scholarly journals Reactive Transport with Wellbore Storages in a Single-Well Push-Pull Test

2018 ◽  
Author(s):  
Quanrong Wang ◽  
Hongbin Zhan
Keyword(s):  
Solute Transport ◽  
Reactive Transport ◽  
Transport Processes ◽  
Linear Functions ◽  
Sorption Model ◽  
Hydraulic Diffusivity ◽  
Wellbore Storage ◽  
Non Linear ◽  
Single Well ◽  
Robin Condition

Abstract. Using the single-well push-pull (SWPP) test to determine the in situ biogeochemical reaction kinetics, a chase phase and a rest phase were recommended to increase the duration of reaction, besides the injection and extraction phases. In this study, we presented multi-species reactive models of the four-phase SWPP test considering the wellbore storages for both groundwater flow and solute transport and a finite aquifer hydraulic diffusivity, including three isotherm-based models (Freundlich, Langmuir and linear sorption models), one-site kinetic sorption model, two-site sorption model, which were also capable of describing the biogeochemical reactive transport processes, e.g. Monod or Michaelis-Menten kinetics. The models of the wellbore storage for solute transport were derived based on the mass balance, and the results showed that ignoring it could produce great errors in the SWPP test. In the injection and chase phases, the influence of the wellbore storage increased with the decreasing aquifer hydraulic diffusivity. The peak values of the breakthrough curves (BTCs) increased with the increasing aquifer hydraulic diffusivity in the extraction phase, and the arrival time of the peak value became shorter with a greater aquifer hydraulic diffusivity. Meanwhile, the Robin condition performed well at the rest phase only when the chase concentration was zero and the solute in the injection phase was completely flushed out of the borehole into the aquifer. The Danckwerts condition was better than the Robin condition even when the chase concentration was not zero. The reaction parameters could be determined by directly best fitting the observed data when the non-linear reactions were described by piece-wise linear functions, while such an approach might not work if one attempted to use non-linear functions to describe such non-linear reactions. The field application demonstrated that the new model of this study performed well in interpreting BTCs of a SWPP test.

scholarly journals Reactive transport with wellbore storages in a single-well push–pull test

2019 ◽  
Vol 23 (4) ◽  
pp. 2207-2223 ◽  
Author(s):  
Quanrong Wang ◽  
Hongbin Zhan
Keyword(s):  
Solute Transport ◽  
Reactive Transport ◽  
Breakthrough Curves ◽  
Field Application ◽  
Linear Functions ◽  
Hydraulic Diffusivity ◽  
Wellbore Storage ◽  
Nonlinear Reactions ◽  
Single Well ◽  
Robin Condition

Abstract. Using the single-well push–pull (SWPP) test to determine the in situ biogeochemical reaction kinetics, a chase phase and a rest phase were recommended to increase the duration of reaction, besides the injection and extraction phases. In this study, we presented multi-species reactive models of the four-phase SWPP test considering the wellbore storages for both groundwater flow and solute transport and a finite aquifer hydraulic diffusivity, which were ignored in previous studies. The models of the wellbore storage for solute transport were proposed based on the mass balance, and the sensitivity analysis and uniqueness analysis were employed to investigate the assumptions used in previous studies on the parameter estimation. The results showed that ignoring it might produce great errors in the SWPP test. In the injection and chase phases, the influence of the wellbore storage increased with the decreasing aquifer hydraulic diffusivity. The peak values of the breakthrough curves (BTCs) increased with the increasing aquifer hydraulic diffusivity in the extraction phase, and the arrival time of the peak value became shorter with a greater aquifer hydraulic diffusivity. Meanwhile, the Robin condition performed well at the rest phase only when the chase concentration was zero and the solute in the injection phase was completely flushed out of the borehole into the aquifer. The Danckwerts condition was better than the Robin condition even when the chase concentration was not zero. The reaction parameters could be determined by directly best fitting the observed data when the nonlinear reactions were described by piece-wise linear functions, while such an approach might not work if one attempted to use nonlinear functions to describe such nonlinear reactions. The field application demonstrated that the new model of this study performed well in interpreting BTCs of a SWPP test.

scholarly journals New model of reactive transport in a single-well push–pull test with aquitard effect and wellbore storage

2020 ◽  
Vol 24 (8) ◽  
pp. 3983-4000
Author(s):  
Quanrong Wang ◽  
Junxia Wang ◽  
Hongbin Zhan ◽  
Wenguang Shi
Keyword(s):  
Reactive Transport ◽  
Molecular Diffusion ◽  
Breakthrough Curves ◽  
Advective Transport ◽  
New Model ◽  
Wellbore Storage ◽  
Single Well ◽  
Radial Dispersion ◽  
Injection Phase ◽  
Extraction Phase

