Evidence for diffuse contamination of river sediments by reed asphalt particles

Saturated hydrocarbons analysis was carried out on different river sediment s from Alsace-Lorraine in order to detect possible contaminations by petrol eum byproducts. The distributions of n-alkanes from all studied samples are very similar and are, characterized by an odd-over-even carbon number pred ominance, underlining the higher plant contributions. On the other hand, pe ntacyclic triterpanes and steranes occur in all river sediments and display similar signatures that are characteristic of a nature organic matter cont ribution inherited from anthropogenic contaminations, Among the different p ossible pollutants origins, point industrial sources seem unlikely because of the highly homogeneous biomarker signatures and the geographical reparti tion of the studied rivers. Because of the intense road traffic in Alsace-L orraine, main vehicle fuels anti exhausts have been investigated. Unleaded and diesel fuels, used engine oils, and engine exhausts cannot account for the biomarker distributions observed in river sediments. On the contrary, s aturated hydrocarbons extracted from road asphalts are chiefly composed of polycyclic biomarkers with chromatographic signatures very close to those o f river sediments. Moreover, microscopic investigations of river sediments allow us to identify asphalt particles and to confirm that the different ri vers studied are contaminated by road asphalts. Such contaminations may dis tort biomarker signatures and GC-MS data and overprint the possible polluti on by other petroleum byproducts.