Application of a plant bioassay for the evaluation of ecotoxicological risks of heavy metals in sediments affected by mining activities

摘要

Purpose The objective of this work was to evaluate the effectiveness of a plant bioassay (Phytotoxkit~®) for screening ecotoxicological risks in sediments affected by mining activities. Materials and methods A total of 42 sediment samples affected by mining activities were studied, including 39 sediment samples from the Sierra Minera, Spain, an area affected by old extraction procedures, and three sediments from an area affected by opencast mining. These three samples were then mixed with limestone filler at 10,20 and 30 %, providing nine stabilised samples. The total and soluble metalloid) content (As, Cd, Cu, Fe, Pb and Zn) was determined in all samples, and the Phytotoxkit~® bioassay was applied to determine the ecotoxicological effect of this procedure. Results and discussion The stabilised material had a neutral pH and low soluble metal(loid) concentration, similar to that of samples in which a natural attenuation process had taken place because of mixing with surrounding carbonate-rich materials. An ecotoxicological survey identified the low tox-icity levels of the stabilised samples. Conclusions The applied bioassay is a good tool for screening metal(loid) contamination in areas affected by mining activities, since it provides information on both natural and simulated attenuation processes. The mixing of sediments with limestone filler could be applied to the remediation of zones affected by mining activities, because the toxicolog-ical effect on the tested organisms in the stabilised sediments was reduced significantly and the metal(loid) content was diminished.