Download or read book The Anomalous Oxygen Isotopic Composition of Atmospheric CO2 and Applications to the Carbon Cycle and Stratospheric Chemistry and Transport written by Katherine Jean Hoag and published by . This book was released on 2007 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Non mass dependent Isotopic Composition of Ozone and Its Photochemical Transfer to Stratospheric CO2 written by Aaron Andrew Wiegel and published by . This book was released on 2013 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atypically large and non-mass-dependent kinetic isotope effects (KIEs) in the three-body ozone formation reaction, O(3P) + O2 2!O3* + M 2!O3 + M*, lead to a non-mass-dependent oxygen isotopic composition for O3 observed in both the laboratory and the atmosphere. Theoretical work has suggested that a dynamically-driven, quantum symmetry isotope effect in the lifetime of the excited ozone complex O3* or its collisional stabilization is responsible, although the underlying chemical physics has remained mysterious. Stratospheric CO2 also has a non-mass-dependent oxygen isotopic composition that is thought to be transferred from ozone by photolysis to form O(1D) followed by the O(1D) + CO2 isotope exchange reaction. However, the non-mass-dependent isotopic compositions of CO2 measured either in UV photochemistry experiments or in stratospheric air samples could not easily be explained by isotope effects in ozone formation, leading some to claim that additional anomalous isotope effects must exist in ozone photolysis or in the O(1D) + CO2 isotope exchange reaction. In the research results presented here, I detail several significant advances in the understanding of the non-mass-dependent isotopic composition of ozone and its transfer to stratospheric CO2. I made these advances through new measurements and kinetics modeling of the isotopic composition of O3 and CO2 in photochemistry experiments in which mixtures of O2, CO2, and other bath gases were irradiated with UV light from a mercury lamp as well as comparisons of these results with the latitude, altitude, and seasonal dependence of the isotopic composition of stratospheric CO2. For application to the non-mass-dependent isotopic composition of stratospheric CO2, I show using a kinetics model that the non-mass-dependent isotope effects in ozone formation alone can quantitatively account for the non-mass-dependent isotopic composition of CO2 in laboratory measurements of UV-irradiated mixtures of O2 and CO2 at atmospheric mixing ratios. I then used the kinetics model to provide a conceptual framework for understanding the significant differences in the non-mass-dependent isotopic composition of CO2 between the laboratory experiments and the stratosphere and between different regions of the stratosphere that I discovered in the atmospheric measurements. Based on model sensitivities to the temperature dependence of the ozone KIEs and mass-dependent isotope effects in ozone photolysis, differences in temperature and in the relative rate of ozone photolysis are found to be the likely sources of the differences in the non-mass-dependent isotopic composition of CO2 between the laboratory and the stratosphere and between different regions of the stratosphere. Having accounted for the non-mass-dependent isotopic composition of CO2 at an atmospheric O2/CO2 mixing ratio, I performed additional laboratory measurements of the non-mass-dependent isotopic composition of CO2 as a function of the O2/CO2 mixing ratio to explore the dramatic decrease in the non-mass-dependent 17O and 18O enrichments in CO2 as the O2/CO2 mixing ratio decreases found in previous experiments. Kinetics modeling shows that expected changes in the non-mass-dependent KIEs in ozone formation as O2/CO2 decreases cannot explain the O2/CO2 dependence of the non-mass-dependent enrichments in CO2, so a number of different potential chemical mechanisms with non-mass-dependent isotope effects were tested using the model. Of the mechanisms tested, only inclusion of non-thermal rate coefficients for the reactions of 16O(1D), 17O(1D), and 18O(1D) with O2, CO2, and O3 led to any significant decrease in the non-mass-dependent isotopic composition of CO2 as the O2/CO2 mixing ratio is decreased in the model. These non-thermal rate coefficients were derived from non-thermal kinetic energy distributions for 16O(1D), 17O(1D), and 18O(1D) that were calculated using the hard sphere approximation for collisional energy transfer between O(1D) and O2 and between O(1D) and CO2 and the initial energy distributions from O3 photolysis. While the inclusion of the non-thermal rate coefficients in the model produced an O2/CO2 mixing ratio dependence that is still approximately 5 times smaller than the experimentally observed O2/CO2 mixing ratio dependence (i.e.-5 / instead of -50 / from high to low O2/CO2), that the non-thermal reactions involving 16O(1D), 17O(1D), and 18O(1D) could produce non-mass-dependent isotopic compositions even though the corresponding thermal reactions are mass-dependent is novel and, to our knowledge, has not been explored thoroughly in any previous work. Because of the role that collisional energy plays in the isotope exchange between O(1D) and CO2, I also conducted measurements of the isotopic composition of O3 formed in different bath gases, M, to test how the efficiency of collisional energy transfer between O3* and M in ozone formation affects the non-mass-dependent isotopic composition of the resulting O3. New measurements and kinetics modeling of the isotopic composition of O3 formed in an air-like mixture of O2/N2 show statistically significant differences between the non-mass-dependent isotopic composition of O3 formed in pure O2 and in an air-like mixture of O2 and N2. Using a kinetics model, I explore possible origins for these differences in in these experiments and in experiments involving O3 photolysis or O3 formation in SF6. The combined results comparing the model results with the measurements suggest that mass-dependent KIEs in the O2(1[Sigma]) + O3 reaction can likely be ruled out and that the radical complex mechanism for O3 formation (as opposed to the energy transfer mechanism) may indeed play a role in generating the differences in the isotopic composition of O3 formed in different bath gases.
