Sulfur Cycling and Methane Oxidation

Jørgensen, Bo Barker; Kasten, Sabine

doi:10.1007/3-540-32144-6_8

Cited by 236 publications

(252 citation statements)

References 177 publications

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“…Specifically, the modeling predicts elevated pyrite contents that are limited to the sulfidic zone, coinciding with a strong decrease in magnetic susceptibility . Similar observations are also reported for other iron-dominated areas such as the Amazon Fan (Jørgensen and Kasten, 2006), Zambesi Fan (März et al, 2008) or cold-seep systems off southwestern Taiwan (Hsu et al, 2014).…”

Section: Pyrite Formation At the Center Of The Sulfidic Zonesupporting

confidence: 86%

Sulfur Cycling in an Iron Oxide-Dominated, Dynamic Marine Depositional System: The Argentine Continental Margin

Riedinger

Brunner

Krastel³

et al. 2017

Front. Earth Sci.

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The interplay between sediment deposition patterns, organic matter type and the quantity and quality of reactive mineral phases determines the accumulation, speciation, and isotope composition of pore water and solid phase sulfur constituents in marine sediments. Here, we present the sulfur geochemistry of siliciclastic sediments from two sites along the Argentine continental slope-a system characterized by dynamic deposition and reworking, which result in non-steady state conditions. The two investigated sites have different depositional histories but have in common that reactive iron phases are abundant and that organic matter is refractory-conditions that result in low organoclastic sulfate reduction rates (SRR). Deposition of reworked, isotopically light pyrite and sulfurized organic matter appear to be important contributors to the sulfur inventory, with only minor addition of pyrite from organoclastic sulfate reduction above the sulfate-methane transition (SMT). Pore-water sulfide is limited to a narrow zone at the SMT. The core of that zone is dominated by pyrite accumulation. Iron monosulfide and elemental sulfur accumulate above and below this zone. Iron monosulfide precipitation is driven by the reaction of low amounts of hydrogen sulfide with ferrous iron and is in competition with the oxidation of sulfide by iron (oxyhydr)oxides to form elemental sulfur. The intervals marked by precipitation of intermediate sulfur phases at the margin of the zone with free sulfide are bordered by two distinct peaks in total organic sulfur (TOS).Organic matter sulfurization appears to precede pyrite formation in the iron-dominated margins of the sulfide zone, potentially linked to the presence of polysulfides formed by reaction between dissolved sulfide and elemental sulfur. Thus, SMTs can be hotspots for organic matter sulfurization in sulfide-limited, reactive iron-rich marine sedimentary systems. Furthermore, existence of elemental sulfur and iron monosulfide phases meters below the SMT demonstrates that in sulfide-limited systems metastable sulfur constituents are not readily converted to pyrite but can be buried to deeper Riedinger et al.Non-steady State Subsurface Sulfur Cycling sediment depths. Our data show that in non-steady state systems, redox zones do not occur in sequence but can reappear or proceed in inverse sequence throughout the sediment column, causing similar mineral alteration processes to occur at the same time at different sediment depths.

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Section: Pyrite Formation At the Center Of The Sulfidic Zonesupporting

confidence: 86%

Sulfur Cycling in an Iron Oxide-Dominated, Dynamic Marine Depositional System: The Argentine Continental Margin

Riedinger

Brunner

Krastel³

et al. 2017

Front. Earth Sci.

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“…In general, aerobic metabolism dominates the organic matter mineralization in deep-sea sediments that are characterized by low organic matter content (Jahnke et al, 1982;Glud, 2008), especially in organic-carbon-starved deep-sea sediments with low sedimentation rates (Mewes et al, 2014D'Hondt et al, 2015;Mogollón et al, 2016). In contrast, owing to high sulfate concentrations in marine sediment, sulfate reduction might account for up to 50 % of total carbon oxidation in continental margins with high organic matter flux (Jørgensen, 1982;Jørgensen and Kasten, 2006;Bowles et al, 2014). However, in sediments where manganese and iron oxides are abundant or rapidly recycled, microbial reduction of manganese and iron can be the dominant electron-accepting processes over sulfate reduction (Sørensen and Jørgensen, 1987;Aller, 1990;Canfield et al, 1993b).…”

