Spatiotemporal dynamics of nitrogen biogeochemistry in a - - PowerPoint PPT Presentation

Spatiotemporal dynamics of nitrogen biogeochemistry in a wetland-stream sequence

Patrick E. Hurley1

• H. Maurice Valett1,3

Marc Peipoch2 Benjamin P. Colman1

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

Q: How do biogeochemical processes change along a wetland-stream sequence? Investigating Wetland-Streams 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

Whole Reach Bed Area (km2)

Wetlands (km2) Channel Bed Area (km2) Open Water (km2) Incision Ratio

Reach

Longitudinal Shifts in Water Residence Time

Wetlands (km2) Incision Ratio

Reach

Median Travel Time (hrs)

a b b b

Qgw = (Qdown + Qout) – (Qup + Qin)

Quantifying Groundwater Exchange

Qout Qin Qup Qdown Qgw

• utputs

inputs

net groundwater exchange

MC1 MC2

Groundwater Exchange Varies by Reach

Whole Reach Bed Area (km2)

Qgw (L/sec)

Date

Ground vs. Surface Water

Ground water Surface water NO3-N NH4-N

ΔL = ΔLgw + ΔLbio ∆L = (Ldown + Lout) – (Lup + Lin) L = Q * [nutrient]

Quantifying Material Delivery: Nutrient Loads

• utputs

inputs

ΔL due to groundwater exchange ΔL due to biogeochemical processing total change in load

Changes in Load: Groundwater and Biogeochemical Influences

Reach

b a¥ b b ab¥ a¥ ab b ab¥ a¥ ab¥ b ab¥ b¥ a¥ a

∆Lbio (kg/d) ∆Lgw (kg/d) NO3-N NH4-N

UNO3 > 0 = production UNO3 < 0 = removal

UNO3 (mg N/m2/d)

enhanced nitrification NH4

+

availability

Comparative Rates

[NH4

+]

Bernal et al. 2017

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:

Doug Martin, MT NRDP Jim Ford, MT NRDP Beau Downing, MT NRDP Tom Parker, Geum Consulting Marisa Sowles, Geum Consulting Heggelund Ranch Ueland Ranch Kelley Ranch Lambert Ranch

Field & Lab Techs:

Kim Bray Claire Utzman Fischer Young Kate Perkins Lauren Sullivan Ash Micklewright Carly Andlauer

"This material is based upon work supported in part by the National Science Foundation EPSCoR Cooperative Agreement OIA-1757351"