滇池微囊藻属水华严重时，大量有毒的湖泊型微囊藻属会进入普渡河上游河段（即螳螂川）。螳螂川的起始段水面会出现明显的蓝绿色聚集物，严重影响河流生态及两岸居民的生活。但是，由于微囊藻属在普渡河中的空间变化过程及相应的控制因子尚并不清晰，因此难以判断滇池对于普渡河的影响范围及影响程度。论文针对河流水体富营养化问题建立了大型河流污染源解析方法（空间区域划分，区域内重点指标确定，重点指标污染源解析），并用其分析了导致普渡河（螳螂川、普渡河下游及三条主要支流）水体富营养化的主要污染来源。结果表明滇池对普渡河的螳螂川河段影响最显著，是螳螂川水体富营养化的主要污染源，并导致螳螂川河段富营养化程度最严重且水质空间差异最大。通过2013年6月和9月在滇池口及螳螂川沿程采样分析发现，总藻细胞密度沿程逐渐减少，但9月的减少速率缓于6月，滇池对螳螂川的影响范围随时间变化。来自滇池的微囊藻属在螳螂川沿程逐渐被中心纲硅藻和绿球藻目绿藻所取代。该河段营养盐充足、水温适宜，光强是藻类的主要竞争资源，沿程加剧的水体紊动是导致不同藻属藻细胞密度空间变化的主要原因。在野外采样的基础上，论文构建了受水体紊动影响的微囊藻属和小球藻属垂向光竞争模型。模型中考虑了不同直径的微囊藻群体的浮力调节能力。通过模拟发现：微囊藻群体最大藻细胞密度出现在群体密度与水体密度相同的位置处；微囊藻属在水面会出现昼沉夜浮的现象，且该现象在紊动较弱的水体中更明显。水体紊动较弱时，藻属的垂向自迁移决定其垂向分布，因此，具有浮力调节能力的微囊藻属聚集在上层水体中，进行充分的光合作用，易取得竞争优势；水体紊动剧烈时，剧烈的紊动扩散促使竞争藻属的垂向分布趋于均匀，因此，双方获取光强的机会相同，生长速率较快的小球藻属易取得竞争优势。此外，论文选取水深和水体紊动描述水体动力特征，通过大量的模拟，绘制了不同初始藻细胞密度条件下藻属的竞争优势分布图：微囊藻属适宜生活在水深较深且紊动较弱的水体中；小球藻属适宜生活在水深较浅的水体中；两种藻属均不适宜生活在水深较深且紊动剧烈的水体中。大量的实际案例包括螳螂川中优势藻属的沿程变化均能证明：竞争优势分布图能够预测水动力的改变导致的优势藻属的转变。

In high-bloom seasons in Dianchi Lake, a large amount of lacustrine Microcystis would be transported to the upper reaches of Pudu River (namely Tanglang River). Hence, blue-green algal blooms have been a frequent sight at the origin of the Tanglang River, which may cause many serious problems for river ecology as well as drinking water security. However, the spatial variations of the Microcystis abundance and the corresponding influencing factors are still unclear. In the case, it is difficult to estimate both the scope and extent of the influence of the Dianchi Lake on the Pudu River. In this work, a set of pollution source apportionment for large rivers was established. The method consisted of three steps: sampling station grouping, identification of key pollutants and source apportionment of key pollutants. The method was applied in the Pudu River (the Tanglang River, the lower Pudu River and three main tributaries) to analyse the source apportionments of pollutants leading to eutrophication. The results showed that the Dianchi Lake had the most significant impact on the Tanglang River. In addition, it was the main contributor for the eutrophication in the Tanglang River, which made the Tanglang River obviously more spatial heterogenous in water quality and more eutrophic than other reaches.Two field observations were conducted in the mouth of the Dianchi Lake and the Tanglang River in June and September 2013, respectively. The results showed that the total abundance gradually decreased along the river downstream. However, the decrease rate in September was slower than that in June. The influence scope of the Dianchi Lake on the Tanglang River varied with time. The Microcystis colonies from the Dianchi Lake were gradually replaced by centric diatoms and chlorococalean green algae in the middle and lower reaches of the river. Considering that the nutrients were rich and the water temperature was suitable, the incident light was the only competition resource. In addition, the differences in adaptability of different algae to changing hydrodynamics explained the variations of phytoplankton abundances along the Tanglang River.Based on the analysis of field observations, a vertical competition model for light between Microcystis and Chlorella under different hydrodynamic turbulences was developed. The buoyancy regulation of the Microcystis with different colony sizes was incorporated into the competition model. According to the simulation results, it was found that the largest abundance of the Microcystis showed up below the water surface. On the surface, the Microcystis colonies would sink in the daytime and float upwards in the night, which would be more obvious in the calm water. The vertical self-migration of the competition algae determined the vertical distributions of populations in the calm water while the vertical turbulent diffusion determined the vertical distributions in the turbulent water. Therefore, the buoyant Microcystis floated upwards to have fully photosynthesis and dominated in the calm water. However, the faster-growing Chlorella dominated in the turbulent water because both the phytoplanktons were distributed uniformly over depth. In addition, the depth of water and the turbulent diffusion were chosed to describe the water. The competitive advantage pictures were drawn through numerous model simulations. They revealed that the toxic and buoyant Microcystis was suitable to live in the calm and deep aquatic environment while the sinking Chlorella was well adapted to the shallow water. None of them could survive in the turbulent and deep water. The dominant algae would shift according to the changes in the turbulent diffusion and the depth of water. Many reported cases including the phytoplankton composition variations in the Tanglang River confirmed that the competitive advantage pictures could predict the shift in the dominant phytoplankton when the hydrodynamics change.