大清河水系保定段城市河道浮游植物群落结构及水质评价

Assessment on Phytoplankton Community Structure and Water Quality of Baoding City Watercourse in Daqinghe Basin

分别于2012年5、7、9、11月对大清河水系保定段城市河道的7个样点进行4次采样,调查浮游植物的群落结构并对水质进行评价。结果表明,在保定段城市河道中共鉴定出浮游植物7门、140种(属);其中,绿藻门69种,蓝藻门15种,硅藻门3种,裸藻门4种,隐藻门21种,金藻门24种,甲藻门4种。浮游植物种类数量变化规律为:5月>7月>9月>11月,位于上游清水桥采样点的浮游植物多样性均大于其他采样点。各点浮游植物密度均超过1000个/mL,水体达到富营养化程度。利用理化指标进行水质评价,大清河水系在流入保定市区之前水体处于中营养状态,流出保定市区时水体处于重度富营养状态。浮游植物密度指数评价结果与理化指标评价结果基本一致,而Shannon-Wiener物种多样性指数和Pielou均匀度指数的评价结果与理化指标评价结果存在明显的差异。讨论了生物指数法对于城市河道水质评价的适用性。

In order to investigate the phytoplankton community structure and assess the water quality, the 7 sampling sites in Baoding city watercourse of Daqinghe basin was sampled 4 times in 2012 May, July, September and November, respectively. The results showed that 140 species of 7 phylum of phytoplankton were identified, including 69 species of Chlorophyceae, 15 species of Cyanophyta, 3 species of Bacillariophyta, 4 species of Euglenophyta, 21 species of Cryptophyta, 24 species of Chrysophyta and 4 species of Dinophyta. The regularity of number changing of phytoplankton species was May＆gt;July＆gt;September＆gt;November. The diversity of phytoplankton, which was located in the upstream of Qingshui Bridge, was greater than other sampling sites. The density of phytoplankton in all sampling sites was not less than 1 000 ind/mL, and the water body reached the level of eutrophication. By using the phytoplankton index to assess the water quality, the water body was in mesotropher before Daqinghe basin flowed into Baoding city, and it was in hypereutropher when Daqinghe basin flowed out of Baoding city. The assessment result of water quality due to density index of phytoplankton was in accordance with that due to physicochemical index, but the result due to Shannon-Wiener biodiversity index and Pielou evenness index was obviously different from that due to physicochemical index. The applicability of biotic index for assessing water quality of city watercourse was discussed.