Trace-element concentrations and growth of earthworms and plants in soils with and without cadmium, copper, iron, lead and zinc contamination: Interaction of soil and earthworms

An experiment was carried out, under controlled conditions, using three soil types. These soils have similar physico-chemical properties but differ mainly in their contents of Rye trace elements (Cd, Cu, Fe, Pb and Zn). All the soils were planted with ryegrass (Lolium perenne) seedlings. Only half of them received an adult earthworm of the species Lumbricus terrestris. The objective of this first part of the work was to study on the one hand the effect of soil contamination on the growth and concentration of trace elements in L. terrestris, and on the other hand the effect of earthworms on the availability of trace elements for the plants. Results show that the presence of trace elements in high concentrations inhibit the growth of the earthworms. The amount of trace elements in earthworms differs according to the element, the time, the contamination and the physiological stage of the animal (adult or cocoon). The presence of L. terrestris only has a minor effect on the availability of trace elements studied for the plants.