Fulvic acid oxidation state detection using fluorescence spectroscopy.

TitleFulvic acid oxidation state detection using fluorescence spectroscopy.
Publication TypeJournal Article
Year of Publication2002
AuthorsKlapper L, McKnight DM, Fulton RJ, Blunt-Harris EL, Nevin KP, Lovley DR, Hatcher PG
JournalEnviron Sci Technol
Volume36
Issue14
Pagination3170-5
Date Published2002 Jul 15
ISSN0013-936X
KeywordsBenzopyrans, Environmental Monitoring, Iron, Oxidation-Reduction, Spectrometry, Fluorescence
Abstract

Humic substances are a heterogeneous class of moderate molecular weight, yellow-colored biomolecules present in all soils, sediments, and natural waters. Although humic substances are generally resistant to microbial degradation under anaerobic conditions, some microorganisms in soils and sediments can use quinone moieties in humic substances as electron acceptors. Laboratory experiments have shown that humic substances can act as electron shuttles in the microbial reduction of ferric iron. Field studies of electron shuttling processes have been constrained by the lack of methods to characterize the oxidation state of quinone moieties in humic substances at natural concentrations. All humic substances have fluorescent properties, and fluorescence spectroscopy can indicate differences in precursor organic source of humic substances. Here we show that the quinone moieties responsible for electron transfer reactions contribute significantly to the fluorescence of humic substances. Further we use fluorescence spectroscopy to elucidate the oxidation state of quinone moieties in humic substances at natural concentrations found in sediment interstitial waters.

Alternate JournalEnviron. Sci. Technol.
PubMed ID12141500