An Investigation of Urban-Runoff as a Source of Polycyclic Aromatic Compounds to Santa Monica Bay in Southern California

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic and mutagenic compounds that are ubiquitous in the environment. Anthropogenic sources include the incomplete combustion of fossil fuels, especially diesel. Wet and dry deposition transports PAH-containing particulate matter produced in fossil fuel combustion to the Earth's surface. Through these processes, PAHs may become concentrated in both the water and sediment associated with urban watersheds. This study used high performance liquid chromatography (HPLC) to analyze water and sediment samples from Ballona and Fern Dell creeks for polycyclic aromatic hydrocarbons. These watersheds feed untreated, urban runoff directly into Santa Monica Bay. A commercially available standard was used to identify unknown peaks in the sediment and water samples. The results show that all PAHs were below the limits of detection in the water samples. The sediment sample results show four peaks that were identified as polycyclic aromatic hydrocarbons. A four point calibration was performed to quantify these data. These results show that pyrene, benzo[a]pyrene, dibenz[a,h] anthracene, and benzo[g,h,i]perylene were detected in the sediment samples at concentrations of 0.02, 0.05, 0.03, and 0.02 µg mL^-1, respectively. From these results, we can confidently affirm the presence of these carcinogenic and mutagenic compounds in the urban watershed, which are a potential threat to the wildlife in this coastal region.