石家庄市挥发性有机物和臭氧的污染特征及源解析

Characteristics and Source Apportionment of VOCs and O in Shijiazhuang

为研究石家庄市挥发性有机物(VOCs)的化学特征和污染来源,于2017年3月至2018年1月取3个国控点进行环境VOCs的罐采样及分析,并结合臭氧(O3)及气象数据进行相关性分析,采用正交矩阵因子模型(PMF)开展溯源解析;为确定夏季O3的污染周期,利用小波分析研究其时序特征.结果表明,石家庄市采样期间VOCs浓度为(137.23±64.62)μg·m^-3,以卤代烷烃(31.77%)、芳香烃(30.97%)和含氧VOCs(OVOCs,23.76%)为主.采样期间VOCs的季节变化为:冬季(187.7μg·m^-3)>秋季(146.8μg·m^-3)>春季(133.24μg·m^-3)>夏季(107.1μg·m^-3),空间特征呈自西向东逐渐增加的格局.监测期内O3与VOCs、NO2呈显著负相关,与温度、日照时数、风速和能见度呈正相关.在夏季O3≤160μg·m^-3时,6月应关注气温开始上升后4~5 d的气象条件变化,而7~8月需关注7~8 d后的气象变动.PMF溯源解析了6个VOCs的来源,依次为:汽油车排放源(24.78%)、柴油车排放源(24.69%)、溶剂使用源(18.64%)、化工生产排放源(11.87%)、区域背景(10.84%)及制药工业生产排放源(9.17%);其中汽油车和柴油车排放源的O3生成潜势(OFP)贡献(54.98%)超过一半.因此,石家庄市夏季O3削减的关键是控制交通及工艺过程源的排放.

To study the composition characteristics and sources of volatile organic compounds(VOCs)in Shijiazhuang City,three national control points were selected to conduct VOCs sampling and analysis from March 2017 to January 2018.The correlation of VOCs through combination with meteorological and ground-level O3 data,and the sources of VOCs were analyzed by positive matrix factorization(PMF).To quantify the pollution period of O3 in summer,its temporal sequence characteristics were studied by wavelet analysis.During the sampling period,the average concentration of ambient total VOCs(TVOCs)was(137.23±64.62)μg·m^-3.Haloalkanes were the most dominant VOC compounds,accounting for 31.77%of total VOCs mass,followed by aromatic(30.97%)and oxygenated VOCs(OVOCs,23.76%).The seasonal variation in VOC concentration followed the trend in winter(187.7μg·m^-3)>autumn(146.8μg·m^-3)>spring(133.24μg·m^-3)>summer(107.1μg·m^-3);the concentration of VOCs shows a trend of increasing gradient from west to east.The O3 concentration correlated negatively with VOCs and NO2,and positively with temperature,sunshine duration,wind speed,and visibility.Changes in meteorological elements were concerned before the occurrence of ozone pollution in summer,especially in 4-5 days in June and 7-8 days during July to August after the occurrence of increasing temperature.Finally six potential sources of VOCs were quantified by the PMF model,including from gasoline emissions(24.78%),diesel vehicle emissions(24.69%),solvent usage(18.64%),the chemical industry(11.87%),regional background(10.84%),and the pharmaceutical industry(9.17%).Ozone formation potential(OFP)contribution of emission sources of gasoline and diesel vehicles(54.98%)was over half of the total contribution.Meanwhile,these findings illustrated that control of vehicle emissions and industrial sources would be an important way to reduce VOCs concentrations and improve air quality in Shijiazhuang.