Session HS8.1.2

HS8.1.2 | Coupled transport, reactive processes and biological activity in soils, the vadose zone, and below

Coupled transport, reactive processes and biological activity in soils, the vadose zone, and below

Co-organized by SSS5

Convener: Yves Meheust | Co-conveners: Maria KlepikovaECSECS, Vittorio Di Federico, Oshri BorgmanECSECS, Clement Roques, Florian Doster, Pietro De Anna

Orals

| Wed, 17 Apr, 10:45–12:30 (CEST)

Room 2.15

Posters on site

| Attendance Wed, 17 Apr, 16:15–18:00 (CEST) | Display Wed, 17 Apr, 14:00–18:00

Hall A

Physical (e.g. flow and transport), chemical (e.g. red-ox reactions) and biological (e.g. bio-mineralization) processes occurring in the fluid phases or at solid-fluid boundaries in soils, the vadose zone, and in deeper subsurface permeable media, are critical in controlling the dynamics of contaminant transport and remediation in groundwater and the vadose zone; of biogeochemical cycles; of the geological storage of energy, CO2 and H2; or of enhanced oil and gas recovery. The increasing need to better understand and characterize the temporal dynamics of these coupled processes, which take place in heterogeneous environments, has motivated the development of novel experimental approaches, from laboratory to field, including 4D geophysical methods, near-real time biochemical and isotopic monitoring, smart sensors and observation systems, and microscopy imaging techniques. Detailed experimental investigation and evidence of complex subsurface processes allow testing and validating new measuring techniques, and provide datasets with sufficient resolution to make the validation of theories and numerical models involving coupled processes possible. The session will provide the opportunity for a multidisciplinary discussion based on recent advances in the experimental characterization and modeling of single and multiphase flows (including flows of non-Newtonian fluids), conservative and reactive solute transport, heat transport, and/or bacterial dynamics and biofilm growth, in porous and fractured media. Configurations where these processes are coupled will be particularly appreciated. Examples of applications include NAPL remediation and (bio)degradation, CO2 and H2 storage, geothermal energy, and hydrogeological field tests (in particular tracer and heat tests). Experiments featuring high resolution measurements with novel sensors, analytical, and imaging techniques, as well as novel modeling and upscaling techniques, will be addressed prominently.

Orals: Wed, 17 Apr | Room 2.15

Chairpersons: Clement Roques, Ronan Abhervé, Oshri Borgman

10:45–10:47

Introduction by conveners

Mutiphase flows

10:47–10:57

EGU24-4016

ECS

On-site presentation

Experiment and simulation of quasistatic capillary rise in an ink-bottle setup resultingin pressure-saturation (p-s) hysteresis

Animesh Nepal, Juan J. Hidalgo, Jordi Ortin, Ivan Lunati, and Marco Dentz

During imbibition, fluid-fluid interface at the inlet of a constriction experiences an increase in capillary force that results in rapid fluid invasion known as Haines jump. During drainage, the interface gets pinned at the end of the constriction, which causes pressure-saturation (p-s) trajectories to follow different paths during imbibition and drainage resulting in p-s hysteresis. In this work, we performed quasistatic two-phase flow experiments and simulations of cyclic imbibition and drainage in a capillary tube with a constriction (ink-bottle) to have a quantitative understanding of p-s hysteresis. In the setup, drainage and imbibition were driven by quasitatically changing the pressure gradient between the inlet and the outlet of the tube. The experimental results were compared with the results from a numerical model in OpenFOAM, which solves the Navier-Stokes equations employing Volume of Fluid method to calculate the position of the interface. We observed that multiphase flow through a single constriction revealed distinct p-s hysteresis, a common trait in porous media. The steeper the constriction, the more pronounced the p-s hysteresis and vice versa. We derived an analytical solution to obtain the p-s curve and compared the results obtained from experiments and simulations. This comparative study will allow us to quantitatively link the pore-scale capillary physics to large-scale p-s hysteresis.

How to cite: Nepal, A., Hidalgo, J. J., Ortin, J., Lunati, I., and Dentz, M.: Experiment and simulation of quasistatic capillary rise in an ink-bottle setup resultingin pressure-saturation (p-s) hysteresis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4016, https://doi.org/10.5194/egusphere-egu24-4016, 2024.

10:57–11:07

EGU24-5680

ECS

On-site presentation

Vapor condensation in fractured porous media revealed by in-situ rapid neutron tomography and numerical modeling

Arash Nemati, Bratislav Lukić, Alessandro Tengattini, Matthieu Briffaut, and Philippe Sechet

The study of phase change in processes involving two-phase flow in porous media remains relatively under-explored due to the intricate nature arising from the strong coupling between heat and mass transfer and the heterogeneity of the medium. However, condensation in porous media plays a crucial role in various applications, including steam-based gas recovery, underground contamination removal, the integrity of geothermal, CO₂ storage reservoirs, durability of concrete structure, and porous fabric and insulation condensation. The objective of this study is to provide a deeper understanding of the subject by conducting rapid neutron tomographies during vapor injection experiments and introducing a novel numerical approach to model the process.

The identification and quantification of water is revealed using 3D rapid in-situ neutron imaging, acquired at 30-second intervals per tomography. Such temporal resolution is possible thanks to the high neutron flux of the Institute Laue Langevin Grenoble (ILL) using the imaging instrument NeXT (Neutron and X-ray Tomograph [1]). The experiments were preceded by a calibration and correction campaign where the quantification of water content was fitted to empirical correlation and the spurious deviations arising from the scattering of neutrons were accounted for using the black body (BB) grid method [2]. The in-situ experiment consists of the injection of a predefined mixture of air and water vapor at a constant flow rate into cylindrical samples of Fontainebleau sandstone with a splitting crack along their height. Successive rapid neutron tomographies are acquired during the injection of vapor to investigate the evolution of water content and condensation process inside the sample. Furthermore, X-ray tomography is performed prior to the vapor injection, and part of the sample is scanned by synchrotron microtomography with 6.5 micrometers pixel size. This allows for extracting the microstructure and morphology of the crack and porous matrix, and its impact on the spatio-temporal accumulation of liquid water, and understanding its migration within the crack and matrix. The results [3,4] show that water initially emerges near the inlet and spreads toward distant areas. Condensed water generally has the tendency to occupy tighter spaces within the sample. The condensed water diffuses into the porous matrix due to capillary effects and pressure buildup in the crack.

