Characterization of Hydrocarbon Compounds in Liquefied PM1 Aerosol Using Particle into Liquid System (PILS) Collected from the ARM Southern Great Plains Site of USA

The hydrocarbon composition of liquefied PM1 aerosol samples collected using the particle into liquid system (PILS) at the Atmospheric Radiation Measurement (ARM) site of the Southern Great Plains (SGP) of the USA was analyzed in terms of organic compound composition. The results indicate that anthropogenic aliphatic compounds contributed significantly to the organic pool of PM1 fine aerosols in the ambient air of the rural area of the Southern Great Plains, with a broad range of aliphatic hydrocarbons (HCs) being the dominant organic component. The molecular markers of hopanes and steranes were generally absent or present in trace amounts in most samples, but a significant number of low-abundance hopanes and steranes were detected in only two samples, while the aromatic compounds were generally insignificant and comprised mainly low molecular weight naphthalene and its methylated derivatives. The overall composition of organic compounds and the back trajectories analysis for the sampling days suggest that the local petroleum refinery and vehicular emissions are the two major sources of the aliphatic and aromatic compounds in the fine aerosols, while plant wax may occasionally contribute a minor portion of organic matter. Furthermore, it was found that the organic composition of PM1 fine aerosol was clearly related to the ambient air temperature and suggests that the temperature is a controlling factor of organic aerosol formation.