controlled by soil N and atmospheric CO2 is dependent upon plant species. The results showed the interaction between plant species and soil N had a significant impact on microbial activity and plant growth. The interaction between CO2 and soil N had a significant impact on soil soluble C and soil microbial biomass C under Madicago but not under Avena. Although both CO2 and soil N affected plant growth significantly, there was no interaction between CO2 and soil N on plant growth. In other words, the effects of CO2 and soil N on plant growth were additive. We considered that the interaction between N2 fixation trait of legume plant and elevated CO2 might have obscured the interaction between soil N and elevated CO2 on the growth of legume plant. In low-N soil, the shoot-to-root ratio of Avena dropped from 2.63 +/- 0.20 in the early growth stage to 1.47 +/- 0.03 in the late growth stage, indicating that Avena plant allocated more energy to roots to optimize nutrient uptake (i.e. N) when soil N was limiting. In high-N soil, the shoot-to-root ratio of Medicago increased significantly over time (from 2.45 +/- 0.30 to 5.43 +/- 0.10), suggesting that Medicago plants allocated more energy to shoots to optimize photosynthesis when N was not limiting. The shoot-to-root ratios were not significantly different between two CO2 levels.

  20. The Impact of Free Air CO2 Enrichment (FACE) on Protein and Amino Acids Concentration of Conventional Japonica Rice%开放式空气中CO2浓度增高(FACE)对常规粳稻蛋白质和氨基酸含量的影响

    Institute of Scientific and Technical Information of China (English)

    周晓冬; 赖上坤; 周娟; 王云霞; 董桂春; 朱建国; 杨连新; 王余龙

    2012-01-01

    Rice( Oryza saliva L.) is one of the most important crops in the world and the first staple food in Asia, providing nutrition to a large proportion of the world's population. Rising atmospheric carbon dioxide concentration([CO2]) has numerious impacts on rice production. Compared with growth and grain yield, our understanding in the response of grain quality to elevatedfCO2] is very limited. A field experiment was carried out using the FACE(Free Air CO2 Enrichment) system to evaluate the effects of elevated CO2 concentration on nutrient quality of three conventional japonica varieties, Wuyunjing 21, Yangfujing 18 and Wujing 15 in 2009. Plants were grown at ambient or elevated(200 μmol·mol‐1 higher than ambient) CO2 concentrations. At maturity, the grains were harvested for protein and amino acids analysis. Elevated [C02] decreased protein concentration in milled rice of all tested varieties by 5.6% on average. The contents of total amino acids, essential amino acids and non-essential araino acids were declined under elevated[CO2] by 7.6%, 6.7% and 7.9%, respectively. The percentage of essential amino acids increased and that of the non-essential amino acids declined significantly, but relative concentrations of essential and non-essential amino acids did not show significant changes in response to elevated[CO2]. Concentrations of seven essential amino acids and eight non-essential amino acids were significantly decreased by elevated[CO2]. In general, the responses of Wuyunjing 21 to elevated[CO2] were significantly greater than that of Yangfujing 8 and Wujing 15. The above results suggested that the lower concentrations of rice protein and amino acids would be expected under the atmospheric environment in the middle of this century.%为了明确未来大气CO2浓度升高对水稻蛋白质营养品质的影响,2009年利用稻田开放式空气CO2浓度增高(FACE,FreeAir CO2 Enrichment)系统,以武运粳21、扬辐粳8号和武粳15为供试品种,研究大田生长期CO

  1. High-accuracy C-14 measurements for atmospheric CO2 samples by AMS

    NARCIS (Netherlands)

    Meijer, H.A.J.; Pertuisot, M.H.; van der Plicht, J.

    2006-01-01

    In this paper, we investigate how to achieve high-accuracy radiocarbon measurements by accelerator mass spectrometry (ANIS) and present measurement series (performed on archived CO2) of (CO2)-C-14 between 1985 and 1991 for Point Barrow (Alaska) and the South Pole. We report in detail the measurement

  2. Coupling between atmospheric CO2 and temperature during the onset of the Little Ice Age

    NARCIS (Netherlands)

    Hoof, T.B. van

    2004-01-01

    Present day global warming is primarily caused by the greenhouse effect of the increased CO2 emissions since the onset of the industrial revolution. A coupling between temperature and the greenhouse gas CO2 has also been observed in several ice-core records on a glacial-interglacial timescale as we

  3. An isotopomer strategy to detect plant acclimation to increasing atmospheric CO2

    Science.gov (United States)

    Augusti, A.; Betson, T. R.; Schleucher, J.

    2009-04-01

    , but individual D isotopomer abundances are ultimately set by enzyme isotope effects. In tree-ring cellulose, abundance differences between exchanging and non-exchanging isotopomers reflect evaporative enrichment and may be exploited to reconstruct humidity. Finally, we have shown that abundance ratios of non-exchanging D isotopomers are wholly determined by biochemical isotope fractionations, independent of source water. Consequently, isotopomer ratios represent signals of leaf-level metabolic regulation, which are deposited in tree rings. For example, one isotopomer ratio responds to the CO2 concentration during photosynthesis. This effect reflects CO2-induced changes of the metabolic flux ratio of photosynthesis versus photorespiration. Photorespiration reduces the efficiency of photosynthesis, therefore this isotopomer ratio may reveal plant acclimation on time scales of decades, and associated trends in plant productivity. Combining signals reflecting metabolic regulation with climate signals opens the possibility to study acclimation of plants to increasing atmospheric CO2 and concomitant climatic changes, on time scales of decades and centuries.

