Wang Congcong, Xiao Xinzong, Zhou Xiongdong, Li Xiaoli, Zhang Jiahao, Wang Ruiyu, Liu Kai, Wei Yaoguo, Xu Mengzhen
State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084, China.
China South to North Water Diversion Middle Route Corporation Limited, Beijing, 100038, China.
Water Res. 2025 Jul 19;286:124260. doi: 10.1016/j.watres.2025.124260.
Large-scale water diversion projects play a critical role in the redistribution of essential water resources. Despite their crucial role in maintaining water quality and ecosystem stability in water diversion projects, a deeper understanding of the transport mechanism of phytoplankton in water diversion has yet to be thoroughly explored. A systematic investigation was conducted to better understand the ecological processes related to phytoplankton in the mammoth Middle Route of the South-North Water Diversion Project. Methods including β-diversity partitioning, null model, and generalized linear model were applied to analyze the process and driving mechanism of the assembly of phytoplankton communities. Results indicated that the temporal and spatial variation of phytoplankton in the canal was mainly regulated and controlled by Chlorophyta and Bacillariophyta. The β-diversity of phytoplankton throughout various seasons was mainly driven by species turnover, and was less influenced by dispersal limitation. On a year-long time scale, stochastic processes dominated. However, the relative weights of stochastic and deterministic processes varied with seasons. Phytoplankton communities were primarily influenced by stochastic processes in summer and autumn, and by deterministic processes in winter and spring. Seasonal and season-related factors (e.g., water temperature, dissolved oxygen) had a much greater impact on the β-diversity of phytoplankton than location and location-related factors (e.g., permanganate index). Further analyses showed that phytoplankton communities exhibited characteristics of stochastic assembly in summer and autumn. In winter and spring, however, the composition of phytoplankton communities was significantly regulated by the variations in turbidity, flow velocity, and dissolved organic matter. The above results revealed a unique mechanism: artificial water diversion projects weakened spatial heterogeneity via hydrologic homogeneity, thereby redirecting the main control axis of phytoplankton community assembly towards the temporal dimension. Based on the above findings, we recommend implementing seasonally differentiated real-time algae monitoring and a rapid response mechanism to more effectively address potential ecological risks, optimize water quality management, and ensure ecological safety in long-distance water diversion projects.
大型调水工程在重要水资源的重新分配中发挥着关键作用。尽管它们在维持调水工程中的水质和生态系统稳定性方面起着至关重要的作用，但对调水过程中浮游植物输运机制的深入理解尚未得到充分探索。为了更好地了解南水北调中线工程中与浮游植物相关的生态过程，进行了一项系统调查。采用β多样性划分、零模型和广义线性模型等方法分析浮游植物群落组装的过程和驱动机制。结果表明，渠道中浮游植物的时空变化主要受绿藻门和硅藻门调控。浮游植物在不同季节的β多样性主要由物种周转驱动，受扩散限制的影响较小。在全年时间尺度上，随机过程占主导。然而，随机和确定性过程的相对权重随季节变化。浮游植物群落在夏季和秋季主要受随机过程影响，而在冬季和春季受确定性过程影响。季节性和与季节相关的因素（如水温、溶解氧）对浮游植物β多样性的影响远大于位置和与位置相关的因素（如高锰酸盐指数）。进一步分析表明，浮游植物群落在夏季和秋季表现出随机组装特征。然而，在冬季和春季，浮游植物群落的组成受浊度、流速和溶解有机物变化的显著调控。上述结果揭示了一种独特的机制：人工调水工程通过水文均匀性减弱了空间异质性，从而将浮游植物群落组装的主要控制轴转向时间维度。基于上述发现，我们建议实施季节性差异化的实时藻类监测和快速响应机制，以更有效地应对潜在生态风险，优化水质管理，并确保长距离调水工程中的生态安全。
