太原市夏季大气O_(3)演变及VOCs贡献特征研究

Characteristics of Atmospheric O_(3) and the Contributions of VOCs in Summer,Taiyuan

本研究开展了太原市夏季大气臭氧(O_(3))变化特征研究,并探讨NOx和主要VOCs组分对O_(3)贡献特征。结果显示,O_(3)浓度日高值在(65.00~286.00)μg/m^(3)之间,均值为188.52μg/m^(3),期间45天超过国家空气质量二级标准。O_(3)日变化表现为9:00-14:00的快速升高,14:00-18:00呈现日均高值。O_(3)高值天气影响特征表现为白天持续高温(≥30℃),低湿度(≤35%),西风和西南风向影响(≥2 m/s).NO_(X)日高值在(31.00~234.00)μg/m^(3)变化,日变化表现为白天低、晚上高。主要前体物醛酮(OVOCs)(10.41 ppbv),烯烃(3.27 ppbv)和芳香烃(1.32 ppbv)的升高,导致O_(3)高值。VOCs对O_(3)生成贡献为108.00 ppbv,O_(3)高值天OFP从92.93 ppbv达到123.07 ppbv,上升32.44%,甲醛、乙醛和异戊二烯增长最大,达到17.42 ppbv、7.34 ppbv和6.35 ppbv.经过比值分析发现,太原市VOCs来源主要受西和西南方向焦化和煤炭行业区域传输影响,其OVOCs主要来自光化学反应的二次生成。

In this study,the variation of atmospheric ozone(O_(3)) was carried out in summer in Taiyuan,and the relationship between O_(3 )with NOx and main VOCs was studied.The results showed that the daily O_(3) concentration varied from 65.00 to 286.00 μg/m^(3),with an average of 188.52 μg/m^(3),exceeding the national air quality standard II for 45 days.The daily O_(3) increased rapidly from 9:00 to 14:00,and reached the highest values during 14:00 to 18:00.The influence of meteorological parameters on the days with O_(3) high-value presented continuous high air temperature(≥30℃),low relative humidity(≤35%),and west wind and southwest wind(≥2 m/s).The daily NOx concentration varied from 31.00 to 234.00 μg/m^(3),and it was low in the daytime and relatively higher at night.The increase of main precursors including carbonyls(OVOCs)(10.41 ppbv),alkenes(3.27 ppbv) andaromatic hydrocarbons(1.32 ppbv) led to the higher levels of O_(3).The ozone formation potential(OFP) of VOCs was 108.00 ppbv,which increased from 92.93 to 123.07 ppbv and increased by 32.44%.Formaldehyde,acetaldehyde and isoprene increased rapidly and reached 17.42 ppbv,7.34 ppbv and 6.35 ppbv,respectively.The ratio analysis showed that the sources of VOCs in Taiyuan were mainly affected by the regional transport of coking and coal industry in the west and southwest,and the OVOCs mainly comes from the secondary photochemical reaction.