Influence of pH, soil type and soil organic matter content on soil-to-plant transfer of radiocesium and -strontium as analyzed by a nonparametric method

A new nonparametric method, called the relative comparison method, is presented to evaluate the effect of some soil parameters on transfer of Cs or Sr from soil to edible plant parts. A large number of transfer factors is used for 134Cs, 137Cs, 85Sr, 89Sr and 90Sr. Transfer of Cs increased with increasing organic matter content. Compared to the transfer of Cs in soils with an organic matter content of less than 5%, the effect was approximately a factor of 2-5 to 20% and increased up to a factor of 10 in soils with an organic matter content of more than 50%. In contrast, transfer of Sr decreased with increasing soil organic matter content. Relative to the transfer of Sr in soils with an organic matter content of less than 5% the decrease was by about a factor of 1.5 at 6-10% organic matter up to a factor of 10 in soils with an organic matter content of more than 50%. In the range pH 3.9-8.4, transfer of Cs was not affected by soil pH. On average, transfer of Sr decreased by a factor of 1.7 when soil pH increased from pH 4.5 to 7.4. Transfer of Cs in clay or loam was lower than in sand, by five or three times, respectively. For Sr the transfer in clay or loam was about 1.4 times lower than in sand. These results may be used as correction factors when evaluating soil-to-plant transfer factors of Cs or Sr. (author)