Seasonal variation and chemical characterization of PM2.5 in northwestern Philippines

The seasonal and chemical characteristic of fine particulate matter (PM2.5) was investigated in Burgos, Ilocos Norte, located at the northwestern edge of the Philippines. Each 24H-sample of fine aerosol was collected for two weeks every season. Fine particulate in the region shows strong seasonal variation in both concentration and composition. Highest mass concentration was seen during the boreal spring season with a mean mass concentration of 21.59 μg m-3, and lowest was in fall with a mean concentration of 8.44 μg m-3. Three-day wind back trajectory analysis of air mass reveals the influence of the North Western Pacific monsoon regimes on PM2.5 concentration. During southwest monsoon, sea salt is the dominant component of fine aerosols carried by moist air from the South China Sea. During northeast monsoon, on the other hand, both wind and receptor model (USEPA PMF) analysis showed that higher particulate concentration was due to the Long Range Transport (LRT) of anthropogenic emissions from the northern East Asia. Overall, sea salt and soil comprise 33 % of total PM2.5 concentration while local biomass burning makes up 33 %. LRT of industrial emission, solid waste burning and secondary sulfate from East Asia have a mean contribution of 34 % to the total fine particulate for the whole sampling period.