苏南地区一次灰霾天气程中颗粒物的空间特征分析  

The Spatial Characteristics of Particulate Matters during a Haze Episode in South of Jiangsu

作　　者：沈毅 王界 盛世杰 张毅 万学平 孟胜强 

机构地区：[1]无锡新区环境监测中心,江苏无锡214028 [2]无锡中科光电技术有限公司,江苏无锡214100

出　　处：《环境科学与技术》2017年第5期200-205,共6页Environmental Science & Technology

基　　金：国家火炬计划(2014GH710703);江苏省科技成果转化专项资金(BA2015010);国家重点研发计划(JFYS2016ZY01002708);国家重点研发计划(2016YFC0200400)

摘　　要：针对2014年5月24-31日期间江苏省南部的一次典型的灰霾天气过程,结合地面环境空气自动监测站数据(AQI、PM_(10)和PM_(2.5))、近地面能见度数据、激光雷达垂直探空结果、气象条件数据,对此次区域灰霾污染的近地面特征和空间特征进行了分析。发现此次灰霾污染过程可以分为2个阶段:第一个阶段,5月24-25日,空气质量由良逐渐增重为中度污染,其中25日11时AQI峰值达到200,近地面能见度2.2 km。近地面PM_(10)和PM_(2.5)的峰值浓度分别为215μg/m^3和150μg/m^3,该阶段PM_(2.5)/PM_(10)的比值均值达到0.6;无锡地区2.5 km高度范围内分布大量的强消光性粒子,导致消光系数超过0.8 km^(-1),退偏振度不足0.1,以局地球形细粒子为主;第二个阶段,26-31日空气质量再次恶化,污染程度累积,27日23时、29日21时、31日3时达到484、239和231。26-31日,近地面首要污染物是PM_(10),PM_(10)的均值210μg/m3,PM_(2.5)的均值97.7μg/m^3,PM_(2.5)/PM_(10)的比值均值低于0.5;大气中分布的颗粒态污染物粒子的不规则程度增大,大气消光系数略有减弱,约0.6 km^(-1),退偏振度系数大于0.3,说明此阶段大气中含有较多的浮尘粒子。其中,27日消光系数有突然增大的过程,这与江苏地区的秸杆燃烧过程密切。通过后向轨迹与卫星监测的火点分布,表明27、28日的气流轨迹将大量的不完全燃烧的生物质粒子带到观测站点附近。近地面的气象条件分析发现,26-29日,随近地面的大气压力从1 000 h Pa降至993 h Pa,相对温度从80%以上降至不足45%,峰值超过6 m/s,直接使得空气中颗粒物增多。The vertical characteristics in a regional haze episode in south of Jiangsu from May 24th-31 st 2014 was analyzed with a data set of AQI,PM2.5,PM10,visibility,near ground meteorological parameters and LiDAR observation in Wuxi City.This episode was marked as a two-stage process. In first stage,from May 24 th to 25 th,air quality index（AQI）climbed from the grade of ＂moderate＂to ＂severe＂pollution with a peak value of 200 at 11 am 25 thand the corresponding visibility lower than 2 km. The maximum concentrations of PM10 and PM2.5in this stage were 215 μg/m3 and 150 μg/m3 respectively. The dominated fine particulate matters were verified by an averaged ratio of PM2.5/PM10 of close to 0.6. LiDAR observations showed particles mainly stayed in 2.5 km with strong extinction feature. The extinction coefficient was over 0.8 km-1 and depolarization coefficient was no more than 0.1 which was dominated by local spherical fine particle from near surface. In sec-ond stage,26th-31 st,the air quality of Wuxi exaggerated to ＂serious pollution＂with AQI of 484,239 and 221 appearing at11 pm 27 th,9 pm 29 th and 3 am 31 st. The primary pollutant was PM10 with an average value of 210 μg/m3 and 97.7 μg/m3 for PM10and PM2.5respectively. The ratio of PM2.5/PM10 in second stage reduced to less than 0.5 illustrated a main distribution of coarse particulate matters in air. In this stage,the extinction coefficient was down to 0.6 km-1 and depolarization coefficient increased to 0.3 along with a great of floating dust aerosol injected into atmospheric boundary layer. The depolarization fromLi DAR results showed a sharp magnification on 27 thnight which had a close relation to biomass-burning transport in south of Jiangsu. The back trajectories method also demonstrated that pollution transport over-boundary produced by northwest fire points directly contributed to the high extinction in Li DAR observation and peak values of PM10 and PM2.5on 27 thand 28th.The meteorological parameters near ground level 26th-29 thfound that atm

关 键 词：灰霾 激光雷达 消光系数 退偏振度 后向轨迹 跨界传输 

分 类 号：X82[环境科学与工程—环境工程]