Cycling of Mercury in the Environment with Emphasis on the Importance of the Element in Acid Rain Studies

Information on mercury and its environmentally significant chemical forms in the biogeochemical cycle is presented. Components of this cycle considered include the atmosphere, hydrometeors, surface waters, soils and biota. The need for considering kinetic and mechanistic aspects of mercury chemistry in relation to the on-going environmental acidification is emphasized. Different sources of mercury emissions to air as well as mercury deposition rates are discussed, mainly based on the available Swedish data. Further, mercury budgets for oligotrophic lakes are proposed. It is demonstrated that there is a continuous accumulation of mercury in large forest regions. High concentrations of mercury in fish in oligotrophic lakes in such areas are generally due to the increased mercury supply and to increasing acidification.