Temporal and Spatial Distribution, Ecological Risk Assessment and source Identification of heavy Metals in the Surface Sediments of Lake Taihu Basin, China

In this study, sediment samples from the 4 regions of Lake Taihu Basin were collected to analyze the distribution characteristics, potential risks and possible sources of heavy metal pollution (Cr, Cu, Zn, As, Cd, Pd and Hg). The results showed that the concentrations and risks from heavy metals were lower in 2018 than in 2012, while the average concentrations of the 7 heavy metals were lower than the upper chemical exceedance level (UCEL). Spatially, the contents were higher in the eastern plains and Yangtze Riverside regions. The results of the risk assessment indicated that all heavy metals other than Cd were at low-pollution levels. In contrast, Cd showed high risk (Eir 255.425 in 2012, Eir 149.293 in 2018), which led to the high comprehensive potential ecological risk level in the western hilly region in 2012. In 2018, the risk for the entire Lake Taihu Basin decreased to a moderate level. In addition, the results of principal component analysis showed that Zn mainly originated from agriculture and zinc ore, Cd originated from metallurgical industries and pesticides, portions of Cu and Cr may have come from natural sources, and the other portions and other heavy metals mostly came from chemical industries such as electroplating. This study thoroughly analyzed the heavy metal pollution status of the Lake Taihu Basin surface sediments and provided a scientific basis for preventing and controlling water pollution in the region.