Information on the distribution of natural and artificial radioactive nuclei and the level of their radiation in the environment is very important for assessing the health effects of people living in a given region. Recently, In addition to natural radioactive elements, artificial radioactive elements such as 137Cs, produced by human processes such as nuclear weapons testing, etc., increased the radioactivity of the environment. This study aimed to determine the specific activity of radionuclides in the water and surrounding soils around the tributaries of the Qarasu River in the north of Iran, in the mountains of Golestan Province, along the Drazno River, by gamma spectroscopy method using high purity germanium (HPGe) detectors. The average specific activity of 226Ra and 232Th in soil samples was lower and in the case of 40K close to the world average. The mean concentration of 137Cs activity in soil samples not adjacent to the waterway is higher than in soil samples in the watercourse, this may be due to the dissolution of cesium salt in the water and its transfer to the Gorgan Gulf. The concentration of thorium and potassium in the water is significant, therefore these elements are carried by the waters into the Gorgan Gulf and form thorium and potassium salts and finally settle in the Gulf. Raeq values for all samples were found to be generally lower than the world average value of 131.69 Bq/kg. The air absorbed dose (42.19 nGy/h) and the external annual effective dose (0.05 mSv/y) were lower than the world average. Soil radiation in this area does not pose a health risk.
