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What approach would one take to calculate the vertical transport of a water miscible salt in groundwater that is continually entering from the soil? I am searching for a global solution. Is using a global groundwater recharge rate useful? I am trying to understand the extent of migration of the salt in groundwater and the concentration gradient that will occur.
Thanks for taking time to consider this question.
David
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Thanks Neil Wang
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I need to use runkel's solute transport result as benchmark results. Can anyone provide me algorithm for runkel's solute transport model. Thanks in advance.
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Dear Mr. Modi!
I found the following article free to access:
Tinet, AJ, Collon, P, Philippe, C, Dewaide, L & Hallet, V 2019, 'OM-MADE: An open-source program to simulate one-dimensional solute transport in multiple exchanging conduits and storage zones', Computers and Geosciences, vol. 127, pp. 23-35. https://doi.org/10.1016/j.cageo.2019.03.001 Free access:
Yours sincerely, Bulcsu Szekely
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Hello everyone,
I am new to hydro-chemistry and planning to analyze freshwater (pristine environment) water samples for trace element analysis using ICP-MS. I have gone through literature for identification of suitable filter type for in-situ sample filtration and found that people have used a variety of filter types Cellulose Nitrate/PES Filter/Millipore filters/Polytetrafluoroethylene/Ester cellulose millipore/Polycarbonate, etc.
I was wondering which could be the most suitable filter choice for freshwater sample filtration?
I request you to give your valuable suggestions in this respect.
Thanking you all.
Regards
Rajat
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Make sure before you purchase too many sample containers etc, that the supplies are appropriately metal-free. This applies to filters as well, and the acids you will need to stabilize the trace elements in the sampled water. Check the lids too: liners may be treated with something that might look like field contamination, but was in the flexible disc inside the screw-on lid.
As you say you are new to hydrochemistry , I would recommend you speak to a local expert (university researchers or government environment office etc), see what equipment they use etc and get an idea of what you need for your purposes.
Also speak to the analytical laboratory that will be doing your analysis and find out what they need in a sample: they may have done this work before and will have some suggestions that could save you a lot of time, travel, and plastic containers if you haven't thought of some important details.
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Hello everyone,
I am working in solute transport modelling for which I have a 1d solute transport model. The problem is validation of the model. I need benchmark solutions for the validations for different channel reach. I was working with Runkel solute transport equations to find the benchmark solution but was unable to complete it.
I need to know what can I use a software or any other program code which will help me to validate my model.
In total I need benchmark results for solute transport modelling
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Use Groundwater Vistas with modflow also you can use aquatox models.
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I try to simulate solute transport using column experiments. Based on the literature and manual I come to know about setting initial/input conditions. I am not sure, where to enter the initial solute concentration to get BTC of concentration with time.
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Due to solute atoms diffusion, substitutional atoms diffuse by vacancies diffusion, so I am asking, if the concentration of solute atoms increases, so what will be the effect on vacancies mobility ?
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If you are referring to solid state diffusion, there are a number of standard monographs which give the underlying theoretical treatments, which are well developed, e.g.
Shewmon, P. (Ed) (2016) Diffusion in Solids Springer
J. S. Kirkaldy (John Samuel) ; David J Young (David John)
Diffusion in the condensed state
London ; Brookfield, VT, USA : Institute of Metals, 1987
For the liquid state:
H.J. V. Tyrrell and K R Harris, Diffusion Liquids, Butterworths 1984
E L Cussler, Diffusion, Cambridge UP
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I know one application is in modeling the blood flow and solute transport in a hollow fiber dialyzer. I want to know any other applications and if anyone can provide me suggested papers on such work.
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reverse osmosis, waste water, sulfide removal
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Hello everyone,
I am dealing with the residence time distributions (RTD) curve in solute transport in groundwater, which is usually plotted by dc/dt versus t. So, what is the meaning of this curve, and for a specific t, what is the physical meaning of its dc/dt value? Besides, for two RTD curves at a specific t, the larger value of dc/dt indicates what?
Does anyone know it, or is there any reference for explaining this RTD curve? Thanks in advance.
-Jiaqing
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Chapter 10 in Mark Clark’s text “Transport Modeling for Environmental Engineers and Scientists” has a good discussion of RTDs. The RTDF (residence time distribution function) is the same as a probability density function in statistics. If you think about groundwater moving along a flow line from Point A to Point B, and you inject a Dirac pulse of solute at Point A, the RTDF (which is conventionally designated f(t)) indicates the probability that a molecule of solute will reach Point B at time t. With this definition of f(t), you can see that the integral of f(t) between time=0 and time=infinity must be 1 (that is, there is 100% probability that all molecules of solute will reach Point B after infinite time). Also, the probability that a particular molecule of solute will reach Point B between times t1 and t2 is the integral of f(t) between times t1 and t2. In practice, an RTDF can be measured by injecting (at time = 0) a step of solute at Point A, with a concentration of C0, and measuring concentrations, c(t), at Point B over time, . The cumulative residence time distribution function (conventionally designated as F(t)) is the concentration at Point B divided by C0 (that is F(t)=c(t)/C0). The time derivative of F(t) is the RTDF (that is, f(t)=dF(t)/dt). I think this may be what you were referring to when you stated the RTD is dc/dt. Hope this is helpful. If you can get a copy of the Clark text, you’ll see a much better and more detailed explanation.
