OBSERVATIONS OF ICE AND ITS SEDIMENTS ON THE BALTIC SEA COAST

Ice samples were taken in winter 1996 for determining the quality and quantity of sediment inclusions (suspended matter). The study area was the coast of the Gulf of Finland in the Baltic Sea. The data are from 13 sites and include for the water fraction of a melted ice sample pH , electric conductivity and soluble matter, and for the suspended matt er within the ice include the total mass, organic proportion and conce ntrations of some chemical elements. Three lakes were sampled for regi onal freshwater references. The soluble matter was mainly due to the s alts in sea water acid amounted to around 1 g/l (25-50% of the water s alinity), and the pH was 4.0-7.5. The sediment content was mostly 1-10 mg/l; larger values resulted from industrial and traffic fallout on i ce and snow and from sea bottom sand. Of toxic metals, lead and zinc s howed enriched concentrations in ice and snow. The snow cover was also investigated and the result was close to those of the ice samples, bu t the pH and amount of soluble matter was lower in the snow. A potenti al ecological risk exists in spring as the ice and snow meltwater, wit h possibly a very low pH and enriched in pollutants, is mixed with the surface water layer. This layer is particularly thin beneath the fast ice zone.