合肥市冬季颗粒物污染传输通道分析及通量研究

综合前后向轨迹聚类分析、激光雷达探测传输量及典型案例,系统分析2018-2020年冬季合肥市主要传输型重污染过程,揭示合肥大气污染输送通道的主要特征和污染期间PM_2.5的传输通量。结果表明:合肥市冬季污染主要输入通道分别为京津冀-山东西部-安徽北部-合肥(35%)、山东南部-安徽北部-南京-合肥(26%)、内蒙古-河北-山东-江苏中部-合肥(24%)、内蒙古-山西-河北南部-河南-安徽北部-合肥(15%);主要输出通道为合肥-六安或安庆-湖北-江西(54%)、合肥-安徽北部-江苏北部(18%)、合肥-河南南部-陕西(17%)、合肥-上海或浙江-海上(11%)。对激光雷达监测结果采用像素检测法分析,结果表明2018-2020年污染传输过程的平均传输通量分别可达20.3、33.7、19.5 t/h,年际差异较大。外源传输通量较高时的主导风向为偏北风,并且风速为3.1 m/s左右。合肥市处于安徽省自北向南污染传输通道的中游区域,受上游城市传输影响显著,典型污染传输型的平均传输通量可比上游城市(淮北市)低57.6%,比下游城市(池州市)高25.5%,且污染过程中常伴随PM_2.5的二次生成,主要生成成分为NH₄⁺与NO₃^-等。

Study on the Transmission Channels and Fluxes of Particulate Pollution in Hefei in Winter

The main transmission-type heavy pollution processes that occurred in Hefei in the winter of 2018-2020 were systematically analyzed,relying on forward and backward trajectory cluster analysis,lidar detection transmission volume and typical case analysis,which were researched to reveal the main characteristics of air pollution transmission channels in Hefei.The results showed that the main input channels of winter pollution in Hefei were Beijing,Tianjin and Hebei(BTH)-Western Shandong-North Anhui-Hefei(35%),Southern Shandong-North Anhui-Nanjing-Hefei(26%),Inner Mongolia-Hebei-Shandong-Central Jiangsu-Hefei(24%),and Inner Mongolia-Shanxi-Southern Hebei-Henan-Northern Anhui-Hefei(15%).Meanwhile,the main export channels were Hefei-Lu''an or Anqing-Hubei-Jiangxi(54%),Hefei-Northern Anhui-Northern Jiangsu(18%),Hefei-Southern Henan-Shanxi(17%),and Hefei-Shanghai or Zhejiang-Marine area(11%).The transmission flux of PM_2.5 with a large inter-annual difference during the pollution episode was analyzed with the pixel detection method for lidar figures.From 2018 to 2020,the average transmission flux of the pollution transmission processes reached 20.3,33.7,and 19.5 t/h,respectively.When the external source transmission flux was high,the dominant wind was northerly wind,and the wind speed was about 3.1 m/s.Hefei was located in the midstream of the pollution channel from north to south in Anhui Province,which was extremely vulnerable to pollution transmission from upstream cities.The average transmission flux of the typical pollution transport episodes was 57.6% lower than that of the upstream city(Huaibei) and 25.5% higher than that of the downstream city(Chizhou).In addition,the pollution process was often accompanied by the secondary generation of PM_2.5,with the main components being NH₄⁺ and NO₃^-.