  4. ASSIMILATION, RESPIRATION AND ALLOCATION OF CARBON IN PLANTAGO MAJOR AS AFFECTED BY ATMOSPHERIC CO2 LEVELS - A CASE-STUDY

    NARCIS (Netherlands)

    DENHERTOG, J; STULEN, [No Value; LAMBERS, H

    1993-01-01

    The response of Plantago major ssp. pleiosperma plants, grown on nutrient solution in a climate chamber, to a doubling of the ambient atmospheric CO2 concentration was investigated. Total dry matter production was increased by 30 % after 3 weeks of exposure, due to a transient stimulation of the rel

  5. ‘Fuji’ apple (Malus domestica Borkh) volatile production during high pCO2 controlled atmosphere storage

    Science.gov (United States)

    ‘Fuji’apple [Malus sylvestris var. domestica (Borkh.) Mansf.] volatile compound dynamics were characterized during cold storage in air or at low pO2 controlled atmosphere (CA) with up to 5 kPa CO2. Volatile compounds in storage chambers were adsorbed onto solid sorbent traps and analyzed by GC-MS....

  6. Biological and physical controls in the Southern Ocean on past millennial-scale atmospheric CO2 changes

    Science.gov (United States)

    Gottschalk, Julia; Skinner, Luke C.; Lippold, Jörg; Vogel, Hendrik; Frank, Norbert; Jaccard, Samuel L.; Waelbroeck, Claire

    2016-05-01

    Millennial-scale climate changes during the last glacial period and deglaciation were accompanied by rapid changes in atmospheric CO2 that remain unexplained. While the role of the Southern Ocean as a 'control valve' on ocean-atmosphere CO2 exchange has been emphasized, the exact nature of this role, in particular the relative contributions of physical (for example, ocean dynamics and air-sea gas exchange) versus biological processes (for example, export productivity), remains poorly constrained. Here we combine reconstructions of bottom-water [O2], export production and 14C ventilation ages in the sub-Antarctic Atlantic, and show that atmospheric CO2 pulses during the last glacial- and deglacial periods were consistently accompanied by decreases in the biological export of carbon and increases in deep-ocean ventilation via southern-sourced water masses. These findings demonstrate how the Southern Ocean's 'organic carbon pump' has exerted a tight control on atmospheric CO2, and thus global climate, specifically via a synergy of both physical and biological processes.

  7. Change is in the air: impacts of the historical and predicted increase in atmospheric CO2 on pasture and prairie

    Science.gov (United States)

    The concentration of carbon dioxide (CO2) gas in the atmosphere has increased by almost 40% since the beginning of the Industrial Revolution and is predicted to reach double the pre-Industrial concentration within 50 years. By stimulating leaf photosynthesis and reducing stomatal conductance to wat...

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

    NARCIS (Netherlands)

    Yin, X.

    2013-01-01

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

  9. Effects of rising atmospheric CO2 on evapotranspiration and soil moisture: A practical approach for the Netherlands

    NARCIS (Netherlands)

    Kruijt, B.; Witte, J.P.M.; Jacobs, C.M.J.; Kroon, T.

    2008-01-01

    The extent to which climate change will affect evapotranspiration and water deficits is still uncertain. Temperature increase was recently shown to lead to enhanced drought in the Netherlands. In contrast, experimental evidence shows that elevated atmospheric CO2 concentrations tend to reduce stomat

  10. The use of forest stand age information in an atmospheric CO2 inversion applied to North America

    NARCIS (Netherlands)

    Deng, F.; Chen, J.M.; Pan, Y.; Peters, W.; Birdsey, R.; McCullough, K.; Xiao, J.

    2013-01-01

    Atmospheric inversions have become an important tool in quantifying carbon dioxide (CO2) sinks and sources at a variety of spatiotemporal scales, but associated large uncertainties restrain the inversion research community from reaching agreement on many important subjects. We enhanced an atmospheri

  11. A proposed potential role for increasing atmospheric CO2 as a promoter of weight gain and obesity

    DEFF Research Database (Denmark)

    Hersoug, Lars-Georg; Sjödin, Anders Mikael; Astrup, A

    2012-01-01

    , which in turn spills over to cerebrospinal fluids. Nerve cells in the hypothalamus that regulate appetite and wakefulness have been shown to be extremely sensitive to pH, doubling their activity if pH decreases by 0.1 units. We hypothesize that an increased acidic load from atmospheric CO2 may...

  12. The global pyrogenic carbon cycle and its impact on the level of atmospheric CO2 over past and future centuries.

    Science.gov (United States)

    Landry, Jean-Sébastien; Matthews, H Damon

    2016-12-19

    The incomplete combustion of vegetation and dead organic matter by landscape fires creates recalcitrant pyrogenic carbon (PyC), which could be consequential for the global carbon budget if changes in fire regime, climate, and atmospheric CO2 were to substantially affect gains and losses of PyC on land and in oceans. Here, we included global PyC cycling in a coupled climate-carbon model to assess the role of PyC in historical and future simulations, accounting for uncertainties through five sets of parameter estimates. We obtained year-2000 global stocks of (Central estimate, likely uncertainty range in parentheses) 86 (11-154), 47 (2-64), and 1129 (90-5892) Pg C for terrestrial residual PyC (RPyC), marine dissolved PyC, and marine particulate PyC, respectively. PyC cycling decreased atmospheric CO2 only slightly between 1751 and 2000 (by 0.8 Pg C for the Central estimate) as PyC-related fluxes changed little over the period. For 2000 to 2300, we combined Representative Concentration Pathways (RCPs) 4.5 and 8.5 with stable or continuously increasing future fire frequencies. For the increasing future fire regime, the production of new RPyC generally outpaced the warming-induced accelerated loss of existing RPyC, so that PyC cycling decreased atmospheric CO2 between 2000 and 2300 for most estimates (by 4-8 Pg C for Central). For the stable fire regime, however, PyC cycling usually increased atmospheric CO2 (by 1-9 Pg C for Central), and only the most extreme choice of parameters maximizing PyC production and minimizing PyC decomposition led to atmospheric CO2 decreases under RCPs 4.5 and 8.5 (by 5-8 Pg C). Our results suggest that PyC cycling will likely reduce the future increase in atmospheric CO2 if landscape fires become much more frequent; however, in the absence of a substantial increase in fire frequency, PyC cycling might contribute to, rather than mitigate, the future increase in atmospheric CO2 .

