Fracture Intensity Impacts on Reaction Front Propagation and Mineral Weathering in Three‐Dimensional Fractured Media

Andrews, Elizabeth; Hyman, Jeffrey D.; Sweeney, Matthew; Karra, Satish; Moulton, J. David; Navarre‐Sitchler, Alexis

doi:10.1029/2022wr032121

Cited by 8 publications

(3 citation statements)

References 87 publications

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“…The old landscape age of the Manitou watershed enables a transport‐limited groundwater system, as 40 Ma of Pikes Peak granite weathering (Blair, 1976) has established preferential flowpaths along fractures in the granite. In fractured‐igneous systems, weathering rates scale and slow through time as reaction fronts propagate and lead to zones of low reactivity, as observed and modelled in Gordon Gulch, a small headwater catchment with similar climate and geology (Andrews et al, 2023). In a fractured‐granite system such as at Manitou, these low‐reactivity fractures coupled with long groundwater residence times enable clays to become geochemically saturated and drive stream chemostasis for solutes involved in both primary mineral dissolution and secondary mineral precipitation, notability SiO 2(aq) and Al 3+ .…”

Section: Resultsmentioning

confidence: 96%

Water‐rock interactions drive chemostasis

Warix,

Navarre‐Sitchler,

Singha

2024

Hydrological Processes

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The western U.S. is experiencing shifts in recharge due to climate change, and it is currently unclear how hydrologic shifts will impact geochemical weathering and stream concentration–discharge (C–Q) patterns. Hydrologists often use C–Q analyses to assess feedbacks between stream discharge and geochemistry, given abundant stream discharge and chemistry data. Chemostasis is commonly observed, indicating that geochemical controls, rather than changes in discharge, are shaping stream C–Q patterns. However, few C–Q studies investigate how geochemical reactions evolve along groundwater flowpaths before groundwater contributes to streamflow, resulting in potential omission of important C–Q controls such as coupled mineral dissolution and clay precipitation and subsequent cation exchange. Here, we use field observations—including groundwater age, stream discharge, and stream and groundwater chemistry—to analyse C–Q relations in the Manitou Experimental Forest in the Colorado Front Range, USA, a site where chemostasis is observed. We combine field data with laboratory analyses of whole rock and clay x‐ray diffraction and soil cation‐extraction experiments to investigate the role that clays play in influencing stream chemistry. We use Geochemist's Workbench to identify geochemical reactions driving stream chemistry and subsequently suggest how climate change will impact stream C–Q trends. We show that as groundwater age increases, C–Q slope and stream solute response are not impacted. Instead, primary mineral dissolution and subsequent clay precipitation drive strong chemostasis for silica and aluminium and enable cation exchange that buffers calcium and magnesium concentrations, leading to weak chemostatic behaviour for divalent cations. The influence of clays on stream C–Q highlights the importance of delineating geochemical controls along flowpaths, as upgradient mineral dissolution and clay precipitation enable downgradient cation exchange. Our results suggest that geochemical reactions will not be impacted by future decreasing flows, and thus where chemostasis currently exists, it will continue to persist despite changes in recharge.

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Section: Resultsmentioning

confidence: 96%

Water‐rock interactions drive chemostasis

Warix,

Navarre‐Sitchler,

Singha

2024

Hydrological Processes

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“…It has been hypothesized that soil O 2 to CO 2 ratios in different landscape positions (ridgetops vs. valleys) are key measures of reactivity and can directly link to the depths of weathering fronts and CZ (Brantley et al., 2013; Li et al., 2017); this has indeed been shown to be the case using RTM (Heidari et al., 2017). Geochemical modeling capabilities have been recently expanded to include root processes to test hypotheses regarding how plants affect weathering and CZ thickness (Sullivan, Goddéris, et al., 2019; Wen et al., 2021) as well as to better incorporate fracturing and fracture networks, a major component of the deep CZ (Andrews et al., 2023). A major limitation of current RTMs is the assumption of constant, stable, physical upper boundary at the ground surface without integrating dynamic processes such as soil erosion, dust deposition, and sediment transport.…”

Section: Current Approaches To Constrain the Base And Thickness Of Th...mentioning

confidence: 99%

Expanding the Spatial Reach and Human Impacts of Critical Zone Science

Singha,

Sullivan,

Billings

et al. 2024

Earth's Future

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Two major barriers hinder the holistic understanding of subsurface critical zone (CZ) evolution and its impacts: (a) an inability to measure, define, and share information and (b) a societal structure that inhibits inclusivity and creativity. In contrast to the aboveground portion of the CZ, which is visible and measurable, the bottom boundary is difficult to access and quantify. In the context of these barriers, we aim to expand the spatial reach of the CZ by highlighting existing and effective tools for research as well as the “human reach” of CZ science by expanding who performs such science and who it benefits. We do so by exploring the diversity of vocabularies and techniques used in relevant disciplines, defining terminology, and prioritizing research questions that can be addressed. Specifically, we explore geochemical, geomorphological, geophysical, and ecological measurements and modeling tools to estimate CZ base and thickness. We also outline the importance of and approaches to developing a diverse CZ workforce that looks like and harnesses the creativity of the society it serves, addressing historical legacies of exclusion. Looking forward, we suggest that to grow CZ science, we must broaden the physical spaces studied and their relationships with inhabitants, measure the “deep” CZ and make data accessible, and address the bottlenecks of scaling and data‐model integration. What is needed—and what we have tried to outline—are common and fundamental structures that can be applied anywhere and used by the diversity of researchers involved in investigating and recording CZ processes from a myriad of perspectives.

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“…Dissolution and precipitation of solid solutes occur in a broad range of natural phenomena and technological applications. Typical examples are dissolution of minerals in subsurface hydrology (Andrews et al., 2023; Baqer & Chen, 2022; Přikryl et al., 2017), biofilm growth in nutrient rich environments (Jung & Meile, 2021), etching into substrates (Cui et al., 2019), and conversion of active material in energy storage systems (Danner & Latz, 2019; Fang et al., 2021).…”

Section: Introductionmentioning

confidence: 99%

General Local Reactive Boundary Condition for Dissolution and Precipitation Using the Lattice Boltzmann Method

Weinmiller,

Lautenschlaeger,

Kellers

et al. 2024

Water Resources Research

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A general and local reactive boundary condition (RBC) for studying first‐order equilibrium reactions using the lattice Boltzmann method is presented. Its main characteristics are accurate reproduction of wall diffusion, invariance to the wall and grid orientation, and absence of nonphysical artifacts. The scheme is successfully tested for different benchmark cases considering diffusion, advection, and reactions of fluids at solid‐liquid interfaces. Unlike other comparable RBCs from the literature, the novel scheme is valid for a large range of Péclet and Damköhler numbers, and shows realistic pattern formation during precipitation. In addition, quantitative results are in good accordance with analytical solutions and values from literature. Combining the new RBC with the rest fraction method, Péclet‐Reynolds ratios of up to 1,000 can be achieved. Overall, the novel RBC accurately models first‐order reactions, is applicable for complex geometries, and allows efficiently simulating dissolution and precipitation phenomena in fluids at the pore scale.

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Fracture Intensity Impacts on Reaction Front Propagation and Mineral Weathering in Three‐Dimensional Fractured Media

Cited by 8 publications

References 87 publications

Water‐rock interactions drive chemostasis

Water‐rock interactions drive chemostasis

Expanding the Spatial Reach and Human Impacts of Critical Zone Science

General Local Reactive Boundary Condition for Dissolution and Precipitation Using the Lattice Boltzmann Method

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