Reactive transport modeling Research Papers (original) (raw)

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- Reactive transport modeling, Soil sciences, Vadose Zone Modeling

Abstract: Regional modeling of subsurface cadmium and zinc transport in a diffusely polluted area in the south of the Netherlands is the subject of this study. The atmospheric deposition of cadmium and zinc was caused by three zinc-ore... more

- by Manuel Marcoux
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- Mechanical Engineering, Materials Science, Biomedical Engineering, Biomechanics

This paper is addressed to the TOUGH2 user community. It presents a new tool for handling simulations run with the TOUGH2 code with specific application to CO 2 geological storage. This tool is composed of separate FORTRAN subroutines (or modules) that can be run independently using input and output files in ASCII format for TOUGH2. These modules have been developed specifically for modeling of carbon dioxide geological storage and their use with TOUGH2 and the Equation of State module ECO2N, dedicated to CO 2 -water-salt mixture systems, with TOUGHREACT, which is an adaptation of TOUGH2 with ECO2N and geochemical fluid-rock interactions, and with TOUGH2 and the EOS7C module dedicated to CO 2 -CH 4 gas mixture is described. The objective is to save time for the pre-processing, execution and visualization of complex geometry for geological system representation. The workflow is rapid and user-friendly and future implementation to other TOUGH2 EOS modules for other contexts (e.g. nuclear waste disposal, geothermal production) is straightforward. Three examples are shown for validation: i) leakage of CO 2 up through an abandoned well, ii) 3D reactive transport modeling of CO 2 in a sandy aquifer formation in the Sleipner gas Field, (North Sea, Norway), and iii) an estimation of enhanced gas recovery technology using CO 2 as the injected and stored gas to produce methane in the K12B Gas Field (North Sea, Denmark).

- by Pascal Audigane and +1
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- Engineering, Earth Sciences, Carbon Dioxide, Multiphase Flow

This paper attempts to establish the fact that Proactive transport protocols are better than conventional Reactive transport protocols in terms of overall utilization of resources. This has been proved analytically in this paper using a mathematical model developed for proactive congestion avoidance. The paper also provides a mathematical framework for Proactive Transport Protocol and predicts the congestion window evolution and throughput achieved by single and multiple proactive TCP flows. The congestion window evolution and throughput of a Proactive TCP connection are modeled as functions of the bandwidth, delay, packet size, number of concurrent TCP flows and the penalty factor used by the proactive protocols. Results obtained from the model are verified with ns2 simulation. The optimal value of the penalty factor is derived mathematically from the designed model. It has also been shown how the derived optimal values enhances the performance of the protocol and almost a near maximum utilization of resources is achieved by extensive simulation in ns2 considering both single and multiple TCP flows.

- by Haleem Farman
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- Mobile Ad Hoc Networks, Routing, Routing protocols, Reactive transport modeling

One approach for utilizing geoscience models for management or policy analysis is via a simulationbased optimization framework-where an underlying model is linked with an optimization search algorithm. In this regard, MATLAB and Python are high-level programming languages that implement numerous optimization routines, including gradient-based, heuristic, and direct-search optimizers. The ever-expanding number of available algorithms makes it challenging for practitioners to identify optimizers that deliver good performance when applied to problems of interest. Thus, the primary contribution of this paper is to present a series of numerical experiments that investigated the performance of various MATLAB and Python optimizers. The experiments considered two simulationbased optimization case studies involving groundwater flow and contaminant transport. One case study examined the design of a pump-and-treat system for groundwater remediation, while the other considered least-squares calibration of a model of strontium (Sr) transport. Using these case studies, the performance of 12 different MATLAB and Python optimizers was compared. Overall, the Hooke-Jeeves direct search algorithm yielded the best performance in terms of identifying least-cost and best-fit solutions to the design and calibration problems, respectively. The IFFCO (implicit filtering for constrained optimization) direct search algorithm and the dynamically dimensioned search (DDS) heuristic algorithm also consistently yielded good performance and were up to 80% more efficient than Hooke-Jeeves when applied to the pump-and-treat problem. These results provide empirical evidence that, relative to gradient-and population-based alternatives, direct search algorithms and heuristic variants, such as DDS, are good choices for application to simulation-based optimization problems involving groundwater management.

- by Kenny Leung
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- Engineering, Earth Sciences, Policy Analysis, Reactive transport modeling

The past decade has seen considerable progress in the development of models simulating pesticide transport in structured soils subject to preferential flow (PF). Most PF pesticide transport models are based on the two-region concept and usually assume one (vertical) dimensional flow and transport. Stochastic parameter sets are sometimes used to account for the effects of spatial variability at the field scale. In the past decade, PF pesticide models were also coupled with Geographical Information Systems (GIS) and groundwater flow models for application at the catchment and larger regional scales. A review of PF pesticide model applications reveals that the principal difficulty of their application is still the appropriate parameterization of PF and pesticide processes. Experimental solution strategies involve improving measurement techniques and experimental designs. Model strategies aim at enhancing process descriptions, studying parameter sensitivity, uncertainty, inverse parameter identification, model calibration, and effects of spatial variability, as well as generating model emulators and databases. Model comparison studies demonstrated that, after calibration, PF pesticide models clearly outperform chromatographic models for structured soils. Considering nonlinear and kinetic sorption reactions further enhanced the pesticide transport description. However, inverse techniques combined with typically available experimental data are often limited in their ability to simultaneously identify parameters for describing PF, sorption, degradation and other processes. On the other hand, the predictive capacity of uncalibrated PF pesticide models currently allows at best an approximate (order-of-magnitude) estimation of concentrations. Moreover, models should target the entire soil-plant-atmosphere system, including often neglected above-ground processes such as pesticide volatilization, interception, sorption to plant residues, root uptake, and losses by runoff. The conclusions compile progress, problems, and future research choices for modelling pesticide displacement in structured soils.

