滆湖藻密度的时空分布及驱动因子分析

在2年内分季度调查滆湖浮游植物种群和水环境因子,分析藻密度的空间分布状况以及按时间序列的藻密度变化和浮游植物优势种群变化,分别采用"多元线性逐步回归法"和"偏相关系数法"进行藻密度驱动因子识别。结果表明,滆湖藻密度空间分布趋势为由北向南逐渐升高,年际间季节差异极显著。浮游植物的演替规律为冬、春季节以绿藻和硅藻为主,夏、秋季节蓝藻占绝对优势。通过比较2种统计方法的计算结果,确定全湖及中、南部湖区藻密度的驱动因子是温度和高锰酸盐指数,北部湖区藻密度的驱动因子是温度和硝酸盐氮,所有驱动因子对滆湖藻密度的影响均为正效应。在富营养化严重的滆湖,N,P营养盐已经不再是浮游植物生长的主要驱动因子,从统计方法的角度解释了部分环境因子没有入选为驱动因子的原因,并推断了其他可能的驱动因子。

The spatial-temporal distribution of algae density and the succession law of phytoplankton are analyzed based on the quarterly monitoring data within 2 years in Lake Gehu.Stepwise multiple linear regression and partial correlation coefficient are employed to determine the driving forces of algae density.The results showed that the spatial distribution characteristic was that algal density increased gradually from north to south,and there’s significant inter-annual seasonal difference.The succession law of phytoplankton in Lake Gehu was that the dominant species in winter and spring was Chlorophyta and Bacillariophyta,while in summer and autumn Cyanophyta was the dominant species.Through comparing the calculated results of two different statistical methods,T and CODMn were identified as driving forces of middle area,south area and the whole area of Lake Gehu.T and NO3-N were identified as driving forces of north area.All these driving forces had positive effects on the algae density of Lake Gehu.Nitrogen and phosphorus nutrients were no more the main driving forces of phytoplankton in Lake Gehu,which is in a state of high eutrophication.The reasons that some environment factors are not selected as driving forces are explained in the point of statistical method and some possible driving forces are also listed.