The effects of soil chemical characteristics on the 134Cs concentrations in earthworms. Uptake from liquid medium

The concentrations of potassium, stable cesium, calcium and ammonium in soil, and of the pH are known to affect the uptake of 134Cs by plants and soil organisms. It is uncertain as to which extent this is a direct effect on the uptake of 134Cs (e.g. through competition for binding sites) or an indirect effect through a changing distribution of the 134Cs between the solid and liquid phase of the soil. Studying the effect of both varying concentrations of potassium, stable cesium, calcium and ammonium and the pH on the uptake of 134Cs by the earthworms Eisenia foetida and Lumbricus rubellus from solution was, therefore, a means to investigate this effect. The concentrations of 134Cs in the earthworms were found to differ by a factor of three between the species. Highest and lowest 134Cs concentration differed by a factor of five within each species. Potassium affected the 134Cs concentration in the earthworms significantly in contrast to stable cesium. However, the effects expressed per millimole added, were comparable for both elements. The non-significance of stable cesium might have been caused by the small concentration range used. Considering the natural concentrations of potassium and stable cesium in soil solution, addition of potassium was shown to be a more realistic countermeasure. No significant effects from varying pH or calcium and ammonium concentrations were observed. The internal calcium concentration increased with increasing calcium concentration in solution, whereas the internal potassium concentration was independent of the potassium concentration in the solution.