Characteristics and Risk Assessment of Heavy Metals in Urban Soils of Major Cities in China

The rapid urbanization in China may lead to heavy metal pollution in urban soil, threatening the health of residents. By collecting literature data published in the last 15 years, the characteristics and risks of heavy metals in the urban soils of 52 cities in China were analyzed. The results showed that the average ω(Pb), ω(Cd), ω(Cu) and ω(Zn)in the urban soils of China were 58.5, 0.49, 42.1, and 156.3 mg•kg-1, respectively, and the average Igeo values were ordered as follows Cd(1.10)> Zn(0.36)> Pb(0.28)> Cu(0.13). The high concentrations of heavy metals in the urban soils were mainly found in cities located in coastal economically developed provinces (such as Jiangsu, Zhejiang, etc.) and resource-based provinces (such as Hunan, Henan, Inner Mongolia, etc.). The cities of Kaifeng, Yangzhou, Hohhot, Taiyuan, and Xiangtan had relatively high Igeo values for heavy metals in the soils. The concentrations of heavy metals in soils from industrial areas and roadsides were significantly higher than those from residential areas and parks, suggesting that heavy traffic and developed heavy industry were the main causes of heavy metal accumulation in the urban soils. No significant correlations between the average concentrations of heavy metals in urban soil and urban economic and environmental indicators [such as permanent population, GDP, ρ (PM10), ρ(PM2.5), and SO2 emissions] were found. The concentrations of heavy metals in urban soils showed large spatial heterogeneity, and hence the average concentrations may not reflect the overall accumulation level in a city. The non-carcinogenic risks for children posed by heavy metals in urban soils were generally low, and the main risk contributor was Pb. However, the exposure to heavy metals in soils in cities with developed smelting industries is worthy of attention. © 2022, Science Press. All right reserved.