Earth History of Oxygen and the iprOxy PDF Download
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Author: Zunli Lu
Publisher: Cambridge University Press
ISBN: 1009028413
Category : Science
Languages : en
Pages : 52
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Book Description
How oxygen levels in Earth's atmosphere and oceans evolved has always been a central question in Earth System Science. Researchers have developed numerous tracers to tackle this question, utilizing geochemical characteristics of different elements. Iodine incorporated in calcium carbonate (including biogenic) minerals, reported as I/Ca, is a proxy for dissolved oxygen in seawater. Here we review the rationale behind this proxy, its recent applications and some potential future research directions.
Author: Zunli Lu
Publisher: Cambridge University Press
ISBN: 1009028413
Category : Science
Languages : en
Pages : 52
Get Book Here
Book Description
How oxygen levels in Earth's atmosphere and oceans evolved has always been a central question in Earth System Science. Researchers have developed numerous tracers to tackle this question, utilizing geochemical characteristics of different elements. Iodine incorporated in calcium carbonate (including biogenic) minerals, reported as I/Ca, is a proxy for dissolved oxygen in seawater. Here we review the rationale behind this proxy, its recent applications and some potential future research directions.
Author: Nathan D. Sheldon
Publisher: Cambridge University Press
ISBN: 1108876811
Category : Science
Languages : en
Pages : 38
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Book Description
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.
Author: Colin Mettam
Publisher: Cambridge University Press
ISBN: 1108847560
Category : Science
Languages : en
Pages : 46
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Book Description
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.
Author: Sune G. Nielsen
Publisher: Cambridge University Press
ISBN: 110885270X
Category : Science
Languages : en
Pages : 42
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Book Description
Vanadium isotope ratios (51V/50V) have potential to provide information about changes in past ocean oxygen contents. In particular, V isotopes may find utility in tracing variations at non-zero oxygen concentrations because the redox couple that controls V elemental and isotopic abundances in seawater (vanadate-vanadyl) appears to operate around 10M O2. This characteristic sets V isotopes apart from many other metal isotope redox proxies that require more reducing conditions to register significant changes in their isotope budgets. The oxygen abundance sensitivity range of V isotopes suggests that this paleoproxy could be particularly useful in tracing marine oxygenation changes throughout the Phanerozoic and potentially beyond.
Author: Daniel D. Gregory
Publisher: Cambridge University Press
ISBN: 110884751X
Category : Science
Languages : en
Pages : 46
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Book Description
The use of the trace element content of sedimentary pyrite as a proxy for the trace element composition of past oceans has recently emerged. The pyrite proxy has several potential advantages over bulk sample analysis: preservation through metamorphism; little dilution during analysis (samples are ablated not dissolved, allowing for the less abundant elements commonly held in the sulfide fraction to be investigated as proxies); accurate measurement of several elements simultaneously; the ability to screen sediments for hydrothermal overprint; and the technique can give information regarding trace element availably at multiple stages of diagenesis. Because of these multiple strengths, the pyrite trace element proxy is a valuable potential addition to the paleo-ocean chemistry tool kit.
Author: Eva E. Stüeken
Publisher: Cambridge University Press
ISBN: 1108804438
Category : Science
Languages : en
Pages : 44
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Book Description
The attraction of selenium isotopes as a paleoenvironmental tracer lies in the high redox potential of selenium oxyanions (SeIV and SeVI), the dominant species in the modern ocean. The largest isotopic fractionations occur during oxyanion reduction, which makes selenium isotopes a sensitive proxy for the redox evolution of our planet. As a case study we review existing data from the Neoarchean and Paleoproterozoic, which show that significant isotopic fractionations are absent until 2.5 Ga, and prolonged isotopic deviations only appear around 2.3 Ga. Selenium isotopes have thus begun to reveal complex spatiotemporal redox patterns not reflected in other proxies.
Author: Rosie Chance
Publisher: Frontiers Media SA
ISBN: 2832549160
Category : Science
Languages : en
Pages : 153
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Book Description
The marine iodine cycle has remained enigmatic despite decades of research. As a redox active element that is accumulated by many marine organisms, it exists in multiple oxidation states and phases in the oceans. Abiotic, photochemical and biological processes occurring at the ocean surface, at depth, and at the sediment-water interface all drive transformations between iodine species. A recent resurgence in interest in marine iodine speciation has been driven by its importance in a diverse range of fields, from atmospheric chemistry to paleoceanography.
Author: D.A.T. Harper
Publisher: Geological Society of London Special Publications
ISBN: 1786205882
Category : Science
Languages : en
Pages : 514
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Book Description
The Ordovician was one of the longest of the geological periods, characterized by major magmatic and tectonic activity, an immense biodiversification, swings in climate and sea levels and the first Phanerozoic mass extinction. ‘A Global Synthesis of the Ordovician System’ is presented in two volumes in The Geological Society, Special Publications. This first volume (SP532) charts the history of the Ordovician System and explores significant advances in our understanding of its biostratigraphy, including more precise calibration of its timescale with tephra chronology and regional alignments using astrochronology and cyclostratigraphy. Changes in the world’s oceans, their shifting currents and sea levels, the biogeography of their biotas and the ambient climate are described and discussed against a background of changing palaeogeography. This first volume also includes syntheses of the Ordovician geology for most European countries, including historical key areas, such as Great Britain, Baltoscandia and Bohemia. The second volume (SP533) provides synthetic aspects of the Ordovician geology of most other parts of the world.
Author: Sune G. Nielsen
Publisher: Cambridge University Press
ISBN: 9781108797948
Category : Science
Languages : en
Pages : 75
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Book Description
Vanadium isotope ratios (51V/50V) have potential to provide information about changes in past ocean oxygen contents. In particular, V isotopes may find utility in tracing variations at non-zero oxygen concentrations because the redox couple that controls V elemental and isotopic abundances in seawater (vanadate-vanadyl) appears to operate around 10M O2. This characteristic sets V isotopes apart from many other metal isotope redox proxies that require more reducing conditions to register significant changes in their isotope budgets. The oxygen abundance sensitivity range of V isotopes suggests that this paleoproxy could be particularly useful in tracing marine oxygenation changes throughout the Phanerozoic and potentially beyond.
Author: K. Kobayashi
Publisher: Springer Science & Business Media
ISBN: 9784431220749
Category : Medical
Languages : en
Pages : 306
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Book Description
While a reliable supply of donated blood is vital in modern medicine, it remains the case that blood transfusion comes with its own problems, such as infectious diseases, immunological adverse reactions, and difficulties with long-term storage and transportation of blood components. With a view to solving these problems, developing a suitable blood substitute has been a major goal for decades. Artificial Oxygen Carrier: Its Front Line is a compilation of reports on the concepts behind artificial oxygen carriers, as well as the new discoveries in the field that were presented during the 13th Keio International Symposium for Life Science and Medicine. This volume describes valuable topics, including artificial red blood cells, modified haemoglobin, perfluorocarbons, and haemoglobin vesicles. It explains cutting-edge developments in artificial oxygen carrier research and will be a valuable resource to all concerned with the field.
