Uptake of 134Cs from a sandy soil by two earthworm species: the effects of temperature.

Abstract

The uptake of 134Cs by the earthworm species Lumbricus rubellus and Eisenia andrei was studied in potted soils at different temperatures. Concentration factors were between 0.23 and 0.37 for E. andrei, and between 0.30 and 0.41 for L. rubellus. Biological half-lives ranged from 3 to 11 days for E. andrei and from 3 to 9 days for L. rubellus. The 134Cs uptake increased with temperature in both species. A 10 degrees C rise in temperature resulted in a 1.6-fold increase in 134Cs concentration in E. andrei and a 2.1-fold increase in L. rubellus. Maximum difference between 134Cs concentrations of the two species was 2.4. The increase in internal 134Cs concentration with increasing temperature could be mainly explained by earthworm-related factors such as increased metabolism or feeding rate since 134Cs concentrations in solution did not increase with temperature in pots without earthworms. 134Cs concentrations in soil solution from pots with earthworms compared to those in pots without earthworms were increased. Other soil solution characteristics, such as potassium, calcium concentration and conductivity, were also affected by adding earthworms. The 134Cs accumulation in earthworms was calculated as a function of the 134Cs concentration in the soil solution over time. The results indicate, at least in the case of L. rubellus, that since the accumulation pattern could not be explained by concentrations in soil solution, uptake through food must contribute considerably to the total uptake.