7 years of monitoring of 40K in surface water samples from Olt River, Romania

The aim of this study was to determine naturally occurring radionuclide 40K in surface water samples from Olt River, Romania. A monitoring study during 7 years (2012-2018) was accomplished. A number of 728 surface water samples were collected and analysed. Several hundred pollution sources were identified for the Olt River basin in Romania. This study is of particular importance since it is the first effort to evaluate the activity concentrations of 40K in surface water from Romania for such a long period. For this reason, two sampling points along the Olt River were chosen, the first one upstream of the discharge point of the magistrate channel "Deversor Olt" (reference location) and respectively the second sampling point downstream of the liquid effluents discharges point (indicator location). The radioactivity concentration of 40K was determined from the 1460.8 keV photopeak. The method used was high resolution gamma ray spectrometry performed with a hyperpure germanium detector. An activity concentration for 40K, no more than 2.14 ± 0.32 Bq l -1 , is observed, but the values recorded for the background location had a slight, but not significant difference compared with the values recorded in the second sampling point.