Oxidation and methylation of dissolved elemental mercury by anaerobic bacteria

Hu, Haiyan; Lin, Hui; Zheng, Wang; Tomanicek, S.J.; Johs, Alexander; Feng, Xinbin; Elias, Dwayne A.; Liang, Liyuan; Gu, Baohua

doi:10.1038/ngeo1894

Cited by 164 publications

(244 citation statements)

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“…In addition, Hg transformations operated by microbial activity, via methylation and demethylation processes (likely not applicable to building materials we are dealing with in this paper), may further mobilize or stabilize mercury, e.g. [65] and references therein).…”

Section: Total and Leached Mercury Concentrations In The Building Andmentioning

confidence: 99%

Gaseous Elemental Mercury and Total and Leached Mercury in Building Materials from the Former Hg-Mining Area of Abbadia San Salvatore (Central Italy)

Vaselli¹,

Nisi²,

Rappuoli³

et al. 2017

Preprint

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Mercury has a strong environmental impact since both its organic and inorganic forms are toxic and it represents a pollutant of global concern. Liquid Hg is highly volatile and it can be released during natural and anthropogenic processes in the hydrosphere, biosphere and atmosphere. In this study the distribution of Gaseous Elemental Mercury (GEM) and the total and leached mercury concentrations on paints, plasters, roof tiles, concretes, metals, dust and wood structures were determined in the main buildings and structures of the former Hg-mining area of Abbadia San Salvatore (Siena, Central Italy). The mining complex (divided into 7 units) covers a surface of about 65 ha and contains mining structures and managers and workers buildings. In this work, nine surveys of GEM measurements were carried out from July 2011 to August 2015 for the buildings and structures located in the units 2, 3 and 6. Moreover, detailed measurements were performed in February, April, July, September and December 2016 in the edifices and mining structures of Unit 6. GEM concentrations showed a strong variability in terms of space and time mostly depending on the distance from the building hosting driers, furnaces and condensers and ambient temperature, respectively. In the Unit 2 surveys carried out in the hotter period (from June to September) showed GEM concentrations up to 27,500 ng m −3 , while in the Unit 6 they were on average much higher and occasionally they saturated the GEM measurement device (>50,000 ng m −3 ). Concentrations of total (in mg kg −1 ) and leached (in μg L −1 ) mercury measured in different building materials (up to 46,580 mg kg −1 and 4,470 mg L −1 for total and leached mercury, respectively) showed for the same type of material highly variable values in dependence on the edifice or mining structure from which they were collected. The results obtained in this study are of relevant interest for the operational cleanings to be carried out during the reclamation activities.

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Section: Total and Leached Mercury Concentrations In The Building Andmentioning

confidence: 99%

Gaseous Elemental Mercury and Total and Leached Mercury in Building Materials from the Former Hg-Mining Area of Abbadia San Salvatore (Central Italy)

Vaselli¹,

Nisi²,

Rappuoli³

et al. 2017

Preprint

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“…Kuss et al (2015) reported that cyanobacteria-light synergetic and photochemical transformation equally contributed to ∼ 30 % DGM production in the Baltic Sea, while low-light production contributed and transported out as Hg 0 (Barkay et al, 2003); the other is Hg II reduced by Hg-sensitive dissimilatory metal-reducing bacteria utilizing iron and/or manganese as a terminal electron acceptor during respiration (Wiatrowski et al, 2006). Intracellular oxidation is supposed to be mediated by oxidase (Siciliano et al, 2002), while extracellular thiol functional groups on cell membrane also show capabilities in oxidizing Hg 0 under anoxic environment (Colombo et al, 2013;Hu et al, 2013). A review of genetic-based microbial Hg redox transformation can be found in Lin et al (2011).…”

