@article {DING20111303,
	title = {The influence of temperature and aerosol acidity on biogenic secondary organic aerosol tracers: Observations at a rural site in the central Pearl River Delta region, South China},
	journal = {Atmospheric Environment},
	volume = {45},
	number = {6},
	year = {2011},
	pages = {1303 - 1311},
	abstract = {At a rural site in the central Pearl River Delta (PRD) region in south China, fine particle (PM2.5) samples were collected during fall-winter 2007 to measure biogenic secondary organic aerosol (SOA) tracers, including isoprene SOA tracers (3-methyl-2,3,4-trihydroxy-1-butene, 2-methylglyceric acid, 2-methylthreitol and 2-methylerythritol), α-pinene SOA tracers (cis-pinonic acid, pinic acid, 3-methyl-1,2,3-butanetricarboxylic acid, 3-hydroxyglutaric acid and 3-hydroxy-4,4-dimethylglutaric acid) and a sesquiterpene SOA tracer (β-caryophyllinic acid). The isoprene-, α-pinene- and sesquiterpene-SOA tracers averaged 30.8{\textpm}15.9, 6.61{\textpm}4.39, and 0.54{\textpm}0.56ngm-3, respectively; and 2-methyltetrols (sum of 2-methylthreitol and 2-methylerythritol, 27.6{\textpm}15.1ngm-3) and cis-pinonic acid (3.60{\textpm}3.76ngm-3) were the dominant isoprene- and α-pinene-SOA tracers, respectively. 2-Methyltetrols exhibited significantly positive correlations (p\&lt;0.05) with ambient temperature, probably resulting from the enhanced isoprene emission strength and tracer formation rate under higher temperature. The significantly positive correlation (p\&lt;0.05) between 2-methyltetrols and the estimated aerosol acidity with a slope of 59.4{\textpm}13.4ngm-3 per μmol [H+] m-3 reflected the enhancement of isoprene SOA formation by aerosol acidity, and acid-catalyzed heterogeneous reaction was probably the major formation pathway for 2-methyltetrols in the PRD region. 2-Methylglyceric acid showed poor correlations with both temperature and aerosol acidity. The α-pinene SOA tracers showed poor correlations with temperature, probably due to the counteraction between temperature effects on the precursor emission/tracer formation and gas/particle partitioning. Among the α-pinene SOA tracers, only cis-pinonic acid and pinic acid exhibited significant correlations with aerosol acidity with slopes of -11.7{\textpm}3.7 and -2.2{\textpm}0.8ngm-3 per μmol [H+] m-3, respectively. The negative correlations observed for α-pinene SOA tracers might result from their transfer from particle to gas phase with the increase of aerosol acidity. The ratio of cis-pinonic acid plus pinic acid to 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA) ranged from 0.28 to 28.9 with a mean of 7.19, indicating the relatively fresh α-pinene SOA tracers during our campaign.},
	keywords = {Pearl River Delta (PRD)},
	issn = {1352-2310},
	doi = {http://dx.doi.org/10.1016/j.atmosenv.2010.11.057},
	url = {http://www.sciencedirect.com/science/article/pii/S1352231010010289},
	author = {Xiang Ding and XinMing* Wang and Mei* Zheng}
}
