THESIS
2016
xix, 89 pages : illustrations (some color) ; 30 cm
Abstract
Non-refractory submicron aerosol (NR-PM
1) was characterized using an Aerosol Chemical
Speciation Monitor (ACSM) in one year from September 2013 to August 2014 at the roadside in
an Asian megacity environment in Hong Kong. Organic aerosol (OA), characterized by application
of Positive Matrix Factorization (PMF), and sulfate were found dominant for each season. The
detailed analysis of organic aerosol (OA) during fall and winter showed that traffic-related organic
aerosol correlated well with other vehicle-related species, and cooking aerosol displayed clear
meal-time concentration maxima and association with surface winds from restaurant areas. Semi-volatile
oxygenated OA (SV-OOA) mass concentration was variably correlated with hydrocarbon-hydrocarbon-like OA (HOA), cooking OA (CO...[
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Non-refractory submicron aerosol (NR-PM
1) was characterized using an Aerosol Chemical
Speciation Monitor (ACSM) in one year from September 2013 to August 2014 at the roadside in
an Asian megacity environment in Hong Kong. Organic aerosol (OA), characterized by application
of Positive Matrix Factorization (PMF), and sulfate were found dominant for each season. The
detailed analysis of organic aerosol (OA) during fall and winter showed that traffic-related organic
aerosol correlated well with other vehicle-related species, and cooking aerosol displayed clear
meal-time concentration maxima and association with surface winds from restaurant areas. Semi-volatile
oxygenated OA (SV-OOA) mass concentration was variably correlated with hydrocarbon-hydrocarbon-like OA (HOA), cooking OA (COA) and low-volatile oxygenated OA (LV-OOA)
under different conditions and period of a day. Secondary aerosols are responsible for high day-to-day episodic haze events. The episodes frequently occurred though out the one year covering
137 days, with the dominance of continental transport episodes (CTs; ~45%) concentrated on fall
and winter, to a lesser extent land-sea-breeze episodes (LSBs) and typhoon-related episodes
accounting for 16% and 13% respectively. Significant increase of the contribution from secondary
aerosol (SA) was observed in CTs relative to their adjacent non-haze periods, from about 70% to
80% of total NR-PM
1 concentration. The NR-PM
1 during LSBs also increased significantly and
this increase came from nearly all components due to effective accumulation under a land-sea-breeze
circulatory conditions. In addition, both CTs and LSBs showed increasing fractions from
SV-OOA and nitrate, while these fractional increases were associated with transported input from
outside of Hong Kong in CTs but local formation and their circulatory accumulation in LSBs. The
mass increase in typhoon-related episode was mainly driven by the increase in SA, especially LV-OOA
and sulfate. This obvious increase in SA was caused by the intensive local formation,
accumulation and the air subsidence.
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