Articoli di riviste: "PHREEQC"

1

Toran, Laura, e David Grandstaff. "PHREEQC and PHREEQCI: Geochemical Modeling with an Interactive Interface". Ground Water 40, n. 5 (settembre 2002): 462–64. http://dx.doi.org/10.1111/j.1745-6584.2002.tb02528.x.

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2

Ji, Shu Hua, e Mei Ling Wu. "Study on Simulation of Heavy Metal Transport in Soil Using PHREEQC". Applied Mechanics and Materials 522-524 (febbraio 2014): 153–60. http://dx.doi.org/10.4028/www.scientific.net/amm.522-524.153.

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This paper looked back on the current situation about simulation using PHREEQC of heavy metal transport in soil and the current situation of coupling with other value simulation software. On such a base, the feasibility, advantages and problems of heavy metal reactive solute transport in soil using PHREEQC were discussed.

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Huber, Patrick, Christophe Neyret e Eric Fourest. "Implementation of the anaerobic digestion model (ADM1) in the PHREEQC chemistry engine". Water Science and Technology 76, n. 5 (26 maggio 2017): 1090–103. http://dx.doi.org/10.2166/wst.2017.282.

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Anaerobic digestion is state-of-the-art technology to treat sludge and effluents from various industries. Modelling and optimisation of digestion operations can be advantageously performed using the anaerobic digestion model (ADM1) from the International Water Association. The ADM1, however, lacks a proper physico-chemical framework, which makes it difficult to consider wastewater of complex ionic composition and supersaturation phenomena. In this work, we present a direct implementation of the ADM1 within the PHREEQC chemistry engine. This makes it possible to handle ionic strength effects and ion-pairing. Thus, multiple mineral precipitation phenomena can be handled while resolving the ADM1. All these features can be accessed with very little programming effort, while retaining the full power and flexibility of PHREEQC. The distributed PHREEQC code can be easily interfaced with process simulation software for future plant-wide simulation of both wastewater and sludge treatment.

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4

Parkhurst, David L., e Laurin Wissmeier. "PhreeqcRM: A reaction module for transport simulators based on the geochemical model PHREEQC". Advances in Water Resources 83 (settembre 2015): 176–89. http://dx.doi.org/10.1016/j.advwatres.2015.06.001.

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5

de Moel, P. J., A. W. C. van der Helm, M. van Rijn, J. C. van Dijk e W. G. J. van der Meer. "Assessment of calculation methods for calcium carbonate saturation in drinking water for DIN 38404-10 compliance". Drinking Water Engineering and Science 6, n. 2 (18 novembre 2013): 115–24. http://dx.doi.org/10.5194/dwes-6-115-2013.

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Abstract. The new German standard on the calculation of calcite saturation in drinking water, DIN 38404-10, 2012 (DIN), marks a change in drinking water standardization from using simplified equations applicable for nomographs and simple calculators to using extensive chemical modeling requiring computer programs. The standard outlines the chemical modeling and presents a dataset with 10 water samples for validating used computer programs. The DIN standard, as well as the Standard Methods 2330 (SM) and NEN 6533 (NEN) for calculation of calcium carbonate saturation in drinking water were translated into chemical databases for use in PHREEQC (USGS, 2013). This novel approach gave the possibility to compare the calculations as defined in the standards with calculations using widely used chemical databases provided with PHREEQC. From this research it is concluded that the computer program PHREEQC with the developed chemical database din38404-10_2012.dat complies with the DIN standard for calculating Saturation Index (SI) and Calcite Dissolution Capacity (Calcitlösekapazität) or Calcium Carbonate Precipitation Potential (CCPP). This compliance is achieved by assuming equal values for molarity as used in DIN (obsolete) and molality as used in PHREEQC. From comparison with widely used chemical databases it is concluded that the use of molarity limits the use of DIN to a maximum temperature of 45 °C. For current practical applications in water treatment and drinking water applications, the PHREEQC database stimela.dat was developed within the Stimela platform of Delft University of Technology. This database is an extension of the chemical database phreeqc.dat and thus in compliance with SM. The database stimela.dat is also applicable for hot and boiling water, which is important in drinking water supply with regard to scaling of calcium carbonate in in-house drinking water practices. SM and NEN proved to be not accurate enough to comply with DIN, because of their simplifications. The differences in calculation results for DIN, SM and NEN illustrate the need for international unification of the standard for calcium carbonate saturation in drinking water.

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6

de Moel, P. J., A. W. C. van der Helm, M. van Rijn, J. C. van Dijk e W. G. J. van der Meer. "Assessment of calculation methods for calcium carbonate saturation in drinking water for DIN 38404-10 compliance". Drinking Water Engineering and Science Discussions 6, n. 2 (1 agosto 2013): 167–98. http://dx.doi.org/10.5194/dwesd-6-167-2013.

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Abstract. The new German standard for calcium carbonate saturation in drinking water, DIN 38404-10, 2012 (DIN), marks a change in drinking water standardization from using simplified equations applicable for nomographs and simple calculators to using extensive chemical modeling requiring computer programs. The standard specifies the chemical outlines for the modeling and presents a dataset with 10 water samples for validating used computer programs. The DIN standard, as well as the Standard Methods 2330 (SM) and NEN 6533 (NEN) for calculation of calcium carbonate saturation in drinking water were translated into chemical databases for use in PHREEQC (USGS, 2013). This novel approach gave the possibility to compare the calculations as defined in the standards and internationally accepted chemical databases provided with PHREEQC. From the research it is concluded that the computer program PHREEQC with the developed chemical database din38404-10_2012.dat complies with the DIN standard for calculating Saturation Index (SI) and Calcite Dissolution Capacity (Calcitlösekapazität) or Calcium Carbonate Precipitation Potential (CCPP). This compliance is achieved by assuming equal values for molarity as used in DIN (obsolete) and molality as used in PHREEQC. From comparison with internationally accepted chemical databases it is concluded that the use of molarity limits the use of DIN to a maximum temperature of 45 °C. For current practical applications in water treatment and drinking water applications, the PHREEQC database stimela.dat was developed within the Stimela platform of Delft University of Technology. This database is an extension of the internationally accepted chemical database phreeqc.dat and thus in compliance with Standard Methods 2330. The database stimela.dat is also applicable for hot and boiling water, which is important in drinking water supply with regard to scaling of calcium carbonate in in-house drinking water practices. The SM and NEN proved to be not accurate enough to comply with DIN, because of their simplifications. The differences in calculation results for DIN, SM and NEN illustrate the need for international unification of the standard for calcium carbonate saturation in drinking water.

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7

Holmes, Niall, Mark Tyrer, Roger West, Aaron Lowe e Denis Kelliher. "Using PHREEQC to model cement hydration". Construction and Building Materials 319 (febbraio 2022): 126129. http://dx.doi.org/10.1016/j.conbuildmat.2021.126129.

