Ice core record of fatty acids over the past 450 years in Greenland

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Abstract
Fatty acids have been studied in the ice core taken from Site‐J, Greenland using a capillary gas chromatography and mass spectrometry. Their molecular distributions showed a strong even/odd carbon number predominance with two maxima at C16 and C24 or C22 acids. Unsaturated fatty acids such as oleic acid (C18∶1) were also detected in the ice samples as major species, being in contrast to the remote marine aerosols in which unsaturated fatty acids are depleted by photochemical degradation. This suggests that organic aerosols derived from marine and terrestrial biological sources are transported long distances in the atmosphere over the south Greenland ice sheet without serious photochemical transformation. Total concentrations of fatty acids were relatively constant (ca. 10 µg/kg‐ice) in the 16th to 19th centuries, however, they significantly increased in the 20th century with maxima in the 1930s–1950s and 1980s (up to ca. 100 µg/kg‐ice), suggesting an enhanced sea‐to‐air emission of organic matter and subsequent transport over the Greenland. The increased concentrations of fatty acids in this century were found to be consistent with an increased arctic temperature. During warmer periods, atmospheric circulation is enhanced and more lipids which are enriched in the sea surface microlayers are emitted to the atmosphere by bubble bursting mechanisms and imprinted in the ice core of south Greenland.