The Study Of Treatment About Alga In Cheng Feng Lake Da Qing Oil Field

Eutrophication of lakes became a main environmental problem in China, not only they restricted utilization of lake resource,but also they impacted directly human health and survival and sustainable development of social economy. The practice of controlling lake eutrophication has come along and difficult way from controlling nutrient, direct killing algae to biomanipulation and ecological restoration. Although many countries have put a huge amount of money into it, little effect has been produced yet. At present, no perfect theories or nature methods for treatment of the eutrophication of lakes have been summarized in the country and lots of respects in control of internal-sourcedpollution and in the principle of bioremediation are yet to be further studied. Text is based on the instance of fathered the burst out of alga in Cheng Feng lake at Da Qing oil field. We lucubrate the reasons of bursting out of alga, accordingly brings forward effective methods.Cheng Feng lake of Da Qing oil field locate at Rang Hu road section, the area is about 200 hectare, the depth of the lake is about 2.5m on average. In the middle ten days of June,2007,millions of red fleas erupt in Cheng Feng lake, after that float grass deluges in the lake, on top of that, in the middle ten days of July,2007,micro bursa flea began to burst cosmically. It affects the sight and the safety of fish very badly. And the smell liberates from the flea has affected the existence of denizen around lake. Northwestern Polytechnical University assayed the lake ,the result indicates that the concentration of flea in Cheng Feng lake has reached ten thousand million per liter, it means that the lake attributes eutrophication.The flea is the same as all the other biology, it needs C,N,P,K,Ca,Mg,S etc nutrition element, as well as Fe,B,Mn,Zn,Co,Cu,Mo,Si etc microelement, with all these element it is able to maintain the natural development, carry through the photosynthesis. Photosynthesis offers enough oxygen for the other hydrophily biology, achieves the aim of energy metabolize and the circle of materials. In all the nutrition element, N and P are both the most important ones. If there is a lack of N and P, the growth and propagate of flea will be restricted; but if they are abundant, it is going to arose an excessive propagate of flea, present itself as the phenomenon of"eutrophication", and blooms happens.The excessive of nutrition element can induce eutrophication, beside this reason, we also can explain why the flea will burst out from the point of view of ecology.In the ecosystem of a lake which is not influenced by human beings, the producer, consumer and disintegrator do their own jobs, carrying through the substance circle whose scope is counterpoise with the condition of environment.The activity of humans'discharging of contamination offers excessive food and nutrition to the consumer directly, get across the producer. This brings a speedup of propagate in all kinds of species belong to the lake ecology community, but the condition of the environment that sustain substance circle doesn't change with the increase of substance gross, reflecting on a lose of the backup of lake ecosystem. At first, the dissolve oxygen provided by circumstance is numbered, it can't content the need of the consumer, so the lake becomes anoxic rather than aerobic, the color of the lake turns black and the smell turns odour. After that, the sinking plants die because they can't get enough illumination in a lake whose diaphaneity is degressive. Producer give priority to flea, because of the degressive of oxygen, the consumer not only can't follow the growth scope of producer and disintegrator, but also even die. So the food chain of ecosystem is cut hereon, the flow of energy and the circle of substance are blocked, the ecosystem loses it's balance. Flea and the other primary producer lose the control of consumer, they propagate wantonly and blooms happened. Via the melody on the spot, the reasons that induce the going beyond of standard of nutrition substance contains the following items:(1).Before the alteration of Cheng Feng lake, a mass of sewage and waste water were discharged in the lake, there are lots of N and P accumulated in the bottom mud. Although we cleared the mud on the bottom of the lake, we can't able to clear up all the N,P who had filtered in the soil of the bottom of the lake. After the alteration, N and P etc. will release to the lake form the soil.(2).The drain system of Da Qing city doesn't come true the distributary of rain and sewage.(3)There is the circs that the denizen and the industry around the lake discharge sewage and waste water secretly.(4)The air temperature of the year is on the high side, and the depth of Cheng Feng lake is relatively fleet, the capacity of flow and circle of the lake is debased.At present, the technical method of fathering the eutrophication lake mainly fastened on the following 4 items: 1.control the nutrition substance; 2.clear the flea directly; 3.biology melody and control; 4.ecology project and ecology restore. These 4 methods all have their own advantage, we can't apply only one, and should chose different instrumentality based on the different aim at different period.Considering the actuality of Cheng Feng lake, we cut the project of fathering the flea of Cheng Feng lake into two parts, one is the urgency blue print, the other is extended blue print, these two blue print carry through in turn. At first put in medicine to perish the flea, making the majority of the flea in the lake die quickly, accomplish the job of urgency fathering; and then adopt the mode of throwing fry, planting water lily, refloatation floate grass, air sparging to resume the oxygen, exchange water etc to accomplish the job of extended blue print.After the actualization of urgency blue print, the concentration of flea fell at a great extend; the extended blue print actualized form July, 2007 to August 2008, after survey the concentration of TN has fell gradually, the concentration of TP fell also, so it indicates that the fathering blue print is scientific, reasonable and effective.