Volume 16, No. 8, August 2016, Pages 1868-1878 PDF(1.09 MB)
Formaldehyde and Acetaldehyde at Different Elevations in Mountainous Areas in Hong Kong
Zhenhao Ling1,2, Hai Guo2, Gexiang Chen1, Sean Ho Min Lam3,4, Shaojia Fan1
1 School of Atmospheric Sciences, Sun Yat-sen University, Guangzhou, China
2 Air Quality Studies, Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kongs
3 School of Chemistry and Biochemistry, University of Western Australia, Perth, Western Australia, Australia
4 Pacific Environment Limited, Perth, Western Australia, Australia
- The concentrations of CH3CHO were higher at urban site than those at mountain site.
- The levels of HCHO were comparable at both sites.
- Higher daytime levels of HCHO and CH3CHO were observed.
- In-situ formation was the major contributor at urban site.
- HCHO and CH3CHO were related to background and in-situ formation at mountain site.
Intensive field measurements of formaldehyde (HCHO) and acetaldehyde (CH3CHO) were concurrently conducted at a mountain site (TMS) and an urban site (TW) at the foot of the same mountain in Hong Kong from September to November 2010. The spatiotemporal variations of HCHO and CH3CHO, the correlation between HCHO and CH3CHO and the ratios of HCHO/CH3CHO indicated different impacts of primary emissions and secondary formation at the two sites. The source apportionments of HCHO and CH3CHO at both sites were investigated using the Positive Matrix Factorization (PMF) model, while the in-situ formation of HCHO and CH3CHO was estimated using a Photochemical Box Model coupled with Master Chemical Mechanism (PBM-MCM). At TMS, the in-situ formation was the most significant contributor to ambient HCHO and CH3CHO, accounting for 51 ± 5 and 32 ± 2%, respectively, followed by the transport of photochemically-formed aldehydes, vehicular emissions, biogenic emissions, biomass burning and solvent usage. On the other hand, at TW, the in-situ formation and vehicular emissions explained 55 ± 7% and 18 ± 1% of ambient HCHO, respectively, while vehicular emissions and in-situ formation made comparable contributions to CH3CHO (~35%). The findings are helpful for the formulation and implementation of appropriate control strategies for aldehydes and their precursors in Hong Kong.
Source apportionment; HCHO; CH3CHO; Hong Kong.