Yu Mao-Lei, Hong Guo-Xi, Xu Hai, Zhu Guang-Wei, Zhu Meng-Yuan, Quan Qiu-Mei
College of Environmental Science and Engineering, China West Normal University, Nanchong 637009, China.
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
Huan Jing Ke Xue. 2019 Feb 8;40(2):603-613. doi: 10.13227/j.hjkx.201804047.
The location at which the Liangxi River meets Meiliang Bay of Lake Taihu was selected to explore the influence and controlling factors of algal blooms on the connected rivers. The cyanobacterial particulates and water quality parameters including nitrogen, phosphorus, and dissolved oxygen were monitored daily during the summer bloom season. The spatial variation in water quality parameters along the river were also surveyed, and data from hydrological and meteorological factors such as discharge, temperature, and wind field characteristics over the same period were collected to help investigate the effects of cyanobacterial blooms on the water quality of connected rivers. The results showed that the total fresh biomass of algal blooms entering Liangxi River for three months during the summer cyanobacterial bloom period in Meiliang Bay was 9733 t, which was similar to the amount harvested from the entire lake throughout the year. The flux of water bloom particles to the river varied widely, ranging from 75-496 t·d, with an average of 105 t·d. The flux was primarily controlled by hydrological and meteorological conditions. Water volume, temperature, and wind direction were the most important influencing factors. Lake water with a large amount of cyanobacterial particles entering the river can significantly improve the dissolved oxygen, ammonia-nitrogen, and other qualities of the river water in the city. It also significantly increased the concentrations of nutrients such as particulate nitrogen and phosphorus in the river, while it had a relatively weak effect on dissolved nitrogen and phosphorus. Spatially, the chlorophyll a concentration rapidly decreased with increasing distance from the lake, and the concentration of nitrogen and phosphorus exist as particulate cyanobacteria also declined. Upon being discharged into the canal 7 km away, the cyanobacterial particles were largely decomposed, and chlorophyll content from the phytoplankton collected from the river by a 67 μm net decreased from 152.93 μg·L to 1.99 μg·L. The results indicated that lakes plagued with cyanobacterial blooms have a great impact on the water quality of surrounding rivers. Although the connection between rivers and lakes can effectively relieve black spots and solve the black and odorous phenomenon in urban rivers, it had a great impact on nutrients concentration in the rivers. Depending on the different protection targets of rivers and lakes, lake water blooms and hydro-meteorological factors should be considered during water transfer management to optimize the water ecological services of lakes and rivers.
选取梁溪河与太湖梅梁湾交汇的位置，以探究蓝藻水华对相连河流的影响及其控制因素。在夏季水华暴发季节，每天监测蓝藻颗粒以及包括氮、磷和溶解氧在内的水质参数。同时还对沿河流向的水质参数空间变化进行了调查，并收集了同期的流量、温度和风场特征等水文气象因素数据，以帮助研究蓝藻水华对相连河流的水质影响。结果表明，梅梁湾夏季蓝藻水华暴发期的三个月内，进入梁溪河的蓝藻总鲜生物量为9733吨，这与全年从整个太湖收获的量相近。水华颗粒进入河流的通量变化很大，范围为75 - 496吨·天，平均为105吨·天。通量主要受水文气象条件控制。水量、温度和风向是最重要的影响因素。大量含有蓝藻颗粒的湖水进入河流，可显著改善城市河流水体的溶解氧、氨氮等水质指标。同时也显著增加了河流中颗粒态氮、磷等营养物质的浓度，而对溶解态氮、磷的影响相对较弱。在空间上，叶绿素a浓度随着离湖距离的增加而迅速降低，以颗粒态蓝藻形式存在的氮、磷浓度也随之下降。在排放至7公里外的运河时，蓝藻颗粒大部分被分解，用67μm网从河中采集的浮游植物叶绿素含量从152.93μg·L降至1.99μg·L。结果表明，受蓝藻水华困扰的湖泊对周边河流的水质有很大影响。虽然河湖连通能有效缓解城市河流的黑臭现象，但对河流中的营养物质浓度有很大影响。根据河湖不同的保护目标，在调水管理过程中应考虑湖泊水华和水文气象因素，以优化河湖的水生态服务功能。
