Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) are pollutants of global concern due to their toxicity, bioaccumulation, and long-term ecological consequences in marine ecosystems. Their presence and associated hazards were investigated in the water–sediment system of the Xiangshan Harbour Watershed, a zone influenced by both industrial and agricultural activities. Samples were obtained from 19 key locati...