Mercury methylation by anaerobic microorganisms in the oxic water column of a deep lake
Methylmercury is a neurotoxin mainly produced by strictly anaerobic microorganisms in anoxic aquatic environments such as lake sediments, wetlands or rice paddles. However, recent observations indicate that this process may also occur in the water column of marine and freshwater environments, albeit under oxic conditions overall, which seems counter intuitive.
The present study demonstrates the presence of methylmercury in the oxic water column of Lake Geneva. Its likely origin is the production of methylmercury by microorganisms inside the aggregates (lake snow) present in the water column, these aggregates presenting anoxic conditions in their interior, a micro-environment favorable to methylators. These particles forming the lake snow are probably a major entry point of methylmercury into the lake’s food chain.
Gallorini, A., et Loizeau, J.-L., 2022, Lake snow as a mercury methylation micro-environment in the oxic water column of a deep peri-alpine lake: Chemosphere, 299, 134306.
2 Apr 2022