Anaerobic oxidation of Hg(0) and methylmercury formation by Desulfovibrio desulfuricans ND132

Colombo, Matthew J.; Ha, Ju-Young; Reinfelder, John R.; Barkay, Tamar; Yee, Nathan

doi:10.1016/j.gca.2013.03.001

Cited by 107 publications

(102 citation statements)

References 72 publications

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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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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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“…Further studies are needed regarding mercury in glacial ecosystems, especially regarding Me-Hg that can be bioaccumulated along the trophic chain [51]. Indeed Larose et al, found a negative correlation between bioavailable Hg and Me-Hg indicating a probable Hg biotic methylation [50]; in fact, bacteria can both cleave the bond or be responsible of methylation especially in anaerobic conditions [51,54]. Hg concentration in mountain firn core was found to be in the range of 2-35 ng·L −1 [55], and in…”

Section: Accumulation Of Pollutants and Microbiological Response In Cmentioning

confidence: 99%

“…On a molecular basis, the ability to aerobically biodegrade PCBs was identified in the presence of the gene bphA coding for the enzyme biphenyl dioxygenase, which was found in both metagenomic DNA and in the genome of the bacterial isolates. between bioavailable Hg and Me-Hg indicating a probable Hg biotic methylation [50]; in fact, bacteria can both cleave the bond or be responsible of methylation especially in anaerobic conditions [51,54]. Hg concentration in mountain firn core was found to be in the range of 2-35 ng•L −1 [55], and in freshwater from uncontaminated sites was in the range of 1-20 ng•L −1 [51], but a study by Moller and colleagues found in snow/brine concentrations of 70-80 ng•L −1 [53].…”

Section: Accumulation Of Pollutants and Microbiological Response In Cmentioning

confidence: 99%

Post-Depositional Biodegradation Processes of Pollutants on Glacier Surfaces

et al. 2018

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Abstract:Glaciers are important fresh-water reservoirs for our planet. Although they are often located at high elevations or in remote areas, glacial ecosystems are not pristine, as many pollutants can undergo long-range atmospheric transport and be deposited on glacier surface, where they can be stored for long periods of time, and then be released into the down-valley ecosystems. Understanding the dynamics of these pollutants in glaciers is therefore important for assessing their environmental fate. To this aim, it is important to study cryoconite holes, small ponds filled with water and with a layer of sediment, the cryoconite, at the bottom, which occur on the surface of most glaciers. Indeed, these environments are hotspots of biodiversity on glacier surface as they host metabolically active bacterial communities that include generalist taxa able to degrade pollutants. In this work, we aim to review the studies that have already investigated pollutant (e.g., chlorpyrifos and polychlorinated-biphenyls (PCBs)) degradation in cryoconite holes and other supraglacial environmental matrices. These studies have revealed that bacteria play a significant role in pollutant degradation in these habitats and can be positively selected in contaminated environments. We will also provide indication for future research in this field.

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“…13 Hg(0) can be oxidized to Hg(II) by both chemical and biological processes in aquatic environments, 6,7,14−17 and reduction of Hg(II) can produce Hg(0) in water, through photochemical processes, 6,18−20 enzymatic catalysis by mercury-resistant microorganisms, 7,21−23 or geochemical reactions involving humic acids and mineral-associated ferrous ion. 24−27 It was recently observed that dissolved Hg(0) could be methylated by Desulfovibrio desulf uricans ND132 to form MeHg, 13,14 which was a previously unrecognized pathway in Hg cycling. MeHg photodegradation in natural waters could also produce Hg(0) as an end product.…”

Section: ■ Introductionmentioning

confidence: 99%

Elemental Mercury in Natural Waters: Occurrence and Determination of Particulate Hg(0)

Liu³

et al. 2015

Environ. Sci. Technol.

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Elemental mercury, Hg(0), is ubiquitous in water and involved in key Hg biogeochemical processes. It is extensively studied as a purgeable dissolved species, termed dissolved gaseous mercury (DGM). Little information is available regarding nonpurgeable particulate Hg(0) in water, Hg(0) bound to suspended particulate matter (SPM), which is presumably present due to high affinity of Hg(0) adsorption on solids. By employing stable isotope tracer and isotope dilution (ID) techniques, we investigated the occurrence and quantification of particulate Hg(0) after Hg(0) being spiked into natural waters, aiming to provide firsthand information on particulate Hg(0) in water. A considerable fraction of 201 Hg(0) spiked in water (about 70% after 4 h equilibration) was bound to SPM and nonpurgeable, suggesting the occurrence of particulate Hg(0) in natural waters. A scheme, involving isotope dilution, purge and trap, and inductively coupled plasma mass spectrometry detection, was proposed to quantify particulate Hg(0) by the difference between DGM and total Hg(0), determined immediately and at equilibration after spiking ID Hg isotope, respectively. The application of this newly established method revealed the presence of particulate Hg(0) in Florida Everglades water, as the determined DGM levels (0.14 to 0.22 ng L −1 ) were remarkably lower than total Hg(0) (0.41 to 0.75 ng L −1 ). ■ INTRODUCTIONMercury (Hg), as a global pollutant, has received great attention due to accumulation and biomagnification of its methylation product, methylmercury (MeHg), through aquatic food chains. Elemental mercury, Hg(0), is an important species in Hg cycling, as considerable levels of Hg(0) are present in all environmental media, including the atmosphere (up to 95% of Hg being Hg(0)), 1,2 soil 3 and sediment, 4 and water. 5 Previous studies have shown that dissolved gaseous Hg (DGM), being mainly composed of Hg(0), is a ubiquitous form of inorganic Hg in seawater, 5,6 fresh water, 7−9 and groundwater. 10,11 Hg(0) in water is involved in key processes of Hg biogeochemical cycling including air−water exchange, 12 oxidation−reduction, 8 and methylation−demethylation. 13 Hg(0) can be oxidized to Hg(II) by both chemical and biological processes in aquatic environments, 6,7,14−17 and reduction of Hg(II) can produce Hg(0) in water, through photochemical processes, 6,18−20 enzymatic catalysis by mercury-resistant microorganisms, 7,21−23 or geochemical reactions involving humic acids and mineral-associated ferrous ion. 24−27 It was recently observed that dissolved Hg(0) could be methylated by Desulfovibrio desulf uricans ND132 to form MeHg, 13,14 which was a previously unrecognized pathway in Hg cycling. MeHg photodegradation in natural waters could also produce Hg(0) as an end product. 28−30 It should be noted that Hg(0) can be present in two forms in water, liquid Hg(0) droplet and aqueous Hg(0) (denoted as Hg(0) aq for distinction in some cases), with the former being rarely observed in uncontaminated natural waters and the latter being u...

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Anaerobic oxidation of Hg(0) and methylmercury formation by Desulfovibrio desulfuricans ND132

Cited by 107 publications

References 72 publications

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

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

Post-Depositional Biodegradation Processes of Pollutants on Glacier Surfaces

Elemental Mercury in Natural Waters: Occurrence and Determination of Particulate Hg(0)

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