Review of contaminants in Baltic sediments

The sediments offer a tremendous potential for the follow-up of the relative changes in the concentrations of the inorganic and persistent organic contaminants in the marine environment. Concentrations of harmful substances in water are known to be variable, depending on water exchange, season and hydrographical factors, while concentrations in biomaterial depend, among other things, on species, tissue type, age of the specimen, and the migration habits of the species. In peaceful net sedimentation areas, the sediments represent the local hydrodynamic regime, integrating the changes in the concentrations of persistent substances over a period of

time, the length of which depends on the sedimentation rate. While the rate of sedimentation depends on the season, it has a great tendency to remain constant over the years. In the Baltic Sea, the use of biota as a pollution indicator suffers from the drawback that, because of the strongly varying environmental conditions, only very few, if any, species are represented in all the subareas in at least roughly equal abundances. Due to the harsh conditions and low salinities in the northern areas, the species distribution and abundances differ greatly from those encountered in the southern parts of the Baltic Sea. This may affect the comparability of the results.