草海丰水期chl-a空间分布与环境因子相关关系

水体富营养化是我国湖泊面临的主要问题,分析叶绿素a含量的变化特征及其影响因素,能为湖泊水质评价提供可靠基础。以2017年7月草海丰水期水质数据为参考,对各监测点叶绿素a与环境因子(TN,TP,NH_3-N,COD_(Mn),DO,WT)进行相关性分析并预测叶绿素a的变化趋势。结果表明:草海丰水期叶绿素a的均值为8.07μg/L,处于中营养化状态;叶绿素a与TN,TP,NH_3-N,COD_(Mn)呈显著正相关,而与其他环境因子相关性不显著,表明营养盐对浮游植物影响程度最大;将spearman秩相关系数及多元线性回归方程计算的叶绿素a预测值与实测值进行相关性拟合,得到较好的相关性(R~2=0.85,P0.01),表明该方法的预测结果能为预测草海叶绿素a变化趋势提供参考。草海上游及人类活动较大区域污染程度高,TP是草海藻类生长的限制因子,因此控制TP含量的输入是改善水质的关键。

Correlation between chlorophyll a and environmental factors during wet season of Caohai Lake in Guizhou Province

The eutrophication of water body is a major problem faced by lakes in China. Analyzing the variation characteristics of chlorophyll a content and its influencing factors can provide a reliable basis for lake water quality assessment. In this paper, we use the water quality data at monitoring sites of Caohai Lake in July 2017 as a reference to study the correlation between chlorophyll a and environmental factors (TN, TP, NH3-N, CODMn, DO, WT) and predict the variation trend of chlorophyll a. The results show that the average value of chlorophyll a is 8.07 μg/L in wet season of Caohai Lake, and it is in a medium eutrophication state. Chlorophyll a is significantly positively correlated with TN, TP, NH3-N, and CODMn, but is not significantly correlated with other environmental factors, indicating the greatest influence factor on phytoplankton is nutritive salt; TN / TP average ratio is 18.16 and the lake is in P restricting state; the fitting of predicted and measured chlorophyll a with multiple linear regression equation and spearman rank correlation coefficient obtains better correlation (R2=0.85,P<0.01), indicating that this method can provide a reference for predicting the chlorophyll a variation trend in Caohai Lake. The pollution in upstream area of Caohai Lake and intensive human activities area is heavy and TP is a limiting factor for the growth of grass algae. Therefore, controlling TP input is the key to improving water quality.