Research On The Relevant Factors Of The Algal Growth In Hydrodynamic Condition

Phytoplankton is one of the component in aquatic ecosystem,and it is also primary producter.The phytoplankton's constructure and quantity largely affect the evolution and the develop of the aquatic ecosystem.In the period of the reservoir being formd,the species and the quantity of phytoplankton almost are changed,even grow crazly.All these will lead to the eutrophycation.So,as to prevention of reservoir's eutrophycation and ecosystem administer , it is an important to holding the characteristic of the phytoplankton.The Three Gorges Reservoir started water storage in June 2003,and water level of the dam fluctuated around 135 meters.Since then ,the average velocity of entire flow place in dry seasons has declined remarkable,and the velocity of entire place in deep area before dam decreased about 10 times to the the velocity of entire place in nature flow.The influence of the change of hydrology factors such as water level and flow velocity on the phytoplankton in the Three Gorges Reservoir is given close attention.At first, though monitoring the values of flow velocity,water temperature, turbidity,dissolved oxygen,pH,dissolved total nitrogen,dissolved total phosphorus,and Chlorophyll-a,this paper shows that the rules of the relevant factors of alage growth influence on alage growth in condition of different flow velocity.Then,the order are arranged as the degree of the relevant factors influence on alage growth,and mathematical model between Chla and the relevant factors of alage growth are build.Finally,the paper comes to the following conclusions:①The change of Chla shows the same trend in different flow velocity,which ascend first,then descend.②The time needed about 11～15 days when the value of Chla get to the maximum.In the test,when the original nutrients are aboundant,and the nutrients are not added,the whole life cycle is around 20～28 days.③When the dynamic temperature is higher than the static temperature between 1 and 3℃,the value of Chla increases with the flow velocity increases under the condition of the flow velocity below or amount to 0.08m/s,and the value of Chla increases with the flow velocity decreases under the condition of the flow velocity above 0.14m/s.The results illustrates that there is a critical flow velocity between 0.08m/s and 0.14m/s.When the flow velocity is below the critical value,the value of...