Using multi-medium factors analysis to assess heavy metal health risks along the Yangtze River in Nanjing, Southeast China

Abstract

In the environmental ecosystem, there are no absolutely isolated risks. Each risk might be influenced by multiple environmental factors and the factors’ interaction within the specific system. Hence, health risk assessments of heavy metal contamination must consider multiple environmental media and their transfer processes from one medium to another. Integrated assessments provide a new perspective for evaluating many factors, such as the potential ecological risks of soils, sediments, plants, and the transportation of heavy metals in these media, which influences the health risks. In this study, the main influencing factors for human health risk from heavy metals along the Yangtze River in Nanjing, Southeast China, were explored. The contents of five heavy metals were measured in sediment-soil-plant, including cadmium (Cd), lead (Pb), copper (Cu), zinc (Zn), and chromium (Cr). The Cd displayed the highest potential ecological risk in soils and sediments, as it possessed high bioaccessibility (BA; 0.17 ± 0.211) and bioaccumulation factor (BCF; 0.35 ± 0.33). The 5.97% of the target hazard quotient (THQ) of Cd were higher than 1, indicating a potential health risk in plant consumption. Based on the geodetector model, determinant power (DP) valves for factors influencing health risk strongly suggest that plant types (0.479) has a highest effect, followed by soil organic matter (SOM; 0.292), and the BA of heavy metals (0.107). The results also indicate that pollution from the upper reaches of the river, and agricultural activities, had a greater impact on health risk than did industrial activities in the study area. Thus, regular monitoring and source control for Cd, along with integrated agricultural management practices should be implemented to control and reduce heavy metal inputs and improve the safety of cultivated plants.