Mild extractability and bioavailability of polycyclic aromatic hydrocarbons in soil

A study was conducted to determine the relationship between bioavailability of unaged and aged polycyclic aromatic hydrocarbons (PAHs) in soil and the amounts detected by mild solvent extraction. More aged than unaged anthrac ene remained in Lima foam following introduction of earthworms (Eisenia foe tida), a mixed culture containing anthracene-degrading microorganisms, or e arthworms or wheat after bacterial biodegradation of the compound. Aging de creased the percentage of anthracene recovered by mild extraction with iz-b utanol from soil following introduction of earthworms, growth of wheat, bio degradation by bacteria, or when maintained sterile. Biodegradation resulte d in a marked decrease in the percentage of aged and unaged anthracene reco vered from soil by mild extraction with n-butanol or ethyl acetate. Aging o f fluoranthene and pyrene decreased the amount removed by mild extraction w ith n-butanol, ethyl acetate, and propanol. The uptake of aged and unaged a nthracene, fluoranthene, and pyrene by earthworms was correlated with the a mounts recovered from soil by mild extraction with n-butanol, propanol, and ethyl acetate (r values in the range 0.911-0.992). The retention of aged a nd unaged anthracene by wheat and barley was correlated with the amounts re covered from soil by the same procedure (r values in the range 0.892-0.945) . We suggest that mild extraction with organic solvents can be used to pred ict the bioavailability of PAHs in soil.