Factors that affect the situation

 
At present, the Baltic Sea is being burdened mostby the nutrient loadings and hazardous substances that have entered and are entering the sea, and also the greatly increased amount of shipping.

Eutrophication is caused by the activities of people, such as community wastewater, agriculture, scattered settlements, traffic, energy production, and industry. Research has shown that the wastewater from the St Petersburg area affects the entire open sea area of the Gulf of Finland, whereas the poor condition of our coastal waters is mainly due to domestic emissions.

From 1997 – 2001, the total amounts of nutrients entering the Baltic Sea were 35,000 tons of phosphorous and 650,000 tons of nitrogen. During the same period, Finland’s share of the overall nutrient loading entering the Baltic Sea from rivers and from wastewater amounted to 10%.

From Finland’s land area, an average of 3,000 tons of phosphorous and 42,000 tons of nitrogen enter the Baltic Sea each year as a result of people’s activities. When the airborne nutrient deposition and natural leaching are also taken into account the annual phosphorous loading is 4,200 tons and that of nitrogen is 84,000 tons. In comparison with the loadings from 1992 to 1996, the amount of phosphorous has remained approximately the same, but the amount of nitrogen has risen by 8,000 tons.

Agriculture is the most significant loading source for Finnish coastal waters, and its significance is underscored in the reduction of point loading sources of nutrient emissions. From 1997 – 2001 agriculture accounted for almost half of the phosphorous loading and over one third of the nitrogen loading. The share from agriculture in the Helsinki and Turku areas is even greater. The share from agriculture in the Helsinki area is over one half for both phosphorus and nitrogen loading, and in the Archipelago up to three quarters.

Industry, fish farming and residential centres are also significant sources of nutrients, although there has been a significant reduction in the phosphorous and nitrogen loading from these sources during the last twenty years. The living organisms and seabed sediment of the Baltic Sea accumulate large amounts of hazardous substances in comparison with the oceans. This is due the high loading of the Baltic Sea, unfavourable conditions for decomposition, and also the low water exchange. The discharges of hazardous substances into the Baltic Sea mainly come from community and industry wastewater, and from runoff waters. In addition to this, there are also airborne depositions of emissions.

Heavy metals are also carried directly into the sea along with the emissions from industrial plants, but also as diffuse loadings. Heavy metals affect the growth, reproduction and activity of living organisms. The amounts of heavy metals have decreased over the last twenty years, but the values are still significantly higher than in the North Sea, for example.

Heavy metal emissions from industry are generally concentrated in the coastal waters close to the factories. Heavy metal loading from river waters, however, spread more evenly over a larger area, and is tens of times greater than industrial emissions. Heavy metals accumulate in the sediment and seabed layers, from where they can move back into the Baltic Sea food web. For example, dredging and the disposal of dredging waste transfer the heavy metals accumulated in the seabed back to the water.

There are tens of thousands of different chemicals in use, and for only a small proportion of these is there any basic information in terms of assessment of environmental impact. Furthermore, the combined impact of various substances is often unknown. There has been a great deal of research into the effect of environmental poisons on living organisms. Poisons cause, for example, deformities in fish, and weaken the ability of shellfish to catch prey. One example that can be mentioned of the problems caused by hazardous substances is the high dioxin concentrations in Baltic herring.

Although the amount of certain environmental poisons has decreased, environmental poisons continue to accumulate in the living organisms of the Baltic Sea. Accurate information on the concentrations of hazardous substances in the Baltic Sea only exists for some of the most significant organic materials and for some heavy metals.

A large part of the oil in the Baltic Sea has come from land, river waters and the air. These oil emissions mainly pollute the sediment, but also the entire Baltic Sea ecosystem. The continuously growing volume of tankers has considerably increased the environmental risks and the risk of an accident in the Baltic Sea. Furthermore, deliberate discharging of oil into the Baltic is continuously happening. There are also over 1,000 wrecks with oil storage in the Finnish marine area.

The natural balance of the Baltic Sea is being shaken by the increased amount of shipping, and by boating and recreational activity. Problems are also caused by the construction of bridges, harbours and fairways, removal of sand from the seabed, and other activities being carried out in the Baltic Sea area, for example, the excavation of sea sand causes changes to the underwater landscape, the depth relationships, and the currents.