Mercury in Nordic Freshwater Fish: An Assessment of Spatial Variability in Relation to Atmospheric Deposition

Data on mercury levels in freshwater fish (mainly pike, perch, trout and char), from Norway, Sweden and Finland have been collected in a common database to assess spatial patterns as well as relationships with environmental factors such as atmospheric mercury deposition. A preliminary evaluation of fish Hg data from >1500 lakes shows that Hg levels referring to a 1-kg pike are highest in low-altitude lakes of the southern regions S. Norway, S+C. Sweden, and C. Finland, where regional medians are 0.5-0.8 mg/kg fw. In these regions, about 50-80 % of the lakes exceed 0.5 mg/kg and about 520(40) % of the lakes exceed 1.0 mg/kg. Fish Hg levels in high-altitude lakes are lower than in low-altitude lakes in the corresponding region.