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环境科学学报（英文版）
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2026年10期
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Variability and ozone formation potential of ambient non-methane hydrocarbons in a tropical semi-arid atmosphere of northwest India
Variability and ozone formation potential of ambient non-methane hydrocarbons in a tropical semi-arid atmosphere of northwest India
摘要
We present first-time measurements of twenty-six ambient non-methane hydrocarbons(NMHCs;C2-C8),in-cluding isoprene(C5H8),at a semi-arid site in northwest India(Ajmer;26.45°N,74.64°E),during January 2022-December 2023.Ambient samples were analyzed using a thermal desorption gas chromatography system equipped with dual flame ionization detectors.Daily total NMHC levels ranged from 6 ppbV to＞100 ppbV.Most NMHCs,except isoprene,toluene,ethylbenzene,m-xylene and o-xylene,exhibited the highest levels in winter and the lowest in the monsoon.In contrast,others were highest in the pre-monsoon and toluene was highest dur-ing monsoon.These variations reflect the combined influence of emissions,chemistry and meteorology.Toluene and o-xylene were the dominant NMHCs(25％-67％).Correlation analyses indicated major contributions from liquefied petroleum gas(LPG)and vehicular emissions,with additional influence from urban and oil and natural gas activities.Compared with other Indian sites,NMHCs levels at Ajmer were 2-5 times lower than Ahmedabad and Udaipur and 10 times lower than Delhi.The total ozone formation potential was highest in the monsoon(about 175 ppbV)and lowest in the post-monsoon(about 55 ppbV),with dominance of o-xylene(24％-33％)and toluene(8％-37％).Propylene-equivalent concentrations were highest in the pre-monsoon(30.23 ppb C)and lowest in the post-monsoon(7.28 ppb C).Similarly,OH reactivity was highest in the pre-monsoon(19.58 s-1)and lowest in the post-monsoon(4.71 s-1),dominated by benzene and toluene.These findings emphasize the importance of NMHC chemistry in a climatically sensitive region and highlight the need for their continuous monitoring.
年，卷(期)：
2026, 168(10)
机标分类号：
TP391.4
S
TV213.4
在线出版日期：
2026年10月9日
