A multi media load model for the Baltic Sea

The background of this work is the international decision process with rega rd to the selection of chemicals to be assessed with priority In order to s tress the precautionary principle, mass flows were analysed rather than con centrations, threshold values, etc., as preferred by the chemical legislati on (which still excludes the marine area). Lindane, hexachlorobenzene (HCB) , trichloroacetic acid and its sodium salt, medium-chained chlorinated para ffins and tributyltin (TBT) were selected due to their great relevance for the marine area. Trichloroacetic acid is an interesting model compound on a ccount of its accidental formation by degradation of volatile chlorinated h ydrocarbons and during chlorination processes. In addition, a hypothetical compound was modelled, representing a highly water-solubte substance with l ow vapour pressure. The balancing area is the Baltic Sea and its catchment area. In order to model the substance flows, the 'Input/Output-load model' has been developed. The model quantifies the shift and the distribution of a yearly load of the substance investigated from the terrestrial-limnic int o the marine compartment (Baltic Sea). Water-soluble substances, which are usually considered to be of no concern, may enter the sea in great amounts and, if not degradable, remain there. It turned out to be necessary to take into account remobilisation, unintended formation and point as well as lin e-sources.