Biodegradation of Benzo(a)pyrene in Contaminated Soil: Plant and Microorganism Contributions from Isotope Tracing.

Biological degradation effectively removes benzo(a)pyrene (BaP) from contaminated soil; however, knowledge regarding the contributions of plant absorption, microbial degradation, and volatilization to BaP removal remains limited. In this study, the BaP removal pathway in contaminated soil was investigated. The structural evolution of the microbial community in contaminated soil was revealed using a comparative experimental study. BaP, as a representative of high-molecular-weight polycyclic aromatic hydrocarbons, was removed from freshly contaminated soil by microbial degradation, plant absorption, and volatilization in proportions of 20.955%, 12.771%, and 0.005%, respectively. The proportions of BaP removed by microbial degradation, plant absorption, and volatilization in aged contaminated soil were 29.471%, 16.453%, and 0.004%. Microbial degradation was the most responsible mechanism for BaP removal. Moreover, a higher number of BaP degrading bacteria occurred in the aged contaminated soil. At the genus level, and were detected in both types of soils, being the key bacterial species involved in BaP degradation.