Download or read book The Carbon Isotope Biogeochemistry of Epsilon Co2 Production in a Methanogenic Marine Sediment written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-13 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: To investigate the relationship between sigma(CO2) delta(C-13) values and rates of the dominant remineralization processes at the organic-rich field site of Cape Lookout Bight, NC, the isotopic composition of porewater sigma(CO2) was measured on a seasonal basis. The sigma(CO2) delta(C-13) values varies seasonally in response to changes in rates of sulfate reduction and methanogenesis, the dominant remineralization processes at this site. A tube incubation experiment was also performed to determine the isotopic signature of the sigma(CO2) produced by sulfate reduction and methanogenesis. The delta(C-13) of the sigma(CO2) produced in the sulfate reduction zone determined from the tube incubation was -14.3 plus or minus 1.9, a value enriched in C-13 relative to the labile organic fraction. The C-13-enrichment may be caused by low rates of methanogenesis occurring in the sulfate reduction zone. The delta(C-13) of the sigma(CO2) produced in the methanogenic zone was estimated to be +44 per mil, whereas the co-produced methane was -65 per mil. The fractionation factor for CO2 reduction was calculated to be 1.055, a value in agreement with previous estimates at this site. The measured concentration and delta(C-13) of the sigma(CO2) at Cape Lookout was closely reproduced by a diagenetic model using the measured rates of sulfate reduction and sigma(CO2) production, and the isotopic signature of the sigma(CO2) production in the two biogeochemical zones. Boehme, Susan E. Unspecified Center ...

Download or read book Carbon Isotope Biogeochemistry of Epsilon CO2 Production in a Methanogenic Marine Sediment written by S. E. Boehme and published by . This book was released on 1993 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Carbon Isotope Biogeochemistry of a Methanogenic Marine Sediment written by Susan Elizabeth Boehme and published by . This book was released on 1993 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Stable Carbon Isotope Biogeochemistry of Acetate and Methane in Freshwater Environments written by Jeffrey Todd Gelwicks and published by . This book was released on 1989 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 818 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 The Carbon Cycle in an Anoxic Marine Sediment written by Marc J. Alperin and published by . This book was released on 1989 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government Reports Announcements Index written by and published by . This book was released on 1994 with total page 1142 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ocean Biogeochemistry written by Michael J.R. Fasham and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: Oceans account for 50% of the anthropogenic CO2 released into the atmosphere. During the past 15 years an international programme, the Joint Global Ocean Flux Study (JGOFS), has been studying the ocean carbon cycle to quantify and model the biological and physical processes whereby CO2 is pumped from the ocean's surface to the depths of the ocean, where it can remain for hundreds of years. This project is one of the largest multi-disciplinary studies of the oceans ever carried out and this book synthesises the results. It covers all aspects of the topic ranging from air-sea exchange with CO2, the role of physical mixing, the uptake of CO2 by marine algae, the fluxes of carbon and nitrogen through the marine food chain to the subsequent export of carbon to the depths of the ocean. Special emphasis is laid on predicting future climatic change.

Download or read book Biogeochemistry of Marine Dissolved Organic Matter written by Dennis A. Hansell and published by Elsevier. This book was released on 2024-07-04 with total page 870 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biogeochemistry of Marine Dissolved Organic Matter, 3rd edition is the most up-to-date revision of the fundamental reference for the biogeochemistry of marine dissolved organic matter. Since its original publication in June 2002, the science, questions, and priorities have advanced, and the editors of this essential guide, have added nine new chapters, including one on the South China Sea. An indispensable manual edited by the most distinguished experts in the field, this book is addressed to graduate students, marine scientists, and all professionals interested in advancing their knowledge of the field. Features up-to-date knowledge on DOM, including 9 new chapters Presents the only published work to synthesize recent research on dissolved organic carbon in the South China, a region receiving a great deal of attention in recent decades Offers contributions by world-class research leaders

Download or read book Methanogenesis Redox and Carbon Isotope Biogeochemistry Georgetown Lake Montana written by Tyler Johnston and published by . This book was released on 2014 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Previous studies conducted at Georgetown Lake have identified increasing concentrations of dissolved inorganic carbon (DIC) near the bottom of the lake and this DIC was also isotopically heavier (delta13C- DIC) than in the upper reaches of the water column. Based on this observation methane production was suspected to be occurring, since acetoclastic methanogenesis produces isotopically depleted CH4 and enriched CO2.

Download or read book Marine Carbon Biogeochemistry written by Jack J Middelburg and published by . This book was released on 2020-10-08 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book discusses biogeochemical processes relevant to carbon and aims to provide readers, graduate students and researchers, with insight into the functioning of marine ecosystems. A carbon centric approach has been adopted, but other elements are included where relevant or needed. The book focuses on concepts and quantitative understanding of primary production, organic matter mineralization and sediment biogeochemistry. The impact of biogeochemical processes on inorganic carbon dynamics and organic matter transformation are also discussed. This work was published by Saint Philip Street Press pursuant to a Creative Commons license permitting commercial use. All rights not granted by the work's license are retained by the author or authors.

Download or read book Marine Carbon Biogeochemistry written by Jack J. Middelburg and published by . This book was released on 2019 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book discusses biogeochemical processes relevant to carbon and aims to provide readers, graduate students and researchers, with insight into the functioning of marine ecosystems. A carbon centric approach has been adopted, but other elements are included where relevant or needed. The book focuses on concepts and quantitative understanding of primary production, organic matter mineralization and sediment biogeochemistry. The impact of biogeochemical processes on inorganic carbon dynamics and organic matter transformation are also discussed.

