Systematic investigation into winter and spring algal blooms in Daning river of Three Gorges Reservoir

According to the survey conducted from winter and spring algal blooms, the changes of water quality and characteristics of Daning River of Three Gorges Reservoir (TGR) were studied. The results suggested that during the period of winter algal blooms centered on Tangjia bay in Daning river, chlorophyll a (Chl-a) had a wide range (the rates of (Chl-a)_max and (Chl-a)_min is 260). The contents of total nitrogen (TN), total phosphorus (TP) and potassium permanganate index were at very high levels because of bioaccumulation from algal blooms, but the values of dissolved oxygen (DO) and pH were very low. During winter algal blooms fastigium poor algae were observed accounting for 2 phylum 4 species, dominant species are Microcystis aeruginosa and Microcystis flos-aquae, the maximum value of algal density was 3.15×10⁷ cells/L, and the correlation weighted nutrition state index was 80, which indicated water body was at high eutrophication level. However the spring algal blooms belonged to whole watershed outbreak, the values of Chl-a, TN, TP and potassium permanganate index became all markedly high with outbreak of algal blooms. There were 5 phylum 44 species algae being observed during spring algal blooms fastigium, different sections observed different dominant species and algal density values. The correlation weighted nutrition state index showed water of Dongping bar and Baishui River sections was at slight eutrophication level. During winter algal blooms there were significantly positive correlations between Chl-a and TN, TP, potassium permanganate index, water temperature, between pH and SD. Significantly negative correlations were observed between Chl-a and DO, SD, between pH and TN, TP, potassium permanganate index. In spring algal blooms significantly positive correlations were observed between Chl-a and TP, potassium permanganate index, DO, pH, between pH and Chla, TP, potassium permanganate index, DO, air temperature. Significantly negative correlations were observed between Chl-a and SD, between pH and SD.