Related Subjects
 

Fluorescence spectroscopy reveals ubiquitous presence of oxidized and reduced quinones in dissolved organic matter

Author(s): Cory RM, McKnight DM

Abstract

Excitation−emission matrixes (EEMs) of 379 dissolved organic matter (DOM) samples from diverse aquatic environments were modeled by parallel factor analysis (PARAFAC). Thirteen components likely representing groups of similarly fluorescing moieties were found to explain the variation in this data set. Seven of the thirteen components were identified as quinone-like based on comparison of their excitation and emission spectra to spectra of model quinones. These quinone-like fluorophores were found to vary in redox state and degree of conjugation. Two components were identified as amino acid-like based on comparison to tyrosine and tryptophan fluorescence spectra. The other four components are not yet associated with any class of molecules. The quinone-like fluorophores account for about 50% of the fluorescence for every sample analyzed, showing that quinone-like fluorophores are an important and ubiquitous fluorescing moiety and in natural waters. Further, the distribution of the quinone-like fluorophores was evaluated as a function of environmental and laboratory redox gradients. Under reducing conditions, the contribution of the reduced quinone-like fluorophores increased concurrent with a decrease in the oxidized quinone-like fluorophores, indicating that DOM fluorescence is a function of redox state of quinone-like moieties. Lastly, a ratio of two quinone-like fluorophores was found to explain the variation in the fluorescence index. These results provide new insight into the redox reactivity of DOM and have implications for the application of fluorescence spectroscopy as a tool to characterize DOM.

Similar Articles

Estimating global "blue carbon" emissions from conversion and degradation of vegetated coastal ecosystems

Author(s): Pendleton L, Donato DC, Murray BC, Crooks S, Jenkins WA, et al.

Major role of marine vegetation on the oceanic carbon cycle

Author(s): Duarte CM, Middelburg JJ, Caraco N

Seagrass community metabolism: Assessing the carbon sink capacity of seagrass meadows

Author(s): Duarte CM, Marbà N, Gacia E, Fourqurean JW, Beggins J, et al.

Seagrass sediments as a global carbon sink: Isotopic constraints

Author(s): Kennedy H, Beggins J, Duarte CM, Fourqurean JW, Holmer M, et al.

Distribution of Terrestrially Derived Dissolved Organic Matter on the Southeastern U

Author(s): Moran MA, Pomeroy LR, Sheppard ES, Atkinson LP, Hodson RE

Fluorescence spectroscopy and multi-way techniques

Author(s): Murphy KR, Stedmon CA, Graeber D, Bro R

Limnol Oceanography 50: 686-697

Author(s): Stedmon CA, Markager S  (2005a) Resolving the variability in dissolved organic matter fluorescence in a temperate estuary and its catchment using PARAFAC analysis

Limnol Oceanography 50: 1415-1426

Author(s): Stedmon CA, Markager S (2005b) Tracing the production and degradation of autochthonous fractions of dissolved organic matter by fluorescence analysis