Abstract
Low molecular weight dicarboxylic acids are abundant in atmospheric aerosols in continental, marine and polar reions. They are water-soluble and thus can act as cloud condensation nuclei, playing an important role in radiative forcing of the Earth and also in water cycle. Here, we studied dicarboxylic acids in the marine aerosols (n=32) from the Pacific (34°N-14°S, 140°E-150°W) for their stable carbon isotopic ratios using a capillary GC/isotope ratios mass spectrometer (GC/irMS) after dibutyl ester derivatization. We found a significant diversity of δ13C values for C2-C9 saturated and some unsaturated diacids as follows: oxalic acid (av. +10.3 ‰), malonic (-7.3 ‰), succinic (-17.6 ‰), glutaric (?23.0 ‰), adipic (?16.0 ‰), pimelic (- 22.1 ‰), suberic (-16.3 ‰), azelaic (-22.4 ‰), fumaric (-17.2 ‰), and phthalic (-22.2 ‰) acids. Heaviest δ13C values were obtained for C2 and C3 diacids especially over the tropical Pacific, suggesting an isotopic enrichment possibly caused by photochemical processes.
