Sulfate stimulation of mercury methylation in freshwater sediments

Gilmour, Cynthia C.; Henry, E. A.; Mitchell, Ralph

doi:10.1021/es00035a029

Cited by 966 publications

(652 citation statements)

References 33 publications

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“…The MeHg contents in sediments account for normally 1% to 1.5% of HgT except for some lakes and wetlands where the percentage of MeHg can reach 10% (Gilmour et al, 1992;Ullrich et al, 2001). In Haihe River and Dagu Drainage River sediments, the MeHg concentrations ranged from 0.7 to 21.7 ng g À1 (dry weight) and the average value was 2.9 ng g À1 (dry weight).…”

Section: Total Mercury and Methylmercury In Sedimentsmentioning

confidence: 99%

The speciation and bioavailability of mercury in sediments of Haihe River, China

Shi

Liang

Jiang

et al. 2005

Environment International

140

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Twenty-one sediment samples in 11 sites along the Haihe River and Dagu Drainage River, Tianjin, China, were analyzed to investigate the pollution status and bioavailability of mercury (Hg). The results showed that the Haihe River was slightly polluted with Hg when flowing through Tianjin city. On the contrary, the sediments collected from Dagu Drainage River, an important drainage river in Tianjin, were found to have very high Hg concentrations and the highest concentration reached 8779.1 ng g À1 (dry weight). The methylmercury (MeHg) concentrations accounted for 0.1-2.4% (average: 0.9%) of total mercury (HgT) and were strongly influenced by HgT (r=0.91, p=0.99, n=20) and total organic carbon (TOC; r=0.76, p=0.99, n=20) contents in sediments. Moreover, a five-step sequential selective extraction (SSE) procedure was used to study the bioavailability of Hg in sediments. The mercury in sediments existed mainly as element Hg and mercury sulfide, which accounted for 46.5% and 39.0% of HgT, respectively. The percentage of exchangeable Hg (defined as water soluble Hg plus dhuman stomach acidT soluble Hg) was only 0.1-4.6%. The distribution of exchangeable Hg showed an obvious difference to that of HgT, indicating that the HgT concentrations were absolutely insufficient to evaluate the risk of Hg in sediments. D

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Section: Total Mercury and Methylmercury In Sedimentsmentioning

confidence: 99%

The speciation and bioavailability of mercury in sediments of Haihe River, China

Shi

Liang

Jiang

et al. 2005

Environment International

140

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“…Most Hg in soil is detected as ionic Hg 2+ species and shows relatively low toxicity, however, it still poses some environmental risk due to potential for Hg methylation followed by bioamplification in soilplant systems (Meng et al 2010;Liu et al 2012). Earlier studies have examined microbial methylation of Hg in estuarine, wetland, and freshwater sediments (Gilmour et al 1992; Heyes et al 2006;Duran et al 2008;Todorova et al 2009), but little attention to date has been paid to the linkage between specific types of microorganism and Hg methylation in soil environments. Since some studies reported high MeHg contents in both of soil and rice in the Wanshan Hg mine area of Guizhou province in southwest China (Feng et al 2008;Zhang et al 2010), concerns have been raised about the fate of Hg and potential production of MeHg in the local soil-rice system.…”

Section: Introductionmentioning

confidence: 99%

Linkage between community diversity of sulfate-reducing microorganisms and methylmercury concentration in paddy soil

Liu

Zheng

Zhang

et al. 2013

Environ Sci Pollut Res

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Sulfate-reducing microorganisms (SRM) have been thought to play a key role in mercury (Hg) methylation in anoxic environments. The current study examined the linkage between SRM abundance and diversity and contents of methylmercury (MeHg) in paddy soils collected from a historical Hg mining area in China. Soil profile samples were collected from four sites over a distance gradient downstream the Hg mining operation. Results showed that MeHg content in the soil of each site significantly decreased with the extending distance away from Hg mine. Soil MeHg content was correlated positively with abundance of SRM and the contents of organic matter (OM), NH 4 + , SO 4 2− , and Hg. The abundances of SRM based on dissimilatory (bi) sulfite reductase (dsrAB) gene at 0-40 cm depths were higher than those at 40-80 cm depth at all sites. The SRM community composition varied in the soils of different sampling sites following terminal restriction fragment length polymorphism (T-RFLP) and phylogenetic analyses, which appeared to be correlated with contents of MeHg, OM, NH 4 + , and SO 4 2− through canonical correspondence analysis. The dominant groups of SRM in the soils examined belonged to Deltaproteobacteria and some unknown SRM clusters that could have potential for Hg methylation. These results advance our understanding of the relationship between SRM and methylmercury concentration in paddy soil.

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“…For instance, in forested wetland-dominated watersheds, the stimulation of microbial MeHg production would be fueled by the oxidation of abundant organic matter as microbial respiration of organic carbon leads to the development of anoxic conditions which in turn favors sulfate reduction by sulfate reducing bacteria (SRB). The latter are one of the prevalent microbial groups linked to Hg methylation in several published studies (Gilmour et al 1992;King et al 2000;Drott et al 2007;Shao et al 2012). Also, wetlands have been identified as factories of MeHg production (St. Louis et al 1994;Branfireun et al 1999;Hall et al 2008) and would likely behave as sources of both MeHg and DOC to rivers when present within watersheds.…”

Section: Resultsmentioning

confidence: 99%

Linking landscape development intensity within watersheds to methyl-mercury accumulation in river sediments

Donkor

Attibayeba

Gao

2015

Ambio

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An indicator of the disturbance of natural systems, the landscape development intensity (LDI) index, was used to assess the potential for land-use within watersheds to influence the production/ accumulation of methyl-mercury (MeHg) in river sediments. Sediment samples were collected from locations impacted by well-identified land-use types within the Mobile-Alabama River Basin in Southeastern USA. The samples were analyzed for total-Hg (THg) and MeHg concentrations and the obtained values correlated to the calculated LDI indexes of the sampled watersheds to assess the impact of prevalent land use/land cover on MeHg accumulation in sediments. The results show that unlike THg, levels of MeHg found in sediments are impacted by the LDI indexes. Overall, certain combinations of land-use types within a given watershed appear to be more conducive to MeHg accumulation than others, therefore, pointing to the possibility of targeting land-use practices as potential means for reducing MeHg accumulation in sediments, and ultimately, fish contamination.

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Sulfate stimulation of mercury methylation in freshwater sediments

Cited by 966 publications

References 33 publications

The speciation and bioavailability of mercury in sediments of Haihe River, China

The speciation and bioavailability of mercury in sediments of Haihe River, China

Linkage between community diversity of sulfate-reducing microorganisms and methylmercury concentration in paddy soil

Linking landscape development intensity within watersheds to methyl-mercury accumulation in river sediments

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