Novel Approaches to Bioindication of Heavy Metals in Soils Contaminated by Oil Shale Wastes

The major sources of heavy metal pollution in Estonia are oil shale industry and oil shale combustion. There is an utmost need to monitorsoil pollution with heavy metals in this region. Earthworms are good accumulators of heavy metals and can be used as bioindicators. Endogeic species Aporrectodea caliginosa and Aporrectodea rosea as well as anecic species Lumbricus terrestris are good bioindicators for Zn(II) and Cu(II) ions in soils contaminated by oil waste or fly ash because of the high level of accumulation of these metals in their tissues. Electrochemical methods were used for the determination of heavy metal ions in earthworms as the amount of the sample needed for the analytical work is from 10 to 100 times smaller, when compared to the traditional methods.