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8

Aris, A. Z., S. M. Praveena, M. H. Abdullah e M. Radojevic. "Statistical approaches and hydrochemical modelling of groundwater system in a small tropical island". Journal of Hydroinformatics 14, n. 1 (12 aprile 2011): 206–20. http://dx.doi.org/10.2166/hydro.2011.072.

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The aquifer of Manukan Island of Borneo, Malaysia had been found to be affected by seawater intrusion associated with excessive groundwater exploitation. This research attempted to characterize the chemistry of an impacted zone in the island using factor analysis (FA), cluster analysis (CA) and a hydrochemical model package (PHREEQC). The factor scores were used to plot the spatial map and to group the relationships among the monitoring wells using CA. The results of FA analysis revealed that the three main processes associated with the seawater intrusion event are aquifer salinization, cation exchange process and redox sequences. Output from the PHREEQC simulation was used to support the findings from the multivariate analysis.

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Abdelaziz, Ramadan, Broder J. Merkel, Mauricio Zambrano-Bigiarini e Sreejesh Nair. "Particle swarm optimization for the estimation of surface complexation constants with the geochemical model PHREEQC-3.1.2". Geoscientific Model Development 12, n. 1 (8 gennaio 2019): 167–77. http://dx.doi.org/10.5194/gmd-12-167-2019.

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Abstract. Sorption of metals on minerals is a key process in treatment water, natural aquatic environments, and other water-related technologies. Sorption processes are usually simulated with surface complexation models; however, identifying numeric values for the thermodynamic constants from batch experiments requires a robust parameter estimation technique that does not get trapped in local minima. Recently, particle swarm optimization (PSO) techniques have attracted many researchers as an efficient and effective optimization technique to find (near-)optimum model parameters in several fields of research. In this work, uranium at low concentrations was sorbed on quartz at different pH, and the hydroPSO R optimization package was used – the first time – to calibrate the PHREEQC geochemical model, version 3.1.2. Results show that thermodynamic parameter values identified with hydroPSO are more reliable than those identified with the well-known parameter estimation (PEST) software, when both parameter estimation software are coupled to PHREEQC using the same thermodynamic input data. In addition, post-processing tools included in hydroPSO were helpful for the correct interpretation of uncertainty in the obtained model parameters and simulated values. Thus, hydroPSO proved to be an efficient and versatile optimization tool for identifying reliable thermodynamic parameter values of the PHREEQC geochemical model.

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10

Lu, Peng, Guanru Zhang, John Apps e Chen Zhu. "Comparison of thermodynamic data files for PHREEQC". Earth-Science Reviews 225 (febbraio 2022): 103888. http://dx.doi.org/10.1016/j.earscirev.2021.103888.

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11

Farajzadeh, R., T. Matsuura, D. van Batenburg e H. Dijk. "Detailed Modeling of the Alkali/Surfactant/Polymer (ASP) Process by Coupling a Multipurpose Reservoir Simulator to the Chemistry Package PHREEQC". SPE Reservoir Evaluation & Engineering 15, n. 04 (18 giugno 2012): 423–35. http://dx.doi.org/10.2118/143671-pa.

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Summary Accurate modeling of an ASP flood requires detailed representation of geochemistry and, if natural acids are present, the saponification process. Geochemistry and saponification affect the propagation of the injected chemicals and the amount of generated natural soaps. These in turn determine the chemical phase behavior and, hence, the effectiveness of the ASP process. In this paper, it is shown that by coupling a multipurpose reservoir simulator (MPRS) with PHREEQC (Parkhurst and Appelo 1999; Charlton and Parkhurst 2008), a robust and flexible tool is developed to model ASP floods. PHREEQC is used as the chemical-reaction engine, which determines the equilibrium state of the chemical processes modeled. The MPRS models the impact of the chemicals on the flow properties, solves the flow equations, and transports the chemicals. The validity of the approach is confirmed by benchmarking the results with the ASP module of the UTCHEM simulator (Delshad et al. 2000). Moreover, ASP corefloods have been matched with the new tool. The functionality of the model also has been tested on a 2D sector model. The advantages of using PHREEQC as the chemical engine include its rich database of chemical species and its flexibility in changing the chemical processes to be modeled. Therefore, the coupling procedure presented in this paper can also be extended to other chemical enhanced-oil-recovery (EOR) methods.

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12

Bozau, E. "Prozessmodellierung hochsalinarer Wässer mit einem erweiterten PHREEQC-Datensatz". Grundwasser 18, n. 2 (9 febbraio 2013): 93–98. http://dx.doi.org/10.1007/s00767-013-0222-8.

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13

Riba, O., E. Coene, O. Silva e L. Duro. "Spent fuel alteration model integrating processes of different time-scales". MRS Advances 5, n. 3-4 (2020): 159–66. http://dx.doi.org/10.1557/adv.2020.51.

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ABSTRACTA 1D reactive transport model has been implemented in iCP (interface COMSOL Multiphysics and PhreeqC) to assess the corrosion of Spent Fuel (SF), considered as homogeneous UO2(am,hyd) doped with Pd. The model couples: i) generation of water radiolysis species by alpha and beta radiation considering the complete water radiolysis system with the kinetic reactions involving: H+, OH-, O2, H2O2, H2, HO2-, HO2·, O·, O-, O2-, H·, ·OH and e- ii) processes occurring in the spent fuel surface: oxidative dissolution reactions of UO2(am,hyd) and subsequent reduction of oxidized fuel, considering H2 activation by Pd, and iii) corrosion of Fe(s) in oxic and anoxic conditions. Process i) has been implemented in COMSOL and processes ii) and iii) have been implemented in PHREEQC with their kinetic constants being calibrated with different sets of experimental data published in the open literature. The model yields a UO2(am,hyd) dissolution rates similar to the values selected in safety assessments.

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14

Lipson, David S., John E. McCray e Geoffrey D. Thyne. "Using PHREEQC to Simulate Solute Transport in Fractured Bedrock". Ground Water 45, n. 4 (luglio 2007): 468–72. http://dx.doi.org/10.1111/j.1745-6584.2007.00318.x.

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15

Huang, Yi, Sen Yang, Shipeng Zhang, Ningmei Wang, Shi-Jun Ni e Yongli Wang. "Detection of Strontium Present in Groundwater Using PHREEQC Simulation". Asian Journal of Chemistry 28, n. 5 (2016): 1059–63. http://dx.doi.org/10.14233/ajchem.2016.19585.

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16

De Lucia, Marco, e Michael Kühn. "Coupling R and PHREEQC: Efficient Programming of Geochemical Models". Energy Procedia 40 (2013): 464–71. http://dx.doi.org/10.1016/j.egypro.2013.08.053.

