Distinguishing molecular characteristics of aerosol water soluble organic matter from the 2011 trans-North Atlantic US GEOTRACES cruise

• Published in: Atmospheric Chemistry and Physics
• Main Authors: A. S. Wozniak, A. S. Willoughby, S. C. Gurganus, P. G. Hatcher
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2014
• Subjects: Physics; QC1-999; Chemistry; QD1-999; North Atlantic
• Online Access: https://doi.org/10.5194/acp-14-8419-2014; https://doaj.org/article/ffd3ae0911314063b5cb0c02174625dd

The molecular characteristics of aerosol organic matter (OM) determines to a large extent its impacts on the atmospheric radiative budget and ecosystem function in terrestrial and aquatic environments, yet the OM molecular details of aerosols from different sources are not well established. Aerosol particulate samples with North American-influenced, North African-influenced, and marine (minimal recent continental influence) air mass back trajectories were collected as part of the 2011 trans-North Atlantic US GEOTRACES cruise and analyzed for their water soluble OM (WSOM) molecular characteristics using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. Principal component analysis (PCA) separated the samples into five groups defined by distinct molecular formula characteristics. An abundance of nitrogen containing compounds with molecular formulas consistent with amino acid derivatives defined the two samples comprising the primary marine group (henceforth referred to as Primary Marine), which suggest a primary marine biological source to their WSOM in spite of their North American-influenced air mass trajectories. A second group of samples (aged marine, henceforth referred to as Aged Marine) with marine air mass trajectories was characterized by an abundance of low O / C (0.15–0.45) sulfur containing compounds consistent with organosulfate compounds formed via secondary aging reactions in the atmosphere. Several samples having North American-influenced air mass trajectories formed another group again characterized by organosulfate and nitrooxyorganosulfate type compounds with higher O / C ratios (0.5–1.0) than the Aged Marine samples reflecting the combustion influence from the North American continent. All the samples with North African-influenced air mass trajectories were grouped together in the PCA and were characterized by a lack of heteroatom (N, S, P) containing molecular formulas covering a wide O / C range (0.15–0.90) reflecting the desert source of this WSOM. The two ...