Seasonal and spatial distributions and possible sources of polychlorinated biphenyls in surface sediments of Yangtze Estuary, China

► PCBs in the estuarine surface sediments showed significant seasonal variations. ► The effects of the surface sediment properties on PCB distributions were studied. ► Light PCBs with 2-3 chlorines showed a predominant proportion. ► Atmospheric deposition and surface runoff were suggested as the major PCB sources.