Concentrations of Cd, Cu, Ni, Pb and Zn in various aqueous and biotic media in four small forested catchments located throughout Finland (61–70°N) are presented. The data has been collected (1989–96) as part of the UN-ECE Integrated Monitoring programme. Aqueous media included: bulk (open) precipitation, throughfall, stemflow, soil water, groundwater, and lake and stream waters. The biotic media included: moss (Pleurozium schreberi), needles (Pinus sylvestris), litterfall, humus layer, red wood ants (Formica aquilonia and F. lugubris), and common shrew (Sorex areneus) liver. In comparison to temperate ecosystems, the concentrations of each metal in all media were low. Levels and bioaccumulation of Cu and Zn were clearly affected by their role as micro-nutrients and, in the case of Zn at one of the catchments, by local lithological sources. Humus layer and surface water 95th percentile concentration values were below lowest effect values. Concentrations of Pb have significantly declined over the study period