Download or read book The Phanerozoic Carbon Cycle written by Robert A. Berner and published by Oxford University Press. This book was released on 2004-08-19 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: The term "carbon cycle" is normally thought to mean those processes that govern the present-day transfer of carbon between life, the atmosphere, and the oceans. This book describes another carbon cycle, one which operates over millions of years and involves the transfer of carbon between rocks and the combination of life, the atmosphere, and the oceans. The weathering of silicate and carbonate rocks and ancient sedimentary organic matter (including recent, large-scale human-induced burning of fossil fuels), the burial of organic matter and carbonate minerals in sediments, and volcanic degassing of carbon dioxide contribute to this cycle. In The Phanerozoic Carbon Cycle, Robert Berner shows how carbon cycle models can be used to calculate levels of atmospheric CO[2 and O[2 over Phanerozoic time, the past 550 million years, and how results compare with independent methods. His analysis has implications for such disparate subjects as the evolution of land plants, the presence of giant ancient insects, the role of tectonics in paleoclimate, and the current debate over global warming and greenhouse gases
Download or read book CO2 in Seawater Equilibrium Kinetics Isotopes written by R.E. Zeebe and published by Elsevier. This book was released on 2001-10-15 with total page 361 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon dioxide is the most important greenhouse gas after water vapor in the atmosphere of the earth. More than 98% of the carbon of the atmosphere-ocean system is stored in the oceans as dissolved inorganic carbon. The key for understanding critical processes of the marine carbon cycle is a sound knowledge of the seawater carbonate chemistry, including equilibrium and nonequilibrium properties as well as stable isotope fractionation. Presenting the first coherent text describing equilibrium and nonequilibrium properties and stable isotope fractionation among the elements of the carbonate system. This volume presents an overview and a synthesis of these subjects which should be useful for graduate students and researchers in various fields such as biogeochemistry, chemical oceanography, paleoceanography, marine biology, marine chemistry, marine geology, and others. The volume includes an introduction to the equilibrium properties of the carbonate system in which basic concepts such as equilibrium constants, alkalinity, pH scales, and buffering are discussed. It also deals with the nonequilibrium properties of the seawater carbonate chemistry. Whereas principle of chemical kinetics are recapitulated, reaction rates and relaxation times of the carbonate system are considered in details. The book also provides a general introduction to stable isotope fractionation and describes the partitioning of carbon, oxygen, and boron isotopes between the species of the carbonate system. The appendix contains formulas for the equilibrium constants of the carbonate system, mathematical expressions to calculate carbonate system parameters, answers to exercises and more.
Download or read book A History of Atmospheric CO2 and Its Effects on Plants Animals and Ecosystems written by James R. Ehleringer and published by Springer Science & Business Media. This book was released on 2005-07-28 with total page 545 pages. Available in PDF, EPUB and Kindle. Book excerpt: Based in extensive research in geology, atmospheric science, and paleontology, this book offers a detailed history of CO2 in the atmosphere, and an understanding of factors that have influenced changes in the past. The text illuminates the role of atmospheric CO2 in the modern carbon cycle and in the evolution of plants and animals, and addresses the future role of atmospheric CO2 and its likely effects on ecosystems.
Download or read book Measurements and Analysis of Post bomb Era Stratospheric 14CO2 written by Lauren Lee Comfort and published by . This book was released on 2008 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Carbon Cycle and Atmospheric CO2 written by Eric T. Sundquist and published by . This book was released on 1985 with total page 648 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advances In Atmospheric Chemistry Volume 2 Organic Oxidation And Multiphase Chemistry written by John R Barker and published by World Scientific. This book was released on 2019-01-07 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt: This series presents authoritative invited summaries of research on atmospheric chemistry in a changing world. These range from comprehensive reviews of major subject areas to focused accounts by individual research groups. The topics may include laboratory studies, field measurements, in situ monitoring and remote sensing, studies of composition, chemical modeling, theories of atmospheric chemistry and climate, feedback mechanisms, emissions and deposition, biogeochemical cycles, and the links between atmospheric chemistry and the climate system at large.Volume 2 comprises chapters describing research on multiphase chemistry affecting air quality in China, on multiphase chemistry of organic compounds leading to secondary organic aerosol formation, on biogeochemical cycles involving ammonia, on oxidation of aromatic compounds, on reactions of Criegee intermediates (important in oxidation of alkenes), and on laboratory and field measurements of isotopic fractionation in the atmosphere.
