污染治理前后小清河上游浮游植物群落变化与水质评价

为研究小清河污染治理前后浮游植物群落与水质变化,分别于2015年(治理前)和2020年(治理后)在小清河上游进行采样调查。调查结果显示,2015年样品中共检出浮游植物6门35种,2020年样品中共检出4门31种。配对样本t检验结果显示,污染治理前后的浮游植物种类、密度都发生了显著改变。相比治理前,治理后的硅藻门和绿藻门相对丰度分别上升了51.6个百分点和13.3个百分点,蓝藻门下降了62.9个百分点,小环藻(Cyclotella spp.)取代微囊藻(Microcysitis spp.)成为绝对优势种,群落类型由蓝藻型演替为硅藻型。相似性分析结果和相似度百分比分析结果表明,小清河上游群落特征发生显著改变。非度量多维标度分析结果显示,治理后的S2与S3采样点群落特征表现出差异,S4与S1采样点群落特征相似。通过冗余分析发现,治理后,TP、DO对浮游植物群落的影响明显减弱,TN、NH₃-N、pH是目前影响群落特征的主要指标,主城区氮磷污染对浮游植物的影响范围由S2、S3、S4采样点缩小到S2采样点。治理前后的小清河上游Shannon-Wiener多样性指数、Pielou均匀度指数和Marglef丰富度指数存在显著差异。总体来看,治理后的小清河上游水质处于α-中污染状态,较治理前有明显改善。

Variation of Phytoplankton Community and Water Quality Assessment Before and After Pollution Control in the Upper Reaches of Xiaoqing River

In order to study the variation of phytoplankton community and water quality before and after pollution control in the upper reaches of Xiaoqing River,samples were collected in 2015 (before pollution control) and 2020 (after pollution control) respectively.The phytoplankton species decreased from 35 species of 6 phyla in 2015 to 31 species of 4 phyla in 2020.The paired sample T-test showed that the species and density were significantly changed,with the relative abundance of diatom and green algae increasing by 51.6 percentage points and 13.3 percentage points respectively,while that of cyanobacteria decreasing by 62.9 percentage points.Cyclotella spp.replaced Microcysitis spp.as the dominant species,and the community changed from cyanobacteria to diatoms.Similarity analysis (ANOSIM) and similarity percentage analysis (SIMPER) showed that the community characteristics changed significantly.The results of non-metric multidimensional scaling analysis (NMDS) showed that the community characteristics of S2 and S3 were different after treatment,and the community characteristics of S4 and S1 tended to be similar.Redundancy analysis (RDA) showed that the effects of TP and DO on phytoplankton community were significantly weakened after pollution treatment,while TN,NH₃-N and pH were the main physicochemical indexes affecting the community structure.The influence of N and P pollution on phytoplankton was reduced from S2-S4 reach to S2 reach.There were significant differences in Shannon-Wiener diversity index (H''),Pielou evenness index (J) and Marglef richness index (d) before and after treatment.After treatment,the upper reaches of Xiaoqing River were still in a state of alpha-pollution,but the river water quality had been significantly improved.