Arsenic - Science topic

Hi,

just add the following lines (also to AD4.1_bound.dat):

atom_par Na 3.98 0.030 12.000 -0.00110 0.0 0.0 0 -1 -1 1 # Sodium

atom_par As 4.23 0.309 13.000 -0.00110 0.0 0.0 0 -1 -1 1 # Arsenic

First; the matrix must be homogenized;

then perform an acid digestion and at the end the analysis, for details see this article

As to arsenic, I recommend the following publications (and references therein) that give a state-of-the-art insight in our knowledge of the effects of arsenic on health:

Kumar, A., Rahman, M.S., Ali, M. et al. Assessment of disease burden in the arsenic exposed population of Chapar village of Samastipur district, Bihar, India, and related mitigation initiative. Environ Sci Pollut Res 29, 27443–27459 (2022). https://doi.org/10.1007/s11356-021-18207-6

Mondal, D., Rahman, M.M., Suman, S., Sharma, P., Siddique, A.B., Rahman, M.A., Bari, A.S.M.F., Kumar, R., Bose, N., Singh, S.K., Ghosh, A., Polya, D.A., 2021. Arsenic exposure from food exceeds that from drinking water in endemic area of Bihar, India. Sci. Total Environ. 754 (2021), 142082. https://doi.org/10.1016/j.scitotenv.2020.142082

Contact me if you cannot access the papers.

hey, Kavya Bisaria, here is my answer

1) generally, it is of importance to know HOW you calculate equilibrium constants, and therefore, how do you calculate delta G;

2) I might suppose that equilibrium constants are taken as the Langmuir model affinities; albeit, the conceptual answer does not depend on the specific model;

3) In any case, adsorption equilibrium constants, as in any chemical reaction, depend on concentration units of reagents, which are, concentrations (feacrions, et cetera) cancelled (implicitly) in delta G calculations, by dividing equilibrium concentrations to the unit concentration in a reference state

4) equilibrium constants may be less than 1, of course. There is no any problem with that. Therefore, the free energy changes calculated may be positive. This means that the adsorption reaction would not occur spontaneously being performed between the reference states. If the Langmuir model affinity constant is found 0.1 L/mg (better converted to L/mol), this means that this reaction does not occur spontaneously, within the Langmuir adsorption reaction, between As in solution at its concentration of 1 mg/L (since you have used mg/L scale), an empty sorption site and a fully occupied sorption site. But, it will be spontaneous at many other conditions, for example, when there is a higher As concentrations. If adsorption is measured, it is obviously spontaneous. The sign of delta G makes sense only in relating to the reference states used for delta G definition. That is why indicating delta G values, and discussing their sign, and speculating regarding direction, often found in the literature, may be seen as mistaken. Changing concentration units will affect calculated delta G values, but, typically not enthalpies...

I have not worked on As bioaccumulation yet i think you may check out As conc. in the fish's feed as well as gut content. Maybe it will help you to come to a satisfactory conclusion

ICP-MS is the best option for speciation even at PPB level

Hi Aditya,

I recommend following the project Nature and nurture in arsenic induced toxicity of Bihar, India : UKIERI-DST Project on ResearchGate.

Also, Mahavir Cancer Sansthan & Research Centre (MCSRC) in Patna conducts very relevant research in the relation between cancer and arsenic intake. Check: https://www.mahavircancersansthan.com/contact%20us.html

Good luck with your research!

That depends on which statistical hypotheses you aim to test. After all, any hypothesis can be constructed as some linear combination of hypotheses of model coefficients from both models, as these are the same, just parametrized differently. So for instance it's rather complicated to test the strain:arsenic interactions in a oneway ANOVA but straight forward in a twoway ANOVA.

geogenic causes are the main cause of those contaminations in the groundwater. the sources of fluoride and arsenic are depends slightly on each other. generally, arsenic contamination depends on iron and manganese. the origin of arsenic and lead in groundwater is different. the health impacts of those individual metals are also different.

hi,

MIB is a binding site prediction and docking server for metal ions, and this server provides an accurate, integrated approach to search the residues in metal ion-binding sites using the fragment transformation method. (18) Predictions of residues that bind 12 types of metal ions are supported

Kindly refer this link:

Best wishes..

Tin forms a volatile/gaseous hydride under these conditions and my work, depending whether or not there are other interferences. It is worth noting that there may be interferences between selenium and arsenic in hydride based analyses.

