@article {li2018spatiotemporal,
	title = {Spatiotemporal variations of ambient volatile organic compounds and their sources in Chongqing, a mountainous megacity in China},
	journal = {Science of the Total Environment},
	volume = {627},
	year = {2018},
	pages = {1442{\textendash}1452},
	abstract = {Chongqing is the largest\&nbsp;megacity\&nbsp;in southwest China and has a mountainous and humid climate. Online measurements of 96 volatile organic compound (VOC) species were performed at the three sites JYS, CJZ, and NQ, which are located in the northern, central, and southern sections of the Chongqing urban district, respectively. The measurements were performed from August to September 2015, at a time interval of 1\&nbsp;h. The spatiotemporal variation of VOC sources in Chongqing was characterized by combining the positive matrix\&nbsp;factorization\&nbsp;(PMF) model with the online measurement data. The average total VOC\&nbsp;mixing ratios\&nbsp;of the CJZ, NQ, and JYS sites were 41.2, 34.1, and 23.0\&nbsp;ppbv, respectively. The mixing ratios of tracers of incomplete\&nbsp;combustion, exhibited obvious bimodal profiles at the CJZ and NQ sites, whereas those at the JYS site exhibited little change throughout the day.\&nbsp;Isoprene\&nbsp;at the three sites followed a similar pattern of average\&nbsp;diurnal variations\&nbsp;in mixing ratios, with minimums before sunrise and maximums at noon. The dominant sources of\&nbsp;acetaldehyde\&nbsp;and\&nbsp;acetone\&nbsp;were secondary\&nbsp;anthropogenic sourceand aged\&nbsp;air mass\&nbsp;transport, respectively, in the city of Chongqing. Seven sources were apportioned to the results of PMF calculation using spatiotemporal VOCs composition data. The Vehicle-related sources were the largest contributor at CJZ and NQ, contributing 44\% and 37\% of the total VOC mixing ratios, respectively, and exhibited clear diurnal variations. Aged background air, with 68\% of total VOC emissions, dominated the VOC emissions at JYS.\&nbsp;Solvent\&nbsp;utilization was a very important contributor at NQ and coincided with the higher levels of aromatics. O3\&nbsp;formation was generally VOC-limited at NQ and CJZ, and was NOx-limited and transition region alternatively at JYS.\&nbsp;Alkenes\&nbsp;were important for the O3formation at CJZ, and both alkenes and aromatics were important for the O3\&nbsp;formation at NQ.},
	url = {https://www.sciencedirect.com/science/article/pii/S0048969718303966?via\%3Dihub},
	author = {Jing Li and Zhai, Chongzhi and Yu, Jiayan and Liu, Ruilin and Li, Yaqi and Limin Zeng and Shaodong Xie}
}
