Availability of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) to earthworms in urban soils

We studied the uptake of 20 PAHs and 12 PCBs from 25 field-contaminated soi ls by Lumbricus terrestris L. and tested the suitability of the equilibrium partitioning theory (EPT) to describe the uptake. The bioavailability of P AHs and PCBs was assessed by exhaustive (hexane-acetone) and nonexhaustive extraction methods (methanol-water 1:1 and 0.5 M NaOH). The latter extracte d on average 6-68% and 2-42% of the total PAH concentrations and 7-81% and 9-22% of the total PCB concentrations, respectively. The extractability of an individual compound decreased with increasing octanol-water partitioning coefficient (K-OW) and was higher for the PCBs than for the PAHs. The EPT described the uptake of PAHs and PCBs well. After 15 d of exposure, the con centrations in earthworms were near steady-state. We found close correlatio ns between concentrations in all extracts and concentrations in earthworms after 15 d of exposure (total: r = 0.75-0.94; methanol-water: r = 0.68-0.94 ; NaOH: r = 0.59-0.87). The average biota-to-soil accumulation factors (BSA F) were 10-100 times higher for PCBs (0.71-70) than for PAHs (0.13-0.41). T he BSAFs of the PAHs were independent of K-OW; those of the PCBs decreased with increasing K-OW(-0.72 r less than or equal to -0.97).