无锡市一次霾形成过程大气污染物特征分析

于2013年12月21~26日期间对一次霾污染过程中PM2.5、含碳气溶胶、气态污染物（O3，NOx SO2）进行测量，利用微脉冲偏振激光雷达获得气溶胶消光和退偏振度参数，分析了霾过程大气污染物的特征。结果显示：本次霾污染过程持续3.4天，以细粒子污染为主。采样期间，PM2.5的质量浓度小时平均值为131.04µg•m-3，霾天气下为183.75µg•m-3，是非霾天气的2.98倍。碳质气溶胶（TC）占PM2.5的24.18%，并且与PM2.5之间存在较好的相关性（R2=0.790）。在霾天气下TC在PM2.5中所占的比例（TC%，16.65）要比非霾天气（TC%，34.38）小，二次水溶性无机盐粒子的快速增长可能是造成霾天气PM2.5质量浓度较高的重要原因之一。霾天气和非霾天气对比：O3浓度无明显变化，受太阳辐射影响较大；NOx和SO2的体积分数在霾天气下分别是非霾天气下的1.66和1.68倍；SO2浓度的增加不仅与本地SO2的累积有关，还有可能是受外来输入的粒子中存在含硫化合物、抑制了SO2的非均相反应造成的。

Analysis of Air Pollutants During Process of a Haze in Wuxi City

The concentrations of PM2.5, carbonaceous aerosols, O3, NOx, SO2 were measured from a haze event in Wuxi City, Jiangsu, Chinafrom Dec.21th to Dec.26th, 2013. Aerosol extinction coefficient and depolarization ratio were measured by micro-pulse polarization lidar. Characteristics of air pollutants in haze days were analysed. The haze event last for 3.4 days and fine particles were the main pollutants. Hourly average mass concentration of PM2.5 was 131.04µg•m-3, and 183.75 µg•m-3 in haze days which was 2.98 times higher than in normal days. Total carbon (TC), which was strongly correlated (correlation coefficients=0.790) with PM2.5, accounted for 24.18% of the mass concentration of PM2.5. In haze days, the ratio of TC to PM2.5 was 16.65%, lower than that in normal days (34.38%). Thissuggested that secondary inorganic particles might have a fast increase in haze days, which led to a high concentration of PM2.5. The concentration of O3, affected greatly by solar radiation, showed less variation both in haze days and normal days. The volume fraction of NOx and SO2 in haze days was 1.66which was1.68 times higher than in normal days, respectively. The increase concentration of SO2 was not only related to local accumulation but also can be affected by sulfur-rich particles from external transmission; the sulfur-rich particles might inhibit the heterogeneous reaction of SO2.