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Title: Mercury Sorption and Desorption on Organo-Mineral Particulates as a Source for Microbial Methylation

Abstract

In natural freshwater and sediments, mercuric mercury (Hg(II)) is largely associated with particulate minerals and organics, but it remains unclear under what conditions particulates may become a sink or a source for Hg(II) and whether the particulate-bound Hg(II) is bioavailable for microbial uptake and methylation. In this study, we investigated Hg(II) sorption–desorption characteristics on three organo-coated hematite particulates and a Hg-contaminated natural sediment and evaluated the potential of particulate-bound Hg(II) for microbial methylation. Mercury rapidly sorbed onto particulates, especially the cysteine-coated hematite and sediment, with little desorption observed (0.1–4%). However, the presence of Hg-binding ligands, such as low-molecular-weight thiols and humic acids, resulted in up to 60% of Hg(II) desorption from the Hg-laden hematite particulates but <6% from the sediment. Importantly, the particulate-bound Hg(II) was bioavailable for uptake and methylation by a sulfate-reducing bacterium Desulfovibrio desulfuricans ND132 under anaerobic incubations, and the methylation rate was 4–10 times higher than the desorption rate of Hg(II). These observations suggest direct contacts and interactions between bacterial cells and the particulate-bound Hg(II), resulting in rapid exchange or uptake of Hg(II) by the bacteria. The results highlight the importance of Hg(II) partitioning at particulate–water interfaces and the role of particulates as a significant source ofmore » Hg(II) for methylation in the environment.« less

Authors:
 [1];  [2]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [3]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Nanchang Univ. (China)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1509536
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Environmental Science and Technology
Additional Journal Information:
Journal Volume: 53; Journal Issue: 5; Journal ID: ISSN 0013-936X
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Zhang, Lijie, Wu, Shan, Zhao, Linduo, Lu, Xia, Pierce, Eric M., and Gu, Baohua. Mercury Sorption and Desorption on Organo-Mineral Particulates as a Source for Microbial Methylation. United States: N. p., 2019. Web. doi:10.1021/acs.est.8b06020.
Zhang, Lijie, Wu, Shan, Zhao, Linduo, Lu, Xia, Pierce, Eric M., & Gu, Baohua. Mercury Sorption and Desorption on Organo-Mineral Particulates as a Source for Microbial Methylation. United States. doi:10.1021/acs.est.8b06020.
Zhang, Lijie, Wu, Shan, Zhao, Linduo, Lu, Xia, Pierce, Eric M., and Gu, Baohua. Thu . "Mercury Sorption and Desorption on Organo-Mineral Particulates as a Source for Microbial Methylation". United States. doi:10.1021/acs.est.8b06020.
@article{osti_1509536,
title = {Mercury Sorption and Desorption on Organo-Mineral Particulates as a Source for Microbial Methylation},
author = {Zhang, Lijie and Wu, Shan and Zhao, Linduo and Lu, Xia and Pierce, Eric M. and Gu, Baohua},
abstractNote = {In natural freshwater and sediments, mercuric mercury (Hg(II)) is largely associated with particulate minerals and organics, but it remains unclear under what conditions particulates may become a sink or a source for Hg(II) and whether the particulate-bound Hg(II) is bioavailable for microbial uptake and methylation. In this study, we investigated Hg(II) sorption–desorption characteristics on three organo-coated hematite particulates and a Hg-contaminated natural sediment and evaluated the potential of particulate-bound Hg(II) for microbial methylation. Mercury rapidly sorbed onto particulates, especially the cysteine-coated hematite and sediment, with little desorption observed (0.1–4%). However, the presence of Hg-binding ligands, such as low-molecular-weight thiols and humic acids, resulted in up to 60% of Hg(II) desorption from the Hg-laden hematite particulates but <6% from the sediment. Importantly, the particulate-bound Hg(II) was bioavailable for uptake and methylation by a sulfate-reducing bacterium Desulfovibrio desulfuricans ND132 under anaerobic incubations, and the methylation rate was 4–10 times higher than the desorption rate of Hg(II). These observations suggest direct contacts and interactions between bacterial cells and the particulate-bound Hg(II), resulting in rapid exchange or uptake of Hg(II) by the bacteria. The results highlight the importance of Hg(II) partitioning at particulate–water interfaces and the role of particulates as a significant source of Hg(II) for methylation in the environment.},
doi = {10.1021/acs.est.8b06020},
journal = {Environmental Science and Technology},
number = 5,
volume = 53,
place = {United States},
year = {2019},
month = {1}
}

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This content will become publicly available on January 31, 2020
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