Preliminary results of a numerical model developed in OpenFoam are also discussed. The model solves heat transfer and two-phase flow equations with phase change mass transfer terms. It is capable of modeling water condensation and temperature fields within a domain of heterogeneous porous media contributing additional insights to the phenomena.

References:

1) Tengattini, A., et al., Nucl. Instrum. Methods Phys. Res., 968, 163939 (2020)

2) Boillat, P., et al., Optics Express, 26(12), 15769-15784 (2018)

3) Gupta, R. et al., Cem. Concr. Res., 162, p. 106987. (2022)

4) Nemati, A., et al., Transp. Porous Media, 150(2), 327-357 (2023)

How to cite: Nemati, A., Lukić, B., Tengattini, A., Briffaut, M., and Sechet, P.: Vapor condensation in fractured porous media revealed by in-situ rapid neutron tomography and numerical modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5680, https://doi.org/10.5194/egusphere-egu24-5680, 2024.

Discussion Post a comment

Solute mixing and dispersion

11:07–11:17

EGU24-5575

On-site presentation

Experimental imaging of pore scale stretching and coalescence as drivers for solute mixing in porous media

Kevin Pierce, Tanguy Le Borgne, and Gaute Linga

The combined action of stretching and diffusion within solute plumes controls mixing in flows through soils and fractured rocks, ultimately affecting the rates of subsurface reactions. Stretching enhances mixing by increasing the area available for diffusion to act and steepening concentration gradients. Ultimately, the resulting solute filaments coalesce which drives the transition of concentration profiles toward uniformity. While the role of stretching is well described by current models, the effect of coalescence on mixing has been more challenging to understand, partly because the spatial extent and distribution of coalesced regions depends on the geometric structure of the medium. Here we present a new set of experiments designed to isolate the role of coalescence on mixing in porous media. Using stereolithography 3D printing, we have fabricated transparent porous models with different geometric structures. By imaging pulses of fluorescent dye as they mix in flows through these models, we have resolved the dependence of mixing rates on both Peclet number and the medium geometry. We observe that converging streamlines downstream of stagnation points establish local zones in the flow where coalescence is enhanced. From these observations, we describe the statistics of coalescence and its impact on mixing and reaction rates. These findings support the ongoing effort to improve our predictions of mixing and reactive transport in the subsurface.

How to cite: Pierce, K., Le Borgne, T., and Linga, G.: Experimental imaging of pore scale stretching and coalescence as drivers for solute mixing in porous media, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5575, https://doi.org/10.5194/egusphere-egu24-5575, 2024.

11:17–11:27

EGU24-10971

On-site presentation

Dispersion in heterogeneous networks under linear and non-linear flow conditions

Marco Dentz, Jannes Kordilla, and Juan Hidalgo

The understanding and prediction of dispersion phenomena in natural and engineered media are key issues in different fields of science and engineering, with applications ranging from groundwater management to geological energy storage. Spatial variability in the physical medium properties and flow conditions leads to scale effects in the flow and dispersion processes. Here we study the mechanisms of dispersion in two- and three-dimensional heterogeneous networks under linear and non-linear flow conditions, that is, for flows in which the flow rate is a non-linear function of the pressure gradient. Such non-linear relationships have been found for the flow of non-Newtonian fluids, for multiphase flow and inertial flows in porous, fractured and karstic media. We study transport under steady flow using a Lagrangian approach. The flow fields are characterized statistically in terms of the distribution of Eulerian and Lagrangian flow velocities and their correlation properties. Longitudinal dispersion is measured in terms of particle breakthrough curves. We observe broad distributions of particle arrival times, which are manifestations of memory processes that occur due to broadly distributed flow velocities and mass transfer rates. These behaviors are analyzed in terms of the Eulerian and Lagrangian flow statistics, medium structure and flow conditions. Based on this analysis, we propose a stochastic time domain random walk approach to quantify the impact of the network heterogeneity and flow conditions on large-scale dispersion.

How to cite: Dentz, M., Kordilla, J., and Hidalgo, J.: Dispersion in heterogeneous networks under linear and non-linear flow conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10971, https://doi.org/10.5194/egusphere-egu24-10971, 2024.

11:27–11:37

EGU24-3554

ECS

On-site presentation

Experimental and numerical study of CO2 sequestration in a heterogeneous porous medium

Rima Benhammadi, Patrice Meunier, Marco Dentz, and Juan J. Hidalgo

We investigate both experimentally and numerically the gravitational instability due to the dissolution of carbon dioxide into brine in heterogeneous porous media. To do so, we consider a two dimensional Hele-Shaw cell of 0.073 m x 0.49 m, in which a log-normally distributed permeability field has been engraved. Permeability fields with a mean gap of 370 µm and 500 µm, a correlation length λ_x = 0.032 m, λ_z = 0.016 m and a variance of 0.137 are considered in order to see the effect of heterogeneity on the convective instability. Experiments in cells with a constant gap are also performed. The CO₂ partial pressure is varied between 12% and 85%. The convective patterns are visualized using a pH sensitive dye (Bromocresol green).

Experimental results show that fingers tend to merge faster in the heterogeneous cases than in the homogeneous ones and tend to look more distorted. The number of fingers at late times is smaller in the heterogeneous cases than in the homogeneous ones. The gap thickness has little effect in the heterogenous cells but a small increase of fingers with the gap width is observed in the absence of heterogeneity. Moreover, the amplitude of the instability is higher in the case of the heterogeneous experiments whereas the growth rate at early times is a bit smaller compared to the homogeneous ones. The amplitude of the instability at late times is higher for the cases with bigger gap thickness for homogeneous and heterogeneous cases. Increasing the partial pressure of CO₂ intensifies the amplitude of the instability as well as the number of fingers at a given time. As for the Numerical simulations, they reproduce well the evolution of the number of fingers and the amplitude of the instability. However, the numerical time for the onset of convection is longer.

Key words: CO₂ sequestration, Rayleigh-Taylor instability, heterogeneity, fingering patterns, amplitude, growth rate.

How to cite: Benhammadi, R., Meunier, P., Dentz, M., and Hidalgo, J. J.: Experimental and numerical study of CO2 sequestration in a heterogeneous porous medium, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3554, https://doi.org/10.5194/egusphere-egu24-3554, 2024.

Coupled transport and heterogeneous reactions

11:37–11:47

EGU24-2217

ECS

On-site presentation

What controls the development of heterogenous dissolution patterns in carbonate rocks?

