Download or read book Nitrogen Isotopes in Deep Time written by Colin Mettam and published by Cambridge University Press. This book was released on 2021-02-18 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrogen is an essential nutrient for life, and its sources and cycling have varied over earth history. Stable isotope ratios of nitrogen compounds (expressed as δ15N, in ‰) are preserved in the sedimentary record and track these changes, providing important insights into associated biogeochemical feedbacks. Here we review the use of nitrogen stable isotope geochemistry in unravelling the evolution of the global N cycle in deep time. We highlight difficulties with preservation, unambiguous interpretations, and local versus global effects. We end with several case studies illustrating how depositional and stratigraphic context is crucial in reliably interpreting δ15N records in ancient marine sediments, both in ancient anoxic (Archean) and more recent well oxygenated (Phanerozoic) environments.
Download or read book Refining the Interpretation of Nitrogen Isotopes in Deep Time Systems written by Magali Ader and published by Frontiers Media SA. This book was released on 2022-08-01 with total page 173 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Carbon Cycling in the Glacial Ocean Constraints on the Ocean s Role in Global Change written by Rainer Zahn and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 579 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive progress report on the multi-disciplinary field of ocean and climate change research is given. It compiles introductory background papers and leading scientific results on the ocean-atmosphere carbon cycle with emphasis on the ocean's carbon inventory and the various components involved. The relationship between plankton productivity, carbon fixation, oceanic PCO2 and climate change is investigated from the viewpoint of long-term climatic change during the late Quaternary cycles of ice ages and warm ages. The various approaches range from micropaleontology over organic and trace element geochemistry to molecular isotope geochemistry.
Download or read book Barium Isotopes written by Tristan J. Horner and published by Cambridge University Press. This book was released on 2021-04-22 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the modern marine environment, barium isotope (δ138Ba) variations are primarily driven by barite cycling—barite incorporates 'light' Ba isotopes from solution, rendering the residual Ba reservoir enriched in 'heavy' Ba isotopes by a complementary amount. Since the processes of barite precipitation and dissolution are vertically segregated and spatially heterogeneous, barite cycling drives systematic variations in the barium isotope composition of seawater and sediments. This Element examines these variations; evaluates their global, regional, local, and geological controls; and, explores how δ138Ba can be exploited to constrain the origin of enigmatic sedimentary sulfates and to study marine biogeochemistry over Earth's history.
Download or read book Molybdenum as a Paleoredox Proxy written by Stephan R. Hlohowskyj and published by Cambridge University Press. This book was released on 2021-09-09 with total page 57 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molybdenum (Mo) is a widely used trace metal for investigating redox conditions. However, unanswered questions remain that concentration and bulk isotopic analysis cannot specially answer. Improvements can be made by combining new geochemical techniques to traditional methods of Mo analysis. In this Element, we propose a refinement of Mo geochemistry within aquatic systems, ancient rocks, and modern sediments through molecular geochemistry (systematically combining concentration, isotope ratio, elemental mapping, and speciation analyses). Specifically, to intermediate sulfide concentrations governing Mo behavior below the 'switch-point' and dominant sequestration pathways in low oxygen conditions. The aim of this work is to 1) aid and improve the breadth of Mo paleoproxy interpretations by considering Mo speciation and 2) address outstanding research gaps concerning Mo systematics (cycling, partitioning, sequestration, etc.). The Mo paleoproxy has potential to solve ever complex research questions. By using molecular geochemical recommendations, improved Mo paleoproxy interpretations and reconstruction can be achieved.
Download or read book Local and Global Controls on Carbon Isotope Chemostratigraphy written by Anne-Sofie Ahm and published by Cambridge University Press. This book was released on 2022-03-31 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over million-year timescales, the geologic cycling of carbon controls long-term climate and the oxidation of Earth's surface. Inferences about the carbon cycle can be made from time series of carbon isotopic ratios measured from sedimentary rocks. The foundational assumption for carbon isotope chemostratigraphy is that carbon isotope values reflect dissolved inorganic carbon in a well-mixed ocean in equilibrium with the atmosphere. However, when applied to shallow-water platform environments, where most ancient carbonates preserved in the geological record formed, recent research has documented the importance of considering both local variability in surface water chemistry and diagenesis. These findings demonstrate that carbon isotope chemostratigraphy of platform carbonate rarely represent the average carbonate sink or directly records changes in the composition of global seawater. Understanding what causes local variability in shallow-water settings, and what this variability might reveal about global boundary conditions, are vital questions for the next generation of carbon isotope chemostratigraphers.
