Occurrence and fate of PAHs from road runoff in the south drainage basin of Annecy Lake

The nature and concentration of Polycyclic Aromatic Hydrocarbons (PAHs) from main road runoff were evaluated in several potential deposition areas close to Annecy Lake. Investigations were conducted on sediments from road lining ditches, surface sediments, surface water of the lake, Eau Morte river, stagnant water from a natural reserve. Sixteen common PAHs were studied and the concentration determined monthly from February to November, 1997 by High-Resolution Shpol'skii Spectrofluorometry. For liquid samples, the total PAH concentration ranges from 0.07 ng/L (Eau Morte) to 8150 ng/L (ditch water). In the sediments the highest PAHs level (1430 ng/g) was observed for the ditches lining the road and illustrate the significant contribution of road runoff to the contamination of the river. The results evidence the PAH adsorption on particulate matter for ditches and river sediments. PAHs bind preferentially to humic substances in stagnant water of swamp areas. The very low concentrations of PAHs found in Annecy Lake water reflect the importance of marshes in the preservation of this natural ecosystem from road runoff contamination.