An assessment of Hg in the freshwater aquatic environment related to long-range transported air pollution in Europe and North America (ICP Waters report 97/2009)

Long-range transboundary atmospheric transport of the pollutant mercury (Hg) (LTRAP-Hg) poses an ecological threat to aquatic ecosystems and biota. Through fish consumption, mercury and its highly toxic and bioaccumulative organic form methylmercury (MeHg) may cause harmful effects on human health. Factors controlling the bioaccumulation of Hg in aquatic ecosystems are not well understood. In Scandinavia an increased content of Hg in piscivorous fish has been observed the last decade. Today, legislation and guidelines on concentration levels of Hg for fish retail and private consumption are in place in most countries and the utility of the fishery as a resource is reduced. This report gives an overview of : - relevant international agreements on Hg pollution - factors that drive the spreading and accumulation of Hg in the environment - current knowledge on the status of LRTAP Hg in freshwater aquatic ecosystems (fish, sediments, water) within the UNECE region (North America and Europe). recommendations for an outline of a monitoring network suitable for assessing the distribution and effects of LTRAP-Hg in freshwater aquatic environments.