- by fei hua
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- Information Systems, Soil, Biofilms, Water resources

Aqueous Co(II) chloride complexes play a crucial role in cobalt transport and deposition in ore-forming hydrothermal systems, ore processing plants, and in the corrosion of special Co-bearing alloys. Reactive transport modelling of cobalt in hydrothermal fluids relies on the availability of thermodynamic properties for Co complexes over a wide range of temperature, pressure and salinity. Synchrotron X-ray absorption spectroscopy was used to determine the speciation of cobalt(II) in 0-6 m chloride solutions at temperatures between 35 and 440°C at a constant pressure of 600 bar. Qualitative analysis of XANES spectra shows that octahedral species predominate in solution at 35°C, while tetrahedral species become increasingly important with increasing temperature. Ab initio XANES calculations and EXAFS analyses suggest that in high temperature solutions the main species at high salinity (Cl:Co >> 2) is CoCl 4 2À , while a lower order tetrahedral complex, most likely CoCl 2 (H 2 O) 2(aq) , predominates at low salinity (Cl:Co ratios 2).EXAFSanalysesfurtherrevealedthebondingdistancesfortheoctahedralCo(H2O)62+(octCo−O=2.075(19)A˚),tetrahedralCoCl42Aˋ(tetCo−Cl=2.252(19)A˚)andtetrahedralCoCl2(H2O)2(aq)(tetCo−O=2.038(54)A˚andtetCo−Cl=2.210(56)A˚).AnanalysisoftheCo(II)speciationinsodiumbromidesolutionsshowsasimilartrend,withtetrahedralbromidecomplexesbecomingpredominantathighertemperature/salinitythaninthechloridesystem.EXAFSanalysisconfirmsthatthelimitingcomplexathighbromideconcentrationathightemperatureisCoBr42Aˋ.Finally,XANESspectrawereusedtoderivethethermodynamicpropertiesfortheCoCl42AˋandCoCl2(H2O)2(aq)complexes,enablingthermodynamicmodellingofcobalttransportinhydrothermalfluids.SolubilitycalculationsshowthattetrahedralCoCl42Aˋisresponsiblefortransportofcobaltinhydrothermalsolutionswithmoderatechlorideconcentration(2). EXAFS analyses further revealed the bonding distances for the octahedral Co(H 2 O) 6 2+ ( oct Co-O = 2.075(19) Å ), tetrahedral CoCl 4 2À ( tet Co-Cl = 2.252(19) Å ) and tetrahedral CoCl 2 (H 2 O) 2(aq) ( tet Co-O = 2.038(54) Å and tet Co-Cl = 2.210(56) Å ). An analysis of the Co(II) speciation in sodium bromide solutions shows a similar trend, with tetrahedral bromide complexes becoming predominant at higher temperature/salinity than in the chloride system. EXAFS analysis confirms that the limiting complex at high bromide concentration at high temperature is CoBr 4 2À . Finally, XANES spectra were used to derive the thermodynamic properties for the CoCl 4 2À and CoCl 2 (H 2 O) 2(aq) complexes, enabling thermodynamic modelling of cobalt transport in hydrothermal fluids. Solubility calculations show that tetrahedral CoCl 4 2À is responsible for transport of cobalt in hydrothermal solutions with moderate chloride concentration (2).EXAFSanalysesfurtherrevealedthebondingdistancesfortheoctahedralCo(H2O)62+(octCo−O=2.075(19)A˚),tetrahedralCoCl42Aˋ(tetCo−Cl=2.252(19)A˚)andtetrahedralCoCl2(H2O)2(aq)(tetCo−O=2.038(54)A˚andtetCo−Cl=2.210(56)A˚).AnanalysisoftheCo(II)speciationinsodiumbromidesolutionsshowsasimilartrend,withtetrahedralbromidecomplexesbecomingpredominantathighertemperature/salinitythaninthechloridesystem.EXAFSanalysisconfirmsthatthelimitingcomplexathighbromideconcentrationathightemperatureisCoBr42Aˋ.Finally,XANESspectrawereusedtoderivethethermodynamicpropertiesfortheCoCl42AˋandCoCl2(H2O)2(aq)complexes,enablingthermodynamicmodellingofcobalttransportinhydrothermalfluids.SolubilitycalculationsshowthattetrahedralCoCl42Aˋisresponsiblefortransportofcobaltinhydrothermalsolutionswithmoderatechlorideconcentration(2 m NaCl) at temperatures of 250°C and higher, and both cooling and dilution processes can cause deposition of cobalt from hydrothermal fluids.

- by D. Testemale
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- Geology, Geochemistry, Thermodynamics, X ray absorption spectroscopy

Multi-phase reactive flow and transport modeling is an effective tool for monitoring, verification, and accounting of CO 2 sequestration in deep geological formations. In the current study, modeling is performed to simulate large scale CO 2 injection (a million tons per year for 100 years) into Mt. Simon sandstone, a major candidate saline reservoir in the Midwest of USA. The long term fate of CO 2 was simulated by extending the modeling period to 10,000 years. The results indicate that most of the injected CO 2 remains within a radius of 3300 m lateral distribution. Four major trapping mechanisms and their spatial and temporal variations are evaluated in our simulations: hydrodynamic, solubility, residual, and mineral trapping. A strongly acidified zone (pH 3-5) forms in the areas affected by the injected CO 2 (0-3300 m), and consequently causes extensive mineral precipitation and dissolution. The predicted long-term fate of CO 2 is closely linked to the geochemical reactions conceptualized in the models. In our model, the replenishing upstream water continues to dissolve CO 2 long after the injection, which results in total dissolution of hydrodynamically trapped CO 2 at the end of 10,000 years. In contrast, most previous models neglected the regional flow after injection and hence artificially limited the extent of geochemical reactions as if in a batch system. Consequently, a supercritical CO 2 plume (hydrodynamic trapping) would persist after 10,000 years. The continued supply of acidified water from interaction between replenishing water and CO 2 also results in extensive dissolution of feldspars and precipitation of secondary clay minerals, to a much more extent than what predicted in models without including regional flow. However, the prediction of complete dissolution of feldspars in 10,000 years can also result from the artifact that the linear rate laws are used in our model (as well as all previous work), which overestimates the rates of feldspar dissolution near equilibrium. Nevertheless, our simulations indicate the prolonged existence of an acidic brine plume, which suggests long-term risk assessment should transfer from the primary risk of CO 2 leakage to secondary risk of acidic plume leakage after all CO 2 is dissolved.

- by faye liu
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- Reactive transport modeling, CO2 sequestration

A general description of the mathematical and numerical formulations used in modern numerical reactive transport codes relevant for subsurface environmental simulations is presented. The formulations are followed by short descriptions of commonly used and available subsurface simulators that consider continuum representations of flow, transport, and reactions in porous media. These formulations are applicable to most of the subsurface environmental benchmark problems included in this special issue. The list of codes described briefly here includes PHREEQC, HPx, PHT3D, OpenGeoSys (OGS), HYTEC, ORCHESTRA, TOUGHREACT, eSTOMP, HYDROGEOCHEM, Crunch-Flow, MIN3P, and PFLOTRAN. The descriptions include a C. I. Steefel () · B. Arora · S. Molins · N. Spycher high-level list of capabilities for each of the codes, along with a selective list of applications that highlight their capabilities and historical development.

