Particle Size Dependent Heavy Metals in Road Dusts from Maanshan City, China

Abstract

In this study the road dusts (RDs) <1,000 μm from Maanshan City, China were characterized from the prospects of size fractionated pollution by heavy metals (HMs). Particulates with size <75 μm, 75–125 μm, 125–250 μm, 250–500 μm and 500–1,000 μm averagely accounted for 35.7±11.7%, 14.6±11.0%, 25.3±12.5%, 11.6±8.8% and 12.8±12.9% of the total weight, respectively. This result implies the gravimetric percentage was overall declined with increasing granular size, following gamma distribution function (p < 0.001). It was observed that the highest contents of Zn, Ni, Pb and Cd occurred with the fine RDs < 75 μm while Cu with these < 125 μm, suggesting HMs preferred to be associated with the fine particulates. Cu, Zn, Ni, Pb, Cr and Cd were present in RDs with bulk contents of 68±30 mg/kg, 285±122 mg/kg, 23±16 mg/kg, 53±21 mg/kg, 432+297 mg/kg and 0.56±0.39 mg/kg, which resulted in geo-accumulation index (lgeo) values as -1.04, 2.35, -2.38, 0.38, 1.54 and 0.18, respectively. Hence, it can be concluded that the RDs had only been significantly polluted by Zn. Person correlation analysis suggests those HMs ubiquitously present in RDs had size-dependent sources.