Download or read book Iron Formations as Palaeoenvironmental Archives written by Kaarel Mänd and published by Cambridge University Press. This book was released on 2022-01-20 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ancient iron formations - iron and silica-rich chemical sedimentary rocks that formed throughout the Precambrian eons - provide a significant part of the evidence for the modern scientific understanding of palaeoenvironmental conditions in Archaean (4.0–2.5 billion years ago) and Proterozoic (2.5–0.539 billion years ago) times. Despite controversies regarding their formation mechanisms, iron formations are a testament to the influence of the Precambrian biosphere on early ocean chemistry. As many iron formations are pure chemical sediments that reflect the composition of the waters from which they precipitated, they can also serve as nuanced geochemical archives for the study of ancient marine temperatures, redox states, and elemental cycling, if proper care is taken to understand their sedimentological context.
Download or read book Reconstructing Precambrian pCO2 and pO2 Using Paleosols written by Nathan D. Sheldon and published by Cambridge University Press. This book was released on 2021-03-04 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Paleosols formed in direct contact with the Earth's atmosphere, so they can record the composition of the atmosphere through weathering processes and products. Herein we critically review a variety of different approaches for reconstructing atmospheric O2 and CO2 over the past three billion years. Paleosols indicate relatively low CO2 over that time, requiring additional greenhouse forcing to overcome the 'faint young Sun' paradox in the Archean and Mesoproterozoic, as well as low O2 levels until the Neoproterozoic. Emerging techniques will revise the history of Earth's atmosphere further and may provide a window into atmospheric evolution on other planets.
Download or read book Emerging Patterns in Proterozoic Lipid Biomarker Records written by Gordon D. Love and published by Cambridge University Press. This book was released on 2021-03-25 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Diverse and abundant lipid biomarker assemblages have been reported from a variety of Proterozoic marine environments from the careful analysis of well-preserved rocks and oils. These molecular biosignatures have provided unique insights into the communities and the environmental conditions which characterized the Proterozoic marine biosphere. We summarize some of the major temporal patterns evident in Proterozoic lipid biomarkers found to date, whilst emphasizing the scale of local heterogeneity found within Neoproterozoic oceans from region to region, and their relationship with the evolving ecological, climatic and ocean/atmospheric redox conditions. Short commentaries on a selection of papers published from the last 15 years of biomarker literature are given. The focus here is on key studies, highlighted for further reading, which have helped to better constrain the timing of the ecological expansion of eukaryotes in Proterozoic oceans or which have impacted on our knowledge of the biological sources of Proterozoic biomarkers.
Download or read book Deep time Perspectives on Climate Change written by Mark Williams and published by Geological Society of London. This book was released on 2007 with total page 604 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nitrogen in the Marine Environment written by Edward J. Carpenter and published by Elsevier. This book was released on 2013-10-22 with total page 919 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrogen in the Marine Environment provides information pertinent to the many aspects of the nitrogen cycle. This book presents the advances in ocean productivity research, with emphasis on the role of microbes in nitrogen transformations with excursions to higher trophic levels. Organized into 24 chapters, this book begins with an overview of the abundance and distribution of the various forms of nitrogen in a number of estuaries. This text then provides a comparison of the nitrogen cycling of various ecosystems within the marine environment. Other chapters consider chemical distributions and methodology as an aid to those entering the field. This book discusses as well the enzymology of the initial steps of inorganic nitrogen assimilation. The final chapter deals with the philosophy and application of modeling as an investigative method in basic research on nitrogen dynamics in coastal and open-ocean marine environments. This book is a valuable resource for plant biochemists, microbiologists, aquatic ecologists, and bacteriologists.
