Study On The Nonlinear Responses Of Air Quality To Primary Pollutant Emissions In Hangzhou

The Community Multiscale Air Quality (CMAQ) model is now an important research tool in field of atmospheric environmental management and scientific research, and it has been applied very well at home and abroad. However, since CMAQ is too complicated and professional to put it into actual use, its advantages are greatly reduced. Based on the simulated pollutants concentrations from pollutants emissions control matrix of CMAQ experiments, we can establish a fast and efficient "emissions-air quality" response model which can be used to improve the performance of air quality prediction system, quickly and easily evaluate the control effects of the pollutants emissions reduce measures, as well as provide a scientific basis for the development of optimized control program, by means of statistical induction of the functional relationship between pollutants emission control ratio and response concentrations - also called the Response Surface Model (RSM).Based on the above background, an RSM that can be applied to predicting the pollution concentration of the fine particulate matter (PM2.5) in Hangzhou was developed in the present dissertation. The model has 10 control factors:the organic carbon (OC), the black carbon (BC), particles with diameters of 10 μm or less (PM10), nitrogen oxides (NOx) emissions from transportations, NOx emissions from power plants, NOx emissions from industries, sulfur dioxide (SO2) emissions from transportations, SO2 emissions from power plants, ammonia (NH3) and the volatile organic compounds (VOC). Put the combination of these 10 parameters into RSM, the PM2.5 concentration change in the responding control scenario can be quickly calculated. After remaining one-out cross validation and external validation of the RSM established in this dissertation to evaluate its model reliability, the RSM model was applied to study the PM2.5 pollution mechanisms and sources of analysis in Hangzhou, evaluate the NH3 emissions and VOC emissions impact to PM2.5 in Hangzhou, and predict the future air quality in 2020 in Hangzhou as well as the effect of air quality control and abatement policies. The main conclusions of the study are: OC, BC and PM10 emissions have linear response characteristics to PM2.5 emissions, while NOx, SO2, NH3 and VOC have obvious nonlinear response characteristics. Contributions to PM2.5 concentrations of the same pollutant are not the same in different seasons. In winter, the primary pollutants of PM2.5 are more than secondary pollutants; in summer, the proportion of secondary aerosols is much greater than the first component. In winter, it can effectively reduce the PM2.5 pollution by controlling OC, BC and PM10 emissions; when control policy are strengthened, NOx and NH3 influence obviously. In summer, the impact of PM10 to PM2.5 is still larger; the impacts of NOx emissions from power plants and industries are significantly higher than others.