Contribution of urban runoff to hydrocarbon pollution.

Abstract

Runoff from an urban, northern Philadelphia, Pa., area was found to contain on the average 3.69 mg/l total hydrocarbons. This concentration indicates a loading of 25.7 kg/ha/y (22.9 lb/yr/acre) from urban areas on the lower Delaware Estuary. Of the total hydrocarbons, 69.9% were aliphatic and 30.4% aromatic. In addition, 86.4% were associated with the particulate materials present and only 13.6% with the soluble constituents. However, as the runoff increased the fraction of hydrocarbons associated with the particulates also increased. No relationship was found between load and the time since prior rainfall, but a relationship was observed between runoff and load. Preliminary analysis indicates that the primary source of these hydrocarbons may be crankcase oil.