Study On Euthophication Algal Characters And Environmental Factors Effect Of Three Gorge Reservoir

The Three Gorge Reservoir is a river-type reservoir, which hydrodynamic conditions have characteristics of space distribution. Its water-body has the variation that is transiting from torrential flow to static water. There are some researches only from the aspect of static water (lakes) or from dynamic water (rivers) till now. In this paper, we selected the Changjiang and Jialing Rivers of its confluence and Shuanglong Lake in Chongqing for objectives. We researched the changes of algae's and dominant species's composition, quantity and seasonal distribution in different current speed water. We analyzed the forming algal characters by the effect of environment factors.We fond the growth chang law in different current speed water and the algal characters and its space distribution when arose eutrophication in Three Groge Reservoir. It can afford the foundation and research basis for eutrophication in Three Groge Reservoir.In Changjiang and Jialing Rivers and Shuanglong Lake, we respectively set 4, 5 and 6 sampling stations, and researched from August in 2004 to July in 2006. The water tempreture, pH, TN, TP were measured and the plankton species and theirs quantity were identified and counted with microscopy. The data of algal composition, density and dominant species were arranged in three waterbodies. Then algal composition, density, dominant species and theirs annual changes were analyzed about different current speed water.The main conclusions were summarized as follows:Diatom is the first dominant specie in Changjiang and Jialing Rivers. The proportion of diatom is higher in Changjiang River, and the proportions of chlorophyta and cyanothece are higher in Jialing River. In Shuanglong Lake, cyanothece and chlorophyta are dominant species, and the proportion of diatom is lower. In Changjiang River, the change of total algal density is highest in spring and lowest in autumn, and algal community structure is diatom-cyanothece. In Jialing River, the change of total algal density is going up in spring, and it up to the highest in summer, and dropped in autumn, and it down to the lowest in winter. The algal community structure is diatom-chlorophyta-cyanothece. In Shuanglong Lake, the total algal amount is less in summer and winter, and it more in spring and autumn. The current speed has more effects on algal character in Changjiang and Jialing Rivers. Along with current speed decreasing, the total algae species and densities increase. The proportion of diatom is reduced and proportions of cyanothece and chlorophyta is increased. At the same time, the change of current speed can arouse the changes of sediment and nutrition in waterbodies, so it affects the growth of algae. By the correlation analysis about algal density and nutrition, the effect of current speed is more and the effect of nutrition is less in Changjiang and Jialing River in which diatom is the chief. Afer researching the algal characters in Changjiang and Jialing River, and compared ones in Shuanglong Lake, the space distribution of eutrophic algal character is sum up in the Three Gorge Reservoir. That is some waterbody types which are transition-waterbody and lake-waterbody arise eutrophication most possible in spring and summer. The transition-waterbody's current speed is 0.05m/s～0.2m/s, and the lake-waterbody's current speed is less than 0.05m/s.