三峡水库蓄水前后浮游植物调查及水环境初步分析

STUDY ON THE PHYTOPLANKTON IN THE THREE GORGES RESERVOIR BEFORE AND AFTER SLUICE AND THE PROTECTION OF WATER QUALITY

比较了三峡水库蓄水前后湖北库区干流江段及其主要支流的藻类生态特征及水质状况,结果显示,蓄水前(2002年12月至2003年6月)和蓄水后(2003年6月至2004年5月)三峡湖北库区江段藻类的群落结构和细胞密度存在明显差异。蓄水前共鉴定藻类7门66属79种,硅藻、绿藻、蓝藻分别占34.6%,38.5%和10.3%,其余藻类合计16.6%。蓄水后,藻类的总种类数增至151种,硅藻、绿藻、蓝藻所占比例依次为23.8%,55.0%和9.9%,其余藻类合计11.3%。藻类的细胞密度,蓄水前,干流平均272.6×104ind/L,支流1042×104ind/L;蓄水后,干流和支流的平均细胞密度分别高达384.8×104ind/L和2006.7×104ind/L,较蓄水前增加41.2%和92.6%,数据说明,三峡成库过程对湖北库区水生态系统中的藻类群落结构产生了影响,尤以对支流中的影响更为明显。作者通过分析蓄水后库区水质下降的原因及其负面影响,提出了相应的防治措施与建议。

The Three Gorges Reservoir,located at 29°16′—31°25′N and 106°50′—110°50′E,is the largest water conservancy for irrigation works and generate electricity in China. It has a total area of 54061.5km^2 and a water area of 189km^2, when the normal pool level is 175m. In order to understand the diversifications and effects of sluice on water environment and aquatic ecosystem,the authors made a preliminary study on the phytoplankton features,including species richness,dominant species,cells and diversity index,in the Hubei river section of the Three Gorges Reservoir during the period before sluice(2002. 12-2003. 06)and after sluice(2003. 06-2004. 05). The results showed that the species richness,composition and cell densities of algae were changed considerably throughout the studied period. Before sluice,in total of 79 species of algae were observed,belong to 7 phyla and 66 genera. Diatoms,green algae and blue-green algae occupied 34.6%,38.5%and 10.3% of the total,respectively. Other four phyla were only representing 16.6%. After sluice, the species richness of algae were increased to 151 species,belong to 8 phyla and 103 genera. The percentage of diatoms,green algae and blue-green algae was 23.8%,55.0%and 9.9%to the algae flora,respectively. The species richness of diatoms was decreased,but that of green algae was increased. The cell densities of algae were the following situation:Before sluice, the monthly mean values were reached to 272.6×10~4ind./L in the main channel,and to 1042×10~4ind./L in the bay region. After sluice, the values were raised to 384.8×10~4ind./L and 2006.7×10~4ind./L,respectively,increased by 41.2% and 92.6%than that before sluice. The concentrations of nitrogen and phosphorus were in the range of 2.39—2.54mg/L and 0.11—0.18mg/L in the main channel,and 1.42—1.84 mg/L and 0.18—0.30mg/L in the bay region,respectively. Those were much higher than the values in normal water bodies. The trophic status of the studied river section is at mesotrophy level in the main channel and at α-β-mesotrophy level in the bay region. The results illuminated that the process of valley changing into reservoir would be surely to affect the ecological characteristics of algae in aquatic ecosystem. Therein,the effects were more notably on bay region. Some prevention and cure measures and advices were also given in the paper,for protecting the water quality of the Three Gorges Reservoir.