Influence of pH on the accumulation of cadmium and lead in earthworms (Aporrectodea caliginosa) under controlled conditions

This study was conducted with soils from the vicinity of Oulu, northern Finland to investigate the effect of pH on the accumulation of Cd and Pb in earthworms. The earthworms (Aporrectodea caliginosa) were maintained in wooden boxes in two series of experiments. The calcium, pH and heavy metal content (Pb and Cd) were adjusted in order to follow the influence of pH on the Pb and Cd uptake by the worms. The cadmium uptake seems to clearly depend on the pH of the soil and the accumulation becomes faster at a lower pH. The same trend is also seen in lead accumulation. The concentration ratio for cadmium over a period of 230 days varied from 13 to 33.