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Proterozoic ocean redox and biogeochemical stasis.
Proc Natl Acad Sci U S A. 2013 Apr 02; 110(14):5357-62.PN

Abstract

The partial pressure of oxygen in Earth's atmosphere has increased dramatically through time, and this increase is thought to have occurred in two rapid steps at both ends of the Proterozoic Eon (∼2.5-0.543 Ga). However, the trajectory and mechanisms of Earth's oxygenation are still poorly constrained, and little is known regarding attendant changes in ocean ventilation and seafloor redox. We have a particularly poor understanding of ocean chemistry during the mid-Proterozoic (∼1.8-0.8 Ga). Given the coupling between redox-sensitive trace element cycles and planktonic productivity, various models for mid-Proterozoic ocean chemistry imply different effects on the biogeochemical cycling of major and trace nutrients, with potential ecological constraints on emerging eukaryotic life. Here, we exploit the differing redox behavior of molybdenum and chromium to provide constraints on seafloor redox evolution by coupling a large database of sedimentary metal enrichments to a mass balance model that includes spatially variant metal burial rates. We find that the metal enrichment record implies a Proterozoic deep ocean characterized by pervasive anoxia relative to the Phanerozoic (at least ∼30-40% of modern seafloor area) but a relatively small extent of euxinic (anoxic and sulfidic) seafloor (less than ∼1-10% of modern seafloor area). Our model suggests that the oceanic Mo reservoir is extremely sensitive to perturbations in the extent of sulfidic seafloor and that the record of Mo and chromium enrichments through time is consistent with the possibility of a Mo-N colimited marine biosphere during many periods of Earth's history.

Authors+Show Affiliations

Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA. reinhard@caltech.eduNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Historical Article
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

23515332

Citation

Reinhard, Christopher T., et al. "Proterozoic Ocean Redox and Biogeochemical Stasis." Proceedings of the National Academy of Sciences of the United States of America, vol. 110, no. 14, 2013, pp. 5357-62.
Reinhard CT, Planavsky NJ, Robbins LJ, et al. Proterozoic ocean redox and biogeochemical stasis. Proc Natl Acad Sci U S A. 2013;110(14):5357-62.
Reinhard, C. T., Planavsky, N. J., Robbins, L. J., Partin, C. A., Gill, B. C., Lalonde, S. V., Bekker, A., Konhauser, K. O., & Lyons, T. W. (2013). Proterozoic ocean redox and biogeochemical stasis. Proceedings of the National Academy of Sciences of the United States of America, 110(14), 5357-62. https://doi.org/10.1073/pnas.1208622110
Reinhard CT, et al. Proterozoic Ocean Redox and Biogeochemical Stasis. Proc Natl Acad Sci U S A. 2013 Apr 2;110(14):5357-62. PubMed PMID: 23515332.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Proterozoic ocean redox and biogeochemical stasis. AU - Reinhard,Christopher T, AU - Planavsky,Noah J, AU - Robbins,Leslie J, AU - Partin,Camille A, AU - Gill,Benjamin C, AU - Lalonde,Stefan V, AU - Bekker,Andrey, AU - Konhauser,Kurt O, AU - Lyons,Timothy W, Y1 - 2013/03/20/ PY - 2013/3/22/entrez PY - 2013/3/22/pubmed PY - 2013/6/12/medline SP - 5357 EP - 62 JF - Proceedings of the National Academy of Sciences of the United States of America JO - Proc Natl Acad Sci U S A VL - 110 IS - 14 N2 - The partial pressure of oxygen in Earth's atmosphere has increased dramatically through time, and this increase is thought to have occurred in two rapid steps at both ends of the Proterozoic Eon (∼2.5-0.543 Ga). However, the trajectory and mechanisms of Earth's oxygenation are still poorly constrained, and little is known regarding attendant changes in ocean ventilation and seafloor redox. We have a particularly poor understanding of ocean chemistry during the mid-Proterozoic (∼1.8-0.8 Ga). Given the coupling between redox-sensitive trace element cycles and planktonic productivity, various models for mid-Proterozoic ocean chemistry imply different effects on the biogeochemical cycling of major and trace nutrients, with potential ecological constraints on emerging eukaryotic life. Here, we exploit the differing redox behavior of molybdenum and chromium to provide constraints on seafloor redox evolution by coupling a large database of sedimentary metal enrichments to a mass balance model that includes spatially variant metal burial rates. We find that the metal enrichment record implies a Proterozoic deep ocean characterized by pervasive anoxia relative to the Phanerozoic (at least ∼30-40% of modern seafloor area) but a relatively small extent of euxinic (anoxic and sulfidic) seafloor (less than ∼1-10% of modern seafloor area). Our model suggests that the oceanic Mo reservoir is extremely sensitive to perturbations in the extent of sulfidic seafloor and that the record of Mo and chromium enrichments through time is consistent with the possibility of a Mo-N colimited marine biosphere during many periods of Earth's history. SN - 1091-6490 UR - https://www.unboundmedicine.com/medline/citation/23515332/Proterozoic_ocean_redox_and_biogeochemical_stasis_ L2 - http://www.pnas.org/cgi/pmidlookup?view=long&pmid=23515332 DB - PRIME DP - Unbound Medicine ER -