兰州市银滩湿地硅藻群落演变及PCA相关分析

Diatom community evolution and PCA analysis for Lanzhou Yintan Wetland

分析了兰州市银滩湿地2011年3—10月沉积物中硅藻群落结构以及演变特征.每月中旬在湿地样点采集8个沉积物样,同时测定样点水体温度、电导率和pH值.共鉴定出27属,126种及变种硅藻,Navicula和Nitzschia两个属出现的频率最高.各个月份的硅藻优势种、个体形态、种群数量及结构有较大的差异.其中,3月份以Navicula pupula为优势种,4月份以Navicula simplex为优势种,5,8,10三个月Navicula veneta在表层沉积物中含量最高,6月份Cymbella pusilla丰度最高,7,9两个月的优势种为Navicula viridula var.rostellata.而从7月以后湿地硅藻属种的面貌发生了较大的变化,Nitzschia palea,Cymbella affinis,Cymbellaventricosa,Navicula veneta,Navicula viridula var.rostellata等成为了主要硅藻属种.受黄河7月以后水位上升的影响,外源污水可能大量进入湿地水体,湿地大部分处于弱有机污染状态.通过对硅藻属种及pH、电导率、总有机质质量分数和温度环境变量之间的去趋势对应分析和主成分分析表明:pH是影响硅藻属种分布最主要的环境变量,能解释较多的硅藻属种分布特征;次要的环境变量是电导率、有机质质量分数受水体的影响,表明湿地水体有机污染物有外源输入的特征.

Diatom community and structure were analysized in the sediments collected from March to October in the Lanzhou Yintan Wetland. Every mid-month, eight samples in 50 g surface sediments were collected at the same site. Simultaneity, water temperature, conductivity and pH were determined at the sample site. 27 genera, 126 species and varieties of diatom were identified in the Environmental Lab in the College of Earth and Environmental Sciences, Lanzhou University and it was found that Navicula and Nitzschia were the highest concentration among them. Navicula pupula was the dominant species in March, Navicula simplex in April, Navicula veneta in May, August and October, Navicula viridula var. rostellata in July and September. Navi- cymbuIa pusiUa was the dominant species in June. The diatom community characteristics changed greatly after July. Nitzsehia palea, Cymbella aJfinis, Cymbella ventricosa, Navieula veneta, Navicula viridula var. rosteUata became the predominant diatom species. Seen from the diatom community, external organic pollution influenced the water in the Lanzhou Yintan Wetland with rise of the water level of the Yellow River starting from July. The relationship between diatom species and environmental variances such as pH, SC, w（TOC） and temperature was analysised using DCA and PCA methods. The result showed that pH was the primary environmentM variance influencing diatom species and next was the conductivity （SC）. And the TOC contained in the samples showed that the water was influenced by external orangic pollutions.