不同水源补给河流浮游植物群落结构特征及其与环境因子的关系

为探究不同水源补给河流浮游植物群落结构的差异，于2019年5~11月对北京市北运河水系和永定河水系7条河流进行逐月采样调查，分析不同水源补给河流浮游植物群落结构特征，并采用相关性分析和冗余分析（RDA）探究浮游植物群落与环境因子之间的关系.结果表明，7条河流共监测到9门127种浮游植物，硅藻、绿藻和蓝藻为优势种群，分别占种类总数的40.94%、34.65%和10.24%.浮游植物密度介于（0.24~169.14）×10⁶ cell·L^-1之间，均值为38.20×10⁶ cell·L^-1，生物量介于0.21~78.50 mg·L^-1之间，均值为16.49 mg·L^-1.浮游植物种类、密度和生物量均表现为：混合水源补给组>完全再生水补给组>无再生水补给组.浮游植物生物多样性指数H''均值介于1.56~2.18之间，均匀度指数J均值介于0.47~0.67之间，H''和J均表现为：无再生水补给组>混合水源补给组>完全再生水补给组.RDA排序结果表明，影响混合水源补给组浮游植物优势种的主要环境因子为DOC、pH、Chla、DO和TP，影响无再生水补给组和完全再生水补给组优势种的主要环境因子为TN、NH₄⁺-N、N/P和ORP.

Phytoplankton Community Structures and Their Relationship with Environmental Factors in Rivers Supplied with Different Water Sources

To understand differences in phytoplankton community structure in rivers supplied with different water sources, monthly sampling investigations were carried out for seven rivers of the Beiyun River system and Yongding River system during the period from May to November of 2019. We analyzed phytoplankton community structure characteristics of rivers supplied with different water sources and explored the relationship between phytoplankton community and environmental factors using correlation analysis and redundancy analysis (RDA). A total of nine phyla and 127 species of phytoplankton were identified in the seven rivers; Bacillariophyta, Chlorophyta, and Cyanophyta were the dominant species, accounting for 40.94%, 34.65%, and 10.24% of the total species, respectively. The phytoplankton species composition of three groups of rivers, namely the no-reclaimed water supply group (NR), fully reclaimed water supply group (RW), and mixed-reclaimed water supply group (MW), was mainly Bacillariophyta or Chlorophyta. The phytoplankton density ranged from (0.24-169.14)×10⁶ cell·L^-1 with an average of 38.20×10⁶ cell·L^-1, and the biomass ranged from 0.21-78.50 mg·L^-1 with an average of 16.49 mg·L^-1. Variations in the species numbers, density, and biomass of phytoplankton among groups were all shown as MW>RW>NR. The mean phytoplankton biodiversity index H'' ranged from 1.56-2.18, and the mean uniformity index J ranged from 0.47-0.67, overall in the moderate to heavy pollution range. The biodiversity index and evenness index were all shown as NR>MW>RW. RDA sequencing results indicated that the dominant phytoplankton species in the MW group were mainly related to DOC, pH, Chla, DO, and TP, whereas the dominant phytoplankton species in the NR group and the RW group were mainly related to TN, NH₄⁺-N, N/P, and ORP.