Heavy metal sources and associated risk in response to agricultural intensification in the estuarine sediments of Chaohu Lake Valley, East China.

In this study, the source and risk associated with heavy metals in the estuarine sediments of Chaohu Lake Valley in East China were studied. The results demonstrated that most metal contents (Cd, Pb and Zn) increased continuously from 0.21, 8.05 and 73.76 mg/kg in the substrate to 0.33, 17.20 and 100.22 mg/kg in the surface sediments on average, respectively, in all ten estuaries evaluated. In addition, the high proportion of chemically reactive forms of Cd (18.10-33.60%) implied a moderately high risk, while the risk associated with Pb and Zn was moderate in most estuaries. Enrichment factor (EF) and cluster analysis (CA) were conducted to assess the metal sources. The EF values of Cd, Pb and Zn (4.96, 3.68 and 2.25, respectively) indicated that they had accumulated in the estuarine sediments. Additionally, CA suggested that their primary sources were anthropogenic, namely the extensive use of fertilizers. Therefore, heavy metal pollution due to agricultural intensification in Chaohu Lake Valley should be taken into account during the formation of valley management strategies for the water environment.