Precipitation of nanoscale mercuric sulfides in the presence of natural organic matter: Structural properties, aggregation, and biotransformation

Pham, Anh Le‐Tuan; Morris, Amanda J.; Zhang, Tong; Ticknor, Jonathan L.; Levard, Clément; Hsu‐Kim, Heileen

doi:10.1016/j.gca.2014.02.027

Cited by 64 publications

(97 citation statements)

References 37 publications

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“…For instance, the methylation rate has been shown to decrease with increasing mercuric sulfide aging (from dissolved Hg to nanoparticulate and microcrystalline HgS) [95]. In addition, the association with organic matter would also influence this methylation rate [96]. In the present case, nanoparticulate HgS in the zone hosting sulfate-reducing bacteria may be favorable to the production of methyl mercury.…”

Section: Microorganisms: Mineral Interactions Down To the Deep Monimomentioning

confidence: 67%

Mineralogical Diversity in Lake Pavin: Connections with Water Column Chemistry and Biomineralization Processes

et al. 2016

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Abstract:As biominerals are good tracers of microbial interactions with the environment, they may provide signatures of microbial evolution and paleoenvironmental conditions. Since modern analogues of past environments help with defining proxies and biosignatures, we explored microbe mineral interactions in the water column of a maar lake, located in France: Lake Pavin. This lake is considered as a potential Precambrian ocean analogue, as it is ferruginous and meromictic, i.e., stratified with a superficial O 2 -rich layer (mixolimnion) and a deeper permanently anoxic layer (monimolimnion). We combined bulk chemical analyses of dissolved and particulate matter in combination with electron microscopy analyses of the particulate matter at different depths along the water column. The mineralogy changed along with water chemistry, and most of the minerals were intimately associated with microorganisms. Evolution of the redox conditions with depth leads to the successive precipitation of silica and carbonates, Mn-bearing, Fe-bearing and S-containing phases, with a predominance of phosphates in the monimolimnion. This scheme parallels the currently-assessed changes of microbial diversity with depth. The present results corroborate previous studies that suggested a strong influence of microbial activity on mineralogical diversity through extracellular and intracellular biomineralization. This paper reports detailed data on mineralogical profiles of the water column and encourages extended investigation of these processes.

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Section: Microorganisms: Mineral Interactions Down To the Deep Monimomentioning

confidence: 67%

Mineralogical Diversity in Lake Pavin: Connections with Water Column Chemistry and Biomineralization Processes

et al. 2016

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“…The HgS stock solution was aged for 24 h at room temperature before use in the experiments. According to previous work (Pham et al, 2014), stocks prepared in this manner resulted in nanoparticles of a metacinnabar-like composition with a primary particle diameter of *5 nm and a hydrodynamic diameter of 33 nm.…”

Section: Methodsmentioning

confidence: 99%

“…The suspension was mixed vigorously for 5 min until the particles were formed, and then the solution was aged for an additional 24 h under static conditions (Pham et al, 2014). Previous characterization by Pham et al showed that the particles comprised crystalline b-HgS.…”

Section: Methodsmentioning

confidence: 99%

“…For instance, mercury is capable of forming nanoscale particles with sulfide, and previous studies have shown that nanoparticulate HgS is more bioavailable for methylating bacteria when compared with their microparticulate counterparts (Zhang et al, 2012). This difference between nanoscale and microcrystalline phases is not predicted based on equilibrium solubility and cannot be explained entirely by the dissolution of Hg into bulk water (Zhang et al, 2012Pham et al, 2014). In addition, the formation rate of nanoparticulate HgS is influenced by the amount of dissolved sulfide and natural organic matter (Deonarine and Hsu-Kim, 2009;Slowey, 2010;Gerbig et al, 2011;Graham et al, 2012a;Pham et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…This difference between nanoscale and microcrystalline phases is not predicted based on equilibrium solubility and cannot be explained entirely by the dissolution of Hg into bulk water (Zhang et al, 2012Pham et al, 2014). In addition, the formation rate of nanoparticulate HgS is influenced by the amount of dissolved sulfide and natural organic matter (Deonarine and Hsu-Kim, 2009;Slowey, 2010;Gerbig et al, 2011;Graham et al, 2012a;Pham et al, 2014). Thus, to accurately quantify methylation, the system dynamics must be considered, which is beyond the capability of today's chemical speciation models.…”

Section: Introductionmentioning

confidence: 99%

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Thiol-Based Selective Extraction Assay to Comparatively Assess Bioavailable Mercury in Sediments

Ticknor

Kucharzyk

Porter

et al. 2015

Environmental Engineering Science

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Bioaccumulation of methylmercury in the aquatic food web is governed in part by the methylation of inorganic divalent mercury (Hg(II)) by anaerobic microorganisms. In sulfidic settings, a small fraction of total Hg(II) is typically bioavailable to methylating microorganisms. Quantification of this fraction is difficult due to uncertainties in the speciation of Hg(II) and the mechanisms of uptake by methylating microbes. However, recent studies have shown that the bioavailable fraction is likely to include a portion of Hg(II) associated with solid phases, that is, nanostructured mercuric sulfides. Moreover, addition of thiols to suspensions of methylating cultures coincides with increased uptake into cells and methylmercury production. Here, we present a thiol-based selective extraction assay to provide information on the bioavailable Hg fraction in sediments. In the procedure, sediment samples were exposed to a nitrogen-purged solution of glutathione (GSH) for 30 min and the amount of GSH-leachable mercury was quantified. In nine sediment samples from a marine location, the relative GSH-leachable mercury concentration was strongly correlated to the relative amount of methylmercury in the sediments (=0.91, <0.0001) across an order of magnitude of methylmercury concentration values. The approach was further applied to anaerobic sediment slurry microcosm experiments in which sediments were cultured under the same microbial growth conditions but were amended with multiple forms of Hg with a known spectrum of bioavailability. GSH-leachable Hg concentrations increased with observed methylmercury concentrations in the microcosms, matching the trend of species bioavailability in our previous work. Results suggest that a thiol-based selective leaching approach is an improvement compared with other proposed methods to assess Hg bioavailability in sediment and that this approach could provide a basis for comparison of sites where Hg methylation is a concern.

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Planetary, Geological and Environmental Sciences

Farges

Wilke

2016

X‐Ray Absorption and X‐Ray Emission Spectroscopy

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Precipitation of nanoscale mercuric sulfides in the presence of natural organic matter: Structural properties, aggregation, and biotransformation

Cited by 64 publications

References 37 publications

Mineralogical Diversity in Lake Pavin: Connections with Water Column Chemistry and Biomineralization Processes

Mineralogical Diversity in Lake Pavin: Connections with Water Column Chemistry and Biomineralization Processes

Thiol-Based Selective Extraction Assay to Comparatively Assess Bioavailable Mercury in Sediments

Planetary, Geological and Environmental Sciences

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