Compound specific radiocarbon and δ13C measurements of fatty acids in a continental aerosol sample

Compound-specific radiocarbon analysis of individual fatty acids was conducted for a semi-urban aerosol sample using preparative capillary gas chromatography (PCGC) system and accelerator mass spectrometry (AMS). The aerosol fatty acids (C-16 to C-34) showed a typical bimodal distribution with two maxima at C-16 and C-26. Their carbon isotopic compositions ranged from -30.3 parts per thousand (C-26) to -23.3 parts per thousand (C-18), suggesting that they are derived from terrestrial higher plants and marine sources. Radiocarbon measurements of C-16-C-22 fatty acids showed modem C-14 ages, suggesting that the acids are emitted from living higher plants and possibly from marine organisms. On the other hand, C-24-C-26 fatty acids that are characteristic to terrestrial plant waxes showed C-14 ages of 5860 (+/- 200) years. This suggests that some portion of higher molecular weight fatty acids have been stored in geochemical reservoirs such as soils at least for hundreds to thousands of years and then emitted to the atmosphere. These aged fatty acids could be in part transported long distances from the Asian continent through the atmosphere.