Radionuclide partitioning coefficients in the Sava River ecosystem

Abstract

The radionuclides⁵⁴Mn,⁶⁰Co,⁹⁰Sr,⁹⁵Nb,⁹⁵Zr,¹⁰³Ru,¹⁰⁶Ru,¹²⁵Sb,¹³¹I,¹³⁴Cs,¹³⁷Cs,¹⁴⁰Ba,¹⁴⁴Ce,²²⁶Ra and²²⁸Ac have been studied in the Sava River environment since the Chernobyl accident in 1986. The measured periphyton concentration ratios (CR) for each radionuclide were correlated with the measured sediment distribution coefficients (K_d) for that radionuclide. The K_d-CR relationships obtained were defined by the equation ln K_d=−0.5 ln CR +7.4. These K_d-CR relationships were assumed to be referable to the Sava River ecosystem and were used to predict the missing soil K_d values and/or the missing CR values for the wide range of radionuclides, respectively. Moreover, the K_d-CR relationship characteristic for the Sava River ecosystem was compared with the K_d-CR relationship proposed by Baes¹ and by Shepard². The characterization of the partition coefficients in the Sava River environment and understanding of the mechanisms affecting radionuclide retardation and bioaccumulation are required for the planning of radioactive waste depositories in the area.