- by Diederik Jacques
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- Reactive transport modeling

This paper presents a 2D reactive transport model of long-term geological storage of carbon dioxide. A data set from the Utsira formation in Sleipner (North Sea) is utilized for geochemical simulation, while the aquifer is approximated as a 2D cylindrically symmetric system. Using the reactive transport code TOUGHREACT, a 25 year injection scenario followed by a 10 000 year storage period are simulated. Supercritical CO 2 migration, dissolution of the CO 2 in the brine, and geochemical reactions with the host rock are considered in the model. Two mineralogical assemblages are considered in the Utsira formation, a sand formation that is highly permeable and a shale formation representing four semi-permeable layers in the system that reduce the upward migration of the supercritical CO 2 . The impacts of mineral dissolution and precipitation on porosity are calculated. Furthermore, the 2D cylindrical geometry of the mesh allows simulating both the upward migration of the supercritical gas bubble as well as the downward migration of the brine containing dissolved CO 2 . A mass balance of the CO 2 stored in, respectively, the supercritical phase, dissolved in the aqueous phase, and sequestered in solid mineral phases (carbonate precipitation) is calculated over time. Simulations with a lower residual gas 1 hal-00564444, version 1 -

- by Pascal Audigane and +1
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- Geology, Geochemistry, Geophysics, Reactive transport modeling

To demonstrate the potential for geologic storage of CO 2 in saline aquifers, the Frio-I Brine Pilot was conducted, during which 1600 tons of CO 2 were injected into a high-permeability sandstone and the resulting subsurface plume of CO 2 was monitored using a variety of hydrogeological, geophysical, and geochemical techniques. Fluid samples were obtained before CO 2 injection for baseline geochemical characterization, during the CO 2 injection to track its breakthrough at a nearby observation well, and after injection to investigate changes in fluid composition and potential leakage into an overlying zone. Following CO 2 breakthrough at the observation well, brine samples showed sharp drops in pH, pronounced increases in HCO 3 and aqueous Fe, and significant shifts in the isotopic compositions of H 2 O and dissolved inorganic carbon. Based on a calibrated 1-D radial flow model, reactive transport modeling was performed for the Frio-I Brine Pilot. A simple kinetic model of Fe release from the solid to aqueous phase was developed, which can reproduce the observed increases in aqueous Fe concentration. Brine samples collected after half a year had lower Fe concentrations due to carbonate precipitation, and this trend can be also captured by our modeling. The paper provides a method for estimating potential mobile Fe inventory, and its bounding concentration in the storage formation from limited observation data. Long-term simulations show that the CO 2 plume gradually spreads outward due to capillary forces, and the gas saturation gradually decreases due to its dissolution and precipitation of carbonates. The gas phase is predicted to disappear after 500 years. Elevated aqueous CO 2 concentrations remain for a longer time, but eventually decrease due to carbonate precipitation. For the Frio-I Brine Pilot, all injected CO 2 could ultimately be sequestered as carbonate minerals.

- by Christine Doughty and +2
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- Geology, Geochemistry, Chemical Geology, Water Chemistry

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- by George Tchobanoglous
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- Water, Biomass, Modeling, Water Purification

The injection of CO2 in exploited natural gas reservoirs as a means to reduce greenhouse gas (GHG) emissions is highly attractive as it takes place in well-known geological structures of proven integrity with respect to gas leakage. The injection of a reactive gas such as CO2 puts emphasis on the possible alteration of reservoir and caprock formations and especially of the wells’ cement sheaths induced by the modification of chemical equilibria. Such studies are important for injectivity assurance, wellbore integrity, and risk assessment required for CO2 sequestration site qualification. Within a R&D project funded by Eni, we set up a numerical model to investigate the rock–cement alterations driven by the injection of CO2 into a depleted sweet natural gas pool. The simulations are performed with the TOUGHREACT simulator (Xu et al. in Comput Geosci 32:145–165, 2006) coupled to the TMGAS EOS module (Battistelli and Marcolini in Int J Greenh Gas Control 3:481–493, 2009) developed for the TOUGH2 family of reservoir simulators (Pruess et al. in TOUGH2 User’s Guide, Version 2.0, 1999). On the basis of field data, the system is considered in isothermal (50°C) and isobaric (128.5 bar) conditions. The effects of the evolving reservoir gas composition are taken into account before, during, and after CO2 injection. Fully water-saturated conditions were assumed for the cement sheath and caprock domains. The gas phase does not flow by advection from the reservoir into the interacting domains so that molecular diffusion in the aqueous phase is the most important process controlling the mass transport occurring in the system under study.

- by claudio geloni
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- Chemical Engineering, Civil Engineering, Applied Mathematics, Carbon Dioxide

In the near field of a radioactive waste repository, bentonite is often used as a buffer material to prevent the migration of hazardous radionuclides into the biosphere. Traditionally the retardation mechanisms are simplified into a linear isotherm concept. The corresponding KD value is thereafter used for safety assessment purposes. Often, due to the lack of experimental data, the retardation based on the formation of solid solutions is ignored and only cation exchange and surface complexation processes are considered in evaluating KDs. In this contribution, we use the newly coupled code GeoSys-GEM to simulate the reactive transport of radium in a bentonite column. In a first step, a chemical model was set up which contained non-ideal radium, barium, and strontium sulfate and carbonate solid solutions. Our reactive transport simulations suggest that the formation of such solid solutions strongly contributes to the retardation of radium. The aqueous Ra2+ concentration will be lower ...

