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Powers, L.C.* ; Hertkorn, N. ; McDonald, N.* ; Schmitt-Kopplin, P. ; Del Vecchio, R.* ; Blough, N.V.* ; Gonsior, M.*

Sargassum sp. act as a large regional source of marine dissolved organic carbon and polyphenols.

Global Biogeochem. Cycles 33, 1423-1439 (2019)
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Free by publisher: Verlagsversion online verfügbar 12/2021
Dissolved organic carbon (DOC) plays critical roles in marine carbon cycling, but its sources and sinks remain uncertain. In this study, we monitored DOC exudation rates of Sargassum natans under visible light (lambda > 390 nm) and solar radiation. DOC release rates ranged from 7 to 10 mu g C g(biomass)(-1) hr(-1) (wet weight) under visible light, but increased to 23 to 41 mu g C g(biomass)(-1) hr(-1) when exposed to natural sunlight. Results indicate that DOC released by Sargassum could amount to 0.3 to 1.2 Tg C/year, potentially contributing significantly to the marine DOC pool in the Gulf of Mexico and Western North Atlantic. We employed the Folin-Ciocalteu phenolic content method, nuclear magnetic resonance (NMR) spectroscopy, and ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to characterize the diverse pool of organic compounds exuded from Sargassum. Results from these complementary methods showed that Sargassum release large quantities of phlorotannins, a class of polyphenols that have very similar properties to terrestrial DOC. These phlorotannins and their oxygenated phenolic derivatives exhibit a high hydrogen deficiency and functionalization (i.e., 4 to 6 oxygen atoms per aromatic ring), representing 5 to 18% of the released DOC isolated by solid phase extraction. Thus, Sargassum is the largest biological source of open ocean polyphenols recorded to date. The amount of polyphenolic DOC released by Sargassum challenges previous beliefs that all polyphenols found within the oceans are remnants of terrestrial organic matter, although the stability of phlorotannins and their derivatives needs to be further evaluated.
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Publikationstyp Artikel: Journalartikel
Dokumenttyp Wissenschaftlicher Artikel
Schlagwörter Sargassum ; Marine Dissolved Organic Matter ; Marine Polyphenols ; Doc ; Nmr ; Ft-icr Ms; Solid-phase Extraction; Molecular Formula Assignment; Resolution Mass Data; Matter Cdom; Optical-properties; Pelagic Sargassum; Phenolic Substances; Fulvic-acids; Brown Alga; Spectrometry
ISSN (print) / ISBN 0886-6236
e-ISSN 1944-9224
Quellenangaben Band: 33, Heft: 1, Seiten: 1423-1439 Artikelnummer: , Supplement: ,
Verlag Wiley
Verlagsort 2000 Florida Ave Nw, Washington, Dc 20009 Usa
Begutachtungsstatus Peer reviewed