Controlling internal nitrogen and phosphorus loading using Ca-poor soil capping in shallow eutrophic lakes: Long-term effects and mechanisms

文献类型： 外文期刊

第一作者： Sun, Chuanzhe

作者： Sun, Chuanzhe;Zhong, Jicheng;Yu, Juhua;Wen, Shuailong;Zhang, Lei;Yin, Hongbin;Fan, Chengxin;Pan, Gang;Mortimer, Robert J. G.;Pan, Gang;Yu, Juhua;Sun, Chuanzhe;Wen, Shuailong

作者机构：

关键词： Eutrophication; Internal nutrient loading; Capping; Ca-poor clean soil; Sediment-water interface; Shallow lakes

期刊名称：WATER RESEARCH （ 影响因子：12.8； 五年影响因子：13.3 ）

ISSN： 0043-1354

年卷期： 2023 年 233 卷

页码：

收录情况： SCI

摘要： Clean soil is a potential capping material for controlling internal nutrient loading and helping the recovery of macrophytes in eutrophic lakes, but the long-term effects and underlying mechanisms of clean soil capping under in-situ conditions remain poorly understood. In this study, a three-year field capping enclosure experiment combining intact sediment core incubation, in-situ porewater sampling, isotherm adsorption experiments and analysis of sediment nitrogen (N) and phosphorus (P) fractions was conducted to assess the long-term perfor-mance of clean soil capping on internal loading in Lake Taihu. Our results indicate that clean soil has excellent P adsorption and retention capacity as an ecologically safe capping material and can effectively mitigate NH4+-N and SRP (soluble reactive P) fluxes at the sediment-water interface (SWI) and porewater SRP concentration for one year after capping. The mean NH4+-N and SRP fluxes of capping sediment were 34.86 mg m- 2 h-1 and-1.58 mg m- 2 h-1, compared 82.99 mg m- 2 h-1 and 6.29 mg m- 2 h-1 for control sediment. Clean soil controls internal NH4+-N release through cation (mainly Al3+) exchange mechanisms, while for SRP, clean soil can not only react with SRP due to its high Al and Fe content, but also stimulate the migration of active Ca2+ to the capping layer, thus precipitating as Ca-bound P (Ca-P). Clean soil capping also contributed to the restoration of macrophytes during the growing season. However, the effect of controlling internal nutrient loading only lasted for one year under in-situ conditions, after which the sediment properties returned to pre-capping conditions. Our results highlight that clean Ca-poor soil is a promising capping material and further research is needed to extend the longevity of this geoengineering technology.

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