Section: Air-water Hg Exchangementioning

confidence: 99%

Global observations and modeling of atmosphere–surface exchange of elemental mercury: a critical review

et al. 2016

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Abstract. Reliable quantification of air-surface fluxes of elemental Hg vapor (Hg 0 ) is crucial for understanding mercury (Hg) global biogeochemical cycles. There have been extensive measurements and modeling efforts devoted to estimating the exchange fluxes between the atmosphere and various surfaces (e.g., soil, canopies, water, snow, etc.) in the past three decades. However, large uncertainties remain due to the complexity of Hg 0 bidirectional exchange, limitations of flux quantification techniques and challenges in model parameterization. In this study, we provide a critical review on the state of science in the atmosphere-surface exchange of Hg 0 . Specifically, the advancement of flux quantification techniques, mechanisms in driving the air-surface Hg exchange and modeling efforts are presented. Due to the semi-volatile nature of Hg 0 and redox transformation of Hg in environmental media, Hg deposition and evasion are influenced by multiple environmental variables including seasonality, vegetative coverage and its life cycle, temperature, light, moisture, atmospheric turbulence and the presence of reactants (e.g., O 3 , radicals, etc.). However, the effects of these processes on flux have not been fundamentally and quantitatively determined, which limits the accuracy of flux modeling.We compile an up-to-date global observational flux database and discuss the implication of flux data on the global Hg budget. Mean Hg 0 fluxes obtained by micrometeorological measurements do not appear to be significantly greater than the fluxes measured by dynamic flux chamber methods over unpolluted surfaces (p = 0.16, one-tailed, Mann-Whitney U test). The spatiotemporal coverage of existing Hg 0 flux measurements is highly heterogeneous with large data gaps existing in multiple continents (Africa, South Asia, Middle East, South America and Australia). The magnitude of the evasion flux is strongly enhanced by human activities, particularly at contaminated sites. Hg 0 flux observations in East Asia are comparatively larger in magnitude than the rest of the world, suggesting substantial re-emission of previously deposited mercury from anthropogenic sources. The Hg 0 exchange over pristine surfaces (e.g., background soil and water) and vegetation needs better constraints for global analyses of the atmospheric Hg budget. The existing knowledge gap and the associated research needs for future measurements and modeling efforts for the air-surface exchange of Hg 0 are discussed.

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“…5 The Hg methylation process is primarily mediated by certain anaerobic microbes (e.g., sulfate-reducing bacteria (SRB), ironreducing bacteria, and methanogens), 13−15 and SRB have been considered to play the most important role. 16,17 Studies have shown that SRB are abundant in paddy fields, because the flooded condition can favor the reoxidation process of reduced sulfur compounds. 18,19 Moreover, anaerobic conditions in paddy fields may increase Hg mobilization into the soil solution and favor the methylation of Hg by anaerobic microbes, leading to an enhancement of Hg and MeHg bioavailability to rice plants.…”

Section: Introductionmentioning

confidence: 99%

Growing Rice Aerobically Markedly Decreases Mercury Accumulation by Reducing Both Hg Bioavailability and the Production of MeHg

Wang

Luo³

et al. 2014

Environ. Sci. Technol.

100

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Rice consumption represents a major route of mercury (Hg) and methylmercury (MeHg) exposure for those living in certain areas of inland China. In this study we investigated the effects of water management on bioavailable Hg, MeHg, and sulfate-reducing bacteria (SRB, abundance and community composition) in rhizosphere soil, and total Hg (THg) and MeHg in rice plants grown under glasshouse and paddy field conditions. Aerobic conditions greatly decreased the amount of THg and MeHg taken up by rice plants and affected their distribution in different plant tissues. There were positive correlations between bioavailable Hg and THg in brown rice and roots and between numbers of SRB and MeHg in brown rice, roots, and rhizosphere soil. Furthermore, the community composition of SRB was dramatically influenced by the water management regimes. Our results demonstrate that the greatly reduced bioavailability of Hg and production of MeHg are due to decreased SRB numbers and proportion of Hg methylators in the rhizosphere under aerobic conditions. These are the main reasons for the reduced Hg and MeHg accumulation in aerobically grown rice. Water management is indicated as an effective measure that can be used to reduce Hg and MeHg uptake by rice plants from Hgcontaminated paddy fields.

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Oxidation and methylation of dissolved elemental mercury by anaerobic bacteria

Cited by 164 publications

References 30 publications

Gaseous Elemental Mercury and Total and Leached Mercury in Building Materials from the Former Hg-Mining Area of Abbadia San Salvatore (Central Italy)

Gaseous Elemental Mercury and Total and Leached Mercury in Building Materials from the Former Hg-Mining Area of Abbadia San Salvatore (Central Italy)

Global observations and modeling of atmosphere–surface exchange of elemental mercury: a critical review

Growing Rice Aerobically Markedly Decreases Mercury Accumulation by Reducing Both Hg Bioavailability and the Production of MeHg

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