http://precedings.nature.com/tags/carbon%20dioxide Recently posted documents tagged with 'carbon dioxide' Nature Publishing Group en Nature Precedings http://precedings.nature.com/images/header_logo.gif http://precedings.nature.com http://dx.doi.org/10.1038/npre.2009.3703.1 Atmospheric carbon dioxide (CO2) and ozone (O3) concentrations are rising, which may have opposing effects on tree C balance and allocation to fine roots. More information is needed on interactive CO2 and O3 effects on roots, particularly fine-root life span, a critical demographic parameter and determinant of soil C and N pools and cycling rates. We conducted a study in which ponderosa pine (Pinus ponderosa) seedlings were exposed to two levels of CO2 and O3 in sun-lit controlled-environment terracosms for three years. Minirhizotrons were used to monitor individual fine roots in three soil horizons every 28 days. Proportional hazards regression was used to analyze effects of CO2, O3, diameter, depth, and season of root initiation on fine-root survivorship. More fine roots were produced in the elevated CO2 treatment than in ambient CO2. Median life spans varied from 140-448 days depending on the season of root initiation. Elevated CO2, increasing root diameter, and increasing root depth all significantly increased fine-root survivorship and median life span. Life span was slightly, but not significantly, lower in elevated O3, and increased O3 did not reduce the effect of elevated CO2. These results indicate the potential for elevated CO2 to increase the number of fine roots and their residence time in the soil, which is also affected by root diameter, root depth, and phenology. http://dx.doi.org/10.1038/npre.2009.3703.1 Tue, 01 Sep 2009 09:09:59 UTC Elevated CO2 and O3 Effects on Fine-Root Life Span in Ponderosa Pine doi:10.1038/npre.2009.3703.1 2009-09-01 Donald L. Phillips Nature Precedings 2009-09-01T09:09:59Z Poster Ecology Earth & Environment Plant Biology http://creativecommons.org/licenses/by/3.0/ http://dx.doi.org/10.1038/npre.2009.3613.1 Pinus edulis (piñon pine) is found across 35% of the Colorado Plateau and is a foundation species in the piñon-juniper woodlands of the Southwest. Piñon pine mortality in the recent drought has been high and climate change models forecast a warmer future for the region, which will increase piñon pine water stress. In order to predict the fate of piñon pine, we must understand how various climatic factors influence piñon growth. Tree rings provide a climate sensitive record of growth ideal for exploring the relationship between growth and climate. We used 78 piñon pine trees cored at Red Mountain in northern Arizona in 1998 to predict tree ring width and piñon pine mortality, using variables including available moisture, growing season length, tree age, growth in prior years, and [CO2] in a hierarchical Bayes modeling structure. As a first step towards the full model, tree ring width in the prior year and [CO2] was considered in a lag 1 year autoregressive model of mean yearly ring width with [CO2] as a linear covariate.As a linear covariate, [CO2] is related to tree ring width with slope 0.019 (95% Credible Interval (CI) 0.015 to 0.024) and intercept -5.5 (95% CI -6.88 to -4.07). Tree ring width increases with [CO2] and [CO2] explains the overall increasing trend in average yearly ring width better than available moisture (as Palmer Drought Severity Index values) or growing season length (as the number of days/year with an average of 5°C or higher). The autocorrelation coefficient is 0.49 (95% CI 0.30 to 0.68), suggesting a strong effect of growth in the prior year on growth in the subsequent year. The model successfully predicts yearly average ring width, though ring width is overestimated in extremely dry years. As other factors and more data are incorporated into the model, ring width predictions should improve along with our understanding of piñon growth. We plan to consider the ramifications of various climate change scenarios for piñon pine with this model and compare the responses of trees that have survived to those that have died in the recent drought. As recent experiments indicate that piñon pine mortality can arise from drought-induced carbon starvation, the contribution of increasing [CO2] to growth could be very important to predicting piñon pine survival. http://dx.doi.org/10.1038/npre.2009.3613.1 Fri, 14 Aug 2009 19:57:45 UTC Toward a complete model of radial growth in Pinus edulis: the effects of CO2 and prior years doi:10.1038/npre.2009.3613.1 2009-08-14 Nature Precedings 2009-08-14T19:57:45Z Poster Ecology Plant Biology http://creativecommons.org/licenses/by/3.0/ http://dx.doi.org/10.1038/npre.2008.2636.1 Within the scope of producing clean fossil fuels by simultaneously tackling greenhouse gas emissions, the interfacial tension of partially miscible phases containing CO2 is being investigated with the pendant drop method. Emphasis is given to measurements at elevated pressures and temperatures, analogous to reservoir conditions. A high pressure apparatus consisting of a view cell and high pressure capillary fittings is used for creating pendent drops at the desired conditions. A computer aided Drop Shape Analysis system is used for capturing images of such drops, which are then analysed for the interfacial tension calculation of the two phases with the KRUSS DSA software. The results acquired from the initial measurements conducted for the H2O/CO2 system are presented in comparison with literature data. http://dx.doi.org/10.1038/npre.2008.2636.1 Fri, 12 Dec 2008 17:34:45 UTC Pendent Drops at Elevated P & T