基于多源探测的南京市大气污染状况分析

Analysis of Atmospheric Pollution Status over Nanjing Based on Multi-Source Detection

南京市作为长三角地区的核心城市之一,工业发达,大气污染状况较为严重.为深入研究南京市污染状况,利用MODIS以及CALIPSO的气溶胶产品对南京市2011—2019年气溶胶特性进行分析,并基于地基反应性气体分析仪数据分析了冬季南京市大气中4种常见反应性气体(SO_(2)、NO、NO_(2)、O_(3))的体积分数时序状况.结果表明:①南京市2011—2019年气溶胶光学厚度(AOD)整体呈下降趋势,冬季AOD值可达0.7,污染程度为四季中最高,且气溶胶以粗粒子和吸收性粒子为主.②南京市近地层大气(2 km以内)以大粒子和不规则颗粒物为主,2~6 km高度层内细粒子与规则颗粒物的占比逐渐增多,且2~6 km高度层内粒子的体积大小变化不大.③冬季4种常见的反应性气体中,φ(NO)在大气中的变化最为显著,且最高值可达160×10^(-9),φ(NO_(2))与φ(O_(3))在大气中的变化趋势相反.由于排放限制措施、工厂脱硫措施的推广以及光化学反应的影响,导致φ(SO_(2))较低,仅在3×10-9左右.结合OMI卫星观测数据发现,受新冠肺炎疫情下工厂停工的影响,2020年初南京市φ(NO_(x))维持在较低水平.研究显示,近年来南京市颗粒物污染状况有所改善,但仍需注意粗颗粒物的排放,需严格控制工厂气态污染物,尤其是NO_(x)的排放.

Nanjing,as one of the core cities in the Yangtze River Delta,has developed industries and serious air pollution.In order to further study the pollution status in Nanjing,MODIS and CALIPSO′s aerosol products were used to analyze the aerosol characteristics of Nanjing from^(2)011 to 2019.Then,four kinds of common reactive gases(SO_(2),NO,NO_(2) and O_(3))in the atmosphere of Nanjing in winter were analyzed based on the data of ground-based reactive gas analyzer.The results shows that:(1)The AOD over Nanjing showed a downward trend in the whole nine years,and the AOD could reach 0.7 in winter.The pollution degree was the highest in the four seasons.The aerosol was mainly composed of coarse particles and absorbent particles in winter.(2)The near surface atmosphere(within 2 km)of Nanjing was dominated by large particles and irregular particles.Mainly,the proportion of fine particles and regular particles gradually increased within 2-6 km,and the volume of particles changed little within 2-6 km.(3)Among the four common reactive gases in winter,theφ(NO)in the atmosphere was the most significant,and the maximum value was 160×10^(-9),and the change trend of NO_(2) and O_(3) was opposite.Due to the emission limitation and the promotion of desulfurization measures,and the influence of photochemical reaction,theφ(SO_(2))was the lowest,only about 3×10-9.Combined with OMI data,theφ(NO_(x))over Nanjing remained at a low level in early 2020 due to the shutdown of factories because of COVID-19.Studies have shown that the particulate pollution in Nanjing has improved in recent years,but it is still necessary to pay attention to the emission of coarse particles,and it is necessary to strictly control the emission of gaseous pollutants from factories,especially NO_(x).