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 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 Oxygen Isotope Effect in the Formation of Ozone from Molecular Discharge written by John E. Heidenreich and published by . This book was released on 1985 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Isotope Effects In Chemistry and Biology written by Amnon Kohen and published by CRC Press. This book was released on 2005-11-01 with total page 1092 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of isotope effects has expanded exponentially in the last decade, and researchers are finding isotopes increasingly useful in their studies. Bringing literature on the subject up to date, Isotope Effects in Chemistry and Biology covers current principles, methods, and a broad range of applications of isotope effects in the physical, biolo
Download or read book Treatise on Geochemistry written by and published by Newnes. This book was released on 2013-10-19 with total page 14787 pages. Available in PDF, EPUB and Kindle. Book excerpt: This extensively updated new edition of the widely acclaimed Treatise on Geochemistry has increased its coverage beyond the wide range of geochemical subject areas in the first edition, with five new volumes which include: the history of the atmosphere, geochemistry of mineral deposits, archaeology and anthropology, organic geochemistry and analytical geochemistry. In addition, the original Volume 1 on "Meteorites, Comets, and Planets" was expanded into two separate volumes dealing with meteorites and planets, respectively. These additions increased the number of volumes in the Treatise from 9 to 15 with the index/appendices volume remaining as the last volume (Volume 16). Each of the original volumes was scrutinized by the appropriate volume editors, with respect to necessary revisions as well as additions and deletions. As a result, 27% were republished without major changes, 66% were revised and 126 new chapters were added. In a many-faceted field such as Geochemistry, explaining and understanding how one sub-field relates to another is key. Instructors will find the complete overviews with extensive cross-referencing useful additions to their course packs and students will benefit from the contextual organization of the subject matter Six new volumes added and 66% updated from 1st edition. The Editors of this work have taken every measure to include the many suggestions received from readers and ensure comprehensiveness of coverage and added value in this 2nd edition The esteemed Board of Volume Editors and Editors-in-Chief worked cohesively to ensure a uniform and consistent approach to the content, which is an amazing accomplishment for a 15-volume work (16 volumes including index volume)!
Download or read book Isotope Geochemistry written by Heinrich D Holland and published by Academic Press. This book was released on 2010-09-27 with total page 750 pages. Available in PDF, EPUB and Kindle. Book excerpt: After the discovery that elements were commonly composed of isotopes, there developed a range of studies of the variability of isotopic compositions in Earth materials, which was able to add to our understanding of Earth processes and history. This collection of chapters from the Treatise on Geochemistry describes the range of isotopic studies. The chapters are grouped into the following categories: light stable isotopes, radiogenic tracers, noble gases and radioactive tracers. The first three groups depend on mass spectrometric measurements. The section on radioactive tracers employs both radioactive counting techniques and the newly developed accelerator mass spectrometric techniques. Comprehensive, interdisciplinary and authoritative content selected by leading subject experts Robust illustrations, figures and tables Affordably priced sampling of content from the full Treatise on Geochemistry
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 Proceedings of the National Academy of Sciences of the United States of America written by National Academy of Sciences (U.S.). and published by . This book was released on 2007 with total page 1172 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 Introduction to Atmospheric Chemistry written by Daniel J. Jacob and published by Princeton University Press. This book was released on 1999 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atmospheric chemistry is one of the fastest growing fields in the earth sciences. Until now, however, there has been no book designed to help students capture the essence of the subject in a brief course of study. Daniel Jacob, a leading researcher and teacher in the field, addresses that problem by presenting the first textbook on atmospheric chemistry for a one-semester course. Based on the approach he developed in his class at Harvard, Jacob introduces students in clear and concise chapters to the fundamentals as well as the latest ideas and findings in the field. Jacob's aim is to show students how to use basic principles of physics and chemistry to describe a complex system such as the atmosphere. He also seeks to give students an overview of the current state of research and the work that led to this point. Jacob begins with atmospheric structure, design of simple models, atmospheric transport, and the continuity equation, and continues with geochemical cycles, the greenhouse effect, aerosols, stratospheric ozone, the oxidizing power of the atmosphere, smog, and acid rain. Each chapter concludes with a problem set based on recent scientific literature. This is a novel approach to problem-set writing, and one that successfully introduces students to the prevailing issues. This is a major contribution to a growing area of study and will be welcomed enthusiastically by students and teachers alike.