Abstract
Intensive field measurements were carried out at a mountain site and an urban site at the foot of the mountain from September to November 2010 in Hong Kong. Acetone was monitored using both canister air samples and 2,4-dinitrophenylhydrazine cartridges. The spatiotemporal patterns of acetone showed no difference between the two sites (p > 0.05), and the mean acetone mixing ratios on O3 episode days were higher than those on non-O3 episode days at both sites (p < 0.05). The source contributions to ambient acetone at both sites were estimated using a receptor model i.e. Positive Matrix Factorization (PMF). The PMF results showed that vehicular emission and secondary formation made the most important contribution to ambient acetone, followed by the solvent use at both sites. However, the contribution of biogenic emission at the mountain site was significantly higher than that at the urban site, whereas biomass burning made more remarkable contribution at the urban site than that at the mountain site. The mechanism of oxidation formation of acetone was investigated using a photochemical box model. The results indicated that i-butene was the main precursor of secondary acetone at the mountain site, while the oxidation of i-butane was the major source of secondary acetone at the urban site.
Highlights
Acetone is an abundant carbonyl compound in the atmosphere
Compared to other mountain sites, it was found that the acetone concentration at Tai Mo Shan (TMS) (640 m a.s.l) was in line with that at Mt
By comparing the temporal variations at the two sites, we found that the daily concentrations of anthropogenic air pollutants i.e. CO and i-butane were higher at the urban site Tsuen Wan (TW), whereas the daily levels of biomass burning tracer i.e. CH3Cl were similar at the two sites
Summary
Acetone is an abundant carbonyl compound in the atmosphere. It exerts a substantial effect on atmospheric oxidative capacity. Apportioning acetone sources is complicated as acetone is emitted into the atmosphere from both natural and anthropogenic sources. Natural sources include direct emissions from vegetation, decaying organic material and secondary production by the oxidation of biogenic hydrocarbons (Singh et al, 1994; Jacob et al, 2002). Anthropogenic sources are vehicular emissions, solvent use and secondary production by the oxidation of man-made hydrocarbons (Singh et al, 1994; Jacob et al, 2002). Biomass burning is found to emit acetone (Singh et al, 1994), whereas the role of the ocean was considered for the first time by de Laat et al (2001) and
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