Download or read book Carbon Cycling in the Glacial Ocean written by Rainer Zahn and published by Springer. This book was released on 1994 with total page 606 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Ocean Carbon Cycle and Climate written by Mick Follows and published by Springer Science & Business Media. This book was released on 2004-08-03 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our desire to understand the global carbon cycle and its link to the climate system represents a huge challenge. These overarching questions have driven a great deal of scientific endeavour in recent years: What are the basic oceanic mechanisms which control the oceanic carbon reservoirs and the partitioning of carbon between ocean and atmosphere? How do these mechanisms depend on the state of the climate system and how does the carbon cycle feed back on climate? What is the current rate at which fossil fuel carbon dioxide is absorbed by the oceans and how might this change in the future? To begin to answer these questions we must first understand the distribution of carbon in the ocean, its partitioning between different ocean reservoirs (the "solubility" and "biological" pumps of carbon), the mechanisms controlling these reservoirs, and the relationship of the significant physical and biological processes to the physical environment. The recent surveys from the JGOFS and WOCE (Joint Global Ocean Flux Study and World Ocean Circulation Ex periment) programs have given us a first truly global survey of the physical and biogeochemical properties of the ocean. These new, high quality data provide the opportunity to better quantify the present oceans reservoirs of carbon and the changes due to fossil fuel burning. In addition, diverse process studies and time-series observations have clearly revealed the complexity of interactions between nutrient cycles, ecosystems, the carbon-cycle and the physical envi ronment.

Download or read book Government Reports Annual Index written by and published by . This book was released on 1994 with total page 1368 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Application of Transport reaction Modeling to Constrain Biogeochemical Processes in Marine Sediments written by Wei-Li Hong and published by . This book was released on 2014 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantifying the mass transport through marine sediments, and the geochemical response to such flow with numerical models has become a common and powerful approach for geochemical data interpretation. In this dissertation, I developed and applied transport-reaction models to unravel complex and interdependent reactions involving carbon, sulfur and silica transformations in shallow marine sediments, and the impact of physical (mass transport deposits) and depositional events (volcanic ash input) on the overall geochemical state of the system. Carbon cycling in the gas hydrate bearing sediments of the Ulleung Basin was quantified using both box and kinetic modeling approaches. The box model balances mass, flux, and carbon isotopes of carbon (Chapter 2), and led to a better understanding of how methane is cycled in the marine sediments of this area. This effort demonstrates the significance of CO2 reduction, a previously overlooked reaction. The picture of reaction network derived from this work serves as the foundation for a transport-reaction model (Chapter 3). The kinetic model results revealed a very different biogeochemistry between two distinct fluid-flow environments. At sites where transport is predominantly diffusive (non-chimney environments), organic matter decomposition is the dominant process driving production of methane, dissolved inorganic carbon (DIC) and consumption of sulfate. In contrast, anaerobic oxidation of methane (AOM) drives both carbon and sulfur cycles in the advective settings characterized by acoustic chimneys indicative of gas transport. I show that methane produced within the model domain, through CO2 reduction and methanogenesis, fuels AOM in the non-chimney sites while AOM is primarily induced by methane from external sources at the chimney sites. A simulation of the system evolution from a non-chimney to a chimney condition was developed by increasing the bottom methane supply to an originally diffusion-controlled site. Results from this exercise show that the higher methane flux leads to a higher AOM activity, and enhanced organic matter decomposition through methanogenesis. Organic carbon cycling is also affected by changes in the depositional environment, as shown by application of the kinetic model to the sediments from the Krishna-Godavary (K-G) basin along the eastern Indian margin (Chapter 4). Proximity to large rivers results in the widespread occurrence of mass transport deposits (MTD) throughout the basin. In this work, MTD is defined as a fluidized sediment block whose pore water composition is identical to sea water value to reflect the homogenization process during sediment transport. The pore water sulfate and ammonium profiles measured at seven sites drilled in the K-G Basin during the NGHP-01 expedition were simulated to provide a quantitative description of how MTDs can affect geochemistry profiles, not only for sulfate and ammonium but potentially all pore water species. This model provides reliable estimates of the MTDs thickness, the time elapsed after the most recent event, and the organoclastic sulfate reduction rate at these seven sites. A transport-reaction modeling approach was also applied to investigate the silica diagenetic reactions fueled by volcanic ash decomposition in Shikuko Basin, Nankai Trough (Chapter 5). The model developed for this setting reproduces a silica diagenetic boundary (SDB) at each site, which is defined by marked decreases in reactive volcanic ash, pore water silica and potassium. Volcanic ash alteration was constrained by modeling pore water 87Sr/86Sr profiles. Below the SDB, formation of clinoptilolite consumes potassium and regulates the extension of amorphous silica by consuming SiO2(aq). The observed low SiO2(aq) and dissolved potassium in these deep sequences require continuous precipitation of clinoptilolite; however in order to maintain oversaturation of this mineral at the low SiO2(aq) in sediments below the SDB, an increase in pH is required, consistent with pore water observations. Thermal history, rather than temperature alone, controls the inferred reaction network as shown by the convergence of the thermal maturity of sediments at the SDB from all studied sites and is consistent with other locations documented onshore Japan. These results are valuable as we move forward in understanding the mechanisms and consequences of ash alteration in convergent margins worldwide.