  13. Biomass fast pyrolysis in a fluidized bed reactor under N2, CO2, CO, CH4 and H2 atmospheres.

    Science.gov (United States)

    Zhang, Huiyan; Xiao, Rui; Wang, Denghui; He, Guangying; Shao, Shanshan; Zhang, Jubing; Zhong, Zhaoping

    2011-03-01

    Biomass fast pyrolysis is one of the most promising technologies for biomass utilization. In order to increase its economic potential, pyrolysis gas is usually recycled to serve as carrier gas. In this study, biomass fast pyrolysis was carried out in a fluidized bed reactor using various main pyrolysis gas components, namely N(2), CO(2), CO, CH(4) and H(2), as carrier gases. The atmosphere effects on product yields and oil fraction compositions were investigated. Results show that CO atmosphere gave the lowest liquid yield (49.6%) compared to highest 58.7% obtained with CH(4). CO and H(2) atmospheres converted more oxygen into CO(2) and H(2)O, respectively. GC/MS analysis of the liquid products shows that CO and CO(2) atmospheres produced less methoxy-containing compounds and more monofunctional phenols. The higher heating value of the obtained bio-oil under N(2) atmosphere is only 17.8 MJ/kg, while that under CO and H(2) atmospheres increased to 23.7 and 24.4 MJ/kg, respectively.

  14. Atmospheric CO2 from the late Oligocene to early Miocene reconstructed from photosynthesis data and leaf characteristics of fossil plants

    Science.gov (United States)

    Grein, Michaela; Oehm, Christoph; Konrad, Wilfried; Utescher, Torsten; Kunzmann, Lutz; Roth-Nebelsick, Anita

    2013-04-01

    In the Cenozoic era, global climate changed from greenhouse to icehouse conditions. During the Oligocene, the comparatively cool phase in the earlier part of the late Oligocene is followed by the Late Oligocene Warming and a major glaciation event at the Oligocene-Miocene transition (Mi-1). Various studies indicate that these climate events were coupled to changes in atmospheric CO2 levels. In this study, atmospheric CO2 from the late Oligocene to the early Miocene was reconstructed by using photosynthesis data and fossil leaf characteristics. We used plant material from various sites located in Germany and Austria comprising fossil leaves of four angiosperm plant species: Platanus neptuni (Platanaceae), Quercus rhenana, Q. praerhenana and Eotrigonobalanus furcinervis (all Fagaceae). A mechanistic-theoretical approach based on stomatal parameters, photosynthesis data and gas exchange parameters was applied to model palaeoatmospheric CO2 levels. Detailed climate data of the considered sites were reconstructed as well since the mechanistic-theoretical approach requires climate data as input parameters for calculating both assimilation rate and transpiration rate. Our results indicate a steady CO2 level of about 400 ppm for all sites and therefore suggest a decoupling of CO2 and cooling/warming events for the considered time slices.

  15. Role of Carbonic Anhydrase as an Activator in Carbonate Rock Dissolution and Its Implication for Atmospheric CO2 Sink

    Institute of Scientific and Technical Information of China (English)

    刘再华

    2001-01-01

    The conversion of CO2 into H+ and is a relatively slow reaction. Hence, its kinetics may be rate determining in carbonate rock dissolution. Carbonic anhydrase (CA), which is widespread in nature, was used to catalyze the CO2 conversion process in dissolution experiments of limestone and dolomite. It was found that the rate of dissolution increases by a factor of about 10 after the addition of CA at a high CO2 partial pressure (Pco2) for limestone and about 3 at low Pco2 for dolomite. This shows that reappraisal is necessary for the importance of chemical weathering (including carbonate rock dissolution and silicate weathering) in the atmospheric CO2 sink and the mysterious missing sink in carbon cycling. It is doubtless that previous studies of weathering underestimated weathering rates due to the ignorance of CA as an activator in weathering, thus the contribution of weathering to the atmospheric CO2 sink is also underestimated. This finding also shows the need to examine the situ distribution and activity of CA in different waters and to investigate the role of CA in weathering.``

  16. Diurnal and seasonal variations in stomatal conductance of rice at elevated atmospheric CO(2) under fully open-air conditions.

    Science.gov (United States)

    Shimono, Hiroyuki; Okada, Masumi; Inoue, Meguru; Nakamura, Hirofumi; Kobayashi, Kazuhiko; Hasegawa, Toshihiro

    2010-03-01

    Understanding of leaf stomatal responses to the atmospheric CO(2) concentration, [CO(2)], is essential for accurate prediction of plant water use under future climates. However, limited information is available for the diurnal and seasonal changes in stomatal conductance (g(s)) under elevated [CO(2)]. We examined the factors responsible for variations in g(s) under elevated [CO(2)] with three rice cultivars grown in an open-field environment under flooded conditions during two growing seasons (a total of 2140 individual measurements). Conductance of all cultivars was generally higher in the morning and around noon than in the afternoon, and elevated [CO(2)] decreased g(s) by up to 64% over the 2 years (significantly on 26 out of 38 measurement days), with a mean g(s) decrease of 23%. We plotted the g(s) variations against three parameters from the Ball-Berry model and two revised versions of the model, and all parameters explained the g(s) variations well at each [CO(2)] in the morning and around noon (R(2) > 0.68), but could not explain these variations in the afternoon (R(2) rice production.

  17. Photodissociation in the atmosphere of Mars - Impact of high resolution, temperature-dependent CO2 cross-section measurements

    Science.gov (United States)

    Anbar, A. D.; Allen, M.; Nair, H. A.

