Abstract:
In order to understand the variations in heavy metals pollution levels and source structures in surface sediments of Rudong coastal zone, Jiangsu Province, over different years, surface sediments were collected in 2011 and 2018. The concentrations of seven heavy metals (Cu, Pb, Cd, Zn, Cr, Hg, and As) were measured to assess pollution levels and identify their sources. The results showed that Cd, Hg, and As exhibited relatively high concentrations in 2011, while Hg, Pb, and Cd concentrations were more prominent in 2018. Except for As, the concentrations of heavy metals in 2018 were higher than those in 2011. In 2011, the heavy metal pollution levels in the sediments ranged from mild to moderate, with Cd and As being the most significant pollutants. In 2018, the pollution levels ranged from mild to severe, with Hg and Cd as the dominant pollutants. The sources of Cu, Pb, Cd, Zn, and Cr in 2011 were identified as a mixed contribution from natural sources, land-port traffic emissions, and industrial wastewater discharge (62.41%), while Hg and As were mainly influenced by petrochemical industrial activities and agricultural and fishery practices (37.59%). In 2018, Cu, Pb, and Cr were primarily attributed to a combination of natural sources and land-port traffic emissions (44.83%), Cd and Hg were mainly derived from industrial wastewater discharge (31.03%), and Zn and As were influenced by petrochemical industrial activities and agricultural and fishery activities (24.14%). The variations in heavy metal concentrations and their source contributions were closely linked to changes in the industrial structure. The green transformation of agricultural and fishery activities in primary industries have led to a reduction in As pollution and its source contribution. Meanwhile, the increased energy consumption in secondary industries and the intensification of transportation activities in tertiary industries have contributed to the heightened pollution levels of most heavy metals.