Estimation of the accumulation rates and health risks of heavy metals in residential soils of three metropolitan cities in China

摘要

Heavy metal concentrations in urban soils are likely to increase over time because of contin-uous urbanization and heavy metal emissions.To estimate the accumulation rates of heavy metals in urban soils,we collected soil samples from residential areas with different build-ing ages in the metropolitan cities of Shanghai,Shenzhen,and Beijing,China.Heavy metal concentrations in the soils varied among the cities and were primarily affected by soil parent material and the intensity of anthropogenic sources.Regression analyses revealed that the accumulation rates of Cd and Cu in the soils ranged from 0.0034 to 0.0039 mg/(kg·year)and 0.343 to 0.391 mg/(kg·year),respectively,and were similar across the three cities,while ac-cumulation rates of Zn and Pb in Shanghai were higher than those in Shenzhen and Beijing.The higher accumulation rates of Zn and Pb in Shanghai can be explained by differences in city history and industrial structures among the cities.Residential soils with high health risks posed by the heavy metals were mostly collected from old towns of Shanghai because of high Pb content in the areas.Although recent urbanization resulted in elevated concen-trations of Cd,Cu,Zn,and Pb in the residential soils,the effect on the total health risks of residents exposed to the soils was negligible.