Article Stable hydrogen isotope ratios of n-alkanes in atmospheric aerosols from Okinawa, Japan

Molecular compositions of n-alkanes and their stable hydrogen isotope ratios (δD) were studied in atmospheric aerosols collected from Cape Hedo, Okinawa, Japan, to better understand the long-range atmospheric transport of organic aerosols from the Asian continent. The δD values of the C22 – C33 n-alkanes range from –201 to –115‰, being similar to those of typical fossil fuels and contemporary higher plant leaf waxes in Far East Asia. A correlation between the δD values and the carbon preference index (CPI) suggests that these n-alkanes originated from fossil fuel combustion residues and/or terrestrial higher plant waxes. The concentrations of fossil fuel-derived n-alkanes increased from mid-November 2009 to February 2010, which is consistent with the enhanced emission of coal-burning aerosols during the winter in China. δD values of the fossil fuel-derived n-alkanes (–174 ± 7‰) in the atmospheric aerosols from Okinawa are much lower (by up to 95‰) than those from Tokyo and Sapporo, Japan, suggesting that they are derived from multiple sources in East Asia and are delivered by complex transport processes