Sun Chuanzhe, Gong Wanqing, Pan Gang, Mortimer Robert J G, Yao Enqin, Wen Shuailong, Chen Musong, Zhong Jicheng
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China; Department of Ocean Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon 999077, Hong Kong SAR, PR China.
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China.
J Hazard Mater. 2025 Feb 15;484:136789. doi: 10.1016/j.jhazmat.2024.136789. Epub 2024 Dec 4.
The comprehensive effects of environmental dredging on heavy metals (HM) are still uncertain. This study comprehensively evaluates the long-term effects of dredging on the environmental risk and bioavailability of HM (Cu, Ni, Zn, Pb, Cd, Cr, and As) in Lake Taihu, China, by comparing simulated dredged treated (D) and undredged (UD) sediment cores under in-situ conditions for one year. Threshold effect level (TEL), geological accumulation index (I), potential ecological risk index (RI), and ratios of secondary phase and primary phase (RSP) methods were used to assess the environmental risk of sediment HM; and the diffusive gradient in thin-films (DGT) technique was applied to assess the bioavailability of sediment HM. The results indicate that Cd was the most polluted metal assessed by the I and RI method, and that dredging significantly reduced the total content of sediment HM, particularly for Cu, Zn, and Cd, and its I and RI index, but caused a slight effect on its fractionation and distinct effect on RSP index. These indices changed independently and seasonally. Porewater analysis suggested higher HM concentrations in summer and winter may cause corresponding deterioration in overlying water. DGT analysis suggested a large proportion of metal-DOM complexes and showed that dredging reduced the bioavailability of Ni, Cd, and As but had a mixed impact (effective and/or ineffective impact varied with seasons) on other metals. These findings highlight the complexity of dredging effects on sediment HM dynamics, underscoring the importance of seasonal monitoring and multi-geoengineering techniques targeted at total and specific metals.