Present strategies for the long-term disposal of high-level nuclear wastes are based on the construction of repositories hundreds of meters below the earth surface. Although the surrounding host-rocks are relatively isolated from the light at the earth surface they are by no means lifeless. Microorganisms rule the deep part of the biosphere and it is well established that their activity can alter chemical and physical properties of these environments. Microbial processes can directly and indirectly affect radionuclide migration in multiple ways. Within 6th FP IP FUNMIG the interplay between microbial biofilms and radionuclides and the effect of microbially induced redox transformations of Fe on radionuclide mobility have been investigated. For the first time, formation of U(V) as a consequence of microbial U(VI) reduction in a multi-species biofilm was detected in vivo by combining laser fluorescence spectroscopy and confocal laser scanning microscopy. Furthermore, it was demonstrated that addition of U(VI) can lead to increased respiratory activity in a biofilm. Increased respiration in a biofilm can create microenvironments with lower redox potential, and hence induce reduction of radionuclides. Transient mobilization of U was observed in experiments with Fe oxides containing adsorbed U(VI) in which the activity of SO 4reducing organisms was mimicked by sulfide addition. Faster reaction of sulfide with Fe oxides compared to U(VI) reduction, and decreasing U(VI) adsorption due to the transformation of Fe oxides into FeS can explain the observed intermittent U mobilization. The presented research on microbe-radionuclide interactions performed within FUNMIG addresses only a few aspects of the potential role of microorganisms in the performance assessment of nuclear waste repositories. For this reason, additionally, this article provides a cursory overview of microbial processes which were not studied within the FUNMIG project but are relevant in the context of performance assessment. The following aspects are presented: (a) the occurrence and metabolic activity of microorganisms of several proposed types of host-rocks, (b) the potential importance of microorganisms in the near-field of nuclear waste repositories, (c) indirect effects of microbial processes on radionuclide mobility in the repository far-field, (d) binding of radionuclides to microbial biomass, (e) microbial redox transformations of radionuclides, and (f) the implementation of microbial processes in reactive transport models for radionuclide migration.

- by Thilo Behrends and +1
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- Geochemistry, Fluorescence Spectroscopy, Performance Assessment, Reactive transport modeling

- by Robin Gerlach
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- Information Systems, Spatial Analysis, Biofilms, Kinetics

We present ESCRIPT-RT, a new reactive transport simulation code for fully saturated porous media which is based on a finite element method (FEM) combined with three other components: (i) a Gibbs minimisation solver for equilibrium modelling of fluid-rock interactions, (ii) an equation of state for pure water to calculate fluid properties and (iii) a thermodynamically consistent material database to determine rocks' material properties. Using decoupling of most of the standard governing equations, this code solves sequentially for temperature, pressure, mass transport and chemical equilibrium. In contrast, pressure and Darcy flow velocities are solved as a coupled system. The reactive transport itself is performed using the masses of chemical elements instead of chemical species. In such way it requires less computing memory and time than the majority of other packages. The code is based on ESCRIPT, a parallelised platform which supports efficient stepwise simulation of realistic geodynamic scenarios at multiple scales. It is particularly suitable to analyse hydrothermal systems involving geometrically complex geological structures with strong permeability contrasts and subject to complex fluid-rock chemical interactions. The modular architecture of the code and its high level Python interface also provide flexibility for modellers who can easily modify or add new feedbacks between the different physical processes. In addition, the implemented abstract user interface allows geologists to run the code without knowledge of the underlying numerical implementation. As an example we show the simulation of hydrothermal gold precipitation in a granite-greenstone geological sequence, which illustrates the important coupling between thermal response and mass transfer to the localisation of gold.

- by Lutz Gross
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- Engineering, Earth Sciences, Geochemistry, Thermodynamics

- by Denis Testemale
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- Geology, Geochemistry, Thermodynamics, X ray absorption spectroscopy
- by Mercè Corbella
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- Thermodynamics, Kinetics, Numerical Method, Reactive transport modeling

The transport of reactive contaminants in the subsurface is generally affected by a large number of nonlinear and often interactive physical, chemical, and biological processes. Simulating these processes requires a comprehensive reactive transport code that couples the physical processes of water flow and advective-dispersive transport with a range of biogeochemical processes. Two recently developed coupled geochemical models that are both based on the HYDRUS-1D software package for variably saturated flow and transport are summarized in this paper. One model resulted from coupling HYDRUS-1D with the UNSATCHEM module. While restricted to major ion chemistry, this program enables quantitative predictions of such problems as analyzing the effects of salinity on plant growth and the amount of water and amendments required to reclaim salt-affected soil profiles. The second model, HP1, resulted from coupling HYDRUS-1D with the PHREEQC biogeochemical code. The latter program accounts for a wide range of instantaneous or kinetic chemical and biological reactions, including complexation, cation exchange, surface complexation, precipitation dissolution and/or redox reactions. The versatility of HP1 is illustrated in this paper by means of two examples: the leaching of toxic trace elements and the transport of the explosive TNT and its degradation products. (KEY TERMS: vadose zone; transport and fate; transport models; heavy metals; multicomponent geochemical transport; reclamation models.) S imů nek, Jirka, Diederik Jacques, Martinus Th. van Genuchten, and Dirk Mallants, 2006. Multicomponent Geochemical Transport Modeling Using HYDRUS-1D and HP1.

The Zero Emissions Research and Technology (ZERT) collaborative was formed to address basic science and engineering knowledge gaps relevant to geologic carbon sequestration. Many of the research activities fall between areas normally funded by different directorates at DOE and might be considered too applied for the basic science directorate and too basic in nature for other directorates. An executive committee

- by Michael Gardner
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- Engineering, Carbon Sequestration, Regional development, Risk assessment
- by Mercè Corbella
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- Genetics, Geology, Geochemistry, Reactive transport modeling

Editorial handling by R. Fuge a b s t r a c t

- by Wilfried Pfingsten and +1
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- Geochemistry, Performance Assessment, Reactive transport modeling, Applied Geochemistry

A feed-forward Neural Network is an interconnection of perceptrons in which data and computations flow in a single direction from the input data to the outputs. We used a two layer feed-forward network using Levenberg -Marquardt Back propagation Neural Network (LMBNN) to forecast the Ghanaian Cedi -US Dollar rate with Treasury bill rates, money supply, consumer price index and inflation. The results were measured with the Mean Squared Error (MSE), Root Mean Squared Error (RMSE) and the Weighted Absolute Percentage Error (WAPE). After careful and extensive training, validation and testing, the Artificial Neural Network (ANN) produced MSE, RMSE, WAPE and an R-value of 0.0010, 0.0324, 2.30%, 0.99634 respectively with a prediction accuracy of 97.70%.

