| The dissertation mainly evaluates the environmental impact of a project named "Environmental impact assessment of water quality improvement projects in the central area of Beijing”.Based on the previous studies,the water quality improvement projects in the central area of Beijing has carried out comprehensive demonstration and engineering application of water bloom control.The project is located at the central water area of Beijing,mainly including Changhe River、Zhuanhe River、North Moat and Six Lakes,and the key areas are Changhe River、Xi Hai and Hou Hai.The purposes of the projects are as followed.To reduce the organic pollutants of Changhe River,people take control of the surface source pollution and set the in situ remediation project.To improve the water quality of Six Lakes and making BOD level close to the surface water class III requirements,people take control of the organic pollution of Xi Hai.To further improve the water quality,control the occurrence of water bloom in summer,and make the transparency reached50 cm people implement the ecological restoration project of Hou Hai.To maintain the water quality restoration results and make Bei Hai and Zhongnan Hai benefit from it,people implement the water quality maintenance project of Qian Hai.The paper is based on the projects which are implemented in the central part of Beijing.Main projects consist of several projects: the project in Chang’he River where water flows through gravel bed filtration,the projects of Beizhan River and Xi Hai where artificial grass biological contact oxidation treatment is carried out,the project of Xi Hai where surface source pollution is controlled,the project of Xi Hai where the artificial creation of a dynamic water flow and water circulation is undergone,the project of Hou Hai where water quality get improved by aquatic plants and the projects of Qian Hai where water quality and landscape get improved by aquatic plants floating bed.All of them are water treatment projects with the purposes of reducing pollution and improving water quality.The evaluation results show that the primary pollutant in the evaluation area is PM10 with the maximum daily average exceeded 1.8 times compared to the standard,and the hourly average of SO2 and NO2 and daily average are all up to the standard.The noise source of the project mainly comes from the aeration machine and the submersible pump.The aeration machine is located under the water and the noise source of the suction port of the aeration machine is strong at50~60 dB(A).In that case,the noise of the submersible pump is absorbed by water,so the impact to the surrounding environment is very little.The projects don’t have too much engineering constructions,so the degree of pollution is small during the construction period.The work is mainly the equipment installation and aquatic plants cultivation in water in projects,in addition to earthwork construction in a river.Underwater construction will have a certain impact on the plants,animals and microorganisms in water,but the impact is eliminated after the construction time,so the influence on the ecological environment is acceptable.The implementations of the projects have improved the water quality of Changhe River and Shichahai River,and they are beneficial to increase the number and kinds of animals,plants and microorganisms of the artificial water ecological system.The disadvantages of the projects are less than the advantages and the adverse effects on the ecological environment are acceptable.The author conducts the on-the-spot investigation and on-the-spot monitoring to understand fully about the natural environment,social environment and environmental quality of the project area,and analyzes the project schemes and pollution source.On the basis of which the author analyzes and predicts the degree and scope of the environmental impact on the local environment during andafter the construction and provides the prevention requirements and countermeasures to the environmental problems and ecological problems which may arise.And the author carries out the analysis of environmental economic profit and loss.Then the author puts forward the environmental management monitoring plan and makes a conclusion on the environmental feasibility of the project construction,which provides scientific basis of decision making for the environmental management. |