Procedure for 1ppm solution: Dissolve 0.33 g of arsenic trioxide in 5 ml of 2M sodium hydroxide and dilute to 250 ml with water. Dilute 1 volume of this solution with 100 volumes of water.

Further dilute the solution to get your required 1-10 ppb solution. Hope this helps.

The binding of the arsenic aptamer is controversial. Check this paper for reference:

Has anyone used the MP-AES 4200 to analyze macros and micro nutrients in it. If so what was the total analyte amount there seem to be some opinions that say to add DI water to fill centrifuge tubes to 15 mL. And another that suggested to add to DI water to 10 mL to be able to dilute a second time to do second run.

Please check it.

No, by thermodinamical asprcts this effects takes place in the surface. One of the reasons why you have to optimize substrate temperature. Being its influence also in diffudion lenght searching for a proper place in the formind 2d layer. Hope is clear. A comprehensive analysis, for instance J. Y. Tsao "materials fundamentals of MBE" Ac. Press and MA. Hermann, H. Sitter "Moleecular Beam Epitaxi+y". Springer series in materials science.

"Wastewater: Sludge Removal & the Chemicals Used"

📷Wastewater treatment involves several key components: physical treatment (i.e. screening and filtering processes), biological treatment (i.e. oxidation ponds and lagoons), and chemicals. The chemicals required for water treatment must be used more aggressively and in larger quantities for wastewater than municipal drinking water. As such, safe, proper storage for wastewater treatment chemicals is critical.

There are five basic steps for the wastewater treatment process, each of which involves a set of common chemicals. The steps are as follows: removal of solid particles, neutralization, odor control, disinfection, and sludge treatment and removal. The following details sludge removal and the chemicals used in the process.

Wastewater treatment produces sludge in both on-site (i.e. septic tank) and off-site (i.e. activated sludge) systems. As wastewater treatment takes solids out of the wastewater, it is inevitable that there will be sludge remaining. Sludge characteristics can vary significantly from fairly fresh fecal materials, which contain large quantities of pathogens, to fecal matter that has decomposed over the course of the year, which contains much fewer pathogens, as many of them have already died off. The treatment required for the sludge is highly dependent on the specific characteristics.

Before sludge goes through its final disposal, it must be treated to bring down the volume and stabilize the organic materials. Stabilized sludge does not have a harsh smell and can be handled without risk of safety hazards. With a smaller volume, the costs for storing, pumping, and disposing of the sludge are less.

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There are various options for treating sludge including stabilization, thickening, dewatering, drying, and incineration. The costs for treating sludge and removing sludge from wastewater are roughly the same. Typically a polymer chemical is used for the volume reduction process known as dewatering. Polymers are slippery chemicals, which means that there is always a risk of slipping or falling due to spills and leaks. Polymers can also be environmental stress crack agents.

Dewatering decreases sludge liquid volume as much as 90 percent. Digested sludge is put through large centrifuges that work in the same fashion as a washing machine spin cycle. The spinning centrifuge produces a force that separates the majority of the water from the sludge solid, creating a biosolid substance. Then the water pulled from the spinning is sent back to the plant for reprocessing. Adding polymer chemical to the substance improves the consistency, creating a firmer product that is easier to manage. The biosolid cake consists of between 25 and 27 percent solid material.

A cross-linked polyethylene vertical tank design with an IMFO® system is optimal for sludge control polymers and offers simple, stress-free cleaning because the tank drains at the true bottom. The tank's cross-linked construction enables increased expansion and contraction while keeping structural integrity, decreasing the risk of tank failure. Heat pads and insulation can assist with keeping chemicals at the proper temperature, substantially decreasing the possibility of separation and settling. A mixing system can also be installed to reduce the incidence of chemical separation.

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Dear Raneesha, thank your for sharing this very intersting and important technical question on RG. In addition to the relevant link suggested by Chinaza Godswill Awuchi please also have a look at the following useful article which might help you in your analysis:

and

The first article has been posted by the authors as public full text on RG, so you can freely download it as pdf file. Please find attached a pdf file of the second paper.

Good luck with your work and best wishes, Frank Edelmann

Dear Nathalie , The best method for determining Arsenic along with other heavy and trace metals could be ICP-MS ,

Inductively coupled plasma-mass spectrometry (ICP-MS) is applicable to the determination of sub-µg/L concentrations of a large number of elements in water samples and in waste extracts or digests......

