DISTRIBUTION OF POLYAROMATIC HYDROCARBONS IN THE WATER COLUMN AND SEDIMENTS OF A DRINKING-WATER RESERVOIR WITH RESPECT TO BOATING ACTIVITY

The potential impact of motorboat activity on a major drinking water reservoir was evaluated. Polyaromatic hydrocarbons (PAHs) were measured in water and sediment samples at both marina and nonmarina sites during peak boating activity in June 1990 and during low boating activity in October 1990. Total PAH concentration contour plots and statistical analyses were used to determine the impacts of boating activity. Total PAH concentrations of less than or equal to 4 mu g/l were present in the water during peak boating activity, but aqueous PAHs were not detected during low boating activity. PAHs were detected in the sediments during both sampling periods; sediment concentrations for total PAHs were generally < 700 mu g/kg. The PAH profile of the June water samples was representative of combustion and petrogenic sources, while the PAH profiles found in the sediments were typical of combustion. Boating was shown to be a PAH source to the water column during periods of high boating activity. There was a significant difference for total PAH concentrations between the marina and nonmarina sites for the sediment samples in June, and for the individual PAH concentrations of phenanthrene, fluoranthene, and pyrene for October; this demonstrated localized impacts of boating at marina sites. PAH profiles, ratios, and contour plots indicated urban runoff and atmospheric deposition as other contributors to PAH concentrations in the water and sediments. The PAH concentrations in inlets to the reservoir tended to be higher than those detected in the main channel. This indicated an impact of hydrology on PAH distribution.