    1993-01-01

    We have investigated the impact of high resolution, temperature-dependent CO2 cross-section measurements, reported by Lewis and Carver (1983), on calculations of photodissociation rate coefficients in the Martian atmosphere. We find that the adoption of 50 A intervals for the purpose of computational efficiency results in errors in the calculated values for photodissociation of CO2, H2O, and O2 which are generally not above 10 percent, but as large as 20 percent in some instances. These are acceptably small errors, especially considering the uncertainties introduced by the large temperature dependence of the CO2 cross section. The inclusion of temperature-dependent CO2 cross sections is shown to lead to a decrease in the diurnally averaged rate of CO2 photodissociation as large as 33 percent at some altitudes, and increases of as much as 950 percent and 80 percent in the photodissociation rate coefficients of H2O and O2, respectively. The actual magnitude of the changes depends on the assumptions used to model the CO2 absorption spectrum at temperatures lower than the available measurements, and at wavelengths longward of 1970 A.

  18. Remotely operable compact instruments for measuring atmospheric CO2 and CH4 column densities at surface monitoring sites

    Directory of Open Access Journals (Sweden)

    Y. Matsumi

    2010-04-01

    Full Text Available Remotely operable compact instruments for measuring atmospheric CO2 and CH4 column densities were developed in two independent systems: one utilizing a grating-based desktop optical spectrum analyzer (OSA with a resolution enough to resolve rotational lines of CO2 and CH4 in the region of 1565–1585 and 1674–1682 nm, respectively; the other is an application of an optical fiber Fabry-Perot interferometer (FFPI to the CO2 column density. Direct sunlight was collimated via a small telescope installed on a portable sun tracker and then transmitted through an optical fiber into the OSA or the FFPI for optical analysis. The near infrared spectra of the OSA were retrieved by a least squares spectral fitting algorithm. The CO2 and CH4 column densities deduced were in excellent agreement with those measured by a Fourier transform spectrometer with high resolution. The rovibronic lines in the wavelength region of 1570–1575 nm were analyzed by the FFPI. The I0 and I values in the Beer-Lambert law equation to obtain CO2 column density were deduced by modulating temperature of the FFPI, which offered column CO2 with the statistical error less than 0.2% for six hours measurement.

  19. Remotely operable compact instruments for measuring atmospheric CO2 and CH4 column densities at surface monitoring sites

    Directory of Open Access Journals (Sweden)

    I. Morino

    2010-08-01

    Full Text Available Remotely operable compact instruments for measuring atmospheric CO2 and CH4 column densities were developed in two independent systems: one utilizing a grating-based desktop optical spectrum analyzer (OSA with a resolution enough to resolve rotational lines of CO2 and CH4 in the regions of 1565–1585 and 1674–1682 nm, respectively; the other is an application of an optical fiber Fabry-Perot interferometer (FFPI to obtain the CO2 column density. Direct sunlight was collimated via a small telescope installed on a portable sun tracker and then transmitted through an optical fiber into the OSA or the FFPI for optical analysis. The near infrared spectra of the OSA were retrieved by a least squares spectral fitting algorithm. The CO2 and CH4 column densities deduced were in excellent agreement with those measured by a Fourier transform spectrometer with high resolution. The rovibronic lines in the wavelength region of 1570–1575 nm were analyzed by the FFPI. The I0 and I values in the Beer-Lambert law equation to obtain CO2 column density were deduced by modulating temperature of the FFPI, which offered column CO2 with the statistical error less than 0.2% for six hours measurement.

  20. Quantifying the Observability of CO2 Flux Uncertainty in Atmospheric CO2 Records Using Products from Nasa's Carbon Monitoring Flux Pilot Project

    Science.gov (United States)

    Ott, Lesley; Pawson, Steven; Collatz, Jim; Watson, Gregg; Menemenlis, Dimitris; Brix, Holger; Rousseaux, Cecile; Bowman, Kevin; Bowman, Kevin; Liu, Junjie; Eldering, Annmarie; Gunson, Michael; Kawa, Stephan R.

    2014-01-01

    NASAs Carbon Monitoring System (CMS) Flux Pilot Project (FPP) was designed to better understand contemporary carbon fluxes by bringing together state-of-the art models with remote sensing datasets. Here we report on simulations using NASAs Goddard Earth Observing System Model, version 5 (GEOS-5) which was used to evaluate the consistency of two different sets of observationally constrained land and ocean fluxes with atmospheric CO2 records. Despite the strong data constraint, the average difference in annual terrestrial biosphere flux between the two land (NASA Ames CASA and CASA-GFED) models is 1.7 Pg C for 2009-2010. Ocean models (NOBM and ECCO2-Darwin) differ by 35 in their global estimates of carbon flux with particularly strong disagreement in high latitudes. Based upon combinations of terrestrial and ocean fluxes, GEOS-5 reasonably simulated the seasonal cycle observed at northern hemisphere surface sites and by the Greenhouse gases Observing SATellite (GOSAT) while the model struggled to simulate the seasonal cycle at southern hemisphere surface locations. Though GEOS-5 was able to reasonably reproduce the patterns of XCO2 observed by GOSAT, it struggled to reproduce these aspects of AIRS observations. Despite large differences between land and ocean flux estimates, resulting differences in atmospheric mixing ratio were small, typically less than 5 ppmv at the surface and 3 ppmv in the XCO2 column. A statistical analysis based on the variability of observations shows that flux differences of these magnitudes are difficult to distinguish from natural variability, regardless of measurement platform.

  1. Response of seedlings growth of Pinus sylvestriformis to atmospheric CO2 enrichment in Changbai Mountain

    Institute of Scientific and Technical Information of China (English)

    Han S hijie; Wang Chen rui; Zhang Junhui; Zou Chunjing; Zhou Yumei; Wang Xiaochun

    1999-01-01

    The biomass and ratio of root-shoot of Pinus sylvestriformis seedlings at CO2 concentration of 700 μL· L-1 and 500 μL· L-1 were measured using open-top chambers (OTCs) in Changbai Mountain during Jun.to Oct. in 1999. The results showed that doubling CO2 concentration was benefit to seedling growth of the species (500 μL· L-1 was better than 700 μL-L-1 ) and the biomass production was increased in both aboveground and underground parts of seedlings. Carbon transformation to roots was evident as rising of CO2 concentration.

