spatial distribution of characterised fly-ash particles and trace metals in lake sediments and catchment mosses: Estonia

The principal cause of air pollution in Estonia was power production using fossil fuels, principally domestic oil shale. The concentrations of fly-ash particles and trace metals (lead, zinc, vanadium, cobalt, nickel, copper, cadmium) were determined in surface sediments from 42 lakes in Estonia in 1994-1995. Both spheroidal carbonaceous particles (SCP) and inorganic ash spheres (IAS) were measured in lake sediments. Trace metals levels were determined in moss (Hylocomium splendens and Pleurozium schreberi) from 34 sites. Fly ash particle concentrations and IAS levels were highest in lakes located near large oil shale fired thermal power plants and chemical industries. The highest concentrations of SCP were found in the central part of Estonia. High concentrations of trace metals in lake sediments were found in northern, north-eastern and southern Estonia. In mosses, the highest metal concentrations were found in western, south-eastern and central Estonia. The spatial distribution patterns showed that the deposition of airborne particulates was of local origin around pollution sources. The majority of the studied elements reached Estonia by long-range transport.