| Chongqing Municipality is the largest industrial city in the southwest region of China and meanwhile is the youngest municipality directly under the central government of China. With rapid economic development in recent years, the sharp rise in energy consumption, continuous increase in the number of vehicles, plus main use of sulphur coals, special geographic and meteorological conditions, atmospheric pollution in Chongqing is specially serious. Currently, Chongqing has become one of Chinese cities suffering the most serious air pollution. Serious air pollution not just threatens human health, but also becomes the important barrier restricting economic development. Therefore, it is very necessary to comprehensively and clearly know the trend to air pollution changes in central downtown of Chongqing Municipality, accurately forecast future air quality and timely release early warning when the air pollution is specially serious so as to achieve the purpose of protecting residents’ health, improving environmental awareness of the public and enhancing air pollution control.This study has utilized the data from11automatic monitoring points for air quality and relevant meteorological data in central downtown of Chongqing Municipality during2000and20005, deeply studied space-time change laws of SO2, NO2and PM10, developed air pollution forecasting research by combing atmospheric pollution diffusion model software CALPUFF and mesoscale meteorological model MM5, and proposed the suggestion of graded alarm according to air pollution index (API) in combination of foreign air pollution alarm examples as well as China’s environmental standards and special circumstances of Chongqing. The specific research contents include the following three aspects:(1) Through analysis of air automatic monitoring data in2000-2005, the concentrations of SO2, NO2and PM10show the downtrend year by year; monthly change features of air pollution show air pollution conditions of the central downtown are serious in spring and winter, light in summer and autumn, showing obvious seasonal variation features. This is greatly related to the changes in meteorological conditions in different seasons; seeing from spatial distribution, the air quality of Beibei and Yubei districts in central downtown is good; the air quality of the core districts including Yuzhong and Dadukou districts is poor. Correlation analysis of meteorological elements and air pollution index shows the rise in the wind speed, the precipitation and the temperature can effectively reduce air pollutant concentration; ground atmospheric pressure, relative humidity, cloud amount and stability will also influence the air quality, and their influences are relatively complex.(2) The degree of accuracy of air pollution forecasting system combining CALPUFF and mesoscale meteorological model MM5can reach about70%in practical applications. This system is further applied in the process of wind field simulation analysis and SO2concentration field simulation analysis. The simulation result is basically matched with practical conditions. This system can not only be mastered easily, but also is economical. Thus, it has wide application prospect in the future.(3) The following suggestion is not just easily accepted by the public, but also shows certain rationality in the aspects of the economy and public tolerance:regard grading standards of mild pollution, middle-level pollution and serious pollution in API standards as the first-degree alarm, the second-degree alarm and the third-degree alarm limiting values of air pollution in Chongqing. This suggestion is feasible in practices. |
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