  2. Gravity waves and high-altitude CO$_2$ ice cloud formation in the Martian atmosphere

    CERN Document Server

    Yiğit, Erdal; Hartogh, Paul

    2015-01-01

    We present the first general circulation model simulations that quantify and reproduce patches of extremely cold air required for CO$_2$ condensation and cloud formation in the Martian mesosphere. They are created by subgrid-scale gravity waves (GWs) accounted for in the model with the interactively implemented spectral parameterization. Distributions of GW-induced temperature fluctuations and occurrences of supersaturation conditions are in a good agreement with observations of high-altitude CO$_2$ ice clouds. Our study confirms the key role of GWs in facilitating CO$_2$ cloud formation, discusses their tidal modulation, and predicts clouds at altitudes higher than have been observed to date.

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

    Directory of Open Access Journals (Sweden)

    Y.-S. Lee

    2012-06-01

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

  4. Effects of simulated spring thaw of permafrost from mineral cryosol on CO2 emissions and atmospheric CH4 uptake

    Science.gov (United States)

    Stackhouse, Brandon T.; Vishnivetskaya, Tatiana A.; Layton, Alice; Chauhan, Archana; Pfiffner, Susan; Mykytczuk, Nadia C.; Sanders, Rebecca; Whyte, Lyle G.; Hedin, Lars; Saad, Nabil; Myneni, Satish; Onstott, Tullis C.

    2015-09-01

    Previous studies investigating organic-rich tundra have reported that increasing biodegradation of Arctic tundra soil organic carbon (SOC) under warming climate regimes will cause increasing CO2 and CH4 emissions. Organic-poor, mineral cryosols, which comprise 87% of Arctic tundra, are not as well characterized. This study examined biogeochemical processes of 1 m long intact mineral cryosol cores (1-6% SOC) collected in the Canadian high Arctic. Vertical profiles of gaseous and aqueous chemistry and microbial composition were related to surface CO2 and CH4 fluxes during a simulated spring/summer thaw under light versus dark and in situ versus water saturated treatments. CO2 fluxes attained 0.8 ± 0.4 mmol CO2 m-2 h-1 for in situ treatments, of which 85 ± 11% was produced by aerobic SOC oxidation, consistent with field observations and metagenomic analyses indicating aerobic heterotrophs were the dominant phylotypes. The Q10 values of CO2 emissions ranged from 2 to 4 over the course of thawing. CH4 degassing occurred during initial thaw; however, all cores were CH4 sinks at atmospheric concentration CH4. Atmospheric CH4 uptake rates ranged from -126 ± 77 to -207 ± 7 nmol CH4 m-2 h-1 with CH4 consumed between 0 and 35 cm depth. Metagenomic and gas chemistry analyses revealed that high-affinity Type II methanotrophic sequence abundance and activity were highest between 0 and 35 cm depth. Microbial sulfate reduction dominated the anaerobic processes, outcompeting methanogenesis for H2 and acetate. Fluxes, microbial community composition, and biogeochemical rates indicate that mineral cryosols of Axel Heiberg Island act as net CO2 sources and atmospheric CH4 sinks during summertime thaw under both in situ and water saturated states.

  5. Increasing synoptic scale variability in atmospheric CO2 at Hateruma Island associated with increasing East-Asian emissions

    Directory of Open Access Journals (Sweden)

    S. Hashimoto

    2010-01-01

    Full Text Available In-situ observations of atmospheric CO2 and CH4 at Hateruma Island (24.05° N, 123.80° E, 47 m a.s.l, Japan shows large synoptic scale variations during a 6-month period from November to April, when the sampled air is predominantly of continental origin due to the Asian winter monsoon. Synoptic scale variations are extracted from the daily averaged values for the years between 1996 and 2007, along with the annual standard deviations (σCO2 and σCH4 for CO2 and CH4, respectively for the relevant 6-month period. During this 6-month period the absolute mixing ratios of CO2 and CH4 at Hateruma are also elevated compared to those at two sites in the central North Pacific Ocean. The temporal change in σCO2 shows a systematic increase over the 12-year period, with elevated excursions in 1998 and 2003; there is no clear increase in σCH4. We also find that the σCO2/σCH4 ratio increases gradually from 1996 to 2002 and rapidly after 2002 without any extreme deviations that characterised σCO2. The σCO2/σCH4 ratio correlates closely with the recent rapid increase in fossil carbon emissions from China, as indicated in the Carbon Dioxide Information Analysis Center (CDIAC database. This methodology can be applied to multiple chemical tracers of sufficient lifetime, for tracking overall changes in regional emissions.

  6. Changes in vegetation phenology are not reflected in atmospheric CO2 and (13) C/(12) C seasonality.

    Science.gov (United States)