Atefeh Vafaie, Josep M. Soler, Jordi Cama, Iman R. Kivi, Samuel Krevor, and Victor Vilarrasa

Porosity and permeability changes are anticipated when carbonate rocks are percolated with and dissolved by acidic fluids. The ability to predict the location, extent, and impact of these changes could benefit acid-relevant operations in carbonate rocks, specifically CO₂ storage by improving our estimates of CO₂ flow and storage performance in the subsurface. In this work, we combine percolation experiments and numerical simulations to capture the chemical effects of CO₂-saturated water (weak acid) and HCl solution (strong acid) on cm-scale limestone cores. Numerical simulations are parameterized and validated against experimental data, including effluent solution chemistry, porosity distribution, and observed dissolution features in CT images of the reacted specimens. CT imaging data of intact cores are employed to construct porosity and permeability distribution maps over the core domain serving as input for reactive transport models of the experiments. The results indicate that the pore space heterogeneity controls the mineral dissolution from the onset of the acidic fluid injections, while the acid type becomes progressively important as the dissolution front further penetrates the rock. The compact dissolution pattern formed in the HCl-treated cores due to the complete dissociation of the strong acid could be numerically simulated using a generalized power-law porosity-permeability relationship with a power value of 3, applied at the numerical grid scale. However, the formation of the lengthwise wormhole in CO₂-treated cores due to partial dissociation of the weak acid and its buffering capacity could be only simulated using a large power value of 15 at the grid scale in the porosity-permeability relationship. This exponent increases to 27.6 for the bulk flow behavior of the limestone core containing the wormhole, illustrating large-scale dependence of acid-induced permeability evolutions in carbonate rocks. These findings highlight the need for developing robust upscaling approaches to account for the hydraulic behavior of reactive, intrinsically heterogeneous carbonate rocks in large-scale simulations.

How to cite: Vafaie, A., Soler, J. M., Cama, J., Kivi, I. R., Krevor, S., and Vilarrasa, V.: What controls the development of heterogenous dissolution patterns in carbonate rocks?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2217, https://doi.org/10.5194/egusphere-egu24-2217, 2024.

11:47–11:57

EGU24-3082

ECS

On-site presentation

Investigation of mineral dissolution kinetics through Atomic Force Microscopy

Chiara Recalcati, Martina Siena, Monica Riva, Monica Bollani, and Alberto Guadagnini

We illustrate an experimental platform grounded on Atomic Force Microscopy (AFM) imaging enabling one to evaluate nanometer-scale absolute material fluxes across a mineral surface subject to precipitation/dissolution reaction under continuous flow. Reactive phenomena of this kind taking place at the solid-fluid interface have a pivotal role in driving alterations of the fundamental properties of natural geologic systems (including, e.g., porosity, permeability, and storage capacity). High resolution experimental observations document that several kinetic processes contribute to the overall reaction. These, in turn, yield a markedly heterogeneous distribution of reaction rates. The latter cannot be characterized through average rate values. Current challenges limiting our ability to characterize such heterogeneity include the establishment of a reliable integrated experimental platform that allows employing AFM imaging to evaluate real-time and in situ absolute material fluxes across the mineral surface. These can then be employed to enrich and expand typical analyses of the evolution of surface morphology. We overcome these barriers and provide spatial distributions of rates observed at the nanoscale across the surface of a calcite crystal subject to dissolution. We then interpret experimental observations through a stochastic approach. The latter is designed to embed the action of diverse kinetic modes corresponding to different mechanistic processes taking place across the surface and driving the spatial heterogeneity of the reaction.

How to cite: Recalcati, C., Siena, M., Riva, M., Bollani, M., and Guadagnini, A.: Investigation of mineral dissolution kinetics through Atomic Force Microscopy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3082, https://doi.org/10.5194/egusphere-egu24-3082, 2024.

11:57–12:07

EGU24-10003

ECS

On-site presentation

Applying Thermodynamic Framework to Analyze Transport Self-Organization Due to Dissolution/Precipitation Reaction in Porous Medium: Entropy, Enthalpy, Heterogeneity

Evgeny Shavelzon and Yaniv Edery

Coupled dissolution/precipitation reactive processes in transport in porous media are ubiquitous in a multitude of contexts within the field of Earth sciences, such as geological CO2 and H2 storage, contaminant remediation and acid injection in petroleum reservoirs. In particular, the dynamic interaction between the reaction and solute transport, capable of giving rise to the phenomenon of preferential flow paths, is of a critical importance, as these paths play a dominant role in determining the transport properties of the porous medium; still, the approaches to its characterization remain disputed. The emergence of preferential flow paths in porous media can be considered a manifestation of transport self-organization, as they introduce concentration gradients that distance the system from the state of perfect mixing.

To investigate the dynamic reactive-transport interaction and its influence on transport self-organization within the porous media, we consider a 2D Darcy-scale reactive transport simulation, where dissolution and precipitation of the calcite porous matrix are driven by the injection of a low-pH water. The reactive process alters the transport properties of the porous medium, thus creating the reaction-transport interaction. The coupled reactive-transport process is simulated in a series of computational analyses employing the Lagrangian particle tracking approach, capable of capturing the subtleties of the multiscale heterogeneity phenomena. We employ the thermodynamic framework to investigate the emergence of preferential flow paths as the manifestation of transport self-organization; in particular, we are interested in the relationship between the reaction enthalpy that leads to alteration of the medium's transport properties and the resulting change in the transport self-organization.

For initially homogeneous media, our findings show an increase in transport self-organization with time, along with the emergence of the medium heterogeneity due to interaction between the transport and reactive processes. By studying the influence of the Peclet number on the coupled reactive-transport process, we observe that self-organization is more pronounced in diffusion-dominated flows, characterized by low Peclet values. The hydraulic power, dissipated by the fluid, is shown to increase with the increasing medium heterogeneity, as well as with the mean hydraulic conductivity value. This increase in power, supplied to the fluid, results in an intensification of transport self-organization.

For heterogeneous media, we find again that transport self-organization increases with the evolution of the reactive process, along with an increase in the heterogeneity of the medium; their rates of change depend on the initial heterogeneity of the porous medium. These parameters correlate well with the "useful" reactive enthalpy invested in the reactive process, suggesting the existence of a relation between the energy spent and the transport self-organization gained. The self-organization of the breakthrough times exhibits the opposite tendencies, that can be explained by means of a thermodynamic analogy.

Employing thermodynamic framework to investigate the dynamic reaction-transport interaction in porous media may prove beneficial whenever the need exists to estimate the alteration of the overall transport properties of the medium due to emergence of preferential flow paths due to reactive-transport interaction.

