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Title: Mercury Adsorption on Minerals and Its Effect on Microbial Methylation

Abstract

Adsorbed or solid-phase inorganic mercury [Hg(II)] is commonly assumed immobile or less bioavailable for microbial uptake, although recent studies suggest that mineral-adsorbed Hg(II) is at least partially available for cell uptake and methylation. This study examined the adsorption of Hg(II) onto two reference minerals, hematite and montmorillonite, and evaluated Hg(II) uptake and methylation by a sulfate-reducing bacterium Desulfovibrio desulfuricans ND132 in laboratory incubations. Mineral-adsorbed Hg(II) on both hematite and montmorillonite was not only available for cell uptake and methylation but also resulted in a 2–3-fold increased methylmercury production compared to the mineral-free incubation. An optimal Hg(II) methylation was observed at a low to moderate mineral/solution ratio (1–5 g L–1) with fixed Hg(II) (25 nM) and cell concentrations. The result could be explained by decreased cellular immobilization of Hg(II) but enhanced close interactions between Hg(II) and cells both adsorbed or concentrated on mineral surfaces, leading to increased methylation. However, a high mineral/solution ratio inhibited Hg(II) methylation, likely as a result of a low Hg(II) coverage (per surface area) at high mineral loadings, which limit close contacts between Hg(II) and the cells. These results indicate that mineral-adsorbed Hg(II) may be directly available for microbial uptake or methylation, although whether the adsorption enhancesmore » or inhibits Hg(II) methylation may depend upon microniches, where Hg(II), microbes, and minerals co-exist in the natural environment. We suggest that future studies are performed to establish quantitative relationships of bioavailable Hg(II) with not only the dissolved but also adsorbed Hg(II) species to improve model predictions of Hg(II) fate and transformations.« less

Authors:
 [1];  [1];  [1];  [2];  [1];  [1]
  1. Oak Ridge National Laboratory
  2. BATTELLE (PACIFIC NW LAB)
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1571496
Report Number(s):
PNNL-SA-147062
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
ACS Earth and Space Chemistry
Additional Journal Information:
Journal Volume: 3; Journal Issue: 7
Country of Publication:
United States
Language:
English

Citation Formats

Zhao, Linduo, Li, Yunzi, Zhang, Lijie, Zheng, Jianqiu, Pierce, Eric M., and Gu, Baohua. Mercury Adsorption on Minerals and Its Effect on Microbial Methylation. United States: N. p., 2019. Web. doi:10.1021/acsearthspacechem.9b00039.
Zhao, Linduo, Li, Yunzi, Zhang, Lijie, Zheng, Jianqiu, Pierce, Eric M., & Gu, Baohua. Mercury Adsorption on Minerals and Its Effect on Microbial Methylation. United States. doi:10.1021/acsearthspacechem.9b00039.
Zhao, Linduo, Li, Yunzi, Zhang, Lijie, Zheng, Jianqiu, Pierce, Eric M., and Gu, Baohua. Thu . "Mercury Adsorption on Minerals and Its Effect on Microbial Methylation". United States. doi:10.1021/acsearthspacechem.9b00039.
@article{osti_1571496,
title = {Mercury Adsorption on Minerals and Its Effect on Microbial Methylation},
author = {Zhao, Linduo and Li, Yunzi and Zhang, Lijie and Zheng, Jianqiu and Pierce, Eric M. and Gu, Baohua},
abstractNote = {Adsorbed or solid-phase inorganic mercury [Hg(II)] is commonly assumed immobile or less bioavailable for microbial uptake, although recent studies suggest that mineral-adsorbed Hg(II) is at least partially available for cell uptake and methylation. This study examined the adsorption of Hg(II) onto two reference minerals, hematite and montmorillonite, and evaluated Hg(II) uptake and methylation by a sulfate-reducing bacterium Desulfovibrio desulfuricans ND132 in laboratory incubations. Mineral-adsorbed Hg(II) on both hematite and montmorillonite was not only available for cell uptake and methylation but also resulted in a 2–3-fold increased methylmercury production compared to the mineral-free incubation. An optimal Hg(II) methylation was observed at a low to moderate mineral/solution ratio (1–5 g L–1) with fixed Hg(II) (25 nM) and cell concentrations. The result could be explained by decreased cellular immobilization of Hg(II) but enhanced close interactions between Hg(II) and cells both adsorbed or concentrated on mineral surfaces, leading to increased methylation. However, a high mineral/solution ratio inhibited Hg(II) methylation, likely as a result of a low Hg(II) coverage (per surface area) at high mineral loadings, which limit close contacts between Hg(II) and the cells. These results indicate that mineral-adsorbed Hg(II) may be directly available for microbial uptake or methylation, although whether the adsorption enhances or inhibits Hg(II) methylation may depend upon microniches, where Hg(II), microbes, and minerals co-exist in the natural environment. We suggest that future studies are performed to establish quantitative relationships of bioavailable Hg(II) with not only the dissolved but also adsorbed Hg(II) species to improve model predictions of Hg(II) fate and transformations.},
doi = {10.1021/acsearthspacechem.9b00039},
journal = {ACS Earth and Space Chemistry},
number = 7,
volume = 3,
place = {United States},
year = {2019},
month = {7}
}