Assessment of radionuclide export from Chernobyl zone via birds 18 years following the accident

¹ Chornobyl Center for Nuclear Safety, Radioactive Waste and Radioecology, International Radioecology Laboratory, 07100 Slavutych, Ukraine
² University of South Carolina, Columbia, SC 29208, USA

Abstract

In 2003–2005 we investigated current contamination of small birds in Chornobyl zone, as vertebrates with the largest diversity and biomass, and inherent season migrations. A whole-body live counting method was used to analyze ⁹⁰Sr and ¹³⁷Cs in the birds. Total number and biomass of small birds was estimated using 1) data of birds population density in different kinds of biogeocenosis, 2) ratio of biogeocenosises area at the zone, 3) data of biomass of species. We used GIS application, an electronic map of the Chernobyl zone contamination and ⁹⁰Sr and ¹³⁷Cs transfer factor “soil–bird” to calculate average contamination of birds at any location regardless they had been caught there or hadn't. According to our assessment total number of small birds by the end of breeding season in 2004 amount to at least 5.14 million individuals, total biomass – 134 tons, total stock of radionuclides – 74.7 MBq ⁹⁰Sr and 55 MBq ¹³⁷Cs. All these birds can export no more 80% of their initial contamination outside the zone. Together with total avian flow yearly passed through the region (2600 km²) they export up to 2.47 GBq ¹³⁷Cs and 3.70 GBq ⁹⁰Sr.