    Gonsamo, Alemu; D'Odorico, Petra; Chen, Jing M; Wu, Chaoyang; Buchmann, Nina

    2017-01-31

    Northern terrestrial ecosystems have shown global warming-induced advances in start, delays in end, and thus increased lengths of growing season and gross photosynthesis in recent decades. The tradeoffs between seasonal dynamics of two opposing fluxes, CO2 uptake through photosynthesis and release through respiration, determine the influence of the terrestrial ecosystem on the atmospheric CO2 and (13) C/(12) C seasonality. Here, we use four CO2 observation stations in the Northern Hemisphere, namely Alert, La Jolla, Point Barrow, and Mauna Loa Observatory, to determine how changes in vegetation productivity and phenology, respiration, and air temperature affect both the atmospheric CO2 and (13) C/(12) C seasonality. Since the 1960s, the only significant long-term trend of CO2 and (13) C/(12) C seasonality was observed at the northern most station, Alert, where the spring CO2 drawdown dates advanced by 0.65 ± 0.55 days yr(-1) , contributing to a nonsignificant increase in length of the CO2 uptake period (0.74 ± 0.67 days yr(-1) ). For Point Barrow station, vegetation phenology changes in well-watered ecosystems such as the Canadian and western Siberian wetlands contributed the most to (13) C/(12) C seasonality while the CO2 seasonality was primarily linked to nontree vegetation. Our results indicate significant increase in the Northern Hemisphere soil respiration. This means, increased respiration of (13) C depleted plant materials cancels out the (12) C gain from enhanced vegetation activities during the start and end of growing season. These findings suggest therefore that parallel warming-induced increases both in photosynthesis and respiration contribute to the long-term stability of CO2 and (13) C/(12) C seasonality under changing climate and vegetation activity. The summer photosynthesis and the soil respiration in the dormant seasons have become more vigorous which lead to increased peak-to-through CO2 amplitude. As the relative magnitude of the

  7. Atmospheric 14 C CO 2 variations in Japan during 1982--1999 based on 14 C measurements of rice grains.

    Science.gov (United States)

    Shibata, Setsuko; Kawano, Eiko; Nakabayashi, Takeshige

    2005-08-01

    (14)C in rice grains is a useful tracer of atmospheric (14)C(CO(2)). (14)C measurement in rice grains for 17 years during 1982--1999 reveals the following. There is negative correlation between Delta(14)C and the population densities of localities in Japan. Under-populated areas in the northern area of Japan and Okinawa remained clean in the 1990s. The (14)C(CO(2)) decline rates at those areas are near to that of Shauinsland. A latitudinal effect due to Chinese nuclear tests is observed in 1982. Small Seuss effects is observed at the middle latitudes in East Asia after 1995.

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

    Science.gov (United States)

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

    2014-12-01

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

  9. Evaluating the Capacity of Global CO2 Flux and Atmospheric Transport Models to Incorporate New Satellite Observations

    Science.gov (United States)

    Kawa, S. R.; Collatz, G. J.; Erickson, D. J.; Denning, A. S.; Wofsy, S. C.; Andrews, A. E.

    2007-01-01

    As we enter the new era of satellite remote sensing for CO2 and other carbon cyclerelated quantities, advanced modeling and analysis capabilities are required to fully capitalize on the new observations. Model estimates of CO2 surface flux and atmospheric transport are required for initial constraints on inverse analyses, to connect atmospheric observations to the location of surface sources and sinks, and ultimately for future projections of carbon-climate interactions. For application to current, planned, and future remotely sensed CO2 data, it is desirable that these models are accurate and unbiased at time scales from less than daily to multi-annual and at spatial scales from several kilometers or finer to global. Here we focus on simulated CO2 fluxes from terrestrial vegetation and atmospheric transport mutually constrained by analyzed meteorological fields from the Goddard Modeling and Assimilation Office for the period 1998 through 2006. Use of assimilated meteorological data enables direct model comparison to observations across a wide range of scales of variability. The biospheric fluxes are produced by the CASA model at lxi degrees on a monthly mean basis, modulated hourly with analyzed temperature and sunlight. Both physiological and biomass burning fluxes are derived using satellite observations of vegetation, burned area (as in GFED-2), and analyzed meteorology. For the purposes of comparison to CO2 data, fossil fuel and ocean fluxes are also included in the transport simulations. In this presentation we evaluate the model's ability to simulate CO2 flux and mixing ratio variability in comparison to in situ observations at sites in Northern mid latitudes and the continental tropics. The influence of key process representations is inferred. We find that the model can resolve much of the hourly to synoptic variability in the observations, although there are limits imposed by vertical resolution of boundary layer processes. The seasonal cycle and its

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

    Science.gov (United States)

    Vieira, Veronica

    1997-01-01

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

  11. CO2 capture from the atmosphere and simultaneous concentration using zeolites and amine-grafted SBA-15.

    Science.gov (United States)

    Stuckert, Nicholas R; Yang, Ralph T

    2011-12-01

    CO(2) capture from the atmosphere and concentration by cyclic adsorption-desorption processes are studied for the first time. New high microporosity materials, zeolite types Li-LSX and K-LSX, are compared to zeolite NaX and amine-grafted SBA-15 with low amine content. Breakthrough performance showed low silica type X (LSX) to have the most promise for application in dry conditions and capable of high space velocities of at least 63,000 h(-1), with minimal spreading of the CO(2) breakthrough curve. Amine-grafted silica was the only adsorbent able to operate in wet conditions, but at a lower space velocity of 1500 h(-1), due to slower uptake rates. The results illustrate that the uptake rate is as important as the equilibrium adsorbed amount in determining the cyclic process performance. Li-LSX was found to have double the capacity of zeolite NaX at atmospheric conditions, also higher than all other reported zeolites. It is further demonstrated that by using a combined temperature and vacuum swing cycle, the CO(2) concentration in the desorption product is >90% for all adsorbents in pellet form. This is the first report of such high CO(2) product concentrations from a single cycle, using atmospheric air.

  12. The first 1-year-long estimate of the Paris region fossil fuel CO2 emissions based on atmospheric inversion

    Science.gov (United States)

    Staufer, Johannes; Broquet, Grégoire; Bréon, François-Marie; Puygrenier, Vincent; Chevallier, Frédéric; Xueref-Rémy, Irène; Dieudonné, Elsa; Lopez, Morgan; Schmidt, Martina; Ramonet, Michel; Perrussel, Olivier; Lac, Christine; Wu, Lin; Ciais, Philippe