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2008 with total page 850 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Handbook of Environmental Isotope Geochemistry written by Mark Baskaran and published by Springer Science & Business Media. This book was released on 2011-10-13 with total page 944 pages. Available in PDF, EPUB and Kindle. Book excerpt: Applications of radioactive and stable isotopes have revolutionized our understanding of the Earth and near-earth surface processes. The utility of the isotopes are ever-increasing and our sole focus is to bring out the applications of these isotopes as tracers and chronometers to a wider audience so that they can be used as powerful tools to solve environmental problems. New developments in this field remain mostly in peer-reviewed journal articles and hence our goal is to synthesize these findings for easy reference for students, faculty, regulators in governmental and non-governmental agencies, and environmental companies. While this volume maintains its rigor in terms of its depth of knowledge and quantitative information, it contains the breadth needed for wide variety problems and applications in the environmental sciences. This volume presents all of the newer and older applications of isotopes pertaining to the environmental problems in one place that is readily accessible to readers. This book not only has the depth and rigor that is needed for academia, but it has the breadth and case studies to illustrate the utility of the isotopes in a wide variety of environments (atmosphere, oceans, lakes, rivers and streams, terrestrial environments, and sub-surface environments) and serves a large audience, from students and researchers, regulators in federal, state and local governments, and environmental companies.
Download or read book The Atmosphere written by Ralph F. Keeling and published by Pergamon. This book was released on 2006-06-20 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Treatise on Geochemistry is the first work providing a comprehensive, integrated summary of the present state of geochemistry. It deals with all the major subjects in the field, ranging from the chemistry of the solar system to environmental geochemistry. The Treatise on Geochemistry has drawn on the expertise of outstanding scientists throughout the world, creating the reference work in geochemistry for the next decade. Each volume consists of fifteen to twenty-five chapters written by recognized authorities in their fields, and chosen by the Volume Editors in consultation with the Executive Editors. Particular emphasis has been placed on integrating the subject matter of the individual chapters and volumes. Elsevier also offers the Treatise on Geochemistry in electronic format via the online platform ScienceDirect, the most comprehensive database of academic research on the Internet today, enhanced by a suite of sophisticated linking, searching and retrieval tools.
Download or read book The Atmosphere and Climate of Mars written by Robert M. Haberle and published by Cambridge University Press. This book was released on 2017-06-29 with total page 613 pages. Available in PDF, EPUB and Kindle. Book excerpt: Humanity has long been fascinated by the planet Mars. Was its climate ever conducive to life? What is the atmosphere like today and why did it change so dramatically over time? Eleven spacecraft have successfully flown to Mars since the Viking mission of the 1970s and early 1980s. These orbiters, landers and rovers have generated vast amounts of data that now span a Martian decade (roughly eighteen years). This new volume brings together the many new ideas about the atmosphere and climate system that have emerged, including the complex interplay of the volatile and dust cycles, the atmosphere-surface interactions that connect them over time, and the diversity of the planet's environment and its complex history. Including tutorials and explanations of complicated ideas, students, researchers and non-specialists alike are able to use this resource to gain a thorough and up-to-date understanding of this most Earth-like of planetary neighbours.
Download or read book Oceanography for Beginners written by Pronab K. Banerjee and published by Allied Publishers. This book was released on 2005 with total page 708 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Isotope Effects written by Max Wolfsberg and published by Springer Science & Business Media. This book was released on 2009-12-15 with total page 477 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the title suggests, Isotope Effects in the Chemical, Geological and Bio Sciences deals with differences in the properties of isotopically substituted molecules, such as differences in the chemical and physical properties of water and the heavy waters. Since the various fields in which isotope effects are applied do not only share fundamental principles but also experimental techniques, this book includes a discussion of experimental apparatus and experimental techniques. Isotope Effects in the Chemical, Geological and Bio Sciences is an educational monograph addressed to graduate students and others undertaking isotope effect research. The fundamental principles needed to understand isotope effects are presented in appropriate detail. While it is true that these principles are more familiar to students of physical chemistry and some background in physical chemistry is recommended, the text provides enough detail to make the book an asset to students in organic and biochemistry, and geochemistry.
