Historically, it has been an analytical challenge to detect and identify the organic components present in ice cores, due to the low abundance of organic carbon.  In order to detect and characterize the small amounts of organic matter in ice cores, advanced analytical instrumentation is required.  Here we utilize ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS), coupled with electrospray ionization, to identify the molecular formulas and compound classes of organic matter in both modern and ancient ice core and glacial samples from Wyoming, Greenland, and Antarctica.  A suite of 21 ice core samples were analyzed and thousands of distinct molecular species were identified in each sample, providing clues to the nature and sources of organic matter in these regions.  An additional suite of surface snow samples from Barrow, Alaska were analyzed using both FTICR-MS and proton NMR spectroscopy.  In all samples, we identify compounds belonging to major biochemical classes, such as lignin, tannins, carbohydrates, proteins, lipids, unsaturated hydrocarbons, and condensed aromatics.  The relative abundance of these species vary with age and sample location, and provide clues to the sources and post-depositional processing (e.g., photo-oxidation) of the organic matter.  Analysis of the samples shows functional group patterns in modern samples that are indicative of atmospheric processing of organic carbon (e.g., potential sources of organic matter from the deposition of aerosols).  Principal component analysis shows that various geographical locations are enriched in different compound classes, indicating potential differences in the major sources of organic matter to these locations.  Use of these advanced analytical techniques, capable of characterizing the low concentration organic matter present at an unprecedented level of detail, now presents us with the opportunity to expand the wealth of knowledge that ice cores could provide for the glaciology, atmospheric, and climate communities.

Characterization of organic matter in ice cores from North America, Greenland, and Antarctica using ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry

248th National Meeting (2014)

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