Investigating the role of deep weathering in critical zone evolution by reactive transport modeling of the geochemical composition of deep fracture water

Ackerer, Julien; Ranchoux, Coralie; Lucas, Yann; Viville, Daniel; Clément, Alain; Fritz, Bertrand; Lerouge, Cathérine; Schäfer, Gerhard; Chabaux, François

doi:10.1016/j.gca.2021.07.017

Cited by 12 publications

(10 citation statements)

References 69 publications

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“…The comparison of water transit times suggested that the deepest and oldest waters are not captured by simulations, as the EcH 2 O-iso model setup for this study does not include the CZ compartment corresponding to deep and fractured bedrock. However, the weathered and porous regolith has been shown to contain much more water than the fractured bedrock (Ackerer et al, 2021), and our storage estimate may only slightly underestimate the exact CZ water storage. In addition, adding this deeper water compartment may only contribute to the inactive water storage in watersheds, as deep waters stored in the fractured bedrock have no clear connection with the hydrological network, at least in the Strengbach watershed (Ackerer et al, 2021).…”

Section: Uncertainties and Model Limitationsmentioning

confidence: 80%

Exploring the Critical Zone Heterogeneity and the Hydrological Diversity Using an Integrated Ecohydrological Model in Three Contrasted Long‐Term Observatories

Ackerer,

Kuppel,

Braud

et al. 2023

Water Resources Research

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An integrated ecohydrological modeling approach was deployed in three long‐term critical zone (CZ) observatories of the French CZ network (CZ Observatories—Application and Research) to better understand how the CZ heterogeneity modulates the water cycle within territories. Ecohydrological simulations with the physically based model EcH2O‐iso constrained by a wide range of observations crossing several disciplines (meteorology, hydrology, geomorphology, geophysics, soil sciences, and satellite imagery) are able to capture stream water discharges, evapotranspiration fluxes, and piezometric levels in the Naizin, Auradé, and Strengbach watersheds. In Naizin, an agricultural watershed in northwestern France with a schist bedrock underlying deep weathered materials (5–15 m) along gentle slopes, modeling results reveal a deep aquifer with a large total water storage (1,080–1,150 mm), an important fraction of inactive water storage (94%), and relatively long stream water transit times (0.5–2.5 years). In the Auradé watershed, representative of agricultural landscapes of the southwestern France developed on molasse, a relatively shallow regolith (1–8 m) is observed along hilly slopes. Simulations indicate a shallow aquifer with moderate total water storage (590–630 mm), an important fraction of inactive water storage (91%), and shorter stream water transit times (0.1–1.3 years). In the Strengbach watershed, typical of mid‐mountain forested landscapes developed on granite, CZ evolution implies a shallow regolith (1–5 m) along steep slopes. Modeling results infer a shallow aquifer with the smallest total water storage (475–575 mm), the shortest stream water transit times (0.1–0.7 years), but also the highest fraction of active water storage (18%).

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Section: Uncertainties and Model Limitationsmentioning

confidence: 80%

Exploring the Critical Zone Heterogeneity and the Hydrological Diversity Using an Integrated Ecohydrological Model in Three Contrasted Long‐Term Observatories

Ackerer,

Kuppel,

Braud

et al. 2023

Water Resources Research

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“…Longer MRTs could be linked to the proximity of the regolith at the catchment area examined here. Shallow groundwater transit times of hundreds of years have been determined deeper (> 15 m) in the critical zone (Ackerer et al 2021 ).…”

Section: Resultsmentioning

confidence: 99%

Soil solution data from Bohemian headwater catchments record atmospheric metal deposition and legacy pollution

