Copper in Scots pine forests around a heavy-metal smelter in south-western Finland

Abstract

Distribution and fluxes of copper within Pinus sylvestris stands were studied during 1992–1994 along a heavy-metal pollution gradient in south-western Finland. The stands are situated at distances of 0.5, 4 and 8 km from a copper-nickel smelter that started operating in 1945 at Harjavalta. According to the results, copper concentrations in the soil, in the understorey vegetation and in the trees increased steeply towards the smelter. Almost 50 years' accumulation of heavy metals in the soil has caused direct toxic effects to soil microbes, thus decreasing decomposition and nutrient mineralisation. During the past few years, sulphur and heavy metal emissions from the copper and nickel smelter have been radically decreased. However, the heavy metals which have been accumulating in the soil for decades continue to affect the vegetation for a long time through soil processes. Consequently, long-term accumulation in the soil has to be taken into account when determining the critical loads of forest ecosystems for heavy metals.