南京一次重霾天气纳米气溶胶观测研究

An observational study of nano-scale aerosol during a heavy haze in Nanjing

为加深对南京地区重霾天气过程纳米尺度气溶胶物理特征的了解,对2017年12月21—25日的一次重霾天气过程进行了综合探测,利用宽范围粒径谱仪观测了此次过程中10~1000 nm颗粒物数浓度,并结合能见度等气象要素,对重霾期间纳米气溶胶谱分布进行了分析。结果表明:此次霾重污染过程出现在低温、高湿、气压上升期间;与非重污染时期相比,重污染期间N 10-20与N 20-100降低,N 100-1000升高;重污染期间气溶胶粒子平均数浓度为17035个/cm^(3),低于非重污染期间粒子数浓度,N 100-1000占总数浓度的55.05%;重霾发生期间纳米气溶胶数浓度谱为单峰结构,峰值在100 nm附近,随着污染加重,纳米气溶胶峰值粒径向大粒径偏移,粒子向大粒径段集中;不同温度对不同粒径粒子数浓度的影响不同,20~100 nm粒径段气溶胶与数浓度与温度呈反相关性,100~500 nm粒子数浓度与温度呈正相关性.

In order to deepen the understanding of physical characteristics of nano-scale aerosol in heavy haze weather process in Nanjing,a heavy haze process during 21-25 December 2017 was selected to detect comprehensively.Based on the aerosol number concentration data those particles are between 10-1000 nmfrom wide range of particle size spectrometer,and combined with meteorological elements,such as visibility,the nano-scale aerosol spectral distribution was analyzed.Results show that the heavy haze pollution occur during the period of low temperature,high humidity and rising air pressure.Compared with non-heavy pollution period,N 10-20 and N 20-100 decrease while N 100-1000 increases in heavy haze period.During heavy pollution,the average concentration of aerosol particles is 17035 in per cubic meter,lower than that during non-heavy pollution.N 100-1000 accounts for 55.05%of the total concentration during heavy pollution.During the occurrence of heavy haze,the nanometre aerosol number concentration spectrum has a single-peak structure,and the peak value is around 100 nm.With the increasing of pollution,the peak particle size of nanometre aerosol is shifted to large particle size,and the particles are concentrated in the large particle size segment.The influence of different temperature on particle number concentration of different particle size is different.The particle number concentration of 20-100 nm is inversely correlated with temperature,while the particle number concentration of 100-500 nm is positively correlated with temperature.