Stepwise multiple regression analysis on environmental factors of algae in a surface water resource of Zhengzhou city

  Objective   To analyze the relations between algae and related environmental factors and make the model prediction.

  Methods   Eight indices were determined in two sampling sites by standardized methods from Mar 2004 to Oct 2004 in the water resource.The influence of some environmental factors on chlorophyll-a(Chla)and algae cell density(ACD)was analyzed via cor related analysis and stepw ise multiple regr ession.In addition, the contents of Chla and ACD were predicted by building stepwise multiple regression equations respectively.

  Results   The results of correlated analysis showed that significant positive correlations were found between the standar dized Chla and w ater temperature(WT), chemical oxygen demand(CODMn)to tal phosphorus(TP)and between the standardized ACD and WT, TP; significant neg ative correlations were foud between the standardized Chla and secchi-depth(SD)and betw een the standardized ACD and SD, water depth(WD).Furthermore, the results of stepw ise multiple regression showed that WT, CODM nand TP were the most significant relat ed factors to the standardized Chla; WT and TP were the most significant related factors to the standardized ACD.The contents of Chla and ACD could be predicted by the equations perfectly.

  Conclusion   The contents of Chla and ACD are predicted by the multiple regression equations perfectly.It is very significant to decrease the contents of TP and CODMn in controlling the contents of Chla and ACD effectively.