Determination and evaluation of natural radioactive nuclides in drinking water from selected water supplies of the Erzgebirge and the Vogtland regions

Investigations have been carried out to determine the natural radionuclide content of drinking and raw waters, in water supplies of the Erzgebirge and the Vogtland region. The maximum concentration values for the typical nuclides have proved to be lower than the concentration levels published in 1995 by the German Commission on Radiological Protection (SSK) for waters which are possibly susceptible to influences from uranium mining. Taking into consideration the nuclides Pb-210, Po-210, Ra-226, U-234, U-238, and Th-232, the average annual ingestion dose totals 20 mu Sv for infants, and 15 mu SV for adults, which is relatively low compared to the other pathways of natural radiation exposure. Under application of conservative assumptions, the annual ingestion dose can reach 480 mu Sv and 360 mu Sv, respectively. The dose-predominate nuclides are usually Ra-226 and Pb-210. The reduction of concentrations of natural radionuclides in drinking water, which is achieved through the treatment of raw waters in water works is usually low. It decreases in the following order: Pb-210, Ra-226, Po-210, thorium isotopes, uranium isotopes.