Determination of Lead Source in Urban Road Runoff Due to Automobile Traffic

Abstract

Lead isotopic analyses of road sediments and traffic-related substances, such as asphalt, traffic paint, automobile tires, wheel balance weights and automobile exhaust, have been carried out to determine the sources of lead pollution in road runoff. Smaller particles in road sediments contained a higher lead concentration and showed the same lead isotopic composition as road runoff; therefore, lead in road runoff was mainly attributed to minute particles (<53 μm) in the sediments. Because yellow traffic paint was found to be rich in lead and showed a similar lead isotopic composition to road runoff, it would be considered as the source of lead pollution on the condition that it was used near the site. White traffic paint and automobile tires did not contribute to lead runoff because of their low lead concentration and different lead isotopic composition. The lead isotope ratios in wheel balance weights fell within almost the same range as that of road runoff; therefore, wheel weights were determined as a major source of traffic-related lead runoff.