Sulfate was a trace constituent of Archean seawater

Crowe, Sean A.; Paris, Guillaume; Katsev, Sergei; Jones, CarriAyne; Kim, Sang‐Tae; Zerkle, Aubrey L.; Nomosatryo, Sulung; Fowle, David A.; Adkins, Jess F.; Sessions, Alex L.; Farquhar, James; Canfield, Donald E.

doi:10.1126/science.1258966

Cited by 275 publications

(216 citation statements)

References 66 publications

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“…Bradley et al (2016) showed that sulfate reducers suppress the discrimination against heavier sulfate isotopes when sulfate concentrations in their environment fall below strain-specific concentration thresholds. A sulfate threshold of ∼200 µmol L −1 was suggested for natural communities of bacterial sulfate reducers (Habicht et al, 2002), but has recently been challenged by the report of substantial isotope fractionation between sulfate and sulfide at sulfate concentrations in the range of 5-10 µmol L −1 in the chemocline of ferruginous Lake Matano (Crowe et al, 2014). Isotope fractionation between sulfate and sulfide in natural environments may, however, also result from disproportionation processes.…”

Section: Introductionmentioning

confidence: 99%

“…Seawater sulfate levels in the Archaean Eon (before 2.5 billion years ago) are estimated to <0.01% of modern seawater, probably restricting biological productivity (Crowe et al, 2014), while estimated atmospheric methane levels were two to three orders of magnitudes higher than at present (Catling et al, 2001). As iron dominated oceanic chemistry during this time and through much of Earth's history, a coupling of AOM to iron instead of sulfate has been proposed as a globally important process on early Earth (Konhauser et al, 2005;Beal et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

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High Sulfur Isotope Fractionation Associated with Anaerobic Oxidation of Methane in a Low-Sulfate, Iron-Rich Environment

2016

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Sulfur isotope signatures provide key information for the study of microbial activity in modern systems and the evolution of the Earth surface redox system. Microbial sulfate reducers shift sulfur isotope distributions by discriminating against heavier isotopes. This discrimination is strain-specific and often suppressed at sulfate concentrations in the lower micromolar range that are typical to freshwater systems and inferred for ancient oceans. Anaerobic oxidation of methane (AOM) is a sulfate-reducing microbial process with a strong impact on global sulfur cycling in modern habitats and potentially in the geological past, but its impact on sulfur isotope signatures is poorly understood, especially in low-sulfate environments. We investigated sulfur cycling and 34 S fractionation in a low-sulfate freshwater sediment with biogeochemical conditions analogous to early Earth environments. The zone of highest AOM activity was associated in situ with a zone of strong 34 S depletions in the pool of reduced sulfur species, indicating a coupling of sulfate reduction (SR) and AOM at sulfate concentrations <50 1 µmol L − . In slurry incubations of AOM-active sediment, the addition of methane stimulated SR and induced a bulk sulfur isotope effect of ∼29 . Our results imply that sulfur isotope signatures may be strongly impacted by AOM even at sulfate concentrations two orders of magnitude lower than at present oceanic levels. Therefore, we suggest that sulfur isotope fractionation during AOM must be considered when interpreting 34 S signatures in modern and ancient environments.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High Sulfur Isotope Fractionation Associated with Anaerobic Oxidation of Methane in a Low-Sulfate, Iron-Rich Environment

2016

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“…We focus on net production to conservatively reflect the amount of O 2 that would be available to participate in reactions beyond those already consuming O 2 in modern benthic ecosystems. This metric is additionally conservative in that aerobic microbial oxidation of sulfide in modern mats is not included in net production despite generating the same weathering signals under question, and in the sulfate-poor conditions of the Archean (53,54), phototrophic/chemolithoautotrophic sulfur oxidation would have been inhibited, leading to enhanced net O 2 production (45). Despite the term "net O 2 production," no gaseous O 2 escape is necessarily implied in our model; rather we simply consider this net O 2 as being available for further reaction with nearby reductants.…”

Section: Benthic Oxygen Oases Before the Goe: Mechanistic And Numericmentioning

confidence: 99%

Benthic perspective on Earth’s oldest evidence for oxygenic photosynthesis

Lalonde

Konhauser

2015

Proc. Natl. Acad. Sci. U.S.A.

189

147

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The Great Oxidation Event (GOE) is currently viewed as a protracted process during which atmospheric oxygen increased above ∼10−5 times the present atmospheric level (PAL). This threshold represents an estimated upper limit for sulfur isotope mass-independent fractionation (S-MIF), an Archean signature of atmospheric anoxia that begins to disappear from the rock record at 2.45 Ga. However, an increasing number of papers have suggested that the timing for oxidative continental weathering, and by conventional thinking the onset of atmospheric oxygenation, was hundreds of million years earlier than previously thought despite the presence of S-MIF. We suggest that this apparent discrepancy can be resolved by the earliest oxidative-weathering reactions occurring in benthic and soil environments at profound redox disequilibrium with the atmosphere, such as biological soil crusts and freshwater microbial mats covering riverbed, lacustrine, and estuarine sediments. We calculate that oxygenic photosynthesis in these millimeter-thick ecosystems provides sufficient oxidizing equivalents to mobilize sulfate and redox-sensitive trace metals from land to the oceans while the atmosphere itself remained anoxic with its attendant S-MIF signature. As continental freeboard increased significantly between 3.0 and 2.5 Ga, the chemical and isotopic signatures of benthic oxidative weathering would have become more globally significant from a mass-balance perspective. These observations help reconcile evidence for pre-GOE oxidative weathering with the history of atmospheric chemistry, and support the plausible antiquity of a terrestrial biosphere populated by cyanobacteria well before the GOE.

