Ecotoxicological and analytical assessment of effects of bioremediation on hydrocarbon-containing soils

Ecotoxicological assessments of contaminated soils require an understanding of the impact of chemicals on the terrestrial ecosystem. Eight hydrocarbon‐containing field soils were evaluated using physical‐chemical, hydrocarbon, and ecotoxicological assays during 11 to 13 months of laboratory bioremediation. Ecotoxicity tests included earthworm (Eisenia fetida) 14‐d survival and reproduction assays and seed germination and root length assays using corn, lettuce, mustard, and wheat seeds. During bioremediation, freon‐extractable total petroleum hydrocarbon decreased by 26 to 84%, depending on the soil. In most soils, earthworm survival increased to or remained at 100% following bioremediation. Earthworm reproduction increased or remained the same relative to control soils. Lettuce and mustard seed germination increased following bioremediation except in two soils with high salt concentrations. Corn and wheat germination was high on most soils and did not change following bioremediation. Root length responses varied among seeds and soils, increasing in some soils and remaining unchanged in others. The responses of organisms to hydrocarbon‐containing field soils directionally improved with bioremediation.