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

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 categoried 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 BOD5,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.