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17

Antelmi, Matteo, Pietro Mazzon, Patrick Höhener, Massimo Marchesi e Luca Alberti. "Evaluation of MNA in A Chlorinated Solvents-Contaminated Aquifer Using Reactive Transport Modeling Coupled with Isotopic Fractionation Analysis". Water 13, n. 21 (20 ottobre 2021): 2945. http://dx.doi.org/10.3390/w13212945.

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Groundwater contamination by chlorinated hydrocarbons is a worldwide problem that poses important challenges in remediation processes. In Italy, the Legislative Decree 152/06 defines the water quality limits to be obtained during the cleanup process. In situ bioremediation techniques are becoming increasingly important due to their affordability and, under the right conditions, because they can be more effective than conventional methodologies. In the initial feasibility study phase, the numerical modeling supports the reliability of each technique. Two different codes, BIOCHLOR and PHREEQC were discussed and compared assuming different field conditions. Isotopic Fractionation-Reactive Transport Models were then developed in one synthetic and one simple field case. From the results, the two codes were in agreement and also able to demonstrate the Monitored Natural Attenuation processes occurring at the dismissed site located in Italy. Finally, the PHREEQC model was used to forecast the remediation time frame by MNA, hypothesizing a complete source cleanup: a remediation time frame of about 10–11 years was achieved by means of natural attenuation processes.

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ZHANG, H., e S. LUO. "Modeling the leaching behavior of simulated HLW-glass using PHREEQC". Nuclear Science and Techniques 18, n. 3 (giugno 2007): 150–53. http://dx.doi.org/10.1016/s1001-8042(07)60037-2.

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19

Bothe, James V., e Paul W. Brown. "PhreeqC modeling of Friedel's salt equilibria at 23±1 °C". Cement and Concrete Research 34, n. 6 (giugno 2004): 1057–63. http://dx.doi.org/10.1016/j.cemconres.2003.11.016.

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20

Khaledialidusti, Rasoul, e Jon Kleppe. "Significance of Geochemistry in Single-Well Chemical-Tracer Tests by Coupling a Multiphase-Flow Simulator to the Geochemical Package". SPE Journal 23, n. 04 (7 febbraio 2018): 1126–44. http://dx.doi.org/10.2118/189971-pa.

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Summary Single-well chemical tracer (SWCT) is the most commonly used field method to determine oil or water saturation in one-well enhanced-oil-recovery (EOR) pilots. Because hydrolysis of an ester, which is the main part of the method, leads to forming acid as well as alcohol, the equilibrium state of the reservoir is disturbed, and thus the pH changes. It is generally accepted that the hydrolysis-reaction rate is mainly dependent on the pH and temperature. Therefore, it is required to know the extent to which this dependency might affect the shape of the product-tracer profiles and the numerical interpretation of the field-test data for computing residual oil saturation (Sor). In this study, this notion has been investigated by coupling a multiphase-flow simulator to the geochemistry package PHREEQC (Parkhust and Appelo 2013). In this study, the PHREEQC geochemical simulator has been used to illustrate the extent to which different parameters might affect the pH variation during the test. The PHREEQC database has been modified to take the ester-hydrolysis reaction into account by adding the ester, alcohol, and acid-product species. The hydrolysis-reaction mechanisms of ester have also been programmed to account for the dependency of the hydrolysis reaction on the pH. Also, because ester partitions into the oil phase and travels behind the water phase (i.e., Darcy velocity), performing two-phase flow would be necessary to highlight the significance of the pH dependency of the hydrolysis-reaction rate on the tracer profiles. For doing that, a multiphase Buckley-Leverett (BL) flow simulation is coupled with IPhreeqc, which is an open-source module of the PHREEQC geochemical package. Then, a California Turbidite SWCT test has been re-evaluated to verify the approach. At the end, the geochemistry of a reservoir with an almost weak resistance (high temperature and weak buffer capacity) against pH variation in the SWCT test has been studied using the geochemical-based approach. The results show that the variation of the hydrolysis rate with pH could affect mainly the tail edge of the predicted tracer profiles, and it could marginally affect the apex of the profiles; however, it might affect the interpreted value of the Sor measurement as the resistance against pH variation becomes weaker. In these conditions, adapting the SWCT-test designs (i.e., shut-in time and injecting lower concentration of ester) could diminish the pH variation. The pH dependency of the hydrolysis-reaction rate is recommended for the numerical interpretation of the field SWCT-test data. The results of this study can be used to minimize the uncertainties of the SWCT tests and to improve the reliability of the Sor measurements.

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Slimani, Rabia, Abdelhamid Guendouz, Fabienne Trolard, Adnane Souffi Moulla, Belhadj Hamdi-Aïssa e Guilhem Bourrié. "Identification of dominant hydrogeochemical processes for groundwaters in the Algerian Sahara supported by inverse modeling of chemical and isotopic data". Hydrology and Earth System Sciences 21, n. 3 (21 marzo 2017): 1669–91. http://dx.doi.org/10.5194/hess-21-1669-2017.

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Abstract. Unpublished chemical and isotopic data taken in November 1992 from the three major Saharan aquifers, namely the Continental Intercalaire (CI), the Complexe Terminal (CT) and the phreatic aquifer (Phr), were integrated with original samples in order to chemically and isotopically characterize the largest Saharan aquifer system and investigate the processes through which groundwaters acquire their mineralization. Instead of classical Debye–Hückel extended law, a specific interaction theory (SIT) model, recently incorporated in PHREEQC 3.0, was used. Inverse modeling of hydrochemical data constrained by isotopic data was used here to quantitatively assess the influence of geochemical processes: at depth, the dissolution of salts from the geological formations during upward leakage without evaporation explains the transitions from CI to CT and to a first end member, a cluster of Phr (cluster I); near the surface, the dissolution of salts from sabkhas by rainwater explains another cluster of Phr (cluster II). In every case, secondary precipitation of calcite occurs during dissolution. All Phr waters result from the mixing of these two clusters together with calcite precipitation and ion exchange processes. These processes are quantitatively assessed by the PHREEQC model. Globally, gypsum dissolution and calcite precipitation were found to act as a carbon sink.

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Güler, Cüneyt, Geoffrey D. Thyne, Hidayet Tağa e Ümit Yıldırım. "Processes Governing Alkaline Groundwater Chemistry within a Fractured Rock (Ophiolitic Mélange) Aquifer Underlying a Seasonally Inhabited Headwater Area in the Aladağlar Range (Adana, Turkey)". Geofluids 2017 (2017): 1–21. http://dx.doi.org/10.1155/2017/3153924.

