Parameters of bank vole decontamination from radiocesium and radiostrontium

¹ International Radioecology Laboratory, Slavutych Division of International Chornobyl Center, P.B. 151, Slavutych, Kievskaya Oblast 07100, Ukraine
² Department of Biological Sciences, Texas Tech University, Lubbock, Texas 79409-3131, U.S.A.

Abstract

13 voles in 2000 and 15 in 2001 were moved from the most contaminated area of Chornobyl Zone to lab and fed by "clean" food over 2 months. Application of specially designed beta-gamma spectrometer and live counting methods allowed describing whole body decontamination. Initial whole body activity ranged : 22-385 kBq ¹³⁷Cs and 0.9-7.7 kBq ⁹⁰Sr. Less 0.4 % activity was lost by physical decay during the study, the most - by biological excretion way. In the 2000 study 97.4 % ¹³⁷Cs activity was excreted with half-life period of 1.93d, and in the 2001 study - 99.3% and 2.18d, respectively. 43 % ⁹⁰Sr activity contents was excreted with half-life of 13.7d in the 2000 study and 59 % with 13.1d in the 2001 study, respectively. The rest amount of the radionuclides was considered as non-excreted over the study term. At that, ⁹⁰Sr and ¹³⁷Cs loss rate of males was higher than females, and, paradoxically, lactating females over suckling period had more slow reduction both radionuclides, than other females. At birth ¹³⁷Cs content in newborns was 2-10.5 % of their mother activity, and 0.15-1.12 % of mother's ⁹⁰Sr content. Over the first 4-8 days of life (the period of exclusive milk consumption), substantial growth of ¹³⁷Cs activity took place, reaching a maximum value of 30-40% of their initial activity. The ⁹⁰Sr activity in newborns continued to grow over the suckling period, even with the steady decrease of ⁹⁰Sr activity in mother's body. By the end of the suckling period (15-18 days), total ⁹⁰Sr activity in a litter increased and attained an average of 3-4 times their initial value.