ASSESSMENT OF THE ACUTE TOXICITY OF CRUDE OILS IN SOILS USING EARTHWORMS, MICROTOX(R) AND PLANTS

The assessment of soil quality resulting from a chemical or oil spill and/or remediation effort may be obtained by evaluating the toxicity t o soil organisms. To enhance our understanding of the soil quality res ulting from laboratory and field oil spill remediation, we have assess ed three soil toxicity test methods. Heavy, medium and light crude oil s (API gravity 16-18, 30 and 53) were spiked into two soils in the lab oratory. The earthworm (Eisenia foetida) 14-d lethality assay, the mod ified Microbics Microtox(R) Solid-Phase assay, and the 14-d plant seed germination and growth assays were tested with combinations of crude oils and soils. Earthworms were 1.4 to 14 times more sensitive than Mi crotox and 1.3 to >77 times more sensitive than plants to the oily soi ls. Light oil in the silty low organic carbon soil was generally the m ost toxic, while heavy oil in the sandy high organic carbon soil was l east toxic. The bioassay techniques were demonstrated to be sensitive indicators of soil quality and may be used to evaluate the quality of remediated oily soils. (C) 1998 Elsevier Science Ltd. All rights reser ved.