Chemical composition of aquatic dissolved organic matter in five boreal forest catchments sampled in spring and fall seasons

Marc Schumacher, Iso Christl*, Rolf D. Vogt, Kurt Barmettler, Chris Jacobsen, Ruben Kretzschmar

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

The chemical composition and carbon isotope signature of aquatic dissolved organic matter (DOM) in five boreal forest catchments in Scandinavia were investigated. The DOM was isolated during spring and fall seasons using a reverse osmosis technique. The DOM samples were analyzed by elemental analysis, FT-IR, solid-state CP-MAS 13C-NMR, and C-1s NEXAFS spectroscopy. In addition, the relative abundance of carbon isotopes (12C, 13C, 14C) in the samples was measured. There were no significant differences in the chemical composition or carbon isotope signature of the DOM sampled in spring and fall seasons. Also, differences in DOM composition between the five catchments were minor. Compared to reference peat fulvic and humic acids, all DOM samples were richer in O-alkyl carbon and contained less aromatic and phenolic carbon, as shown by FT-IR, 13C-NMR, and C-1s NEXAFS spectroscopy. The DOM was clearly enriched in 14C relative to the NBS oxalic acid standard of 1950, indicating that the aquatic DOM contained considerable amounts of organic carbon younger than about 50 years. The weight-based C:N ratios of 31 ± 6 and the δ13C values of -29±2‰ indicate that the isolated DOM is of terrestrial rather than aquatic origin. We conclude that young, hydrophilic carbon compounds of terrestrial origin are predominant in the samples investigated, and that the composition of the aquatic DOM in the studied boreal forest catchments is rather stable during low to intermediate flow conditions.

Original languageEnglish (US)
Pages (from-to)263-275
Number of pages13
JournalBiogeochemistry
Volume80
Issue number3
DOIs
StatePublished - Sep 2006

Keywords

  • Boreal forest catchment
  • Carbon isotopes
  • Dissolved organic matter
  • Flow condition
  • Reverse osmosis
  • Spectroscopy

ASJC Scopus subject areas

  • Environmental Chemistry
  • Water Science and Technology
  • Earth-Surface Processes

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