- by Adu Sakyi(PhD)
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- Reactive transport modeling

Constructed Wetland Model No. 1 (CWM1) processes were implemented within RetrasoCodeBright (RCB) to simulate hydraulics and reactive transport as well as the main biodegradation and transformation processes in horizontal subsurface flow constructed wetlands (SSF CWs). New values for some stoichiometric and kinetic coefficients were determined in the calibration step in order to obtain more realistic biochemical transformation and degradation processes. The model was checked and then tested for a horizontal SSF CW operating with different hydraulic loading rates [20, 36 and 45 mm/d]. Modifications to the CWM1 formulation had a negligible effect on the good fitting of measured and simulated data. However, changes in stoichiometric and kinetic parameters positively affected performance. Bacterial concentrations defined as initial conditions proved to be a variable requiring attention in the calibration. In terms of pollutant concentrations in effluent, simulated data corresponded well with data measured in most cases evaluated. The quality of the results obtained suggests that CWM1-RETRASO, the resulting model, is a potential tool for studying hydraulics, reactive transport and the main biochemical transformation and degradation processes for organic matter, nitrogen and sulphur in horizontal SSF CWs.

- by Maarten W. Saaltink and +1
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- Chemical Engineering, Kinetics, Modeling, Wastewater Treatment

The article gives an introduction to numerical modeling of flow and transport problems and to software tools that are currently in use for modeling such phenomena. Details are explained on numerical approximations leading to different numerical models. Extensions for reactive transport are mentioned. Basic guidelines and criteria are given that should be taken into account by the modeler in order

A method to estimate reactive transport parameters as well as geometric conduit parameters from a multitracer test in a karst aquifer is provided. For this purpose, a calibration strategy was developed applying the two-region nonequilibrium model CXTFIT. The ambiguity of the model calibration was reduced by first calibrating the model with respect to conservative tracer breakthrough and later transferring conservative transport parameters to the reactive model calibration. The reactive transport parameters were only allowed to be within a defined sensible range to get reasonable calibration values. This calibration strategy was applied to breakthrough curves obtained from a large-scale multitracer test, which was performed in a karst aquifer of the Swabian Alb, Germany. The multitracer test was conducted by the simultaneous injection of uranine, sulforhodamine G, and tinopal CBS-X. The model succeeds to represent the tracer breakthrough curves (TBCs) of uranine and sulforhodamine G and verifies that tracer-rock interactions preferably occur in the immobile fluid region, although the fraction of this region amounts to only 3.5% of the total water. However, the model failed to account for the long tailing observed in the TBC of tinopal CBS-X. Sensitivity analyses reveal that model results for the conservative tracer transport are most sensitive to average velocity and volume fraction of the mobile fluid region, while dispersion and mass transfer coefficients are least influential. Consequently, reactive tracer calibration allows the determination of sorption sites in the mobile and immobile fluid region at small retardation coefficients.

- by Steffen Birk
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- Fluorescent Dyes and Reagents, Reactive transport modeling, Germany, Water Supply

severe groundwater contamination with extensive plumes of arsenic, phosphate and ammonium was found in a coastal aquifer beneath a former fertilizer production plant. The implementation of an active groundwater remediation strategy, based on a comprehensive pump and treat scheme, now prevents the migration of the dissolved contaminants into the marine environment. However, due to the site’s proximity to the coastline, a seawater wedge was induced by the pumping scheme. Additionally the groundwater flow and salinity patterns were also strongly affected by leakage from the site’s sewer system and from a seawater-fed cooling canal. The objective of this study was to elucidate the fate of arsenic and its co-contaminants over the site’s history under the complex, coupled hydrodynamic and geochemical conditions that prevail at the site. A detailed geochemical characterisation of samples from sediment cores and hydrochemical data provided valuable high-resolution information. The obtained data were used to develop various conceptual models and to constrain the development and calibration of a reactive transport model. The reactive transport simulations were performed for a sub-domain (two-dimensional transect) of an earlier developed
three-dimensional flow and variable density solute transport model. The results suggest that in the upper sub-oxic zone the influx of oxygenated water promoted As attenuation via co-precipitation with Al and Fe oxides and copper hydroxides. In contrast, in the deeper aquifer zone, iron reduction, associated with the release of adsorbed As and the dissolution of As bearing phases, provided and still provides to date a persistent source for groundwater pollution. . The presented monitoring and modelling approach could be broadly applied to coastal polluted sites by complex contaminant mixture containing As.

- by Mastrocicco M. and +2
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- Reactive transport modeling

Injecting anthropogenic CO2 into the subsurface is suggested for climate change mitigation. However, leakage of CO2 from its target storage formation is a concern. In the event of leakage, permeability in leakage pathways such as faults may get altered due to mineral reactions induced by CO2-enriched water, thus influencing the migration and fate of the CO2. An example of such fault permeability alteration is found in the Little Grand Wash Fault zone (LGWF), where the fault outcrops show fractures filled with calcium carbonate. To test the nature, extent, and time-frame of such fault ‘self-sealing’, we developed reactive flow simulations based on hydrogeological conditions of the LGWF. We measured LGWF water chemistry and conducted an x-ray powder diffraction (XRD) analysis of the fault-rock to constrain the model geochemistry. We hypothesized that the choice of parameters for relative permeability, capillary pressure, and reaction kinetics will have a huge impact on the fault sealing predictions. Simulation results showed that precipitation of calcite in the top portion of the fault led to a decrease in porosity of the damage zone from a value of 40% to ∼2%. Over a simulation time of 1000 years, porosity in the damage zone showed self-enhancing behavior in the bottom portion and self-sealing behavior in the top portion of the fault. We found that the results were most sensitive to the relative permeability parameters and the fault architecture. A major conclusion from this analysis is that, under similar conditions, some faults are likely to seal over time. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd.

- by Vivek V Patil
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- Geochemistry, Hydrogeology, Carbon Sequestration, Hydrogeochemistry

Microbially induced calcite precipitation (MICP) offers an alternative solution to a wide range of civil engineering problems. Laboratory tests have shown that MICP can immobilize trace metals and radionuclides through co-precipitation with calcium carbonate. MICP has also been shown to improve the undrained shear response of soils and offers potential benefits over current ground improvement techniques that may pose environmental risks and suffer from low "certainty of execution." Our objective is to identify an effective means of achieving uniform distribution of precipitate in a one-dimensional porous medium. Our approach involves column experiments and numerical modeling of MICP in both forward and inverse senses, using a simplified reaction network, with the bacterial strain Sporoscarcina pasteurii. It was found that the stop-flow injection of a urea-and calcium-rich solution produces a more uniform calcite distribution as compared to a continuous injection method, even when both methods involve flow in opposite direction to that used for bacterial cell emplacement. Inverse modeling was conducted by coupling the reactive transport code TOUGHREACT to UCODE for estimating chemical reaction rate parameters with a good match to the experimental data. It was found, however, that the choice of parameters and data was not sufficient to determine a unique solution, and our findings suggest that additional time and space-varying analytical data of aqueous species would improve the accuracy of numerical modeling of MICP.