    2016-11-01

    The ability of a Bayesian atmospheric inversion to quantify the Paris region's fossil fuel CO2 emissions on a monthly basis, based on a network of three surface stations operated for 1 year as part of the CO2-MEGAPARIS experiment (August 2010-July 2011), is analysed. Differences in hourly CO2 atmospheric mole fractions between the near-ground monitoring sites (CO2 gradients), located at the north-eastern and south-western edges of the urban area, are used to estimate the 6 h mean fossil fuel CO2 emission. The inversion relies on the CHIMERE transport model run at 2 km × 2 km horizontal resolution, on the spatial distribution of fossil fuel CO2 emissions in 2008 from a local inventory established at 1 km × 1 km horizontal resolution by the AIRPARIF air quality agency, and on the spatial distribution of the biogenic CO2 fluxes from the C-TESSEL land surface model. It corrects a prior estimate of the 6 h mean budgets of the fossil fuel CO2 emissions given by the AIRPARIF 2008 inventory. We found that a stringent selection of CO2 gradients is necessary for reliable inversion results, due to large modelling uncertainties. In particular, the most robust data selection analysed in this study uses only mid-afternoon gradients if wind speeds are larger than 3 m s-1 and if the modelled wind at the upwind site is within ±15° of the transect between downwind and upwind sites. This stringent data selection removes 92 % of the hourly observations. Even though this leaves few remaining data to constrain the emissions, the inversion system diagnoses that their assimilation significantly reduces the uncertainty in monthly emissions: by 9 % in November 2010 to 50 % in October 2010. The inverted monthly mean emissions correlate well with independent monthly mean air temperature. Furthermore, the inverted annual mean emission is consistent with the independent revision of the AIRPARIF inventory for the year 2010, which better corresponds to the measurement period than the 2008

  13. Global modelling of the early Martian climate under a denser CO2 atmosphere: Water cycle and ice evolution

    CERN Document Server

    Wordsworth, R; Millour, E; Head, J; Madeleine, J -B; Charnay, B

    2012-01-01

    We discuss 3D global simulations of the early Martian climate that we have performed assuming a faint young Sun and denser CO2 atmosphere. We include a self-consistent representation of the water cycle, with atmosphere-surface interactions, atmospheric transport, and the radiative effects of CO2 and H2O gas and clouds taken into account. We find that for atmospheric pressures greater than a fraction of a bar, the adiabatic cooling effect causes temperatures in the southern highland valley network regions to fall significantly below the global average. Long-term climate evolution simulations indicate that in these circumstances, water ice is transported to the highlands from low-lying regions for a wide range of orbital obliquities, regardless of the extent of the Tharsis bulge. In addition, an extended water ice cap forms on the southern pole, approximately corresponding to the location of the Noachian/Hesperian era Dorsa Argentea Formation. Even for a multiple-bar CO2 atmosphere, conditions are too cold to a...

  14. The impact of temperature dependent CO2 cross section measurements: A role for heterogeneous chemistry in the atmosphere of Mars?

    Science.gov (United States)

    Anbar, A. D.; Allen, M.; Nair, H.; Leu, M-T.; Yung, Y. L.

    1992-01-01

    Carbon dioxide comprises over 95 percent of the Mars atmosphere, despite continuous photolysis of CO2 by solar ultraviolet (UV) radiation. Since the direct recombination of CO and O is spinforbidden, the chemical stability of CO2 in the Martian atmosphere is thought to be the result of a HO(x)-catalyzed recombination scheme. Thus the rate of CO oxidation is sensitive to the abundance and altitude distribution of OH, H, and HO2. Most Martian atmospheric models assume that HO(x) abundances are governed purely by gas phase chemistry. However, it is well established that reactive HO(x) radical are adsorbed by a wide variety of surfaces. The authors have combined laboratory studies of H, OH, and HO2 adsorption on inorganic surfaces, observational data of aerosol distributions, and an updated photochemical model to demonstrate that adsorption on either dust or ice aerosols is capable of reducing HO(x) abundances significantly, thereby retarding the rate of CO oxidation.

  15. TransCom model simulations of hourly atmospheric CO2: Analysis of synoptic-scale variations for the period 2002-2003

    NARCIS (Netherlands)

    Patra, P. K.; Law, R. M.; Peters, W.; RöDenbeck, C.; Takigawa, M.; Aulagnier, C.; Baker, I.; Bergmann, D. J.; Bousquet, P.; Brandt, J.; Bruhwiler, L.; Cameron-Smith, P. J.; Christensen, J. H.; Delage, F.; Denning, A. S.; Fan, S.; Geels, C.; Houweling, S.; Imasu, R.; Karstens, U.; Kawa, S. R.; Kleist, J.; Krol, M. C.; Lin, S.-J.; Lokupitiya, R.; Maki, T.; Maksyutov, S.; Niwa, Y.; Onishi, R.; Parazoo, N.; Pieterse, G.; Rivier, L.; Satoh, M.; Serrar, S.; Taguchi, S.; Vautard, R.; Vermeulen, A. T.; Zhu, Z.

    2008-01-01

    The ability to reliably estimate CO2 fluxes from current in situ atmospheric CO2 measurements and future satellite CO2 measurements is dependent on transport model performance at synoptic and shorter timescales. The TransCom continuous experiment was designed to evaluate the performance of forward t

  16. Elevated CO2 Atmosphere Minimizes the Effect of Drought on the Cerrado Species Chrysolaena obovata.

    Science.gov (United States)

    Oliveira, Vanessa F; Silva, Emerson A; Carvalho, Maria A M

    2016-01-01

    Chrysolaena obovata stores inulin in the rhizophores, associated with drought tolerance. While crop plants are widely studied concerning the interactive effects of high [CO2] and drought, few studies reported these effects in native species. Here, we evaluated the combined effects of these factors on water status and fructan metabolism in C. obovata, a native Cerrado species. Two lots of plants were kept at 380 and 760 ppm CO2 in open-top chambers. In each, [CO2] plants were divided into four groups and cultivated under different water availability: irrigation with 100 (control), 75 (low), 50 (medium), and 25% (severe drought) of the water evapotranspirated in the last 48 h. In each, water treatment plants were collected at 0, 9, 18, and 27 days. On day 27, all plants were re-watered to field capacity and, after 5 days, a new sampling was made. Water restriction caused a decrease in plant moisture, photosynthesis, and in enzymes of fructan metabolism. These changes were generally more pronounced in 25% plants under ambient [CO2]. In the later, increases in the proportion of hexoses and consequent modification of the fructan chain sizes were more marked than under high [CO2]. The results indicate that under elevated [CO2], the negative effects of water restriction on physiological processes were minimized, including the maintenance of rhizophore water potential, increase in water use efficiency, maintenance of photosynthesis and fructan reserves for a longer period, conditions that shall favor the conservation of this species in the predicted climate change scenarios.

