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Abundance and properties of dissolved organic matter in pore waters of a freshwater wetland
Author(s) -
Chin YuPing,
Traina Samuel J.,
Swank Cathleen R.,
Backhus Debera
Publication year - 1998
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.1998.43.6.1287
Subject(s) - dissolved organic carbon , chemistry , anoxic waters , dissolution , environmental chemistry , organic matter , total organic carbon , pore water pressure , sediment , carbon fibers , molar concentration , inorganic chemistry , geology , organic chemistry , materials science , paleontology , geotechnical engineering , composite number , composite material
The abundances, molecular weights, molar absorptivities, and polydispersities of sediment pore water dissolved organic matter (DOM) and ferrous iron, Fe(II), were measured from three sites within a freshwater wetland (Old Woman Creek) adjacent to Lake Erie. DOM concentrations (expressed as organic carbon) increased with depth. Number‐average molecular weight, weight‐average molecular weight, and molar absorptivities (at 280 nm) also increased with depth up to 5 cm and remained relatively constant below this depth. These properties are indicative of the respective changes in the size of the DOM constituents and the number of aromatic moieties present. Moreover, a strong correlation was observed between Fe(II) and DOM, which suggests that both constituents coaccumulate in these pore fluids, It is hypothesized that reductionof iron oxides coated with organic matter releases both DOM and Fe(II). Increases in the molecular weights and molar absorptivities of the DOM constituents suggest that the “sorbed” component released by iron oxide dissolution is composed of larger and more aromatic molecules. The molecular‐weight data also suggest that much of the refractory organic carbon in the interstitial waters comprises smaller‐than‐expected polymeric molecules. Thus, the release of the sorbed organic materials during the reductive dissolution of the oxide phases in anoxic sediments coupled with the selective preservation of refractory organic components may play an important role in both the DOM‐mediated fate of pollutants and the cycling of carbon in wetlands.