Radioisotopes in the ground water

Isotopical methods are applied for investigation of various processes in the hydrosphere. Hydrodynamical, genetical, temporary parameters of underground and surface water are determined by these methods. Some of the most widely applied isotopes are: radioactive isotope of hydrogen - tritium, radiocarbon, radiogenic helium. Technogenic radioisotopes are falling but to environment, too. There arises a new problem of investigations -radioecological. Since 1971 isotopical investigations of the hydrosphere are fulfilled by the Institute of Geology inn different regions of the Lithuanian Republic: the Baltic sea, zones of mineral water in surroundings of Druskininkai and Birshtonas, Rykantai hydrogeological net-work, the basin of Virinta river, the area of aquiferous complex of the upper Permian deposits in West Lithuania, the Karst massive in North Lithuania, the region of Ignalina atomic power plant (IAPP). At present time radioecological problems of the Ignalina APP are solved for the most part. There is arranged a control-net. In accordance with the results of investigations natural distribution of radioisotopes (3H, 14C) and helium in vertical and horizontal sections is determined. After isotopical hydrodynamical schemes (sections) of water-bearing horizons, schemes of time of water-exchange (or stable water) in water horizons, schemes of protection of water bearing horizons concerning pollutants are compiled. Applying these methods two main problems are raised: 1) intensive contamination of ground water in the area of depository of radioactive waste (concentration of tritium - 141500 TU); 2) accumulation of radioactive matter (tritium, in the first place) in the lake Drukshiai and in ground waters of its coastal zone. (author). 1 fig., 4 refs