Please note that 6020B; in somehow developed the method of 6020 A!!!!!!

If Method 6020 is used to determine any analyte not listed in Sec. 1.2, it is the responsibility of the analyst to demonstrate the precision and bias of the method for the waste to be analyzed. The analyst must always monitor potential sources of interferences and take appropriate action to ensure data of known quality (see Sec. 9.0). Other elements and matrices may be analyzed by this method if performance is demonstrated for the analyte of interest, in the matrices of interest, at the concentration levels of interest in the same manner as the listed elements and matrices (see Sec. 9.0).

The best references are attached, although I know you have both!

Best wishes

Dear Kumar

Please read the following paper, it can help you hopefully!

Very well project! Bio-adsorbents from agricultural wastes are highly recommended, and the papers are available in Research Gate too!

Good Luck

Check https://www.who.int/news-room/fact-sheets/detail/arsenic

Dear Muhammad, this is a very interesting and important technical question. There are both natural and man-made sources of arsenic found in the environment. For the number of man-made compounds I do not yet have any reliable information. However, according to the link cited below the Earth's crust comprises more than 320 arsenic-containing natural minerals:

For more information about the origin of environmental arsenic please also have a look at the following useful link:

Yet another valuable source of information is the following article:

ARSENIC AND ARSENIC COMPOUNDS

Good luck with your work and best wishes, Frank Edelmann

I concur with Matthew Wheal. You might have to increase the amount of sample volume to be above the detection limit.

Rida Shakir Nagarajan Krishnan Just a comment to observe regarding activated charcoal: It is "activated" by incubating at high temeperature with a number of metals, amongst which could be As, so what looks like a "clean" wine has just been dosed with any number of metals (V, Cr, Al, Fe and a few more that I can't recall).

While red wine can interefere with interpretations of some visual tests (SO2, Sugar analysis etc), ICP and AAS analysis are very unlikely to be affected in this way.

In my routine ICPMS work, the colour of the wine makes very little difference to it's analysis, as the sample is heated to >5000K in the plasma. Any organic compounds that contribute to the colour are completely destroyed. Plenty of other matrix effects occur, but wine colour is not one of them.

Dear P. Ravikumar many thanks for your very interestingctechnical question. In fact, there are gender and age differences in the metabolism of toxic arsenic in the body. For more information about this please have a look at the following relevant study:

More general information about this problem can be found in the following article:

There is another interesting article which is freely available as public full text:

(see attached pdf file)

Kindly use ANOVA madam for various sites.

Saman... The hydride generation coupled with atomic absorption spectrophotometry is one of the most recommended technique for such purpose with promising detection limit. However, the LPG needs to be injected in an emulsion to ensure capturing of the hydrocarbon, followed by treatment with nitric acid addition to convert the As into an inorganic form that can be analyzed after phase separation. More details can be given...

First better to detect quantitatively any accumulation of Arsenic than perform analysis. For detection you need to use about 20-80mg of cells digestion in HNO3.

Almost all plant tissue contain metals. ICP technique is capable to detect the metals even in a lowest concentration.

I always used a 5% nickel nitrate/potassium persulfate solution (1% HNO3) for matrix stabilization of arsenic and selenium. It worked quite nicely. I used equal volumes of sample and matrix modifier and dried completely prior to ashing. Don't know your system so I can't tell you maximum temperature but I was able to ash at 1050 C (Hitachi Zeeman).

Drinking-water containg Arsenic increases the risks of cancer in the skin, lungs, bladder and kidney, as well as other skin changes such as hyperkeratosis and pigmentation changes.The effects on environments include death, inhibition of growth, photosynthesis and reproduction, and behavioral effects. Environments contaminated with arsenic contain only a few species and fewer numbers within species. If levels of arsenate are high enough, only resistant organisms, such as certain microbes, may be present. If arsenic poisoning occurs over a brief period of time, symptoms may include vomiting, abdominal pain, encephalopathy, and watery diarrhea that contains blood. Long-term exposure can result in thickening of the skin, darker skin, abdominal pain, diarrhea, heart disease, numbness, and cancer.

Tshivute Iipinge you may contact Dr Ibrahim A. Allamin in Nigeria for further advise as he did the experiment in our lab. Would be interesting to see the capability of this hardy plant to remediate the contaminated soil. In addition you can do metagenomic studies to see population shifts/succession.

