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Hysteresis in nitrate uptake
No full textAccurately quantifying nutrient removal and retention in streams is crucial for the proper management of watersheds as anthropogenic nutrient inputs continue to increase. The Tracer Additions for Spiraling Curve Characterization (TASCC) method is commonly used to estimate the ambient uptake rates of nutrients, such as nitrate (NO3). However, uptake dynamics along the concentration gradient from TASCC additions are often dependent on whether nutrient concentrations are increasing or decreasing, exhibiting hysteresis. The hysteresis in uptake relative to nutrient concentration affects the TASCC method`s ability to obtain accurate estimates of ambient uptake metrics. What properties of the stream that are influencing the hysteresis is unclear, though exchange with subsurface flowpaths, such as the hyporheic zone is suspected. We conducted TASCC additions of NO3 at 5 headwater mountain streams whose hyporheic extent and exchange rates have been measured by 3D geophysical imaging and estimated from solute transport models to see if the hyporheic zone affects hysteresis in NO3 uptake dynamics. We present a single metric for quantifying hysteresis in uptake, M_H, that describes both its magnitude and direction. M_H was positive (clockwise in direction) at all of the streams with measurable uptake. However, M_H was not related to the extent of the hyporheic zone as measured by 3D geophysical imaging or its size and exchange rate estimated by solute transport models. Describing hysteresis in nutrient uptake with M_H will provide a more comprehensive understanding of nutrient uptake dynamics and allow for more accurate estimates of nutrient processing in streams
Hyporheic zone size from 3D geophysics
No full textThe hyporheic zone is an ecologically critical region of a stream where surface waters transit the subsurface. Spatially defining the hyporheic zone from in-stream solute dynamics models is indirect, where individual model terms describe overlapping regions of the solute breakthrough curve. Alternatively, direct measurements of the hyporheic zone from geophysical imaging techniques, such as electrical resistivity tomography (ERT), combined with additions of an electrically conductive tracer (e.g. sodium chloride; NaCl) have provided insight to the extent and spatial heterogeneity of hyporheic exchange in two dimensions. While 2D ERT produces a planar representation of the hyporheic zone, characterizing all three spatial dimensions is critical to better describe its distribution and role in biogeochemical processes along a reach. We applied 3D ERT imaging combined with constant rate NaCl additions to three headwater streams to yield spatially comprehensive representations of dynamic solute concentrations volumetrically within the hyporheic zone. Vertical exchange of the tracer with the streambed was the dominant vector of hyporheic exchange in all streams. The average depth of penetration of the tracer into the streambed was similar for streams and ranged from 0.77 to 0.80 m. The movement of solutes through the hyporheic zone was quicker than the 3D ERT acquisition speed (<45 min) in all three streams, where the hyporheic zone both reached a steady enriched state and returned to ambient conditions in a single measurement cycle. The rapid hyporheic exchange at all of the streams did not permit the assessment of their temporal dynamics. Due its direct measurement of subsurface electrical properties, the use of 3D ERT provided a better representation of the hyporheic zone extents and heterogeneity with estimates of the cross-sectional area of the hyporheic zone 2-4x larger than estimates from transient storage modeling
Linking denitrification with oxygen respiration in mountain streams
No full textChamber estimates of denitrification and respiration. Raw data for estimating denitrification and respiration are located in the csv file
Data for paper 'Validation of finite water-content vadose zone dynamics method using column experiments with a moving water table and applied surface flux'
No full textData for paper 'Validation of finite water-content vadose zone dynamics method using column experiments with a moving water table and applied surface flux
5_(100)_100 Grain Boundary
No full textInitial structure was downloaded from Grain Boundaries studio website, and then structures were relaxed for Ni using LAMMPS code with Bonny 2013 potential
Salt precipitation in ultra-tight porous media
No full textSalt precipitation in ultra-tight porous medi
WRF outputs over Wyoming
No full textDataset size: 1.1 TB, ReadMe available below; Weather and Research Forecasting (WRF) outputs over Wyomin
5_(1-21)_100 Grain Boundary
No full textInitial structure was downloaded from Grain Boundaries studio website, and then structures were relaxed for Ni using LAMMPS code with Bonny 2013 potential
Behavioural plasticity modulates temperature-related constraints on foraging time for a montane mammal
No full textBehavioural plasticity modulates temperature-related constraints on foraging time for a montane mamma