- by Belén Martinez Vives
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- Chemical Engineering, Civil Engineering, Applied Mathematics, Trace Metals

- by Tess Weathers
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- Chemical Engineering, Civil Engineering, Applied Mathematics, Trace Metals

The present paper aims at modelling the decalcification process in cement-based materials and its impact on the material stiffness, which represents a serious matter in terms of long-term durability. The resistance of cementitious materials to this chemical alteration is strongly conditioned by their mineral composition and porosity. For this purpose, a multi-scale homogenization approach (Stora et al., Trans. Por. Med. 73, 3, 2008) is implemented in the numerical platform ALLIANCES (P. Montarnal, C. Mügler, J. Colin, M. Descotes, A. Dimier, E. Jacquot, Presentation and use of a reactive transport code in porous media, Phys. Chem. Earth 32, 2007) to estimate from these data the elastic and diffusive properties of cement-based materials. The association of this homogenization model and of the integration platform, which can couple different numerical codes, then allows for evaluating the evolution of the mineral composition and of the diffusive and mechanical properties of a concrete material during chemical deterioration processes. Simulations of pure water leaching of hydrated cement pastes are performed and the consequences of this decalcification on the material's residual elastic behaviour are estimated. The numerical results are confronted with available experimental data and analyzed. The simulations of the non-linear mechanical behaviour of leached cementitious materials taking into account interactions between damage and leaching is not reported here for conciseness but can be found in another document (Stora, Modelling and simulations of the chemo-mechanical behaviour of leached cement-based materials. PhD Dissertation, univ. of Paris-Est 2008).

- by Eric Stora
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- Civil Engineering, Reactive transport modeling, Building, Mineral Composition

A numerical model based on smoothed particle hydrodynamics (SPH) was used to simulate reactive transport and mineral precipitation in porous and fractured porous media. The stability and numerical accuracy of the SPH-based model was... more

- by George Redden
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- Environmental Engineering, Civil Engineering, Mass Transfer, Water resources

Both geothermal convection and brine reflux drive circulation of seawater derived fluids through carbonate platforms during early burial, but dynamic interactions between heat and solute transport and resulting diagenesis are at present poorly understood. This paper describes high-resolution reactive transport model (RTM) simulations that suggest that reflux of 85 ppt brines rapidly restricts geothermal convection to the platform margin, with flow focused in the more permeable shallow carbonates. In a baseline simulation, involving an elongate, 25-km-wide grain-dominated packstone platform, brine reflux resulted in complete dolomitization beneath the 5-km-wide brine pool in 335 ky. The dolomite body then extends downward at c. 22 m/100 ky into an underlying broad area of partial dolomitization. This process enhances porosity at shallow depth, but beneath the dolomite body precipitation of anhydrite occludes porosity and limits the depth of reflux. In contrast, geothermal convection at the platform margin forms a smaller partially dolomitized body over a longer time (, 60% dolomite after 1 My), with very minor associated anhydrite cementation. Reflux diagenesis is sensitive to platform geometry, with higher rates of fluid flow increasing the depth of alteration beneath the brine pool for a circular platform compared to the linear baseline. Fluid flow across thermal gradients enhances reaction rates, and ignoring heat transport by 85 ppt brine reflux underestimates the extent of reflux dolomite by 25% and associated anhydrite by 90%. The depth and rate of anhydritization is sensitive to the geothermal heat flux, whereas platform-top temperatures affect dolomitization rate. Reflux diagenesis is also sensitive to brine density, which affects both fluid flow and reaction rates. Sediment permeability and reactive surface area (RSA) are key intrinsic controls on diagenesis. Where the permeability structure permits sufficient fluid flow, diagenesis preferentially affects more reactive fine-grained sediments. However, as flow rates decline, reactions become focused in the more permeable but less reactive sediments. Simulations thus shed light on why in some settings reflux preferentially dolomitizes muddy sediments, but elsewhere favors grainstones. Once active reflux ceases, brines continue to flow in the subsurface, but this ''latent reflux'' causes only minor dolomitization due to prior Mg 2+ consumption at shallow depth.

- by Dr. Anwar B Al-Helal
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- Reactive transport modeling

In order to understand the interaction of a hyperalkaline solution with a fractured shear zone in granite and its influence on the migration of radionuclides, laboratory and underground field experiments at the Grimsel Test Site (Switzerland) were analysed by means of numerical modelling. Supporting data came from hydrogeological testing, structural and mineralogic characterisation of boreholes and cores and from dye

- by Wilfried Pfingsten
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- Geology, Geochemistry, Kinetics, Numerical Modelling

A model was developed simulating reactive transport in groundwater including bioclogging. Results from a bioclogging experiment in a flow cell with a two-dimensional flow field were used as a data base to verify the simulation results of the model. Simulations were performed using three different hydraulic conductivity vs. porosity relations published in literature; two relations derived from pore network simulations assuming the biomass to grow in discrete colonies and as a biofilm, respectively, and a third relation, which did not include pore connectivity in more than one dimension. Best agreement with the experimental data was achieved using a hydraulic conductivity vs. porosity relation derived from pore network simulation assuming the biomass to grow in colonies. The relation derived from pore network simulations assuming biomass to grow as a biofilm was unable to reproduce the experimental data when realistic parameter values were employed. With the third relation the clogging ability of the biomass was strongly underestimated. These findings indicate that the porous medium needs to be treated as a multi-dimensional medium already on the pore scale, and that biomass growth different than in a biofilm must be considered to get an appropriate description of bioclogging. D

- by Wolfgang Kinzelbach
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- Biofilms, Water, Carbon, Biomass

The main objec ve of this research was to enhance our understanding of and obtain quanta ve rela on between Darcy-scale adsorp on parameters and pore-scale fl ow and adsorp on parameters, using a three-dimensional mul direc onal pore-network model. This helps to scale up from a simplifi ed but reasonable representa on of microscopic physics to the scale of interest in prac cal applica ons. This upscaling is performed in two stages: (i) from local scale to the eff ec ve pore scale and (ii) from eff ec ve pore scale to the scale of a core. The fi rst stage of this upscaling from local scale to eff ec ve pore scale has been reported in an earlier manuscript. There, we found rela onships between localscale parameters (such as equilibrium adsorp on coeffi cient, k d , and Peclet number, Pe) and eff ec ve parameters (such as a achment coeffi cient, k a , and detachment coeffi cient, k det ). Here, we perform upscaling by means of a three-dimensional mul direc onal network model, which is composed of a large number of interconnected pore bodies (represented by spheres) and pore throats (represented by tubes). Upscaled transport parameters are obtained by fi ng the solu on of classical advec on -dispersion equa on with adsorp on to the average concentra on breakthrough curves at the outlet of the pore network. This procedure has resulted in rela onships for upscaled adsorp on parameters in terms of the microscale adsorp on coeffi cient and fl ow velocity.

