关键词: 叶绿素a, 环境因子, 相关分析, 草海

Abstract: 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.

Key words: Chlorophyll a, environmental factors, correlation analysis, Caohai Lake