Analysis of Spatial-Temporal Variations of Chlorophyll a Concentration and Related Environmental Factors in Chaohu Lake

摘要

Multivariate statistical techniques,such as cluster analysis (CA),correlation analysis and stepwise regression analysis were applied to the data set on water quality of the Chaohu Lake,China,generated during eight years (2000-2007) monitoring at 12 routine national water quality sampling sites.The spatial-temporal variations of chlorophyll a concentration were first explored by using ArcGIS-based kriging method.Throughout the whole lake,the concentration distribution showed a pattern of decreasing from the northwest to the southeast.CA was used to category the 12 sampling sites,by means of the Ward's method.Three significant groups,Group Ⅰ (including Site-2),Group Ⅱ (including Sites-1 and 3) and Group Ⅲ (including Sites-4 to 12) were obtained on the basis of similarity between them.The relationships between chlorophyll a and related environmental factors were analyzed and the Pearson correlation coefficients were obtained through correlation analysis.Stepwise multiple regression analysis was adopted to examine the controlling role of any particular parameter or group of parameters on phytoplankton biomass,using chlorophyll a concentration as the dependent variable,while related physicochemical parameters as the independent variables,the best-fit linear multiple-regression equations for chlorophyll a concentration prediction were established,and the dominating factors for chlorophyll a were simultaneously identified.These results will help researchers and decision-makers to better understand the influence of environmental factors on phytoplankton and to manage eutrophication adaptively in Chaohu Lake.