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Fluorescence-based proxies for lignin in freshwater dissolved organic matter

Journal of Geophysical Research G: Biogeosciences

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Abstract

Lignin phenols have proven to be powerful biomarkers in environmental studies; however, the complexity of lignin analysis limits the number of samples and thus spatial and temporal resolution in any given study. In contrast, spectrophotometric characterization of dissolved organic matter (DOM) is rapid, noninvasive, relatively inexpensive, requires small sample volumes, and can even be measured in situ to capture fine-scale temporal and spatial detail of DOM cycling. Here we present a series of cross-validated Partial Least Squares models that use fluorescence properties of DOM to explain up to 91% of lignin compositional and concentration variability in samples collected seasonally over 2 years in the Sacramento River/San Joaquin River Delta in California, United States. These models were subsequently used to predict lignin composition and concentration from fluorescence measurements collected during a diurnal study in the San Joaquin River. While modeled lignin composition remained largely unchanged over the diurnal cycle, changes in modeled lignin concentrations were much greater than expected and indicate that the sensitivity of fluorescence-based proxies for lignin may prove invaluable as a tool for selecting the most informative samples for detailed lignin characterization. With adequate calibration, similar models could be used to significantly expand our ability to study sources and processing of DOM in complex surface water systems.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Fluorescence-based proxies for lignin in freshwater dissolved organic matter
Series title:
Journal of Geophysical Research G: Biogeosciences
Volume
114
Year Published:
2009
Language:
English
Publisher:
American Geophysical Union
Publisher location:
Washington, D.C.
Contributing office(s):
California Water Science Center
Description:
10 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
G00F03
Last page:
G00F03