Abstract. The model of single-well push–pull (SWPP) test has been widely used to investigate reactive radial dispersion in remediation or parameter estimation of in situ aquifers. Previous analytical solutions only focused on a completely isolated aquifer for the SWPP test, excluding any influence of aquitards bounding the tested aquifer, and ignored the wellbore storage of the chaser and rest phases in the SWPP test. Such simplification might be questionable in field applications when test durations are relatively long because solute transport in or out of the bounding aquitards is inevitable due to molecular diffusion and cross-formational advective transport. Here, a new SWPP model is developed in an aquifer–aquitard system with wellbore storage, and the analytical solution in the Laplace domain is derived. Four phases of the test are included: the injection phase, the chaser phase, the rest phase and the extraction phase. As the permeability of the aquitard is much smaller than the permeability of the aquifer, the flow is assumed to be perpendicular to the aquitard; thus only vertical dispersive and advective transports are considered for the aquitard. The validity of this treatment is tested against results grounded in numerical simulations. The global sensitivity analysis indicates that the results of the SWPP test are largely sensitive (i.e., influenced by) to the parameters of porosity and radial dispersion of the aquifer, whereas the influence of the aquitard on results could not be ignored. In the injection phase, the larger radial dispersivity of the aquifer could result in the smaller values of breakthrough curves (BTCs), while there are greater BTC values in the chaser and rest phases. In the extraction phase, it could lead to the smaller peak values of BTCs. The new model of this study is a generalization of several previous studies, and it performs better than previous studies ignoring the aquitard effect and wellbore storage for interpreting data of the field SWPP test reported by Yang et al. (2014).

Recent developments in the HPx-codes for coupled reactive transport in porous media

2021 ◽  
Author(s):  
Diederik Jacques ◽  
Jirka Simunek ◽  
Bertrand Leterme ◽  
Hans Meeussen ◽  
Eric Laloy
Keyword(s):  
Porous Media ◽  
Solute Transport ◽  
Reactive Transport ◽  
Environmental Science ◽  
Transport Processes ◽  
Machine Learning Techniques ◽  
Coupled Processes ◽  
Large Set ◽  
Geochemical Model ◽  
Scripting Language

<p>Coupled reactive transport codes are indispensable tools for simulating the fate of solutes in porous media for both environmental and engineering applications. HP1 and HP2/3 are some of the most versatile tools for coupled processes of variably-saturated water flow, multicomponent solute transport, heat transfer, and equilibrium-kinetic chemical reaction networks (Jacques et al., 2018). To date, multiple extensions are included that significantly increase the flexibility of the HPx codes. In addition to the default PHREEQC geochemical solver, HPx provides alternatives for the geochemical step: the geochemical solver ORCHESTRA (Meeussen, 2003) or direct scripting. The ORCHESTRA solver is relatively small and efficient and comes with a large set of user definable adsorption models, including the NICA-Donnan model. The choice of the scripting language has been extended from the classical BASIC scripting language to the structured, prototype-based programming variant of BASIC and Python. The latter gives the possibility to include several libraries of Python immediately in the HPx based models. For example, machine learning techniques can replace computationally expensive geochemical calculations to speed up the calculations. The HPx code is also coupled to the MT3D-USGS code, the groundwater solute transport simulator for MODFLOW. Via the MODFLOW-HYDRUS1D integration, soil flow and transport processes can be integrated as an unsaturated zone component into MODFLOW and MT3D-USGS. The last change is the updated graphical user interface (GUI) for the geochemical model input and post-processing output, incorporated in the standard HYDRUS GUI. Besides, a stand-alone GUI version is available as an advanced interface for geochemical calculations with PHREEQC.</p> <p> </p> <p>Jacques, D., J. Simunek, D. Mallants and M. T. van Genuchten (2018).  JOURNAL OF HYDROLOGY AND HYDROMECHANICS <strong>66</strong>(2): 211-226.</p> <p>Meeussen, J. C. L. (2003). Environmental Science & Technology <strong>37</strong>(6): 1175-1182.</p>

scholarly journals Simulation of reactive solute transport in the critical zone: A Lagrangian model for transient flow and preferential transport

