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Riverine dissolved organic matter transformations increase with watershed area, water residence time, and Damköhler numbers in nested watersheds
  • +4
  • Kevin A. Ryan,
  • Vanessa A Garayburu-Caruso,
  • Byron C Crump,
  • Ted Bambakidis,
  • Peter A Raymond,
  • Shaoda Liu,
  • James C Stegen
Kevin A. Ryan
U.S. Geological Survey New York Water Science Center

Corresponding Author:[email protected]

Author Profile
Vanessa A Garayburu-Caruso
Pacific Northwest National Laboratory
Byron C Crump
Oregon State University
Ted Bambakidis
Oregon State University
Peter A Raymond
Yale University
Shaoda Liu
School of Environment, Beijing Normal University
James C Stegen
Washington State University, Pacific Northwest National Laboratory


Quantifying the relative influence of factors and processes controlling riverine ecosystem function is essential to predicting future conditions under global change. Dissolved organic matter (DOM) is a fundamental component of riverine ecosystems that fuels microbial food webs, influences nutrient and light availability, and represents a significant carbon flux globally. The heterogeneous nature of DOM molecular composition and its propensity for interaction (i.e., functional diversity) can characterize riverine ecosystem function across spatiotemporal scales. To investigate fundamental drivers of DOM diversity, we collected seasonal water samples from 42 nested locations within five watersheds spanning multiple watershed sizes (~5 to 30,000 km2) across the United States. Patterns in DOM molecular diversity and putative biochemical transformations derived from high-resolution mass spectrometry were assessed across gradients of explanatory variables associated with watershed characteristics (e.g., watershed area, water residence time, land cover). We found that putative biochemical transformations were more strongly related to explanatory variables across watersheds than common bulk DOM parameters and that watershed area, surface water residence time and derived Damköhler numbers representing DOM reactivity timescales were strong predictors of DOM diversity. The data also indicate that catchment-specific land cover factors can significantly influence DOM diversity in diverging directions. Overall, the results highlight the importance of considering water residence time and land cover when interpreting longitudinal patterns in DOM chemistry and the continued challenge of identifying generalizable drivers that are transferable across watershed and regional scales for application in Earth system models. This work also introduces a Findable Accessible Interoperable Reusable (FAIR) dataset (>300 samples) to the community for future syntheses.
26 Mar 2024Submitted to ESS Open Archive
28 Mar 2024Published in ESS Open Archive