Spatial-temporal Characteristics of Chlorophyll-a Concentration and Its Relationship with Environmental Factors in the Inlets of South Taihu Lake

According to the monitoring data in the inlets of South Taihu Lake from January to December 2010,the spatial-temporal characteristics of chlorophyll-a concentration and the correlation analysis between the chlorophyll-a concentration and main environmental factors including water temperature and nutrients were investigated.The results indicated that there was an obvious temporal and spatial variation of chlorophyll-a concentration.The highest average concentration of chlorophyll-a was monitored at summer,the lowest was monitored at spring;the average chlorophyll-a concentration at southwest of Taihu Lake was higher than that at south of Taihu Lake.The annual average of chlorophyll-a concentration was(15.71±11.24)μg/L,ranged from 1.50μg/L to 74.3μg/L.Significantly positive correlations were found between chlorophyll-a concentration and water temperature,pH,permanganate index(CODMn),total phosphorus(TP),and ammonia-nitrogen(NH+4-N).Significantly negative correlations were found between chlorophyll-a concentration and dissolved oxygen(DO),total nitrogen(TN),and TN/TP.The chlorophyll-a concentration was influenced by multi environmental factors,and the water temperature was the key factor.The average value of TN/TP was 17.8,which was in the best range for the growth of algae and made the cyanobacterial bloom happen easily.Significantly positive logarithmic correlation was found between chlorophyll-a concentration and TP.Significantly negative logarithmic correlations were found between chlorophyll-a concentration and TN,TN/TP.Phosphorus was the main limited factor for the growth of phytoplankton in inlets of South Taihu Lake.