2020 ◽  
Author(s):  
Alexander Sternagel ◽  
Ralf Loritz ◽  
Julian Klaus ◽  
Brian Berkowitz ◽  
Erwin Zehe
Keyword(s):  
Solute Transport ◽  
Reactive Transport ◽  
Preferential Flow ◽  
Critical Zone ◽  
Transport Processes ◽  
Tracer Transport ◽  
Flow Conditions ◽  
Model Framework ◽  
Soil Matrix ◽  
Reactive Solute Transport

Abstract. We present an approach to simulate reactive solute transport within the Lagrangian Soil Water and Solute Transport Model framework (LAST). The LAST-Model is based on a Lagrangian perspective describing the (1-D) movement of discrete water particles, which travel at different velocities and carry solutes through a heterogeneous, partially saturated soil that is separated into a soil matrix and structural macropore domain. In this study, we implement an approach to represent non-linear sorption and first-order degradation processes of reactive solutes under well-mixed and preferential flow conditions in the critical zone. The intensity of the two reactive transport processes may vary with the soil depth, to account for topsoil that facilitates enhanced microbial activity (and hence sorption) as well as chemical turnover rates. This expanded LAST-Model is evaluated with simulations of conservative tracer transport and reactive transport of the herbicide Isoproturon, at different flow conditions, and compared to data from field experiments. Additionally, the model is compared to simulations from the commonly used HYDRUS 1-D model. Both models show equal performance at a matrix flow dominated site, but LAST better matches indicators of preferential flow at a macropore flow dominated site. These results demonstrate the feasibility of the approach to simulate reactive transport in the LAST-Model framework, and highlight the advantage of the structural macropore domain to cope with preferential bypassing of topsoil and subsequent re-infiltration into the subsoil matrix.

Claudin Tight Junction Proteins: Novel Aspects in Paracellular Transport

2008 ◽  
Vol 28 (6) ◽  
pp. 577-584 ◽  
Author(s):  
Constanze Will ◽  
Michael Fromm ◽  
Dominik Müller
Keyword(s):  
Tight Junction ◽  
Solute Transport ◽  
Molecular Mechanisms ◽  
Family Members ◽  
Transport Processes ◽  
Paracellular Transport ◽  
Solute Flux ◽  
Solute Fluxes ◽  
Essential Components ◽  
Renal Tubular

Claudins are essential components of the intercellular tight junction and major determinants of paracellular solute fluxes across epithelia and endothelia. Many members of this family display a distinct charge or size specificity, whereas others render the epithelium impermeable to transport. Due to intercellular localization, claudin-mediated transport processes are passive and driven by an electrochemical gradient. In epithelial tissues, claudins exhibit a temporal–spatial expression pattern corresponding with regional and local solute transport profiles. Whereas paracellular transport mechanisms in organs such as intestine and kidney have been extensively investigated, little is known about the molecular mechanisms determining solute transport in the peritoneum, and thus the determinants of peritoneal dialysis. Given the ubiquitous expression of claudins in endothelia and epithelia, it is predictable that claudins also contribute to pore formation and determination in the peritoneum, and that they are involved in solute flux. Therefore, we review the basic characteristics of claudin family members and their function as exemplified in renal tubular transport and give an outlook to what extent claudin family members might be of importance for solute reabsorption across the peritoneal membrane.

Solvent Polarity Studies of the Water+t-Butyl Alcohol and Water+t-Butylamine Binary Systems With the Solvatochromic Dyes Nile Red and Pyridinium-N-phenoxide Betaine, Refractometry and Permittivity Measurements

1994 ◽  
Vol 47 (9) ◽  
pp. 1771 ◽  
Author(s):  
PK Kipkemboi ◽  
AJ Easteal
Keyword(s):  
Binary Systems ◽  
Hydrophobic Interactions ◽  
Nile Red ◽  
Solvent Polarity ◽  
Butyl Alcohol ◽  
Linear Functions ◽  
Non Linear ◽  
Organic Cosolvent ◽  
Two Parameters ◽  
Polarity Parameters

The empirical solvent polarity parameters ENR and ET for the solvatochromic compounds Nile Red (1) and pyridinium-N-phenoxide betaine (2), respectively, have been determined as a function of composition for water+t -butyl alcohol and water+t-butylamine binary mixtures, over the whole composition range at 298 K. For both systems the two parameters vary with composition in a strongly non-linear fashion, and the polarity of the mixture decreases with increasing proportion of the organic cosolvent. The non-linear variation of the polarity parameters is attributed to water-cosolvent hydrophobic interactions at low cosolvent contents, and hydrogen-bonding interactions at higher cosolvent contents. Permittivity and refractive index have also been measured at 298 K for both systems, and both properties are strongly non-linear functions of composition.

