Ecological risk assessment and source apportionment of heavy metals in sediments of a typical marine reservoir in the East China Sea: A case study of xuanmen bay marine reservoir

This study explores the distribution, ecological risks, and sources of heavy metals in the sediments of the Xuanmen Bay marine reservoir in eastern China. Surface sediment samples were collected during both the wet and dry seasons in 2023 and analyzed for eight heavy metals: copper (Cu), zinc (Zn), nickel (Ni), chromium (Cr), lead (Pb), cadmium (Cd), mercury (Hg), and arsenic (As), in addition to pH and total organic carbon (TOC). The ecological risk was assessed using the Potential Ecological Risk Index, while source analysis was conducted through Positive Matrix Factorization (PMF).

The findings reveal that heavy metal concentrations were generally higher during the wet season than in the dry season, with Regions I and II exhibiting the highest levels. Metal correlations were stronger in the wet season, displaying negative correlations with pH and positive correlations with TOC. Although the overall potential ecological risk in the reservoir was low, risk levels were heightened during the wet season, especially for Cd, Cu, and Hg in Region II.

PMF analysis identified industrial activities as the primary sources of heavy metal pollution, including metal processing, agricultural runoff, electroplating, non-ferrous metal smelting, and oil pollution resulting from the manufacturing of automobiles, machinery, and valve components. Notably, the metalworking and electroplating industries emerged as the most significant contributors to this pollution.

This study offers valuable insights and data for effectively managing heavy metal pollution in the Xuanmen Bay Marine Reservoir.