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The aim of this study was to investigate natural and anthropogenic processes governing the chemical composition of alkaline groundwater within a fractured rock (ophiolitic mélange) aquifer underlying a seasonally inhabited headwater area in the Aladağlar Range (Adana, Turkey). In this aquifer, spatiotemporal patterns of groundwater flow and chemistry were investigated during dry (October 2011) and wet (May 2012) seasons utilizing 25 shallow hand-dug wells. In addition, representative samples of snow, rock, and soil were collected and analyzed to constrain the PHREEQC inverse geochemical models used for simulating water-rock interaction (WRI) processes. Hydrochemistry of the aquifer shows a strong interseasonal variability where Mg–HCO3 and Mg–Ca–HCO3 water types are prevalent, reflecting the influence of ophiolitic and carbonate rocks on local groundwater chemistry. R-mode factor analysis of hydrochemical data hints at geochemical processes taking place in the groundwater system, that is, WRI involving Ca- and Si-bearing phases; WRI involving amorphous oxyhydroxides and clay minerals; WRI involving Mg-bearing phases; and atmospheric/anthropogenic inputs. Results from the PHREEQC modeling suggested that hydrogeochemical evolution is governed by weathering of primary minerals (calcite, chrysotile, forsterite, and chromite), precipitation of secondary minerals (dolomite, quartz, clinochlore, and Fe/Cr oxides), atmospheric/anthropogenic inputs (halite), and seasonal dilution from recharge.

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KLUNK, Marcos Antônio, Andrey Alexandrovich PONOMAREV, Sudipta DASGUPTA e Mohuli DAS. "ARSENIC SPECIATION IN GROUNDWATER USING THE SOFTWARES PHREEQC, GWB AND GEODELING". SOUTHERN BRAZILIAN JOURNAL OF CHEMISTRY 26, n. 26 (20 dicembre 2017): 30–35. http://dx.doi.org/10.48141/sbjchem.v25.n25.2017.35_2017.pdf.

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Geochemical modelling speciation is used to understand the interactions that occur in the groundwater. Thermodynamic data, kinetic parameters, numerical methods are factors that affect any geochemical modelling system. The conceptual formulation of geochemical modeling calculates the distribution of chemically reactive species for an aqueous solution. The mathematical formulation of the model results in a system of nonlinear algebraic equations that are solved using numerical methods. Most programs allow the user to estimate the speciation model. Activities of aqueous species are usually calculated using the Davies equation, Debye-Hückel equation, or the extended Debye-Hückel equation. We perform a comparative study of geochemical speciation using three different software: PHREEQCTM, Geochemist's WorkbenchTM (GWB) and GEODELING. Details of each software take into account the distribution, mobility, and availability of chemical species in groundwater. We can observe very similar results in speciation when working with low-temperature systems (20 to 80 °C). GWBTM, PHREEQCTM, and GEODELING employ an integrated system to define when to use Davies, Debye-Huckel or B-dot equation, according to the value of the solution ionic strength. The geochemical speciation aimed to compare the results of simulators able to predict the chemical species present in groundwater. The utilization of GEODELING allows comparing the results with software GWBTM and PHREEQCTM with a high degree of acceptance for low temperatures. The numerical methods used by GWBTM, PHREEQCTM, and GEODELING software are able to seek its own best set of numerical solutions to achieve the equilibrium. Users must be cautious when choosing geochemical modeling software, as an essential factor for choosing a simulator is to know the temperature range that will be used.

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Pötter, Leonie, Ralph Tollrian, Frank Wisotzky e Linda C. Weiss. "Determining freshwater pCO2 based on geochemical calculation and modelling using PHREEQC". MethodsX 8 (2021): 101430. http://dx.doi.org/10.1016/j.mex.2021.101430.

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Skold, Magnus E., Geoffrey D. Thyne e John E. McCray. "Using UCODE_2005 and PHREEQC To Determine Thermodynamic Constants from Experimental Data". Ground Water 45, n. 3 (maggio 2007): 368–73. http://dx.doi.org/10.1111/j.1745-6584.2007.00303.x.

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Song, Yonghui, Feng Qian, Ying Gao, Xiaohui Huang, Jieyun Wu e Huibin Yu. "PHREEQC program-based simulation of magnesium phosphates crystallization for phosphorus recovery". Environmental Earth Sciences 73, n. 9 (1 aprile 2015): 5075–84. http://dx.doi.org/10.1007/s12665-015-4340-8.

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Kersten, Michael. "Geothermometrische Modellierung der Lagerstättentemperatur balneologisch genutzter Thermalwässer mit Hilfe von PHREEQC". Grundwasser 24, n. 4 (31 agosto 2019): 269–75. http://dx.doi.org/10.1007/s00767-019-00429-8.

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De Lucia, Marco, e Michael Kühn. "Geochemical and reactive transport modelling in R with the RedModRphree package". Advances in Geosciences 56 (5 ottobre 2021): 33–43. http://dx.doi.org/10.5194/adgeo-56-33-2021.

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Abstract. Advances in computing and experimental capabilities in the research of water-rock-interactions require geoscientists to routinely combine laboratory data and models to produce new knowledge. Data science is hence a more and more pervasive instrument for geochemists, which in turn demands flexible and easy to learn software adaptable to their specific needs. The GNU R language and programming environment has established itself as de facto standard language for statistics and machine learning, enjoying increasing diffusion in many applied scientific fields such as bioinformatics, chemometrics and ecological modelling. The availability of excellent third party extensions as well as its advanced graphical and numerical capabilities make R an ideal platform for comprehensive geochemical data analysis, experiment evaluation and modelling. We introduce the open source RedModRphree extension package, which leverages the R interface to the established PHREEQC geochemical simulator. The aim of RedModRphree is to provide the user with an easy-to-use, high-level interface to program algorithms involving geochemical models: parameter calibration, error and sensitivity analysis, thermodynamical database manipulation, up to CPU-intensive parallel coupled reactive transport models. Among the out-of-the-box features included in RedModRphree, we highlight the computation and visualization of Pourbaix (Eh-pH) diagrams using full speciation as computed by PHREEQC and the implementation of 1D advective reactive transport supporting the use of surrogate models replacing expensive equation-based calculations.

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De Lucia, Marco, e Michael Kühn. "Geochemical and reactive transport modelling in R with the RedModRphree package". Advances in Geosciences 56 (5 ottobre 2021): 33–43. http://dx.doi.org/10.5194/adgeo-56-33-2021.

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Abstract (sommario):

Abstract. Advances in computing and experimental capabilities in the research of water-rock-interactions require geoscientists to routinely combine laboratory data and models to produce new knowledge. Data science is hence a more and more pervasive instrument for geochemists, which in turn demands flexible and easy to learn software adaptable to their specific needs. The GNU R language and programming environment has established itself as de facto standard language for statistics and machine learning, enjoying increasing diffusion in many applied scientific fields such as bioinformatics, chemometrics and ecological modelling. The availability of excellent third party extensions as well as its advanced graphical and numerical capabilities make R an ideal platform for comprehensive geochemical data analysis, experiment evaluation and modelling. We introduce the open source RedModRphree extension package, which leverages the R interface to the established PHREEQC geochemical simulator. The aim of RedModRphree is to provide the user with an easy-to-use, high-level interface to program algorithms involving geochemical models: parameter calibration, error and sensitivity analysis, thermodynamical database manipulation, up to CPU-intensive parallel coupled reactive transport models. Among the out-of-the-box features included in RedModRphree, we highlight the computation and visualization of Pourbaix (Eh-pH) diagrams using full speciation as computed by PHREEQC and the implementation of 1D advective reactive transport supporting the use of surrogate models replacing expensive equation-based calculations.