The reactive mixing between seawater and terrestrial water in coastal aquifers influences the water quality of submarine groundwater discharge. While these waters come into contact at the seawater groundwater interface by density driven flow, their chemical components dilute and react through dispersion. A larger interface and wider mixing zone may provide favorable conditions for the natural attenuation of contaminant plumes. It has been claimed that the extent of this mixing is controlled by both, porous media properties and flow conditions. In this study, the interplay between dispersion and reactive processes in coastal aquifers is investigated by means of numerical experiments. Particularly, the impact of dispersion coefficients, the velocity field induced by density driven flow and chemical component reactivities on reactive transport in such aquifers is studied. To do this, a hybrid finite-element finite-volume method and a reactive simulator are coupled, and model accuracy and applicability are assessed. A simple redox reaction is considered to describe the degradation of a contaminant which requires mixing of the contaminated groundwater and the seawater containing the terminal electron acceptor. The resulting degradation is observed for different scenarios considering different magnitudes of dispersion and chemical reactivity. Three reactive transport regimes are found: reaction controlled, reaction–dispersion controlled and dispersion controlled. Computational results suggest that the chemical components' reactivity as well as dispersion coefficients play a significant role on controlling reactive mixing zones and extent of contaminant removal in coastal aquifers. Further, our results confirm that the dilution index is a better alternative to the second central spatial moment of a plume to describe the mixing of reactive solutes in coastal aquifers.► Developing a multicomponent reactive transport model for density driven flow regimes. ► The kinetics of the degradation and dispersion determines the extent of mass removal. ► Three distinct dispersion- or/and reaction-controlled transport regimes are shown.

A generalized formulation for kinetically controlled reactions has been developed and incorporated into a multicomponent reactive transport model to facilitate the investigation of a large variety of problems involving inorganic and organic chemicals in variably saturated media. The general kinetic formulation includes intra-aqueous and dissolutionprecipitation reactions in addition to geochemical equilibrium expressions for hydrolysis, aqueous complexation, oxidation-reduction, ion exchange, surface complexation, and gas dissolution-exsolution reactions. The generalized approach allows consideration of fractional order terms with respect to any dissolved species in terms of species activities or in terms of total concentrations, which facilitates the incorporation of a variety of experimentally derived rate expressions. Monod and inhibition terms can be used to describe microbially mediated reactions or to limit the reaction progress of inorganic reactions. Dissolution-precipitation reactions can be described as surface-controlled or transport-controlled reactions. The formulation also facilitates the consideration of any number of parallel reaction pathways, and reactions can be treated as irreversible or reversible processes. Two groundwater contamination scenarios, both set in variably saturated media but with significantly different geochemical reaction networks, are investigated and demonstrate the advantage of the generalized approach. The first problem focuses on a hypothetical case study of the natural attenuation of organic contaminants undergoing dissolution, volatilization, and biodegradation in an unconfined aquifer overlaid by unsaturated sediments. The second problem addresses the generation of acid mine drainage in the unsaturated zone of a tailings impoundment at the Nickel Rim Mine Site near Sudbury, Ontario, and subsequent reactive transport in the saturated portion of the tailings.

- by David Blowes
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- Environmental Engineering, Civil Engineering, Geology, Chemistry

Accurate prediction of contaminant migration in surface and ground water bodies, including interaction with aquifer and hyporheic zone materials requires reactive transport modeling. The increasing complexity and the procedure-oriented type of programming often used in reactive transport hinder codes reuse and transportability. We present a Fortran 90 module using object-oriented concepts that simulates complex hydrobiogeochemical processes (CHEPROO, CHEmical PRocesses Object-Oriented). CHEPROO consists of a general structure with two classes. The Nodal Chemistry class accounts for the description of local chemistry and geochemical state variables. As such, it provides many functions related to basic operations (evaporation, mixing, etc.) and can easily grow on this direction (extreme dry conditions, biochemical state variables, etc.). The Chemical System class includes kinetic and thermodynamic models that describe reactions between and within phases. As such, it can grow in the di...

- by Sergio Andres Bea
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- Engineering, Earth Sciences, Computer Science, Object Oriented Programming

Current risk-based methods for assessing the effects of landfill leachate migration on groundwater resources are conservative and generalised. Cost-effective and practical strategies are required which can robustly determine the potential for contaminant attenuation on a site-specific basis. In this paper laboratory column experiments and reactive transport modelling are evaluated as a combined approach for assessing the chem'ical impact of leachate migration in the Triassic Sandstone aquifer. The results are compared with field data for a landfill in the East Midlands. Columns of aquifer sandstone were flushed sequentially with groundwater, followed by acetogenic or methanogenic leachate to simulate chemical interactions occurring during leachate loading episodes. The key contaminants in leachate (NH 4 , heavy metals, organic fractions) were attenuated by ion exchange, redox reactions, sorption and degradation. These processes produce a consistent hydrochemical signature which may help identify the extent of leachate migration in the aquifer. The laboratory results largely replicate those found in the field system, and the behaviour of inorganic contaminants during leachate flushing of the aquifer columns can be described by the reactive transport model. The experimental and modelling approach presented represents a powerful tool for risk assessment and prediction of leachate contaminant fate at unlined and lined landfills.

