Lead, cadmium and other metals in scandinavian surface waters, with emphasis on acidification and atmospheric deposition

Long-range atmospheric transport of pollutants affects the chemistry of heavy metals in natural waters in several ways. First, the direct atmospheric supply of some metals to lakes and their catchments may add strongly to the total burden of these metals in the lake ecosystems. Second, the acidity of the precipitation may enhance the metal fluxes by dissolution of metals originating from mineral material in the catchment or previously supplied by atmospheric deposition and fixed to surface soil or sediment. Furthermore, the acidification of surface waters interferes strongly with the speciation of the metals in the water. The southern part of Scandinavia is considerably influenced by long range atmospheric transport from other parts of Europe. The present paper is a review of recent work in this region related to the occurrence and chemical behavior of lead, cadmium and other trace metals in natural surface waters, with emphasis on the supply from atmospheric deposition. The impact of acidification on the mobility and chemical speciation of the metals is briefly discussed.