Characterization of n-alkanes in urban submicron aerosol particles (PM1)

Ambient particulate matter mass concentrations were measured in terms of PM1 and PM1−10 for 8 months in 2000–2001, at a sampling site in the urban city of Kaohsiung, Taiwan. On average for the 8-month samples, 52±20% of the PM10 was made up of PM1. The concentration of particulate n-alkanes was in the range of 75–265 ng m−3 in PM1 and 89–346 ng m−3 in PM10, considerably higher than the concentration levels measured at other urban areas. The mass content of n-alkanes in ambient submicron aerosol particles (PM1)(0.38%) was statistically higher than that in PM1−10 (0.13) and suggests that the n-alkanes exist mainly in PM1 in Kaohsiung city. The concentration ratio of the homologues (C19–C33) of alkanes indicated that homologues were associated with submicron particles in general and that there was a high level of fractions (0.87±0.09 for C19) in PM1 for low carbon n-alkanes than for high carbon n-alkanes (0.64±0.09 for C33). For all the collected samples in this study, the average and standard deviation of CPI (carbon preference index) was 1.26±0.17 for PM1 and 1.39±0.28 for PM1−10. The plant wax contributions to the total alkanes for PM1 and PM1−10 were estimated to be 13.4% (5.9–21.7%) and 17.1% (4.8–32.0%), respectively. These observed results suggest that the organic matter in the submicron aerosol particles (PM1) in Kaohsiung city contained compounds that were predominantly contributed by anthropogenic sources with only a minor contribution from biogenic sources.