I would suggest Phytoextraction but the most suitable technique would depend on a lot of site factors. You can refer to US EPA Technology Screening Matrix. That's a great tool to help you pin down the right remedial technology.

Good Luck!

Arsenic contamination and pollution of soils arises from the activities listed by Isa but also from agricultural activity - specifically the use of arsenical pesticides and herbicides. For example, it was common for cotton farmers in the USA to defoliate the cotton plants by spaying with arsenical herbicide (to make the leaves drop off) before machines could pick the cotton bolls. The As accumulated in soils and could poison other crops when grown in place of cotton: rice has straighthead disease if grown straight after cotton. Arsenic also has been known to accumulate in fruit orchards from the use of arsenical spray used as insecticides. Livestock dipping once used arsenical tickicides but in such cases pollution was highly localised around the dipping pens.

More diffuse loading of arsenic onto soils arises from the widespread use of arsenic-polluted groundwater for irrigation, a growing problem in deltaic regions, especially the Bengal basin.

As sort-of-in-between case was the spill of arsenic from a pesticide factory in Kolkata, India, in the 1980s that polluted groundwater under a large part of southern Kolkata - it had almost disappeared by 2018.

In Northern India, arsenic pollution of groundwater has a natural, not an anthropogenic, source and is driven by reduction of sedimentary iron oxides onto which arsenic was sorbed. Neither the source of arsenic, nor its mobilization, is connected in any way with volcanism.

Relevant articles to illustrate these points are on ReseachGate under my name.

The answer to the question depends on the location, age, and depth, of the sand you are refering to. In the Bengal Basin, As-pollution of groundwater occurs almost exclusively in the grey sands deposited in the last 18 ka (since the last glacial maximum or LGM for short) and not in deeper pre-LGM sands. The post-LGM grey sands once held iron oxides on which As was sorbed. The oxides have been dissolved and the As released to solution. In the upper 5 to 10 m of the the underlying pre-LGM sands, there is a lot more iron oxide, and little has dissolved, so the As remains sorbed to the oxides and groundwater in such sands is not polluted by As. Deeper pre-LGM sands are grey, but host unpolluted groundwater because all the As they used to contain (on deposition) has been flushed away by > 100 ka of groundwater flow.

So, to return to the question, brown sands have groundwater with < 10 ppb As, shallow (< 150m) grey sands SOMETIMES, not always) have groundwater that is polluted by As. Grey sands > 150m deep (and across many parts of the basin > 50m deep) are not polluted by As.

A better way to assess pollution in an area is to look at the colour of stain on the well, buckets used to transoprt water, or the concrete well-completion. Red stain indicated a possibility of As pollution. Black stain indicates no As, but Mn instead.

Further information on colour as a guide to arsenic pollution can be found in

McArthur J.M., Nath B., Banerjee D.M., Purohit R. and Grassineau N. (2011). Palaeosol control on groundwater flow and pollutant distribution: the example of arsenic. Environ. Sci. Technol., 45, 1376–1383. dx.doi.org/10.1021/es1032376.

The presence of pyrite in the sediments of the Bengal Basin has little to do with the arsenic pollution apart from lessening its severity marginally.

See P. Ravenscroft1,2, J.M. McArthur3* and B.A. Hoque4, 5 (2001). Geochemical and Palaeohydrological Controls on Pollution of Groundwater by Arsenic. In: Arsenic Exposure and Health Effects IV. W.R. Chappell, C.O. Abernathy & R. Calderon (Eds), p 53-78, Elsevier Science Ltd. Oxford.

Thank You Dr. Carsten Bahr for your guidance and support

@ Abdul, yes it can be as the therapeutic effect of arsenic trioxide was explored for the first time in a model of chronically SIV‐infected macaques. In combination with ART, arsenic trioxide can significantly reduce the viral reservoirs and delay viral rebound after ART termination in this macaque model. But the concentration should be below 10 ppb as the levels above 10 ppb will increase the risk of long-term or chronic health problems. The higher the level and length of exposure, the greater the risk.

Hi Chinaza.

Thank you for your contributions, but I am looking for an organic solvent that is suitable for extracting arsenic trichloride from an aqueous solution. Chloroform or benzene is used in the paper mentioned above but these have health risks. I am looking for a safer organic solvent.

Regards

In my opinion, to avoid precipitation and maintain or reduce of pH level.

Nasar Khan I am concerned about the interference with As and ArCl, hoping I can get more info regarding that issue.

