Journal
ENVIRONMENTAL SCIENCE & TECHNOLOGY
Volume 52, Issue 5, Pages 2538-2548Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.est.7b05513
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- National Science Foundation [ANT 1203885, OCE 1333157, OCE 1464396, PLR 1500169, DMR 11-57490]
- U.S. Geological Survey National Stream Quality Accounting Network
- U.S. Geological Survey National Research Program
- Fond de Recherche du Quebec - Nature et Technologies
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The link between composition and reactivity of dissolved organic matter (DOM) is central to understanding the role aquatic systems play in the global carbon cycle; yet, unifying concepts driving molecular composition have yet to be established. We characterized 37 DOM isolates from diverse aquatic ecosystems, including their stable and radiocarbon isotopes (delta C-13-dissolved organic carbon (DOC) and Delta C-14-DOC), optical properties (absorbance and fluorescence), and molecular composition (ultrahigh resolution mass spectrometry). Isolates encompassed end-members of allochthonous and autochthonous DOM from sites across the United States, the Pacific Ocean, and Antarctic lakes. Modern Delta C-14-DOC and optical properties reflecting increased aromaticity, such as carbon specific UV absorbance at 254 nm (SUVA(254)), were directly related to polyphenolic and polycyclic aromatic compounds, whereas enriched delta C-13-DOC and optical properties reflecting autochthonous end-members were positively correlated to more aliphatic compounds. Furthermore, the two sets of autochthonous end-members (Pacific Ocean and Antarctic lakes) exhibited distinct molecular composition due to differences in extent of degradation. Across all sites and end-members studied, we find a consistent shift in composition with aging, highlighting the persistence of certain biomolecules concurrent with degradation time.
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