西南典型区域夏季大气含氧挥发性有机化合物来源解析

Sources Apportionment of Oxygenated Volatile Organic Compounds(OVOCs)in a Typical Southwestern Region in China During Summer

含氧挥发性有机物(OVOCs)是大气光化学过程中的重要中间产物,是臭氧的重要来源之一.利用质子转移反应飞行时间质谱仪(PTR-TOF-MS)在成都平原对OVOCs进行观测,探讨其日变化特征、光化学反应活性、臭氧生成潜势和来源.结果表明,10个VOCs[乙醛、丙酮、异戊二烯、甲基乙基酮(methyl ethyl ketone,MEK)、甲基乙烯基甲酮(methyl vinyl ketone,MVK)、甲基丙烯醛(methacrolein,MACR)、苯、甲苯、苯乙烯、C8芳香烃和C9芳香烃]总浓度(体积分数)为(10.97±4.69)×10^(-9),OVOCs为(8.54±3.44)×10^(-9),芳香烃为(1.53±0.93)×10^(-9),生物源VOCs为(0.90±0.32)×10^(-9);光化学活性和臭氧生成潜势均排名前三的物种为:异戊二烯、乙醛和C8芳香烃;3个OVOCs物种(乙醛、丙酮和MEK)主要来源于本地生物源和人为二次源,且丙酮有较强的区域背景值,说明该地区的污染受到较为显著的区域传输的影响.本研究可加深对西南地区臭氧的区域形成机制的认识,为科学管控臭氧污染提供依据.

Oxygenated volatile organic compounds(OVOCs)are important intermediates in the troposphere and the most important sources of ozone.Proton-transfer-reaction time-of-flight mass spectrometry(PTR-TOF-MS)was used to measure VOCs in the Chengdu Plain,Southwestern China.The diurnal variations,photochemical reactivity,O_(3) formation potential,and sources were also investigated.The mixing ratios of ten kinds of VOCs(acetaldehyde,acetone,isoprene,Methyl ethyl ketone,Methyl vinyl ketone and Methacrolein,benzene,toluene,styrene,C8 aromatics,and C9 aromatics)were(10.97±4.69)×10^(-9).The concentrations of OVOCs,aromatic hydrocarbons,and biogenic VOCs were(8.54±3.44)×10^(-9),(1.53±0.93)×10^(-9),and(0.90±0.32)×10^(-9),respectively.Isoprene,acetaldehyde,and m-xylene were the top three photochemically active species with the greatest O_(3) formation potentials.The dominant three OVOCs species(acetaldehyde,acetone,and MEK)were mainly derived from local biogenic sources and anthropogenic secondary sources,and acetone had a strong regional background level,indicating that pollution in this area is significantly affected by regional transmission.This study deepens the understanding of regional O_(3) formation mechanisms in southwest China and provides a basis for the scientifically informed control of O_(3) pollution.