Based on the survey data of eight kinds of heavy metals in the Xiangshan Bay watershed during the flood season, the pollution status of heavy metals in water was analyzed. The potential ecological risks of heavy metals were evaluated based on the single factor pollution index (Pi), the Nemero comprehensive pollution index (Pn), and the heavy metal pollution index (HPI). Based on the correlation between land-use types and heavy metal concentrations, the sources of heavy metals were analyzed. The results show that the average concentration of heavy metals is in the order Fe > Mn > Zn > Cu > As > Cr > Pb > Cd. All heavy metal concentrations, except those of Mn and Fe, conform to the class I surface water environment quality standard. The risk level of heavy metals is low, and there is no pollution, but some contamination. Agricultural non-point source pollution is the main factor in the contamination of heavy metals. Overall, the heavy metals in the region have not reached the risk threshold. To reasonably avoid the risk of heavy metal pollution in the urban development process, it is important to strengthen the supervision of pollution sources based on agricultural non-point sources.
Keywords: Xiangshan Bay watershed; dissolved heavy metal; land-use; risk assessment; source analysis.