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Prihartini, R., R. Syaputra e G. J. Kusuma. "KARAKTERISTIK PEMBENTUKAN AIR ASAM TAMBANG PADA ENDAPAN HIGH SULPHIDATION EPITHERMAL". Jurnal Pertambangan 6, n. 3 (16 dicembre 2022): 107–14. http://dx.doi.org/10.36706/jp.v6i3.1306.

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Kegiatan penambangan meliputi aktivitas penggalian dan penimbunan batuan sisa pada tambang emas dengan tipe endapan high sulphidation epithermal (HSE), memungkinkan terdedahnya material sulfida kontak dengan udara dan air berpotensi untuk menimbulkan air asam tambang (AAT). Tujuan penelitian untuk mengetahui studi pembentukan AAT dengan meninjau karakteristik laju oksidasi mineral sulfida dengan pendekatan mol besi total, mol sulfat, dan mol pirit dari hasil pemodelan geokimia PHREEQC. Sebanyak empat sampel batuan yang digunakan dan dikelompokkan berdasarkan domain geologi tingkat oksidasi sempurna (COX) dan tidak teroksidasi (UOX). Metode penelitian menggunakan uji mineralogi dan unsur, serta uji geokimia (statik dan kinetik). Pemodelan geokimia menggunakan PHREEQC dilakukan untuk mensimulasikan perubahan pH dan konsentrasi zat terlarut yang dihasilkan selama uji kinetik. Hasil air lindian memiliki pH relatif rendah yang diiring oleh peningkatan konsentrasi sulfat, besi, aluminium, dan konstituen lainnya. Laju oksidasi pembentuk AAT berdasarkan mol sulfat (1,172 x 10-10 – 5,453 x 10-10 mol/m2s) lebih mendekati nilai transfer mol pyrite hasil pemodelan geokimia (4,260 x 10-11 – 5,561 x 10-10 mol/m2s), dibandingkan laju oksidasi mol besi total (3,102 x 10-18 – 9,090 x 10-09 mol/m2s). Kondisi ini disebabkan oleh kandungan besi dalam air lindian yang lebih banyak mengendap dibandingkan sulfat. Laju reaksi pyrite pada sampel COX jauh lebih rendah dari UOX, hal ini disebabkan oleh sampel COX yang lebih sedikit mengalami laju reaksi oksidasi dibandingkan UOX.

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31

Wang, Xiaocui, e Xun Zhou. "Geothermometry and Circulation Behavior of the Hot Springs in Yunlong County of Yunnan in Southwest China". Geofluids 2019 (11 marzo 2019): 1–16. http://dx.doi.org/10.1155/2019/8432496.

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Travertine and nontravertine thermal springs have been studied in Yunlong County in southwest China to determine the geothermal reservoir temperatures and to find the geochemical processes that affect the evolution of thermal groundwater constituents during subsurface circulation. Hydrochemical characteristics distinguish travertine from nontravertine types. Travertine springs show HCO3·Cl-Na and SO4·HCO3-Ca·Na type, and a nontravertine spring presents Cl·HCO3·SO4-Na type. Log(Q/K) versus T diagrams show that reservoir temperatures can be expressed as intervals based on the equilibrium mineral assemblages coexisting in equilibrium and multiminerals in equilibrium with the aid of the PHREEQC and WATCH programs. The spring water mixing ratio with shallow water is between 59% and 82% with steam loss ranging from 12.1% to 27.8%. The Dalang Spring mixes with the highest proportion of cold water (76% to 82%) among the four hot springs and has the highest geothermal reservoir temperature (132°C to 176.9°C). The water-rock interaction during recharge from precipitation demonstrates that the minerals halite, kaolinite, chalcedony, plagioclase, and CO2(g) play an important part in the evolution of the thermal groundwater. Four inverse modeling simulation paths between precipitation and spring discharge were established to calculate the mass flux of minerals by the PHREEQC program. Halite, kaolinite, chalcedony, plagioclase, and CO2(g) participate in dissolution reactions in the thermal groundwater circulation, while gypsum, calcite, dolomite, biotite, and fluorite keep the geochemical processes in equilibrium.

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Tiruta-Barna, L. "Using PHREEQC for modelling and simulation of dynamic leaching tests and scenarios". Journal of Hazardous Materials 157, n. 2-3 (settembre 2008): 525–33. http://dx.doi.org/10.1016/j.jhazmat.2008.01.028.

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33

Alimuddin, H., P. Andarani, K. Yokota, T. Inoue e M. N. Nguyen. "Analysis of hydrochemical parameters and dissolved zinc interaction by using PHREEQC simulation". IOP Conference Series: Earth and Environmental Science 1117, n. 1 (1 dicembre 2022): 012044. http://dx.doi.org/10.1088/1755-1315/1117/1/012044.

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Abstract Zinc is frequently reacting with inorganic species in water to form zinc species. Thus, the chemical speciation of Zinc in the aquatic environment has become a significant concern nowadays due to its adverse effect on humans and its potential toxicity in the water system. In this study, to investigate the interaction between dissolved zinc and hydro-chemical factors and to estimate the Zn speciation form, samples of river water were collected spatially from the Umeda River mainstream and tributaries in different seasons for one year. The hydrochemistry and dissolved zinc pollution characteristics of the samples were analyzed. Zn speciation was assessed by PHREEQC simulation. The result show that the main form of Zn speciation was Zinc free ion (Zn2+) in all seasons. However, in summer and spring season, the ZnCO3 and ZnOH+ concentration was higher than the other season. These speciation form may be attributed to the activities around the river in different season according to the similarities in downstream and upstream areas by the hierarchical cluster analysis result.

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Kempka, Thomas, Svenja Steding e Michael Kühn. "Verification of TRANSPORT Simulation Environment coupling with PHREEQC for reactive transport modelling". Advances in Geosciences 58 (3 novembre 2022): 19–29. http://dx.doi.org/10.5194/adgeo-58-19-2022.

