Dimethylmercury and Dimethylmercury-Sulfide of Microbial Origin in the Biogeochemical Cycle of Hg

Baldi, Franco; Parati, Francesca; Filippelli, Marco

doi:10.1007/978-94-011-0153-0_86

Cited by 14 publications

(4 citation statements)

References 26 publications

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“…66−70 To avoid the possible interference by acetate buffer in the formation of Hg compounds, 70 sulfuric acid and sodium hydroxide were used to adjust pH. 70,71 Therefore, in this study 100 mL of 0.035 mg 72 A schematic illustration of this design is shown in Figure S1. The total volume of the chamber of OTCs was 0.6 m 3 , with the air turnover time of about 50 s. All fixtures and tubing for the experiments were made or wrapped with Teflon to minimize the absorption of gaseous DMeHg.…”

Section: Methodsmentioning

confidence: 99%

Mechanism of Accumulation of Methylmercury in Rice (Oryza sativa L.) in a Mercury Mining Area

Wang

Sun

Driscoll

et al. 2018

Environ. Sci. Technol.

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Rice consumption is the primary pathway for methylmercury (MeHg) exposure at inland mercury (Hg) mining areas of China. The sources and processes of formation and translocation for MeHg in rice plant are complex and remain largely unknown. In this study, rice ( Oryza sativa L.) was exposed to isotopically labeled dimethylmercury (DMeHg) in field experiments using open top chambers to explore the response of MeHg accumulation in rice tissues to different levels of DMeHg in air. Rice leaves assimilated DMeHg from air, which was subsequently largely stored in aboveground tissues, including the rice grain, with only a small amount reaching the root. Combining these experimental results with field investigations of DMeHg concentrations in air beneath the rice canopy in a Hg mining area, we estimate that 15.5%, 10.8%, and 8.50% MeHg in the brown rice, the leaf, and the upper stalk, respectively, could be derived from atmospheric sources of DMeHg, while 99.5% of MeHg in rice root originated from the rice soil-water system. These findings help refine the mechanism of MeHg accumulation in rice that, in addition to soil, a fraction of MeHg in rice plants can be derived from DMeHg emissions from flooded rice paddies in Hg mining areas.

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Section: Methodsmentioning

confidence: 99%

Mechanism of Accumulation of Methylmercury in Rice (Oryza sativa L.) in a Mercury Mining Area

Wang

Sun

Driscoll

et al. 2018

Environ. Sci. Technol.

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“…DMHg production has been shown to occur in cultures of Hg methylating bacteria. 132 The mechanism of this process, particularly in the context of the hgcAB system, is unknown, as stated earlier. Abiotic formation of DMHg can occur from a reaction between MMHg (as CH 3 HgCl) with H 2 S, yielding volatile products such as Hg 0 and DMHg.…”

Section: Methylation and Demethylation Of Mercurymentioning

confidence: 98%

Biogeochemical transformations of mercury in solid waste landfills and pathways for release

Lee

Lowry

Hsu‐Kim

2016

Environ. Sci.: Processes Impacts

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Mercury (Hg) is present in a variety of solid wastes including industrial wastes, household products, consumer electronics, and medical wastes, some of which can be disposed in conventional landfills. The presence of this neurotoxic metal in landfills is a concern due to the potential for it to leach or volatilize from the landfill and impact local ecosystems. The objective of this review is to describe general practices for the disposal of mercury-bearing solid wastes, summarize previous studies on the release of mercury from landfills, and delineate the expected transformations of Hg within landfill environments that would influence transport of Hg via landfill gas and leachate. A few studies have documented the emissions of Hg as landfill gas, primarily as gaseous elemental Hg(0) and smaller amounts as methylated Hg species. Much less is known regarding the release of Hg in leachate. Landfill conditions are unique from other subsurface environments in that they can contain water with very high conductivity and organic carbon concentration. Landfills also experience large changes in redox potential (and the associated microbial community) that greatly influence Hg speciation, transformations, and mobilization potential. Generally, Hg is not likely to persist in large quantities as dissolved species, since Hg(0) tends to evolve in the gas phase and divalent Hg(ii) sorbs strongly to particulate phases including organic carbon and sulfides. However, Hg(ii) has the potential to associate with or form colloidal particles that can be mobilized in porous media under high organic carbon conditions. Moreover, the anaerobic conditions within landfills can foster the growth of microorganisms that produced monomethyl- and dimethyl-Hg species, the forms of mercury with high potential for bioaccumulation. Much advancement has recently been made in the mercury biogeochemistry research field, and this study seeks to incorporate these findings for landfill settings.

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“…Early investigations reported microbially mediated DMeHg production in estuarine and mangrove environments. 50,51 Incubation experiments utilizing Arctic seawater demonstrated that during methylation the rate of conversion of MMeHg to DMeHg was 1 to 2 orders of magnitude greater than the conversion of Hg 2+ to DMeHg. 52 The total production of gaseous DMeHg and MMeHg was determined as the sum of all temporal observations during the incubation experiments (Figure S5A).…”

Section: T H Imentioning

confidence: 99%

Dimethylmercury in Floodwaters of Mercury Contaminated Rice Paddies

Wang

Sun

Driscoll

et al. 2019

Environ. Sci. Technol.

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Dimethyl mercury (CH3HgCH3, DMeHg) has been observed in upwelling marine environments and the deep ocean. However, little is known about the occurrence and mechanisms of DMeHg formation in freshwater environments. In this study, concentrations of dissolved gaseous DMeHg were investigated in floodwaters of rice paddies in China that have been contaminated by mercury from mining. Values of DMeHg in rice paddies were compared with measurements from nearshore surface seawater in the Bohai Gulf. High concentrations of dissolved gaseous DMeHg occurred in rice paddies. Average DMeHg concentration was 12 ± 22 pg L–1 with range of 0.39 to 91 pg L–1 in rice paddies at Shuijing, China, a site impacted by an abandoned mercury mine. These concentrations are comparable to those previously observed in the deep seawater and coastal upwelling environments (2.3–115pg L–1). An alkaline environment was found to be necessary for DMeHg formation in rice paddies. Associated incubation experiments showed that production of DMeHg in paddy soil was limited by Hg availability. Although iron amendments accelerated the production of gaseous methylmercury (MeHg) species to floodwaters, available Hg2+ is crucial for this production in flooded rice paddies. These observations are the first to demonstrate the occurrence of DMeHg and reveal factors affecting DMeHg production in rice paddies. Given the high volatility of DMeHg, these measurements also suggest a source for observations of MeHg in atmospheric deposition and advance understanding of a potentially important aspect of the biogeochemical cycling of Hg.

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Dimethylmercury and Dimethylmercury-Sulfide of Microbial Origin in the Biogeochemical Cycle of Hg

Cited by 14 publications

References 26 publications

Mechanism of Accumulation of Methylmercury in Rice (Oryza sativa L.) in a Mercury Mining Area

Mechanism of Accumulation of Methylmercury in Rice (Oryza sativa L.) in a Mercury Mining Area

Biogeochemical transformations of mercury in solid waste landfills and pathways for release

Dimethylmercury in Floodwaters of Mercury Contaminated Rice Paddies

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