LEVELS, TRENDS AND FATE OF POLYCYCLIC AROMATIC HYDROCARBONS (PAHs) IN DIRT AND DUST FROM ROADS IN THE LONG CREEK WATERSHED, SOUTH PORTLAND, MAINE

Long Creek, located in South Portland, Cumberland County, Maine has been classified as an urban impaired stream. Potential causes for impairment are believed to be associated with extensive impervious areas, e.g. asphaltic pavement, within the drainage basin affecting surface water runoff discharging to Long Creek. In the largest urbanized segment of Long Creek Watershed, impervious surface coverage is in excess of 55%. Polycyclic aromatic hydrocarbons (PAHs) were evaluated in dirt and dust samples collected from various locations along roadways and paved surfaces in the Long Creek Watershed. Samples of dirt and dust were obtained from paved areas based on visual accumulations of material in low-lying areas, and from dirt and debris collected during routine street sweeping. Additional samples were collected from catch basins located throughout the basin which divert surface water runoff into the municipal stormwater system, ultimately discharging to various tributaries of Long Creek. Distribution of PAH compounds within fine-grained street dirt samples obtained from highly trafficked areas in Long Creek Watershed are dominated by high molecular weight PAHs, with concentrations 1-2 orders of magnitude higher than those found in street dust samples collected in rural areas outside the basin.