Identification of possible source markers in marine dissolved organic matter using ultrahigh resolution mass spectrometry
Date
2009-04-30Author
Kujawinski, Elizabeth B.
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Longnecker, Krista
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Blough, Neil V.
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Del Vecchio, Rossana
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Finlay, Liam
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Kitner, Joshua B.
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Giovannoni, Stephen J.
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https://hdl.handle.net/1912/2897As published
https://doi.org/10.1016/j.gca.2009.04.033Abstract
Marine dissolved organic matter (DOM) is one of the most heterogeneous and largest pools of
reactive carbon on earth, rivaling in mass the carbon in atmospheric carbon dioxide.
Nevertheless, the molecular-level composition of marine DOM has eluded detailed description,
impeding inquiry into the specific mechanisms that add or remove compounds from the DOM
pool. Here we describe the molecular-level composition of C18-extracted DOM along an east-west
transect of the North Atlantic Ocean. We examine the changes in DOM composition along
this transect with ultrahigh resolution mass spectrometry and multivariate statistics. We use
indicator species analysis (ISA) to identify possible source markers for photochemical degradation and heterotrophic bacterial metabolism. The inclusion of ISA in statistical evaluation
of DOM mass spectral data allows investigators to determine the m/z values associated with
significant changes in DOM composition. With this technique, we observe indicator m/z values
in estuarine water that may represent components of terrestrially-derived chromophoric DOM
subject to photo-chemical degradation. We also observe a unique set of m/z values in surface
seawater and show that many of these are present in pure cultures of the marine α-proteobacterium Candidatus Pelagibacter ubique when grown in natural seawater. These
findings indicate that a complex balance of abiotic and biotic processes controls the molecular
composition of marine DOM to produce signatures that are characteristic of different
environments.
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Author Posting. © Elsevier B.V., 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 73 (2009): 4384-4399, doi:10.1016/j.gca.2009.04.033.