Pathways and sources of hazardous substances
The main pathways of hazardous substances to the marine environment are industrial wastewater, municipal wastewater - discharged directly or transported in rivers- and atmospheric deposition. Water pollution is closely monitored by all coastal states, but the methods differ from country to country, and improvements are needed for identifying relevant hazardous substances.
Hazardous substances from industries are emitted from all stages of the product chain - from the raw material and the production processes, from the use of products and from the handling of products as waste.
Contaminants also originate from shipping. Special problems include the anti-fouling agents used in paints, and illegal oil releases.
Inputs from the atmosphere are still high, particularly where heavy metals are concerned. Considering the prevailing wind directions, these inputs probably originate in western Europe.
The loads of many hazardous substances selcted by HELCOM for priority action have been reduced by at least 50% since the late 1980s - mainly due to the effective implementation of environmental legislation, the substitution of hazardous substances with harmless or less hazardous substances, and technological improvements. In the new EU countries and Russia the reduction of pollution by hazardous substances in the beginning of the 1990 was largely due to the decline in economical activitiy. As the discharges, emissions and lossess from point sources such industries and mines have been substantially reduced the importance of emissions from diffuse sources, like consumer products, is increasing.
Heavy metals from the air
Annual emissions of heavy metals in the HELCOM countries decreased during the period 1996–2000, by 26% for cadmium, 15% for mercury and 10% for lead. These figures should be considered with some caution, however, because emission trends over this period were far from clear for most countries.
Heavy metals via rivers
The Gulf of Finland and the Baltic Proper receive the lion’s share of the riverine heavy metal loads entering the Baltic Sea. During the period 1994–2000 discharges of heavy metals (mostly cadmium and lead) decreased in most of the sub-regions.
Persistent organic pollutants (POPs)
Vast amounts of persistent organic pollutants have been released into the environment around the world. Due to long distance transportation by winds, POPs have spread and become a global contamination problem. Like heavy metals, POPs tend to accumulate in living organisms.
There have been substantial inputs of POPs into the Baltic Sea from numerous sources over the past 50 years. These sources include industrial discharges, such as the organochlorines in effluent from pulp and paper mills, runoff from farmland, the special paints used on ships and boats, and dumped wastes. Several POPs, notably certain organochlorine pesticides such as DDT and technical grade HCH, have been completely banned since the 1980s.
For further information on hazardous substance inputs, see: