Mercury Methylation by Dissimilatory Iron-Reducing Bacteria

Kerin, E.; Gilmour, Cynthia C.; Roden, Eric E.; Suzuki, Marcelino T.; Coates, John D.; Mason, Robert P.

doi:10.1128/aem.01602-06

Cited by 452 publications

(304 citation statements)

References 26 publications

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“…There are several possible environmental sources of MeHg, but few studies have measured production rates from these various sources in Arctic environments, especially in marine settings. In temperate marine and fresh water environments, wetlands and benthic sediments are major MeHg sources and this is thought to be due to the activity of sulfate-and iron-reducing bacteria [140][141][142] and methanogens [143] in these anoxic environments. MeHg can also be produced during detrital remineralisation in oxic marine waters, associated with mid-depth nutrient maxima and oxygen utilisation.…”

Section: Controls On Arctic Food Chain Mercury Accumulation By Methylmentioning

confidence: 99%

The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review

Douglas

Loseto²,

Macdonald³

et al. 2012

Environ. Chem.

119

147

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Environmental context. Mercury, in its methylated form, is a neurotoxin that biomagnifies in marine and terrestrial foodwebs leading to elevated levels in fish and fish-eating mammals worldwide, including at numerous Arctic locations. Elevated mercury concentrations in Arctic country foods present a significant exposure risk to Arctic people. We present a detailed review of the fate of mercury in Arctic terrestrial and marine ecosystems, taking into account the extreme seasonality of Arctic ecosystems and the unique processes associated with sea ice and Arctic hydrology.Abstract. This review is the result of a series of multidisciplinary meetings organised by the Arctic Monitoring and Assessment Programme as part of their 2011 Assessment 'Mercury in the Arctic'. This paper presents the state-of-the-art knowledge on the environmental fate of mercury following its entry into the Arctic by oceanic, atmospheric and terrestrial pathways. Our focus is on the movement, transformation and bioaccumulation of Hg in aquatic (marine and fresh water) and terrestrial ecosystems. The processes most relevant to biological Hg uptake and the potential risk associated with Hg exposure in wildlife are emphasised. We present discussions of the chemical transformations of newly deposited or transported Hg in marine, fresh water and terrestrial environments and of the movement of Hg from air, soil and water environmental compartments into food webs. Methylation, a key process controlling the fate of Hg in most ecosystems, and the role of trophic processes in controlling Hg in higher order animals are also included. Case studies on Eastern Beaufort Sea beluga (Delphinapterus leucas) and landlocked Arctic char (Salvelinus alpinus) are presented as examples of the relationship between ecosystem trophic processes and biologic Hg levels. We examine whether atmospheric mercury depletion events (AMDEs) contribute to increased Hg levels in Arctic biota and provide information on the links between organic carbon and Hg speciation, dynamics and bioavailability. Long-term sequestration of Hg into non-biological archives is also addressed. The review concludes by identifying major knowledge gaps in our understanding, including:(1) the rates of Hg entry into marine and terrestrial ecosystems and the rates of inorganic and MeHg uptake by Arctic microbial and algal communities; (2) the bioavailable fraction of AMDE-related Hg and its rate of accumulation by biota and (3) the fresh water and marine MeHg cycle in the Arctic, especially the marine MeHg cycle.

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Section: Controls On Arctic Food Chain Mercury Accumulation By Methylmentioning

confidence: 99%

The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review

Douglas

Loseto²,

Macdonald³

et al. 2012

Environ. Chem.

119

147

View full text Add to dashboard Cite

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“…Methylation of Hg(II) in soils and surface-water was found to be carried out under anoxic conditions by dissimilatory sulfate-reducing bacteria (DSRBs) (Gilmour et al, 1992). Dissimilatory iron-reducing bacteria (DIRBs) later were found to be able to methylate Hg(II) as well (e.g., Kerin et al, 2006). Populations of both DSRBs and DIRBs have been found to coexist in stream-bottom sediments where fine-grained sediments were "potential hot spots for both methylation and demethylation activities" (Yu et al, 2012).…”

Section: Microbial Transformationsmentioning

confidence: 99%

Occurrence and Mobility of Mercury in Groundwater

Barringer¹,

Szabó²,

Reilly³

2013

Current Perspectives in Contaminant Hydrology and Water Resources Sustainability

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“…Although methylation can occur abiotically, most of the MeHg present in ecosystems is formed in the environment via microbial processes. Several species of sulfate reducing bacteria [18], iron reducing bacteria [19] and methanogens [20] are known to methylate Hg, though other microbes including aerobic ones may also be capable of this conversion [21]. The fact that MeHg, the key chemical species responsible for environmental Hg problems, is formed in situ in the environment after the deposition of inorganic Hg, instead of directly from anthropogenic emissions, poses a major challenge in controlling its levels in the ecosystem.…”

Section: Sensitivity Of Hg Biogeochemical Cycles To Environmental Changementioning

confidence: 99%

“…Reservoirs, particularly recently flooded reservoirs, are known areas of rapid Hg methylation and thus act as MeHg sources for bioaccumulation in aquatic food web [46]. This is due to the influx of "fresh" organic carbon at the oxic-anoxic transition zone which promotes the activities of Hg methylating bacteria [18,19]. While this has been extensively demonstrated in North America, it is not unusual to see very low levels of Hg in freshwater fishes in many reservoirs in China, even in most contaminated regions [47].…”

Section: Implications For the Three Gorges Reservoirmentioning

confidence: 99%

Mercury contamination in aquatic ecosystems under a changing environment: Implications for the Three Gorges Reservoir

Wang

Zhang

2012

Chin. Sci. Bull.

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Mercury is one of the primary contaminants of global concern. As anthropogenic emissions of mercury are gradually placed under control, evidence is emerging that biotic mercury levels in many aquatic ecosystems are increasingly driven by internal biogeochemical processes, especially in ecosystems that have been undergoing dramatic environmental changes. Here we review the unique properties of mercury that are responsible for the exceptional sensitivity of its biogeochemical cycles to changes in climatic, geochemical, biological and ecological processes. We show that, due to rapid climate warming, a shift from sources-driven to processes-driven mercury bioaccumulation is already happening in the Arctic marine ecosystem. We further suggest that such a shift might also be operating in the Three Gorges Reservoir due to changes in these biogeochemical processes induced by the damming. As a result, the effectiveness of mercury emission control is expected to be followed by long delays before ensuing reduction is seen in food-web levels, making it all the more pressing to control and reduce mercury emissions to the reservoir. Long-term monitoring and targeted studies are urgently needed to understand how biotic mercury levels in the reservoir are responding to changes in mercury emissions and in biogeochemical processes.

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Mercury Methylation by Dissimilatory Iron-Reducing Bacteria

Cited by 452 publications

References 26 publications

The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review

The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review

Occurrence and Mobility of Mercury in Groundwater

Mercury contamination in aquatic ecosystems under a changing environment: Implications for the Three Gorges Reservoir

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