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As groundwater modeling, solute transport, surface water modeling or any other modeling used in water resource management
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Thank you for your concern. In fact, you will find enormous number of scientists who published their works over Africa. I kindly ask you to explain more on your request. It is better to highlight the purpose of your question. Thanks and Kind regards, Islam
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The reaction term in the advection-dispersion equation for solute transport in porous medium can be represented by isotherm models or kinetic models. My question: which models will be more representative for this situation and why?
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Dear Dr. Faisal,
I agree with @Jakab. I think there will be no significant difference between results of equilibrium isotherm model and kinetic model.
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Let the concentration of tracer in the sand column experiment be c´ and the velocity with which it is being injected is v. So the influx of tracer in the column would be -vc´ (negative sign to denote influx)
My question is which inlet boundary condition should be applied? 1st type or 3rd type?
With 1st type condition at the inlet C= c´,
the same concentration as the experiment can be ensured, but the influx will be higher than actual experiment as
Model influx: D∇c´−vc´
Experimental influx: -vc´
But if 3rd trype boundary condition is applied i.e
(D∇C−vC)⋅n= -vc´
The same flux condition as the experiment can be ensured, but the inlet concentration will be lower, untill diffusive flux becomes zero.
In that case, which boundary condition should be applied?
Thanks in anticipation
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If you're measuring flux averaged concentrations at the column outlet, as is typically assumed, you should use the first-type BC at the inlet. See van Genuchten and Parker, Soil Science Society of America Journal, 703-708, 1984 for a full discussion.
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In Groundwater flow problems, the flow equations are linearized using different linearization techniques. Is it possible to apply some kind of linearization technique to soute transport model?
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Kaveh Zamani, Thank you sir.I will go through it.
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As I am working on a project with Diode laser of 400mW and 635Nm, I want a solution to transport the laser beam to a remote place with optical fiber.
Can someone help to decide the required characteristics of optical fiber required - Type, Diameter and other properties?
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Thank you so much for the suggestions. I will look into them for sure.
@Vincent Lecoeuche I couldn't understand by what you mean as Wavefront conservation.
To be more clear about my application. I want to transport for a distance of just 2 meter.
I also think if some one could suggest me link of the sellers for the required optical fiber, its cladding and other required components, because, I am not very aware of all the required components
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I need to transport embryonic organs fixed in 4% PFA and previously stained in b-gal solution (LacZ) to another country. Our objective is to embeed the tissues in paraffin. Is 4% PFA the best solution for transport of these organs in leak/spill-proof containers? Any experience/insights would be very helpful.
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Once the tissue is thoroughly fixed, it should be fine for transport in PBS for example. This would save you from making and transporting copious amounts of toxic PFA! I would do a trial run with a small piece of tissue first to make sure before committing to large shipments.
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I am doing a soil column experiment, using quartz sand as a transport medium. We are using 0.001 M NaNO3 as a background solution. Before injection to soil column the pH was adjusted to 7.5 with NaOH and HCl, but after sometime the pH of influent changes and the pH tends to decrease, so does the effluent. After this we used 0.0001 M NaHCO3 to stabilize the pH. The concentration of the influent becomes 0.0009 M NaNO3 + 0.0001M NaHCO3. but still it doesn't work and the pH of influent still tends to decrease. Please help me to solve this issue. I want to keep the pH at 7.5.
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To maintain the pH at 7.5 you must use a buffer (a phosphate buffer can be used for this purpose). You have to check the buffer capacity to ensure that it can maintain the pH at the desired value.
I don't know the other details of your research, but I'm supposing the use of the buffer doesn't interfere with your experiments
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when applying to solute transport problems in agricultural field
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Thank you both of you for valuable input
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I need some literature about transport of Phosphorus in soil porous media.
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What are the differences between stokes radius, radius of gyration and hydrodynamic radius ?? and how can they be measured (size exclusion chromatography, DLS, SAXS) ??
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Strongly recommend that you look up each term on the web. That way you can learn about them and answer any questions that you may have. Learning how to research questions on your own is a critical skill that is best acquired as early as possible in your studies.
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Hello everyone, I'm doing work about solute transportation in soil. There are 40 sample points and in GS+ software, active lag distance is default as half of sample distance. After calculation, only four or five plotted points were showed, but R2 is more than 0.9. Is this analysis reliable? How many plotted points are needed at least?