Download or read book Calcium Isotopes written by Elizabeth M. Griffith and published by Cambridge University Press. This book was released on 2021-01-21 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: Precise measurements of the calcium (Ca) isotopes have provided constraints on Ca cycling at global and local scales, and quantified rates of carbonate diagenesis in marine sedimentary systems. Key to applying Ca isotopes as a geochemical tracer of Ca cycling, carbonate (bio)mineralization, and diagenesis is an understanding of the impact of multiple factors potentially impacting Ca isotopes in the rock record. These factors include variations in stable isotopic fractionation factors, the influence of local-scale Ca cycling on Ca isotopic gradients in carbonate settings, carbonate dissolution and reprecipitation, and the relationship between the Ca isotopic composition of seawater and mineral phases that record the secular evolution of seawater chemistry.
Download or read book Encyclopedia of Geochemistry written by C.P. Marshall and published by Springer Science & Business Media. This book was released on 1999-07-31 with total page 677 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a complete and authoritative reference text on an evolving field. Over 200 international scientists have written over 340 separate topics on different aspects of geochemistry including organics, trace elements, isotopes, high and low temperature geochemistry, and ore deposits, to name just a few.
Download or read book Isotopes Advances in Research and Application 2011 Edition written by and published by ScholarlyEditions. This book was released on 2012-01-09 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt: Isotopes: Advances in Research and Application: 2011 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Isotopes. The editors have built Isotopes: Advances in Research and Application: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Isotopes in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Isotopes: Advances in Research and Application: 2011 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
Download or read book Isotopes Advances in Research and Application 2013 Edition written by and published by ScholarlyEditions. This book was released on 2013-06-21 with total page 435 pages. Available in PDF, EPUB and Kindle. Book excerpt: Isotopes—Advances in Research and Application: 2013 Edition is a ScholarlyEditions™ book that delivers timely, authoritative, and comprehensive information about Nitrogen Isotopes. The editors have built Isotopes—Advances in Research and Application: 2013 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Nitrogen Isotopes in this book to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Isotopes—Advances in Research and Application: 2013 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
Download or read book Metals Microbes and Minerals The Biogeochemical Side of Life written by Peter Kroneck and published by Walter de Gruyter GmbH & Co KG. This book was released on 2021-01-18 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal Ions in Life Sciences links coordination chemistry and biochemistry in their widest sense and thus increases our understanding of the relationship between the chemistry of metals and life processes; in fact, it is an old wisdom that metals are indispensable for life. The series reflects the interdisciplinary nature of Biological Inorganic Chemistry and coordinates the efforts of scientists in numerous interconnecting research fields.
Download or read book Encyclopedia of Ecology written by Brian D. Fath and published by Newnes. This book was released on 2014-11-03 with total page 4292 pages. Available in PDF, EPUB and Kindle. Book excerpt: The groundbreaking Encyclopedia of Ecology provides an authoritative and comprehensive coverage of the complete field of ecology, from general to applied. It includes over 500 detailed entries, structured to provide the user with complete coverage of the core knowledge, accessed as intuitively as possible, and heavily cross-referenced. Written by an international team of leading experts, this revolutionary encyclopedia will serve as a one-stop-shop to concise, stand-alone articles to be used as a point of entry for undergraduate students, or as a tool for active researchers looking for the latest information in the field. Entries cover a range of topics, including: Behavioral Ecology Ecological Processes Ecological Modeling Ecological Engineering Ecological Indicators Ecological Informatics Ecosystems Ecotoxicology Evolutionary Ecology General Ecology Global Ecology Human Ecology System Ecology The first reference work to cover all aspects of ecology, from basic to applied Over 500 concise, stand-alone articles are written by prominent leaders in the field Article text is supported by full-color photos, drawings, tables, and other visual material Fully indexed and cross referenced with detailed references for further study Writing level is suited to both the expert and non-expert Available electronically on ScienceDirect shortly upon publication
