EXPLORING HOW CARBON SOURCE AND REACTIVITY AFFECT THE FATE OF NITRATE AT THE SEDIMENT-WATER INTERFACE
The sediment-water interface (SWI) is an important regulator of biogeochemical processes in streams. Carbon and nitrogen inputs from various terrestrial and aquatic sources influence the function of this interface, however it is not known how carbon source composition and reactivity influence the export of denitrification products. We tested how porewater from the SWI of Augusta Creek, MI was processed when amended with four carbon types, a conservative bromide tracer, and a 15N-nitrate isotopic tracer in a series of SWI push-pull experiments. Leachates from the leaves of Elm and Tamarack trees, as well as from flocculated organic matter, and a solution of sodium acetate, were added in four sequential experiments. We hypothesized that uptake rates and denitrification products would scale with increasing carbon source reactivity. One set of triplicate porewater push-pull samplers was used to look at the degradation of dissolved organic carbon and nitrate concentrations at high temporal resolution (~10 min), while a second set of triplicates was sampled separately for dissolved di-nitrogen and nitrous oxide gasses. This study will contribute to our understanding of how seasonal or land-use dependent carbon dynamics could affect the function of SWIs.
Tyler Hampton (Primary Presenter/Author), Department of Earth and Environmental Sciences, Michigan State University, USA, firstname.lastname@example.org;
Jay Zarnetske (Co-Presenter/Co-Author), Department of Earth and Environmental Sciences, Michigan State University, USA, email@example.com;
Joseph Lee-Cullin (Co-Presenter/Co-Author), Department of Earth and Environmental Sciences, Michigan State University, USA, firstname.lastname@example.org;
Rachel Geiger (Co-Presenter/Co-Author), College of the Environment, Western Washington University, WA, USA, email@example.com;