Petrash

Krám

Pérez-Rivera

et al. 2023

Environ Sci Pollut Res

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Soil solution chemistry depends largely on mineralogy and organic matter properties of soil horizons with which they interact. Differing lithologies within a given catchment area can influence variability in soil cation exchange capacities and affect solute transport. Zero-tension and tension lysimeters were used to evaluate the fast transport of solutes in the topsoil vs. slow diffusional matrix flow at the subsoil of three contrasting lithology catchments in a mid-elevation mountain forest. Our aim was to test the feasibility of lysimeters’ hydrochemical data as a gauge for legacy subsoil pollution. Due to contrasting lithologies, atmospheric legacy pollution prevailing at the soil-regolith interface is differently yet consistently reflected by beryllium, lead, and chromium soil solution concentrations of the three catchments. Geochemical (dis)equilibrium between the soil and soil matrix water governed the hydrochemistry of the soil solutions at the time of collection, potentially contributing to decreased dissolved concentrations with increased depths at sites with higher soil pH. A complementary isotopic δ18O runoff generation model constrained potential seasonal responses and pointed to sufficiently long water-regolith interactions as to permit important seasonal contributions of groundwater enriched in chemical species to the topsoil levels. Our study also reflects subsoil equilibration with atmospheric solutes deposited at the topsoil and thus provides guidance for evaluating legacy pollution in soil profiles derived from contrasting lithology.

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“…Although a common observation, permeability distribution can be complicated by the presence of fractures and roots that enable deeper penetration of acidic soil water and promote weathering at depth (Sullivan et al., 2022). This can happen especially when fractures are roots are the primary water conduits (Ackerer et al., 2021; Wen et al., 2021). The OC content typically declines with depth, as we assumed here (Hauser et al., 2020).…”

Section: Discussionmentioning

confidence: 99%

“…Here we begin to address this knowledge gap by asking the question: How and to what extent do subsurface carbon transformation, chemical weathering, and solute export differ across hydrological and subsurface structure regimes? To answer this question, we draw upon the rich foundation of reactive transport modeling (RTM) that has been widely used to understand hydrological and biogeochemical coupling (Ackerer et al., 2021; Dwivedi et al., 2022; Jung & Navarre‐Sitchler, 2018; Li, Bao, et al., 2017; Wen et al., 2020). Here we first developed a hillslope‐scale RTM using soil CO 2 and soil water chemistry data from the Fitch Forest, a temperate forest at the ecotone boundary of the Eastern temperate forest and mid‐continent grasslands in Kansas (Fitch, 2006).…”

Section: Introductionmentioning

confidence: 99%

From Soils to Streams: Connecting Terrestrial Carbon Transformation, Chemical Weathering, and Solute Export Across Hydrological Regimes

Wen

Sullivan

Billings

et al. 2022

Water Resources Research

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Soil is the largest terrestrial carbon pool (Batjes, 2014). Vertical fluxes of CO 2 into the atmosphere have been extensively studied (e.g., Bond-Lamberty et al., 2020;Chapin et al., 2006;Jian et al., 2021). Lateral fluxes of dissolved organic and inorganic carbon (DOC and DIC) from terrestrial to aquatic systems have been increasingly recognized for emitting substantial amounts of CO 2 along river corridors (e.g., Barnes et al., 2018;Battin et al., 2009;Regnier et al., 2013). Vertical and lateral carbon fluxes, however, are often studied separately within disciplinary boundaries (Brookfield et al., 2021;Grimm et al., 2003). Their connections, partitioning, and relationship to carbon transformation across gradients of hydroclimatic and subsurface conditions have remained poorly understood. As a result, quantifications of carbon transformation rates and fluxes have remained highly uncertain (Duvert et al., 2018).Organic carbon (OC) transformation and chemical weathering (i.e., carbonate dissolution and precipitation) are key processes that produce dissolved and gaseous carbon and drive terrestrial carbon dynamics. Their rates depend on hydroclimatic conditions (Figure 1) that are bound to change under future climates with intensifying hydrological extremes including droughts and storms (Ault, 2020;Mastrotheodoros et al., 2020). Soil respiration rates often increase with temperature (Lloyd & Taylor, 1994) but peak at 50%-70% water saturation (Yan et al., 2018).

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Investigating the role of deep weathering in critical zone evolution by reactive transport modeling of the geochemical composition of deep fracture water

Cited by 12 publications

References 69 publications

Exploring the Critical Zone Heterogeneity and the Hydrological Diversity Using an Integrated Ecohydrological Model in Three Contrasted Long‐Term Observatories

Exploring the Critical Zone Heterogeneity and the Hydrological Diversity Using an Integrated Ecohydrological Model in Three Contrasted Long‐Term Observatories

Soil solution data from Bohemian headwater catchments record atmospheric metal deposition and legacy pollution

From Soils to Streams: Connecting Terrestrial Carbon Transformation, Chemical Weathering, and Solute Export Across Hydrological Regimes

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