Importance of chemical structure on the development of hydrocarbon catabolism in soil.

A soil was amended with (14)C-analogues of naphthalene, phenanthrene, pyrene, B[a]P or hexadecane at 50 mg kg(-1) and the development of catabolic activity was assessed by determining the rate and extent of (14)CO(2) evolution at time points over 180 days. The catabolic potential of the soil was hexadecane>naphthalene>phenanthrene>pyrene>B[a]P, determined by the decrease in lag time (as defined by the time taken for 5%(14)CO(2) to be evolved from the minerialization of the (14)C-labeled hydrocarbons). The results clearly showed the difference between constitutive and inducible biodegradation systems. The 0 day time point showed that hexadecane minerialization was rapid and immediate, with a 45.4 +/- 0.6% mineralization extent, compared with pyrene minerialization at 1.0 +/- 0.1%. However, catabolism for pyrene developed over time and after a 95 days soil-pyrene contact time, mineralization extent was found to be 63.1 +/- 7.8%. Strong regression was found (r(2)>0.99) between the maximum rates of mineralization and the partioning coefficient between the mineralized hydrocarbons, which may indicate linearity in the system.