Correlation analysis between eutrophication and environmental factors in Lake of Wuliangsuhai, Inner Mongolia.

Spatial and temporal distribution characteristics of chlorophyll-α were analyzed based on monthly monitoring data in Lake of Wuliangsuhai,Inner Mongolia from June to October in 2008,with chlorophyll-α as reference factor which can best reflect the state of eutrophication.Twenty sampling sites of the Lake were classified into four types by clustering method.The modified Carlson trophic state index for the four types of sampling sites was calculated to assess water condition of the Lake.Multiple regression equation was worked out according to analytical results between chlorophyll-α and environmental factors.Results showed that concentration of chlorophyll-α ranged from 1.54mg/m3 to 26.87mg/m3 and with a mean value of 6.314mg/m3,with peak of chlorophyll-α concentration occurred in August and September,medium in July and September and the lowest in June.Distribution trend of whole water area took on decreased from the northeast to the southwest.Based on modified Carlson trophic state index,whole lake was in eutrophic state.Statistical analysis results showed that chlorophyll-a,pH and dissolved oxygen had negative correlations with transparency although the affecting factors for chlorophyll-α varied specially.Significant environmental factors affecting chlorophyll-α were turbidity,suspended substance,total phosphate,total nitrogen,nitrate nitrogen and nitrite nitrogen.