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Title: Quantification of Mercury Bioavailability for Methylation Using Diffusive Gradient in Thin-Film Samplers

Abstract

Here, mercury-contaminated sediment and water contain various Hg species, with a small fraction available for microbial conversion to the bioaccumulative neurotoxin monomethylmercury (MeHg). Quantification of this available Hg pool is needed to prioritize sites for risk management. This study compared the efficacy of diffusive gradient in thin-film (DGT) passive samplers to a thiol-based selective extraction method with glutathione (GSH) and conventional filtration (<0.2 μm) as indicators of Hg bioavailability. Anaerobic sediment slurry microcosms were amended with isotopically labeled inorganic Hg “endmembers” (dissolved Hg 2+, Hg-humic acid, Hg-sorbed to FeS, HgS nanoparticles) with a known range of bioavailability and methylation potentials. Net MeHg production (expressed as percent of total Hg as MeHg) over 1 week correlated with mass accumulation of Hg endmembers on the DGTs and only sometimes correlated with the 0.2 μm filter passing Hg fraction and the GSH-extractable Hg fraction. These results suggest for the first time that inorganic Hg uptake in DGTs may indicate bioavailability for methylating microbes. Moreover, the methylating microbial community assessed by hgcA gene abundance was not always consistent with methylation rates between the experiments, indicating that knowledge of the methylating community should target the transcript or protein level. Altogether, these results suggest that DGTsmore » could be used to quantify the bioavailable Hg fraction as part of a method to assess net MeHg production potential in the environment.« less

Authors:
 [1];  [2]; ORCiD logo [1];  [2]; ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [1]
  1. Duke Univ., Durham, NC (United States). Dept. of Civil and Environmental Engineering
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biosciences Division
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1465054
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Environmental Science and Technology
Additional Journal Information:
Journal Volume: 52; Journal Issue: 15; Journal ID: ISSN 0013-936X
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Ndu, Udonna, Christensen, Geoff A., Rivera, Nelson A., Gionfriddo, Caitlin M., Deshusses, Marc A., Elias, Dwayne A., and Hsu-Kim, Heileen. Quantification of Mercury Bioavailability for Methylation Using Diffusive Gradient in Thin-Film Samplers. United States: N. p., 2018. Web. doi:10.1021/acs.est.8b00647.
Ndu, Udonna, Christensen, Geoff A., Rivera, Nelson A., Gionfriddo, Caitlin M., Deshusses, Marc A., Elias, Dwayne A., & Hsu-Kim, Heileen. Quantification of Mercury Bioavailability for Methylation Using Diffusive Gradient in Thin-Film Samplers. United States. doi:10.1021/acs.est.8b00647.
Ndu, Udonna, Christensen, Geoff A., Rivera, Nelson A., Gionfriddo, Caitlin M., Deshusses, Marc A., Elias, Dwayne A., and Hsu-Kim, Heileen. Tue . "Quantification of Mercury Bioavailability for Methylation Using Diffusive Gradient in Thin-Film Samplers". United States. doi:10.1021/acs.est.8b00647. https://www.osti.gov/servlets/purl/1465054.
@article{osti_1465054,
title = {Quantification of Mercury Bioavailability for Methylation Using Diffusive Gradient in Thin-Film Samplers},
author = {Ndu, Udonna and Christensen, Geoff A. and Rivera, Nelson A. and Gionfriddo, Caitlin M. and Deshusses, Marc A. and Elias, Dwayne A. and Hsu-Kim, Heileen},
abstractNote = {Here, mercury-contaminated sediment and water contain various Hg species, with a small fraction available for microbial conversion to the bioaccumulative neurotoxin monomethylmercury (MeHg). Quantification of this available Hg pool is needed to prioritize sites for risk management. This study compared the efficacy of diffusive gradient in thin-film (DGT) passive samplers to a thiol-based selective extraction method with glutathione (GSH) and conventional filtration (<0.2 μm) as indicators of Hg bioavailability. Anaerobic sediment slurry microcosms were amended with isotopically labeled inorganic Hg “endmembers” (dissolved Hg2+, Hg-humic acid, Hg-sorbed to FeS, HgS nanoparticles) with a known range of bioavailability and methylation potentials. Net MeHg production (expressed as percent of total Hg as MeHg) over 1 week correlated with mass accumulation of Hg endmembers on the DGTs and only sometimes correlated with the 0.2 μm filter passing Hg fraction and the GSH-extractable Hg fraction. These results suggest for the first time that inorganic Hg uptake in DGTs may indicate bioavailability for methylating microbes. Moreover, the methylating microbial community assessed by hgcA gene abundance was not always consistent with methylation rates between the experiments, indicating that knowledge of the methylating community should target the transcript or protein level. Altogether, these results suggest that DGTs could be used to quantify the bioavailable Hg fraction as part of a method to assess net MeHg production potential in the environment.},
doi = {10.1021/acs.est.8b00647},
journal = {Environmental Science and Technology},
number = 15,
volume = 52,
place = {United States},
year = {2018},
month = {6}
}

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