Levoglucosan enhancement in ambient aerosol during springtime transport events of biomass burning smoke to Southeast China

An intensive field experiment was conducted at an urban and a rural site in Hong Kong to identify the influence of biomass burning emissions transported from distinct regions on ambient aerosol in coastal southeast China. Watersoluble ionic and carbonaceous species, specifically the biomass burning tracer levoglucosan, were analysed. Elevated levoglucosan concentrations with maxima of 91.5 and 133.7 ng m^-3 and overall average concentrations of 30 and 36 ng m^-3 were observed at the rural and urban sites, respectively. By combining the analysed meteorological data, backward trajectories, fire counts and Aerosol Index from the Earth Probe satellite, southwest China and the northern Philippines, together with the southeast China coast, were identified for the first time as source regions of the transported biomass burning particles at the surface level in rural Hong Kong. Occasional levoglucosan enhancements observed at urban Hong Kong were attributed to local incense and joss paper burning during the Ching-Ming festival period. The contributions of transported biomass burning emissions, especially from the northern Philippines, were estimated to account for 7.5% and 2.9% of OC and PM_2.5, respectively.