- by John Tellam
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- Civil Engineering, Reactive transport modeling, Case Study, Heavy Metal

Geochemical modeling is widely used for understanding the geo-chemical ramifications of injecting anthropogenic CO 2 into subsurface aquifers for sequestration purposes. We develop a kinetic batch reaction model of CO 2 injection into an arkosic sandstone. The model is simulated in two very different simulators, TOUGHREACT and The Geochemist's Workbench. The goal is to characterize the effect of their differences on the results. We find that in both models that the evolution of pH and porosity over a 1000 years follow a similar trend. However, the models differ in the formation of secondary minerals. We postulate that this is due to the different mechanisms used by the two models for mineral formation. Treatment of CO 2 in a multiphase code (TOUGHREACT) versus that in a single-phase (GWB) can be another controlling factor. This work is meant to give an insight to geochemical modelers into the effects of the nature of simulators on the results.

- by Vivek V Patil
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- Carbon Sequestration, Reactive transport modeling

Concentrated aqueous solutions (CAS) have unique thermodynamic and physical properties. Chemical components in CAS are incompletely dissociated, especially those containing divalent or polyvalent ions. The problem is further complicated by the interaction between CAS flow processes and the naturally heterogeneous sediments. As the CAS migrates through the porous media, the composition may be altered subject to fluid-rock interactions. To effectively

- by Guoxiang Zhang
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- Environmental Engineering, Civil Engineering, Thermodynamics, Water resources

A popular method for the treatment of aquifers contaminated with chlorinated solvents is chemical oxidation based on the injection of potassium permanganate (KMnO 4 ). Both the high density (1025 gL − 1 ) and reactivity of the treatment solution influence the fate of permanganate (MnO 4 ) in the subsurface and affect the degree of contaminant treatment. The MIN3P multicomponent reactive transport code was enhanced to simulate permanganate-based remediation, to evaluate the pathways of MnO 4 utilization, and to assess the role of density contrasts for the delivery of the treatment solution. The modified code (MIN3P-D) provides a direct coupling between density-dependent fluid flow, solute transport, contaminant treatment, and geochemical reactions. The model is used to simulate a field trial of TCE oxidation in a sandy aquifer that is underlain by an aquitard. Three-dimensional simulations are conducted for a coupled reactive system comprised of ten aqueous components, two mineral phases, TCE (dissolved, adsorbed, and NAPL), reactive organic matter, and including ion exchange reactions. Model parameters are constrained by literature data and a detailed data set from the field site under investigation. The general spatial and transient evolution in observed concentrations of the oxidant, dissolved TCE, and reaction products are adequately reproduced by the simulations. The model elucidates the important role of density-induced flow and transport on the distribution of the treatment solution into NAPL containing regions located at the aquiferaquitard interface. Model results further suggest that reactions that do not directly affect the stability of MnO 4 have a negligible effect on solution density and MnO 4 delivery.

- by T. Kvitek and +1
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- Water Purification, Density, Stability, Multidisciplinary

Saprolite formation rates influence many important geological and environmental issues ranging from agricultural productivity to landscape evolution. Here we investigate the chemical and physical transformations that occur during weathering by studying small-scale "saprolites" in the form of weathering rinds, which form on rock in soil or saprolite and grow in thickness without physical disturbance with time. We compare detailed observations of weathered basalt clasts from a chronosequence of alluvial terraces in Costa Rica to diffusion-reaction simulations of rind formation using the fully coupled reactive transport model CrunchFlow. The four characteristic features of the weathered basalts which were specifically used as criteria for model comparisons include (1) the mineralogy of weathering products, (2) weathering rind thickness, (3) the coincidence of plagioclase and augite reaction fronts, and (4) the thickness of the zones of mineral reaction, i.e. reaction fronts. Four model scenarios were completed with varying levels of complexity and degrees of success in matching the observations. To fit the model to all four criteria, however, it was necessary to (1) treat diffusivity using a threshold in which it increased once porosity exceeded a critical value of 9%, and (2) treat mineral surface area as a fitting factor. This latter approach was presumably necessary because the mineralwater surface area of the connected (accessible) porosity in the Costa Rica samples is much less than the total porosity . The model-fit surface area, here termed reacting surface area, was much smaller than the BET-measured surface area determined for powdered basaltic material. In the parent basalt, reacting surface area and diffusivity are low due to low pore connectivity, and early weathering is therefore transport controlled. However, as pore connectivity increases as a result of weathering, the reacting surface area and diffusivity also increase and weathering becomes controlled by mineral reaction kinetics. The transition point between transport and kinetic control appears to be related to a critical porosity (9%) at which pore connectivity is high enough to allow rapid transport. Based on these simulations, we argue that the rate of weathering front advance is controlled by the rate at which porosity is created in the weathering interface, and that this porosity increases because of mineral dissolution following a rate that is largely surface-reaction controlled.

- by Peter Sak
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- Geology, Geochemistry, Kinetics, Reactive transport modeling

We use Monte Carlo simulations of flow and transport in two-dimensional random conductivity, porosity, and geochemistry fields to explore the influence of their spatial variability on flow and transport processes for both conservative and reactive chemicals. For conservative transport, results show that when the porosity is correlated to the hydraulic conductivity (which may be expected in geologic formations); the dispersion process is significantly affected. Positive cross correlation between the porosity and the conductivity decreases dispersion, while a negative correlation tends to increase dispersion in the longitudinal direction. For reactive transport in physically and chemically heterogeneous media, the geochemical variability alone yields results that are significantly different than when both geochemistry and porosity are random space variables correlated to the conductivity field. These results suggest that it is necessary to examine the role porosity variability and its correlation to the conductivity play in transport theories. The stochastic perturbation transport theory, previously developed by our group for conservative chemicals, is modified to account for the porosity variability and its correlation with the hydraulic conductivity. The results of the modified theory support the Monte Carlo simulations and indicate that porosity variability significantly affects the second longitudinal moment. The implication of the study for field problems depends on the existence of cross correlation between porosity and conductivity. but the discrepancy between the two cases becomes very substantial when the porosity variability is strongly nonlinear. Although this disregards the conductivity variability, it does show the importance of porosity. Shvidler [1985, 1993] studied purely convective transport of nonreactive solutes in porous media with random porosity and conductivity. However, he did not report on the significance of assuming a random porosity rather than a deterministic porosity. Warren and Skiba [1964] and Naff [1978] considered the variability in the porosity field and found it secondary relative to the effect of the conductivity variability. However, these authors did not allow the porosity to be correlated to the conductivity field which is to be expected in natural porous media. They also did not study its effect when combined with a random reactivity field. It should be mentioned that these aspects, which we try to investigate here, were outside the scope of those studies. To the authors knowledge, no one has studied the effect of correlations between geochemistry, porosity, and conductivity.