Emission factors of ultrafine particulate matter (PM<0.1 μm) and particle-bound polycyclic aromatic hydrocarbons from biomass combustion for source apportionment.

Data for source apportionment estimation was obtained from combustion of 11 types of biomass (rubber wood, palm kernel, palm fiber, sugarcane bagasse, sugarcane leaves, maize residue, rice stubble, rice straw, Xylocarpus moluccensis, Avicennia alba Blume and Rhizophora mucronata) and bituminous coal. Combustion was carried out in a tube furnace and emitted particulate matter (PM) was collected using a nanosampler that segregated particle sizes down to 0.1 μm. Emission factors of PM < 0.1 μm were in the range of 0.11-0.28 g kg (∼1-8% of total PM), except in the case of Rhizophora mucronata, which had an emission factor of 0.071 ± 0.004 g kg (∼18% of total PM). The dominant polycyclic aromatic hydrocarbons (PAHs) found on PM < 0.1 μm were chrysene from combustion of rubber wood, palm kernel, palm fiber, maize residue, Xylocarpus moluccensis, Avicennia alba Blume, Rhizophora mucronata and bituminous coal; benzo[b]fluoranthene from combustion of rice straw, sugarcane bagasse and sugarcane leaves; and benzo[k]fluoranthene from rice stubble combustion. The emission factors of PAHs bound to PM < 0.1 μm from biomass combustion ranged from 0.005 to 0.044 mg kg and the emission factor from bituminous coal combustion was 0.1411 ± 0.0004 mg kg. The carcinogenic potency equivalent or benzo[a]pyrene equivalent was highest from bituminous coal combustion (0.1252 mg kg) and between 0.0019 and 0.0192 mg kg from biomass combustion. However, emission factors of both PM and particle-bound PAHs from biomass combustion were affected by moisture content of biomass and moisture contents of biomass used in this study were quite low, ranging from 0.165 to 0.863%.