title: Effects of riverine suspended particulate matter on the post-dredging increase in internal phosphorus loading across the sediment-water interface.
abstract: Dredging is frequently used in the river mouths of eutrophic lakes to reduce internal phosphorus (P) loading from the sediment. However, the accumulation of P-adsorbed suspended particulate matter (SPM) from the inflowing rivers negatively affects the post-dredging sediment-water interface and ultimately increases internal P loading. Here, a 360-d experiment was carried out to investigate the influence of riverine SPM on the efficacy of dredging in reducing internal P loading. SPM was added to dredged and undredged sediments collected from the confluence area of Lake Chaohu. Several parameters related to internal P loading, including oxygen profile, soluble reactive P, and ferrous iron across the sediment-water interface, organic matter, alkaline phosphatase activity, and P fractions, were measured throughout the experimental period. The results showed that the P content (especially mobile P) in the sediment increased to the pre-dredging level with the accumulation of SPM in the dredged sediment. In addition, the P flux across the sediment-water interface increased with the accumulation of SPM. Several characteristics of SPM, including high organic matter content, mobile P, high activity of alkaline phosphatase, and high biological activity, were considered correlated with the post-dredging increase in internal P loading. Overall, this study showed that the heavily contaminated riverine SPM regulates the long-term efficacy of dredging as a nutrient management option in the confluence area. Management is needed to avoid or reduce this phenomenon during dredging projects of this nature.
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Liu
authors.affiliation: College of Hydrology and Water Resource, Hohai University, Nanjing 210098, PR China.
authors.forename: Shiguang
authors.initials: S
authors.lastname: Shao
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China.
authors.forename: Qiushi
authors.initials: Q
authors.lastname: Shen
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China. Electronic address: cxfan@niglas.ac.cn.
authors.forename: Chengxin
authors.initials: C
authors.lastname: Fan
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
authors.forename: Qilin
authors.initials: Q
authors.lastname: Zhou
mesh_terms: D000327:Adsorption; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry; D060106:Lakes; D052638:Particulate Matter / Q000032:analysis*; D010758:Phosphorus / Q000032:analysis*; D045483:Rivers / Q000737:chemistry; D014867:Water; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D052638:Particulate Matter; D014874:Water Pollutants, Chemical; D014867:Water; D010758:Phosphorus
keywords: Dredging; Internal phosphorus loading; Lake Chaohu; Sediment-water interface; Suspended particulate matter