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Abstract. Many types of geologic subsurface utilisation are associated with fluid and heat flow as well as simultaneously occurring chemical reactions. For that reason, reactive transport models are required to understand and reproduce the governing processes. In this regard, reactive transport codes must be highly flexible to cover a wide range of applications, while being applicable by users without extensive programming skills at the same time. In this context, we present an extension of the Open Source and Open Access TRANSPORT Simulation Environment, which has been coupled with the geochemical reaction module PHREEQC, and thus provides multiple new features that make it applicable to complex reactive transport problems in various geoscientific fields. Code readability is ensured by the applied high-level programming language Python which is relatively easy to learn compared to low-level programming languages such as C, C++ and FORTRAN. Thus, also users with limited software development knowledge can benefit from the presented simulation environment due to the low entry-level programming skill requirements. In the present study, common geochemical benchmarks are used to verify the numerical code implementation. Currently, the coupled simulator can be used to investigate 3D single-phase fluid and heat flow as well as multicomponent solute transport in porous media. In addition to that, a wide range of equilibrium and nonequilibrium reactions can be considered. Chemical feedback on fluid flow is provided by adapting porosity and permeability of the porous media as well as fluid properties. Thereby, users are in full control of the underlying functions in terms of fluid and rock equations of state, coupled geochemical modules used for reactive transport, dynamic boundary conditions and mass balance calculations. Both, the solution of the system of partial differential equations and the PHREEQC module, can be easily parallelised to increase computational efficiency. The benchmarks used in the present study include density-driven flow as well as advective, diffusive and dispersive reactive transport of solutes. Furthermore, porosity and permeability changes caused by kinetically controlled dissolution-precipitation reactions are considered to verify the main features of our reactive transport code. In future, the code implementation can be used to quantify processes encountered in different types of subsurface utilisation, such as water resource management as well as geothermal energy production, as well as geological energy, CO2 and nuclear waste storage.

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Gerla, P. J. "Can pH and electrical conductivity monitoring reveal spatial and temporal patterns in wetland geochemical processes?" Hydrology and Earth System Sciences Discussions 10, n. 1 (16 gennaio 2013): 699–728. http://dx.doi.org/10.5194/hessd-10-699-2013.

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Abstract. Carbonate reactions and equilibria play a dominant role in the biogeochemical function of many wetlands. The US Geological Survey PHREEQC computer code was used to model geochemical reactions that may be typical for wetlands with water budgets characterized by: (a) input dominated by direct precipitation, (b) interaction with groundwater, (c) variable degrees of reaction with organic carbon, and (d) different rates of evapotranspiration. Rainfall with a typical composition was progressively reacted with calcite and organic carbon at various rates and proportions using PHREEQC. Contrasting patterns of the results suggest that basic water quality data collected in the field can reveal differences in the geochemical processes in wetlands. Given a temporal record, these can signal subtle changes in surrounding land cover and use. To demonstrate this, temperature, pH, and electrical conductivity (EC) were monitored for three years in five large wetlands comprising 48 sample sites in northwest Minnesota. EC and pH of samples ranged greatly – from 23 to 1300 μS cm−1 and 5.5 to 9. The largest range in pH was observed in small beach ridge wetlands, where two clusters are apparent: (1) low EC and a wide range of pH and (2) higher pH and EC. Large marshes within a glacial lake – till plain have a broad range of pH and EC, but depend on the specific wetland. Outlying data typically occurred in altered or disturbed areas. The inter-annual and intra-wetland consistency of the results suggests that each wetland system hosts characteristic geochemical conditions.

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Ferreira, Quênia C. G., e Luis A. P. Bacellar. "Analysis of Chemical Mobility of Leachate Contaminants in Gneiss Saprolite of Belo Horizonte Solid Waste Landfill (CTRS BR 040), South-Eastern Brazil". Soils and Rocks 37, n. 1 (1 gennaio 2014): 51–59. http://dx.doi.org/10.28927/sr.371051.

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Municipal solid waste landfill is a potential source of contamination due to the harmful elements of the leachate, such as trace elements. In the Belo Horizonte landfill, the waste is partially disposed of directly on gneiss saprolites, with lower capacity to mitigate contaminants than upper soil horizons. Column tests were made to analyse the attenuation capacity of this saprolite. The analysis of the chemical elements concentration in soil and leached effluent after the tests and the calculation of the saturation index with PHREEQC software showed the ability of saprolite to mitigate the contamination, mainly by chemical precipitation and immobilization in the colloidal fraction.

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Al-Shalabi, Emad W., Kamy Sepehrnoori e Gary Pope. "Geochemical Interpretation of Low-Salinity-Water Injection in Carbonate Oil Reservoirs". SPE Journal 20, n. 06 (18 dicembre 2015): 1212–26. http://dx.doi.org/10.2118/169101-pa.

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Summary The advantages of using the low-salinity-water-injection (LSWI) technique to improve oil recovery in carbonates are reported in the literature; however, the mechanism behind it is still uncertain. This paper represents a comparison between two geochemical simulators [UTCHEM (UTCHEM manual, 2000) and PHREEQC (Parkhurst and Appelo 2013)] through modeling fluid- and solid-species concentrations of a recently published LSWI coreflood. Moreover, an attempt to interpret the mechanism controlling the LSWI effect on oil recovery from carbonates is presented on the basis of the findings of this work. The LSWI technique is case-dependent, and hence, the findings cannot be generalized.

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Zhang, Yilun, Bin Hu, Yanguo Teng, Kevin Tu e Chen Zhu. "A library of BASIC scripts of reaction rates for geochemical modeling using phreeqc". Computers & Geosciences 133 (dicembre 2019): 104316. http://dx.doi.org/10.1016/j.cageo.2019.104316.

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Benavente, D., P. Brimblecombe e C. M. Grossi. "Thermodynamic calculations for the salt crystallisation damage in porous built heritage using PHREEQC". Environmental Earth Sciences 74, n. 3 (4 marzo 2015): 2297–313. http://dx.doi.org/10.1007/s12665-015-4221-1.

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Lecomte, Karina L., Andrea I. Pasquini e Pedro J. Depetris. "Mineral Weathering in a Semiarid Mountain River: Its assessment through PHREEQC inverse modeling". Aquatic Geochemistry 11, n. 2 (giugno 2005): 173–94. http://dx.doi.org/10.1007/s10498-004-3523-9.

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41

Fairgray, M. E., J. G. Webster-Brown e J. Pope. "Testing Geochemical Predictions of Trace Element Toxicity and Bioavailability at a Rehabilitated Mine Site". Mine Water and the Environment 39, n. 1 (12 novembre 2019): 75–92. http://dx.doi.org/10.1007/s10230-019-00644-y.

