Radioactivity of Drinking Waters from Different Regions of Bulgaria in the Period 2017-2019

Radioactivity of drinking waters is determined by trace quantities of natural radionuclides 238U, 232Th, their daughter products and 40K. They are transferred to water by processes of erosion and dissolution of aquifer rocks and minerals. Man-made radionuclides may also occur in water as a result of technological pollution. Therefore, annual radiological monitoring is a key factor in ensuring water safety. In the present study, radiological monitoring of drinking waters from different regions in Bulgaria was carried out according to the national regulations in the period 2017-2019. Content of natural uranium, gross alpha and beta activity, radon-222 and tritium in water samples were determined. Content of radiological indicators under study was not exceeding the reference values in the predominant part of analyzed samples. Relatively higher values of natural uranium and gross alpha activity were observed in insignificant number of samples, probably due to specific hydro-geological characteristics of the aquifers in the respective regions, as well to the presence of closed uranium mining sites near them. Content of radon and tritium in all tested waters were below the parametric values. As a result of the present survey it can be concluded that drinking waters in the studied regions were not hazardous for human health from radiological point of view.