title: Evaluation of in situ simulated dredging to reduce internal nitrogen flux across the sediment-water interface in Lake Taihu, China.
abstract: Sediment dredging is considered an effective restoration method to reduce internal loading of nitrogen (N) and phosphorus (P) in eutrophic lakes. However, the effect of dredging on N release from sediments to overlying water is not well understood. In this study, N exchange and regeneration across the sediment-water interface (SWI) were investigated based on a one-year simulated dredging study in Lake Taihu, China. The results showed low concentrations of inorganic N in pore water with low mobilization from the sediments after dredging. The calculated fluxes of NO3(-)-N from post-dredged sediments to overlying water significantly increased by 58% (p < 0.01), while those of NH4(+)-N dramatically decreased by 78.2% after dredging (p < 0.01). N fractionation tests demonstrated that the contents and lability of N generally declined in post-dredged sediments. Further high-throughput sequencing analysis indicated that relative abundance of the bacterial communities decreased, notably by 30% (compared with undredged sediments). The estimated abundance of Nitrospira enhanced, although the relative abundance of Thiobacillus, Sterolibacterium, Denitratisoma, Hyphomicrobium, Anaeromyxobacter and Caldithrix generally declined after dredging. Therefore, dredging reduced N mobilization from the sediments, which primarily due to decreases in N mobility, in organic matter (OM) mineralization potential and in the bacterial abundance of post-dredged sediments. Overall, to minimize internal N pollution, dredging is capable of effectively reducing N release from sediments. In addition, the negative side effect of dredging on removal of NO3(-)-N and NO2(-)-N from aquatic ecosystems should be paid much more attention in future.
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Number 73 Beijing East Road, 210008 Nanjing, PR China. Electronic address: juhuayu1984@gmail.com.
authors.forename: Juhua
authors.initials: J
authors.lastname: Yu
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Number 73 Beijing East Road, 210008 Nanjing, 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, Number 73 Beijing East Road, 210008 Nanjing, PR China. Electronic address: jczhong@niglas.ac.cn.
authors.forename: Jicheng
authors.initials: J
authors.lastname: Zhong
authors.affiliation: Key Laboratory of Forestry Ecological Engineering of Jiangsu Province, Nanjing Forestry University, Nanjing 210037, PR China. Electronic address: ecoenvylz@163.com.
authors.forename: Yinlong
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Number 73 Beijing East Road, 210008 Nanjing, PR China. Electronic address: chwang@niglas.ac.cn.
authors.forename: Changhui
authors.initials: C
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Number 73 Beijing East Road, 210008 Nanjing, PR China. Electronic address: leizhang@niglas.ac.cn.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
mesh_terms: D001419:Bacteria / Q000187:drug effects; D002681:China; D052918:Environmental Restoration and Remediation / Q000379:methods*; D019015:Geologic Sediments / Q000737:chemistry; D060106:Lakes / Q000737:chemistry*; D009584:Nitrogen / Q000032:analysis; D058458:Nitrogen Cycle; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical; D009584:Nitrogen
keywords: Nitrogen; Regeneration; Release flux; Sediment dredging; Sediment-water interface