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Updated: Jun 22, 2026
09:33
An Anaerobic Biosensor Assay for the Detection of Mercury and Cadmium
Published on: December 17, 2018
Is Clear Lake methylmercury distribution decoupled from bulk mercury loading?
Thomas H Suchanek1, Collin A Eagles-Smith, E James Harner
1Department of Wildlife, Fish and Conservation Biology, University of California, Davis, California 95616, USA. tsuchanek@usgs.gov
Summary
Mercury contamination at Clear Lake, despite high total mercury (TotHg) levels from an abandoned mine, shows low methylmercury (MeHg) in biota. Acid mine drainage, not bulk loading, drives MeHg production, suggesting current mercury load reduction strategies may be flawed.
Area of Science:
- Environmental Science
- Geochemistry
- Ecotoxicology
Background:
- Clear Lake, California, is contaminated by mercury (Hg) from the abandoned Sulphur Bank Mine (1873-1957).
- Sediment and water exhibit some of the world's highest total mercury (TotHg) concentrations.
- Biota show lower methylmercury (MeHg) than expected, indicating decoupled methylation from inorganic Hg loading.
Purpose of the Study:
- Investigate the factors controlling mercury methylation and bioaccumulation in Clear Lake.
- Evaluate the effectiveness of current mercury load reduction strategies.
- Compare mercury methylation patterns with other contaminated sites globally.
Main Methods:
- Analysis of mercury speciation (TotHg and MeHg) in sediments, water, and biota.
- Assessment of environmental factors influencing mercury methylation (e.g., pH, lake depth, organic matter).
- Comparison of MeHg:TotHg ratios across different contaminated sites.
Main Results:
- Methylation appears decoupled from bulk inorganic Hg loading; acid mine drainage (AMD) is a significant driver of MeHg production.
- Lake characteristics (alkalinity, depth, productivity) influence MeHg levels.
- Cinnabar/metacinnabar mines show lower MeHg production than chloralkali or gold/silver mine sites.
Conclusions:
- Current total mercury load reduction strategies for Clear Lake may be ineffective as they don't target the bioavailable form, methylmercury.
- Understanding the specific sources and pathways of methylmercury production is crucial for effective remediation.
- Lake limnology and mine type significantly impact mercury bioaccumulation dynamics.
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