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Abstract The speciation, toxicity and bioavailability of trace elements in mine drainage environments can be readily predicted using geochemical modelling, and this is frequently the basis for assessing the likely impacts of mine effluents and efficacy of rehabilitation plans. However, such predictions are rarely validated against observed trace element characteristics after mine rehabilitation is complete. In this study of a former Pb–Zn mine in New Zealand, PHREEQC was used to predict dissolved trace element and sediment-bound speciation for the rehabilitated mine site, and the results were compared to the observed water and sediment quality. For Fe, Mn, Al, Cu, Pb, Zn, Cd, Ni, As, and Sb, it was predicted that only Zn2+ and Cd2+ concentrations would exceed recommended guideline values for ecosystem health. PHREEQC indicated that the pH would have to be raised to > 9.5 to reduce these toxicants to a level fit for ecosystem health. Modelling of potential mineral formation indicated that the waters were saturated with respect to a variety of Fe-, Mn- and Al (oxy)hydroxides at and immediately downstream of the mine site, but were not saturated with respect to any trace element-bearing minerals, or sulfide or carbonate phases. This was consistent with X-ray diffraction and scanning electron microscopy (SEM) observations of the sediment. Sequential extraction of the sediment showed strong associations of Zn, Cu, Pb, As and Sb with iron (oxy)hydroxides. Modelling trace element adsorption onto only hydrous ferric oxide surfaces accurately predicted the adsorption of Zn, Cd, Cu, and Ni, but predictions of Pb and As adsorption were less reliable. Additionally, a strong association between Zn and Mn oxyhydroxide was observed in SEM analysis.

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Zhang, Feng Juan, Li Ting Xing, Tong Qiang Peng, Juan Zhou e Yi Yang. "Time and Space Evolution of Shallow Saline Groudwater Dynamic in Inland Area of Jiyang County，Shandong Province, China". Advanced Materials Research 1092-1093 (marzo 2015): 1197–201. http://dx.doi.org/10.4028/www.scientific.net/amr.1092-1093.1197.

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Inland plain shallow saline water has great exploitation potentiality. Based on field water testing, water level monitoring, pumping test, as well as indoor leaching experiment, applying mathematical statistics, Pipers trilinear nomograph and PHREEQC chemistry simulation methods, saline water area of the town of Sungeng Jiyang was studied. The results showed as follows: (1) Inland shallow groundwater presents “weather-evaporative” dynamic type; (2)The shallow saline water and middle-deep groundwater belonging to different flow system; (3) Because of the creeping flow and aqueous medium riched in clay, inland shallow groundwater mineralized significantly. In saline water area inland plain, the unique features of groundwater circulation result in brackish water dynamic relative stability.

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Nurmi, Pauliina, Lasse Ahonen e Olli H. Tuovinen. "Thermodynamic Modelling of Iron Solubility in Sulphide Mineral Leaching". Advanced Materials Research 71-73 (maggio 2009): 441–44. http://dx.doi.org/10.4028/www.scientific.net/amr.71-73.441.

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In this study the effects of pH and temperature on iron solubility were predicted using the geochemical modelling code PHREEQC and the thermodynamic database WATEQ4F. The modelling results demonstrated that the solubility of secondary solid phases formed under acid bioleaching conditions decreases with increasing temperature and also with increasing pH. Modelling calculations showed that bioleaching solutions are typically supersaturated with respect to K-, Na-, NH4-, and H3O-jarosites and the precipitates are typically solid solutions containing their mixtures. Jarosite solubility modelling results were also compared with a data set from jarosite synthesis experiments. Model-derived temperature dependence of hydronium-jarosite correlated very well with the actual experimental data.

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Wei, W., A. Varavei, A. Sanaei e K. Sepehrnoori. "Geochemical Modeling of Wormhole Propagation in Carbonate Acidizing Considering Mineralogy Heterogeneity". SPE Journal 24, n. 05 (6 maggio 2019): 2163–81. http://dx.doi.org/10.2118/195593-pa.

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Summary Matrix acidizing is a widely used stimulation process during which acid is injected into the formation at pressures that are less than the fracturing pressure. The purpose of matrix acidizing is to improve formation permeability or to bypass damaged zones through rock dissolution. Because of precipitation and diagenesis, carbonate rocks might contain different compositions, including calcite (CaCO3), dolomite [CaMg(CO3)2], and other minerals. When acid is injected into the formation, reactions between acid and multiple minerals of carbonate rocks occur simultaneously. In this paper, a two–scale continuum model is implemented in UTCOMP, a 3D compositional reservoir simulator, coupled with IPhreeqc, a generalized code of PHREEQC as a module. PHREEQC is an open–source program that performs a wide variety of geochemical calculations (Charlton and Parkhurst 2011). For the UTCOMP/IPhreeqc coupled model, the two–scale continuum model describes the mechanisms of convection and dispersion, whereas IPhreeqc is used for the calculation of reactions between aqueous phase and minerals. We have validated the simulation model through comparison with the analytical solution. We also compared the UTCOMP/IPhreeqc coupled model with a simple–reaction model, in which the reaction is assumed to be a first–order reaction between acid and calcite, by modifying the IPhreeqc database to obtain consistent results. On this basis, we have investigated the effects of mineral compositions on acidizing efficiency and the wormhole–propagation process. It is found that mineralogy heterogeneity is a key factor that affects acidizing efficiency and the dissolution structure. This work contributes to simulating the acidizing process with complex geochemical reactions considering the chemistry of the aqueous solution interacting with minerals. The presented model improves our understanding of carbonate–acidizing optimization.

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von Schenck, Henrik, Ulrik Kautsky, Björn Gylling, Elena Abarca e Jorge Molinero. "Advancing the Modelling Environment for the Safety Assessment of the Swedish LILW Repository at Forsmark". MRS Proceedings 1744 (2015): 223–28. http://dx.doi.org/10.1557/opl.2015.348.

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ABSTRACTAn extension of the Swedish final repository for short-lived radioactive waste (SFR) is planned and a safety assessment has been performed as part of the licensing process. Within this work, steps have been taken to advance the modelling environment to better integrate its individual parts. It is desirable that an integrating modelling environment provides the framework to set up and solve a consistent hierarchy of models on different scales. As a consequence, the consistent connection between software tools and models needs to be considered, related to the full assessment domain. It should also be possible to include the associated geometry and material descriptions, minimizing simplifications of conceptual understanding.The usefulness of the analysis software Comsol Multiphysics as component of an integrating modelling environment has been tested. Here, we present two examples of hierarchical models. Consistent properties and boundary conditions have been extracted form regional hydrogeology and surface hydrology models when setting up repository scale models. CAD models of the repository have been imported into the analysis software, representing tunnel systems and storage vaults with engineered structures and barriers. Data from geographic information systems such as digital elevation models and geological formations have been also directly implemented into model geometries.The repository scale hydrology models have provided a basis for further developments focussed on the modelling of coupled processes. An interface between Comsol Multiphysics and the geochemical simulator Phreeqc has been developed to support reactive solute transport studies. An important test case concerns radionuclide transport in a 3D, near-surface model of a catchment area. The dynamic surface hydrology has been simulated with MIKE SHE and connected to Comsol Multiphysics and Phreeqc for detailed hydro-geo-chemical modelling of radionuclide migration through soils and sediments.

