Impacts of key factors on heavy metal accumulation in urban road-deposited sediments (RDS): Implications for RDS management.

Understanding of the impacts of key influential factors on RDS related heavy metal (HM) contamination is crucial for developing effective RDS management strategies to support the stormwater pollution mitigation. In this paper, three factors (i.e. traffic condition, slope of road and antecedent dry period) were considered to investigate their influences on the accumulation of RDS and adsorbed HMs. Positive correlations between truck and Zn/Ni content in RDS, car and Cu/Pb content in fine RDS, as well as bus and Cu content in coarse RDS were observed. Relative to sloping stretches, RDS from level stretches generally presented finer size distributions and aggravated HM contamination in fine fractions. Moreover, the fine RDS and adsorbed HMs increased significantly with the accumulation of RDS. Based on these findings, optimized RDS management strategies were proposed to enhance the removal of washable RDS in pollution hotspots. For example, tandem sweeping technologies, performing high efficiency in capturing fine particles, are suggested to be employed during the steady period of RDS accumulation, in order to reduce fine RDS effectively. The outcomes of this study provide useful reference for the source control of stormwater runoff pollution.