Contribution of liquid wastes from Beloyarsk NPP to contamination of Pyshma river basin in the Urals

Institute of Plant and Animal Ecology of Ural Division of Russian Academy of Sciences, 8 Marta Street 202, 620219 Ekaterinburg, Russia

Abstract

We studied the distribution of radionuclides in the components of the swamp-river ecosystem into which weakly radioactive debalance water from the Beloyarsk nuclear Power Plant was discharged during 35 years. We estimated the influence of this ecosystem on the Olkhovka and Pyshma rivers connected with the swamp in the same hydrographic system. During operation of 3 units of the power station the content of ⁶⁰Co, ⁹⁰Sr and ¹³⁷Cs in the swamp water was 2.5, 0.7 and 15.6 Bq l^-1 respectively. Concentration of ⁶⁰Co and ¹³⁷Cs in the sediments of the ecosystem under study was units and tens of kBq kg^-1 dry weight respectively, while concentration of ⁹⁰Sr was only tens - hundreds of Bq kg^-1 dry weight. According to calculations about 3.7·10¹²Bq has deposited in bottom sediments. When the first two units of the power station were out of operation the content of radionuclides in the water and sediments decreased significantly as a result of a decreased discharge, natural radioactive decay and the washout into the river system. ¹³⁷Cs was the main pollutant of the Olkhovsk swamp-river ecosystem. Significant quantities of this radionuclide were discovered in bottom sediments of the Pyshma 50 km from the pollution source.