Microbial and photochemical processes affect chromophoric dissolved organic matter (CDOM) dynamics in the ocean. Some evidence suggests that dissolved nitrogen plays a role in CDOM formation, although this has received little systematic attention in marine ecosystems. Coastal seawater incubations were carried out in the presence of model dissolved organic nitrogen (DON: amino sugars and amino acids) and dissolved inorganic nitrogen (DIN) compounds to assess their role in biological and photochemical production of CDOM. For several of the dissolved N compounds, microbial processing resulted in a pulse of CDOM that was mainly labile, appearing and disappearing within 7 days. In contrast, a net loss of CDOM occurred when no N was added to the microbial incubations. The greatest net biological CDOM formation was found upon addition of amino sugars (formation of fluorescent, mostly labile CDOM) and tryptophan (formation of non-fluorescent, refractory CDOM). Photochemical formation of CDOM was only found with tryptophan, the one aromatic compound tested. This CDOM was highly fluorescent, with excitation-emission matrices (EEMs) resembling those of terrestrial, humic-like fluorophores. The heterogeneity in CDOM formation from this collection of labile N-containing compounds was surprising. These compounds are common components of biopolymers and humic substances in natural waters and likely to contribute to microbially- and photochemically-produced CDOM in coastal seawater. © 2006 Elsevier B.V. All rights reserved.
CITATION STYLE
Biers, E. J., Zepp, R. G., & Moran, M. A. (2007). The role of nitrogen in chromophoric and fluorescent dissolved organic matter formation. Marine Chemistry, 103(1–2), 46–60. https://doi.org/10.1016/j.marchem.2006.06.003
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