Impact of ageing and weather conditions on soil-to-plant transfer of radiocesium and radiostrontium

Abstract Results from long-term lysimeter experiments on soil-to-plant transfer of Cs and Sr were re-analysed to study the impact of ageing and climatic conditions. The experimental design allowed the effects of both parameters on the transfer to be distinguished. Transfer of Cs to edible parts of several plant species gradually decreased as a result of ageing. This decrease is estimated to be a factor of 1·5 after 1–2 years, up to a factor of 4 after 7 years. Transfer of Sr did not change when its residence time in the soil increased. After correction for effects of ageing, annual fluctuations of up to a factor of 10 were found, dependent on the plant species. These fluctuations were attributed to the effects of climatic conditions. The transfer of Sr to several plant species appeared to increase with increasing rainfall or with decreasing intensity of light, hours of sunlight or temperature. A negative correlation was found between the transfer of Cs to spinach and the amount of rainfall.