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PATTERNS IN DISSOLVED ORGANIC MATTER CHARACTER PROVIDE PERSPECTIVE ON THE INTERCONNECTION AND FUNCTION OF WATERSHED ECOSYSTEMS

The movement of water connects watershed ecosystems linking uplands to floodplains and headwater streams to oceans. Dissolved organic matter (DOM) is a critical currency for material and energy exchange among these systems, as well as an indicator of processes that transform DOM character along the way. Hence, DOM character may trace hydrologic connectivity between ecosystems, and indicate function within ecosystems. We evaluated DOM composition fluorometrically (Excitation Emission Matrices; EEMs), and modeled variation in carbon quality with parallel factor (PARAFAC) analyses. We compiled eight DOM PARAFAC models representing common watershed components, including: precipitation, glacial snowpack/ice, agricultural soils, floodplain sediments, headwaters, and higher-order rivers. Recalcitrant DOM chemical species were dominant signatures of precipitation, headwaters, floodplains, soils, and rivers, and may provide a more conservative tracer of hydrologic connections (e.g., linking terrestrial and aquatic ecosystems). Labile DOM were ubiquitous, varying with source environment (e.g., glaciers and geothermally-fed streams), indicating primary production or local carbon processing dynamics. Taken together, classification of DOM character regimes across watersheds will lead to a scalable perspective on how whole-watershed function emerges from the integrated behavior of composite ecosystems.

Juliana D'Andrilli (Primary Presenter/Author), Montana State University, juliana@montana.edu;


James Junker ( Co-Presenter/Co-Author), Montana State University, james.junker1@gmail.com;


Robert Payn ( Co-Presenter/Co-Author), Montana State University, Montana Institute on Ecosystems, rpayn@montana.edu;


Meryl Storb ( Co-Presenter/Co-Author), Montana State University, meryl.storb@gmail.com;


H. Maurice Valett ( Co-Presenter/Co-Author), University of Montana, maury.valett@umontana.edu;


Marc Peipoch ( Co-Presenter/Co-Author), University of Montana, Division Biological Sciences, marc.peipoch@mso.umt.edu;


Brent Christner ( Co-Presenter/Co-Author), University of Florida, xner@ufl.edu;


Rachel Joyce ( Co-Presenter/Co-Author), University of Florida, rejoyce17@ufl.edu;


Rachel Kohn ( Co-Presenter/Co-Author), University of Florida, rkohn2@ufl.edu;


Eric Scholl ( Co-Presenter/Co-Author), Montana State University, escholl86@gmail.com ;


Richard Engel ( Co-Presenter/Co-Author), Montana State University, rengel@montana.edu;


Carlos Romero ( Co-Presenter/Co-Author), Montana State University, carlos.romero2@msu.montana.edu;