Heavy metal contamination of road-deposited sediments in a medium size city of China

Abstract

Road-deposited sediment (RDS) is an important environmental medium that affects the characteristics of heavy metals in stormwater runoff. 62 RDS samples were collected from four different land use types (commercial, residential, intense traffic and riverside park) in the Zhenjiang city of China. The samples were analysed for concentrations of five metals (Zn, Pb, Cu, Cr and Ni). The maximum mean concentrations of Zn, Pb, Cu, Cr and Ni from different land use types were 686, 589, 158, 129 and 125 mg/kg, respectively. The intense traffic area displayed the highest metal concentrations, whilst Zn, Cr, Ni and Cu did not show any discernible variations among the other three areas. Seven particle sizes were analysed separately for the heavy metal concentrations. In all studied areas, particles<63 microm have the highest metal concentrations: 926-1,188 mg/kg of Zn, 270-928 mg/kg of Pb, 150-220 mg/kg of Cu, 99-172 mg/kg of Cr and 96-147 mg/kg of Ni. The fine particle fraction (<63 microm) of the samples accounted for about 25-60% of the total metal loading; in contrast, the coarsest fraction (1,000-2,000 microm) only contributed 1-5%. The calculated ecological risk index shows that considerably high potential risks exist in the intense traffic area particularly due to high concentrations of Pb. These findings provide invaluable information for the development of appropriate management strategies to decrease nonpoint source contamination loading to the water environment in urban areas.

Index models to evaluate the potential metal pollution contribution from washoff of road-deposited sediment

“…As point sources of pollution in China and many other countries decrease, urban runoff containing contaminated road-deposited sediment (RDS) is becoming an increasingly serious problem (Zhu et al, 2008;Zhao et al, 2010). RDS from impervious surfaces is an important carrier of contaminants, often containing metals at elevated concentrations (Aryal et al, 2009;Xiang et al, 2010).…”

Risk assessment of metals in road-deposited sediment along an urban–rural gradient

“…Excessive accumulation of metals in RDS also results in increased human exposure to metals due to their close proximity to anthropogenic activities (Christoforidis and Stamatis, 2009;Charlesworth et al, 2011). As point source pollution is reduced in China and many other countries, urban runoff with contaminated RDS has become an increasingly serious problem (Zhu et al, 2008;Zhao et al, 2010). Thus, a proper understanding of RDS contamination is crucial in urban ecosystem.…”

Spatial distribution, environmental risk and source of heavy metals in street dust from an industrial city in semi-arid area of China

“…Thus, the original evaluation index classifi cation was adjusted according to the number of pollutants and the ratio of the toxicity coeffi cient of each element. The degree of ecological risk was classifi ed as low ecological risk (E i < 15, RI < 50), moderate ecological risk (15 ≤ E i < 30, 50 ≤ RI < 100), considerable ecological risk (30 ≤ E i < 60, 100 ≤ RI < 200), high ecological risk ( 60 ≤ E i < 120, RI ≥ 200) and very high ecological risk (E i ≥ 120) (Lu et al 2014;Zhu et al 2008;Zhao and Li, 2013).…”