Can stable elements (Cs and Sr) be used as proxies for the estimation of radionuclide soil-plant transfer factors?

Transfer parameters are key inputs for modeling radionuclide transfer in the environment and estimating risk to humans and wildlife. However, there are no data for many radionuclide-foodstuff/wildlife species combinations. The use of parameters derived from stable element data when data for radionuclides are lacking is increasingly common. But, do radionuclides and stable elements behave in a sufficiently similar way in the environment? To answer this question, at least for soil to plant transfer, sampling was conducted in four different countries (England, Kazakhstan, Spain and Ukraine) affected by different anthropogenic radionuclide source terms (in chronological order: global fallout, Semipalatinsk Test Site, the 1957 Windscale accident and the 1986 Chernobyl accident) together with a bibliographical review. Soil to grass transfer parameters (ratio between dry matter concentrations in plant and soil), Fv, for 137Cs and 90Sr were significantly higher than those for stable elements, suggesting that the use of the latter could lead to underestimating radionuclide concentrations in plant samples Transfer parameters for 137Cs and stable Cs were linearly correlated, with a slope of 1.54. No such correlation was observed for 90Sr and stable Sr, the mean value of the 90Sr:Sr ratio was 35 ranging (0.33–126); few data were available for the Sr comparison. The use of radionuclide transfer parameters, whenever possible, is recommended over derivation from stable element concentrations. However, we acknowledge that for many radionuclides there will be few or no radionuclide data from environmental studies. From analyses of the data collated there is evidence of a decreasing trend in the Fv(137Cs)/Fv(Cs) ratio with time from the Chernobyl accident. [Display omitted] •Soil-to-plant transfer factors, Fv, 137Cs > stable Cs and 90Sr > stable Sr.•Radionuclide (Cs and Sr) Fv values can be up to over an order of magnitude than stable Fv's.•Differences between radionuclide-stable element transfer are observed 32–67 y after deposition.•Stable element based Fv may underestimate radionuclide activity concentrations.