Spatial and temporal distribution patterns of chlorophyll-a and the correlation analysis with environmental factors in Lake Qiandao

为了解千岛湖在大量放养鲢鳙鱼后叶绿素a的时空分布格局及其与主要环境因子的相关性, 本文于2007年1月至2009年12月对千岛湖叶绿素a及其他10个水质理化指标进行了每月定期采样及监测.结果表明:上游河流区和过渡区叶绿素a含量存在明显的季节变化, 其共同特点是每年会形成春季和夏末秋初的双高峰.叶绿素a含量在空间分布上具有一定的分异性, 河流区叶绿素a含量明显高于中下游区(过渡区和湖泊区).叶绿素a含量的最高峰通常出现在4-12m, 最深出现在20m, 春夏季出现明显分层.千岛湖叶绿素a与亚硝酸盐氮(NO2-N)、高锰酸盐指数(CODMn)、水温(WT)和硅酸盐(SiO32-)呈低度相关, 与其他环境因子无显著相关性或相关性很弱.多元逐步回归分析结果显示, 千岛湖叶绿素a与筛选出的几个关键环境因子之间的回归方程为:Chl.a=0.114WT+2.120CODMn+17.157SiO32--37.391NO2-N-1.946。;The temporal and spatial distribution patterns of chlorophyll-a and its correlation with the main environmental factors were analyzed according to the monthly investigation from January, 2007 to December, 2009 in Lake Qiandao where a large number of silver carp and bighead carp stocked.Results showed that the concentration of chlorophyll-a in sampling stations located in the upper reach riverine and transitional zones of the reservoir showed a significant seasonal variations with two concentration peaks oc-curred in spring and late summer or early fall,respectively.The concentrations of chlorophyll-a in upstream sites(in the riverine and transitional zones) were significantly higher than those of downstream sites.The chlorophyll-a during the warm season was usu-ally stratified with a concentration peak occurring at depths between 4m and 12m, occasionally at a depth of 20m.The result of cor-relation analysis showed a weak correlation between chlorophyll-a and NO2-N,CODMn ,water temperature( WT) and silicate (SiO32- ),while no significant correlations of the chlorophyll-a were found with other environmental factors,especially with the TP in the water.The regression equation between chlorophyll-a and the correlated environmental factors could be expressed through the multiple linear stepwise regressions as:Chl.a=0.114WT +2.120CODMn +17.157SiO32--37.391 NO2-N -1.946.