Yuan, ChenPolycyclic aromatic hydrocarbons (PAHs) are a group of organic pollutions that are carcinogenic to humans. A bioretention cell at the campus of University of Maryland, College Park, evaluated for their potential to remove PAHs from stormwater. The risk of PAH pollution was confirmed by the fact that the highest value of total PAH concentration (25.5 μg/g) and the average concentrations of pyrene (1.78 μg/g) and chrysene (1.40 μg/g) was higher than their respective probable effect concentrations (PECs) (22.8 μg/g, 1.52 μg/g and 1.29 μg/g),. Sources of PAHs in the media originated from fossil fuel combustion and petroleum. Human carcinogenicity was evaluated by determining the Benzo[a]pyrene Total Toxicity Equivalent (BaP-TEQ), and benzo[a]pyrene made most contribution to carcinogenicity. Biotransformation of PAH is possible in bioretention cell, because PAH-ring cleaving dioxygenases (PAH-RCD) gene was found in media.enThesisEnvironmental engineeringBioretention cellsPAH Degrading BacteriaPolycyclic Aromatic Hydrocarbons (PAHs)Stormwater