| Summary: |
In this study the impact of bioremediation on heavily petroleum-contaminated soil leachates by measurements of toxicity and physico-chemical parameters was investi-gated. Leachates were collected from two biopiles located at a Polish oil refinery representing different bioremedia-tion applications. To evaluate the toxicity of leachates the following bioassays were applied: Spirotox test, Protoxkit FTM, Rotoxkit FTM, Thamnotoxkit FTM, Ostracodtoxkit FTM, Microtox® test, and different plant tests. The meas-urements were carried out after 48 and 8 months of the bioremediation process for engineered biopile 1 and non-engineered biopile 2, respectively. The leachates from both biopiles were found to be not toxic for most of the test organisms. This was most likely due to reduction in hydro-carbon concentrations by bioremediation. The protozoa Spirostomum ambiguum and Tetrahymena termophila were sensitive to the leachates from biopiles 1 and 2, and toxic effects were noted. The leachate from biopile 2 was 4 times more toxic than that from biopile 1. The seven plant spe-cies in the seed germination tests were also sensitive to hydrocarbon concentrations in both biopile leachates. The use of bioassays together with chemical analyses gives the most reliable results for risk analyses, and confirm the effects of active bioremediation reducing the toxicity of contaminated biopile leachates on several test organisms at different trophic levels. |