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Quantification of Mercury Bioavailability for Methylation Using Diffusive Gradient in Thin-Film Samplers
Udonna Ndu1, Geoff A Christensen2, Nelson A Rivera1
1Department of Civil and Environmental Engineering , Duke University , Box 90287, Durham , North Carolina 27708 , United States.
Environmental Science & Technology
|June 20, 2018
Summary
Quantifying bioavailable mercury (Hg) is crucial for managing contaminated sites. Diffusive gradient in thin-film (DGT) passive samplers effectively indicate mercury
Area of Science:
- Environmental Chemistry
- Environmental Science
- Microbiology
Background:
- Mercury contamination in sediment and water poses risks due to its conversion to the neurotoxin methylmercury (MeHg).
- Accurate quantification of bioavailable mercury is essential for effective risk management and site prioritization.
Purpose of the Study:
- To compare the effectiveness of diffusive gradient in thin-film (DGT) passive samplers against traditional methods (glutathione extraction and filtration) in assessing mercury bioavailability.
- To evaluate DGTs as a tool for quantifying the bioavailable mercury fraction that can be converted to MeHg by microbes.
Main Methods:
- Anaerobic sediment slurry microcosms were used with isotopically labeled inorganic mercury species.
- Diffusive gradient in thin-film (DGT) passive samplers, glutathione (GSH) extraction, and <0.2 μm filtration were employed to measure mercury.
- Methylmercury (MeHg) production was monitored over one week, and hgcA gene abundance was assessed.
Main Results:
- Mercury accumulation on DGTs correlated with net MeHg production.
- Traditional filtration and GSH extraction methods showed inconsistent correlations with MeHg production.
- Methylating microbial community assessment via hgcA gene abundance did not consistently predict methylation rates.
Conclusions:
- Diffusive gradient in thin-film (DGT) passive samplers show promise for quantifying bioavailable inorganic mercury, indicating its potential for microbial methylation.
- DGTs can serve as a valuable tool for assessing net MeHg production potential at contaminated sites.
- Further research should focus on microbial transcript or protein levels for a more accurate assessment of methylation activity.
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