Massive release of hydrogen sulfide to the surface ocean and atmosphere during intervals of oceanic anoxia

Simple calculations show that if deep-water H2S concentrations increased beyond a critical threshold during oceanic anoxic intervals of Earth history, the chemocline separating sulfidic deep waters from oxygenated surface waters could have risen abruptly to the ocean surface (a chemocline upward exc...

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Bibliographic Details
Published in:Geology (Boulder) 2005-05, Vol.33 (5), p.397-400
Main Authors: Kump, Lee R, Pavlov, Alexander, Arthur, Michael A
Format: Article
Language:English
Subjects:
anaerobic environment
Atmosphere
Cenomanian
chemocline
Cretaceous
Devonian
extinction
geochemistry
Hydrogen sulfide
Lower Triassic
Marine
marine environment
Mesozoic
Oceans
paleo-oceanography
paleoatmosphere
paleoecology
Paleozoic
Permian
Permian-Triassic boundary
Phanerozoic
photochemistry
Precambrian
Proterozoic
stratigraphic boundary
Stratigraphy
Surface water
theoretical models
Triassic
Turonian
Upper Cretaceous
Upper Devonian
Upper Permian
upper Precambrian
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Summary:Simple calculations show that if deep-water H2S concentrations increased beyond a critical threshold during oceanic anoxic intervals of Earth history, the chemocline separating sulfidic deep waters from oxygenated surface waters could have risen abruptly to the ocean surface (a chemocline upward excursion). Atmospheric photochemical modeling indicates that resulting fluxes of H2S to the atmosphere (>2000 times the small modern flux from volcanoes) would likely have led to toxic levels of H2S in the atmosphere. Moreover, the ozone shield would have been destroyed, and methane levels would have risen to >100 ppm. We thus propose (1) chemocline upward excursion as a kill mechanism during the end-Permian, Late Devonian, and Cenomanian-Turonian extinctions, and (2) persistently high atmospheric H2S levels as a factor that impeded evolution of eukaryotic life on land during the Proterozoic.
ISSN:0091-7613
1943-2682
DOI:10.1130/G21295.1