Chemical characteristics of dissolved organic matter in an oligotrophic subtropical wetland/estuarine ecosystem

Authors

Nagamitsu Maie, Southeast Environmental Research Center and Department of Chemistry, Florida International UniversityFollow
Chengyong Yang, Southeast Environmental Research Center and Department of Chemistry, Florida International UniversityFollow
Toshikazu Miyoshi, Research Center of Macromolecular Technology, National Institute of Advanced Industrial Science and TechnologyFollow
Kathleen Parish, Southeast Environmental Research Center and Department of Chemistry, Florida International UniversityFollow
Rudolf Jaffe´, Southeast Environmental Research Center and Department of Chemistry and Biochemistry, Florida International UniversityFollow

Abstract

Fluorescence properties of whole water samples and molecular characteristics of ultrafiltrated dissolved organic matter (UDOM > 1,000 D) such as lignin phenol and neutral sugar compositions and ¹³C nuclear magnetic resonance (NMR) spectra were determined along a freshwater to marine gradient in Everglades National Park. Furthermore, UDOM samples were categorized by hierarchical cluster analysis based on their pyrolysis gas chromatography/mass spectrometry products. Fluorescence properties suggest that autochthonous DOM leached/exuded from biomass is quantitatively important in this system. ¹³C NMR spectra showed that UDOM from the oligotrophic Taylor Slough (TS) and Florida Bay (FB) ecosystems has low aromatic C (13% ± 3% for TS; 2% ± 2% for FB) and very high O-alkyl C (54% ± 4% for TS; 75% ± 4% for FB) concentrations. High O-alkyl C concentrations in FB suggest seagrass/phytoplankton communities as dominant sources of UDOM. The amount of neutral sugars was not appreciably different between the TS and FB sites (115 ± 12 mg C g C^-1 UDOM) but their concentrations suggest a low level of diagenesis and high production rates of this material in this oligotrophic environment. Total yield of lignin phenols (vanillyl + syringyl phenols) in TS was low (0.20–0.39 mg 100 mg C^-1 UDOM) compared with other riverine environments and even lower in FB (0.04–0.07 mg 100 mg C^-1 UDOM) and could be a result of photodegradation and/or dilution by other utochthonous DOM. The high O-alkyl and low aromatic nature of this UDOM suggests significant biogenic inputs (as compared with soils) and limited bioavailability in this ecosystem.

Comments

This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DBI-0620409 and #DEB-9910514. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Recommended Citation

Maie, N., C. Yang, T. Miyoshi, K. Parish, R. Jaffe. 2005. Chemical characteristics of dissolved organic matter in an oligotrophic subtropical wetland/estuarine ecosystem. Limnology and Oceanography 50(1): 23-35.