How to cite: Shavelzon, E. and Edery, Y.: Applying Thermodynamic Framework to Analyze Transport Self-Organization Due to Dissolution/Precipitation Reaction in Porous Medium: Entropy, Enthalpy, Heterogeneity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10003, https://doi.org/10.5194/egusphere-egu24-10003, 2024.

12:07–12:17

EGU24-6219

ECS

On-site presentation

Biofilm Growth in Porous Media well approximated by Fractal Multirate Mass Transfer with Advective-Diffusive Solute Exchange

Jingjing Wang, Jesús Carrera, Maarten W. Saaltink, Jordi Petchamé-Guerrero, Graciela S. Herrera, and Cristina Valhondo

Biofilm growth in porous media changes the hydrodynamic properties of the medium: porosity and permeability decrease, and dispersivity increases. However, the first arrival of breakthrough curves (BTCs) is more reduced than derived from the reduction in porosity, and the BTC tail becomes heavier. These observations suggest the need for multicontinuum models (Multi-Rate Mass Transfer, MRMT) which describe reactive transport in heterogeneous porous media and facilitate the simulation of localized reactions often observed within biofilms. Here, we present a conceptual model of biochemical reactive transport with dynamic biofilm growth based on MRMT formulations. The model incorporates microbial growth by updating the porosity, dispersivity, and local mass exchange between mobile water and the immobile biofilm according to the stoichiometry and kinetic rate laws of biochemical reactions. This model has been successfully tested using two sets of laboratory data. We found that (1) the basic model based on the growth of uniformly sized biofilm aggregates (memory function with 1/2 slope), fails to reproduce laboratory tracer tests and rate of biofilm growth, while the fractal growth model, which we obtain by integrating the memory functions of biofilm aggregates with a power law distribution, does; (2) The biofilm memory function evolves as the biofilm grows in response to the varying aggregate size distribution; and (3) the early time portion of eluted volume BTCs are independent of flow rate, whereas the tail becomes heavier when the flow rate is decreased, that both advection controlled and diffusion controlled mass exchange coexist in biofilms.

How to cite: Wang, J., Carrera, J., Saaltink, M. W., Petchamé-Guerrero, J., Herrera, G. S., and Valhondo, C.: Biofilm Growth in Porous Media well approximated by Fractal Multirate Mass Transfer with Advective-Diffusive Solute Exchange, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6219, https://doi.org/10.5194/egusphere-egu24-6219, 2024.

Discussion Post a comment

12:17–12:27

EGU24-18015

ECS

On-site presentation

Linking biogeochemical potential to depositional processes

Vitor Cantarella, Adrian Mellage, and Olaf Cirpka

Biogeochemical reactions are microbially mediated chemical reactions that occur naturally in the subsurface, involving naturally occurring and anthropogenically enriched reactants as well as microbes. These reactions play a crucial role in determining the fate of reactive solutes in groundwater. In Quaternary aquifers, the depositional (sedimentological) processes modulate the composition of the sedimentary matrix, leading to strong spatial variability in both hydraulic and reactive properties. For example, the presence or absence of reduced minerals or organic matter in the sediment matrix determines its “reactivity” with respect to oxidized reactants, auch as dissolved oxygen and nitrate. Additionally, the depositional processes determine properties relevant to groundwater flow, notably the hydraulic conductivity. In this work, we attempt to link depositional processes and the physico-chemical makeup of sediment matrices with the ability of an aquifer to naturally attenuate electron acceptors. We focus on nitrate and denitrification as dissolved electron acceptor and associated biodegradation pathway, respectively. Traditional numerical modeling approaches that account for physical heterogeneity in reactive transport rely on geostatistical methods using, e.g., multi-Gaussian random fields, and often fall short in capturing the link to the geological generating processes. We propose the use of object-based modeling to realistically represent the subsurface's physical characteristics and bridge the gap between geology and biogeochemical potential. Object-based models depict various sedimentary features as 3-D geometries (geo-bodies) within a hierarchical framework. On the largest spatial scale, the model represents strata, corresponding to the sedimentary deposition setting. Within each stratum, facies elements (with internal structure such as crossbedding or layering) representing architectural elements, such as channels or scour-pool fills, are assigned. We illustrate the construction of an object-based aquifer scale groundwater flow model informed via sedimentological descriptions (core logs), integrating field and lab-derived information. Furthermore, we apply a travel-time based reactive transport modelling approach to quantify the effect of the realistic distribution of reactive sedimentary faces on the extent of denitrification. We expect our ongoing analysis to shed light on the quantitative link between the sedimentological architecture of an aquifer and its denitrification potential.

How to cite: Cantarella, V., Mellage, A., and Cirpka, O.: Linking biogeochemical potential to depositional processes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18015, https://doi.org/10.5194/egusphere-egu24-18015, 2024.

12:27–12:30

Conclusion by conveners

Posters on site: Wed, 17 Apr, 16:15–18:00 | Hall A

Display time: Wed, 17 Apr 14:00–Wed, 17 Apr 18:00

Chairpersons: Clement Roques, Ronan Abhervé

A.92

EGU24-14397

OSPP

A Study on the analysis of groundwater flow using thermal and hydrochemical data of groundwater and surface water in the karst area of Samcheok, Korea

Han-Sun Ryu and Heejung Kim

In this study, a study on groundwater flow analysis was conducted using hydrochemical and thermal data to find out the flow of groundwater and pollutant behavior in the karst area and to secure countermeasures for problems related to water quality and water resource stability. The flow characteristics were identified using the study area's overall topographic slope and groundwater map. It is more vulnerable to groundwater pollution because it belongs to the discharge stand where groundwater from the west is discharged into the sea. The vertical hydraulic gradient was measured to confirm the direction of recharge and discharge of groundwater and surface water, and it can be seen that the inflow and outflow of groundwater-surface water is active. In both Gyogokcheon (Gyogok-ri) and Sohancheon (Hamaengbang-ri), the recharge of groundwater tends to be more dominant, and in the case of Sohancheon located in Hamangbang-ri, the recharge of groundwater in summer and winter was more active than in spring and fall. In addition, the residence time of groundwater and the recharge and mixing of surface water according to the flow of groundwater and the behavior of pollutants were analyzed using hydrochemical data. There was a distinct difference in radon concentration values between Gyogokcheon (gneiss-based rock) and Sohancheon (limestone-based rock). In the case of Hamaengbang-ri, radon concentration values were not significantly divided according to surface water, groundwater-surface water mixing section (hyporheic zone), and cave water. In the case of Gyogok-ri, radon concentration was used as one of the indicators to estimate the mixing ratio of groundwater and surface water in the hyporheic zone. This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (grant numbers 2019R1I1A2A01057002 and 2019R1A6A1A03033167). This subject is supported by Korea Ministry of Environment as "The SS(Surface Soil conservation and management) projects; 2019002820004.