Download or read book Triple Oxygen Isotope Variations in Natural and Anthropogenic Carbon Dioxide written by Magdalena Else Gabriele Hofmann and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The oxygen and carbon isotope composition (18O/16O and 13C/12C) of atmospheric carbon dioxide is an excellent tool to investigate the atmospheric CO2 cycle. In recent years, it has been suggested that the triple oxygen isotope composition (17O/16O and 18O/16O) of tropospheric CO2 might be a potential new tracer for the terrestrial gross primary production. This study investigates whether and to which extent this new tracer might complement conventional stable isotope investigations of tropospheric CO2. This thesis presents (i) a new high-precision technique for triple oxygen isotope analysi ...
Download or read book The Chemistry of CO2 and TiO2 written by Svatopluk Civiš and published by Springer. This book was released on 2019-07-06 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive overview of the chemistry of CO2 in relation to surface interactions and photocatalytic transformation by UV radiation. The first part deals with the modelling of an anatase surface, its interaction with CO2, and the spontaneous exchange of oxygen atoms between the gas and solid phases. The book then naturally transitions to the photocatalytic reduction of CO2, achieved by adding UV radiation and traces of water to the experimental system, to produce methane and CO. This photocatalytic reduction is explained in detail and the implications for planetary chemistry (specifically concerning Mars), as well as Earth’s atmospheric chemistry and global warming, are discussed.
Download or read book Synthesis Inversion of Atmospheric CO2 Using the GISS Tracer Transport Model written by I. G. Enting and published by . This book was released on 1993 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Production and Characterisation of High Purity Ozone and Experimental and Modelling Studies of Anomalous Oxygen Isotope Effects in the Formation of Carbon Dioxide from Irradiated Mixtures of Carbon Monoxide and Ozone Or Oxygen written by Daniela Simone and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ozone formation reaction O+O2+M→O3+M is a unique example of a chemical reaction that leads to an anomalous isotopic composition of the products, most likely due to symmetry - breaking effects. So far, results on other chemical systems that might show similar effects are spurious, even though such claims concerning reactions other than the formation of ozone have been made repeatedly.This applies in particular to the spin forbidden O+CO+M→CO2+M reaction, where two studies report a mass-independent fractionation of about 8%. Nevertheless, the presence of ozone in these experiments raises questions as to the validity of this assertion. We thus make a new attempt to study the O+CO+M reaction in the photoreactor at CCAR (University of Copenhagen) where reagents and contaminants are monitored on-line by FTIR spectroscopy. This study combined with the analysis of the spectral distribution of the employed lamps and isotope kinetic modeling lead to a complete re-interpretation of previous experiments. We conclude that available measurements are more compatible with the hypothesis that there is no mass-independent isotope fractionation in the O+CO reaction. We propose that all observations can be completely explained by an isotope transfer from ozone, involving photolytic production of O(1D) that in turn leads to OH radicals, which then rapidly form CO2 from reaction with CO. We also present a method to produce pure ozone samples and derive an upper limit on nitrogen oxide contaminations based on mass spectrometer measurements. These values will serve as benchmarks values for future studies of ozone absorption cross sections in the IR and UV.
Download or read book Halocarbons Effects on Stratospheric Ozone written by National Research Council (U.S.). Panel on Atmospheric Chemistry and published by National Academies. This book was released on 1976 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Middle Atmosphere written by PLUMB and published by Birkhäuser. This book was released on 2013-11-21 with total page 465 pages. Available in PDF, EPUB and Kindle. Book excerpt: PAGEOPH, stratosphere, these differences provide us with new evidence, interpretation of which can materially help to advance our understanding of stratospheric dynamics in general. It is now weil established that smaller-scale motions-in particular gravity waves and turbulence-are of fundamental importance in the general circulation of the mesosphere; they seem to be similarly, if less spectacularly, significant in the troposphere, and probably also in the stratosphere. Our understanding of these motions, their effects on the mean circulation and their mutual interactions is progressing rapidly, as is weil illustrated by the papers in this issue; there are reports of observational studies, especially with new instruments such as the Japanese MV radar, reviews of the state of theory, a laboratory study and an analysis of gravity waves and their effects in the high resolution "SKYHI" general circulation model. There are good reasons to suspect that gravity waves may be of crucial significance in making the stratospheric circulation the way it is (modeling experience being one suggestive piece of evidence for this). Direct observational proof has thus far been prevented by the difficulty of making observations of such scales of motion in this region; in one study reported here, falling sphere observations are used to obtain information on the structure and intensity of waves in the upper stratosphere.
