Hydrocarbons in Urban Runoff

Runoff from 15 watersheds in the San Francisco Bay area are sampled over a 2-yr period and analyzed for hydrocarbons. Both gravimetric analyses and high-resolution gas capillary chromatography are performed. It is found that land uses with high commercial/industrial activity have much greater aliphatic hydrocarbon emissions than non-commercial areas. A relationship between commercial land use and the anthropogenic aliphatic hydrocarbon fraction is found. The ratio of total extractable organics to total organic carbons is found to vary with land use, with a ratio of six or more indicating significant commercial/industrial activity. Aromatic hydrocarbons, including polynuclear aromatics, are also found, but in smaller concentrations than aliphatics.