How to cite: Ryu, H.-S. and Kim, H.: A Study on the analysis of groundwater flow using thermal and hydrochemical data of groundwater and surface water in the karst area of Samcheok, Korea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14397, https://doi.org/10.5194/egusphere-egu24-14397, 2024.

OSPP judging

A.93

EGU24-12432

Intrinsic permeability of porous systems: models and microfludiic experiments for heterogeneous structures

Wenqiao Jiao, David Scheidweiler, Nolwenn Delouche, Alberto Guadagnini, and Pietro de Anna

Understanding the relationship between flow (Q) and pressure drop (ΔP) for porous media is a long-standing challenge affecting a wide variety of environmental, societal and industrial issues, from soil remediation to enhanced oil recovery. While for homogeneous media such dependence is well represented by the Kozeny-Carman formula, the fundamental nature of such a relationship (Q vs ΔP) within heterogeneous systems, characterized by a broad range of pore sizes, is still not understood. We design a set of controlled and complex porous structures that we use to conduct microfluidics experiments to measure their intrinsic permeability. We synthesize the results upon deriving an analytical formulation relating the overall intrinsic permeability and key features of the porous structure. We propose to embed the spatial variability of pore sizes into the medium permeability by upscaling the flow through each pore, via the Hagen Poiseuille Law. Our prediction fits well the collected data, highlighting the role played by the micro-structure on the overall medium permeability. Furthermore, beside the theoretical understanding of this important relationship, we also extend our set-up to novel experiments focusing on the paradigmatic case study of biofilm growth that affects the system permeability by obstructing the pore spaces.

How to cite: Jiao, W., Scheidweiler, D., Delouche, N., Guadagnini, A., and de Anna, P.: Intrinsic permeability of porous systems: models and microfludiic experiments for heterogeneous structures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12432, https://doi.org/10.5194/egusphere-egu24-12432, 2024.

A.94

EGU24-22487

Numerical Investigation of Shear-Thinning Fluid Flow in Geological Fractures with Variable Aperture Using Finite-Volume and Finite Element Methods

(withdrawn)

Vittorio Di Federico, Alessandro Lenci, Enrico Facca, and Mario Putti

A.95

EGU24-9743

Direct Numerical Simulation of Immiscible Two-phase Flow in Rough Fractures from Viscous to Capillary Fingering – Impact of Flow regime and Structure of the Aperture Field

Insa Neuweiler, Rahul Krishna, Zhibing Yang, and Méheust Yves

Immiscible fluid displacement in rough geological fractures plays a crucial role in various subsurface processes, such as enhanced oil recovery and geological carbon sequestration. In horizontal settings, this displacement is governed by capillary and viscous forces, resulting in the emergence of various displacement patterns as a less viscous fluid displaces a more viscous one (drainage). The macroscopic variables quantifying the flow process differ substantially between the two limit unstable regimes, namely capillary and viscous fingering, for very low and very large capillary numbers, respectively. While there has been extensive investigation of such phenomena in the context of porous media, studies on rough fractures are relatively scarce. In this study, we perform Direct Numerical Simulation (DNS) to analyze the process of drainage by solving the Navier–Stokes equations within the fracture pore space, employing the Volume of Fluid (VOF) method to track the evolution of the fluid-fluid interface. We consider a wide range of Capillary numbers (10^-5 – 10^-2) encompassing both the viscous and capillary dominated regimes, as well as three distinct viscosity ratios (0.8, 0.05 and 0.01), and address realistic synthetic fracture geometries characterized by their Hurst exponent, the ratio of the roughness amplitude to the mean aperture (denoted as the fracture closure), and the correlation scale L_c (i.e., the scale above which the two fracture walls are identical) of the investigated fracture domain. The fracture closure is varied between 0.1 and 1, and L_c between L/32 (aperture field with spatial correlations only at small scales) and L (self-affine aperture field), where L denotes the length of the domain. Starting from the invasion morphologies of the fluid-fluid interface, we examine various pore-scale and macroscopic flow observables, allowing us to systematically characterize the displacement processes of the two-phase system at the hydrodynamic scale. Additionally, flow observables, such as the residual saturation of the displaced fluid and the interfacial area, can be utilized to define the parameter functions of a continuum scale two-phase flow model towards upscaling.

How to cite: Neuweiler, I., Krishna, R., Yang, Z., and Yves, M.: Direct Numerical Simulation of Immiscible Two-phase Flow in Rough Fractures from Viscous to Capillary Fingering – Impact of Flow regime and Structure of the Aperture Field , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9743, https://doi.org/10.5194/egusphere-egu24-9743, 2024.

A.96

EGU24-2723

ECS

Effect of Hydrophobicity on the Transport of Carbon Nanoparticles in Saturated and Unsaturated Porous Media

Bahareh Hassanpour, Daniel May, Laura SinClair, Tammo Steenhuis, and Lawrence Cathles

Carbon-based nanoparticles (CNPs) are increasingly used for environmental and industrial applications such as in pharmaceuticals, energy production, and water and wastewater treatment. Thus, it is crucial to understand their interactions and transport in porous media. Here, we examine the impact of CNP hydrophobicity and porous medium surface area on their transport. We use CNPs that are synthesized from citric acid and ethanolamine and are fluorescent. They exhibit synthesis-temperature-dependent hydrophobicity and were synthesized at four temperatures: 190 °C, 210 °C, 230 °C, and 250 °C. The experiments were conducted by flowing these CNPs in sand-packed columns under saturated and unsaturated conditions. To examine the impact of the surface area of sand on CNP transport, the sands packed in the columns had three surface areas. In addition, a particle transport model in HYDRUS 1D was used to model the transport.

Together, our experimental and modeling noted four important observations. The first observation indicated the importance of hydrophobicity on CNP transport. There was a 55% difference between the recovery of CNPs synthesized at 190 °C compared to those synthesized at 250 °C. Second, a five-fold increase in surface area yielded a 17% decrease in the recovery of CNPs, suggesting the role of sand surface area on CNP recovery. Third, due to the small size of CNPs relative to the water film on the sand surface, there were no significant differences in the mass recovery of CNPs under unsaturated and saturated conditions. Fourth, the particle transport model with a Langmuirian site blocking term successfully simulated the transport of CNPs. There was approximately a 10-fold increase in the adsorption coefficients for hydrophobic CNPs compared to hydrophilic ones. In sum, our observations and modeling demonstrated that hydrophobicity was a major factor that impacted the transport of CNPs.