Download or read book Investigation of the Triple Oxygen Isotopic Composition of Ozone and Carbon Dioxide Through Experiments and Photochemical Modeling written by Amanda Susan Cole and published by . This book was released on 2006 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: Both O3 and CO2 in the stratosphere have unusual isotopic signatures in that they are more enriched in 17O than is expected based on their enrichments in 18O and the usual "mass-dependent" relationship between 17O and 18O. This 17O isotope anomaly in O3 is due to non-mass-dependent isotope effects in O3 formation, while the 17O isotope anomaly in CO2 is thought to arise, at least in part, from ultraviolet photolysis of anomalously enriched O3, followed by isotope exchange between the resulting O(1D) and CO2. However, efforts to quantify the transfer of the isotopic signature from O3 to CO2 have so far been unsuccessful. Furthermore, previous laboratory experiments have been interpreted to indicate that there may be additional non-mass-dependent isotope effects both in O 3 photolysis and in the CO2+O(1D) isotope exchange reaction. To address these issues, a photochemical kinetics model was developed to simulate all isotope-specific reactions involved in the isotope transfer. Using this model to simulate earlier O3 photolysis experiments revealed that non-mass-dependent isotope effects in O3 photolysis are not required to reproduce the experimental data, nor are recent theoretical calculations inconsistent with the laboratory results as they previously appeared to be. The model was then modified to include CO2 and used to test the sensitivity of the CO2 isotopic composition to isotope effects in underlying reactions. The predictions of this model were tested by performing a series of laboratory photochemistry experiments in which the isotopic composition of CO2 in a mixture with O2 was directly measured after irradiation with UV light. The results show that the reaction scheme in the model successfully describes the chemical origin of the 17O isotope anomaly in CO2, implying that no non-mass-dependent isotope effects exist in CO2+O(1D), O3 photolysis, or any other reaction besides O3 formation. These findings may lead to a deeper understanding of the chemical physics of non-mass-dependent isotope effects in general. In addition, measurements of the anomaly in CO 2 in the atmosphere and in O2 in ice cores can now be more confidently used as tracers of stratospheric ozone chemistry and transport and of biospheric productivity on annual and millennial timescales.
Download or read book Compilation of Minimum and Maximum Isotope Ratios of Selected Elements in Naturally Occurring Terrestrial Materials and Reagents written by Tyler B. Coplen and published by . This book was released on 2002 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: Documented variations in the isotopic compositions of some chemical elements are responsible for expanded uncertainties in the standard atomic weights published by the Commission on Atomic Weights and Isotopic Abundances of the International Union of Pure and Applied Chemistry. This report summarizes reported variations in the isotopic compositions of 20 elements that are due to physical and chemical fractionation processes (not due to radioactive decay) and their effects on the standard atomic weight uncertainties. For 11 of those elements (hydrogen, lithium, boron, carbon, nitrogen, oxygen, silicon, sulfur, chlorine, copper, and selenium), standard atomic weight uncertainties have been assigned values that are substantially larger than analytical uncertainties because of common isotope abundance variations in materials of natural terrestrial origin. For 2 elements (chromium and thallium), recently reported isotope abundance variations potentially are large enough to result in future expansion of their atomic weight uncertainties. For 7 elements (magnesium, calcium, iron, zinc, molybdenum, palladium, and tellurium), documented isotope-abundance variations in materials of natural terrestrial origin are too small to have a significant effect on their standard atomic weight uncertainties.
Download or read book The Carbon Cycle written by T. M. L. Wigley and published by Cambridge University Press. This book was released on 2005-08-22 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reducing carbon dioxide (CO2) emissions is imperative to stabilizing our future climate. Our ability to reduce these emissions combined with an understanding of how much fossil-fuel-derived CO2 the oceans and plants can absorb is central to mitigating climate change. In The Carbon Cycle, leading scientists examine how atmospheric carbon dioxide concentrations have changed in the past and how this may affect the concentrations in the future. They look at the carbon budget and the "missing sink" for carbon dioxide. They offer approaches to modeling the carbon cycle, providing mathematical tools for predicting future levels of carbon dioxide. This comprehensive text incorporates findings from the recent IPCC reports. New insights, and a convergence of ideas and views across several disciplines make this book an important contribution to the global change literature.
