Abstract：
Planktonic microorganisms play an important role in urban aquatic ecosystems; however, environmental changes significantly affect their role in the degradation and transformation of pollutants. The highly artificial North Canal River was chosen as the research area in this study. Seasonal changes in planktonic microbial community structure were studied using 16S rRNA high-throughput sequencing. The seasonal change mechanism of planktonic microbial diversity in urban rivers supplied with reclaimed water and its response relationship with environmental parameters were examined. The results showed that there were significant seasonal changes in the diversity and structure of the planktonic microbial community. The alpha diversity in summer was significantly higher than that in spring, owing to the enhancement of water diffusion capacity caused by seasonal rainfall and physical disturbance of the reclaimed water supply. The beta diversity of the planktonic microbial community in summer was weakened compared to that in spring, also owing to the enhancement of water diffusion capacity. Seasonal runoff and temperature were the main driving factors of the seasonal variation in hydrology and water quality in the highly artificial urban river. The changes in NO2--N and TP caused by seasonal runoff and temperature change were the main reason for planktonic microbial diversity changes in the river. The reductive environment of the river was caused by static and discontinuous flow in the spring. Anaerobic bacteria such as Bacteroidetes related to the degradation of dissolved organic matter and Gracilibacteria related to the denitrification process were dominant in the river. Seasonal runoff and frequent rainfall in summer, as well as the increase in the opening and closing frequency of river sluice gates, enhanced the reoxygenation capacity of the river. This significantly alleviated nutrient pollution in the North River Cannel. Additionally, aerobic bacteria and facultative anaerobic bacteria were dominant species in the river during spring. Cyanobacteria with high temperature characteristics, Chloroflexi and other autotrophic microorganisms, as well as Acidobacteria and Gemmatimonadetes played an important role in the degradation and transformation of pollutants. The results of this study have practical significance for urban river pollution control and ecological restoration with reclaimed water as the recharge water source.
摘要：
浮游微生物在城市水生态系统中起着重要作用；然而，环境变化显著影响它们在污染物降解和转化中的作用。本研究选择了高度人工的北运河河作为研究区域。使用16SrRNA高通量测序研究了浮游微生物群落结构的季节性变化。研究了再生水供应的城市河流中浮游微生物多样性的季节变化机理及其与环境参数的响应关系。结果表明，浮游微生物群落的多样性和结构存在显著的季节性变化。夏季的α多样性显著高于春季，由于季节性降雨和再生水供应的物理扰动导致水扩散能力增强。夏季浮游微生物群落的β多样性较春季减弱，还由于水扩散能力的增强。季节性径流和温度是高度人工城市河流水文和水质季节性变化的主要驱动因素。季节径流和温度变化引起的NO2--N和TP的变化是河流浮游微生物多样性变化的主要原因。河流的还原环境是由春季的静态和不连续流量引起的。在河流中，与溶解有机物降解相关的拟杆菌和与反硝化过程相关的拟杆菌等厌氧细菌占主导地位。夏季季节性径流和频繁降雨，以及河闸启闭频率的增加，增强了河流的复氧能力。这大大减轻了北河Cannel的养分污染。此外,春季，需氧菌和兼性厌氧菌是河流中的优势种。蓝藻具有高温特性，氯氟菌和其他自养微生物，以及酸性细菌和Gemmatimonadetes在污染物的降解和转化中起着重要作用。本研究结果对以再生水为补给水源的城市河流污染治理和生态修复具有现实意义。
