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Is the methylmercury paradox real ?


The authors hypothesize that such methylmercury accumulation paradox is explained by the quantitative induction of bacterial enzymes by inorganic mercury (Hg(II)). The hypothesis was further investigated at two different surface water sites, and it was found that bacteria that efficiently break down methylmercury thrive in the waters of the more contaminated site but are largely absent at the more prestine site. By demethylating mercury, these bacteria can significantly reduce the uptake of mercury into the food web and hence into fish. The action of the water column bacteria may well serve as a kind of natural mercury defense mechanism, reducing the proportion of the methylated mercury. The authors also showed that the absolute concentration of methylated mercury in contaminated water is still higher than in pristine waters.

Michael Sperling

 Original article

 Jeffra K. Schaefer, Jane Yagi, John R. Reinfelder, Tamara Cardona, Kristie
M. Ellickson, Shoshana Tel-Or, Tamar Barkay, Role of the Bacterial Organomercury Lyase (MerB) in Controlling Methylmercury Accumulation in Mercury-Contaminated Natural Waters, Environ. Sci. Technol., 38/16 (2004) 4304-4311. DOI: 10.1021/es049895w

Related information

University of Montana: Biomethylation of metals and metalloids
 EPA - Mercury home page - General information
 EPA - Methylmercury in fish and shellfish
 More about mercury

 Related EVISA Resources

Link Database: Environmental cycling of methylmercury
Link Database: Environmental cycling of inorganic mercury
Link Database: Environmental pollution of methylmercury
Link Database: Environmental pollution of inorganic mercury

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last time modified: June 24, 2020


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