doi:10.1038/npre.2008.2636.1 2008-12-12 Apostolos Georgiadis Nature Precedings 2008-12-12T17:34:45Z Poster Chemistry Earth & Environment http://creativecommons.org/licenses/by/3.0/ http://dx.doi.org/10.1038/npre.2008.2649.1 Acquiring a comprehensive understanding of the behaviour of carbon dioxide under reservoir conditions is essential for optimizing its usage in enhanced oil recovery (EOR) and for developing sequestration schemes. In order to obtain this understanding, it is necessary to study the physical properties and phase behaviour of mixtures of carbon dioxide with hydrocarbons and brines under conditions of high pressure. In this work we are addressing both the experimental and the theoretical aspects of this problem. A new apparatus, based on the static-analytical method, has been developed to measure phase equilibrium. The equipment comprises a high-pressure cell with sapphire windows for visual observation and phase sampling, with on-line gas chromatography analysis, for measuring the phase compositions. The experimental work is complemented with a theoretical modelling for these mixtures, using the statistical association fluid theory for potentials of variable range (SAFT-VR). As an example of the predictive capabilities of the equation, the fluid phase behaviour of the mixture (carbon dioxide + n-decane) is presented. http://dx.doi.org/10.1038/npre.2008.2649.1 Fri, 12 Dec 2008 17:33:17 UTC Measurement & Prediction of Phase Behaviour of Carbon Dioxide Mixtures doi:10.1038/npre.2008.2649.1 2008-12-12 Esther Forte Nature Precedings 2008-12-12T17:33:17Z Poster Chemistry Earth & Environment http://creativecommons.org/licenses/by/3.0/ http://dx.doi.org/10.1038/npre.2008.1741.2 Increasing concentrations of carbon dioxide (CO2) in the atmosphere have stimulated significant global research and development efforts regarding the reduction in CO2 emissions from all point and non-point sources. In addition to technologies that do not use carbon feedstocks or which capture and “permanently” store CO2 (i.e., sequestration), there is considerable worldwide interest among the academic, industrial, and government communities regarding methods for dissociating waste stream carbon dioxide molecules into their constituent carbon and oxygen (“CO2 splitting”) atoms as a final “end-of-pipe” treatment option. The splitting of carbon dioxide has also been actively discussed and researched in the space exploration and extraterrestrial colonization programs for several decades. This document summarizes the peer-reviewed open source scientific literature regarding thermal methods for carbon dioxide splitting. http://dx.doi.org/10.1038/npre.2008.1741.2 Tue, 22 Apr 2008 11:44:02 UTC Thermal Carbon Dioxide Splitting: A Summary of the Peer-Reviewed Scientific Literature doi:10.1038/npre.2008.1741.2 2008-04-22 Sierra Rayne Nature Precedings 2008-04-22T11:44:02Z Manuscript Chemistry Earth & Environment http://creativecommons.org/licenses/by/3.0/ http://dx.doi.org/10.1038/npre.2008.1741.1 Increasing concentrations of carbon dioxide (CO2) in the atmosphere have stimulated significant global research and development efforts regarding the reduction in CO2 emissions from all point and non-point sources. In addition to technologies that do not use carbon feedstocks or which capture and “permanently” store CO2 (i.e., sequestration), there is considerable worldwide interest among the academic, industrial, and government communities regarding methods for dissociating waste stream carbon dioxide molecules into their constituent carbon and oxygen (“CO2 splitting”) atoms as a final “end-of-pipe” treatment option. The splitting of carbon dioxide has also been actively discussed and researched in the space exploration and extraterrestrial colonization programs for several decades. This document summarizes the peer-reviewed open source scientific literature regarding carbon dioxide splitting. http://dx.doi.org/10.1038/npre.2008.1741.1 Tue, 01 Apr 2008 13:15:20 UTC Carbon Dioxide Splitting: A Summary of the Peer-Reviewed Scientific Literature doi:10.1038/npre.2008.1741.1 2008-04-01 Sierra Rayne Nature Precedings 2008-04-01T13:15:20Z Manuscript Chemistry Earth & Environment http://creativecommons.org/licenses/by/3.0/ http://dx.doi.org/10.1038/npre.2008.1590.1 Carbon capture and storage (CCS) is the collection of carbon dioxide (CO2) from industrial point sources such as power plants and its injection underground. Much of the technology necessary to capture and inject CO2 into the subsurface already exists and CCS will be an integral part of any strategy to combat anthropogenic climate change until we, as a society, are able to move away from our dependence on fossil fuels. There are three options for geological storage of CO2: deep saline aquifers, depleted oil reservoirs and unmineable coal beds. It is the purpose of this presentation to provide a general survey of each of these options. For each geological formation I review (1) The ways in which CO2 could escape into the atmosphere. (2) Current scientific knowledge and uncertainties about the behaviour of CO2 after it is underground -particularly the interactions of water, oil or gas initially present in the geological formation with injected CO2. (3) The overall advantages and disadvantages of each option in terms of technical challenges and cost. http://dx.doi.org/10.1038/npre.2008.1590.1 Tue, 12 Feb 2008 21:48:02 UTC Reducing Greenhouse Gas Emissions: Geological Storage of CO2 doi:10.1038/npre.2008.1590.1 2008-04-29 Tara LaForce Nature Precedings 2008-02-12T21:48:02Z Presentation Earth & Environment http://creativecommons.org/licenses/by/3.0/