Risk assessment and ecotoxicological diagnosis of soil from a chemical industry park in Nanjing, China

Soil pollution due to the activities of industrial parks, is becoming an increasingly serious issue, particularly throughout China. Therefore, it is essential to explore the soil pollution characteristics and its ecotoxicological effects on model species, such as higher plant species, in typical industrial areas. In this study, concentrations of heavy metals and polycyclic aromatic hydrocarbons (PAHs) were examined in the soil collected from 10 sampling sites at a chemical industry park in Nanjing, China. The pollution index was used to assess the heavy metal pollution level of soils, while the hazard index (HI) and carcinogenic risk index (RI) were calculated to assess the human health risk of soil PAHs. In addition, wheat (Triticum aestivum L.) was used as the model species to evaluate the ecotoxicological effects of polluted soil in pot experiments. Results showed that the content of heavy metals and PAHs varied greatly in soil samples, among which the heavy metal pollution at S1, S2 and S3 was the most serious. The health risk assessment of PAHs indicated that non-carcinogenic and carcinogenic values for all soil samples were below the threshold levels. Statistical analysis of the correlation between contaminated soil and toxic effects in wheat found that the significance values of regression equations were all less than 0.05 for chlorophyll content, peroxidase (POD) and amylase (AMS) activity. This indicates that the chlorophyll content, POD and AMS activity in wheat leaves could be suitable biomarkers for evaluation of the combined toxicity of multiple pollutants. This study provides a reference for future research on the risk assessment of soil containing multiple pollutants from industrial chemical parks.