Abstract
Mercury (Hg) contamination of soils and sediments impacts numerous environments worldwide and constitutes a challenging remediation problem. In this study, we evaluate the impact of dissolved organic matter (DOM) on the effectiveness of eight sorbent materials considered for Hg remediation in soils and sediments. The materials include both engineered and unmodified materials based on carbon, clays, mesoporous silica and a copper alloy. Initially, we investigated the kinetics of Hg(II) complexation with DOM for a series of Hg:DOM ratios. Steady-state Hg-DOM complexation occurred within 48 to 120 h, taking longer time at higher Hg:DOC (dissolved organic carbon) molar ratios. In subsequent equilibrium experiments, Hg(II) was equilibrated with DOM at a defined Hg:DOC molar ratio (2.4 · 10−6) for 170 h and used in batch experiments to determine the effect of DOM on Hg partition coefficients and sorption isotherms by comparing Hg(II) and Hg-DOM. Hg sorption capacities of all sorbents were severely limited in the presence of DOM as a competing ligand. Thiol-SAMMS®, SediMite™ and pine biochar were most effective in reducing Hg concentrations. While pine biochar and lignin-derived carbon processed at high temperatures released negligible amounts of anions into solution, leaching of sulfate and chloride was observed for most engineered sorbent materials. Sulfate may stimulate microbial communities harboring sulfate reducing bacteria, which are considered one of the primary drivers of microbial mercury methylation in the environment. The results highlight potential challenges arising from the application of sorbents for Hg remediation in the field.
Original language | English |
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Pages (from-to) | 410-416 |
Number of pages | 7 |
Journal | Science of the Total Environment |
Volume | 690 |
DOIs | |
State | Published - Nov 10 2019 |
Funding
The authors would like to thank Christian Lee and Valerie Garcia-Negron for assistance with sample preparation and analysis. This research was supported in part by URS|CH2M Oak Ridge LLC (UCOR) and the Mercury Technology Development Program at Oak Ridge National Laboratory (ORNL) with funding by the Oak Ridge Office of Environmental Management, U.S. Department of Energy (DOE). ORNL is managed by UT-Battelle, LLC, for DOE under Contract No. DE-AC05-00OR22725. D.P.H. also acknowledges support from the USDA National Institute of Food and Agriculture Award 2017-67021-26599 and Hatch Project 1012359. The authors would like to thank Christian Lee and Valerie Garcia-Negron for assistance with sample preparation and analysis. This research was supported in part by URS|CH2M Oak Ridge LLC (UCOR) and the Mercury Technology Development Program at Oak Ridge National Laboratory (ORNL) with funding by the Oak Ridge Office of Environmental Management, U.S. Department of Energy (DOE). ORNL is managed by UT-Battelle, LLC, for DOE under Contract No. DE-AC05-00OR22725. D.P.H. also acknowledges support from the USDA National Institute of Food and Agriculture Award 2017-67021-26599 and Hatch Project 1012359.
Funders | Funder number |
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Oak Ridge Office of Environmental Management | |
UCOR | |
URS | |
U.S. Department of Energy | |
U.S. Department of Agriculture | |
National Institute of Food and Agriculture | 1012359, 2017-67021-26599 |
Oak Ridge Associated Universities | |
Oak Ridge National Laboratory |
Keywords
- Contamination
- Mercury
- Organic matter
- Remediation
- Sorbents