MOBILIZATION AND REMOVAL OF CONTAMINANTS ASSOCIATED WITH URBAN DUST AND DIRT

The objective of this research was to examine the effects of pH and contaminant/sorbent concentrations on the partitioning of contaminants in urban dust and dirt. An emphasis has been placed on the environmental behavior of trace metals. Contaminants in urban dust and dirt are primarily associated with particles, even after suspension in runoff water for several hours to days. This affects the reactivity, toxicity, and mobility of the contaminants. Particle size distributions (PSD) for urban dust and dirt and partition coefficients (K(p) for the distribution of various contaminants between the water and the particles of various sizes are described. Where streams have very low alkalinity or in areas affected by acid precipitation, there can be substantial decrease in pH with dilution of the initial runoff. This has a significant effect on the speciation of contaminants, and therefore on the reactivity and mobility of contaminants in urban runoff.