乌梁素海叶绿素a与理化因子的统计分析

STATISTICAL ANALYSIS BETWEEN CHLOROPHYLL-A CONCENTRATION AND PHYSICAL-CHEMICAL FACTORS IN THE LAKE OF WULIANGSUHAI

利用2008年6月—10月乌梁素海水体叶绿素a浓度与环境理化因子的测定结果,分析了叶绿素a的时空分布特征.运用分层聚类分析法将乌梁素海现有的20个测点分成四类,找出各类测点及总测点中与叶绿素a显著相关的理化因子,建立了多元逐步回归方程.2008年乌梁素海各测点叶绿素a的平均值为6.31 mg.m-3,变幅1.54—26.87 mg.m-3;夏季最高,秋季居中,春季最低,整个区域呈现较明显的东北高西南低的分布趋势.应用SPSS统计分析软件进行相关分析的结果表明叶绿素a与BOD5、悬浮物、浊度、总磷都呈极显著相关,与透明度呈极显著负相关,与pH值和溶氧呈显著负相关.综合逐步回归方程表明,影响乌梁素海叶绿素a的理化因子因不同类型的测点各有所不同,但主要的影响因子有浊度、悬浮物、总磷、总氮、硝酸盐氮和亚硝酸盐氮.

The spatial and temporal distribution characteristics of chlorophyll-a were analyzed based on the monthly monitoring data in the lake of Wuliangsuhai from June to October of 2008. Twenty sampling sites of Lake Wuliangsuhai were categorical into four groups by clustering method. The multiple regression equation was worked out according to the analytical results between chlorophyll-a and the physical-chemical factors. The results showed that the concentration of chlorophyll-a ranged from 1.54 mg · m-3to 26.87 mg · m-3 and with a mean value of 6. 314 mg · m-3. Peak chlorophyll-a concentration occurred in the summer , the medium in the autumn and the lowest in the spring. The distribution trend in the whole water area showed a pattern of decreasing from the northeast to the southwest. The statistical analysis results showed that chlorophyll-a had significantly positive correlation with BODs, suspended substance, turbidity, total phosphate, significantly negative positive correlation with transparency, negative correlation with pH, and dissolved oxygen. Although the factors affecting chlorophyll-a varied with sampling sites, the major physical-chemical factors were turbidity, suspended substance, total phosphate, total nitrogen, nitrate nitrogen and nitrite nitrogen.