Dear Shaw,

Have a look at these guidelines and reports:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4972851/#:~:text=Obtained%20results%20revealed%20that%20maximum,affected%20by%20geogenic%20arsenic%20contamination. https://cfpub.epa.gov/safewater/arsenic/arsenictradeshow/Pubs/handbook_arsenic_treatment-tech.pdf https://www.who.int/water_sanitation_health/publications/2011/9789241548151_ch12.pdf

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6210428/

https://www.ncbi.nlm.nih.gov/books/NBK442375/

https://www.hindawi.com/journals/jchem/2015/716125/

https://dnr.wi.gov/regulations/labcert/documents/training/basics-genchem.pdf

https://www.usbr.gov/research/dwpr/reportpdfs/report041.pdf

Since you're doing a spin-polarized calculation, the number of bands must be AT LEAST equal to the total number of electrons in the system, i.e. Sum(zval_i *number of atom type_i) where is the number of atomic species. If you use a smaller number (which seems to be the case here), your scf loop can never converge as it can not afford to generate enough electronic states to accommodate all the existing electrons.

In practice, you could do a quick test using no NBANDS in INCAR and a coarse k-mesh. From the output of this calculation, you will find the suggested value for NBANDS and also the real number of occupied bands (including partial ones). If you think this value is too large, you could then reduce it, but mind that in no circumstances it can be smaller than the number of occupied bands. Also, mind that if you do a parallel calculation NBANDS is automatically modified so that it will be divisible by the number of allocated cores.

As for parallelization, the simplest trick is to play with NPAR. It all depends on your machine, the number of cores in each node and the inter-node connections. In my case, I have found that for up to 128 cores distributed on 8 nodes, NPAR=4 performs the best.

Thanks S. Béatrice Marianne Ewalds-Kvist for your valued contribution.

Elevated contents of arsenic in the ground- and surface water in India and Bangladesh are first and foremost the result of a geogen process caused by oscillating redox conditions in one of the strongest tidal regimes on the globe the impact of which can be recognized for quite a long distance landward of the coastline. Contamination which is synonymous with pollution refer to each and every process be it anthropogenic or geogen making water undrinkable or unusable for all kinds of living beings by the addition of chemical substances and/ or changing the physical regime.

H.G.Dill

thank you so much for suggestions and sharing all these files.

I think it may be the problem with the VASP compilation or your memory allocation for that particular job. Try to decrease the number of cores and increase the memory per CPU in your script.

It's very easy to do.

1 - Look in the lithology table of your project for the lithocode you attributed to 'sand'.

2 - From your lithology model create a boolean model defining as true (1) the voxels with your sand lithocode value.

3 - Multiply the boolean model by your arsenic model. Take care: all you models must have the same dimensions. You're done !

Regards

Dear W. P. R. T. Perera

I fully agree with the opinion of Professor Frank T. Edelmann , Please find the attached paper which may give you further informations

Regards

Arsenic may harm to plants through the soil.

Dear Hamid,

You do not say with what accuracy and precision you require, so a full answer is not possible.

There are several good field-test kits, such as the Palintest's 'Arsenator', that give good semi-quantitative results and can be used in the lab perfectly well. Google 'Arsenator' or 'As field-test' for details.

There are colorimetric methods, such as the silver diethylthiocarbamate (AgDDTC) method. Although such methods have highish detection limits (typically a few tens of ppb) by using larger samples that can be lowered. Search for 'colourimetric (or colorimetric) As analysis'

Graphite-furnace AAS is a good direct method with detection limits (if my recall is correct - it's years since I used it) of a few ppb.

Most of us use ICP-MS, so it would be worthwhile your seeking a collaboration with someone near you that has one and (important) really knows how to use it. Getting numbers out of an ICP-MS is very easy; getting numbers for As that mean something is not.

ICP-MS is also OK if you want to speciate - you simply use an ion-exchange column to remove As(V) and measure the remaining As(III), whilst also measuring total As on a separte subsample. It doubles the cost and more than doubles the time needed, but it works.

John McArthur

Thank you Dr Cross to provide me some information. While looking for arsenic removal using RO technique I have already gone through 2 theses, one as mentioned by you and the other one an engineering thesis. I came to know that As (V) is mainly remained in higher pH range. For quantitative removal of As from potable water As(III) is preferably converted to As(V) which can be quantitatively removed by using RO technique. The salt bearing As(V) is mostly dissociated to ionic form. The ionic salts are preferably retained in functional active layer of RO permitting water to pass through it. Hence about 98% arsenic is removed by RO. In case of As (III) form it remained mostly in neutral molecule form where dissociation to ionic species is much less due to its high pKa value. In that case the pore size of neutral molecule is less than that of functional layer of RO . Hence it is easily passed through without removal. If it is so how 55 to 80% of As(III) is retained through RO? (as mentioned in literature). Hence my question is what is the chemistry behind removal of As through RO?

