Han River "bloom" Impact Factor Analysis And Research

Han-jiang River is an important water resource of city life,industry and agriculture production. Since 90's, with the development of industry and agriculture's construction, letting amount of industry's waste water , fertilizer water of agriculture and life's waste water is increasing by degrees, these waste water inpour Han-jiang River directly without treating, which induce deterioration badly of water quality of integrant reaches of Han-jiang River especially lower reache. The worse water bloom of Han-jiang River which resulted in eutrophication of water had happened for four years since 90's. So, the paper studies water bloom and algaeas in Han-jiang River as follows.(1) Based on datas of years of happening water bloom and without happening about water quality, hydrology, temperature, the paper analyzes and studies water bloom in Han-jiang River, according to water bloom of 1992y, 1998y, 2000y, 2003y.The factors on appearance of water bloom in Han-jiang River's lower reaches is that abundant nutriment of nitrogen and phosphor provide basic growth and multiplication condition for algae, the datas of past year made clear that phosphor becomes limiting factor because the ratio of nitrogen and phosphor in Han-jiang River's lower reaches is bigger than seven; Little flux(less than 500 stere per second), slow velocity of flow(less than 0.8 meter per second), low water level(less than 25 meters), which make water body presenting lake's characteristic approximately and provide essential environment room for happening of water bloom; In addition, fitting sunlight and water temperature(more than 10 centigrades) creat good environment condition for algae's reproduction.(2) The paper analyzes Cyclotella belonging to diatom algae phylum and Microcystis aeruginosa belonging to blue-green algae phylum using experiment. The principle of effective accumulate temperature is applied for counting the threshold temperature of Cyclotella, when temperature reach 8.5 centigrades, Cyclotella will propagate and growth.If only temperature is taken into account, diatom algae bloom happen by any possibility when temperature's cumulation reaches 476.4 ℃·d at least; Microcystis aeruginosa are cultivated continously using Chemosta at appropriate temperature, the result indicts that when temperature is 25 centigrades (less or more 1 centigrades than 25), the speed of mixing round culture liquid is low(50rpm) or stock-still, dilution ratio of culture liquid is 0.00736 per hour, the relative growth rates of Microcystis aeruginosa is more faster, on the condition of phosphor being limitative element. So, when phosphor charge is more and more aggravated, hydrology condition can't improve, high frequency of warm spring is more and more, the possibility of breaking out of blue-green algae bloom in Han-jiang river will increase.