Effect of nonaqueous-phase liquids on the availability of polycyclic aromatic hydrocarbons in soil for worm uptake and bacterial genotoxicity.

A study was conducted to determine the effect of nonaqueous-phase liquids (NAPLs) on the bioavailability of benzo[a]pyrene (BaP) in soil. Sentry 19 oil and pristane reduced the availability of BaP for assimilation by the earthworm Eisenia fetida and for mutagenicity in a rifampicin-sensitive strain of Pseudomonas putida. As much as 80% of the compound could be rendered unavailable to the worms or for genotoxicity. Tests with five alkanes and an oil showed that the extent of reduction in genotoxicity of BaP varied with the identity, viscosity, and hydrophobicity of the NAPL. The magnitude of the decline in availability for genotoxicity differed in tests of three soils. Because little or no BaP was lost from the soil, the diminished bioavailability was not the result of a diminished total concentration of the compound. These findings show that exposure to hydrophobic toxicants can be appreciably altered in soils containing NAPLs.