How to cite: Hassanpour, B., May, D., SinClair, L., Steenhuis, T., and Cathles, L.: Effect of Hydrophobicity on the Transport of Carbon Nanoparticles in Saturated and Unsaturated Porous Media, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2723, https://doi.org/10.5194/egusphere-egu24-2723, 2024.

A.97

EGU24-14733

ECS

Tracing colloidal co-transport in porous media with tailor-made polymers

Nimo Kwarkye, Thomas Ritschel, and Kai Totsche

The soil aqueous phase contains a multitude of dissolved as well as colloidal substances, e.g., organic colloids and clay minerals. Due to their ability to facilitate co-transport, colloids significantly contribute to the fluxes of carbon, nutrients, and contaminants, which renders a thorough consideration of colloids and their mobility a prerequisite for an understanding of soil matter exchange. However, a comprehensive assessment of colloidal transport is often hampered by the heterogeneity of reactions at soil mineral interfaces and the compositional and functional diversity of organic matter in natural soil suspensions. We addressed this challenge by using tailored organic polymers based on poly(ethylene glycol) (PEG) with high reactivity towards clay minerals. Hence, the polymers may be immobilized when clays are exposed on pore walls or mobilized when clay minerals form a colloidal suspension that permits a co-transport of clays and polymers. To unravel the competition between these mechanisms, we investigated the separate and combined transport of PEG and bentonite in column experiments using natural limestone as substrate. Here, PEG was strongly retarded due to adsorption on clay mineral surfaces that were exposed following limestone weathering. In contrast, PEG was highly mobile when transported simultaneously with bentonite and the observed PEG breakthrough resembled that of bentonite, indicating PEG was co-transported. This demonstrates that the application of PEG is promising in the disentanglement of complex transport phenomena in natural porous media, particularly if competition between adsorption sites is decisive for the fate of organic matter.

How to cite: Kwarkye, N., Ritschel, T., and Totsche, K.: Tracing colloidal co-transport in porous media with tailor-made polymers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14733, https://doi.org/10.5194/egusphere-egu24-14733, 2024.

A.98

EGU24-3327

Transport of technology critical elements and other heavy metals originating from phosphogypsum effluents in carbonate aquifer rock materials

(withdrawn)

Ishai Dror, Nitai Amiel, and Brian Berkowitz

A.99

EGU24-5012

OSPP

Evaluating the Behavior of Uranium Through Column Experiments Using Artificial Groundwater and Coaly Slate from a Natural Analogue Study Site in Korea

Soyeon Lim, Hakyung Cho, Suyeong Noh, and Sung-Wook Jeen

The deep geological disposal method is a prominent approach for the management of high-level radioactive waste, and understanding the behavior of uranium under various geochemical conditions is essential for this purpose. To predict the behavior of uranium in the field, it is necessary to evaluate not only the transport of uranium but also the reactions between host rock and groundwater at the field site. In this regard, we evaluated the behavior of uranium in the underground environment by analyzing the temporal and spatial changes in uranium geochemistry in response to water-rock reactions. This was achieved through column experiments using rocks containing uranium ore bodies and groundwater from a natural analogue study site in Korea. Two columns (NA-PJ1 and NA-PJ2) were prepared by collecting coaly slate materials containing uranium minerals sourced from the Okcheon Metamorphic Belt in Korea. NA-PJ1 was filled with coaly slate (0.025 ~ 2 mm grain size) collected from the study area, while NA-PJ2 included a mixture of coaly slate and limestone (10 wt%) to provide pH buffering. The input solutions to the columns were artificial groundwater manufactured with a chemistry similar to that of the groundwater at the study site. The artificial groundwater was purged with Ar gas before the experiment to minimize the ingress of dissolved oxygen (DO) from the atmosphere. To observe spatial and temporal changes in geochemistry resulting from the interactions between the artificial groundwater and the reactive materials inside the columns, water samplings were performed at 0, 5, 10, 15, 20, 25, 30, 35, and 40 cm from the column influent. The results consistently showed low and stable DO concentrations in both columns. The pH in NA-PJ1 initially exhibited the highest value at 0 cm but gradually decreased to below 4.5. This was attributed to the insufficient carbonate buffering capacity to neutralize hydrogen ions generated by the oxidation of iron sulfide in coaly slate. In NA-PJ2, in contrast, the pH remained around 8. Uranium concentration in NA-PJ1 increased gradually with distance. It was determined that uranium was released through the dissolution of uranium minerals (i.e., uraninite and ekanite). Subsequently, the released uranium formed uranium aqueous complexes with dissolved F or SO₄ induced by iron sulfide oxidation. Furthermore, it was shown that uranium in NA-PJ1 formed UO₂CO₃(aq) complexes closer to the column influent, while it formed more UO₂SO₄(aq) complexes with increasing distance. This study contributes to understanding the transport and reaction characteristics of uranium in groundwater, ultimately aiding in the management of high-level radioactive waste in a deep geological disposal site.

How to cite: Lim, S., Cho, H., Noh, S., and Jeen, S.-W.: Evaluating the Behavior of Uranium Through Column Experiments Using Artificial Groundwater and Coaly Slate from a Natural Analogue Study Site in Korea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5012, https://doi.org/10.5194/egusphere-egu24-5012, 2024.

OSPP judging

A.100

EGU24-6871

ECS

OSPP

The advantages and considerations of applying dual tracers in SWPP tests

Nam-Ryeong Lee, Ji-Young Baek, and Kang-Kun Lee

The Single-Well Push-Pull (SWPP) test is a cost-effective tracer test that has been widely used for aquifer characterization. There is an advantage in concurrently utilizing heat and solute tracers for a comprehensive understanding of the hydraulic and thermal characteristics of the aquifer. However, the application of both tracers in SWPP tests has yet to be commonly used due to their particularity in setting experimental conditions such as drift time and the use of chaser. In this research, dual-tracer SWPP tests were conducted in a laboratory scale using sand (d₅₀ = 0.84 mm, U = 2.06) under six different seepage velocities (v_s = 17.5 ― 59.7 m/d), with relative drift time as the variable. As tracers, a sodium chloride solution with a concentration of 1000 ppm and a temperature difference of approximately 6℃ from the background water temperature was employed. Obtained EC and temperature time series data were analyzed by several analytical models. The estimates from analytical models (seepage velocity, porosity, volumetric heat capacity) were compared to those from measurements to evaluate the applicability of a single analytical model on dual-tracer SWPP test. Preliminary experimental results showed that slower velocities and shorter drift times resulted in higher recovery rates but also led to larger error rates in estimates for the solute tracer. Building upon a solute tracer, more accurate analytical models suitable for the current experimental setup were identified, and subsequently extended to the heat tracer for further analysis. Based on the interpretation of both tracers, appropriate test conditions for dual-tracer SWPP tests will be proposed. We anticipate to offer a deeper understanding of the benefits and considerations associated with the combined use of heat and solute tracers for the thorough evaluation of aquifer characteristics during push-pull tests.

