[Radioactive contamination of cistern waters along the Croatian coast of the Adriatic Sea].

Measurements of radioactive contamination of cistern waters with 90Sr, 134Cs and 137Cs have been carried out along the Croatian coast of the Adriatic Sea. An exponential decline of radioactivity followed the moratorium on nuclear tests. After the nuclear accident at Chernobyl, high radioactivity levels were detected again. The pre-Chernobyl and the post-Chernobyl mean residence times of 90Sr in cistern waters reflect the mechanism by which strontium was released to the atmosphere (atmospheric nuclear weapon tests conducted in the stratosphere or explosions in the Chernobyl nuclear reactor releasing radioactive material to the troposphere). For the pre-Chernobyl period, the mean residence time of 90Sr in cistern waters was similar to that calculated for fallout, being approximately 10 years. The post-Chernobyl 137Cs/90Sr activity ratio has been decreasing, but it has not yet reached the pre-Chernobyl values (approximately 1.6). The time-dependent 134Cs/137Cs activity ratio reflects the Chernobyl reactor inventory of these radionuclides. The annual dose for the critical adult population received from 90Sr, 134Cs and 137Cs by consumption of cistern water was estimated to be a few percentages of the dose from natural background radiation.