Chemical characteristics of dissolved organic matter in an oligotrophic subtropical wetland/estuary ecosystem, Everglades National Park (FCE), South Florida from December 2001 to January 2002

The objective of this study was to investigate in detail the molecular characteristics of DOM in a sub-tropical, oligotrophic aquatic environment, namely the Florida coastal Everglades, along a freshwater wetland, mangrove fringe to estuarine transect. For this purpose, surface waters from five sites along Taylor Slough ranging from freshwater marsh to mangrove ecotone environments, as well as three sites within the Florida Bay estuary were collected for analyses. Fluorescence properties of DOM were measured for a quick assessment of DOM quality. Ultrafiltered DOM samples (UDOM; less than 0.7 um, greater than 1000 Da) were concentrated and freeze dried for the determination of bulk C composition, lignin-phenol concentration, and neutral sugar composition. These molecular characteristics were investigated by 13C-NMR spectroscopy, TMAH thermochemolysis, and hydrolysis with trifluoroacetic acid (TFA), respectively. Furthermore, UDOM samples were classified by cluster analysis based on their pyrolysis products obtained via flash pyrolysis-GC/MS.