Keywords: Single-well push-pull test, Laboratory experiments, Heat tracer, Solute tracer

Acknowledgements : This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2022R1A2C1006696). This work was also supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government(MSIT) (No. 2022R1A5A1085103). This work was also supported by the Nuclear Research and Development Program of the National Research Foundation of Korea (NRF-2021M2E1A1085200).

How to cite: Lee, N.-R., Baek, J.-Y., and Lee, K.-K.: The advantages and considerations of applying dual tracers in SWPP tests , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6871, https://doi.org/10.5194/egusphere-egu24-6871, 2024.

OSPP judging

A.101

EGU24-14769

ECS

Prediction of As behavior in a vadose zone using an empirical relationship between As retardation factor and the soil properties

Sang Hyun Kim, Tho Huynh Huu Tran, Jaeshik Chung, and Seunghak Lee

Arsenic (As) pollution in soil from various anthropogenic sources potentially threatens groundwater by migrating downward through a vadose zone. As goes through complex biogeochemical reactions such as sorption, desorption, and/or redox transformation, which affects its retention in this zone. A retardation factor is a critical solute-transport parameter to quantitatively assess the retention of As in this zone, and eventually to predict the potential risk of groundwater contamination. Despite its importance, however, there is still limited information to quantify the retardation factor in a vadose zone, compared to in the saturated condition. This study aimed to assess the retardation factor of As using twenty-two unsaturated soil columns coupled with the non-equilibrium solute-transport modeling. We employed a multiple linear regression approach to develop a prediction model for the retardation factor based on the soil properties. Soil columns with 3-cm inner diameter and 45-cm height were packed with six different field soils at various bulk densities. Distilled water was infiltrated into each column at a constant flowrate, until a steady-state unsaturated condition was achieved. The distilled water was replaced with a solution containing As and a conservative tracer (chloride, Cl), to obtain their breakthrough curves. The retardation factor of As was determined by inversely fitting the breakthrough data of As and Cl with Mobile-Immobile model integrated in HYDRUS 1-D software. The derived retardation factors of As in the mobile and immobile zones ranged 1.58–6.93 and 1.44–25.48, respectively. These showed high degree of dependence on soil properties. In the mobile water zone, iron content and organic matter content emerged as the two most influential properties affecting As transport, impeding As mobility. Conversely, in the immobile water zone, coefficient of uniformity and bulk density were identified as the most influential factors, enhancing As retention. Based on the results, empirical equations were derived to predict the retardation factors of As in a vadose zone based on the aforementioned soil properties.

How to cite: Kim, S. H., Tran, T. H. H., Chung, J., and Lee, S.: Prediction of As behavior in a vadose zone using an empirical relationship between As retardation factor and the soil properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14769, https://doi.org/10.5194/egusphere-egu24-14769, 2024.

A.102

EGU24-9577

ECS

Heat transfer modeling in karst environments to study the impact of climate change on the future of decorated caves

Clément Artigue and Claude Mugler

The effects of global warming have already been recorded in many decorated caves located in karst systems, and some prehistoric paintings are already deteriorating. Modeling the microclimate of caves under various climate change scenarios will enable to adapt the conservation strategy for rock art heritage.

The first step in this modeling approach is to simulate heat transfer from the surface to the cave through the soil/epikarst/karst system. The rock characteristics in the model are calibrated using sensor data taken at various depths in the soil and in the karst over a few years, and in the cave thanks to long-term monitoring. To provide long-term climate forcing, a transfer function is established between meteorological data measured at a height of 2 meters by Météo France and the temperature measured at the ground surface.

Then, this heat transfer model is fed with projections from regional climate downscaling models. This modeling approach, which integrates both current data and climate projections, will be a significant step towards the effective management and conservation of decorated caves, which are not only geological wonders but also hold critical historical and archaeological significance.

How to cite: Artigue, C. and Mugler, C.: Heat transfer modeling in karst environments to study the impact of climate change on the future of decorated caves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9577, https://doi.org/10.5194/egusphere-egu24-9577, 2024.

A.103

EGU24-17262

ECS

Effect of velocity fluctuations on pore scale stretching kinematics in 3D porous media

Manuel Maeritz, Joris Heyman, Tanguy Le Borgne, and Marco Dentz

Fluid stretching plays an important role in controlling mixing dynamics in porous media. Recent advances have shown that stretching at pore scale in 3D porous media is chaotic, leading to exponential elongation of mixing interfaces [e.g. 1,2]. Yet, it is not known how the associated stretching rate depend on the pore scale velocity heterogeneity. In this study, we perform particle tracking simulations in a periodic flow fields to investigate how flow heterogeneity control the transient evolution of the stretching rate as well as the asymptotic stretching rate (Lyapunov exponent). Our results reveal that rare low velocity events have a significant impact on the Lyapunov exponent, while these regions are numerically more difficult to treat and thus sometimes excluded from statistics [1]. Moreover, we discuss conceptual difficulties associated to velocity pdf with heavy tails towards low velocities: Ensemble averages of the deformation gradient tensor do not converge under these conditions when taken them at equal advective distances, as opposed to at equal times. As a consequence, the meaning of the steady state stretching rate must be discussed in the context of long memories. Using Continuous Time Random Walks (CTRW) we derive analytical expressions for the averages and discuss low velocity cutoffs to guarantee convergence. We further discuss the nature of the pre-asymptotic stretching kinematics, which can have a dominant effect on mixing processes. We show that the strength of the transient is controlled by the typical shear rate while the duration is determined by the Lyapunov exponent. Weaker chaotic stretching are associated to a longer lasting transient regime.

