Characteristic comparison of heavy metal contamination between road-deposited and roof-deposited sediments in suburban area.

Surface-deposited sediment in urban area is an essential environmental medium for assessing heavy metal contamination. A total of 10 sampling trips were conducted to collect road-deposited and roof-deposited sediments for the comparison of nickel (Ni), copper (Cu), cadmium (Cd), lead (Pb), zinc (Zn), and chromium (Cr) contamination characteristics. Results indicated that roof sediment appeared to have a finer size distribution than road sediments. Roof sediment indicated higher metal concentration and lower surface loading than road sediment. The impact of particle size on heavy metal contamination was quantified by using the developed pioneering term of finer particle effect factor; it differed according to surface types and grain size fraction. Particles in individual grain size fraction showed different contribution to the surface loading for bulk sediments. No consistent trend was found for the grain size fraction loading along with grain size for the studied heavy metals for road sediments. In contrast, an asymmetric "W" trend was observed for the roof sediments, and it had the following results: Fraction of <63 and 250-500 μm showed higher loading, while fraction of 90-125 and >850 μm indicated the smaller loading. Findings above facilitated the appropriate management practice selection for the treatment of surface-deposited sediments.