Size distribution of n-alkanes and polycyclic aromatic hydrocarbons (PAHs) in urban and rural atmospheres of Guangzhou, China

n-Alkanes and polycyclic aromatic hydrocarbons (PAHs) were identified in particle-sized aerosols of the urban and rural atmospheres of Guangzhou, China. Most of the organic compounds were mainly associated with fine particles with aerodynamic diameters less than 1.5 μm in the urban and rural atmospheres. In the urban aerosol close to the road, about 57% of n-alkanes and 62% of PAHs were found in the particle fraction with diameters of <0.49 μm. Size distributions of particulate mass and low molecular weight organic compounds exhibited bimodal patterns, while high molecular weight organic compounds exhibited unimodal distribution. Mass mean diameter (MMD) of total n-alkanes calculated over the whole size range was 0.43 μm in urban and 0.83 μm in rural. A similar trend was observed for PAHs. MMD for total PAHs in the urban and rural aerosol was 0.40 and 0.69 μm, respectively.