滴水湖引水河段组合型生态工程春季对水体净化效果研究

Research of the ecological restoration results of the combined ecological project in Yinshui River,Dripping Lake in spring

为探究滴水湖引水河段生态浮床和滨岸带组合型生态工程建成初期对入湖水质的改善效果,于2010年春季设点对引水河进行营养盐浓度、透明度、叶绿素等理化指标和浮游植物种类数量的测定,并用综合营养状态指数法评价水体富营养化状况。结果表明:(1)工程河段水体TN、TP、Chl.a、NH3-N水平较上游明显降低,浮床和滨岸带组合工程对TN去除率为47.9%,TP为46.8%;(2)浮游植物密度变化与温度呈极显著正相关、与TN/TP呈极显著负相关,其密度单因子评价显示各点均达富营养化水平;(3)样点水体的综合评分范围为54.58～72.75,综合评分均值为64.07,处于中度富营养水平,其中样点1为重度富营养化;(4)Shannon-Wiener多样性指数显示滨岸带工程下游样点受污程度降低,与Pielou均匀度指数比较表明,调查水体绝大部分为中污和重污染,2类指数评价相似度为52.4%。考虑滴水湖周边潜在污染源较多、换水周期长,浮游植物群落结构尚不稳定等特征,对湖区及其周边水系的长期监测和评估可以为人工湖相关研究提供重要参考。

In order to evaluate the improvement of water quality by the construction of the eco-floating bed and the bank restoration project in the Yinshui River of the Dripping Lake,indicators like nutrient,transparency,chlorophyll,as well as phytoplankton density and distribution have been investigated in this study,which was carried out druing the Spring 2010.In addition,the biological diversity index of phytoplankton was calculated and TLI method was used to estimate the sites eutrophication level.Results：（1） the physical and chemical indicators variation trend demonstrated that the project had improved the water quality to some extent,with the TN removal rate 47.9% and TP removal rate 46.8%;（2） the variation of phytoplankton density showed a significant positive correlation with temperature and a significant negative correlation with TN/TP,and eutrophication was found in all sites through density evaluation.（3） the sites TLI ranged from 54.58 to 72.75,with the average of 64.07,which indicated a meso-eutrophication level with severe eutrophication in Site 1.（4） the comparison of Shannon-Wiener Index（H＇） and Pielou Evenness Index（J） showed that most of the samplings were in the states of moderate and severe pollution,with the similarity of 52.4%.Besides,Shannon-Wiener Index（H＇） demonstrated the pollution degree of the site in the rear of riparian buffer reduced.Finally,the number of potential pollution sources around the Dripping Lake is large while the water changing period is long and the community of phytoplankton is different from other freshwater lakes because of its special beach sediment.Considering the newly-built water ecological system of the Dripping Lake and its water sourcing rivers is not stable yet,long-time monitoring and assessment are of significant value especially for man-made lakes.