Bornholm Basin
Bornholm Basin |
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It is estimated that annual average pollution loads carried by the Odra/Oder at the mouth of the lagoon are some 56 000 tons of BOD, (23 percent of total discharges in the basin), 24 000 tons of tot-N (21 percent), 7 000 tons of tot-P (44 percent), 920 tons of heavy metals (59 percent) and 2 630 000 tons of chlorides and sulfates (100 percent). It should be noted that the river still has a significant self-purification potential and that sedimentation of heavy metals is significant (almost all of them are deposited in the Odra/Oder River below its confluence with the Warta). The pollution loads reaching the Baltic are less than the above values due to the effect of the lagoon.
On the Polish coast, several large cities discharge their wastewaters directly to the sea. Four coastal municipalities are in the category of 50 000 to 500 000 p.e.: Szczecin (no wastewater treatment or mechanical treatment only), Swinoujscie (mechanical treatment), and Koszalin and Kolobrzeg, (biological treatment). Five municipalities in the 10 000 to 50 000 p.e. category are provided mostly with mechanical treatment. Their total annual input to the Baltic Sea in the early 1990s was some 21 400 tons of BOD7, 3700 tons of tot-N, and 770 tons of tot-P.
Heavy loads of municipal wastewater are discharged into the Odra/Oder, particularly in the urbanized upper part of the basin where heavy industrial and mining activities are located, especially the Ostrava region in Czechoslovakia and Katowice region in Poland. Other large sources of municipal pollution are Wroclaw, Zielona Gora, Lodz; Poznan, the coastal city of Szczecin, and Gorlitz, Guben, and Frankfurt/O. Municipal systems discharge some 210 000 tons of BOD5 annually and are thus a major contributor to water pollution in the Odra/Oder basin. Although some 65 percent of sewage flows are treated, many treatment plants are old (average age in excess of 30 years), and BOD reduction efficiency is poor, on average only some 43 percent. Sludge disposal is also problematic in many regions.
Municipal wastes in the Odra/Oder basin are generated in quantities corresponding to 1.0 kg/inhabitant/day. Dump sites, which are by far the most usual method of disposal, are frequently filled close to capacity.
There are several industrial plants located on the Polish coast of the Baltic Sea. Most of the 8 fish and food processing plants are provided with mechanical wastewater treatment installations only. In addition, there are 5 chemical industry plants, 3 metal works, 2 energy and harbour installations, and 2 wood fibre plants. Total annual input of the Polish coastal industrial plants discharging their wastewaters to the Bornholm Basin is some 3450 tons of BOD7, 210 tons of tot-P (130 tons from the Police fertilizer plant), and 610 tons of tot-N.
The main culprits in industrial BOD discharges to the OdralOder river basin (about 32 000 tons annually) are food processing, forestry and textile industries. The fertilizer and steel industries located mainly in the Katowice area in Poland and Ostrava in Czech Republic, account for most of the nitrogen loads from industry. Phenols discharged by coke ovens and the chemical industry are a special problem; about 100 tons per year are released.
The large non-ferrous mining and foundry industries located in the basin, such as the copper complex at Legnica-Glogow, are major generators of heavy metals pollution. Accumulated refuse from many years of mining and metal working activities is also a source of sizeable, but not well quantified pollution by heavy metals. Solid wastes of industrial origin include large quantities of phosphogypsum from a phosphate fertilizer plant. Many dump sites, such as for coal mines, are not systematically identified, and this is likely to be a major problem in any clean-up effort. As regards recent trends, the decrease in activity observed in many industries, such as iron and steel works, has contributed to a lower level of emissions. However, economic difficulties have also exacerbated funding problems for investments in less polluting production processes.
With regard to air pollution, the Odra/Oder River basin region in Poland accounts for some 1.6 million tons per year of SO2 emissions (total country emission in 1988 was 4.3 million tons), some 360 000 tons of NOx emissions (country total 1.5 million tons), and 840 000 tons of particulate (country total 3.4 million tons). Much smaller, although still significant quantities of airborne pollutants are emitted in the Ostrava region of the Czech Republic. The largest emitters are enterprises often run on high sulphur coal. Approximately 50 percent of the sulphur and 6 percent of the nitrogen thus emitted to the air are deposited in the basin. However, it is estimated that Polish air pollutant emissions only account for some 20 to 30 percent of total deposits in the Odra/Oder basin. The major contributions come from the Czech Republic and from outside the basin area. Because of reconstruction and shutdowns in the industrial sector of the new Länder, Germany’s contribution to airborne deposition in the Odra/Oder catchment area decreased significantly over the last two years.
A comparison of heavy metal pollution flows from airborne deposition and from waterborne sources shows that the quantities are of the same order of magnitude (some 100 to 300 tons per year each). However. it should be remembered that only a small fraction of airborne heavy metal deposits ends up in the Odra/Oder due to runoff, estimated at 5-7 percent of the total.
In the Odra/Oder river basin, by the end of the 1980s about 30 000 tons per year of N and 1 100 tons per year of phosphorus were leached from farming operations. Recently, however, agriculture has been strongly influenced by economic factors. The increase in fertilizer prices has caused a decrease of N emission over the past few years in excess of 50 percent, although it can be expected that former fertilizer consumption levels will again be reached in the longer term. The situation is similar for pesticides.
Substantial inputs of nutrients by agriculture, industries and municipalities. A large proportion of the pollution load reaches Bornholm Basin by atmospheric deposition. This is estimated to be on the order of 55 000 tons per year for nitrogen and 600 tons per year for phosphorus. There is a substantial deposition of heavy metals. Information on pesticide residues is lacking.
Source: The Baltic Sea Joint Comprehensive Environmental Action Programme. Helsinki, 1993. (Balt. Sea Environ. Proc. No. 48), pp. 3-11 - 3-14
