Risk Assessment of Heavy Metals in Sediments from Xiangshan Harbor, Sanmen Bay and Hangzhou Bay
Surface sediment samples were collected from 28 stations in the intertidal zones of Xiangshan Harbor, Sanmen Bay, and the southern coast of Hangzhou Bay, major fishery waters in Ningbo, to assess heavy metal pollution and ecological risk. Concentrations of Cu, Pb, Zn, Cd, Cr, Hg, and As were determined. Results showed that Cu and Cr were the primary超标 factors, with mean concentrations exceeding the Class I standard (GB 18668-2002) by factors of 1.03 and 1.1, respectively, in Xiangshan Harbor; in Sanmen Bay, Cr exceeded by 1.1 times, while Cu did not. In Hangzhou Bay, Cu and Cr were elevated but below the standard. Coefficients of variation (CV) for five metals in Hangzhou Bay exceeded 30%, indicating strong external influence. In Xiangshan Harbor, As showed strong variation, and in Sanmen Bay, Hg showed strong variation. The potential ecological risk indices (RI) were 38.5, 36.7, and 31.1 for Xiangshan Harbor, Sanmen Bay, and Hangzhou Bay, respectively, all indicating low ecological risk. Spatial distribution in Hangzhou Bay revealed a decreasing gradient from a chemical industrial park, suggesting industrial discharge as a primary source. The study provides baseline data for environmental management and recommends source control and bioremediation in high-risk areas.