Combined effect of sequestration and bioremediation in reducing the bioavailability of polycyclic aromatic hydrocarbons in sod

A study was conducted to determine the combined effect of sequestration and laboratory-scale bioremediation on the bioavailability of polycyclic aromatic hydrocarbons in soil. After the compounds had aged for 140-203 days in soil, bacteria capable of degrading the compounds were added, and the availability of the hydrocarbons after bioremediation was determined. Aging decreased the amount of phenanthrene, anthracene, fluoranthene, and pyrene available to bacteria as shown by increases in the amount of the compounds remaining after bioremediation and to earthworms (Eisenia foetida) as shown by lower tissue concentrations, percentages assimilated, and bioconcentration factors. Aging also diminished the availability of anthracene to wheat and barley. Bioremediation caused a marked diminution in the amount of phenanthrene, fluoranthene, and pyrene taken up by earthworms. The smallest amounts of these three compounds were assimilated from soil in which they had aged and then been subject to biodegradation. The results show that the combined effects of sequestration and bioremediation lead to a more marked reduction in bioavailability than either process alone.