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If you going to use the variogram for kriging or simulation remember that the purpose of the variogram is purely utilitarian; you are trying to develop a model that captures the spatial covariance of observed values.  The model you specify for kriging or simulation helps control the smoothness and roughness of the resulting surface.  Therefore you want enough variogram points to indicate a range of spatial dependence,  existence and  magnitude of any very small-scale variability ("nugget effect"), and a value for the sill.  Four points might be enough for some datasets, including yours.  For others, forty might not be enough.  You can play around with different lag sizes but remember that as the number of variogram values increases the number of pairs used to calculated each value decreases and the variogram can become more noisy.
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I have currently carried out solute rejection for four different molecular weight cut-off (MWCO) but don't understand how to translate their response in order to determine the pore size distribution. How can i go about it.
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There are several models to determine pore size from rejection experiment using neutral solutes like PEG. The easiest and popular one is probably the steric hindrance pore (SHP) model. There are quite many publications about it. Let me know if you couldn't find any.
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Thank you sir, for your reply.
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I am not sure how it is possible to see the interaction of two solutes on each other and soil particles! So I like to do batch experiments firstly but what I have seen so far isotherms are fitted to two components (one sorbate and another sorbent). If I want to to see adsorption of solute on soil one by one and on each other three different batch should be performed which equals missing a unit and real system.
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You want to see the interaction of two solutes on each other and soil particles.  You can adopt doping or impregnation technique .  They can be apply for the sorption process by batch  method.
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What are the initial and boundary condition to be applied in case of groundwater model in presence of tide?
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Interface boundary between groundwater and tidal water may be delineated by the parameter like Chloride and Bicarbonate, along with various other chemical parameters. Tidal water has very low HCO3  and very very high concentration of chloride. In case of groundwater, in general HCO3 is high, and Cluoride is comparatively very less. Good published work available online.
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As it is seen in literature, the ADE with a (dS/dt) is used to model a reactive transport. However, how it can be modeled if nitrate as one solute is stuck by another solute (e.g. nanoparticles)? in this case part of nitrate is adsorbed by soil particles and another part by nano.
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It goes even beyond: Nitrate adsorbed to nano may be adsorbed to soil because nano adsorbs to soil. I know just one code capable of modelling co-transport and co-sorption. (You may consult: Totsche K.U., Knabner P. & Kögel-Knabner I. 1996. The modelling of reactive solute transport with sorption to mobile and immobile sorbents - Part II: Model discussion and numerical simulation. Water Resour. Res. 32, 1623-1632.). Kai Totsche is a Professor at Jena University in Germany
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In describing the transport of solutes in a classical porous medium,
the concept of macro-dispersion or differential advection (resulting from conductivity variation) plays a crucial role in field-scale heterogeneous aquifers,
while the concept of micro-dispersion (resulting from velocity variation) decides the resultant transport of solutes to be either advective or dispersive dominant at the microscopic-scale.
In this context, while describing the transport of solutes in a fractured aquifer,
what happens to the concept of macro-dispersion,
if the transport of solutes is modeled
by ignoring the local-scale interaction between high-permeable fracture and low-permeable rock-matrix -  at the larger field-scale?
In fact, at the larger field-scale, it is quite possible that the magnitude of microscopic-dispersion within the fracture alone might be insignificant  - in comparison  - with that of the macroscopic-dispersion resulting from the coupled fracture-matrix interaction:
In turn, won't it affect the resultant direction and magnitude of plume spreading?
Suresh Kumar.
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Good thinking and questions. I would say that in real life the spatial variability in the fracture network properties matters a lot.  Without a good (!!) structural model most mathematical models are fruitless.
Prof. Dagan's theoretical work on media of limited variance in ln(K) can be applied to som extent for greater values of Var(ln(K)). Let me know if you needs references to read.
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Hopefully, I can find some one who knows the specific values of solute transport parameters in (m/sec) for sugar compounds (Sucrose, Glucose, fructose, malic acid and sorbitol) at the polyamide spiral wound reverse osmosis membrane ..?
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You can refer Table 1 and Table 3 in “Journal of Membrane Science 437 (2013) 72–81”. This article is related to Forward Osmosis. RO and FO are similar processes, thus you can use these values for RO simulations. The membrane reported in this article is cellulose triacetate not polyamide. Experiments were conducted on test cell, but solute permeability values do not depend on the module geometry. So you can use these values for spiral wound module simulations.
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For inserting multiple biological sample, the surface of substrate (glass) should be enough hydrophilic to avoid hydrophobicity by the residual effect of solutions. The case especially capillary flow system requires superhydrophilic surface. TiO2 can be irradiated to get the superhydrophilic surface but patterning on glass wafer seems to be difficult. Can any body give nice solution to it? It will be very much helpful for my research.
