Ecological risk assessment and source identification of heavy metal in dredged sediments from the Gaoyou section of the Beijing- Hangzhou Grand Canal

Heavy metals demonstrate a marked tendency to accumulate in riverine sediments, primarily attributed to their chemical persistence and intrinsic toxicity, thereby posing latent long-term threats to both ecosystem integrity and human health. This study aimed to examine the occurrence of heavy metals (Hg, As, Cd, Cu, Zn, Pb, Ni, and Cr) in dredged sediments obtained from the Gaoyou section of the Beijing-Hangzhou Grand Canal. The geoaccumulation index (Igeo) and potential ecological risk index (RI) were employed to evaluate the heavy metal pollution levels in the sediments and their associated ecological risks. Meanwhile, principal component analysis (PCA) and positive matrix factorization (PMF) models were used as analytical tools to identify and quantify the sources of the heavy metals. The findings revealed that Hg, As, Cd, Cu, Zn, Pb, Ni, and Cr had mean concentrations of 0.289, 9.82, 0.051, 29.63, 70.33, 36.17, 32.54, and 53.54 mg/kg, respectively. Notably, the mean concentrations of Cu, Zn, Pb, and Ni exceeded the soil background values of Jiangsu Province. Results from I _geo and RI analyses indicated slight enrichment of Hg, Pb, and Cu. The comprehensive ecological risk remained low, with Hg being the primary contributor. Based on PCA and PMF analyses, three primary sources of heavy metals were identified. Hg was primarily derived from industrial sources such as coal combustion; Pb, Ni, Zn, and Cu were mainly attributed to emissions from shipping and transportation; while As, Cr, and Cd occurred at low concentrations, indicating their predominantly natural origins.