Spatiotemporal dynamics of nitrogen biogeochemistry in a - PowerPoint PPT Presentation

Spatiotemporal dynamics of nitrogen biogeochemistry in a wetland-stream sequence Patrick E. Hurley 1 H. Maurice Valett 1,3 Marc Peipoch 2 Benjamin P. Colman 1 1 2 3

Wetland-Stream Interactions Fluvial wetlands act as hot spots of biogeochemical activity - Wollheim et al. 2013 Wetlands play an important role in fluvial landscape nutrient budgets - Lottig et al. 2013 Streams transform significant N loads from their catchments - Koenig et al. 2017 Distinct nutrient process domains (NPD) are spatially discrete and temporally variable - Caldwell et al. 2015; Montgomery 1999

Investigating Wetland-Streams Q: How do biogeochemical processes change along a wetland-stream sequence? H: Linked aquatic ecosystems function as distinct nutrient process domains due to variation in both morphologic structure and hydrologic linkages to nutrient sources and sinks.

Lost Creek Dutchman Complex (LCDC) WWTP

Lentic, Wetland & Lotic Units

Longitudinal Shifts in Morphology Channel Bed Area (km 2 ) Whole Reach Bed Area (km 2 ) Wetlands (km 2 ) Open Water (km 2 ) Incision Ratio Reach

Longitudinal Shifts in Water Residence Time a Wetlands (km 2 ) Median Travel Time (hrs) b b b Incision Ratio Reach

Quantifying Groundwater Exchange Q gw = (Q down + Q out ) – (Q up + Q in ) MC1 outputs inputs Q up Q out Q in Q down MC2 net groundwater exchange Q gw

Groundwater Exchange Varies by Reach Whole Reach Bed Area (km 2 ) Q gw (L/sec) Date

Ground vs. Surface Water Ground water Surface water NO 3 -N NH 4 -N

Quantifying Material Delivery: Nutrient Loads L = Q * [nutrient] ∆ L = (L down + L out ) – (L up + L in ) total change outputs inputs in load Δ L = Δ L gw + Δ L bio Δ L due to Δ L due to biogeochemical groundwater processing exchange

Changes in Load: Groundwater and Biogeochemical Influences NO 3 -N NH 4 -N a¥ ab¥ ∆ L gw (kg/d) ab¥ a¥ b b b b a¥ ∆L bio (kg/d) ab¥ a¥ a ab¥ ab b¥ b Reach

U NO3 (mg N/m 2 /d) U NO3 > 0 = production U NO3 < 0 = removal

Comparative Rates Bernal et al. 2017 enhanced nitrification + ] [NH 4 + NH 4 availability

Lessons from a Wetland-Stream Q: How do biogeochemical processes change along a wetland-stream sequence? 1. Nutrient Process Domains differ between lentic, wetland, and lotic reaches 2. Hydrologic linkages to surface and subsurface nutrients drive the formation of spatially discrete, temporally variable NPDs 3. Arrangement of landscape (morphologic) units along a sequence influences character, magnitude, and fate of nutrient dynamics to downstream waters

Acknowledgements Project Partners: Field & Lab Techs: "This material is based upon work supported in part Doug Martin, MT NRDP Kim Bray by the National Science Foundation EPSCoR Jim Ford, MT NRDP Claire Utzman Cooperative Agreement OIA-1757351" Beau Downing, MT NRDP Fischer Young Tom Parker, Geum Consulting Kate Perkins Marisa Sowles, Geum Consulting Lauren Sullivan Heggelund Ranch Ash Micklewright Ueland Ranch Carly Andlauer Kelley Ranch Lambert Ranch