mentioning

confidence: 99%

Manganese and iron reduction dominate organic carbon oxidation in surface sediments of the deep Ulleung Basin, East Sea

et al. 2017

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Abstract. Rates and pathways of benthic organic carbon (C org ) oxidation were investigated in surface sediments of the Ulleung Basin (UB) characterized by high C org contents (> 2.5 %, dry wt.) and very high contents of Mn oxides (> 200 µmol cm −3 ) and Fe oxides (up to 100 µmol cm −3 ). The combination of geochemical analyses and independently executed metabolic rate measurements revealed that Mn and Fe reduction were the dominant C org oxidation pathways in the center of the UB, comprising 45 and 20 % of total C org oxidation, respectively. By contrast, sulfate reduction was the dominant C org oxidation pathway, accounting for 50 % of total C org mineralization in sediments of the continental slope. The relative significance of each C org oxidation pathway matched the depth distribution of the respective electron acceptors. The relative importance of Mn reduction for C org oxidation displays saturation kinetics with respect to Mn oxide content with a low half-saturation value of 8.6 µmol cm −3 , which further implies that Mn reduction can be a dominant C org oxidation process even in sediments with lower MnO 2 content as known from several other locations. This is the first report of a high contribution of manganese reduction to C org oxidation in offshore sediments on the Asian margin. The high manganese oxide content in the surface sediment in the central UB was maintained by an extreme degree of recycling, with each Mn atom on average being reoxidized ∼ 3800 times before permanent burial. This is the highest degree of recycling so far reported for Mn-rich sediments, and it appears linked to the high benthic mineralization rates resulting from the high C org content that indicate the UB as a biogeochemical hotspot for turnover of organic matter and nutrient regeneration.

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“…Co-existence of methanogenesis and sulfate reduction is not normally observed because sulfate reduction is more energetically favorable than methanogenesis, and sulfate reducers should outcompete methanogens for common substrates such as hydrogen and acetate (Oremland and Polcin, 1982;Jørgensen and Kasten, 2006). Moreover, anaerobic oxidation of methane (AOM) coupled with sulfate reduction at the base of the sulfate reducing zone should further deplete methane (Capone and Kiene, 1988;Valentine and Reeburgh, 2000).…”

Section: Co-existence Of Methane and Sulfate In Sedimentsmentioning

confidence: 99%

Methane and sulfate dynamics in sediments from mangrove-dominated tropical coastal lagoons, Yucatán, Mexico

et al. 2016

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Abstract. Porewater profiles in sediment cores from mangrove-dominated coastal lagoons (Celestún and Chelem) on the Yucatán Peninsula, Mexico, reveal the widespread coexistence of dissolved methane and sulfate. This observation is interesting since dissolved methane in porewaters is typically oxidized anaerobically by sulfate. To explain the observations we used a numerical transport-reaction model that was constrained by the field observations. The model suggests that methane in the upper sediments is produced in the sulfate reduction zone at rates ranging between 0.012 and 31 mmol m −2 d −1 , concurrent with sulfate reduction rates between 1.1 and 24 mmol SO 2− 4 m −2 d −1 . These processes are supported by high organic matter content in the sediment and the use of non-competitive substrates by methanogenic microorganisms. Indeed sediment slurry incubation experiments show that non-competitive substrates such as trimethylamine (TMA) and methanol can be utilized for microbial methanogenesis at the study sites. The model also indicates that a significant fraction of methane is transported to the sulfate reduction zone from deeper zones within the sedimentary column by rising bubbles and gas dissolution. The shallow depths of methane production and the fast rising methane gas bubbles reduce the likelihood for oxidation, thereby allowing a large fraction of the methane formed in the sediments to escape to the overlying water column.

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Sulfur Cycling and Methane Oxidation

Cited by 236 publications

References 177 publications

Sulfur Cycling in an Iron Oxide-Dominated, Dynamic Marine Depositional System: The Argentine Continental Margin

Sulfur Cycling in an Iron Oxide-Dominated, Dynamic Marine Depositional System: The Argentine Continental Margin

Manganese and iron reduction dominate organic carbon oxidation in surface sediments of the deep Ulleung Basin, East Sea

Methane and sulfate dynamics in sediments from mangrove-dominated tropical coastal lagoons, Yucatán, Mexico

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