Study On The Ecological Amplitude Of Nutrition Restrictive Factors Of Jialing Rivers In The City Zone Of Chongqing

The Three Gorges Projects which will be completed by 2009,is a world-famous super-huge water control project. It will play a great role in flood control, generate electricity, shipping, irrigation and regulating climate and so on, and will mean great to influence of economic construction of our country as well. Since Jialing River in Chongqing lies in the interjunction of Jialing River and the end of the Three Gorges Reservoir Area,do research of its water quality ,examine and predict the eutrophication of it will have a great meaning not only to the research of The Three Gorges Projects but also to the economic development of chongqing as an important industrial city in the southwest area.The eutrophication of water is a complicated ecology course.In order to further understand relation between nutrition restrictive factors and alga in Jialing River in Chongqing,and search for the mechanism of how eutrophication takes place,the task uses the principle of ecological amplitude to research the nutrition restrictive factors in it deeply and systemically,then has got primary conclusions as follows:①phosphorus acts as the restrictive factor of the alga in the researching water area.It has a great relationship between the growing rate of the alga and the concentrate of phosphorus.②the ecological amplitude of phosphorus is unimodality for alga, and showed characteristic three base points, its tolerance range is the concentrate of phosphorus 0.005~100mg/L, and peak value of ecological amplitude is 0.150mg/L. Compartmentalize the ecological amplitude into three range: fast growing alga range whose concentrate of TP is(0.005mg/L～0.150mg/L); slow growing alga range whose concentrate of TP is (0.150mg/L～100mg/L);steady growing alga range whose concentrate of TP is more than 100mg/L.Besides,the high-increase growing alga range`s TN/TP is (1.9～21.5), and its concentrate of TP is(0.106mg/L～1.079mg/L). In the ecological amplitude, threshold of alga growing TP concentration is0.150mg/L,and threshold of TN/TP is 13.5.When the air temperature is during 10 degree centigrade and 30 degree centigrade,the peak value of alga phosphorus ecological amplitude will grow as temperature grows.③in the researching water area, when the concentrate of phosphorus grows more than 0.202mg/L,nitrogen will replace phosphorus steply acts as the restrictive factor; when TN/TP is less than 10,phosphorus will act as the restrictive factor;when TN/TP is more than 10,nitrogen will act as the restrictive factor.④integrating the three important factors of nutrition ,water temperature and the condition of hydrology, it can be concluded that the time which the eutrophication of water in Jialing River in chongqing is most likely to take place is the last ten-day of April, May, the first ten days of June and September. During these days, concentrate of TP in water is 0.089mg/L～0.112mg/L,which is in the fast growing alga range of ecological amplitude, what`s more,when it is June or September, concentrate of TP in water is right in the high-increase growing alga range.