Please go through the following RG links.

Please go through the following RG links.

Thank you so much for help.

to preserve the water samples for analyzing the arsenic , the preservation method depending on what arsenic species do you want to analysis . If you want to determine total arsenic compounds you can acidification the water samples ( 5 ml con. HNO3/L) for two months , while when you want to determine arsenicas as dissolved and as particulate in water you cannot acidification.

with pest wishes

I am understanding that you may be doing an As/P competition study in acidic soil. Is that correct?

Is it entirely in the lab without biota or will you measure some 'biotic availability' ?

If it's chemistry only in the lab do you in fact want to suppress biotic activity?

These factors are important in deciding what to do and how.

The next paper focused on :The Effects of Heavy Metals on Aquatic Animals and its mechanism , hope it can help

Using buffer solution, you can get the desired pH.

NCS chitosan nano can be used. The following paper can help you:

"REMOVAL OF FE (II) AND MN (II) FROM WASTEWATER USING NANOCHITOSAN

PREPARED FROM SHRIMP WASTE"

I am not sure this is the best, but I would advise immediate liming of affected area to increase soil pH and help precipitate heavy metal contaminants and hold them in place, so you may have more time to figure this out what to do before groundwater gets contaminated. Rain is typically acidic, and the low pH helps to dissolve and mobilize heavy metals. Hopefully you might find or build toxic material containment site, where excavated contaminated soils can be deposited, contained, and managed for breakdown. There might be some ways to recover some types of contaminants, such as recovering lead from gun ranges. Hiring an individual or company trained in evaluating and handling hazardous materials as well as addressing the needs for monitoring is another option to address urgent issues. A proper mining plan should have been required, with performance bond, emergency spill plans when mining companies plan to use hazardous materials, build containment ponds (that fail sometimes), intend to use and store hazardous materials, etc.

Hi Mohamad Mirazimi,

I think the surface potential of As2S3 is relatively lower (more negative) than the equilibrium potential of O2/H2O redox potential under applied conditions. Without solids the ORP value of the leach solution is controlled by the dissolved oxygen and may be higher than the ORP with solids i.e. As2S3. This clearly states the oxidation of sulfide sulfur species to high oxidation state species at the surface facilitated by the reduction of dissolved oxygen. In other words, the ORP would lie in between the O2/H2O redox potential and surface potential of As2S3. In other words, the resulting ORP after addition of solids would be lower than the O2/H2O but higher than the surface potential of As2S3 (meaning oxidation of As2S3). But in this case, the large decrease in ORP corresponds to the dissolution controlled by the supply of oxidizing species (here dissolved O2). The formation of hydroxide species is obvious but the overall charge will remain neutral. Otherwise, this may significantly influence the pH at the surface, which I assume is not the case here under applied conditions.

Thanks anna Vinesh .V

simple equation is used here

VI = MF*VF/MI

VI= intional volume

VF= final volume

MI = intional mass

MF= final mass

In case of groundwater, arsenic concentration varies with different aquifer dissolution from Fe and Mn complexes and different lithologic compositions might play an important role in correlation between Fe and Mn towards As in groundwater. Please go through the below given article (sorry for the inconvenience as the article is in two parts) where it has been stated clearly with evidence-

Due to unique physical properties of activated carbon,, so many solids, gaseous and dissolved substances are trapped through adsorption, occlusion and precipitation. Contaminated activated carbon implies the decreased level of all these properties and almost in saturated level or deactivated . As a result, this deactivated carbon can not remove any contaminants from water instead it may contaminate the treated water through release of so many contaminants may be through displacement reactions ,already present or by slipping. Hence, contaminated activated carbon must be reactivated by removing those contaminants and then could be used.

