Dissolved organic matter transport reflects hillslope to stream connectivity during snowmelt in a montane catchment

Margaret A. Burns, Holly R. Barnard, Rachel S. Gabor, Diane M. McKnight, Paul D. Brooks

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Dissolved organic matter (DOM) transport is a key biogeochemical linkage across the terrestrial-aquatic interface in headwater catchments, and quantifying the biological and hydrological controls on DOM composition provides insight into DOM cycling at the catchment scale. We evaluated the mobility of DOM components during snowmelt in a montane, semiarid catchment. DOM composition was evaluated on a near-daily basis within the soil and the stream during snowmelt, and was compared to groundwater samples using a site-specific parallel factor analysis (PARAFAC) model derived from soil extracts. The fluorescent component loadings in the interstitial soil water and in the groundwater were significantly different and did not temporally change during snowmelt. In the stream, a transition occurred during snowmelt from fluorescent DOM with higher contributions of amino acid-like components indicative of groundwater to higher humic-like contributions indicative of soil water. Furthermore, we identified a humic-like fluorescent component in the soil water and the stream that is typically only observed in extracted water soluble organic matter from soil which may suggest hillslope to stream connectivity over very short time scales. Qualitative interpretations of changes in stream fluorescent DOM were supported by two end-member mixing analyses of conservative tracers. After normalizing fluorescent DOM loadings for dissolved organic carbon (DOC) concentration, we found that the peak in DOC concentration in the stream was driven by the nonfluorescent fraction of DOM. This study demonstrated how PARAFAC analysis can be used to refine our conceptual models of runoff generation sources, as well as provide a more detailed understanding of stream chemistry dynamics.

Original languageEnglish (US)
Pages (from-to)4905-4923
Number of pages19
JournalWater Resources Research
Volume52
Issue number6
DOIs
StatePublished - Jun 1 2016
Externally publishedYes

Keywords

  • PARAFAC
  • dissolved organic matter
  • ecohydrology
  • fluorescence
  • montane
  • snowmelt

ASJC Scopus subject areas

  • Water Science and Technology

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