Bioassays used for Detection of Ecotoxicity at Contaminated Areas
Abstract : Ten bioassays were used for the evaluation of acute, (sub)chronic toxicity and genotoxicity of an unknown soil from a military base and six model soils that were contaminated at former military bases with the major pollutants : kerosene, petroleum and used motor oil. The test species represented algae and higher plants, invertebrates and bacteria. The ability to detect toxicants in test soils and their waste extracts was investigated and the sensitivity of each bioassay was compared with regard to the tested material (soil vs. water extract from oil) and other test species.
The most sensitive bacterial assays (Toxi-ChromoPad and ECHA Biocide Monitor) were able to detect acute toxicity in most samples. Another bacterial assay, MetPAD, responded positively to the presence of metals. The least sensitive test of the whole battery was the bacterial luminescence assay. The two phytotoxicity tests were similar in sensitivity. The crustacean test Thamnotoxkit F detected acute toxicity only in three samples. The maturation of nematodes was the most sensitive endpoint in nematode assay that was able to indicate potential genotoxicity in most extracts. The MutaChromoPlate identified the presence of mutagenic agents in all soil extracts, unlike the SOS-Chromotest Pad, which was positive for genotoxicity only for the most toxic soil with kerosene.
A minimised battery of bioassays for detecting toxicity in investigated soils could be composed of a bacterial assay (Toxi-ChromoPad or ECHA), a phytotoxicity assay (a seed germination and root elongation test) and an invertebrate test (nematode assay).
Basic information about genotoxicity could be given by the Muta-ChromoPlate.