yes it can be known@ Ruediger Buchkremer . I am reproducing details from a article by Das NK, Sengupta SR {Arsenicosis: Diagnosis and treatment. Indian J Dermatol Venereol Leprol [serial online] 2008 [cited 2019 Jul 16];74:571-81. Available from: http://www.ijdvl.com/text.asp?2008/74/6/571/45098} for Diagnosis of arsenicosis relies on both clinical and laboratory criteria, but principally it can be diagnosed on the basis of its cutaneous manifestations. Cutaneous manifestations (melanosis, keratosis, and cutaneous cancers) are essential clues in the diagnosis, and trained dermatologists or arsenic experts are able to clinically confirm a case even without laboratory backup. Although systemic manifestations are not considered as diagnostic hallmarks, yet their presence serves as important telltale signs in arriving at the diagnosis. In countries where laboratory facilities are available, measuring the level of arsenic in drinking water (consumed in the last 6 months), urine, hair, and nails is of immense value. Newer biomarkers of arsenic exposure are being explored to provide early information about arsenic intoxication, of which urinary porphyrin level, blood metallothionein have shown promising results. Controlling the problem of arsenicosis depends on various factors, of which the most important is cessation of intake of arsenic-contaminated water. Deep wells, traditional dug wells, treatment of surface water, rainwater harvesting, and removing arsenic from the contaminated water by arsenic removal plant or arsenic treatment unit are the available options for providing arsenic-free drinking water. The role of nutrition and antioxidants in preventing the onset of symptoms of arsenicosis is also of importance. Nonspecific therapies (e.g., keratolytics for hyperkeratosis) cannot also be ignored and serve as palliative measures. The persons affected need to be followed up at regular intervals to detect the onset of cancers (if any) at the earliest. Role of counseling and education should never be underestimated since absence of public awareness can undermine all efforts of mitigation measures.

One study it and conclude after going through this paper.

This basically suggest that your Si RNA is primarily targeting KEAP-1, by lowering the expression of KEAP1, the level of NRF2 will automatically be lowered due to lowering of ubiquitination and subsequent proteolysis of NRF2.

Or

If your Si RNA is very specific to NRF2, lowering of NRF2 is downregulating KEAP1, that is possible as its main action is to help NRF2 stay in cytoplasm.

Did you look at expression of IL6, IL10 and TNF alpha? Thats what is ultimately desired.

I will suggest you also look at NF-kB, and HO1

There are two source of Arsenic either natural or Anthropogenic.

You can use these recommended limits

You need to understand and look up Eh-pH diagrams for uranium, iron, and arsenate as their speciation and aqueous solubility are dependent on the redox state and the pH of the water. For example, iron as a mineral in the aquifer matrix is present as Fe(III), which is insoluble. Under low redox conditions, Fe(III) reduces to Fe(II) cation, thereby becoming far more soluble in water. Uranium and Arsenic typically form oxyanions and should have some correlation....but you will still need to look at the differences in their Eh-pH diagrams to understand which species are present under different solution conditions.

Thanks for sharing information.

HACH makes a low and high range Arsenic test kit which is fairly inexpensive.

Low range kit (0-500 ppb As):

https://www.hach.com/arsenic-low-range-test-kit/product?id=7640217303&callback=qs

High range test kit (0-4000 ppb As):

https://www.hach.com/ez-arsenic-high-range-test-kit/product?id=7640217305&callback=qs

each kit allows for 100 test to be performed

An alternative method is to utilize a rapid colorimetric method for measuring arsenic. A good paper is by Dhar et al., 2004, A rapid colorimetric method for measuring arsenic concentrations in groundwater, Analytical chimica Acta, 526, pp 203-209.

https://www.ldeo.columbia.edu/~avangeen/pdf/Dhar_ACA_04.pdf

https://medlineplus.gov › Medical Tests

Hi Sachin Seth

Could you clarify what you mean by react vigorously? My initial inclination is to say a variety of oxidizing agents (many of which are used in water treatment) can react with As(III) to convert it to As(V), which carries a charge and can be removed with filtration technology.

In terms of adsoprtion, my own work with As suggests that dissolved organic matter, humic acids and fulvic acids carry a variety of functional groups that can bind to arsenic, making it less bioavailable (although it can be more bioavailable depending on binding time). I am in agreement with Leonardo Pantoja Munoz with regards to iron hydroxides that play an important role in controlling As mobility (particularly given that As tends to exist as arsenopyrite in the Earth's crust).

Many compounds that bind strongly to phosphate can also interact strongly with arsenic given that they have very similar chemistry, this is in part why As is toxic because it can easily target DNA.

I hope this was helpful, happy to continue answering questions in this thread if need be.

Daniel