title: Calibration of sulfate levels in the archean ocean.
abstract: The size of the marine sulfate reservoir has grown through Earth's history, reflecting the accumulation of oxygen into the atmosphere. Sulfur isotope fractionation experiments on marine and freshwater sulfate reducers, together with the isotope record, imply that oceanic Archean sulfate concentrations were <200 microM, which is less than one-hundredth of present marine sulfate levels and one-fifth of what was previously thought. Such low sulfate concentrations were maintained by volcanic outgassing of SO2 gas, and severely suppressed sulfate reduction rates allowed for a carbon cycle dominated by methanogenesis.
authors.affiliation: Danish Center for Earth System Science and Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230, Odense M, Denmark.
authors.forename: Kirsten S
authors.initials: KS
authors.lastname: Habicht
authors.forename: Michael
authors.initials: M
authors.lastname: Gade
authors.forename: Bo
authors.initials: B
authors.lastname: Thamdrup
authors.forename: Peter
authors.initials: P
authors.lastname: Berg
authors.forename: Donald E
authors.initials: DE
authors.lastname: Canfield
mesh_terms: D000693:Anaerobiosis; D019611:Archaeoglobus fulgidus / Q000254:growth & development / Q000378:metabolism*; D001419:Bacteria / Q000254:growth & development / Q000378:metabolism*; D005618:Fresh Water / Q000737:chemistry / Q000382:microbiology; D019015:Geologic Sediments / Q000737:chemistry* / Q000382:microbiology; D007501:Iron / Q000032:analysis; D008697:Methane / Q000378:metabolism; D009792:Oceans and Seas; D010084:Oxidation-Reduction; D010100:Oxygen / Q000032:analysis; D012623:Seawater / Q000737:chemistry* / Q000382:microbiology; D013431:Sulfates / Q000032:analysis* / Q000378:metabolism; D013440:Sulfides / Q000032:analysis / Q000378:metabolism; D013995:Time
chemical_list: D013431:Sulfates; D013440:Sulfides; C011342:pyrite; D007501:Iron; D008697:Methane; D010100:Oxygen