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“…evaporitic sulfates and carbonate-associated sulfate (e.g., Kampschulte and Strauss, 2004), and (iv) highly variable, yet frequently negative ı 34 S values in sedimentary sulfides attributed to biological sulfur cycling, notably bacterial sulfate reduction (e.g., Strauss, 1997;Canfield, 2001). Considering respective observations and underlying systematics of sulfur isotopic fractionation (reviewed, e.g., in Canfield and Raiswell, 1999;Johnston, 2011), the sedimentary records of Archean ı 34 S sulfate and ı 34 S sulfide have been regarded as generally reflecting (i) a low-sulfate ocean (Habicht et al, 2002;Crowe et al, 2014), whereas (ii) controversial views exist with respect to an early activity of biological sulfur cycling. Notably, the absence of consistently sizeable fractionations in 34 S has been regarded as evidence for a limited importance of biological sulfur cycling in Archean sedimentary surface environments (e.g., Strauss et al, 2003), despite individual reports of highly 34 S-depleted pyrite in Paleoarchean sedimentary rocks (e.g., Ohmoto et al, 1993;Shen et al, 2001Shen et al, , 2009Philippot et al, 2007;Wu and Farquhar, 2013) and the notion from molecular biology that bacterial sulfate reduction represents an ancient metabolic pathway (Shen and Buick, 2004;Blumenberg et al, 2006;Philippot et al, 2007;Ueno et al, 2008;Shen et al, 2009;Johnston, 2011).…”

Section: Multiple Sulfur Isotope Systematics and Applications To The mentioning

confidence: 99%

Paleoarchean sulfur cycling: Multiple sulfur isotope constraints from the Barberton Greenstone Belt, South Africa

Montinaro

Strauß

Mason

et al. 2015

Precambrian Research

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a b s t r a c tMass-dependent and mass-independent sulfur isotope fractionation archived in volcanic and sedimentary rocks from the Barberton Greenstone Belt (3550-3215 Ma), South Africa, provide constraints for sulfur cycling on the early Earth. Four different sample suites were studied: komatiites and tholeiites, barite, massive and disseminated sulfide ores, and non-mineralized black shales.Variable but generally slightly positive ı 34 S values between −0.7 and +5.2‰, negative 33 S values between −0.50 and −0.09‰, and a negative correlation between ı 34 S and 33 S as well as between 33 S and 36 S for komatiites and tholeiites from the Komati Formation and from the Weltevreden Formation are outside the expected range of unfractionated juvenile sulfur. Instead, results suggest alteration of oceanic crustal rock sulfur through interactions with fluids that most likely derived their sulfur from seawater.Barite from the Mapepe Formation displays positive ı 34 S values between +3.1 and +8.1‰ and negative 33 S values between −0.77 and −0.34‰. The mass-independent sulfur isotope fractionation indicates an atmospheric sulfur source, notably photolytic sulfate, whereas the positive ı 34 S values suggest bacterial sulfate reduction of the marine sulfate reservoir.Non-mineralized black shale samples from the presumed stratigraphic equivalent of the Mapepe Formation show positive ı 34 S values between 0.0 and +1.3‰ and positive 33 S values between +0.59 and +2.45‰. These results are interpreted to result from the reduction of photolytic elemental sulfur, carrying a positive 33 S signature.Positive ı 34 S values ranging from +0.7 to +3.5‰ and slightly negative 33 S values between −0.17 and −0.12‰ characterize massive and disseminated sulfides from the Bien Venue Prospect. Results suggest unfractionated juvenile magmatic sulfur source as the primary sulfur source, but a contribution from recycled seawater sulfate, which would be indicative of submarine hydrothermal activity, cannot be ruled out.Massive and disseminated sulfides from the M'hlati prospect are distinctly different from massive and disseminated sulfide from the Bien Venue Prospect. They show negative ı 34 S values between −1.2 and −0.1‰ and positive 33 S values between +2.66 and +3.17‰, thus, displaying a sizeable mass-independent A. Montinaro et al. / Precambrian Research 267 (2015) 311-322 sulfur isotopic fractionation. Again, these samples clearly exhibit the incorporation of an atmospheric MIF-S signal. The source of sulfur for these samples has positive 33 S values, suggesting a connection with photolytic elemental sulfur. In conclusion, the sulfur isotope signatures in Paleoarchean rocks from the Barberton Greenstone Belt are diverse and indicate the incorporation of different sources of sulfur. For komatiites and tholeiites, barite and massive and possibly also disseminated sulfides from Bien Venue, multiple sulfur isotopes are related to ambient seawater sulfate and its photolytic origin, while massive and disseminated sulfides from M'hlati and non-...

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Sulfate was a trace constituent of Archean seawater

Cited by 275 publications

References 66 publications

High Sulfur Isotope Fractionation Associated with Anaerobic Oxidation of Methane in a Low-Sulfate, Iron-Rich Environment

High Sulfur Isotope Fractionation Associated with Anaerobic Oxidation of Methane in a Low-Sulfate, Iron-Rich Environment

Benthic perspective on Earth’s oldest evidence for oxygenic photosynthesis

Paleoarchean sulfur cycling: Multiple sulfur isotope constraints from the Barberton Greenstone Belt, South Africa

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