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

A soil was amended with C-14-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 (CO2)-C-14 evolution at time points over 180 days. The catabolic potential of the soil was hexaclecane > naphthalene > phenanthrene > pyrene > B[a]P, determined by the decrease in lag time (as defined by the time taken for 5% (CO2)-C-14 to be evolved from the minerialization of the C-14-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.