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Hu, Hongyu, Guoping Lu, Qiuying Lu, Yan Li, Linjun Xie, Xuanhao Lin, Ming Wu, Cehui Mo e Bei Zhang. "Hydrogeochemical Characteristics and Geothermometry of Hot Springs in the Tensile Tectonic Region Leizhou Peninsula and Hainan Island in South China". Geofluids 2022 (17 marzo 2022): 1–21. http://dx.doi.org/10.1155/2022/1101015.

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Hydrochemistry and isotopes are studied for characterizations of geothermal waters, groundwaters, and surface waters in Leizhou Peninsula (LZ) and the northern part of Hainan Island (HN) across the tensile-tectonic Qiongzhou Strait, southern China. Water chemistry results showed that most geothermal waters are of alkaline and HCO3-Na types, while shallow groundwater samples were significantly different with HCO3-Ca, HCO3-Mg, and HNO3-Ca types. Stable isotope data indicated that the source of LZ geothermal waters is of atmospheric precipitation, while HN geothermal water has a slight “oxygen drift”. Cation geothermometers and silica geothermometers could appropriately predict reservoir temperatures. Based on multicomponent mineral equilibria and quart geothermometer without steam loss, reservoir temperatures were estimated to be in the range of 65.0°C to 165.0°C at an average circulation depth of 2023 m, substantiated with data from a thousand-meter-depth borehole. The saturation indexes (SI) simulated by PHREEQC and Na-K-Mg triangle diagram revealed that the chemical components in the geothermal waters are possibly derived from water-rock interactions at high temperatures. Four simulation paths were established to calculate the mass flux of minerals by PHREEQC program. The hydrothermal circulation process of the volcanic rocks on both sides of the Qiongzhou Strait was similar, but the water-mineral reactions of Leizhou Peninsula were more intense. During the high-temperature hydrothermal deep circulation in the central part of Hainan Island, the molar transfer was low and the degree of mineral reaction is weak. Finally, the geothermal genetic mechanism for the study area of the extensional geostructure was proposed. The findings mark the characteristics for the tensile-tectonic region in slight “oxygen shift”, low values of 87Sr/86Sr for possible deep source from the mantle, and higher reservoir temperatures at shallower circulation depths.

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Weyand, Torben, Holger Seher e Guido Bracke. "Geochemical benchmark tests to validate the conversion of thermodynamic data for TOUGHREACT". Safety of Nuclear Waste Disposal 1 (10 novembre 2021): 161–62. http://dx.doi.org/10.5194/sand-1-161-2021.

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Abstract. According to the ongoing site selection process for a repository for high-level radioactive waste in Germany, rock salt, clay and crystalline rock are possible host rocks. The pore water of these rocks contains saline solutions with high ionic strengths. To model the speciation and/or migration of radionuclides in long-term safety analyses for nuclear waste disposal, a geochemical code that includes thermodynamic data suitable for saline solutions is needed. Thermodynamic equilibrium in saline solutions with high ionic strengths is usually modelled using the Pitzer approach (Pitzer, 1991). Within the context of nuclear waste disposal, the THEREDA project (Moog et al., 2015) provides thermodynamic data for some widely used geochemical codes (PHREEQC, Geochemist's Workbench, ChemApp, and EQ 3/6) using the Pitzer approach; however, for modelling in long-term safety analyses for nuclear waste disposal, another geochemical code, TOUGHREACT, is used. Therefore, scripts were developed to convert thermodynamic data of the THEREDA project to be applicable in TOUGHREACT. The scripts were validated by benchmark tests and by comparing calculations using PHREEQC and TOUGHREACT (Weyand et al., 2021). In total, 50 different benchmark tests were performed considering 3 specific geochemical systems, which are relevant to long-term safety analyses: (1) oceanic salt system, polythermal: K, Mg, Ca, Cl, SO4, H2O(l), (2) actinide system, isothermal: Am(III), Cm(III), Nd(III), Na, Mg, Ca, Cl, OH, H2O(l) and (3) carbonate system, isothermal: Na, K, Mg, Ca, Cl, SO4, HCO3/CO2(g), H2O(l). Each benchmark test considered specific ion concentrations in solution and in gaseous phases in the presence of specific minerals. The benchmark tests derived the geochemical equilibria and the results of both codes were compared to each other and to experimental data. The results of the calculations using both codes showed a good correlation. Remaining deviations can be explained by technical differences of the codes.

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de Tello, Clédola C. O., Daisy M. M. dos Santos e Thais B. Teixeira. "Study of the sorption and modelling of cesium by a Brazilian bentonite using PHREEQC". MRS Advances 5, n. 5-6 (2020): 245–52. http://dx.doi.org/10.1557/adv.2020.57.

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ABSTRACTTo estimate the cesium sorption by the bentonite and to obtain the isotherms, some batch-adsorption experiments are being carried out, being the Kd (retardation coefficient) calculated from these isotherms. One-dimensional flow cell was constructed to measure the bentonite permeability regarding to a cesium solution, which results will be used to evaluate the diffusion coefficient – D. It will be used the PHREEQC software to model the transport of the cesium radionuclide through this bentonite with the Kd and D data. The modelling of radionuclide transport in the Brazilian materials will contribute to evaluate the efficiency of multi-barriers system of the national repository, because it is one of its safety criteria.

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Lei, Jie Hong. "Analog Computation of Forms of Americium Presence in Aqueous Solution". Advanced Materials Research 549 (luglio 2012): 500–503. http://dx.doi.org/10.4028/www.scientific.net/amr.549.500.

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In geological disposal of radioactive wastes, the study of Americium migration is very important for the safety evaluation of the repository. The forms of chemical components of Americium presence in aqueous solution that directly affect its migration behavior provide a basis for analog computation of the element. This paper uses PHREEQC, the geochemical model, for analog computation of forms of Americium presence in two types of groundwater, and analyzes the morphologies of the main elements and the influencing factors. The results show that the morphology of Americium is mainly controlled by the characteristics of the chemical composition of groundwater, while the PH value also has a great impact on the forms of Americium presence.

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Lei, Jie Hong. "Analog Computation of Forms of Uranium Presence in Aqueous Solution". Advanced Materials Research 463-464 (febbraio 2012): 12–15. http://dx.doi.org/10.4028/www.scientific.net/amr.463-464.12.

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In geological disposal of radioactive wastes, the study of uranium migration is very important for the safety evaluation of the repository. The forms of chemical components of uranium presence in aqueous solution that directly affect its migration behavior provide a basis for analog computation of the element. This paper uses PHREEQC, the geochemical model, for analog computation of forms of uranium presence in two types of groundwater, and analyzes the morphologies of the main elements and the influencing factors. The results show that the morphology of uranium is mainly controlled by the characteristics of the chemical composition of groundwater, while the PH value also has a great impact on the forms of uranium presence.

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