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Mercury methylation by fish intestinal contents
Applied and Environmental Microbiology
|October 1, 1980
Summary
Fish intestinal contents can convert inorganic mercury (203Hg2+) into methylmercury (CH3203Hg+), challenging previous assumptions. This mercury methylation process, likely bacterial, occurs in various fish species regardless of environmental mercury levels.
Area of Science:
- Environmental Chemistry
- Aquatic Toxicology
- Microbiology
Background:
- Mercury methylation is a critical process in aquatic ecosystems, influencing mercury's bioavailability and toxicity.
- Previous research suggested limited or no mercury methylation occurs within fish intestines.
Purpose of the Study:
- To investigate the potential for mercury methylation within the intestinal contents of freshwater fish.
- To identify factors influencing mercury methylation activity in fish guts.
Main Methods:
- A novel radiochemical method using 203Hg2+ was employed to detect mercury methylation.
- Intestinal contents from six freshwater fish species across six lakes were analyzed.
Main Results:
- Six freshwater fish species demonstrated the capacity to convert inorganic mercury (203Hg2+) to methylmercury (CH3203Hg+).
- Methylation activity was detected in fish from five of six lakes, irrespective of mercury pollution.
- Bacterial activity is the presumed driver of this observed methylation.
Conclusions:
- Fish intestinal contents possess a significant capacity for mercury methylation, primarily driven by bacteria.
- This finding contradicts prior conclusions, indicating that fish can actively methylate mercury internally.
- Methylating activity varied among species and was inversely related to the quantity of intestinal contents.