README

Resource title:
Data and Model Materials for "Contrasting Roles of Sedimentary and Microbial Heterogeneity in Controlling Hyporheic Nitrate Removal”.


1. Overview

This resource contains supporting data for the study "Contrasting Roles of Sedimentary and Microbial Heterogeneity in Controlling Hyporheic Nitrate Removal".

The resource includes:
(1) initial permeability fields for the heterogeneous sediment structures based on the Massillon Sandstone and Brazos River deposits;
(2) initial particulate organic carbon (POC) fields corresponding to these sediment structures; and
(3) numerical simulation data underlying Figures 3–5 of the manuscript.

These data support the analyses of the effects of sedimentary heterogeneity, microbial biomass dynamics, and biofilm-induced bioclogging on hyporheic nitrate removal.


2. Sediment-property data

The sediment-property datasets describe the initial heterogeneous fields used in the numerical simulations.

Massillon Sandstone:
- Initial permeability field
- Initial POC content field

Brazos River:
- Initial permeability field
- Initial POC content field

The spatial fields were constructed from image-based representations of the sediment structures described in the manuscript. In COMSOL, the imported images were represented by the interpolation function im1(x,y), with image values nominally ranging from 0 to 1. The image function was then scaled to generate the initial POC fields used in the reactive-transport simulations. POC supplies dissolved organic carbon (DOC) through the first-order kinetic dissolution process described in Eq. (6) of the manuscript.


3. Data underlying Figures 3–5

The resource contains the numerical simulation data used to generate Figures 3–5 of the manuscript.

Figure 3:
Spatiotemporal distributions from the Hetero. Sed. & Bio. Growth model for the Brazos River sediment structure at U = 0.8 m s−1.

Figure 4:
Spatiotemporal distributions from the corresponding Homo. Sed. & Bio. Growth model.

Figure 5:
Spatiotemporal distributions from the Hetero. Sed. & Const. Bio. model.

The variables include:
- Xh: functional heterotrophic microbial biomass
- kxx: streamwise component of intrinsic permeability
- DOC: dissolved organic carbon
- DO: dissolved oxygen
- NO3−: nitrate
- R_DOC: DOC reaction rate
- R_NO3: nitrate reaction rate

Units are provided in the corresponding data files and/or figure descriptions.


4. Model scenarios

Three model configurations are compared in the study:

Hetero. Sed. & Bio. Growth:
Heterogeneous sediment properties with spatiotemporally evolving microbial biomass and associated bioclogging feedback.

Homo. Sed. & Bio. Growth:
Equivalent homogeneous sediment properties with microbial growth and associated bioclogging feedback.

Hetero. Sed. & Const. Bio.:
Heterogeneous sediment properties with spatially uniform and temporally constant microbial biomass.

These scenarios are used to evaluate the contrasting influences of small-scale sedimentary heterogeneity and spatiotemporally evolving microbial heterogeneity and its associated bioclogging feedback on hyporheic nitrate removal.


5. Data use

The sediment-property fields can be used to reconstruct the heterogeneous sediment configurations considered in the study. The Figure 3–5 datasets provide the numerical results underlying the spatial and temporal patterns presented in the manuscript.

For detailed descriptions of the governing equations, model parameterization, boundary conditions, and simulation scenarios, please refer to the associated manuscript.