内蒙古乌梁素海富营养化与环境因子的相关分析

文章利用2008年6～10月对乌梁素海水体的测定结果,以最能表现水体富营养化状态进程的叶绿素a为基准因子,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,然后应用修正的卡尔森营养状态指数对四类测点的水质进行评价,找出各类测点及总测点中与叶绿素a显著相关的环境因子,最后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6.314mg/m3,变幅1.54～26.87mg/m3;在8、9月出现高峰,7、10月居中,6月最低,整个区域呈现较明显的东北高西南低的分布趋势。依据修正的卡尔森营养状态指数公式,计算得出乌梁素海TSIM平均值为65.1(53),全湖处于富营养化状态。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、总磷都呈极显著正相关,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的环境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。

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.