Effect of concentration on sequestration and bioavailability of two polycyclic aromatic hydrocarbons

A study was conducted to determine the effect of concentration on sequestra tion and bioavailability of phenanthrene and pyrene in soil. The compounds at 1.0, 10, and 100 mg/kg of soil became increasingly resistant to a mild s olvent extraction and progressively less bioavailable to earthworms (Eiseni a foetida) as a result of aging for 120 days. Aging also resulted in both c ompounds at 1.0 and 10 mg/kg and phenanthrene but not pyrene at 100 mg/kg b ecoming more resistant to microbial degradation. increasing the concentrati on led to an increase in the percentages of the unaged and aged compounds t hat were susceptible to microbial degradation. Some of each of the two comp ounds was still available to earthworms following biodegradation. The data show that sequestration of the polycyclic aromatic hydrocarbons occurs at b oth low and high concentrations.