Trace Metals in Finnish Headwater Lakes — Effects of Acidification and Airborne Load

Abstract

The study on the effects of acidification and airborne load on the concentrations of some trace metals (Al, Mn, Cd, Cu, Pb, Zn, Ni, Hg) in sediments (16 lakes), water (259 lakes) and aquatic fauna (14 lakes) of pristine Finnish headwater lakes was conducted in 1985–1989. Atmospheric trace metal load and concentrations in the water and in the sediments were higher in southern Finland than in central and northern Finland. The share of anthropogenic load according to sediments varied from 62 to 95% for Cd, Hg and Pb, was from 39 to 91% for Zn and varied from 0 to 84% for Ni and Cu in southern and central Finland. Anthropogenic load could be explained by atmospheric deposition. Acid conditions favoured high concentrations of Al, Mn, Zn, Pb and Cd in water and high concentrations of Pb, Cd, Zn, Cu and Ni in aquatic plants. Lead concentrations were usually one order of magnitude higher in liver and bones of fish from acidic lakes than in circumneutral lakes. Cadmium in liver, Hg in muscle and Al in gills also showed increased concentrations in several fish species in acidic lakes.