Sulfate-Reducing Bacteria: Principal Methylators of Mercury in Anoxic Estuarine Sediment

Compeau, Geoffrey C.; Bartha, Richárd

doi:10.1128/aem.50.2.498-502.1985

Cited by 1,059 publications

(537 citation statements)

References 19 publications

(13 reference statements)

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“…The shallower active layer at the northern valley side (L2 to L4) suggests wetter soils compared to the southern valley side (L1, A2 and A3, Table 3). This is supported by the hydrogen sulphide smell of the cores L2 to L4, indicating the presence of sulphate-reducing bacteria (Rivkina et al 1998;Gilichinsky et al 2003), which are common in saturated soils (Compeau & Bartha 1985;Hansen et al 2007). The low sulphate PIC and high chloride-sulphate ratios with depth reflect consistent saturated conditions during late Holocene permafrost aggradation (Fig.…”

Section: Local Factors Controlling Ground-ice Formationmentioning

confidence: 95%

Holocene permafrost history and cryostratigraphy in the High‐Arctic Adventdalen Valley, central Svalbard

Cable

Elberling

Kroon

2017

Boreas

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This paper presents the history and cryostratigraphy of the upper permafrost in the High‐Arctic Adventdalen Valley, central Svalbard. Nineteen frozen sediment cores, up to 10.7 m long, obtained at five periglacial landforms, were analysed for cryostructures, ice, carbon and solute contents, and grain‐size distribution, and were 14C‐ and OSL‐dated. Spatial variability in ice and carbon contents is closely related to the sedimentary history and mode of permafrost aggradation. In the valley bottom, saline epigenetic permafrost with pore ice down to depths of 10.7 m depth formed in deltaic sediments since the mid‐Holocene; cryopegs were encountered below 6 m. In the top 1 to 5 m, syngenetic and quasi‐syngenetic permafrost with microlenticular, lenticular, suspended and organic‐matrix cryostructures developed due to loess and alluvial sedimentation since the colder late Holocene, which resulted in the burial of organic material. At the transition between deltaic sediments and loess, massive ice bodies occurred. A pingo developed where the deltaic sediments reached the surface. On hillslopes, suspended cryostructure on solifluction sheets indicates quasi‐syngenetic permafrost aggradation; lobes, in contrast, were ice‐poor. Suspended cryostructure in eluvial deposits reflects epigenetic or quasi‐syngenetic permafrost formation on a weathered bedrock plateau. Landform‐scale spatial variations in ground ice and carbon relate to variations in slope, sedimentation rate, moisture conditions and stratigraphy. Although the study reveals close links between Holocene landscape evolution and permafrost history, our results emphasize a large uncertainty in using terrain surface indicators to infer ground‐ice contents and upscale from core to landform scale in mountainous permafrost landscapes.

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Section: Local Factors Controlling Ground-ice Formationmentioning

confidence: 95%

Holocene permafrost history and cryostratigraphy in the High‐Arctic Adventdalen Valley, central Svalbard

Cable

Elberling

Kroon

2017

Boreas

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“…Chem. 28, 2009 1569 Selenium-aided demethylation of MeHg Methylation of inorganic Hg to MeHg is generally thought to be a microbial process mediated primarily by sulfate-reducing bacteria [77,78]. No conclusive evidence exists that Hg methylation occurs in vivo in animals.…”

Section: Mercury-selenium Antagonismmentioning

confidence: 99%

Mercury‐selenium compounds and their toxicological significance: Toward a molecular understanding of the mercury‐selenium antagonism

Khan

Wang

2009

Enviro Toxic and Chemistry

401

294

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The interaction between mercury (Hg) and selenium (Se) is one of the best known examples of biological antagonism, yet the underlying mechanism remains unclear. This review focuses on the possible pathways leading to the Hg-Se antagonism, with an emphasis on the potential Hg-Se compounds that are responsible for the antagonism at the molecular level (i.e., bis[methylmercuric]selenide, methylmercury selenocysteinate, selenoprotein P-bound HgSe clusters, and the biominerals HgSe(x)S(1-x)). The presence of these compounds in biological systems has been suggested by direct or indirect evidence, and their chemical properties support their potentially key roles in alleviating the toxicity of Hg and Se (at high Hg and Se exposures, respectively) and deficiency of Se (at low Se exposures). Direct analytical evidences are needed, however, to confirm their in vivo presence and metabolic pathways, as well as to identify the roles of other potential Hg-Se compounds. Further studies are also warranted for the determination of thermodynamic properties of these compounds under physiological conditions toward a better understanding of the Hg-Se antagonism in biota, particularly under real world exposure scenarios.

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“…In the seepage lake example described above, biotic methylation appeared to produce almost all of the methylmercury. Sulfate-reducing bacteria appear to be important mediators of the methylation process [60,61,64]. Direct evidence for sulfate reduction linked to methylation of mercury came from estuarine studies using specific metabolic inhibitors [HI.…”

Section: Methylationmentioning

confidence: 99%

Mercury Cycling and Effects in Freshwater Wetland Ecosystems

Zillioux¹,

Porcella²,

Benoit³

1993

Environ Toxicol Chem

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This literature review borrows from diverse fields because of the paucity of freshwater wetland studies on mercury cycling and effects. Peat cores provide an excellent means of dating mercury deposition temporal patterns. Conclusions about cycling suggest that a biogeochemical model would prove useful for evaluating wetland processes of mercury transformation and accumulation. Mercury methylation and the association of mercury with organic matter require additional research. Wetlands trap and release mercury, and its association with organic matter seems to affect the release rate. At high exposure, usually associated with laboratory studies or waste discharges, a variety of biotic toxic responses are observed. Predator species accumulate mercury predictably, and residue-effect relationships seem useful for an index of ecologic damage. More definitive conclusions require additional research to define the ecosystem properties that affect mercury transfer to wetland predators. 5-30 22"-76" ~ ~ aEstimated by assuming net of leaching vs. uptake from deeper levels is zero and peat production rate is 0.4 kg/m2/yr [56,10,55].

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Sulfate-Reducing Bacteria: Principal Methylators of Mercury in Anoxic Estuarine Sediment

Cited by 1,059 publications

References 19 publications

Holocene permafrost history and cryostratigraphy in the High‐Arctic Adventdalen Valley, central Svalbard

Holocene permafrost history and cryostratigraphy in the High‐Arctic Adventdalen Valley, central Svalbard

Mercury‐selenium compounds and their toxicological significance: Toward a molecular understanding of the mercury‐selenium antagonism

Mercury Cycling and Effects in Freshwater Wetland Ecosystems

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