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We measure protein absorption on gold surface via imaging ellipsometry in a SPR cell with patterned surfaces (buffer solution).  So you can distinguish between the gold layer and the hydrophobis or hydrophilic pattern (depending on the end function of the silane/thiol you are using)
Best regards
Christian
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HYDRUS is based on finite element method which allows designing complicated mesh grids in triangular geometry, but Visual MODFLOW is based on finite difference technique and barely finite volume (e.g., TVD scheme) which allows designing only rectangular mesh grids. HYDRUS can simulate both saturated and unsaturated conditions with its core scheme, but the main models in Visual MODFLOW (MODLFW, MT3DMS, SEAWAT) are unable to simulate the unsaturated flow condition, although SEAWAT can simulate the variable density flow, e.g., saline water. HYDRUS can also consider the vadose zone, uptake of plant, infiltration and so forth. Visual MODFLOW links the groundwater transport models with surface water, e.g., through Mike 11. HYDRUS can optimize the parameters by its built-in Marquardt-Levenberg algorithm. Visual MODFLOW uses the WinPEST which can optimize the parameter with the same algorithm, but  by 2012 it was not possible to optimize most of the solute transport parameters by the software directly and you had to build the input files of WinPEST by yourself. HYDRUS has a demo version in public domain but Visual MODFLOW is free in full version only for one month. The most magnificent point about HYDRUS is that recently it has been applied and modified to simulate the colloid and nanoparticle transport in porous media with considering various phenomena of attachment, detachment, blocking, ripening, and straining. We recently modified MODFLOW too to simulate the transport of nanoparticles with considering the aggregation phenomena. 
Hope this helps
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Why Naringin solubility in water is low but solubility of this compound in aprotic solvent like THF and DMF is high? I wanna the reason of this phenomena from organic perspective.
Best regards
Mohammad
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Dear Mohamad,
Hydrophilicity of flavones increases with the number of free hydroxyl groups. Naringin, a flavonone glycoside, has only two free hydroxyl groups; the heterocyclic ring (the middle ring) does not possess a free hydroxyl group, which is found in quercetin, a flavonol with 5 free hydroxyl groups. The B-ring of naringin has a single free hydroxyl group. With its limited number of free hydroxyl groups, naringin possessing two phenolic (aromatic) rings, may partition better in lipid solvents (example,  methanol).  Flavonones possess low solubility in polar solvents. Generally, flavonoid glucosides are more soluble in water than their aglycones (free non-sugar derivatives).
The increase in solubility of the citrus flavonone, naringin, with the increase in temperature was not pronounced up to 45 degrees.
The solubility of naringin in water at 37 °C it was found to be only 1.9 μg per mL.  Complexation of naringin with the cyclic oligosaccharide,  beta-cyclodextrin, greatly increased its solubility in water.
Regards!
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One argued with me that solute transported by the capillary rise as advection. Can it really be? My counter argument was for media like clayey soils, the velocity of the capillary rise is much slower. So according to J=CV equation, in such media, dispersion should be dominant. 
What do you think?
Thanks in advance
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Andre is right. It is all a matter of the physical parameters of the problem. Capillary rise usually occurs due to a pressure jump on the interface, however the intensity of the Péclet number will inform which physical mechanism is more prominent: diffusion or advection.
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Aggregated Dead Zone for solute transport between two locations in a river system. at the sampling interval of 1 minute.
given the following expression:
xk = {1- (0.05+β )}xk-1 +0.05uk-δ.
In the above expression I need to eliminate the β in order to compute the response xk to a step input uk of the pollutant at a constant concentration of 15mg l.
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thanks adam, the β = 0.05 and δ = 2min assuming x0 = 0
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I want to calculate the structure of water on the surface of non-polar solute (not for bulk system). For this calculation I cannot use radial distribution curve (g(r)) method because there will be a break in the radial symmetry if I consider a shell around the solute and calculate g(r) of water inside that shell. For the particles which at the interface (boundary of the shell) we don't have radial symmetry. I dont want to use angle dependence for these calculations. Are there any other methods for finding the structure?
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Dear Jose, 
Glad to see your reply. 
First of all yes the structure of water non-polar solute is a bit different from that of bulk system. If you plot distribution of water around the solute (just upto a certain distance say first shell) then it will be much more enhanced as compared to bulk water. I can see such results in my system but the problem is calculating radial distribution curves is not a correct method because of the breakage of the radial symmetry for the particles which at the interface of the shell you are considering. So i want alternative method. 
Hope i am able to convey my problem.
shashank
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I am working on groundwater flow and solute transport modelling in an heterogeneous mufti-layered porous media in part of a sedimentary basin in Nigeria.
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ModelMuse can be used with MODFLOW and SUTRA for groundwater flow and solute transport using finite difference and finite element approaches. ModelMuse is available free on the USGS web site.