Environmental dose rate distribution along the Romanian Black Sea Shore

The ambient dose rate distribution, measured along the Southern sector of Romanian Black Sea shore, between Vama Veche in South and Chituc sandbank in North gave, with some notable exception, values between 34 and 54 nSv/h, lower than the 90 nSv/h, the average value for Romania. The experimental dose rates increase northward, reaching a maximum in the vicinity the Chituc sandbank, i.e. at the Vadu and Corbu beaches. According to gamma ray measurements performed in the Slanic-Prahova Low-Background Radiation Laboratory on the sand collected from the same location, the natural radionuclides have a major contribution to observes dose rate while the contribution of the anthropogenic 137 Cs, 26 years after Chernobyl accident, remains almost negligible. By taking into account both activity concentrations of radionuclides and the contribution of cosmic rays, we have calculated the local values of dose rate, which showed to be, within experimental uncertainties, coincident with the experimental ones. Moreover, on Chituc sandbank, we have noticed the presence of some local maxima, two to three times higher than the average ones. Further investigations showed an increased content of natural radionuclides, most probably accumulated in the heavy minerals fraction—a common occurrence in the vicinity of Danube Delta.