Separate and/or simultaneous generations of non-linear functions inherent in non-ohmic resistivities

1976 ◽  
Vol 18 (1) ◽  
pp. 51-61
Author(s):  
Yasuhiro Kobayashi∗ ◽  
Masaaki Ohkita ◽  
Michio Inoue ◽  
Masao Nakamura
Keyword(s):  
Linear Functions ◽  
Non Linear

Porous media as a canvas for hydro-bio-geo-chemical processes: Facing the challenges

2021 ◽  
Author(s):  
Xavier Sanchez-Vila
Keyword(s):  
Porous Media ◽  
Reactive Transport ◽  
Field Work ◽  
Open Science ◽  
Transport Processes ◽  
Aquifer Recharge ◽  
Music Production ◽  
Emerging Compounds ◽  
Technological Developments ◽  
Large Research

<p>The more we study flow and transport processes in porous media, the larger the number of questions that arise. Heterogeneity, uncertainty, multidisciplinarity, and interdisciplinarity are key words that make our live as researchers miserable… and interesting. There are many ways of facing complexity; this is equivalent as deciding what colors and textures to consider when being placed in front of a fresh canvas, or what are the sounds to include and combine in a music production. You can try to get as much as you can from one discipline, using very sophisticated state-of-the-art models. On the other hand, you can choose to bring to any given problem a number of disciplines, maybe having to sacrifice deepness in exchange of the better good of yet still sophisticated multifaceted solutions. There are quite a number of examples of the latter approach. In this talk, I will present a few of those, eventually concentrating in managed aquifer recharge (MAR) practices. This technology involves water resources from a myriad of perspectives, covering from climate change to legislation, from social awareness to reactive transport, from toxicological issues to biofilm formation, from circular economy to emerging compounds, from research to pure technological developments, and more. All of these elements deserve our attention as researchers, and we cannot pretend to master all of them. Integration, development of large research groups, open science are words that will appear in this talk. So does mathematics, and physics, and geochemistry, and organic chemistry, and biology. In any given hydrogeological problem you might need to combine equations, statistics, experiments, field work, and modeling; expect all of them in this talk. As groundwater complexity keeps amazing and mesmerizing me, do not expect solutions being provided, just anticipate more and more challenging research questions being asked.</p>

Assessment of groundwater contamination by chlorpyrifos using the PWC model in Valencia Region (Spain)

2021 ◽  
Author(s):  
Ricardo Pérez Indoval ◽  
Javier Rodrigo-Ilarri ◽  
Eduardo Cassiraga
Keyword(s):  
Reactive Transport ◽  
Management Practices ◽  
Fate And Transport ◽  
Environmental Modeling ◽  
Transport Processes ◽  
Negative Effects ◽  
Advection Dispersion ◽  
Agricultural Applications ◽  
Transformation Processes ◽  
Mass Transport Equation

<p>Chlorpyrifos is commoly used as an pesticide to control weeds and prevent nondesirable grow of algae, fungi and bacteria in many agricultural applications. Despite its highly negative effects on human health, environmental modeling of this kind of pesticide in the groundwater is not commonly done in real situations. Predicting the fate of pesticides released into the natural environment is necessary to anticipate and minimize adverse effects both at close and long distances from the contamination source. A number of models have been developed to predict the behavior, mobility, and persistence of pesticides. These models should account for key hydrological and agricultural processes, such as crop growth, pesticide application patterns, transformation processes and field management practices.</p><p>This work shows results obtained by the Pesticide Water Calculator (PWC) model to simulate the behavior of chlorpyrifos. PWC model is used as a standard pesticide simulation model in USA and in this work it has been used to  simulate the fate and transport of chlorpyrifos in the unsaturated zone of the aquifer. The model uses a whole set of parameters to solve a modified version of the mass transport equation considering the combined effect of advection, dispersion and reactive transport processes. PWC is used to estimate the daily concentrations of chlorpyrifos in the Buñol-Cheste aquifer in Valencia Region(Spain).</p><p>A whole set of simulation scenarios have been designed to perform a parameter sensitivity analysis. Results of the PWC model obtained in this study represents a crucial first step towards the development of a pesticide risk assessment in Valencia Region. Results show that numerical simulation is a valid tool for the analysis and prediction of the fate  and transport of pesticides in the groundwater.</p>

Sign in / Sign up

Export Citation Format

Share Document