合肥市典型交通干道大气苯系物的特征分析

Characteristics of Atmospheric BTX near a Main Road in Hefei City

为研究合肥市交通干道大气苯系物污染状况,采用自主研制的差分吸收光谱(DOAS)系统,于2016年3月期间对合肥市交通主干道大气苯系物(苯、甲苯、间二甲苯和邻二甲苯)以及常规污染物NO_2、SO_2等进行了连续观测.观测结果显示,观测期间苯、甲苯、间二甲苯和邻二甲苯的平均浓度分别为:21.7、63.6、33.9和98.7μg·m^(-3).与国内外其它城市比较显示,合肥市交通干道大气苯和甲苯的污染处于中等水平,二甲苯的污染较为严重.结合观测期的间风速风向、T/B特征比值以及与CO等污染物的相关性,对上述苯系物来源进行了分析,结果显示观测期间T/B值为0.8~4.5,苯、甲苯与CO的相关性系数R分别为0.55和0.34.表明机动车尾气排放是观测区域苯和甲苯的主要排放源之一,同时也受到周边工业园区排放的影响,二甲苯的主要排放源为观测地点北偏东方向的涂料行业工业园区.苯和甲苯的夜间高浓度峰值分析结果表明,夜间的高浓度苯和甲苯可能主要来源于观测地点周边工业园区的排放.观测区域苯系物的臭氧生成潜势(OFP)表现为邻二甲苯>间二甲苯>甲苯>苯,其中二甲苯的OFP占总OFP的85%,表明周边工业园区的排放对该地区臭氧生成的贡献较大.

In order to study levels of BTX near a main road in Hefei in March 2016,benzene,toluene,m-xylene,and o-xylene（BTX） and conventional pollutants（such as NO2 and SO2） in the atmosphere were monitored through a home-made differential optical absorption spectroscopy（DOAS） system. Results showed that average concentrations of benzene,toluene,m-xylene,and o-xylene were 21. 7,63. 6,33. 9,and 98. 7 μg·m^-3,respectively. Compared with other cities both in China and elsewhere,benzene and toluene pollution can be considered to be of medium level,while xylene pollution is serious. Wind direction,T/B ratio,and correlation with CO were also analyzed,together with BTX sources. Result showed that the T/B ratio was 0. 8-4. 5,with correlation coefficients of benzene,toluene,and CO of 0. 55 and 0. 34,respectively. These values indicate that benzene and toluene are mainly derived from automotive emissions,also affected by surrounding industrial parks. Xylene is mainly derived from a coating industrial park north of the observation site. It was shown that high night-time concentrations of benzene and toulene could be due to industrial emissions from the industrial parks around the observation site. The ozone formation potential is in the order of o-xylene m-xylene toulene benzene at the observation site. The ozone formation potential of xylene accounted for 85% of total ozone formation potential,indicating that emissions from surrounding industrial parks contribute greatly to ozone formation in the area.