Quantitative and Predictive Evaluation of Heavy Metal Pollution in Bay Ecosystems of Northern China: Characteristics, Accumulation, and Risk Assessment

The quantitative and predictive evaluation of heavy metal (HM) pollution threats remains limited in bay ecosystems. In the present study, multiple models were used to evaluate the characteristics, accumulation, and risk assessments of HMs in typical bays in northern China. The results revealed the following: (1) HMs were accumulated in the sediment of the selected bays, and their presence had a moderate ecological risk owing to the high concentrations of Cd and Hg. (2) Quantitative evaluation revealed that HM concentrations in these bays were within the safety threshold; however, the simulated health risks indicated that bivalve HM exposure could not be considered negligible with the probability of high accumulation. (3) HMs showed accumulation heterogeneity in the sediment and bivalves due to the geochemical and physical indexes of the bay ecosystems. Geochemical properties, including sedimentary organic matter (SOM), grain size, and sediment texture, affected Cd and Hg accumulation in the sediment and the bioaccumulation of As in bivalves, whereas physical properties, including temperature and salinity, influenced the bioaccumulation of Cd and Cu through bivalves. Overall, these results provide novel insights into HM pollution in terms of accumulation heterogeneity and support valuable implications to ensure the accurate control of HM pollution in bay ecosystems.