Comprehensive effects of sediment dredging on environmental risk and bioavailability of heavy metals from the sediment of Lake Taihu, China

Chuanzhe Sun; Wanqing Gong; Gang Pan; Robert J G Mortimer; Enqin Yao; Shuailong Wen; Musong Chen; Jicheng Zhong

doi:10.1016/j.jhazmat.2024.136789

Comprehensive effects of sediment dredging on environmental risk and bioavailability of heavy metals from the sediment of Lake Taihu, China

J Hazard Mater. 2024 Dec 4:484:136789. doi: 10.1016/j.jhazmat.2024.136789. Online ahead of print.

Authors

Chuanzhe Sun¹, Wanqing Gong², Gang Pan³, Robert J G Mortimer⁴, Enqin Yao⁵, Shuailong Wen², Musong Chen², Jicheng Zhong⁶

Affiliations

¹ 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.
² State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China.
³ School of Humanities, York St John University, Lord Mayor's Walk, York YO31 7EX, UK; School of Chemical and Environmental Sciences, Guangdong Ocean University, Zhanjiang 524088, PR China.
⁴ School of Humanities, York St John University, Lord Mayor's Walk, York YO31 7EX, UK.
⁵ Huzhou Ecological and Environmental Monitoring Center of Zhejiang Province, Huzhou, 313000, PR China.
⁶ State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China. Electronic address: jczhong@niglas.ac.cn.

PMID: 39647333
DOI: 10.1016/j.jhazmat.2024.136789

Abstract

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_geo), 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_geo and RI method, and that dredging significantly reduced the total content of sediment HM, particularly for Cu, Zn, and Cd, and its I_geo 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.

Keywords: Bioavailability; Environmental and ecological risk assessment; Heavy metals; Lake Taihu; Sediment dredging.