Risk assessment and ecotoxicological effects of leachates extracted from industrial district soils of Nanjing, China

With the intensification of industrial development and urbanization, soil pollution is increasingly prominent. Therefore, the potential adverse effects caused by industrial activities need to be investigated. In this study, nine soil samples were collected from the industrial district of Nanjing, China, and the heavy metal concentrations were analyzed. Ambient severity of health (ASI) and ambient severity of ecology (ASII) caused by heavy metals in soil extracts were also evaluated via the multi-media environmental goals (MEG). The environmental risk assessment model was used to assess the health risk of soil extracts. The toxicity of soil extracts was diagnosed for wheat and Vicia faba. The results indicate that the contents of heavy metals were significantly different among the nine soil samples and mass concentration of heavy metals were as followed: Pb > Mn > As > Zn > Cd. Except for CK and S9, the total health impact of all sampling sites were greater than 1. Also, the total ecological hazard degrees of the five heavy metals were all greater than 1, which showed that the soil extracts were harmful to human health and ecological environment. According to the risk characterization model, the carcinogen risk of soil extracts was 1 to 10 orders of magnitude higher than that of non-carcinogens. Drinking water intake was the most direct and primary exposure route. In addition, the ecotoxicological results indicated that with the increase of heavy metal concentration, the activity of amylase (AMS) decreased, while the activity of peroxide (POD) increased, indicating that the soil extracts were toxic to V. faba. The micronucleus rates of V. faba root tips in the sampling soils were significantly higher compared with the control group, reflecting the higher genotoxicity. Our study provides theoretical support for the evaluation of potential health and ecological risks in this industrial district.