Comprehensive assessment of PM sub(2.5) physicochemical properties during the Southeast Asia dry season (southwest monsoon)

A comprehensive assessment of fine particulate matter (PM sub(2.5)) compositions during the Southeast Asia dry season is presented. Samples of PM sub(2.5) were collected between 24 June and 14 September 2014 using a high-volume sampler. Water-soluble ions, trace species, rare earth elements, and a range of elemental carbon (EC) and organic carbon were analyzed. The characterization and source apportionment of PM sub(2.5) were investigated. The results showed that the 24h PM sub(2.5) concentration ranged from 6.64 to 68.2 mu gm super(-3). Meteorological driving factors strongly governed the diurnal concentration of aerosol, while the traffic in the morning and evening rush hours coincided with higher levels of CO and NO sub(2). The correlation analysis for non sea-salt K super(+)-EC showed that EC is potentially associated with biomass burning events, while the formation of secondary organic carbon had a moderate association with motor vehicle emissions. Positive matrix factorization (PMF) version 5.0 identified the sources of PM sub(2.5): (i) biomass burning coupled with sea salt [I] (7%), (ii) aged sea salt and mixed industrial emissions (5%), (iii) road dust and fuel oil combustion (7%), (iv) coal-fired combustion (25%), (v) mineral dust (8%), (vi) secondary inorganic aerosol (SIA) coupled with F super(-) (15%), and (vii) motor vehicle emissions coupled with sea salt [II] (24%). Motor vehicle emissions, SIA, and coal-fired power plant are the predominant sources contributing to PM sub(2.5). The response of the potential source contribution function and Hybrid Single-Particle Lagrangian Integrated Trajectory backward trajectory model suggest that the outline of source regions were consistent to the sources by PMF 5.0. Key Points * Physical driving factors govern the concentration of PM sub(2.5) * Morning and evening rush hours coincide with enhanced levels of CO and NO sub(2) * EC is associated with biomass burning, while OC is mainly due to secondary sources