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| Titel |
Molecular characterization of water soluble organic nitrogen in marine rainwater by ultra-high resolution electrospray ionization mass spectrometry |
| VerfasserIn |
K. E. Altieri, M. G. Hastings, A. J. Peters, D. M. Sigman |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 12, no. 7 ; Nr. 12, no. 7 (2012-04-12), S.3557-3571 |
| Datensatznummer |
250011027
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| Publikation (Nr.) |
 copernicus.org/acp-12-3557-2012.pdf |
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| Zusammenfassung |
| Atmospheric water soluble organic nitrogen (WSON) is a subset of the complex
organic matter in aerosols and rainwater, which impacts cloud condensation
processes and aerosol chemical and optical properties and may play a
significant role in the biogeochemical cycle of N. However, its sources,
composition, connections to inorganic N, and variability are largely unknown.
Rainwater samples were collected on the island of Bermuda
(32.27° N, 64.87° W), which experiences both
anthropogenic and marine influenced air masses. Samples were analyzed by
ultra-high resolution electrospray ionization Fourier transform ion cyclotron
resonance mass spectrometry to chemically characterize the WSON. Elemental
compositions of 2281 N containing compounds were determined over the mass
range m/z+ 50 to 500. The five compound classes with the largest number
of elemental formulas identified, in order from the highest number of
formulas to the lowest, contained carbon, hydrogen, oxygen, and nitrogen
(CHON+), CHON compounds that contained sulfur (CHONS+), CHON compounds that
contained phosphorus (CHONP+), CHON compounds that contained both sulfur and
phosphorus (CHONSP+), and compounds that contained only carbon, hydrogen, and
nitrogen (CHN+). Compared to rainwater collected in the continental USA,
average O:C ratios of all N containing compound classes were lower in the
marine samples whereas double bond equivalent values were higher, suggesting
a reduced role of secondary formation mechanisms. Despite their prevalence in
continental rainwater, no organonitrates or nitrooxy-organosulfates were
detected, but there was an increased presence of organic S and organic P
containing compounds in the marine rainwater. Cluster analysis showed a clear
chemical distinction between samples collected during the cold season
(October to March) which have anthropogenic air mass origins and samples
collected during the warm season (April to September) with remote marine air
mass origins. This, in conjunction with patterns identified in van Krevelen
diagrams, suggests that the cold season WSON is a mixture of organic matter
with both marine and anthropogenic sources while in the warm season the WSON
appears to be dominated by marine sources. These findings indicate that,
although the concentrations and percent contribution of WSON to total N is
fairly consistent across diverse geographic regions, the chemical composition
of WSON varies strongly as a function of source region and atmospheric
environment. |
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