| Population, resources and the environment has become a recognized three major problems in the world today. In the past 30-40 years, accompanied by rapid population growth, industrial development, environmental problems caused by excessive consumption of resources is becoming serious. Especially in recent years,the problems caused by smog are affecting everyone’s daily life as it appears more and more frequently. People began to pay close attention to the atmospheric pollution which has been an environmental pollution for a long time. The air pollution is no longer the problem of one area, one region, one country. The urban air pollution has become an important environmental issues drawn worldwide attention,and it has threaten the survival and development of human beings on some degree.Due to the complex terrain of valley, inversion weather happens frequently and the resistance of the surrounding mountains to the airstream is large, which causes the air pollution of the city in the valley more serious. Lanzhou city in Gansu province is a typical example. As a typical valley city and an industrial city, Lanzhou is one of the most serious air-polluted city in China. At present, there has been a lot research on the diffusion and forecast of the air pollution in Lanzhou, but no model applicability and usage conditions in Lanzhou area has been done.Lanzhou city’s wind speed is relatively small, the adverse weather conditions throughout the year, the frequency was 81% inversion, winter can be up to 96%, poor air flow and a large number of industrial emissions in the atmosphere of the primary and secondary pollutants Without easy to spread, resulting in poor air quality of the environment. Lanzhou as one of the key construction after the founding of the emerging industrial city in the process of rapid industrialization and urbanization development, due to its industrial layout and energy structure is not reasonable, high energy consumption, high pollution of the industrial structure,external ecological conditions are poor winter and spring dust weather are frequent, and coupled with local topography and is not conducive to the spread of pollutants generated by meteorological conditions, resulting in air pollution in Lanzhou particularly serious. Air pollution in Lanzhou has become the key factor of economic development, to a large extent hindered the economic development of Lanzhou.Gaolan County, Gansu Province in the central region, Gaolan County, Gansu cold climate is temperate Central Asia arid zone, continental climate significantly, four seasons,winter cold and long, hot summers and short term. The overall climate is characterized by:little precipitation, dry climate, weather and more sand, sunshine time is short, evaporation.This article uses the environmental quality monitoring reports of Gansu Tenda Metallurgical Company, Gaolanjinxin Ferroalloy Company and Gansu Hongfeng CarbideCompany in Gaolan County, Shi dong Town, Zhuangziping Village in the year 2007,2010-2012, the daily hourly weather data collected by Gaolan meteorological station from January to December in 2012, the Shuttle Radar Topography Measurement(SRTM)data by NASA and the site radiosonde data by NOAA/ESRL. Through Aermodsystem3.3atmospheric environment effects evaluation system and using industrial kiln furnace as pollution sources, the atmospheric diffusion simulation research of 2012 has been done of the selected district(Gaolan County, Shi dong Town, Zhuangziping Village). The analog prognosis was exercised on the base of plain terrain and terrain parameters via comparison.Datas of both typical day and different weather conditions of seasons were obtained.Through the study of its forecast ability of the analog model to valley terrain,the model susceptibility to the local terrain datas and the terrain influnce to the air pollution diffusion can be discussed.Use the model to carry out the daily mean value analog prognosis of each concerned piont and to compare the correlation between the analog results and the real—time monitoring results under the two cindotions(monitoring datas of July,2011,July,2012, December, 2012).According to the comparison analysis, conclusions can be summarized as follow:1.By the analog of extreme means of hour and daily in a whole year,the analog results appear in different seconds and points under the two conditions.It is the terrain datas which were affecting the results of the Aermodsystem model.Predicted results show that the concentration of the two cases were simulated maximum moment, appears in different levels;Concern points of similar simulation results, as concerns more flat for the rural areas, while the terrain factors have certain effects on the ground concentration, but its impact on the prediction results is small; Terrain data have influence Aermodsystem model simulation results.2.The analog results comparison of the four seasons shows that the means with terrain factors are lesser than those without terrain ones,and the extremes appears in different points.This phenomenon means terrain factors affect the air pollution density on the ground.The pollution diffusion contour map ranges wildly.The pollution contour curves display the pollution status better when terrain factors are considered.3.The comparison analysis results between the prognosis and the monitoring datas in summer and winter shows that the summer ones are better than the winter ones,which also consists with the monitoring datas.Under the terrain factors,the prognosis datas equal the monitoring ones well,they are more close.Generally speaking,Aermodsystem model can not only present the air conditions and terrain effects in monitoring areas,but also has specific effect on dealing terrain datas.Results shows that,in the Gaolan County meteorological and topographic conditions,Aermodsystem model for point sources, small areas of simulation results are effective and sensitive to terrain, so using this software in Lanzhou area using terrain data to obtain better results.Due to the limitations of this study, it failed to get better targeted monitoring data(such as feature pollutants). The forecasting in this paper is small and rural, which can be effected by many factors. The research of the AERMOD model is overall and the most of conclusions are qualitative analysis.It is recommended to expand the forecast area next, select an area in the city of Lanzhou and do synchronism-monitor. Characteristic factors are used to reduce the influence of other sources to the monitoring data in the environment. Each parameter in the model is analyzed separately. Through the comparison with monitored values, the sensitive parameters are discovered and amended in order to make better use of the mode for river valley of atmospheric environmental impact prediction, designed for the early stage of the construction project to provide more reliable prediction results... |
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