Zhang Qimou, Huang Jiacong, Ji Yulai, Zhang Jing, Zhang Shuai, Gao Junfeng
Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 10094, China.
Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
J Environ Sci (China). 2025 Jan;147:189-199. doi: 10.1016/j.jes.2023.09.030. Epub 2023 Oct 3.
China's lowland rural rivers are facing severe eutrophication problems due to excessive phosphorus (P) from anthropogenic activities. However, quantifying P dynamics in a lowland rural river is challenging due to its complex interaction with surrounding areas. A P dynamic model (River-P) was specifically designed for lowland rural rivers to address this challenge. This model was coupled with the Environmental Fluid Dynamics Code (EFDC) and the Phosphorus Dynamic Model for lowland Polder systems (PDP) to characterize P dynamics under the impact of dredging in a lowland rural river. Based on a two-year (2020-2021) dataset from a representative lowland rural river in the Lake Taihu Basin, China, the coupled model was calibrated and achieved a model performance (R>0.59, RMSE<0.04 mg/L) for total P (TP) concentrations. Our research in the study river revealed that (1) the time scale for the effectiveness of sediment dredging for P control was ∼300 days, with an increase in P retention capacity by 74.8 kg/year and a decrease in TP concentrations of 23% after dredging. (2) Dredging significantly reduced P release from sediment by 98%, while increased P resuspension and settling capacities by 16% and 46%, respectively. (3) The sediment-water interface (SWI) plays a critical role in P transfer within the river, as resuspension accounts for 16% of TP imports, and settling accounts for 47% of TP exports. Given the large P retention capacity of lowland rural rivers, drainage ditches and ponds with macrophytes are promising approaches to enhance P retention capacity. Our study provides valuable insights for local environmental departments, allowing a comprehensive understanding of P dynamics in lowland rural rivers. This enable the evaluation of the efficacy of sediment dredging in P control and the implementation of corresponding P control measures.
由于人为活动导致的磷（P）过量排放，中国低地农村河流正面临严重的富营养化问题。然而，由于低地农村河流与周边地区的复杂相互作用，量化其磷动态具有挑战性。为此，专门设计了一个磷动态模型（River-P）来应对这一挑战。该模型与环境流体动力学代码（EFDC）和低地圩田系统磷动态模型（PDP）相结合，以表征低地农村河流疏浚影响下的磷动态。基于中国太湖流域一条典型低地农村河流的两年（2020 - 2021年）数据集，对耦合模型进行了校准，总磷（TP）浓度的模型性能达到了R>0.59，RMSE<0.04 mg/L。我们在研究河流中的研究表明：（1）沉积物疏浚控制磷的有效时间尺度约为300天，疏浚后磷截留能力增加74.8 kg/年，总磷浓度降低23%。（2）疏浚显著减少沉积物中磷的释放98%，同时分别增加磷的再悬浮和沉降能力16%和46%。（3）沉积物 - 水界面（SWI）在河流内的磷转移中起关键作用，再悬浮占总磷输入的16%，沉降占总磷输出的47%。鉴于低地农村河流具有较大的磷截留能力，种植大型植物的排水沟和池塘是提高磷截留能力的有前景的方法。我们的研究为当地环境部门提供了有价值的见解，有助于全面了解低地农村河流中的磷动态。这使得能够评估沉积物疏浚在控制磷方面的效果，并实施相应的磷控制措施。
