Heavy metal contamination of sediments in stormwater management systems: the effect of land use, particle size, and age

Sediments from stormwater retention ponds, roadside swales and street sweepings have to be disposed of or reused periodically. Information on their pollution is needed to establish reuse and disposal regulations and to schedule clean out and street-sweeping activities. This study examines the heavy metal contamination in these sediments and the factors that aect this contamination. Results show that the particle size distribution of the sediments depends on dierential erosion processes of natural soils, land use, and technical limitations of street sweepers. Pond and swale sediments are more polluted with heavy metals than natural soils, but street sweepings are not. This can be explained by the high clay contents of sediments in ponds and swales and the very low clay content of sweepings. Land use is an important factor for the heavy metal pollution of ponds and swales, but does not considerably aect heavy metals in street sweepings. Within a given type of land use, heavy metal concentrations in pond sediments increase with age.