THE EFFECTS OF SOIL CHEMICAL CHARACTERISTICS ON THE CS-134 CONCENTRATIONS IN EARTHWORMS - UPTAKE FROM LIQUID-MEDIUM

The concentrations of potassium, stable cesium, calcium and ammonium i n soil, and of the pH are known to affect the uptake of Cs-134 by plan ts and soil organisms. It is uncertain as to which extent this is a di rect effect on the uptake of Cs-134 (e.g. through competition for bind ing sites) or an indirect effect through a changing distribution of th e Cs-134 between the solid and liquid phase of the soil. Studying the effect of both varying concentrations of potassium, stable cesium, cal cium and ammonium and the pH on the uptake of Cs-134 by the earthworms Eisenia foetida and Lumbricus rubellus from solution was, therefore, a means to investigate this effect. The concentrations of Cs-134 in th e earthworms were found to differ by a factor of three between the spe cies. Highest and lowest Cs-134 concentration differed by a factor of five within each species. Potassium affected the Cs-134 concentration in the earthworms significantly in contrast to stable cesium. However, the effects expressed per millimole added, were comparable for both e lements. The non-significance of stable cesium might have been caused by the small concentration range used. Considering the natural concent rations of potassium and stable cesium in soil solution, addition of p otassium was shown to be a more realistic counter measure. No signific ant effects from varying pH or calcium and ammonium concentrations wer e observed. The internal calcium concentration increased with increasi ng calcium concentration in solution, whereas the internal potassium c oncentration was independent of the potassium concentration in the sol ution. (C) 1997 Elsevier Science Limited.