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(T/EH090) Pollution of drinking water resources. Pastare, Silvija1, Zilbere, U.1, 1 ABSTRACT- As about 60% of the drinking water production for Riga, the capital of Latvia is coming from Baltezers Area and for many reasons the withdrawn quantity should be increased in the near future, great attention must be paid to the consequences of the existing pollution evolution influencing the drinking water quality. The present and future of Riga Drinking Water Supply is for an important part connected with eutrophication factors in the Baltezers lakes system. At present 30-40% from all the obtained groundwater is under the influence of quality of Lake Mazais Baltezers. The water quality of Lake Mazais Baltezers creates the quality of supplement ground water. The level of organic compounds is on the increase in addition to high level of mineralization. Groundwater increase occurs through the infiltration basins and they are located 200-300 m from the wells. Every day 40-80th m3 of water are pumped from the lake Mazais Baltezers to infiltration basins. From the basins the water filters through the sand layer in a natural way. At present the lakes of this system are characterised by rapid increase of the sludge layer (from gathering of organic matters) and intensive development of pfytoplancton. The development of phytoplancton in the lakes depends on the physical conditions as well as on the amount of nutrients. During the all vegetation season a high concentration of nitrogen and phosphorus in lakes was observed. Marine waters from Riga Gulf have driven in the lakes and mineralization level is considerably increased. In both lakes sodium is dominating among the cations. Key words: lakes, eutrophication, drinking water |
