温榆河水环境质量与浮游植物群落结构的时空变化及其相互关系

温榆河是北京市重要的生态廊道.本研究基于历史文献资料和现场调查,比较分析了2006、2011和2018年温榆河水环境质量与浮游植物群落结构的时空变化,探讨了浮游植物群落变化与水温T、溶解氧DO、pH和营养盐之间的相互关系.结果表明,温榆河水环境质量总体好转,经历了重度污染→污染遏制→水质改善过程,水污染物已从NH_4~+-N为主转向TN为主.NH_4~+-N、TN的平均浓度和平均超标倍数从2011年的15. 52～19. 16 mg·L~(-1)、9. 34～8. 58倍和20. 21～19. 58 mg·L~(-1)、12. 47～8. 79倍降低到2018年的1. 93～2. 66 mg·L~(-1)、0. 29～0. 33倍和5. 66～6. 79 mg·L~(-1)、2. 77～2. 39倍,并且温榆河和支流清河的DO和NH_4~+-N浓度已基本达到水功能区划目标.与水质改善过程相对应,浮游植物群落的物种种类大幅增加,经历了绿藻门(Chlorophyta)→蓝藻门(Cyanophyta)→硅藻门(Bacillariophyta)物种为主的变化过程,Shannon-Wiener多样性指数(H')、均匀度Pielou指数(J)有所改善,但依然存在高耐污绝对优势物种小环藻(Cyclotella)和直链藻(Melosira)等,且2018年温榆河依旧处于中富营养化状态.统计分析结果表明,DO、pH、NH_4~+-N、TN和TP是影响温榆河流域浮游植物多样性和蓝藻、硅藻及其他藻类密度的主要因素.

Spatio-temporal Evolution and Relationship of Water Environment Quality and Phytoplankton Community in Wenyu River

The Wenyu River is an important ecological corridor of Beijing. In this study, the spatio-temporal dynamics of water quality and phytoplankton community in the Wenyu River in 2006, 2011, and 2018, as well as their relationship were thoroughly analyzed by historical data analysis and field surveys. Results show that the water quality in the Wenyu River improved significantly from serious pollution owing to pollution containment. The major water pollutant has shifted from ammonia nitrogen (NH₄⁺-N) to total nitrogen (TN). Compared with 2011, the average multiple of NH₄⁺-N and total nitrogen TN exceeding the national standard were reduced by factors of 0.29-0.33 and 2.77-2.39, respectively, in 2018. The average concentration of NH₄⁺-N and TN decreased from 15.52-19.16 mg·L^-1 and 20.21-19.58 mg·L^-1 in 2011 to 1.93-2.66 mg·L^-1 and 5.66-6.79 mg·L^-1 in 2018. Moreover, dissolved oxygen (DO) and NH₄⁺-N concentrations in the Wenyu River and its tributaries, the Qinghe River, almost met requirements of their water function zoning target. Corresponding with the water quality improvement, the phytoplankton and community species increased dramatically. Phytoplankton species increased from 6 to 8 phyla, as well as community species. The dominant species changed from Chlorophyta in 2006 to the Cyanophyta in 2011, then to Bacillariophyta in 2018. The Shannon-Wiener diversity index (H'') and evenness Pielou index (J) had improved. However, the major dominant species such as Cyclotella and Melosira persisted, and the Wenyu River was still in the eutrophication state in 2018. Statistical analysis results indicated that Cyanophyta, Bacillariophyta, and other algae abundance were significantly correlated with DO, pH, NH₄⁺-N, TN, and TP.