Contamination and risk assessment of metals in road-deposited sediments in a medium-sized city of China.

Road-deposited sediment (RDS) is a valuable environmental medium for characterizing contamination of metals in urban areas and the associated risks to human health. A total of 62 RDS samples were collected for metal test in four urban areas in a medium size city in eastern China. The areas that represented different land uses consisted of intense traffic area (ITA), commercial area (CA), residential area (RA), and riverside park area (RPA). The effects of particle size and different land uses on metal contamination and health risk were the major focus in this study. The test results showed that RDS in ITA appeared to have higher metal content, enrichment factor (EF), ecological risk index (RI), and the non-cancer and cancer risks than in the other areas. The metal contamination and health risk increased inversely with particle size. The particles less than 63 μm were found to be most critical in development of metal contamination and health risk. The EF was measured to be greater than 2.0 in the four areas, indicating a moderate enrichment. The measured RI ranged between 50 and 200, indicating considerable to moderate risks. The non-cancer risk for children was high in the four areas but was low for adults in all test areas except in ITA. The cancer risk of Cr for children was high in all test areas. Based on the test results, the contamination control and management for metals in RDS shall focus on the effects from such factors as particles (<63 μm) and the land use for intense traffic (ITA).