Efficacy of dredging engineering as a means to remove heavy metals from lake sediments

Musong Chen; Shiming Ding; Shuaishuai Gao; Zhen Fu; Wanying Tang; Yuexia Wu; Mengdan Gong; Dan Wang; Yan Wang

doi:10.1016/j.scitotenv.2019.02.057

Efficacy of dredging engineering as a means to remove heavy metals from lake sediments

Sci Total Environ. 2019 May 15:665:181-190. doi: 10.1016/j.scitotenv.2019.02.057. Epub 2019 Feb 5.

Authors

Musong Chen¹, Shiming Ding², Shuaishuai Gao³, Zhen Fu⁴, Wanying Tang⁴, Yuexia Wu¹, Mengdan Gong⁵, Dan Wang⁶, Yan Wang⁷

Affiliations

¹ State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
² State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China. Electronic address: smding@niglas.ac.cn.
³ State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China.
⁴ Nanjing University of Science and Technology, 200 Xiaolingwei Road, 210094 Nanjing, China.
⁵ Shanghai Water Source Construction Development Co., Ltd., Shanghai 200437, China.
⁶ Shanghai Waterway Engineering Design and Consulting Co., Ltd., Shanghai 200120, China.
⁷ State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; Nanjing EasySensor Environmental Technology Co., Ltd, Nanjing 210018, China.

PMID: 30772548
DOI: 10.1016/j.scitotenv.2019.02.057

Abstract

Dredging is used worldwide to remove polluted sediments from water bodies. However, the dredging efficacy remains hard to identify. Here, we studied the efficacy of dredging engineering as a means to remove Cu, Cd, and Pb from polluted lake sediments, after six years of completion. Dissolved metals and DGT-labile metals were quantified in the non-dredged and post-dredged sediments by high-resolution dialysis (HR-Peeper) and diffusive gradients (DGT) in thin films techniques. April and July measurements showed that dredging was effectively remediate the polluted sediments. The dissolved Pb, Cd, and Cu contents decreased up to 30%, 44%, and 26%, and the DGT-labile contents decreased up to 51%, 27%, and 33% compared with the contents in the non-dredged zone. Dredging was thus proven efficient in decreasing the labile metal fractions, increasing the capacity of available solids to bind metals, and slowing the leaching of metals from available solids in the post-dredged sediments. In October and January, the dredging efficacy was counteracted by the decomposition of algae, which increased the dissolved and DGT-labile metal concentrations in the post-dredged zone.

Keywords: Dredging engineering; Heavy metals; Passive sampling; Sediment.