  17. Ocean-atmosphere exchange of organic carbon and CO2 surrounding the Antarctic Peninsula

    Science.gov (United States)

    Ruiz-Halpern, S.; Calleja, M. Ll.; Dachs, J.; Del Vento, S.; Pastor, M.; Palmer, M.; Agustí, S.; Duarte, C. M.

    2014-05-01

    Exchangeable organic carbon (OC) dynamics and CO2 fluxes in the Antarctic Peninsula during austral summer were highly variable, but the region appeared to be a net sink for OC and nearly in balance for CO2. Surface exchangeable dissolved organic carbon (EDOC) measurements had a 43 ± 3 (standard error, hereafter SE) μmol C L-1 overall mean and represented around 66% of surface non-purgeable dissolved organic carbon (DOC) in Antarctic waters, while the mean concentration of the gaseous fraction of organic carbon (GOC H-1) was 46 ± 3 SE μmol C L-1. There was a tendency towards low fugacity of dissolved CO2 (fCO2-w) in waters with high chlorophyll a (Chl a) content and high fCO2-w in areas with high krill densities. However, such relationships were not found for EDOC. The depth profiles of EDOC were also quite variable and occasionally followed Chl a profiles. The diel cycles of EDOC showed two distinct peaks, in the middle of the day and the middle of the short austral dark period, concurrent with solar radiation maxima and krill night migration patterns. However, no evident diel pattern for GOC H-1 or CO2 was observed. The pool of exchangeable OC is an important and active compartment of the carbon budget surrounding the Antarctic Peninsula and adds to previous studies highlighting its importance in the redistribution of carbon in marine environments.

  18. Response of salt marsh and mangrove wetlands to changes in atmospheric CO2, climate, and sea-level

    Science.gov (United States)

    Mckee, Karen L.; Rogers, Kerrylee; Saintilan, Neil; Middleton, Beth A.

    2012-01-01

    Coastal salt marsh and mangrove ecosystems are particularly vulnerable to changes in atmospheric CO2 concentrations and associated climate and climate-induced changes. We provide a review of the literature detailing theoretical predictions and observed responses of coastal wetlands to a range of climate change stressors, including CO2, temperature, rainfall, and sea-level rise. This review incorporates a discussion of key processes controlling responses in different settings and thresholds of resilience derived from experimental and observational studies. We specifically consider the potential and observed effects on salt marsh and mangrove vegetation of changes in (1) elevated [CO2] on physiology, growth, and distribution; (2) temperature on distribution and diversity; (3) rainfall and salinity regimes on growth and competitive interactions; and (4) sea level on geomorphological, hydrological, and biological processes.

  19. The Berkeley Atmospheric CO2 Observation Network (BEACON): Measuring Greenhouse Gases and Criteria Pollutants within the Urban Dome

    Science.gov (United States)

    Teige, V. E.; Weichsel, K.; Hooker, A.; Wooldridge, P. J.; Cohen, R. C.

    2012-12-01

    Efforts to curb greenhouse gas emissions, while global in their impacts, often focus on local and regional scales for execution and are dependent on the actions of communities and individuals. Evaluating the effectiveness of local policies requires observations with much higher spatial resolution than are currently available---kilometer scale. The Berkeley Atmospheric CO2 Observation Network (BEACON):, launched at the end of 2011, aims to provide measurements of urban-scale concentrations of CO2, temperature, pressure, relative humidity, O3, CO, and NO2 with sufficient spatial and temporal resolution to characterize the sources of CO2 within cities. Our initial deployment in Oakland, California uses ~40 sensor packages at a roughly 2 km spacing throughout the city. We will present an initial analysis of the vertical gradients and other spatial patterns observed to date.

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

    Science.gov (United States)

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

    2011-01-01

    We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS space mission [1]. It uses two pulsed laser transmitters allowing simultaneous measurement of a CO2 absorption line in the 1575 nm band, O2 extinction in the Oxygen A-band, surface height and backscatter profile. The lasers are precisely stepped in wavelength across the CO2 line and an O2 line region during the measurement. The direct detection receiver measures the energies of the laser echoes from the surface along with the range profile of scattering in the path. The column densities for the CO2 and O2 gases are estimated from the ratio of the on- and off-line signals via the integrated path differential absorption (IPDA) technique. The time of flight of the laser pulses is used to estimate the height of the scattering surface and to reject laser photons scattered in the atmosphere. We developed an airborne lidar to demonstrate an early version of the CO2 measurement from the NASA Glenn Lear-25 aircraft. The airborne lidar stepped the pulsed laser's wavelength across the selected CO2 line with 20 wavelength steps per scan. The line scan rate is 450 Hz, the laser pulse widths are 1 usec, and laser pulse energy is 24 uJ. The time resolved laser backscatter is collected by a 20 cm telescope, detected by a NIR photomultiplier and is recorded on every other reading by a photon counting system [2]. During August 2009 we made a series of 2.5 hour long flights and measured the atmospheric CO2 absorption and line shapes using the 1572.33 nm CO2 line. Measurements were made at stepped altitudes from 3-13 km over locations in the US, including the SGP ARM site in Oklahoma, central Illinois, north-eastern North Carolina, and over the Chesapeake Bay and the eastern shore of Virginia. Although the received signal energies were weaker than expected for ASCENDS, clear CO2 line shapes were observed at all altitudes, and some measurements were made