[1]: Turuban et al. (2019) In: JFM
[2]: Heyman et al. (2020) In: PNAS

How to cite: Maeritz, M., Heyman, J., Le Borgne, T., and Dentz, M.: Effect of velocity fluctuations on pore scale stretching kinematics in 3D porous media, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17262, https://doi.org/10.5194/egusphere-egu24-17262, 2024.

A.104

EGU24-5519

Simulating pore-scale nonlinear reactions at the fluid-solid interface using random walk particle tracking

Tomas Aquino

Random walk particle tracking (RWPT) methods employ a Lagrangian discretization of solute plumes into point particles to numerically solve the advection-dispersion equation. Their recognized advantages over more traditional grid-based Eulerian methods regarding numerical stability and numerical dispersion make them ideal candidates to simulate complex reactive fronts in heterogeneous media. However, handling nontrivial boundary conditions remains a challenge, restricting the range of interface processes that can be simulated. We derive and validate a new collision-based approach to implement a broad class of generalized Robin-type boundary conditions, representing the balance between diffusive fluxes and an arbitrary nonlinear function of the transported and surface reactant concentrations. This formulation allows for modeling arbitrary coupled sets of nonlinear surface reactions within the classical RWPT framework, thus opening new opportunities for simulating pore-scale reactive transport in the subsurface. The collision-based nature of the proposed technique allows for estimating surface reaction rates based on single-particle collisions with the reactive interface. Thus, it does not require concentration field reconstructions or multi-particle searches. We verify the method for a coupled set of nonlinear mass-action reactions under pure diffusion and for nonlinear kinetics representing calcite dissolution in a model porous medium.

How to cite: Aquino, T.: Simulating pore-scale nonlinear reactions at the fluid-solid interface using random walk particle tracking, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5519, https://doi.org/10.5194/egusphere-egu24-5519, 2024.

A.105

EGU24-5705

ECS

OSPP

Unraveling biogeochemical transformation of organic carbon and nitrogen compounds in groundwater along a hill slope transect

Thanh Quynh Duong, Anke Hildebrandt, and Martin Thullner

The origin and the fate of organic carbon and nitrogen compounds in groundwater play an important role in the global biogeochemical cycling of carbon and nutrients and have implications for drinking water production. While the input of these compounds into the subsurface is strongly driven by land use, their fate in subsurface environments such as fractured aquifers is controlled by a complex interplay between hydrological and biogeochemical processes at different temporal and spatial scales and is poorly understood yet. Determining the fate of these organic compounds in fractured aquifers is additionally challenging due to spatial heterogeneities at various scales down to centimeter scales, leading to a multitude of flow paths of different lengths and residence times. This causes an overlap of solute residence times for compounds moving from the surface through the subsurface to surface waters or groundwater observation wells, stretching from days to many years, thus affecting the dynamics of the biogeochemical processes and the quantitative assessment of compound fluxes. To address this issue, a travel time-based modeling approach is employed to simulate the fate of carbon and nitrogen compounds in groundwater along a hill slope transect of the Hainich Critical Zone Exploratory (CZE), located northwest of Thuringia (central Germany). This transect is set up under the Collaborative Research Center AQUADIVA. It is subject to an intensive surface and subsurface monitoring program providing groundwater quality and quantity data. Travel time distributions obtained from a numerical groundwater flow model of the transect and its vicinity are combined with a set of numerical 1D simulations describing the biogeochemical transformations of carbon and nitrogen. The simulated complex reaction network describes the transformation of carbon and nitrogen along individual groundwater flow paths, which considers varying microbial functional groups such as aerobes and anaerobes, as well as key microbial life processes under different redox conditions, including aerobic, nitrate-reducing, ammonia-oxidizing, and sulfate-reducing conditions. The model-predicted concentrations of reactive species at various observation wells are compared to measured concentrations to validate the approach. The results show that processes on the surface strongly shape the dynamics of resulting recharge zones represented by different land use areas, which have an impact on observed concentrations at wells. Travel time distributions combined with simulations of the biogeochemical transformation along a flow path can provide a model-based interpretation of measured observations and the factors controlling them. This allows predicting fluxes of chemical species through the entire sub-catchment and their dependency on the dynamics of surface conditions.

How to cite: Duong, T. Q., Hildebrandt, A., and Thullner, M.: Unraveling biogeochemical transformation of organic carbon and nitrogen compounds in groundwater along a hill slope transect, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5705, https://doi.org/10.5194/egusphere-egu24-5705, 2024.

OSPP judging

A.106

EGU24-10397

ECS

Impact of Sharp Interfaces on Biofilm Growth: Insights from Mixing Processes in a Flow-Through Column Experiment.

Michela Trabucchi, Paula Rodriguez Escales, Xavier Sanchez Vila, Jesus Carrera, and Daniel Fernandez Garcia

Biofilms in porous media host microbial communities that play a central role in the degradation of nutrients and Contaminants of Emerging Concern. Their importance for promoting contaminants removal in the context of Natural Based Solutions is acknowledged, but we still lack a complete understanding and quantification of biofilm growth dynamics in porous media, and their impact on flow and transport behavior.

In this context, we aim to investigate the effects of sharp interfaces on the spatial and temporal distribution of biofilms growth and their subsequent role in the evolution of flow and transport properties. For this purpose, we conduct flow-through experiments in sand-packed columns characterized by two homogeneous porous media separated by a sharp interface. We inject electron acceptor and electron donor solutions sequentially and multiple times. This creates multiple reactive mixing zones that flow and evolve through the system, depending on the porous medium. The high-resolution monitoring system enables the quantification of biofilm activity, as well as changes in hydraulic conductivity over time and at different sections of the column. Additionally, image analysis allows for the evaluation of the spatial distribution of biofilm growth over time, while breakthrough curve concentrations derived from several tracer tests provide further insights into overall transport parameter changes.

How to cite: Trabucchi, M., Rodriguez Escales, P., Sanchez Vila, X., Carrera, J., and Fernandez Garcia, D.: Impact of Sharp Interfaces on Biofilm Growth: Insights from Mixing Processes in a Flow-Through Column Experiment., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10397, https://doi.org/10.5194/egusphere-egu24-10397, 2024.

A.107

EGU24-10720

Spatial structure, chemotaxis and quorum sensing shape bacterial biomass accumulation in complex porous media

(withdrawn)

Pietro de Anna, David Scheidweiler, Ankur Bordoloi, Wenqiao Jiao, Vladimir Sentchilo, Monica Bollani, Audam Chhun, and Philipp Engel