Ecotoxicity monitoring of hydrocarbon-contaminated soil using earthworm (Eisenia foetida).

In order to assess the applicability of an earthworm bioassay as a technique for monitoring the soil flushing process, short-term and long-term toxicity tests were conducted on remediated soil using various pore volumes of surfactant solution. Results obtained on short-term toxicity testing indicated that biomass increased as the soil flushing proceeded, and on diesel-contaminated soils this testing showed that the effect of diesel is lethal and that 25 pore volumes of soil surfactant were not sufficient to abrogate the toxic effect of diesel. These short-term tests also showed strong sublethal relationships between the development of biomass, and the concentrations of toxic chemicals in the soil. Although relationships between contaminants and the various bioassay parameters examined were not significant in long-term testing, an increase in the number of juveniles was observed over time, which may have been a consequence of a reduction in toxicity associated with the flushing process.