Radionuclide contamination in the Syrdarya river basin of Kazakhstan; Results of the Navruz Project

As part of an international collaboration (the Navruz Project) between Kazakhstan, Kyrgyzstan, Tajikistan, Uzbekistan, and the United States of America on transboundary river monitoring, the Radiometric Laboratory of the Institute of Physics in Kyrgyzstan measured the isotopic composition of uranium (as measured by g, the ratio of activities of 234 U/ 238 U) for the water of the Naryn River basin. This ratio varies from 1.5 to 1.9 due to natural causes. The results point to the lack of the technogenic uranium along the Naryn River through territory of the Kyrgyz Republic and to the contamination of the Mailuu-Suu River by technogenic uranium from tailing dumps in the area. The share of technogenic uranium transported to Uzbekistan does not exceed 30p, and the total uranium content is considerably lower than the maximum admissible concentration (MAC) and is almost an order of magnitude lower than that of potable waters of the Chui Valley of Kyrgyz Republic.