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Chemical characteristics of dissolved organic matter in an oligotrophic subtropical wetland/estuarine
Author(s) -
Maie Nagamitsu,
Yang Chengyong,
Miyoshi Toshikazu,
Parish Kathleen,
Jaffé Rudolf
Publication year - 2005
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.2005.50.1.0023
Subject(s) - environmental chemistry , chemistry , organic matter , dissolved organic carbon , lignin , organic chemistry
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 13 C 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. 13 C 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.