RESTORATION INSIGHTS: EVALUATING RIVER HEALTH THROUGH DISSOLVED ORGANIC CARBON COMPOSITION DYNAMICS

Most of the world’s rivers have been substantially modified by human activities. A notable example is the Upper Clark Fork River (UCFR) in western Montana, USA, where historic mining and floods have resulted in the largest U.S. Environmental Protection Agency superfund site. Ecological restoration in the UCFR and floodplains included the removal of metal-laden floodplain soils, reconnecting the floodplains to the main stem, and re-vegetation of over 70 km of river. Restoration activities were expected to recover “healthy” ecosystem signatures and shift biogeochemical processes. The river’s dissolved organic carbon (DOC) was measured qualitatively (by absorbance spectroscopy and 3D excitation-emission matrix fluorescence spectroscopy) and quantitatively (DOC concentrations). We analyzed the DOC data for changing amounts of terrestrial signatures to determine restoration effects on river health annually across five years (2017-2022). DOC composition varied seasonally and annually. These data were paired with UCFR hydrologic flow patterns (snow melt onset, spring runoff, and base flow) to understand how ecological regimes change across seasons and throughout the summer with increased biological activity. Aromatic DOC composition measured by absorbance was greater in the headwaters where more intense floodplain restoration efforts occurred. We anticipate an increase in allochthonous terrestrial DOC delivered to the river reflecting successful floodplain-to-river connectivity from restoration efforts.

Presentation Preference: Poster

Primary Presenter: Emily Coronado, University of North Texas (coronadoemily2020@gmail.com)

Authors:

Emily Coronado, University of North Texas  (emilycoronado2@my.unt.edu)

Arya Mohanan, University of North Texas  (aryamohanan@my.unt.edu)

James Junker, University of North Texas  (james.junker@unt.edu)

Juliana D'Andrilli, University of North Texas  (juliana.d'andrilli@unt.edu)