气候变化领域集成服务门户(CCPortal): Proterozoic seawater sulfate scarcity and the evolution of ocean

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DOI	10.1038/s41561-019-0351-5
	Proterozoic seawater sulfate scarcity and the evolution of ocean–atmosphere chemistry
	Fakhraee M.; Hancisse O.; Canfield D.E.; Crowe S.A.; Katsev S.
发表日期	2019
ISSN	17520894
卷号	12 期号:5
英文摘要	Oceanic sulfate concentrations are widely thought to have reached millimolar levels during the Proterozoic Eon, 2.5 to 0.54 billion years ago. Yet the magnitude of the increase in seawater sulfate concentrations over the course of the Eon remains largely unquantified. A rise in seawater sulfate concentrations has been inferred from the increased range of marine sulfide δ34S values following the Great Oxidation Event and was induced by two processes: enhanced oxidative weathering of sulfides on land, and the onset of marine sulfur redox cycling. Here we use mass balance and diagenetic reaction-transport models to reconstruct the sulfate concentrations in Proterozoic seawater. We find that sulfate concentrations remained below 400 µM, and were possibly as low as 100 µM, throughout much of the Proterozoic. At these low sulfate concentrations, relatively large sulfate–pyrite sulfur isotope differences cannot be explained by sulfate reduction alone and are only possible through oxidative sediment sulfur cycling. This requires oxygen concentrations of at least 10 µM in shallow Proterozoic seawater, which translates to 1–10% of present atmospheric oxygen concentrations. At these oxygen and sulfate concentrations, the oceans would have been a substantial source of methane to the atmosphere (60–140 Tmol yr−1). This methane would have accumulated to high concentrations (more than 25 ppmv) and supported greenhouse warming during much of the Proterozoic Eon, with notable exceptions during the Palaeoproterozoic and Neoproterozoic eras. © 2019, The Author(s), under exclusive licence to Springer Nature Limited.
语种	英语
scopus关键词	atmosphere-ocean coupling; concentration (composition); oxidation; Proterozoic; reactive transport; reconstruction; redox conditions; seawater; sulfate; weathering
来源期刊	Nature Geoscience
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/124671
作者单位	Large Lakes Observatory, University of Minnesota Duluth, Duluth, MN, United States; Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, BC, Canada; Department of Microbiology and Immunology and Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, BC, Canada; Nordic Center for Earth Evolution and Institute of Biology, University of Southern Denmark, Odense, Denmark; Department of Physics and Astronomy, University of Minnesota Duluth, Duluth, MN, United States
推荐引用方式 GB/T 7714	Fakhraee M.,Hancisse O.,Canfield D.E.,等. Proterozoic seawater sulfate scarcity and the evolution of ocean–atmosphere chemistry[J],2019,12(5).
APA	Fakhraee M.,Hancisse O.,Canfield D.E.,Crowe S.A.,&Katsev S..(2019).Proterozoic seawater sulfate scarcity and the evolution of ocean–atmosphere chemistry.Nature Geoscience,12(5).
MLA	Fakhraee M.,et al."Proterozoic seawater sulfate scarcity and the evolution of ocean–atmosphere chemistry".Nature Geoscience 12.5(2019).