Heavy metal exposure risk to black-winged stilt (Himantopus himantopus) in a typical industrial city in northwest of China†

Heavy metal pollution poses a critical threat to waterfowl, and a quantitative risk assessment model is significant for accurately evaluating the threat level and providing early warning of the potential harm before the situation becomes nonreversible. In this study, the exposure risk of heavy metals to black-winged stilt (Himantopus himantopus) was assessed in three districts (Dawukou District, Huinong District and Pingluo County) of Shizuishan, an important industrial city in northwestern China. The results showed that Cr, Cd, Pb and Zn concentrations in habitat soil or water exceeded the local background levels or the permissible safe limits, which were the main heavy metal pollutants in the habitats. Cd and Cr were the most major heavy metals causing potential ecological hazards in the habitat. The food pathway and soil pathway were the main routes of exposure to heavy metals in waterfowl, and Cr was the priority pollutant in waterfowl conservation in Shizuishan due to the high health risk grade. The combined risks of heavy metals were high in all three districts; however, the potential health hazards to waterfowl in Dawukou District, a region historically associated with coal mining activities that has undergone years of ecological remediation, especially need to focus attention. Our findings provide a scientific basis for waterfowl conservation and their habitat improvement management in industrial cities.