Biogeochemical pathways of arsenic in lakes

Owing to various human activities, arsenic (As) concentrations have increased in lakes and other aquatic ecosystems around the world. This increase of As concentrations has become a concern because of the known toxic, carcinogenic, mutagenic, and teratogenic effects of As on ecosystem organisms and humans. Understanding the biogeochemistry of As in the aquatic environment is therefore a topic of fundamental interest. This study presents a review of the major biogeochemical processes controlling the concentration of solid and dissolved As in freshwater lakes. These processes are dynamic and vary both temporally and spatially because of a complex relationship between microbial activity and various geochemical processes. Particularly the oxidation of As sulphides and the reduction of Fe and Mn oxyhydroxides at the sediment–water interface play an important role in the mobilization of As. These and other interactions among the various biogeochemical processes are synthesized in a conceptual model of As mobility in lakes.Key words: arsenic cycling, biogeochemistry, freshwater lakes.