The negative impact of aging on the loss of PAH components in a creosote-contaminated soil

Soil samples were collected from sites contaminated with creosote but differing in the length of time since cessation of production. They were used to evaluate in laboratory experiments the effect of aging and the significance of adding metabolically competent bacteria on the loss of indigenous fluoranthene and pyrene. Incubation was carried out with or without addition of cells grown with 3-methylbenzoate. Control experiments used spiked contaminants to confirm the metabolic competence of the added bacteria, and azide was used to exclude the role of abiotic reactions. It was concluded that there was no advantage in adding metabolically competent bacteria to facilitate degradation of these PAH contaminants in soil, and that aging was a primary factor in determining the success of bioremediation. Indigenous benzo[e]phenanthrylene, benzo[ghi]perylene, and benzo[a]pyrene were recalcitrant in the younger soil; and in view of the results for fluoranthene and pyrene, they may, therefore, be presumed to be recalcitrant in aged soils.