Search Results - "Anbar, A. D."

Tracing the stepwise oxygenation of the Proterozoic ocean by Scott, C, Lyons, T. W, Bekker, A, Shen, Y, Poulton, S. W, Chu, X, Anbar, A. D

“…Biogeochemical signatures preserved in ancient sedimentary rocks provide clues to the nature and timing of the oxygenation of the Earth's atmosphere…”
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Oceanic oxygenation events in the anoxic Ediacaran ocean by Sahoo, S. K., Planavsky, N. J., Jiang, G., Kendall, B., Owens, J. D., Wang, X., Shi, X., Anbar, A. D., Lyons, T. W.

“…The ocean‐atmosphere system is typically envisioned to have gone through a unidirectional oxygenation with significant oxygen increases in the earliest (ca…”
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Proterozoic Ocean Chemistry and Evolution: A Bioinorganic Bridge? by Anbar, A. D., Knoll, A. H.

“…Recent data imply that for much of the Proterozoic Eon (2500 to 543 million years ago), Earth's oceans were moderately oxic at the surface and sulfidic at…”
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Molybdenum isotope evidence for widespread anoxia in mid-Proterozoic oceans by ARNOLD, G. L, ANBAR, A. D, BARLING, J, LYONS, T. W

“…How much dissolved oxygen was present in the mid-Proterozoic oceans between 1.8 and 1.0 billion years ago is debated vigorously. One model argues for…”
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Coevolution of metal availability and nitrogen assimilation in cyanobacteria and algae by GLASS, J.B, WOLFE-SIMON, F, ANBAR, A.D

“…Marine primary producers adapted over eons to the changing chemistry of the oceans. Because a number of metalloenzymes are necessary for N assimilation,…”
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Molybdenum isotope fractionation during adsorption by manganese oxides by Barling, J., Anbar, A.D.

“…The isotopic composition of Mo ( delta super(97/95)Mo) in seawater is ~2ppm heavier than Mo in marine ferromanganese crusts and nodules [Barling et al. Earth…”
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Predicting multiple myeloma disease activity by analyzing natural calcium isotopic composition by Gordon, G W, Monge, J, Channon, M B, Wu, Q, Skulan, J L, Anbar, A D, Fonseca, R

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Fe Isotope Variations in Natural Materials Measured Using High Mass Resolution Multiple Collector ICPMS by Arnold, G. L, Weyer, S, Anbar, A. D

“…We present the first measurements of Fe isotope variations in chemically purified natural samples using high mass resolution multiple-collector inductively…”
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A late methanogen origin for molybdenum-dependent nitrogenase by BOYD, E. S., ANBAR, A. D., MILLER, S., HAMILTON, T. L., LAVIN, M., PETERS, J. W.

“…Mounting evidence indicates the presence of a near complete biological nitrogen cycle in redox‐stratified oceans during the late Archean to early Proterozoic…”
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Iron stable isotopes: beyond biosignatures by Anbar, A.D.

“…The stable isotope geochemistry of Fe has attracted intense interest in the past five years. This interest was originally motivated by the possible use of Fe…”
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Nonbiological Fractionation of Iron Isotopes by Anbar, A. D., Roe, J. E., Barling, J., Nealson, K. H.

“…Laboratory experiments demonstrate that iron isotopes can be chemically fractionated in the absence of biology. Isotopic variations comparable to those seen…”
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Precise Determination of Mass-Dependent Variations in the Isotopic Composition of Molybdenum Using MC-ICPMS by Anbar, A. D, Knab, K. A, Barling, J

“…We present an analytical approach for the precise determination of mass-dependent differences in the isotopic composition of Mo between samples and reference…”
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A Coevolutionary Tale by Anbar, A. D.

“…Writing for nonspecialists, Hazen presents the geological and biological history of our planet from the perspective of his "mineral evolution" hypothesis…”
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Iron isotopes in hot springs along the Juan de Fuca Ridge by Sharma, M., Polizzotto, M., Anbar, A.D.

“…We present Fe isotope data for high temperature hydrothermal fluids, sulfides, and basalts from the Juan de Fuca Ridge, USGS basalt standard BCR-2 and the…”
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Ordinary stoichiometry of extraordinary microorganisms by Neveu, M., Poret-Peterson, A. T., Anbar, A. D., Elser, J. J.

“…All life on Earth seems to be made of the same chemical elements in relatively conserved proportions (stoichiometry). Whether this stoichiometry is conserved…”
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238U/235U Variations in Meteorites: Extant 247Cm and Implications for Pb-Pb Dating by BRENNECKA, G. A, WEYER, S, WADHWA, M, JANNEY, P. E, ZIPFET, J, ANBAR, A. D

“…The 238U/235U isotope ratio has long been considered invariant in meteoritic materials (equal to 137.88). This assumption is a cornerstone of the…”
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Iridium in Natural Waters by Anbar, A. D., Wasserburg, G. J., Papanastassiou, D. A., Andersson, P. S.

“…Iridium, commonly used as a tracer of extraterrestrial material, was measured in rivers, oceans, and an estuarine environment. The concentration of iridium in…”
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Natural mass-dependent variations in the isotopic composition of molybdenum by Barling, J, Arnold, G.L, Anbar, A.D

“…We present the first observations of natural mass-dependent fractionation of the isotopic composition of molybdenum (Mo), using multi-collector inductively…”
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Determination of Iridium in Natural Waters by Clean Chemical Extraction and Negative Thermal Ionization Mass Spectrometry by Anbar, A. D, Papanastassiou, D. A, Wasserburg, G. J

“…Methods for the precise, routine measurement of Ir in seawater, riverwater, and estuarine water using isotope dilution negative thermal ionization mass…”
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Methyl bromide: ocean sources, ocean sinks, and climate sensitivity by Anbar, A D, Yung, Y L, Chavez, F P

“…The oceans play an important role in the geochemical cycle of methyl bromide (CH3Br), the major carrier of O3-destroying bromine to the stratosphere. The…”
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