Contribution of Biomass Burning to Ambient Particulate Polycyclic Aromatic Hydrocarbons at a Regional Background Site in East China

Biomass burning has a significant impact on regional air quality, public health, and climate change. It is an important source of particulate polycyclic aromatic hydrocarbons (PAHs), which make up a major class of toxic air pollutants. To estimate the contribution of biomass burning to ambient particulate PAH concentrations, 15 PAHs and three anhydrosugars (levoglucosan, galactosan, and mannosan) were analyzed in particulate samples collected at a background site in east China from August 2012 to August 2015. Higher concentrations of all species were observed in fall and winter. Indoor biofuel combustion in north China was considered to be the major contributor to the high concentrations of anhydrosugars in fall and winter, because there were few fires detected on a fire count map for this period. A tracer-based approach, using the ratio of PAHs to levoglucosan (PAHs/lev) in fresh biomass burning aerosols, was proposed and used to estimate the contribution of biomass burning to PAHs. The results showed that biomass burning contributed nearly 11% of the total particulate PAHs. The estimation of the contribution from biomass burning using PAHs/lev agreed well with the results obtained from an independent positive matrix factorization analysis.