Impacts Of Different Sources On Air Pollutants Over East China Based On Numerical Study And Assessment Of Emission Reduction

In this study,the meso-scale meteorology-chemistry coupled model WRF-Chem was used to simulate the contribution of different emission sources in MEIC inventory(industry,power,residential,transportation and agricultural)to main atmospheric pollutants over East China.In addition,based on the "13th Five-Year Plan" emission reduction target,"till 2020,SO2,NOx emissions will fall by 15%compared with 2015,and volatile organic compounds will drop by more than 10%,sensitivity tests were used to quantitatively evaluate the effect of "13th Five-Year Plan" reduction on the concentration of major atmospheric pollutants,and further analyzed the effect of NOx and VOCs on O3.The conclusions are as follows:(1)Industry contributes about 40%～60%PM2.5 in spring,summer and autumn,while residential contributes the largest in winter due to the use of scattered coal for heating,with over 50%in the areas such as Shandong,Anhui and Jiangsu province.The contributions from agriculture,power and transportation to PM2.5 have minor seasonal differences,in which about 20%～3 0%from agriculture,about 10%from transportation and power plant.It may indicate that we should mainly regulate residential source in winter,and limit the emission of industry and agriculture in other seasons.(2)The contribution of primary PM2.5 from coal-based industry,residential and power plant are about 50%～60%,and the contribution of NO;and NH4 from transportation and agriculture could be up to 53%and 93%,respectively.The contribution of SO42-from industry and power plant is only about 5%～15%which is possibly underestimated due to under-predicted sulfate by the model.The contribution of OC from residential,BC from transportation and Na+ and Cl-from all major sources to the total PM2.5 is about 30%,15%,and less than 3%,respectively.(3)Industry is the most important source of SO2-in spring,summer and autumn,the contribution rate exceeds 70%in East China and about 50%～60%in winter,and then the contribution of power is 20%-35%.The total contribution of industry and power sources to SO2 exceeds 90%.NO2 mainly comes from industry,power and transportation,industry and power contribute 30%-40%and 20-40%,respectively,and transportation contribute about 20%in Shandong and Yangtze River Delta,and over 40%in other regions.Unlike other pollutants,the contribution rate of industry,power and transportation to O3 in Shandong and Yangtze River Delta is negative,that is,the concentration of O3 increased after the industry,power and transportation were turned off,the distribution of O3 and NO2 concentrations showed a counter-gradient profile,since the O3 concentration in autumn and winter is relatively lower than that in spring and summer,and heating result in higher NOx emissions,indicating that in autumn and winter NOx have a significant consumption of O3 in Eastern China.(4)The "13th Five-Year Plan" emission reduction sensitivity tests show that PM2.5 can be reduced by 5%in winter,and about 10～15%in summer,because the baseline of PM2.5 concentration in summer is relatively small compared to winter,the emission reduction effect is relatively prominent.There is little difference in the seasonal changes of SO2,which can be reduced by 20%～30%.In winter,NO2 decreases by 20%-25%in the south of East China,10%～15%in Shandong,northern Anhui and the Yangtze River Delta,and decreases by 20%～30%in summer.East China belongs to the VOCs control area where NOx concentation is relatively high,reducing NOx emissions will cause an increase in O3,but at the same time,the reduction of VOCs can reduce O3 concentration,O3 concentration decreases with decreasing VOCs.(5)Simulated tests were conducted in summer with severe ozone pollution in East China.VOCs emission reduction has a significant impact on Shandong Province and the Yangtze River Delta region,with NMVOC emission reductions of 10%,30%,50%,and 100%,the decrease in 03 concentration is approximately 0～10μg/m3,5～15μg/m3,10～25μg/m3,25～80μg/m3,the reduction ratios are 5～10%,10～25%,15～35%,35～50%respectively.When the anthropogenic NMVOC emission reduction exceeds 50%,the number of days when O3 peak concentrations in Nanjing and Jinan reach the secondary standards exceeds 87%and 70%,respectively.In the more densely populated and economically developed regions of Shandong and the Yangtze River Delta,the reduction of anthropogenic emissions of volatile organic compounds can effectively reduce the concentration of ozone.Compared with the rainy weather,the reduction of anthropogenic emissions of NMVOC in summer clear air can significantly reduce the ozone concentration.